1. LHCf: very forward measurement of neutral particles at LHC
SAKO Takashi
(for the LHCf collaboration)
Solar-Terrestrial Environment Laboratory,
Nagoya University, Japan
HERA and the CERN 28-May-2008

2. Outline HECR observations and interaction models The LHCf experiment
GZK energy (absolute energy scale, composition)
Galactic cosmic-rays (composition)
The LHCf experiment
Experiment setup
Model discrimination

3. Energy spectrum of CRs Knee; acceleration limit of galactic CRs?
GZK cutoff; Propagation limit due to CMB
Engel, Nuclear Phys. B (Proc. Suppl.) 151 (2006)

4. Berezinsky, ICRC 2007 Systematics of AGASA Total ±18%
AGASA X HiRes X1.2
Yakutsk X Auger X1.2 (not enough)
Systematics of AGASA
Total ±18%
Hadron interaction
(QGSJET, SIBYLL) ~10%
(Takeda et al., 2003)

5. Composition (Auger) Xmax favors heavy primary4
Composition (Auger)
Xmax favors heavy primary
Anisotropy favors light primary
(if accept AGN correlation)

6. Composition of Galactic CRs (KASCADE)
QGSJET01
SIBYLL 2.1

7. Energy spectrum of CRs LHC pp collision
Knee; acceleration limit of galactic CRs?
GZK cutoff; Propagation limit due to CMB
LHC pp collision
Engel, Nuclear Phys. B (Proc. Suppl.) 151 (2006)

8. Transverse energy flow
Pseudo rapidity in LHC
LHCf
Energy flow
Transverse energy flow
The CMS and TOTEM diffractive and forward physics working group
pseudorapidity：　 = - ln (tan /2)

9. LHCf
interaction point 1
140m
96mm
Arm#1
Arm#2

10. Installation of the detectors in the TAN absorbers at 140m from IP1
LHCf
96 mm

11. LHCf (ZDCs) Acceptance
η> 8.4
η> 8.7 XF
~10cmX10cm at 140m away from collision point
(5cm/140m ~ 300 urad)

12. The LHCf experiment
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

13. Double Arm Detectors
Arm#1 Detector
Arm#2 Detector
290mm
90mm

14. Double Arm Detectors Arm#1 Detector 20mmx20mm+40mmx40mm
4 XY SciFi+MAPMT
Arm#2 Detector
25mmx25mm+32mmx32mm
4 XY Silicon strip detectors

15. Model dependence in LHCf
θ~ 0 radian
θ~ 270 μradian
Gamma-ray spectra expected in a 1000 sec operation of LHCf at very low LHC luminosity（1029cm-2s-1）

16. π0 spectra QGSJETII ⇔ DPMJET3χ2= 106 (C.L. <10-6)
Pi zero produced at collision can be extracted by using gamma pair events
Powerful to eliminate beam-gas BG
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

17. Neutron spectra Energy spectra at detector front
Resolution included spectra

18. New models (PICCO, EPOS)
Proton
New models (PICCO, EPOS)
Drescher, Physical Review D77,
(2008)
Pi0
Neutron

19. LPM effect
○ w/o LPM
■ w/ LPM
Transition curve of a 1 TeV photon w/ and w/o LPM to be measured by LHCf

20. Run schedule
LHCf runs will be carried out during the LHC commissioning with low luminosity L<1030cm-2s-1
Data taking at 10TeV collisions in 2008 and 14TeV collisions in 2009
Dedicated run with beam crossing angle in under discussion (pseudo-rapidity limit 8.7 => 8.4)
Future runs during ion collisions in study

21. Summary
Interpretation of CR observation data in eV strongly depends on the interaction model used in the analysis.
LHCf will set a crucial calibration point at 1017eV for the interaction models.
LHCf can measure E, p spectra of gamma-rays, π0 and neutrons at η>8.7 (8.4).
LHCf can clearly discriminate existing/proposed models with a short operation under very low luminosity condition.

22. Backup

23. Knapp, Shower curve
大気深さ
シャワー粒子数

24. Calorimeter 44 radiation lengths, 1.7 hadron interaction lengths
n, gamma
44 radiation lengths, 1.7 hadron interaction lengths
16 sampling scintillators
4 position layers (2 for EM, 2 for hadron)
GeV gammaに対して <5%の分解能

25. Manipulator 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

26. Energy resolution (gamma-rays)5%
1TeV
↑　MC simulation <7TeV
← SPS beam test <200GeV

27. Position resolution