#Half life source beta free#
Under bombardment of alphas, beryllium undergoes a number of reactions which leads to the production of free neutrons (see Neutron Activation of Silver for details). There are no natural isotope sources of neutrons, but by mixing an alpha-emitting isotope with a suitable target material, neutrons can be produced through a nuclear reaction.
Half lives are 30.2 and 5.26 yr, respectively. We use the two most common of such sources: 137Cs, which gives off a 662 keV gamma, and 60Co (1.173 and 1.332 MeV gammas). Like the discreet atomic energy levels which give rise to specific photon energies, the well defined nuclear states are the source of specific gamma ray energies. Gamma rays are electromagnetic radiation emitted by excited nuclei in their transition to lower nuclear energy levels (following beta decay). Nuclides that decay directly to the ground state are "pure beta emitters." 2 90Sr/ 90Y is such a source, emitting a continuous spectrum of fast electrons up to a maximum energy of 0.546/2.27 MeV. Beta particles are fast electrons (or positrons) emitted as a result of the decay of a neutron (or proton) in nuclei which contain an excess of the respective nucleon. The alpha particle source is 241Am (5.49 MeV (85%) and 5.44 MeV (13%) α's) which also gives off γ and x-rays. Alpha particles are 4He nuclei and are generally emitted by very heavy nuclei containing too many nucleons to remain stable. We first describe the sources presently available and follow with how their radiations are detected.ġ. The interactions of these radiations with matter are unique and the purpose of the demonstration is to show how the physics determines the detection techniques in each of the four types. The interaction processes of each type of radiation explain their penetrability through matter, their difficulty or ease of detection, and their danger to biological organisms. Radiations originating from atomic and nuclear processes are classified into four types:Ĭharged particulate radiation consisting of
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