Discussion Overview
The discussion revolves around understanding the units of solar event flux, specifically focusing on the number of protons (or photons) striking a surface area during solar events. Participants explore the implications of the units #/(cm2 s sr) and how to apply them to a 1 m2 surface area facing the sun, including the concept of solid angles.
Discussion Character
- Technical explanation
- Debate/contested
- Conceptual clarification
Main Points Raised
- Some participants question whether the original inquiry was about protons or photons, suggesting a possible misunderstanding of the terminology.
- There is a discussion about the solid angle for a surface area facing the sun, with some suggesting that a whole sphere has a solid angle of 4π steradians.
- One participant proposes that the units of proton flux (#/(cm2 s sr)) are necessary for accurately describing the flux, while others speculate on the relationship between cm2 and steradians.
- Another participant mentions that to calculate the number of protons hitting a surface, one must multiply the flux by the area and the acceptance solid angle.
- Concerns are raised about the isotropy of incoming protons, with one participant suggesting that the quoted numbers may overestimate exposure for astronauts due to the assumption of half-space detection.
- There is a suggestion that for rough estimates, multiplying by a factor of three may be appropriate.
Areas of Agreement / Disagreement
Participants express uncertainty about the correct interpretation of the units and the nature of the particles involved (protons vs. photons). There is no consensus on the exact solid angle to use or the implications of the flux measurements for astronaut safety, indicating multiple competing views.
Contextual Notes
Participants note the potential for overestimation in exposure calculations due to the non-isotropic nature of proton flux, and there are unresolved questions regarding the definitions and applications of the units discussed.
Who May Find This Useful
This discussion may be useful for individuals interested in solar physics, space weather, astronaut safety, or those studying the implications of solar events on human activities in space.
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