Gamma Spectrometry Forum

Hi all,

For those of you fascinated by cosmic rays, Marek Dolleiser (Author of PRA software) has just shared with me a paper documenting his post retirement research on the subject.

In typical Marek fashion, the paper is fascinatingly detailed and leaves no room for hand waving. I read the paper once this morning, but it will have to go over it again slowly to fully understand it. I would just like to point out the clever way in which Marek uses pulse coincidence summing with PRA to analyse his data, AFAIK this is a novel idea.

Abstract
Secondary cosmic rays are particles which originate from a primary high-energy particle com- ing to our planet from the outside space. We can detect them at the surface of Earth. The experiment was carried at my place starting by 2018. After retirement, I had much time. Ob- servation of the cosmic rays was primarily meant to keep me busy. When it results with some significant outcome, I decided to make them available to everybody. This work could be of in- terest of cosmic rays amateur researchers. Their finances are usually minimal, and vast arrays of advanced detectors or usage of satellites are out of the scope. This document is not a scien- tific paper, but more like a story about my adventure, including a personal view on the subject. I am giving a quite detailed description of the used equipment and analysis of the collected data as an example for the eventual followers. Doing one physical experiment yourself can give you more satisfaction and knowledge than reading hundreds of scientific books.

https://www.gammaspectacular.com/marek/ ... icRays.pdf

Enjoy..

Steven

I count as one fascinated by Cosmic Rays. I enjoyed and learned from Dr. Dolleiser's paper. I have also tried to estimate the secondary CR flux with GM tubes, but my efforts look very childish in comparison. I built a "muon telescope" with a viewing window sized to overlap such that 0-180 degree sweep could be performed with 6 positions. I am working on a similar experiment with over-lapping pancake tubes. Dr. Dolleiser's paper might help me come up with a geometry correction for that one. I am using coincident detection logic circuits instead of his novel energy summing method.

I have one question I would ask of him. Why take data over a full 360 degrees? I would think this would be redundant in that results 180 degrees apart have essentially the same test arrangement. I would think it is a safe assumption that our small planet would offer sufficient shielding from below.

I have some preliminary data from my dual pancake secondary cosmic ray (muon) detector. The hardware worked very well. Using just the active area of the lower tube, I get a flux rate of .87 counts/(cm^2 min). I believe 1 counts/(cm^2 min) is a number I have seen as a usual average in literature.

I also did an experiment where I excited the detector with Radium to try and estimate how many coincidence counts might be caused by background gamma. Dolleiser did something like this with stacks of bricks. I was pleased to see that such false counts are less than 1% of my coincidence rate, probably much less. The attached photo show this Radium Test in progress.
I would like to adjust my calculated muon flux rate for the “average solid angle” of the detector, refer to Dolleiser’s equation #5 in his paper.

I think I have converted his equation to cylindrical coordinates well enough to fit my detector geometry, but the WolframAlpha calculator he referenced appears to only do up to triple integers, while both Dolleiser’s equation #5, and my version of it, require a quadruple integration. Dolleiser probably has a work-around for this. I am stuck. If anyone knows how I might calculate this, please respond. Does MathCad have this capability?

This detection of cosmic muons is quite interesting. It seems that one can use a variety of detectors. Some folks in the physics program at MIT (a US technology college in Boston, Mass.) have a website with much information on constructing a scintillator-based detector.

http://www.cosmicwatch.lns.mit.edu/
[broken link removed - Steven]
https://news.mit.edu/2017/handheld-muon-detector-1121

Other downloadable papers and related projects can be found in the links below -

https://www.instructables.com/Detecting ... imple-can/
https://gustavus.edu/physics/concertFil ... Thesis.pdf
https://indico.cern.ch/event/505644/con ... _rev_2.pdf

Links are give for some YouTube videos related to muons and the detection thereof -

https://www.youtube.com/watch?v=86zZuqqi5gU
https://www.youtube.com/watch?v=qQpXGQ4Igks
https://www.youtube.com/watch?v=OtW99aGycEo
https://www.youtube.com/watch?v=4-5iTDagC_U

(The feller doing the below experiment uses some familiar spectrometry equipment)
https://www.youtube.com/watch?v=N02VubBfai0

Rob,

Thanks for posting, I had never seen the last video by the Thought Emphorium, the guys name is Justin Atkin and he does a great job of teaching science. Nice to see my spectrometer being used.

I wonder if it is possible to make a muon detector with two geiger tubes on a continuously rotating platform. Using a stepper motor and recording the angle vs the coincidence counts, one could run the experiment over several days and the create a histogram, of coincidence counts vs. angle. An Arduino and a handful of stuff from RadioShack should do it.

Steven

I believe that one will find the coincidence count rate to be fairly low. It might be more effective to have an automated system that acquires data at a fixed angle for some period of time (day or days?) then advances to the next increment (smallish angle, say 5 to 15 degrees). More data would be acquired for a period of time then repeat. I do not think that there would be much advantage in rotating beyond 180 degrees if detectors are identical. It might be interesting if different detectors are used. In the linked Thought Emporium video both plastic and NaI scintillators were used.

In the US RadioShack stores are long gone. I still have a few bags with the RadioShack logo that contain purchases made many years back. DigiKey, Mouser, Adafruit, Sparkfun, and Newark work well for supplies. Banggood, AliExpress, SeeedStudio, and Allnet have also worked if the desired items are available; wait times to receive product can be more extended to the US.

In the Thought Emporium YouTube video a couple of Gamma Spectacular devices were used with a plastic and NaI detector. A measurement was made of the pulse shape and displayed on an oscilloscope. I was not able to discern the specific location where the oscilloscope probe was placed. It would be quite useful if you were able to show a location on the older Gamma Spectacular devices and newer devices where an oscilloscope probe could be placed. I would really hate to fry (technical term for letting the "magic" smoke out of electronic devices) either my oscilloscope or Gamma Spectacular devices.

Rob,

On the GS-USB-PRO, the BNC connector is connected directly to the low voltage end of the coupling, so if you are using a single wire detector you can connect the BNC to your scope.

If you want to catch those 2.4 µs muons, you will need a Tee on your scope with a 50 ohm terminator, this will shorten the pulse length and allow you to see that second pulse. Note, you will need a scope with a dual pulse trigger function.

On the older GS-1100A I think there was a pin on the board marked RAW, check the trace it should go to the coupling.

Steven

I've been working with the preliminary data of my pancake CR detector to try and calculate a Cosmic Ray Flux that I could compare with what Dolleiser reported. I posted a description of the basic arrangement of my detector, and the data earlier. He reported a zenith angle flux and an equation (#6) to determine the count rate at any angle or to allow integration of the full 2 pi view of the sky. My flux estimates are about a third less than Dolleiser's. I don't know why there is a difference, although I am at a slightly lower altitude (sea level) and latitude (29.6 degrees) than where he is. For what it is worth, I have seen 1 count/cm^2 min as the average muon flux reported a few places, and our results straddle this value. I was mostly checking to see if I was missing counts because of the incomplete view of the sky of the detector. The answer is not many. About 1%. My calculations, which try and follow Dolleiser's, are attached. This file is from a longer report that includes information already posted.

I’m trying the same experiment from though Emporium with 2 gamma scintillator and i was wondering how to connect 2 usb-pro for coincidence counting. In the manual there is written to connect them with an audio crossover cable…. Is that it?