Microdosimetric Properties of Alpha-Particle Tracks Measured in a Low-Pressure Cloud Chamber

Fundamentals of Microdosimetry

“…Nuclear emulsions have been employed for studies of track struc- ture [14,15], but they do not have sufficient resolution to represent individual ionizations. Somewhat better resolution has been obtained with the more sensitive cloud chamber, which permits a fairly accurate visualization of the tracks, at least of sparsely ionizing particles [16]. However, the only common and practicable method for obtaining geometric representations of charged particle tracks is Monte Carlo simulation on the basis of known and interpolated collision cross sections.…”

On the possibility of obtaining non-diffused proximity functions from cloud-chamber data: I. Fourier deconvolution

“…To a large extent the cloud chamber is an ideal microdosimetric device: by measuring the positions of ionising events in charged-particle tracks one can generate-with a flexibility matched only by Monte Carlo simulations-any microdosimetric quantity of interest, ranging from lineal energy spectra (in volumes of practically arbitrary shape and size) to proximity functions, that is, distributions of distances between energy transfer points in the track. Cloud-chamber data analysed in such ways have been indeed reported for a variety of radiations (Budd and Marshall 1983, Marshall er a1 1985, Budd et a1 1983, Budd and Marshall 1980).…”

“…Recent publications from the Harwell grolup (Budd and Marshall 1983, Marshall et a1 1985, Budd et a1 1983, Budd and Marshall 1980) report one-dimensional root mean square diffusion distances of 4 nm and 3.5 nm in water vapour and tissueequivalent gas mixture, respectively. The spatial resolution in the proximity functions (or'interdroplet distance distributions, as they are called in these papers) is 0.5 nm in unit density (1 g water.…”

Calculation of boron neutron capture cell inactivation in vitro based on particle track structure and x-ray sensitivity

“…Single track effects were calculated separately for the alpha-particles and 7 Li-ions. Experimental measurements [30,31] as well as numerical [18,32,33] and Monte-Carlo calculations [34,35] suggest a 1/r 2 -dependence for the radial dose distribution D (r) inside the particle track. The track structure model of Butts and Katz [18] has been developed as a parametric description to fit experimental data measured at different energies.…”