118925554
Lambda Lambda interactions in finite-density QCD sum rules
The properties of Lambda hyperons in pure Lambda matter are studied with the finite-density quantum chromodynamics (QCD) sum rule approach. The first-order quark and gluon condensates in Lambda nuclear matter are deduced from the chiral perturbation theory. The sum-rule predictions are sensitive to the four-quark condensates, (2)(rho) and (rho) (rho), and the pi N sigma term. When (2)(rho) is nearly independent of density and (rho) (rho) depends strongly on density, we can obtain weakly attractive Lambda Lambda potentials (about several MeV) in the low Lambda density region, which agrees with the information from the latest double Lambda hypernucleus experiments. The nearly no-density dependence of (2)(rho) and strong density dependence of (rho) (rho) can be explained naturally if the properties of (2)(rho) and rho (rho) are assumed to be similar to those of pi pi and (K) over barK in nuclear medium, respectively.
10157335
Multi-deformed Configurations and Shape Coexistence for Superheavy Elements ∗
We use the considered axial deformed relativistic mean field theory to perform systematical calculations for Z = 112 and 104 isotopic chains with force parameters NL3, NL-SH and NL-Z2 sets. Three deformed chains (oblate, moderate prolate and super-deformed chain) are found for Z = 112 and 104 isotopic chains. It is found that there is a chain of super-deformed nuclei which can increase the stability of superheavy nuclei in the Z = 112 isotopic chain. Shape coexistence is found for Z = 112,104 isotopic chain and the position is defined. For moderate prolate deformed chains of Z = 112 and 104, there is shell closure at N = 184 for moderate prolate deformed chain. For oblate deformed chain of Z = 112, the shell closure appears around at N = 176. For super-deformed chains of Z = 112 and 104, the position of shell closure have strong parameter dependence. There is shell anomalism for oblate or superdeformed nuclei.
120641266
$K^-$-Nuclear Bound States in Relativistic Mean-Field Theory
50826737
The hyperon mean free paths in the relativistic mean field
The Λ- and Ξ−-hyperon mean free paths in finite nuclei are firstly calculated in the relativistic mean-field theory. The real optical potentials are derived from the RMF approach, while the imaginary parts are obtained from the assumptions: USIY = ασY·USIN and UVIY = αωY·UVIN. With these assumptions, the depth of the imaginary potential for Ξ− is WΞ − 3.5 MeV, and for Λ is WΛ − 7 MeV at low incident energy. We find that the hyperon MFP decreases with the increment of the incident energies of the hyperon (from 200 MeV to 800 MeV); and in the nuclear interior, the MFP is about 2–3 fm for Λ, and about 4–8 fm for Ξ−, depending on the incident energy of the hyperon.
121190690
Study of the radiation hardness of CsI(Tl) crystals for the BELLE detector
Abstract The radiation hardness of prototype CsI(Tl) crystals has been tested for the barrel electromagnetic calorimeter for the BELLE detector of the KEK B factory. Although samples made by one of the producers were found to be soft under irradiation, the problem was quickly improved when this information was fed back. All the tested crystals were found to meet our requirement. The light output was found to be almost uniform along a crystal, even when the front part was damaged by radiation. The damage causes a degradation of the attenuation length due to the formation of color centers; this conclusion was confirmed by a Monte Carlo ray-tracing study.