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71.
Using a method developed in theory of double beta decay[1], we propose a new mechanism, namely the two-nucleon pion absorption-emission mechanism for pion double charge exchange reaction at low energies. The calculations are compared with the experimental data of the angular distribution at 50 MeV and the 0° excitation functions of the DCX reactions on 14C, 18O with energies < 130 MeV. It is found that the contribution of this new mechanism is very important at low energies. 相似文献
72.
A new method of calculating 2υ-2β decay probability ia derived. It is shown that with the present knowledge of nucleon-nucleon force and reasonable nuclear wave functions for the parent and daughter nuclei this method can provide a reliable result without using closure approximation. 相似文献
73.
According to Parisi's suggestion, we assume that the gluon possesses a non-zero effective mass μ. From the assumption we derive an effective Hamiltonian up to order β2 for quarbnium. For μ=0.8GeV and 0.4 GeV, we find the spectra as well as the relative leptonic widths for charmonium upsilon, which are in good agreement with experiment. 相似文献
74.
A fireball theory in the quark level with supersymmetry between quark and antidiquark is suggested. A preliminary study of this model indicates that it can well describe all characteristic phenomena of multiproduction. In particular, the appearance of diquarks will enhance the baryon yield in multiproduction. 相似文献
75.
In this paper, the Bethe-Salpeter equation for a Coulombic bound system consisting of a fermion (mass ml and spin 1/2) and an anti-fermion (mass m2 and spin 1/2) is solved. The approximate B-S wave functions for (∑U) atom are given. Utilizing the perturbative expansion of the quantum field theory of composite particles, the decay rate and branching ratio for E°→(∑+μ-)+νμ are calculated with accuracy up to order O(α). 相似文献
76.
It is shown that by applying PCAC, the 2β-decay process can be directly related to double-charge-exchange reaction. Therefore, by studying double-charge-exchange reactions one is able to determine the nuclear matrix element of the relevant 2β-decay experimentally. A preliminary analysis has indicated that if the experimental data of forward-angle cross section on Ca40 with pion beam at 164 Mev[9] are used and extrapolated to Ca48, then the squared nuclear matrix element thus determined is smaller than that calculated for Ca40→Ti48+2e-+2v[11] by 105~106. 相似文献
77.
It is shorn that the double magic nucleus 40Ca is unstable with respect to the double K-electron capture 40Ar. By using the shell model wave functions for both 40Ca and 40Ar, the lifetime of 40Ca is estimated as 1.2×1033yrs. 相似文献
78.
高频红外碳硫仪由于便捷高效,常应用于区域地球化学样品中硫的分析检测。本文采用高频红外碳硫仪测定低中高含量的硫,以纯铁屑、锡粒和钨粒为助熔剂,对样品称样量、助熔剂的种类、加入顺序和用量等因素进行探讨,确定了最佳分析岩石、土壤和水系沉积物中硫含量的条件,并且用国家一级标准物质验证了该方法的准确度和精密度。结果表明,当样品和助熔剂的加入顺序和质量分别为:0.05 g样品、0.5 g铁助熔剂、1.7 g钨粒时,土壤和水系沉积物中硫的测定结果最稳定,岩石标准样品额外的加入0.5 g锡改善样品流动性,提高分析准确度。该方法的相对标准偏差(RSD)小于6%(n= 12),相对误差绝对值小于8%。此方法具有操作简单、高效、稳定性好的特点,适合于大批量区域地球化学样品中硫的检测。 相似文献
79.
80.
Minh-Phuong TRAN Thanh-Nhan NGUYEN Phuoc-Toan HUYNH Nhu-Binh LY Minh-Dang NGUYEN Quoc-Anh HO 《数学物理学报(B辑英文版)》2022,(1):105-126
In this paper,we establish a new algorithm to the non-overlapping Schwarz domain decomposition methods with changing transmission conditions for solving one dimensional advection reaction diffusion problem.More precisely,we first describe the new algorithm and prove the convergence results under several natural assumptions on the sequences of parameters which determine the transmission conditions.Then we give a simple method to estimate the new value of parameters in each iteration.The interesti... 相似文献