LHCf
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, 15-19
Apr 2007
W.C. Turner – The LHCf Experiment
1
LHCf
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, 15-19
Apr 2007
W.C. Turner – The LHCf Experiment
2
LHCf
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, 15-19
Apr 2007
W.C. Turner – The LHCf Experiment
3
LHCf
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 400 + 400 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, 15-19
Apr 2007
W.C. Turner – The LHCf Experiment
4
The LHCf detectors are located
+/-140m from IP1 in LHC
LHCf
IP5, CMS
IP1, ATLAS, LHCf
IP8, LHCb
IP2, ALICE
Aspen Workshop on CRP, 15-19
Apr 2007
W.C. Turner – The LHCf Experiment
5
LHCf
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, 15-19
Apr 2007
W.C. Turner – The LHCf Experiment
6
LHCf
Exploded view of the TAN and
transition beam tube
Instrumentation slot (96mm x 60.7mm x 1000mm)
IP, +140m
~ 5m
Aspen Workshop on CRP, 15-19
Apr 2007
W.C. Turner – The LHCf Experiment
7
LHCf
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, 15-19
Apr 2007
W.C. Turner – The LHCf Experiment
8
LHCf
Aspen Workshop on CRP, 15-19
Apr 2007
W.C. Turner – The LHCf Experiment
9
LHCf
Arm#1 during assembly
32 PMTs + 8 MAPTs
Light guides
Tower calorimeters
Aspen Workshop on CRP, 15-19
Apr 2007
W.C. Turner – The LHCf Experiment
10
LHCf
Aspen Workshop on CRP, 15-19
Apr 2007
Transverse projection of LHCf
and beam pipe acceptance
W.C. Turner – The LHCf Experiment
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LHCf
LHCf Arm#1 acceptance
“450 mrad” <=> 140 mrad xing angle
“310 mrad” <=> 0 mrad xing angle
Aspen Workshop on CRP, 15-19
Apr 2007
W.C. Turner – The LHCf Experiment
12
LHCf
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, 15-19
Apr 2007
W.C. Turner – The LHCf Experiment
13
LHCf
Aspen Workshop on CRP, 15-19
Apr 2007
The LHCf team for 2006
SPS Beam Tests
W.C. Turner – The LHCf Experiment
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LHCf
SPS H4 Setup
Aspen Workshop on CRP, 15-19
Apr 2007
W.C. Turner – The LHCf Experiment
15
LHCf
SPS test beam 2004 results
Beam
Energy(GeV)
Measurements
Electron beam
50, 100, 150,
200
Simulate photon showers,
measure energy resolution,
spatial resolution and shower
leakage
Proton beam
150, 350
Simulate neutron showers
Muon beam
150
Obtain calibration for single mip,
measure non-uniformity of light
collection efficiency
Aspen Workshop on CRP, 15-19
Apr 2007
W.C. Turner – The LHCf Experiment
16
LHCf
Light efficiency correction measured
with a muon beam
Aspen Workshop on CRP, 15-19
Apr 2007
W.C. Turner – The LHCf Experiment
17
LHCf
Shower leakage, energy
resolution, SPS data +MC
Fig. 7 MC simulation, include it?
Aspen Workshop on CRP, 15-19
Apr 2007
W.C. Turner – The LHCf Experiment
18
LHCf
Aspen Workshop on CRP, 15-19
Apr 2007
MC simulation shows the shower
leakage fraction is energy
independent
W.C. Turner – The LHCf Experiment
19
LHCf
Position resolution
Aspen Workshop on CRP, 15-19
Apr 2007
W.C. Turner – The LHCf Experiment
20
LHCf
e-p/g-n separation
LHCf = 44rad lengths, 2 hadron interaction lengths
L20-90 = discrimination parameter
= distance between 20% and 90% of longitudinal sum of shower
particles
Aspen Workshop on CRP, 15-19
Apr 2007
W.C. Turner – The LHCf Experiment
21
MC calculations of p0 mass
and neutron energy resolutions
LHCf
p0 inv mass res ~ 5%
Aspen Workshop on CRP, 15-19
Apr 2007
Neutron energy res ~ 30%
W.C. Turner – The LHCf Experiment
22
LHCf
Arm#1 pre-installed Jan 07,
Arm#1&2 final installation ~ Sep 07
IP1 140m away
LHCf Arm#1
TAN
Aspen Workshop on CRP, 15-19
Apr 2007
W.C. Turner – The LHCf Experiment
23
LHCf
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 midMay.)
– 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, 15-19
Apr 2007
W.C. Turner – The LHCf Experiment
24