Validation of a Gross Alpha – Beta
Counter for Homogeneity Tests
Katie Freeman
26th September 2012
Contents
 Introduction to Validation (1)
 Instrumentation (2)
 Calibration Procedure (6)






Source Preparation
Detector Plateau Measurements
Background
Effectiveness of the Guard Detector
Efficiency
Discriminator Settings
 Quality Control and Assurance (2)
 Linearity
 Reproducibility
 Conclusions and Future Work (1)
Introduction to Validation
 Calibration
 Quality
 UKAS Accreditation
 Standards - ISO/IEC 17025:2005: General requirements for the
competence of testing and calibration laboratories
Instrumentation – LB-790
HV
alpha/beta radiation
http://en.wikipedia.org/wiki/File:
DmwdxrfFlowDetector.jpg
Instrumentation
Calibration - Source Preparation
Calibration - Detector Plateau Measurement
5000
Detector 1: Alpha Plateau Measurement
4500
4000
Counts (cpm)
3500
3000
2500
2000
1500
1000
500
0
750 V
950 V
1150 V
1350 V
Voltage (V)
1550 V
1750 V
Calibration - Detector Plateau Measurement
Detector 1: Beta Plateau Measurement
70000
60000
Counts (cpm)
50000
40000
30000
20000
10000
0
750 V
950 V
1150 V
1350 V
Voltage (V)
1550 V
1750 V
Calibration - Discriminator Settings
http://nuclearpowertraining.tpub.c
om/h1013v2/css/h1013v2_83.htm
Calibration - Verification of Counter Background
Detector 1: Background Counts of Empty Planchets
1.4
1.2
Counts (cpm)
1.0
0.8
Beta
0.6
Alpha
0.4
0.2
0.0
0
500
1000
1500
2000
2500
-0.2
Time (minutes)
3000
3500
4000
Calibration - Effectiveness of Guard Detector
Cosmic Background Radiation
Calibration - Efficiency

241Am

90Sr
= 20%
= >90%
Calibration - Efficiency

241Am

90Sr
= >90%

90Sr
= 45%
= 20%
http://www.nucleide.org/DDEP_
WG/Nuclides/Sr90_tables.pdf
Quality Control and Assurance - Linearity
Comparison of Linearity using Alpha Disk - X91001
13500
13000
12500
Counts (cpm)
12000
Alpha Lipped
11500
Beta Lipped
Alpha Non-Lipped
11000
Beta Non-Lipped
10500
10000
9500
9000
0
2
4
Detector #
6
8
10
Quality Control and Assurance - Reproducibility
Detector 1: Shewart Chart (Alpha)
3700
3650
Counts (cpm)
UALp
UWLp
3600
UILp
Data
3550
Mean
LILp
LWLp
3500
LALp
3450
03/09/12 05/09/12 07/09/12 09/09/12 11/09/12 13/09/12 15/09/12 17/09/12 19/09/12 21/09/12 23/09/12
Date
Quality Control and Assurance - Reproducibility
Detector 1: Shewart Chart (Alpha)
3700
3680
Counts (cpm)
3660
UALp
UWLp
3640
UILp
Data
3620
Mean
LILp
3600
LWLp
LALp
3580
3560
03/09/12 05/09/12 07/09/12 09/09/12 11/09/12 13/09/12 15/09/12 17/09/12 19/09/12 21/09/12 23/09/12
Date
Quality Control and Assurance - Reproducibility
Detector 1: Shewart Chart (Beta)
58000
57500
UALp
Counts (cpm)
57000
UWLp
UILp
56500
Data
Mean
56000
LILp
LWLp
LALp
55500
55000
04/09/12 06/09/12 08/09/12 10/09/12 12/09/12 14/09/12 16/09/12 18/09/12 20/09/12 22/09/12
Date
Future Work
 Limits of detectability
 Background produced by empty planchets
 Backgrounds produced by blank samples
 Homogeneity tests
 Ground samples
 Chipped samples
Acknowledgements
I would like to thank
 Maria Garcia-Miranda, Selina Woods and all the RMG staff at NPL
 Viridian Partnership for running the EMpower scheme and providing funding,
direction and advice throughout the project
 Professor Paul Nolan for his on-going support in both my undergraduate and
MSc studies
Title of Presentation
Name of Speaker
DateThe National Measurement System delivers world-class
measurement science & technology through these organisations
The National Measurement System is the UK’s national infrastructure of measurement
Laboratories, which deliver world-class measurement science and technology through four
National Measurement Institutes (NMIs): LGC, NPL the National Physical Laboratory, TUV NEL
The former National Engineering Laboratory, and the National Measurement Office (NMO).