Search found 174 matches

by iRad
08 Apr 2022, 04:59
Forum: Detectors
Topic: Plateau and Efficiency of a 44-2
Replies: 6
Views: 116

Re: Plateau and Efficiency of a 44-2

Oh, I see that all the time... Bad crystal. Used Ludlum 44-2 are often found with bad 1X1 crystals, and one way to quickly diagnose is to see the response to a low energy source like Am241. With a good crystal (and good PMT), you should have gotten plenty of counts at less than 800 volts using an Am...
by iRad
04 Apr 2022, 08:14
Forum: Spectrum
Topic: Odd radtioactivity from US-based organic soybeans
Replies: 8
Views: 200

Re: Odd radtioactivity from US-based organic soybeans

Chris - Please check out your "Private messages" from me and contact me at my email address. Thanks, Tom
by iRad
23 Feb 2022, 09:25
Forum: Spectrum
Topic: PMT give light !
Replies: 6
Views: 230

Re: PMT give light !

Peter - I've actually never seen that happen and have soldered directly to the pins of thousands of PMTs. Perhaps it is possible by using excessive heat and/or poor soldering technique, or excessive stressing of the pins with certain especially fragile PMTs, but it is not something to usually worry ...
by iRad
19 Jan 2022, 09:00
Forum: Spectrum
Topic: PMT give light !
Replies: 6
Views: 230

Re: PMT gives light !

Cool effect indeed, but I'm guessing only finding 2 such samples over your many years is a good thing in this instance. :)
by iRad
26 Nov 2021, 03:11
Forum: Detectors
Topic: Request for advice about PMT for bespoke crystal
Replies: 8
Views: 178

Re: Request for advice about PMT for bespoke crystal

Your first question... Just based on what I can see, and without an available datasheet, I'd guess probably not. 2nd question... I'm guessing the coax with the BNC is signal out, and the leads terminating in the green connector are HV. This scheme "might" be compatible with the GS-USB-PRO ...
by iRad
02 Nov 2021, 04:01
Forum: Detectors
Topic: Newly built GS detector with Hamamatsu R6233 PMT
Replies: 5
Views: 268

Re: Newly built GS detector with Hamamatsu R6233 PMT

Andrey - This is one of the nicest and most useful projects for field detecting I've seen recently. You and Charles have done an excellent job with its design and construction. I really like the idea of variable tones combined with a squelch control. FANTASTIC!
by iRad
23 Sep 2021, 04:50
Forum: Detectors
Topic: Newly built GS detector with Hamamatsu R6233 PMT
Replies: 5
Views: 268

Re: Newly built GS detector with Hamamatsu R6233 PMT

Hi Andrey -
Nicely documented build, and very nice results. The larger detector is a nice addition to your stable.
by iRad
22 Sep 2021, 08:35
Forum: Detectors
Topic: How difficult is it to detect K40 using LaBr3(Ce)?
Replies: 13
Views: 358

Re: How difficult is it to detect K40 using LaBr3(Ce)?

Here is LaBr3 2X2 detector with background in grey and 5 pounds of Kitty Litter in Green.
by iRad
22 Sep 2021, 08:31
Forum: Detectors
Topic: How difficult is it to detect K40 using LaBr3(Ce)?
Replies: 13
Views: 358

Re: How difficult is it to detect K40 using LaBr3(Ce)?

It's still possible to pick out the Cs134 peaks from Fukushima with LaBr3...
by iRad
26 Aug 2021, 00:48
Forum: Detectors
Topic: Purpose of optical coupling gel
Replies: 12
Views: 458

Re: Purpose of optical coupling gel

Hi Tim, and welcome to the group Of course, I’m sure you know light needs to travel from the crystal to the PMT. To get there, it must pass through several surfaces. Usually on the crystal there is a glass window, then there is an air gap between the glass window of the crystal and the glass window ...