Building a LaBr3:Ce Gamma Spectrometer

[GigaBecquerel]

Interesting, I always assumed that isotope ratio was the same everywhere, but I guess it makes sense that it differs depending on location...

Next step will be to design a PCB with preamp, shaper and amplifier all on it, at the moment I am using very old parts that seem to drift a lot with temperature.
The drift might also come from the power supply, but I have no way to do a proper long term measurement on this.

The more I get to know this detector the more I like it!
Below ~100 keV LaBr has worse resolution than NaI, but in the "interesting range" for most isotopes, in 100-500 keV it has wonderful detection efficiency and resolution.

[GigaBecquerel]

I just found one of these PMTs in my stash:
https://et-enterprises.com/images/data_sheets/9924B.pdf

The typical CB value for this is 12, a bit better than the R9420 I'm using right now, and now I'm debating if I should build a new detector with this crystal...
It would be smaller and might give better resolution, but on the other hand one should never change a running system.
Any opinion or experience would be appreciated.

Edit:
The Datasheet mentions "Good SER", but I have no idea what SER stands for.
Any hints?

[luuk]

SER: Single photon Electron Response.
Not really relevant for hobby use!
Luuk

[iRad]

Lukas - Unless you really need a slightly smaller diameter detector, I think you would be spending a lot of time and energy going backwards, as the Hamamatsu R9420 is a very good PMT.