Bragg-like curve for dark matter searches; binary gases

The directional detection of low-energy recoil ions can provide strong possibility for observation of dark matter in the Galaxy. Quenching factors for 5-200 keV recoil ions in N2, CO2, CF4 and CS2 gases are evaluated and Bragg-like curves, the electronic energy deposition as a function of the projected range, are presented. The Bragg-like curves are intended for directional search for the dark matter candidate, WIMPs, using the gas TPC. Quenching factors for very heavy ions produced in alpha-decay in dry air, N2, CO2, CF4 and CS2 are also estimated and compared with experimental values.Comment: Submitted to Rad. Phys. Chem., 18 pages, 9 figure

Observation of Hysteretic Transport Due to Dynamic Nuclear Spin Polarization in a GaAs Lateral Double Quantum Dot

We report a new transport feature in a GaAs lateral double quantum dot that emerges only for magnetic field sweeps and shows hysteresis due to dynamic nuclear spin polarization (DNP). This DNP signal appears in the Coulomb blockade regime by virtue of the finite inter-dot tunnel coupling and originates from the crossing between ground levels of the spin triplet and singlet extensively used for nuclear spin manipulations in pulsed gate experiments. The unexpectedly large signal intensity is suggestive of unbalanced DNP between the two dots, which opens up the possibility of controlling electron and nuclear spin states via DC transport.Comment: 5 pages, 4 figure

ICONE14-89378 EXPERIMENTAL STUDY ON STRUCTUAL INTEGRITY OF A CORE SHROUD SUPPORT WITH A CRACK UNDER SEISMIC LOAD

ABSTRACT This study was performed to experimentally confirm the conservatism of the integrity assessment procedure for a cracked core shroud support of the boiling water reactor (BWR) under seismic load. From the comparison of the experimental and analytical results, it is shown that finite element method (FEM) is accurate and collapse load estimated by twice-elastic slope method is conservative

Performance and Fundamental Processes at Low Energy in a Two-Phase Liquid Xenon Dark Matter Detector

We extend the study of the performance of a prototype two-phase liquid xenon WIMP dark matter detector to recoil energies below 20 keV. We demonstrate a new method for obtaining the best estimate of the energies of events using a calibrated sum of charge and light signals and introduce the corresponding discrimination parameter, giving its mean value at 4 kV/cm for electron and nuclear recoils up to 300 and 100 keV, respectively. We show that fluctuations in recombination limit discrimination for most energies, and reveal an improvement in discrimination below 20 keV due to a surprising increase in ionization yield for low energy electron recoils. This improvement is crucial for a high-sensitivity dark matter search.Comment: 4 pages, 6 figures, submitted to DM06 conference proceedings in Nucl Phys

A low-temperature phase of the 1:1 complex of 2-(6-diethylamino-3-diethyl­iminio-3H-xanthen-9-yl)benzoate with ethyl gallate at 93 K

The title compound, C28H30N2O3·C9H10O5, is a well known red leuco complex of 2-(6-diethylamino-3-diethyl­iminio-3H-xanthen-9-yl)benzoate (rhodamine B base abbreviated to RBB, a leuco dye) with ethyl gallate (EG, developer). The structure of the complex at room temperature has recently been reported by Sekiguchi, Takayama, Gotanda & Sano [Chem. Lett. (2007 ▶), 36, 1010–1011]. We have found a new phase of the material with two discrete base/developer complexes (RBB-A/EG-A and RBB-B/EG-B) in the asymmetric unit at 93 K. There are no significant differences between the two developer mol­ecules EG-A and EG-B. The lactone ring of RBB is opened in each mol­ecule to form a zwitterionic structure. However, the xanthene system is almost flat in RBB-A (r.m.s. deviation 0.0234 Å) but is less so in RBB-B (r.m.s. deviation 0.1095 Å). Furthermore, the ethyl groups of the xanthene diethyl­amino substituents lie on the same side of the xanthene plane in RBB-A but on opposite sides in RBB-B. Dimeric dye/developer complexes are formed through inter- and intra­molecular O—H⋯O hydrogen bonds and are linked further into dimers by additional O—H⋯O hydrogen bonds involving either EG-A or EG-B developer mol­ecules

Detection of Scintillation Light of Liquid Xenon with a LAAPD

First observation of liquid xenon scintillation due to alpha-particles and gamma-rays with a large area avalanche photodiode immersed in the liquid is reported. An energy resolution of 10% (FWHM) and a coincidence time resolution of less then 1 ns (FWHM) were measured with 5.5 MeV alpha-particles and 511 keV gamma-rays, respectively. The quantum efficiency of the photodiode for xenon scintillation light (wavelength 178 nm) is estimated to be ~100%.Comment: 11 pages, 9 figures, to be published in Nuclear Instruments and Method