Forward Experiments at LHC: how LHC can contribute to Cosmic Ray Physics Alessia Tricomi University and INFN Catania EDS’09: 13th International Conference

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

PhysicsAlessia Tricomi

University and INFN Catania

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

ScatteringCERN, 29 June – 3 July 2009

Physics Motivations

Forward Experiments

Physics performances

Ultra High Energy Cosmic Rays

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 University & INFN Catania

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

2009

GZK cutoff: 1020 eV

GZK cutoff would limit energy to 1020eV (for

protons, due to Cosmic Microwave Background

pg(2.7K)DNp

The Cosmic Ray Spectra

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

super GZK events?!?

Different results between different

experiments



2009

The Cosmic Ray SpectraDifference in the energy scale between different

experiments???

Berezinsky 2007

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

AGASAx 0.9HiRes x 1.2Yakutsk

x 0.75Auger x 1.2



2009

HECR 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.

IRON

PROTON

Unger, ECRS 2008LHC



2009

HECR composition

Auger Xmax measurements

favors heavier composition as the energy increases

Anisotropy would favor proton

primaries (AGN correlation)



2009

Modelling Cosmic Rays at LHC

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

LHC

Forward Physics - cross section - particle spectra (E, PT, q, h, XF)

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



2009

Development of atmospheric showers

LHC

Tevatron

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

AUGER

Cosmic ray spectrum

Determination of E and mass of cosmic rays depends on description of primary UHE QCD (p+N,O Fe+N,O) interactionHadronic MC’s need tuning with dataThe dominant contribution to the energy flux is in the very forward region ( 0)In this forward region the highest energy available measurements of p0 cross section done by UA7 (E=1014 eV, y= 5÷7)



2009

Use LHC (firstly proposed by LHCf) √s = 14 TeV Elab=1017 eV to calibrate MCs

But…

Charged particles

Neutral particles

Beam pipe

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

Special detectors to access forward particles are necessaryAlessia Tricomi University & INFN Catania


2009

How to access Very Forward Physics at LHC?

Charged particles

Neutral particles

Beam pipe

Surrounding the beam pipe with detectorsSimple way, but still miss very very forward particlesAlessia Tricomi

University & INFN Catania


2009

Neutral particles

Beam pipe

Charged particles

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




2009

Y shape chamber enables us whole neutral measurementsZero Degree Calorimeters

Charged particles

Neutral particles Beam pipe


LHCf



2009

E leading hadron

E0

Elasticity / inelasticity Forward spectra Cross section

EM shower

Key Measurements at LHC

Neutrals in ZDCs / LHCf: neutrons, mesons (p0,K0

s g )

TOTEMATLAS Fwd (ALFA)



2009

Pseudo rapidity coverage at LHC

pseudorapidity: h = - ln (tanq/2)



2009

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

LHC experiments



2009

IP1: ATLAS forward detector



2009

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 detector



2009

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 m-strip Layers

IP2-IP8: ALICE/LHCb forward detectors



2009

ZDCs also at ±7m, ±100 m

Good capabilities for heavy Q, QQ, gauge

boson measurements(low x-PDFs)

IP5: CMS forward+TOTEM detectors



2009

IP5: CMS forward+TOTEM detectors



2009

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: p-p total cross section



2009

(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 Calorimeters

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

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

» enhance acceptance of central detectors for diffractive Physics

» kinematics and production spectra of forward particles

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

pp Physics

ATLAS ZDC ATLAS ZDC

HI

Physics



2009

Zero Degree Calorimeters: LHCfLHCf: same h coverage as other ZDCs but

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

capabilities– Excellent energy resolution(<5%) for g and p0, p0 mass

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

SPS electron data

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

Spatial Resolution:SPS-200 GeV electrons

Very important toolto calibrate energy scale



2009

Nu

mb

er

of

even

t

σx=40 mm

x-pos[mm]

Spatial Resolution:SPS-200 GeV electrons

LHCf : Monte Carlo discrimination

106 generated LHC interactions 1 Minute exposure@1029 cm-2s-1 luminosity Discrimination between various models is feasible

Quantitative discrimination with the help of a properly defined c2 discriminating variable based on the spectrum shape (see TDR for details)

5% Energy resolution



2009

LHCf: model dependence of neutron energy distribution

Original n energy 30% energy resolution



2009

New Models

Drescher, Physical Review D77, 056003 (2008)

PICCOEPOS

Neutron p0

Proton29



2009

MC model tuning: pp @ √s=14 TeV



2009

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

MC Model tuning: p+A @ √s= 8.8 TeV



2009

MC Model tuning: A+A @ √s=5.5 TeV



2009

Conclusions and plansCompilation of EAS data is affected by the uncertanties of hadron interaction models.LHC fwd experiments will provide crucial data of hadron interaction for CR study covering the whole phase space



2009

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

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

Aknowledgement



2009

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 slides



2009

Cosmic Ray Composition

QGSJET01

SIBYLL 2.1

Kascade Results



2009

CMS CASTOR & ZDC calorimeters

• 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



2009

TOTEM T1 & T2 tracking detectors

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, h, from pads Resolution strip~70mm



2009

Detector #1

16 scintillator layers (3 mm

thick)

Trigger and energy profile measurements

Absorber22 tungsten layers 7mm – 14 mm thick

(W: X0 = 3.5mm, RM = 9mm)

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

Energy

Impact point (h)

2 towers 24 cm long stacked vertically with 5 mm gap

Lower: 2 cm x 2 cm area

Upper: 4 cm x 4 cm area



2009

Detector # 2

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

16 scintillator layers (3 mm

thick)

Trigger and energy profile measurements

Absorber22 tungsten layers 7mm – 14 mm thick (2-4 r.l.)(W: X0 = 3.5mm, RM = 9mm)

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

Lower: 2.5 cm x 2.5 cm

Upper: 3.2 cm x 3.2 cm

Energy

Impact point (h)



2009

Detec

table

eve

nts

140

Beam crossing angle

LHCf: acceptance on PTg-Eg plane

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



2009

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 ResolutionN

um

ber

of

even

tN

um

ber

of

even

t

σx=40 mm

x-pos[mm]

y-pos[mm]

200 GeV electrons

σy=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



2009

ARM1 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

σx=172 mm

σy=159 mm



2009

ARM2-Silicon Energy Resolution

DE/E ~ 12%

No correction/calibration applied

ADC

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 electronsSPS beam test data

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



2009

Energy Resolution

Monte Carlo

SPS beam test

Energy distribution is corrected for leakagecorrection

Distance from Edge

N P

art

icle

s

MC predicts that the leakage is energy independent!



2009

QGSJETII: used modelQGSJET: c2/DOF=107/125DPMJET3: c2/DOF=224/125SYBILL: c2/DOF=816/125

g ray energy spectrum for different positions



2009

p0 spectra

QGSJETII ⇔ DPMJET3χ2= 106 (C.L. <10-6) ⇔ SIBYLL χ2= 83 (C.L. <10-6)DPMJET3 ⇔ SIBYLL χ2= 28 (C.L.= 0.024) 107events DOF = 17-2=15

p0 produced at collision can be extracted by using gamma pair eventsPowerful tool to calibrate the energy scale and also to eliminate beam-gas BG



2009



2009

p0 reconstruction

9.15 m

g

g350 GeV Proton beam

Carbon target (6 cm)in the slot used for beam monitor Arm1

Not in scale!

>107 proton on target (special setting from the SPS people)Dedicated trigger on both towers of the calorimeter has been used

(MeV)

Prelim

inary!!!! 250 p0 events

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

20 GeV) Direct protons in the

towers Multi hits in the same

tower

Ex:Dm ~ 8 MeVDm/m ~ 6%Sim:Dm/m ~ 5%



2009

p0 rate



2009

The LPM effect

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

○ w/o LPM■ w/ LPM



2009

g rate



2009

Estimate of the background beam-beam pipe E γ(signal) > 200 GeV, OK background < 1%

beam-gas It depends on the beam condition

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

background < 10% (conservative value)



2009

‘Analysis’ of Beam Gas events

We got 116 FC triggers in 8.275.034 BPTX: Nt=1162.109 protons/bunch Total # of protons: Np=1.7 x 1016

We try to estimate the gas density r from this rate:Nt=Np* L * s * r

L=effective lenght ~ 100 ms=Cross section ~ 80 mbarn = 80 x 10-31 m2

We find: r = 8.5 x 1012 H/m3 = 4.2 x 1012 H2/m3

From the LHC Project Report #783: r = 1012 H2/m3

From the pressure measurement in April 2008: r ~ 1012 H2/m3

~ CONSISTENT!!!!!!!!!!!!!Alessia Tricomi University & INFN Catania


2009

Low-x Physycs and UHECR



2009

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

Reduced charm cross sections: Less muons !

Forward QQ in ALICE



2009

D. D’Enterria (Trieste May 09)

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



2009

D. D’Enterria (Trieste May 09)

Documents

Forward Experiments at LHC: how LHC can contribute to Cosmic Ray Physics Alessia Tricomi University and INFN Catania EDS’09: 13th International Conference