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EUROPEAN ORGANISATION FOR NUCLEAR RESEARCH (CERN)

October 4, 2017

Status report to the proposal SPSC-P-330

Report from the NA61/SHINE experimentat the CERN SPS

The NA61/SHINE Collaboration

This document reports on the status of the NA61/SHINE experiment at the CERN SPS as ofOctober 2017. The beam request for 2018 is also given.

c© 2017 CERN for the benefit of the NA61/SHINE Collaboration.Reproduction of this article or parts of it is allowed as specified in the CC-BY-4.0 license.

Contents

1. Introduction 4

2. Data-taking Summary 4

3. Summary of Facility modifications 53.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4. Forward-TPCs 7

5. Vertex Detector 85.1. Test measurements in December 2016 . . . . . . . . . . . . . . . . . . . . . . . . . . . 85.2. Data reconstruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95.3. Reconstruction of the D0 signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

6. Projectile Spectator Detector 156.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156.2. Upgrade of PSD read-out electronics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

7. Software and calibration modifications 17

8. New Results 188.1. New results for strong interactions physics . . . . . . . . . . . . . . . . . . . . . . . . . 188.2. New results for neutrino physics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 318.3. New results for cosmic-ray physics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

9. Data-taking Plan 40

10. Summary 42

11. Published papers and preliminary results 4511.1. Published papers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4511.2. Submitted papers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4511.3. New preliminary results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

A. Details on Vertex Detector 46A.1. Shine data structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46A.2. Readout upgrade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46A.3. SAVD geometry tuning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48A.4. Matching between SAVD and TPC tracks . . . . . . . . . . . . . . . . . . . . . . . . . 50

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The NA61/SHINE Collaboration

A. Aduszkiewicz 16, Y. Ali 13, E.V. Andronov 22, T. Anticic 3, B. Baatar 20, M. Baszczyk 14, S. Bhosale 11,A. Blondel 25, M. Bogomilov 2, A. Brandin 21, A. Bravar 25, W. Brylinski 18, J. Brzychczyk 13,S.A. Bunyatov 20, O. Busygina 19, A. Bzdak 14, H. Cherif 7, M. Cirkovic 23, T. Czopowicz 18,A. Damyanova 25, N. Davis 11, M. Deveaux 7, P. von Doetinchem 30, W. Dominik 16, P. Dorosz 14,J. Dumarchez 4, A. Datta 30, R. Engel 5, A. Ereditato 24, G.A. Feofilov 22, Z. Fodor 8,17, C. Francois 24,A. Garibov 1, M. Gazdzicki 7,10, M. Golubeva 19, K. Grebieszkow 18, F. Guber 19, A. Haesler 25,A.E. Hervé 5, J. Hylen 26, S.N. Igolkin 22, A. Ivashkin 19, S.R. Johnson 28, K. Kadija 3, E. Kaptur 15,M. Kiełbowicz 11, V.A. Kireyeu 20, V. Klochkov 7, V.I. Kolesnikov 20, D. Kolev 2, A. Korzenev 25,V.N. Kovalenko 22, K. Kowalik 12, S. Kowalski 15, M. Koziel 7, A. Krasnoperov 20, W. Kucewicz 14,M. Kuich 16, A. Kurepin 19, D. Larsen 13, A. László 8, T.V. Lazareva 22, M. Lewicki 17, B. Lundberg 26,B. Łysakowski 15, V.V. Lyubushkin 20, M. Mackowiak-Pawłowska 18, B. Maksiak 18, A.I. Malakhov 20,D. Manic 23, A. Marchionni 26, A. Marcinek 11, A.D. Marino 28, K. Marton 8, H.-J. Mathes 5,T. Matulewicz 16, V. Matveev 20, G.L. Melkumov 20, A.O. Merzlaya 22, B. Messerly 29, Ł. Mik 14,G.B. Mills 27, S. Morozov 19,21, S. Mrówczynski 10, Y. Nagai 28, M. Naskret 17, V. Ozvenchuk 11,V. Paolone 29, M. Pavin 4,3, O. Petukhov 19,21, C. Pistillo 24, R. Płaneta 13, P. Podlaski 16, B.A. Popov 20,4,M. Posiadała 16, R.R. Prado 5, S. Puławski 15, J. Puzovic 23, R. Rameika 26, W. Rauch 6, M. Ravonel 25,R. Renfordt 7, E. Richter-Was 13, D. Röhrich 9, E. Rondio 12, M. Roth 5, B.T. Rumberger 28,A. Rustamov 1,7, M. Rybczynski 10, A. Rybicki 11, A. Sadovsky 19, K. Schmidt 15, I. Selyuzhenkov 21,A.Yu. Seryakov 22, P. Seyboth 10, M. Słodkowski 18, A. Snoch 7, P. Staszel 13, G. Stefanek 10,J. Stepaniak 12, M. Strikhanov 21, H. Ströbele 7, A. Shukla 30, T. Šuša 3, A. Taranenko 21, A. Tefelska 18,D. Tefelski 18, V. Tereshchenko 20, A. Toia 7, R. Tsenov 2, L. Turko 17, R. Ulrich 5, M. Unger 5,F.F. Valiev 22, D. Veberic 5, V.V. Vechernin 22, M. Walewski 16, A. Wickremasinghe 29, C. Wilkinson 24,Z. Włodarczyk 10, A. Wojtaszek-Szwarc 10, O. Wyszynski 13, L. Zambelli 4, E.D. Zimmerman 28, andR. Zwaska 26

1 National Nuclear Research Center, Baku, Azerbaijan2 Faculty of Physics, University of Sofia, Sofia, Bulgaria3 Ruder Boškovic Institute, Zagreb, Croatia4 LPNHE, University of Paris VI and VII, Paris, France5 Karlsruhe Institute of Technology, Karlsruhe, Ger-many6 Fachhochschule Frankfurt, Frankfurt, Germany7 University of Frankfurt, Frankfurt, Germany8 Wigner Research Centre for Physics of the HungarianAcademy of Sciences, Budapest, Hungary9 University of Bergen, Bergen, Norway10 Jan Kochanowski University in Kielce, Poland11 H. Niewodniczanski Institute of Nuclear Physics ofthe Polish Academy of Sciences, Kraków, Poland12 National Centre for Nuclear Research, Warsaw,Poland13 Jagiellonian University, Cracow, Poland14 AGH - University of Science and Technology, Cra-cow, Poland

15 University of Silesia, Katowice, Poland16 University of Warsaw, Warsaw, Poland17 University of Wrocław, Wrocław, Poland18 Warsaw University of Technology, Warsaw, Poland19 Institute for Nuclear Research, Moscow, Russia20 Joint Institute for Nuclear Research, Dubna, Russia21 National Research Nuclear University (Moscow En-gineering Physics Institute), Moscow, Russia22 St. Petersburg State University, St. Petersburg, Russia23 University of Belgrade, Belgrade, Serbia24 University of Bern, Bern, Switzerland25 University of Geneva, Geneva, Switzerland26 Fermilab, Batavia, USA27 Los Alamos National Laboratory, Los Alamos, USA28 University of Colorado, Boulder, USA29 University of Pittsburgh, Pittsburgh, USA30 University of Hawaii at Manoa, Honolulu, USA

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1. Introduction

This NA61 annual report presents briefly the status and plans of the NA61/SHINE experiment [1] at theCERN SPS. The report refers to the period October 2016 – October 2017.

The document is organized as follows. The data taking summary is given in Section 2. Detector upgradesand maintenance are listed in Sec. 3. New detectors, the Forward-TPCs and Vertex Detector, are presentedseparately in Secs. 4 and 5. Software and calibration upgrades are listed in Sec. 7. New results are brieflyreviewed in Sec. 8. Finally, the beam request for data taking in 2018 is presented in Sec. 9. It includes anew request for a test on light ion fragmentation that requires a primary Pb beam. This request is justifiedin Addendum [2] submitted to the SPSC in parallel to this document. The summary in Sec. 10 closes thereport.

A proposal to extend the NA61/SHINE physics programme for the period between Long Shutdown 2and 3 is under preparation and will be submitted to the SPSC within the coming months.

2. Data-taking Summary

The data taking in summer and autumn of 2016 was devoted to reactions scheduled in 2015 but whichwere impossible to register with full detector due to the failure of the magnets in September 2015.

Between September and October 2016 data for the Fermilab neutrino beam programme were taken asscheduled. Table 1 lists the recorded reactions together with the number of registered events.

Table 1: Data collected between September and October 2016 for the Fermilab neutrino beam programme.

beam target beam momentum number of events

π+ C 60 GeV/c 2.6Mp C 120 GeV/c 4.1Mp Al 60 GeV/c 3.2Mp Be 60 GeV/c 2.2Mπ+ Be 60 GeV/c 2.7Mp Be 120 GeV/c 2.5M

In October and November 2016 data were recorded with an attenuated primary proton beam of 400 GeV/cmomentum. Large statistics of 9.5 million events of p+p interactions at beam momentum of 400 GeV/cwere collected.

In November and December 2016 heavy ion data taking took place. Data on Pb+Pb interactions at13A, 30A, and 150A GeV/c were recorded. The data at the two lower beam momenta were taken withfocus on collective flow studies. The data at 150A GeV/c were registered to test a newly constructedSmall Acceptance Vertex Detector with the additional optimistic aim to detect a signal of D0 mesons.

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Table 2: Data collected in November and December 2016 for the heavy ion programme.


Pb Pb 13A GeV/c 2.9MPb Pb 30AA GeV/c 5.7MPb Pb 150AA GeV/c 1.6M

Concurrently with this data taking a test of Alpide CMOS pixel sensors was performed together with theALICE ITS group. Table 2 lists the recorded reactions together with the number of registered events.

Data taking in 2017 started with a PSD calibration run on June 18th. Then at the end of June 5.2 millionevents of p+Pb interactions at 30 GeV/c beam momenta were registered.

In July 2017 installation and beam tests of the FTPCs were performed.

In August 2017 data taking for Fermilab neutrino beam programme was continued with the newly in-stalled FTPCs. Table 3 lists the recorded reactions together with the number of registered events.

Table 3: Data collected in August 2017 for Fermilab neutrino beam programme.


π+ Al 60 GeV/c 2.6Mπ+ C 30 GeV/c 2.2Mπ− C 60 GeV/c 3.6Mp C 120 GeV/c 2.6Mp Be 120 GeV/c 4.0Mp C 90 GeV/c 3.4M

3. Summary of Facility modifications

3.1. Overview

Within the past 12 months the facility upgrades and maintenance listed below were performed. Thepresent layout of the detector system is shown in Fig. 1.

(i) Forward TPC installation and commissioning. Three Time Projection Chambers (FTPC-1/2/3)were designed to close the gap in the forward acceptance. Together with the existing GAP TPC theyprovide momentum reconstruction and particle identification by the ionisation energy loss measure-ment. Despite being placed directly on the beam trajectory off-time beam particles can be identified

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~13 m

ToF-L

ToF-R

ToF-F

MTPC-R

MTPC-L

VTPC-2VTPC-1

Vertex magnets

Target

GAPTPC

Beam

S4 S5

S2S1

BPD-1 BPD-2 BPD-3

V1 V1V0THCCEDAR

z

x

y

p

SAVD

FTPC-1

FTPC-2/3

PSD

Figure 1: NA61/SHINE detector layout as of October 2017, horizontal cut, not to scale [3]. It includes new VertexDetector, Forward TPCs 1, 2, and 3, and four reinstalled ToF-F modules.

and removed off-line thanks to the innovative design of alternating drift directions. In spring 2017the detectors were assembled at CERN, installed in the NA61/SHINE facility and commissionedon beam in July. The detectors were successfully used during the data taking campaign for theFermilab neutrino beam programme in August–September. For more details see Sec. 4.

(ii) Small Acceptance Vertex Detector (SAVD) tests. The completed SAVD with readout integratedwith the NA61/SHINE central DAQ was tested in beam during the Pb+Pb data taking period inDecember 2016. The reconstruction and calibration algorithms were optimized based on the data.For more details see Sec. 5, which includes first indications for the D0 peak reconstruction.

(iii) Forward Time of Flight with DRS4 based readout. Four (out of ten) existing ToF-F moduleswere installed behind the MTPCs, covering the gap between FTPC-2/3 and ToF-L/R. Signals from64 photo-multipliers were read with new DRS4 boards. The system was configured during the datataking campaign and used during measurements with the 90 and 120 GeV/c beams in August.

(iv) Projectile Spectator Detector maintenance. The detector was calibrated in June 2017 and pre-pared for operation, in particular for the Xe+La data taking. For more details see Sec. 6.

(v) Beam Position Detector electronics upgrade. In 2016 the quality of the signals from the BPDsdeteriorated probably due to a new source of electromagnetic noise in the experimental area. InJuly 2017 the problem was fixed by replacement of the low voltage distribution cables and an im-proved grounding scheme. Meanwhile analysis techniques are being refined in order to improve thereconstruction efficiency of the already collected data.

(vi) Chiller for TPC FEE cooling. The TPC FEE operation is very sensitive to unavoidable instabil-ities of the CERN chilled water network. The EN-CV-DC group proposed to use our own chillerproviding an independent source of chilled water. A 9 kW chiller was installed in 2016, but it turned

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out the required power was underestimated. A new 25 kW chiller was installed in September 2017and is supposed to be ready for the autumn runs this year.

4. Forward-TPCs

In the past year, the Forward-TPC (FTPC) project was completed and the chambers used in the August-September physics run. These chambers are intended to allow the measurement of secondary protons inthe moderate- to high-xF region. These protons are responsible for a significant fraction of the νµ flux inthe NuMI beam, and likely a comparable fraction in the LBNF/DUNE beam. A secondary goal of thesystem is to measure the high-momentum part of the π+ production.

The NA61/SHINE detector was designed primarily to track particles that bend out of the beam; onlyone small tracking detector, the GAP-TPC, covered the forward region. We have added three TPCs, oneimmediately upstream and two immediately downstream of the MTPCs. The new TPCs have a readoutplane geometry based largely on the existing NA61/SHINE TPCs, and use previously existing spareelectronics. However, to minimize material upstream of the main TPCs, the FTPCs were designed with alight plastic superstructure and a printed kapton field cage instead of a heavier fiberglass frame supportingtensioned mylar strips as in the other NA61/SHINE TPCs. The FTPCs are important for future protonbeam data for NA61/SHINE’s strong interaction physics programme, but FTPC-1 is designed to be movedout of the beam during heavy ion operation. Higher-rate running conditions are expected to generateenough tracks in the beam region so that out-of-time tracks may produce significant backgrounds. Out-of-time tracks are reconstructed as spatially displaced tracks. In order to reject these tracks, successive fieldcages have opposite drift directions so out-of-time tracks will appear unconnected at chamber boundaries.This “tandem TPC” concept originated with the Budapest group and has been implemented for the firsttime here.

This project was a collaboration between Colorado, the Wigner Institute in Budapest, and Warsaw Univer-sity. Colorado designed the chamber, procured, machined, and shipped the components. The wire frameswere wound in Budapest. Colorado and Wigner Institute personnel assembled the field cage at CERN,and then attached the modular wire frames after they were delivered from Hungary. The Colorado group

Figure 2: A proton interaction event in the 2017 NA61/SHINE data. The new FTPCs are outlined in orange, andthe green hits in them represent a track that passes through all three chambers. Grey hits are out of time tracks ornoise hits.

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was responsible for organizing the installation of the chambers, while Wigner and Colorado personneltested and connected the electronics. The gas system was built by the Warsaw group.

The chambers were installed in 2016-17 and were fully operational during the 2017 neutrino-related dataruns. An event display is shown in Fig. 2. Reconstruction software is being developed as part of the newShine software framework (Sec. 7).

5. Vertex Detector

Construction of a high resolution vertex detector was mostly motivated by the importance and the pos-sibility of the first direct measurements of open charm meson production in heavy ion collisions at SPSenergies. The decision was made to start with a limited acceptance version of the detector, named theSmall Acceptance Vertex Detector (SAVD). This device will, however, already cover 35% of the accep-tance of the final version which is foreseen to operate beyond 2020. The constructed SAVD is based onMIMOSA-26AHR sensors developed in IPHC Strasbourg.

The first test of a single MIMOSA-26AHR sensor was performed in November 2016 using a Pb beam of30A GeV/c. The main motivation of this measurement was to test the proper functioning of the MIMOSA-26AHR sensor in a heavy ion beam. In July 2016 the test of a single SAVD arm (8 sensors) was performedwith p+Pb reactions at a proton beam momentum of 150 GeV/c. The test and the obtained results weredescribed in the NA61/SHINE Status Report 2016 [4] in Appendix A. The July results allowed to validatethe basic concept of the intended measurements using the SAVD, namely proper data synchronization andthe ability of precise tracking and primary vertex reconstruction were demonstrated. Appendix A of StatusReport 2016 also describes the procedure of the sensor geometry reconstruction (geometry tuning), whichwas then used to reconstruct the sensor geometry in the July 2016 data.

5.1. Test measurements in December 2016

In December 2016 a test of the completed version (16 sensors) of the SAVD was performed with Pb+Pbreactions at 150A GeV/c. The main upgrades of the device, as compared to the version used in July,include:

• addition of the second detection arm,

• integration of the piezo-motors with the SAVD arms and the target holder providing independentremote control for arms and target in the horizontal direction.

• extension of the readout-system to the full 16 sensor system, in parallel to TRBv3 board firmwaremodification (see Appendix A in Status Report 2016).

The main goal of the test was to prove precise tracking in the large track multiplicity environment, demon-strate the ability of precise primary vertex reconstruction and eventually to reconstruct a D0 signal fromthe collected data.

A picture of the inner part of the completed detector is shown in Fig. 3. One can see vertically orientedcarbon fiber ladders with MIMOSA-26 sensors installed in their centres as well as the Pb target of 1 mmthickness located about 50 mm upstream from the first SAVD station (Vds1).

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Figure 3: Photograph of the SAVD taken during preparations for the test run in December 2016 before closing thedetector with the front and exit windows. The installed target is well visible in front of the Vds1 station.

The detector was installed in the beam on the 5th of December. The first period of beam was usedto perform integration of the low level SAVD DAQ with the central experimental DAQ system. Theintegration was successfully accomplished on the 7th of December. After that data were continuouslyrecorded for 5 days till the end of the Pb run period. During that time 728k minimum bias and 494k of the20% Pb+Pb collision with the smallest PSD energy (central collisions) at 150A GeV/c beam momentumwere collected.

5.2. Data reconstruction

As indicated in Appendix A.1 of Ref. [4] the first step of data reconstruction is cluster recognition. Theclusters of fired pixels are generated by the charged particles passing through the sensors and can becombined to particle hits in a given sensor. Before track reconstruction one needs to apply the sensorgeometry tuning procedure which was described in detail in Appendix A.1 of Ref. [4]. The geometrytuning is performed independently for the Jura and Saleve arms. The names were given to the SAVD armsaccording to the standard NA61/SHINE convention: the Jura arm is located on the Jura Mountains sidewheras the Saleve arm is located on the Mont Saleve side of the beam. The tuning procedure determinesrelative rotations and positions of the sensors in the arms. It is essential for efficient track reconstructionin both arms.

Track reconstruction is done iteratively. The first step uses a straight line track model. The reconstructionprocedure is based on checking all possible hit combinations. If the hits detected in different SAVDstations lie on a straight line according to the χ2 criterion, the combination is accepted as a reconstructedtrack. This procedure is called the combinatorial method. After this first iteration it was possible toimprove the geometry tuning by developing a dedicated procedure based on the MIGRAD minimiserfrom the MINUIT package. This procedure and the improvements due to its application are described inAppendix A.3.

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Figure 4: Distributions of cluster deviations devx (left) and devy (right) from a straight line track fit for a givensensor combination (see text) after fine tuning of the sensor geometry.

Track reconstruction by the combinatorial method was first performed on the data taken with zero mag-netic field. Figure 4 displays distributions of the cluster deviations from the fitted straight line in thehorizontal (devx (left)) and vertical (devy (right)) directions. The width of these distributions describesthe level of non-collinearity of hits associated to a given track (refer to Appendix A.3 for devx and devydefinitions). From these distributions one can derive the effective spatial resolution of a single sensor.Assuming that the resolution is the same for each sensor and taking into account the definitions of devx

and devy one obtains that

σx/y =

√23σdevx/y ,

where σx and σy denote the spatial sensor resolution in x and y direction, respectively. From the Gaussianfits represented by solid the lines in Fig. 4, one obtains σx = 4.7 µm and σy = 5.0 µm.

It turns out, that the same combinatorial method can also be applied successfully to reconstruct tracksfrom regular physics runs taken with magnetic fields on. It was, however, observed that using the straightline track model the hits in the third and forth station visibly deviate from the fitted straight line. Theresult is a double peak structure in the distribution of cluster deviations for the x direction rather than asingle peak. This effect is caused by the non-zero By component of the magnetic field. Therefore thex positions of hits were fitted using a second order polynomial function for matching SAVD and TPCtracks.

For primary vertex reconstruction tracks were described by the following simpler 3D line parametriza-tion:

x(z) = A z + x0

y(z) = B z + y0

The primary vertex is defined as the point of the closest convergence of all reconstructed tracks. Thus,the longitudinal coordinate zprim of the primary vertex is found by minimizing the expression:

D(z) =∑i< j

(Aiz + x0

i − A jz − x0j )

2 + (Biz + y0i − B jz − y0

j)2

which describes the sum of the relative distances of all track pairs reconstructed in a single event at the

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given transverse plane defined by the longitudinal coordinate z. The transverse vertex coordinates xprim

and yprim are then calculated as the average of track positions x and y at z = zprim.

Independent reconstruction of primary vertices using Jura and Saleve arms allowed to find the relativeposition of the arms, and eventually to describe their position in a common coordinate system. After thetransformation of the arms to the common system it is possible to reconstruct the primary vertex using alltracks measured in both arms.

Figure 5: Top-left: distribution of the longitudinal coordinate zprim of primary vertices for two samples of tracks(see text). Top-right: distribution of zprim for tracks produced in the target. Bottom: distributions of differencesbetween x, y and z coordinates of the primary vertices reconstructed using subevent1 and subevent2 tracks (see textfor details).

The results of this procedure are presented in Fig. 5. The top left panel shows the distribution of thelongitudinal primary vertex positions, zprim. It is seen, that the distribution consists of 3 component. Thefirst is a narrow spike (blue) located about 49 mm upstream of the first SAVD station and is associatedwith particles produced by interactions in the target. The second component shows a relatively smoothdistribution upstream of the target (red) which extends from about −50 mm (near the target) to about−1200 mm (exit from the H2 beam line). A third feature of the distribution at −190 mm is a sharp peakwhich is caused by interactions in the aluminized Mylar front window of the SAVD. One can also seethat upstream of the window the frequency of interactions drops by a factor of 5. This drop is due to thefilling with helium gas of the SAVD box volume. The components of the zprim distribution associated withinteractions in the target and with interactions outside the target can be well separated as the respectivetracks can be discriminated by applying cuts on the track x-slope.

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The top-right panel of Fig. 5 shows the distribution of zprim in the target region. The near rectangularshape of the distribution allows to reconstruct the target width (= 1 mm) and provides precise informationon the target location with respect to the front face of the Vds1 station.

In order to determine the spatial accuracy of primary vertex reconstruction, SAVD tracks from an eventwere split into two non-overlapping sub-events, namely every second track from Jura and Saleve arms wasassigned to subevent1, wheres the remaining tracks were assigned to subevent2. In this way one obtainstwo equivalent track samples and the primary vertex spatial resolutions obtained with subevent1 andsubevent2 are expected to be identical. The bottom panel of Fig. 5 shows the distributions of differencesbetween x, y and z coordinates of the primary vertices reconstructed using subevent1 and subevent2 tracks.One can see that the distributions can be well described by Gaussians with σ of 10 µm, 3.5 µm and 60 µmin the x, y and z direction respectively. The observed widths can be converted to the spatial resolution ofthe primary vertex using all SAVD tracks (subevent1 + subevent2) giving σx = 5 µm, σy = 1.5 µm andσz = 30 µm. The difference betweenσx andσy can be attributed to the presence of the vertical componentof the magnetic field which deteriorates the description of the track trajectories in the x projection. Infuture this will be improved by applying a global track fit procedure including SAVD and TPC hits.

Figure 6: Left: TPC track multiplicity versus SAVD track multiplicity. Right: TPC momentum multiplied byparticle charge versus track curvature reconstructed in the SAVD for matched SAVD-TPC tracks.

Before introducing the matching between SAVD and TPC tracks, the multiplicity correlation betweentracks reconstructed in the SAVD and the TPCs was checked. The scatter plot showing the multiplic-ity correlation is displayed in the left panel of Fig. 6. As one can see the multiplicities of SAVD andTPC tracks are well correlated supporting the correctness of the procedures described above. The prepa-ration for SAVD-TPC track matching requires transformation of the SAVD detector into the standardNA61/SHINE coordinate system. The vector of transformation was determined by studying differencesof primary vertex positions reconstructed using SAVD and TPC tracks. This was done for events havingreconstructed primary vertices in both the SAVD and the TPCs and allowed to determine the position ofthe SAVD in the standard NA61/SHINE coordinate frame with an accuracy of 16 µm, 6 µm and 100 µmin the x, y and z coordinate, respectively.

Due to the small analysis power of∫

Bdl ≈ 0.04 Tm, the track momenta determined with the SAVDalone are not accurate enough to allow sufficiently precise extrapolation of SAVD tracks through themagnetic field into the TPC volumes. So, the basic idea behind the matching procedure is the following:for a given TPC track take its total momentum (which is precise) assign it to SAVD tracks (candidates

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for matching) and extrapolate those SAVD tracks to the TPC to verify the matching. The full matchingprocedure consists of several steps and is described in detail in Appendix A.4. The right panel of Fig. 6presents the distribution of TPC track momenta multiplied by the particle charge versus the coefficient ofthe quadratic term obtained from the parabola fit to the SAVD track trajectory in the x projection (trackcurvature). As expected, for matched tracks the SAVD track curvature is correlated with the TPC trackmomentum, although the correlation bands are rather broad due to the relatively weak analysis powerof the SAVD. The correlation seen in the figure indicates that the developed matching procedure allowsunique matching with only a small fraction of accepted random combinations.

5.3. Reconstruction of the D0 signal

The current preliminary analysis did not use PID information. Based on simulations, it is expected thatthe results presented below will improve significantly after applying the PID cuts which will be done inthe next analysis iteration.

Figure 7: The invariant mass distribution of all unlike sign track pairs (green) reconstructed from the December2016 data. The spectrum was constructed without assuming particle identification (see text). The invariant massdistribution for 200k simulated 0-10% most central Pb+Pb collisions at 150A GeV/c assuming the SAVD geometryis plotted for comparison (dark blue). The red histogram displays the contribution from D0 mesons in the simulation.

The invariant mass distribution of track pairs accepted in the SAVD and successfully matched with TPCtrack is shown in Fig. 7 (green). Because PID information was not used yet, each track pair contributestwice to the spectrum, namely to calculate the invariant mass it is assumed that the first track in the pair isa pion and the second is a kaon and vice-versa. For comparison Fig. 7 also shows in dark blue the invariantmass distribution for 200k simulated 0-10% most central Pb+Pb collisions at 150A GeV/c assuming theSAVD geometry .

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It is seen that the combinatorial background is several orders of magnitude higher than the D0 + D0 signalshown in red colour. The narrow peak and the broadly distributed counts of the D0 signal componentresult from the correct and the false mass assignement to the D0 daughter tracks, respectively.

The developed background suppression strategy using simulations was already described in Refs. [5]and [6]. For the experimental data we four kinematical and topological cuts were applied:

(i) A cut on the track transverse momentum pT,

(ii) a cut on the track impact parameter d ,

(iii) a cut on the longitudinal distance VZ between the D candidate decay point and the interaction point,

(iv) a cut on the impact parameter dP of the back-extrapolated D candidate momentum vector.

Figure 8: Left: Distributions of the cut variables pT , d, VZ and dP for background (blue) and signal (red) in simu-lations. Right: Distributions of pT , d, VZ and dP extracted from reconstructed data. The cut values selected for thesimulation (left) and data analysis (right) are indicated by the vertical dashed lines.

Figure 8 shows distributions of the cut variables for simulation (left) and for the experimental data (right).Striking quantitative similarity is seen for the respective distributions derived in simulations and in thedata analysis. Some differences e.g. between pT and d slopes and the widths of central peaks in VZ canbe attributed to the simplifications used in simulations such as the assumption of zero magnetic field inthe SAVD volume. There is ongoing collaboration effort to prepare a more realistic description of theexperimental conditions for the standard NA61/SHINE simulation framework.

The cut values used for background suppression in simulation are indicated by the vertical dashed lines.Tracks with pT > 0.31 GeV/c, d > 31 µm, and track pairs with Vz > 400 µm, dP < 20 µm were selected.These values were chosen to maximize the signal to noise ratio (SNR) of the reconstructed D0 peak.For the experimental data a consistent SNR maximization procedure has not yet been developed. Justdifferent cut values around those used in the simulation were tried, and finally cut values of 0.34 GeV/c,34 µm, 475 µm and 21 µm were selected for pT, d, Vz and dP, respectively. These values are also indicatedin Fig. 8 (right).

The full Pb+Pb data set from December 2017 has been analyzed. The invariant mass distribution of unlikecharge π, K pairs in the range of the expected D0 peak is shown in Fig. 9 (left).

14

Figure 9: Left: Invariant mass distribution of unlike charge π,K decay track candidates. Right: Invariant massdistribution of π−,π+ decay track candidates. The mass spectra were obtained by applying background reductioncuts to enhance D0 (left) and K0

S (right) signals, respectively. See text for details. No pid information was used, thevertical bars represent statistical errors.

It is seen that there is a weak indication of a D0 signal. In this region the invariant mass distributionwas fitted using a sum of a third order polynomial function to describe the background and a Gaussianpeak that accounts for the D0 signal contribution. The fit is presented by the red line. From the fit onecan determine the width of the peak to be 40 ± 15 MeV and the total yield to amount to 55 ± 20 witha SNR of 3. The indicated errors are statistical only. To validate the D0 peak extraction procedure theanalysis was modified in order to extract the K0

S peak which is expected to be seen more easily than theD0 peak. For the same data set the invariant mass spectrum was reconstructed assigning pion masses toeach track pair and applying modified cut values, namely pT > 0.2 GeV/c, d > 48 µm for daughter tracks,and Vz > 750 µm, dP < 22 µm for K0

S candidates. Figure 9 (right) shows the invariant mass distributionin the region of the K0

S mass after applying all cuts. A clear peak corresponding to K0S decays is seen with

a width of 18 MeV and a SNR of about 4.5. Note, that we see only a small fraction of all K0S decaying to

π+ + π− because the tracking was optimize to account for decays of D0 which have much shorter lengthof the flight path.

At this stage of the analysis there is a weak indication of a D0 signal. However, the data are not yet finallycalibrated, and further optimization of track reconstruction, track matching, analysis algorithms and cutsis still ongoing. It may be premature to draw a final conclusion from the analysis result, except to say thatit appears promising.

6. Projectile Spectator Detector

6.1. Overview

The Projectile Spectator Detector (PSD) is a segmented forward hadron calorimeter used by the NA61/

SHINE experiment to determine the collision centrality and the orientation of the event plane. A precisecharacterization of the event class is of crucial importance for selection of event centrality at the trigger

15

level as well as for the analysis of event-by-event fluctuation observables. The PSD is also important toimprove the quality and kinematic range of measurements of collective flow in the collisions.

6.2. Upgrade of PSD read-out electronics

During previous data taking periods the PSD read-out electronics failed sometimes due to ageing of con-tacts in power connectors installed on read-out PCBs shown in Fig. 10 (left). The left pin on the connectoris the +6V power line and conducts a current of about 1.5A. During operation the area of contacting sur-faces oxidizes. This leads to unstable +6V power line connection to the board and causes instabilityof FPGA performance, which then results in DAQ crashes or corrupted waveform data delivered by theFPGA. In order to fix this issue a new type of power connector was installed. It is the MOLEX typeconnector widely used in power supplies of desktop PCs. A read-out board with exchanged connector isshown in Fig. 10 (right). The stability of operation was tested during the summer 2017 beam periods andwas found to be perfect.

A performance test of calorimeter was done in July 2017. It included a scan of PSD modules with muonand hadron beams as well as an energy scan with hadrons of 20–158 GeV/c momentum. Results of thetests are plotted in Fig. 11. Calorimeter response linearity is presented in the left panel and the energyresolution is shown in the right panel.

Figure 10: Left: Old power connector of PSD read-out module. Right: new MOLEX type connector installed.

Figure 11: Left: PSD response linearity. Right: PSD energy resolution.

16

7. Software and calibration modifications

Software and calibration upgrades performed during the last year are

(i) Only three “legacy” software releases have been made since the time of the last Status Report inorder to introduce necessary bug-fixes and updates. In view of the migration to the new Shinesoftware framework, the Collaboration decided to minimize the “legacy” software support underSLC6 and to freeze its development.

(ii) Given the progress with the new Shine software framework it was decided that only data sampleswith well advanced calibration process will be produced by the old “legacy” software for consistencyof all calibration stages. It concerns data samples collected until the end of 2015. The last datasamples reconstructed by the “legacy” chain are Ar+Sc collisions at 6 SPS energies.

(iii) The Data Base calibration constants were transferred to the new structures required by the organi-zation of the new Shine reconstruction chain.

(iv) Since the last Status Report 2016 the Collaboration started to use new Shine reconstruction software.It still inherits some functions and modules from the “legacy” software. The new Shine reconstruc-tion software and the new Data Base structures were validated over the “legacy” production chainfor several data samples.

(v) The data samples collected after 2015 are processed by the new Shine reconstruction chain. Theyare calibrated by all currently available Shine calibration modules using the SHO∗E data format.

(vi) This year the NA61/SHINE production team started to use the HTCondor system for the recon-struction of the Pb+Pb data samples. In parallel other data samples are reconstructed on the LSFplatform (LXBATCH).

(vii) The old data format DSPACK and old “legacy” Data Base are maintained only for the data samplescollected up to the end of 2015.

(viii) The new ToF-L/R Shine calibration module which uses the SHO∗E data format and a new calibrationprocedure was validated and used for calibration of the Ar+Sc data samples. The new calibrationprocedure proved to be much faster (up to seven times) and provide better time resolution (10-15%)compared to the “legacy” software.

(ix) The calibration of energy loss in TPCs (dE/dx) is still ongoing using “legacy” calibration softwarebut the software operates on ASCII DST’s obtained by the conversion from SHO∗E files - data inDSPACK format are not required. The scripts operate with files stored on EOS which makes themmuch faster than using files stored on AFS. The work on native Shine calibration and reconstructionmodules is ongoing.

(x) The Kalman filter for tracking in the magnetic field was implemented in the GAP TPC vD Calibra-tion Module. The module reads NA61/SHINE data in the SHO∗E format. The software was testedon several data samples and validated.

(xi) A neural network-based Quality Assessment algorithm was developed for the analysis of radioactivekrypton decays in the NA61/SHINE TPC system collected during dedicated calibration runs. Basedon a human-controlled analysis of about 30000 krypton decay charged deposit spectra this algorithmensures an “intelligent” monitoring of all sources of readout signal deterioration and secures themaintenance of excellent NA61/SHINE charged particle identification capabilities.

17

(xii) PSD calibrations were performed for all PSD modules using muon and proton beams. The energyscan with 20, 30, 40, 60, 80, 120 and 158 GeV/c proton beams was done for the central PSD modules.

(xiii) Significant effort was put on development of the Shine Data Base structure and Shine reconstructionchain related to the Vertex Detector. The details of the VD data structure are described in A.1. TheVD data reconstruction chain was discribed in Sec. 5.2.

8. New Results

8.1. New results for strong interactions physics

This section summarizes new physics results from the programme on physics of strong interactions andreports on analysis progress.

8.1.1. Charged kaon spectra in Be+Be collisions

New results on charged kaon production in violent Be+Be collisions at mid-rapidity have been obtainedand shown in Refs. [7, 8, 9, 10, 11, 12]. The analysis was performed for the 20% of events with thesmallest forward energy deposited in the PSD detector - 20% of the most violent Be+Be collisions. Thetof -dE/dx method of particle identification was used (measurement in a wider rapidity range, via the dE/dxmethod, is in progress). Transverse momentum spectra were fitted [9, 11] with an exponential functionin mT and the resulting inverse slope parameters are presented in Fig. 12. A step (plateau) in the energydependence of the inverse slope parameter is observed in central Pb+Pb collisions, which was predictedas a signature of the onset of deconfinement [13]. NA61/SHINE results on violent Be+Be collisions andinelastic p+p interactions are also consistent with such a plateau at SPS energies, though at a lower valueof T .

[GeV]NNs1 210 410

T [

MeV

]

200

400 +K 0≈y

[GeV]NNs1 210 410

T [

MeV

]

200

400-K 0≈y

p+p NA61 (prelim.)

Be+Be NA61 (prelim.)

p+p RHIC

p+p LHC

)πp+p world (4

Au+Au AGS

Au+Au RHIC

Pb+Pb SPS

Pb+Pb LHC

Figure 12: Energy dependence of the inverse slope parameter of transverse mass spectra at mid-rapidity for posi-tively (left) and negatively (right) charged kaons. The NA61/SHINE results on p+p interactions (full blue circles)and new results on violent Be+Be (full green diamonds) collisions are compared with world data on p+p and heavyion (Pb+Pb and Au+Au) reactions.

Figure 13 shows rapid change in the energy dependence of the K+/π+ ratio observed in Pb+Pb collisions(horn), which was also predicted as a signature of the onset of deconfinement [13]. In violent Be+Be

18

collisions, as well as in inelastic p+p interactions, a step-like structure with a following plateau is alsoobserved in the energy dependence of the K+/π+ ratio, however, at a much lower level.

[GeV]NNs1 210 410

0)≈ (

y+ π/

+K

0

0.1

0.2

[GeV]NNs1 210 410

0)≈ (

y- π/-

K0

0.1

0.2p+p NA61 (prelim.)

Be+Be NA61 (prelim.)

p+p RHIC

p+p LHC

)πp+p world (4

Au+Au AGS

Au+Au RHIC

Pb+Pb SPS

Pb+Pb LHC

Figure 13: Energy dependence of positively (left) and negatively (right) charged kaon yield divided by the corre-sponding charged pion yield at mid-rapidity.

8.1.2. Charged kaon spectra in Ar+Sc collisions

This summer, charged kaon spectra and yields were presented for the first time for violent Ar+Sc inter-actions at beam momenta 30A, 40A and 75A GeV/c [14, 12]. The double differential pT, y spectra wereobtained using the dE/dx method of particle identification. Then, pT-extrapolated and rapidity integratedspectra were used to derive mean multiplicities (in 4π) which are presented in Fig. 14. There is no clearenergy dependence and no horn structure visible in Ar+Sc collisions. The 〈K+〉/〈π+〉 ratio in Ar+Sccollisions is between the ratio in inelastic p+p interactions and the one in violent Pb+Pb collisions. Theanalysis of Ar+Sc data at 13A, 19A and 150A GeV/c is in progress.

[GeV]NNs1 10 210

0

0.2

⟩+π⟨⟩+K⟨

SPS NA61/SHINESPS NA61/SHINEWORLD (p+p)AGSSPS NA49RHIC

Pb+Pb Au+Au

p+pAr+Sc

Figure 14: Energy dependence of the 〈K+〉/〈π+〉 ratio in 4π acceptance. The new results for violent Ar+Sc collisionsare indicated by red triangles.

19

8.1.3. Multiplicity fluctuations in Be+Be collisions

New results on multiplicity fluctuations of negatively charged hadrons measured in Be+Be collisionswere obtained and shown in Refs. [15, 16, 17, 11]. For cross-check, two different measures were used:the scaled variance of the multiplicity distribution, ω[N], and the strongly intensive fluctuation measureΩ[N, EP] calculated for the distributions of multiplicity N and energy of projectile participants EP [15,16]. As expected ω[N] for very violent (0-1%) collisions coincides with Ω[N, EP] for violent (0-10%)collisions.

The energy dependence of ω[N] in inelastic p+p interaction as well as violent (0-1%) Be+Be and (0-0.2%) Ar+Sc collisions is shown in Fig. 15. The results for p+p and Be+Be collisions are close to eachother, whereas the Ar+Sc results are significantly lower and their energy dependence is weaker. Noanomalies are observed in the energy dependence for p+p, Be+Be and Ar+Sc collisions. The Epos1.99model reproduces the Ar+Sc and p+p results but underestimates the Be+Be data.

[GeV]NNs6 8 10 12 14 16 18

0.6

0.8

1

1.2

1.4

1.6

1.8

2 [h] ppω[h] BeBe 0-1%ω[h] ArSc 0-0.2%ω

EPOS ppEPOS BeBe 0-1%EPOS ArSc 0-0.2%

]-

[hω

beam<y

π0<yNA61/SHINE acceptance

NA61/SHINE preliminary

Figure 15: ω[N] in inelastic p+p (grey dots), 0-1% Be+Be (red dots), and 0-0.2% Ar+Sc (blue dots) collisionsobtained by NA61/SHINE at forward-rapidity, 0 < yπ < ybeam, and in pT < 1.5 GeV/c. Results for negativelycharged hadrons. 0nly statistical uncertainties are shown. The NA61/SHINE data are compared to the Epos1.99model.

Figure 16 presents the system size dependence of ω[N] for negatively charged hadrons at 19A GeV/cand 150A GeV/c and shows an interesting effect. A rapid decrease of ω[N] when moving from violentBe+Be to Ar+Sc collisions is observed. Within the Wounded Nucleon Model ω[N]AA = ω[N]pp providedthe number of wounded nucleons W does not fluctuate (dotted lines in Fig. 16). The WNM with Wfluctuations results in ω[N]AA > ω[N]pp. Thus Ar+Sc results are in qualitative disagreement with theWounded Nucleon Model predictions. In the Ideal Boltzmann gas within the Grand Canonical Ensemble(IB-GCE) ω[N] = 1 (Poisson multiplicity distribution), independently of the (fixed) system volume.Volume fluctuations increase multiplicity fluctuations resulting in ω[N] > 1. Adding resonance decaysand Bose-Einstein statistics would further increase ω[N]. Consequently ω[N]AA < 1 is forbidden in theIB-GCE and its extensions. The observed small values of ω[N] in violent Ar+Sc collisions may be dueto conservation laws acting in a large volume system [18]. In statistical mechanics they are introduced

20

by using canonical and microcanonical ensembles. Finally, ω[N] 1, as seen in p+p reactions at158A GeV/c, can be understood in statistical models as a result of fluctuations of the fireball volumeand/or the energy converted into particle production [19].

<W>1 10 210 310

[N]

ω

0.7

0.8

0.9

1

1.1

1.2

1.3 at 19A-20A GeV/c

-h


WNMPoisson

p+p

Ar+Sc

Be+Be

<W>1 10 210 310

[N]

ω

0.8

0.9

1

1.1

1.2

at 150A-158A GeV/c-

h


WNM

Poisson

p+p

Be+Be

Ar+Sc

Figure 16: Scaled variance of the multiplicity distribution of negatively charged hadrons versus mean number ofwounded nucleons at low (left) and high (right) SPS energy. Results for inelastic p+p interactions as well as,violent (0-1%) Be+Be, and (0-0.2%) Ar+Sc collisions are shown at forward-rapidity, 0 < yπ < ybeam, and inpT < 1.5 GeV/c. 0nly statistical uncertainties are shown.

8.1.4. System size dependence: onset of fireball

Figure 17 shows example plots on the system size dependence of the ratio of K+ and π+ yields at mid-rapidity and of the scaled variance of multiplicity distributions. The Be+Be results are very close to p+pindependently of collision energy. Moreover, the data show a jump between light (p+p, Be+Be) and in-termediate/heavy (Ar+Sc, Pb+Pb) systems. In the case of multiplicity fluctuations in the narrower NA49acceptance (the so-called NA49-B acceptance, see Ref. [20]) a difference between light and intermedi-ate/heavy systems remains but the jump is a bit less pronounced.

Here one recalls the following:

(i) The K+/π+ ratio in p+p interactions is below the predictions of statistical models. However, theratio in central Pb+Pb collisions is close to statistical model predictions for large volume systems.For detail see e.g. Ref. [21]

(ii) In p+p interactions, and thus also in Be+Be collisions, multiplicity fluctuations are larger thanpredicted by statistical models. However, they are close to statistical model predictions for largevolume systems in central Ar+Sc and Pb+Pb collisions, for detail see Ref. [18].

Thus the observed rapid change of hadron production properties that start when moving from Be+Be toAr+Sc collisions can be interpreted as the beginning of creation of large clusters of strongly interactingmatter. This phenomenon was referred to as the onset of fireball 1.

Furthermore hadron production properties in heavy ion collisions wre found to change rapidly with in-creasing collision energy in the low SPS energy domain,

√sNN ≈ 10 GeV (for a recent review see

1 The name was proposed by Edward Shuryak during the CPOD 2017 conference.

21

<W>1 10 210 310

0)≈ (

y+ π/

+K

0.1

0.15

0.2

0.25

p+pBe+Be

Pb+Pb


NA49

c GeV/A30

<W>1 10 210 310

0)≈ (

y+ π/

+K

0.1

0.15

0.2

0.25

p+pBe+Be

Pb+Pb


NA49

c GeV/A - 158A150

<W>1 10 210 310

[N]

ω

0.8

0.9

1

1.1

1.2at 150A-158A GeV/c-h


WNM

Poisson

p+pBe+Be

Ar+Sc

<W>1 10 210 310

[N]

ω

0.8

0.9

1

1.1

1.2at 150A-158A GeV/c-h


WNM

Poisson

p+pBe+Be

Ar+Sc

Pb+PbNA49

Figure 17: Top left and top right: System size dependence of K+/π+ ratio at mid-rapidity at two SPS energies.Bottom left and bottom right: System size dependence of multiplicity fluctuations of negatively charged hadrons at150/158A GeV/c in NA61/SHINE and NA49 acceptances, respectively.

Ref. [22]). The NA61/SHINE results shown in Figs. 12 and 13 indicate that this is also the case in in-elastic p+p interactions and probabaly also in Be+Be collisions. The phenomenon is labelled as the onsetof deconfinement and interpreted as the beginning of creation of quark-gluon plasma with increasingcollision energy [23].

Thus the two-dimensional scan conducted by NA61/SHINE by varying collision energy and nuclear massnumber of colliding nuclei indicates four domains of hadron production properties separated by twothresholds: the onset of deconfinement and the onset of fireball. The sketch presented in Fig. 18 illustratesthese conclusions.

The results on the onset of fireball can be considered within two theoretical approaches:

(i) The percolation approach [24, 25, 26, 27, 28] assumes that with increasing nuclear mass numberthe density of clusters (partons, strings, ...) in the transverse plane increases. Thus the probability

22

Figure 18: Two-dimensional scan conducted by NA61/SHINE by varying collision energy and nuclear mass num-ber of colliding nuclei indicates four domains of hadron production properties separated by two thresholds: theonset of deconfinement and the onset of fireball.

to form a large clusters by overlapping many elementary clusters may rapidly increase with A, thebehaviour typical for percolation models. However, this approach does not explain the equilibriumproperties of large clusters.

(ii) Within the AdS/CFT correspondence [29] creation of strongly interacting matter (system of stronglyinteracting particles in equilibrium) is dual to the formation of a (black hole) horizon and trappingsome amount of information from the distant observer [30]. It was found that the formation ofthe trapping surface takes place when critical values of model parameters are reached [31]. Thismay serve as a possible explanation of the onset of the fireball phenomenon - only starting from asufficiently large nuclear mass number the formation of the trapping surface in A+A collisions ispossible. This is then observed as the onset of fireball.

8.1.5. Pseudo-rapidity dependence of fluctuations in Be+Be collisins at 150A GeV/c

New results on joint fluctuations of multiplicity N and sum of transverse momenta PT of charged parti-cles were obtained for forward energy selected Be+Be collisions at 150A GeV/c [32]. The measures usedto quantify these fluctuations are the strongly intensive observables ∆[PT ,N] and Σ[PT ,N] [33]. Fig-ure 19 (left) shows the pseudorapidity intervals in which these quantities were determined. Figure 19 alsopresents results on the dependences on the width of the pseudorapidity interval for ∆[PT ,N] (middle) andΣ[PT ,N] (right). These dependences might be a useful probe of the phase diagram of strongly interactingmatter as different values of pseudorapidities correspond to different values of baryochemical potential.The results shown in Fig. 19 reveal that ∆[PT ,N] and Σ[PT ,N] change monotonically with increasingacceptance in pseudorapidity η in contradiction to the Epos1.99 model predictions, where ∆[PT ,N] has anon-monotonic dependence.

In Ref. [32] a strongly intensive, forward-backward multiplicity correlation measure Σ[NF ,NB] was in-troduced, where NF and NB represent multiplicities in two separated pseudorapidity intervals. Figure 20

23

8/21

Analysis extension: choice of phase-space7Be+9Be, 150A GeV/c

Sketch of psedorapidity (lab)spectrum of charged hadronswith proposed windows

0 2 4 6 8

arb.

uni

ts

0

100

200

300

400

500

600

310×

Rapidity width dependence studies will allowto probe different baryochemical potentials( pp = e−(2µB )/T ) - extension of the phasediagram scan!

ηlab

9 intervals considered:from ηlab ∈ (4.6; 5.2) up to ηlab ∈ (3; 5.2)

The lower cut: poor azimuthal angle acceptance andstronger electron contamination at backward rapidities.The upper cut: to reduce effects of spectators.

Rapidity spectra of p and p in inelastic p+pinteractions at SPS energies

y

0 0.5 1 1.5 2 2.5

dy

dn

0

0.2

0.4

0.6

0.8

1

1.2

1.4+ X

+K→p+p 16×158 GeV/c

8×80 GeV/c

4×40 GeV/c

2×30.9 GeV/c

1×20 GeV/c

y

0 0.5 1 1.5 2 2.5

dy

dn

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

+ X-

K→p+p 158 GeV/c

80 GeV/c

40 GeV/c

30.9 GeV/c

20 GeV/c

y

0 0.5 1 1.5 2 2.5 3

dy

dn

0

2

4

6

8

10

12

14

16+ X+

π→p+p 16×158 GeV/c

8×80 GeV/c

4×40 GeV/c

2×30.9 GeV/c

1×20 GeV/c

y0 0.5 1 1.5 2 2.5 3

dydn

0

2

4

6

8

10

12

14

16 + X-π →p+p 16×158 GeV/c

8×80 GeV/c

4×40 GeV/c

2×30.9 GeV/c

1×20 GeV/c

y

0 0.5 1 1.5 2 2.5 3

dy

dn

0

1

2

3

4

5

6p + X→p+p 16×158 GeV/c

8×80 GeV/c

4×40 GeV/c

2×30.9 GeV/c

1×20 GeV/c

y

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

dy

dn

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.14×158 GeV/c

4×80 GeV/c

2×40 GeV/c

1×30.9 GeV/c

+Xp→p+p

Figure 34: (Color online) Rapidity spectra of K+, K−, π+, π−, p and p produced in inelastic p+p interactions at SPSenergies, scaled by appropriate factors for better visibility. Vertical bars indicate statistical, shaded bands systematicuncertainties of the measurements. Curves depict Gaussian fits used to determine total multiplicities.

y

0 0.5 1 1.5 2 2.5 3

dy

dn

0

0.1

0.2

0.3

0.4

0.5

ur

Entries 1

Mean 1.727RMS 0.7982

positiv protons spectra

NA61

NA49

UrQMD 3.4

EPOS 1.99

p+X @ 158 GeV/c→p+p

Figure 35: (Color online) Proton rapidity distribution in inelastic p+p interactions at 158 GeV/c compared with NA49measurements [24] and predictions of the UrQMD [25, 26] and EPOS [19] models.

47

pp changes significantly with rapidityNA61, arXiv:1705.02467 [nucl-ex]

E. Andronov (for the NA61/SHINE Collaboration) Saint Petersburg State University, LUHEPN-N, PT-N and PT-PT fluctuations in nucleus-nucleus collisions at the NA61/SHINE experiment

window width0 0.5 1 1.5 2 2.5

]N

,T

[P∆

0.4

0.6

0.8

1

1.2++h-h


GeV/cABe, 0-8%, 1509Be+7NA61/SHINE,

GeV/cABe, 0-8%, 1509Be+7EPOS1.99,

window width0 0.5 1 1.5 2 2.5

]N

,T

[PΣ

0.95

1

1.05

1.1 ++h-h



GeV/cABe, 0-8%, 1509Be+7EPOS1.99,

Figure 19: Left: Sketch of pseudorapidity intervals selected for analysis. Middle: Pseudorapidity interval width de-pendence of ∆[PT ,N] of all charged hadrons produced in forward energy selected Be+Be collisions at 150A GeV/ccompared to the Epos1.99 model predictions. Right: The same for Σ[PT ,N].

shows the intervals for which the analysis was performed (left) and the resulting values of Σ[NF ,NB](right). The observed increasing trend is reproduced by the Epos1.99 model.

13/21

Strongly intensive fluctuation measures: two windows case

For extensive observables in two separated pseudorapidity intervals F and B

one can introduce new strongly intensive quantities:

Σ [NF ,NB ] =〈NB〉ω [NF ] + 〈NF 〉ω [NB ]− 2cov (NF ,NB)

〈NB〉+ 〈NF 〉

I NF , NB fluctuations

Similar expressions can be given forI NF , PTB fluctuationsI PTF , PTB fluctuations

Sketch of psedorapidity (lab)spectrum of charged hadronswith proposed windows

0 2 4 6 8

arb.

uni

ts

0

100

200

300

400

500

600

310×

7 pairs of intervals considered:ηlabB moves from (3; 3.5) up to (4.2; 4.7)

ηlabF ∈ (4.7; 5.2)

ηlab

Andronov, TMPh 185 1: 1383

E. Andronov (for the NA61/SHINE Collaboration) Saint Petersburg State University, LUHEPN-N, PT-N and PT-PT fluctuations in nucleus-nucleus collisions at the NA61/SHINE experiment

distance between centers of windows0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

]B

N,

F[NΣ

0.95

1

1.05

1.1

1.15

1.2 ++h-h



GeV/cABe, 0-8%, 1509Be+7EPOS1.99,

Figure 20: Left: Sketch of pseudorapidity intervals selected for the analysis. Right: Dependence of Σ[NF ,NB] of allcharged hadrons produced in forward energy selected Be+Be collisions at 150A GeV/c on the separation betweenthe two rapidity intervals compared to the Epos1.99 model predictions.

8.1.6. Intermittency of protons in Be+Be and Ar+Sc collisions at 150A GeV/c

An intermittency analysis was performed, in transverse momentum space, of protons produced in violentBe+Be collisions at 150A GeV/c at mid-rapidity. The results were shown in Refs. [34, 35]. The analysiswas performed for the 12% of events with the smallest forward energy, deposited in the PSD detector.The dE/dx method was used for the identification of protons. The Second Scaled Factorial Moments(SSFMs) F2(M) of candidate proton momenta were calculated as a function of bin size (number of binsM) in transverse momentum space. The correlator ∆F2(M), derived by subtracting the moments F2(M)of mixed events from data moments, was fitted, whenever possible, with a power-law. The resultingexponent (intermittency index φ2) was compared to the theoretically expected [36] critical value φ(B)

2 =

5/6.

Figure 21 (left) shows the SSFMs for data and mixed events in Be+Be. The overlap of F2(M) for data andmixed events indicates that ∆F2(M) fluctuates around zero, and suggests that no intermittency (scalingof SSFMs) is observed for Be+Be at 150A GeV/c. An estimation of the upper limit of the fraction of

24

0

0.5

1

1.5

2

2.5

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3.5

4

0 5000 10000 15000 20000

F2(M

)

M2

NA61 Be+Be dataNA61 Be+Be mixed 100

101

102

5000 10000 20000

F 2(M

)

M2

NA61 Be+BeBe+Be CMC, 99.7% noiseBe+Be CMC, 98.0% noiseBe+Be CMC, 95.0% noise

10-4

10-3

10-2

10-1

100

101

102

103

104

5000 10000 20000

∆F

2(M

)

F

2(M

)

M2

NA61 Be+BeBe+Be CMC, 99.7% noiseBe+Be CMC, 98.0% noiseBe+Be CMC, 95.0% noise

Be+Be pure CMCslope 0.84

Figure 21: Left: F2(M) of Be+Be proton transverse momenta for data (black circles) and mixed events (red trian-gles). Middle and right: F2(M) and ∆F2(M) of NA61/SHINE data and noisy CMC simulated Be+Be collisions(12% most central, 150A GeV/c), for different levels of background noise. For comparison, F2(M) of the pure CMCis plotted, along with the theoretically expected slope φ2.

critical protons in the analyzed data is performed by matching the values of F2(M) measured in the datawith those of a mixture of critical protons produced via the Critical Monte Carlo (CMC) algorithm [36]with uncorrelated background protons (noise), for different levels of background noise. Figure 21 (mid-dle/right) shows a scan in background level, with noisy CMC matching the F2(M) values from the datafor a critical component level of ∼ 0.3%. Therefore this percentage can be taken as an upper limit ofcritical component presence in the data.

Additionally, an analysis of protons produced in violent Ar+Sc collisions at 150A GeV/c at mid-rapidityis in progress. In preparation, a feasibility study was performed with Epos1.99 [37] simulations of Ar+Sccollisions at

√sNN = 16.8 GeV, corresponding to 150A GeV/c in target rest frame, with the maximum

impact parameter set to bmax = 3.5 fm. The Epos moments F2(M) are again compared to noisy CMC.Figure 22 shows the results of the Ar+Sc feasibility study. One is led to conclude that the intermittencyanalysis is feasible for Ar+Sc data, and predicts a sensitivity level to a critical component of ∼ 0.5% orhigher, above which threshold the φ2 of the critical component scaling can be recovered via fitting thecorrelator ∆F2(M).

8.1.7. ∆φ, ∆η correlations in Be+Be collisions

An analysis of two-particle correlations in ∆φ and ∆η for Be+Be collisions has been started [40]. Theenergy scan of correlations for all charged pairs is shown in Fig. 23. The results show an enhancement at∆η ≈ 0 and ∆φ ≈ π (away-side) and also a peak at (∆η,∆φ) = (0, 0) becomes visible at higher energies.

The observed structures result from different effects. Figure 24 shows two-particle correlations for dif-ferent charge combinations for beam momentum of 150A GeV/c. The away-side enhancement probablycomes from resonance decays and momentum conservation. It is most significant in unlike-sign andmuch weaker in like-sign pair combinations. This may be due to the fact that the majority of resonances

25

100

101

5000 10000 20000

F 2(M

)

M2

EPOS Ar+ScAr+Sc CMC, 99.5% noiseAr+Sc CMC, 99.0% noiseAr+Sc CMC, 98.0% noise

10-3

10-2

10-1

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101

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103

104

5000 10000 20000

∆F

2(M

)

F

2(M

)

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EPOS Ar+ScAr+Sc CMC, 99.5% noiseAr+Sc CMC, 99.0% noiseAr+Sc CMC, 98.0% noise

Ar+Sc pure CMCslope 0.84

0

20

40

60

80

0.4 0.6 0.8 1 1.2 1.4

Nsa

mp

les

φ2

CMC Ar+Sc, 99.5% noise

Figure 22: Left and middle: F2(M) and ∆F2(M) of Epos1.99 and noisy CMC simulated Ar+Sc collisions (12% mostcentral, 150A GeV/c). For comparison, F2(M) of the pure CMC is plotted, along with the theoretically expectedslope. Right: distribution of fitted φ2 values, obtained via bootstrap resampling [38, 39] of events.

Figure 23: Two-particle correlations in ∆η∆φ in Be+Be collisions. Energy scan for all charged pairs of particles.

26

Figure 24: Two-particle correlations in ∆η∆φ in Be+Be collisions. Results for different charge combinations atbeam momentum of 150A GeV/c.

decay to particles with opposite charges. The low production multiplicity of double-positively or double-negatively charged resonances gives only a very weak signal in the away-side region.

The peak at (0,0) may be due to different phenomena. It is most visible in negatively charged pairs andmay be due to the Bose-Einstein statistics effect because the majority of pairs are negatively chargedpions (bosons). The peak is lower in pairs of positively charged particles which suggests interplay ofboth Bose-Einstein and Fermi-Dirac statistics: positively charged pions (bosons) generate a correlationsignal, while protons (fermions) generate an anti-correlation signal in the same region. A (0,0) peak isweakly visible even in unlike-sign pairs. Since the products of γ conversions were removed during thedata selection process, the peak may be a result of Coulomb attraction.

The correlations in Be+Be collisions are generally weaker than those in p+p interactions which producesmaller multiplicities [41]. The larger combinatorial background in Be+Be reactions dilutes the strengthof the correlation signal. Qualitatively, the correlation landscape is similar in both systems, but in Be+Bethe enhancement around (∆η,∆φ) = (0, 0) is more prominent relative to other structures.

8.1.8. φ meson production in p+p collisions

New results on φ meson production were obtained in inelastic p+p interactions at 40, 80, and 158 GeV/cand presented in Refs. [8, 11, 12]. Examples of transverse momentum spectra, as well as rapidity distri-butions can be found in Ref. [11]. The mean multiplicity of φ mesons in 4π is plotted as a function ofcollision energy in Fig. 25 (left) and compared to various model predictions (for fitting the paramters inthe HRG model [42] only π+, π−, K+, K− and antiproton multiplicities were used). Figure 25 (middle) de-picts mid-rapidity yields. The best agreement with the data is shown by the Epos1.99 model although theenergy dependence is too steep. Figure 25 (right) demonstrates that the φ to π ratio is strongly enhancedin central Pb+Pb collisions [43] compared to inelastic p+p interactions.

8.1.9. Performance of anisotropic flow measurement in Pb+Pb collisions

In NA61/SHINE the measurement of flow harmonics in Pb+Pb collisions provides a reference for study-ing collective flow effects in smaller systems explored by the collision energy and system size scan. Atthe moment the only published results for v1 and v2 of pions, protons, and Λ hyperons at 40A GeV and158A GeV are available from NA49 [44, 45]. The new data samples of Pb+Pb collisions collected byNA61/SHINE in November 2016 make it possible to extend the measurements of the anisotropic flow as

27

[GeV]NNs10 20 30 40 50

⟩φ⟨

0

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0.05NA61/SHINE

world data

EPOS 1.99Pythia 6UrQMD 3.4

HRG

[GeV]NNs10 210 310 410

dy

(y =

0)

/d

n

0

0.01

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0.04NA61/SHINE

world data

EPOS 1.99Pythia 6UrQMD 3.4

[GeV]NNs5 10 15 20

⟩π⟨ / ⟩φ⟨

1000

1

2

3

4

5

NA61 p+p

NA49 Pb+Pb

Figure 25: Energy dependence of φ meson mean multiplicity in 4π (left) and at mid-rapidity (middle). Energydependence of the 〈φ〉/〈π〉 ratio in inelastic p+p interactions and central Pb+Pb collisions [43] (right).

a function of collision centrality with beams in the momentum range from 13A GeV/c to 158A GeV/c andto forward rapidities which are significantly larger than what is presently accessible by RHIC experiments(see e.g. results by STAR [46]). Performance studies of charged pion directed flow measurement per-formed on Pb+Pb data collected by NA61/SHINE in November 2016 at 30A GeV/c are reported below.

Event classification (centrality determination) is performed following the procedure described in Ref. [47].Figure 26 shows the result of the event classification procedure using the multiplicity distribution ofcharged particles reconstructed in the NA61/SHINE TPCs.

0 100 200 300 400TPC multiplicity

1

10

210

310

410coun

ts

Fit: mWNM (MC-Glauber+NBD)

NA61/SHINE

NA61/SHINE Performance

Pb-Pb @ 30A GeV

Centrality: TPC

0-5%>50%

Figure 26: Multiplicity distribution of charged particles produced in minimum bias Pb+Pb collisions at 30A GeV/cand reconstructed in the NA61/SHINE TPCs together with a fit function based on the modified Wounded NucleonModel (aka Glauber fit). The vertical lines mark event (centrality) classes.

To estimate the reaction plane orientation it is common to use the azimuthal asymmetry of particle pro-duction in the transverse plane to the beam direction. Due to the momentum transfer between participantsand spectators, the spectators (fragments of projectile and target nuclei) are deflected in the course of thecollision. For non-central collisions, the asymmetry of the initial energy density in the transverse planeis expected to be aligned in the direction of the reaction plane, and thus the spectator deflection directionis likely to be correlated with the impact parameter (or reaction plane) direction. One can estimate thereaction plane angle with spectators detected in the PSD and extract flow of produced particles detectedin the TPCs with respect to this plane.

28

The asymmetry of the measured distributions is described in terms of two dimensional vectors u1, q andQ determined event-by-event from the TPC tracks and groups of PSD modules (sub-events):

Q =1E

∑i

Ei ni ; q =1M

∑i

u1,i ; u1,i = cosϕi, sinϕi , (1)

where the unit vector ni points to the center of the i-th PSD module, Ei is the energy deposition in the i-thmodule and E =

∑i Ei is the total energy of the PSD sub-event. For each particle track i reconstructed

with the TPC a 1-st harmonic unit vector u1,i is defined. The TPC q-vectors were calculated in 0.2 wideslices of rapidity using Eq. (1) where M is the number of particle tracks in a given slice of rapidity.

Independent estimates of the Q-vector correction factors CA1,iB,C and flow harmonics v1,iA, B can be

obtained as follows:

v1,iA, B =2〈qiQA

i 〉

CA1,iB,C

; CA1,iB,C =

√2〈QA

i QBi 〉〈Q

Ai QC

i 〉

〈QBi QC

i 〉. (2)

Imperfect acceptance and efficiency of the detector bias the azimuthal angle distribution of measuredparticles. A correction procedure for the Q-vectors was proposed in Ref. [48]. This procedure is im-plemented in a software framework (QnCorrections framework) [49, 50]. The event plane resolutioncorrection is defined similar to Eq. (2) (right), but instead of the Q-vector components the event planeangles are used to define Q = |Q|(cos ΨEP, sin ΨEP):

RA1,yB,C =

√√2〈sin ΨA

EP sin ΨBEP〉〈sin ΨA

EP sin ΨCEP〉

〈sin ΨBEP sin ΨC

EP〉. (3)

Figure 27 (left) shows the resolution correction factors for Qy-vector components defined for three PSDsub-events: central (PSD1), middle (PSD2), and outer (PSD3) module groups.

0 10 20 30 40 50 60centrality, %

0

0.2

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A 1,

yR

PSD1PSD2,PSD3

PSD2PSD1,PSD3

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NA61/SHINE Performance

Pb-Pb @ 30A GeV

centrality: TPC

subeventsyQ

subevent: A B, C

0 0.5 1 1.5y

0.06−

0.04−

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0

1v

> 0 GeV/c 15-35%T

p±π

> 0.2 GeV/c 10-40%T

p-π

> 0 GeV/c mid-centralT

p±πNA49

> 0.2 GeV/c 10-40%T

p-πSTAR

NA61/SHINE Performance Pb-Pb @ 30A GeV

centrality: TPC

subeventsyQ

-dep. eff. corr.]T

NA61/SHINE [without p

Figure 27: Left: resolution correction factors RA1,y obtained with different PSD sub-events. Right: charged pion

directed flow for the 15-35% (blue) and 10-40% (red) centrality classes obtained using the y components of thePSD Q-vectors.

Results for charged pion directed flow calculated for 400K selected Pb+Pb collisions at 30A GeV/c andthe event plane estimates from the combined PSD are shown in Fig. 27 (right). Directed flow as a function

29

of rapidity was measured for the 15-35% event (centrality) class (red squares), which corresponds to themidcentral class used in the NA49 flow analysis [44, 45]. At the moment no pT-dependent acceptance andefficiency correction was applied to the extracted value of v1. NA61/SHINE results for π± (blue squares)are compared to those published for midcentral collisions by NA49 [44] and for π− (red squares) withrecent publication from the RHIC Beam Energy Scan [46] obtained for the 10-40% centrality class. Al-though not yet ready for physics interpretation, the comparison presented in Fig. 27 (right) demonstratesthe improved NA61/SHINE performance with respect to the NA49 experiment gained in particular by theuse of the spectator measurements with the PSD. The results also promise an extended rapidity coveragefor flow measurements in comparison to the RHIC BES data with a comparable precision.

8.1.10. Analysis of electromagnetic effects in Ar+Sc collisions

x F

x F

x F

−

+π

/π

Ar+Sc, 150 GeVAr+Sc, 150 GeV

Ar+Sc, 150 GeVAr+Sc, 150 GeV

(b)(a)

intermediatehigh multiplicity multiplicity

−

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/π

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+π

/π

NA49 preliminary

p = T

500225175125 75 25 MeV/c

p = T

500225175125 75 25 MeV/c

p = T

500225175125 75 25 MeV/c

peripheralPb+Pb, 158 GeV

(c)

NA61/SHINE NA61/SHINE

Figure 28: The π+/π− ratio in high multiplicity (a) and intermediate multiplicity (b) Ar+Sc collisions, compared toperipheral Pb+Pb reactions (c). Statistical uncertainties in Ar+Sc collisions are not shown. They are typically 4%,but reach 7% in the region of the minimum seen in panel (b). The vertical arrow indicates the position of beamrapidity at pT = 0.

Two results of the first analysis of spectator-induced electromagnetic (EM) effects [51] occurring inAr+Sc collisions at 150A GeV/c beam momentum are presented in Fig. 28. As this first analysis wasperformed on experimental data taken with a semi-central trigger, cuts on total observed charged particlemultiplicity were applied in order to select central and intermediate centrality collisions. These are pre-sented in Figs. 28 (a) and 28 (b), respectively. The number ratio of produced positively over negativelycharged pions (π+/π−) is drawn as a function of xF = pL(pion)/pL(beam nucleon) at several fixed valuesof transverse momentum pT, both variables taken in the collision c.m.s. For central Ar+Sc collisions,shown in Fig. 28 (a), relatively little dependence of π+/π− on pion longitudinal and transverse momentumis apparent, although some lowering of the ratio at xF ≈ 0.15 could be suggested by the data. On the otherhand, at intermediate multiplicity (centrality) shown in Fig. 28 (b), a strong depletion of the ratio in thevicinity of xF = 0.15 at low pT is evident. The latter value of xF (0.15 = mπ/mp) corresponds at low pT topions moving with spectator velocity (rapidity). One sees here the result of the final state electromagneticrepulsion (attraction) of positively (negatively) charged pions produced in the collision by the positivelycharged spectator system. This effect can be regarded as a presage of the fully developed EM distortionpresent in the NA49 data on peripheral Pb+Pb collisions at 150A GeV/c shown in Fig. 28 (c). Here theπ+/π− ratio comes close to zero at xF = 0.15.

The electromagnetic nature of this effect seen in intermediate multiplicity Ar+Sc data is confirmed, in a

30

model independent way, by the fact that such low values of the π+/π− ratio break the isospin symmetryfor the Ar+Sc system composed of 18 protons and 22 neutrons for argon, and 21 protons and 24 neutronsfor scandium. This EM effect is noticeably large, although it is caused by a spectator charge of the orderof only about 10 elementary units. This has to be compared to about 70 e.u. in the peripheral Pb+Pbcase. As discussed in Ref. [52], the EM effect can be used to obtain new information on the space-time evolution of the participant system in Ar+Sc reactions (see Ref. [53] for comparison), as well ason the space-time evolution of the argon spectator system [54, 55]. The first observation presented inFig. 28 (b) corresponds, to the best of present knowledge, to the smallest nucleus-nucleus system wherespectator-induced EM effects would be observed experimentally at SPS energies. Put in comparison todata on Pb+Pb collisions, new information on the system size dependence of the space-time evolution ofboth participant and spectator systems will become available. The extension of the present study to fullyperipheral Ar+Sc collisions, also available to NA61/SHINE, will further extend this knowledge and giveaccess to even larger spectator-induced EM effects in the latter reactions.

8.2. New results for neutrino physics

Good progress has been achieved in the NA61/SHINE program for neutrino physics over the last year.

8.2.1. Measurements for T2K

New measurements of π± emission from the surface of the T2K replica (90 cm-long) carbon target wererecently published [56] from data collected during the 2009 run. Fully-corrected differential yields ofπ±-mesons from the surface of the T2K replica target for incoming 31 GeV/c protons were obtained. Apossible strategy to implement these results into the T2K neutrino beam predictions has been proposedand the propagation of the uncertainties of these results to the final neutrino flux has been discussed.

These NA61/SHINE measurements are currently being used by the T2K Collaboration to reduce system-atic uncertainties on the predicted (anti-)neutrino fluxes in T2K. There are good prospects to reduce theflux systematic error from about 10% down to about 5% [57].

Moreover, the analysis of the high-statistics 2010 replica-target data has just been finalized [58] withinNA61/SHINE. It allowed to release π±, K± and proton differential yields from the surface of the T2Kreplica target. It is important to note that K± and proton differential yields from the replica target surfacewere measured for the first time and the accuracy of the measured π± yields was improved. Statisticalerrors which dominated in the previously published results have now been reduced by a factor of two.

The analysis was performed by using a joint energy-loss and time-of-flight particle identification proce-dure as described in the previous publication devoted to replica target measurements [56]. In contrastto other NA61/SHINE measurements, replica-target measurements are performed by extrapolating TPCtracks towards the target surface instead of reconstructing the main interaction point. This was donebecause the T2K neutrino flux actually depends on the longitudinal position of emitted hadrons alongthe target surface. Therefore, the π±, K± and proton results are presented as double differential yieldsnormalized by the total number of incoming beam protons hitting the target, in bins of momentum, polarangle and longitudinal position along the target surface. The target was subdivided into five longitudinalsections 18 cm in size and the downstream target face. Polar angle and momentum binning is defined foreach particle species separately since the size of the bins depends on the available statistics. Extracted

31

p [GeV/c]0 2 4 6 8 10 12 14

]-1

GeV

/c))

⋅)

[(ra

dθ

n/(d

pd2 d

0

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+π

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]-1

GeV

/c))

⋅)

[(ra

dθ

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-π

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p [GeV/c]0 1 2 3 4 5 6 7 8

]-1

GeV

/c))

⋅)

[(ra

dθ

n/(d

pd2 d

0

5

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30

353−10× < 120 mradθ ≤60

+K

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p [GeV/c]0 1 2 3 4 5 6 7 8

]-1

GeV

/c))

⋅)

[(ra

dθ

n/(d

pd2 d

02468

10121416

3−10× < 120 mradθ ≤60

-K

< 120 mradθ ≤60

p [GeV/c]0 5 10 15 20 25 30

]-1

GeV

/c))

⋅)

[(ra

dθ

n/(d

pd2 d

05

10152025303540

3−10× < 40 mradθ ≤20

p

< 40 mradθ ≤20

Data

FLUKA 2011.2c.5

NuBeam G4.10.03

QGSP_BERT G4.10.03

Figure 29: Double differential π±, K± and proton yields coming from the second longitudinal target bin and oneselected polar angle interval. Vertical error bars represent statistical uncertainties, while shaded regions are system-atic uncertainties. Lines represent predictions of different MC models: Fluka2011.2c.5 (red), NuBeam (blue) andQGSP_BERT (green) physics lists of Geant4.10.

yields were fully corrected for various inefficiencies by using multiplicative corrections based on the dataand simulations.

Detailed comparisons of the π±, K± and proton yields with the Fluka2011.2c.5 model [59, 60, 61] as wellas with the NuBeam and QGSP_BERT physics lists of Geant4.10 [62, 63, 64] have also been performed.An example can be seen in Fig. 29 which shows hadrons emitted from the second longitudinal target binin just one selected polar angle interval. Both, the Fluka2011.2c.5 and NuBeam Geant4.10 physics listspredict pion yields within ±30%, whereas QGSP_BERT Geant4.10 shows larger differences. While allselected models provide reasonable predictions for charged kaon yields, they all fail to predict protonyields. The differences can be larger than a factor of two. A full set of comparisons can be found inRef. [58].

These new results represent a major milestone for the neutrino-related programme of NA61/SHINE. Re-duction of systematic uncertainties on the (anti-)neutrino fluxes down to 5% and below is one of thepriorities for the on-going and future neutrino experiments. Publication of these results is in prepara-tion.

32

8.2.2. Measurements for Fermilab neutrino beams

NA61/SHINE is engaged in a programme of hadron production measurements to benefit the Fermilabneutrino programme. The current NuMI beam uses 120 GeV/c protons on a graphite target to produceneutrinos for the Minerva and NOvA experiments (and previously MINOS and MINOS+). The proposedfuture LBNF beamline from Fermilab to South Dakota for the DUNE experiment [65] will provide aneven higher intensity beam using protons with an energy between 60-120 GeV/c (still to be determined)on a graphite or possibly beryllium target. In addition to measurements of the particles produced bythe interactions of the primary beam protons, the hadrons produced by secondary interactions of lower-energy protons and pions and kaons in the target and aluminium horns also contribute significantly to theneutrino flux. NA61/SHINE is well suited to make measurements that can reduce the flux uncertaintiesfor the Fermilab neutrino experiments.

Data were collected for the Fermilab experiments in 2015, but without a magnetic field. This data can beused to constrain the total interaction cross section but cannot be used for spectral measurements. Physicsdata were collected for Fermilab experiments in 2016 and again in 2017. As described in Sec. 3, the 2017data include the newly installed forward TPCs and four reinstalled forward time-of-flight modules wereplaced around the forward TPCs. This improves the acceptance for forward emitted particles (like highmomentum protons) and improves the particle identification for low momentum particles.

Preliminary measurements of the total production cross sections have been made with many of the 2015and 2016 datasets for 31 GeV/c and 60 GeV/c. These preliminary numbers are summarized in Table 4 andFig. 30, which also shows comparisons to existing 60 GeV/c measurements [66]. A paper containing allof these cross sections is in preparation.

Reaction Year Prelim. σprod (mb) Stat. Error (mb) Sys. Error (mb)π+ + C at 31 GeV/c 2015 160.5 1.9 +4.5 -4.3π+ + Al at 31 GeV/c 2015 311.9 4.1 +6.1 - 5.8K+ + C at 60 GeV/c 2015 144.9 2.3 3.0K+ + Al at 60 GeV/c 2015 285.3 5.6 5.3π+ + C at 60 GeV/c 2015 164.2 1.6 +1.8 -4.3π+ + Al at 60 GeV/c 2015 309.6 3.8 +2.7 -7.7π+ + C at 60 GeV/c 2016 155.8 4.1 +3.3 -4.7

Table 4: Preliminary production cross section measurements with NA61/SHINE data.

The ultimate goal is to measure the differential yields of secondary hadrons exiting the target materials.The highest priority are analyses of the π+ +C at 60 GeV/c and p+C at 120 GeVc datasets, and it isexpected that the first of these will be released in 2018. A small π+ +C at 31 GeV/c dataset extracted fromthe 2009 T2K π+ +C at 31 GeV/c dataset has been analysed and preliminary spectra were presented [67].These results should be greatly improved in the future with the dedicated high statistics π+ +C at 31 GeV/cdata that were collected in August 2017.

8.3. New results for cosmic-ray physics

The results obtained within the NA61/SHINE programme on cosmic-ray physics are summarized in thissection. They include new data for air shower physics and dark matter searches.

33

Nuclear Target

2/3

[mb]

/Apr

odσ

25

30

35

40

45

50NA61/SHINE Preliminary

Li C Al Cu Sn Pb

. et alA.S. Carroll,

60 GeV/c+Li, C, Al, Cu, Sn, Pb+π

60 GeV/c+Li, C, Al, Cu, Sn, Pb+

K

beam+πNA61:

+C 31 GeV/c (2015)+π+C 60 GeV/c (2015)+π

+C 60 GeV/c (2016)+π

+Al 31 GeV/c (2015)+π

+Al 60 GeV/c (2015)+π

beam+

NA61: K+C 60 GeV/c (2015)

+K

+Al 60 GeV/c (2015)+

K

Figure 30: Preliminary production cross section measurements for π and K on a variety of targets from 2015 and2016 data of NA61/SHINE (full symbols). Comparisons are also shown to earlier 60 GeV/c measurements fromRef. [66] (open symbols).

8.3.1. Air Shower Physics

The analysis of hadronic production cross sections in π−+C needed for the understanding of cosmic-rayinduced air showers has made significant progress last year.

The mean multiplicities of ρ0, ω and K∗0 in π−+C interactions at 158 and 350 GeV/c were published inEPJC [68]. The measurements are presented in Fig. 31 and compared to hadronic interaction models used

34

Fx0 0.2 0.4 0.6 0.8 1

Fdxdn

Fx

0

0.02

0.04

0.06

0.08

0.1

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0.2EPOS1.99DPMJet3.06Sibyll2.1Sibyll2.3QGSJetII-04EPOSLHC

+C at 158 GeV/c-π in 0ρNA61/SHINE

Fx0 0.2 0.4 0.6 0.8 1

Fdxdn

Fx

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+C at 350 GeV/c-π in 0ρNA61/SHINE

Fx0 0.2 0.4 0.6 0.8 1

Fdxdn

Fx

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0.12 EPOS1.99DPMJet3.06Sibyll2.1Sibyll2.3EPOSLHC

+C at 158 GeV/c-π in 0*KNA61/SHINE

Fx0 0.2 0.4 0.6 0.8 1

Fdxdn

Fx

0

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0.12

0.14

0.16 DPMJet3.06Sibyll2.1Sibyll2.3EPOSLHCEPOS1.99

+C at 158 GeV/c-π in ω

NA61/SHINE

Figure 31: Spectra of ρ0, ω and K∗0 as a function of xF. The statistical uncertainties are represented by bars and thesystematic ones by gray bands [68].

in air shower simulations. These results are the first π−+C measurements taken in this energy range andare important to tune hadronic interaction models used to understand the measurements of cosmic-ray airshowers. The comparisons of the measured spectra to predictions of hadronic interaction models suggestthat for all models further tuning is required to reproduce the measured spectra of ρ0, ω and K∗0 mesonsin the full range of xF. Recent retunes of these models to resonance data in π+p interactions resultedin changes of the muon number at ground of up to 25% [69, 70]. The new data provided here for π+Cinteractions gives a more adequate reference for pion-air interactions relevant for air showers and willhelp to establish the effect of forward resonance production on muons in air showers with the precisionneeded for using the muon number to estimate the particle type of primary cosmic rays, as e.g. plannedwithin the upgrade of the Pierre Auger Observatory [71].

A preliminary release of identified spectra of K±, protons and anti-protons in π− +C interactions waspresented in Ref. [72] and complements the earlier NA61/SHINE measurement of identified π± [73]production. For the comparison with hadronic interaction models, the measured K±, p and p spectrawere integrated over pT by fitting an exponential function in transverse mass to the data. The resultingintegrated spectra for 158 GeV/c are shown in Figs. 32 and similar results for 350 GeV/c can be found inRef. [72]. As can be seen, none of the models provides a satisfactory description of all particle productiondata, at both energies. In the special case of anti-protons, which is of special importance for air showermodelling [74], only the Epos-LHC model provides a satisfactory description of the data from NA61/

SHINE.

These result on identified particles in π−+C interactions are currently finalized by studying the productionof Λ, Λ and K0

S for a better control of feed-down corrections.

35

p [GeV/c]1 10 210

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+ X- p→ + C -πat 158 GeV/c

Figure 32: Spectra of π±, K±, p and p as a function of momentum p, integrated over pT, for the 158 GeV/c data set.The statistical uncertainties are represented by bars and the systematic ones by gray bands.

36

8.3.2. Cosmic-Ray Propagation and Dark Matter

Dark matter annihilation or decay may produce anti-deuterons, which have an ultra-low astrophysicalbackground. This motivates the effort to get a better understanding of the production mechanism of(anti-)deuterons. Dominant sources of anti-deuterons in the astrophysical background are proton-protoninteractions, as protons are the most abundant cosmic-ray particle and hydrogen is the most abundantintergalactic medium. The analysis of NA61/SHINE data will be useful in searching for anti-deuterons inthe AMS-02 data, and also the data from GAPS in future [75].

The anti-deuteron production threshold in p+p interactions is 15.9 GeV/c in the laboratory frame. Thusdata sets of p+p interactions with beam momenta of 158 GeV/c (

√s = 17.3 GeV) and 400 GeV/c

(√

s = 27 GeV) recorded by NA61/SHINE allow for a study of anti-deuteron production well abovethe threshold. Although anti-deuterons are rarer and thus difficult to detect, deuteron production in p+pinteractions is significantly more abundant and it is expected to shed light on anti-deuteron production.

This analysis investigated protons and deuterons produced in inelastic p+p interactions at 158 GeV/crecorded by NA61/SHINE in 2010 and 2011. Protons and deuterons are identified by their energy deposi-tion dE/dx as a function of momentum. At low momenta (below ≈ 2 GeV/c) deuterons are well separatedfrom protons, and both particle types were selected using the regions shown in Fig. 33 (left).

Figure 33: Left: Distribution of positively charged particles in the dE/dx–p plane measured in p+p interactions at158 GeV/c. Regions used to select protons and deuterons are indicated. Right: Distribution of the z-coordinate ofthe main interaction vertices.

Differential production cross-sections of a particle are calculated from the data as:

dσdp

=σtrig

NI − α · NR

(dnI − α · dnR

dp

)where σtrig is the trigger cross-section for interactions within the target (calculated from the interactionprobability pint), NI (NR) are the number of events analysed with target inserted (removed), dnI (dnR)is the count of particles produced with target inserted (removed) corrected for acceptance and detectorefficiency, and dp is the size of the momentum bin.

37

To estimate the correction due to off-target interactions, about 10% of the data were collected withoutthe liquid hydrogen in the target (the so-called target-removed data). Before the particle identificationprocedure, the normalized target-removed yield was subtracted from target-inserted data. The normaliza-tion factor α between target-inserted and target-removed data was calculated from the distribution of thez-coordinate of all interaction vertices as shown in Fig. 33 (right). It is the ratio of the number of eventswith vertex outside the target for target-inserted and removed data. The background-subtracted protonand deuteron counts for Run 2010 and 2011 are shown in Fig. 34. These counts have not been correctedfor detector acceptance and efficiency.

Figure 34: Acceptance and efficiency uncorrected, background-subtracted proton and deuteron counts as a functionof pT (left) and momentum per nucleon (right).

The measured values of pint and σtrig for Runs 2009, 2010 and 2011 are shown in Table 5. These valueshave not been corrected for the quasi-elastic cross-section yet.

Table 5:Run Total p+p events Events analyzed after cuts pint σtrig (mb)2009 4 million 1.0 million 0.0225 ± 0.0004 26.96 ± 0.442010 44 million 15.7 million 0.0240 ± 0.0003 28.8 ± 0.32011 14 million 4.3 million 0.0235 ± 0.0004 28.2 ± 0.4

The particle yields will be used to calculate the Lorentz invariant cross-section for proton and deuteronproduction as function of rapidity and transverse momentum. Preliminary cross-sections for protons anddeuterons, uncorrected for detector acceptance and efficiencies are shown as function of momentum andtransverse momentum in Fig. 35.

The d/p ratio shown in Fig. 36 was also calculated without the detector acceptance and efficiency correc-tions for yields from Monte Carlo. This ratio does not depend on the measurement of pint and σtrig, andhence is a simpler calculation without the need to correct for quasi-elastic effects. The numerator is theinvariant deuteron yield, obtained by scaling the background-corrected counts with particle energy, andthe denominator is the invariant proton yield.

38

Figure 35: Acceptance and efficiency uncorrected, trigger-efficiency corrected cross-sections for protons anddeuterons for Runs 2010 and 2011, as a function of p (left) and as a function of pT (right).

Figure 36: The d/p ratio in p+p interactions as a function of transverse momentum pT in the analysis acceptance.The data are uncorrected for detector acceptance and efficiency.

The analysis will be extended to higher momentum by also using the mass-squared values from the time-of-flight measurement for particle identification. Particle counts in regions where the Bethe-Bloch curvesof protons merge with deuteron will be obtained by dE/dx template fitting. Detected particle countsneed to be corrected for detector efficiency and acceptance using the Geant-based detector simulations.This study will be extended to search for d. The recently recorded p+p collisions at 400 GeV/c beammomentum will also be analysed.

39

9. Data-taking Plan

The NA61/SHINE data-taking plan for 2018 is presented in Table 6. Following the current acceleratorschedule the plan assumes that a primary Pb beam and proton beams will be available in 2018.

Beam Target Momentum Year Days PhysicsPrimary Secondary (A GeV/c)

p 400h Pb 13-400 2018 14 days PSD calibration

p 400p Pb 400 2018 7 days mRPC test

p 400K+ C 30 or 60 2018 7 days ν

p 400p T2K RT 120 2018 28 days ν

Pb 14C,O p,C 13 2018 7 days CR test

Pb Pb 20, 40, 75, 150 2018 60 days SI

Table 6: The NA61/SHINE data taking plan for 2018. The following abbreviations are used for the physics goals:SI – measurements for physics of strong interactions, CR – measurements for cosmic-ray physics, ν – measurementsfor the Fermilab neutrino beams.

The 2018 beam request is explained as follows:

(i) 14 days of h+ beam at 13-400 GeV/c are needed for the PSD calibration.

(ii) 7 days of p beam at 400 GeV/c are needed for the mRPC test.

(iii) 7 days of K+ beam at 30 or 60 GeV/c are needed for data taking for the Fermilab neutrino beams.As indicated in Ref. [76] thin target data with hadrons from 30-120 GeV/c is most useful for theFermilab experiments. One of the dominant uncertainties on the neutrino fluxes in the NuMI andLBNF beamlines is from the production of hadrons from secondary pions and kaons that re-interactin the beamline materials [77]. We have focussed on collecting pion and proton data so far, but thereis no existing hadron production data for kaon interactions on carbon in this energy range.

(iv) 28 days of p beam at 120 GeV/c are needed for data taking for the Fermilab neutrino beams. Protondata have been recorded in NA61/SHINE on a thin carbon target, and in 2018 we aim to take dataon a long cylindrical graphite target, as was indicated in Ref. [76].

(v) 7 days of secondary 12C and 16O beams are needed for the test of fragmentation cross section mea-surements requested by the cosmic-ray community. This new request is justified in Addendum [2]submitted to the SPSC in parallel to this document.

(vi) 60 days of Pb beam at 13A, 19A, 75A and 150A GeV/c are needed to complete data-taking on Pb+Pbcollisions, see Ref. [6] for detail. The Pb beam time will be used as follows:

(a) 20 days Pb beam at 150A GeV/c for open charm, collective effects and fluctuations,

40

(b) 20 days Pb beam at 75A GeV/c for open charm, collective effects and fluctuations,

(c) 8 days Pb beam at 40A GeV/c for collective effects and fluctuations,

(d) 8 days Pb beam at 19A GeV/c for collective effects and fluctuations.

GeV/c]Abeam momentum [13 20 30 40 75 150

syst

em s

ize

p+p

p+Pb

Be+Be

Ar+Sc

Xe+La

Pb+Pb

2009/10/11

/17/182012/14/16

2011/12/13

2015

2017

2016/18

Figure 37: The NA61/SHINE data recorded within the (beam momentum)-(system size) scan and the request tocomplete it in 2018 (in gray).

Figure 37 schematically illustrates the status and plans for data-taking within the NA61/SHINE (beammomentum)-(system size) scan.

41

10. Summary

The summary of this report is as follows:

(i) Recorded data (see Section 2):

(a) Data on hadron-nucleus interactions (six reactions) for the Fermilab neutrino beams were recordedin September and October 2016 as scheduled.

(b) Data on Pb+Pb collisions at 13A GeV/c and 30A GeV/c for studies of collective effects wererecorded in November and December 2016 as scheduled, a test of the Vertex Detector withPb+Pb collisions at 150A GeV/c was successfully conducted.

(c) Data on p+Pb collisions at 30 GeV/c were successfully collected.

(d) Data taking on hadron-nucleus interactions (six reactions) for the Fermilab neutrino beams wascontinued with the newly installed FTPCs in August 2017 as scheduled.

(ii) Facility modifications (see Section 3):

(a) The Forward-TPCs were constructed, installed and commissioned during the June-July testbeam period. The first physics data with the F-TPCs were recorded during the August 2017 runfor the Fermilab neutrino beams.

(b) The Vertex Detector was completed, commissioned and recorded the data on Pb+Pb collisionsat 150A GeV/c in December 2017. The preliminary data analysis shows an indication for the D0

peak.

(c) DRS4-based readout boards were constructed and tested with the F-ToF and PSD detectors.They were used for the first time to read out the F-ToF during the physics run in August 2017.

(d) The Projectile Spectator Detector was calibrated in June 2017 and prepared for operation, inparticular for the Xe+La data taking.

(e) Electronics of the Beam Position Detectors were upgraded to improve signal quality.

(f) The new chiller for TPC FEE water cooling was installed and will be first used in the October-December 2017 runs.

(iii) Software modifications (see Section 7):The most important achievements associated with the upgrade program of the NA61/SHINE soft-ware are:

(a) The Shine reconstruction chain and the Shine data base are used for data production.

(b) The HTCondor system started to be used for data production in parallel with the legacy LSFplatform.

(c) The calibration procedures are being upgraded and moved to Shine.

(d) The development and integration of the calibration and reconstruction algorithms for the newdetectors is ongoing.

(iv) Numerous new physics results, final and preliminary, were released, see Section 8. They, in partic-ular, include:

42

(a) inclusive spectra of charged kaons at mid-rapidity in Be+Be collisions at 30A-150A GeV/c,

(b) inclusive spectra of charged kaons at forward rapidity and their mean multiplicity in the fullacceptance in Ar+Sc collisions at 30A-75A GeV/c,

(c) multiplicity fluctuations in Be+Be collisions at 20A-150A GeV/c.

These results indicate a rapid change of hadron production properties that start when moving fromBe+Be to Ar+Sc collisions and can be interpreted as the beginning of creation of large clusters ofstrongly interacting matter. This unexpected observation is referred to as the onset of fireball.

Further new physics results concern:

(a) the pseudo-rapidity dependence of fluctuations in Be+Be at 150A GeV/c,

(b) intermittency of protons in Be+Be and Ar+Sc at 150A GeV/c,

(c) ∆φ, ∆η correlations in Be+Be at 20A-150A GeV/c,

(d) φ meson production in p+p at 40-158 GeV/c.

(e) high statistics spectra of identified hadrons emitted from the T2K replica target (2010 data set),

(f) cross section for hadron-nucleus production interactions for six different reactions (data recordedin 2015 and 2016),

(g) final resonance spectra in π−+C interactions at 158 and 350GeVc,

(h) spectra of identified hadrons in π−+C interactions at 158 and 350 GeV/c

Moreover, the status of the analysis of the π+/π− ratio in Ar+Sc collisions was reported, showing forthe first time the presence of spectator-induced EM effects for such a small system at SPS energies.The analysis of anisotropic flow demonstrates the improved NA61/SHINE performance with respectto the NA49 experiment and promises an extended rapidity coverage compared to the RHIC BESdata.

(v) The data-taking plan for 2018 (see Section 9) requests runs with primary Pb beams as well assecondary hadron beams needed for measurements for strong interaction and neutrino physics. Afurther request for a test with secondary light ion beams resulting from fragmentation of a primaryPb beam is presented in detail in Addendum [2] submitted to the SPSC in parallel to this document.

A proposal to extend the NA61/SHINE physics programme for the period between Long Shutdown 2and 3 is under preparation and will be submitted to the SPSC within the coming months.

Acknowledgements

We would like to thank the CERN EP, BE and EN Departments for the strong support of NA61/SHINE.

This work was supported by the Hungarian Scientific Research Fund (Grants NKFIH 123842–123959),the János Bolyai Research Scholarship of the Hungarian Academy of Sciences, the Polish Ministry ofScience and Higher Education (grants 667/N-CERN/2010/0, NN 202 48 4339 and NN 202 23 1837), thePolish National Center for Science (grants 2011/03/N/ST2/03691, 2013/11/N/ST2/03879, 2014/13/N/

ST2/02565, 2014/14/E/ST2/00018, 2014/15/B/ST2/02537 and 2015/18/M/ST2/00125, 2015/19/N/ST2 /

43

01689), the Foundation for Polish Science — MPD program, co-financed by the European Union withinthe European Regional Development Fund, the Federal Agency of Education of the Ministry of Ed-ucation and Science of the Russian Federation (SPbSU research grant 11.38.242.2015), the RussianAcademy of Science and the Russian Foundation for Basic Research (grants 08-02-00018, 09-02-00664and 12-02-91503-CERN), the Ministry of Science and Education of the Russian Federation, grant No.3.3380.2017/4.6, the National Research Nuclear University MEPhI in the framework of the Russian Aca-demic Excellence Project (contract No. 02.a03.21.0005, 27.08.2013), the Ministry of Education, Cul-ture, Sports, Science and Technology, Japan, Grant-in-Aid for Scientific Research (grants 18071005,19034011, 19740162, 20740160 and 20039012), the German Research Foundation (grant GA 1480/2-2),the EU-funded Marie Curie Outgoing Fellowship, Grant PIOF-GA-2013-624803, the Bulgarian NuclearRegulatory Agency and the Joint Institute for Nuclear Research, Dubna (bilateral contract No. 4418-1-15/17), Bulgarian National Science Fund (grant DN08/11), Ministry of Education and Science of theRepublic of Serbia (grant OI171002), Swiss Nationalfonds Foundation (grant 200020117913/1), ETHResearch Grant TH-01 07-3 and the U.S. Department of Energy.

44

11. Published papers and preliminary results

In this appendix published papers, submitted papers, and new preliminary results obtained since October2016 are listed.

11.1. Published papers

1. Results on transverse momentum and multiplicity fluctuations of non-identified hadrons in p+p at20–158 GeV/c [20]

2. Results on two-particle correlations of non-identified hadrons in azimuthal angle and pseudo-rapidity in p+p at 20–158 GeV/c [41]

3. Results on π± differential yields from the surface of the T2K replica target for incoming 31 GeV/cprotons [56]

4. Results on ρ0, K∗0 ω production in π−+C interactions at 158 and 350 GeV/c [68]

11.2. Submitted papers

1. Results on π±, K±, (anti-)proton production in p+p at 20–158 GeV/c; based on information fromdE/dx and tof -dE/dx [78]; submitted to EPJC

11.3. New preliminary results

1. p+p collisions at 13, 20, 31, 40, 80, and 158 GeV/c

a) φ meson spectra and yields in p+p at 40–158 GeV/c [8, 11, 12]

2. Be+Be collisions at 13A, 19A, 30A, 40A, 75A, and 150A GeV/c

a) Charged kaon spectra in Be+Be at 30A–150A GeV/c; based on information from tof -dE/dx [7,8, 9, 10, 11, 12]

b) Multiplicity and forward energy fluctuations of negatively charged hadrons in Be+Be at 19A–150A GeV/c [15, 16, 17, 11]

c) Pseudorapidity dependence of fluctuations of non-identified hadrons in Be+Be at 150A GeV/c [32]

d) Protons intermittency in Be+Be at 150A GeV/c [34]

e) Two-particle correlations of non-identified hadrons in azimuthal angle and pseudo-rapidity inBe+Be at 19A–150A GeV/c [40]

3. Ar+Sc collisions at 13A, 19A, 30A, 40A, 75A, and 150A GeV/c

a) Charged kaon spectra and yields in Ar+Sc at 30A, 40A and 75A GeV/c; based on informationfrom dE/dx [14, 12]

4. p+C collisions at 31 GeV/c (thin target and T2K replica target)

45

a) Measurements of π±, K± and proton yields from the surface of the T2K replica target forincoming 31 GeV/c protons [58]

5. π−+C collisions at 158 and 350 GeV/c

a) Identified spectra of K±, protons and anti-protons [72]

A. Details on Vertex Detector

A.1. Shine data structure

With the introduction of the silicon pixel vertex detector SAVD, a new data member “Silicon” was addedto the Shine evt::raw and evt::proc data structures. The name “Silicon” was chosen rather than “SAVD”to make it more generic and allow other potential future silicon-based detectors to share the same datastructure. There is currently no “Silicon” data member in evt::rec or evt::sim, as the SAVD is utilizingclasses created for TPC clusters and tracks. It may be desirable that these classes at some point are slightlymodified to take into account the different properties of gas and silicon detectors.

evt::raw::Silicon contains a list of all silicon sensors. A sensor may be retrieved either through its hard-ware address or by its combination of physical station, ladder and sensor location.

evt::raw::SiliconSensor contains a list of all frames on a sensor. A time frame is one of several “shots” ofthe same event. The actual event data may be contained in one or several such frames depending on thetime offset between data read-out and trigger arrival. A time frame may be retrieved through its sequential(counter) number.

evt::raw::SiliconFrame contains a list of all fired pixels of a frame. The time and trigger information forthe frame can be retrieved. The fired pixels can be retrieved as a list.

evt::raw::SiliconPixel contains the line and column number of the pixel within a sensor. There is no datamember that indicates whether or not it fired; its mere presence in the list indicates that it fired.

evt::proc::Silicon contains a list of all silicon sensors, as well as all tracks and clusters detected by any ofthese sensors. A sensor may be retrieved either through its hardware address or by the physical station,ladder and sensor location.

evt::proc::SiliconSensor contains a list of fired pixels of a “merged frame”. A “merged frame” is thecombination of one or several time frames judged to contain the actual event data. It also contains lists ofall clusters and tracks detected by this sensor.

A.2. Readout upgrade

After detailed analysis of the data collected during the November and December run in 2016, it was clearthat the readout had some issues, and that there was a need for optimization. In cooperation with the IKFFrankfurt group, a system upgrade was prepared. The new setup was intended to be ready for the autumnruns in 2017.

The readout upgrade consisted mainly of firmware change in the FPGAs on all TRBV3 boards, introduc-tion of a common clock distribution unit and also a software upgrade on the SAVD server.

46

Figure 38: Upgraded SAVD Busy box circuit diagram.

Compared to the setup presented in Ref. [79], the Busy box for SAVD integration with the Central DAQsystem was also upgraded. It is designed to use the Arduino Nano board connected on top of a custommade board with 2 NIM outputs (2 TTL to NIM interfaces) and a NIM input (NIM to TTL interface).The board is powered by 5V DC through a USB connector. It has a DC-DC voltage converter to get -5Vneeded for NIM interfacing and a new R-S type flip-flop unit for setting the busy signal immediately aftertrigger arrival. The circuit diagram of the new Busy box interface is presented in Fig. 38.

For the readout upgrade, a common clock distribution unit was introduced to provide synchronizationbetween TRBv3 boards. Boards now have the same flavour of firmware as the central FPGAs. Allperipheral FPGAs also have common firmware which in contrast to the previous set-up, where one of theFPGAs had a special firmware for counting incoming triggers. Now all FPGAs have this feature. Thenew firmware ensures fast and predictable trigger marking in frames containing Mimosa-26 sensor data.The readout from boards is performed in parallel. This solution has better scalability features and bettertolerance to system malfunction. If something happens in one of the TRBv3 boards, the other branchwill still work correctly. An alternative solution under consideration was to join the readout and send theframes from a single TRBv3 only. In such a setup the boards work in master/slave mode in completesynchronization of readout with additional communication by fibre optic link between boards. This setuprequires that the central FPGA of the slave unit has a different firmware. However, this configuration stillhas problems in the setup assembled on the test line of the NA61/SHINE experiment and needs morework. Hence, the independent readout mode was chosen for the autumn runs. The new readout setup ispresented in Fig. 39.

47

TRBv3 x2

NET

CERN

NETWORK

NA61VDDAQ

p4p1: 192.168.1.1

p4p2: 192.168.2.1

192.168.1.2

Jura PositiveX (TRB3D1) (107) S/N: 107

Saleve NegativeX (TRB3D2) (45) S/N: 166

Jura armPositiveX

Saleve armNegativeX

Sensor0,1

Front EndBoard

ConverterBoard

NIM TOLVTTL

CONVERTER

UDP PORT:50107

UDP PORT:50045

MT Acc. signal Trig

ger

Cnt.

Rese

t

eth0: na61vddaq.cern.ch128.141.148.137

em1:192.168.3.10 (AUTO DHCP)

NA61CONVCentral DAQ

TRBNET

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p1p1:192.168.0.1

Slow control

BUSYBOX

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PowerSupply+48VDC, +5VDC:192.168.0.100Piezo motor driver:192.168.0.102Thermoregulator:192.168.0.103

DDL-LINKS(TPC,PSD)

VME to USB (BPD, TOF)

Other detectors

port: 20000

Busy

192.168.2.2

Switch

Commonclock

distrib. unit

0x8450 (Central FPGA) - trb3_central_cts_mvd_20170510.bit

0xd450 - trb3_periph_mvd_20170509_doublemarkerword.bit




0x8070 (Central FPGA) - trb3_central_cts_mvd_20170510.bit





CASTOR

Trigger signal

Figure 39: Schematic diagram of the upgraded readout of the NA61/SHINE SAVD

A.3. SAVD geometry tuning

The alignment of the SAVD was done using track candidates found by the combinatorial method withdata taken for which the magnetic field was off. The purpose of geometry tuning is to find the correctionsfor the sensor positions (each sensor has 6 degrees of freedom; offsets from the nominal geometry in x,y and z position and rotation along x, y and z axes). For correct geometry alignment, hits produced bythe same particle should lie on a straight line. In order to define the collinearity of three hits, the variable“dev” was introduced:

devx =x1 + x3

2− x2 (4)

devy =y1 + y3

2− y2 (5)

The meaning of the variable is pictured in Fig. 40. For properly reconstructed tracks, the distribution ofthe “dev” variable should show a narrow correlation peak centred at zero. The sensor naming conventionused in this section is presented in Fig. 41.

Figure 40: The definition of the “dev” variable used for geometry tuning.

The alignment algorithm is based on the MIGRAD minimiser from the MINUIT [80] package. In orderto find the optimal alignment paramters the Variable Metric method is used to minmize the deviationfunction.The geometry tuning was performed separately for the Jura and Saleve arms. The algorithm consists oftwo main parts. Initial tuning is done as follows:

(i) fix the position of the Vds1_0 sensor;

48

Figure 41: The naming convention of the SAVD sensors.

(ii) loop over track candidates reconstructed from hits registered by the following sensors: Vds1_0,Vds2_0, Vds3_0, Vds4_0;

(iii) calculate the sum of “dev” values for hits from stations: Vds1_0, Vds2_0, Vds3_0 and: Vds2_0,Vds3_0, Vds4_0;

(iv) minimise the obtained sum using the MINUIT package by changing the offsets and rotation correc-tions of included sensors;

(v) fix the position of Vds2_0, Vds3_0, Vds4_0 sensors;

(vi) do the same minimisation for track candidates reconstructed from hits registered by the followingsensors: Vds1_0, Vds2_0, Vds3_1, Vds4_1;

(vii) fix the position of Vds3_1, Vds4_1;

(viii) do the analogous minimisation for track candidates consisting of hits from stations: Vds1_0, Vds2_0,Vds3_0, Vds4_2 and fix the position of the Vds4_2 sensor;

(ix) do the analogous minimisation for track candidates consisting of hits from stations: Vds1_0, Vds2_0,Vds3_1, Vds4_3 and fix the position of the Vds4_3 sensor.

The final tuning was done by using all sensors together. The algorithm is the following:

(i) loop over all track candidates and calculate the distributions of residuals between fitted tracks andhits from all stations;

(ii) minimize the sum of estimators of mean and standard deviation values for all the distributions usingthe MINUIT package by slightly changing the position of sensors.

In order to estimate the improvement of tracking resolution after geometry tuning, the distributions ofresiduals between hits and fitted tracks for initial and tuned geometry were compared. Example distribu-tions are shown in Fig. 42 for x (left) and y (right) coordinates, respectively.

49

resX_Vds2_down1 [mm]0.02− 0.015− 0.01− 0.005− 0 0.005 0.01 0.015 0.02

coun

ts

0

50

100

150

200

250

300

350

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resY_Vds4_down1 [mm]0.03− 0.02− 0.01− 0 0.01 0.02 0.03

coun

ts

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100

150

200

250before geometry tuningafter geometry tuning

Figure 42: Left: The distribution of x residuals between fitted tracks and hits registered by the Vds2_0 sensor inthe Jura arm. The improvement factor calculated from formula (6) is 20%. Right: The distribution of y residualsbetween fitted tracks and hits registered by the Vds4_0 sensor in the Saleve arm. The improvement factor calcu-lated from formula (6) is 22%. Distributions before and after final geometry tuning are shown by black and redhistograms, respectively.

To all the distributions Gaussian functions were fitted and standard deviation values (σ) were comparedbetween distributions obtained before and after final geometry tuning. The improvement factor was cal-culated from the following formula:

improvement =σoldGeometry − σnewGeometry

σoldGeometry· 100% (6)

The average values of the improvement factor are presented in Table 7.

Sensors used for track reconstructionImprovement FactorSaleve Jura

Vds1_0, Vds2_0, Vds3_0, Vds4_0 20.23% 19.31%Vds1_0, Vds2_0, Vds3_1, Vds4_1 20.24% 13.05%Vds1_0, Vds2_0, Vds3_0, Vds4_2 1.07% –Vds1_0, Vds2_0, Vds3_1, Vds4_3 19.77% 3.82%

Table 7: Average values of improvement factor calculated from formula (6).

A.4. Matching between SAVD and TPC tracks

As already described in Sec. 5.2 the matching procedure consists of three steps:

(i) since tracks are not affected by the magnetic field in the y direction all SAVD tracks are combinedwith VTPC tracks and for each SAVD–VTPC track pair the difference of the tracks slopes in the ycoordinate day, is calculated. The distribution of day shows a sharp peak on a large combinatorialbackground. A ± 5σ cut around this peak is applied for the pre-selection of SAVD and TPC trackpairs that potentially match.

50

Figure 43: Left: Difference in y coordinate of SAVD and TPC tracks (dy) versus y at the matching plane. Right:example of the projection of distribution of dy versus y onto the dy coordinate for −7mm < y < −2.5 mm (singleslice).

(ii) For a given track pair the TPC total momentum is assigned to the SAVD track. This allows toextrapolate the SAVD track to the VTPC front surface where both are matched in x, y (z is matchedby construction as it defines the matching plane) coordinates and the difference of the track positiondx and dy are calculated. Figure 43 (left) shows the distribution of dy versus y of Saleve sideSAVD tracks matched to Jura side tracks of VTPC1. Because the average value of dy depends on y,narrow ranges of y of the distribution are projected onto dy. The projected distributions (slices) arethen fitted with a sum of a second order polynomial which describes the background related to falsematchings and the Gaussian peak that accounts for the true matchings. The example of a single sliceis shown in Fig. 43 (right). The dependence of the fitted mean (〈dy〉) and variance (σdy) on y arethen fitted with a third order polynomial function. The result of this fit is shown as red (〈dy〉 (y)) andblue lines (± σdy(y)) in Fig. 43 (left). A similar procedure was followed for dx versus z matching.Both for dy versus y and dx versus z separate distributions were constructed and sliced for Jura -Jura, Jura - Saleve, Saleve - Saleve and Saleve - Jura track combinations, separately for VTPC1 andVPTC2.

(iii) The values of 〈dy〉, σdy and 〈dx〉, σdx obtained from the fits are used to apply elliptic cuts to selectthe right matchings.

Figure 44 shows the distribution of the difference of SAVD and TPC momentum components dpx anddpz calculated at the matching plane for SAVD and TPC track combinations that passed the cut on day(blue) and with the elliptical 4σ cuts on dx and dy (red). It can be seen that after the dx and dy cuts thedistributions are practically free of background. An additional test of the matching procedure is shown inFig. 6 (right) of Sec. 5.2.

Currently, about 60% of SAVD tracks are matched to a VTPC track. According to Geant4 simulations,

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Figure 44: Difference of momentum components dpx and dpz calculated at the matching plane for SAVD - TPCtrack combinations that passed the cut on day (blue) and after additional elliptical 4σ cuts on dx and dy (red).

about 70% of SAVD tracks should have a matching with a VTPC track. The remaining tracks either missthe VTPC acceptance, or decay before reaching the VTPC.

52

References

[1] N. Antoniou et al., [NA61/SHINE Collab.], “Study of hadron production in hadron nucleus and nucleus nucleuscollisions at the CERN SPS,” 2006. CERN-SPSC-2006-034.

[2] A. Aduszkiewicz et al., [NA61/SHINE Collab.], “Feasibility Study for the Measurement of Nuclear Fragmentation CrossSections with NA61/SHINE at the CERN SPS,” 2017. Addendum to the NA61/SHINE proposal submitted to the SPSCon October 3, 2017.

[3] N. Abgrall et al., [NA61/SHINE Collab.] JINST 9 (2014) P06005, arXiv:1401.4699 [physics.ins-det].

[4] A. Aduszkiewicz, [NA61/SHINE Collab.], “Report from the NA61/SHINE experiment at the CERN SPS,” Tech. Rep.CERN-SPSC-2016-038. SPSC-SR-197, CERN, Geneva, Oct, 2016. https://cds.cern.ch/record/2222876.

[5] Y. Ali et al. Acta Phys. Pol. B44 (2013) 2019–2034, arXiv:hep-ph/9909407 [hep-ph].

[6] A. Aduszkiewicz et al., [NA61/SHINE Collab.], “Beam momentum scan with Pb+Pb collisions at the CERN SPS,” 2015.Addendum to the NA61/SHINE proposal submitted to the SPSC on October 14, 2015.

[7] A. Aduszkiewicz, [NA61/SHINE Collab.], “Recent results from NA61/SHINE,” in XXVI international conference onultrarelativistic heavy-ion collisions "Quark Matter 2017", Chicago, USA February 5-11, 2017. 2017.arXiv:1704.08071 [hep-ex]. http://inspirehep.net/record/1596898/files/arXiv:1704.08071.pdf.

[8] M. Mackowiak-Pawlowska, [NA61/SHINE Collab.], “Recent results from NA61/SHINE,” in 9th Workshop "ExcitedQCD" 2017 Sintra, Portugal, May 7-13, 2017. 2017. arXiv:1707.04735 [nucl-ex].http://inspirehep.net/record/1610347/files/arXiv:1707.04735.pdf.

[9] M. Kuich, [NA61/SHINE Collab.], talk at 2017 RHIC and AGS Annual Users’ Meeting,https://www.bnl.gov/aum2017/content/workshops/Workshop_1e/2_mkuich_BNL_slides.pdf.

[10] M. Kuich, [NA61/SHINE Collab.], talk at European Physical Society Conference on High Energy Physics (EPS-HEP2017), https://indico.cern.ch/event/466934/contributions/2588338/attachments/1487755/2311337/EPS-HEP_2017_mkuich_slides.pdf.

[11] T. Susa, [NA61/SHINE Collab.], talk at Strangeness in Quark Matter (SQM 2017), https://indico.cern.ch/event/576735/contributions/2565900/attachments/1490283/2316205/susaNA61.pdf.

[12] S. Pulawski, [NA61/SHINE Collab.], talk at Critical Point and Onset of Deconfinement (CPOD 2017),https://indico.bnl.gov/getFile.py/access?contribId=97&sessionId=1&resId=0&materialId=slides&confId=2866.

[13] M. Gazdzicki and M. I. Gorenstein Acta Phys.Polon. B30 (1999) 2705, arXiv:hep-ph/9803462 [hep-ph].

[14] M. Lewicki, [NA61/SHINE Collab.], talk at Critical Point and Onset of Deconfinement (CPOD 2017),https://indico.bnl.gov/getFile.py/access?contribId=15&sessionId=3&resId=0&materialId=slides&confId=2866.

[15] A. Seryakov and E. Andronov, [NA61/SHINE Collab.], talk at Workshop on Particle Correlations and Femtoscopy(WPCF 2017), https://indico.cern.ch/event/539093/contributions/2568061/attachments/1475320/2284948/Seryakov.pdf.

[16] A. Seryakov, [NA61/SHINE Collab.], talk at International School of Subnuclear Physics,http://www.emfcsc.infn.it/issp2017/newtalents/talkSeryakov.pdf.

[17] K. Grebieszkow, [NA61/SHINE Collab.], talk at European Physical Society Conference on High Energy Physics(EPS-HEP 2017), https://indico.cern.ch/event/466934/contributions/2588329/attachments/1487704/2311258/EPS_HEP_KGrebieszkow_2017.pdf.

[18] V. V. Begun, M. Gazdzicki, M. I. Gorenstein, M. Hauer, V. P. Konchakovski, and B. Lungwitz Phys. Rev. C76 (2007)024902, arXiv:nucl-th/0611075 [nucl-th].

[19] V. V. Begun, M. Gazdzicki, and M. I. Gorenstein Phys. Rev. C78 (2008) 024904, arXiv:0804.0075 [hep-ph].

[20] A. Aduszkiewicz et al., [NA61/SHINE Collab.] Eur. Phys. J. C76 no. 11, (2016) 635, arXiv:1510.00163 [hep-ex].

53

https://cds.cern.ch/record/2287004?ln=en

https://cds.cern.ch/record/2287004?ln=en

http://dx.doi.org/10.1088/1748-0221/9/06/P06005

http://arxiv.org/abs/1401.4699

https://cds.cern.ch/record/2222876

http://dx.doi.org/10.5506/APhysPolB.44.2019

http://arxiv.org/abs/hep-ph/9909407



http://inspirehep.net/record/1596898/files/arXiv:1704.08071.pdf


http://inspirehep.net/record/1610347/files/arXiv:1707.04735.pdf

https://www.bnl.gov/aum2017/content/workshops/Workshop_1e/2_mkuich_BNL_slides.pdf

https://indico.cern.ch/event/466934/contributions/2588338/attachments/1487755/2311337/EPS-HEP_2017_mkuich_slides.pdf

https://indico.cern.ch/event/466934/contributions/2588338/attachments/1487755/2311337/EPS-HEP_2017_mkuich_slides.pdf

https://indico.cern.ch/event/576735/contributions/2565900/attachments/1490283/2316205/susaNA61.pdf

https://indico.cern.ch/event/576735/contributions/2565900/attachments/1490283/2316205/susaNA61.pdf

https://indico.bnl.gov/getFile.py/access?contribId=97&sessionId=1&resId=0&materialId=slides&confId=2866





https://indico.cern.ch/event/539093/contributions/2568061/attachments/1475320/2284948/Seryakov.pdf

https://indico.cern.ch/event/539093/contributions/2568061/attachments/1475320/2284948/Seryakov.pdf

http://www.emfcsc.infn.it/issp2017/newtalents/talkSeryakov.pdf

https://indico.cern.ch/event/466934/contributions/2588329/attachments/1487704/2311258/EPS_HEP_KGrebieszkow_2017.pdf

https://indico.cern.ch/event/466934/contributions/2588329/attachments/1487704/2311258/EPS_HEP_KGrebieszkow_2017.pdf

http://dx.doi.org/10.1103/PhysRevC.76.024902


http://arxiv.org/abs/nucl-th/0611075



http://dx.doi.org/10.1140/epjc/s10052-016-4450-9


[21] F. Becattini, J. Manninen, and M. Gazdzicki Phys.Rev. C73 (2006) 044905, arXiv:hep-ph/0511092 [hep-ph].

[22] M. Gazdzicki, M. Gorenstein, and P. Seyboth Int.J.Mod.Phys. E23 (2014) 1430008, arXiv:1404.3567 [nucl-ex].

[23] M. Gazdzicki, M. Gorenstein, and P. Seyboth Acta Phys.Polon. B42 (2011) 307–351, arXiv:1006.1765 [hep-ph].

[24] G. Baym Physica A 96 (1979) 131–135.

[25] T. Celik, F. Karsch, and H. Satz Phys. Lett. 97B (1980) 128–130.

[26] M. Braun and C. Pajares Nucl. Phys. B390 (1993) 542–558.

[27] N. Armesto, M. A. Braun, E. G. Ferreiro, and C. Pajares Phys. Rev. Lett. 77 (1996) 3736–3738,arXiv:hep-ph/9607239 [hep-ph].

[28] L. Cunqueiro, E. G. Ferreiro, F. del Moral, and C. Pajares Phys. Rev. C72 (2005) 024907, arXiv:hep-ph/0505197[hep-ph].

[29] J. M. Maldacena Int. J. Theor. Phys. 38 (1999) 1113–1133, arXiv:hep-th/9711200 [hep-th]. [Adv. Theor. Math.Phys.2,231(1998)].

[30] E. Shuryak Prog. Part. Nucl. Phys. 62 (2009) 48–101, arXiv:0807.3033 [hep-ph].

[31] S. Lin and E. Shuryak Phys. Rev. D79 (2009) 124015, arXiv:0902.1508 [hep-th].

[32] E. Andronov, [NA61/SHINE Collab.], talk at Workshop on Particle Correlations and Femtoscopy (WPCF 2017),https://indico.cern.ch/event/539093/contributions/2568087/attachments/1475198/2284685/EA_wpcf_forEA.pdf.

[33] M. Gorenstein and M. Gazdzicki Phys. Rev. C84 (2011) 014904.

[34] N. Davis, [NA61/SHINE Collab.], talk at Critical Point and Onset of Deconfinement (CPOD 2017), https://indico.bnl.gov/getFile.py/access?contribId=37&sessionId=2&resId=0&materialId=slides&confId=2866.

[35] M. Gazdzicki, [NA61/SHINE Collab.], talk at Critical Point and Onset of Deconfinement (CPOD 2017),https://indico.bnl.gov/getFile.py/access?contribId=101&sessionId=1&resId=2&materialId=slides&confId=2866.

[36] N. G. Antoniou, F. K. Diakonos, A. S. Kapoyannis, and K. S. Kousouris Phys. Rev. Lett. 97 (2006) 032002,arXiv:hep-ph/0602051 [hep-ph].

[37] K. Werner Nucl. Phys. Proc. Suppl. 175-176 (2008) 81–87.

[38] B. Efron The annals of Statistics (1979) 1–26.

[39] W. J. Metzger, “Estimating the uncertainties of factorial moments,” Tech. Rep. HEN-455, Experimental High EnergyPhysics Group, University of Nijmegen, Nijmegen, The Netherlands, June, 2004.

[40] B. Maksiak, [NA61/SHINE Collab.], talk at Critical Point and Onset of Deconfinement (CPOD 2017),https://indico.bnl.gov/getFile.py/access?contribId=55&sessionId=3&resId=0&materialId=slides&confId=2866.

[41] A. Aduszkiewicz et al., [NA61/SHINE Collab.] Eur. Phys. J. C77 no. 2, (2017) 59, arXiv:1610.00482 [nucl-ex].

[42] V. Vovchenko, V. V. Begun, and M. I. Gorenstein Phys. Rev. C93 no. 6, (2016) 064906, arXiv:1512.08025[nucl-th].

[43] C. Alt et al., [NA49 Collab.] Phys. Rev. C78 (2008) 044907, arXiv:0806.1937 [nucl-ex].

[44] C. Alt et al., [NA49 Collab.] Phys. Rev. C68 (2003) 034903, arXiv:nucl-ex/0303001 [nucl-ex].

[45] C. Alt et al., [NA49 Collab.] Phys. Rev. C75 (2007) 044901, arXiv:nucl-ex/0606026 [nucl-ex].

[46] L. Adamczyk et al., [STAR Collab.] Phys. Rev. Lett. 112 no. 16, (2014) 162301, arXiv:1401.3043 [nucl-ex].

[47] V. Klochkov and I. Selyuzhenkov, [CBM Collab.] GSI Scientific Report 2015 :DOI:10.15120/GR-2016-1,MU-NQM-CBM-22 https://repository.gsi.de/record/194850 (2016) 8.

54



http://dx.doi.org/10.1142/S0218301314300082




http://dx.doi.org/10.1016/0378-4371(79)90200-0

http://dx.doi.org/10.1016/0370-2693(80)90564-X

http://dx.doi.org/10.1016/0550-3213(93)90467-4

http://dx.doi.org/10.1103/PhysRevLett.77.3736





http://dx.doi.org/10.1023/A:1026654312961

http://arxiv.org/abs/hep-th/9711200

http://dx.doi.org/10.1016/j.ppnp.2008.09.001


http://dx.doi.org/10.1103/PhysRevD.79.124015


https://indico.cern.ch/event/539093/contributions/2568087/attachments/1475198/2284685/EA_wpcf_forEA.pdf

https://indico.cern.ch/event/539093/contributions/2568087/attachments/1475198/2284685/EA_wpcf_forEA.pdf








http://dx.doi.org/10.1016/j.nuclphysbps.2007.10.012



http://dx.doi.org/10.1140/epjc/s10052-017-4599-x








http://arxiv.org/abs/nucl-ex/0303001


http://arxiv.org/abs/nucl-ex/0606026

http://dx.doi.org/10.1103/PhysRevLett.112.162301(2014), 10.1103/PhysRevLett.112.162301


https://repository.gsi.de/record/194850

[48] I. Selyuzhenkov and S. Voloshin Phys. Rev. C77 (2008) 034904, arXiv:0707.4672 [nucl-th].

[49] V. Gonzalez, J. Onderwaater, and I. Selyuzhenkov, [ALICE Collab.] GSI Scientific Report 2015:DOI:10.15120/GR-2016-1, MU-NQM-ALICE-11 https://repository.gsi.de/record/194850 (2016) 23.

[50] J. Onderwaater, I. Selyuzhenkov, and V. Gonzalez https://github.com/jonderwaater/FlowVectorCorrections(2015) available under GNU General Public License v.3.

[51] A. Rybicki and A. Szczurek Phys.Rev. C87 (2013) 054909.

[52] A. Rybicki and A. Szczurek Phys.Rev. C75 (2007) 054903.

[53] A. Szczurek, M. Kiełbowicz, and A. Rybicki Phys.Rev. C95 (2017) 024908.

[54] A. Rybicki Acta Phys. Polon. B42 (2011) 867.

[55] K. Mazurek, A. Szczurek, C. Schmitt, and P. N. Nadtochy arXiv:1708.03716 [nucl-th].

[56] N. Abgrall et al., [NA61/SHINE Collab.] Eur. Phys. J. C76 no. 11, (2016) 617, arXiv:1603.06774 [hep-ex].

[57] T. Vladisavljevic, [T2K Collab.], “Estimating the T2K Neutrino Flux with NA61/SHINE 2009 Replica-Target Data,”2017.https://meetings.triumf.ca/indico/event/6/session/31/contribution/160/material/poster/0.pdf.Poster at the NuInt workshop, 25-30 June 2017, Toronto, Ontario, Canada.

[58] M. Pavin, “Measurements of hadron yields from the T2K replica target in the NA61/SHINE experiment for neutrino fluxprediction in T2K,” 2017. PhD. Thesis, University of Paris VI, France.

[59] G. Battistoni et al. AIP Conf.Proc. 896 (2007) 31.

[60] A. Ferrari, P. R. Sala, A. Fasso, and J. Ranft, “FLUKA: A multi-particle transport code (Program version 2005),” 2005.CERN-2005-010, SLAC-R-773, INFN-TC-05-11.

[61] T. Bohlen, F. Cerutti, M. Chin, A. Fassò, A. Ferrari, P. Ortega, A. Mairani, P. Sala, G. Smirnov, and V. VlachoudisNuclear Data Sheets 120 no. 0, (2014) 211 – 214.

[62] S. Agostinelli et al., [GEANT4 Collab.] Nucl. Instrum. Meth. A506 (2003) 250.

[63] J. Allison et al., [GEANT4 Collab.] IEEE Trans.Nucl.Sci. 53 (2006) 270.

[64] J. Allison et al., [GEANT4 Collab.] Nucl. Instrum. Meth. A835 (2016) 186–225.

[65] R. Acciarri et al., [DUNE Collab.] arXiv:1601.05471 [physics.ins-det].

[66] A. S. Carroll et al. Phys. Lett. 80B (1979) 319–322.

[67] S. Johnson PoS ICHEP2016 (2016) 944.

[68] A. Aduszkiewicz et al., [NA61/SHINE Collab.] Eur. Phys. J. C77 (2017) 626, arXiv:1705.08206 [nucl-ex].

[69] S. Ostapchenko EPJ Web Conf. 52 (2013) 02001.

[70] F. Riehn et al. PoS (ICRC2015) (2015) 558, arXiv:1510.00568.

[71] A. Aab et al., [Pierre Auger Collab.] arXiv:1604.03637 [astro-ph.IM].

[72] R. R. Prado, [NA61/SHINE Collab.], “Measurements of Hadron Production in Pion-Carbon Interactions withNA61/SHINE at the CERN SPS,” in Proceedings, 35th International Cosmic Ray Conference (ICRC 2017): Bexco,Busan, Korea, July 12-20, 2017. 2017. arXiv:1707.07902 [hep-ex].

[73] A. Herve for the NA61/SHINE Coll. to appear in Proc. 34th ICRC (2015) .

[74] T. Pierog and K. Werner Phys. Rev. Lett. 101 (2008) 171101, arXiv:astro-ph/0611311 [astro-ph].

[75] Physics Reports 618 (2016) 1 – 37. Review of the theoretical and experimental status of dark matter identification withcosmic-ray antideuterons.

55



https://repository.gsi.de/record/194850

https://github.com/jonderwaater/FlowVectorCorrections






http://dx.doi.org/10.1140/epjc/s10052-016-4440-y


https://meetings.triumf.ca/indico/event/6/session/31/contribution/160/material/poster/0.pdf

http://dx.doi.org/10.1063/1.2720455

http://dx.doi.org/http://dx.doi.org/10.1016/j.nds.2014.07.049

http://dx.doi.org/10.1016/S0168-9002(03)01368-8

http://dx.doi.org/10.1109/TNS.2006.869826

http://dx.doi.org/10.1016/j.nima.2016.06.125


http://dx.doi.org/10.1016/0370-2693(79)90226-0

http://dx.doi.org/10.1140/epjc/s10052-017-5184-z


http://dx.doi.org/10.1051/epjconf/20125202001





http://arxiv.org/abs/astro-ph/0611311

http://dx.doi.org/10.1016/j.physrep.2016.01.002

[76] S. Johnson et al., [NA61/SHINE Collab.], “Hadron Production Measurements for Fermilab Neutrino Beams,” 2014.Addendum to the NA61/SHINE proposal submitted to the SPSC on October 14, 2014.

[77] L. Aliaga. Talk at the NA61/SHINE Beyond 2020 Workshop, University of Geneva, July 2017, slides athttps://indico.cern.ch/event/629968.

[78] A. Aduszkiewicz et al., [NA61/SHINE Collab.] to be published Eur. Phys. J. C (2017) , arXiv:1705.02467[nucl-ex].

[79] A. Aduszkiewicz, [NA61/SHINE Collab.], “Report from the NA61/SHINE experiment at the CERN SPS,” Oct, 2016.http://cds.cern.ch/record/2222876.

[80] F. James and M. Winkler, “MINUIT User’s Guide,” 2004.

56


https://indico.cern.ch/event/629968



http://cds.cern.ch/record/2222876

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