1. LHCf - an experiment for measuring the very forward
production of neutral particles at the LHC
W.C. Turner
LBNL
for
the LHCf Collaboration
Presented at the Aspen Workshop on Cosmic Rays
15-19 Apr 2007
Aspen Workshop on CRP, Apr 2007
W.C. Turner – The LHCf Experiment

2. W.C. Turner – The LHCf Experiment
The LHCf Participants
Nagoya University, Japan
K. Fukui, Y. Itow, T. Mase, K. Masuda, Y. Matsubara, H. Matsumoto, H. Menjo,
T. Sako, K. Taki, H. Watanabe
Kanagawa University, Japan
T. Tamura
Konan University
Y. Muraki (Spokesperson),
Waseda University, Japan
K. Kasahara, Y. Shimizu, S. Torii
Shibaura Inst. of Tech., Japan
K. Yoshida
University of Florence, Italy
O. Adriani, L. Bonechi, M. Bongi, G. Castellini, R. D’Alessandro, P. Papini
University of Catina, Italy
A. Tricomi
Univerity of Valencia, Spain
A, Faus-Golffe, J. Valesco
CERN, Switzerland
D. Macina, A.-L. Perrot
Ecole-Polytechnique Palaiseau, France
M. Hauguenauer
Lawrence Berkeley Laboratory, USA
W.C. Turner
Aspen Workshop on CRP, Apr 2007
W.C. Turner – The LHCf Experiment

3. W.C. Turner – The LHCf Experiment
Outline
Motivation and History of LHCf
The LHC Environment
The LHCf Detectors
Anticipated LHCf Performance
SPS Beam Test and Monte Carlo Results
Installation and Schedule
Aspen Workshop on CRP, Apr 2007
W.C. Turner – The LHCf Experiment

4. Motivation and History
Use 7+7 TeV pp collisions to benchmark neutral particle production cross sections at 1017eV laboratory equivalent energy
Useful for cosmic ray simulations, contribute to resolution of super GZK and composition questions
Previous experiment UA7 performed at SPPS GeV, 1014 eV (E. Pare et al, Phys. Lett., B242 (1990))
Present Experiment LOI submitted to LHCC in May 2004 and TDR approved in 2006
Prototype detector tested at SPS H4 in 2004 and final detector in 2006
First detector installed at IP1 in Jan 2007
Aspen Workshop on CRP, Apr 2007
W.C. Turner – The LHCf Experiment

5. The LHCf detectors are located +/-140m from IP1 in LHC
IP1, ATLAS, LHCf
IP5, CMS
IP2, ALICE
IP8, LHCb
Aspen Workshop on CRP, Apr 2007
W.C. Turner – The LHCf Experiment

6. W.C. Turner – The LHCf Experiment
Interaction region
TAN neutral particle absorber
The TAN absorbs forward neutral collision products (mostly
neutrons and photons) and is placed in front of the outer beam separation
dipole D2 to protect superconducting magnets
LHCf exploits the opportunity to install detectors inside the TAN for
measurement of very forward neutral particle production cross sections
Aspen Workshop on CRP, Apr 2007
W.C. Turner – The LHCf Experiment

7. Exploded view of the TAN and transition beam tube
IP, +140m
Instrumentation slot (96mm x 60.7mm x 1000mm)
~ 5m
Aspen Workshop on CRP, Apr 2007
W.C. Turner – The LHCf Experiment

8. W.C. Turner – The LHCf Experiment
The LHCf detectors are compact
sampling and imaging calorimeters
Measure 100 GeV - 7 TeV gammas and neutrons
Detectors are located on both sides of IP1 (Arm#1 and Arm#2) for coincidence studies and redundancy
Each Arm consists of two “tower” calorimeters for separately measuring the two gammas from p0 decay
44 radiation lengths of W plates interleaved with 16 scintillation panels (overall length 25cm)
Transverse cross sections 20mm x 20mm + 40mm x 40mm Arm#1 and 25mm x 25mm + 32mm x 32mm Arm#2
Four position sensitive layers measure the transverse center of the showers
Arm#1 SciFi (1mm x1 mm)
Arm#2 Si microstrip detectors(80mm pitch)
Aspen Workshop on CRP, Apr 2007
W.C. Turner – The LHCf Experiment

9. W.C. Turner – The LHCf Experiment
Aspen Workshop on CRP, Apr 2007
W.C. Turner – The LHCf Experiment

10. W.C. Turner – The LHCf Experiment
Arm#1 during assembly
32 PMTs + 8 MAPTs
Light guides
Tower calorimeters
Aspen Workshop on CRP, Apr 2007
W.C. Turner – The LHCf Experiment

11. Transverse projection of LHCf and beam pipe acceptance
Aspen Workshop on CRP, Apr 2007
W.C. Turner – The LHCf Experiment

12. W.C. Turner – The LHCf Experiment
LHCf Arm#1 acceptance
“450 mrad” <=> 140 mrad xing angle
“310 mrad” <=> mrad xing angle
Aspen Workshop on CRP, Apr 2007
W.C. Turner – The LHCf Experiment

13. PMT + scintillator linearity ~+/- 2% over anticipated dynamic range
Dynamic range req’d: 1 mip (muon calibration of light collection efficiency) to
7x104 mips (7 TeV gamma shower max)
“mips” simulated with Nitrogen
Laser excitation of scintillator
Aspen Workshop on CRP, Apr 2007
W.C. Turner – The LHCf Experiment

14. W.C. Turner – The LHCf Experiment
The LHCf team for 2006
SPS Beam Tests
Aspen Workshop on CRP, Apr 2007
W.C. Turner – The LHCf Experiment

15. W.C. Turner – The LHCf Experiment
SPS H4 Setup
Aspen Workshop on CRP, Apr 2007
W.C. Turner – The LHCf Experiment

16. W.C. Turner – The LHCf Experiment
SPS test beam 2004 results
Beam Energy(GeV) Measurements
Electron beam 50, 100, 150, Simulate photon showers, measure energy resolution, spatial resolution and shower leakage
Proton beam 150, 350 Simulate neutron showers
Muon beam Obtain calibration for single mip, measure non-uniformity of light collection efficiency
Aspen Workshop on CRP, Apr 2007
W.C. Turner – The LHCf Experiment

17. Light efficiency correction measured with a muon beam
Aspen Workshop on CRP, Apr 2007
W.C. Turner – The LHCf Experiment

18. Shower leakage, energy resolution, SPS data +MC
Fig. 7 MC simulation, include it?
Aspen Workshop on CRP, Apr 2007
W.C. Turner – The LHCf Experiment

19. MC simulation shows the shower leakage fraction is energy independent
Aspen Workshop on CRP, Apr 2007
W.C. Turner – The LHCf Experiment

20. W.C. Turner – The LHCf Experiment
Position resolution
Aspen Workshop on CRP, Apr 2007
W.C. Turner – The LHCf Experiment

21. W.C. Turner – The LHCf Experiment
e-p/g-n separation
LHCf = 44rad lengths, 2 hadron interaction lengths
L = discrimination parameter
= distance between 20% and 90% of longitudinal sum of shower particles
Aspen Workshop on CRP, Apr 2007
W.C. Turner – The LHCf Experiment

22. MC calculations of p0 mass and neutron energy resolutions
p0 inv mass res ~ 5%
Neutron energy res ~ 30%
Aspen Workshop on CRP, Apr 2007
W.C. Turner – The LHCf Experiment

23. Arm#1 pre-installed Jan 07, Arm#1&2 final installation ~ Sep 07
IP1 140m away
LHCf Arm#1
TAN
Aspen Workshop on CRP, Apr 2007
W.C. Turner – The LHCf Experiment

24. Plans for future operation with LHC
“450 x 450 GeV Engineering Run” ~Oct - Dec 2007
(Could get delayed to 2008 owing to inner triplet problems! Will know in mid-May.)
Observe first pp collisions and background rates due to beam-gas, beam halo collisions etc
Low event rates owing to reduced acceptance,
single g >10GeV ~20Hz
p0 reconstruction below background
“Stage 1” 7 TeV x 7 TeV beam commissioning ~Jun - Sep 2008
Luminosity ~1029cm-2 s-1, inelastic collision rate ~ 8kHz
43 x 43 bunches => 2msec bunch spacing matches max DAQ rate
Single g>100GeV rate ~ 800Hz
Two g p0 rate ~ 80Hz (106 events in 3.5 hrs)
Two arm coincidence ~ 80Hz
Neutrons >100GeV ~ 4kHz
Remove LHCf when Luminosity > 1030cm-2 s-1 to avoid rad. damage
Aspen Workshop on CRP, Apr 2007
W.C. Turner – The LHCf Experiment