On Monday, June 6, 2022 at 11:36:51 AM UTC+2, Mike Monett wrote:> whit3rd <whi...@gmail.com> wrote: > > > On Sunday, June 5, 2022 at 4:07:22 PM UTC-7, Mike Monett wrote: > >> My Radiascan Radiacode finally arrived from Russia. After the > >> sanctions, I was surprised to see it made it. > >> > >> After learning how to operate it, I began to be curious about the low > >> level background radiation. This is shown in the photo at > >> > >> https://www.mrmonett.com/RADIACOD.JPG > >> > >> I wonder what the spectrum curve is saying, particularly the rise and > >> quick drop near zero. Scouring google, I was unable to find any source > >> that explained it. What mechanism could produce such weak gamma or > >> x-rays? > > > > As a general rule, X-rays excite fluorescences in lots of materials; > > unless you have only low-atomic-number elements around, some of those > > fluuorescences will be in the low X-ray region, and would presumably be > > a low-energy high-count source that penetrates the window of your > > sensor (whatever the sensor is). For some sources, secondary radiation > > is the easiest to detect (a detector can be transparent to high energy > > photons). > Thanks for your reply. As a beginner, it is easy to get confused. I'm > confused. > > To get more information, I decided to get the spectrum of Potassium-40 by > extending the scale of the Radiacode to 3MV, and sitting it on 3 jars of > Windsor Salt Free shown here: > > https://windsorsalt.com/product/salt-free/ > > Wikipedia gives the following information on Potassium-40 decay: > > Potassium-40 is a rare example of a nuclide that undergoes both > types of beta decay. In about 89.28% of events, it decays to > calcium-40 (40Ca) with emission of a beta particle (an electron) > with a maximum energy of 1.31 MeV and an antineutrino. In about > 10.72% of events, it decays to argon-40 (40Ar) by electron capture > (EC), with the emission of a neutrino and then a 1.460 MeV gamma > ray.[1] The radioactive decay of this particular isotope explains > the large abundance of argon (nearly 1%) in the Earth's atmosphere, > as well as prevalence of 40Ar over other isotopes. Very rarely > (0.001% of events), it decays to 40Ar by emitting a positron (?+) > and a neutrino.[2] > > https://en.wikipedia.org/wiki/Potassium-40 > > The detector in the Radiacode is a 1 cm cube of Thallium Doped Caesium > Iodide (CsI:TI). This is a very popular scintillation detector and has good > performance when coupled to a avalanch diode. > > The Potassium-40 spectrum is here: > > https://www.mrmonett.com/POTASS40.JPG > > You can see a slight hump at 1.31 MeV and a clearer hump at 1.46 MeV. This > is very satisfying, but it's not clear how the hump at 1.31 MeV is > produced. Is the Radiacode sensitive to beta decay? > > Also notice the shelf extending back to zero energy. Where does this come > from?""In about 89.28% of events, it decays to calcium-40 (40Ca) with emission of a beta particle (an electron) with a maximum energy of 1.31 MeV and an antineutrino." The neutrino was pretty much invented to explain why the electron came out with a range of energies - the neutrino carried away the rest of the energy.> You mentioned above "X-rays excite fluorescences in lots of materials". > > But the sources are presumably beta and gamma. Where is the fluorescence coming from?Fluorescence can also be excited by energetic electrons - "beta rays". Gamma ray is just another name for an X-ray. It took a while for us to understand that they were both energetic photons. -- Bill Sloman, Sydney
Low Level Gamma Radiation
Started by ●June 5, 2022
Reply by ●June 6, 20222022-06-06
Reply by ●June 6, 20222022-06-06
On 6/6/2022 6:38 AM, Anthony William Sloman wrote:> On Monday, June 6, 2022 at 11:36:51 AM UTC+2, Mike Monett wrote: >> whit3rd <whi...@gmail.com> wrote: >> >>> On Sunday, June 5, 2022 at 4:07:22 PM UTC-7, Mike Monett wrote: >>>> My Radiascan Radiacode finally arrived from Russia. After the >>>> sanctions, I was surprised to see it made it. >>>> >>>> After learning how to operate it, I began to be curious about the low >>>> level background radiation. This is shown in the photo at >>>> >>>> https://www.mrmonett.com/RADIACOD.JPG >>>> >>>> I wonder what the spectrum curve is saying, particularly the rise and >>>> quick drop near zero. Scouring google, I was unable to find any source >>>> that explained it. What mechanism could produce such weak gamma or >>>> x-rays? >>> >>> As a general rule, X-rays excite fluorescences in lots of materials; >>> unless you have only low-atomic-number elements around, some of those >>> fluuorescences will be in the low X-ray region, and would presumably be >>> a low-energy high-count source that penetrates the window of your >>> sensor (whatever the sensor is). For some sources, secondary radiation >>> is the easiest to detect (a detector can be transparent to high energy >>> photons). >> Thanks for your reply. As a beginner, it is easy to get confused. I'm >> confused. >> >> To get more information, I decided to get the spectrum of Potassium-40 by >> extending the scale of the Radiacode to 3MV, and sitting it on 3 jars of >> Windsor Salt Free shown here: >> >> https://windsorsalt.com/product/salt-free/ >> >> Wikipedia gives the following information on Potassium-40 decay: >> >> Potassium-40 is a rare example of a nuclide that undergoes both >> types of beta decay. In about 89.28% of events, it decays to >> calcium-40 (40Ca) with emission of a beta particle (an electron) >> with a maximum energy of 1.31 MeV and an antineutrino. In about >> 10.72% of events, it decays to argon-40 (40Ar) by electron capture >> (EC), with the emission of a neutrino and then a 1.460 MeV gamma >> ray.[1] The radioactive decay of this particular isotope explains >> the large abundance of argon (nearly 1%) in the Earth's atmosphere, >> as well as prevalence of 40Ar over other isotopes. Very rarely >> (0.001% of events), it decays to 40Ar by emitting a positron (?+) >> and a neutrino.[2] >> >> https://en.wikipedia.org/wiki/Potassium-40 >> >> The detector in the Radiacode is a 1 cm cube of Thallium Doped Caesium >> Iodide (CsI:TI). This is a very popular scintillation detector and has good >> performance when coupled to a avalanch diode. >> >> The Potassium-40 spectrum is here: >> >> https://www.mrmonett.com/POTASS40.JPG >> >> You can see a slight hump at 1.31 MeV and a clearer hump at 1.46 MeV. This >> is very satisfying, but it's not clear how the hump at 1.31 MeV is >> produced. Is the Radiacode sensitive to beta decay? >> >> Also notice the shelf extending back to zero energy. Where does this come >> from? > > ""In about 89.28% of events, it decays to calcium-40 (40Ca) with emission of a beta particle (an electron) with a maximum energy of 1.31 MeV and an antineutrino." > > The neutrino was pretty much invented to explain why the electron came out with a range of energies - the neutrino carried away the rest of the energy.And in the more modern physics it helps conserve spin and lepton number/flavor, they're on the lookout for something like muon -> electron + gamma where the energies are correct but lepton flavor conservation is violated. Haven't seen it yet AFAIK>> You mentioned above "X-rays excite fluorescences in lots of materials". >> >> But the sources are presumably beta and gamma. Where is the fluorescence coming from? > > Fluorescence can also be excited by energetic electrons - "beta rays". Gamma ray is just another name for an X-ray. It took a while for us to understand that they were both energetic photons. >I think in particle physics all photons that come from decay tend to be called "gamma" even if they overlap with the X-ray's domain below about 100 keV. At the bottom of page 4: <http://www-odp.tamu.edu/publications/tnotes/tn26/CHAP5.PDF> "About 90% of the counts come from the low-energy part of the spectrum, which is degraded by Compton scattering." I think this means the area around 100 keV in the background radiation is very noisy with contributions from the scattered photons of lots of stuff.
Reply by ●June 6, 20222022-06-06
On 06/06/2022 03:12, Ricky wrote:> On Sunday, June 5, 2022 at 9:25:18 PM UTC-4, bitrex wrote: >> On 6/5/2022 9:24 PM, bitrex wrote: >>> On 6/5/2022 7:07 PM, Mike Monett wrote: >>>> My Radiascan Radiacode finally arrived from Russia. After the >>>> sanctions, I >>>> was surprised to see it made it. >>>> >>>> After learning how to operate it, I began to be curious about the low >>>> level >>>> background radiation. This is shown in the photo at >>>> >>>> https://www.mrmonett.com/RADIACOD.JPG >>>> >>>> I wonder what the spectrum curve is saying, particularly the rise and >>>> quick >>>> drop near zero. Scouring google, I was unable to find any source that >>>> explained it. What mechanism could produce such weak gamma or x-rays? >>>> >>>> Thanks >>> >>> What does the X axis represent?Energy I presume. There will be a mix of elements contributing to the background and some will have characteristic lines. Potassium nitrate or instant coffee may have enough K40 in to allow some calibration. https://gammaspectacular.com/blue/k-40-gamma-spectrum#>>> >>> There's a long decay chain from naturally-occurring thallium 232 >> Er, Thorium 232, not thallium > > When I look at the decay chain, I don't see any gamma emissions. Is this in a more rare decay event?No they are common but they occur in conjunction (shortly after) either an alpha or beta decay due to the recoil and necessary rearrangement of the remaining components of the atomic nucleus. Just after the alpha or beta particle escapes the nucleus is in an excited state with a hole in it where the emitted particle once sat. Gamma ray(s) get emitted as it rearranges back to its new ground state. Only emissions that alter the atomic number and/or mass are normally shown on decay chain diagrams. -- Regards, Martin Brown
Reply by ●June 6, 20222022-06-06
On 6/6/2022 4:24, bitrex wrote:> On 6/5/2022 7:07 PM, Mike Monett wrote: >> My Radiascan Radiacode finally arrived from Russia. After the >> sanctions, I >> was surprised to see it made it. >> >> After learning how to operate it, I began to be curious about the low >> level >> background radiation. This is shown in the photo at >> >> https://www.mrmonett.com/RADIACOD.JPG >> >> I wonder what the spectrum curve is saying, particularly the rise and >> quick >> drop near zero. Scouring google, I was unable to find any source that >> explained it. What mechanism could produce such weak gamma or x-rays? >> >> Thanks > > What does the X axis represent? > > There's a long decay chain from naturally-occurring thallium 232 and > uranium 238 down to stable lead, and a number of steps in the chain > produce a gamma photon > > > >X-axis should be energy, the spectrum looks right for it to be that. Clearly with such a device you won't see much energy resolution, probably the 1461 keV line of 40K won't be visible even if it were within the energy range of the device (probably not, by the size of it the detector would be too small for that; buy a kilogram of bananas and measure it to see if that's the case). Here is what the 40K peak looks like (the marker, a red X, is on top of it): http://tgi-sci.com/tgi/nmc3spc.htm#nmc3demo If the banana pack yields higher counts per second and no visible peak (which is what I expect you will see) it will be due to Compton etc., others may be more familiar with the details, I just design the spectrometers and have learnt only as much as it takes to do the measurement and the evaluation of the spectra.... ====================================================== Dimiter Popoff, TGI http://www.tgi-sci.com ====================================================== http://www.flickr.com/photos/didi_tgi/
Reply by ●June 6, 20222022-06-06
In article <d14769a6-4607-49b7-b2c3-0f9e5312bacen@googlegroups.com>,>> I wonder what the spectrum curve is saying, particularly the rise and quick >> drop near zero. Scouring google, I was unable to find any source that >> explained it. What mechanism could produce such weak gamma or x-rays? > >As a general rule, X-rays excite fluorescences in lots of materials; unless you >have only low-atomic-number elements around, some of those >fluuorescences will be in the low X-ray region, and would presumably be >a low-energy high-count source that penetrates the window of your sensor >(whatever the sensor is).Correct. In fact, when building high-quality isolation chambers for measuring gamma specta (the gamma equivalent of a Faraday cage, in effect) it's necessary to use a layered approach. The outer layer is usually lead, but when gammas from outside hit the lead it will fluoresce in the X-ray spectrum. So, inside the lead, you have another layer which effectively absorbs those X-rays... and *it* may fluoresce at a lower-energy X-ray frequency, so you may need a third layer of yet another material. I've used a home-made gamma spectrometer (NaI crystal, a PMT, and my own electronics) to look at some naturally-occurring radioactive materials. One interesting source is some monazite sand from a local beach - it has a significant amount of thorium in the mix and I get an appreciable count rate if I lower the sensor down onto a big box of the stuff. The spectrum does show the expected gamma-ray peaks for thorium, but they're not as "clean" as for a purer thorium sample and there's a strong continuum of lower-energy gamma/X-rays just as the OP's photo showed. My understanding is that this is "degraded" gamma - in other words, gamma-induced fluorescence occurring within the sample itself. Reducing or eliminating this requires flattening out the sample (so that there's a better chance for a thorium-generated gamma to hit the NaI sensor before it hits an atom of the sand and causes fluorescence). One spectrum I looked at was that of a "quantum energy pendant" that can be bought inexpensively on eBay and elsewhere. It's supposedly a natural negative-ion source with semi-mystical healing powers. What it actually seems to be is a pendant made from a natural ore rich in thorium. It emits "negative ions" in the form of beta-decay electrons, and reportedly its emission rates are high enough that if you wear it next to your skin every day you'd exceed certain government safety limits for ionizing-radiation exposure in that area (possible cancer risk or a localized radiation burn). http://www.radagast.org/~dplatt/gamma/quantum-pendant.png The green trace is the background radiation level in my work area. The purple trace is from sampling for the same amount of time, with the pendant in contact with the NaI sensor. The thorium-228 peak is clear, there's another from lead and radium decay daughters, and the actinium-228 peak is also visible. With another sensor and voltage setting, the background signal from potassium-40 is visible... and bringing a bottle of Morton "lite salt" or a bag of water-softener potassium chloride around the sensor really makes it obvious!
Reply by ●June 7, 20222022-06-07
On 6/5/2022 11:54 PM, Anthony William Sloman wrote:> On Monday, June 6, 2022 at 1:07:22 AM UTC+2, Mike Monett wrote: >> My Radiascan Radiacode finally arrived from Russia. After the sanctions, I >> was surprised to see it made it. >> >> After learning how to operate it, I began to be curious about the low level >> background radiation. This is shown in the photo at >> >> https://www.mrmonett.com/RADIACOD.JPG >> >> I wonder what the spectrum curve is saying, particularly the rise and quick >> drop near zero. Scouring google, I was unable to find any source that >> explained it. What mechanism could produce such weak gamma or x-rays? > How about > > https://en.wikipedia.org/wiki/Potassium-40 > > I seem to remember that it is the most important gamma ray source in regular terrestrial environments. > Yep, used to built bore hole equipment that explored what layers were below. One piece was a gamma ray detector. This description doesn't mean much to me anymore, if it ever did, but but here are some down hole gamma graphs.> https://www.kgs.ku.edu/Publications/Bulletins/LA/03_gamma.html Mikek -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus
Reply by ●June 12, 20222022-06-12
On Sunday, June 5, 2022 at 4:07:22 PM UTC-7, Mike Monett wrote:> My Radiascan Radiacode finally arrived from Russia. After the sanctions, I > was surprised to see it made it.This listing is also very interesting: https://www.ebay.com/itm/194659036410 Basically 2000+ PMT+CsI(Tl) assemblies for sale at around $20 each. Wonder how they'd compare to the solid-state CsI(Tl) detector assembly in the Radiacode unit? -- john, KE5FX
Reply by ●June 12, 20222022-06-12
On 6/12/2022 22:19, John Miles, KE5FX wrote:> On Sunday, June 5, 2022 at 4:07:22 PM UTC-7, Mike Monett wrote: >> My Radiascan Radiacode finally arrived from Russia. After the sanctions, I >> was surprised to see it made it. > > This listing is also very interesting: > > https://www.ebay.com/itm/194659036410 > > Basically 2000+ PMT+CsI(Tl) assemblies for sale at around $20 each. > Wonder how they'd compare to the solid-state CsI(Tl) detector assembly > in the Radiacode unit? > > -- john, KE5FXThis is incredibly cheap indeed. I thought even Hamamatsu can't make PMT-s that small :). (4 years ago they sold us some of their R12421 at 450 euro each IIRC). But just the scintillation crystal would probably cost much more, let alone the PMT at Hamamtsu.... No idea how they manage that.
Reply by ●June 25, 20222022-06-25
"John Miles, KE5FX" <jmiles@gmail.com> wrote:> On Sunday, June 5, 2022 at 4:07:22 PM UTC-7, Mike Monett wrote: >> My Radiascan Radiacode finally arrived from Russia. After the >> sanctions, I was surprised to see it made it. > > This listing is also very interesting: > > https://www.ebay.com/itm/194659036410 > > Basically 2000+ PMT+CsI(Tl) assemblies for sale at around $20 each. > Wonder how they'd compare to the solid-state CsI(Tl) detector assembly > in the Radiacode unit? > > -- john, KE5FXI tried to order one. Does not ship to Canada. Can you order one and mail it to me? I can pay you via Paypal. Thanks. -- MRM
Reply by ●June 26, 20222022-06-26
On a sunny day (Sat, 25 Jun 2022 18:16:39 -0000 (UTC)) it happened Mike Monett <spamme@not.com> wrote in <XnsAEC1913D785B5idtokenpost@144.76.35.252>:>"John Miles, KE5FX" <jmiles@gmail.com> wrote: > >> On Sunday, June 5, 2022 at 4:07:22 PM UTC-7, Mike Monett wrote: >>> My Radiascan Radiacode finally arrived from Russia. After the >>> sanctions, I was surprised to see it made it. >> >> This listing is also very interesting: >> >> https://www.ebay.com/itm/194659036410 >> >> Basically 2000+ PMT+CsI(Tl) assemblies for sale at around $20 each. >> Wonder how they'd compare to the solid-state CsI(Tl) detector assembly >> in the Radiacode unit? >> >> -- john, KE5FX > >I tried to order one. Does not ship to Canada. Can you order one and mail it >to me? I can pay you via Paypal. Thanks.I just found this on tomshardware.com: https://www.tomshardware.com/news/raspberry-pi-pico-detects-radiation nice spectra (github link) https://github.com/Open-Gamma-Project/Open-Gamma-Detector
