For Ed:

(taken almost verbatin from my highschool chemistry notebook that I still hang onto; although any spelling erros are probbly mine. . )
Alpha Radiation consists of helium nuclei emitted from a radioactive source
Characteristics:
-Charge: 2+
-Mass: 4amu
-low penetrating ability (1/10 speed of light )
-can be stopped by thin sheet of aluminum (appox 0.7mm) or several sheets of paper
-burns flesh (0.05mm living tissue but cannot penetrate dead skincells) & ionizes air easily

Beta Radiation consists of fast-moving electrons (called Beta particles) formed by the decomposition of an n0 which breaks into a p+and an e-.
Characteristics:
-charge: -1
-mass: 1/1837 amu
-penetrating ability = 10 x Alpha particle (aprox speed of light!)
-can be stopped by 1/8 inch thick Al foil
-will penetrate 4mm of living bone/tissue

Gamma Radiation high energy electromagnetic waves, often emited along with alpha and beta particles.
Characteristics
-charge: 0
-mass: 0
-penetrating ability: most penetrating of all three forms of radiation; travels at the speed of light!
-can be stopped by several inches of lead or several feet of concrete
-can pass completely through human body

For Mark:
With regard to cosmic rays, in the absence of a magnetosphere the best protection is to put mass between yourself and the incoming rays.

I agree, but since electromagnetic waves carry no charge, this holds true regardless of the status of the magnetosphere.

This is the basis for the living underground plans of dealing with this hazard. While a terraformed atmosphere would not provide the same level of protection from Solar flares and cosmic rays as Earth's Magnetospher,

again I am not sure that the magnetosphere woudl have anything to do with protection from cosmic rays.

I believe it would provide a significant improvement over an airless world. I'd appreciate some more exact numbers from any of the real experts who post here.

well I think I gave Ed some numbers above that may be helpfull, but they were form my notebook out of a public highschool chemistry class. . . and with public school hte way they are. . . caveat emptor.

-Justin Kelly