"Charles Angelich" wrote to "Scott Little" (11 Feb 03  19:29:08)
 --- on the topic of "Columbia's 'computers'"

 CA> I was thinking
 CA> that Gamma particles in space could be hitting the CPU and too
 CA> thin/small a trace within the PNP of the chip itself could be
 CA> literally disconnected while the larger trace used on older
 CA> designs could withstand multiple strikes?

The problem of radiation has two main effects. One is called a soft
failure in which an event switches a bit state, the other is a hard
failure where a state becomes permanent. In both cases, electrons
displaced by the gamma ray ionisation cause a discharge event though the
material, like a lightning bolt. Charges are moved about and/or some of
the material becomes damaged (i.e. silicon into charcoal). The damage
accumulates over time until the circuit component such as a memory cell
or logic gate fails. BTW circuit traces will withstand much more damage
before they stop conducting. You can experiment this effect using an
1N4001 diode and a gamma source. The diode will exhibit an EMF when
subjected to the radiation but this EMF will gradually decrease as the
diode material becomes damaged. BTW be sure to observe proper nuclear
safety handling procedures! 

 Mike
 ****

... Beware of programmers carrying screwdrivers!
--- Blue Wave/DOS v2.30