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 detection, 5 (Multiple detectors?)
Date: Oct 06, 2:33 am
Poster: Dave Cooper

On Oct 06, 2:33 am, Dave Cooper wrote:

>>On PMT's and large screens.... You might find a simple large diameter lens would be a pretty efficient means ot couple a small PMT to the larger screen. The only issue might be if there is a significant amount of UV in the screen's output. Then the lens would seriously attenuate unless it were quartz.
>What about reflective losses off the lens surfaces?
Reflective losses could be significant if an uncoated multi-element lens were used. For a simple plano or bi-convex lens... you would heave about 4% reflectivity at each air glass surface, unless AR coatings are used. They should lower losses to about 1% per surface.
>Of course, for neutron counting, we aren't really looking at pulse height, just that there IS a pulse at all, above a certain threshold, so you might not care that the gains aren't the same.
Good point!! You only need enough gain to get a pulse. Thanks.

Dave Cooper