This PDF file contains the front matter associated with SPIE Proceedings Volume 7079, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

Virtual Frisch-grid CdZnTe detectors potentially can provide energy resolution close to the statistical limit. However, in real detectors, the quality of the crystals used to fabricate the devices primarily determines energy resolution. In this paper, we report our findings on the spectral response of devices and their relation to material-characterization data obtained using IR microscopy and X-ray diffraction topography.

Long term reliability is critical for a detector module to be used in applications that can not afford failure and require high accuracy such as medical imaging and homeland security. In this study, we report the reliability of pixellated Cadmium Zinc Telluride (CZT) detector modules fabricated from crystals grown by the Traveling Heater Method (THM). The reliability of the module which consists of the pixellated detector assembled to a PCB carrier board via conductive epoxy was studied with both a Quantitative Accelerated Life Test (QALT) as well as the Highly Accelerated Stress Test (HAST) which is a common form of a Qualitative Accelerated Life test. The robustness of the THM pixellated CZT detector modules is demonstrated via the pre- and post- accelerated life test comparison of the leakage current and the spectral performance of the assembled module. A shear test was also used to ensure the adhesion strength of the epoxy bonded method. To our knowledge, this type of study on pixellated CZT detector module has been very rare if not the first of its kind.

Perforated semiconductor diode detectors have been under development for several years at Kansas State University for a variety of neutron detection applications. The fundamental device configuration is a pin diode detector fabricated from high-purity float-zone refined Si wafers. Perforations are etched into the diode surface with inductively-coupled plasma reactive ion etching and backfilled with ⁶LiF neutron reactive material. The perforation shapes and depths can be optimized to yield a flat response to neutrons over a wide variation of angles. The intrinsic thermal neutron detection efficiency depends strongly upon the geometry, size, and depth of the perforations. Here three basic geometry models are compared. The energy deposition spectra and detection efficiency are estimated for rod-shaped perforations, linear trench perforations and for perforations leaving silicon pillars. These three designs are found to have distinct differences in their capabilities. Besides model calculations, practical considerations for fabricating such neutron detectors are also discussed.

We present measured data on the neutron detection response of the GammaTracker handheld radioisotope identifier. Two neutron detection modes are discussed: measuring absorption gamma rays from the cadmium present in the Cd-Zn- Te spectrometers, and measuring the absorption gamma rays from moderator material present in the environment. In both cases, the capture gamma rays can be imaged to help locate a shielded neutron source. In this work, we discuss the total neutron detection efficiency of the GammaTracker instrument, and we present measured images of shielded neutron sources. Prospects for gamma-ray rejection are discussed.

Detection of nuclear materials is critical in preventing traffic of illicit nuclear materials. Several methods that are based on detection of spontaneous or induced emission of fission neutron are considered. Efficient fast and thermal neutron detectors are generally required. For some applications these detectors must have fast response and should be deployed with large or small detection area. This work expands upon the basic concept of coating a p-n junction solar cell with a neutron detection layer that typically employs either ⁶Li or ¹⁰B. ¹⁰B has a larger absorption cross section and results in higher detection efficiency. When an incident neutron interacts with ¹⁰B, it releases an α-particle and a ⁷Li ion; this α-particle excites electron-hole-pairs in the silicon p-n junction. This work investigated a variety of different silicon trench/pillar/hole geometries in combination with the ¹⁰B filling or coating; thermal neutron detection efficiencies as high as 30% are projected. It utilizes trenches spaced as closely as 2 μm and 50 μm deep. Simulations predict that when these single layer detectors are bonded in a multiple layer configuration, efficiencies in the range of 90% could be achieved. Along with nuclear and electrical simulations, a highly controllable deep-reactive-ion-etching (DRIE) recipe is developed for trench/pillar/hole etching. The ability to create p-n junctions along those trenches is presented. Trenches and pillars as small as 2 μm by 2 μm are fabricated and p-n junctions are created along their surface. Smooth, uniform trenches are ready for trench refilling procedures.

The overall goal of this research is to develop and apply computational modeling to better understand the processes used to grow bulk crystals employed in radiation detectors. Specifically, the work discussed here aims at understanding the growth of cadmium zinc telluride (CZT), a material of long interest to the detector community. We consider the growth of CZT via gradient freeze processes in electrodynamic multizone furnaces and show how crucible mounting and design are predicted to affect conditions for crystal growth. Analysis of these systems will be essential for for significant materials improvement, i.e., growing larger crystals with superior quality and at a lower cost.

Surface passivation and final surface treatment on the lateral sides of CdZnTe/CdTe gamma ray detectors have been studied by many research groups. However, systematic studies of spectroscopic performance and the current voltage (I-V) characteristic behavior of devices as a result of surface treatments have not been conducted. Additionally, few studies report results for high energy gamma ray detection, which requires different techniques and technologies. In this study, a variety of final surface treatments and oxidizing agents have been applied on different CdZnTe detectors, and the effects on the I-V characteristic behavior and spectral performance of Frisch collar devices at 662 keV are reported. Further, the possibility of an alternative method is investigated, in which ion milling is utilized to etch the lateral surfaces with energetic ions of Xenon. The process is described in detail and the challenges are presented. Electron Microprobe (EMP) technique was performed on the device sides to determine the surface elements using Energy Dispersive Spectroscopy (EDS) before and after each treatment. The CdZnTe materials for this study were acquired from Redlen Technologies, and the CdZnTe devices were fabricated and characterized for each treatment at the S.M.A.R.T. Laboratory at Kansas State University.

Surface electronic properties of Cd_xZn_yTe were characterized through scanning spreading resistance microscopy (SSRM) and correlated IR transmittance maps. We observed the magnitude of the SSRM current is dominant by the density of surface localized Te precipitates and spatial variation of Zn content. The magnitude of the average SSRM current for forward probe bias was found to correlate strongly with the density of Te precipitates, while the variation in I-V characteristics were caused by slight p-type or n-type characteristics due to non-uniformity in Zn content of the crystal. Experimentally observed I-V characteristics were simulated using thermionic emission theory.

The novel 3-D display system is required in the medical treatment field and non-destructive testing field. In these field, the X-ray CT system is used for obtaining 3-D information. However, there are no meaningful 3-D information in X-ray CT data, and there are also no practical 3-D display system. Therefore, in this paper, we propose an X-ray 3-D CT display system by combining a photon-counting X-ray CT system and a holographic image display system. The advantage of this system was demonstrated by comparing the holographic calculation time and recognizability of a reconstructed image.

Native and impurity point defects, complexes and extended defects which are formed during CdTe crystal growth and fabrication of diode structure are crucial for CdTe-based X-ray and gamma-ray detectors, cause deterioration of parameters and limit widespread practical application. Therefore, control of defect formation in CdTe crystals and device structures is important to achieve excellent charge collection efficiency and high energy resolution. Photoelectric, electrical and spectral properties of M-p-n structured CdTe diodes fabricated by the optimized excimer laser doping technique have been studied at different conditions. To make the diodes, a relatively thick In film was deposited on the surface of CdTe crystal and then it was irradiated with a laser pulse. The film served as an n-type dopant source as well as an electrode after laser irradiation. A Schottky contact was deposited on the opposite side of CdTe crystals. The In/CdTe/Au detectors have showed promise for nuclear radiation devices. However, the variations of I-V and C-V characteristics, fluctuations of time dependences of leakage current and degradation of spectral characteristics were evidences that electrically active defects cause non-uniform carrier trapping and induce excessive noise, deteriorating the detector performance.

A photon-counting K-edge x-ray Computed Tomography (CT) system is useful for discriminating photon energy and for decreasing absorbed dose for patients. The CT system is of the first generation type and consists of an x-ray generator, a turn table, a translation stage, a two-stage controller, a multipixel photon counter (MPPC) module, a 0.5-mm-thick zinc oxide (ZnO) scintillator, a counter board (CB), and a personal computer (PC). Tomography is accomplished by repeating the translation and rotation of an object. Penetrating x-ray photons from the object are detected by the scintillator in conjunction with the MPPC module, and the event signals are counted by the CB. Without using energy discriminating, photon counting CT was carried out by controlling x-ray spectra.

We have proposed a new system for X-ray computed tomography (CT) scanning. By employing the dual-energy measurement, the obtained data can be used to deduce distribution images of the atomic number and electron density which are useful for identifying the scanned material. In this work, two different methods were given for the derivative process. We found method A was suitable for measuring low-Z materials while method B worked well for high-Z materials. Therefore, the two derivative methods may work complementally for material identification.

Long-term stability of TlBr detectors with Tl electrodes was evaluated in this study. Tl/TlBr/Tl detectors were fabricated and tested with a charge sensitive preamplifier and a spectroscopy amplifier and a gated integrator. Significant improvement of energy resolutions was realized by applying the gated integrator to the TlBr detectors. The full-energy peak positions, counts and resolutions for 662 keV gamma-rays from ¹³⁷Cs were monitored during the course of measurements (10 days). By changing the polarity of the applied bias voltages every 24 hours, the Tl/TlBr/Tl detectors exhibited stable spectroscopic performance for totally over 240 hours.

TlBr is a promising semiconductor for gamma-ray detection at room temperature, but it has to be extremely pure to become useful. We investigated the purification and crystal growth of TlBr to improve the mobility and lifetime of charge carriers, and produce TlBr detectors for radioisotopic detection. Custom equipment was built for purification and crystal growth of TlBr. The zone refining and crystal growth were done in a horizontal configuration. The process parameters were optimized and detector grade material with an electron mobility-lifetime product of up to 3x10^-3 cm²/V has been produced. The material analysis and detector characterization results are included.

Growth of mercuric iodide platelets in horizontal furnaces with the addition of polyethylene powder has been analyzed with a 2³ full factorial analysis. The factors investigated were the temperature gradient between the zones, the source/hot zone temperature, and the amount of polyethylene powder. The crystallization zone length was chosen as the observable. Normal probability and Lenth's plots were used to analyze the effects. Both plots show that the temperature gradient is an active effect.

CdMnTe (CMT) can be a good candidate for producing gamma-ray detectors because of its wide band-gap, high resistivity, and good electron transport properties. Further, the ability to grow CMT crystals at relatively low temperatures ensures a high yield for manufacturing detectors with good compositional uniformity and few impurities. Groups at Brookhaven National Laboratory and Institute of Physics are investigating several CMT crystals, selecting a few of them to make detectors. In this paper, we discuss our initial characterization of these crystals and describe our preliminary results with a gamma-ray source.

The layered anisotropic chalcogenide semiconductors GaSe and GaTe single crystals have been grown by a modified vertical Bridgman technique using high purity Ga (7N) and in-house zone refined (ZR) precursor materials (Se and Te). The crystals harvested from ingots of up to 10 cm length and up to 2" diameter, have been characterized by measuring resistivity through current-voltage (I-V) characteristics and bulk carrier concentration and mobility through Hall effect measurements. Micro-hardness, infrared microscopy, etching characteristics, low-temperature photoluminescence (PL) and contact resistivity studies have also been performed to further characterize the grown crystals.

We investigate amorphous Selenium Frisch-grid detector design to improve the spectral performance, reliability of single photon detection, and image lag for radiation imaging and detection. Incomplete charge collection due to the low electron mobility in amorphous Selenium results in depth-dependent signal variations. The slow signal rise-time for the portion of the induced charge due to electron-movement towards the anode and significant electron trapping cause ballistic deficit. This phenomenon can be observed from spectrum tailing (also called "electron tailing" for a-Se) and the wide Gaussian spectrum at low photon energies. The implications of this analysis for the design of new Selenium-based photoconductors are discussed, and some preliminary simulation results of the theory are presented.

We have investigated the electronic structures of bulk GaSe and GaTe as well as the nature of defect states associated with substitutional impurities and vacancies in GaSe and GaTe. These calculations were done using <i>ab initio</i> density functional theory and supercell models. We find that the Ga-Ga dimers play an important role in the formation of defect states. Analysis of the charge densities and the band structures associated with the defect states indicates that they are strongly localized. Theoretical results are in good agreement with experiment for Cd_Ga and V_Ga in GaSe and for V_Ga in GaTe. The effect of spin-orbit interaction on the band structure of GaTe has been investigated; it is found that the top valence bands at the Γ-point shift up in energy by ~ 0.1 eV due to the mixing of Te p_x-p_y and p_z bands.

Semi-conducting CdZnTe (or CZT) crystals can be used in a variety of detector-type applications. CZT shows great promise for use as a gamma radiation spectrometer. However, its performance is adversely affected by point defects, structural and compositional heterogeneities within the crystals, such as twinning, pipes, grain boundaries (polycrystallinity), secondary phases and in some cases, damage caused by external forces. One example is damage that occurs during characterization of the surface by a laser during Raman spectroscopy. Even minimal laser power can cause Te enriched areas on the surface to appear. The Raman spectra resulting from measurements at moderate intensity laser power show large increases in peak intensity that is attributed to Te. Atomic Force Microscopy (AFM) was used to characterize the extent of damage to the CZT crystal surface following exposure to the Raman laser. AFM data reveal localized surface damage in the areas exposed to the Raman laser beam. The degree of surface damage to the crystal is dependent on the laser power, with the most observable damage occurring at high laser power. Moreover, intensity increases in the Te peaks of the Raman spectra are observed even at low laser power with little to no visible damage observed by AFM. AFM results also suggest that exposure to the same amount of laser power yields different amounts of surface damage depending on whether the exposed surface is the Te terminating face or the Cd terminating face of CZT.

CdZnTe (or CZT) crystals can be used in a variety of detector-type applications. This large band gap material shows great promise for use as a gamma radiation spectrometer. Historically, the performance of CZT has typically been adversely affected by point defects, structural and compositional heterogeneities within the crystals, such as twinning, pipes, grain boundaries (polycrystallinity) and secondary phases (SP). The synthesis of CZT material has improved greatly with the primary performance limitation being attributed to mainly SP. In this presentation, we describe the extensive characterization of detector grade material that has been treated with post growth annealing to remove the SPs. Some of the analytical methods used in this study included polarized, cross polarized and transmission IR imaging, I-V curves measurements, synchrotron X-ray topography and electron microscopy.

In this work we measured the crystal defect levels and tested the performance of CdZnTe detectors by diverse methodologies, viz., Current Deep Level Transient Spectroscopy (I-DLTS), Transient Current Technique (TCT), Current and Capacitance versus Voltage measurements (I-V and C-V), and gamma-ray spectroscopy. Two important characteristics of I-DLTS technique for advancing this research are (1) it is applicable for high-resistivity materials (>10⁶ Ω-cm), and, (2) the minimum temperature for measurements can be as low as 10 K. Such low-temperature capability is excellent for obtaining measurements at shallow levels. We acquired CdZnTe crystals grown by different techniques from two different vendors and characterized them for point defects and their response to photons. I-DLTS studies encompassed measuring the parameters of the defects, such as the energy levels in the band gap, the carrier capture cross-sections and their densities. The current induced by the laser-generated carriers and the charge collected (or number of electrons collected) were obtained using TCT that also provides the transport properties, such as the carrier life time and mobility of the detectors under study. The detector's electrical characteristics were explored, and its performance tested using I-V, C-V and gamma-ray spectroscopy.

Precision crystal calorimeter traditionally plays an important role in experimental high energy physics. In the last two decades, it faces a challenge to maintain its precision in a hostile radiation environment. This paper reviews the performance of crystal calorimeters constructed for high energy physics experiment and the progress achieved in understanding crystal's radiation damage and in developing high quality scintillating crystals. Future crystal calorimeters, such as a LSO and LYSO calorimeter and homogeneous hadronic calorimeter, being considered for experimental particle physics is also discussed.

Transparent ceramics offer an alternative to single crystals for scintillator applications such as gamma ray spectroscopy and radiography. We have developed a versatile, scaleable fabrication method, using Flame Spray Pyrolysis (FSP) to produce feedstock which is readily converted into phase-pure transparent ceramics. We measure integral light yields in excess of 80,000 Ph/MeV with Cerium-doped Garnets, and excellent optical quality. Avalanche photodiode readout of Garnets provides resolution near 6%. For radiography applications, Lutetium Oxide offers a high performance metric and is formable by ceramics processing. Scatter in transparent ceramics due to secondary phases is the principal limitation to optical quality, and afterglow issues that affect the scintillation performance are presently being addressed.

The growth and scintillating properties of undoped and Eu²⁺ doped Strontium Iodide indicate excellent potential for gamma ray spectroscopy. Energy resolution at 662 keV was found to be as good as 2.7% at 662 keV. The effect of purification by zone refining was also studied and crystal growth of SrI₂ by the Bridgman technique was found to be less subject to cracking compared to the growth of lanthanum halide scintillators.

Energy-discriminating x-ray camera is useful for performing monochromatic radiography using polychromatic x-rays. The x-ray camera was developed to carry out K-edge radiography using iodine-based contrast media. In this camera, objects are exposed by a cerium x-ray generator, and penetrating x-rays are detected by a cadmium telluride (CdTe) detector with an amplifier unit. The optimal x-ray photon energy and energy width are selected out using a multichannel analyzer (MCA), and the photon number is counted by a counter board (CB). Radiography was performed by the detector scanning using an x-y stage driven by a two-stage controller, and x-ray images obtained by energy discriminating are shown in a personal-computer (PC) monitor. Cerium K-series characteristic x-rays are absorbed effectively by iodine based contrast media, and iodine K-edge radiography was performed using x-rays with photon energies just beyond K-edge energy 33.2 keV.

We present the design and initial performance characterization of the XENA-2 readout IC for solid-state x-ray detector arrays. XENA-2 consists of 32 readout channels, each with charge-sensitive input amplifier, adjustable two-stage gain amplifier and five comparators with 16-bit pulse counters. Readout of the counters, over a 16-bit data bus, takes approximately 20 μs. Compared to the XENA chip, its predecessor, this new IC's main improvement is significantly reduced noise, which allows for lower comparator thresholds and increased count rates.

A novel CdTe X-ray image sensor, which was driven by the FEA, was proposed in order to obtain high spatial resolution X-ray images and have demonstrated the principle operation by using the CdTe image sensor with one pixel. We have also fabricated a FEA matrix with 12x12 pixels to obtain X-ray images. For the further improvement of spatial resolution in the CdTe image sensor, we have proposed a novel double-gated FEA with a focusing lens, which was fabricated by using the etch-back method. The double-gated FEA showed a good focusing characteristic without significant decrease of the emission current, when the height of the focus electrode was optimized. The CdTe image sensor driven by the double-gated FEA is promising for an ultra-high-resolution X-ray image sensor.

We have developed high energy and high spatial resolution two-dimensional (2D) solid-state imaging pixel detectors and their custom integrated circuits (ICs). Solid-state pixel detectors and their readout ICs are now regarded to be an integral part of position-sensitive semiconductor detectors such as Si, CdTe and CdZnTe for x-ray and gamma-ray imaging. These detectors have a 2D structure. We have also developed one-dimensional (1D) detectors, which are mostly used for scanning type imaging. The new 2D pixel detectors we have developed can be used for both scanning and staring mode imaging applications. Because the requirements of various detector applications tend to be diverse, a custom IC is typically designed for a specific detector array. This often lengthens the time and raises the cost of system development. To help close the readout technology gap and facilitate advances in this field, we have been formulating and implementing strategies for instrumenting different detectors of a given application category with highly versatile ICs that meet a range of requirements. The solid-state pixel detectors that have been developed within this effort are presented below.

CCDs have been the primary sensor in imaging systems for x-ray diffraction and imaging applications in recent years. CCDs have met the fundamental requirements of low noise, high-sensitivity, high dynamic range and spatial resolution necessary for these scientific applications. State-of-the-art CMOS image sensor (CIS) technology has experienced dramatic improvements recently and their performance is rivaling or surpassing that of most CCDs. The advancement of CIS technology is at an ever-accelerating pace and is driven by the multi-billion dollar consumer market. There are several advantages of CIS over traditional CCDs and other solid-state imaging devices; they include low power, high-speed operation, system-on-chip integration and lower manufacturing costs. The combination of superior imaging performance and system advantages makes CIS a good candidate for high-sensitivity imaging system development. This paper will describe a 1344 x 1212 CIS imaging system with a 19.5μm pitch optimized for x-ray scattering studies at high-energies. Fundamental metrics of linearity, dynamic range, spatial resolution, conversion gain, sensitivity are estimated. The Detective Quantum Efficiency (DQE) is also estimated. Representative x-ray diffraction images are presented. Diffraction images are compared against a CCD-based imaging system.

L-3 Communications Security and Detection Systems (SDS) has developed a new system for automated alarm resolution in airline baggage Explosive Detection Systems (EDS) based on coherent x-ray scattering spectroscopy. The capabilities of the system were demonstrated in tests with concealed explosives at the Transportation Security Laboratory and airline passenger baggage at Orlando International Airport. The system uses x-ray image information to identify suspicious objects and performs targeted diffraction measurements to classify them. This extra layer of detection capability affords a significant reduction in the rate of false alarm objects that must presently be resolved by opening passenger bags for hand inspection.

Recently SrI₂, a scintillator patented by Hofstadter in 1968, has been rediscovered and shown to possess remarkable scintillation properties. The light output of SrI₂:Eu²⁺ has been measured to be even higher than previously observed and exceeds 120,000 photons/MeV, making it one of the brightest scintillators in existence. The crystal also has excellent energy resolution of less than 3% at 662 keV. The response is highly linear over a wide range of gamma ray energies. The emission of SrI₂:Eu²⁺ and SrI₂:Ce³⁺/Na⁺ is well-matched to both photomultiplier tubes and blue-enhanced silicon photodiodes. While SrI₂:Eu²⁺ is relatively slow, SrI₂:Ce³⁺/Na⁺ has a fast response. SrI₂ crystals with many different dopant concentrations have been grown and characterized. In this presentation, crystal growth techniques as well as the effects of dopant concentration on the scintillation properties of SrI₂, over the range 0.5% to 8% Eu²⁺ and 0.5% to 2% Ce³⁺/Na⁺, will be discussed in detail.

Scintillators on the basis of AIIBVI compounds, such as ZnSe(Te), can be used for detection of secondary charged particles coming from nuclear reactions in which neutrons interact with target nuclei of atoms present in transparent materials of dispersion scintillation detectors matrices. Using unique properties of scintillator ZnSe(Te) we show possibility of increase detection efficiency for soft x-ray radiation (20 - 90 keV). The amorphous silicon flat panels and the photodiode arrays wide used for non-destructive testing and medical imaging (spatial resolution 20 - 400 mkm). By our estimations, using of such detectors in combination with thin film of ZnSe(Te) can increase efficiency of registration of x-ray radiation (for the source of 60-140kV) in 1,2 - 2 times. We obtained thin films (10-450mkm) of scintillator ZnSe(Te) on the different substrate materials and estimated the relative light yield of the layers deposited on the graphite and Al₂O₃ ceramic substrates and the bulk ZnSe(Te) crystal. Use of ZnSe(Te) in the low-energy "scintillator - photodiode" type detector allowed to increase accuracy of authentication of explosives (HEIMANN X-RAY INSPECTION SYSTEM EDtS10080). Using the dual energy digital radiography system prototype we obtained the x-ray images (60 projections of each object). These images are basic data for computer tomography and three-dimensional reconstruction of density and effective atomic number. The color identification palette provides clearly show variations of effective atomic number in biological and inorganic objects. So, for example, changes of calcium concentration in a bone. The research described in this publication was supported by STCU #4115 and NATO SfP-982823.

High-speed microchannel plate (MCP)-based imagers are critical detectors for x-ray diagnostics employed on Z-experiments at Sandia National Laboratories (SNL) to measure time-resolved x-ray spectra and to image dynamic hohlraums. A multiframe design using eight half strips in one imager permits recordings of radiation events in discrete temporal snapshots to yield a time-evolved movie. We present data using various facilities to characterize the performance of this design. These characterization studies include DC and pulsed-voltage biased measurements in both saturated and linear operational regimes using an intense, short-pulsed UV laser. Electrical probe measurements taken to characterize the shape of the HV pulse propagating across the strips help to corroborate the spatial gain dependence

CdZnTe (CZT) is the most promising semiconductor for room-temperature nuclear radiation detectors. At Brookhaven's National Synchrotron Light Source (NSLS), we used a highly collimated synchrotron X-ray radiation to map different CZT detectors. In this paper, the latest results from high spatial resolution X-ray mapping of CZT detectors are reported. Effects of different internal defects on the performance of CZT detectors are discussed.

Generally, mechanical polishing is performed to diminish the cutting damage followed by chemical etching to remove the remaining damage on crystal surfaces. In this paper, we detail the findings from our study of the effects of various chemical treatments on the roughness of crystal surfaces. We prepared several CdZnTe (CZT) and CdMnTe (CMT) crystals by mechanical polishing with 5 μm and/or lower grits of Al₂O₃ abrasive papers including final polishing with 0.05-μm particle size alumina powder and then etched them for different periods with a 2%, 5% Bromine-Methanol (B-M) solution, and also with an E-solution (HNO₃:H₂0:K₂Cr₂O₇). The material removal rate (etching rate) from the crystals was found to be 10 μm, 30 μm, and 15 μm per minute, respectively. The roughness of the resulting surfaces was determined by the Atomic Force Microscopy (AFM) to identify the most efficient surface processing method by combining mechanical and chemical polishing.

The RENA-3 (R Readout E eadout Electronics for N lectronics Nuclear A uclear Applications) is a multi-channel mixed-signal integrated circuit (IC) developed for the readout of position-sensitive solid-state detectors with excellent energy resolution. We will present results of experiments characterizing its performance as used with a variety of spectroscopy-grade detectors currently available in the industry, notably CZT pixel arrays as well as other detector configurations. The merits of specific RENA-3 design features vis-à-vis different detector applications will also be discussed.

Molecular compounds used as potential experimental models for contaminant inclusions in cadmium zinc telluride (CZT) are discussed. The compounds include those that have been previously directly observed or postulated in previous research studies of CZT and ones that have not yet been observed or studied in either CZT melts or large crystals. Several experimental techniques that are effective for direct interrogation of impurities in solid materials such as CZT are discussed.