Let's measure radiation. A sample that acquisition is easy and safe is low-salt used for the dietary therapy for high blood pressures.(C)2004-2006 All rights reserved by Y.Onodera.
Weight distribution: Sodium chloride 50%(NaCl) and potassium chloride 50%(KCl). You can get it in a supermarket.
0.0117% of the potassium in a nature is 40K of radioisotope. 40K emits a beta ray.
Calculating from an atomic weight, 3mg per 100g of this low-salt 40K is included.
The salt (NaCl 99%) which does not contain potassium chloride for comparison is also prepared.
Preparation
- Put the gas of a lighter into an air Geiger Mueller counter. Butane gas is heavier than air.(Air:Butone=1.00:2.08). It takes 10 seconds. Butane gas is flammable gas. Be careful not to ignite.
- Measure a background. A relative dose of radiation is measured on the basis of this.
- Wrap a sample to use easily. A beta ray passes a wrap.
Tips on measurementMeasurement result
- Butane gas slightly escapes from a wrap gradually. Put in gas before measurement. You may have a experience that the helium gas balloon has shrunk on the next day.
- Power on and wait until the operation voltage is stable. A background is stable.
- Keep away the sample which is not measured several meters from a Geiger-Muller counter. To keep low background. A beta ray progresses the inside of air several meters, colliding with a molecule. You can observe this phenomenon with a misty box.
- Since measurement is accompanied by the error, it is good to carry out a sample several times and to average.
- Don't wrap a sample doubly.
Sample First[cpm] Second[cpm] Average[cpm] Background 11 9 10 Low salt(NaCl+KCl) 25 21 23 Salt(NaCl) 9 13 11 glow tube starter(Fluorescent Starter) 2111 2173 2142
ConsiderationAll the food containing potassium emits radiation.
- The low-salt containing potassium shows 2 times the value compared with a background.
- Natural salt shows a slightly larger value than a background.
- The promethium 147Pm is used for the old glow tube starter, 147Pm emit the beta ray. The beta ray is protected by glass and does not leak. Long luminous paint is used instead of the radiation element, and then the latest glow tube starter does not have radiation.
- In addition, there is a mineral-rich sediment of a hot spring as a sample which can be obtained comparatively safely. It is known that the radiation element is contained in mineral-rich sediments, such as a radium hot spring.