Lithium-drifted Germanium Detector Research Articles

Determination of red cell survival by activation analysis

The determination of red cell survival by activation analysis using non-radioactive enriched 50Cr was clinically applied. The method described is very practical with the use of a lithium-drifted germanium detector which avoids chemical separation of samples after neutron irradiation. Though there were scatterings in individual data points of 50Cr, fairly good agreements were obtained between half-lives of 50Cr labeled red cells and those of 5ICr labeled red cells.

Distribution en masse dans la fission de 238U par des neutrons de 14 MeV

The fission yields of twenty-eight mass chains were measured for the 14 MeV neutron induced fission of 238U. Fission product gamma activities from 238U were determined with a high resolution lithium drifted germanium detector. The fission yields were derived using only nuclear data of fission products. To test the method, we have measured the yields of twenty-one mass chains in the thermal neutron induced fission of 235U. For these two mass distributions, comparison with recent compilations were made.

Measurement of γ-ray attenuation coefficients

Gamma-ray attenuation coefficients have been determined for five elements between Z = 13 and Z = 82, using γ-rays with energies between 295 and 2440 keV from a sealed Ra-226 source. A lithium-drifted germanium detector was employed without collimation or shielding. The average standard error of the experimental results was 1 per cent.

Low energy gamma rays from thermal neutron capture

The beam tubeP2 of the 4 MW FRM pool reactor was used as the neutron source for this nuclear spectroscopy study. An 8.5 and 13.5 cm lithium drifted germanium detector were used as gamma ray detector to measure the low energy prompt photon emissions from thermal neutron capture in 18 elements (12 rare earth elements) having aσ/A value greater than 0.1. The energy region was from 50–500 keV. Energy and intensity of the gamma ray lines are given.

An evaluation of trace element analysis in the forensic investigation of fibre samples

The use of trace element analysis in the forensic examination of fibres has been investigated. Samples of both natural and synthetic fibres have been analysed to show that it is possible to both identify and discriminate between samples that would, by present methods, be considered indistinguishable. A number of wool garments of predetermined trace element composition were sent for wear for a period of nine months. The conditions and frequency of wear and cleaning were reported to enable their effect upon the trace element composition of these garments to be determined. The wool samples were analysed by both short (30 min) and long (50 hrs) irradiations in a reactor flux of about 1012 n·cm−2·sec−1. This permitted the concentrations of the elements such as sodium, chlorine, iodine, manganese, cobalt and chromium to be determined. Both sodium iodide and lithium drifted germanium detectors were used to measure the induced activity of the wool samples. The composition of a range of acrylic fibres from a variety of sources has also been examined using a sodium iodide detector. The concentrations of sodium chlorine, bromine, managese, copper, aluminium, titanium, indium and barium were determined in these samples.

Quantitative evaluation of the photon-activation method in analysis

Yields of the photonuclear reactions of various types induced in 71 elements have been determined experimentally by means of bremsstrahlung irradiation with different maximum energies, and detection of the resultant activities with a lithium-drifted germanium detector. From the results obtained, sensitivities in photon-activation analysis were evaluated and the reactivity of high-energy photons with nuclei in a wide range of atomic number was discussed.

Identification of Radioactive Isotopes in Reactor Pool Water

A lithium-drifted germanium detector has been used to identify 36 radioactive isotopes in a sample of pool water from the Western New York Research Center reactor. A total of 100 peaks were observed in gamma-ray spectra taken over a period of 3 months. The primary methods of production of the isotopes are fission and the (n, γ) reaction. Two isotopes were produced by the (n, p) reaction and possibly one by the (p, n) reaction. Fission products are present in the water as a result of a fuel element cladding failure. The elements which were activated are either in the water as a result of corrosion of material in the pool, or in water soluble compounds of elements from material in the pool.

Lithium-drifted germanium detectors edited by I. C. Brownridge

<i>Lithium-drifted germanium detectors</i> edited by I. C. Brownridge

Operational Characteristics of Germanium Detectors at Higher Temperatures

Several important areas for the use of germanium spectrometers would be opened if these detectors could be successfully operated at temperatures considerably in excess of 77°K. Precise measurements on a series of detectors made from different high-purity germanium crystals and on one lithium-drifted germanium detector indicate that the resolution does not degrade significantly until nearly 150°K is reached. Similar-sized detectors, including the lithium-drifted device, exhibited essentially identical temperature-resolution relationships.

Fast-neutron flux measurement with a lithium-drifted germanium detector

The use of lithium-drifted germanium detectors for fast-neutron flux measurement has been investigated. The proposed detection mechanism is observation of the internal conversion electrons emitted during the de-excitation of the 691 KeV 0 + state in 72Ge following excitation via fast-neutron scattering. A 4.0 cm 3 (approx.) planar Ge(Li) detector has been calibrated for neutron flux measurements over the energy range E n = 700−5000 keV. The absolute efficiency for this detector (ratio of neutrons detected to neutrons incident on the detector) has been determined to be (8.2±0.5) × 10 −4 at E n = 1500 keV which is about 10% of the full-energy peak efficiency for 1332 keV 60Co gamma rays. Cross-sections for excitation of the 691 keV 0 + state in 72Ge via neutron scattering have been extracted from the measured efficiency function. These cross-sections can be used to calculate efficiency functions for other detectors. Insensitivity to thermal neutrons, gamma-ray discrimination capability and stability are among the desirable features of this type of fast-neutron detector. Submicrosecond timing is not possible because of the isomeric nature of the 691 keV 0 + state in 72Ge. While Ge(Li) detectors suffer radiation damage from fast-neutron bombardment, the detector used for these measurements withstood an integrated dose exceeding 10 10 neutrons/cm 2 without serious deterioration of its performance.

The Relative Intensities and Angular Distributions of Gamma Rays from the Nuclear Reaction 19F(p,αγ)16O

The relative intensities of the 6.13, 6.92 and 7.12 MeV gamma rays from the nuclear reaction 19F(p,αγ)16O have been measured for proton energies between 1.3 MeV and 2.2 MeV, in steps of about 6 keV. In addition, angular distributions of gamma rays have been measured on and around the different resonances for 22 proton energies in the energy interval. A lithium-drifted germanium detector with an energy resolution of about 0.5% has been used, permitting the two 7 MeV components to be fully resolved. The behaviour of the three components at the various resonances differ somewhat.

Mass yields from thermal-neutron induced fission of 245CM

The fission yields of 21 mass chains were measured for the thermal-neutron induced fission of 245Cm. Fission product gamma activities from 245Cm were determined relative to those from 235U with a high resolution lithium-drifted germanium detector. The measured errors ranged from 1 to 10% over a mass number range of 85–147. No significant fine structure in the mass yield curve was apparent.

Halogen-doped Cadmium Telluride for Detection of Gamma Rays

DURING the past ten years the development of semiconductors for the detection of gamma rays has been proceeding at an accelerating pace, so that lithium drifted silicon detectors, as well as lithium drifted germanium detectors and undrifted germanium detector materials, are now commercially available. These materials have two important shortcomings: first, they must be operated at liquid nitrogen temperatures if they are to give their best performance (although Si is useful up to +40° C); and second, silicon in particular has a low absorption cross section for gamma rays because of its low atomic weight. So the use of heavier compound semiconductors with larger energy gaps, in particular CdTe, has been of substantial interest in the development of solid state nuclear detectors1,2.

Yields of photonuclear reactions for photon-activation analysis with high-energy bremsstrahlung

Experimental reaction yields have been determined for various types of photonuclear reactions, induced in 52 elements by means of Bremsstrahlung irradiation with maximum energies ranging from 30 to 72 MeV, and of detection of the resultant activities with a lithium-drifted germanium detector. From the results obtained, sensitivities in photon-activation analysis were evaluated and the reactivity of high-energy photons with nuclei in a wide range of atomic number is discussed. Some nuclear considerations in photon-activation analysis, involving the relative probability of forming each product as a result of the (γ, xnyp) reactions are also given.

The Intercomparison of Radium Sources Using a Lithium-Drifted Germanium Detector

A method is described for the intercomparison of the activities of radium sources, using a lithium-drifted germanium detector for relative measurements of the photopeak intensity corresponding to a given γ-ray. Some typical results are presented and experimental uncertainties are discussed.

Radioanalytical applications of gamma-gamma coincidence techniques with lithium-drifted germanium detectors

Radioanalytical applications of gamma-gamma coincidence techniques with lithium-drifted germanium detectors

X-ray Fluorescence: Detection of Lead in Wall Paint

An instrument has been developed for the in situ determination of lead on painted surfaces. It utilizes, as a source of gamma rays, radioactive cadmium-109 and its daughter silver-109 (metastable) to excite the K series x-rays of lead, and a solid-state, lithium-drifted germanium detector. The device, which is capable of detecting 0.26 milligram of lead per square centimeter of paint [approximately 3 percent (by weight) of lead in a single coat] beneath ten layers of lead-free paint, has been tested in a preliminary survey of several tenement apartments in New York City.

Neutron capture γ-ray techniques for iron and gold in mixtures

The feasibility of utilizing prompt γ-rays from thermal neutron capture as a non-destructive technique for the identification and estimation of gold in mixtures has been studied. Thermal neutrons from the University of Maryland reactor and a 40-cm 3 lithium-drifted germanium detector were applied with promising results. The high-energy capture γ-ray spectra for mixtures of gold and abundant elements, such as silicon, iron, calcium and aluminum were measured. A 'Capture γ-Ray Sensitivity Index' is introduced to provide an indication of relative sensitivity for detection of elements by this technique.

Elastic Scattering of 1.33-MeV Photons from Lead and Uranium

Differential cross sections for the elastic scattering of 1.33-MeV photons from lead and uranium have been measured at angles ranging from 12 to 60\ifmmode^\circ\else\textdegree\fi{}, using a lithium-drifted germanium detector. Available calculations of the various elastic scattering amplitudes are briefly reviewed and an argument is presented to establish the relative phases between the two polarization components of the real scattering amplitudes. Those relative phases and the relative phases among the amplitudes of the various scattering processes permit the addition of the amplitudes to calculate theoretical cross sections. Discrepancies exist between the measured and theoretical cross sections. Suggestions by several authors for resolving these discrepancies are discussed and the need for further theoretical work is indicated.

Rotational states of 158Dy, 164Er, 168Yb and 174Hf excited by evaporation reactions

A series of rotational bands in 158Dy, 164Er, 168Yb and 174Hf were studied by excitation with neutron evaporation reactions initiated by protons, deuterons, 3He and α-particles with energies between 16 and 28 MeV. The resulting prompt γ-ray spectra were analyzed with a curved crystal diffraction spectrometer and with lithium-drifted germanium detectors. Transitions from levels in the ground state bands were seen up to 10 + in 168Yb, 12 + in 158Dy and 174Hf and 14 + in 164Er. The γ-vibrational bands in three of the nuclei were strongly excited and several β-bands were weakly excited. The energy levels deduced from the measurements were successfully fit by the empirical formulas of Holmberg and Lipas and of Sood for the ground state band as well as for the higher bands. The cross sections for transitions in the ground state band agree with the statistical model calculations made. Within the validity of the calculations, no large angular momentum deficit was observed.