Theoretical response of a ZnS(Ag) scintillation detector to alpha-emitting sources and suggested applications

Journal Article · Fri Mar 01 00:00:00 EST 1991 · Health Physics; (USA)

DOI:https://doi.org/10.1097/00004032-199103000-00008· OSTI ID:5898902

Skrable, K W; Phoenix, K A; Chabot, G E; French, C S; Jo, M; Falo, G A ^[1]

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1. Univ. of Lowell, MA (USA)

The classic problem of alpha absorption is discussed in terms of the quantitative determination of the activity of weightless alpha sources and the specific alpha activity of extended sources accounting for absorption in the source medium and the window of a large area ZnS(Ag) scintillation detector. The relationship for the expected counting rate gamma of a monoenergetic source of active area A, specific alpha activity C, and thickness H that exceeds the effective mass density range Rs of the alpha particle in the source medium can be expressed by a quadratic equation in the window thickness x when this source is placed in direct contact with the window of the ZnS(Ag) detector. This expression also gives the expected counting rate of a finite detector of sensitive area A exposed to an infinite homogeneous source medium. Counting rates y obtained for a source separated from a ZnS(Ag) detector by different thicknesses x of window material can be used to estimate parameter values in the quadratic equation, y = a + bx + cx2. The experimental value determined for the coefficient b provides a direct estimation of the specific activity C. This coefficient, which depends on the ratio of the ranges in the source medium and detector window and not the ranges themselves, is essentially independent of the energy of the alpha particle. Although certain experimental precautions must be taken, this method for estimating the specific activity C is essentially an absolute method that does not require the use of standards, special calibrations, or complicated radiochemical procedures. Applications include the quantitative determination of Rn and progeny in air, water, and charcoal, and the measurement of the alpha activity in soil and on air filter samples.

• OSTI ID: 5898902
• Journal Information: Health Physics; (USA), Vol. 60:3, Issue 3; ISSN 0017-9078
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
ALPHA PARTICLES
SCINTILLATION COUNTING
RADIATION DETECTORS
EFFICIENCY
ABSORPTION
ALPHA SOURCES
EQUATIONS
CHARGED PARTICLES
COUNTING TECHNIQUES
ION SOURCES
MEASURING INSTRUMENTS
PARTICLE SOURCES
RADIATION SOURCES
440101* - Radiation Instrumentation- General Detectors or Monitors & Radiometric Instruments