LHCf: very forward LHCf: very forward measurement of measurement of

neutral particles at neutral particles at LHCLHC

SAKO TakashiSAKO Takashi(for the LHCf collaboration)(for the LHCf collaboration)

Solar-Terrestrial Environment Solar-Terrestrial Environment Laboratory, Laboratory,

Nagoya University, JapanNagoya University, JapanHERA and the LHC @ CERN 28-May-2008

OutlineOutline

HECR observations and interaction HECR observations and interaction modelsmodels• GZK energy (absolute energy scale, GZK energy (absolute energy scale,

composition)composition)• Galactic cosmic-rays (composition)Galactic cosmic-rays (composition)

The LHCf experimentThe LHCf experiment• Experiment setupExperiment setup• Model discriminationModel discrimination

Energy spectrum of CRsEnergy spectrum of CRs

Engel, Nuclear Phys. B (Proc. Suppl.) 151 (2006) 437-461

Knee; acceleration limit of galactic CRs?

GZK cutoff; Propagation limit due to CMB

Berezinsky, ICRC 2007Berezinsky, ICRC 2007

AGASA X0.9 HiRes X1.2Yakutsk X0.75 Auger X1.2 (not enough)

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

CompositioCompositionn

(Auger) (Auger)

Xmax favors heavy primary

Anisotropy favors light primary (if accept AGN correlation)

4

Composition of Galactic CRsComposition of Galactic CRs(KASCADE)(KASCADE)

QGSJET01

SIBYLL 2.1

Energy spectrum of CRsEnergy spectrum of CRs

Engel, Nuclear Phys. B (Proc. Suppl.) 151 (2006) 437-461

Knee; acceleration limit of galactic CRs?

GZK cutoff; Propagation limit due to CMB

LHC pp collision

Pseudo rapidity in LHCPseudo rapidity in LHC

pseudorapidity ：　 = - ln (tan /2)

The CMS and TOTEM diffractive and forward physics working group

Tra

nsv

erse

en

erg

y fl

ow

En

erg

y fl

ow

LHCf

LHCfLHCf

interaction point 1

140m

96mm

Arm#1

Arm#2

Installation of the detectors in the Installation of the detectors in the TAN absorbers at 140m from IP1TAN absorbers at 140m from IP1

96 mm

LHCf

LHCf (ZDCs) AcceptanceLHCf (ZDCs) Acceptance~10cmX10cm at 140m away fr

om collision point(5cm/140m ~ 300 urad)η> 8.4

η> 8.7

XF 0.1 1.0

K.Fukui, Y.Itow, T.Mase, K.Masuda, Y.Matsubara, H.Menjo, T.Sako, K.Taki, H.Watanabe Solar-Terrestrial Environment Laboratory, Nagoya University, Japan

K.Yoshida Shibaura Institute of Technology, Japan

K.Kasahara, M.Mizuishi, Y.Shimizu, S.Torii Waseda University, Japan

T.Tamura Kanagawa University, Japan

Y.Muraki Konan University

M.Haguenauer Ecole Polytechnique, France

W.C.Turner LBNL, Berkeley, USA

O.Adriani, L.Bonechi, M.Bongi, R.D’Alessandro, M.Grandi, P.Papini, S.Ricciarini, G.Castellini, A. Viciani INFN, Univ. di Firenze, Italy

A.Tricomi INFN, Univ. di Catania, Italy

J.Velasco, A.Faus IFIC, Centro Mixto CSIC-UVEG, Spain

D.Macina, A-L.Perrot CERN, Switzerland

The LHCf experimentThe LHCf experiment

Double Arm DetectorsDouble Arm Detectors

Arm#1 Detector Arm#2 Detector90mm

290mm

Double Arm DetectorsDouble Arm Detectors

Arm#1 Detector20mmx20mm+40mmx40mm4 XY SciFi+MAPMT

Arm#2 Detector25mmx25mm+32mmx32mm4 XY Silicon strip detectors

Model dependence in Model dependence in LHCfLHCf

Gamma-ray spectra expected in a 1000 sec operation of LHCf at very low LHC luminosity （ 1029cm-2s-1 ）

θ~ 0 radian θ~ 270 μradian

ππ0 0 spectraspectra

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

Pi zero produced at collision can be extracted by using gamma pair eventsPowerful to eliminate beam-gas BG

Neutron spectraNeutron spectra

Energy spectra at detector front Resolution included spectra

Drescher, Physical Review D77, 056003 (2008)

New modelsNew models(PICCO, (PICCO, EPOS)EPOS)

Neutron Pi0

Proton

LPM effectLPM effect

Transition curve of a 1 TeV photon w/ and w/o LPM to be measured by LHCf

○ w/o LPM■ w/ LPM

Run scheduleRun schedule

LHCf runs will be carried out during the LHCf runs will be carried out during the LHC commissioning with low luminosity LHC commissioning with low luminosity L<10L<103030cmcm-2-2ss-1-1

Data taking at 10TeV collisions in 2008 Data taking at 10TeV collisions in 2008 and 14TeV collisions in 2009and 14TeV collisions in 2009

Dedicated run with beam crossing angle Dedicated run with beam crossing angle in under discussion (pseudo-rapidity in under discussion (pseudo-rapidity limit 8.7 => 8.4)limit 8.7 => 8.4)

Future runs during ion collisions in studyFuture runs during ion collisions in study

SummarySummary Interpretation of CR observation data in Interpretation of CR observation data in

10101515-10-102020eV strongly depends on the eV strongly depends on the interaction model used in the analysis.interaction model used in the analysis.

LHCf will set a crucial calibration point at LHCf will set a crucial calibration point at 10101717eV for the interaction models.eV for the interaction models.

LHCf can measure E, p spectra of LHCf can measure E, p spectra of gamma-rays, πgamma-rays, π00 and neutrons at η>8.7 and neutrons at η>8.7 (8.4).(8.4).

LHCf can clearly discriminate LHCf can clearly discriminate existing/proposed models with a short existing/proposed models with a short operation under very low luminosity operation under very low luminosity condition. condition.

BackupBackup

Knapp, Shower curveKnapp, Shower curve

大気深さ

シャ

ワー

粒子

数

CalorimeterCalorimeter

n, gamma

n, gamma

44 radiation lengths, 1.7 hadron interaction lengths16 sampling scintillators4 position layers (2 for EM, 2 for hadron)

100-7000GeV gamma に対して <5% の分解能

ManipulatorManipulator

DC motor による駆動光学エンコーダ（放射線に弱い ! ）による位置測定リニアポテンシオメータ（可変抵抗）値による位置測定

名大理学部装置開発室と共同開発　

全て 200m 先の control room から制御が必要

Energy Energy resolutionresolution(gamma-(gamma-

rays)rays)

1TeV

5%

↑ 　 MC simulation <7TeV

← SPS beam test <200GeV

Position resolutionPosition resolution