At 02:16 PM 8/14/97 -0400, you wrote:
>At 08:07 AM 8/14/97 -0500, you wrote:
>
>>  I would guess that a source that gave off
>>gamma's at about the same energy level as the UV light would work fine.
>
>Eh ? You can't have a gamma anywhere near the energy of UV as far as I
>know its impossible.

That may be true I havent looked it up in my old Nuclear Physics books.

>The gamma is higher frequency electromagnetic
>radiation than UV and would likely go straight through the cell with
>out ionising it - ie dislodging the charge.

There is allways a probability of interaction depending on the matter that
the gamma passes through (i.e. lead has a higher probability than
aluminum).  If this were not true, why would we need shielding arround
nuclear reactors for gamma radiation?  Also how could we measure the
levels?  To get the required flux to dislodge the charge, you would need to
increase the incident flux (higher dose), or increase the time (higher dose).

>
>Remember energy level and frequency are not separable when it comes
>to electromagnetic radiation

Gammas are not electromagnetic in the normal fasion.  There is a wide
energy band of gammas that differ in energy (and frequency) depending on
the isotope that generated them.

>- be careful - there is no safe dose
>of Gamma OR UV for that matter

Sure there is according to the US 10CFR20 regulations from DOE.  Dose is
something like 5 REM (radiation equivalent to man) per year for adults over
18 years of age (the formula is a little more complex).  BTW that is above
background, you allready get some exposure just from naturally occuring
radioactive decay, and from outerspace.

>- but you can sit in front of a bar
>heater for as long as you like ;)
>

I agree wholeheartely!

>>Wonder what kind of shielding the package adds?
>
>At Gamma frequencies - NONE - ZERO - ZILTCH.
>

Well, everything does a little.  Polyethelye does offer some sheilding.  I
belive ceramic IC packages offer more than plastic packages (that's why we
uses them in radiation hardened products).

Enough nuclear physics, lets get back to PIC's.

Norm