How Do You Calculate the Activity of a Radioactive Sample?

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Homework Help Overview

The discussion revolves around calculating the activity of a radioactive sample based on the counts registered by a Geiger counter positioned at a specific distance from the sample. The subject area involves concepts from nuclear physics and radiation detection.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to derive the activity from the count rate and area, expressing uncertainty about the validity of their calculations. Some participants question whether all emitted particles are detected by the Geiger counter, leading to further exploration of how to account for detection efficiency.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the problem and questioning the assumptions regarding particle emission and detection. No consensus has been reached, but there is a productive dialogue about the factors affecting the measurement.

Contextual Notes

Participants are considering the implications of uniform emission and the efficiency of the Geiger counter in capturing emitted particles, which are critical to accurately determining the activity of the sample.

jumbogala
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Homework Statement


The sample is placed 0.12 m beneath a Geiger counter.

The counter registers 2 counts per second. What is the activity of the sample?

Homework Equations


The Attempt at a Solution


Just a guess. I am making up formulas here so please tell me if they're not even true.

(2 counts/s)/(2E-4 m2) = Intensity = 10 000 counts/s/m2

Then multiply this by the distance to get the activity? So this would give 1200 counts/s?

Is that correct?
 
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Do you suppose that all the particles emitted by the sample are being captured by the Geiger counter?
 
Nope, they're not. But I don't know how to account for that, since I have no idea what percentage are.
 
jumbogala said:
Nope, they're not. But I don't know how to account for that, since I have no idea what percentage are.

What if you assumed that the sample emits uniformly in all directions?
 

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