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Separating Model Radiation With Two Screens 5 questions
Separating Model Radiation With Two Screens
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A classroom simulation records alpha particles and gamma photons from a model source. The detector counts either type as one event. Screen P stops all alpha particles and passes all gamma photons in the model. Screen Q stops half of both types. The readings are expected counts for equally long recordings, with the background already removed.
| Condition | Expected count |
|---|---|
| No screen | 80 |
| Screen P only | 50 |
| Screen Q only | 40 |
Question 1
Which reading directly measures the gamma contribution in this model?
- 80 with no screen
- 50 with screen P
- 40 with screen Q
- The sum of the two screen readings
Question 2
Calculate the alpha contribution to the no-screen reading. Show how the gamma reading is used.
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Question 3
Explain why the Q-only result would fit a different alpha–gamma mixture as long as the no-screen total stayed at 80.
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The class combines P and Q in the same line. In the simulation each screen still passes the same fraction of what reaches it.
Question 4
Predict the expected count with both screens and explain what reaches the detector.
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In a later test, the records include the same unknown background count. With no screen the total is 90, with P only it is 60, and with P and Q it is 35. The screens affect only the source contributions. The background enters after the screens.
Question 5
Calculate the common background count from the two readings involving screen P. Show how the model for Q enters the calculation.
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