Aerogel Quality Check

1
Aerogel Quality Check
Kyoto University Takeo Shirai

• Contents
• Motivation
• Transmittance measurement
• Cherenkov Light Yield measurement
• Summary

2
Beam Catcher (Single Module)
Single Module

• Aerogel
• 5 cm thick
• Mirror
• flat mirror
• Funnel
• Winston cone
• PMT
• 5inch PMT
• For mass production , quality control of
• Aerogel optical properties is important

5inch PMT
Winston-type funnel
lead sheet (2mmt)
Cerenkov light
Aerogel
flat mirror
3
Aerogel Quality Check System

• We are developing the checking system
• for two important optical properties
• Transmittance Measurement
• LED(Light Source) PMT
• Cherenkov Light Yield Measurement
• Solenoid Magnet spectrometer

4
Setup for Transmittance Measurement

• PMT with 2mm hole mask detects LED light
• 30mmX30mm area is scanned at 2mm interval
• by moving X-Y stage

Masked by black paper with a 2mmX2mm hole
UV,BLUE,GREEN, YELLOW,RED 5-COLORS
Aperture
Aperture
PMT on XY stage
Aerogel on X-Y stage

• position dependence of transmittance can be
  measured

5
Measurement results (Example for BLUE LED
l470nm)
AIR
mm
Aerogel with Clean surface n1.03
Aeorgel with rough surface n1.03
mm
mm
6
Forward scattering and transmittance

• Forward Scattering dominates

Mie scattering?

• Scattering angle is small enough
• Can be detected in 5inch PMT
• Can be included as transmitted lights

• Define transmittance by

225
225
7
Transmittance-Rayleigh scattering-
Note that Rayleigh scattering is dominant in
Aerogel
The Tile with rough surface n1.03
The tile with Clean surface n1.03
transmittance
transmittance
A0.93 CT0.0088mm4
A0.82 CT0.0094mm4
Absorption also increase
l(nm)
?(nm)
Two parameters, A and CT, are used as the input
to our MC simulation . Can it predict correct
light yield?
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Measurement of Cherenkov Light Yield
b sourceGap-type Solenoid Magnet gt Spectrometer

• We can get monochromatic electron beam
• Variable Energy up to a few MeV
• Beam intensity of 30 Hz _at_2.5MeV

r
Concept of Electron trajectory in this magnet

• POINT
• TWO MAGNETS
• Large acceptance
• High Resolution
• parallel e- beam along Z-axis

IRON
Ru
COIL
Electron rotate by Bz
GAP
Magnetic Field is strong near the gap
0.8 m
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Spec of the Spectrometer
Energy spectrum of 106Ru with and without magnet
keV
Spectrum of focused electron
? data ? Expectation
A
keV
10
Measurement of Cherenkov Yield by the
Spectrometer


Setup
Cherenkov image on PMT

• b source
• 106Ru(3.541MeV)

5inchPMT
MC

• Two trigger Scintillators are placed downstream
  of 10f hole at the mirror surface

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Cherenkov Yield Energy Dependence Measurement1

• We measure the Cherenkov light yield with
  changing the energy of electron

Example of the results for two aerogel samples
(thickness11mm) with similar transmittance but
different refractive index
n1.05 TR69_at_470nm
P.E
n1.03 TR67_at_470nm
P.E
? GEANT ? DATA
? GEANT ? DATA
Incident Energy of electron
Incident Energy of electron
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Cherenkov Yield Energy Dependence Measurement2
Example of the results for two aerogel samples
(thickness11mm) with the same refractive index
but different transmittance
n1.03 TR67_at_470nm
n1.03 TR85_at_470nm
P.E
P.E
1.9 P.E _at_2.4MeV
1.5 P.E _at_2.4MeV
? GEANT ? DATA
? GEANT ? DATA
Incident Energy of electron
Incident Energy of electron
A0.82 CT0.0094µm4
A0.94 CT0.0044µm4
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High Energy e- BEAM TEST

• We measure the cherenkov light Yield
• using 60Mev electron beam

Cherenkov Light Yield (Aerogel thickness1.1cm)
vs refractive index
? GEANT ? DATA
Refractive index
1.046
1.05
1.03
AIR
These results are consistent with Solenoid data
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Summary

• We are developing two systems for Aerogel quality
  control
• Transmittance measurement
• 5 color LED PMT scanning in X-Y plane
• It can measure transmittance of 5 layers of tiles
  at once
• It can measure position dependence in Aerogel
• Resulting parameters ,A and CT in
• can well predict light yield
• Cherenkov light yield measurement
• Solenoid Magnet to produce monochromatic electron
• easy to measure light yield of aerogel
• consistent with the results obtained in the 60MeV
  e- beam test
• Other optical properties to check
• refractive indexetc