HPGe detector back to life after long sleep

Scintillation crystals, PMTs, voltage dividers etc...

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Joined: 22 Oct 2017, 04:36
Location: Hamburg

Re: HPGe detector back to life after long sleep

Post by Janni » 29 Dec 2019, 00:48

I would also not buy a used HPGe detector for thousands of Euros if I don't know the condition and I even haven't seen so many for sale on Ebay, at least not a complete one. Only separate parts like cables or NIM modules and even they were expensive. It was just a lucky chance for me to get this detector.

But still, even a vacuum problem I could solve. I work on the vacuum system of a particle accelerator, so vacuum related things are no problem for me :-)

A broken preamp could be maybe more complicated, but even that is maybe possible to find similar electronic parts and replace... I don`t know, I would just try but maybe I think too easy about it...

Regarding liquid nitrogen I have worked with it for years and it is just dangerous if you don't know what you are doing. If the dewar for example falls on the side and expands completely you have about 700 times the volume as gas. If that happens in a small room it would displace the air and you cannot breathe. The other thing is if you touch the liquid nitrogen too long, you get burned, like the same as if you touch something hot. So in any way gloves and safety glasses should be used. But if you even touch it for just a very short time with your skin nothing happens.

So it should be handled with care but if you just have the dewar upright, then only a very small amount evaporates all the time over the venting tubes. Even in a smaller room this is not a problem. Besides I use a device for measuring oxygen in the air if I handle with liquid nitrogen. If you are used to it handling is easy. At work we sometimes produce icecream with it :-)

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Re: HPGe detector back to life after long sleep

Post by sgt_bear » 30 Dec 2019, 08:44

There are quite a few on ebay, most based in US, which makes them even more difficult to get, since shipping will be 300+$. Also there is a working one for 4000$ from italy, the seller even offers to demonstrate the device and deliver it personally :) but 4k$ is alot.

Here is a quite extensive report on fixing a hpge https://carlwillis.wordpress.com/2011/0 ... -i-repair/
But yes, if you have availibility to vaccum devices its of course much easier than if you have to buy all the stuff too...

Okay, nice to hear about the Nitogen, i remember that some people in a different forum were going crazy, because the evoaporating Nitrogen from the devar would be deadly.... thats why i was a bit skeptic.
- Jonathan from Switzerland

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