Problems of component discrimination in space radiation dosimetry

Area of Science:

• Space radiation physics
• Radiation dosimetry
• Astroparticle physics

Background:

• Environmental radiation in space presents unique challenges for dose equivalent assessment.
• Superposition effects complicate the resolution of the Linear Energy Transfer (LET) spectrum.
• Key contributors to the total dose equivalent include trapped protons, tissue disintegration stars, and neutrons.

Purpose of the Study:

• To address the difficulties in resolving the LET spectrum of space radiation.
• To improve the accuracy of dose equivalent assessments in space environments.
• To evaluate the impact of different radiation components on LET-resolution.

Main Methods:

• Analysis of radiation field components: trapped protons, tissue disintegration stars, and neutrons.
• Investigation of superposition effects on LET spectrum determination.
• Comparison of space neutron spectra with fission neutron spectra.
• Evaluation of conventional instrumentation limitations for LET-resolution.

Main Results:

• Tissue disintegration stars, particularly simultaneous bursts of low-energy particles, defy LET-resolution with current instruments.
• The neutron spectrum in space has a higher relative fluence above 5 MeV compared to fission neutrons.
• The LET spectrum of space neutrons centers less on values near the proton Bragg Peak, suggesting a Quality Factor (QF) less than 10.
• Significant shortcomings exist in LET interpretation for heavy primaries.

Conclusions:

• Conventional instrumentation is inadequate for fully resolving the LET spectrum of space radiation, especially from tissue disintegration stars.
• The unique neutron spectrum in space necessitates a re-evaluation of assigned Quality Factor values.
• Accurate dose equivalent assessment in space requires advancements in LET-resolution capabilities, particularly for heavy ions and complex particle events.