Single channel analyzer

Scintillation crystals, PMTs, voltage dividers etc...
john scint
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Joined: 24 May 2018, 03:20
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Single channel analyzer

Post by john scint » 24 May 2018, 03:49

hi all,

My name is John and I try to build signal channel analyzer. Espcsially I would like to made instrument to mesure low x-ray energies about 5-10kev.

I have crystal Cs(ti) with PMt tube EMI 9524.

I have negative high voltage power supply -826v , after charge sencitive amplifier which produce an output with 150μS pulse width and the pulse height about 60mv up to 200mv. Also , I build an operational amplifier LM833 which I power it with +/-12v to increase pulses 20 times , it must?

Moreover , I have LM219 and I would like to build window comparator have some one a circuit?

Lust , I upload the noise of circuit and other photos of my board
Attachments
!!! PM_voltage divider_EMI 9524 !!!.jpg
29955453_10215736217576793_14103723_o.jpg
20mV-200μS.jpg
10mv θορυβος 2.jpg
10mV-500μS.jpg
20mV-500μS -2.jpg

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Steven Sesselmann
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Location: Sydney
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Re: Single channel analyzer

Post by Steven Sesselmann » 24 May 2018, 19:58

Hi John,

Thanks for the introduction..

You do not need much gain for sound card spectrometry, instead you need a nice clean pulse of around 100-150 µs with a pulse height of around 150-200 mV from Cs137 (662 keV). It is preferable to run the signal through an RC filter to round off the top of the pulse.

The sound card Line-In port should have a range of -+1.4 Volts.

Why are you running your PMT with negative voltage, is this the recommended bias?

Normal PMT bias is positive to anode and ground to the photocathode.

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

john scint
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Re: Single channel analyzer

Post by john scint » 25 May 2018, 05:15

Hi Steven,

thank for your quick reply,

I run PMT with negative power supply because I started before years with one other instrument "DT590 scintillation probe - PDR 56F radiac set" and then building some other like this one ... I shop negative power supply and I start stady from this instrument.....

I would like to build a handle instrument which it can adjust the energy which I need every time and then with TTL pulses on output I'll count them.

have some one circuit?

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Steven Sesselmann
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Re: Single channel analyzer

Post by Steven Sesselmann » 25 May 2018, 16:16

John,

I wouldn't build a single channel analyser, I would just use an iPhone and geigerbot to achieve the same thing.

https://youtu.be/CMav0wHTEMQ

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

john scint
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Joined: 24 May 2018, 03:20
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Re: Single channel analyzer

Post by john scint » 25 May 2018, 16:26

Dear Steven

May you have a circuit?

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Steven Sesselmann
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Re: Single channel analyzer

Post by Steven Sesselmann » 26 May 2018, 14:06

No, haven't made one of those, but Google it and something should come up.

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

john scint
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Joined: 24 May 2018, 03:20
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Re: Single channel analyzer

Post by john scint » 26 May 2018, 17:21

Also, May you know if and how can I know the energy of every element on kev which instrument scintillation probe detect???

miree
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Re: Single channel analyzer

Post by miree » 27 May 2018, 03:45

Hello John

This website might be useful: http://www.nndc.bnl.gov/chart/chartNuc.jsp You can click on any isotop and get a list of the decay radiation (appears on the bottom of the page after selecting a radioactive isotope). The page has also a link to a gamma finder (click on "Levels and Gammas" on the bottom right of the page) where you can search for isotopes with given decay energy.

Michael
Michael Reese
Darmstadt Germany

john scint
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Re: Single channel analyzer

Post by john scint » 28 May 2018, 01:57

Thank Michael ,

Very useful site.
But the first think on my homemade instrument are that, how can I know the level of voltage (mv per element) haves every element which detect my instrument???
I would like instrument detect only one element after calibration (single channel analyser)

How can I do that? Someone told me this can do only with one radiation source. I have Am-241 amerisium from smoke detector which it haves two peaks the one higher about 56 Kev

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Peter-1
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Re: Single channel analyzer

Post by Peter-1 » 29 May 2018, 02:38

hello John,
i show you the response from my system with Am241.
The pulse is :

Peter
Attachments
Puls-1.jpg
2018_05_28-Am241.jpg

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