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Abstract

The purpose of this investigation was to measure the effects of distance, and shielding materials water, lead, aluminum, cloth and no shield on radiation activity (counts per 10 seconds) detected from a gamma source, Cobalt-60, a beta source, Strontium-90, and an alpha source, Polonium-210. The procedure consisted of connecting the radiation monitor to the DIG/SONIC 1 of the computer interface Logger Pro. From there, I set up a ruler and measured the appropriate distance from the source to the monitor, then ran 36 trials for each test. For shielding tests, I placed lead, aluminum or cloth up against the monitor, then repeated the 36 trials. For water, I placed the source into a beaker/bucket, filled the appropriate distance with water, placed the monitor at the water’s height, then ran 36 tests for each distance and source. The average radiation counts for the source test measured 0.15m from the source were 5 (SD = 2), 4 (SD = 2) and 10 (SD = 3). The average radiation counts .15m from the source with a shielding material in front of the monitor were 10 counts for no shield, 8 counts for

lead, 9 counts for aluminum, 7 counts for the cloth, and 6 counts for water. The average radiation counts for cobalt-60 was 15 counts from .10m(SD = 4), 10 counts from .15m(SD = 3), and 7 counts from .20m(SD = 2). These tests show distance, source, and shielding do affect radiation safety and that radiation should be respected for its essentiality.

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My Research Question

Background Information

Radiation has been studied thoroughly from multiple aspects. Different sources and their effects are known, how shielding can be important, and why distance and time is important for safety.
Multiple research papers have been conducted about radiation including some by Western Oregon University, Stanford University, USNRC, and more.

Purpose:

The purpose of this investigation is to measure the effects of distance and shielding materials water, lead, aluminum, cloth, and no shield on radiation activity (counts per 10 seconds) detected from a gamma source, cobalt-60, a beta source, strontium-90, and an alpha source, polonium-210.

Hypothesis:

If the distance between a radioisotope and the radiation monitor is increased then the radiation exposure will decrease because particles have spread out more, in random directions.
If I place water in between the radiation source and the monitor then less radiation should be monitored than if I would put metals or other materials such as aluminum, cloth, lead or no shield in front of the monitor because particles should be stopped easier by the density of the water container.
If a radioisotope emitting gamma radiation is placed in front of the monitor, more counts of radiation should be monitored than alpha or beta radiation because of the powerful rays the radioisotope produces.

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Methodology

Procedure:

For testing, I connected the radiation monitor to DIG/SONIC 1 of the computer interface of Logger Pro. I used a ruler to accurately measure the distance between the source and the monitor, and conducted 36 trials for each test. For each shielding material, I placed the material in front of the monitor and conducted the same amount of tests. I measured 3 distances (.10m, .15m, and .20m) as well as 3 sources for all hypothesis I tested.
The three sources tested were: cobalt-60(gamma), strontium-90(beta) and polonium-210(alpha).
The five shielding materials were: lead, aluminum, cloth, water, and a control (air).
When testing for the first hypothesis I controlled the variables by using the same individual sources for each test, measuring out the precisely same distance for each test, and testing in the same area.
When testing for the second hypothesis: I controlled the variables by using the same thickness for each material, placing the material in the same spot, and repeating all the controls I had for the first hypothesis.
The data was collected by using a radiation monitor attached to my computer. There, I used the DIG/SONIC 1 of the computer interface of Logger Pro. The data points were set to a graph and there I completed tables and graphs summarizing the data.

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Methodology

Apparatus for measuring radiation counts with water shielding.

All photos taken by experimenter.

Apparatus for measuring radiation counts with cloth shielding.

Apparatus for measuring radiation counts with aluminum shielding.

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Results

Data

The average radiation counts per 10 seconds for the alpha, beta and gamma as measured 0.15m from the source were 5 (SD = 2), 4 (SD = 2) and 10 (SD = 3) respectively.
The average radiation counts per 10 seconds .15m from the source with a shielding material in front of the monitor were 10 counts for no shield, 8 counts for lead bar, 9 counts for the aluminum sheet, 7 counts for the cloth sheet, and 6 counts for the water container.
The average radiation counts per 10 seconds for the gamma-emitting isotope was 15 counts from .10m away(SD = 4), 10 counts from .15m away(SD = 3), and 7 counts from .20m away(SD = 2).

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Results Continued

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Interpretation of Results

The results of my experiment mean that different sources can affect the damage radiation does, distance is greatly significant when dealing with radiation, and if you have a shield, the danger of severe radiation exposure drop dramatically.
Possible errors that may have occurred when dealing with this experiment is background radiation. I was not expecting the alpha radiation tests to increase in counts when the distance was increased, but this might have had to do with the background radiation counts.
Most of the tests showed that beta radiation had higher counts than alpha radiation. I was not expecting this, as alpha radiation is known to be the most ionizing radiation, which in turn produces more counts. However, while examining the samples used, it was found that the alpha-emitting sources have a much shorter half-life than the beta-emitting and gamma-emitting sources I used, which may have in turn caused it to have significantly less counts.
Background radiation was uncontrollable with the interface of Logger Pro I used. However, I ran a test to see an average of background radiation in the air at any time.

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What conclusions did you reach?

This has a powerful real-world connection, because it shows the importance of the three factors of radiation safety: shielding, distance, and time. If more people could discover this, it may show them to respect radiation more and the harm it can do, as it is all around them. Although it is not likely they will not be dealing directly with sources such as the ones I tested, it will give them a brief overview of its importance.
The results addressed the research question as a success because the question was answered and with a thorough explanation as to why.
My first hypothesis was partially supported. My second and third hypothesis were both strongly supported.
Various scientists dealing with radiation might be interested in this lab, as it can give them an insight into how radiation can affect them from the different distances, or as they’re being shielded by these common materials. For someone starting to learn about and discover radiation, as I was months ago, it can be important for them to know how following these important principles can significantly lower their chances of exposure/damage.

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References

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[Accessed: November 26, 2020].

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https://www.degruyter.com/view/journals/ci/41/1/article-p27.xml?language=en

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Test 1: Boukhris, I., Kebaili, I., Al-Buriahi, M.S., & Sayyed, M.I. (2021). Radiation shielding properties of tellurite-lead-tungsten glasses against gamma and beta radiations. Journal of Non-Crystalline Solids, 551(120430). https://doi.org/10.1016/j.jnoncrysol.2020.120430

Test 2: The effects of time, distance, and shielding on radiation exposure. (n.d.). Retrieved January 8, 2021, from https://www.bio-link.org/home2/sites/files/tdslab.pdf

Test 3: Laboratory 5: Time, distance, and shielding. (2008). Radiation and Life, 99(102), 1-5.

http://faculty.uml.edu/tregan/99.101.801/topics/LECTURE%205.PDF

Test 4: Radioactivity (Research Report No. 13N). (2018, April 11). https://www.usna.edu/ChemDept/_files/documents/112pdf/2018%20Documents/exp-13N-s18-radioactivity-FV.pdf

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