Abstract

We devised this experiment to find out if there was any way to shield an area from incoming muons. We created a magnetic field using a total of 11 neodymium magnets, in order to create a magnetic field that could possibly bend or deflect the paths of muons traveling vertically. Set to a 4 fold coincidence, our detectors were spaced out about 0.5 meters each in a stacked configuration, creating a smaller angle of acceptance for muons to pass through all 4 detectors. Magnets were first placed between the middle detectors, then above all detectors when results were miniscule. Overall we found that count rates were lower with the addition of a magnetic field by ~0.1 counts per second, compared to control runs without magnets. Magnetic fields seem to be a viable means of shielding from muons, though longer data runs and more powerful magnets must be used to fully show the effects of magnetic shielding.

Introduction

Muons have a relatively small mass of .106 GeV/c^2. Therefore, we were hoping that the magnetic force applied by neodymium magnets would be enough to deflect and shield muons. The Earth's magnetic field is .31 Gauss which would be how we later calculated the strength of our permanent magnet's field.  

 Investigative Question:

Can an area be shielded from muons by means of a magnetic field?

Procedures

We started first by calibrating our detectors so that there would be a plateau. We had detectors A,B,C, and D set at .675V, .76v, .73V, and .78V respectively. At first we started with all 4 detectors stacked vertically with about .5m between each one and 4 neodymium magnets placed between detectors B and C. Using trigonometry we were able to calculate that with this setup our detectors would see 9.8% of the sky. Additionally, muon detectors were placed against a solid wall to shield muons from that direction, and we concluded from tests that the muon emissions from the direction of the wall were minimal. After seeing a small but seemingly insignificant change in muon count rate we moved the magnets so that they would sit above detector A thinking that if we put the magnets higher the curvature would be more significant by the time the muons reached detector D. Thus, more of them would possibly bend outside of the field of the detector. When we moved the magnets we also added 7 smaller permanent magnets to smooth out the total magnetic field. The combined field had a strength of .3 Gauss at 16 cm which we measured with a compass. When the compass would turn towards our magnets we would know that our magnetic field was the same strength as Earth's. We alternated between 19 hour and 5 hour data runs, both with and without magnets in order to have a control. By comparing the control to the data tests we would be able to see whether there was any significant change in muon rates.

Results

We were able to calculate that with the amount of force our magnets would apply on the moving muons would be enough to deflect them about 5.73 x 10^-2 degrees. At first we thought that this small of an amount of deflection would make an unnoticeable change in the count per second rate, but when we ran our trials for long enough the error bars became small enough to see a consistent decrease in the count rate when we added the magnets and then another decrease when we raised the magnets to the top of our setup. With the addition of magnets, Muon count rates were noticeably decreased; tested runs were about 0.1 counts/sec less than the control runs, which ran for the same amount of time.

Discussions & Conclusions

Our results showed that when magnets were added the muon count per second rate decreased consistently. After each modification to our setup, count rates decreased enough so that our error bars would either barely overlap, or not overlap at all. We conclude that magnets are a viable way to shield muons. However, the fact that our results were not very consistent with our calculations may indicate other outside factors were present in the environment. Future tests would most likely require an altered setup, with greater distances between detectors, more magnets in terms of quantity and strength, experimentation with electromagnets, and possibly, substantial shielding around the entire setup to ensure that only muons coming straight down would be accepted.

Bibliography

K&J Magnetics Inc. "Magnetic Force Calculator." K&J Magnetics. N.p., n.d. Web.