Fusion Message Board

In this space, visitors are invited to post any comments, questions, or skeptical observations about Philo T. Farnsworth's contributions to the field of Nuclear Fusion research.

Subject: Re: Neutron Counter interface
Date: Oct 29, 1:23 am
Poster: Carl Willis

On Oct 29, 1:23 am, Carl Willis wrote:

>It is important that the mrem remain intact! Remember that for the rem dose rate meters there are classically 8 neuts/sqcm/sec at 1 mrem for 2.45mev. This is your key to you data! Counts on the device mean nothing per se.
>Richard Hull

Hi Richard,

I have a statement from Ludlums that the counter has roughly 30 cpm / mrem / hr., which directly relates counts to mrem (~1800 counts per mrem). And then as you point out, 1 mrem / hr implies a flux of about 8 neutrons /cm^2 /sec. All this seems to get me to a figure like 1 cpm = 16 neutrons per cm^2 per min. So as far as my reasoning can comprehend right now, I should in principle be able to use just a counts vs. time measurement to infer the flux (which is why I thought the meter adjustment didn't matter.)Certainly the thing has to give the right number of counts per millirem, and I will indeed have it properly calibrated.

Finally, here's a question for down the road a bit. What is the proper approach to finding the solid angle the detector occupies? (in order to calculate total fusor neutron yield) I have been thinking that the angle occupied by the BF3 tube itself is all that is needed. But perhaps there is significant scattering in the PE ball and a larger angle should be used. Any help would be appreciated!