Alpha counters for low background measurement

Moo Hyun Lee1st alpha meeting

2014.12.19

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Alpha counter types and status ZnS + Plastic Scintillator counter

Handheld alpha counter Eljen EJ-440 (12”x12” sheet) 2 each delivered.

Silicon sensor (KNU) A prototype was made and tested. 18.5% FWHM with Am-241 with an air gap

Ultralo-1800 (XIA) Ionization chamber with Argon gas and no window. Test material dimension: up to 1800 cm^2. Can separate signals from the chamber. ~80 k USD including training Ordered to have it shipping at the end of March 2015

Proportional wire chamber S/N is big Mylar window Background from the chamber can not be separated

Well type Ge detector CsI crystal detector (thin and wide)

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EJ-440 (ZnS) delivered

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12” x 12”

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ZnS detector design and readout example

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From an article in Progress in NUCLEAR SCIENCE and TECHNOLOGY, Vol. 1, p.194-197 (2011) (S.K.Lee et al.)

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EJ-440 and BC-400 sandwich case

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B.K. Seo et al., in Transactions of the Korean Nuclear Society Spring MeetingChuncheon, Korea, May 25-26 2006

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Backup slides

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Silicon sensor (KNU)

A silicon PIN diode sensor has been developed and tested at KNU.

Excellent experiences with the solid state detectors compared to the gas detector in general.

Enough experiences in KNU.

From DongHa Kah’s slide

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Silicon sensor test (KNU)

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XIA UltraLo-1800 counter Alpha Particle Counter

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Performance category Specification

Required counting time for measurement of ULA (0.001) sample1 (50%) 6 hrs, (25%) 24hrs, (12.5%) 90 hrs -- (measurement accuracy) time

Required counting time for measurement of LA (0.01) sample1 (50%) 30 min, (25%) 2.5 hrs, (12.5%) 9 hrs -- (measurement accuracy) time

Typical counter efficiency > 90% of 2π

Energy resolution (230Th source) < 6% FWHM (at 4.6 MeV) < 6% FWHM (at 4.6 MeV)

Energy sensitivity range 1-10 MeV

Sample sizes (typical min - max) 300mm wafer (707cm2) - 1800cm2

UltraLo-1800 Specification

1 – Sample assumed to be 300mm wafer (count times drop by factor of 2.5 when using max sample area)

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UltraLo-1800 Schematic Overview

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Proportional Counter Overview

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UltraLo-1800 for different alphas locations

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Requirements Specification

Minimum sample size (typical) 300mm wafer (707cm2)

Maximum sample size 1800cm2

Maximum sample weight 20 lbs (9 kg)

Maximum sample thickness 0.25 in (6.3 mm)

Counting Gas Argon

Gas pressure 21psi (150kPa) ±5%

Line Voltage 100-240 (VAC) 50/60 Hz

Power Consumption (Instrument) 50 W (100 W maximum)

Power Consumption (Laptop) 30 W

System dimensions (L x W x H) 65 in x 35 in x 27 in (165 cm x 89 cm x 69 cm)

Weight 360 lb (163 kg)

UltraLo-1800 requirements