Detection of radioactivity

Question 1

______________ is the radiation that is always present around us in the environment

Answer 1

Background radiation

Question 2

Sources of background radiation

Answer 2

Question 3

Although most background radiation is natural, a small amount of it comes from artificial sources, such as____________ (including X-rays)

Answer 3

Medical procedures

Question 4

When radiation passes close to an atom, it knocks out ____________, ionising the atom

Radiation detectors work by detecting the presence of these ions or the chemical changes that they produce

Answer 4

electrons

Question 5

Examples of radiation detectors include:

Answer 5

Photographic film (often used in badges)

Geiger-Muller (GM) tubes (Picture attached)

Ionisation chambers

Scintillation counters

Spark counters

Question 6

Answer 6

192 counts per second

Question 7

A GM-tube is the most useful radiation detector used for determining the intensity of a beam of radiation or for counting individual charge particles.

When ionizing radiation enters the tube through the thin mica window, it collides with the large argon atoms and ________ them.

These free _______ will then accelerate towards the fine wire anode placed along the axis of the cylindrical cathode. These accelerated electrons will cause further ionization of the argon atoms by colliding with them, thus producing an ‘avalanche’ of electrons which are collected almost at once by the anode.

The positively charged ions will be attracted towards the ________. The collection of the electrons and the argon ions at the electrodes produces a current pulse. This current pulse is then amplified and fed to a ratemeter.

Answer 7

ionizes, electrons,cathode

Question 8

The diffusion cloud chamber is the device for making visible the paths of ionizing emissions.

It consists of a container containing air. At the top of the chamber, a row of felt strips is soaked in _________. The lower part of the chamber is cooled by solid carbon dioxide or liquid helium. The alcohol evaporates into vapour and continuously diffuses downwards. It then becomes supersaturated at the centre of the chamber (i.e., the air holds more vapour than it normally could).

When emissions from the radioactive substances are placed in the chamber, the emissions will cause ________along its paths. The ionized air molecules will attract the vapour molecules and become too heavy to stay in suspension and thus, condense into tiny liquid droplets along the paths of the emissions.

Answer 8

alcohol,ionization