Gamma Spectrometry Forum

Given the advent of Fukushima in 311 with the Pacific Ocean becoming the waste dump I have become a very concerned person about the impact that this may have upon this earth and it's bio-systems.

Two plus years ago I built a diy geiger kit counter / logger using the SBT-11A & SBT-10 Russian mica faced tubes which have sensitivities of alpha, beta and gamma. I have learned the basic field technique of using an aluminum and paper filters to respectively block beta/alpha, alpha. The logging function storing unto a SD memory card which greatly simplifies downloading into a spread sheet. I soon became aware of a need for more sensitive scintillation spectrometry equipment. I am hoping to learn the qualitative and quantitative operational skills.

I read some of Dr. John Gofman's and Dr. Ernest Sternglass papers, and follow the nuclear aggregator www.enenews.com.

In process: A Gs-1102 Pro is in the mail. Some support equipment is in the mail. A used Teledyne Isotopes, INC. NaI(TI) s 801 detector is in the mail. If there is anyone on this list that has knowledge about this detector please school me. What is the PMT? Specifications of the crystal?

Thanks Steven for inviting me unto this forum.

Tom

HI Tom! I'm up here in Anchorage. Welcome to the group!

Hi Tom,

Welcome to the group..

PMT stands for Photon Multiplier Tube, it can amplify the energy of a single photon into an electronic pulse of several tens on milli volts. Typically the PMT is mounted to a scintillation crystal, the purpose of the crystal is to convert the high energy of a gamma ray into multiple photons. So you could say it is a multi stage process, One gamma ray is reduced to multiple light photons, those are in turn converted into millions of electrons in the PMT and further amplified by electronics so it comes out at audio line level, with pulses ranging from zero to 1.7 Volts.

Steven

Hi Tom,

Welcome to the group!

If you want to build your own scintillator or modify it, I guess and hope my previous post may bring you some enlightenments: viewtopic.php?f=14&t=108

Feel free to post your questions on the forum!

Yvan.

Thanks for the welcomes.
I am attempting a turnkey start up. That is if one can accept a 30 year old detector from a top end manufacture with no specifications as being turn key.. My past practice has been to understand my tools. The query about this Teledyne Isotopes, INC. NaI(TI) s 801 detector was hopefully someone knows this detectors specifications. My web search s have turned up nothing specific. Teledyne on a similar detector, possibly of an earlier vintage, used a PMT that was similar to { Dumont 6292, RCA 8053, EMI 9536B ].
Thanks
Tom

Hi,

I guess it depends on the purpose you want to use it.
Is it for low or high activity measurement, spectroscopy or only for counting?
Have you see the condition of your crystal? If it was nicely sealed and no leaks occured, there may not be any problem. Otherwise it could be a problem, NaITl ones are really sensitive to humidity and could easily be destroyed in few days (or hours) if exposed to outside atmosphere.

About the PMT, I saw Dumont 6292 could go about 1800V (max. ratings). Most of PMT works at 750/900V but I guess you can go furter for this detector...
In my opinion, and if all is working fine, you sould have a resolution about 7 to 9% (if the crystal dimensions I found were correct), an effective energie range from 30keV to ~2MeV and a background rate about 3000/3500 couts per minute.

Just begin at 500V and carrefully increase until you have approximately these characteristics.

Please create a topic in Detector (or appropriate) section if further questions, we'll be glad to help you!

Yvan.

Thanks Yvan
I'm still awaiting for the rest of my equipment to arrive. FYI; the detector is totally sealed.
At the proper time, I may repost this detector question as you have suggested.
Tom