[en] Because of the difficulties of calibration in fission track (FT) dating over the last 20 yr, including uncertainty of the absolute λ_f value, complexities of neutron dosimetry, complexities of neutron irradiation, correction factors necessary in some methodological procedures, and personal factors in track counting, the Working Group elected at the Cambridge ICOG meeting in 1986 recommended to FT workers meeting at the 6th International Fission Track Dating Workshop in Besancon on 9 September 1988, a uniform approach to system calibration, sample irradiation, calculation of FT age, and presentation of data. After discussion and modification, the recommendation was accepted. This modified recommendation is presented. (author)

[en] The potential of the nuclear track detector CR-39 as a means of characterizing very low current beams of accelerator protons, deuterons and alpha particles in the energy region of 6 MeV/amu is examined. The beam radial specific density and its energy distribution are determined via semiautomatic video analysis of the recorded tracks for a Radial Ridge Cyclotron intermittent operation. Results show CR-39 to be capable of spectrometric measurements with variable resolution for the particles tested, and as a viable and useful medium for spatial isodose distribution applications at very low beam currents in biological irradiations. Scanning electron microscope analysis of the tracks and reaction rate calculations suggest Rutherford scattering as a likely cause of deviations in the energy discrimination ability for alpha particles. (author)

[en] CR-39 track detectors have been used to measure the mean ranges and energy-loss of 17.7 MeV amu^-186Kr in aluminium and 16.34 MeV amu^-1238U in Hostaphan. The nuclear track technique employed in this work is briefly described. The accuracy of measurement has been evaluated. Experimental range data are compared with theoretical values obtained from four different sources. The significance and scope of the work is discussed. (author)

[en] Annealing effects on the sensitivity of gamma-induced thermoluminescence (TL) and on alpha-recoil track (α-RT) density in lepidolite mica have been investigated. A remarkable decrease in TL sensitivity for the glow-curve region of 320-400⁰C was found, after 400⁰C annealing. The correspondence of a decrease in TL sensitivity with a decrease in α-RT density implies that α-RTs may be playing an important role as electron traps in lepidolite. (author)

[en] The basic detection characteristics of the polycarbonate Makrofol track detector are presented. The possibilities of using these detectors for recording and identifying nuclear reaction products are discussed. (author)

[en] A passive time-integrating dosimeter for radon monitoring in the environment was developed. The dosimeter is basically a diffusion chamber equipped with a solid state nuclear track detector. It is a plastic cup 96 mm diameter x 140 mm, closed by a membrane made of filter paper. The membrane stops airborne particles, slows down diffusion of thoron and allows easy diffusion of radon into the chamber. The dosimeter is wrapped in an aluminium foil to protect the track detector from the light. Inside the chamber, the track detector is fixed to a support made of cork. The collection of moisture on the detector surface is reduced in this way, due to improved thermal insulation of the detector from the cup walls. MA-ND/α(CR-39) was selected as the most suitable detector due to its high detection efficiency, lowest background and good stability in outdoor conditions. (author)

[en] The relative biological effectiveness (RBE) and quality factor (Q) at extreme values of linear energy transfer (LET) have been determined on the basis of experiments with single-cell systems and specific tissue responses. In typical single-cell systems, each heavy particle (Ar or Fe) passes through a single cell or no cell. In experiments on animal tissues, however, each heavy particle passes through several cells, and the LET can exceed 200 keV μm^-1 in every cell. In most laboratory animal tissue systems, however, only a small portion of the hit cells are capable of expressing the end-point being measured, such as cell killing, mutation or carcinogenesis. The following question was therefore addressed: do RBEs and Q factors derived from single-cell experiments properly account for the damage at high LET when multiple cells are hit by HZE tracks? A review is offered in which measured radiation effects and known tissue properties are combined to estimate on the one hand, the number of cells at risk, p₃n, per track, where n is the number of cells per track based on tissue and organ geometry, and p₃ is the probability that a cell in the track is capable of expressing the experimental end-point. On the other hand, the tissue and single-cell responses are compared by determining the ratio RBE in tissue/RBE in corresponding single cells. Experimental data from the literature indicate that tissue RBEs at very high LET (Fe and Ar ions) are higher than corresponding single-cell RBEs, especially in tissues in which p₃n is high. (author)

[en] This paper presents unambiguous measurements of the spectrum of neutrons found in spacecraft during spaceflight. The neutron spectrum was measured from thermal energies to about 10 MeV using a completely passive system of metal foils as neutron detectors. These foils were exposed to the neutron flux bare, covered by thermal neutron absorbers (Gd) and inside moderators (Bonner spheres). This set of detectors was flown on three U.S. Space Shuttle flights, STS-28, STS-36 and STS-31, during the solar maximum. We show that the measurements of the radioactivity of these foils lead to a differential neutron energy spectrum in all three flights that can be represented by a power law, J(E)≅E^-0.765 neutrons cm^-2 day ^-1 MeV^-1. We also show that the measurements are even better represented by a linear combination of the terrestrial neutron albedo and a spectrum of neutrons locally produced in a aluminium by protons, computed by a previous author. We use both approximations to the neutron spectrum to produce a worst case and most probable case for the neutron spectra and the resulting dose-equivalents, computed using ICRP-51 neutron fluence-dose conversion tables. We compare these to the skin dose-equivalents due to charged particles during the same flights. (author)

[en] A new method is presented for the determination of the neutron fluence in fission track dating, by determining the product of the neutron fluence multiplied by the effective fission cross section of ²³⁵U with the fission product method. The calibration constant b (b ρ_i/σ·φ) of UG-5 standard uranium glass is obtained and has a mean value of (1.23±0.06) x 10¹¹. The fluence of neutrons reacting with ²³⁵U is derived directly and the influences of the neutron spectrum and neutron temperature are eliminated. (author)

[en] Apatite from granite samples out of the Little Cottonwood stock of north-central Utah range in age from about 7 Ma at 1500 m elevation to about 11 Ma at 3500 m elevation and give an uplift rate of 0.68 mm yr^-1 during this time period. Zircons from some of the same samples range in age from about 9 Ma at 1500 m elevation to 20 Ma at 3500 m, and probably represent an uplifted partial annealing zone. The uplift is associated with movement along the Wasatch fault which borders the stock on its western margin. The calculated uplift rates from the apatite ages in this study agree well with rates found by other workers along the central segments of the Wasatch fault using a variety of methods. (author)