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Timing Counter statusTiming Counter status
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Timing Counter key featuresTiming Counter key features
Scintillator Cross Section
70º
PM outerDiameter :52 mm
PM activediameter: 39 mm
19º 22º8.5º
From COBRA center
105 cm
10º
25 cm
BB
0.75 T1.05 T
Rotated Scintillator Slab
☺ greater response uniformity and better timing performance achievable by using the coincidences
☺ Positron Path-Length (5 cm) enough for required p.e. statistics
Maximal Matching Scin.-PM
☺ all PM active area covered
PM tilted of ~ 20º to Mag. Field
☺ lower Field Gain suppression factor
Sectional view
Long. view
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PhotomultipliersPhotomultipliers
PMDrift
Chamberassembly
Scintillator slab
COBRAMagnet
PMs have been separately tested insideCOBRA for gain and TTS. Ordered in theFall 2004. Should be delivered in April.
Tilting angle reduced to 11°
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Beam test Beam test Frascati (nov 04) Frascati (nov 04) Beam focus
x=2.5 mmy=3.0 mm
5 mm Beam Geom. Select Fast 2-electron
bunch veto
Beam
Scint. Slab Scint. Slab
Scint. Slab
Slow calorimeter
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Exemple of PMs output of Exemple of PMs output of single countersingle counter
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Timing Resolution BC 408
100
105
110
115
120
125
130
135
140
-40 -30 -20 -10 0 10 20 30 40distanc e from c enter (c m)
DT
(p
s) F
WH
M
90 deg
65 deg
53 deg
40 deg
Goal
All data for BC408 vs position at variuos All data for BC408 vs position at variuos
impact anglesimpact angles
Distance from center
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All data for BC404 vs position at All data for BC404 vs position at several impact angleseveral impact angle
Timing resolution of BC 404
70
75
80
85
90
95
100
105
-40 -30 -20 -10 0 10 20 30 40
distanc e from c enter (c m)
D
90 deg
65 deg
53 deg
40 deg
Goal
Distance from center(5cm)
DT FWHM (ps)
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Comparison and final choiceComparison and final choice
comparison: BC404 vs. BC 408@ impact angle = 53 deg
70
80
90
100
110
120
130
140
-40 -30 -20 -10 0 10 20 30 40
distance from center (cm)
DT
(ps)
FW
HM
BC404
BC408
goal
Distance from the center(cm)
DT FWHM (ps)
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Validation test of single Validation test of single counter in COBRA (dec 04)counter in COBRA (dec 04)
19° 22°
From COBRA center
105 cm 25 cm
BB
Pulsed Laser
Pulsed Laser
101 ps FWHM
98 ps FWHM
@ Frascati Beam
@ COBRA
Light diffusor
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Comments Comments BC404 average resolution=91psBC404 average resolution=91ps BC408 average resolution = 113psBC408 average resolution = 113ps Timing resolution over the whole length = ±5% Max.Timing resolution over the whole length = ±5% Max. Underlying systematic effect:Underlying systematic effect:
1.1. Slope of Slope of DDT vs position : different Q.E. of both PMsT vs position : different Q.E. of both PMs2.2. Up/down structure: focusing effect, non uniform Up/down structure: focusing effect, non uniform
surface roughness,…surface roughness,…3.3. Intrinsic rise-time of plastic scintillator plays a Intrinsic rise-time of plastic scintillator plays a
significant role in the timing performances of the two significant role in the timing performances of the two plasticsplastics
4.4. These effects are under study.These effects are under study. Plastics sizes, shapes and PM coupling works fine.Plastics sizes, shapes and PM coupling works fine. The solution has been indirectly validate in the COBRAThe solution has been indirectly validate in the COBRA A test with the DRS in order to verify the readout A test with the DRS in order to verify the readout
solutions is foreseen.solutions is foreseen.
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TC Final DesignTC Final Design• A PLASTIC (BLACK PLEXIGLASS) SUPPORT STRUCTURE ARRANGES THESCINTILLATOR BARS AS REQUESTED
• THE BARS ARE GLUED ONTOTHE SUPPORT
• “LIGHT” INTERFACE ELEMENTS ARE GLUED ONTO THE BARS AND SUPPORT THEFIBRES
• FIBRES ARE GLUED AS WELL
• TEMPORARY ALUMINIUM BEAMS ARE USED TO HANDLE THE DETECTOR DURINGINSTALLATION
• PTFE SLIDERS WILL ENSUREA SMOOTH MOTION ALONG THE RAILS
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TC designTC design• PMTs ARE ATTACHED, BYMEANS OF THE INTERFACE SOCKET, TO THESCINTILLATOR BARS
• GIVEN THE MASS, AN ELASTIC AND REMOVABLE SILICONE GLUE ISAPPROPRIATE
• THE HOLLOW INTERFACEELEMENT IS A “CUSTOMDESIGNED”PROFILE THAT ADDS A MINIMUM AMOUNT OF MATERIAL BETWEENTHE FIBRES AND THE BARS
• SLOT FOR CABLES and OPTICAL FIBERS HAVE BEEN FORESEEN TOALLOW THE CABLES FROM THE INNER PMT TO EXIT
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Comments on DesignComments on Design
Final design has been done and the main parts of the TC Final design has been done and the main parts of the TC have been fixedhave been fixed
PM’s, Scintillator plastics, Scintillating Fiber are PM’s, Scintillator plastics, Scintillating Fiber are already ordered.already ordered.
Building “Blocks”, such us PM’s socket, Hollow Building “Blocks”, such us PM’s socket, Hollow interface for scintillating fiber will be produces interface for scintillating fiber will be produces soon.soon.
He bag under studyHe bag under study New batch of not irradiate APD have been delivered in New batch of not irradiate APD have been delivered in
these days. If test will be positive, we have to these days. If test will be positive, we have to concentrate the construction of the 2 curved detectors concentrate the construction of the 2 curved detectors in the next 6-8 monthsin the next 6-8 months