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Biomedical subjects

J F Ziegler

Publications and source records attributed to J F Ziegler.

3 recordsLinked to original sources

MIDN: a spacecraft microdosimeter mission.

MIDN (MIcroDosimetry iNstrument) is a payload on the MidSTAR-I spacecraft (Midshipman Space Technology Applications Research) under development at the United States Naval Academy. MIDN is a solid-state system being designed and constructed to measure microdosimetric spectra to determine radiation quality factors for space environments. Radiation is a critical threat to the health of astronauts and to the success of missions in low-Earth orbit and space exploration. The system will consist of three separate sensors, one external to the spacecraft, one internal and one embedded in polyethylene. Design goals are mass <3 kg and power <2 W. The MidSTAR-I mission in 2006 will provide an opportunity to evaluate a preliminary version of this system. Its low power and mass makes it useful for the International Space Station and manned and unmanned interplanetary missions as a real-time system to assess and alert astronauts to enhanced radiation environments.

Cosmic Radiation↗

Comments on ICRU report no. 49: stopping powers and ranges for protons and alpha particles.

The International Commission on Radiation Units and Measurements (ICRU) published Report No. 49, Stopping Powers and Ranges for Protons and Alpha Particles, in 1993. Since the report shows only limited comparisons to experimental data, this Commentary discusses limits on the accuracy of its tables. Some of the stopping tabulations appear to have unusual variations for high energies (>1 MeV/nucleon) of the order of 2-4%, while the lower energies have possible errors of 10-20% for those targets which were not fitted with new data.

Alpha Particles↗

Video display terminals and radon.

Recent reports indicate that video display terminals (VDTs) can collect radon progeny from the air. This occurs especially when they are turned off and may have negative electric fields which attract positively charged radioactive dust. We have studied this phenomenon in detail and evaluated various techniques for removing the gettered radioactivity while the video display terminal is both off and on. We have evaluated what happens when the video display terminal is switched, thereby reversing the electric field near the screen. We have also studied possible inhalation effects by a video display terminal operator during field reversal and find that although some radioactivity may be released during the cycle, room air currents redistribute it into the room with no detectable levels being inhaled by users.

Air Pollutants, Radioactive↗