Radioactivity gamma activity

LLW Low Level radioactive Waste waste that contains less than 4 X 10 Bq/tonne of alpha activity, and less than 12 x 10 Bq/tonne of beta/gamma activity (UK usage). 

A shale content estimate can be derived from a gamma measurement based on the correlation between shale cmitent and radioactive isotope content, which originates natural gamma activity. It is assumed that only shale or clay is responsible for the radiation no other radioactive minerals are present. 

Neutron Activation Analysis Few samples of interest are naturally radioactive. For many elements, however, radioactivity may be induced by irradiating the sample with neutrons in a process called neutron activation analysis (NAA). The radioactive element formed by neutron activation decays to a stable isotope by emitting gamma rays and, if necessary, other nuclear particles. The rate of gamma-ray emission is proportional to the analyte s initial concentration in the sample. For example, when a sample containing nonradioactive 13AI is placed in a nuclear reactor and irradiated with neutrons, the following nuclear reaction results. 

Radioactivity occurs naturally in earth minerals containing uranium and thorium. It also results from two principal processes arising from bombardment of atomic nuclei by particles such as neutrons, ie, activation and fission. Activation involves the absorption of a neutron by a stable nucleus to form an unstable nucleus. An example is the neutron reaction of a neutron and cobalt-59 to yield cobalt-60 [10198 0-0] Co, a 5.26-yr half-life gamma-ray emitter. Another is the absorption of a neutron by uranium-238 [24678-82-8] to produce plutonium-239 [15117 8-5], Pu, as occurs in the fuel of a nuclear... 

This can result in a radioactive product from the A(n, t)A reaction where A is the stable element, n is a thermal neutron, A is the radioactive product of one atomic mass unit greater than A, and y is the prompt gamma ray resulting from the reaction. A is usually a beta and/or gamma emitter of reasonably long half-life. Where access to a nuclear reactor has been convenient, thermal neutron activation analysis has proven to be an extremely valuable nondestructive analytical tool and in many cases, the only method for performing specific analyses at high sensitivities... 

The half-life of a radioactive species is defined as the time it takes for the activity of the sample to drop by 50%. In this activity, you will investigate the decay of 137Bam, a metastable isotope of barium that undergoes gamma decay with a half-life of several minutes. 

There is always some level of ambient radioactivity in an environment. This radiation is known as background radiation. Measure and record the background activity by recording the counts registered by the gamma ray detector in 30-s intervals for 5 min. Record the data in Data Table 1. 

Neutron activation analysis (NAA) is a technique for the qualitative and/or quantitative determination of atoms possessing certain types of nuclei. Bombarding a sample with neutrons transforms some stable isotopes into radioactive isotopes measuring the energy and/or intensity of the gamma rays emitted from the radioactive isotopes created as a result of the irradiation reveals information on the nature of the elements in the sample. NAA Is widely used to characterize such archaeological materials as pottery, obsidian, chert, basalt, and limestone (Keisch 2003). 

---