Question 1 Wheres the radiation gone? You are responding to an atmospheric release of Cs-137 from a fire in a sterilization plant. You grab a GM-based detector with sliding beta window and take readings downwind from the plant. This instrument has an approximate background 304

You obtain the following counts

Probe at ground, window open:

Reading 1 : (100651304 28000) cps

Reading 2 : (100651304 29000) cps

Reading 3 : (100651304 31000) cps

Probe at ground window closed:

Reading 1 : (100651304 27000) cps

Reading 2 : (100651304 - 30000) cps

Reading 3 : (100651304 - 27000) cps

Probe at 1 meter (waist level) window open:

Reading 1 : (100651304 40000) cps

Reading 2 : (100651304 42000) cps

Reading 3 : (100651304 40500) cps

Probe at 1 meter window closed:

Reading 1 : (100651304 45000) cps

Reading 2 : (100651304 52000) cps

Reading 3 : (100651304 54000) cps

Where is the radioactive release with respect to your position? State all assumptions.

Hints

- Find the Minimum Detection Limit (MDA) for this detector ( site your reference)

- Compare your readings against background and MDA.

- Calculate respective standard deviations (N) of your readings. Here N is number of counts.

- Use the table in Lab 1 to help make your decision.

- Use a bar graph with Error Bars (standard deviation) to explain your decision making process.

Plume ok Face up Face up Then: If at waist level: Face down (WO) (WC) B+y B+y Y B+y V AND If at ground level: Face down (WO) (WC) B+y Y B+y 7 B+y 7 u v VVN Plume is elevated Plume is at ground level Plume has passed (ground contamination) Figure 30 - Plume localization Plume ok Face up Face up Then: If at waist level: Face down (WO) (WC) B+y B+y Y B+y V AND If at ground level: Face down (WO) (WC) B+y Y B+y 7 B+y 7 u v VVN Plume is elevated Plume is at ground level Plume has passed (ground contamination) Figure 30 - Plume localization