Simulations of heat generation and conduction on a land/groove disc
We applied the finite-difference time-domain (FDTD) method to an optical disc to estimate the energy absorption inside a multi-layered disc with land-and-groove structure. The FDTD method was developed to measure the electromagnetic fields generated by diffraction in a near-field. Afterwards we analyzed the heat conduction. We found that temperature transition depended not only on conductivity but on the initial distribution of the heat and on disc geometry.
Optical disk system using blue-violet laser
Many technologies for the next DVD generation using a blue-violet laser have been developed. This disk system will be applied for audio-visual application and computer peripheral application, like DVD-RAM. In this system three items, large capacity, high data-transfer-rate and reliability, are equally important and their targets have been set. To go toward these targets, the following technologies corresponding to technical fields such as media, optical head, servo-mechanism, read/write channel, signal processing and so on have been developed. Additionally, the basic subjects crossing over these technical fields to solve new problems that have arisen from this generation and have been neglected before were studied.
Monte carlo simulation of events with Drell-Yan lepton pairs from antiproton-proton collisions
The complete knowledge of the nucleon spin structure at leading twist requires also addressing the transverse spin distribution of quarks, or transversity, which is yet unexplored because of its chiral-odd nature. Transversity can be best extracted from single-spin asymmetries in fully polarized Drell-Yan processes with antiprotons, where valence contributions are involved anyway. Alternatively, in single-polarized Drell-Yan the transversity happens convoluted with another chiral-odd function, which is likely to be responsible for the well known (and yet unexplained) violation of the Lam-Tung sum rule in the corresponding unpolarized cross section. We present Monte Carlo simulations for the unpolarized and single-polarized Drell-Yan pp{sup ({up_arrow}}{sup )}{yields}{mu}{sup +}{mu}{sup -}X at different center-of-mass energies in both configurations where the antiproton beam hits a fixed proton target or it collides on another proton beam. The goal is to estimate the minimum number of events needed to extract the above chiral-odd distributions from future measurements at the high energy storage ring (HESR) at GSI. It is important to study the feasibility of such experiments at HESR in order to demonstrate that interesting spin physics can be explored already using unpolarized antiprotons.