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Analytical Techniques


Instrumental neutron activation analysis is a chemically non-destructive technique of elemental analysis used to determine mass fractions of as many as 40 elements in a variety of materials. Samples are packaged as received, irradiated with neutrons. The elements comprising the sample undergo neutron capture resulting in the formation of radioactive product nuclides. The gamma radiation is measured; the energy of the radiation indicates from which element the product nuclide was formed and the amount of radiation at a given energy is directly proportional to the amount of that element.
For more information click here -> INAA.



Radiochemical neutron activation analysis (RNAA)is used when greater sensitivities are required than are provided by INAA. By performing radiochemical separations on the irradiated material, the element or class of elements of interest are isolated to enhance sensitivity by eliminating interferences and reducing background count-rates. For some applications, detection limits can be improved by up to three orders of magnitude as compared with INAA.
For more information click here -> RNAA.



Prompt gamma ray activation analysis (PGAA) is used for the analysis of light elements such as H, B, C, N, as well as for the heavy elements Cd, Sm, Gd. PGAA is used to complement INAA by allowing determination of elements that do not form radioactive products after irradiation (e.g., H and B), and elements for which the half life is too long to be conveniently measured by INAA (e.g., C.). PGAA also provides a second method for analysis of some elements that are determined routinely with INAA (e.g., Na, Cl, K, Sm, Gd). PGAA is a neutron beam technique in which the gamma rays are measured during sample irradiation. In this way samples that are too large or unsuitable for in-core irradiations may be analyzed. There are two PGAA facilities at the NIST Center for Neutron Research, one using a cold neutron beam and the other using a thermal neutron beam.
For more information click here -> PGAA.



Neutron depth profiling is a non-destructive, neutron beam, analytical technique used to determine the concentration of elements such as boron, lithium, and nitrogen, as a function of depth in near surface regions of a variety of materials.
For more information click here-> NDP.


Neutron Focusing

Neutron focusing is a technique used to concentrate and direct a neutron beam onto a small area. Focusing has been combined with both of the analytical cold neutron beam techniques, CNPGAA and NDP, to enhance the spatial resolution and sensitivities for analyses of small samples.
For more information click here-> Neutron focusing.


Last modified 20-November-2002 by website owner: NCNR (attn: Bill Kamitakahara)