Oa. Bondarenko et al., ALPHA-PARTICLE SPECTROSCOPY WITH TASTRAK (CR-39 TYPE) PLASTIC, AND ITS APPLICATION TO THE MEASUREMENT OF HOT PARTICLES, Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment, 369(2-3), 1996, pp. 582-587
Two applications of TASTRAK plastic to measurement of alpha activity a
re described. (1) Alpha particle spectroscopy is possible by automated
analysis of etched alpha particle tracks in TASTRAK (CR-39) type plas
tic. The method is based on the measurement of two geometric parameter
s of etched tracks, the minor axis, and the diameter of the etched out
track end. Accurate measurement of these two parameters allows reliab
le separation of tracks according to alpha particle energy, with a FWH
M of 80-110 keV (1.33-2%) over an energy band of 1.1 MeV. Within this
band the intrinsic measurement efficiency is as high as 0.75, a critic
al factor for possible low level measurement applications. The results
indicate that a basis exists for a robust working method for alpha pa
rticle spectroscopy in TASTRAK plastic. (2) A method is being develope
d for simultaneous measurement of size and activity of alpha emitting
hot particles. A hot particle is defined here as a volume of alpha act
ive material, which may be attached to an inert particle. Hot alpha em
itting particles produce characteristic radial clusters of tracks in e
tched TASTRAK. Automated image analysis of each track yields the follo
wing values: track co-ordinate, azimuth angle, dip angle, and track ra
nge. With these values, track paths can be projected above the plastic
surface. A multi-step procedure is described which calculates three p
arameters for a hot particle: the alpha activity, the physical size an
d distance of the particle above the plastic. The method is demonstrat
ed as applied to anthropogenic hot particles in the Chernobyl region,
Ukraine, and to natural uranium hot particles in soil from Bristol, UK
.