No abstract available

[en] Solid state nuclear track detectors (SSNRDs) are frequently used as integrating detectors for alpha particles, e.g. in Radon dosimetry, Uranium prospection, and in nuclear and solid state physics. Further, alpha particles from radioactive sources or accelerators are especially suitable for fundamental investigations on nuclear track detection characteristics of polymer materials. In view of this widespread interest, the Organizing Committee of the 9th International Conference in Solid State Nuclear Track Detectors (9th ICNTD) taking place from Sept. 30 to Oct. 6, 1976, at the Gesellschaft fuer Strahlen- und Umweltforschung (GSF), Neuherberg, asked the GSF-Institut fuer Strahlenschutz to organize under the sponsorship of the 9th ICNTD for its participants an International Alpha Particle Registration Intercomparison with Solid State Nuclear Track Detectors (ALRIT). In this report the full results of all ALRIT-participants are reproduced, who returned their data before the conference. A discussion of these results and more details of the actual irradiation conditions are presented in the proceedings of the 9th ICNTD (to be published). (orig./ORU)

[en] A concise mathematical model is presented for the microdosimetric ionization distributions produced in subcellular volumes by energetic protons of 0.3 to 20 MeV. The model is based on the results of extensive Monte Carlo computer simulations of high-LET charged particle tracks and can be used to estimate, with only a modest computing effort, straggling and delta-ray transport effects in the nanometer dosimetry of high-LET radiations

No abstract available

[en] The results of the study show that the current radiation exposure of trees or parts of trees (e.g. leaves, needles, roots) practically exclusively is due to the ionizing radiation of natural sources. The dose contributed by radioactive, airborne emissions from nuclear power stations is relatively small, even in the vicinity of the stations. Uptake of radioactive noble gases by plants administers only a very small dose to leaves or needles. The dose rate received by green leaf or needle trees is not very different. However, due to the different lifetime of the trees, the cumulative dose to needle trees is expected to be higher by a factor of 10 on the average. In areas of normal natural soil or airborne activity, an average cumulative energy dose of 1 or 10 mGy, to leaves or needles respectively, as a result of natural radiation is expected. (orig./PW)

[en] The initial spatial pattern of energy deposition by ionizing radiation plays a significant role in the subsequent evolution of biologically active chemical species. The study of track structure includes both theoretical and experimental investigation of the spatial pattern of energy deposition. The modeling of stochastic processes in the transfer of energy in macromolecular systems focused on understanding anisotropic radical yields observed in neutron irradiation of oriented deoxyribonucleic acid (DNA) fibers. Extensive computer simulations of proton tracks have been made for protons of energy E, passing through spherical sites of diameter d, off center by a distance b, which we call eccentricity. Computed ionization distributions for 0.3 < E < 20 MeV, 2 < d < 1000 rm, and 0 < b > d/2 were obtained. The log normal function, f(j) = EXP(- (ln(j)-μ)² / 2 σ²) / σ j (2π) is used to represent these distributions phenomenologically. A concise computer code system written in FORTRAN is under development to evaluate the model of the stochastics of ionization. For high-velocity charged particles and sufficiently small sites it is quite possible for the particle to pass through the site without depositing any energy or without ionization. This situation indicates a breakdown in the proportionality between fluence and dose, and it is therefore desirable to know how frequently this happens and, ideally, to be able to quantify the frequency. From the computer simulations it was discovered that in sites smaller than 1000 nm in diameter, the frequency for zero ionization is simply related to the cross sections for ionization, f(j-O) = EXP [-d(1-b²)^1/2/λ_j(E)_p] where j is the ionization number and λ_j is the mean free path for the interaction

[en] Age-dependent dose factors are given for inhaled or ingested cesium isotopes, which have been calculated on the basis of published data on the biokinetics of cesium in the human organism. Tabulated data are presented for Cs-129, Cs-130, Cs-131, Cs-132, Cs-134, Cs-135, Cs-136, Cs-137(+Ba-137m), and Cs-138. Comparison of results obtained for adults with relevant data published by the ICRP (1978), the NCRP (1977), and Schwarz (1982) shows very good agreement. More significant deviations are however found when comparing the results with data given in the Federal German Radiation Protection Ordinance, both with regard to adults and to infants, particularly refering to the lung data and to those for the gastro-intestinal tract and the skeleton. These discrepancies are primarily due to improved models developed since the time the Radiation Protection Ordinance has been issued, (respiratory and gastro-intestinal tracts), and to improvements achieved with the dosimetric concepts (calculation of dose for bone surfaces instead of the whole skeleton). The dose factors for newborn given by the publication in hand are significantly lower than those given in the Ordinance (for infants); this is a result of age-dependent retention functions having been considered for this publication. The reliability of the dose factor calculations for various ages, pregnant women and fetuses is discussed and quantified. (orig./HP)

No abstract available

[en] Short communication

[en] Protons that pass outside the site but which deposit energy via secondary electrons, so-called touchers, are significant events for very small sites inasmuch as nearly 50% of the stopping power is borne by delta-rays. Toucher-event modeling has focused on trying to discover the systematics of the ionization distributions. The probability for a nanometer site experiencing any ionization deposition was proportional to the solid angle of the site as seen from the ion path, and to the total ionization cross section, i.e., proportional to the number of delta-rays produced per unit path length. The data was scaled by the real trigonometric solid angle for near distances, various effective eccentricities were tried, and partial cross sections were used that realistically reflected the production of only those delta-rays capable of reaching the site. Some of the variations were helpful over small regions of the parameters, ion energy for example. But none, alone or collectively, produced universal simplicity or insight into the problem. The set of computed ionization distributions was inadequate for the task