Killer deal on a GeLi gamma spec

Current images of fusor efforts, components, etc. Try to continuously update from your name, a current photo using edit function. Title post with your name once only. Change image and text as needed. See first posting for details.
Post Reply
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Killer deal on a GeLi gamma spec

Post by Richard Hull »

Attached are images of a Princeton Gamma Tech intrinsic Germanium, gamma spec system I acquired at an unbelievably great price.

Model # IGC2020

No claim of working, but I figure the $2000 worth of Germanium in it and the PGT killer neutron detection ready pre-amp along with the large dewar are worth the price I paid even if it is a bust as a gamma spec.

After a bit of reading, Intrinsic Germanium detectors are GeLi types and upon warming are no good any more. HPGE can be warmed and then re-cooled. So I might just have the Germanium a preamp and a dewar.

Richard Hull
Attachments
HPGE (7).JPG
HPGE (3).JPG
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
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
John Futter
Posts: 1848
Joined: Wed Apr 21, 2004 10:29 pm
Real name: John Futter
Contact:

Re: Killer deal on a GeLi gamma spec

Post by John Futter »

you could try redrifting the GeLi crystal to get it to work again
But I think you will wane on keeping it cool
so good dewar and electronics
Jerry Biehler
Posts: 975
Joined: Tue Nov 24, 2009 3:08 am
Real name:
Location: Beaverton, OR

Re: Killer deal on a GeLi gamma spec

Post by Jerry Biehler »

Usually GeLi sensors are fine being warmed up, they are used in EDX as well on SEMs and TEMs. The issue is the beryllium window. If the dewar has been cold for years they tend to build up condensed vapors inside the dewar insulation since they are basically a cryopump. When the dewar heats up the pressure builds past atmospheric and the window can be blown out. If you have to warm one up you need to make sure the power is off and be pumping down the dewar through the pump-down connection while it is warming to keep the dewar at a vacuum. I only keep my EDX cold when I need to use it.

Im willing to be that as long as the window is intact the sensor will be fine. Main thing to keep in mind is never apply bias voltage to a warm sensor, it will fry it.
User avatar
Jim Kovalchick
Posts: 717
Joined: Wed Apr 13, 2011 8:00 pm
Real name:

Re: Killer deal on a GeLi gamma spec

Post by Jim Kovalchick »

I'm not sure why you believe that intrinsic germanium detectors are inherently GeLi. High purity germanium detectors which do not drift and can be warmed are intrinsic. Looking at the vintage of your detector, I would say you have a chance that it could work if cooled.

As near as I can tell, your detector is a coaxial p HPGE with 20 to 25% efficiency and FWHM of 0.9 keV at 122 keV and 1.92 at 1332 keV. Unless it has been fried by mishandling in the past, you should be able to chill it with ln2 for 6 hours and fire it up to the voltage on the tag.
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Killer deal on a GeLi gamma spec

Post by Richard Hull »

Too Late! I scraped it out for components. I now have a nice dewar for sale and a killer Canberra charge sensitive amp that I will never sell as it is identical to the one I use with my 3He neutron detector. I also have a 504 gram germanium crystal in hand. Yesterdays asking price for a a 1kg ingot of 99.999 purity ingot of Ge was $2300.00. My crystal is much more pure than that. So, I have ~$1150.00 worth of Ge for my element petting zoo.
I got my $30.00 purchase price back on this deal.

As I was poking about in the metals market I was stunned to see what my Hafnium stock is worth. Way back in the late 80's and throughout the 90's I bought large amounts of various rare metals in the form of scrap wire, sheet, foil, rod and bar stock from a local firm that formed the raw rare metals into those different forms and sold to Aldrich, Alpha Aesar, Goodfellows, IBM, Smith Corona, HP, Boeing and others. Among the metals I bought were Tungsten, Indium, Zirconium, Tantalum, Hafnium, Niobium/Columbium, Magnesium, electrolytic O.F. copper, hyper pure Aluminum, Sodium, etc.

It turns out that they sold their scrap back to the raw metals sellers that supplied them. Due to the tremendous loses and expenses incurred in taking their scrap and turning it back into bulk metals again, they often got only 10-20% of what they paid back for their scrap. In the case of Magnesium and Tungsten the manufacturers would take the scrap back but would pay nothing for it, at that time. So I got those scraps for free.

Back then they paid about $150 per lb for Hafnium rod stock which they turned into wire, foil, sheet and smaller rod stock. They sold their scrap Hf to me for $21.00/lb if in the form of rod, block or plate, according to my notes taken back then. Needless to say, I would only take useful scrap, like wire, foil, sheet and rod stock of all the metal scraps I purchased from them. Hafnium was no exception. I have about 20kg of various forms of Hf here and the current market price, as of Yesterday for 1" diameter rod stock containing 0.2% tramp Zirconium was $1780.00/kg.

Finally the worst scrap that often paid only 5% back from the bulk metal sellers was foil and wire which tended to vaporize in any remelt effort. Hf foil and wire was sold to me at $7.00/lb back then. This, as it turned out, was the most useful form for me! For your amusement, check out the prices of these wire and foils. The normal fabrication charges chase the commercial mass price of the finished product up by 1000 to 10,000%!!!

Wow!

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
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Jerry Biehler
Posts: 975
Joined: Tue Nov 24, 2009 3:08 am
Real name:
Location: Beaverton, OR

Re: Killer deal on a GeLi gamma spec

Post by Jerry Biehler »

FWIW, Hf is used in plasma cutter tips, its that little silver piece in the center of the electrode, it melts and helps stabilize the arc.
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Killer deal on a GeLi gamma spec

Post by Richard Hull »

I had to do this once before....Transfer the front end FET in the cold finger along with a couple of components back into the charge sensitive preamp case. This was fairly easy, but I did have to manufacture a new end for the preamp out of 1/8' Aluminum sheet stock as the one on the vacuum end was curved to fit the preamp to the round cold finger housing. I tested the preamp, but wisely tested the 4 power busses first. I found three bad Tantalum filters and replaced them plus two more that tested good as they were very old and probably dried out. The preamp tested perfectly, and is ready for another 3He tube system. I used a stock BNC on the tube end as the bias for most 3He tubes are well under 1800 volts. The normal connector would have been a SHV BNC to allow the preamp to be used up to over 3kv bias.

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
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Post Reply

Return to “Images du Jour”