CdTe Detector

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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wayne
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CdTe Detector

Post by wayne » Sat Sep 02, 2006 4:58 pm

Has anyone built a CdTe detector?

wayne

John Futter
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Re: CdTe Detector

Post by John Futter » Tue Sep 05, 2006 8:34 pm

I have built both CdTe and CZT detectors with integrated pulse amp / disc using 10mm square detectors x 2 to give 10x 20 mm detector area.
Cdte need cooling to reduce noise this can be done using peltier blocks to get -30 degrees C.
Both these forms of detectors are noisy with in our case 66keV gammas being 4 x pulse height of the noise.
Products that we make Onfarm wool scan and Portacat use these detectors www.isoscan.com
Detector bias is in the range of 100 - 300 volts
Wayne Rodgers wrote:
> Has anyone built a CdTe detector?
>
> wayne

wayne
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Joined: Mon Apr 10, 2006 7:45 pm
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Re: CdTe Detector

Post by wayne » Wed Sep 06, 2006 12:58 am

John,

So this puts the noise at about 15KV.
Do you think it is in the material,contacts, or the amp.?
By the way, what do you guys use for the source?

wayne

John Futter
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Re: CdTe Detector

Post by John Futter » Wed Sep 06, 2006 6:38 am

Wayne
Not sure if the problem with noise is the contacts or the detector itself. But different detector pairs show very different noise levels.The amp on its own has about 500eV noise when terminated with a capacitor equal to the capacitance of the detector.
We use Ev products CZT's and have tried to use CZT's from a source in california but they had far too much noise (leakage).

We use 70GBeq Am241 sources collimated to a 2mm beam.
Detector is shielded with Al to remove background and lower energy from source
The on farm wool grader uses a field emission X-ray tube 50uA @ 60kV

The Amp/disc is home grown and built on an alumina substrate 2x1 '' thick film and uses the classical discrete dual JFET detector to first major opamp stage.

If you need more info contact me directly you will find this via the earlier link under contact us and look me up under staff search (j.futter)

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