[Nuclear cascade during the process of heavy atmospheric shower of cosmic rays].
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Cosmic Radiation↗
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Cosmic ray diffusion from the galactic spiral arms, iron meteorites, and a possible climatic connection.
We construct a Galactic cosmic ray (CR) diffusion model. The CR flux reaching the Solar System should periodically increase each crossing of a Galactic spiral arm. We confirm this prediction in the CR exposure age record of iron meteorites. We find that although the geological evidence for the occurrence of iceage epochs in the past eon is not unequivocal, it appears to have a nontrivial correlation with the spiral arm crossings-agreeing in period and phase.
Journal Article↗
Predicting the response of a submillimeter bolometer to cosmic rays.
Bolometers designed to detect submillimeter radiation also respond to cosmic, gamma, and x rays. Because detectors cannot be fully shielded from such energy sources, it is necessary to understand the effect of a photon or cosmic-ray particle being absorbed. The resulting signal (known as a glitch) can then be removed from raw data. We present measurements using an Americium-241 gamma radiation source to irradiate a prototype bolometer for the High Frequency Instrument in the Planck Surveyor satellite. Our measurements showed no variation in response depending on where the radiation was absorbed, demonstrating that the bolometer absorber and thermistor thermalize quickly. The bolometer has previously been fully characterized both electrically and optically. We find that using optically measured time constants underestimates the time taken for the detector to recover from a radiation absorption event. However, a full thermal model for the bolometer, with parameters taken from electrical and optical measurements, provides accurate time constants. Slight deviations from the model were seen at high energies; these can be accounted for by use of an extended model.
Journal Article↗
Preliminary results of the Biobloc experiment on the Cosmos 782 flight: effects of cosmic rays on brine shrimp eggs and tobacco seeds.
The aim of the Biobloc experiment is to determine the biological effects of cosmic rays. Biobloc is a stack made up of biological layers and physical detectors (nuclear emulsions and plastic). Artemia eggs and tobacco seeds are used by French workers. Irradiation by cosmic heavy ions induces a late developmental inhibition of Artemia eggs. A light increase of emergence rate is observed for the non-hit eggs. The results are compared with those of previous space experiments. Investigations on tobacco seeds are in progress.
Animals↗
Re-analysis of the cosmic ray ground level enhancement of 4 May 1960.
The relativistic solar particle event of 4 May 1960, resulting in a cosmic ray ground level enhancement, occurred well before modern analysis techniques were available. We have located surviving data from 23 neutron monitors and have used these to estimate the spectrum, mean arrival direction and particle pitch angle distribution as the event progressed. We find that the apparent particle arrival direction was at equatorial latitudes, over northern South America, in contrast to contemporary analyses that proposed it to be over North America. Our modified power law spectra are broadly consistent with earlier results. Data from stations above sea level need to be corrected for altitude using a two-attenuation length technique. The standard method involves comparison of data from two relatively close stations at significantly different altitude. We have shown that this method may be unreliable in cases, such as this, of quite sharp anisotropy.
Anisotropy↗
Secondary protons and neutrons generated by galactic and solar cosmic ray particles behind the 1-100 g/cm2 aluminum shielding.
Proton and neutron energy spectra behind Al shielding affected by galactic and solar cosmic ray particles are Monte-Carlo calculated using the multipurpose hadron transport code (SHIELD).
Aluminum↗
[The sun as a source of x-rays; cosmic politics].
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Composite Resins↗
Ground-based simulations of galactic cosmic ray fragmentation and transport.
Since mean free paths for nuclear fragmentation are of the order of the ranges of primary Galactic Cosmic Ray (GCR) nuclei, determination of the radiation field produced by successive fragmentations of nuclei in material and tissue is essential to accurate assessment of GCR radiation risk to humans on long-duration missions outside the geomagnetosphere. We describe some recent measurements made at the Bevalac of heavy ion transport through materials, with representative results and examples of how they may be applied to aspects of the space radiation problem, including efforts to devise analytical tools for predicting biological effects and for designing spacecraft shielding.
Computer Simulation↗
Measurements of cosmic-ray low-energy antiproton and proton spectra in a transient period of solar field reversal.
The energy spectra of cosmic-ray low-energy antiprotons ( *p's) and protons ( p's) have been measured by BESS in 1999 and 2000, during a period covering reversal at the solar magnetic field. Based on these measurements, a sudden increase of the *p/p flux ratio following the solar magnetic field reversal was observed, and it generally agrees with a drift model of the solar modulation.
Journal Article↗
Observation by an air-shower array in Tibet of the multi-TeV cosmic-ray anisotropy due to terrestrial orbital motion around the Sun.
We report on the solar diurnal variation of the galactic cosmic-ray intensity observed by the Tibet III air shower array during the period from 1999 to 2003. In the higher-energy event samples (12 and 6.2 TeV), the variations are fairly consistent with the Compton-Getting anisotropy due to the terrestrial orbital motion around the Sun, while the variation in the lower-energy event sample (4.0 TeV) is inconsistent with this anisotropy. This suggests an additional anisotropy superposed at the multi-TeV energies, e.g., the solar modulation effect. This is the highest-precision measurement of the Compton-Getting anisotropy ever made.
Journal Article↗
Galactic cosmic ray origin of Li, Be and B in stars.
A study of the implications of the hypothesis that high energy processes involving cosmic rays acting on the interstellar medium are the sources of the elements Li, Be and B present in stellar atmospheres and in the solar system.
Journal Article↗
Ultra-High-Energy Cosmic-Ray Acceleration by Magnetic Reconnection in Newborn Accretion-induced Collapse Pulsars.
We here investigate the possibility that the ultra-high-energy cosmic-ray (UHECR) events observed above the Greisen-Zatsepin-Kuzmin (GZK) limit are mostly protons accelerated in reconnection sites just above the magnetosphere of newborn millisecond pulsars that are originated by accretion-induced collapse (AIC). We formulate the requirements for the acceleration mechanism and show that AIC pulsars with surface magnetic fields 1012 G /=10(20) eV. Because the expected rate of AIC sources in our Galaxy is very small ( approximately 10(-5) yr(-1)), the corresponding contribution to the flux of UHECRs is negligible and the total flux is given by the integrated contribution from AIC sources produced by the distribution of galaxies located within the distance that is unaffected by the GZK cutoff ( approximately 50 Mpc). We find that reconnection should convert a fraction xi greater, similar0.1 of magnetic energy into UHECRs in order to reproduce the observed flux.
Journal Article↗
[Biological effect of cosmic rays induced in embryo tissues of Arabidopsis seeds exposed in Cosmos-2044 (Bion-9)].
This paper presents the results of evaluation of the biological effect induced by cosmic rays in embryo tissues of Arabidopsis thaliana seeds exposed in Biocosmos-9 (BION-9). The experiment was carried out in cooperation with the Botanical Institute and the Institute of nuclear Physics of J.W. Goethe University, Frankfurt-am-Main, Germany using the Biostack system. The data ere obtained in Moscow 4 months and 3 years after the flight. It was shown that in Arabidopsis seeds exposed outside BION-9 the effect evaluated by all the biological criteria used was higher than in seeds exposed inside BION-9. In some characters the effect in the latter did not differ from that in control seeds but in others (black spots, tumors, mutations) it was higher. In tetraploid line the per cent of plants with tumors was higher than in diploid line. The differences observed can be explained by the fact that the total dose of irradiation and the flow of heavy ions were significantly higher outside than inside BION-9. The data obtained cooperatively with German colleagues showed that the seeds hit by heavy ion could not practically develop in the normal way. It was noted that after prolonged storage of seeds after the flight the biological effect in control seeds and in seeds exposed inside BION-9 did not change, and increased in seeds exposed outside BION-9.
Cosmic Radiation↗
Cosmic-ray ionization in the lower atmosphere.
A high-pressure ion chamber filled with 2.5825 X 10(5) kg m-2 argon as used to measure the dose rates of several sites of interest in an attempt to evaluate the dose rates contributed by cosmic rays. Observation sites included two water reservoirs deeper than 110 m, Mount Ali which is higher than 2500 m, airliners flying at altitudes higher than 6700 m, and some sites at sea level. The results of this investigation were compared with those reported by the United Nations Scientific Committee on the Effects of Atomic Radiation and used for the determination of background radiation monitored with thermoluminescent dosimeters and sodium iodide detectors.
Calibration↗
The impact of ICRP publication 92 on the conversion coefficients in use for cosmic ray dosimetry.
ICRP Publication 92 presents a proposal to achieve coherence between radiation weighting factors and quality factors. In particular, the radiation weighting factors for incident protons and neutrons have been revised and new values have been proposed. On the basis of the proposed values, sets of conversion coefficients fluence-to-effective dose for protons and neutrons have been derived for the irradiation geometries of interest for cosmic ray dosimetry.
Body Burden↗
Study of cosmic ray effects on Artemia salina eggs during the Apollo 16 and 17 flights.
We have used Artemia salina eggs, embedded in polyvinyl alcohol, to study the biological effects of heavy ions of cosmic rays. Each biological layer was sandwiched between track detectors. Hit eggs by heavy ions show a great inhibition of their developmental ability. A lower inhibition is observed for eggs that were flown but not hit. Simulation experiments are in progress to determine the factors responsible for inhibition of eggs that were not hit and to improve our knowledge of cellular damage induced by heavy ions.
Animals↗
Absorbed dose of secondary neutrons from galactic cosmic rays inside the International Space Station.
In this paper, we present the results of Monte-Carlo simulations of the flux and energy spectra of neutrons generated as a result of galactic cosmic ray proton interactions with the material of International Space Station (ISS) inside Zvezda Service Module, the Airlock between Russian and USA segments and one of Russian Research Modules for a full configuration of ISS. Calculations were made for ISS orbit for the energy ranges <10 and >10 MeV for both maximum and minimum of solar activity. To test the accuracy of the calculations the same simulations were made for MIR orbital station and for CORONAS-I satellite and compared with the results of measurements. Calculated and measured fluxes are in reasonable agreement.
Cosmic Radiation↗
Determination of absolute neutrino masses from bursts of Z bosons in cosmic rays.
Ultrahigh energy neutrinos (UHEnu) scatter on relic neutrinos (Rnu) producing Z bosons, which can decay hadronically producing protons (Z burst). We compare the predicted proton spectrum with the observed ultrahigh energy cosmic ray (UHECR) spectrum and determine the mass of the heaviest Rnu via a maximum likelihood analysis. Our prediction depends on the origin of the powerlike part of the UHECR spectrum: m(nu) = 2.75(+1.28)(-0.97) eV for Galactic halo and 0.26(+0.20)(-0.14) eV for extragalactic origin. The necessary UHEnu flux should be detected in the near future.
Journal Article↗