Forward Experiments at LHC: how LHC can contribute to Cosmic Ray Physics

Forward Experiments at LHC:Forward Experiments at LHC:how LHC can contribute to Cosmic Ray how LHC can contribute to Cosmic Ray

PhysicsPhysicsAlessia TricomiAlessia Tricomi

University and INFN CataniaUniversity and INFN Catania

EDS’09: 13th International EDS’09: 13th International Conference on Elastic & Diffractive Conference on Elastic & Diffractive

ScatteringScatteringCERN, 29 June – 3 July 2009CERN, 29 June – 3 July 2009

Physics Physics MotivationsMotivations Forward Forward ExperimentsExperiments Physics Physics performancesperformances

Ultra High Energy Cosmic Ultra High Energy Cosmic RaysRays

Experimental observations: at E>100 TeV only EAS(shower of secondary particles)• lateral distribution• longitudinal distribution• particle type• arrival direction

Extensive Air Showers

Astrophysical parameters:(primary particles)• spectrum• composition• source distribution• origin and propagation

Air shower development (particle

interaction in the atmosphere)

Alessia Tricomi Alessia Tricomi University & INFN University & INFN CataniaCatania

Forward Experiments at LHC Forward Experiments at LHC EDS'09, CERN 29 Jun - 3 July 2009 EDS'09, CERN 29 Jun - 3 July 2009

GZK cutoff: 10GZK cutoff: 102020 eV eV

GZK cutoff would limit energy to 1020eV (for

protons, due to Cosmic Microwave Background

pp(2.7K)(2.7K)NN

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?!?

Different results between different

experiments



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

experiments???experiments???

Berezinsky 2007Berezinsky 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)

AGASAx 0.9HiRes x 1.2Yakutsk

x 0.75Auger x 1.2



HECR compositionHECR composition

Xm

ax(g

/cm

2)

IRON

The depth of the maximum of the

shower Xmax in the

atmosphere depends on energy

and type of the primary particle.

Different hadronic

interaction models give

different answers about

the composition of HECR.

IRONIRON

PROTONPROTON

Unger, ECRS 2008Unger, ECRS 2008LHC



HECR compositionHECR composition

Auger Xmax measurements

favors heavier composition as the energy increases

Anisotropy would favor proton

primaries (AGN correlation)



Modelling Cosmic Rays at LHCModelling Cosmic Rays at LHC

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

LHCLHC

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

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



Development of atmospheric Development of atmospheric showersshowers

LHCLHC

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

AUGERAUGER

Cosmic ray spectrumCosmic ray spectrum

Determination of E and mass of Determination of E and mass of cosmic rays depends on cosmic rays depends on description of primary UHE description of primary UHE QCD (p+N,O Fe+N,O) interactionQCD (p+N,O Fe+N,O) interactionHadronic MC’s need tuning with dataHadronic MC’s need tuning with dataThe 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)In this forward region the highest In this forward region the highest energy available measurements of energy available measurements of 00 cross section done by UA7 (E=10cross section done by UA7 (E=101414 eV, y= 5÷7)eV, y= 5÷7)



Use LHC (firstly Use LHC (firstly proposed by proposed by LHCf)LHCf) √√s = 14 TeV s = 14 TeV EElablab=10=101717 eV eV to calibrate MCsto calibrate MCs

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 necessaryAlessia Tricomi Alessia Tricomi University & INFN University & INFN CataniaCatania


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 particlesAlessia Tricomi Alessia Tricomi

University & INFN University & INFN CataniaCatania



Beam pipeBeam pipe


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




Y shape chamber enables us whole neutral measurementsY shape chamber enables us whole neutral measurementsZero Degree CalorimetersZero Degree Calorimeters


Neutral particlesNeutral particlesBeam pipeBeam pipe


LHCf

LHCf



E leading hadron

E0

Elasticity / inelasticity Forward spectra Cross section

EM shower

Key Measurements at LHCKey Measurements at LHC

Neutrals in ZDCs / LHCf: neutrons, mesons (0,K0

s )

TOTEMATLAS Fwd (ALFA)



Pseudo rapidity coverage at Pseudo rapidity coverage at LHCLHC

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



Particle production at LHC over ≅10All phase space covered thanks to dedicated forward detectors!

LHC experimentsLHC experiments



IP1: ATLAS forward detectorIP1: ATLAS forward detector



LUCID (Cerenkov Tubes, 17m): Cerenkov hits over 5.4 < |η| < 6.1

ZDC (W/Q-fiber calo, 140m): Neutral calorimetry over |η| > 8.3

ALPHA (Sci-Fi RPs): Proton taggers at ± 240 m

FP220,FP420 (Si trackers, timing): Proton tracking at ±220, 420 m

IP1: LHCf detectorIP1: LHCf detector



UHECR-oriented experiment (~30 Japan-European Collaborators)Installed at ±140 m on both side of IP1 in TAN region

Double ARM detector:ARM1: Sci/W + 4 XY Sci Fiber LayersARM2: Sci/W + 4 XY Si -strip Layers

IP2-IP8: ALICE/LHCb forward IP2-IP8: ALICE/LHCb forward detectorsdetectors



ZDCs also at ±7m, ±100 m

Good capabilities for heavy Q, QQ, gauge

boson measurements(low x-PDFs)

IP5: CMS forward+TOTEM IP5: CMS forward+TOTEM detectorsdetectors



IP5: CMS forward+TOTEM IP5: CMS forward+TOTEM detectorsdetectors



TOTEM-T1,T2 (CSC/GEM telescopes):Tracking over 3.1 < |η| < 4.7, 5.3 < |η| < 6.7

CASTOR (W/Q-fiber calo): Calorimetry over 5.1 < |η| < 6.6

ZDC (W/Q-fiber calo): Neutral calorimetry for |η| > 8.3

TOTEM (Si Roman Pots): Proton taggers at ±147, ±220 m

FP420 (Si trackers, timing):Proton tracking at ±420 m

TOTEM: pTOTEM: p-p total cross -p total cross sectionsection



(E710/811–CDF 2.6σ disagreement)

~ l n 2 s

Extrapolations vary by σ(LHC) = 90-130 mb

€

−20+10%

TOTEM goal: ≅1% precisionspecial run/optics: various β*, low lumi

ZDC: Zero Degree ZDC: Zero Degree CalorimetersCalorimeters

ALICE, ATLAS & CMS ZDC (complemented by ALICE, ATLAS & CMS ZDC (complemented by CASTOR)CASTOR)– Total energy flow, wide aperture, high energy Total energy flow, wide aperture, high energy

resolution for hadrons, (proton measurement only by resolution for hadrons, (proton measurement only by ALICE ZDC)ALICE ZDC)

» enhance acceptance of central detectors for diffractive enhance acceptance of central detectors for diffractive PhysicsPhysics

» kinematics and production spectra of forward particleskinematics and production spectra of forward particles

Characterize Event:Characterize Event:» Count spectator neutronsCount spectator neutrons» Measure centrality (magnitude and Measure centrality (magnitude and direction of impact parameter)direction of impact parameter)

ppp p PhysicsPhysics

ppp p PhysicsPhysics

ATLAS ZDC ATLAS ZDC

HIHI

PhysicsPhysics

HIHI

PhysicsPhysics



Zero Degree Calorimeters: Zero Degree Calorimeters: LHCfLHCfLHCf: same LHCf: same coverage as other ZDCs but coverage as other ZDCs but

fully dedicated experiment to HECR fully dedicated experiment to HECR PhysicsPhysics– Double ARM calorimeters with imaging and PID Double ARM calorimeters with imaging and PID

capabilitiescapabilities– Excellent energy resolutionExcellent energy resolution(<5%)(<5%) for for and and 00, , 0 0 mass mass

resolution resolution (< 5%) (< 5%) and and Spatial resolution Spatial resolution (40-200 (40-200 m)m)– Good neutron energy resolution Good neutron energy resolution (<30%)(<30%)Energy Resolution:

SPS electron data

m/m < 4%m/m < 4%1.04 107 events≅20 min @L=1029cm-2s-1

Spatial Resolution:SPS-200 GeV electronsSpatial Resolution:SPS-200 GeV electrons

Very important toolto calibrate energy scaleVery important toolto calibrate energy scale


Forward Experiments at LHC Forward Experiments at LHC EDS'09, CERN 29 Jun - 3 July 2009 EDS'09, CERN 29 Jun - 3 July 2009N

um

ber

of

even

t

σσxx=40 =40 mm

x-pos[mm]

Spatial Resolution:SPS-200 GeV electronsSpatial Resolution:SPS-200 GeV electrons

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 a with the help of a properly defined properly defined 22 discriminating discriminating variable based on variable based on the spectrum 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



MC model tuning: pp @ √s=14 MC model tuning: pp @ √s=14 TeVTeV



Dominated by Soft QCD: underlying events, multiparton interactions, fragmentations

MC Model tuning: p+A @ √s= MC Model tuning: p+A @ √s= 8.8 TeV 8.8 TeV



MC Model tuning: A+A @ MC Model tuning: A+A @ √s=5.5 TeV √s=5.5 TeV



Conclusions and plansConclusions and plans



Several detectors Several detectors already installedalready installedLHCf ready for data LHCf ready for data taking already during taking already during LHC commissioningLHC commissioningWe need only to wait We need only to wait LHC restart!LHC restart!

Hoping to answer all our Hoping to answer all our questions and to help EAS questions and to help EAS experiments to interpret experiments to interpret their datatheir data

AknowledgementAknowledgement



Thanks to ALICE, ATLAS, CMS, LHCb, LHCf, TOTEM Collaborations for useful materialIn particular, I wish to thankO. Adriani, K. Eggert, D. D’Enterria, P. Grafstrom, M. Grothe, S. White

Back-up slidesBack-up slides



Cosmic Ray CompositionCosmic Ray Composition

QGSJET01QGSJET01

SIBYLL 2.1SIBYLL 2.1

Kascade ResultsKascade Results



CMS CASTOR & ZDC CMS CASTOR & ZDC calorimeterscalorimeters

• extends calorimetric coverage of CMS to 5.2 < η < 6.6

• signal collection through Čerenkov photons transmitted to PMTs through aircore lightguides

• W absorber & quartz plates sandwich,

• electromagnetic and hadronic sections

• 16 seg. in φ, 14 seg in z, none in η

• 140 m from interaction point in TAN absorber

• Tungsten/quartz Čerenkov calorimeter with separate e.m. and had. Sections

• Acceptance for neutrals (γ, π0, n) from η > 8.1, 100% for η > 8.4



TOTEM T1 & T2 tracking TOTEM T1 & T2 tracking detectorsdetectors

3m

Test Beam

Cathode Strip Chambers (CSC) Mounted in front of HadronForward calorimeter of CMS 3.1 < | < 4.7 5 planes with 3 coordinates/plane 6 trapezoidal CSC detectors/plane Resolution ~ 0.8mm

Gas Electron Multiplier (GEM) Mounted in front of CASTOR 5.3 < | < 6.5 10 planes formed by 20 GEM semi-circular modules Radial position from strips, , from pads Resolution strip~70m



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)

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 (())



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 A vertical beam crossing angle > 0 increases the acceptance of LHCfincreases the acceptance of LHCf



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

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



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 mmmm

σσyy=159 =159 mmmm



ARM2-Silicon Energy ARM2-Silicon Energy ResolutionResolution

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

No No correction/calibratiocorrection/calibration appliedn applied

ADCADC

E nergy L inearity with S ilicon S ensors

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

Only silicon energy resolution Only silicon energy resolution ~ ~ 10%!!!!!10%!!!!!We can use it as a check for the We can use it as a check for the radiation damage of the radiation damage of the scintillators scintillators



Energy Energy ResolutionResolution

Monte CarloMonte Carlo

SPS beam testSPS beam test

Energy distribution Energy distribution is corrected for is corrected for leakageleakagecorrectioncorrection

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!



QGSJETII: used modelQGSJETII: used modelQGSJET: QGSJET: 22/DOF=107/125/DOF=107/125DPMJET3: DPMJET3: 22/DOF=224/125/DOF=224/125SYBILL: SYBILL: 22/DOF=816/125/DOF=816/125

ray energy spectrum for different ray energy spectrum for different positionspositions



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

pp00 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





00 reconstruction reconstruction

9.15 m9.15 m

350 GeV Proton beam350 GeV Proton beam

Carbon target (6 cm)Carbon target (6 cm)in the slot used for beam monitorin the slot used for beam monitor Arm1Arm1

Not in scale!Not in scale!

>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

(MeV)(MeV)

Prelim

inary!!!! 250 250 00 events events

triggered (in a triggered (in a quite huge quite huge background) and background) and on diskon diskMain problems: Main problems: low photon energy (low photon energy (≥≥

20 GeV) 20 GeV) Direct protons in the Direct protons in the

towerstowers Multi hits in the same Multi hits in the same

towertower

Ex:Ex:m m ~ 8 MeV~ 8 MeVm/m m/m ~ 6%~ 6%Sim:Sim:m/m m/m ~ 5%~ 5%



raterate



The LPM effectThe LPM effect

Transition curve of a1 TeV photon w/ and w/o LPM Transition curve of a1 TeV photon w/ and w/o LPM to be measured by LHCfto be measured by LHCf

○ w/o LPM■ w/ LPM



raterate



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 10(under 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)Alessia Tricomi Alessia Tricomi University & INFN University & INFN CataniaCatania


‘‘Analysis’ of Beam Gas eventsAnalysis’ of Beam Gas events

We got 116 FC triggers in 8.275.034 BPTX: NWe got 116 FC triggers in 8.275.034 BPTX: Ntt=116=1162.102.1099 protons/bunch protons/bunch

Total # of protons: NTotal # of protons: Npp=1.7 x 10=1.7 x 101616

We try to estimate the gas density We try to estimate the gas density from this rate: from this rate:

NNtt=N=Npp* L * * L * * * L=effective lenght L=effective lenght ~ 100 m~ 100 m=Cross section =Cross section ~ 80 mbarn = 80 x 10~ 80 mbarn = 80 x 10-31-31 m m22

We find: We find: = 8.5 x 10 = 8.5 x 101212 H/m H/m33 = 4.2 x 10 = 4.2 x 101212 H H22/m/m33

From the LHC Project Report #783: From the LHC Project Report #783: = 10 = 101212 H H22/m/m33

From the pressure measurement in April 2008: From the pressure measurement in April 2008: ~~ 10 101212 H H22/m/m33

~ ~ CONSISTENT!!!!!!!!!!!!!CONSISTENT!!!!!!!!!!!!!



Low-x Physycs and UHECRLow-x Physycs and UHECR



Reduced dN/dη :Less penetration: lower X (~ -30 g/cm2)

Reduced charm cross sections: Less muons !

Forward QQ in ALICEForward QQ in ALICE



D. D’Enterria (Trieste May 09)


*, Z, W in LHCb (2<*, Z, W in LHCb (2<<5<5





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Forward Experiments at LHC: how LHC can contribute to Cosmic Ray Physics

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