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Hayes, J. C.

Publications and source records attributed to Hayes, J. C..

5 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Kiloton-scale xenon detectors for neutrinoless double beta decay and other new physics searches

We report that large detectors employing xenon are a leading technology in existing and planned searches for new physics, including searches for neutrinoless double beta decay (0νββ) and dark matter. While upcoming detectors will employ target masses of a ton or more, further extending gas- or liquid-phase Xe detectors to the kton scale would enable extremely sensitive next-generation searches for rare phenomena. The key challenge to extending this technology to detectors well beyond the ton scale is the acquisition of the Xe itself. We describe the motivation for extending Xe time-projection chambers to the kton scale and possible avenues for Xe acquisition that avoid existing supply chains. If acquisition of Xe in the required quantities is successful, kton-scale detectors of this type could enable a new generation of experiments, including searches for 0νββ at half-life sensitivities as long as 10 30 yr.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Migration of noble gas tracers at the site of an underground nuclear explosion at the Nevada National Security Site

As part of an underground gas migration study, two radioactive noble gases and two stable tracer gases were injected into a nuclear explosion test chimney and allowed to migrate naturally. Soil gas samples were collected from a series of boreholes and a range of depths from the shallow subsurface (3 meters) to deeper levels (~160 meters) over a period of eleven months. These samples have provided insights into the development and evolution of the subsurface plume and constrained the relative migration rates of the radioactive and stable gas species. Analysis of the samples concluded that the stable tracer SF6 was consistently enriched in the subsurface samples relative to the radiotracer 127Xe, but the ratios of SF6 and 37Ar remained similar throughout the samples.

Johnson, Christine M.↗
NASA NTRS2006

Current ISS Exercise Countermeasures: Where are we now?

Current International Space Station (ISS) crew schedules include 1.5 h/d for completion of resistive exercise and 1 h/d of aerobic exercise , 6 d/wk. While ISS post flight decrements in muscle strength, bone m ineral density, and aerobic capacity improved in some crewmembers, de conditioning was still evident even with this volume of exercise. Res ults from early ISS expeditions show maximum loss in bone mineral density of the lumbar spine and pelvis in excess of 1.5% per month, with all crewmembers demonstrating significant bone loss in one or more re gions. Similarly, post flight muscle strength losses in the hamstring and quadriceps muscle groups exceeded 30% in the immediate post miss ion period in some crewmembers. Measures of aerobic capacity early in the mission show average decrements of 15%, but with onboard aerobic exercise capability, the crew has been able to "train up" over the co urse of the mission. These findings are highly variable among crewmem bers and appear to be correlated with availability and reliability of the inflight resistive exercise device (RED), cycle ergometer, and t readmill. This suite of hardware was installed on ISS with limited op erational evaluation in groundbased test beds. As a result, onorbit hardware constraints have resulted in inadequate physical stimulus, d econditioning, and increased risk for compromised performance during intra and extravehicular activities. These issues indicate that the c urrent ISS Countermeasures System reliability or validity are not ade quate for extendedduration exploration missions. Learning Objective: A better understanding of the status of ISS exercise countermeasures , their ability to protect physiologic systems, and recommendations for exploration exercise countermeasures.

Hayes, J. C.↗
NASA NTRS1992

Program development for exercise countermeasures

The concern of NASA's Exercise Countermeasures Project (ECP) is to ensure crew physical effectiveness for flight- or mission-related tasks, and encompasses postflight as well as preflight and inflight exercise components. Attention is given to the implementation of ECP via the Space Shuttle Orbiter's treadmill, rower, cycle ergometer, and lower body negative pressure apparatus.

Hayes, J. C.↗