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Correlation of local trapping with crystal defects by direct observation of electron loss in a coaxial Ge(Li) detector

Description: From nuclear science symposium; San Francisco, California, USA (14 Nov 1973). A propeller-shaped region of reduced full-energy-peak efficiency was observed on the face of a true coaxial Ge(Li) detector for use in a gamma camera. A similar pattern on the etch-pit photograph suggests that the propeller blades correspond to the 111 symmetry axes of the crystal. Spectra obtained when a 122 keV gamma -ray beam was directed at this degraded region, show a low energy tail which is not present when the beam is directed at normal regions. Current pulses corresponding to gamma -rays that interact in the propeller region have shapes that show deficiencies in the electron component. Thus, degraded crystal regions that are revealed by etch-pit distributions can be correlated to local detector performance by direct observation of trapping rather than only by inference from the presence of tails in the energy spectra. (auth)
Date: January 1, 1973
Creator: Strauss, M.G.; Sherman, I.S. & Bannon, R.W.
Partner: UNT Libraries Government Documents Department

Determination of 243Am in 244Cm by Gamma Spectroscopy

Description: Gamma spectroscopy with a high resolution Ge(Li) detector is used to determine 243Am by its 74.7-keV gamma transition in solutions containing much higher specific activities of other actinides and fission products. The method is well suited for analytical control of curium process steps because of its simplicity, speed and reliability. This paper discusses the study results.
Date: August 29, 2001
Creator: Wakat, M.A.
Partner: UNT Libraries Government Documents Department

SAMPO, A Fortran IV Program for Computer Analysis of Gamma Spectrafrom Ge(Li) Detectors, and for Other Spectra with Peaks

Description: SAMPO is a Fortran IV program written to perform the data- reduction analysis described by J. T. Routti and S. G. Prussin in Photopeak Method for the Computer Analysis of Gamma-Ray Spectra from Semiconductor Detectors, Nuclear Instruments and Methods 72, 125-142 (1969). The code has also been used to analyze other spectra with peaks and continua. Program SAMPO can be used for an automatic off-line or an interactive on-line analysis. It includes algorithms for line-shape, energy, and efficiency calibrations, and peak-search and peak-fitting routines. Different options are available to make the code applicable to accurate nuclear spectroscopic work as well as to routine data reduction. The mathematical methods and their coding are briefly described. Instructions for using the program and for preparing input data are given and the optimal strategies for running the code are discussed. Instructions are given for using the LRL program library version of SAMPO and for obtaining source decks.
Date: October 20, 1969
Creator: Routti, Jorma T.
Partner: UNT Libraries Government Documents Department

Studies with a passive Ge(Li) assay system

Description: From joint meeting of the American Nuclear Society and the Atomic Industrial Forurm and Nuclear Energy Exhibition; San Francisco, California, USA (11 Nov 1973). The use of passive Ge(Li) gamma-ray waste/scrap assay systems for material accountability at Rocky Flats is briefly discussed. (WHK)
Date: January 1, 1973
Creator: Martin, H. R. & Chanda, R. N.
Partner: UNT Libraries Government Documents Department

High-efficiency multidetector system for tumor scanning

Description: A high-efficiency detector system developed especially for medical imaging has three specially cut Ge(Li) coaxial detectors (total volume 249 cm$sup 3$). At 122 keV, the peak efficiency is 93 percent of that of a 7.6 x 7.6 cm NaI (Tl) detector. Degradation of the paralleled energy resolution is avoided and resolution is improved by 35 percent over that of conventional output-summing techniques by gating the detector outputs. In effect this multiplexes them to a single line output. (auth)
Date: November 18, 1975
Creator: Kirby, J.A.; Phelps, P.L.; Armantrout, G.A.; Sawyer, D. & Beck, R.N.
Partner: UNT Libraries Government Documents Department

Intrinsic efficiency of germanium: a basis for calculating expected detector efficiency

Description: A method is presented whereby the intrinsic efficiency of Ge is utilized to calculate the expected peak efficiency of detectors having a wide range of sizes. The intrinsic efficiency of Ge, which is the probability for total absorption, was measured at 122 and 136 keV in Ge(Li) coaxial detectors and HPGe planar detectors having an effective thickness ranging from 5 to 50 mm. At 136 keV it is 64% for a thickness of 10 mm and 82% for 20 mm, after which it levels off reaching 89% at 50 mm. It is shown that the peak efficiency of a detector is a product of only the intrinsic efficiency and the solid angle, once losses due to edge escape and detector imperfections (surface channels and high dislocation densities) are determined. The absolute and relative (to NaI(Tl)) peak efficiency of a sample detector, calculated on the basis of intrinsic efficiency, are in good agreement with measured values. This method should find applications in the design of new detector systems particularly those for diagnostic imaging with /sup 99/Tc (140 keV).
Date: January 1, 1976
Creator: Strauss, M. G.; Sherman, I. S.; Cattelino, M. J.; Brenner, R. & Pehl, R. H.
Partner: UNT Libraries Government Documents Department

CSER 94-015: New portable NDA equipment for use in SNM audits

Description: A criticality safety review is presented for the use of two portable NDA detectors from Los Alamos during an IAEA inspection of the SNM at PFP. The units are an Active Well Coincidence Counter (AWCC) and a High Level Neutron Coincidence Counter (HLNCC). Approval for their employment is based on the inherent safety of the containers to be assayed, one at a time, and because their designs conform with the acceptability criteria which allow the other NDA detectors currently employed at the facility.
Date: December 12, 1994
Creator: Hess, A. L.
Partner: UNT Libraries Government Documents Department


Description: The nuclear radiations of nuclides: U{sup 233}, Pu{sup 239}, Bk{sup 243}, Bk{sup 244}, Bk{sup 245}, Bk{sup 246}, Bk{sup 249}, Cf{sup 249}, and Fm{sup 255} were investigated with high-resolution spectrometers. The {alpha}-particle spectra of all nuclides except Bk{sup 249} were measured with 6 mm diameter surface-barrier detectors. Bk{sup 249} {alpha}-particles were analyzed with a double-focusing magnetic spectrograph. The {gamma}-singles were examined with the recently developed Ge(Li) and Si(Li) detectors coupled with very-low noise 'internal FET' preamplifiers. Weak alpha groups were observed in coincidence with {gamma}-rays, detected with a NaI(Tl) scintillation spectrometer. To improve the over-all coincidence efficiency a new coincidence apparatus was designed and built. This instrument consisted of a cooled 4.5 cm diameter semiconductor detector for {alpha}-particle detection and a 3 cm diameter by 2.7 cm long Ge(Li) detector for {gamma}-ray analysis. The Ge(Li) detector could also be replaced with a NaI(Tl) detector. Cf{sup 249} conversion electrons were measured with a cooled Si(Li) detector coupled with an internal FET preamplifier. On the basis of the present work and previous information, energy-level diagrams of the daughter nuclei have been constructed. The levels have been grouped into rotational bands built on Nilsson single-particle states. Because of identification of several rotational members of the bands, definite Nilsson quantum number assignments have been made in most cases. The alpha intensity calculations of Poggenburg were found quite helpful in making these assignments. A strong Coriolis effect was observed in the Am{sup 245} levels populated by the alpha groups of Bk{sup 249}. Calculations were made with Nilsson wave-functions, and these were found to agree with the experimental results. The Coriolis interaction was found important in almost all cases; the effect was very noticeable in the level spacings between the rotational members of the bands. High-lying bands in Cm{sup 245} (at 644 keV) and cf{sup 251} (at ...
Date: September 20, 1966
Creator: Ahmad, Irshad
Partner: UNT Libraries Government Documents Department