Accuracy of Scionix 38B57? Markings on Cap

[kotarak]

Hey guys,
quick question!
I started reworking the voltage divider of the Scionix 38B57 detector and noticed a label on the top cap - it is hand-written and it reads:

SED 521
6.4%
150 mV

What does it mean? Is the detector any good?

Best regards,
Andrey Stoev

[luuk]

Hello Andrey,
SED521 is the serial number , 6.4% is the resolution for Cs-137(662KeV) that is very good considering that the lowest possible is 6.0% for NaI(Tl), 150mV is the output measured by the customer is has not a significant value for hobby purpose.
If the detector is not modified but still has the original internal voltage divider you have to remember that this is not very linear, that will give you a (fake)better resolution, normally these detectors have mostly a real resolution from 6.4 to 7.0 % for 662KeV
Luuk

[kotarak]

Hi Luuk,
Thank you so much for the information!
The detector had the original circuit which I removed and installed a "standard PMT divider" using R=2M .
Havent tested it yet as I am missing an SHV connector for my cable.
Will update the post once I get it going.
Best,
Andrey