1. The LHCf detectors: zero degree calorimeters at LHC for cosmic ray physics
Tsuyoshi Mase
for the LHCf collaboration
Solar-Terrestrial Environment Laboratory,
Nagoya University

2. Outline Motivation of the LHCf experiment LHCf detector Conclusion
High energy cosmic ray problem
hadron interaction model
LHCf detector
Location
Discrimination the hadron interaction models
Design
Performance (SPS beam test and simulation)
Conclusion
12 Mar. 2009
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3. Energy spectrum of cosmic rays
Knee; acceleration limit of galactic CRs?
GZK cutoff; Propagation limit due to CMB
Engel, Nuclear Phys. B (Proc. Suppl.) 151 (2006)
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4. Cosmic ray composition by Auger
Xmax favors heavy primary
interpretation strongly depends on the hadron interaction model
Confirmation of the various models using the LHC is important key for the cosmic ray physics.
Anisotropy favors light primary
(if accept AGN correlation)
12 Mar. 2009
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5. LHC accelerator ALICE LHCb ATLAS / LHCf CMS / TOTEM
The 14TeV center of momentum energy of the LHC will push the laboratory equivalent collision energy up to 10^17eV.
ATLAS / LHCf
LHCb
CMS / TOTEM
ALICE
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6. The LHCf collaborator
K.Fukui, Y.Itow, T.Mase, K.Masuda, Y.Matsubara, H.Menjo, T.Sako, K.Taki
Solar-Terrestrial Environment Laboratory, Nagoya University, Japan
K.Yoshida Shibaura Institute of Technology, Japan
K.Kasahara, M.Mizuishi, S.Torii
Waseda University, Japan
T.Tamura Kanagawa University, Japan
Y.Muraki Konan University
Y.Shimizu ICRC, University of Tokyo, Japan
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
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7. Location of LHCf LHCf 140m 140m Arm1 Arm2 90cm I.P.
Detectors installed in the TAN region, 140m away from the Interaction Point.
Both side of I.P.
(Arm1 and Arm2)
LHCf covers pseudo-rapidity > 8.4
neutral particle absorber
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8. Model dependence in LHCf
Gamma Spectrum
Model Discrimination by Gamma, Neutron and p0
expected spectra using some hadron interaction models
12 Mar. 2009
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9. LHCf Detector1 (Arm1) Impact point Energy
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
4 pairs of scintillating fiber layers for tracking purpose (6, 10, 32, 38 r.l.)
Absorber
22 tungsten layers mm – 14 mm thick
(W: X0 = 3.5mm, RM = 9mm)
44 radiation length
1.7 interaction length
16 scintillator layers (3 mm thick)
Trigger and energy profile measurements
Energy
12 Mar. 2009
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10. LHCf Detector2 (Arm2) Impact point Energy
We used LHC style
electronics and readout
Impact point
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
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
Absorber
22 tungsten layers mm – 14 mm thick (2-4 r.l.)
(W: X0 = 3.5mm, RM = 9mm)
Energy
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11. Double arm detectors 290mm Arm#2 Detector Arm#1 Detector 90mm
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12. Compact calorimeter and shower leakage correction
Compact two tower calorimeter
need for science
fit the limit of TAN
avoid multi-hit
reconstruct p0 invariant mass
The p0 mass can be reconstructed in the invariant mass distribution of two gamma -rays, one each hitting the two tower calorimeters of Arm1 or Arm2.
Shower leakage occurs
The fraction of shower leakage is only a function of the position and independent of the energy
12 Mar. 2009
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13. SPS beam test electron Calibration the performance muon proton
2007 Aug Sep.11
Aim for SPS beam test
　Calibration the performance
Energy Calibration
Energy Resolution
Position Resolution
particle ID
electron
50, 100, 150, 180, 200GeV/c
muon
150GeV/c
proton
150, 350GeV/c
LHCf Detector
LHCf Detector
ADAMO (silicon tracker)
Trigger scintillator
Beam Pipe
Silicon Tracker
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14. Energy Resolution SPS beam test result and simulation
Summing up the signal in all the layers, the energy resolution is defined as root-mean-square of the distribution.
SPS beam test result
and simulation
Simulation at the LHC condition
L.G.
= Low PMT Gain
H.G.
= High PMT Gain
12 Mar. 2009
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15. Position Resolution (SciFi : Arm1)
200 GeV electrons
SPS beam test result
The center determined by
the SciFi is compared with the incident particle position estimated by ADAMO.
Simulation at the LHC
condition
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16. Position Resolution (Silicon : Arm2)
SPS beam test result
This analysis was done using ADAMO for the reconstruction of the trajectory of each particle hitting the calorimeter.
200 GeV electrons
64mm x 64mm total surface area
285mm thick n-type wafer
A sequence of 768 p+ microstrips with 80mm pitch
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17. in the slot used for beam monitor
p0 reconstruction (1)
350 GeV Proton beam
Not in scale!
gamma
Carbon target (3 cm)
in the slot used for beam monitor
9.15 m
Arm1
Egamma=18GeV
Shower First SciFi Layer
Calorimeters
20mm X
40mm Y
Egamma=46GeV
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18. p0 reconstruction (2)
 250 p0 events triggered (in a quite big background)
The background is caused by uncorrelated pairs those accidentally hit the two calorimeters simultaneously.
The background distribution was evaluated by shifting the events in the two calorimeters so that any correlated pairs disappear.
12 Mar. 2009
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19. Radiation test
The LHCf detectors will be exposed to a considerable amount of ionizing radiation
Using 290MeV/n Carbon beam and 100TBq 60Co gamma ray
100Gy
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20. LHCf Operation LHCf operation
Luminosity < 1030 cm-2 s-1
107 inelastic collision
3 days operation
The decrease of the light output is not large for doses of interest for LHCf
The laser calibration system can correct
The manipulators move the detectors to the safe position
100Gy
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21. Conclusion
LHCf will set a crucial calibration point at 1017eV for the hadron interaction models
The LHCf detectors are sampling and imaging calorimeters
locate both side of the IP1 (Arm1 and Arm2)
made of plastic scintillators interleaved with tungsten converters
correct the shower leakage from the calorimeter
Performance was evaluated by SPS and simulation
energy resolution is 5% above 100GeV gamma-ray
position resolution is
reconstruct p0 mass
Radiation damage is negligible
12 Mar. 2009
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