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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
by 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 agoMy (NaI based) gamma spectrometer disagrees.
- nagrom 10y agoI 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 agoYour 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 agoThe 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
- pif 10y ago> The amount of photons in the scintillator is proportional to the energy deposited. Exactly: it is proportional to the energy deposited in the scintillator! Which, for a cosmic ray, can be a tiny fraction of the total energy. In order to measure the kinetic energy of a particle, you need to stop it. In that case, your detector is called a calorimeter.