Background radiation measurements at high power research reactors Ashenfelter, J.; Balantekin, B.; Baldenegro, C.X. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2016, Letnik:
806
Journal Article
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Research reactors host a wide range of activities that make use of the intense neutron fluxes generated at these facilities. Recent interest in performing measurements with relatively low event ...rates, e.g. reactor antineutrino detection, at these facilities necessitates a detailed understanding of background radiation fields. Both reactor-correlated and naturally occurring background sources are potentially important, even at levels well below those of importance for typical activities. Here we describe a comprehensive series of background assessments at three high-power research reactors, including γ-ray, neutron, and muon measurements. For each facility we describe the characteristics and identify the sources of the background fields encountered. The general understanding gained of background production mechanisms and their relationship to facility features will prove valuable for the planning of any sensitive measurement conducted therein.
Heavy neutrinos were sought in pion decays $\pi^+ \rightarrow \mu^+ \nu$ by
examining the observed muon energy spectrum for extra peaks in addition to the
expected peak for a massless neutrino. No ...evidence for heavy neutrinos was
observed. Upper limits were set on the neutrino mixing matrix $|U_{\mu i}|^2$
in the neutrino mass region of 15.7--33.8 MeV/c$^2$, improving on previous
results by an order of magnitude.
A search for additional evidence for the rare kaon decay K{sup +}{yields}{pi}{sup +}{nu}{nu} (bar sign) has been made with a new data set comparable in sensitivity to the previous exposure that ...produced a single event. No new events were found in the pion momentum region examined, 211<P<229 MeV/c . Including a reanalysis of the original data set, the backgrounds were estimated to contribute 0.08{+-}0.02 events. Based on one observed event, the new branching ratio is B(K{sup +}{yields}{pi}{sup +}{nu} {nu}(bar sign))=1.5{sup +3.4}{sub -1.2}x10{sup -10} . (c) 2000 The American Physical Society.
The improper disposal of unused drugs by flushing them down toilets or discarding them in household trash has emerged as an environmental threat, one with potential health-related consequences for ...animals and humans. Although studies documenting direct cause and effect are few, the potential for harm has been sufficient to galvanize action by a broad range of environmental, government, and health-related organizations. Here, Lauer et al discuss how to reduce the environmental impact and associated health threats of improper disposal of leftover drugs. Currently, there's no federal standard, policy, or program to guide collection and environmentally safe disposal of unused drugs. But coalitions of concerned citizens and professionals, including environmental groups, nurses, pharmacists, public health officials, and law enforcement agencies, have launched a variety of pilot projects to improve environmental protection. Community-based drug "take-back" programs represent one approach. These aim to decrease the amount and accessibility of unused medications in households and prevent them from ending up in the water supply.
We report the first measurement of a structure-dependent component in the decay K{sup +}{yields}{mu}{sup +}{nu}{sub {mu}} {gamma} . Using the kinematic region where the muon kinetic energy is greater ...than 137 MeV and the photon energy is greater than 90 MeV, we find that the absolute value of the sum of the vector and axial-vector form factors is |F{sub V}+F{sub A}|=0.165{+-}0.007{+-} 0.011 . This corresponds to a branching ratio of B(SD{sup +} )=(1.33{+-}0.12{+-}0.18)x10{sup -5} . We also set the limit -0.04<F{sub V}-F{sub A}<0.24 at 90% C.L. (c) 2000 The American Physical Society.
To describe the design, procedures, and cohort for the Better ASsessment of ILlness -(BASIL) study, which is conducted to develop and test new delirium severity measures, compare them with existing ...measures, and examine related clinical outcomes.
Prospective cohort study with 1 year follow-up of study participants at a large teaching hospital in Boston, Massachusetts. After brief cognitive testing and the Delirium Symptom Interview, delirium and delirium severity were rated daily in the hospital using the Confusion Assessment Method (CAM) and CAM-Severity score, the Delirium Rating Scale-Revised-98 (DRS-R-98), and the Memorial Delirium Assessment Scale (MDAS). Other key study variables included comorbidity, physical function (basic and instrumental activities of daily living ADL), ratings of subjective health and well-being, and clinical outcomes (length of stay, 30 day rehospitalization, nursing home admission, healthcare utilization). Follow-up interviews occurred at 1- and 12-month with patients and families. In 42 patient interviews, inter-rater reliability for key variables was assessed.
Of 768 eligible patients approached, 469 were screened and 352 enrolled, yielding an overall study response rate of 67% for potentially eligible participants. The mean participant was 80.3 years old (SD 6.8) and 203 (58%) were female. The majority of patients were medically complex with Charlson Comorbidity Scores ≥2 (192 patients, 55%), and 102 (29%) met criteria for dementia. Inter-rater reliability assessments (n = 42 pairs) were high for overall ratings of presence or absence of delirium by CAM (κ = 1.0), delirium severity by DRS-R-98 and MDAS (weighted kappa, κ = 1.0 for each) and for ADL impairment (κ = 1.0). For eligible participants at each time point, 278 out of 308 (90%) completed the 1-month follow-up and 132 out of 256 (53%) have completed the 12-month follow-up to date, which is still in progress. Among those who completed interviews, there was only 1-3% missing data on most major outcomes (delirium, basic ADL, and readmission).
The BASIL study presents an innovative effort to advance the conceptualization and measurement of delirium severity. Unique strengths include the diverse cohort with complete high quality data and longitudinal follow-up, along with detailed collection of multiple delirium measures daily during hospitalization.
Additional evidence for the rare kaon decay K+-->pi+nu(nu) has been found in a new data set with comparable sensitivity to the previously reported result. One new event was observed in the pion ...momentum region examined, 211<P<229 MeV/c, bringing the total for the combined data set to two. Including all data taken, the backgrounds were estimated to contribute 0.15+/-0.05 events. The branching ratio is B(K+-->pi+nu(nu)) = 1.57(+1.75)(-0.82)x10(-10).
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