[Murphy] Why does GURPS measure radiation sources in Rads anyway?

[lwcamp]

Originally Posted by callen

I went back and double-checked. I'm not so sure I was right to accept the lack of threat from roughly 3.5-MeV alpha particles. We need to remember that we're not talking about a few, nor even a few hundred, particles. We're talking about a beam. In my case, with fusion drives, it's quite a beam, too. I'm pretty sure even non-charged particles moving at those speeds, when placed into a beam, would cause serious problems. In the case of alpha particles, they interact strongly with their target, too, much more so than neutral particles do. So the alpha particle beam is actually probably fairly dangerous but shouldn't be treated as radiation damage by GURPS.

According to the National Institute of Standards and Technology, the penetration of 3.5 MeV alphas in A-150 tissue-equivalent plastic is 0.002 cm.
http://physics.nist.gov/cgi-bin/Star/ap_table.pl (divide range in g/cm^3 by density of about 1 g/cm^3 to get range in cm).
An intense beam could act like a blow-torch, but will not cause radiation damage to living cells (they would all be blocked by the layer of dead skin cells that makes up the epidermis).

As Anthony already said, the neutrons from fusion are worrisome and will cause whole body dose just like gammas. The natural protons from solar storms, planetary radiation belts, and galactic cosmic radiation are also at high enough energy they will cause whole body dose.

Luke

[Lord Carnifex]

Originally Posted by callen

So the alpha particle beam is actually probably fairly dangerous but shouldn't be treated as radiation damage by GURPS.

Agreed. This is a GURPS blaster, doing burn damage (with a [5] armor divisor and a surge side effect) rather than radiation damage. Ultra-Tech p. 123 for the technological version.