Operator's guide for VAXGAP, a gamma-ray spectrum analysis package

This report describes the gamma-ray analysis program VAXGAP, which has continually evolved at the Idaho National Engineering Laboratory over a period of several years. It is an integrated suite of computer programs for performing analyses of pulse-height spectra from high-resolution gamma-ray spectrometers and assorted support functions. VAXGAP programs operate on Digital Equipment Corporation (DEC) VAX computers running the VMS operating system, and were written in VAX FORTRAN and DEC Digital Command Language (DCL). These programs make use of DEC GKS and ReGIS for graphical output on standard terminals and printers, and DEC windows for graphics on workstations and terminals that support the X Window System protocol. This report addresses the use of VAXGAP for data acquisition and control, energy scale calibration, and real-time analyses of background and sample pulse-height spectra. Also addressed are the creation and use efficiency tables and isotope libraries, manipulation of spectrum files and their contents, and graphical display of on-going acquisitions, saved spectra, and mathematical fits to spectral peaks.

The dependence of magnetic Barkhausen emissions (MBE) upon both field excitation and detection frequencies and excitation wave form was studied in order to investigate two of several crucial factors which affect the emissions. Sinusoidal, triangular, and square wave forms were used to generate the MBE and the pulse height spectra, frequency spectra, and pulse wave forms of these signals were analyzed. The frequency spectra of sinusoidal and triangular alternating field excitations showed similar behavior but the spectrum under square wave excitation was different due to the existence of high frequency components during square wave switching. As yet, no common standard has been agreed upon for parameterization and representation of Barkhausen signals. It appears from this work that field excitation wave form and frequency should define the inputs, while detection frequency range, pulse height spectrum, frequency spectrum, and emitted pulse wave form analysis should be used to quantify the output.

Selection of a standard programming language for an oil service consultancy

Activation measurements of fast neutron radiative capture for 139La

Superconducting transition edge sensors (TES) are used for high-resolution X-ray spectroscopy. In our group, we have developed Ir/Au-TESs. We have recently started to develop a high-resolution X-ray and gamma-ray spectrometer using our Ir/Au-TES. In this study, we plan to accelerate the response time of the detector system, thus we have designed a new Sn-absorber coupled TES detector system by improving the thermal contact between the TES and the absorber. A superconducting tin absorber is coupled to an Ir/Au superconducting film with a gold (Au) bump post, instead of an epoxy post, which is used conventionally. The pulse height signal, which we obtained from the Au bump post TES, is more than twice as large as that from the epoxy post system, and the slow component of the decay time constant improved to 8.0 ms from 22.0 ms. The energy resolution of the 59.5 keV photoelectron peak is 280 eV FWHM, which is currently dominated by the mechanical vibration of our pulse-tube refrigerator.

ABSTRACTMercuric iodide (HgI2) is a semiconductor that has shown great promise for use in roomtemperature high-resolution x-ray and gamma-ray spectrometers. Its widespread usage has been limited, however, by low yield and long-term reliability problems. The processing of this material is still in its infancy compared to silicon, so research efforts continue to pursue the root causes of device failures. Two likely sources of performance limitations are impurities and poor contacts. Significant efforts have been expended in developing and using various purification schemes. However, quantitative chemical analyses have shown that several metallic impurities still exist at the high ppb level. In addition, it has not yet been definitively determined which impurities are most problematic and at what level they have a detrimental effect. Leakage currents and currentvoltage measurements have been used to study the movement of mobile impurity-related defect centers in the bulk mercuric iodide. In particular, this method has been used to quantify the drift of metallic impurities, such as Ag and Cu, which are known to or believed to degrade HgI2 detectors. Four-point-probe sheet resistance measurements have been used to study the stability of contacts and the formation of reaction layers. In particular, such measurements have revealed that the Pd contacts currently used for the highest quality detectors are not as stable as previously thought, as the films of Pd react with the HgI2 to form the amalgam PdHg.

The dynamic range of ultra-high-resolution cryogenic gamma-ray spectrometers

VAXGAP (VAX Gamma-ray Analysis Package) is a collection of computer programs for the analysis of pulse height spectra acquired on Ge detector-based spectrometers. VAXGAP was written to provide the operators of a radiation measurements laboratory with the necessary software tools for routine analysis of radioactive samples through the analysis of gamma-ray pulse-height spectra. The authors summarize the unique features and the organization of VAXGAP which makes it of particular value in the routine analysis of spectra.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Development of a flexible γ-ray detector using a liquid scintillation light guide (LSLG)

A robust computer program to simulate X-ray fluorescence (XRF) system and particularly applied to the total reflection mode is presented in this paper. The simulation of the different stages involved in x-ray fluorescence emissions was carried out by writing a suite of computer programs using FORTRAN programming language. These computer simulated XRF stages were then integrated together to generate a general robust model which was run with the digital visual Fortran 6.0 compiler set-up. The model was validated by comparison with experimental spectrum from the TXRF system in the Physics Department of the Obafemi Awolowo University, Ile-Ife. Trail experiments were carried out with this model to determine optimum conditions for detecting certain elements of interest under various analytical conditions in given samples. Results of these trail experiments show that the detectability of elements improved with increasing applied voltages and atomic number of elements. Variation of geometry such as the glancing incidence angle of the excitation and the nature of the support itself were also observed to effect the detect ability of the elements. Nigerian Journal of Physics Vol. 16(2) 2004: 97-104

This paper describes a technique involving the use of two open-path Fourier-transform infrared (FTIR) spectrometers to isolate emissions in complex source environments such as oil refineries or chemical manufacturing facilities. Typically, open-path FTIR monitoring involves collection or generation of an upwind (background) spectrum (I<SUB>0</SUB>) prior to the commencement of measurement activities, and the use of that spectrum to create absorbances for subsequent downwind (sample) spectra (I<SUB>0</SUB>) values. In situations where the upwind single beam spectrum is relatively clean or unchanging in time with respect to target compounds and interferences, this method of handling I<SUB>0</SUB> is generally satisfactory. However, in complex source environments where either I<SUB>0</SUB> or I values can change rapidly, the simultaneous use of two open- path units can yield substantial improvements, especially with respect to target compound detection limits. Although the use of two FTIR units can greatly improve the problem of background variation for target compounds as well as for background atmospheric components and interferences, it introduces a number of other problems resulting in difficulties in the analysis of the resultant absorbance spectra. These problems are discussed, and some recently collected field data showing the application of this technique is presented.

A computer program for the analysis of complicated (e.g. multi‐line) Raman spectra is described. The program includes automatic peak search, various procedures for background determination, peak fit and spectrum deconvolution and extensive spectrum handling procedures.

A high-resolution FTIR supersonic slit jet absorption spectrometer is described for the investigation of weakly bound dimers and trimers in the near-infrared spectral region. The spectrometer is demonstrated to conservatively have a sensitivity of 6×108 molecules/cc/state and can be operated at an apodized resolution of 0.004 cm−1. To illustrate the performance of the spectrometer, it has been applied to the rovibrational analysis of the band spectra of three weakly bound species in the near infrared: ν1 OC–HF, ν1 N2–HCl, and ν5 (H35Cl)3. The recorded spectra of these species are compared with corresponding investigations using state-of-the-art tunable infrared laser supersonic jet or molecular-beam spectrometers to illustrate the capabilities and limitations of the current FTIR supersonic jet spectrometer.

A three-dimnensional vision system for on-line operation that aids a collision avoidance system for an industrial robot is developed. Because of the real-time requirement, the process that locates and describes the obstacles must be fast. To satisfy the safety requirement, the obstacle model should always contain the physical obstacle entirely. This condition leads to the bounding box description of the obstacle, which is simple for the computer to process. The image processing is performed by a Machine Intelligence Corporation VS-100 machine vision system. The control and object perception is performed by the developed software on a host Digital Equipment Corporation VAX 11/780 Computer. The resultant system outputs a file of the locations and bounding descriptions for each object found. When the system is properly calibrated, the bounding descriptions always completely envelop the obstacle. The response time is data-dependent. When using two cameras and processed on UNIX time sharing mode, the average response time will be less than 2 s if eight or fewer objects are present. When using all three cameras, the average response time will be less than 4 s if eight or fewer objects are present.

A mesoscale modeling system is being applied on an experimental basis at The Pennsylvania State University (Penn State) for production of real-time, high resolution, numerical weather forecasts for the northeastern United States. The initial model experimentation is being supported by Penn State. It is believed to be the first time that a real-time, three-dimensional mesoscale model has been run routinely at an American university, although mesoscale models have been run in real time in government laboratories. A version of the Penn State/NCAR mesoscale model is employed, using a two-way interacting nested grid with a fine-grid increment of 30 km, a coarse-grid increment of 90 km, and 15 computational levels. The forecast cycle is initiated automatically by the Department of Meteorology's Digital Equipment Corporation VAX 8350 system when all the required 0000 UTC surface and upper-air National Weather Service (NWS) data have been received, quality checked, and archived. Lateral boundary conditions are ex...