Spectral, nuclear, and matrix interferences in the determination of rare earths in geologic specimens by neutron activation analysis

Conference · Fri Jan 01 00:00:00 EST 1993 · Transactions of the American Nuclear Society; (United States)

OSTI ID:5933271

Landsberger, S ^[1]

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1. Univ. of Illinois, Urbana-Champaign (United States)

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 is 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.

• OSTI ID: 5933271
• Report Number(s): CONF-930601-; CODEN: TANSAO
• Journal Information: Transactions of the American Nuclear Society; (United States), Vol. 68; Conference: American Nuclear Society (ANS) annual meeting, San Diego, CA (United States), 20-24 Jun 1993; ISSN 0003-018X
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
02 PETROLEUM
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
07 ISOTOPES AND RADIATION SOURCES
RARE EARTHS
ECOLOGICAL CONCENTRATION
INTERFERENCE
ROCKS
NEUTRON ACTIVATION ANALYSIS
CALIBRATION STANDARDS
CERIUM
COBALT
COMPTON EFFECT
DYSPROSIUM
EUROPIUM
GADOLINIUM
GEOCHEMICAL SURVEYS
HOLMIUM
INTERFERING ELEMENTS
IRON
LANTHANUM
LEAD
LUTETIUM
MINERALS
NEODYMIUM
NICKEL
PETROLOGY
PRASEODYMIUM
PROMPT GAMMA RADIATION
PROSPECTING
SAMARIUM
SELF-ABSORPTION
TERBIUM
THORIUM
THULIUM
URANIUM
YTTERBIUM
ABSORPTION
ACTINIDES
ACTIVATION ANALYSIS
BASIC INTERACTIONS
CHEMICAL ANALYSIS
ELASTIC SCATTERING
ELECTROMAGNETIC INTERACTIONS
ELECTROMAGNETIC RADIATION
ELEMENTS
GAMMA RADIATION
GEOLOGY
INTERACTIONS
IONIZING RADIATIONS
METALS
RADIATIONS
SCATTERING
SORPTION
STANDARDS
SURVEYS
TRANSITION ELEMENTS
580000* - Geosciences
020200 - Petroleum- Reserves
Geology
& Exploration
050100 - Nuclear Fuels- Reserves
Exploration
& Mining
070204 - Radiation Sources- Industrial Uses
Radiometric