The astrophysical reaction rate of 12C（α,γ）16O plays a key role in massive star evolution. However, this reaction rate and its uncertainties have not been well determined yet, especially at T9=0.2. The existing results even disagree with each other to a certain extent. In this paper, the El, E2 and total （E1＋E2） 12C（α,γ）16O reaction rates are calculated in the temperature range from T9=0.3 to 2 according to all the available cross section data. A new analytic expression of the 12C（α,γ）16O reaction rate is brought forward based on the reaction mechanism. In this expression, each part embodies the underlying physics of the reaction. Unlike previous works, some physical parameters are chosen from experimental results directly, instead of all the parameters obtained from fitting. These parameters in the new expression, with their 3σ fit errors, are obtained from fit to our calculated reaction rate from T9=0.3 to 2. Using the fit results, the analytic expression of 12C（α,γ）16Oreaction rate is extrapolated down to T9=0.05 based on the underlying physics. The 12C（α,γ）16O reaction rate at T9=0.2 is （8.78 ± 1.52） × 10^15 cm3s^-1mol^-1. Some comparisons and discussions about our new 12C（α,γ）16Oreaction rate are presented, and the contributions of the reaction rate correspond to the different part of reaction mechanism are given. The agreements of the reaction rate below T9=2 between our results and previous works indicate that our results are reliable, and they could be included in the astrophysical reaction rate network. Furthermore, we believe our method to investigate the 12C（α,γ）16O reaction rate is reasonable, and this method can also be employed to study the reaction rate of other astrophysical reactions. Finally, a new constraint of the supernovae production factor of some isotopes are illustrated according to our 12C（α,γ）16O reaction rates.
The study of interactions between a high-power laser and atoms has been one of the fundamental and interesting topics in strong field physics for decades.Based on a nonperturbativemodel,ten years ago,we developed a set of programs to facilitate the study of interactions between a circularly polarized laser and atomic hydrogen.These programs included only contribution from the bound states of the hydrogen atom.However,as the laser intensity increases,contribution from continuum states to the excitation and ionization processes becomes larger and can no longer be neglected.Furthermore,because the original code is not able to add this contribution directly due to its many disadvantages,a major upgrade of the code is required before including the contribution from continuum states in future.In this paper,first we deduce some important formulas for contribution of continuum states and present modifications and tests for the upgraded code in detail.Second we show some comparisons among new results,old results from the original codes and the available experimental data.Overall the new result agrees with experimental data well.Last we present our calculation of above-threshold ionization(ATI)rate and compare it with a pertubative calculation.The comparison shows that our nonperturbative calculation can also produce ATI peak suppression.
The measurement of parity-violating （PV） observables in few-nucleon system can shed light on our current understanding of the weak interaction between nucleons.Theoretical models describe the nucleonnucleon weak interaction at low energies use a series of undetermined parameters.Two parity violating measurements have been considered： the capture of polarized slow neutrons on hydrogen （n ＋ p → d ＋ γ） at Los Alamos National Laboratory for first phase and Oka Ridge National Laboratory for second phase and the helicity dependence of the deuteron photodisintegration cross section using circularly polarized photons （γ ＋ d → n ＋ p） at Shanghai Institute of Applied Physics.The goal of both experiments is to constraint the weak meson-nucleon couplings to a precision of 1 ×10^-8 .The introduction of both experiments is presented.
We study the reaction cross sections （σR） and root-mean-square （RMS） radii of ^8Li and ^8B, the halo-like nuclei, with stable target ^12C, ^27Al and ^9Be within the standard optical-limit Glauber model, using densities obtained from relativistic mean-field （RMF） formalisms and other types of distributions. It is found that the experimental σR can be reproduced well at high energy. The RMS radius and Ar extracted by RMF- theory and harmonic oscillator distribution are compared. larger than those of SLi. In addition, we analyze in detail the We find that the RMS radius and Ar of SB are relationship between σR and density distribution.
