Download - Stato del calorimetro elettromagnetico
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Stato del calorimetro elettromagnetico
• Nuove misure a TERAS (maggio)
• TEST beam al PSI (ottobre – novembre-dicembre)
• Lxe facility
• Criostato
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TERAS Beam Line
• Electron beam– Energy: 764MeV– Energy spread: 0.48%(sigma)– Divergence: <0.1mrad(sigma)– Beam size: 1.6mm(sigma)
• Laser photon– Energy: 1.17e-6x4 eV (for 40MeV)– Energy spread: 2x10-5 (FWHM)– Divergence: unknown– Beam size: unknown
Compton Spectrum
•(E-Ec/2)2+(Ec/2)2
Collimator size
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• D: depth
parameter MC simulationData
Previous Test
This Test
Short abs
Long abs
D=
D
DD
DD
D: 20~100 0~25cm
LP operato con Xenon purificato
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Energy Spectrum Fitting
• Principle…
E Npe
Response functionCompton Spectrum
Convolution of
Compton Spectrum
Response Function
•For understanding simply…•Suppose Response function is an asymmetric Gaussian
left
right
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Energy Spectrum Fitting cont’d• Require D(depth
parameter)>45– ~34% of events in the range
of 40MeV+/-4MeV are discarded by this requirement
• Suppose Compton Spectrum around the edge(E-Ec/2)2+Ec2/4
• Detector Response Function– Gaussian with Exponential tailf(x) = Nexp{t/2(t/2-(x-x0)}, x<x0+t
Nexp{-1/2((x-x0)/)2}, x>x0+t
• Convolution– Integration +/- 5
Fitting is done in two steps•Determine the edge position
•Fix the edge in the 2nd fitting for determining the other prams
Detection efficiency (estimated by MC) : 74% within +/- 4% energy cut at 52.8 MeV (cf. Progress Report Jul 02)
(16% of events are lost due to interaction with material in front of the active volume)
26%
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Energy Resolution vs. Depth Parameter
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
30 40 50 60 70 80 90
Sigma2 threshold
Res
olut
ion
(%)
Number of Photoelectrons
D
• For incident at the detector center
• D > 35, 45, 55….85• Resolution: < 2% in sigma
except shallow events (D<45).
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LP al PSI (meta’ agosto): test in ottobre/novembre con fotoni monocromatici
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The elementary process - (essentially) at rest captured on protons:
- p 0 n - p n
0
Photon spectrum
54.9 82.9 129 MeV
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Experimental configuration
NaI
LXeCoincidence:
C & !A & NaI
(Offline: & LXe)
-- beam
AC T Mod
TARGET?•Rate
•Background
•Thin/small (angle/X0)
•Handling
Previous use
•GH2 (Panofsky….)
•LH2 (PIBETA)
•CH2 (MEGA, prec.misure)
•LiH (e at SIN)
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Misure del 1999
•D=100 cm
•10 x 10 window
•9.5 hours
•60 cm (NaI) 75 cm (CsI)
•11 x 13 window
8%FWHM
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Lxe facility
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Criostato• Necessita’ di rivedere il disegno (appoggio esterno )• Selezione materiale finestra di ingresso• Simulazioni nuovo progetto• Contatto con Ditte produttrici il prima possibile
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Photon Detector schedule
2002 2003 2004 2005
Test MilestoneAssemblyDesign Manufactoring
Large Prototype Beam Test Beam Test
Vessel Design Assembly & Test
PMT Delivery + Testing
Refrigerator Manufactoring Assembly
Liq. Purification
Assembly Test
Manufactoring
Engineering runs