Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
Massimo Bongi - INFN Florence
LHCf Collaboration
Astroparticle Physics at LHC: the LHCf experiment ready
for data taking
7th International Conference on Radiation Effects on Semiconductor Materials, Detectors and Devices
(RESMDD)
15-17 October 2008Florence
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 - RESMDD08 - 15 October 2008 - Florence
Ultra-High-Energy Cosmic Rays
Experimental observations:(shower of secondary particles)•lateral distribution•longitudinal distribution•particle type•arrival direction
Extensive Air Showers
Astrophysical parameters:(primary particles)•spectrum•composition•source distribution•origin and propagation
Air shower development (particle
interaction in the atmosphere)
Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
UHECR spectra and the GZK cutoff
AGASAx 0.9HiRes x 1.2Yakutsk
x 0.75Auger x 1.2
Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
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 - RESMDD08 - 15 October 2008 - Florence
HECR composition
Energy(eV)
Xm
ax(g
/cm
2)
PROTON
IRON
UA7
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.
LHCf
Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
HECR composition
Auger Xmax measurements
favors heavier composition as the energy increases
Anisotropy would favor proton
primaries (AGN correlation)
Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
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 (UA7@SppS, 1990)
Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
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 - RESMDD08 - 15 October 2008 - Florence
The LHCf Collaboration
ITALYITALYFirenze University and INFN:Firenze University and INFN: O.Adriani, L.Bonechi, O.Adriani, L.Bonechi, M.Bongi, G.Castellini, M.Bongi, G.Castellini, R.D’Alessandro, P.Papini, S. R.D’Alessandro, P.Papini, S. Ricciarini, A. VicianiRicciarini, A. VicianiCatania University and Catania University and INFN:INFN: A.Tricomi A.Tricomi
JAPAN:JAPAN:STE Laboratory Nagoya University:STE Laboratory Nagoya University:K.Fukui,Y.Itow, T.Mase, K.Fukui,Y.Itow, T.Mase, K.Masuda,Y.Matsubara, K.Masuda,Y.Matsubara, H.Menjo,T.Sako, K.Taki, H. H.Menjo,T.Sako, K.Taki, H. WatanabeWatanabeWaseda University:Waseda University: K. Kasahara, M. K. Kasahara, M. Mizuishi, Y.Shimizu, S.ToriiMizuishi, Y.Shimizu, S.ToriiKonan University:Konan University: Y.Muraki Y.MurakiKanagawa University Yokohama: Kanagawa University Yokohama: T.TamuraT.TamuraShibaura Institute of Technology:Shibaura Institute of Technology: K. YoshidaK. Yoshida
SPAINSPAINIFIC Valencia:IFIC Valencia: A.Fauss, A.Fauss, J.VelascoJ.Velasco
FRANCEFRANCEEcole Politechnique Paris:Ecole Politechnique Paris:M. HaguenauerM. Haguenauer
USAUSALBNL Berkeley:LBNL Berkeley:W. TurnerW. Turner
CERNCERND.Macina, A.L. PerrotD.Macina, A.L. Perrot
Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
The LHC ring
ATLAS (IP1)
Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
Experimental set-up
INTERACTION POINTINTERACTION POINT
IP1 (ATLAS)IP1 (ATLAS)
Beam lineBeam line
Arm#2Arm#2
TungstenTungsten
ScintillatorScintillator
Silicon Silicon microstripsmicrostrips
Arm#1Arm#1
TungstenTungsten
ScintillatorScintillator
Scintillating Scintillating fibersfibers
140 m140 m 140 m140 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 - RESMDD08 - 15 October 2008 - Florence
Experimental set-up
96 mm
Charged particlesCharged particles
Neutral particlesNeutral particles
Beam pipeBeam pipe
ProtonsProtons
LHCf
• 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.
Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
Arm#1 detector
Plastic Scintillator
16 layers 3 mm thick
trigger and energy profile measurements
Absorber
22 tungsten layers 7mm – 14 mm thick
(W: X0 = 3.5mm, RM = 9mm)
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
Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
Arm#2 detector
Plastic Scintillator
16 layers 3 mm thick
trigger and energy profile measurements
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 7mm – 14 mm thick
(W: X0 = 3.5mm, RM = 9mm)
Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
Arm#1 detector Arm#2 detector
The detectors are ready since 2007
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 - RESMDD08 - 15 October 2008 - Florence
LHCf Physics Single photon spectrum 0 mass reconstrucion (1 photon in each tower)
0 reconstruction is an important tool for energy calibration (0 invariant mass constraint)
Basic concept: • 2 towers for 0 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 - RESMDD08 - 15 October 2008 - Florence
Detec
table
eve
nts
141400
Beam crossing angle
LHCf acceptance on PT-E plane
A vertical beam crossing angle > 0 will increase the acceptance of LHCf
Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
LHCf single 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 - RESMDD08 - 15 October 2008 - Florence
LHCf : Monte Carlo discrimination
• 106 generated LHC interactions
• ~ min exposure @1029 cm-2s-1 luminosity
• already allows discrimination between various models (5% energy resolution included)
Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
Neutron spectra at detector front 30% energy resolution included
LHCf: model dependence of neutron energy distribution
Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
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 - RESMDD08 - 15 October 2008 - Florence
Pion reconstruction
9.15 m9.15 m
350 GeV Proton beam350 GeV Proton beam
Carbon target (3 cm)in the slot used for beam monitor Arm#1Arm#1
(not in scale)(not in scale)
Egamma=18GeV
Shower Profile @ First SciFi Layer Shower Profile @ First SciFi Layer Calorimeters Calorimeters
20mm
X
40mm
X Y
YEgamma=46GeV
>107 proton on target (special setting from the SPS people)
Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
Pion mass reconstruction
(MeV)
Prelim
inary
250 pion events triggered (in a quite big background)
Δm ~ 8 MeVΔm/m ~ 6%
Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
Arm#1 position resolutionN
um
ber
of
even
tN
um
ber
of
even
t
x-pos[mm]
y-pos[mm]
200 GeV electrons
E[GeV]
E[GeV]
σX=172µm
σY=159µmσ X
[mm
]σ Y
[mm
]
Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
Arm#2 position resolutionPosition Resolution X Side
0
20
40
60
80
100
120
0 50 100 150 200 250
Energy (GeV)
Re
so
luti
on
(m
icro
ns
)
Data
Simulation Spread Out
x-pos[mm]
y-pos[mm]
Position Resolution Y Side
0
20
40
60
80
100
120
140
160
0 50 100 150 200 250
Energy (GeV)
Re
so
luti
on
(m
icro
ns
)
Data
Simulation Spread Out
Alignment has been taken into account
200 GeV electrons
E[GeV]
E[GeV]
σX=40µm
σY=64µmσ X
[µm
]σ Y
[µm
]
Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
Radiation damage studies
30 kGy
Dose evaluation on the
basis of LHC reports on
radiation environment at
IP1
<10 Gy/day @ 1029 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
Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
LHCf Arm#1 – Installation completed
Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
LHCf Arm#2 – Installation completed
Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
LHCf ready for data taking
The LHCf control room in the ATLAS area
Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
Dummy event
Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
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 - RESMDD08 - 15 October 2008 - Florence
LHCf ready for data taking
Massimo Bongi - RESMDD08 - 15 October 2008 - Florence
Detectors construction and installation completed in 2008
Preparation for running completed First beam gas events acquired We are ready for LHC data
Conclusions
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