Direct determination of the gamma-ray logging system response function in field boreholes

In gamma-ray logging, the system response function is the noise-free response of the logging system to a zone of radioactive material of infinitesimal thickness under a given set of conditions (i.e., logging equipment and borehole and formation parameters). If a gamma-ray log is to be deconvolved to produce a profile of the distribution of radioactive material along the borehole it is essential that the shape of the system response function be known, at least approximately. Previously the system response function has been measured in model boreholes, and it has been assumed that this function remained constant in field boreholes. In this paper a technique is presented for determining the shape of the system response function in field boreholes, under favorable conditions. (orig./HAE)