[en] An iron-free, low-energy charged-particle magnetic spectrometer is designed using a Helmholtz-coil geometry. Through the fringe fields of the coils, the spectrometer provides focusing in both the dispersive and non-dispersive planes. By choosing the optimal deflecting angle and the positions of the source and the focal distance, we expect to obtain a momentum resolution of the order of 0.3%

[en] A technique based on neutron activation has been developed for an extremely high sensitivity analysis of trace elements in organic materials. Organic materials are sealed in plastic or high-purity quartz and irradiated at the HFIR and MITR. The most volatile materials such as liquid scintillator (LS) are first preconcentrated by clean vacuum evaporation. Activities of interest are separated from side activities by acid digestion and ion exchange. The technique has been applied to study the liquid scintillator used in the KamLAND neutrino experiment. Detection limits of <2.4x10^-15 g ⁴⁰K/g LS, <5.5x10^-15 g Th/g LS, and <8x10^-15 g U/g LS have been achieved

[en] We report on the first detailed measurements of electron backscattering from low Z targets at energies up to 124 keV. Both energy and angular distributions of the backscattered electrons are measured and compared with electron transport simulations based on the Geant4 and Penelope Monte Carlo simulation codes. Comparisons are also made with previous, less extensive, measurements and with measurements at lower energies

[en] This article reviews the status of an experiment to study the neutron spin-electron angular correlation with the Los Alamos Ultra-Cold Neutron (UCN) source. The experiment will generate UCNs from a novel solid deuterium, spallation source, and polarize them in a solenoid magnetic field. The experiment spectrometer will consist of a neutron decay region in a solenoid magnetic field combined with several different detector possibilities. An electron beam and a magnetic spectrometer will provide a precise, absolute calibration for these detectors. An A-correlation measurement with a relative precision of 0.2% is expected by the end of 2002

[en] Ultra-cold neutrons (UCN), neutrons with energies low enough to be confined by the Fermi potential in material bottles, are playing an increasing role in measurements of fundamental properties of the neutron. The ability to manipulate UCN with material guides and bottles, magnetic fields, and gravity can lead to experiments with lower systematic errors than have been obtained in experiments with cold neutron beams. The UCN densities provided by existing reactor sources limit these experiments. The promise of much higher densities from solid deuterium sources has led to proposed facilities coupled to both reactor and spallation neutron sources. In this Letter we report on the performance of a prototype spallation neutron-driven solid deuterium source. This source produced bottled UCN densities of 145±7 UCN/cm³, about three times greater than the largest bottled UCN densities previously reported. These results indicate that a production UCN source with substantially higher densities should be possible

[en] Ultra-cold neutrons (UCN) have been produced at reactors over the last 30 years. Although very successful, experiments often suffer from low UCN statistics--as limited by the traditional production scheme. A new type of UCN source has been developed at Los Alamos. The source combines a spallation target, a cold neutron flux trap, and a solid deuterium converter for the down-scattering of cold neutrons into the ultra-cold regime. The breakthroughs of the last year include the theoretical understanding of the production mechanism and its experimental verification. The new technique is capable of delivering orders of magnitude higher densities of UCN. The highest UCN density ever stored in an experiment is reported

[en] 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

[en] We report on a new measurement of the parity-violating asymmetry in quasielastic electron scattering from the deuteron at backward angles at Q²=0.038 (GeV/c)². This quantity provides a determination of the neutral weak axial vector form factor of the nucleon, which can potentially receive large electroweak corrections. The measured asymmetry A=-3.51±0.57 (stat)±0.58 (syst) ppm is consistent with theoretical predictions. We also report on updated results of the previous experiment at Q²=0.091 (GeV/c)², which are also consistent with theoretical predictions

No abstract available

[en] We describe an electron spectrometer designed for a precision measurement of the neutron β-asymmetry with spin-polarized ultracold neutrons. The spectrometer consists of a 1.0-T solenoidal field with two identical multiwire proportional chamber and plastic scintillator electron detector packages situated within 0.6-T field-expansion regions. Select results from performance studies of the spectrometer with calibration sources are reported