A little background: I have a 5x5 "pixel" block of LYSO, each pixel is 4x4x22mm so overall the block is 20x20x22mm. I purchased it many years ago when the price was more affordable, made a detector with it and a PMT tube, then later for some reason I don't remember clearly I dismantled that detector - probably because I wanted to reuse the PMT for something else. I put the LYSO somewhere, and then I couldn't find it anymore.
Recently this had been bothering me a lot, and after a few fruitless extensive searches I realized that I can approach this scientifically.
So I pulled my best probe (a GS-2020-CSI with a 2x2" CsI(Tl) crystal), a GS-USB-PRO and started basically prospecting the places in my home where the LYSO might be. I calibrated it against another much smaller sample of LYSO which somehow I hadn't lost. I boosted the sensitivity as much as I dared (1100V, gain boost of 10) to maximize the chance that I will detect it at a reasonable distance. It turns out that it was the right thing to do.
Did many 30-minute spectrum acquisition sessions, first in the most probable locations, then expanding to the more improbable ones.
Just this afternoon, something caught my eye on the latest scan - which was different from all the others. Here it is:
can you spot it? This is with background subtracted. In case you missed it, it's the peak at 307keV, which did not appear on any of the other scans. So I knew I was close. I moved the probe about 40cm in the suspected direction, and this is the next scan:
:)
Turns out this last location was within 15cm of the LYSO. I found it behind a couch. No idea how it got there, but now I have it back.
Science FTW. :P
