lhcf status oscar adriani university of florence & infn firenze on behalf of the lhcf...

LHCf StatusOscar Adriani

University of Florence & INFN FirenzeOn behalf of the LHCf CollaborationJune 13th, 2012

O. Adriani LHCf Status 110th LHCC Meeting, 13th June 2012

Introduction and contents

LHCf status after march 2012 LHCC

p0 paper submitted to PRD Selected final results will be shown

Short spot on neutron analysis

Arm1 upgrade for 2014 run under way

Preparation for p/Pb autumn 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 binsSubmitted to PRDCERN-PH-EP-2012-145


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

1(E1)

2(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).

Arm1 vs Arm2 comparison



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.


YLAB= Ybeam - Y

<pT> distribution

Two different approaches used to derive the average transverse momentum, ⟨pT⟩ in different rapidity bins:1. by fitting an empirical

function to the pT spectra in each rapidity range (thermodynamical approach)

2. by simply numerically integrating the pT spectra

Results of the two 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


small-η

= La

rge to

wer

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


small-η

= La

rge to

wer

big-η =Small tower



900GeV vs. 7TeVwith the same PT region

900 GeV Small+large tower


small-η

= La

rge to

wer

big-η =Small tower


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)


900GeV vs. 7TeVwith the same PT region

900 GeV Small+large tower

Neutron (very preliminary…) analysis

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

O. Adriani LHCf: results on forward particle production at LHC anf future perspectives Paris, June 11, 2012

Neutron Detection Efficiency and energy linearity

Efficiency at the offline shower triggerFlat efficiency >500GeV

%

Linear fitParabolic fit

Energy and Position Resolution

O. Adriani LHCf: results on forward particle production at LHC anf future perspectives Paris, June 11, 2012

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

Status of the LHCf upgrade and re-installation issues for p/Pb

2012 run


LHCf Upgrade 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) is underway this week

Arm1 will be 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


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 will continue discussion with ATLAS for trigger and data exchange, to get the maximum physics outcome for the data, following the LHCC reccomendation


Conclusions

Three physics papers have been completed: Inclusive g at 900 GeV Inclusive g at 7TeV p0 Pt vs y spectra

We are in strict contacts with model developers, and the feedback from our data is important and appreciated in the community

Neutron analysis is ongoing and is our next priority

Upgrade work for 14 TeV almost completed for Arm1 Beam test in August

p/Pb interesting physics case will be investigated by LHCf with Arm2 detector in Autumn

O.

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LH

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2Spares slides


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)


Uniformity test using C beam at HIMAC(preliminary results from quick analysis)

PMT via fiber bundle

PMT via fiber bundle

No particle due to the beam pipe

• Scan examples for a 20mmx20mm and a 40mmx40mm GSO plates

• All scintillators of Arm1 were mapped by C beam

• Similar uniformity to the current detector is obtained

mm

mm

mm

mm


GSO bars cross talk and attenuation

Attenuation and cross talk are acceptable to determine the position of single particle shower and multihit identification

For multihit analysis, further study is necessary

Paint between the bars reduces cross talk, but worsens attenuation and its bar-to-bar variation

No paint between bars

-30%/35mm

10%

0%

Irrad

iate

d b

ar (1

00%

)

Attenuation along the longest 40mm bar Cross talk


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 TypeBeam energy

LAB proton Energy

(eV)

Detector

2009 p - p450+450

GeV 4.3 1014 Arm1+Arm2

2009/2010 p - p

3.5+3.5 TeV 2.6 1016 Arm1+Ar

m2

2012 p – Pb 3.5 TeV proton E

1016 Arm2

2014 p - p 7+7 TeV 1017

Arm1+Arm2

upgraded


Proton-remnant side – photon spectrum

Small tower Big tower


Proton-remnant side – neutron spectrum


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



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 0 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

lhcf status oscar adriani university of florence & infn firenze on behalf of the lhcf...

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