2. Methods



Ionizing smoke detector (Must contain Americium)
Gloves to handle Americium
Wooden Ruler


Geiger Counter

Data Logger

Retort Stand

Lab Coats

Preparation for experiment
  1. Wear lab coats that are of the right size
  2. Put on the safety goggles
  3. Ensure that there is no one playing in the lab
  4. Experiment in an area away from the people in the room if there are any, preferably a corner
  5. Keep the radiation source in a metal container until it is needed to prevent the radiation from ‘escaping’

Preparing the smoke detector
The smoke detector that we had gotten like many other smoke detectors are very well protected and was very difficult to bust open to get the americium source.
Figure 4

First, we drilled the notches as there were no screws on the outside.
Figure 5

After that, we dismantled the whole smoke detector and these are the parts.
Figure 6

The part left is this, a cover which is used to prevent the radiation. Inside it was metal part which blocked out most of the alpha radiation.
Figure 7

After removing that, we finally got to the americium source which is the portion at the metal ring.

Distance of GM Counter from radiation source
  1. Place both retort stands together such that it forms an L-shape
Figure 8
  1. Place the radiation source in the center area of the base of one of the retort stands

  1. Adjust the arm of the retort stand to a length such that the clamp is directly above the radiation source
Figure 8
  1. Clamp a ruler in the arm of the adjusted retort stand until it is tight
  2. Adjust it such that the bottom of the ruler is at the top of the radiation source (Note : Twisting the Geiger Counter while it is clamped is better than moving the arm as it is much easier)

  1. Clamp the Geiger Counter in the other retort stand such that the bottom of the Geiger counter is clamped and not the middle.

  1. For the first result, lower the Geiger Counter to touch the the radiation source for 0.1cm

  1. Leave the Geiger Counter to measure the radiation for 1 minute

  1. Adjust the Geiger Counter to the next distance (To adjust the Geiger Counter at shorter distances such as millimeters, it is better to screw the Geiger Counter in with the hands instead of moving the arm of the retort stand up and down)

  1. Repeat steps 8 to 9 for distances 0.1cm, 0.2cm, 0.3cm, 0.4cm, 0.5cm and 0.6cm

  1. Record the results

  1. Calculate the average amount of counts for each length

  1. Record the data in a table which shows the correlation between the number of counts and the distance from the radioactive source.(Americium-241)

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