Gamma Spectrometry Forum

Hello everybody,
i want to share with you this comparison i made between 2 Scionix 38B57 E1 detectors,
the first has a bad resolution, around 8,5% @ 662KeV due to some wet in the crystal.
Recently I had the opportunity to refurbish another detetector, this time the things are different,
i obtained a good resolution of 7% both in Theremino MCA and BeqMoni.
The 2 probe was setted in the same way, with the same home made voltage divider of 120Mohm as shown below and both supplied with a 740 Volt bias.
In the third picture you can see the benefits of the new probe with improved resolution, especially on low-mid energies.

Mattia,

Thanks for sharing, nice work on the refurbishment and good spectra. Yes I agree a 1% difference in resolution can make quite a difference, although 8% is usually considered acceptable, but a resolution between 6% and 7% is absolutely more satisfying.

Steven

This is from a thorium mantle using a scionix 38b57 coupled with Theremino PMT. I wonder how old these scionix 38b57 are.

This is from Radium clock parts

These detectors are around 8 to 17 years old.
Luuk

Thank you Luuk!

Sorry to dredge up an old thread, but I could really use some help! Mattia (or anyone else really!), if you're reading this, I would love to get some input from you! I have a Scionix 38B57 with the original transistorized voltage divider soldered in place and I want to convert it to a resistive voltage divider like you have in the first photo, but I can't identify the pinout on my PMT, and I don't know the value of the capacitor I should use. I've got the 10 meg resistors, at least.

Please help!