A benchmark for Monte Carlo simulations in gamma-ray spectrometry Part II: True coincidence summing correction factors.

The goal of this study is to provide a benchmark for the use of Monte Carlo simulation when applied to coincidence summing corrections. The examples are based on simple geometries: two types of germanium detectors and four kinds of sources, to mimic eight typical measurement conditions. The coincidence corrective factors are computed for four radionuclides. The exercise input files and calculation results with practical recommendations are made available for new users on a dedicated webpage.

A benchmark for Monte Carlo simulation in gamma-ray spectrometry.

Monte Carlo (MC) simulation is widely used in gamma-ray spectrometry, however, its implementation is not always easy and can provide erroneous results. The present action provides a benchmark for several MC software for selected cases. The examples are based on simple geometries, two types of germanium detectors and four kinds of sources, to mimic eight typical measurement conditions. The action outputs (input files and efficiency calculation results, including practical recommendations for new users) are made available on a dedicated webpage.

An intercomparison of Monte Carlo codes used in gamma-ray spectrometry.

In an intercomparison exercise, the Monte Carlo codes most commonly used in gamma-ray spectrometry today were compared with each other in order to gauge the differences between them in terms of typical applications. No reference was made to experimental data; instead, the aim was to confront the codes with each other, as they were applied to the calculation of full-energy-peak and total efficiencies. Surprising differences between the results of different codes were revealed.

Monte Carlo simulation of the response of a germanium detector for low-level spectrometry measurements using GEANT4.

In this paper, we will expose the work performed for the adaptation and refinement of the GEANT4 simulation toolkit (originally designed for Monte Carlo simulations in High-Energy Physics) in order to simulate Ge detectors in low-level gamma spectrometry. Special emphasis will be given to show and validate our own algorithms implemented in GEANT4 code for variance reduction and data analysis, that have been used for a quicker and precise efficiency calibration at different source-detector configurations of one of the low-level germanium gamma systems available in our laboratory.

Longitudinal trends and gender differences in physical fitness and lifestyle factors in career U.S. Navy personnel (1983-1994)

This study examines long-term health and physical readiness trends in the U.S. Navy. We mailed lifestyle questionnaires to all participants in baseline studies between 1983 and 1989 who were still on active duty in 1994. Commands provided body composition and physical readiness test scores for the participants. Two longitudinal cohorts were created: an 8-year sample (N = 640) with matched data from 1986, 1989, and 1994; and an 11-year sample (N = 1,576), with data from 1983 and 1994. Analyses of both cohorts revealed significant improvements in cardiovascular fitness, muscle strength, exercise, lean body mass, dietary habits, and sleep, as well as significant decreases in tobacco and alcohol use and job stress. However, hypertension rates, percentage of body fat, and body mass index increased over time. Women's scores were significantly better than men's on a number of factors. Overall, these findings suggest that the Navy's health promotion efforts have had a significant positive effect on the fitness and health behaviors of career Navy men and women.

Tobacco use and smoking policy perceptions onboard an aircraft carrier.

Prior to implementing a shipwide no-smoking policy, the crew of U.S.S. Theodore Roosevelt (CVN 71) participated in a voluntary survey on tobacco-related matters. The survey queried participants on their tobacco-use history, subjective exposure to environmental tobacco smoke (ETS), and attitudes related to smoking policy prior to the cessation of all smoking activities aboard ship. Of the 2,221 crewmembers who participated (74% response rate), 36% classified themselves as current cigarette smokers. Nonsmokers estimated their general exposure to ETS between "low" to "moderate." Of all participants, 57% were in favor of the current restricted smoking policy, including 18% of currently smoking personnel. Follow-up research is being conducted to assess the long-term impact of the no-smoking policy on changes in attitudes regarding policy, tobacco-use rates, and ETS exposure.