Abstract
Gamma-ray quanta, which occur during solar flares due to the interaction of accelerated protons with the photosphere and deeper layers of the sun, enter interplanetary space from a thickness ...of several tens of g/cm
2
. In the presented work, gamma quanta with energies of more than 511 keV are considered. This makes it possible to exclude from consideration the dependence of the probability of ortho- and parapositronium formation on the temperature and density of the solar matter. And also do not consider the probability of annihilation by two or 3 gamma quanta. Thus, the reactions of thermal neutrons remain dependent on the temperature. As the ambient temperature increases, the average number of elastic neutron scattering before capture increases. This leads to a more likely penetration of neutrons to a greater depth or their departure into the interplanetary space. The high temperature of the Sun below the photosphere may be one of the reasons for the absence of the 2.223 MeV line in solar flares with registered protons in the PAMELA and AMS2 experiments. Using the GEANT4 package, the spectra of gamma-quanta arising in nuclear interactions are calculated. The temperature-dependent features of the gamma-ray spectra are discussed.
Detection of the organic matter on Mars is one of the main goals of the future Martian landing missions. Yet, the degradation of organic molecules by cosmic ray irradiation on Mars is often ignored. ...We calculate the radiation dose accumulation rates from solar and galactic cosmic rays at various depths in the shallow Martian subsurface. We demonstrate that a 1‐billion‐year outcrop on Mars accumulates the dosage of ∼500 MGy in the top 0–2 cm and ∼50 MGy at 5–10 cm depths. We show that the preservation of ancient complex organic molecules in the shallow (∼10 cm depth) subsurface of rocks could be highly problematic if the exposure age of a geologic outcrop would exceed 300 Myr. We demonstrate that more simple organic molecules with masses ∼100 amu should have a good chance to survive in the shallow subsurface of rocks. Implications to the sampling strategy for the oncoming Martian missions are discussed.
Key Points
Cosmic rays is a key factor for the degradation of organic molecules on Mars
Solar CR are critically important for degradation in the top 2 cm of rocks
Only 100 amu organic compounds have a good chance to survive cosmic ray exposure
We suggest an explanation of a sharp increase in the abundance of cosmogenic radiocarbon found in tree rings dated AD 775. The increase could originate from high-energy irradiation of the atmosphere ...by a Galactic gamma-ray burst. We argue that, unlike a cosmic ray event, a gamma-ray burst does not necessarily result in a substantial increase in long-lived 10Be atmospheric production. At the same time, the 36Cl nuclide would be generated in the amounts detectable in the corresponding ice-core samples from Greenland and Antarctica. These peculiar features allow experimental discrimination of nuclide effects caused by gamma-ray bursts and by powerful proton events.
Beryllium Isotopes in the PAMELA Experiment Bogomolov, E A; Vasilyev, G I; Menn, W
Journal of physics. Conference series,
11/2021, Letnik:
2103, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Abstract
Analysis of the isotopic composition of nuclei in galactic cosmic rays (GCR) in the orbital experiment of the PAMELA collaboration makes it possible to study the problems of the origin and ...propagation of cosmic rays in the Galaxy. The data of the PAMELA magnetic spectrometer, due to their high statistical and methodological accuracy, ensured significant progress in the study of the isotopic composition of light nuclei from H to Be in GCR in the energy range ~ 0.1-1 GeV/nucleon and for the first time made it possible to estimate the contribution to GCR of Local Interstellar Sources (LIS) from close (∼ 100 pc) of recent (~ million years) supernova explosions. To date, the isotopic composition of beryllium nuclei in GCR has been measured only for
7
Be./
9
Be,
10
Be/
9
Be ratios in the energy range of ∼ 100 MeV/nucleon in the space experiments IMP 7/8, Voyager, Ulysses, ACE/CRIS and for
10
Be/
9
Be in balloon experiment with a superconducting magnet ISOMAX-98 for energies 0.2-1.0 and 1.1-2.0 GeV/nucleon. In this work, using flight data PAMELA 2006-2014, on the rigidity of the detected nuclei and their velocity (time-of-flight analysis and ionization losses in the multilayer calorimeter of the instrument), a new analysis of the isotopic composition of beryllium nuclei in the energy range of ~ 0.1-1.4 GeV/nucleon has been carried out. The results of isotopic analysis of beryllium nuclei in GCR (spectra
7
Be,
9
Be,
10
Be and
7
Be/
9
Be,
10
Be/
9
Be - ratio depending on the rigidity and energy of nuclei) in comparison with the existing measurement and calculation data will be presented.
Precise measurements of the time-dependent intensity of the low-energy (<50 GeV) galactic cosmic rays (GCRs) are fundamental to test and improve the models that describe their propagation inside the ...heliosphere. In particular, data spanning different solar activity periods, i.e., from minimum to maximum, are needed to achieve comprehensive understanding of such physical phenomena. The minimum phase between solar cycles 23 and 24 was peculiarly long, extending up to the beginning of 2010 and followed by the maximum phase, reached during early 2014. In this Letter, we present proton differential spectra measured from 2010 January to 2014 February by the PAMELA experiment. For the first time the GCR proton intensity was studied over a wide energy range (0.08-50 GeV) by a single apparatus from a minimum to a maximum period of solar activity. The large statistics allowed the time variation to be investigated on a nearly monthly basis. Data were compared and interpreted in the context of a state-of-the-art three-dimensional model describing the GCRs propagation through the heliosphere.
Carbon Isotopes in the PAMELA Experiment Bogomolov, E A; Vasilyev, G I; Menn, W
Journal of physics. Conference series,
12/2020, Letnik:
1697, Številka:
1
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
Abstract
An analysis of the isotopic composition of nuclei in galactic cosmic rays (GCR) in the orbital experiment of the PAMELA collaboration allows us to study the problems of the origin and ...propagation of cosmic rays in the Galaxy. Due to the high statistical and methodological accuracy, the data of the PAMELA magnetic spectrometer provided significant progress in studying the isotopic composition of light nuclei from H to Be in the GCR in the energy region of ∼ 0.1-1 GeV / nucleon and for the first time made it possible to estimate the contribution of local sources from close ones to the GCR (∼ 100 pc) of recent (∼ 10
6
yrs) supernova explosions. To date, the isotopic composition of carbon nuclei in the GCR has been measured only for the
13
C /
12
C ratio in the energy region ∼ 0.05-0.13 GeV / nucleon in the VOYAGER 1.2 space experiment and the upper limit for the
14
C /
12
C ratio was estimated in the ACE / CRIS experiment for energies 0.12-0.43 MeV / nucleon. In this work, using PAMELA flight data 2006-2014, on the rigidity of the detected nuclei and their speed (time-of-flight analysis and ionization losses in the multilayer calorimeter of the device), an attempt was made to determine the isotopic composition of carbon nuclei in the energy region of ∼ 0.1-1 GeV / nucleon. The half-life of
14
C nuclei is 5730 years and can be detected in the case of a supernova explosion in the last ∼ 5 10
4
years at a distance of ∼ 100 200 pc. The results of isotope analysis of carbon nuclei in GCR (spectra
12
C,
13
C,
14
C and
14
C /
12
C - ratio depending on the rigidity and energy of the nuclei) in comparison with the existing measurement data will be presented.
Boron Isotopes in the PAMELA Experiment Bogomolov, E A; Vasilyev, G I
Journal of physics. Conference series,
11/2019, Letnik:
1400, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Analysis of the isotopic composition of nuclei in galactic cosmic rays (GCR) in the PAMELA orbital international experiment allows us to study the problems of the origin and propagation of cosmic ...rays in the Galaxy. Due to the high statistical and methodical accuracy, the PAMELA magnetic spectrometer data provided significant progress in the study of the isotopic composition of the light nuclei from H to Be in the GCR in the energy region of ∼0.1-1 GeV/nucleon and, for the first time, made it possible to estimate the contribution in GCR from local (∼100 pc) recent (∼106 years) interstellar sources (LS) from supernova explosions. An isotopic analysis of boron (B) nuclei in the GCR has so far been carried out only in the energy region ∼0.08-0.17 GeV/nucleon in the space experiments Voyager, Ulysses, ACE. In this work using the PAMELA data 2006-2014 about the rigidities of the detected nuclei and their speed (time of flight analysis (TOF) and ionization losses in a multilayer calorimeter) for the first time was made an attempt to determine the 11B/10B ratio in the energy range of ∼0.1-1.0 GeV/nucleon. The new PAMELA data are consistent with existing measurements and those expected from modeling, but the statistical and methodological accuracy of measurements does not allow us to separate the contribution of local boron sources to GCR. The results of the isotope analysis of boron nuclei in the GCR (spectra 10B, 11B and 11B/10B ratio depending on the rigidity and energy of the nuclei) in comparison with the existing measurement data and calculations will be presented.
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