This paper reports that the experimental excitation functions of reaction （p,n） are measured for ^106pd and ^110pd at proton energy Ep = 6.1 - 7.5 MeV and Ep = 6.0 - 7.7 MeV respectively. The off-resonance excitatio...This paper reports that the experimental excitation functions of reaction （p,n） are measured for ^106pd and ^110pd at proton energy Ep = 6.1 - 7.5 MeV and Ep = 6.0 - 7.7 MeV respectively. The off-resonance excitation functions were compared with calculation values of the statistical model. A new formula used to estimate the peak cross section of isobaric analogue resonance was tested and it was found that calculation values agree reasonably well with the present data within experimental error, which confirms that the excitation strength of isobaric analogue state in （p,n） reaction not only depends on its spin, but also proportionally increases with the projectile proton spatial transmission Tp and the spectroscopic factor S for reaction （d,p） on the same target.展开更多
The feasibility of producing superheavy nuclei in proton evaporation channels was systematically studied within the dinuclear system(DNS)model.Due to the Z=114 proton-shell,one can synthesize Fl isotopes in proton eva...The feasibility of producing superheavy nuclei in proton evaporation channels was systematically studied within the dinuclear system(DNS)model.Due to the Z=114 proton-shell,one can synthesize Fl isotopes in proton evaporation channels.We only considered the case of evaporating one proton first and then n neutrons in this work,other cases were ignored due to the small cross-section.The production cross sections of unknown isotopes ^(290,291)Fl in ^(38)S+^(255)Es reaction are the highest compared with ^(50)Ti+^(243)Np and ^(54)Cr+^(239)Pa reactions,and the maximum cross sections are 1.1 and 15.1 pb,respectively.^(42)S+^(254)Es is a promising candidate to approach the island of stability as the radioactive beam facilities are upgraded in the future,and the production cross sections of ^(291−294)Fl in that reaction are estimated to be 3.2,6.0,4.0,and 0.1 pb,respectively.展开更多
A detailed description of the baryon direct Urca processes A: n → p + e + ν_e, B: Λ→ p + e + ν_e and C: Ξ^-→Λ + e + ν_e related to the neutron star cooling is given in the relativistic mean field approximatio...A detailed description of the baryon direct Urca processes A: n → p + e + ν_e, B: Λ→ p + e + ν_e and C: Ξ^-→Λ + e + ν_e related to the neutron star cooling is given in the relativistic mean field approximation. The contributions of the reactions B and C on the neutrino luminosity are calculated by means of the relativistic expressions of the neutrino energy losses. Our results show that the total neutrino luminosities of the reactions A, B and C within the mass range(1.603–2.067) M_⊙((1.515–1.840) M_⊙ for TM1 model) for GM1 model are larger than the corresponding values for neutron star without hyperons. Furthermore, although the neutrino emissivity of the reaction A is suppressed with the appearance of the proton ~1S_0 superfluid, the contribution of the reactions B and C can still quicken a massive neutron star cooling. In particular, the reaction C in PSR J1614-2230 and J0348+0432 is not suppressed by the proton ~1S_0 superfluid due to the higher threshold density of the reaction C, which will further speed up the two pulsars cooling.展开更多
Space nuclear power system is the key technology for deep space exploration missions in the future, especially for space base building-up. This paper evaluates several typical latest space nuclear reactor system （SNR...Space nuclear power system is the key technology for deep space exploration missions in the future, especially for space base building-up. This paper evaluates several typical latest space nuclear reactor system （SNRS） designs, and finds that most of their weights are heavier than necessary. From the point of weight-control, the SA4 design is the best but its design is more complex than others. A newly designed SNRS, based on the SAFE400 model, uses annular fuel and has better performance, with a fuel mass lower than that of the SAFE400 prototype by 18.75%. Meanwhile, different from former opinions, the delay neutron fractions of SNRS are not constant and change with the different SNRS designs. Therefore, designs of SNRS not to count the delayed neutron fracture or directly to consider it as 0.00677 are not appropriate.展开更多
文摘This paper reports that the experimental excitation functions of reaction （p,n） are measured for ^106pd and ^110pd at proton energy Ep = 6.1 - 7.5 MeV and Ep = 6.0 - 7.7 MeV respectively. The off-resonance excitation functions were compared with calculation values of the statistical model. A new formula used to estimate the peak cross section of isobaric analogue resonance was tested and it was found that calculation values agree reasonably well with the present data within experimental error, which confirms that the excitation strength of isobaric analogue state in （p,n） reaction not only depends on its spin, but also proportionally increases with the projectile proton spatial transmission Tp and the spectroscopic factor S for reaction （d,p） on the same target.
文摘The feasibility of producing superheavy nuclei in proton evaporation channels was systematically studied within the dinuclear system(DNS)model.Due to the Z=114 proton-shell,one can synthesize Fl isotopes in proton evaporation channels.We only considered the case of evaporating one proton first and then n neutrons in this work,other cases were ignored due to the small cross-section.The production cross sections of unknown isotopes ^(290,291)Fl in ^(38)S+^(255)Es reaction are the highest compared with ^(50)Ti+^(243)Np and ^(54)Cr+^(239)Pa reactions,and the maximum cross sections are 1.1 and 15.1 pb,respectively.^(42)S+^(254)Es is a promising candidate to approach the island of stability as the radioactive beam facilities are upgraded in the future,and the production cross sections of ^(291−294)Fl in that reaction are estimated to be 3.2,6.0,4.0,and 0.1 pb,respectively.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11447165,11373047,11404336 and U1731240Youth Innovation Promotion Association,CAS under Grant No.2016056the Development Project of Science and Technology of Jilin Province under Grant No.20180520077JH
文摘A detailed description of the baryon direct Urca processes A: n → p + e + ν_e, B: Λ→ p + e + ν_e and C: Ξ^-→Λ + e + ν_e related to the neutron star cooling is given in the relativistic mean field approximation. The contributions of the reactions B and C on the neutrino luminosity are calculated by means of the relativistic expressions of the neutrino energy losses. Our results show that the total neutrino luminosities of the reactions A, B and C within the mass range(1.603–2.067) M_⊙((1.515–1.840) M_⊙ for TM1 model) for GM1 model are larger than the corresponding values for neutron star without hyperons. Furthermore, although the neutrino emissivity of the reaction A is suppressed with the appearance of the proton ~1S_0 superfluid, the contribution of the reactions B and C can still quicken a massive neutron star cooling. In particular, the reaction C in PSR J1614-2230 and J0348+0432 is not suppressed by the proton ~1S_0 superfluid due to the higher threshold density of the reaction C, which will further speed up the two pulsars cooling.
文摘Space nuclear power system is the key technology for deep space exploration missions in the future, especially for space base building-up. This paper evaluates several typical latest space nuclear reactor system （SNRS） designs, and finds that most of their weights are heavier than necessary. From the point of weight-control, the SA4 design is the best but its design is more complex than others. A newly designed SNRS, based on the SAFE400 model, uses annular fuel and has better performance, with a fuel mass lower than that of the SAFE400 prototype by 18.75%. Meanwhile, different from former opinions, the delay neutron fractions of SNRS are not constant and change with the different SNRS designs. Therefore, designs of SNRS not to count the delayed neutron fracture or directly to consider it as 0.00677 are not appropriate.
