5 ms·

Any practical use?

nefitty 10y ago
"Conrad and Axani have taken the detector down into the Boston subway, using the changes in the muon count to calculate the depth of the train tunnels." The main point, though, is to expose younger students to undergraduate-level physics concepts cheaply and easily.
CamperBob2 10y ago
It's a great educational project for a physics class, from what I can tell. The article (http://arxiv.org/abs/1606.01196 http://arxiv.org/abs/1606.01196) is nicely detailed and accessible to undergraduates. Good introduction to instrument design and construction, especially if (as the author suggests) the students are asked to write their own analysis software for it. As far as applications go, the article offers a few ideas: 1. Measure the relative depths of subway stations across the city, using the measured muon rates. 2. Test relativistic time dilation on the cosmic ray flux by measuring the flux at various elevations, such as in an airplane or on a mountain, compared to sea level. 3. Investigate correlations between the atmospheric temperature/pressure/humidity and the count rate. 4. Investigate seasonal variations in muon rates. 5. Using multiple detectors, measure the angular muon rate by looking at the coincidence rate. 6. Lower the gain of the circuit to look at high-energy stopping muon events. Investigate whether or not one can see the Michel electron from the muon decay. Tempted to build one, but I don't immediately understand how it discriminates between muons and other forms of ionizing radiation that an ordinary Geiger counter will pick up.
- kaybe 10y ago
  Scintillators are able to resolve particle energy, and can be used to measure a spectrum. Muons have very high energy, which can be used to identify them. For extra certainty, you can use two stacked scintillators and only count a signal if it occurs in both of them within nanoseconds. This also allows determining the rough direction the particle came from since a particle that comes in at a low angle will not hit both detectors. Changing the distance between the scintillators will change the solid angle the instrument can 'see'. (as given by 5 in your list) This guide for a student experiment has more background than the paper you linked: http://home.fnal.gov/~group/WORK/muonDetection.pdf http://home.fnal.gov/~group/WORK/muonDetection.pdf
  - pif 10y ago
    > Scintillators are able to resolve particle energy No, scintillators only detect a particle going through.
    - nullc 10y ago
      My (NaI based) gamma spectrometer disagrees.
      - nagrom 10y ago
        I suspect that this is a question of energy. At high energies, it's difficult/impossible to stop a particle, so you place a row of scintillators out, bend the charged particle path using a magnetic field and measure its displacement (and thus velocity and thus energy). At lower energies, you can stop the particle in, e.g. an NaI detector which is known as calorimetry. Typically, of course, cosmic rays are quite high energy and given the low rate of muon interaction calorimetry is difficult/impossible. A HEP physicist may use both techniques, e.g. by using heavy-metal plates to cause an EM cascade and measure the resultant shower in a crystalline detector. But typically when one talks of scintillator devices (and almost certainly in the case of cosmic rays) one talks of tracking and measuring deflection in magnetic fields if wanting to measure the energy.
      - gnufx 10y ago
        Your NaI detector is rubbish for spectroscopy because of the lousy resolution. High resolution studies in the UK in the 80s corrected several misapprehensions about the physics from attempted spectroscopy with NaI. It was only useful for Compton suppression as far as we were concerned, and soon replaced for that.
    - kaybe 10y ago
      The amount of photons in the scintillator is proportional to the energy deposited. This is described by the Bethe-Bloch equation [1]. Pages 3-6 of this guide [2] have some plots and explanations on what that looks like for different particles. How good that works in practice depends on the energy- and time resolution of the scintillator. Energy resolution depends on how different the light emission is for different energy depositions. Time resolution depends on how quickly the scintillator is back to a dark state (there are cascading effects from the deposited energy and there is a corresponding decay time). Anorganic material (eg NaI) is better in energy resolution, organic material (eg. plastic/polystyrene) is better in time resolution. High energy resolution is good if you eg. want to look at a spectrum of nuclear fission products to find details of the fission process. High time resolution is good because it is easier to resolve different particles and you have a higher probability of a 'pure' signal. [1] https://en.wikipedia.org/wiki/Bethe_formula https://en.wikipedia.org/wiki/Bethe_formula [2] http://home.fnal.gov/~group/WORK/muonDetection.pdf http://home.fnal.gov/~group/WORK/muonDetection.pdf
- gnufx 10y ago
  Not disputing that, but in undergraduate labs you're likely to find research cast-offs, though the only plastic scintillator experiment I've known (albeit 35 years ago) was purpose-built. There was also a Ge(Li) "jelly" counter, and demonstrators who didn't understand pile-up...
pif 10y ago
Why, does it need any?

Any practical use?

"Conrad and Axani have taken the detector down into the Boston subway, using the changes in the muon count to calculate the depth of the train tunnels." The main point, though, is to expose younger students to undergraduate-level physics concepts cheaply and easily.

CamperBob2 10y ago

It's a great educational project for a physics class, from what I can tell. The article (http://arxiv.org/abs/1606.01196 http://arxiv.org/abs/1606.01196) is nicely detailed and accessible to undergraduates. Good introduction to instrument design and construction, especially if (as the author suggests) the students are asked to write their own analysis software for it. As far as applications go, the article offers a few ideas: 1. Measure the relative depths of subway stations across the city, using the measured muon rates. 2. Test relativistic time dilation on the cosmic ray flux by measuring the flux at various elevations, such as in an airplane or on a mountain, compared to sea level. 3. Investigate correlations between the atmospheric temperature/pressure/humidity and the count rate. 4. Investigate seasonal variations in muon rates. 5. Using multiple detectors, measure the angular muon rate by looking at the coincidence rate. 6. Lower the gain of the circuit to look at high-energy stopping muon events. Investigate whether or not one can see the Michel electron from the muon decay. Tempted to build one, but I don't immediately understand how it discriminates between muons and other forms of ionizing radiation that an ordinary Geiger counter will pick up.

kaybe 10y ago
Scintillators are able to resolve particle energy, and can be used to measure a spectrum. Muons have very high energy, which can be used to identify them. For extra certainty, you can use two stacked scintillators and only count a signal if it occurs in both of them within nanoseconds. This also allows determining the rough direction the particle came from since a particle that comes in at a low angle will not hit both detectors. Changing the distance between the scintillators will change the solid angle the instrument can 'see'. (as given by 5 in your list) This guide for a student experiment has more background than the paper you linked: http://home.fnal.gov/~group/WORK/muonDetection.pdf http://home.fnal.gov/~group/WORK/muonDetection.pdf
- pif 10y ago
  > Scintillators are able to resolve particle energy No, scintillators only detect a particle going through.
  - nullc 10y ago
    My (NaI based) gamma spectrometer disagrees.
    - nagrom 10y ago
      I suspect that this is a question of energy. At high energies, it's difficult/impossible to stop a particle, so you place a row of scintillators out, bend the charged particle path using a magnetic field and measure its displacement (and thus velocity and thus energy). At lower energies, you can stop the particle in, e.g. an NaI detector which is known as calorimetry. Typically, of course, cosmic rays are quite high energy and given the low rate of muon interaction calorimetry is difficult/impossible. A HEP physicist may use both techniques, e.g. by using heavy-metal plates to cause an EM cascade and measure the resultant shower in a crystalline detector. But typically when one talks of scintillator devices (and almost certainly in the case of cosmic rays) one talks of tracking and measuring deflection in magnetic fields if wanting to measure the energy.
    - gnufx 10y ago
      Your NaI detector is rubbish for spectroscopy because of the lousy resolution. High resolution studies in the UK in the 80s corrected several misapprehensions about the physics from attempted spectroscopy with NaI. It was only useful for Compton suppression as far as we were concerned, and soon replaced for that.
  - kaybe 10y ago
    The amount of photons in the scintillator is proportional to the energy deposited. This is described by the Bethe-Bloch equation [1]. Pages 3-6 of this guide [2] have some plots and explanations on what that looks like for different particles. How good that works in practice depends on the energy- and time resolution of the scintillator. Energy resolution depends on how different the light emission is for different energy depositions. Time resolution depends on how quickly the scintillator is back to a dark state (there are cascading effects from the deposited energy and there is a corresponding decay time). Anorganic material (eg NaI) is better in energy resolution, organic material (eg. plastic/polystyrene) is better in time resolution. High energy resolution is good if you eg. want to look at a spectrum of nuclear fission products to find details of the fission process. High time resolution is good because it is easier to resolve different particles and you have a higher probability of a 'pure' signal. [1] https://en.wikipedia.org/wiki/Bethe_formula https://en.wikipedia.org/wiki/Bethe_formula [2] http://home.fnal.gov/~group/WORK/muonDetection.pdf http://home.fnal.gov/~group/WORK/muonDetection.pdf
gnufx 10y ago
Not disputing that, but in undergraduate labs you're likely to find research cast-offs, though the only plastic scintillator experiment I've known (albeit 35 years ago) was purpose-built. There was also a Ge(Li) "jelly" counter, and demonstrators who didn't understand pile-up...

pif 10y ago

Why, does it need any?