History

History of the k0 method

Several researchers proposed the standardization of Neutron Activation Analysis using calibration factors, sometimes called k factors, which were measured for the gamma rays of the elements of interest for specific irradiation and counting conditions. It was very convenient to continue using these k factors as long as the conditions did not change.

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In the early 1970s, András Simonits was working at the laboratory of Julien Hoste in Gent, Belgium. He proposed to Frans de Corte to standardize NAA using “universal k factors”, where the essential information for a gamma ray emitted by any nuclide produced by neutron activation would be contained in the k0 factor. They undertook to work together on an ambitious project to develop the k0 method.

Over a number of years, the k0 values for the gamma rays of practically all nuclides produced by neutron irradiation, as well as other activation and decay properties, were accurately measured by Simonits and De Corte in Budapest and Gent, and in other laboratories. Methods and materials were developed to characterize the reactor neutron spectrum and to model the gamma ray detector efficiency. The k0 method became popular because it had elaborate and complete models of the activation, decay and detection processes and thus enabled accurate and convenient NAA for a large number of elements without the need for the repeated preparation of standards. k0-NAA is more interesting to do than relative NAA because it encourages a complete understanding of all the processes involved. k0-NAA is now used in one form or another in over 50 NAA laboratories around the world.

In 1992, the first International k0 Users’ Workshop was organized by Prof. Frans De Corte in Gent, Belgium. Since then, it has been organized in several venues by laboratories involved with the k0 method.

Earlier meetings of the k0 community:
1st Workshop: Gent, Belgium (1992),
2nd Workshop: Ljubljana, Slovenia (1996)
3rd Workshop: Bruges, Belgium (2001)
4th Workshop: Funchal, Madeira Island, Portugal (2005)
5th Workshop: Belo Horizonte, Brazil (2009)
6th Workshop: Budapest, Hungary (2013)

k0 NAA in Montreal

In 2017 the k0 Workshop arrives in Montreal where the k0 method has been used extensively since 1998. Until 1996 the Montreal NAA lab had been getting along using local k factors. But it was realized that these factors were not always that accurate and they would all have to be remeasured with the upcoming reactor refuelling and the purchase of new gamma ray detectors. With the knowledge acquired at k0 Workshop in Ljubljana, a hybrid k0 method was implemented in the Montreal lab. It merged the best features of the k0 method with the previously used local k factor method to take full advantage of the extreme stability of the Montreal SLOWPOKE reactor and the gamma ray spectrometers.

In 2001, for the first time, the Montreal NAA lab could offer a fast turnaround NAA service for accurately analyzing any material of any combination of chemical elements. The NAA service flourished and the lab became partially auto financed, to reach full self-sustainability after 2010. Presently the lab continue k0 method tradition by performing k0 and Q0 factor measurements, and by innovating in areas such iterative correction of neutron self-shielding combined with gamma ray self-attenuation, NAA software and automation.

During the 2017 Workshop, a half day will be devoted to visiting the NAA lab and observing how the hybrid k0 method is used to analyze a wide variety of materials for university research projects and for Canadian and international industries and government agencies.