[ RadSafe ] Californium vs. Americium

[Brennan, Mike (DOH)]

Hi, Franz.

Are you sure it isn't Pu-Be rather than Po-Be?  I am sure that one could use Po-210 and make a compact source with high output, but the 140 day half life means that you would have to use it quickly, before it decayed too much.  That doesn't sound too good for nuclear weapons, that usually are left inside their delivery systems for many years at a time.  Pu-238, on the other hand, has a really nice half life for doing all sorts of things where you want to balance specific activity and longevity.  

Though both Po-210 and Pu-238 are good from the point of view of not having screaming hot gammas, which I understand was the biggest problem with RaBe sources. 

-----Original Message-----
From: Franz Schönhofer [mailto:franz.schoenhofer at chello.at] 
Sent: Thursday, June 28, 2007 1:52 PM
To: Brennan, Mike (DOH); 'radsafe'
Subject: AW: [ RadSafe ] Californium vs. Americium

Mike (and others interested),

Far from being an expert on neutron sources I remember that Cf-252 is used as a single source of neutrons because of spontaneous fission - as you pointed out. I never heard that its alpha-particles were used to generate neutrons together with Be. 

Po/Be neutron-sources have been and are obviously still used in nuclear reactors and in nuclear bombs. 

The first neutron-sources were obviously Ra-Be mixtures. I doubt they are still used.

Using DU as a source for alpha-particles would - if it were possible - not reduce the quantity of DU stored significantly.....

Best regards,

Franz

Franz Schoenhofer, PhD
MinRat i.R.
Habicherg. 31/7
A-1160 Wien/Vienna
AUSTRIA


-----Ursprüngliche Nachricht-----
Von: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] Im Auftrag von Brennan, Mike (DOH)
Gesendet: Donnerstag, 28. Juni 2007 20:38
An: radsafe
Betreff: RE: [ RadSafe ] Californium vs. Americium

I admit to not knowing much about these kinds of neutron sources (in my program, if you wanted to expose something to neutrons you ran it into the reactor), but I was under the impression that the reason for using CF was the SF neutrons.  My source says that CF-252 decays via SF about 11% of the time.  I have no idea of what percentage of the alpha decays cause an "alpha + Be => n" reaction, but I suspect it is a function of the energy of the alpha and the abundance of Be atoms to encounter.

I realize there are non-trivial drawbacks, but it is a shame that they can't use some of the DU to make DUBE sources.  In addition to a cool name, you could calibrate your logging equipment once, and you'd be good
to go for your lifetime.