1. Massimo Bongi - INFN Florence LHCf Collaboration
7th International Conference on Radiation Effects on Semiconductor Materials, Detectors and Devices (RESMDD)
15-17 October 2008
Florence
Astroparticle Physics at LHC: the LHCf experiment ready for data taking
Massimo Bongi - INFN Florence
LHCf Collaboration
Massimo Bongi - RESMDD October Florence

2. Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
Overview
Cosmic-Ray Physics goals
Ultra-High-Energy CR spectrum
composition of High-Energy CR
(Monte Carlo codes calibration)
LHCf detectors and experimental set-up
Physics performance
Current status
Massimo Bongi - RESMDD October Florence

3. Ultra-High-Energy Cosmic Rays
Experimental observations:
(shower of secondary particles)
lateral distribution
longitudinal distribution
particle type
arrival direction
Extensive Air Showers
Air shower development (particle interaction in the atmosphere)
Astrophysical parameters:
(primary particles)
spectrum
composition
source distribution
origin and propagation
Massimo Bongi - RESMDD October Florence

4. UHECR spectra and the GZK cutoff
AGASA x 0.9
HiRes x 1.2
Yakutsk x 0.75
Auger x 1.2
Massimo Bongi - RESMDD October Florence

5. Calibration of models with experimental data
UHECR spectra and the GZK cutoff
GZK cutoff would limit energy to 1020eV (for protons, due to Cosmic Microwave Background):
p + γ(2.7K)  Δ  N + π
Different hadronic interaction models give different answers for the primary CR energy estimate.
(for instance, AGASA reports 18% as systematic uncertainty in energy determination, 10% being due to the interaction model)
Calibration of models with experimental data
Massimo Bongi - RESMDD October Florence

6. Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
HECR composition
Xmax(g/cm2)
The depth of the maximum of the shower Xmax in the atmosphere depends on energy and type of the primary particle.
Different hadronic interaction models give different answers about the composition of HECR.
PROTON
IRON
UA7
LHCf
Energy(eV)
Massimo Bongi - RESMDD October Florence

7. HECR composition Auger
Xmax measurements favors heavier composition as the energy increases
Anisotropy would favor proton primaries (AGN correlation)
Massimo Bongi - RESMDD October Florence

8. Development of atmospheric showers
1019 eV proton
The dominant contribution to the shower development comes from particles emitted at low angles in the interaction of the primary CR (forward region).
The knowledge of the π-production cross-section in the forward region is needed in order to correctly estimate the energy of the primary CR.
The highest-energy data currently available are at 1014 eV
1990)
Massimo Bongi - RESMDD October Florence

9. Astroparticle Physics at LHC
LHCf will use the highest energy particle accelerator to provide useful data to calibrate the hadronic interaction models used in Monte Carlo simulations of atmospheric showers.
7 TeV + 7 TeV proton collisions at LHC (ECM = 14 TeV) correspond to ELAB = 1017 eV (ELAB ≈ ECM2/(2mp))
Massimo Bongi - RESMDD October Florence

10. The LHCf Collaboration
CERN
D.Macina, A.L. Perrot
USA
LBNL Berkeley:
W. Turner
FRANCE
Ecole Politechnique Paris:
M. Haguenauer
JAPAN:
STE Laboratory Nagoya University:
K.Fukui,Y.Itow, T.Mase, K.Masuda,Y.Matsubara, H.Menjo,T.Sako, K.Taki, H. Watanabe
Waseda University: K. Kasahara, M. Mizuishi, Y.Shimizu, S.Torii
Konan University: Y.Muraki
Kanagawa University Yokohama: T.Tamura
Shibaura Institute of Technology: K. Yoshida
SPAIN
IFIC Valencia:
A.Fauss, J.Velasco
ITALY
Firenze University and INFN: O.Adriani, L.Bonechi, M.Bongi, G.Castellini, R.D’Alessandro, P.Papini, S. Ricciarini, A. Viciani
Catania University and INFN: A.Tricomi
Massimo Bongi - RESMDD October Florence

11. Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
The LHC ring
ATLAS (IP1)
Massimo Bongi - RESMDD October Florence

12. Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
Experimental set-up
INTERACTION POINT
IP1 (ATLAS)
Beam line
Arm#2
Tungsten
Scintillator
Silicon microstrips
Arm#1
Scintillating fibers
140 m
Two independent electromagnetic calorimeters equipped with position sensitive layers, on both sides of IP1 will measure energy and position of γ from π0 decays.
Massimo Bongi - RESMDD October Florence

13. Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
Experimental set-up
Charged particles
Neutral particles
Beam pipe
Protons
The detectors are installed in the TAN region, where the beam pipe splits into 2 separate tubes.
Charged particles are deflected away, only neutral particles hit the detectors.
LHCf
96 mm
Massimo Bongi - RESMDD October Florence

14. Arm#1 detector Scintillating Fibers
4 pairs of layers (6, 10, 32, 38 r.l.)
tracking measurements
2 towers stacked vertically with 5 mm gap
24 cm long
upper: 4.0 cm x 4.0 cm area
lower: 2.0 cm x 2.0 cm area
Absorber
22 tungsten layers mm – 14 mm thick
(W: X0 = 3.5mm, RM = 9mm)
Plastic Scintillator
16 layers mm thick
trigger and energy profile measurements
Massimo Bongi - RESMDD October Florence

15. Arm#2 detector Silicon Microstrip (from ATLAS SCT)
4 pairs of layers (6, 12, 30, 42 r.l.)
tracking measurements
2 towers stacked on their edges and offset from one another
24 cm long
upper: 3.2 cm x 3.2 cm area
lower: 2.5 cm x 2.5 cm area
Absorber
22 tungsten layers mm – 14 mm thick
(W: X0 = 3.5mm, RM = 9mm)
Plastic Scintillator
16 layers mm thick
trigger and energy profile measurements
Massimo Bongi - RESMDD October Florence

16. The detectors are ready since 2007
Arm#1 detector
Arm#2 detector
Massimo Bongi - RESMDD October Florence

17. Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
Front Counter
2 Scintillator Counters
installed in front of Arm#1 and Arm#2
segmented in 2 X and 2 Y slices
check the beam quality, reduce background events and decide whether to move Arm#1 and Arm#2 in the operating position from the “garage” position
Massimo Bongi - RESMDD October Florence

18. Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
LHCf Physics
Single photon spectrum
p0 mass reconstrucion (1 photon in each tower)
p0 reconstruction is an important tool for energy calibration (p0 invariant mass constraint)
Basic concept:
2 towers for p0 reconstruction
Smallest tower on the beam (to reduce multiple hits)
Dimension of the tower  Moliere radius
Maximum acceptance (given the LHC and TAN constraints)
Simulation has been used to understand the physics performances
Beam tests in 2004, 2006 and 2007, to evaluate:
energy resolution
spatial resolution of the tracking part
Massimo Bongi - RESMDD October Florence

19. LHCf acceptance on PT-E  plane
140
Beam crossing angle
Detectable events
A vertical beam crossing angle > 0 will
increase the acceptance of LHCf
Massimo Bongi - RESMDD October Florence

20. LHCf single g geometrical acceptance
Mechanical manipulators allows to remotely move LHCf: some runs with the detectors vertically shifted few cm will allow to cover the whole kinematical range
Massimo Bongi - RESMDD October Florence

21. LHCf : Monte Carlo discrimination
106 generated LHC interactions
~ min cm-2s-1 luminosity
already allows discrimination between various models (5% energy resolution included)
Massimo Bongi - RESMDD October Florence

22. LHCf: model dependence of neutron energy distribution
Neutron spectra at detector front
30% energy resolution included
Massimo Bongi - RESMDD October Florence

23. LHCf energy resolution
2.5 x 2.5 cm2 tower
2.0 x 2.0 cm2 tower
Energy resolution ~ 3% at high energy,
even for the smallest tower
Massimo Bongi - RESMDD October Florence

24. Pion reconstruction   Calorimeters
350 GeV Proton beam
(not in scale) 
Carbon target (3 cm)
in the slot used for beam monitor
9.15 m
Arm#1
>107 proton on target (special setting from the SPS people)
Egamma=18GeV
Shower First SciFi Layer
Calorimeters
20mm X
40mm Y
Egamma=46GeV
Massimo Bongi - RESMDD October Florence

25. Pion mass reconstruction
 250 pion events triggered (in a quite big background)
Δm ~ 8 MeV
Δm/m ~ 6%
Preliminary
(MeV)
Massimo Bongi - RESMDD October Florence

26. Arm#1 position resolution
200 GeV electrons
σX=172µm
Number of event
σX[mm]
x-pos[mm]
E[GeV]
σY=159µm
σY[mm]
Number of event
y-pos[mm]
E[GeV]
Massimo Bongi - RESMDD October Florence

27. Arm#2 position resolution
200 GeV electrons
σX=40µm
σX[µm]
x-pos[mm]
E[GeV]
σY=64µm
σY[µm]
y-pos[mm]
Alignment has been taken into account
Massimo Bongi - RESMDD October Florence
E[GeV]

28. Radiation damage studies
Dose evaluation on the basis of LHC reports on radiation environment at IP1
< cm-2s-1 luminosity are expected
some tens Gy during 1 week operation lead to ~10% light output decrease
scintillators will be monitored and decrease of light output will be corrected by laser calibration
Silicon detectors from ATLAS SCT (see next talk!)
test of Scintillating fibers and scintillators
30 kGy
Massimo Bongi - RESMDD October Florence

29. LHCf Arm#1 – Installation completed
Massimo Bongi - RESMDD October Florence

30. LHCf Arm#2 – Installation completed
Massimo Bongi - RESMDD October Florence

31. LHCf ready for data taking
The LHCf control room in the ATLAS area
Massimo Bongi - RESMDD October Florence

32. Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
Dummy event
Massimo Bongi - RESMDD October Florence

33. LHCf ready for data taking
On September 10 we observed some signals on Front Counters, with Arm#1 and Arm#2 in garage position for safety reasons
That day the Atlas BPTX signal was still not available (no info on the real bunches in the Atlas zone)
On September 11 Atlas gave us the synchronized BPTX signals, and we could take Front Counter data by using this signal (still in garage position)
We are measuring beam-gas interactions from beam2 on Arm#1 side
Massimo Bongi - RESMDD October Florence

34. LHCf ready for data taking
Massimo Bongi - RESMDD October Florence

35. Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
Conclusions
Detectors construction and installation completed in 2008
Preparation for running completed
First beam gas events acquired
We are ready for LHC data
Massimo Bongi - RESMDD October Florence