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View Full Version : Coherency of light from plastic scintillator



DoYouKnow
2014-Dec-16, 04:36 AM
When I visited fermilab a few years ago, we were given plastic rulers made of a scintillator material. Lately I have been interested in trying to detect TeV gamma rays indirectly by the Extensive Air Showers that they produce.

I know that some of the detectors have used arrays of scintillator setups to detect the source of energetic cosmic rays. My question is, is the coherency of the visible scintillating light identical to the coherency of the input particle, or, is any of that information passed through the scintillating reaction at all? So, if I take a long exposure of the sky, can I see the approximate origin direction of cosmic rays? As I understand it, any extensive air showers from gamma that happen to be in the shower blimp and visible on a single CCD via a scintillator would have the endpoint of the airshower vector lying on the scintillator, so the origin of the vector as apparent on the CCD would naturally be the origin of the cosmic radiation

If the input scintillating particle is a UV photon, do I want to focus on infinity to see the sources, or on the scintillator?

In the near future I'll attempt to measure this with a photodiode, scintillator, and oscilloscope, but for now I have a camera and a plastic scintillator.

I am wondering if I can put the scintillator and camera in a dark place, pointed at the sky with minimal shielding, or even short exposures with no shielding (for UV), and see a universe that's different than what I normally see without scintillator.

Also, I have very little of this scintillator left, is there any cheap place where I can buy sheets of scintillator that are transparent enough to be used as lenses?

DoYouKnow

trinitree88
2014-Dec-25, 12:29 AM
When I visited fermilab a few years ago, we were given plastic rulers made of a scintillator material. Lately I have been interested in trying to detect TeV gamma rays indirectly by the Extensive Air Showers that they produce.

I know that some of the detectors have used arrays of scintillator setups to detect the source of energetic cosmic rays. My question is, is the coherency of the visible scintillating light identical to the coherency of the input particle, or, is any of that information passed through the scintillating reaction at all? So, if I take a long exposure of the sky, can I see the approximate origin direction of cosmic rays? As I understand it, any extensive air showers from gamma that happen to be in the shower blimp and visible on a single CCD via a scintillator would have the endpoint of the airshower vector lying on the scintillator, so the origin of the vector as apparent on the CCD would naturally be the origin of the cosmic radiation

If the input scintillating particle is a UV photon, do I want to focus on infinity to see the sources, or on the scintillator?

In the near future I'll attempt to measure this with a photodiode, scintillator, and oscilloscope, but for now I have a camera and a plastic scintillator.

I am wondering if I can put the scintillator and camera in a dark place, pointed at the sky with minimal shielding, or even short exposures with no shielding (for UV), and see a universe that's different than what I normally see without scintillator.

Also, I have very little of this scintillator left, is there any cheap place where I can buy sheets of scintillator that are transparent enough to be used as lenses?

DoYouKnow

You don't need a dark place. Cover the apparatus with opaque electricians tape. MIT loans out a plexiglas wedge...polymethylmethacrylate..covered in tape..sort of tennis racquet in shape. The scintillation from cosmic rays occurs in the paddle.Some of the photons travel towards the "handle", where a PMT amplifies them....about a million..and a pulse occurs. Two paddles stacked with a counter give some directional sensitivity.
You can buy a gallon of methacrylate monomer @ a craft store. Or online. Polymerize your own shapes, or buy it by common name...plexiglas

trinitree88
2014-Dec-25, 01:17 PM
Merry Christmas to one and all. The tandem paddles have a coincidence counter such that only cosmic rays passing through both within time of flight separation plus fluorescing time are counted. As such they "point" to a directional origin perpendicular to the plane of the individual paddles. They'll give you an alt-azimuthal variation indicating predominantly ambient muon flux, but if you are hoping for an occasional exotic transient, good luck. pete