Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: scientizscht on 02/02/2019 13:30:14
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Hi
we know that we can detect electric field (btw how?) that is generated by static charged items.
We also know that we can detect electromagnetic field (btw how) from charged items that move
Can we detect the above but for radiological beams/field?
Ie static and moving radioactive items?
Thanks
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we know that we can detect electric field (btw how?) that is generated by static charged items.
We also know that we can detect electromagnetic field (btw how) from charged items that move
Electric and magnetic fields are fields of force which can produce either attraction or repulsion. A device with its own intrinsic electric charge or magnetic field would therefore respond to any such outside applied field. Any resulting force could therefore theoretically be measured with sensors. Alternatively, the formation of an electric current in a detection device could also be used to measure the presence and strength of an outside field (magnetic fields can produce electric currents under the right circumstances).
Can we detect the above but for radiological beams/field?
Ie static and moving radioactive items?
Thanks
Geiger counters can detect radiation: https://en.wikipedia.org/wiki/Geiger_counter
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We detect ionsing radiation by counting the ions it produces in a gas, liquid or solid.
The simplest device consists of two electrodes separated by air. If you apply a polarising voltage between the elctrodes, any ions generated in the space between them will be attracted to the electrodes and a current will flow proportionate to the flux of radiation. If you increase the potential gradient and add a "quenching" gas, the number of ions produced per incident photon depends on the photon energy and each photon produces a small current pulse proportional to the photon energy. At higher voltage gradients the ions accelerate and produce a cascade of secondary ions so you get a very robust and sensitive "geiger muller" detector that doesn't discriminate photon energy but gives you a large pulse for every absorbed photon.
Energetic photons can produce fluorescence in liquids and solids. The resulting visible photons are easily detected by a photomultiplier tube. Liquid "scintillation counters" can be used to detect α radiation that is difficult to detect by other means because it has a very short range in solids so generally doesn't penetrate the walls of a geiger counter.
Ionisation in solids generates electron-ion pairs just as in liquids and gases. If the solid is a semiconductor junction area, the diode effect can cause a current to flow in an external circuit with no applied polarising voltage: the resulting detector can be very small and extremely robust, and is particularly handy for characterising x-ray beams in radiography and radiotherapy.
Electrons released by ionisation in solids can be trapped by defects in the crystal structure, then released by excitation with a laser or heat, producing characteristic optical radiation as they return to their ground state. This is the basis for most "personal dosemeters" worn by radiation workers.
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Becquerel (https://en.wikipedia.org/wiki/Henri_Becquerel#Experiments) first detected radiation when he placed a sample of uranium-bearing rock on photographic slides. The radiation blackened the photographic slides. This led to early dosimeters based on photographic film.
Also see: https://en.wikipedia.org/wiki/Dosimeter
Real-time radiation visualisation is possible with a cloud chamber. By placing the cloud chamber in a magnetic field, it is possible to distinguish the charge and energy of different particles.
See: https://en.wikipedia.org/wiki/Cloud_chamber
But most radiation sensors today use the electronic detectors described by alan.
There are some kinds of radiation that are very hard to detect, like neutrinos. For these, you need extremely large detectors, like Ice Cube, which is 1 cubic kilometer of ice, at the south pole.
https://en.wikipedia.org/wiki/IceCube_Neutrino_Observatory
It is thought that there may be other types of radiation that are even harder to detect, in the form of Dark Matter - which we have not been able to observe to date, despite a variety of experimental attempts.
See: https://en.wikipedia.org/wiki/Category:Experiments_for_dark_matter_search
The above discussion relates to detecting moving radioactive particles, after they decay. There is another sense of detecting moving radioactive materials before they decay, ie before they can be assembled into a weapon. This is controlled by various methods, including:
- Nuclear non-proliferation treaty verification organisation
- Export controls
- Monitoring the concentration of ores at source, and after refining, and in use to detect any diversion
- Labelling radioactive materials
- Searching for background radiation with characteristic energy signatures at airports and shipping ports
- Tracking sales and usage of materials used in nuclear refining and weapons
- Tracking electrical energy usage to detect undeclared enrichment plants
- No doubt monitoring the location and employment of people with relevant skills
See: https://en.wikipedia.org/wiki/Treaty_on_the_Non-Proliferation_of_Nuclear_Weapons
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"Can we detect flow of radioactivity?"
No
Radioactivity is a property of some materials; it doesn't flow.
It's a bit like colour. Some things, like the river thames, are brown.
You can say that the Thames flows, but you can't say that brown flows.
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...and the Pedantry Award goes to....
(but you are right, of course)
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...and the Pedantry Award goes to....
...Someone involved in pedantry, rather than someone trying to find out what the OP is actually asking
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Indeed, but
Can we detect the above but for radiological beams/field?Ie static and moving radioactive items?
requires creative guesswork rather than interpretation.
However for those wedded to the literal, the answer is Project Cyclamen, which is a system of passive electronic detectors based on some or all of the techniques I outlined earlier (plus neutron detectors) operated by UK Border Force, for detecting undeclared radioactive material entering the UK. We have had some interesting incidents, including all the brass instruments of the London Philharmonic Orchestra which were packed on a pallet at Tokyo airport just as the rain blew in from Fukushima.
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A 2009 report to UK Parliament on Project Cyclamen: https://publications.parliament.uk/pa/cm200809/cmselect/cmpubacc/336/9030910.htm
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However for those wedded to the literal, the answer is Project Cyclamen,
Project cyclamen seems interesting but, as far as I can tell, it measures the movement of radioactive material, not radioactivity per se.
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The radiation detectors at the LHC are extremely large and complex, despite the fact that the "C" in CMS stands for "Compact".
https://en.wikipedia.org/wiki/Compact_Muon_Solenoid
https://en.wikipedia.org/wiki/ATLAS_experiment
There is an existing telescope array which detects high energy cosmic rays - high-energy atomic nuclei which are thought to be produced in extreme environments like neutron star collisions, black hole accretion disks, etc..
https://en.wikipedia.org/wiki/Pierre_Auger_Observatory
A proposed new telescope, the Cherenkov Telescope Array will search for gamma rays from our galaxy and beyond.
Gamma rays are one form of radiation from radioactive substances - it is electromagnetic radiation with extremely high energy.
See: https://en.wikipedia.org/wiki/Cherenkov_Telescope_Array
These telescopes are designed to detect radiation with far higher energy than can be generated by the Large Hadron Collider.
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However for those wedded to the literal, the answer is Project Cyclamen,
Project cyclamen seems interesting but, as far as I can tell, it measures the movement of radioactive material, not radioactivity per se.
Since Cyclamen doesn't always discriminate between radionuclides but measures count rate, "activity" is measured in becquerels (mean count rate per second), and legitimate packages have a declared activity and are referred to on the Notification To Captain and all ground storage and movement documents by species and activity, the trade jargon is indeed "movement of radioactivity".
Nothing pleases emergency responders, the Home Office, Air Traffic Control and the travelling public quite as much as a public quibble about nomenclature whilst the runway is closed.
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the trade jargon is indeed "movement of radioactivity".
And the reality is indeed, "movement of radioactive material".
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"Can we detect flow of radioactivity?"
No
Radioactivity is a property of some materials; it doesn't flow.
It's a bit like colour. Some things, like the river thames, are brown.
You can say that the Thames flows, but you can't say that brown flows.
What malarkey! a bit like colour! lol please. explain with real facts.
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the trade jargon is indeed "movement of radioactivity".
And the reality is indeed, "movement of radioactive material".
I concur with alan calverd, i'm such as suck up! lol
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I hereby disassociate myself from any semblance of concurrence, for fear of reputational contamination.
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I hereby disassociate myself from any semblance of concurrence, for fear of reputational contamination.
:-)
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What malarkey! a bit like colour! lol please. explain with real facts.
I did.
You should try it some time.
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I think radiation cannot be detected by human senses. A variety of handheld and laboratory instruments is available for detecting and measuring radiation
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I think radiation cannot be detected by human senses. A variety of handheld and laboratory instruments is available for detecting and measuring radiation
I am surprised that you think that and you are not sure about that.
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I'm fairly sure that my eyes detect radiation from the Sun, from this computer screen etc.
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Hi
we know that we can detect electric field (btw how?) that is generated by static charged items.
We also know that we can detect electromagnetic field (btw how) from charged items that move
Can we detect the above but for radiological beams/field?
Ie static and moving radioactive items?
Thanks
Radiation is a flow of particles, mostly nuclear or electric particles. So you're asking about the flow of a flow.