Data compilation and evaluation of space shielding problems. Radiation hazards in space, volume III

Radiation hazards of interplanetary space and related shielding problem

Computer programs for shielding problems in manned space vehicles

Computer programs for shielding problems in manned space vehicles - proton penetration code

Results from the Palo Verde neutrino oscillation experiment

The ν̅e flux and spectrum have been measured at a distance of about 800 m from the reactors of the Palo Verde Nuclear Generating Station using a segmented Gd-loaded liquid scintillator detector. Correlated positron-neutron events from the reaction ν̅ep→e+n were recorded for a period of 200 d including 55 d with one of the three reactors off for refueling. Backgrounds were accounted for by making use of the reactor-on and reactor-off cycles, and also with a novel technique based on the difference between signal and background under reversal of the e+ and n portions of the events. A detailed description of the detector calibration, background subtraction, and data analysis is presented here. Results from the experiment show no evidence for neutrino oscillations. ν̅e→ν̅x oscillations were excluded at 90% C.L. for Δm2>1.12×10-3 eV2 for full mixing and sin22θ>0.21 for large Δm2. These results support the conclusion that the observed atmospheric neutrino oscillations do not involve νe

Beam asymmetry Sigma for pi(+) and pi(0) photoproduction on the proton for photon energies from 1.102 to 1.862 GeV

Beam asymmetries for the reactions gamma p -\u3e p pi(0) and gamma p -\u3e n pi(+) have been measured with the CEBAF Large Acceptance Spectrometer (CLAS) and a tagged, linearly polarized photon beam with energies from 1.102-1.862 GeV. A Fourier moment technique for extracting beam asymmetries from experimental data is described. The results reported here possess greater precision and finer energy resolution than previous measurements. Our data for both pion reactions appear to favor the SAID and Bonn-Gatchina scattering analyses over the older Mainz MAID predictions. After incorporating the present set of beam asymmetries into the world database, exploratory fits made with the SAID analysis indicate that the largest changes from previous fits are for properties of the Delta(1700)3/2(-) and Delta(1905) 5/2(+) states

An ALMA 3mm continuum census of Westerlund 1

Context. Massive stars play an important role in both cluster and galactic evolution and the rate at which they lose mass is a key driver of both their own evolution and their interaction with the environment up to and including their terminal SNe explosions. Young massive clusters provide an ideal opportunity to study a co-eval population of massive stars, where both their individual properties and the interaction with their environment can be studied in detail. Aims. We aim to study the constituent stars of the Galactic cluster Westerlund 1 in order to determine mass-loss rates for the diverse post-main sequence population of massive stars. Methods. To accomplish this we made 3mm continuum observations with the Atacama Large Millimetre/submillimetre Array. Results. We detected emission from 50 stars in Westerlund 1, comprising all 21 Wolf-Rayets within the field of view, plus eight cool and 21 OB super-/hypergiants. Emission nebulae were associated with a number of the cool hypergiants while, unexpectedly, a number of hot stars also appear spatially resolved. Conclusions. We were able to measure the mass-loss rates for a unique population of massive post-main sequence stars at every stage of evolution, confirming a significant increase as stars transitioned from OB supergiant to WR states via LBV and/or cool hypergiant phases. Fortuitously, the range of spectral types exhibited by the OB supergiants provides a critical test of radiatively-driven wind theory and in particular the reality of the bi-stability jump. The extreme mass-loss rate inferred for the interacting binary Wd1-9 in comparison to other cluster members confirmed the key role binarity plays in massive stellar evolution. The presence of compact nebulae around a number of OB and WR stars is unexpected; by analogy to the cool super-/hypergiants we attribute this to confinement and sculpting of the stellar wind via interaction with the intra-cluster medium/wind. Given the morphology of core collapse SNe depend on the nature of the pre-explosion circumstellar environment, if this hypothesis is correct then the properties of the explosion depend not just on the progenitor, but also the environment in which it is located

Analysis of lead levels in deciduous teeth from children in Clark County, Nevada.

Background: Elevated blood lead levels (EBLL) are declining in the United States, although some population subgroups continue to exhibit significant health disparities. A childhood lead poisoning prevention program was recently started in Nevada, and many efforts have been made to support this program and increase the screening rates. Methods: To expand the potential pool of children screened for EBLLs, a pilot study was performed to evaluate lead concentrations in extracted deciduous teeth using Graphic Furnace Atomic Absorption Spectrometry (GFAAS), Inductively Coupled Plasma Mass Spectrometry (ICP-MS), and X-Ray Fluorescence (XRF) analysis. Results: Lead concentrations as determined by GFAAS and ICP-MS were found to be within normal ranges (0.585 ppm ± 0.022) and were similar to previous studies. Hispanic patients exhibited higher lead levels (0.580 ppm ± 0.032) than Black (0.478 ppm ± 0.051) patients, and were significantly higher than White (0.275 ppm ± 0.035) patients (p \u3c 0.05). Analysis of a small number of matched saliva samples, however, found no evidence for acute lead poisoning. Although limited by a small initial sample size (n=22), this pilot study provides evidence that teeth can be effectively used to reveal lead exposure in pediatric dentistry patients