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- Akrawy, Dashty T., et al.
(författare)
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New empirical formula for calculating (n, p) reaction cross-sections at 14.5 MeV neutrons
- 2020
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Ingår i: International Journal of Modern Physics E. - 0218-3013. ; 29:8
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Forskningsöversikt (refereegranskat)abstract
- An empirical formula to calculate the (n, p) reaction cross-sections for 14.5 MeV neutrons for 183 target nuclei in the range 44 ≤ A ≤ 212 is presented. Evaluated cross-section data from TENDL nuclear data library were used to test and benchmark the formula. In this new formula, the nonelastic cross-section term is replaced by the atomic number Z, while the asymmetry parameter-dependent exponential term has been retained. The calculated results are presented in comparison with the seven previously published formulae. We show that the new formula is significantly in better agreement with the measured values compared to previously published formulae.
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- Akrawy, Dashty T., et al.
(författare)
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α-decay half-lives new semi-empirical relationship including asymmetry, angular momentum and shell effects
- 2022
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Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474. ; 1021
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Tidskriftsartikel (refereegranskat)abstract
- We present a modified version of the semi-empirical formula SemFIS, which is based on the fission theory for predicting the alpha decay half-lives. The first version of SemFIS was found by D. N. Poenaru et al. and was at that time the best formula to predict the alpha-decay half-lives of superheavy nuclei among 18 different existing models. We compare a modified version of SemFIS against the old version and experimental data for four groups of alpha emitters: even-even; even-odd; odd-even, and odd-odd parent nuclei. Two sets of experimental values are used: set A, and set B. There are 356 nuclides in set A [137 e-e, 90 e-o, 66 o-e, and 63 o-o with Zmin, Zmax of (52,118); (52,112); (63,117), and (53,117), and Amin, Amax of (108,294); (107,281); (147,293), and (110,294), respectively]. Set B includes 420 α-emitters [144 e-e, 112 e-o, 84 o-e, and 80 o-o] with Zmin, Zmax of (52,118); (52,116); (53,117), and (53,117), and Amin, Amax of (106,294); (105,293);(111,293) and (110,294)]. Our study shows that the modified version of SemFIS gives better agreements with the experimental data than previously published versions.
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| 8. |
- Ambrozova, I., et al.
(författare)
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Measurement of target fragments produced by 160 MeV proton beam in aluminum and polyethylene with CR-39 plastic nuclear track detectors
- 2014
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Ingår i: Radiation Measurements. - : Elsevier BV. - 1350-4487. ; 64, s. 29-34
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Tidskriftsartikel (refereegranskat)abstract
- Production of target fragments from reactions of 160 MeV proton beams in aluminum and polyethylene was measured with CR-39 plastic nuclear track detectors (PNTD). Due to the detection limit of PNTD, primary protons cannot be detected; only low-energy short-range target fragments are registered. As a feasibility study, a so called "two step etching method" was employed to get the linear energy transfer (LET) spectra, absorbed dose, and dose equivalent. This method is discussed in this paper, together with the measured results. (C) 2014 Elsevier Ltd. All rights reserved.
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| 9. |
- Bertucci, Antonella, et al.
(författare)
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Shielding of relativistic protons
- 2007
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Ingår i: Radiation and Environmental Biophysics. - : Springer Science and Business Media LLC. - 1432-2099 .- 0301-634X. ; 46:2, s. 107-111
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Tidskriftsartikel (refereegranskat)abstract
- Protons are the most abundant element in the galactic cosmic radiation, and the energy spectrum peaks around 1 GeV. Shielding of relativistic protons is therefore a key problem in the radiation protection strategy of crewmembers involved in long-term missions in deep space. Hydrogen ions were accelerated up to 1 GeV at the NASA Space Radiation Laboratory, Brookhaven National Laboratory, New York. The proton beam was also shielded with thick ( about 20 g/cm(2)) blocks of lucite (PMMA) or aluminium ( Al). We found that the dose rate was increased 40-60% by the shielding and decreased as a function of the distance along the axis. Simulations using the General Purpose Particle and Heavy-Ion Transport code System (PHITS) show that the dose increase is mostly caused by secondary protons emitted by the target. The modified radiation Weld after the shield has been characterized for its biological eVectiveness by measuring chromosomal aberrations in human peripheral blood lymphocytes exposed just behind the shield block, or to the direct beam, in the dose range 0.53 Gy. Notwithstanding the increased dose per incident proton, the fraction of aberrant cells at the same dose in the sample position was not significantly modified by the shield. The PHITS code simulations show that, albeit secondary protons are slower than incident nuclei, the LET spectrum is still contained in the low-LET range (
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