Prompt gamma-ray activation analysis (PGAA) is an important nuclear analytical technique that complements conventional neutron activation analysis (NAA). When a target is placed in a beam of neutrons, gamma-rays emitted upon neutron capture are measured by a shielded germanium detector, yielding quantitative elemental analysis. The radiation is penetrating and the analysis both nondestructive and independent of the chemical form of the element(s) being measured. The technique is most useful for measurement of light elements (H, B, C, N, Si, P, S, Cl) which can not be easily measured by other methods. Best sensitivity is achieved with neutron beams from research reactors. Although sample preparation is minimal, care must be taken to select proper standards and blanks, and numerous corrections must sometimes be applied to the data from the complex spectra. PGAA has proven useful for multielement analysis of a wide variety of different materials spanning a broad range of scientific disciplines. Of particular importance has been the measurement of hydrogen in materials.

Prompt Gamma-Ray Activation Analysis: Fundamentals and Applications

A PGAA instrument consists of a source of neutrons, a collimating beam tube to shape and direct a beam of neutrons onto a sample, a shutter to turn the beam on and off, a target assembly to position the sample reproducibly in the neutron beam, a gamma-ray detector, a beam stop to absorb the neutrons that are not absorbed by the sample, and shielding to protect the detector and personnel from neutron and gamma radiation. Each of these components will be considered in turn.

Beams and Facilities

C60T Presented at the 1978 IEEE Nuclear Science Symposium, Washington D. C , October 18-20, 1978 , . /y/ LBL-8307 RADIATION DAMAGE RESISTANCE OF REVERSE ELECTRODE GE COAXIAL DETECTORS Richard H. Pehl, Norman W. Madden, Jack H. Elliott, Thomas W. Raudorf, Rex C. Trammel 1 and Lawrence S. Darken, Jr. October 1978 Prepared for the U. S. Department of Energy under Contract W-7405-ENG-48 W imIF J.Wi£EO

Radiation damage resistance of reverse electrode ge coaxial detectors

Rat exposed to toxic cadmium chronically and acutely are diagnosed byin vivo promt gamma-ray activation andin vitro neutron activation using nuclear reactor neutron beam. Linear correlation of bothin vivo andin vitro methods is established, damage level of 1.7 mg/g Cd in kidneys and 0.16 mg/g Cd in liver are confirmed by biochemical diagnosis. Features ofin vivo andin vitro nuclear medical diagnoses of cadmium contamination, serving as the basis for future research and correletion to human beings, are discussed.

IN vIVO AND IN VITRO MEDICAL DIAGNOSES OF TOXIC CADMIUM iN RATS

A low cost neutron capture prompt gamma activation analysis facility has been constructed at The University of Michigan's Pheonix Memorial Laboratory. Although the neutron beam used has a fairly large epithermal component (Cd ratio 7.1), background levels are low enough to result in satisfactory measurement of over 16 different elements. For the elements of greatest sensitivity (samarium, boron, gadolinium, and cadmium) minimum detectable levels of 3.6·10−5 to 1.4·10−5 gram for a one hour measurement are possible. The fast neutrons incident to the detector were found to be minimal. Estimates of up to 3 years of continuous operation before measurable damage is expected.

M. A. Ludington

Papers

A low cost neutron capture prompt gamma-ray analysis facility at a research reactor