Feasibility study of a strong ultra cold neutron source

The heat that would be produced in a superthermal ultra-cold neutron source proposed by Golub and Pendlebury is evaluated when it is placed in a cold neutron field. The source strength achievable in the present technology is also discussed.Paper based on the KEK Internal Report 83-7 (Dee), p 223, and 84-2 (Dec), p 139, by H.Y. and M.U.     

Slow neutron scattering and intermolecular excitations in liquid hydrogen

A simple analytical model for inelastic neutron scattering in liquid hydrogen with the effects of delayed diffusion and intermolecular vibrations with a single frequency parameter is proposed. Calculated results show good agreements with experimental results of total and differential scattering cross sections as well as the energy spectra of neutrons in liquid hydrogen moderators, and thus indicate the importance of the consideration of intermolecular excitations in the dynamics of liquid hydrogen.     

Development of Polarized HD Target for Future LEPS Experiments at Spring-8

We are carrying out hadron photoproduction experiments by using polarized photon beams at SPring-8 in Japan.In 2005,we started developing a polarized HD target for future experiments using both the polarized photon beams and the polarized target.The polarized HD target is an idealistic target for experiments observing reactions with small cross sections because the HD does not include heavy nuclei which produce many background events.The measurement of double polarization asymmetries is expected to give much important information to investigate the nucleon hidden structure,hadron photoproduction dynamics,and exotic hadron property.We report on the present status of the development of the polarized HD target al RCNP.     

Measured total cross sections of slow neutrons scattered by gaseous and liquid 2H(2)

The total scattering cross sections for slow neutrons with energies E in the range 300 neV to 3 meV for gaseous and liquid ortho-2H2 have been measured. The cross sections for 2H2 gas are found to be in excellent agreement with both the Hamermesh and Schwinger and the Young and Koppel models. For liquid 2H(2), we confirm the existing experimental data in the cold neutron range and the discrepancy with the gas models. We find a clear 1 / square root[E'] dependence at low energies for both states. A simple explanation for the liquid 2H2 cross section is offered.     

Optical array logic network computing: Design of a prototype system

We present the architecture of novel optoelectronic parallel computing called optical array logic network computing (OAL-NC). In the OAL-NC, electronic processing elements execute local operations, whereas an optical network processor is dedicated to global operations as well as data transfer. As a prototype of the OAL-NC, a 16x16 pixel system is designed at a logical level. Issues associated with the design task are discussed.     

Experimental study of macroscopic coupled resonators for neutron waves

The viscosity coefficient of flux motion in lead films was determined using high resolution magnetooptical flux detection combined with measurements of the flux-flow voltage. A comparison with theoretical models shows, that eddy-current damping is the dominant mechanism for the viscous drag force. The experimental results indicate, that frictional forces due to pinning centers can be neglected in our specimens. The viscosity coefficient was determined by a measurement of the number and the size of flux tubes and their velocities during the flux-flow process.Supported by a grant from the Deutsche Forschungsgemeinschaft     

Measurements of ultracold-neutron lifetimes in solid deuterium

We present the first measurements of the survival time of ultracold neutrons (UCNs) in solid deuterium (SD2). This critical parameter provides a fundamental limitation to the effectiveness of superthermal UCN sources that utilize solid ortho-deuterium as the source material. These measurements are performed utilizing a SD2 source coupled to a spallation source of neutrons, providing a demonstration of UCN production in this geometry and permitting systematic studies of the influence of thermal up-scatter and contamination with para-deuterium on the UCN survival time.