Search found 9 matches

by Neil.
14 Jul 2016, 12:36
Forum: Detector drivers
Topic: Limitation of Detectors
Replies: 6
Views: 3127

Re: Limitation of Detectors

Gerhard, It is good to find you participating on this forum and though your questions were directed to Steven I though I would add what I can. I have tried various sized NaI:Th crystals and have not found any association between size and resolution, in fact my smallest crystal tends toward lower res...
by Neil.
15 Apr 2016, 12:39
Forum: General discussion
Topic: Variation in Total CPM Over Time
Replies: 4
Views: 2575

Re: Variation in Total CPM Over Time

Update: I was able to reconstruct the time of day for the peaks and they occur between 11 AM and 1 PM local time. This would tend to rule out a "sunrise" hypothesis which relates morning temperature rise to radon being carried up from ground level according to a report I read, however this was done ...
by Neil.
13 Apr 2016, 04:49
Forum: General discussion
Topic: Variation in Total CPM Over Time
Replies: 4
Views: 2575

Variation in Total CPM Over Time

I have read some articles about diurnal cycling of background radiation and thought it would be interesting to look for this here. My portable scintillation unit measures CPM over 1 second intervals and reports this via a USB cable to the desktop PC. This count rate fluctuates quite a bit each secon...
by Neil.
07 Aug 2015, 04:53
Forum: Detectors
Topic: My spectrometry system
Replies: 7
Views: 4025

Re: My spectrometry system

Valentin, Very nice work and thank you for sharing. I also use a home built system including an A/D converter rather than a sound card and have noticed the slight compression as you mentioned at higher energy levels. Perhaps this is due to baseline shift after a strong pulse? It is not a problem sin...
by Neil.
22 May 2015, 01:44
Forum: Detector drivers
Topic: Software Defined Radio instead of sound card?
Replies: 4
Views: 3565

Re: Software Defined Radio instead of sound card?

This is an interesting idea but as was mentioned the use of a sound card and low pass filter is probably not a limitation to NaI system resolution. I have carefully observed the output of the PMT with a digital storage oscilloscope and have seen the variation in pulse amplitude around the voltage co...
by Neil.
17 May 2015, 04:09
Forum: Detectors
Topic: Info on some PMTs?
Replies: 10
Views: 5967

Re: Info on some PMTs?

Hi, Karl, The R374 was the first PMT I used for scintillation work. It was given to me years ago by a fellow ham operator. It was a service pull so it was used but it worked. Mine does not have the shield or frosted head end though. I use this with a 3/4 x 3/4 inch crystal for portable counting. Whe...
by Neil.
29 Apr 2015, 10:42
Forum: Introductions
Topic: Hello on New Forum
Replies: 4
Views: 2252

Re: Hello on New Forum

Greetings Karl,

Not a problem about the period, in fact, it makes my user name a bit distinctive.

Neil
by Neil.
28 Apr 2015, 17:33
Forum: Introductions
Topic: Hello on New Forum
Replies: 4
Views: 2252

Re: Hello on New Forum

Steven, Just playing with you a bit about the name :) All I had to do was add an inconspicuous period at the end. Maybe Karl will want to do likewise. Everyone can just assume it is a speck on their screen. Anyway, I am sure this will relieve you of much grief and life will be better. I moderate on ...
by Neil.
28 Apr 2015, 12:51
Forum: Introductions
Topic: Hello on New Forum
Replies: 4
Views: 2252

Hello on New Forum

Am a transplant from the old forum. Had to change my user name because of 5 to 20 char limit. Arrrggghh.

Hope the transition goes well for everyone.

Neil