Alessia Tricomi University and INFN Catania on behalf of the LHCf Collaboration The LHCf experiment...

Alessia TricomiAlessia TricomiUniversity and INFN CataniaUniversity and INFN Catania

on behalf of the LHCf on behalf of the LHCf CollaborationCollaboration

The LHCf experiment at LHCThe LHCf experiment at LHC

ISVHECRI08 - ISVHECRI08 - XV International Symposium XV International Symposium on Very High Energy Cosmic Ray on Very High Energy Cosmic Ray

InteractionsInteractions Paris 1 – 6 September, 2008Paris 1 – 6 September, 2008

Experiment Experiment goalsgoals The LHCf The LHCf detectordetector Physics Physics performanceperformance Running planRunning plan

Alessia Tricomi Alessia Tricomi University & INFN Catan University & INFN Cataniaia

The LHCf experiment at LHC The LHCf experiment at LHC ISVHECRI08, Paris 1-6 Septemb ISVHECRI08, Paris 1-6 September 2008er 2008

The LHCf CollaborationThe LHCf Collaboration

ITALYITALYFirenze University and INFN:Firenze University and INFN: O.Adriani,, L.Bonechi, O.Adriani,, L.Bonechi, M.Bongi, G.Castellini, M.Bongi, G.Castellini, R.D’Alessandro, P.Papini, S. R.D’Alessandro, P.Papini, S. Ricciarini, A. VicianiRicciarini, A. VicianiCatania University and Catania University and INFN:INFN: A.Tricomi A.Tricomi

JAPAN:JAPAN:STE Laboratory Nagoya University:STE Laboratory Nagoya University:K.Fukui,Y.Itow, T.Mase, K.Fukui,Y.Itow, T.Mase, K.Masuda,Y.Matsubara, K.Masuda,Y.Matsubara, H.Menjo,T.Sako, K.Taki, H. H.Menjo,T.Sako, K.Taki, H. WatanabeWatanabeWaseda University:Waseda University: K. Kasahara, M. K. Kasahara, M. Mizuishi, Y.Shimizu, S.ToriiMizuishi, Y.Shimizu, S.ToriiKonan University:Konan University: Y.Muraki Y.MurakiKanagawa University Yokohama: Kanagawa University Yokohama: T.TamuraT.TamuraShibaura Institute of Technology:Shibaura Institute of Technology: K. YoshidaK. Yoshida

SPAINSPAINIFIC Valencia:IFIC Valencia: A.Fauss, A.Fauss, J.VelascoJ.Velasco

FRANCEFRANCEEcole Politechnique Paris:Ecole Politechnique Paris:M. HaguenauerM. Haguenauer

USAUSALBNL Berkeley:LBNL Berkeley:W. TurnerW. Turner

CERNCERND.Macina, A.L. PerrotD.Macina, A.L. Perrot



LHCf: modelling Cosmic Rays at LHCf: modelling Cosmic Rays at LHCLHC

Astrophysical parameters - source type - source distribution - source spectrum - source composition - propagation

LHCLHC

Forward Physics - cross section - particle spectra (E, P(E, PTT, θ, η, X, θ, η, XFF))

Nuclear Interaction - calibration with data of Monte Carlo used in Cosmic Ray Physics



The Cosmic Ray SpectraThe Cosmic Ray Spectra

Based on data presented at the 30th ICRCMerida (Mexico)Figure prepared by Y. Tokanatsu

super GZK super GZK events?!?events?!?

GZK cutoff:GZK cutoff: 10 102020 eV eV

pp(2.7K)(2.7K)NN

Different results Different results between different between different

experimentsexperiments



The Cosmic Ray SpectraThe Cosmic Ray SpectraDifference in the energy scale between different Difference in the energy scale between different

experiments???experiments???

AGASA x 0.9HiRes x1.2Yakutsk x 0.75Auger x1.2 (not enough)

Berezisky 2007Berezisky 2007

AGASA SystematicsAGASA SystematicsTotal Total ±18% ±18%Hadron interaction Hadron interaction (QGSJET, SIBYLL) (QGSJET, SIBYLL) ~10% ~10% (Takeda et al., (Takeda et al., 2003)2003)



Cosmic Ray CompositionCosmic Ray Composition

Not only GZK… Not only GZK…

Different interaction Different interaction models lead different models lead different conclusions about the conclusions about the composition of the composition of the primary cosmic raysprimary cosmic rays..

IRON

IRON

PROTON

PROTON

Knapp et al., 2003Knapp et al., 2003Energy (eV)Energy (eV)

XXm

ax

max (g

/(g

/cmcm

22))




XXmaxmax favors heavy favors heavy primary primary

Anisotropy Anisotropy favors light favors light primary primary (if accept AGN (if accept AGN correlation)correlation)




QGSJET01QGSJET01

SIBYLL 2.1SIBYLL 2.1

Kascade ResultsKascade Results



Need for calibration…Need for calibration…

Composition: inferred from XComposition: inferred from Xmaxmax

Spectrum: Energy is measuredSpectrum: Energy is measuredby “counting the secondaries”by “counting the secondaries”

Simulation plays a crucial roleSimulation plays a crucial role

LHCf is a tool to calibrate the LHCf is a tool to calibrate the simulationsimulation



Development of atmospheric Development of atmospheric showersshowers

The dominant contribution to the The dominant contribution to the energy flux is in the energy flux is in the very forward very forward region (region ( 0) 0)

2θlntany

Simulation of an Simulation of an atmospheric shower due atmospheric shower due to a 10to a 101919 eV proton. eV proton.

No cutNo cut: X: XFF<0.05<0.05, , K: XK: XFF<0.1<0.1

XXFF~E/E~E/E00

In this forward region the highest energy available In this forward region the highest energy available measurements of measurements of 00 cross section were done by UA7 (E=10 cross section were done by UA7 (E=101414 eV, y= 5÷7)eV, y= 5÷7)



Forward Physics at LHCForward Physics at LHC

LHCLHC

LHCf firstly proposed to use LHC, the highest LHCf firstly proposed to use LHC, the highest energy acceleratorenergy accelerator

14 TeV in the center of mass 14 TeV in the center of mass

EElablab=10=101717 eV eV (E(Elablab= E= E22cmcm/2 m/2 mPP))

to calibrate MC simulation codeto calibrate MC simulation code

LHLHCC

TevatronTevatron

A 100 PeV fixed-target A 100 PeV fixed-target interaction with air has interaction with air has the cm energy of a pp the cm energy of a pp collision at the LHCcollision at the LHC

AUGEAUGERR

Cosmic ray spectrumCosmic ray spectrum



But…But…

Charged particlesCharged particles

Neutral particlesNeutral particles

Beam pipeBeam pipe

General purpose detectors (ATLAS, CMS,…) cover only the central regionGeneral purpose detectors (ATLAS, CMS,…) cover only the central region

Special detectors to access forward particles are necessarySpecial detectors to access forward particles are necessary



How to access Very Forward How to access Very Forward Physics at LHC?Physics at LHC?



Beam pipeBeam pipe

Surrounding the beam pipe with Surrounding the beam pipe with detectorsdetectorsSimple way, but still miss very very Simple way, but still miss very very forward particlesforward particles




Beam pipeBeam pipe


Install detectors inside the Install detectors inside the beam pipebeam pipeChallenging but ideal for Challenging but ideal for charged particlecharged particle




Y shape chamber enables us neutral measurementsY shape chamber enables us neutral measurementsZero degree calorimetersZero degree calorimeters


Neutral particlesNeutral particlesBeam pipeBeam pipe


LHCf

LHCf



Pseudo rapidity in LHCPseudo rapidity in LHC

pseudorapiditypseudorapidity ：：　　 = - ln = - ln (tan (tan /2)/2)

The CMS and TOTEM diffractive and forward physics working groupThe CMS and TOTEM diffractive and forward physics working group

Tra

nsvers

e e

nerg

y fl

ow

Tra

nsvers

e e

nerg

y fl

ow

En

erg

y fl

ow

En

erg

y fl

ow

LHCfLHCf



The LHC ringThe LHC ring

27 km ring27 km ringATLASATLASLHCfLHCf IP1IP1



LHCf: location and detector LHCf: location and detector layoutlayout

INTERACTION POINTINTERACTION POINT

IP1 (ATLAS)IP1 (ATLAS)

Beam Beam lineline

Detector IIDetector II

TungstenTungsten

ScintillatorScintillator

Silicon Silicon mstripsmstrips

Detector IDetector I

TungstenTungsten

ScintillatorScintillator

Scintillating Scintillating fibersfibers

140 m140 m 140 m140 m

Detectors should measure energy and position of Detectors should measure energy and position of from from 00 decays decays e.m. calorimeters with e.m. calorimeters with position sensitive layersposition sensitive layers

Two independent detectors on both side of IP1Two independent detectors on both side of IP1 RedundancyRedundancy Background rejection (especially beam-gas)Background rejection (especially beam-gas)



LHCf locationLHCf locationDetectors installed in the TAN Detectors installed in the TAN region, 140 m away from the region, 140 m away from the Interaction Point, in front of Interaction Point, in front of luminosity monitorsluminosity monitors

Here the beam Here the beam pipe splits in 2 pipe splits in 2 separate tubes.separate tubes.

Charged particle Charged particle are swept away by are swept away by magnets!!!magnets!!!

We will cover up to We will cover up to yy



Detector #1Detector #1

16 scintillator 16 scintillator layers (3 mm layers (3 mm

thick)thick)

Trigger and Trigger and energy profile energy profile measurementsmeasurements

AbsorberAbsorber

22 tungsten layers 22 tungsten layers 7mm – 14 mm 7mm – 14 mm thickthick

(W: X(W: X00 = 3.5mm, R = 3.5mm, RMM = = 9mm)9mm)

4 pairs of4 pairs of scintillating scintillating fiber layers fiber layers for for tracking purpose tracking purpose (6, 10, 32, 38 r.l.)(6, 10, 32, 38 r.l.)

EnergyEnergy

Impact point Impact point (())

2 towers 24 cm long 2 towers 24 cm long stacked vertically stacked vertically with 5 mm gapwith 5 mm gap

Lower: 2 cm x 2 cm Lower: 2 cm x 2 cm areaarea

Upper: 4 cm x 4 cm Upper: 4 cm x 4 cm areaarea



Detector # 2Detector # 2

4 pairs of 4 pairs of silicon microstrip silicon microstrip layerslayers (6, 12, 30, 42 r.l.) for tracking (6, 12, 30, 42 r.l.) for tracking purpose (X and Y directions)purpose (X and Y directions)

We used LHC styleWe used LHC styleelectronics and readoutelectronics and readout

16 scintillator 16 scintillator layers (3 mm layers (3 mm

thick)thick)

Trigger and Trigger and energy profile energy profile measurementsmeasurements

AbsorberAbsorber22 tungsten layers 22 tungsten layers 7mm – 14 mm 7mm – 14 mm thick (2-4 r.l.)thick (2-4 r.l.)

(W: X(W: X00 = 3.5mm, R = 3.5mm, RMM = = 9mm)9mm)

2 towers 24 cm long 2 towers 24 cm long stacked on their edges stacked on their edges and offset from one and offset from one anotheranother

Lower: 2.5 cm x 2.5 cmLower: 2.5 cm x 2.5 cm

Upper: 3.2 cm x 3.2 cmUpper: 3.2 cm x 3.2 cm

EnergyEnergy

Impact pointImpact point (())



Double ARM DetectorsDouble ARM Detectors

Arm#1 DetectorArm#1 Detector Arm#2 DetectorArm#2 Detector90mm90mm290mm290mm



Detectors in placeDetectors in place

LHCfLHCf

Luminosity Luminosity Monitor (BRAN)Monitor (BRAN)

ATLAS ZDCATLAS ZDC

Installation performed in two phases:Installation performed in two phases:1.1. Pre-Installation (Jan/Apr 2007)Pre-Installation (Jan/Apr 2007) Baking out of the beam pipe (200 °C)Baking out of the beam pipe (200 °C)2.2. Final Installation (Jan 2008)Final Installation (Jan 2008)



LHCf Physics performanceLHCf Physics performance

1.1. Single photon spectrumSingle photon spectrum2.2. 00 fully reconstructed (1 g in each tower) fully reconstructed (1 g in each tower)

00 reconstruction is an important tool for reconstruction is an important tool for energy calibration (energy calibration (00 mass constraint) mass constraint)

Basic detector requirements: Basic detector requirements: minimum 2 towers (minimum 2 towers (00 reconstruction) reconstruction) Smallest tower on the beam (multiple hits)Smallest tower on the beam (multiple hits) Dimension of the tower Dimension of the tower Moliere radius Moliere radius Maximum acceptance (given the LHC Maximum acceptance (given the LHC

constraints)constraints)

SimulationSimulation Beam TestBeam Test

Unfortunately no LHC data still availableUnfortunately no LHC data still availableResults for the moment based on Results for the moment based on



Detec

table

eve

nts

Detec

table

eve

nts

141400

Beam crossing Beam crossing angleangle

LHCf: acceptance on PLHCf: acceptance on PTT-E-E planeplane

A vertical beam crossing angle > 0 will A vertical beam crossing angle > 0 will increase the acceptance of LHCfincrease the acceptance of LHCf



LHCf single LHCf single geometrical geometrical acceptanceacceptance

Some runs with LHCf vertically shifted few cm Some runs with LHCf vertically shifted few cm will allow to cover the whole kinematical rangewill allow to cover the whole kinematical range



ARM1: Maximization of ARM1: Maximization of the acceptance for the acceptance for vertical beam vertical beam displacement (crossing displacement (crossing angle>0)angle>0)

ARM2: Maximization ARM2: Maximization of the acceptance in R of the acceptance in R (distance from beam (distance from beam center)center)

Transverse projection in TAN Transverse projection in TAN slotslot



LHCf : Monte Carlo LHCf : Monte Carlo discriminationdiscrimination

101066 generated LHC interactions generated LHC interactions 1 Minute exposure@101 Minute exposure@102929 cm cm-2-2ss-1-1 luminosity luminosity Discrimination between Discrimination between various models various models is feasibleis feasible

Quantitative Quantitative discrimination discrimination with the help of with the help of a properly a properly defined defined 22 discriminating discriminating variable based variable based on the spectrum on the spectrum shape shape (see TDR for (see TDR for details)details)

5% Energy resolution5% Energy resolution



LHCf: model dependence of LHCf: model dependence of neutron energy distributionneutron energy distribution

Original n energyOriginal n energy 30% energy resolution30% energy resolution



New ModelsNew Models

Drescher, Physical Review D77, Drescher, Physical Review D77, 056003 (2008)056003 (2008)

PICCOPICCOEPOSEPOS

NeutronNeutron 00

ProtonProton2929



00 spectra spectra

QGSJETIIQGSJETII ⇔ ⇔ DPMJET3χDPMJET3χ22= 106 (C.L. <10= 106 (C.L. <10-6-6)) ⇔ ⇔ SIBYLL χSIBYLL χ22= 83 (C.L. <10= 83 (C.L. <10-6-6))DPMJET3DPMJET3 ⇔ ⇔ SIBYLL χSIBYLL χ22= 28 (C.L.= 0.024)= 28 (C.L.= 0.024) 101077events DOF = 17-2=15events DOF = 17-2=15

00 produced at collision can be produced at collision can be extracted by using gamma pair extracted by using gamma pair eventseventsPowerful tool to calibrate the Powerful tool to calibrate the energy scale and also to energy scale and also to eliminate beam-gas BGeliminate beam-gas BG



Arm #1Arm #1E/E=5%E/E=5%200 200 m spatial resolutionm spatial resolution

m/m = 5%m/m = 5%

LHCf performances: LHCf performances: 00 mass mass resolutionresolution



SPS Beam TestSPS Beam Test

LHCf LHCf DetectorDetector

SiliconSilicon TrackerTracker

Moving TableMoving TableTrigger Trigger ScintillatorScintillator

CERN : SPS T2 H4CERN : SPS T2 H4 2006 Aug. 28 – Sep. 42006 Aug. 28 – Sep. 4 Incident ParticlesIncident Particles

–ProtonProton 　　 150,350GeV/c150,350GeV/c–Electron Electron

100,200GeV/c100,200GeV/c–Muon 150GeV/cMuon 150GeV/cSetupSetup

Test was successfulTest was successfulAnalysis is under way forAnalysis is under way for

Energy calibration of Energy calibration of the calorimetersthe calorimetersSpatial resolution of Spatial resolution of

the tracking systemsthe tracking systems



Energy Energy ResolutionResolution

Monte CarloMonte Carlo

SPS bean testSPS bean test

Energy distribution Energy distribution is corrected for is corrected for leakageleakage

correctioncorrection

Distance from EdgeDistance from Edge

N P

art

icle

sN

Part

icle

s

MC predicts that the MC predicts that the leakage is energy leakage is energy independent!independent!



00 reconstruction reconstruction

9.15 m9.15 m

350 GeV Proton beam350 GeV Proton beam

Carbon target (3 cm)Carbon target (3 cm)in the slot used for beam monitorin the slot used for beam monitor Arm1Arm1

Not in scale!Not in scale!

Egamma=18GeV

Shower Profile @ First SciFi Layer Shower Profile @ First SciFi Layer Calorimeters Calorimeters

20mm

X

40mm

X Y

YEgamma=46GeV

>10>1077 proton on target (special setting from the SPS people) proton on target (special setting from the SPS people)Dedicated trigger on both towers of the calorimeter has been usedDedicated trigger on both towers of the calorimeter has been used



00 mass reconstruction mass reconstruction

(MeV)

Prelim

inary!!!!

250 250 00 events triggered (in a quite big background) and on disk events triggered (in a quite big background) and on disk

Main problems: Main problems: – low photon energy (low photon energy (≥≥ 20 20

GeV) GeV) – Direct protons in the towersDirect protons in the towers– Multi hits in the same towerMulti hits in the same tower



ARM1 Position resolutionARM1 Position resolution

σx[m

m]

σｙ

[mm

]

Nu

mb

er

of

even

tN

um

ber

of

even

t

x-pos[mm]

y-pos[mm] E[GeV]

E[GeV]

200 GeV electrons

σσxx=172 =172 mm

σσyy=159 =159 mm



Position Resolution X Side

0

20

40

60

80

100

120

0 50 100 150 200 250

Energy (GeV)

Re

so

luti

on

(m

icro

ns

)

Data

Simulation

ARM2 Position ResolutionARM2 Position ResolutionN

um

ber

of

even

tN

um

ber

of

even

t

σσxx=40 =40 mm

x-pos[mm]

y-pos[mm]

200 GeV electrons

σσyy=64 =64 mm

Position Resolution Y Side

0

20

40

60

80

100

120

140

160

0 50 100 150 200 250

Energy (GeV)

Re

so

luti

on

(m

icro

ns

)Data

Simulation



ARM2-Silicon Energy ARM2-Silicon Energy ResolutionResolution

E/E E/E ~~ 12% 12%

No No correction/calibratiocorrection/calibration appliedn applied

ADCADC

Energy Linearity with Silicon Sensors

y = 24,927x - 596,44

R2 = 0,994

0,00E+00

5,00E+02

1,00E+03

1,50E+03

2,00E+03

2,50E+03

3,00E+03

3,50E+03

4,00E+03

4,50E+03

5,00E+03

0 50 100 150 200 250

Energy (GeV)

En

erg

y M

ea

su

red

(a

.u.)

Data

Lineare (Data)

200 GeV electrons200 GeV electronsSPS beam test data SPS beam test data



LHC scheduleLHC schedule

Beam commissiong Beam commissiong parameters are good parameters are good for LHCf!for LHCf!

Preferred LHCf run parametersPreferred LHCf run parameters

Beam Beam parameterparameter

ValueValue

# of bunches# of bunches ≤ ≤ 4343

Bunch Bunch separationseparation

> 2 > 2 secsec

Crossing Crossing angleangle

0 0 radrad

140 140 rad rad downwarddownward

Luminosity Luminosity per bunchper bunch

< 2 x 10< 2 x 1028 28 cmcm-2-2ss-1-1

LuminosityLuminosity < 10< 1030 30 cmcm-2-2ss-1-1

Bunch Bunch intensityintensity

4x104x101010 ppb ppb ((*=18m)*=18m)

1x101x101010 ppb ( ppb (*= *= 1m)1m)



Radiation Damage StudiesRadiation Damage Studies

30 kGy30 kGy

• Expected dose: 100 Gy/day at 10Expected dose: 100 Gy/day at 103030 cmcm-2-2ss-1-1

• Few months @ 10Few months @ 103030 cm cm-2-2ss-1-1: 10 kGy: 10 kGy• 50% light output50% light output• Continous monitor and calibration Continous monitor and calibration with with Laser system!!!Laser system!!!

Scintillating fibers and scintillatorsScintillating fibers and scintillators



LHCf possible running LHCf possible running scenarioscenario Phase-IPhase-I

– 900 GeV collision before rumping in 2008 900 GeV collision before rumping in 2008 (hope in a week from now!)(hope in a week from now!)

– 10 TeV run in 2008 during the LHC 10 TeV run in 2008 during the LHC commissioning (low luminosity)commissioning (low luminosity)

– 14 TeV run in 2009 during commissioning 14 TeV run in 2009 during commissioning – Remove LHCf when luminosity reaches 10Remove LHCf when luminosity reaches 1030 30 cmcm--

22ss-1-1 for radiation damage reasons for radiation damage reasons Phase-IIPhase-II

– Re-install the detector at the next opportunity Re-install the detector at the next opportunity of low luminosity run of low luminosity run

– Dedicated runs (crossing angle, etc.)Dedicated runs (crossing angle, etc.) Phase-IIIPhase-III

– Future extension for p-A, A-A run with Future extension for p-A, A-A run with upgraded detectorsare under studyupgraded detectorsare under study



LHCf: conclusions and plansLHCf: conclusions and plans Compilation of the EAS data is affected by the Compilation of the EAS data is affected by the

uncertainty of hadron interaction.uncertainty of hadron interaction. LHCf experiment will provide crucial data of LHCf experiment will provide crucial data of

hadron interaction for CR study.hadron interaction for CR study. LHCf can clearly discriminate the existing and LHCf can clearly discriminate the existing and

new models by measurements of new models by measurements of ππ00,γ and n,γ and n thanks to its excellent performancesthanks to its excellent performances– Energy Resolution Energy Resolution ~~5%5%– Spatial resolution Spatial resolution ~40-200 ~40-200 mm– Beam crossing angle ≠0 and/or vertical shifts of Beam crossing angle ≠0 and/or vertical shifts of

LHCf by few cm will allow more complete physics LHCf by few cm will allow more complete physics measurementsmeasurements

Both Detectors ready to fulfil the run programBoth Detectors ready to fulfil the run programSo nowSo now



LHCf: conclusions and plansLHCf: conclusions and plans

We need only to wait for We need only to wait for LHC beams, which indeed LHC beams, which indeed

are just arriving!are just arriving!Hoping to answer all our Hoping to answer all our

questionsquestions



Back-up slidesBack-up slides



The TAN and LHCfThe TAN and LHCf

marbleshielding

manipulator

boxes for DAQ electronic

box ~ (15box ~ (15××1515××40) cm40) cm33



Front scintillator:Front scintillator:Fixed position wrt to TANFixed position wrt to TAN

Silicon + Tungsten + Scintillator:Silicon + Tungsten + Scintillator:+/- 5 cm vertical excursion+/- 5 cm vertical excursion

PM

TR

74

00

PM

TR

74

00

Front scintillatorFront scintillatorLateral view of ARM #2Lateral view of ARM #2

Si Tracker + HybridSi Tracker + Hybrid

Beam axisBeam axis



raterate



QGSJETII: used modelQGSJETII: used modelQGSJET: cQGSJET: c22/DOF=107/125/DOF=107/125DPMJET3: cDPMJET3: c22/DOF=224/125/DOF=224/125SYBILL: cSYBILL: c22/DOF=816/125/DOF=816/125

ray energy spectrum for different ray energy spectrum for different positionspositions



e, , p beam

Silicon Calorimeter

Before correction After correction

2 mm

The CERN test beam on August The CERN test beam on August 20042004



Leak CorrectionLeak CorrectionMonte Carlo

Prototype Experiment

MC predicts that the leakage is energy independent!

correction

Distance from Edge

N P

arti

cles



Estimate of the backgroundEstimate of the background beam-beam pipebeam-beam pipe E E γγ(signal) > 200 GeV, OK(signal) > 200 GeV, OK

background background < 1% < 1%

beam-gasbeam-gas It depends on the beam conditionIt depends on the beam condition

background background < 1% (< 1% (under 10under 10-10-10 Torr) Torr) beam halo-beam pipebeam halo-beam pipe It has been newly estimated from the beam loss rateIt has been newly estimated from the beam loss rate

Background Background < 10%< 10% (conservative value) (conservative value)



Effect of LHCf on BRAN Effect of LHCf on BRAN measurementmeasurement

The effect of LHCf on BRAN measurements The effect of LHCf on BRAN measurements has been studied in the last months by has been studied in the last months by simulationsimulation– Reduction of shower particles at BRANReduction of shower particles at BRAN– Position dependence on beam displacementPosition dependence on beam displacement

(question from machine peoples: if we shift by (question from machine peoples: if we shift by 1 mm the real beam, does the center of the 1 mm the real beam, does the center of the measured neutral energy shifts by 1 mm?)measured neutral energy shifts by 1 mm?)

LUMI monitor (BRAN) inside TAN is beyond LHCf (replacing 4th copper bar)LUMI monitor (BRAN) inside TAN is beyond LHCf (replacing 4th copper bar)

LHCfLHCfLumiLumi

Cu Bar / ZDCCu Bar / ZDC

IP1IP1

LHCfLHCfLumiLumi

Cu Bar / ZDCCu Bar / ZDC



Arm #1 Arm #2

H.Menjo

Relative change of the reduction factors for BRAN Relative change of the reduction factors for BRAN with respect to the nominal value (center of the beam: with respect to the nominal value (center of the beam:

nominal one) nominal one)

BRAN response vs beam BRAN response vs beam positionposition

If the position of beam center stays within If the position of beam center stays within a few mm from the beam-pipe center, the a few mm from the beam-pipe center, the reduction factors do not change more than reduction factors do not change more than

10%10%

1 x 1 cm2

1 x 1 cm2



LHCf performances: LHCf performances: 00 geometrical geometrical acceptanceacceptance

Arm #1Arm #1

Arm #2Arm #2



LHCf performances: energy LHCf performances: energy spectrum of spectrum of 00

Typical energy resolution of Typical energy resolution of is 3 % at 1TeVis 3 % at 1TeV



Beam parameters Beam parameters used for used for commissioning are commissioning are good for LHCf!!!good for LHCf!!!

Beam Beam parameterparameter

ValueValue

# of bunches# of bunches ≤ ≤ 4343

Bunch Bunch separationseparation

> 2 > 2 secsec

Crossing Crossing angleangle

0 rad0 rad

140 140 rad rad downwarddownward

Luminosity Luminosity per bunchper bunch

< 2 x 10< 2 x 1028 28 cmcm-2-2ss-1-1

LuminosityLuminosity < 0.8 x 10< 0.8 x 1030 30 cmcm--

22ss-1-1

Bunch Bunch intensityintensity

4x104x101010 ppb ppb ((*=18m)*=18m)

1x101x101010 ppb ( ppb (*= *= 1m)1m)

( No radiation problem for 10kGy by a “year” operation with this luminosity )

Optimal LHCf run conditionsOptimal LHCf run conditions



From R. Bailey From R. Bailey presentation at presentation at January 2007 TAN workshop January 2007 TAN workshop

Stage 1Stage 1

Optimal conditions for LHCf running!Optimal conditions for LHCf running!



From R. Bailey From R. Bailey presentation at presentation at January 2007 TAN workshop January 2007 TAN workshop

Alessia Tricomi University and INFN Catania on behalf of the LHCf Collaboration The LHCf experiment...

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