UCRL-PRES 222063

Alpha Beta Counting Instrumentation Radoslav Radev Lawrence Livermore National Laboratory

AAHP Special Session on Radiation Measuring Instrumentation for HPs 51st Annual Health Physics Society Meeting Providence, RI, June 26-29, 2006 1 This work was performed under the auspices of the U.S. Department of Energy by University of California, Lawrence Livermore National Laboratory under Contract W-7405-Eng-48

Alpha Beta Counting Instrumentation Overview z

Summary of existing alpha- beta counters z z z

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Types and uses Detection technologies Discrimination of Rn/Th contribution

Useful features Future possibilities

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Alpha Beta Counting Instrumentation Introduction z

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A-B counting instruments are used to measure alpha and/or total beta activity Do not allow radionuclide identification – gross counters Very little signal analysis is done There is a group of newer devices that can do limited alpha spectroscopic analysis Variety of applications and modifications 3

Alpha Beta Counting Instrumentation Alpha-Beta Counters with single sample holder

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Alpha Beta Counting Instrumentation Low Level or/and Automated Alpha-Beta Counters

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Alpha Beta Counting Instrumentation Surface (Floor) Contamination Monitors

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Alpha Beta Counting Instrumentation Survey Meters

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Alpha Beta Counting Instrumentation Air Monitors

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Alpha Beta Counting Instrumentation Hand and Foot Monitors

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Alpha Beta Counting Instrumentation Detector Technologies z z z z z z

Gas sealed proportional Air proportional Gas flow proportional GM detectors Dual scintillators, phoswich, ZnS (Ag)+plastic Silicon detectors – surface barrier, PIPS

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Alpha Beta Counting Instrumentation Consider z z z z z z z z z

Low background Efficiency Spillover (cross-talk) Rn/Th discrimination capability Window/detector contamination Sample identification Uniformity of efficiency across detector Resolving time/dead time Durability and ruggedness 11

Alpha Beta Counting Instrumentation Useful Features to Consider z z z z z z

Gas saving devices that reduce gas flow Windows that are easy to change Fast sample changer if doing many samples Sample bar-code system Ease of decontamination Flexibility in displayed results – count rate, total counts/activity, specific activity, etc.

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Instrument life time – embedded PC, electronics Training requirements 12

Alpha Beta Counting Instrumentation Microprocessor (PC) Enhanced Data Processing z z

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Counting time determined by confidence level Minimum Detectable Activity (MDA) based on confidence level Probability of detection and false detection Signal processing - smoothing, selectable averaging times Flexibility in displayed results – rate, integral, peak, units Exportability of peak data for further analysis 13

Alpha Beta Counting Instrumentation Radon/Thoron Rejection Algorithms z z z z z

Use of alpha spectroscopic information Improved modeling for alpha spectrum peaks Algorithms for mapping/fitting peaks Tracking Rn/Th daughters/granddaughters Rn/Th rejection algorithms need to be well understood and documented (not a “black box”) in order to be defensible to regulators

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Alpha Beta Counting Instrumentation Calibration and QA z

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Build-in routines: plateau plot, HV scan, S and S2/b plots for probe characterization Computer controlled HV, threshold settings and gain Automatic background compensation Logging – peak, set up parameters Auto calibration and source check routines Calibration with sources, MDA test with sources, computer calculated efficiency QA- self test when invalid or fault conditions sensed 15

Alpha Beta Counting Instrumentation Other Useful Enhancements z z z z z z z z

Large color display- text+graphics, instructions, status, data Wireless data transmission, variable outputs Ease of use, user friendly Useful manuals + good tech support Interchangeable detectors, windows Size (smaller), power (battery) Easy maintenance Cost 16

Alpha Beta Counting Instrumentation Conclusion z

What can we expect from the future alpha beta counters z z z z z z

Basic detection principles won’t change dramatically Increased signal and spectroscopic analysis Increased use of microprocessors and computers Increased set up, calibration, QA and data analysis functions taken by microprocessor/PC Reduction in size with more “whistles and bells” Expected increase of unit cost 17