1. LHCf: a LHC Detector for Astroparticle Physics
EDS th International Conference on Elastic and Diffractive Scattering - Forward Physics and QCD
Hamburg 21 – 25 May, 2007
LHCf: a LHC Detector for Astroparticle Physics
Alessia Tricomi
University and INFN Catania
on behalf of the LHCf Collaboration

2. The LHCf Collaboration
CERN
D.Macina, A.L. Perrot
USA
LBNL Berkeley:
W. Turner
FRANCE
Ecole Politechnique Paris:
M. Haguenauer
SPAIN
IFIC Valencia:
A.Fauss, J.Velasco
JAPAN:
STE Laboratory Nagoya University:
Y.Itow, T.Mase, K.Masuda,Y.Matsubara, H.Matsumoto,H.Menjo,T.Sako,H. Watanabe
Waseda University: K. Kasahara, Y.Shimizu, S.Torii
Konan University: Y.Muraki
Kanagawa University Yokohama: T.Tamura
ITALY
Firenze University and INFN: O.Adriani,, L.Bonechi, M.Bongi, G.Castellini, R.D’Alessandro, P.Papini
Catania University and INFN: A.Tricomi
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

3. The LHCf experiment at LHC EDS07, Hamburg 21-25 May 2007
Outline
Introduction
Main problems in HECR physics: GZK cut off, chemical composition
Idea of LHCf
Measurement of neutral particles emitted into very forward at LHC
Simulation and test beam results
Calibration of MC code
Conclusions, plans and schedule
Toward the LHC operation
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

4. Introduction: GZK cut off
GZK cutoff: 1020 eV
super GZK events?!?
Huge experiment (Auger, TA) will solve the statistics, but not for interaction model.
29th ICRC
Pune (India)
AGASA reports 18% systematic uncertainty in energy determination.
10% of systematic is due to interaction model.
Accelerator calibration is necessary.
HOWEVER
Different interaction models give different answers for
the primary cosmic ray energy estimate.
20% correction on the
absolute energy scale!!!
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

5. Introduction: cosmic ray composition
IRON
PROTON
Xmax(g/cm2)
Not only GZK…
Different interaction models lead
different conclusions about the
composition of the primary cosmic rays.
Energy (eV)
Knapp et al., 2003
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

6. Development of atmospheric showers
Simulation of an atmospheric shower due to a 1019 eV proton.
Calibration of the models at high energy is mandatory
The dominant contribution to the energy flux is in the very forward region (  0)
In this forward region the highest energy available measurements of p0 cross section were done by UA7 (E=1014 eV, y= 5÷7)
LHC
We propose to use LHC, the highest energy accelerator
14 TeV in the center of mass
Elab=1017 eV (Elab= E2cm/2 mP)
Major LHC detectors (ATLAS, CMS, LHCB) will measure the particles emitted in the central region
LHCf is a tool to calibrate MC code to energy relevant
for CR physics. It will cover the very forward part
May be also Heavy Ion runs????
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

7. The LHCf experiment at LHC EDS07, Hamburg 21-25 May 2007
The LHC ring
27 km ring
IP1
ATLAS
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

8. LHCf: location and experimental layout
INTERACTION POINT
IP1 (ATLAS)
Beam line
Detector II
Tungsten
Scintillator
Silicon mstrips
Detector I
Scintillating fibers
140 m
Detectors should measure energy and position of g
from p0 decays e.m. calorimeters with
position sensitive layers
Two independent detectors on both side of IP1
Redundancy
Background rejection (especially beam-gas)
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

9. The LHCf experiment at LHC EDS07, Hamburg 21-25 May 2007
LHCf location
Detectors will be installed in the TAN region, 140 m away from the Interaction Point, in front of luminosity monitors
Here the beam pipe splits in 2 separate tubes.
Charged particle are swept away by magnets!!!
We will cover up to y
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

10. Detector #1 Impact point (h) 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 7mm – 14 mm thick
(W: X0 = 3.5mm, RM = 9mm)
16 scintillator layers (3 mm thick)
Trigger and energy profile measurements
Energy
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

11. The LHCf experiment at LHC EDS07, Hamburg 21-25 May 2007
Arm 1
Arm1 was fully assembled in Japan in July 2006 (scintillators + fibers + Tungsten) and fully tested at CERN in August 2006 beam test
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

12. Detector # 2 Impact point (h) Energy
We used LHC style
electronics and readout
Impact point (h)
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 7mm – 14 mm thick (2-4 r.l.)
(W: X0 = 3.5mm, RM = 9mm)
Energy
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

13. The LHCf experiment at LHC EDS07, Hamburg 21-25 May 2007
Arm 2
Arm2 was partially assembled in Florence in July 2006 and brought to CERN for the Beam Test of August 2006
Arm2 was fully assembled in Florence in April 2007
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

14. LHCf Physics performance
Single photon spectrum
p0 fully reconstructed (1 g in each tower)
p0 reconstruction is an important tool for energy calibration (p0 mass constraint)
Basic detector requirements:
minimum 2 towers (p0 reconstruction)
Smallest tower on the beam (multiple hits)
Dimension of the tower  Moliere radius
Maximum acceptance (given the LHC constraints)
Simulation
Beam Test
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

15. LHCf performances: acceptance on PTg-Eg plane
Detectable events
140
Beam crossing
angle
A vertical beam crossing angle > 0 will
increase the acceptance of LHCf
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

16. LHCf performances: single g geometrical acceptance
Some runs with LHCf vertically shifted few cm
will allow to cover the whole kinematical range
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

17. LHCf performances: g shower in Arm #2
500 GeV g shower
Position resolution of detector # 2
Fluka based simulation
7 mm for 1.8 TeV g
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

18. LHCf performances: p0 mass resolution
Arm #1
DE/E=5%
200 mm spatial resolution
Dm/m = 5%
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

19. The LHCf experiment at LHC EDS07, Hamburg 21-25 May 2007
LHCf performances: Monte Carlo g-ray energy spectrum (5% Energy resolution is taken into account)
106 generated LHC interactions  1 Minute cm-2s-1 luminosity
Discrimination between various models
is feasible
Quantitative discrimination with the help of a properly defined c2 discriminating variable based on the spectrum shape
(see TDR for details)
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

20. LHCf performances: model dependence of neutron energy distribution
Original n energy
30% energy resolution
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

21. Performances of the LHCf Detector
Measured at the SPS
Beam Test in 2004
SciFi Position Resolution
Energy Resolution
LHCf can measure (and provide to LHC) the center of neutral flux from the collisions
If the center of the
neutral flux hits LHCf
 << 1 mm resolution
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

22. Now the real installation in LHC…
The idea is that installation takes place in 2 steps:
Pre-installation
Final installation
In between the 2 installation the baking out of the beam pipe will be done (200 oC), so the detectors should be removed
Pre-Installation dates have been fixed in Fall 2006
LSS1L (Arm1)
8/01/2007 to 26/01/2007  FINISHED!
LSS1R (Arm2)
23/04/2007 to 11/05/2007  FINISHED!
Final installation dates are still under discussion
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

23. The LHCf experiment at LHC EDS07, Hamburg 21-25 May 2007
LHCf – Installation
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

24. Transport and insertion in the TAN
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

25. The LHCf experiment at LHC EDS07, Hamburg 21-25 May 2007
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

26. LHCf possible running scenario
Phase-I
Parasite running during the early stage of LHC commissioning (end of 2007 – beginning of 2008)
Remove LHCf when luminosity reaches 1030 cm-2s-1 for radiation reason
Phase-II
Re-install the detector at the next opportunity of low luminosity run
Phase-III
Future extension for p-A, A-A run with upgraded detectors???
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

27. LHCf: conclusions and plans
LHCf approved in June 2006 by the LHCC
Physics performances:
able to measure π0 mass with ±5% resolution.
able to distinguish the models by measurements of π0 and γ
able to distinguish the models by measurements of n
Beam crossing angle ≠0 and/or vertical shifts of LHCf by few cm will allow more complete physics measurements
Detectors:
ARM1 and ARM2 fully ready
Performance measured in Test Beams
Installation well advanced
ARM1 successfully pre-installed in January 07
ARM2 successfully pre-installed in April-May 07
Final installation date under discussion
Running conditions:
Three foreseen phases
Phase I: low luminosity run during LHC commissioning
Phase II: low luminosity runs and possibly LHCf dedicated runs
Phase III: Heavy Ion runs ?
Waiting for LHC beams!!!
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

28. The LHCf experiment at LHC EDS07, Hamburg 21-25 May 2007
Back-up slides
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

29. The LHCf experiment at LHC EDS07, Hamburg 21-25 May 2007
The TAN and LHCf
box ~ (15×15×40) cm3
manipulator
marble
shielding
boxes for
DAQ electronic
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

30. Transverse projection of detector #1 in the TAN slot
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

31. Transverse projection of detector #2 in the TAN slot
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

32. The LHCf experiment at LHC EDS07, Hamburg 21-25 May 2007
Lateral view of ARM #2
Front scintillator
Front scintillator:
Fixed position wrt to TAN
Silicon + Tungsten + Scintillator:
+/- 5 cm vertical excursion
Si Tracker + Hybrid
PMTR7400
Beam axis
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

33. The LHCf experiment at LHC EDS07, Hamburg 21-25 May 2007
g rate
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

34. The LHCf experiment at LHC EDS07, Hamburg 21-25 May 2007
p0 rate
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

35. g ray energy spectrum for different positions
QGSJETII: used model
QGSJET: c2/DOF=107/125
DPMJET3: c2/DOF=224/125
SYBILL: c2/DOF=816/125
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

36. The CERN test beam on August 2004
e, m, p beam
Silicon
Calorimeter
Before correction
After correction
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007
2 mm

37. The LHCf experiment at LHC EDS07, Hamburg 21-25 May 2007
Monte Carlo
Leak Correction
N Particles
MC predicts that the
leakage is energy independent!
Prototype Experiment
Distance from Edge
correction
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

38. Estimate of the background
beam-beam pipe
 E γ(signal) > 200 GeV, OK
background < 1%
beam-gas
 It depends on the beam condition
background < 1% (under Torr)
beam halo-beam pipe
 It has been newly estimated from the beam loss rate
Background < 10% (conservative value)
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

39. The LHCf experiment at LHC EDS07, Hamburg 21-25 May 2007
SPS Beam Test
Test was successful
Analysis is under way for
Energy calibration of the calorimeters
Spatial resolution of the tracking systems
CERN : SPS T2 H4
2006 Aug. 28 – Sep. 4
Incident Particles
Proton　 150,350GeV/c
Electron 100,200GeV/c
Muon GeV/c
Setup
LHCf
Detector
Silicon
Tracker
Moving Table
Trigger
Scintillator
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

40. Effect of LHCf on BRAN measurement
LUMI monitor (BRAN) inside TAN is beyond LHCf (replacing 4th copper bar)
IP1
Cu Bar / ZDC
LHCf
LHCf
Cu Bar / ZDC
Lumi
Lumi
The effect of LHCf on BRAN measurements has been studied in the last months by simulation
Reduction of shower particles at BRAN
Position dependence on beam displacement
(question from machine peoples: if we shift by 1 mm the real beam, does the center of the measured neutral energy shifts by 1 mm?)
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

41. BRAN response vs beam position
Relative change of the reduction factors for BRAN with respect to the nominal value (center of the beam: nominal one)
If the position of beam center stays within a few mm from the beam-pipe center, the reduction factors do not change more than 10%
1 x 1
cm2
Arm #1
Arm #2
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007
H.Menjo

42. LHCf performances: p0 geometrical acceptance
Arm #1
Arm #2
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

43. LHCf performances: energy spectrum of p0
Typical energy resolution of g is 3 % at 1TeV
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

44. Optimal LHCf run conditions
Beam parameter
Value
# of bunches
≤ 43
Bunch separation
> 2 msec
Crossing angle
rad
140 mrad downward
Luminosity per bunch
< 2 x 1028 cm-2s-1
Luminosity
< 0.8 x 1030 cm-2s-1
Bunch intensity
4x1010 ppb (b*=18m)
1x1010 ppb (b*= 1m)
Beam parameters used for commissioning are good for LHCf!!!
( No radiation problem for 10kGy by a “year” operation with this luminosity )
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

45. The LHCf experiment at LHC EDS07, Hamburg 21-25 May 2007
From R. Bailey presentation at January 2007 TAN workshop
Optimal conditions for LHCf running!
Stage 1
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007

46. The LHCf experiment at LHC EDS07, Hamburg 21-25 May 2007
From R. Bailey presentation at January 2007 TAN workshop
Alessia Tricomi University & INFN Catania
The LHCf experiment at LHC EDS07, Hamburg May 2007