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Lanthanum halide (LA[X.sub.3] : Ce) scintillators are currently being assessed by ESA for use as remote sensing gamma-ray spectrometers on future planetary missions. Such missions place a raft of constraints and requirements on sensor technology, which invariably stem from environmental and resource issues. In the past, NaI(T1) and CsI(T1) based spectrometers offered great advantages in term of device simplicity, reliability and detection efficiency but with poor energy resolution. Lanthanum halides combine these attributes with much higher energy resolution and their extensive deployment in future missions seems assured. In fact, La[Br.sub.3] spectrometers are currently baselined for most missions in planning. In this paper, we describe the needs of remote gamma-ray sensing and efforts by the European Space Agency to develop and qualify the next generation of spectrometers based on La[Br.sub.3] for interplanetary space missions. We contrast their performance to large volume Ge detectors and show that in the context of minimally resourced spacecraft, they represent a more attractive solution. Index Terms--Extraterrestrial measurements, Gamma-ray spectroscopy detectors, remote sensing, scintillation detectors.

Different frequency bands were used for the simultaneous sampling of multiple lines. Findings reveal that the proposed method significantly reduces the time spent on data collection for color flow map (CFM).

The full elastic, piezoelectric and dielectric tensors of two PMN-34.5%PT ceramic and PZN-12%PT single crystal cubes are presented. The piezoelectric sample can be used to measure resonant ultrasound spectroscopy.

Conventional proportional/proportional-integral (P/PI) speed controller for today's servo drives has to be manually tuned at the controller switching set point by trial and error, which may translate into drive system downtime and a subsequent loss of productivity. The adjustable drive performance is heavily dependent on the quality of expert knowledge. The performance becomes inadequate in applications where the operating conditions change in a wide range, i.e., tracking command, acceleration/deceleration time, and load disturbances. In this paper, we discuss the demands on simple controls/setups for industry servo drives. Analyzing the frequency content of the motor torque command, P/PI speed control mode switching is automatically performed with only a prior knowledge of the mechanical time constant. The dynamic performance of the proposed scheme assures a desired tracking response curve with minimal oscillation and settling time over the entire set of operating conditions. For a comprehensive comparison of conventional P/PI control scheme, we carried out extensive tests on an actual servo system. Index Terms--Frequency content of motor torque, industry servo drive, proportional/proportional-integral (P/PI) speed controller, simple controls/setups.

In this Paper we describe the performance of a radhard diode (AI/p+/n/n+/Al), developed in the framework of research and development programs for the future CMS experiment at LHC, for detection and spectrometry of X-and ')'-rays envisaging its use in characterization of porous structures by X-ray tomography. The diode's response was studied using [sup.57]Co, [sup.133]Ba, and [.sup.241]Am radioactive sources at room temperature. A reasonable good energy resolution was obtained in the energy range between 30 and 360 keV (FWHM = 5.2 keV and 5.7 keV, respectively). In the same energy range, measurements of full-energy peak efficiencies were carried out and compared with the theoretical values. For 59.5 keV photons the angular dependence of the efficiency was also measured. The results have demonstrated that this diode is appropriate for direct detection of low energy electromagnetic radiation. Index Terms--Microtomography, rad-hard silicon detectors, X-ray spectrometry.

In this paper, emission spectra of both positive column (PC) and negative glow (NG) regions of the dc glow discharge have been measured at different pressures and currents. The intensity of the lines in the NG is in the order of five times of that corresponding lines' intensity in the PC region. It is found that the line intensity increases linearly with the discharge current, while it increases as [P.sup.[alpha]] with the gas pressure. The electron temperature [T.sub.e] has been estimated using the line-to-line-intensity-ratio technique. It is found that [T.sub.e] derived by this technique generally decreases with the pressure. Also, [T.sub.e] in NG region is about 3/2 of that in the PC. Index Terms--Diagnostics, electron temperature, gas discharge, plasma, probes, spectroscopy.

Efficient and accurate imaging spectroscopy data processing asks for perfectly consistent (i.e., ideally uniform) data in both the spectral and spatial dimensions. However, real pushbroom-type imaging spectrometers are affected by various point spread function (PSF) nonuniformity artifacts. First, individual pixels or lines may be missing in the raw data due to bad pixels originating from the detector, readout errors, or even electronic failures. Second, so-called smile and keystone optical aberrations are inherent to imaging spectrometers. Appropriate resampling strategies are required for the preprocessing of such data if emphasis is put on spatial PSF uniformity. So far, nearest neighbor interpolations have been often recommended and used for resampling. This paper shall analyze the radiometric effects if linear interpolation is used to optimize the spatial PSF uniformity. For modeling interpolation effects, an extensive library of measured surface reflectance spectra as well as real imaging spectroscopy data over various land cover types are used. The real measurements are systematically replaced by interpolated values, and the deviation between original and resampled spectra is taken as a quality measure. The effects of nearest neighbor resampling and linear interpolation methods are compared. It is found that linear interpolation methods lead to average radiometric errors below 2% for the correction of spatial PSF nonuniformity in the subpixel domain, whereas the replacement of missing pixels leads to average errors in the range of 10%-20%. Index Terms--Imaging spectroscopy, interpolation, remote sensing, uniformity.

Dielectric spectroscopy data from measurements on four insect species from 200 MHz to 20 GHz over a temperature range from 10 to 70 [degrees]C are described through reduction of numerous micromotions to a few collective motions, recognition of a low-frequency dispersion through ratio presentation format, application of a self-consistent iteration procedure, a separation procedure for types of collective motions, and application of the eigen-coordinates method for calculation of seven fitting parameters. Use of such fitting parameters to describe the total system relaxation processes quantitatively should enable practical uses of dielectric spectroscopy for measuring desired qualities or characteristics of biological and other complex materials. This general approach based on the reduction procedure and the use of different formats, including the original fitting procedure, allows more precise determination of the corresponding fitting function and description of dielectric spectra of complex systems. The application of this general methodology can be considered as the basic goal and motivation for this paper. Index Terms--Permittivity, dielectric spectroscopy, dielectric relaxation, insects, reduced collective motions, eigen-coordinates method.

An X-ray system with a large area detector has high scatter-to-primary ratios (SPRs), which result in severe artifacts in reconstructed computed tomography (CT) images. A scatter correction algorithm is introduced that provides effective scatter correction but does not require additional patient exposure. The key hypothesis of the algorithm is that the high-frequency components of the X-ray spatial distribution do not result in strong high-frequency signals in the scatter. A calibration sheet with a checkerboard pattern of semitransparent blockers (a 'primary modulator') is inserted between the X-ray source and the object. The primary distribution is partially modulated by a high-frequency function, while the scatter distribution still has dominant low-frequency components, based on the hypothesis. Filtering and demodulation techniques suffice to extract the low-frequency components of the primary and hence obtain the scatter estimation. The hypothesis was validated using Monte Carlo (MC) simulation, and the algorithm was evaluated by both MC simulations and physical experiments. Reconstructions of a software humanoid phantom suggested system parameters in the physical implementation and showed that the proposed method reduced the relative mean square error of the reconstructed image in the central region of interest from 74.2% to below 1%. In preliminary physical experiments on the standard evaluation phantom, this error was reduced from 31.8% to 2.3%, and it was also demonstrated that the algorithm has no noticeable impact on the resolution of the reconstructed image in spite of the filter-based approach. Although the proposed scatter correction technique was implemented for X-ray CT, it can also be used in other X-ray imaging applications, as long as a primary modulator can be inserted between the X-ray source and the imaged object. Index Terms--Cone-beam CT, primary modulation, scatter correction, X-ray scatter.

The 4th-generation readout system based on VAS_UM/TAT4 ASICs for 3-D position sensitive CdZnTe/Hg[I.sub.2] detector arrays has been developed and tested. Each VAS_UM/TAT4 chip is a 129-channel self-triggered monolithic Application Specific Integrated Circuit (ASIC). One 3-D position-sensitive detector module consists of one CdZnTe or Hg[I.sub.2] gamma-ray spectrometer, and one VAS_UM/TAT4 ASIC mounted on a 2.2 cm x 2.2 cm front-end board. Each detector has an array of 11 by 11 pixel anodes fabricated on the anode surface with an area up to 2 cm x 2 cm. The detector and the front-end board are connected by three pairs of 42-pin connectors for easy assembly and component replacement. Up to nine detector modules can be plugged into a single motherboard to form a 3 by 3 detector array. The VAS_UM/TAT4 chip can read out both the amplitude of induced charge on each electrode and the electron drift time needed for reconstructing energy deposition and three-dimensional coordinates of each radiation interaction. Three different sets of VAS_UM/TAT4 chips with different dynamic ranges and shaping times were fabricated for gamma-ray spectroscopy in CdZnTe and Hg[I.sub.2]. These are the first ASIC readout systems that allow multiple 3-D position sensitive CdZnTe/Hg[I.sub.2] detector modules to be tiled together, to achieve a detection volume greater than 50 [cm.sup.3] on a single detector plane. Multiple planes of detector arrays can be operated together to achieve more than 100 [cm.sup.3] detection volume on a single system. In this paper, the VAS_UM/TAT4 ASIC systems are described and their test results are reported. Index Terms--Array, CdZnTe, CZT, position sensitive, readout, spectrometer, three-dimensional (3-D).

Indium iodide (InI) is a compound semiconductor with a wide band gap. Due to its high atomic number ([Z.sub.In] : 49 and [Z.sub.I] : 53) and high density (5.31 g/[cm.sup.3]), InI exhibits high photon stopping power similar to that of CdTe. Since InI has wide band gap energy (2.0 eV), radiation detectors fabricated from InI are expected to realize low-noise operation at and above room temperatures. These physical properties indicate that InI is a very promising material for fabrication of room temperature X- and gamma-ray detectors. In this study, radiation detectors were fabricated from InI crystals. InI materials were purified by the multi-pass zone-refining method up to 80 times. InI crystals were grown by the traveling molten zone (TMZ) method with the zone-purified materials. The resultant InI radiation detectors were evaluated by measuring their electrical property, spectral responses and long-term stability. The resistivity of the InI detectors were found to be approximately 3 x [10.sup.9] ([OMEGA]cm). The InI detector exhibited a clear peak corresponding to 22 keV X-rays from a [10.sup.9] Cd radioactive source at room temperature. To evaluate the long-term stability of the InI detectors, temporal change of the energy spectra of the detectors was measured for a period of time at 20[degrees]C and at -20[degrees]C. At 20[degrees]C, the InI detectors exhibited some degradation in spectral response. On the other hand, the InI detectors operated stably for more than 32 hours at -20[degrees]C. Index Terms--Crystal growth, gamma-ray spectroscopy, radiation detectors, semiconductor materials.

Original lanthanum halide scintillators suffered significantly from internal alpha contamination due to [sup.227]Ac. As the effect of this contamination has been substantially reduced, and the crystal sizes have grown towards volumes that are useful for many applications, the effect of the gamma-, beta-, and x-ray-contamination due to [sup.138]La in these materials has risen to the foreground. This paper discusses and quantifies the current status of lanthanum halide contamination. Included are comparisons with other internally-contaminated, commercially-available scintillators and computer simulation results to breakdown contamination versus background contributions. Although the high resolution of the lanthanum halides holds great promise, the internal activity clearly places limits on their superiority. Index Terms--Gamma spectroscopy, internal contaminants, [sup.138]La, La[Cl.sub.3]: Ce, scintillator.

We have developed a CMOS circuit to be used with Silicon Drift Detectors (SDDs) for X-ray spectroscopy and [gamma]-ray imaging applications. The circuit operates with the input transistor integrated directly on the detector wafer. The circuit is composed of 8 analog channels, each including a low-noise voltage preamplifier, a 6th order semi-Gaussian shaping amplifier, with four selectable peaking times from 1.8 [micro]s up to 6 [micro]s, and a peak stretcher. The integrated time constant used for the shaping are implemented by means of a recently proposed 'RC' cell. This cell is based on the de-magnification of the current flowing in a resistor R thanks to the use of current mirrors. The 8 analog channels of the chip are multiplexed to a single analog output. A digital section provides self-resetting of the channels, trigger output and the external programming of independent threshold on the analog channels by means of a 3 bit DAC and a programmable serial register. In this work, the main features of the circuit are described. The measurement results obtained in the characterization of the prototype are then reported and discussed. The energy resolution measured using a single channel of the chip with a Silicon Drift Detector Droplet ([SDD.sup.3]) is of 128 eV at 6 keV with the detector cooled at -20[degrees]C. Spectroscopy measurements using a multi-element SDD are also shown. Index Terms--Low-noise readout circuit, silicon detectors, silicon drift detectors.

A fully digital trigger technique is presented. It is based on evaluating the occurrence or the absence of an event on a statistical basis. This allows very low-level discrimination for isolated events as well as high time resolving capabilities, i.e., double event discrimination, provided that the events are sufficiently energetic. These two conflicting requirements are met by using a single processing architecture. The theory of the underlying optimum filter and a less resource-hungry processor are carried out and their relative performance compared. Self-calibration and self-optimization of the algorithm with respect to the actual noise conditions have also been implemented. The user can easily adapt to his/her requirements the balance between false triggering reduction, low-level discrimination, and multiple event rejection. Index Terms--Digital spectroscopy, high-resolution spectroscopy, trigger, prediction.

The process of hydrophobic recovery of surface-polluted silicone rubber weather sheds on high voltage (HV) composite insulators was studied by applying an artificial kaolin coating to a sample of clean silicone rubber surface. Quantitative analysis of the kaolin coating into which had diffused low molecular weight silicones (LMWS) was achieved using diffuse reflectance infra red spectroscopy (DRIFT). The results show that: the recovery of hydrophobicity is due to the diffusion of LMWS to the surface from the bulk of the insulator rather than the re-orientation of surface molecules; the LMWS concentration in the contaminant is dependent on its concentration in the bulk of the rubber; and at least 60 % of the final surface concentration was reached within 24 hours and a plateau reached in 10-15 days. However, the diffusion rate was not affected by temperature in the range from 30 to 80 [degrees]C. The results also show that ageing may facilitate the diffusion process. Analysis of the LMWS concentration in the small amounts of real pollutants on insulators returned from service was also achieved using DRIFT by adding an internal standard. Electrostatic deposition of kaolin on rubber surfaces successfully mimics 'real world' processes and is an aid in determining the condition of these materials. Index Terms--Silicone rubber insulators, diffusion, surface contamination, diffuse reflectance infra red spectroscopy, low molecular weight silicone.

The subject matter of this paper refers to the application of optical spectral diagnostics to the detection of electromagnetic waves generated by partial discharges. The research work refers to creeping discharges at bakelite/oil interface. The analysis of optical spectrum time changes was performed. The influence of voltage on the changes of the creeping discharge optical spectrum was determined. The spectrum distibutions were determined in the area of creeping discharges. The results obtained at this stage of the research can constitute a source material for people dealing with issues connected with electrical material science and diagnostics of insulation systems. Index Terms--Optical spectroscopy, surface discharges, radiometry, oil insulation.

The temperature dependent dielectric spectroscopy in frequency domain is compared to physicochemical and electrical tests that are periodically applied on highly insulating transformer oils. Complex permittivity and tank data are obtained as a function of frequency and operation temperatures, to demonstrate the polarization phenomena and the induced loss intensification by the thermally stimulated currents. The acquired dielectric data of oil samples collected from 201 operating High Voltage (HV) power transformers, were correlated to their corresponding physicochemical ones in order to demonstrate the future potential employment of the proposed measuring technique in the field of high voltage engineering, towards reliability monitoring of oil filled electrical equipment (OFEE). Index Terms--Dielectric spectroscopy, Dielectric liquids, Dielectric losses, Dielectric polarization, Permittivity measurement, Oil insulation, Insulation testing

A portable fiber-optic spectroscopic system (TRANSPEC) has been developed for nondestructive measurement of aged transformer insulating paper. Following successful measurement of degree of polymerization (DP) of a range of transformer-aged paper samples, the system has now been shown to separate the oil and paper information for measurement of DP in oil-wetted paper samples. In addition, the system has been shown to be capable of the prediction of both oil and water content of paper to a high accuracy, and is also capable of identifying and quantifying different water species. Spectroscopic measurements have been used together with gravimetric water adsorption measurements to investigate the kinetics of uptake of water vapour into paper from air in the case of nominally dry and oil-impregnated samples. Relationships between water adsorption parameters and properties of the paper insulation have also been investigated using measurements under controlled conditions. Index Terms--Humidity control, multivariate statistical analysis, oil insulation, paper insulation, power transformers, spectroscopy, weight measurement, water content

New possibilities are opened up utilizing position-sensitive germanium detectors in the X-ray spectroscopy of highly charged heavy ions at GSI-Darmstadt. The recent experiments revealed the need for two-dimensional strip detectors with their inherent advantages concerning spectroscopy and imaging capabilities as well as polarization sensitivity. For the first prototype a germanium diode (70 mm x 41 mm, 11 mm thick) with a boron implanted contact and an amorphous Ge contact was prepared. A 128-strip structure on an area of 32 mm x 56 mm with a pitch of 250 [micro]m on the front contact (implanted) and a 48-strip structure with a pitch of 1167[micro]m on the rear contact (amorphous Ge) are realized with the help of plasma etching. The detector is mounted in a cryostat which will enable any orientation of the detector with respect to a photon source. The results of laboratory tests and planned applications at the ESR storage ring in Darmstadt are presented.

The promise of good energy and spatial resolution coupled with high efficiency and room temperature operation has fuelled a large international effort to develop cadmium zinc telluride (CZT) for hard X-ray applications. We are involved on the development of a hard X-ray telescope based on multilayer optics and focal plane detector operative in the 10-80 keV energy range. This telescope requires a high efficiency focal plane providing both fine spatial resolution and spectroscopy with a compact and robust design. This paper reports preliminary results on the characterization both in spectroscopic and spatial response of two small pixellated CZT detectors (10 x 10 x 1 m[m.sup.3] and 10 x 10 x 2 m[m.sup.3] single crystals) with 0.45 mm pixel size. We present the results obtained using both standard commercial read-out electronics Readout Electronics for Nuclear Applications (RENA) and innovative low noise and low power dissipation ASICs developed within the collaboration. Index Terms--CZT, focal plane, hard X-ray, pixel detector, spectroscopy.

We report a recent study undertaken at the Council for the Central Laboratory of the Research Councils (CCLRC) Rutherford Appleton Laboratory to evaluate the performance of a gas electron multiplier (GEM) coupled with a microstrip gas counter (MSGC) for X-ray spectroscopy. The parameters investigated during this study were effective gain, effective gain stability, and energy resolution at 8.05 keV using Cu-K X-rays. These parameters were studied as a function of drift field, induction field, and potential differences across the GEM holes and that across the MSGC anodes and cathodes. This study demonstrates that a single stage GEM can sustain effective gains up to 6000 whilst retaining adequate X-ray energy resolution. By utilizing the MSGC as well as the GEM amplification the gains easily exceed 100 000 and allow the MSGC operation at much lower voltages. This study also demonstrates that the introduction of the GEM preamplification to the MSGC enables the operation of the latter at much higher effective gains (30 000) before any degradation in the X-ray energy resolution. Index Terms--Energy resolution, gain stability, GEM, MSGC, X-ray.

Hermetic stainless-steel open-ended coaxial probes have been designed for precision dielectric spectroscopy of biological tissue, such as breast tissue, over the 0.5-20-GHz frequency range. Robust data-processing techniques have also been developed for extracting the unknown permittivity of the tissue under test from the reflection coefficient measured with the precision probe and a vector network analyzer. The first technique, referred to as a reflection-coefficient deembedding method, converts the reflection coefficient measured at the probe's calibration plane to the desired aperture-plane reflection coefficient. The second technique uses a rational function model to solve the inverse problem, i.e., to convert the aperture-plane reflection coefficient to the tissue permittivity. The results of the characterization and validation studies demonstrate that these precision probes, used with the prescribed measurement protocols and data-processing techniques, provide highly accurate and reliable in vivo and ex vivo biological tissue measurements, including breast tissue spectroscopy. Index Terms--Breast tissue, dielectric properties of biological tissue, microwave measurements, open-ended coaxial probe, rational function model (RFM), vector network analyzer (VNA).

We show that observed biases in retrievals of temperature and water vapor profiles from a 12-channel microwave radiometer arise from systematic differences between the observed and model-calculated brightness temperatures at five measurement frequencies between 22 and 30 GHz. Replacing the value for the air-broadened half-width of the 22-GHz water vapor line used in the Rosenkranz absorption model with the 5% smaller half-width from the HITRAN compilation largely eliminated the systematic differences in brightness temperatures. An a priori statistical retrieval based on the revised model demonstrated significant improvements ill the accuracy and vertical resolution of the retrieved temperature and water vapor profiles. Additional improvements were demonstrated by combining the MWRP retrievals with those from the GOES-8 sounder and by incorporating brightness temperature measurements at off-zenith angles in the retrievals. Index Terms--Microwave remote sensing, spectroscopy, thermodynamic profile retrieval, water vapor absorption.

A sensitivity study was performed with the commonly used millimeter-wave propagation model (MPM) to assess the impact of prescribed uncertainty in the temperature dependence of the line-coupling factors used to model the oxygen line shape. In some cases, apparent nonphysical behaviors were noticed and their impact on microwave channels was found to be significant and more importantly, nonremovable by simple calibration or bias removal. The Advanced Microwave Sounding Unit configuration in particular was tested because of its prime importance in current data assimilation. This impact, which reached a maximum of a few Kelvin in some channels, is modulated nonlinearly by the amount of water vapor present in the atmosphere, with maximum impact in dry air situations, which makes it dependent on the brightness temperature itself. These errors directly impact the error budget of any physically based geophysical retrieval. The line shape of these [O.sub.2] lines has impacts across the microwave spectrum, through the wing effects. This includes channels near 23, 36, and 85 GHz, commonly used in operational radiometry. Index Terms--Microwave remote sensing, oxygen absorption, spectroscopy, temperature dependence.

As the physical limits of silicon-based microelectronics are reached, a need for new materials is required in order to continually improve processor speed. Carbon nanotubes have been suggested as a material to fill in where silicon technology leaves off, due to their small dimensions and unique metallic and semiconductor properties. In order to better understand the conditions in which carbon nanostructures are formed, a detailed plasma analysis has been performed on a gaseous electronics conference (GEC) plasma chamber. This analysis includes plasma composition, rotational temperatures, and spatially resolved hydrogen actinometry during carbon nanostructure growth. Index Terms--Carbon-based plasmas, hydrogen actinometry, nanotechnology, plasmas, rotational temperature, spectroscopy.

Atmospheric gravity waves play a significant role in the dynamics and thermal balance of the upper atmosphere. In this paper, we present a novel technique for automated and robust calculation of momentum flux of high-frequency quasi-monochromatic wave components from spectroscopic imaging and horizontal radar wind measurements. Our approach uses the two-dimensional (2-D) cross periodogram of two consecutive Doppler-shifted time-differenced (TD) images to identify wave components and estimate intrinsic wave parameters. Besides estimating the average perturbation of dominant waves in the whole field of view, this technique applies 2-D short-space Fourier transform to the TD images to identify localized wave events. With the wave parameters acquired, the momentum flux carried by all vertically propagating wave components is calculated using an analytical model relating the measured intensity perturbation to the wave amplitude. This model is tested by comparing wave perturbation amplitudes inferred from spectroscopic images with those from sodium lidar temperature measurements. The proposed technique enables characterization of the variations in the direction and strength of gravity waves with high temporal resolution for each clear data-taking night. The nightly results provide statistical information for investigating seasonal and geographical variations in momentum flux of gravity waves. Index Terms--Atmospheric measurement, feature extraction, spectrum analysis, spectroscopic imaging.

We report on the temperature and count-rate dependent noise behavior of an Si-drift detector system using an on-sensor integrated JFET in a source-follower configuration. The readout chain of a 0.8-[micro]m BiCMOS chip consists of a fully differential low-noise postamplifier, current-mode shaper with gated integrator, and analog storage cell. Six channels are processed in parallel using a 6 : 1 multiplexer buffered by a 100-[OMEGA] line driver. The readout chain's power dissipation is ~15 mW/channel. The indexes for parallel, serial, and 1 / f noise of the time-variant signal processor are calculated using weighting functions. For a detector capacitance of ~140 fF and low count rates, the chip's and total electronics' input-referred equivalent noise charge is about 20 and 23 rms electrons, respectively. Due to an almost quadratical increase of the noise indexes with increasing count rate, the signal current deteriorates so that the spectral resolution of a Cu-K[alpha]-emission line at 20 [degrees]C decreases from ~300 eV (full-width at half-maximum) at low count rates to ~850 eV at 600 kilocounts per second. The investigation of the temperature-dependent leakage current for different detectors leads to current densities between 1.5 pA/[mm.sup.2] and 3 pA/[mm.sup.2] at 20 [degrees]C. The simulated and experimental data verify the theoretical results for a wide range of count rates and sensor temperatures. Index Terms--Noise index, silicon drift detector (SDD), spectral resolution, time-variant shaping, weighting function, X-ray spectroscopy.

Experiments and calculations simulating the neutron shadow shield for a reactor-powered space vehicle are described, including calculations for a variety of shield configurations and materials, and an experimental benchmark test using a bare fast reactor. Index Terms--Fission reactors, lithium compounds, Monte Carlo methods, neutron shielding, neutron spectroscopy, radiation effects, radiation transport, space technology.

A quasi-optical deembedding technique for characterizing waveguides is demonstrated using wide-band time-resolved terahertz spectroscopy. A transfer function representation is adopted for the description of the signal in the input and output port of the waveguides. The time-domain responses were discretized and the waveguide transfer function was obtained through a parametric approach in the z-domain after describing the system with an AutoRegressive with eXogenous input (ARX), as well as with a state-space model. Prior to the identification procedure, filtering was performed in the wavelet domain to minimize both signal distortion, as well as the noise propagating in the ARX and subspace models. The optimal filtering procedure used in the wavelet domain for the recorded tune-domain signatures is described in detail. The effect of filtering prior to the identification procedures is elucidated with the aid of pole-zero diagrams. Models derived from measurements of terahertz transients in a precision WR-8 waveguide adjustable short are presented. Index Terms--Identification algorithms, multimode waveguide characterization, signal processing, terahertz spectroscopy.

Pulsed electric fields (PEFs) above a certain voltage threshold cause electroporation for microsecond pulses and intracellular effects for submicrosecond pulses. Models describing these effects often depend on the electrical properties of the cell, which are altered by the PEF. We used time domain dielectric spectroscopy to provide data for these models and to measure effects on cell suspension conductivity. We applied single 50-[micro]s and 10-ns pulses to HL-60 cells, with the voltages chosen so the pulses have approximately the same energy. For 1.l-kV/cm, 50-[micro]s pulses, the conductivity rose within a minute after the pulse and dropped dramatically approximately 40 min after the pulse. For 78-kV/cm, 10-ns pulses, we observed a brief delay prior to the conductivity rise and noted the same drop in conductivity after approximately 40 min. For both pulse durations, higher voltages frequently led to membrane potation followed by a gradual recovery approximately 30--40 min after the pulse. For 2-kV/cm, 50-[micro]s pulses, we observed significantly more scatter in Trypan Blue uptake measurements due to stronger effects on the cell membrane. By using a cell model, we showed that a 50-[micro]s pulse caused a much larger rise in membrane conductivity than a 10-ns pulse of the same energy. Index Terms--Bioelectric phenomena, biological cells, biological effects of electromagnetic radiation, biomembranes, dielectric measurements, pulse power systems.

High spatial- and temporal-resolution spectroscopic methods are employed to perform detailed studies of the interaction between the propagating magnetic field and a multi-ion-species plasma. The experiment is performed in a plasma-opening-switch configuration, in which a 150-kA current of ~400 ns duration is conducted through a plasma. Recent observations demonstrated a new phenomenon of simultaneous rapid magnetic field penetration into the heavy-ion plasma and specular reflection of the light-ion plasma, leading to ion-species separation. Additionally, noticeable inconsistencies between experimental results and theories were found. The current paper summarizes these recent results and discusses the aspect of the role of the plasma composition in the magnetic field evolution and ion dynamics. In order to systematically investigate the effect of the plasma composition, a method for producing plasmas with controllable compositions, based on spatial species separation and electrode heating, is presented. This method allows for achieving plasmas with varying proton-to-carbon ion ratios, however, at different electron densities. Measurements are described for studying the relation between the magnetic field propagation velocity and the plasma composition and density; however, this relation is not yet satisfactorily clear. Index Terms--Magnetic field-plasma interaction, multi-ion species plasma, plasma devices, plasma spectroscopy.

Scintillators like CsI(Na), having double-exponential decay times, typically cannot be used in high-count rate applications due to the complicated pulse shapes created by the convolution of their light output decay curves with the decay constant of charge integrating preamplifiers. We present here a novel dig. ital filtering algorithm that is capable of using CsI(Na) at input count rates exceeding 250 kcps, while still achieving good energy resolution. We used a 2.54 cm diameter and 2.54 cm long CsI(Na) crystal, whose scintillation light can be best described by a short component with a 550 ns decay time and a long component with a 4 [micro]s decay time. The crystal was coupled to a 2.86 cm diameter photomultiplier tube. The digital filtering algorithm was implemented in XIA's all-digital Polaris spectrometer, in which five running sums were captured from each digitized scintillation pulse and the Polaris's on-board DSP read these sums and used a set of precomputed coefficients to reconstruct the pulse's total light output as a measure of the deposited energy. The algorithm was tested at different input count rates, ranging from 19 kcps to 270 kcps using a 1 m[Ci.sup.137] Cs source. The energy resolution (full-width at half-maximum) at 662 key was 10.7% at 19 kcps and 11.7% at 270 kcps with a filter rise time of 1.0 [micro]s, and improved to 7.0% and 8.4%, respectively, with a filter rise time of 3.2 [micro]s. The energy peak shifted by less than 0.3% for input count rates below the maximum throughput point. Output count rates of 65.3 and 17.8 kcps were obtained with filter rise time of 1.0 and 3.2 [micro]s, respectively, at an input count rate of 270 kcps. This algorithm can be easily adapted to other double-exponential decaying scintillators by changing the decay times used in the energy reconstruction formula. Index Terms--Author, please supply your own keywords or send a blank e-mail to keywords@ieee.org to receive a list of suggested keywords.

COMPASS, the fixed-target experiment at CERN studying the structure of the nucleon and spectroscopy, has collected over 500 TB during 2002 and 2003 runs. At the beginning of the experiment these data together with the reconstructed events information were put in a database infrastructure based on Objectivity/DB and on the hierarchical storage manager CASTOR. Starting from 2003 Oracle has been adopted as the database technology. The experience in the usage of the databases is reviewed, and the evolution of the system outlined. Index Terms--Computing in high-energy physics, database management systems, data management, spectroscopy, elementary particles, high-energy data stores.

Advances in manufacturing technology for microstructures are allowing new opportunities for vacuum electron devices producing radio-frequency (RF) radiation. Specifically, the capability to produce small circuit structures is allowing development of RF devices at frequencies impractical with traditional machining technology. This is generating increased interest in applications in the submillimeter and terahertz frequency range. High-power RF devices in this frequency range are needed for medical, communications, defense, and homeland security applications. This paper describes the most promising microfabrication techniques applicable to high-frequency RF devices and examples of recent applications. Index Terms--Backward wave oscillator (BWO), cold cathode, deep reactive ion etching (DRIE), electrical discharge machining (EDM), field emission, field emitter array (FEA), focused ion beam (FIB), LIGA, radiation, RF source, spectroscopy, SU-8.

Data obtained from measurements of complex impedance spectroscopy (constant sample temperature, varying electric field frequency) and dielectric dynamic thermal analysis (sample heated at a constant rate, constant electric field frequency) on Na-Mordenite (a zeolite) samples are presented and compared. Specifically, the shape and energies of the distribution of activation energies obtained from each experimental technique are compared. The two distributions are similar. However, the data obtained from dielectric dynamic thermal analysis (DDTA) seem to be independent of some experimental conditions, e.g. sample geometry and the sample/electrode interface. DDTA therefore appears to be a useful technique for investigation of dielectric relaxation in ionic solids. Index Terms--Dielectric relaxation spectroscopy, complex impedance spectroscopy, dielectric dynamic thermal analysis, distribution of activation energies, space charges.

The main principles of time domain dielectric spectroscopy, its application to conductive systems and possible methods of electrode polarization corrections in time domain are introduced. A comprehensive theoretical and experimental study of static and dynamic dielectric properties of different biological systems including globular and membrane proteins, hydrate water, human erythrocytes, and normal and malignant blood cells of different types is presented in the paper. Index Terms--Dielectric spectroscopy, biological materials, globular and membrane proteins, hydrate water, human blood cells.

Spectral behavior of spatially coherent polychromatic Hermite-Gaussian (H-G) beams focused by an aperture lens is examined and discussed.

Thick mercuric iodide (Hg[I.sub.2]) detectors are investigated as potential room temperature gamma-ray spectrometers. By using pixelated anodes the induced charge on the electrode is dependent mainly on electron movement and is almost independent of the depth of interaction. Moreover, by reading out the planar cathode signal simultaneously, the depth of interaction can be determined and any effects of electron charge loss can be corrected. By combining these two methods (pixelated anodes and depth sensing), the resolution from 1 cm thick [HgI.sub.2] devices can be improved to 1.4% FWHM when using a Cs-137 point source. These results were obtained using a modest electric field (2500 V/cm) and relatively short shaping times (4-16 [micro]s) for [HgI.sub.2]. A comparison between conventional planar readout and single polarity charge sensing techniques with wide band-gap semiconductors is discussed. Index Terms--Gamma-ray spectroscopy, mercuric iodide, room temperature.

We present the design of the gamma-ray and neutron spectrometer (GR/NS) for Dawn, which is a NASA Discovery-class mission to explore two of the largest main-belt asteroids, 1 Ceres and 4 Vesta, whose accretion is believed to have been interrupted by the early formation of Jupiter. Dawn will determine the composition and structure of these protoplanetary bodies, providing context for a large number of primitive meteorites in our sample collection and a better understanding of processes occurring shortly after the onset of condensation of the solar nebula. The Dawn GR/NS design draws on experience from the successful Lunar Prospector and Mars Odyssey missions to enable accurate mapping of the surface composition and stratigraphy of major elements, radioactive elements, and hydrogen at both asteroids. Here, we describe the overall design of the GR/NS and compare the expected performance of the neutron spectrometer subsystem to the neutron spectrometer on Mars Odyssey. We also describe radiation damage studies carried out on CdZnTe detectors, which will be components of the primary gamma-ray spectrometer on Dawn. We conclude that provisions for annealing at moderate temperatures (40[degrees]C to 60[degrees]C) must be made to ensure that the spectrometer will function optimally over the nine-year mission. Index Terms--Gamma-ray spectroscopy, planets, neutron spectroscopy, semiconductor device radiation effects.

We describe a new amplitude specific integrated circuit (ASIC) for accurate and efficient processing of high-rate pulse signals from highly segmented detectors. In contrast to conventional approaches, this circuit affords a dramatic reduction in data volume through the use of analog techniques (precision peak detectors and time-to-amplitude converters) together with fast arbitration and sequencing logic to concentrate the data before digitization. In operation the circuit functions like a data-driven analog first-in, first-out (FIFO) memory between the preamplifiers and the analog-to-digital converter (ADC). Peak amplitudes of pulses arriving at any one of the 32 inputs are sampled, stored, and queued for readout and digitization through a single output port. Hit timing, pulse risetime, and channel address are also available at the output. Prototype chips have been fabricated in 0.35 micron CMOS and tested. First results indicate proper functionality for pulses down to 30 ns peaking time and random input rates up to 1.6 MHz on a single channel. Amplitude accuracy of the peak detect and hold circuit is 0.3% (absolute). TAC accuracy is within 0.3% of full scale. Power consumption is less than 2 mW/channel at the maximum counting rate. Compared with conventional techniques such as track-and-hold and analog memory, this new ASIC will enable efficient pulse height measurement at 20 to 300 times higher rates. Index Terms--Analog memory, derandomizer, peak detector, spectroscopy.

A study of the spectroscopic performance of a CdTe detector, equipped with a 'strip anode' placed between two parallel focusing strips, was carded out. The focusing strips were kept at an intermediate bias voltage with respect to anode and cathode. This configuration increases the intensity and focuses the weighing field on the region surrounding the strip anode, thus improving the uniformity of signals due to the collection of electrons. The detector was irradiated with a narrow photon beam emitted by a [sup.57]Co source. When the photon beam is impinging perpendicularly to the cathode plane, the spectroscopic response of the strip anode detector looks better than that obtained by the usual 'full anode' CdTe detectors, especially with regard to the photopeak in the 122-keV energy region. Previous measurements carried out on detectors having the same crystal size, but equipped with a full anode, showed a considerable improvement in spectroscopic performance at 122 keV, when the photon beam was impinging on the detector at almost grazing angle with respect to the cathode surface [1]. In this paper, a similar set of measurements at variable angle of the photon beam is carried out on detectors having strip anode configuration in order to investigate their behavior under the same experimental conditions. Index Terms--CdTe spectrometer, microstrip detectors, semiconductor detectors, various irradiation angles, X- and Gamma-ray spectroscopy.

Microwave [H.sub.2], [N.sub.2], and [N.sub.2]-Ar discharges driven by traveling surface waves are investigated as sources of ground state N([sup.4]S]), H(1s) atoms. The dissociation kinetics is discussed in the framework of theoretical models based on a self-consistent treatment of the main discharge balances, wave electrodynamics and plasma-wall interactions. It is shown that the number density of hydrogen H(1s) atoms depends heavily on the wall conditions at low pressure conditions. The kinetics of N([sup.4.]S]) and metastable N([sup.2]D]) and N([sup.2]P) atoms and of the molecular [N.sub.2] ([A.sup.3][[SIGMA].sup.+.sub.u] metastable state in a pure [N.sub.2] [N.sub.2] discharge are shown to be strongly coupled. One Possible way to control and to enhance nitrogen dissociation is the use of an [N.sub.2]-Ar mixture. The increase in dissociation degree of [N.sub.2] molecules at high Ar fractional concentration can be attributed to dissociative recombination between electrons and [N.sup.+.sub.2] positive ions. The predicted results for the atomic density are compared with emission spectroscopy data. Index Terms--Argon, dissociation, hydrogen, microwave discharge, modeling, nitrogen, plasma-wall, spectroscopy.