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Showing papers in "IEEE Transactions on Nuclear Science in 1977"


Journal ArticleDOI
TL;DR: THREDE as mentioned in this paper is a time-domain, linear, finite-difference, three-dimensional EMP coupling and scattering code, which can accomodate a problem space consisting of a 30×30×30 mesh.
Abstract: THREDE is a time-domain, linear, finite-difference, three-dimensional EMP coupling and scattering code. In its present form, it can accomodate a problem space consisting of a 30×30×30 mesh. Differencing is linear. Problem-space boundaries are provided with a radiating condition which does not generate ficticious mathematical echos at late times. The scatterer must be a perfect conductor, although a nonideal ground plane (runway) may be close by. The present article describes the mathematical basis of THREDE, and shows the results of applying it to predict the response of an F-111 shell in the horizontally-polarized dipole (HPD) EMP simulator. Amplitude agreement between experiment and prediction for this example is typically on the order of 20%; resonant frequencies are predicted more closely than this. THREDE costs about 1 second of CDC 7600 computer time per program cycle; most practical analyses require 500 to 1000 program cycles.

167 citations


Journal ArticleDOI
TL;DR: In this paper, the field and temperature dependence of the interface state density as a function of time following pulsed e-beam irradiation, and the dose dependence of interface-state density following steady state Co60 irradiation were examined in MOS capacitors with both hardened dry and wet gate oxides.
Abstract: The field and temperature dependence of the interface-state density as a function of time following pulsed e-beam irradiation, and the dose dependence of the interface-state density following steady state Co60 irradiation were examined in MOS capacitors with both hardened dry and wet (pyrogenic) gate oxides. From the results of the pulsed e-beam experiment, we show that in the wet oxide the electric field affects the time scale for the buildup of interface states as well as the final or saturation value of interface states at late times (~105 s), but that in the dry oxide there is no marked field dependence. For the wet oxide, we observed that temperature affects only the time scale for the buildup of interface states. From total-dose Co60 measurements, we report a power law dependence on dose, D0.65, for both wet and dry oxide capacitors. The buildup of interface states in the wet-oxide capacitors is considerably larger than in the dry.

132 citations


Journal ArticleDOI
J. M. Aitken1, D. R. Young1
TL;DR: Avalanche injection techniques are used to provide hole currents through MOS capacitors and study the trapping of holes in the oxide layer as mentioned in this paper, which indicate a strong similarity between hole trapping induced by avalanche injection and by radiation.
Abstract: Avalanche injection techniques are used to provide hole currents through MOS capacitors and study the trapping of holes in the oxide layer. Although radiation is not in any way involved in these experiments, the trapped positive charge and surface states resulting from hole injection are similar to those obtained using radiation. The processing and oxide thickness dependence of hole trapping phenomena are also investigated. Prolonged post-oxidation annealing treatments are shown to lead to enhanced hole trapping in "hardened" oxides. Hole trapping cross-sections between 10-13 and 10-14 cm2 and trap densities between 1012 - 1013 cm-2 are measured depending on the processing conditions. The effective charge density is studied over the range of oxide thickness between 200 A and 600 A as a function of post-oxidation anneal in these "hardened" oxides. While the effective charge density is only weakly dependent on oxide thickness in unannealed oxides, in annealed oxides it exhibits a strong linear dependence of trapping on oxide thickness. The dependence on post-oxidation anneal time and ambient are also discussed. These results indicate a strong similarity between hole trapping induced by avalanche injection and by radiation.

101 citations


Journal ArticleDOI
TL;DR: In this paper, all potential compounds which can be formed by the binary combination of elements from the periodic chart were considered as possible detector materials and a rank-ordered list of the most promising materials for further development was given as well as an assessment of the prospects for future success.
Abstract: It has been hoped that high-Z semiconductors would offer efficient ?-ray detection at or near ambient temperatures with energy resolution significantly better than NaI (T1) scintillators. For use at X-ray energies, this goal has been achieved with both HgI2, CdTe, and GaAs detectors. However, at higher energies (~660 keV) all current detectors have one or more significant deficiencies in terms of attainable volume, charge collection efficiency, and polarization effects. Starting with first principles, all potential compounds which can be formed by the binary combination of elements from the periodic chart were considered as possible detector materials. A rank-ordered listing of the most promising materials for further development is given as well as an assessment of the prospects for future success.

90 citations


Journal ArticleDOI
TL;DR: Measurements of imaging and background rates under various operating conditions are presented and it is shown that 1.5 million events are sufficient to reliably image 3.5 mm hot spots with 14 mm center-to-center spacing and isolated 9 mm diameter cold spots in phantoms 15-20 cm in diameter.
Abstract: High resolution computed transaxial tomography has been performed on phantoms containing positron-emitting isotopes. The imaging system consisted of two opposing groups of eight NaI(T1) crystals 8 mm × 30 mm × 50 mm deep and the phantoms were rotated to measure coincident events along 8960 projection integrals as they would be measured by a 280 crystal ring system now under construction. The spatial resolution in the reconstructed images is 7.5 mm FWHM at the center of the ring and approximately 11 mm FWHM at a radius of 10 cm. We present measurements of imaging and background rates under various operating conditions. Based on these measurements, the full 280 crystal system will image 10,000 events per sec with 400 ?Ci in a section 1 cm thick and 20 cm in diameter. We show that 1.5 million events are sufficient to reliably image 3.5 mm hot spots with 14 mm center-to-center spacing and isolated 9 mm diameter cold spots in phantoms 15-20 cm in diameter.

84 citations


Journal ArticleDOI
TL;DR: In this article, it is suggested that hydrogen present in various forms in the oxide film plays a crucial and complex role in the irradiation behavior of Si/SiO2 interface structures.
Abstract: Similarly to vitreous silica, irradiation of Sio2 films on silicon releases bond strain by creating network defects and a small increase in density and a decrease in polarizability. In contrast, the density of quartz crystal decreases and its polarizability increases during irradiation. These effects are due to the basic trend of maximizing ?-bonding and minimizing bond strain in the Si-O network. From the irradiation-generated electron-hole pairs, the holes are trapped in narrow and localized ?-bands at ~0.4 eV above the SiO2 valence band while the electrons move rather freely. This hole trapping is an intrinsic property of the Si-O bond. Hole trapping also occurs at the Si/SiO2 interface where interface states are generated. It is suggested that this process involves breaking surface Si-H bonds. Results obtained with various analytical techniques demonstrate that hydrogen present in various forms in the oxide film plays a crucial and complex role in the irradiation behavior of Si/SiO2 interface structures.

83 citations


Journal ArticleDOI
F. Sacherer1
TL;DR: In this article, a single-bunch instability that leads to blow-up of bunch area and microwave signals (100 MHz to 3 GHz) has been observed in the pS1) and the ISR2).
Abstract: A single-bunch instability that leads to blow-up of bunch area and microwave signals (100 MHz to 3 GHz) has been observed in the pS1) and the ISR2). A similar instability may cause bunch lengthening in electron storage rings. Attempts to explain this as a high-frequency coasting-beam instability require e-folding rates faster than a synchrotron period, and wavelengths shorter than a bunch length. In this case, the usual Keil-Schnell coasting-beam criterion3) is used, but with local values of bunch current and momentum spread, as suggested by Boussard1). This yields |Z/n| ? 13 ? for the ISR, and values about five to ten times larger for the PS. The restricitons mentioned above, however, are not fulfilled near threshold, or for frequencies as low as 100 MHz.

82 citations


Journal ArticleDOI
TL;DR: In this article, it was shown that over a wide range of dose rates there is no true dose rate dependence and that the differences in radiation charging can be attributed to annealing effects.
Abstract: Exposure of MOS devices to different dose-rate ionizing radiation environments indicates an apparent dependence of radiation charging upon the dose rate. It is shown in this paper that over a wide range of dose rates there is no true dose rate dependence and that the differences in radiation charging can be attributed to annealing effects. It is shown that convolution integrals and linear system theory accurately predict charging behavior and that the impulse response of the system can accurately be predicted for very long times since the annealing phenomenon is temperature activated.

74 citations


Journal ArticleDOI
TL;DR: In this article, changes in silicon surface preparation prior to thermal oxidation are shown to leave a signature by altering the final SiO2/Si interface structure Surface analytical techniques, including XPS, static SIMS, ion milling, and newly developed wet-chemical profiling procedures are used to obtain detailed information on the chemical structure of the interface.
Abstract: Changes in silicon surface preparation prior to thermal oxidation are shown to leave a signature by altering the final SiO2/Si interface structure Surface analytical techniques, including XPS, static SIMS, ion milling, and newly developed wet-chemical profiling procedures are used to obtain detailed information on the chemical structure of the interface The oxides are shown to be essentially SiO2 down to a narrow transitional interface layer (3-7 A) A number of discrete chemical species are observed in this interface layer, including different silicon bonds (eg, C-, OH-, H-) and a range of oxidation states of silicon (0 ? +4) The effect of surface preparation and the observed chemical species are correlated with oxide growth rate, surface-state density, and flatband shifts after irradiation

70 citations


Journal ArticleDOI
TL;DR: In this paper, it was shown that high-purity Ge low-energy X-ray detectors have a relatively thick entrance window which renders them practically useless below 2.3 KeV.
Abstract: We have found experimentally that high-purity Ge low-energy X-ray detectors have a relatively thick entrance window which renders them practically useless below ~ 2.3 KeV. A simple X-ray fluorescence experiment establishes clearly that the window is physically in the Ge material itself. Experiments with detectors made from different Ge crystals, and with Schottky barrier contacts of different metals indicate that the effect is due to a basic property of the transport of electrons near a surface. Theoretical considerations and a Monte Carlo calculation show that the window is caused by the escape of warm electrons which are the end product of a photo event. The mean free path of the electrons becomes longer as they lose energy by optical phonon collisions and they can be trapped at the surface before they are picked up by the electric field.

65 citations


Journal ArticleDOI
TL;DR: In this article, the number of photons produced by a single electron travelling the unit of distance, divided by the gas pressure, depends only on the reduced electric field but not on the hydrogen pressure, and an empirical equation for this quantity is given.
Abstract: Data an the xenon uniform field gas proportional scintillation counter is presented. The energy resolution obtained for 8.1 MeV ?-particles was 1.2%. Measurements for pressures from 600 to 1500 Torr showed that the "reduced light output", i. e. the number of photons produced by a single electron travelling the unit of distance, divided by the gas pressure, depends only on the reduced electric field but not on the gas pressure. An empirical equation for this quantity is given. The role played by different mechanisms is discussed.

Journal ArticleDOI
TL;DR: In this paper, the loss rate of the active material from the catalysts under vehicle operating conditions was determined with a radiometric method in which radioactive platinum and palladium were used as tracers.
Abstract: Automotive exhaust gas catalysts contain platinum and palladium as the active material on an alumina substrate. The loss rate of the active material from the catalyst under vehicle operating conditions was determined with a radiometric method in which radioactive platinum and palladium were used as tracers. Experiments with a commercial catalyst made radioactive by irradiation in a nuclear reactor indicated that a maximum of about 6 percent of the active material would be lost from the catalyst in 80,000 km. Experiments with a laboratory prepared catalyst containing 195mPt and 103Pd indicated that about 10 percent of the active material lost was water soluble, possibly in the form of halides.

Journal ArticleDOI
Flemming Pedersen1, F. Sacherer1
TL;DR: In this article, the amplitude-phase response (RF knockout applied to a bunched beam) and frequency spread within the bunch, coherent frequent shifts, plus the usual stability diagram in the U-V plane are shown.
Abstract: Longitudinal instabilities have long been trouble-some in the Booster1). They are described by the coupledbunch mode number n = 0 to 4 for five bunches, and by the within-bunch mode number m = 1 for dipole, m = 2 for quadrupole, m = 3 for sextupole, and so on (Fig. 1). The normal beam control system damps the rigid-bunch oscillation (m = 1) when all five bunches move togethier (n = 0)2). The new feedback system3) damps the other coupled-bunch modes n = 1 to 4 for the three lowest orders, m = l to 3. With the damping system off, one can display the evolution of any mode along the cycle, which helps in locating coupling impedances that cause instability. One can also excite the various modes and measure the amplitude-phase response (RF knockout applied to a bunched beam). This gives the frequency spread within the bunch, the coherent frequent shifts, plus the usual stability diagram in the U-V plane.

Journal ArticleDOI
TL;DR: In this paper, the joint probability density function of the projections was used to derive the reconstruction scheme which is optimum in the maximum likelihood sense, and it was shown that for an average number of counts detected in excess of approximately 100 per projection, the image is essentially unbiased.
Abstract: The stochastic nature of the projections used in transmission image reconstruction has received little attention to date. This paper utilizes the joint probability density function of the projections to derive the reconstruction scheme which is optimum in the maximum likelihood sense. Two regimes are examined: that where there is significant probability of a zero count projection, and that where the zero count event may be safely ignored. The former regime leads to a complicated algorithm whose performance is data dependent. The latter regime leads to a simpler algorithm. Its performance, in terms of its bias and variance, has been calculated. It is shown that, for an average number of counts detected in excess of approximately 100 per projection, the image is essentially unbiased, and for counts in excess of approximately 2500 per projection, the image approximately attains the minimum variance of any reconstruction scheme using the same measurements.

Journal ArticleDOI
TL;DR: PbI2 detectors fabricated starting from samples either grown from the melt by the Bridgman method either from the vapour by the iodine assisted chemical transport method, have been tested for nuclear applications and compared each other in this respect as discussed by the authors.
Abstract: PbI2 detectors fabricated starting from samples either grown from the melt by the Bridgman method either from the vapour by the iodine assisted chemical transport method, have been tested for nuclear applications and compared each other in this respect. Values of (mobility) × (trapping times) product, ??+, measured both for electrons and holes turn out to be one or two orders of magnitude larger than reported previously and they are better for vapour-grown samples than for melt-grown ones. Moreover, dark currents seem to be one or two orders of magnitude lower for samples grown from the vapour-phase. The indication is obviously that, at least at this early stages, the growth by the chemical transport seems to be superior to the Bridgman method for obtaining detector quality crystals. Finally, the main features of this material as nuclear detector are discussed.

Journal ArticleDOI
TL;DR: In this article, a generalization of Ramachandran and Lakshminarayanan's |ω|-filter has been proposed for 3D reconstruction of a density function, based on a direct convolution algorithm.
Abstract: The 3-D reconstruction of a density function is based on a direct convolution algorithm developed first by Ramachandran and Lakshiminarayanan. Their method adopts a particular choice of weighting function or filter which is called here an |ω|-filter. In some cases this choice of filter had an undesirable oscillatory response. To remedy this problem Shepp and Logan found a weighting function which produced a better reconstruction of a head section. The filter functions of Ramachandran and Lakshminarayanan and Shepp and Logan are only two of many choices for an |ω|-filter. Shepp and Logan's filter was the best for the early tomographic machines. Their filter function provided both a damped response to the cut-off frequency and a low sensitivity to noise. For the new tomographic machines, however, it is desirable to find filters that are not sensitive to counting noise, sample size and sample spacing as the previous filters. Here a study and generalization is made of the previous |ω|-filters. It extends the important filters of Ramachandran and Lakshiminarayanan, and Shepp and Logan to a class of generalized |ω|-filters. A generalized |ω|-filter can be chosen to have both good accuracy and a flexibility to cope with noise. A detailed comparison is made among the different possible filter shapes with respect to their responses to simulated data and noise. Finally in this paper it is demonstrated that a substantial reduction in the x-ray exposure time can be accomplished by choosing the appropriate generalized |ω|-filter.

Journal ArticleDOI
TL;DR: In this article, the influence of native defects in detector grade mercuric iodide crystals has been investigated by doping with either mercury or iodine, and the results are discussed in terms of different trapping mechanisms.
Abstract: The influence of native defects in detector grade mercuric iodide crystals has been investigated by doping with either mercury or iodine. Measurements have been made of mobility-lifetime products and of thermally stimulated conductivity in undoped, Hg doped, and I2 doped crystals. The results are discussed in terms of different trapping mechanisms.

Journal ArticleDOI
TL;DR: In this article, the authors proved that the luminosity of the storage ring DORIS is limited by betatron-synchrotron resonances which are produced by the beam-beam interaction.
Abstract: Experimental and theoretical investigations have shown that the luminosity of the storage ring DORIS is limited by betatron-synchrotron resonances which are produced by the beam-beam interaction. The resonance frequencies are given by Qsa=(p+rQs)/q, where p, q, r are integers and Qs and Qs are the betatron and synchrotron wave numbers, respectively. It is proved that these resonances are caused by the crossing angle. Analytical investigations as well as computer simultionsare in good agreement with measurements made at DORIS. The analytical investigation further shows that also a dispersion at the interaction point will produce these satellite resonances.

Journal ArticleDOI
TL;DR: Some characteristics of diamond detectors have been investigated with a view to finding out the possibilities of their application for X-ray and δ-radiation dosimetry in medical radiology and a tissue-equivalent diamond dosimeter is shown.
Abstract: Some characteristics of diamond detectors have been investigated with a view to finding out the possibilities of their application for X-ray and δ-radiation dosimetry in medical radiology. The results of this investigation are described. The design of a tissue-equivalent diamond dosimeter is shown. It possesses a uniform energy dependence and threshold sensitivity of lμR/s to the dose rate.

Journal ArticleDOI
TL;DR: In this article, anomalous bunch lengthening and energy spread, the spectroscopy of longitudinal modes and the shift of synchronous phase were simultaneously measured in order to study the dynamics of the interaction.
Abstract: In recent years, electron storage ring designers have become aware of the problems caused by the interaction of short, high current bunches with their environment. Important effects are: (1) energy loss can cause local overheating of chamber components; (2) additional rf power is required due to overall energy loss; (3) the increased energy spread requires increased aperture; (4) destructive instabilities could occur. Anomalous bunch lengthening and energy spread, the spectroscopy of longitudinal modes and the shift of synchronous phase were simultaneously measured in order to study the dynamics of the interaction. From the data obtained at SPEAR II one is led to a model of coupling impedance which should be useful in the design of any electron ring.

Journal ArticleDOI
TL;DR: The NASCAP (NASA Charging Analyzer Program) as mentioned in this paper was developed by Systems, Science and Software under contract to NASA-LeRC to simulate the charging of a complex spacecraft in geosynchronous orbit.
Abstract: A computer code, NASCAP (NASA Charging Analyzer Program), has been developed by Systems, Science and Software under contract to NASA-LeRC to simulate the charging of a complex spacecraft in geosynchronous orbit. The capabilities of the NASCAP code include a fully three-dimensional solution of Poisson's equation about an object having considerable geometrical and material complexity, particle tracking, shadowing in sunlight, calculation of secondary emission, backscatter and photoemission, and graphical output. A model calculation shows how the NASCAP code may be used to improve our understanding of the spacecraft-plasma interaction.

Journal ArticleDOI
TL;DR: Transverse axial positron annihilation coincidence detection tomography with a stationary circular ring posi tron camera system is described in this paper, where a prototype constructed with 64 NaI(T1) crystal system has the capability of recording 736 - 1312 simultaneous coincidence pairs and is able to perform certain dynamic function studies.
Abstract: Transverse axial positron annihilation coincidence detection tomography with a stationary circular ring posi tron camera system is described. A prototype constructed with 64 NaI(T1) crystal system has the capability of recording 736 - 1312 simultaneous coincidence pairs and is able to perform certain dynamic function studies.

Journal ArticleDOI
TL;DR: In this paper, it was found that simple thermally evaporated amorphous Ge made fairly good electron or hole blocking contacts on high-purity germanium, and a number of spectrometers have been made with Amorphous geysers replacing the n+ contact.
Abstract: Experiments were performed in an attempt to make thin n+ contacts on high-purity germanium by the solid phase1 epitaxial regrowth of arsenic doped amorphous germanium. After cleaning the crystal surface with argon sputtering and trying many combinations of layers, it was not found possible to induce recrystallization below 673K. However, it was found that simple thermally evaporated amorphous Ge made fairly good electron or hole blocking contacts. Excellent spectrometers have been made with amorphous Ge replacing the n+ contact. As presently produced, the amorphous Ge contact diodes show a large variation in high-voltage leakage current.

Journal ArticleDOI
TL;DR: In this article, the Cerenkov process was shown to occur in low-loss optical waveguides in severe radiation environments, and the spectral data and angular dependence of luminescence were used to verify the effect of radiation on optical fiber properties.
Abstract: Radiation-induced effects in low loss optical waveguides have been studied to determine parameters affecting the use of these materials in plasma diagnostic instrumentation operating in severe radiation environments. Radiation-induced luminescence of fibers was shown to result from the Cerenkov process occurring within the fibers. Both spectral data and angular dependence of luminescence were used to verify the Cerenkov effect. Absolute magnitude of luminescence data were obtained. Different fiber types were shown to exhibit comparable luminescence output. Radiation-induced absorption was measured immediately following a 40 ns radiation pulse at wavelengths of 600 nm and 800 nm. Saturation effects in absorption were observed as well as changes in fiber recovery vs time as a function of radiation dose. Step- and graded-index profile fibers were shown to exhibit comparable absorption. Fibers tested included plastic clad silica fibers, as well as graded- and step-index germanium-doped and boron-doped fibers. Plastic clad silica fibers exhibited much less radiation-induced absorption than any other fiber type. The data presented allow optical fiber data links to be designed for use in severe radiation environments where data transmission is required during, or shortly after, the radiation pulse.

Journal ArticleDOI
TL;DR: In this paper, the applied field dependence of flatband voltage shift in MOS capacitors irradiated at 77°K can be accounted for in terms of the field dependent of electron yield and the transport of holes at high fields.
Abstract: Charge buildup in irradiated MOS devices is significantly more severe at low temperatures than at room temperature. Approaches for counteracting this problem are considered in this paper, including: (1) careful selection of the applied field; (2) ion implantation of the oxide; (3) use of a thin oxide. Experimental and analytical results are presented and it is demonstrated that the applied field dependence of flatband voltage shift in MOS capacitors irradiated at 77°K can be accounted for in terms of the field dependence of electron yield and the transport of holes at high fields. Analysis of ion implantation effects indicates that a significant improvement in radiation tolerance should be achievable by this method. A simultaneous consideration of the effects of oxide thickness and applied field on charge buildup in an unimplanted oxide suggests that reducing the thickness to ?500 A° will largely eliminate low temperature problems in a steady-state ionizing radiation environment as long as the applied voltage is ? 10V.

Journal ArticleDOI
TL;DR: In this article, transition zone dosimetry and secondary electron transport data are incorporated in a new methodology which includes space charge effects and time dependent replacement currents, and results of experiments on several organic polymers irradiated by 60Co photons are presented.
Abstract: Methods for measuring induced conductivity due to high energy (> 10 keV) irradiation in dielectrics are discussed. Transition zone dosimetry and secondary electron transport data are incorporated in a new methodology which includes space charge effects and time dependent replacement currents. In addition, a radically different method for the measurement of radiation induced conductivity which takes advantage of space charge fields is proposed which should be advantageous for in-situ measurements. Results of experiments using both methods on several organic polymers irradiated by 60Co photons are presented. Time dependent replacement current is measured and compared to theoretical prediction. Experimentally measured replacement current is in agreement with calculations based on published theoretical photocompton current data for field free conditions. An equation for estimating the maximum space charge field generated by high energy photons or electrons is proposed.

Journal ArticleDOI
TL;DR: In this paper, a pair of ring cores are used to provide flux rate feedback to a power amplifier which drives the ampere-turn compensating current through a common compensating winding, and a specially developed burden resistor converts the compensating currents into a voltage signal, which is amplified to give a 10 V output signal at the nominal value of the current to be measured.
Abstract: A current-carrying conductor is surrounded by a pair of ring cores. A sense winding on one core provides flux rate feedback to a power amplifier which drives the ampere-turn compensating current through a common compensating winding. The other core serves as a second-harmonic modulator to establish zero-flux operation and thus to ensure a perfect, temperature-independent current balance. A specially-developed burden resistor converts the compensating current into a voltage signal, which is amplified to give a 10 V output signal at the nominal value of the current to be measured. A substantial number of devices, ranging from 50 to 25000 Amperes is now operational in the beam transfer and extraction power supplies for the CERN SPS.

Journal ArticleDOI
C. Kerns1
TL;DR: In this article, a photomultiplier tube base designed to minimize voltage changes at the phototube's dynodes under high-rate conditions is described, making use of emitter follower characteristics of high beta, high voltage, video transistors.
Abstract: A photomultiplier tube base designed to minimize voltage changes at the phototube's dynodes under high-rate conditions is described. Over 200 of these phototube bases are presently used on lead glass and other calorimeter phototubes in high energy physics experiments. Stiff voltage sources for dynodes are provided by making use of emitter follower characteristics of high beta, high voltage, video transistors.

Journal ArticleDOI
TL;DR: In this paper, three distinct trap levels are observed at (Ec-Et) equals 0.14, 0.23, and 0.41 eV, respectively, and the dispersion in the time vs. emission curves leads to apparent widths of 0.08 and 0.10 eV of the energy levels.
Abstract: Electron traps created by high energy (~15 MeV) neutron irradiation at 300°K have been characterized by the double pulse technique in an n-buried-channel CCD. Measurements have been made of electron emission from the traps as a function of time from 77°K to 300°K. Three distinct trap levels are observed at (Ec-Et) equals 0.14, 0.23, and 0.41 eV. Electron emission from the traps as a function of time does not follow the expected exponential time behavior. Analysis of the dispersion in the time vs. emission curves leads to apparent widths of 0.08 and 0.10 eV of the energy levels at Ec - 0.14 and Ec - 0.41 eV, respectively. Introduction rates of the levels and possible physical defects which create the levels are also discussed.

Journal ArticleDOI
TL;DR: In this paper, the possibility of using AlSb as a potential material for high-energy photon detection is examined by comparing the mobilities of the free carriers, the energy gap, the atomic number, and the carrier recombination time.
Abstract: The possibility of using AlSb as a potential material for high-energy photon detection is examined by comparing the mobilities of the free carriers, the energy gap, the atomic number, and the carrier recombination time for AlSb, CdTe, Si, and Ge. It is concluded that at room temperature AlSb should be an intrinsically better high-energy photon detector than the three other materials. Simulated detector spectra for AlSb and CdTe are compared for ambient temperature detector performance.