Alpha, Beta, Gamma Radiation
(Download the MS Word version of this document.)
Procedure: Setting up the calculator and data collection device.
Setting up the calculators and CBLs with a Radiation Monitor.
- Use a CBL II or a LabPro.
- Plug in a Vernier power source.
- Link an 83+ calculator to the data collection device. The calculator needs the program DATARAD.
- Select DATARAD from the PRGM menu. If it is archived, go to 2nd, MEM; 2: Mem Mgmt/Del; 7:Prgm Arrow down to DATARAD and hit ENTER to remove from archive.
- Start the program.
- Go to 1:Setup
- 1:Set interval
- 2:Set interval; Enter 20 seconds
- 1:OK
- 2:Background Correction
- 1:Perform now
- 1 Interval Enter
Procedure 1: Penetrating Ability
- Using forceps, place a gamma radiation source on the ruler 5.0-cm from the detection unit. Select 6: single interval from the menu on the calculator screen.
- 2:Start
- After the 20-second interval, the calculator will show the counts/interval and the corrected counts/interval. That is the count with the background radiation subtracted out. It will also multiply by three to show corrected counts/minute. This is the number that you should record. Press Enter.
- Without moving the gamma source, place a piece of cardboard between the source and the detector.
- Select 2:Start.
- Record your data.
- Repeat with a glass plate, and a lead plate.
- Change to a beta source and repeat. Record your data.
- Change to an alpha source and repeat. Record your data.
| Source | CPM No Barrier |
CPM Cardboard |
CPM Glass |
CPM Lead |
| Gamma | ||||
| Beta | ||||
| Alpha |
Questions
1. Which shielding materials were effective in reducing the intensity of each type of radiation?
2. How do the three types of radiation you tested compare in their penetrating ability?
3. Which of the three materials is most effective in blocking radiation? Which is the least effective?
4. What properties of a material appear to affect its radiation-shielding ability?
Procedure 2: Shielding Effects
This procedure is much like the preceding one, except that you will only use a gamma source. You will experiment with the amount of each material used as a shield in order to drop the count to within 5 counts/minute of background. You should use the same calculator procedure as you did with Procedure 1. This time, however, use one piece of cardboard, 2 pieces, 3 pieces, etc. Then switch to glass, and then to lead. Record your results in counts/minute.
| Cardboard | Glass | Lead | |
| 1 piece | |||
| 2 pieces | |||
| 3 pieces | |||
| 4 pieces |
Questions
1. How effective was doubling the shield thickness in blocking the radiation intensity?
a. for cardboard?
b. for glass?
c. for lead?
2. When you have a dental X-ray, your body is shielded with a special blanket. What material would be a good choice for this blanket? Why?
3. Which type of nuclear radiation from a source outside the body is likely to be most dangerous to living organisms?
4. If you ingested a radioactive source, which source would be the most damaging to a living organism? Why?
Procedure 3: Effect of Distance on Intensity
- Press Enter to return to the main menu.
- 1:Setup
- 5:Event with entry
- Place a beta source on the ruler 4.0-cm from the detector.
- 2:Start Enter
- Enter Value: 4.0
- Move source to 4.5 cm.
- 2:Start Enter
- Enter Value: 4.5
- Repeat for 5.0 cm, 5.5 cm, 6.0 cm, and 6.5 cm, 7.0 cm, and 8.0 cm.
- Press STO to stop.
- 3: Graph
- Enter
Questions
1. By what factor did the intensity of radiation (in cpm) change when the initial distance was doubled?
2. State the mathematical relationship between distance and intensity. You might want to use the 4:Analyze feature to help you with this question.
Adapted by Carol B. Brown, Saint Mary's Hall, San Antonio, TX, from Chemistry in the Community (4th Ed.), W.H. Freeman.
