Astrophysical S_(E2) Factor of ~(12)C(α,γ)~(16)O Reaction through ~(12)C(~(11)B,~7Li)~(16)O Transfer Reaction

<正>The ~(12)C(α,γ)~(16)O reaction is believed to be one of the most crucial reactions in nuclear astrophysics.Following the production of ~(12)C by the triple-αprocess,it strongly influences the ratio of the abundances for the main isotopes of carbon     

The cross section calculation of ~(112)Sn(α,γ) ~(116)Te reaction with different nuclear models at the astrophysical energy range

The theoretical cross section calculations for the astrophysical p process are needed because most of the related reactions are technically very difficult to be measured in the laboratory. Even if the reaction was measured,most of the measured reactions have been carried out at the higher energy range from the astrophysical energies.Therefore, almost all cross sections needed for p process simulation have to be theoretically calculated or extrapolated to the astrophysical energies.~(112)Sn(α,γ)~(116)Te is an important reaction for the p process nucleosynthesis. The theoretical cross section of ~(112)Sn(α,γ)~(116)Te reaction was investigated for different global optical model potentials,level density, and strength function models at the astrophysically interested energies. Astrophysical S factors were calculated and compared with experimental data available in the EXFOR database. The calculation with the optical model potential of the dispersive model by Demetriou et al., and the back-shifted Fermi gas level density model and Brink-Axel Lorentzian strength function model best served to reproduce experimental results at an astrophysically relevant energy region. The reaction rates were calculated with these model parameters at the p process temperature and compared with the current version of the reaction rate library Reaclib and Starlib.     

Astrophysical ~(13)N(p,γ)~(14)O Reaction Rate

13N(p,γ)14O is is one of the key reactions in the hot CNO cycle which occurs at stellar temperatures around T9≤0.1. At the energies of astrophysical interest, the 13N(p,γ) 14O reaction is dominated by the     

Preparation of ~(242)Cm

This work concerns in the preparation of carrier-free 242Cm (T1/2=162.8 d,α-decay). The 242Cm was produced via reaction1 / 2241 242 β242Am(n, γ) Am ?T? =??16 h?→ Cm. The reaction cross section is 553× 10-28 m2,few reaction products are produced simul     

Cross Section Measurements for ~(111)Cd(n,p)~(111m)Ag,~(106)Cd(n,2n)~(105)Cd,~(110)Cd(n,2n)~(109)Cd,~(116)Cd(n,2n)~(115m)Cd and ~(116)Cd(n,2n)~(115g)Cd Reactions

Activation cross sections for cadmium were measured in the neutron energy range from 13.40 MeV to 14.80 MeV using the T(d,n)~4He reaction as neutron source. The cross sections of ~(27)Al(n,α)~(24)Na reaction is used as standard one.     

Measurement of Double Differential Cross Sections for ~(40)Ca(n,α)~(37)Ar Reaction at 5.0 and 6.0 MeV

Introduction Calcium is one of the most important structural materials. The abundance of ~(40)Ca in natural calcium is 96.94%, so ~(40)Ca(n,α) data are very important in nuclear engineering. As we know, experimental data for ~(40)Ca(n,α) reaction are scarce and there are large differences among them. Although ~(40)Ca is a double magic nucleus, theoretical calculation of ~(40)Ca(n,α) data is difficult to fit experimental ones. Reliable data are needed for the study of reaction mechanism.     

The total cross sections of the ~(11)B(α,n)~(14N) and the ~(10)B(α,n)~(13)N reactions between 2 and 6 MeV

There is considerable interest in potential aneutronic fusion reactors. One possible reaction is~(11)B(p,a)2a.However, the emitted alpha particles are energetic enough to generate neutrons by interacting with boron inside the reactor through the ~(11)B(α,n)~(14N) and ~(10)B(α,n)~(13)N reactions.To aid in evaluating neutron production within this potential aneutronic reactor, the total cross sections were measured for the ~(11)B(α,n)~(14N) reaction between 2 and 6 MeV and for the ~(10)B(α,n)~(13)N reaction between 2 and 4.8 MeV. The results are presented and compared with previously reported results.     

Theoretical Calculation of Neutron Cross Sections for ~(176)Hf

Neutron activation cross sections calculation for ~(176)Hf in the neutron energy below 20 MeV is carried out with UNF code. The calculated cross sections for (n,γ), (n,p), (n,α), (n,d), (n,t), (n,2n) and (n,3n) reaction are given. The results of the calculation are compared with the available experimental data and a good agreement is obtained. The calculation is also compared with the relevant evaluation data.     

Evaluation of the (n,α) Cross Sections for ~(58, 60～62, 64)Ni and ~(Nat)Ni

The cross section of the (n,α) reaction is very important for fusion reactor for monitoring neutron field in the context of radiation induced material damage, radiation safety, neutron dosimetry, etc. The natural nickel consists of five stable isotopes, i. e. ~(58)Ni,~(60～62,64)Ni. Their abundances and threshold energies are given in Table 1.     

Indirect Measurement of 57.7 keV Resonance Strength for ~(25)Mg(p,γ)~(26)AI via(~7Li,~6He) Reaction

<正>~(25)Mg (p,γ)~(26)Al is the most important reaction in the Mg-Al cycle in the hydrogen burning regions of stars.Its cross sections at stellar ener-gies are essential to understand the issues of radioactive~(26)Al in the Galaxy and meteorites.The57.7 keV is one of the dominant resonances forthe~(25)Mg (p,γ)~(26)Al astrophysical reaction rates,     

Evaluation of Neutron Activation Cross Sections for ~(93)Nb(n,2n)~(92m)Nb and ~(93)Nb(n,n′)~(93m)Nb Reactions from Threshold to 20 MeV

Niobium is a very important structure material in nuclear fusion engineering. The activation cross sections of neutron interaction with ~(93)Nb must be considered for the evaluation of radiation safety, radiation induced material damage. Meanwhile, knowledge of the neutron(n,2n) and (n,n') reactions have been used for the neutron dosimetry. The dosimetry reaction of ~(93)Nb(n,n')~(93m)Nb is characterized by the low threshold energy less than 0.1     

Determination of Astrophysical ~(26)Si(p, γ)~(27)P Reaction Rate From Asymptotic Normalization Coefficients of ~(27)Mg → ~(26)Mg n

The 1.809 MeV γ-ray from the decay of 26Al is an excellent observable for some astrophysical events, such as novae and X-ray burst. The nucleosynthesis of 26Al is dominated by the reaction chain 24Mg(p,γ)25Al(β )25Mg(p,γ)26Al, however, it is complicat…     

Tests of the GIC and Measurements of Angular Distributions and Energy Spectra for ~(58)Ni(n,p)~(58)Co Reaction at 4.1 MeV

On the basis of measurements of double differential cross sections for (n,α) reactions in 5-7 MeV neutron energy region using gridded ionization chamber (GIC), we constructed a new GIC which, compared with the old ones, can bear higher pressure and makes it possible to measure (n,p) reactions up to 6 MeV and (n,xα) reactions up to 20 MeV. To test the new chamber, the saturation property for argon and krypton mixed with a few percent CO_2 was studied using ~(241)Am and compound Pu α source and tritium from ~6Li(n_(th),t)~4He, and the two dimensional spectra for ~(241)Am and Pu α source, ~6Li(n_(th),t)~4He and H(n,p) reactions were measured. The measured energy spectra and angular distributions for α and tritium are reasonable, and the derived data for α, proton and tritium in argon and krypton from the measured spectra data were compared with the calculated ones. They are in good agreement. The angular distributions and energy spectra for ~(58)Ni(n,p)~(58)Co reaction at 4.1 MeV neutron energy were m     

Measurement of Double Differential Cross Sections for ~(39)K(n,α)~(36)Cl Reaction

Introduction ~(39)K(n,α)~(36)Cl reaction data are important in nuclear engineering, nuclear medicine, astrophysics as well as in the study of nuclear mechanism. As we know, experimental data for ~(39)K(n,α)~(36)Cl reaction are scanty and there is no double differential datum. The double differential cross section data of ~(39)K(n,α)~(36)Cl reaction were measured at 4.41±0.26, 5.46±0.21 and 6.52±0.16 MeV using a gridded ionization chamber (GIC).     

~(25)Mg(p,γ)~(26)Al Astrophysical Reaction Rate

<正>A total ~(26)Al mass were derived through the analysis of the measured gamma spectra by the COMPTEL telescope.The ~(25)Mg(p,γ)~(26)Al reaction is the main way to produce ~(26)Al in the galaxy and its astrophysical reaction rates are dominated by the capture reactions of isolated narrow resonances in the ~(26)Al excited state.Up to date,the     

Halo Structure of the Isobaric Analog States in Some Mirror Nuclei

Using ANC method the rms radius of the last nucleon in the 2s1/2 isobaric analog states of 21Ne/2lNa and 17O / 17F is extracted from transfer reaction data. The results are summarized in Tab. 1. The 2s1/2 single proton states in 21Na and 17O have the rms radii almost twice as large as that for their core nuclei (2.88 fin for 20Ne and 2.71 fm for 16O) and are proton halo states, while their isobaric analog states in 2INe and I7O can be considered as neutron skin states, because the neutrons in these states have one third of the probability staying out of the nuclear interaction range. The obvious difference in the rms radii between a mirror pair indicates the binding energy difference between the     

Study of Crucial Nuclear Reaction in Nucleosynthesis of Elements

<正>The~(12) C (α,γ)~(16)O reaction is quoted as the holy grail in nuclear astrophysics.The cross section of this reaction affects not only the evolution of all M0.55M☉stars but also nucleosynthesis of elements up to iron and the evolution of the massive stars and their final fates.The littlechange for this reaction rate can cause drastic changes in the abundance of other elements,     

恒星中子源~(13)C(α,n)~(16)O反应的研究

13 C(α,n)16 O是渐进巨星支(AGB)星中慢速中子俘获(s)过程的主中子源反应,而17 O 6.356 MeV1/2+阈下共振对13 C(α,n)16 O反应影响很大。本文使用HI-13串列加速器和Q3D磁谱仪,首次测量了13C(11B,7Li)17 O转移反应角分布,确定了影响13C(α,n)16 O反应最关键、最不确定的17 O(Ex=6.356MeV)阈下共振态的α宽度,从而得出天体物理能区13 C(α,n)16 O反应的天体物理S因子和反应率,澄清了国际上已有S因子数据间高达25倍的巨大分歧。AGB星s过程核合成网络计算表明:新反应率数据导致恒星中铅的丰度增加了25%。     

The Cross Section Evaluation and Recommendation of ~(197)Au (n,2n)~(196)Au Reaction

The evaluation for 197Au(n,2n)196Au cross section was performed, the data of this reaction in the neutron energy range from threshold to 30 MeV were given, compared with the evaluation results by YUAN Hanrong et al., ZHAO Wenrong et al, Jose Martinez-Rico and YU Baosheng et al.. The agreement between different evaluations is good. However, the deviations are shown up for the data from ENDF/B-6 and JEF-2.2.