Brown, Lead Underpants Moments?
normally avoid a headline like that, but Rajan Bedi, author of this
short story on proton radiation susceptibility testing, really seems
to like the term since it is used repeatedly throughout. It is funny
and conjures up a number of less-than-flattering images. We are accustomed
to reading about testing with electromagnetic beams
(cosmic rays, x-rays, microwaves, mm-waves, etc.)
and electron beams (beta rays), but proton
beams (alpha rays) are mostly an unfamiliar
entity. Most of us can tell you how to create the former, but how about
creating the latter, and why is there a need to test for susceptibility
to them? How do you shield against alpha rays? Fast-moving protons,
being large and heavy, can dislodge atoms from semiconductor lattices,
potentially affecting a circuit. Proton beams are generated using nuclear
accelerators. Spaceborne platforms are particularly vulnerable. The
test setup described used thick, paraffin-impregnated blocks, which
I always thought were used for blocking neutrons, not protons, so maybe
that is the secondary radiation mentioned. If the proton source is anything
other than a hydrogen atom (not deuterium or tritium),
then it probably has a neutron or two attached to it.
Brown, lead underpants, though, will stop the protons.
Posted March 2013