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Title: Borehole neutron activation: The rare earths

Abstract

Neutron-induced borehole gamma-ray spectroscopy has been widely used as a geophysical exploration technique by the petroleum industry, but its use for mineral exploration is not as common. Nuclear methods offer the mining geologist techniques for mineral exploration, for determining stratigraphy and bed correlations, for mapping ore deposits, and for studying mineral concentration gradients. High-resolution detectors are essential for mineral exploration, and by using them as analysis of the major element concentrations in a borehole can usually be made. A number of economically important elements can be detected at typical ore-grade concentrations using this method. Because of the new application of the rare-earth elements to high-temperature superconductors, these elements are examined in detail as an example of how nuclear techniques can assist the mining geologist.

Authors:
;
Publication Date:
Research Org.:
U.S. Geological Survey, Reston, VA (US)
OSTI Identifier:
7181737
Alternate Identifier(s):
OSTI ID: 7181737
Report Number(s):
CONF-871006-
Journal ID: CODEN: IETNA
Resource Type:
Conference
Resource Relation:
Journal Name: IEEE Trans. Nucl. Sci.; (United States); Journal Volume: 35:1; Conference: 34. nuclear science symposium and 19. nuclear power systems symposium, San Francisco, CA, USA, 21 Oct 1987
Country of Publication:
United States
Language:
English
Subject:
02 PETROLEUM; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; PETROLEUM DEPOSITS; RADIOACTIVITY LOGGING; RARE EARTHS; ACTIVATION ANALYSIS; EXPLORATION; GAMMA SPECTROSCOPY; GEOPHYSICS; NEUTRON REACTIONS; RADIATION DETECTORS; STRATIGRAPHY; BARYON REACTIONS; CHEMICAL ANALYSIS; ELEMENTS; GEOLOGIC DEPOSITS; GEOLOGY; HADRON REACTIONS; MEASURING INSTRUMENTS; METALS; MINERAL RESOURCES; NUCLEAR REACTIONS; NUCLEON REACTIONS; RESOURCES; SPECTROSCOPY; WELL LOGGING 020200* -- Petroleum-- Reserves, Geology, & Exploration; 400102 -- Chemical & Spectral Procedures

Citation Formats

Mikesell, J.L., and Senftle, F.E. Borehole neutron activation: The rare earths. United States: N. p., 1988. Web.
Mikesell, J.L., & Senftle, F.E. Borehole neutron activation: The rare earths. United States.
Mikesell, J.L., and Senftle, F.E. Mon . "Borehole neutron activation: The rare earths". United States. doi:.
@article{osti_7181737,
title = {Borehole neutron activation: The rare earths},
author = {Mikesell, J.L. and Senftle, F.E.},
abstractNote = {Neutron-induced borehole gamma-ray spectroscopy has been widely used as a geophysical exploration technique by the petroleum industry, but its use for mineral exploration is not as common. Nuclear methods offer the mining geologist techniques for mineral exploration, for determining stratigraphy and bed correlations, for mapping ore deposits, and for studying mineral concentration gradients. High-resolution detectors are essential for mineral exploration, and by using them as analysis of the major element concentrations in a borehole can usually be made. A number of economically important elements can be detected at typical ore-grade concentrations using this method. Because of the new application of the rare-earth elements to high-temperature superconductors, these elements are examined in detail as an example of how nuclear techniques can assist the mining geologist.},
doi = {},
journal = {IEEE Trans. Nucl. Sci.; (United States)},
number = ,
volume = 35:1,
place = {United States},
year = {Mon Feb 01 00:00:00 EST 1988},
month = {Mon Feb 01 00:00:00 EST 1988}
}

Conference:
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  • In the past, the study of the rare earths (lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium) has been of great interest to geochemists because of its petrogenic value. More recently rare earths have been used in a variety of geochemical prospecting techniques and source signatures in environmental studies. Perhaps one of the most common uses of instrumental neutron activation analysis (NAA) has been the determination of rare earths in geologic samples. Because of the relatively high activation cross section that these rare earths exhibit, analytical sensitivity for the majority of them ismore » excellent, often with detection limits typically below one part per million. During the past decade, several papers have appeared on the nuclear interferences that uranium fission has on the determination of lanthanum, cerium, and neodymium. The spectral interferences of uranium, thorium, and gadolinium on samarium have also been tabulated. Although it is generally thought that matrix corrections are not needed for NAA, a very careful consideration must be given to self-absorption of gamma rays in high-Z materials. This is especially important when using the low-energy gamma rays of neutron-activated rare earths in geologic samples that contain high abundances of iron, nickel, lead, cobalt, etc. While this effect is small in typical silicate rocks, many different types of minerals have occlusions of such high-Z materials. This paper focuses on several important features of NAA of rare earths. These include preparation of primary standards, uranium fission interferences, spectral interferences including those often neglected, gamma-ray self-absorption, epithermal NAA to increase the sensitivity of certain elements, and the use of special instrumental techniques such as prompt-gamma, cyclic NAA, and Compton suppression.« less
  • Research was carried out both in the laboratory and at a mine to establish suitable dynamic borehole logging technologies for manganese mining based on prompt neutron-gamma and neutron activation techniques. The calibration accuracies obtained in similarly mineralized media at the mine, in dry shallow (15 m deep) boreholes of 150 mm diameter, were also about 4% Mn for the prompt neutron-gamma method, both for the entire mine and for the individual deposits at the mine. For logging based on neutron activation analysis, the calibration accuracy was less than 3.5% Mn in one area of the mine. However, the accuracy wasmore » 6.5% Mn for the calibration based on the entire mine.« less