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 Q's
Date: Oct 25, 1:29 pm
Poster: Richard Hull

On Oct 25, 1:29 pm, Richard Hull wrote:

>This is a real interesting point- to let the thing stabilize, and I'm glad you mentioned it. When we turned it on, it would chirp several times per minute and then seem to stop after a couple minutes with only a sporadic chirp. I thought we had a cable problem, and I put in another (rather shabby built-on-the-spot) test cable, during which it kept up doing a count every twenty sec's or so. But this might just have been noise. The original cable is fine in fact, and in putting it back we see a chirp every couple min, AFTER waiting about five minutes. I'll run the chirper output to a LabView interfaced meter to get data, and I'll probably start keeping backgroud counts right now so I get familiar with daily cycles, normal patterns, whatnot. Tx for the help! -Carl


Sounds like you are off to th' races there now. Yes, the factory cable is always the best. Regular, new coax can actually be noisier than the original which is often of special manufacture and selected to reduce triboelectric effects and is often double shielded.

Background count, locally, and familiarization with it is most important to the neutron metrologist working in the scud. (like we are) I have noted a definite diurnal effect (reasonable) amongst my long term background checks. I have only been reading this over about a three year span and this is around a solar maximum. I would imagine this effect might soften or disappear during certain periods of a minimum solar cycle.

Most neutron measurements around reactors, accelerators and the like are way above background and its significance falls off to a virtual non-issue for most health physicists.

You'll have lots of illuminations over the next year or so as you fiddle with the neutron measurment end of things. It is, of course, important to get a handle on this black art so that we do not deceive ourselves (or others) and can report viable and accurate data.

Unlike a lot of stastics drive experimentalists, I like a minimum or 100% clearance on the noise floor. (example) 1cpm normalized background demands 2 cpm output reading before I start getting excited and believe it is due to my fusor fusing away.

Richard Hull