Community Development in Kamphaeng Phet

departmental bulletin pape

Search for B decays into η'p, η'K^*, η'φ, η'ω and η'η^(')

We report on a search for the exclusive two-body charmless hadronic B meson decays B → η'ρ, B → η'K^*, B^0 → ηφ, B^0 → η'ω, and B0 →η'η^('). The results are obtained from a data sample containing 535×10^6 B\bar{B} pairs that were collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^+e^- collider. We find no significant signals and report upper limits in the range (0.5–6.5)×10^-6 for all of the above decays.journal articl

Observation of Large CP Violation and Evidence for Direct CP Violation in B0→π+π- Decays

journal articl

Engineering quantum wave-packet dispersion with a strong nonresonant femtosecond laser pulse

A nondispersing wave packet has been attracting much interest from various scientific and technological viewpoints. However, most quantum systems are accompanied by anharmonicity, so that retardation of quantum wave-packet dispersion is limited to very few examples only under specific conditions and targets. Here we demonstrate a conceptually universal method to retard or advance the dispersion of a quantum wave packet through “programmable time shift” induced by a strong nonresonant femtosecond laser pulse. A numerical simulation has verified that a train of such retardation pulses stops wave-packet dispersion.journal articl

Development of a spectral model based on charge transport for the Swift/BAT 32K CdZnTe detector array

[著者版]The properties of 32K CdZnTe (4 x 4 mm(2) large, 2 rum thick) detectors have been studied in the pre-flight calibration of the Burst Alert Telescope (BAT) on-board the Swift Gamma-ray Burst Explorer (scheduled for launch in November 2004). In order to understand the energy response of the BAT CdZnTe array, we first quantify the mobility-lifetime (mu tau) products of carriers in individual CdZnTe detectors, which produce a position dependency in the charge induction efficiency and results in a low-energy tail in the energy spectrum. Based on a new method utilizing Co-57 spectra obtained at different bias voltages, the mu tau for electrons ranges from 5.0 x 10(-4) to 1.0 x 10(-2) cm(2) V-1 while the mu tau for holes ranges from 1.3 x 10(-5) to 1.8 x 10(-4) cm(2) V-1. We find that this wide distribution of mu tau products explains the large diversity in spectral shapes between CdZnTe detectors well. We also find that the variation of mu tau products can be attributed to the difference of crystal ingots or manufacturing harness. We utilize the 32K sets of extracted mu tau products to develop a spectral model of the detector. In combination with Monte Carlo simulations, we can construct a spectral model for any photon energy or any incident angle. (c) 2005 Elsevier B.V. All rights reserved