Momentum distribution and correlation of two-nucleon relative motion in 6^6He and 6^6Li

The momentum distribution of relative motion between two nucleons gives information on the correlation in nuclei. The momentum distribution is calculated for both $^{6}$He and $^6$Li which are described in a three-body model of $\alpha$+$N$+$N$. The ground state solution for the three-body Hamiltonian is obtained accurately using correlated basis functions. The momentum distribution depends on the potential model for the $N$-$N$ interaction. With use of a realistic potential, the $^6$He momentum distribution exhibits a dip around 2 fm$^{-1}$ characteristic of $S$-wave motion. In contrast to this, the $^6$Li momentum distribution is very similar to that of the deuteron; no dip appears because it is filled with the $D$-wave component arising from the tensor force.Comment: 14 pages, 9 figure

Low Energy Solar Neutrino Detection by using Liquid Xenon

Possibility to use ultra pure liquid Xenon as a low energy solar neutrino detector by means of $\nu$+e scatterings is evaluated. A possible detector with 10 tons of fiducial volume will give $\sim$14 events for pp-neutrinos and $\sim$6 events for $^{7}$Be neutrinos with the energy threshold at 50 keV. The detector can be built with known and established technologies. High density of the liquid- Xe would provide self-shields against the incoming backgrounds originating from the container and outer environments. Internal backgrounds can be reduced by distillation and other techniques. Purification of the liquid Xe can be done continuously throughout the experiment. The spallation backgrounds are estimated to be small though an experimental determination is neccessary. The liquid-Xe detector can also provide a significantly better sensitivity for the double beta decay and a dark matter search. However the 2$\nu$ double beta decay of $^{136}$Xe would be most background. It could be overcome if the 2$\nu$ lifetime is longer than 10$^{22}$yr. However, an isotope separation of $^{136}$Xe is inevitable for a shorter lifetime. The isotope separations would, intoroduce a new opportunity to definitively identify dark matter. The interesting feature in addition to the solar neutrino measurements will also be discussed.Comment: 16 pages, 4 figures, Talk presented at LowNu workshop, June-15-2000, Sudbury, Canad

Ab initio approach to s-shell hypernuclei 3H_Lambda, 4H_Lambda, 4He_Lambda and 5He_Lambda with a Lambda N-Sigma N interaction

Variational calculations for s-shell hypernuclei are performed by explicitly including $\Sigma$ degrees of freedom. Four sets of YN interactions (SC97d(S), SC97e(S), SC97f(S) and SC89(S)) are used. The bound-state solution of $_\Lambda^5$He is obtained and a large energy expectation value of the tensor $\Lambda N-\Sigma N$ transition part is found. The internal energy of the $^4$He subsystem is strongly affected by the presence of a $\Lambda$ particle with the strong tensor $\Lambda N-\Sigma N$ transition potential.Comment: Phys. Rev. Lett. 89, 142504 (2002

Ammonia formation caused by the presence of water in the wet grinding of silicon nitride powder

Si3 N4 powder (amorphous, alpha-, and beta-Si3 N4) was mixed with MeOH containing 8.87 mol. % H2O and ground. The NH3 generation rapidly increased after a grinding time of 100 hours. Silicon nitride sintered material was chosen as one of the high temperature, high strength structural materials and studies of the control of the raw material powder, preparation of the sintered body (finding the right assistant, hot press, high pressure sintering, fracture toughness and oxidation at high temperature were performed