No abstract available

[en] Here, a new design for the anode of a time projection chamber, consisting of a charge-detecting "tile", is investigated for use in large scale liquid xenon detectors. The tile is produced by depositing 60 orthogonal metal charge-collecting strips, 3 mm wide, on a 10 cm × 10 cm fused-silica wafer. These charge tiles may be employed by large detectors, such as the proposed tonne-scale nEXO experiment to search for neutrinoless double-beta decay. Modular by design, an array of tiles can cover a sizable area. The width of each strip is small compared to the size of the tile, so a Frisch grid is not required. A grid-less, tiled anode design is beneficial for an experiment such as nEXO, where a wire tensioning support structure and Frisch grid might contribute radioactive backgrounds and would have to be designed to accommodate cycling to cryogenic temperatures. The segmented anode also reduces some degeneracies in signal reconstruction that arise in large-area crossed-wire time projection chambers. A prototype tile was tested in a cell containing liquid xenon. Very good agreement is achieved between the measured ionization spectrum of a ²⁰⁷Bi source and simulations that include the microphysics of recombination in xenon and a detailed modeling of the electrostatic field of the detector. An energy resolution σ/E=5.5% is observed at 570 keV, comparable to the best intrinsic ionization-only resolution reported in literature for liquid xenon at 936 V/cm.

No abstract available

No abstract available

[en] We have measured the branching ratio GAMMA (K/sub L/ → π⁺π^-)/GAMMA (K/sub L/ → all) to be (2.01 +- 0.09) x 10^-3. This value is in good agreement with other recent determinations of this branching ratio and yields a value for the CP-violating parameter eta/sub + -/ of (2.25 +- 0.05) x 10^-3

[en] The branching ratio GAMMA (K⁰/sub L/ → μ⁺μ^-)/GAMMA (K⁰/sub L/ → π⁺π^-) has been measured and found to be 4.0atsup +1.4atatsub -0.9at x 10^-6. With the same apparatus the branching ratio GAMMA (K⁰/sub L/ → π⁺π^-)/GAMMA (K⁰/sub L/ → all) has been measured to be (2.01 +- 0.09) x 10^-3. The combination of these two results gives GAMMA (K⁰/sub L/ → μ⁺μ^-)/GAMMA (K⁰/sub L/ → all) < 8.1atsup +2.8atatsub -1.8at x 10^-9. This result is consistent with the lower bound predicted from the decay rate K/sub L/ → γγ and unitarity

[en] The design and construction of two lead/liquid argon electromagnetic shower detectors are described. Test results in beams of electrons and π^- of momenta 0.125-4 GeV/c and 1-4 GeV/c respectively are presented. Measurements were made of the energy resolution for electromagnetic showers, the position resolution, the behavior of the device in a transverse magnetic field and the radial and longitudinal characteristics of energy deposition, especially as they apply to π^-/e^- discrimination. (Auth.)

[en] Individual Ba ions are trapped in a gas-filled linear ion trap and observed with a high signal-to-noise ratio by resonance fluorescence. Single-ion storage times of ∼5 min (∼1 min) are achieved using He (Ar) as a buffer gas at pressures in the range 8 x 10^-5 - 4 x 10^-3 torr. Trap dynamics in buffer gases are experimentally studied in the simple case of single ions. In particular, the cooling effects of light gases such as He and Ar and the destabilizing properties of heavier gases such as Xe are studied. A simple model is offered to explain the observed phenomenology

[en] A novel technique has been developed to build vessels for liquid xenon ionization detectors entirely out of ultra-clean fluoropolymer. We describe the advantages in terms of low radioactivity contamination, provide some details of the construction techniques, and show the energy resolution achieved with a prototype all-fluoropolymer ionization detector

[en] We describe a source capable of producing single barium ions through nuclear recoils in radioactive decay. The source is fabricated by electroplating ¹⁴⁸Gd onto a silicon α-particle detector and vapor depositing a layer of BaF₂ over it. ¹⁴⁴Sm recoils from the alpha decay of ¹⁴⁸Gd are used to dislodge Ba⁺ ions from the BaF₂ layer and emit them in the surrounding environment. The simultaneous detection of an α particle in the substrate detector allows for tagging of the nuclear decay and of the Ba⁺ emission. The source is simple, durable, and can be manipulated and used in different environments. We discuss the fabrication process, which can be easily adapted to emit most other chemical species, and the performance of the source.