摘要:

The aim of the Biostack, namely, to contribute to a dosimetry of the HZE-particles as the highly structured component of the cosmic radiation, leads to a variety of physical and biological requirements in order to achieve that goal. The temporal, spatial and atomic characteristics of that radiation field rendered visual track detectors with the capability of individually recording and correlating single hit events as the most suitable physical detectors. One of the objects selected had been the spores ofBacillus sub tills, which were flown in the missions of Apollo 16, 17 and the Apollo-Soyuz Test Project (ASTP). A substantial biological improvement was the development of routine methods which allowed the investigation of various biological endpoints of one individual spore together with a more precise determination of its impact parameter with respect to the path of the heavy ion. Preliminary results of the ASTP experiment are presented which strongly support the findings of the previous Biostack experiments

ISSN:0033-7579    

DOI:10.1080/00337577708233136

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

For experimental investigations in the field of microdosimetry of heavy ions a high precision localization method for biological objects relative to the path of the penetrating ion is mandatory. New methods are described for corn seeds ofArabidopsis thalianaand spores ofBacillus subtilis.In the latter case the actual penetration point of the particle in the spore layer is determined by an individual microetching technique with an accuracy of about 0.2 μm. This is done after removing the spores from the hit area by “break-through” etching. With the help of reference spores the impact parameter is determined for correlating the biological effects with the physical event. Besides the aspect of water during the track development is described.

ISSN:0033-7579    

DOI:10.1080/00337577708233137

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

In considering the biological problems which experience has so fa shown to appear in longer space flights, and which must be considered as risk factors, the two main points are weightlessness and the threat posed by ionizing radiation. Naturally, there are other factors as well such as ozone intoxication, decrease in air pressure, ad temperature fluctuations.

ISSN:0033-7579    

DOI:10.1080/00337577708233138

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

High-LET particle hits in embryos ofZea mays(corn) seeds, flown as part of the ASTP-Biostack III, were determined via plastic nuclear track detectors. Based on etched particle-track measurements, 41 embryos were hit in seed layer 1 which contained 80 seeds, and 49 hits occurred in layer 2 which contained 79 seeds. The mean LET value and range of atomic numbers of recorded hits is, respectively, 210 ± 57 keV/μm and 9 ≲Z≲ 26. Detailed analysis of one particular seed showing marked growth anomalies revealed two hits in the central region of the embryo. These two hits had LET values in the region of 100–150 keV/μm, and Z ≳ 20.

ISSN:0033-7579    

DOI:10.1080/00337577708233139

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The calculation is based on a factorization of fragmentation cross-sections into a projectile-depending and a target-depending part, which was found at Bavalac for high energy C and O ions. With this the known cross-sections for the fragmentation of heavy ions in collision with protons can be extrapolated to heavier targets. Considering the fragmentation and the energy loss of heavy nuclei the energy spectra of individual elements are calculated for different depths of absorber. This energy spectra can easily be converted to LET (linear energy transfer) spectra. The changes of the isotopic composition with absorber depth and its influence on the shape of the LET-spectra are discussed. The calculated results are compared with experimental data.

ISSN:0033-7579    

DOI:10.1080/00337577708233140

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

In the Biostack I, II and III experiments flown on the Apollo 16 and 17 and ASTP missions, nuclear emulsion plates have been used for the first time for heavy-ion identification in connection with biological layers. After the calibration step using the heavy ions available at the Bevalac at Berkeley, the nuclear emulsion can give dosimetric results for the heavy ions hitting biological materials. These results have been sent for exploitation to the biological laboratories of Toulouse, Frankfurt and Marburg. We summarize all the dosimetric results in the field of heavy-ion tracks and nuclear stars induced by cosmic-ray particles. The last results from Biobloc (December, 1975) are presented.

ISSN:0033-7579    

DOI:10.1080/00337577708233141

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

There have been a large number of laboratory experiments on particle induced visual sensations which have resulted in a variety of visual phenomena that are similar in appearance to the so-called “light flashes” described by astronauts on Apollo missions 11 through 17 and Skylab 4. Unfortunately, no direct comparison of the laboratory and space observations have been made by observers who have experienced both. More than one physical mechanism has been shown to be involved in the laboratory phenomena and presumably in the space observations also. A number of models for particle induced visual phenomena are described and a quantitative estimate of their contribution to the space observations is attempted.

ISSN:0033-7579    

DOI:10.1080/00337577708233142

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor