infn of genova, pavia and roma flavio gatti, psi, february 9 th, 2005 1 timing counter status timing...

Flavio Gatti, PSI, February 9Flavio Gatti, PSI, February 9thth, 2005, 2005 11

INFN of Genova, Pavia and Roma

Timing Counter statusTiming Counter status



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



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°



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



Exemple of PMs output of Exemple of PMs output of single countersingle counter



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



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)



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)



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



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.



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



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



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

infn of genova, pavia and roma flavio gatti, psi, february 9 th, 2005 1 timing counter status timing...

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