Radiation Q: C Answr w/1cm Alum Plate?

Thread starter User1265
Start date Oct 4, 2019
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Radiation

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The discussion centers on the effectiveness of a 1cm thick aluminum plate in blocking beta particles from a radiation source. It is argued that if the surface is 6 cm from the radiation detector, all beta particles should be stopped by the aluminum. However, it is noted that the count rate remains unchanged even when the source is removed, suggesting that other factors are influencing the readings. This indicates that the presence of beta particles may not be the only contributor to the detected radiation. The conversation highlights the complexity of radiation detection and the need for careful analysis of the data.

Oct 4, 2019

User1265

Homework Statement: 12. A radioactive source is placed 6 cm from a radiation detector sensitive to all
forms of ionizing radiation, and records 74 counts/minute. When a 1 cm
thick aluminium plate is placed in the gap then the count rate falls to
45 counts/minute. If the source is removed entirely then the count rate
remains the same. If the aluminium plate is removed and the source is
placed 2 cm from the detector, the count rate rises to 5000 counts/minute.
What forms of radiation does the source emit?
A alpha only B beta only
C alpha and beta D alpha and gamma

Why is the Answer A and Not C?

Relevant Equations: Alpha, beta gamma

I thought the answer was C because what's not to say when surface is placed 6 cm from radiation detector beta particles are also present, and that surely all beta particles would be stopped with a 1cm thick aluminium plate?

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Oct 4, 2019

kuruman

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You need to take into account the observation that when the source is removed entirely, the count rate remains the same.

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