[HN Gopher] Handheld detector for all types of ionizing radiatio...
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Handheld detector for all types of ionizing radiation improves
radiation safety
Author : PaulHoule
Score : 49 points
Date : 2025-04-20 17:13 UTC (2 days ago)
(HTM) web link (phys.org)
(TXT) w3m dump (phys.org)
| goda90 wrote:
| It claims it detects all ionizing radiation but doesn't list high
| energy UV among the things detected.
| blueflow wrote:
| 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".
| thyristan wrote:
| "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.
| mppm wrote:
| 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.
| thyristan wrote:
| 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.
| mppm wrote:
| 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/4137
| 563/at...
| thyristan wrote:
| 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.
| theglocksaint wrote:
| 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.
| thyristan wrote:
| 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.
| tzs wrote:
| > 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?
| thyristan wrote:
| 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.
| jjtheblunt wrote:
| maybe it infers alpha radiation from detection of decay chain
| particles / photons at energies indicative of alpha presence.
| momoschili wrote:
| 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.
| weinzierl wrote:
| 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...
| momoschili wrote:
| 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.
| frozencooler wrote:
| >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.
| KMnO4 wrote:
| TSA employees can use them, they are just not permitted to (for
| some reason).
| toomuchtodo wrote:
| Federal liability around future health concerns.
|
| Edit: https://www.cdc.gov/niosh/hhe/reports/pdfs/2003-0206-30
| 67.pd...
| PaulHoule wrote:
| 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.
| krisoft wrote:
| 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.
| simonebrunozzi wrote:
| Why aren't they?
| weinzierl wrote:
| 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.
| thadt wrote:
| 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.
| manmal wrote:
| 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.
| perching_aix wrote:
| 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.
| yababa_y wrote:
| Well, if the exposure isn't chronic, there might be a
| hormetic effect? Radiation dosage is the "classical" example
| of hormesis
| alnwlsn wrote:
| 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.
| adrianN wrote:
| I wonder how they figured out that radon causes that cancer and
| not, say tire particles.
| manmal wrote:
| 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.
| mppm wrote:
| 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.
| jchw wrote:
| 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.
| 1970-01-01 wrote:
| Yes, we're all still waiting for the medical tricorder.
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