A comparison of the polarization observables for the d(e, e\u27p) and P(e, e\u27p) reactions at quasi-free kinematics

Final-state recoil proton polarization observables were measured using the newly commissioned Proton Focal-Plane-Polarimeter at the MIT-Bates Linear Accelerator Center. This device permits access to a new class of electromagnetic spin observables. Measurements were made at two values of {dollar}{lcub}\cal Q{rcub}\sp2,{dollar} 0.38 and 0.50 (GeV/c){dollar}\sp2,{dollar} in the quasi-elastic region using the {dollar}d(\vec e,e\sp\prime\vec p)n{dollar} reaction in parallel kinematics with zero recoil momentum. Simultaneous measurements were also made using the {dollar}p(\vec e,e\sp\prime\vec p){dollar} reaction at the same kinematics allowing a precise comparison between the hydrogen and deuterium spin-dependent observables, {dollar}D\sb{lcub}LL{rcub}{dollar} and {dollar}D\sb{lcub}LT{rcub}{dollar} as well as the induced polarization {dollar}P\sb{lcub}n{rcub}.{dollar} In the elastic scattering limit the spin observables can be used to directly extract the ratio of {dollar}G\sbsp{lcub}E{rcub}{lcub}p{rcub}/G\sbsp{lcub}M{rcub}{lcub}p{rcub}.{dollar} Therefore, in the impulse approximation the results have direct bearing on the validity of approximations used to extract {dollar}G\sbsp{lcub}E{rcub}{lcub}n{rcub}/G\sbsp{lcub}M{rcub}{lcub}n{rcub}{dollar} for the neutron in analogous {dollar}d(\vec e,e\sp\prime\vec n)p{dollar} experiments. This comparison is also nearly free of systematic errors and is independent of both the beam polarization and the analyzing power of the {dollar}\sp{lcub}12{rcub}C(p,p\sp\prime){dollar} reaction. The results for deuterium are in good agreement with the hydrogen data and with the Plane-Wave-Impulse-Approximation theories of Arenhovel and Van Orden

Computational Analysis of Coriant and PNNL Radioxenon Data Viewers

The analysis by Coriant of the beta-gamma coincidence data coming from the ARSA systems show a systematic basis towards lower concentrations for all isotopes and a systematic increase in the minimum detectable concentrations. These variations can be directly traced to the method of analysis that is used by the Coriant software compared to the methods that have been developed by the International Noble Gas Experiment collaboration. This report details the differences and suggests solutions where appropriate. The report writers recommend that the algorithm changes be made to the Coriant software to bring up to the international standards

Symptoms of Paranoia Experienced by Students of Pakistani Heritage in England: The Role of Explicit and Implicit Identities and Perceived Discrimination

ABSTRACT: Individuals belonging to ethnic minority groups are less likely to experience symptoms of psychosis, such as paranoia, if they live in areas with high proportions of people from the same ethnic background. This effect may be due to processes associated with group belonging (social identification). We examined whether the relationship between perceived discrimination and paranoia was moderated by explicit and implicit Pakistani/English identification among students of Pakistani heritage (N = 119). Participants completed measures of explicit and implicit Pakistani and English identity, a measure of perceived discrimination, and a measure of paranoia. Perceived discrimination was the strongest predictor of paranoia (0.31). Implicit identities moderated the relationship between perceived discrimination and paranoia (-0.17). The findings suggest that higher levels of implicit Pakistani identity were most protective against high levels of paranoia (0.26, with low implicit English identity; 0.78, with medium English identity; 1.46, with high English identity). Overall, a complex relationship between identity and paranoia was apparent

Air Activation Following an Atmospheric Explosion

In addition to thermal radiation and fission products, nuclear explosions result in a very high flux of unfissioned neutrons. Within an atmospheric nuclear explosion, these neutrons can activate the various elemental components of natural air, potentially adding to the radioactive signature of the event as a whole. The goal of this work is to make an order-of-magnitude estimate of the total amount of air activation products that can result from an atmospheric nuclear explosion

Calculation of Minimum-Detectable-Concentration Levels of Radioxenon Isotopes Using the PNNL ARSA System

Measurement of xenon fission product isotopes is a key element in the global network being established to monitor the Comprehensive Nuclear-Test-Ban Treaty. The automated Radio-xenon Analyzer/Sampler (ARSA), built by Pacific Northwest National Laboratory, can detect 131mXe, 133mXe, 133Xe, and 135Xe via a beta-gamma counting system. Due to the variable background and sources of these four radio-xenon isotopes, it is important to have as sensitive a detection system as possible and to quantify the Minimum-Detectable-Concentrations (MDC) that such a system will be able to detect to preclude false negative and false positive results. From data obtained from IAR in Germany MDC values for 133Xe were well below the 1 mBq/SCMA as required by the PTS for the Comprehensive Test BAn Treaty [WGB TL-11,1999]

Origin and passivation of fixed charge in atomic layer deposited aluminum oxide gate insulators on chemically treated InGaAs substrates

We report experimental and theoretical studies of defects producing fixed charge within Al(2)O(3) layers grown by atomic layer deposition (ALD) on In(0.53)Ga(0.47)As(001) substrates and the effects of hydrogen passivation of these defects. Capacitance-voltage measurements of Pt/ALD-Al(2)O(3)/n-In(0.53)Ga(0.47)As suggested the presence of positive bulk fixed charge and negative interfacial fixed charge within ALD-Al(2)O(3). We identified oxygen and aluminum dangling bonds (DBs) as the origin of the fixed charge. First-principles calculations predicted possible passivation of both O and Al DBs, which would neutralize fixed charge, and this prediction was confirmed experimentally; postmetallization forming gas anneal removed most of the fixed charge in ALD-Al(2)O(3). (C) 2010 American Institute of Physics. (doi:10.1063/1.3399776

Representative Atmospheric Plume Development for Elevated Releases

An atmospheric explosion of a low-yield nuclear device will produce a large number of radioactive isotopes, some of which can be measured with airborne detection systems. However, properly equipped aircraft may not arrive in the region where an explosion occurred for a number of hours after the event. Atmospheric conditions will have caused the radioactive plume to move and diffuse before the aircraft arrives. The science behind predicting atmospheric plume movement has advanced enough that the location of the maximum concentrations in the plume can be determined reasonably accurately in real time, or near real time. Given the assumption that an aircraft can follow a plume, this study addresses the amount of atmospheric dilution expected to occur in a representative plume as a function of time past the release event. The approach models atmospheric transport of hypothetical releases from a single location for every day in a year using the publically available HYSPLIT code. The effective dilution factors for the point of maximum concentration in an elevated plume based on a release of a non-decaying, non-depositing tracer can vary by orders of magnitude depending on the day of the release, even for the same number of hours after the release event. However, the median of the dilution factors based on releases for 365 consecutive days at one site follows a power law relationship in time, as shown in Figure S-1. The relationship is good enough to provide a general rule of thumb for estimating typical future dilution factors in a plume starting at the same point. However, the coefficients of the power law function may vary for different release point locations. Radioactive decay causes the effective dilution factors to decrease more quickly with the time past the release event than the dilution factors based on a non-decaying tracer. An analytical expression for the dilution factors of isotopes with different half-lives can be developed given the power law expression for the non-decaying tracer. If the power-law equation for the median dilution factor, Df, based on a non-decaying tracer has the general form Df=a〖×t〗^(-b) for time t after the release event, then the equation has the form Df=e^(-λt)×a×t^(-b) for a radioactive isotope, where λ is the decay constant for the isotope

Sexual Signal Evolution Outpaces Ecological Divergence during Electric Fish Species Radiation

Natural selection arising from resource competition and environmental heterogeneity can drive adaptive radiation. Ecological opportunity facilitates this process, resulting in rapid divergence of ecological traits in many celebrated radiations. In other cases, sexual selection is thought to fuel divergence in mating signals ahead of ecological divergence. Comparing divergence rates between naturally and sexually selected traits can offer insights into processes underlying species radiations, but to date such comparisons have been largely qualitative. Here, we quantitatively compare divergence rates for four traits in African mormyrid fishes, which use an electrical communication system with few extrinsic constraints on divergence. We demonstrate rapid signal evolution in the Paramormyrops species flock compared to divergence in morphology, size, and trophic ecology. This disparity in the tempo of trait evolution suggests that sexual selection is an important early driver of species radiation in these mormyrids. We also found slight divergence in ecological traits among closely related species, consistent with a supporting role for natural selection in Paramormyrops diversification. Our results highlight the potential for sexual selection to drive explosive signal divergence when innovations in communication open new opportunities in signal space, suggesting that opportunity can catalyze species radiations through sexual selection, as well as natural selection

Final Technical Report on Radioxenon Event Analysis

This is a final deliverable report for the Advanced Spectral Analysis for Radioxenon project with a focus on radioxenon event categorization