CZT Detector help

Scintillation crystals, PMTs, voltage dividers etc...
Post Reply
User avatar
sgt_bear
Posts: 71
Joined: 16 Jan 2017, 07:06
Contact:

CZT Detector help

Post by sgt_bear » 11 Nov 2018, 23:15

Hello folks,

I recently purchased a CZT detector from ebay. Its marked
"EV products, B1829 - Division of II-VI Incorporated"

I only found this data about it
https://www.kephis.com/kephis/czt.htm

Providing schematic and details, but no information about the "HV" voltage that needs to applied. Various sites have values for CZT from 30 up to 1kV but i'm not in the mood to damage my detector by just apply any voltage to it...

Has anyone here ever seen this detector or knows what voltage to apply ?
- Jonathan from Switzerland

miree
Posts: 19
Joined: 23 Apr 2017, 00:04
Contact:

Re: CZT Detector help

Post by miree » 12 Nov 2018, 04:13

Hello

I have a similar detector from the same source since quite a while but never got the time to build a readout for it. So I never recorded a spectrum (still on my to do list though). But I tested it starting at 0V and increased voltage until I saw pulses. They started coming at around 90V. I believe that in order to get the full resolution the voltage should be higher. But I would want to see a spectrum first, and then play around with the HV to optimize resolution.
In general I believe these detectors are similar to HPGe in that the HV should ramp up slowly.

Best regards
Michael
Michael Reese
Darmstadt Germany

luuk
Posts: 189
Joined: 01 May 2015, 21:00
Location: the Netherlands
Contact:

Re: CZT Detector help

Post by luuk » 12 Nov 2018, 06:57

Hi Jonathan,

These detectors will work already around 60 V, best is to connect the output to an oscilloscope and watch the pulses coming out if you raise the voltage to high you can see the noise getting stronger.
So that gives you a good indication that you are at the breaking voltage of the crystal try an as low as possible voltage, so the noise stay is low as possible.
Detection with these detectors is interesting but if you connect it to an mca you will see a relative long tail on the peaks but that is just the way they works.
You can have a nice resolution special with lower energies because the crystal is relative small.

Luuk

User avatar
Steven Sesselmann
Posts: 613
Joined: 27 Apr 2015, 11:40
Location: Sydney
Contact:

Re: CZT Detector help

Post by Steven Sesselmann » 12 Nov 2018, 18:22

Jonathan,

There have been quite a few of those eV-CZT detector floating around on eBay, several years ago i recorded this spectrum with one.

https://www.gammaspectacular.com/image/ ... 3Ba(2).jpg

Luuk is in the ballpark, I recall running these at around 70V using the GS-1100A with a simple 10:1 voltage divider. The only problem with those detectors is that they are microphonic, so they pick up any sound in the room. providing the frequency of the sound is low, PRA corrects for the baseline shift, but it's a problem you might run into.

Steven
Steven Sesselmann | Sydney | Australia | gammaspectacular.com | groundpotential.org | rephopper.com | beejewel.com.au |

Post Reply

Who is online

Users browsing this forum: No registered users and 1 guest