My Gamma Spectroscopy Setup

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.
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Jon Rosenstiel
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Real name: Jon Rosenstiel
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My Gamma Spectroscopy Setup

Post by Jon Rosenstiel » Fri Apr 13, 2018 11:22 pm

It may have been 60 some years ago but I remember it like it was yesterday. I was sitting at my workbench in the basement of my parents’ home on our family farm listening to faint clicks in my headphones. The Geiger counter I had just finished building actually worked! The faint clicks were the result of mysterious things going on inside of atoms and mysterious “rays” from outer space. I was hooked and had to know more.

Fast forward to the present with a tour of my spectroscopy lab. As one can see, I’m still hooked. (And maybe a little nuts too!)

Images…
First image: A brand new old stock Ortec GEM40P4 Poptop hpGe detector that showed up one day on eBay. Two days on the vacuum bench to refresh its vacuum and she was good to go.

Second image: Another shot of the detector.

Third image: On the left under the workbench. White box is an Ortec X-cooler. The X-cooler does away with the hassle of having to drive down to Airgas every couple of weeks to buy liquid nitrogen. The X-cooler is able to reach liquid nitrogen temperatures using a normal refrigeration compressor along with a secret-sauce mix of 5 different refrigerants. Black box is a UPS and the grey box is a power line conditioner.

Fourth image: A peek inside of the shield. 4-inches of lead with a cadmium & copper lining for x-ray suppression.

Fifth image: To the immediate right of the lead shield is a Spectrace 6000 X-ray fluorescence (XRF) spectrometer. It didn’t come with its computer interface so I hacked the electronics in order to manually control the x-ray tube’s current and voltage. (The unit contains an Oxford rhodium anode x-ray tube, max voltage is 50 kV, and max current is 350 ua)

The rack to the right of the Spectrace contains the electronics for the hpGe detector. (Two Canberra Series 35+ mca’s and two Canberra 2025 spectroscopy amplifiers along with an Ortec 449 ratemeter and an Ortec 459 bias supply)

The lower NIM bin contains a couple more Ortec counters, a Canberra 3102D HV supply, a beta spectrometer and an alpha spectrometer.
Anyway, all this cool stuff should allow me to kick up my neutron activation hobby up a notch or two. Stay tuned.

Jon Rosenstiel
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Richard Hull
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Re: My Gamma Spectroscopy Setup

Post by Richard Hull » Sat Apr 14, 2018 6:28 am

Jon,

You be da man! We have known for some years that you have perhaps the best personal gamma spec system of anyone here. The very castle you have appeared at our scrap yard about 4 years ago and They would let it go for the market price of the lead and they would deliver it. About the best anyone might ask for from a scrap yard.

I wanted it, but had no room for it and no way to effectively move it around in my lab. Add to that fact, I did not have a GeLi system which would make the nearly 1000 dollar castle investment worthwhile. Thus, I demurred.

I have always printed out your fusor.net posted results in the past and Bill Kolb has shared much of your Trinitite results with me.

Your laboratory quality results always speak not only of the quality of your gear, but the care and knowledge of their application.

I tend to limp along with my Canberra gamma spec and my 2", 3" and 5" Bicron PMT heads. Noise and background subtraction are the order of the day and any very faint stuff requires very long collection times and wind up as mere broad based pimples on the base line. Its main application now is in checking gamma signatures from fleeting activations and getting an accurate handle on uranium ore samples U content.

Again great setup and good output to tell the tale of whatever is under analysis in your lab.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

richnormand
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Re: My Gamma Spectroscopy Setup

Post by richnormand » Wed Apr 18, 2018 2:05 am

OK I have to admit drooling here....

One thing that kept me from an hpGe has been the need for LN2.
Can you comment on your Ortec X cooler reliability, availability for common mortals and price range (ie: don't want a second mortgage... or "if you have to ask...")?
Might it be useful for my Ge spectroscopy IR detector too...

Cheers Jon.

Jon Rosenstiel
Posts: 1343
Joined: Thu Jun 28, 2001 5:30 am
Real name: Jon Rosenstiel
Location: Southern California

Re: My Gamma Spectroscopy Setup

Post by Jon Rosenstiel » Thu Apr 19, 2018 4:59 pm

Richard,

Appreciate the kind words. My reasoning behind all of this is that if something goes haywire with my back (I ain't no spring chicken) I will still have some hobbies that I can play with despite not being able to easily get around. (Anyway, that's the plan)

Rich,

Yeah, it's pretty-much one of those "if you have to ask" deals. Ortec claims their X-cooler should be good for about 5-years. A brand new warranted unit runs about as much as a new compact car. Ortec sold me one of their demo units for a quarter of that. Considering what LN would cost me, I'll break even if this demo unit lasts two years.

Jon Rosenstiel

Jerry Biehler
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Re: My Gamma Spectroscopy Setup

Post by Jerry Biehler » Fri Apr 20, 2018 1:13 am

LN2 is not that bad. I use it for my EDX, I have a 25L dewar and it costs less than $20 to fill and if I am not using it lasts several weeks. I had a 50L and that thing would keep for quite a long time.

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Richard Hull
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Re: My Gamma Spectroscopy Setup

Post by Richard Hull » Fri Apr 20, 2018 4:55 am

In my area, LN2 is easy to get, (as long as you have a real dewar). It costs just a little less than cheap beer per liter. $2.25-$3.00 depending on price ups and downs. For demos of the meissner effect I have a little 10 liter dewar and run the demo about once a year. I have done it several times at the HEAS gathering here in October.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

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