Systematic Studies of Small Scintillators for New Sampling Calorimeter

E.P.Jacosalem, S.Iba, N.Nakajima, H.Ono, A.L.Sanchez, A.M.Bacala & H.Miyata

GLD Calorimeter Group

LCWS06 (Linear Collider Workshop 2006)Indian Institute of Science, Bangalore, India

March 9 - 13, 2006

2

Outline:Introduction

Calorimeter designMotivation

Bench Test Set-upResultsSummaryFuture plansAcknowledgment

3

Previous Calorimeter Designs

10x200x2mm Strip-array EM Calorimeter 40x40mm Tile Calorimeter Module

Beam experiments at KEK: T517 in 2002 & T454 in 2004

4

Proposed Calorimeter Designs (GLD DOD Draft)

EMCAL Scintillator Design

Motivation : To come up with the optimal size of small strip type scintillator and appropriate wrapping reflector that will have the best light collection efficiency

HCAL Scintillator Design

MPPC

MPPC

MPPC MPPC

MPPC

MPPC

5

Bench Test set-up

Sensor

PMT

PMT

HV90Sr

WLS fiber

Collimator

HV

Black Box

Trigger

Discri-minator

OctalPulse Amp

GateGen

1

GateGen 2

GateGen

3

ADC

Int.Reg.

Cable 15m(75ns delay)

PC

Veto

Veto

Gate

CH7

Logic Circuit

6

WLS fiber16 Ch PMT

Trigger scint

Collimator & source

sensor

Photograph of the Bench test set-up

7

Strip Type Scintillator

White Paint wrapping reflector (1.7mm groove for 1.6mm WLS fiber)

10x40x2mm scintillator (1.4mm groove for 1mm fiber)

10x160x2mm

10x80x2mm

10x40x2mm

3M Radiant Mirror Film

Teflon

Black tape

White Paint + Teflon

Gold Coat

White Paint

Aluminum Coat

10x120x2mm

WLS fiber dia: 1.0mm ;1.6mm

10x10mm teflon-wrapped scintillator

8mm thick

6mm thick

5mm thick

4mm thick

2mm thick

Block Type Scintillator

8

Plotted the pulse height (ADC Counts) vs. sensor’s length with different wrapping reflectors

Measured and plotted the position dependence across and along the strip scintillator

Determined the number of photoelectrons

Signal Pulse Height

pedestal

signal fitted pulse height

1.0cm

2.5 mm

Top view

Strip-type Sensor

Source point

9

Pulse height slightly increases except for white paint and black tape wrapped scintillator

Greatest pulse height : 3M reflective mirror film and teflon

Systematic error: 3M : ± 17 ; Teflon : ± 15

Teflon

Whitepaint + Teflon

Aluminum coat

Black tape

Whitepaint

3M radiant mirror film

10Greatest light yield: 3M reflective mirror film wrapped scint.

Systematic error: 3M : ± 5.4 ; Teflon : ± 10

Teflon

Whitepaint + Teflon

Aluminum coat Black tape

Whitepaint

3M radiant mirror film

11

PMT

1.6mmΦ WLS_3Mmirror film

1.0mmΦ WLS_3Mmirror film

1.6mmΦ WLS_ Teflon

1.0mmΦ WLS_ Teflon

Position dependence along the strip scintillator showed the uniformity of light transmission from the sensor to PMT.

Keyhole

WLS fiber

measurementalong the strip

measurement across the strip

12

small peaks

Fiber diameter

1.6mm

1mm

‘dip’ at the center small peaks near the fiber (1.6mmΦ fiber) no significant difference on PH values at 2 different locations light yield increases 100% as fiber diameter increase for 3M radiant mirror film.

r = 20mm r = 30mm

r = 20mm r = 30mm

r = source distance from the edge

13

3M radiant mirror film

Teflon

Top view

5.0mm

2.5mm

Block-type Sensor

Source point

No trigger is observed at 8mm thick.

Pulse height directly proportional with scint thickness.

Pulse height about the same level as strip scintillator.

14

Comparison of simulation and bench test results on PH dependence on sensors length and wrapping reflector.

Simulation results is in good agreement with the bench test results.

simulation results (by Sayaka Iba)

3M radiant mirror film

Whitepaint

Black tape

15

Bench test result

simulation results show a drop at fiber location is ~50%; no drop at both sides; narrow opening (@ drop).bench test ~ 40% ; with drop at both sides; wider opening

Comparison of Bench Test & Simulation results on Position Dependence across the 10x40x2m 3M radiant film covered scintillation

Simulation result (by: Sayaka Iba)

16 Ave. light yield is 9.2 photoelectrons in a 10x40x2mm 3M radiant mirror film wrapped scintillator

PH=13.8 ADC

PH = 126.9 ADC

17

Summary

3M radiant mirror film covered scintillator has the greatest light yield for both WLS fiber diameters (1.0 & 1.6mm).

Light yield increases by 100% as WLS fiber diameter increases from 1.0mm to 1.6mm for 3M radiant mirror film wrapped scintillator

Block type scintillator’s pulse height is proportional to its thickness.

18

Summary cont..

Position dependence along the strip scintillator shows the uniformity of light transmission of the WLS fiber from scintillator to PMT.

Dip at the center of the strip scintillator is dependent on the size of fiber groove.

Simulation results for the PH dependence on sensor’s length and wrapping reflector in good agreement with the bench test results.

19

Future plans

Do simulations for other type of scintillators.

Test the best light yield scintillator using photon sensor or MPPC as read out through WLS fiber.

20

AcknowledgmentMSU-IIT, Philippines

CHED – COE, Philippines

Department of Physics, Niigata University, Japan

Japan Student Services Organization (JASSO) Short-Term Student Exchange Promotion Program

Dr. T. Takeshita

ACFA, Prof. S. Kurokawa

LCWS06 Organizers

Simulation conditions:

• Scintillator: x: width : 10mm; Y: length: 40,80, 120mm

• Fiber : diameter: 1.0mm ; length: 20cm

• Attenuation length of scintillator: 400mm ; fiber : 3500mm

• Refractive index scintillator : 1.50 ; fiber : 1.49

• Density of fiber (dye of fiber) : 200.0 ppm

• Absorption rate of fiber : 0.01338

• Wrapping reflector reflectivity:

– 3M mirror film: top and bottom 95%; side 80%; total reflection

– white paint: top and bottom 95%; side 90%; random reflection

– Black tape: top and bottom 30%; side 20%; scint & air 90%; total reflection

Flow of simulation: by S. Iba