ABSTRACT
INTRODUCTION8.1 An absolute measurement is one in which the exact number of particles emitted or the exact number of events taking place is determined, for example,
1. Determination of the activity of a radioactive source, that is, measurement of the number of particles emitted by the source per second
2. Determination of the neutron ux (neutrons per square meter per second) at a certain point in a reactor
3. Measurement of the number of neutrons emitted per ssion
4. Measurement of the rst cross section for a nuclear interaction
A relative measurement is one in which the exact number of particles emitted or the exact number of events taking place is not determined. Instead, a “relative” number of particles or events is measured, a number that has a xed, but not necessarily known, relationship to the exact number, for example,
1. Determination of the G-M plateau. The relative change of the number of particles counted versus HV is measured. The exact number of particles emitted by the source is not determined; in fact, it is not needed.
