A. Baldini 23 sett CSN I Lecce

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Stato del calorimetro elettromagnetico

• Nuove misure a TERAS (maggio)

• TEST beam al PSI (ottobre – novembre-dicembre)

• Lxe facility

• Criostato

A. Baldini 23 sett CSN I Lecce

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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

A. Baldini 23 sett CSN I Lecce

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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

A. Baldini 23 sett CSN I Lecce

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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

A. Baldini 23 sett CSN I Lecce

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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%

A. Baldini 23 sett CSN I Lecce

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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).

A. Baldini 23 sett CSN I Lecce

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LP al PSI (meta’ agosto): test in ottobre/novembre con fotoni monocromatici

A. Baldini 23 sett CSN I Lecce

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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

A. Baldini 23 sett CSN I Lecce

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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)

A. Baldini 23 sett CSN I Lecce

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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

A. Baldini 23 sett CSN I Lecce

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Lxe facility

A. Baldini 23 sett CSN I Lecce

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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

A. Baldini 23 sett CSN I Lecce

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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