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In order to provide a quantitative test of theoretical calculations incorporating meson-exchange currents and intermediate {Delta} resonances, we measure the normal-component spin correlation coefficient {ital C}{sub {ital NN}}, the differential cross section {ital d}{sigma}/{ital d}{Omega}, and the neutron and proton analyzing powers {ital A}{sub {ital n}} and {ital A}{sub {ital p}}, each as a function of angle, for {ital {rvec n}{rvec p}}{r_arrow}{ital d}{gamma} at {ital T}{sub {ital n}}=183 MeV. Our {ital {rvec n}{rvec p}}{r_arrow}{ital d}{gamma} results, combined with the previous cross section and photon asymmetry data collected in the past decade, place quite strong constraints on model calculations. Our data are in excellent agreement with theoretical predictions by Jaus and Woolcock that incorporate meson-exchange and isobar current effects and relativistic corrections, signifying great recent progress in our understanding of these effects in the nucleon-nucleon system.

A decommissioned LHC test magnet is being prepared as the CERN Axion Solar Telescope (CAST) experiment. The magnet has a field of 9.6 Tesla and length of 10 meters. It is being mounted on a platform to track the sun over ±8° vertically and ±45°, horizontally. A sensitivity in axion-photon coupling gαγγ < 5 × 10−11GeV−1 can be reached for mα ≤ 10−2eV, and with a gas filled tube-can reach gαγγ ≤ 10−10GeV−1 for axion masses mα < 2eV.

Pulse analysis techniques with the scintillator LiBaF/sub 3/:Ce allow very clean separation of densely ionizing radiation (protons, deuterons, tritons, alphas, etc.) from less densely ionizing radiation (electrons). Consequently, pulse height spectra for each type of radiation can be obtained simultaneously. The pulse discrimination is based on the presence or absence of sub-nanosecond core-valence luminescence and in crystals doped with Ce/sup +3/ the presence or absence of Ce luminescence having a /sup -/35 ns lifetime. We are developing a pulse discrimination technique based on digital signal processing (DSP) using a CAMAC based module from XIA, Inc. Discrimination between electrons (gammas) and the light charged particles is based on the ratio of signal amplitude in the first 50 ns to signal amplitude at a longer time interval. We are evaluating more complicated algorithms to determine whether discrimination between hydrogen isotopes and alpha particles can be achieved. These techniques may allow determination of pulse height spectra for thermal neutron capture events, fast neutron capture events, fast-neutron-induced nuclear reactions, alpha events from Ra impurities in the scintillator, and gamma events simultaneously using a single scintillator.

Pulse-shape discrimination techniques using the scintillator LiBaF/sub 3/ allow very clean separation of densely ionizing radiation (protons, tritons, alphas, etc.) from less densely ionizing radiation (electrons). The pulse-shape discrimination is based on the presence or absence of subnanosecond core-valence luminescence and in crystals doped with Ce/sup +3/ the presence or absence of Ce luminescence. We use a pulse discrimination technique based on integration of the signal over a short time interval compared to integration over a long time interval. Thermal neutron capture events, fast neutron capture events, fast neutron elastic scattering events on Li, and alpha events from Ra impurities in the scintillator have distinctive loci in a two-dimensional plot of the short-gate pulse heights versus long-gate pulse heights. The resolution (full-width at half-maximum) of the /sup 137/Cs gamma photopeak is about 16%, and the resolution of the thermal neutron peak from neutron capture on /sup 6/Li is about 17%. Applications of this scintillator include measurements of fast to thermal neutron ratios, fast neutron spectroscopy, alpha contamination, etc., in the presence of significant gamma radiation.

Pacific Northwest National Laboratory has designed and constructed a prototype portable neutron coincidence counter intended for use in a variety of applications, such as the verification and inspection of weapons components, safety measurements for novel and challenging situations, portable portal deployment to prevent the transportation of fissile materials, uranium enrichment measurements in hard-to-reach locations, waste assays for objects that cannot be measured by existing measurement systems, and decontamination and decommissioning. The counting system weighs less than 40 kg and is composed of parts each weighing no more than 5 kg. In addition, the counter`s design is sufficiently flexible to allow rapid, reliable assembly around containers of nearly arbitrary size and shape. The counter is able to discern the presence of 1 kg of weapons-grade plutonium within an ALR-8 (30-gal drum) in roughly 100 seconds and 10 g in roughly 1000 seconds. The counter`s electronics are also designed for maximum adaptability, allowing operation under a wide variety of circumstances, including exposure to gamma-ray fields of 1 R/h. This report provides a detailed review of the design and construction process. Finally, preliminary experimental measurements that confirm the performance capabilities of this counter are discussed. 6 refs., 18 figs., 3 tabs.

The Automated Particulate Sampler Field Test Model Operations Guide is a collection of documents which provides a complete picture of the Automated Particulate Sampler (APS) and the Field Test in which it was evaluated. The Pacific Northwest National Laboratory (PNNL) Automated Particulate Sampler was developed for the purpose of radionuclide particulate monitoring for use under the Comprehensive Test Ban Treaty (CTBT). Its design was directed by anticipated requirements of small size, low power consumption, low noise level, fully automatic operation, and most predominantly the sensitivity requirements of the Conference on Disarmament Working Paper 224 (CDWP224). This guide is intended to serve as both a reference document for the APS and to provide detailed instructions on how to operate the sampler. This document provides a complete description of the APS Field Test Model and all the activity related to its evaluation and progression.

The extension of singles (p↘,p↘′) studies to include coincident (p↘,p′γ) measurements can provide new information about the effective nucleon–nucleus interaction. We have therefore made simultaneous measurements of (p↘,p↘′) and (p↘,p′γ) observables for the 15.11 MeV, 1+, T=1 state in 12C at an incident beam energy of 200 MeV. Contained in these coincident observables are determinations of the sideways and longitudinal analyzing powers, D0S and D0L, which must vanish in singles measurements due to parity conservation. With this large data set on a transition with a relatively simple spin sequence, we have, in principle, enough information for a complete determination of the scattering amplitude.

Recent analyses of NN and πN scattering data have resulted in values for the πNN coupling constant which are significantly smaller than those obtained prior to 1987. These controversial results prompted us to investigate the usefulness of high‐quality spin measurements towards resolving this issue. We found that the normal component spin transfer observable DNN′ for p+p elastic scattering is very sensitive to g20, particularly at small angles. We have therefore determined precise values of DNN′ for this reaction for θlab=5.0°, 7.2°, 8.4°, 9.7°, 11.8°, 14.6°, 18.8°, 24°, 30°, and 38° at an incident beam energy of 200 MeV. The forward‐going proton was detected in the IUCF K600 spectrometer and the coincident recoil proton was detected in a Si/CsI detector telescope. Our preliminary DNN′ values are reproduced reasonably well by Arndt’s C200 solution, the Nijmegen PWA93, and the Nijmegen I potential, but differ severely from both Arndt’s SM94 global solution and the predictions of the Bonn potential.

Bowyer et al.1 present a novel mathematical approach for determining patterns of brain activity associated with performance of language tasks. The software developed by the authors has two main advantages, which could, in theory, ensure a level of confidence sufficient for presurgical planning applications. First, it takes into account the anatomy of the brain, constraining potential “sources” of magnetic activity based on physiologic and physical considerations. Second, and perhaps most important, the software is designed to operate unsupervised, significantly reducing the impact of subjective input from the user, a limitation characteristic of the “standard” method of the iterative application of the single equivalent current dipole (ECD) that the Bowyer et al. method claims to surpass in efficiency. Incidentally, the ECD method remains the “gold standard” in magnetoencephalography (MEG) studies on the cerebral mechanisms of basic sensory functions and of language, …