KEK BT Summary &Plan Shinshu University Miho Nishiyama.

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KEK BT Summary &Plan Shinshu University Miho Nishiyama

Transcript of KEK BT Summary &Plan Shinshu University Miho Nishiyama.

KEK BTSummary &Plan

Shinshu University

Miho Nishiyama

KEK Fuji beam line・ Electron beam・ This beam is made form bremsstrahlung photons from KEKB ring・ Beam spot size: ~ 3cm x 4 cm・ Beam energy : 3 GeV ・ Rate: 15Hz @ 3 GeV

beam

Setup

Semiconductor Tracker(borrowed by ATLAS Group) 12cm×6cmResolution vertical : 23μm horizontal: 580μm

Veto counter

Beam e-

Scintillator Fiber Tracker

Trigger countersMovable stage

Scintillator strips

scintillator

Beam e-

Semiconductor Tracker

Scintillator Fiber Tracker

Scintillator strips

Movable stage

Veto counter

Scintillator

Setup of side view

A B C D E F

beam

Scintillator Strips

Method Read-

out

Cover Thickness(mm)

A1

Extruded

Fiber

TiO2

3

No fiber !

A2 good positioning

B1

Reflector

big hole

B2 matched hole

C1 Direct TiO2

D

KurarayDirect

Reflector

2E

3F Fiber reference

• 8 layers with different types of strips• 4 same type strips per one layer

All collected events MIP events

Response for MIP

extruded TiO2

No fiber

extruded TiO2

good matching

extrudedreflectorbad matching

extrudedreflector good matching

extruded TiO2

Kurarayreflector

Kurarayreflectorthickness:2mm

Kurarayreflector

reference

Num

ber

of e

vent

s (lo

g sc

ale)

Signal (ADC counts)

0 5000 0 5000 0 5000

0 0 0 0

0

5000 5000 5000 5000

5000

Response for MIPVariation of strip by strip

Num

ber

of e

vent

s (lo

g sc

ale)

Signal (ADC counts)

All collected events MIP events

Extruded scintillator strip + reflector film good matching

These plots show the variation of strip by strip is big.

There are 4 results since we’ve prepared 4 strips read out per one layer.

Uniformity

extruded TiO2

No fiber

extruded TiO2

good matching

extruded reflector bad matching

extruded reflectorgood matching

extruded TiO2

Kuraray reflector  thickness:2mm

Kurarayreflector

Kuraray reflector

reference

Beam position (mm)

Sig

nal (

AD

C c

ount

s)

Beam position (mm)

Sig

nal (

AD

C c

ount

s)Uniformity

Variation of strip by strip

Extruded scintilattor strip + reflector film good matching

These plots show the variations of the uniformity aren’t so big. However light yields aren’t same.

Sig

na

l (A

DC

co

un

ts)

Beam position (mm)

Direct Photon 25%

1mm 1mmφ

Direct Photon 100%

1mmDirect Photon 25%

4.5cm

0.4cm1cm

Scintillator strip

Sensitive area of MPPC Fiber

Problems were found at KEK BT・ Direct photons caused significant non-uniformity.

MPPC

Conclusion• The position of fiber and MPPC is important.

 → We asked KNU to make extruded scintillator

strips with the precise size of fiber hole and

position .

• Reflector film works better than TiO2 .

→We asked KNU to make scintiilator stirip

without TiO2.

• Direct photons may cause significant non-uniformity.

→Bench test has been done .

Setup

PMT

Discriminator Gate Generator

90SrMPPC

ADC

(Vbias = 76.5 [ V])

Trigger scintillator

Thermostatic chamber (25 )℃

Extruded with TiO2

Collimator with2 mmhole

Signal input

Gateinput

AMP (x63)

72 [ns]

KIMOTO reflector

Position of-ray source

×x mm

MPPC

57mm

Measurement of 3 ways

1mmφ 1mmφ

White paint to shield direct light

KIMOTO reflector to shield direct light

Scintillator with TiO2

Nothing to shield direct light

the length of fiber : 43mm Fiber : 57mm Fiber : 43mm

Result of measurementFiber : 43mmFiber : 57mm + KIMOTO reflectorFiber : 43mm + white paint

MPPC side

To look into two peaks…

Check the response for MIP of MPPC side and another.

4.5cm

1cm 1cm

MPPC sideAnother side

extruded TiO2

Good matching

extrudedreflector filmGood matching

Response for MIPN

umbe

r of

eve

nts

(log

scal

e)

Signal (ADC counts)

MIP eventsMIP events (MPPC side)MIP events (another side)

extruded TiO2

extruded TiO2

Good matching

extrudedReflector filmBad matching

extruded Reflector filmGood matching

extruded TiO2

Kuraray(2mm) Kuraray(3mm) Kuraray(3mm)

Plan

• Two peak (~January)

• Comparison of absolute light yield (~March)

• Bias voltage dependence (~March)

Back up

MIP selection  

MIP selected strip

spacer

Only pedestal signal

For the selected strip, MIP event must satisfy following conditions: ・ In the same layer, strips show the pedestal signal but the selected strip.

・ In the front and the rear layer, the strips at same position of the selected strip show the MIP signal.  

MIP signal

e-