Activity 5

Pulling radon out of the air

Your teacher will tell you whether you are doing Level 1 (Phases 1 to 3) or Level 2 (all five phases plus decay readings). Predict first, then observe, then explain.

Name Partner(s) Date

Before you start

Your level

Level 1, demo, Phases 1 to 3 Level 2, full investigation, all five phases

Predict, before Phase 1

Two questions about the air

Question 1. You vacuum floor-level indoor air through a tissue and place it near the detector. Compared with the background, the tissue will give...

Clearly more alpha tracks About the same as the background Fewer alpha tracks

Question 2. After opening the windows and airing the room for 20 minutes, the count from a new tissue will...

Go up compared with the un-aired tissue Stay about the same Go down compared with the un-aired tissue

Explain your reasoning.

Predictions locked. You will find out at the bench.

Observe, Phases 1 to 5

Alpha counts across all phases

Settings for every phase: Tracking mode, Sum on, 900 frames, 1 s each, 15 minutes total. Record the alpha blob count and start time for each phase.

Phase	What you did	Alpha blob count	Start time	Notes
1	Background, windows closed
2	Clean tissue (control)
3	Indoor air, un-aired room
4	Outdoor air through window
5	Indoor air, after airing

Observe, Level 2 only: decay readings

Extra readings from the Phase 3 tissue

Keep the same tissue from Phase 3. Take three more readings one hour apart on the same day, then two per day on the next two days. Record alpha and worm (electron) counts separately.

Reading	Date and time	Alpha blob count	Worm count
Phase 3 (reference)
Day 1, reading 2
Day 1, reading 3
Day 1, reading 4
Day 2, morning
Day 2, evening
Day 3, morning
Day 3, evening

Sketch or describe the shape of the alpha-count-vs-time graph from your decay readings.

Using your decay data, estimate the mean-life of the radon decay products. Show your working.

Explain

What does it mean?

Compare the alpha counts across the five phases. Did Phase 3 give clearly more than Phases 1 and 2? Did airing the room bring the count back down? If the counts were similar across all phases, what might explain that? Does finding radioactivity in indoor air mean the room is dangerous? Justify your answer.

Your predictions

Keep these in mind when the tissue goes near the detector.