A Prediction of a New Dibaryon System (Ω-Ω-)Jπ=o+

The structure of a new dibaryon (ΩΩ)_o+ is studied and predicted in the framework of the chiral SU(3) quark model by solving a resonating group method equation. The binding energy of this dibaryon is around 100 MeV, the mean root square of the distance between two Ωs is 0.84 fm and the preliminary estimated mean lifetime is about two times longer than that of the free Ω. All these interesting properties and also the two negative charge units it carried could make it be easily identified experimentally in the heavy-ion collision process. The production probability of this new dibaryon in 158A GeV Pb+Pb collision is estimated using the thermal model, which is of the order of 10^-6 to 10^-5 per event; And it is expected, that with the increase of temperature, the production rate will also be increased.     

A Discussion of the Question in Connexion with the Expansion of a Divergent Series Encountered in Calculating Nuclear 2υ-2β Decay Matrix Element

It is shown that the expansion and summation of the divergent series occurring in 2υ-2β decay calculation^[1,2] can be well-defined without mathematical flaw.     

Electronic Energy Loss and Straggling of Protons in Metals

By making use of the linear-response dielectric theory and local electron density approximation, we calculate the electronic stopping cross section and energy straggling. of protons in metals. The correlation and exchange interaction of electron gas in metals is taken into consideration by introducing a local-field-correction function.in the dielectric function. The theoretical results are compared with experimental and empirical data, as well as with other previous theoretical results.     

Compression Properties of Finite Nuclear Matter at Zero and Finite Temperatures with the Skyrme Force SKM

By taking into account the finite-size effect rationally in the framework of the Hartree-Fock theory, compression properties at zero and finite temperatures of finite nuclear matter are investigated with the Skyrme force SKM^*. Energies of the isoscalar giant monopole resonance of nuclei at zero temperature calculated are found to be in agreement with experimental and empirical values.     

ON THE HYDROGEN MOLECULAR CORRECTION TO THE TRITON β-SPECTRUM AND THE MEASUREMENT OF THE NEUTRINO MASS

By using a highly accurate variational wave function with 50 parameters for hydrogen molecule^[4] and the wave function of HeH⁺ used by Wolniewicz with 64 parameters^[5], the behavior of the β-spectrum of H-T→ HeH⁺+β^-+νe is discussed. The spectral shape thus obtained deviates remarkably from the β-spectrum of an atomic triton, and hence is different from the for mula used by Lyubimov et al. in determining the neutrino mass. This means that the "atomic approximation" is invalid in describing the molecular β-spectrum of valine, and the conclusion about the value of neutrino mass based upon the analysis of β -spectrum of valine also cannot be regarded as a reliable one. Therefore, in order to obtain ari accurate value of neutrino mass from the β-spectral shape, it is important to investigate the structure of the radioactive source, from which the corection has arisen.     

A MODEL OF NEUTRINO STELLAR SYSTEM AND THE UPPER BOUND OF NEUTRINO MASS OBTAINED FROM THE RCTATION CURVES OF SOME GALAXIES

We discuss in this paper a stellar model of degenerate massive neutrinos with a core made of heavy matter. Dimension of the core is much smaller than the scale of neutrino star. The Oppenheimer-Volkoff equation is solved for such a system. Our calculation shows that under certain conditions, this neutrino halo will resemble a pure neutrino star. We have further obtained insides the neutrino star (or halo) the rdtation curve and the gravitational red shifts. It is interesting to note that the relative rotation velocity v(r)EV(r)/V(R) (R is the radius of the neutrino star) depends only on the relative coordinate ξ=r/R in the nonrelativistic cases. Therefore, all nonrelativistically degenerate neutrino systems will have a universa1 relative rotation curve(v versus ξ). Within the accuracy of numeri calcalculation, we have also obtained a useful relation connecting the maximum velocity V_m and the corresponding coordinate R_m as V_mR_m2=0.231. By comparing this relation with the observed rotation data at large distances for some galaxies, we have obtained an upper bound for neutrino mass of about 6-9eV.     

RECOMBINATION MODEL OF SUBQUARK COLLISION AND SCALING VIOLATION IN SUPERHIGH ENERGY COLLISION

A recombination model of subquarks for superhigh energy collision is proposed.The new phenomena observed in experiments of superhigh energy cosmic ray can be explained naturally via the cascade decay of superfireballs of subquark stratum from this model.The mean multiplicity,the average transverse momentum,the distributions of both transverse and longitudinal momenta and the inclusive spectrum for the superhigh energy collision are obtained based on this model.It is shown that if the mean multiplicity of secondary particles increases as S increases according to the power law,the scaling violation should take place.Espe-cially,when the behavior of mean multiplicity changes from s⁺ to S⁺ there will be a significant jump of violation coofficient and the scaling violation.wil1 become more significant as S in-creases.It is also pointed out that the characteristic behavior of the existence of subquark stratum for the inclusive distribu-tion is almost model-independent and can be treated as a decided experimental verification of the appearance of subquark stratum,in particular,for the experiments with accelerator in the near future.     

氯化铯与三氯化锑在冰醋酸中所成复盐的初步研究

用重量法、容量法和放射性示踪法测定了氯化铯和三氯化锑在冰醋酸介质中形成的复盐的组成,初步确定为7CsCl·5SbCl₃。并且发现该复盐在一定条件下,经过适当时间可能逐渐向4CsCl·3SbCl₃转变,而不是向3CsCl·2SBCl₃转变.研究了两种复盐7CsCl·5SbCl₃和3CsCl₃·2SbCl₃在冰醋酸和9.965N盐酸中的溶解动力学,分別绘出它们的溶解动力学曲线。结果指出,除了3CsCl·2SbCl₃复盐在9.965N盐酸中是稳定的外,7CsCl·5SBCl₃复盐在冰醋酸和9.965N盐酸中以及3CsCl·2SbCl₃复盐在冰醋酸中均不稳定。也作了7CsCl·5SBCl₃和3CsCl·2SbCl₃两种复盐的初步热重分析和显微结晶观察,绘出了热重分析曲线,并计算了两个大平台部分的残重百分数。这些结果也指出两种复盐显然不同。     

6.8GeV/cπ-N非弹性作用下π0介子的产生

利用联合原子核研究所24立升丙烷气泡室照片,对动量为6.8GeV/cπ^-介子与核子非弹性作用产生π⁰介子的问题进行了研究。扫描了约2700对立体照片。在宽度为29.3厘米的有效范围内得到了1275个π^--N非弹性作用事例。在936个π^--p事例和339个π^--n事例中,观察到正电子、负电子对数目分别为240和89。考虑了气泡室对γ光子的探测效率,我们得到每个事例产生的平均π⁰介子数n_(π⁰)=1.00±0.06。γ光子的平均横动量为p_⊥γ=173MeV/c。此外,着重研究了γ光子的能量分布。在γ光子全部是由π⁰介子衰变产生以及π⁰介子和π^±介子具有相同能谱的假设下,利用在相同入射粒子能量的π^--N作用中所产生的次级π^±介子能量分布变换成γ光子的能量分布;将本实验所得的γ光子能量分布和变换得到的分布进行比较,这两个分布在实验误差范围内完全符合。     

Fragmentation Behavior and Ionization Potentials of Lead Clusters Pb_n(n≤30)

The properties of Pbn(n=2―30) clusters including binding energies,second differences in energy,and HOMO-LUMO gaps,especially fragmentation energies and ionization potentials,have been studied by ab initio calculation.The main fragmentation products of Pbn+ are shown to be Pb+Pbn-1+ for n≤14 and two small cluster fragments for larger ones with n14.The Pb13+ appears frequently as the products in the fragmentations of large clusters.Also,the calculated ionization potentials of the clusters are consistent with the experiment data.