1. Stato del calorimetro elettromagnetico
Nuove misure a TERAS (maggio)
TEST beam al PSI (ottobre – novembre-dicembre)
Lxe facility
Criostato
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2. TERAS g Beam Line Compton Spectrum (Eg-Ec/2)2+(Ec/2)2 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
Collimator size
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3. Data MC simulation Short labs D: 20~100  0~25cm Long labs g
LP operato con Xenon purificato
D: depth parameter
Data
MC simulation D D
Short labs
Previous Test D=
D: 20~100  0~25cm D
Long labs D
This Test D g
Baldini 23 sett
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4. Energy Spectrum Fitting
For understanding simply…
Suppose Response function is an asymmetric Gaussian
Principle…
Compton Spectrum
Response function Eg
Npe
s left
Convolution of
Compton Spectrum
Response Function
s right
Baldini 23 sett
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5. 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 tail
f(x) = Nexp{t/s2(t/2-(x-x0)}, x<x0+t
Nexp{-1/2((x-x0)/s)2}, x>x0+t
Convolution
Integration +/- 5s
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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6. Energy Resolution vs. Depth Parameter
For g incident at the detector center
D > 35, 45, 55….85
Resolution: < 2% in sigma except shallow events (D<45). D
Number of Photoelectrons
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7. LP al PSI (meta’ agosto): test in ottobre/novembre con fotoni monocromatici
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8. 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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9. Experimental configuration
TARGET?
-- beam A C T
Mod
Rate
Background
Thin/small (angle/X0)
Handling
NaI
Previous use
GH2 (Panofsky….)
LH2 (PIBETA)
CH2 (MEGA, prec.misure)
LiH (e  at SIN)
Coincidence:
C & !A & NaI
(Offline: & LXe)
LXe
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10. Misure del 1999 8%FWHM D=100 cm 10 x 10 window 9.5 hours
60 cm (NaI) 75 cm (CsI)
11 x 13 window
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11. Lxe facility
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12. 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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13. Photon Detector schedule
2002
2003
2004
2005
Large Prototype
Beam Test
Beam Test
Engineering runs
Vessel Design
Manufactoring
Assembly & Test
PMT Delivery + Testing
Assembly
Test
Refrigerator
Manufactoring
Assembly
Liq. Purification
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Design
Manufactoring
Assembly
Test
Milestone