- The problem with regular Geiger counters is that the sensitive ones saturate and you risk missing being in a high radiation environment. The models built for civil protection are not sensitive enough for daily use.
Luckily scintillation counters, like the one from the article seems to be, became really cheap in the past few years. I have a RadiaCode and it is a device one could only dream of a decade ago.
- >The device can be used by industrial and medical radiation users, regulatory authorities, the nuclear energy industry, first responders and military users
It cannot be used by TSA employees. They are not allowed to even wear dosimeters.
- TSA employees can use them, they are just not permitted to (for some reason).
- Federal liability around future health concerns.
Edit: https://www.cdc.gov/niosh/hhe/reports/pdfs/2003-0206-3067.pd...
- Those big backscatter X-ray machines [1] have a powerful X-Ray tube. Not that I'd be worried if I flew once a month, but if I was a member of the aircrew and going through more than once a day I'd be concerned. Think about when you get a medical or dental X-Ray and the operator puts on a lead apron and goes around a corner -- they don't get anywhere near the dose that you get, but they are around the machine all the time time. TSA staff did none of that.
Those machines were killed off because it was easy to demonstrate walking right through them and not getting detected if you wear a gun in a holster the way you would normally wear a gun if you weren't trying to hide it. The trouble is it depends on the gun being between you and the scanner because the gun appears black against the white radiation bouncing back from all the hydrogen atoms in you. With no background the gun is black-on-black and invisible. When people realized you could put a cop in front of the scanner and demo that the scanner couldn't see his gun it got around quickly that the scanner was worthless. [2]
[1] https://en.wikipedia.org/wiki/Backscatter_X-ray
[2] Ok, instead of getting scanned twice on your front and back they could scan you four times but this is getting ridiculous.
- I'm not sure what is the context of your link. Is it supposed to show that TSA employees are not permitted to wear dosimeters? Because if so, I can't find that in there.
- Why aren't they?
- Tangentially related: If you haven’t already, I‘d suggest to look at Radon. It‘s the #2 reason for lung cancer, and is very easy to measure and mitigate (automatic ventilation). Many countries have Radon hazard maps.
- I wound up grabbing a couple of AirThings sensors to see what my indoor air quality looks like. Those things can be a bit pricey, but they are easy to interface with locally and integrate into Home Assistant, providing you with measures for a few different properties. I found that the radon levels in my basement rarely breach 2 pCi/L, but can breach as high as 4 pCi/L very infrequently (i.e. once a year.) Not sure if there is really any point in being concerned about it, but it's interesting information nonetheless.
- In the meantime I was recommended a spa day at a place with Radon gas because it's so good for me health wise supposedly. Irony through the roof.
- Let's just hope they are lying. Where do you even get radon gas? The most stable isotope has a half life of just 3.8 days. Unless they mean they built on a place with unfortunate geology or have a large stockpile of radium around.
- There are caves and mines that have radon from natural sources.
Why are people hanging out in Montana's radon-filled mines? https://www.mtpr.org/montana-news/2023-01-18/why-are-people-...
- Granite sided valleys fill every day with radon until wind clears it out.
Certainly not as dense as basements and caves but worth pointing out that radon is a constant ongoing decay product of natural uranium in rock.
- Well, if the exposure isn’t chronic, there might be a hormetic effect? Radiation dosage is the “classical” example of hormesis
- I wonder how they figured out that radon causes that cancer and not, say tire particles.
- From what I can tell, they didn't. The theoretical basis for it is the Linear No-Threshold Model, which is, bluntly put, garbage. The empirical evidence seems to come mostly from so-called case-control studies, which are, bluntly put, garbage.
You conduct a case-control study as follows: 1) Select some number of lung cancer patients and a control group without lung cancer. 2) Try to establish why the cancer patients got cancer and the non-cancer group didn't, by retroactively estimating their smoking habits, radon exposure (from radon maps or retroactive measurements of places they lived at), as well as other factors. 3) Use statistics to try to disentangle suspected radon cases from smoking (90%) and other stuff. 4) Pretend that all this is not totally biased, sampling or otherwise.
- And have one of the highest impact studies conducted on coal miners (who all smoked.)
- The radon-cancer link has been suspected and studied since the mid 20th century, and been suspected in miners before the word cancer even existed.
- I note the comment by mppm and accept that exact risk levels and associations are problematic while also noting medical students can and have demonstrated increased cancer and tumours in lab animals when exposed to radon.
I once measured broad area environmental levels of background radiation as part of geophysical exploration, I'm not in the medical field (although I did some post grad epidemiology work as part of a mathematics degree).
Medical papers of interest on radon include:
* WHO Handbook on Indoor Radon: A Public Health Perspective (2009) - https://pubmed.ncbi.nlm.nih.gov/23762967/Indoor radon was declared a human carcinogen in 1987 by the WHO and in 1988 by the United States Environmental Protection Agency (EPA).* Radon and Lung Cancer: Current Trends and Future Perspectives (2022) - https://pmc.ncbi.nlm.nih.gov/articles/PMC9264880/
^^ Broad overview handbooks and trends
-------------------
Example studies
* Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies (2005) - https://pmc.ncbi.nlm.nih.gov/articles/PMC546066/
* A 10-year follow-up study of yearly indoor radon measurements in homes, review of other studies and implications on lung cancer risk estimates (2021) - https://www.sciencedirect.com/science/article/pii/S004896972...
- Kinda neat that they were able to marry all those different scintillators together in one package, but their paper makes it sound like you're still going to want an He3 tube along if you really care about finding neutrons.
- It claims it detects all ionizing radiation but doesn't list high energy UV among the things detected.
- UV-C radiation is so rare in our lives and even in specific work environments that unless you have a very special need for it, you don't need to detect it. As far as I know, it's mostly just germicidal lamps and arc lamps that generate enough UV-C to be of any real concern, and in that case the operator knows about it.
- Agreed that a detector would not help but some UV-C lamps are sold freely with arguably insufficient warnings.
Is das folgende Geraet sicher? https://www.doctor-san.eu/luftreinigung-desinfektion/uvc-des...
https://www.doctor-san.eu/luftreinigung-desinfektion/uvc-des...
https://www.amazon.de/Doctor-San-Sanierungstechnik-Desinfekt...
- interesting, you're right they are devoid of warnings. I thought maybe it was an EU/Germany thing, but looking at American listings it's similar. This may be due to the level of UV-C exposure you're getting. EG weak laser pointers won't have the same caution signs as a Class IV laser.
Edit: Looking into it a bit more, seems that "far-UVC" light is a bit higher energy than the typical "UVC". It seems that far-UVC penetrates less deeply and critically is apparently much better absorbed by the dead layers of the skin than UVC, so it is currently recognized as safe... All I could find on it was a Columbia research artcle.
- Like UV light, alpha radiation is easily shielded by most kinds of material. Even after skimming the linked publication, it does not seem clear to me how the alpha radiation (and UV) would reach the devices sensor.
Probably something behind "... and measure alpha and beta radiation from contaminated surfaces".
- "Shielding" is a relatively crude term. Alpha radiation is "shielded" by a sheet of paper in the sense that the attenuation is so high, and the attenuation length is so short when compared to the thickness of that paper, that less than 1/1000th of the original particles arrive on the other side of the paper.
However, this means that there are still very few but not zero alpha particles arriving on the other side. Plus, the energy of those alpha particles doesn't just go away, it will be either transformed into highly energetic photons (in the hard UV to gamma range) or it will ionize the attenuating medium, leading to photons from line emissions (infrared to visible to UV) or other ionization-related effects (e.g. an ionisation current in semiconductor diodes). All those things can be detected, and you can calibrate your detector for the relative sizes of those effects you are seeing when compared to the incident alpha rays.
- This is somewhat inaccurate from a physical perspective. What you say would be applicable to the attenuation of gamma rays, which is governed by low-probability interactions and is therefore exponential. But alpha particles, being charged an heavy, lose energy continuously through electron interactions and have a relatively fixed range in matter, beyond which the incidence is practically zero.
- No, that is just plain wrong. All attenuation is exponential (except very special stuff like energy resonances at certain particle energies). You just get very different exponents for rarely vs. frequently interacting particles. The charge of an alpha particle is also only twice the charge of a beta particle with a far higher (orders of magnitude, not just a factor of 2) penetration depth. The relevant difference is actually the mass and size (i.e. cross-section) of an alpha particle that makes it far more frequently interacting.
There are some more differences that govern the cross-section like conservation of momentum and angular momentum in certain interactions where there are differences between gamma and alpha particles. Or magic number nuclei that are relevant for neutron absorption.
But in general, for a given material and particle, attenuation is always always always exponential over the penetration depth vs number of particles, until you hit a low enough energy that some other mechanism for energy transfer can come into play or become unavailable, where the exponent will change and you will see a change in slope.
- Please take a look at slide 11 of this presentation [1]. Stopping power and Bragg peak (slide 30) are also relevant concepts. What you are describing applies to photons and neutrons, but not to charged particles.
1. https://indico.cern.ch/event/975141/contributions/4137563/at...
- Well then, please read what those slides say. Then read what I wrote.
The Bragg peak is about energy deposition, not the number of particles arriving at some point. When the energy of a particle changes going through the medium, the absorption changes. Still an exponential curve, just piece-wise exponential. Look at slide 11, that cutoff. Look at the logistic formula for it and its limit going right: still an exponential.
- > Plus, the energy of those alpha particles doesn't just go away, it will be either transformed into highly energetic photons (in the hard UV to gamma range) or it will ionize the attenuating medium, leading to photons from line emissions (infrared to visible to UV) or other ionization-related effects (e.g. an ionisation current in semiconductor diodes).
Why can't it end up as thermal energy in the attenuating medium instead?
- Because thermal energies are far lower than what those particles are depositing. The thermal movement at those energies would still be ionizing because it would some nucleus away leaving a few stray electrons in the lattice.
But of course, sooner or later the secondary, tertiary, ... particles will end up as thermal energy. And of course any ionization always has a thermal component, the lattice will always get a transfer of momentum.
- Shielding is not a crude term, it is indeed used as technical language in the world of radiation safety. You are also using the term attenuation incorrectly, as sibling comment points out.
- Shielding in radiation safety means attenuation to a safe level. But for detection, that is irrelevant because radiation detectors can be very sensitive, such that even very minute quantities making it through a "shielding" are still sufficient. When in doubt, you just increase integration time to almost forever and you will still get a sufficient number of particles to get a measurement.
- maybe it infers alpha radiation from detection of decay chain particles / photons at energies indicative of alpha presence.
- Yes, we're all still waiting for the medical tricorder.
57 points by PaulHoule 4 days ago | 36 comments