LHCf: stato e programmi

Oscar Adriani

CSN1,Torino, 27 settembre 2012

Introduction and contents Analyses

p0 paper accepted by PRD 900 GeV g paper published on PLB Short spot on other analyses

Arm1 preparation for 14 TeV Beam test at SPS (August-September 2012) Arm2 preparation for p/Pb 2013 run

LHCf: location and detector layout

44X0, 1.6 lint

INTERACTION POINT

IP1 (ATLAS)

Detector IITungsten

ScintillatorSilicon

mstrips

Detector ITungsten

ScintillatorScintillating

fibers140 m 140 m

n π0

γ

γ8 cm 6 cm

Front Counter Front Counter

Arm#1 Detector20mmx20mm+40mmx40mm4 X-Y SciFi tracking layers

Arm#2 Detector25mmx25mm+32mmx32mm4 X-Y Silicon strip tracking layers

π0 analysis: PT spectra for different rapidity bins“Measurement of forward neutral pion transverse momentum spectra for √s = 7TeV proton-proton collisions at LHC“‘Accepted’ by PRD

Type-I Type-II

Type-II at small tower

Type-II at large tower

Type-ILHCf-Arm1

Type-IILHCf-Arm1

LHCf-Arm1Data 2010

BG

Signal

Preliminary

•Large angle•Simple•Clean•High-stat.

•Small angle•large BG•Low-stat., but can cover•High-E•Large-PT

π0 analysis at √s=7TeVSubmitted to PRD (arXiv:1205.4578).

Type I π0 analysis procedure

Mass, energy and transverse momentum are reconstructed from the energies and impact positions of photon pairs measured by each calorimeter

Analysis Procedure • Standard photon reconstruction• Event selection

- one photon in each calorimeter- reconstructed invariant mass

• Background subtraction by using outer region of mass peak

• Unfolding for detector response. • Acceptance correction.

Dedicated part for π0 analysis

m 140= R

I.P.1

g1(E1)

g2(E2)

140m

R

Acceptance for π0 at LHCf-Arm1Validity check of unfolding method

• Remaining background spectrum is estimated using the sideband information, then the BG spectrum is subtracted from the spectrum obtained in the signal window.

• Raw distributions are corrected for detector responses by an unfolding process that is based on the iterative Bayesian method.(G. D’Agostini NIM A 362 (1995) 487)

• Detector response corrected spectrum is then corrected for acceptance

LHCf-Arm1√s=7TeV9.0<y<11.0

True EPOSUnfolded(by π0+EPOS)Unfolded(by π0+PYTHIA)

Measured EPOS

Acceptance and unfoldingSubmitted to PRD (arXiv:1205.4578).

π0 results: Data vs MC

π0 results: Data/MCSubmitted to PRD (arXiv:1205.4578).

Data/MC commented

dpmjet 3.04 & pythia 8.145 show overall agreement with LHCf data for 9.2<y<9.6 and pT <0.25 GeV/c, while the expected p0 production rates by both models exceed the LHCf data as pT becomes large

sibyll 2.1 predicts harder pion spectra than data, but the expected p0 yield is generally small

qgsjet II-03 predicts p0 spectra softer than LHCf data

epos 1.99 shows the best overall agreement with the LHCf data.

behaves softer in the low pT region, pT < 0.4GeV/c in 9.0<y<9.4 and pT <0.3GeV/c in 9.4<y<9.6

behaves harder in the large pT region.

<pT> distribution Three different approaches used to derive the average transverse momentum, ⟨pT⟩1. by fitting an empirical function

to the pT spectra in each rapidity range (exponential distribution based on a thermodynamical approach)

2. By fitting a gaussian distribution

3. by simply numerically integrating the pT spectra

Results of the three methods are in agreement and are compared with UA7 data and hadronic model predictions.

Two UA7 and LHCf experimental data show the same trend→ no evident dependence of <pT> on ECMS.

YBeam=6.5 for SPSYBeam=8.92 for7 TeV LHC

900 GeV inclusive g spectra“Measurement of zero degree single photon energy spectra for √s = 900 GeV proton-proton collisions at LHC“PLB 715 (2012) 298CERN-PH-EP-2012-048

Comparison wrt MC Models at 900 GeV

small-η

= Large tower

big-η =Small tower

g analysis: Comparison btw 900 GeV and 7 TeV spectra

Coverage of the photon spectra in the plane Feynman-X vs PT

small-η

= Large tower

big-η =Small tower

A jump back to g analysis: Comparison btw 900GeV and 7TeV spectra

Coverage of the photon spectra in the plane Feynman-X vs PT

900GeV vs. 7TeVwith the same PT region

900 GeV Small+large tower

small-η

= Large tower

big-η =Small tower

A jump back to g analysis: Comparison btw 900GeV and 7TeV spectra

Normalized by the number of entries in XF > 0.1 No systematic error is considered in both collision

energies.

XF spectra : 900GeV data vs. 7TeV data

Good agreement of XF spectrum shape between 900 GeV and 7 TeV. weak dependence of <pT> on ECMS

Preliminary

Data 2010 at √s=900GeV(Normalized by the number of entries in XF > 0.1)Data 2010 at √s=7TeV (η>10.94)

Coverage of the photon spectra in the plane Feynman-X vs PT

900GeV vs. 7TeVwith the same PT region

900 GeV Small+large tower

Neutron and K0 (very preliminary…) analyses

Why neutron measurement is important for CR physics

Auger hybrid analysis• event-by-event MC

selection to fit FD data (top plot)

• comparison with SD data vs MC (bottom plot)

• Clear muon excess in data even for Fe primary MC

The number of muons increases with the increase of the number of baryons! => importance of direct baryon measurement

Neutron Detection Efficiency and energy linearity

Efficiency at the offline shower triggerFlat efficiency >500GeV

%

Linear fitParabolic fit

Energy and Position Resolution

X Y

Neutron incident at (X,Y) = (8.5mm, 11.5mm) ~1mm position resolutionWeak dependence on incident energy

We are trying to improve the energy resolution by looking at the ‘electromagneticity’ of the event

K0 analysis

K0 Acceptance

Status of the LHCf preparation for 14 TeV

LHCf preparation for the 14 TeV p-p run

Calorimeter radiation hardening by replacing plastic scintillator with GSO Scintillator plates

3 mm 1mm thick scintillators Acrylic quartz light guides

construction and light yield uniformity test carried out in Japan SciFi

1 mm square fibers 1 mm GSO square bars No clad-core structure (GSO bar)

Attenuation and cross talk test carried out Acrylic light guide fiber quartz light guide fibers

Construction and light yield test carried out

Production and laboratory tests of the new scintillators in Japan is finished Beam test at Ion facility (HIMAC) has been done in June 2012 Arm1 has been re-assembled in Florence starting from end of June Same procedure will be followed in 2013 for the Arm2 detector

Upgrade of the silicon positioning measurement system Rearranging Silicon layers for independent precise energy measurement Increase the dynamic range to reduce saturation effects

Beam test at the SPS Long beam test has been conducted from August 17th to

September 4th in the H2 SPS area Muons, 50-250 GeV electrons, 350 GeV protons More than 1 TB of data

Main goals: Energy scale of upgraded Arm1 detector Check of energy scale of not upgraded Arm2 for the p/Pb

run Test of the solution to improve the silicon saturation for 14

TeV run Check of the temperature dependence of the absolute

energy scale both for Arm1 and Arm2 Very successful beam test!

Test of new silicon pattern bonding Problem: saturation of the silicon electronics for Eg

> 1.5 TeV Pace3 dynamic range is not enough to sustain such

a huge energy release Not a problem for 3.5+3.5 TeV runs

Software corrections based on the different PACE3 samples allow to increase saturation up to 2.5/3 TeV

Become an issue for 7+7 TeV run We will change the silicon sensors position to improve

the silicon only energy resolution…. We developed a new idea to hardware improve the

saturation level

Silicon sensor

Not used

Normal configuration

New configuration

Readout

ReadoutFloating

Readout

ReadoutGround

Arm2 detector New silicon

Pb (40mm)e-, 200 GeV/c

Different silicon bonding scheme

The beam test setup

80 mm implant pitch160 mm readout pitch

New Silicon Module results (Quick analysis)

Clearly the pulse height in the region of new configuration were reduced by a factor of 1.5 ~ 1.7 (we could naively expect 2)

The modification works fine to enlarge the silicon dynamic range

#Strip

Normal NewSilicon Lateral distribution

Histogram of peak values

Arm2 Pi0 Mass v.s. Temperature at LHC

15-Mar.-2012 /31-Mar-2012

Remember the 3.8% Mass Shift that was longly discussed….

Temperature test and control at SPS

During the beam test, we carefully controlled the temperature of the detector with a chiller

We waited for some hours until the temperature was very stable (< 0.1 degree / hour)

Chiller

Water

Temperature test (Arm2) Check the temperature dependency of the energy

scale by changing the chiller temperature to 18, 23, 28, 33 degrees.

18

23

28

33

Chiller temperature

Thermometer in Arm2

Energy scale temperature dependence(Arm2)

The temperature coefficient is consistent with the R7400U catalog value (-0.20% /C)

We could confirm that there is a dependence of energy scale on the temperature.Compatible with 3.8% mass shift???? To be checked

Re-installation for the p/Pb run Arm2 will be re-installed in the TAN during the technical

stop foreseen at the end of the p/p run We have modified the LHCf support structure and cabling to

significantly reduce the installation required time The procedure for reinstallation  has been carefully

discussed in the LTEX meetings and is ready Checked with RP RP gave green light

We are continuing discussions with ATLAS for trigger and data exchange, to get the maximum physics outcome for the data, following the LHCC recommendation

Arm2 will be brought back to Florence after the p/Pb run completion (special transport will be necessary because of the slight radioactivity)

Miscellanea…. I Possibility to use LIGHT IONS in LHC from

2016/2017? Light Ion source setup is ongoing because of SPS

interest RHIC run in 2015/2016 was under discussion… Please stand by a little bit to see how things are

evolving!!!! We have a new Japanese expert post doc that will

stay in Italy for 2 years paid by Japan

Miscellanea II:Working together with MC model developers

Since the first paper we are in strict connection with model developers (EPOS,QGSJET, SYBILL etc.) We have taken part to several meetings/workshops We are contributing to the tuning of the model to LHCf

data We are also involved in the MCPLOTS/RIVET project

(http://mcplots.cern.ch) a simple browsable repository of MC (Monte Carlo) plots

comparing High Energy Physics event generators to a wide variety of available experimental data, for tuning and reference purposes

Miscellanea III:Working together with other LHC MC contacts

Since last year we are involved in one of the WG of the MC4LHC project

A new WG is now starting to focus on astroparticle physics connection with contact persons from each LHC experiments A. Tricomi, T. Sako Set up and organize a workshop

Miscellanea IV: LHCf computing Lo scorso anno abbiamo presentato un piccolo modello di calcolo per far fronte

alle esigenze di simulazione e ricostruzione di LHCf per il run p-Pb di cui siamo responsabili I referee ci hanno finanziato una parte di quello richiesto rimandando a

quest’anno la seconda parte a fronte di stime più precise per consentirci la produzione dei plot per la LOI

Il data set per la LOI è stato prodotto interamente in Italia e le tre macchine acquistate sono state fondamentali

Abbiamo fatto i primi test di simulazione completa con p-Pb 500 KB per evento e 570 sec/evento con la simulazione completa 20 KB per evento e 22 sec/evento se applichiamo dei tagli cinematici abbastanza

duri (eccessivi per quello che vorremmo fare) Una via di mezzo tra queste due, dell'ordine dei 100 KB e 100 sec/evento e' quella

piu' realistica senza perdere informazioni di fisica rilevanti. Noi abbiamo bisogno di produrre come minimo 107 eventi per ciascuno dei

modelli studiati (finora 5) Poichè le stime dello scorso anno, basate sulla sola generazione erano ben

più ottimistiche di quello che abbiamo ottenuto ora, chiediamo il completamento delle risorse. Per il disco cercheremo di utilizzare risorse presenti in sezione ma abbiamo bisogno di CPU dedicate 15 Keuro per l’acquisto delle CPU

Miscellanea V: Missioni estere Ad Aprile 2012 la CSN1 ci aveva sbloccato 35 kE di

Missioni Estere che erano SJ al run p/Pb Dato che il run p/Pb è stato spostato al 2013,

restituiamo alla CSN1 27 kE di ME (21 kE da Firenze e 6 kE da Catania) Cerchiamo di effettuare più lavori possibile nel 2012

Setup di control room e DAQ Test di interfaccia con la macchina Installazione meccanica nel tunnel

Con la ragionevole speranza che ci vengano riassegnati per il 2013!!!!!!

Conclusions The analysis work is nicely going on Very important and tight contacts with the theorists and

the model developers to maximize the outcome of the LHCf results

Arm1 upgrade has been completed Arm2 is ready to be installed for the 2013 p/Pb run Very successful test beam has been completed in

summer 2012 Arm2 upgrade will be completed in 2013 Ready to take data at 14 TeV And…. Possible Light Ions runs at RHIC/LHC are under

investigation

Spares slides

Temperature dependency (Arm1)

The temperature dependency has been also checked for Arm1.The coefficient of GSO may be bigger than PMT, about - 0.5% / degree.Compared the histograms of dE in each layer at 18, 23, 28, 33 chiller temperatures.

T_Chiller

2318 28 33

Layer 03 Layer 04

Layer 06Layer 05

The coefficient is between 0.17% degree and 0.45% / degree.Slightly bigger than Arm2, but not so serious.

Fast install/uninstall

Silicon strip FE electronics

LHCf main detector

Calorimeters amplifier To be

assembled in a single structure

Now 35 BNC connections in the tunnel

To be packed in 2-3 Harting multipoles connectors

Now 3 main structures installed separately

Radiation hardness of GSO

No decrease up to 1 MGy

+20% increase over 1 kGy (τ=4.2h recovery)

2 kGy is expected for 350nb-1 @ 14TeV pp)

１ kGyNot irradiated ref. sample

Irradiated sample

τ~4.2h recovery

K. Kawade et al., JINST, 6, T09004, 2011

Dose rate=2 kGy/hour(≈1032cm-2s-1)

Global LHCf physics programLHCf measurement for p-Pb interactions at 3.5TeV proton energy could be easily and finely integrated in the LHCf global campaign.

Period Type Beam energy

LAB proton Energy

(eV)Detector

2009 p - p 450+450 GeV 4.3 1014 Arm1+Ar

m22009/20

10 p - p 3.5+3.5 TeV 2.6 1016 Arm1+Ar

m2

2013 p – Pb 3.5 TeV proton E 1016 Arm2

2014 p - p 7+7 TeV 1017Arm1+Ar

m2 upgraded

Proton-remnant side – photon spectrumSmall tower Big tower

Proton-remnant side – neutron spectrumSmall tower Big tower

35% ENERGY RESOLUTION IS CONSIDERED IN THESE PLOTS

Proton remnant side – Invariant cross section for isolated g-rays

What LHCf can measure in the p+Pb run (2)Study of the Nuclear Modification Factor

Nuclear Modification Factor measured at RHIC (production of p0): strong suppression for small pt at <>=4.

LHCf can extend the measurement at higher energy and for >8.4Very important for CR Physics

Phys. Rev. Lett. 97 (2006) 152302

Lead-remnant side – multiplicityPlease remind that EPOS does not consider Fermi motion and Nuclear Fragmentation

n

g

Small tower Big tower

Minimum required number of collision: Ncoll = 108 (factor 10 more statistics wrt shown plots) Integrated luminosity Lint = 50 mb-1

2106 single photons expected on p-remnant side

35000 p0 expected on same side

Assuming a pessimistic scenario with luminosity L = 1026 cm-2s-1 : Minimum running time for physics t = 140 h

(6 days)

… and required statistics to complete the p/Pb physics run