Light, Magnetic, and Electrostatic Shielding of the PMT Enclosure.

This area is for discussions involving any fusion related radiation metrology issues. Neutrons are the key signature of fusion, but other radiations are of interest to the amateur fusioneer as well.
Post Reply
teslapark
Posts: 49
Joined: Sat Jun 30, 2001 5:20 am
Real name:
Contact:

Light, Magnetic, and Electrostatic Shielding of the PMT Enclosure.

Post by teslapark »

I'm just getting ready to deposit my scintillator in an enclosure, and I was wondering if anyone had any tips on shielding it properly.

For the electrostatic I have the PMT wrapped in aluminum foil, which is grounded to the steel enclosure (which in turn is earth grounded).
I don't plan on using any mu metal, but as I understand, as long as the enclosure material is magnetic (i.e. steel), you are ok if you keep at least a 1" gap between the PMT and the walls of the enclosure.
Keeping the enclosure light tight seems simple enough. I've thought about using duct seal or some other dark putty around the electrical ports but any suggestions from experience would be appreciated.

That's about it. I am planning on using one of those gallon paint cans for my enclosure. I assume that any metal enlosure will knock out background alphas and betas.

Hopefully this discussion will help make a guide for anyone who wants to build a PMT detector without spending a lot of money or buying special materials.

Adam Parker
Richard Hester
Posts: 1519
Joined: Thu Jul 05, 2001 12:07 am
Real name:

Re: Light, Magnetic, and Electrostatic Shielding of the PMT Enclosure.

Post by Richard Hester »

A paint can might serve for magnetic shielding, but you might want to degauss it in case it has been magnitized, or at least check it. Very small magnetic fields will really desensitize a PMT. If you have a 2" PMT, Don Orie will sell you a mu-metal shield for a very reasonable price.
For electrostatic shielding, I use pressure sensitive copper tape. I wrap the tube and attached scintillator with the tape, then solder a wire down the length of the tube to ensure all the tape spirals are connected together. I then solder a wire directly between the tape and the photocathode connection, which is where it should be connected.
A paint can is tin coated, so you can actually solder your connectors into the lid, which will take care of light shielding.
The enclosure will probably take care of most betas, but most gammas will whizz right through.
Post Reply

Return to “Neutrons, Radiation, and Detection (& FAQs)”