RE: electronics hormesis ??

["Minnema, Douglas" <Douglas.Minnema@nnsa.doe.gov>]

Jaro and all,

 

Sorry it took some time to respond, but I wanted to add my two cents worth

here.  The research reactor I used to work at was used for both the testing

and production of radiation-hardened electronics for weapons and space

applications.  As I recall, modern electronics are quite susceptible to

radiation damage from both gamma and high energy particles and neutrons.

This is mainly due to the very small sizes and the very small thicknesses of

the conducting and insulating regions of the device.  It is not unusual for

a single interaction to cause a circuit failure.

 

As I recall, one of the experimenters gave us a presentation on this

phenonemon that indicated that damage was quite directly proportional to

dose, similar to the LNT concept.  The only saving grace for the electronics

industry was that the failure rate in our ambient environment was low enough

to be economically acceptable (ever wonder why that IC chip in your computer

failed for no reason ?-).  I do believe that they attempt to select

materials for low intrinsic radiation levels.

 

On the other hand, it was also interesting that the process for producing

radiation-hardened electronics included exposure to specific levels of

neutron and/or gamma radiation levels.  Our reactor was one of the

facilities used for this purpose also.  (Sorry, I don't recall the mechanism

by which this worked.)  In fact, I think that we may have done some of the

parts for the Galileo satellite.  Therefore, one could argue a hormesis

analogue.

 

Finally, there was also the annealing process mentioned below that

represented a damage repair mechanism.  What is unusual in the Galileo case

is that they can actually watch the repair process at work in a real

situation, where it was normally a laboratory experiment.

 

Doug Minnema, Ph.D., CHP

National Nuclear Security Administration, US DOE

mailto:Douglas.Minnema@nnsa.doe.gov <mailto:Douglas.Minnema@nnsa.doe.gov> 

 

what few thoughts i have are truly my own ...



-----Original Message-----

From: Franta, Jaroslav [mailto:frantaj@AECL.CA]





>From the Galileo spacecraft mailing list......







Jaro



<SNIP>



The electronics associated with the gyros have shown significant degradation

over the years of exposure to the harsh radiation environment near Jupiter.

However, when the spacecraft spends time farther away from Jupiter, the

electronics have shown some tendency to heal themselves somewhat from these

radiation effects, or anneal. This test will provide engineers with data

about how much self-healing takes place after 2-1/2 months far from the

radiation damage.



<SNIP>









************************************************************************

You are currently subscribed to the Radsafe mailing list. To unsubscribe,

send an e-mail to Majordomo@list.vanderbilt.edu  Put the text "unsubscribe

radsafe" (no quote marks) in the body of the e-mail, with no subject line.

You can view the Radsafe archives at http://www.vanderbilt.edu/radsafe/