[109478] in Cypherpunks
Re: About Alpha radiation...
daemon@ATHENA.MIT.EDU (Jean-Francois Avon)
Thu Mar 25 13:20:03 1999
From: "Jean-Francois Avon" <jf_avon@citenet.net>
To: "Tim Griffiths" <griffith@wis.weizmann.ac.il>
Cc: "Cypherpunks" <cypherpunks@toad.com>
Date: Thu, 25 Mar 1999 12:26:29 -0500
Reply-To: "Jean-Francois Avon" <jf_avon@citenet.net>
On Thu, 25 Mar 1999 09:55:03 +0200, Tim Griffiths wrote:
>Alpha's from radiative decay, yes. Alpha's from space can have energies
>at least two orders of magnitude higher. Don't forget as well that an
>Alpha doesn't need to penetrate to the conducting layer (2DEG) in a
>FET transistor to cause damage - charging effect by the secondary
>electrons are enough to stop it working.
>On the other hand, I agree with you that for a chip in a case, in a box,
>under a desk, in a room then it should be safe.
Well. I assume here that you mean "sea level alpha from space". Since, AFA my
books are stating, the typical free mean travel is in the order of 4 cm, two
order of magnitude would give 4 meters. Pit that against several kilometres of
nominal density 1 air and the alpha count would be pretty low... thus I conclude
that the two orders of magnitude energized alpha are observed at sea level.
Isn't it?
I have a table, which I will digitize, OCR and post. It is from Rasetti. Or
maybe I could look in my old CRC handbook... Will check it out.
>Tim May wrote:
So, Tim did not killfile me after all! :-)
Ciao CPunks!
jfa
