Radiocativité

Re 1.1 The background effect

Principle

This experiment should bring the students to the realization that radioactivity is a natural process. Ever since its origin, life on earth has been continuously exposed to ionizing radiation. Radioactive materials in the earth are a major source of th ...

Re 1.2 Random variations in the count rates

Principle

The observation of radioactive transformations is particularly suitable for familiarizing students with the peculiarities of randomly occurring events. The random character of decay processes is clearly recognizable simply from the acoustic detection ...

Re 1.3 Examination of rock samples

Principle

We cannot percept the radiation from radioactive substances with our sensory organs. Of all of the pieces of equipment developed to detect such radiation, the Geiger-Müller counter is the most frequently used one. With the help of this simple experime ...

Re 1.4 Examination of salts

Principle

Potassium belongs to the naturally radioactive substances, alongside uranium and thorium. With its 2.6 percent by weight, it is among the 10 most frequently occurring elements in the earth's crust, and is present in numerous minerals as well as in all ...

Re 1.5 Radioactive minerals as sources of different typesofradiation

Principle

The uranium which is contained in the columbit sample is the mother substance of the uranium disintegration series. The successive products have differing half-lives and are converted one after the other by alpha and beta processes until finally a sta ...

Re 2.1 The influence of distance on the intensity of radia-tion

Principle

Keeping the maximum distance away from a source of radioactivity is one of the most effective ways of of reducing the burden of ionizing radiation.
The quadratic dependence of the dose level on the distance, as given by geometrical consideratio ...

Re 2.2 Range and shielding of alpha radiation

Principle

Because of their high specific ionization capacity in air, alpha particles only have a range of a few centimetres. This is dependant upon their energy E, and can be calculated from the following empirical relationship:

R = 0.476 E1.5 (cm/MeV ...

Re 2.3 Shielding from beta radiation

Principle

As the energy values of the beta particles are distributed continuously over a region of from 0 to a maximum value, the dependence between radiation intensity and material thickness can only be approximately described by the exponential law which is ...

Re 2.4 The distance law pour beta and gamma radiation

Principle

The law of inverse quares is valid for point sources which are isotropic, i.e. radiate out in all spatial directions with the same intensity, and which do not suffer losses by absorption between the source and the irradiated surface. These conditions ...

Re 2.5 The deflection of beta radiation in à magnetic field

Re 2.6 The behaviour of gamma radiation in à magnetic field

Principle

This experiment should be connected with the determination of the deflection of beta radiation in a magnetic field. Conclusions on the physical nature of gamma radiation can be drawn from the result of the experiment, that their radiation intensity is ...

Re 2.8 The back-scattering of beta radiation

Principle

Because of their charge, beta particles are deflected from their direction when they interact with the electrical fields of the shell or the nucleus of the atoms of the irradiated substance. Back-scattering occurs, when the angle of deflection is grea ...

Re 3.1 Filling control

Principle

The specimen tube material absorbs some of the beta radiation from the source of radiation, so that the protective cap should be removed from the counter tube to obtain higher count rates. The filling height should not be known to the students, in ord ...

Re 3.2 Determination of layer thickness

Principle

The method of determining layer thickness with beta back scattering is particularly suitable for double-layer systems in which the two components differ sufficiently in their atomic numbers. For example, the lacquer coating on metals can be controlle ...