Gamma Spectrometry Forum

Hi all,

My first day with GS-USB-Pro & Scionix 38B57. I calibrated it using Lu-176. GQ GMC-600+ detects 0.03 uSv/h from this wild mushroom from europe. Attached is the spectrum data (PRA). I wonder what the radionuclides are?

TIA

Chris

BTW, I don't have any lead shielding yet (waiting for shipment of lead ingots).

Here is the spectrum with peak @ ~ 400 keV (using Sum Quantity in PRA)

BTW, here is GQ GMC-600 Plus using food inspection mode (measure background first for 5 mins & then measure the subject at the same spot). Banana got 0.03 uSv/h, Brazil nut got 0.02 uSv/h & the wild mushroom from Europe got 0.03 uSv/h.

I'm trying to find out if GQ GMC-600 Plus with pancake GM tube is good enough for food/water inspection for radionuclides. So far, it looks very promising. I wanna see when the 600+ fails to detect any obvious signs. Because it can also detect alpha, I have high hope for this unit. Anyone has experience with the 600+?

ChrisqMalibu wrote: ↑

15 Mar 2022, 00:44

Here is the spectrum with peak @ ~ 400 keV (using Sum Quantity in PRA)

So which isotope is creating the peak at 400 keV ?

What detector are you using here?

Have you considered using background subtraction?

Steven

[BTW, are there any low-cost setups for identifying non-radioactive elements using spectroscopy? I wanna use it to check other contamination in food/water. I would like to compare organic & non-organic foods using spectroscopy as hobby. So it can't cost arms and legs. BTW, I wanna why I'm getting into GS @ https://controlc.com/e388ef75 Thanks]

Looks like Pb-211 or Au-198? per [broken link removed - Steven]

I'm using Scionix 38B57 NaI(Tl) 38mm detector just bought last week from iRad. I bought 2 exact same sets from them with 2 GS-USB-PRO (for myself & my younger brother. One more set to buy for the other ones but may get 3" ones or learn to build my own). BTW, I made a mistake of touching the refurbished detector with bare hands. Something started to itch fingers & had to wash hands and clean everything. I had running stomach that evening. I got to clean used detectors really well. Hope it's not something too toxic. I should have known better to always wear gloves touching any used equipments. My bad.

I also have to buy lead pigs to store all radioactive sources. I have Uranium ore plus Lyso crystal & Thorium lantern mantle (luckily, iRad provided for free for calibration or I would still never have a chance to get calibration done right). I also bought Po-210, Cs-137 & Sr-90 sources but it takes forever to ship. I'm going to store them all in lead pigs. Before I got the lead pigs, it feels weird in the room even though it's supposed to be very low dose. Now, it feels normal. Lesson learns.

I'll do background subtraction this weekend. I'm at work now & when I get home, I'll go to bed by 8PM to get at 3:30 to do mindfulness meditation and get ready for work.

Chris,

I m not 100% convinced about your spectrum. If the Scionix detector is in reasonable condition your spectrum should look different.

Can you please post a clean uncalibrated background spectrum recorded over at least 1 hour with the scionix.

Try setting your gain so the K40 (1460keV) peak lands on around 50 arb.u

Steven

Thanks, Steve. I'll order 16 oz of Potassium Chloride. This weekend, I'll clean the probes well (I'm afraid to touch it before cleaning) and will redo calibration before taking uncalibrated background spectrum for several hours and retaking the spectrum of the wild mushroom.

I also ordered 3 more of the bottles of wild mushroom. I'll have 3 more samples. I got it from Amazon https://www.amazon.com/dp/B006EY0XR6

ChrisqMalibu wrote: ↑

17 Mar 2022, 03:31

Thanks, Steve. I'll order 16 oz of Potassium Chloride. This weekend, I'll clean the probes well (I'm afraid to touch it before cleaning) and will redo calibration before taking uncalibrated background spectrum for several hours and retaking the spectrum of the wild mushroom.

Chris,

There is so much potassium in our environment, that adding KCL hardly makes a difference, you should see the peak from K40 without any additional source, just do a long slow background recording.

Ticking the Sum qty box will make the K40 peak stand out more clearly.

Steven