1275 keV peak desapeared

[Andres Vargas]

Hi everyone.

I'm working on calibrating a LYSO crystal (4x4x20 mm), to do so I am using Na22. I was able to get a full spectrum showing the 511 keV peak, the 1275 keV peak and it's compton background, however the very next day I tried to recreate the measurement, nothing was changed on the setup, but the 1275 peak is gone, it's like my crystal is now blind to that peak, I still get signals that should correspond to 1275 keV readings from my SiPM, however they are not above background, there is no peak.

Does anyone have any idea why this could happen? I've tried multiple changes to the setup but I still can't se the peak. Also, just to to be clear, nothing in the electronics has changed. The spectrum I get is a histogram of areas measured by a Rhode & Schwarz RTO6 oscilloscope, it calculates the pulse area directly from the SiPM signal.

[Sesselmann]

Hello "anvargas",

Thanks for posting your question, I don't have an answer to your question, but can I ask you to please hop over to the introductions forum, and give yourself a quick introduction. Tell us who you are (Real Names only) and what your interests are.

In the UCP (User Control panel) you can change your handle to a real name or add a signature to your posts.

Thanks..

Steven