title: Compact Tissue-equivalent Proportional Counter for Deep Space Human Missions.
abstract: Effects on human health from the complex radiation environment in deep space have not been measured and can only be simulated here on Earth using experimental systems and beams of radiations produced by accelerators, usually one beam at a time. This makes it particularly important to develop instruments that can be used on deep-space missions to measure quantities that are known to be relatable to the biological effectiveness of space radiation. Tissue-equivalent proportional counters (TEPCs) are such instruments. Unfortunately, present TEPCs are too large and power intensive to be used beyond low Earth orbit (LEO). Here, the authors describe a prototype of a compact TEPC designed for deep space applications with the capability to detect both ambient galactic cosmic rays and intense solar particle event radiation. The device employs an approach that permits real-time determination of yD (and thus quality factor) using a single detector. This was accomplished by assigning sequential sampling intervals as detectors “1” and “2” and requiring the intervals to be brief compared to the change in dose rate. Tests with g rays show that the prototype instrument maintains linear response over the wide dose-rate range expected in space with an accuracy of better than 5% for dose rates above 3 mGy h(-1). Measurements of yD for 200 MeV n(-1) carbon ions were better than 10%. Limited tests with fission spectrum neutrons show absorbed dose-rate accuracy better than 15%.
authors: *NASA Ames Research Center, Moffett Field, CA 94035; †Texas A&M University, College Station, TX 77843; ‡Colorado State University, Ft. Collins, CO 80523.
authors: T
authors: T
authors: Straume
authors: L A
authors: LA
authors: Braby
authors: T B
authors: TB
authors: Borak
authors: T
authors: T
authors: Lusby
authors: D W
authors: DW
authors: Warner
authors: D
authors: D
authors: Perez-Nunez
mesh_terms: D018480:Astronauts; D032701:Biomimetics / Q000295:instrumentation*; D003359:Cosmic Radiation; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005118:Extraterrestrial Environment / Q000737:chemistry*; D006801:Humans; D008904:Miniaturization; D016273:Occupational Exposure; D011829:Radiation Dosage; D011835:Radiation Protection / Q000295:instrumentation*; D013026:Space Flight / Q000295:instrumentation*; D014915:Whole-Body Counting / Q000295:instrumentation*