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Nuclear Science, IEEE Transactions on

Issue 5  Part 3 • Date Oct. 2010

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Displaying Results 1 - 25 of 30
  • Table of contents

    Page(s): C1 - 2782
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  • IEEE Transactions on Nuclear Science publication information

    Page(s): C2
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  • Suppression of Beam Loss at the First Arc Section in the J-PARC Linac

    Page(s): 2783 - 2789
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1124 KB) |  | HTML iconHTML  

    J-PARC (Japan Proton Accelerator Research Complex) linac has recently started its continuous operation to provide a 181-MeV H- beam to the downstream 3-GeV synchrotron and a neutron target. Immediately after the commencement of the continuous operation, significant residual radiation and beam loss were observed at the first bending magnet in the first arc section. The measured radiation and beam loss were localized in the side opposite to the deflection of the H- beam. A possible beam loss source is the H+ produced by double electron-stripping of H- in a residual gas scattering at the front end part of the linac. To confirm this supposition, an H+ signal was measured with a wire scanner monitor at the beam energy of 3 MeV by separating H+ from the H- beam with horizontal dipole magnets. Then the separated H+ is successfully removed by a beam scraper originally for beam chopping. With this H+ suppression, the beam loss at the first bend was suppressed by factor of 24-31 without sacrificing the beam chopping performance. Consequently, the residual radiations were reduced to a comfortable level for the continuous operation. View full abstract»

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  • The SYNC Chip in the Electronics Architecture of the LHCb Muon Detector

    Page(s): 2790 - 2797
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    We present a custom integrated circuit, named SYNC, which plays a fundamental role in the time alignment of the LHCb Muon Detector and consequently in the trigger performance. The SYNC is realized in IBM 0.25 μm technology, using radiation-hardening layout techniques. SYNC receives data from the muon detector front-end electronics synchronizing them with the 40.08 MHz LHC clock. The data are tagged with the correct Bunch-Crossing identifier, output to the trigger system and stored in internal memories. The chip integrates 8 time to digital converters with a resolution up to 1 ns to measure the time phase of the input signals with respect to the system clock period. A histogram block can build real time spectra from the TDCs output. A I2C interface is implemented to configure and control the device, while a JTAG interface is integrated for boundary-scan purpose. We describe the circuit architecture, its internal blocks and its main modes of operation. Measurements performed on final prototypes are also reported. View full abstract»

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  • A Power Efficient 12-bit and 25-MS/s Pipelined ADC for the ILC/Ecal Integrated Readout

    Page(s): 2798 - 2804
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    The design of full integrated electronics readout for the future ILC ECAL presents many challenges. Low power dissipation is required, and it will be necessary to integrate the very front-end stages with an analog to digital converter. We present here a 12 bit 25 MHz analog to digital converter using a pipelined architecture. It is composed of ten 1.5 bit sub-ADCs along with a final 2 bit flash converter. A CMOS 0.35 μm process is used. The dynamic range is 2 V over a 3.3 V power supply and the total power dissipation is 37 mW. The analog part of the converter can be switched to a standby mode in only a couple of μs. This power management helps to reduce the DC power dissipation by three orders of magnitude. Therefore by switching the DC bias following the beam cycle time (1% of duty cycle), an average power consumption of only 0.2 μW is measured. The converter prototype occupies an active die area of 1.7 mm *0.6 mm. View full abstract»

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  • Physics-Related Epistemic Uncertainties in Proton Depth Dose Simulation

    Page(s): 2805 - 2830
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1186 KB) |  | HTML iconHTML  

    A set of physics models and parameters pertaining to the simulation of proton energy deposition in matter are evaluated in the energy range up to approximately 65 MeV, based on their implementations in the Geant4 toolkit. The analysis assesses several features of the models and the impact of their associated epistemic uncertainties, i.e., uncertainties due to lack of knowledge, on the simulation results. Possible systematic effects deriving from uncertainties of this kind are highlighted; their relevance in relation to the application environment and different experimental requirements are discussed, with emphasis on the simulation of radiotherapy set-ups. By documenting quantitatively the features of a wide set of simulation models and the related intrinsic uncertainties affecting the simulation results, this analysis provides guidance regarding the use of the concerned simulation tools in experimental applications; it also provides indications for further experimental measurements addressing the sources of such uncertainties. View full abstract»

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  • Smoothing Low Resolution Gamma Spectra

    Page(s): 2831 - 2840
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    The energy spectra of gamma-rays emitted by radioisotopes act as finger prints that enable identification of the source. Such identification from low-resolution NaI detectors over short time periods is challenging for several reasons, including the Poisson fluctuations in the recorded counts. Smoothing the data over neighboring energy bins can reduce the noise in the raw counts, at the cost of introducing a bias that de-emphasizes the peaks and valleys of a spectrum. This paper describes a new two-stage smoothing procedure that uses a multiplicative bias correction (MBC) for adjusting initial smoothed spectra. Applying the MBC to an initial smoother reduces bias of the initial smoother in the peaks and valleys with no or negligible increase in its variance. We illustrate the benefit of this new method on example real and simulated spectra. View full abstract»

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  • Tertiary Scintillation Gas Proportional Scintillation Counter (TS-GPSC): First Experimental Results$^{ast}$

    Page(s): 2841 - 2847
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (909 KB) |  | HTML iconHTML  

    A new concept for a gaseous radiation detector is presented: the Tertiary Scintillation Gas Proportional Scintillation Counter (TS-GPSC). In this detector the electric field induced secondary scintillation is first detected by a CsI-coated GEM-like structure where it releases photoelectrons which are transferred through the GEM holes, with no charge multiplication, to another region where further field induced scintillation (tertiary) is produced and then again detected on a planar CsI-coated photocathode at the backplane of the detector. The electrons released therein are collected at a grid and constitute the detector's signal. Since there is no avalanche charge multiplication in the detector, the gain will be quite stable and, moreover, as the field induced scintillation yield is very high, and in spite of the low photocathode quantum efficiency, the gain will be high and with low fluctuations, so an improvement in the energy resolution as compared to other types of Gas Proportional Scintillation Counters is expected. The first prototype of the tertiary scintillation detector was tested in a xenon atmosphere for hard X-rays and experimental results are presented. Energy resolutions of 8.2% were achieved for 22.1 keV X-rays. View full abstract»

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  • Performance of the Low-Jitter High-Gain/Bandwidth Front-End Electronics of the HADES tRPC Wall

    Page(s): 2848 - 2856
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1943 KB) |  | HTML iconHTML  

    A front-end electronics (FEE) chain for accurate time measurements has been developed for the new Resistive Plate Chamber (RPC)-based Time-of-Flight (TOF) wall of the High Acceptance Di-Electron Spectrometer (HADES). The wall covers an area of around 8 m2, divided in 6 sectors. In total, 1122 4-gap timing RPC cells are read-out by 2244 time and charge sensitive channels. The FEE chain consists of 2 custom-made boards: a 4-channel DaughterBOard (DBO) and a 32-channel MotherBOard (MBO). The DBO uses a fast 2 GHz amplifier feeding a dual high-speed discriminator. The time and charge information are encoded, respectively, in the leading edge and the width of an LVDS signal. Each MBO houses up to 8 DBOs providing them regulated voltage supply, threshold values via DACs, test signals and, additionally, routing out a signal proportional to the channel multiplicity needed for a 1st level trigger decision. The MBO delivers LVDS signals to a multi-purpose Trigger Readout Board (TRB) for data acquisition. The FEE allows achieving a system resolution around 75 ps fulfilling comfortably the requirements of the HADES upgrade . View full abstract»

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  • Comparison of Neutron Detection Efficiency of a He-3 Counter and a Boron-10 Loaded Liquid Scintillator

    Page(s): 2857 - 2861
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (738 KB) |  | HTML iconHTML  

    Performance of a He-3 counter and a B-10 loaded liquid scintillator EJ309B5 has been studied in terms of neutron detection efficiency. The measurements were carried out in a mixed field of neutron and gamma radiation from an intense ( ~ 106 neutrons/s/4π)252Cf source. The response of both detectors to background and high intensity gamma radiation ( ~ 100 μSv/h at a detector) from a 60Co source has been measured to establish background count rate and gamma rays cut-off point, respectively. The analysis showed that the properties of a He-3 counter are significantly better than that of EJ309B5. However, it has been pointed out how to improve the performance of a liquid scintillator in order to reduce gamma radiation sensitivity. View full abstract»

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  • Identification and Differentiation of Actinides Inside Nuclear Waste Packages by Measurement of Delayed Gammas

    Page(s): 2862 - 2871
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    Abstract-The Alpha-activity resulting from the presence of actinides inside nuclear waste packages must be characterized, in order to select the most appropriate means of storage. Non-destructive active methods, based on the fission process, allow the global mass of actinides to be quantified. However, in most cases, these measurements provide no information on the nature of the isotopes. We are currently developing a method dedicated to the identification of the actinides (235U, 238U, 239Pu) contained inside nuclear waste packages. This technique is based on the detection of delayed gammas emitted by fission products, the latter being created by irradiation with a neutron or photon beam. The delayed gamma spectrum can be thought of as a "fingerprint" of the irradiated sample. Qualitative and quantitative analysis of the peaks allows the actinides to be identified. In this paper, we firstly explain the theoretical principle of our method. We then present experimental results obtained on sample mixtures for both types of interrogation (236U/239Pu in fission, 235U/238U in photofission). Finally, we describe the experiments carried out on different mock-up packages, dedicated to the assessment of the performance and limitations of our technique. View full abstract»

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  • Applying Online Monitoring for Nuclear Power Plant Instrumentation and Control

    Page(s): 2872 - 2878
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (976 KB) |  | HTML iconHTML  

    This paper presents a practical review of the state-of-the-art means for applying OLM data acquisition in nuclear power plant instrumentation and control, qualifying or validating the OLM data, and then analyzing it for static and dynamic performance monitoring applications. Whereas data acquisition for static or steady-state OLM applications can require sample rates of anywhere from 1 to 10 seconds to 1 minutes per sample, for dynamic data acquisition, higher sampling frequencies are required (e.g., 100 to 1000 Hz) using a dedicated data acquisition system capable of providing isolation, anti-aliasing and removal of extraneous noise, and analog-to-digital (A/D) conversion. Qualifying the data for use with OLM algorithms can involve removing data `dead' spots (for static data) and calculating, examining, and trending amplitude probability density, variance, skewness, and kurtosis. For static OLM applications with redundant signals, trending and averaging qualification techniques are used, and for single or non-redundant signals physical and empirical modeling are used. Dynamic OLM analysis is performed in the frequency domain and/or time domain, and is based on the assumption that sensors' or transmitters' dynamic characteristics are linear and that the input noise signal (i.e., the process fluctuations) has proper spectral characteristics. View full abstract»

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  • Gamma-Ray Signatures Improvement of the EURITRACK Tagged Neutron Inspection System Database

    Page(s): 2879 - 2885
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (323 KB) |  | HTML iconHTML  

    The EURopean Illicit TRAfficking Countermeasures Kit (EURITRACK) inspection system uses 14 MeV neutrons produced by the D(T,n α) reaction to detect explosives in cargo containers. Reactions induced by fast neutrons inside the container produce gamma rays, which are detected in coincidence with the associated alpha particle, the detection of which allows the neutron direction to be determined. The neutron path length is obtained from a neutron time-of-flight measurement, thus allowing the origin of the gamma rays inside the container to be determined, while the chemical composition of the target material is correlated with their energy spectrum. Gamma-ray spectra have been collected with the inspection portal equipped with large volume NaI (Tl) detectors, in order to build a database of signatures for various elements (C, O, N, Fe, Pb, Al, Na, Si, Cl, Cu, Zn) with a low energy threshold of 0.6 MeV. The spectra are compared with previous ones, which were acquired with a 1.35 MeV threshold. The new library is currently being tested to unfold the energy spectra of transported goods into elemental contributions. Results are compared with data processed with the old 1.35 MeV threshold database, thus illustrating the improvement for material identification. View full abstract»

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  • Characterization of Scintillators by Modern Photomultipliers—A New Source of Errors

    Page(s): 2886 - 2896
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (396 KB) |  | HTML iconHTML  

    The observed discrepancy in the light output, measured for a number of LSO, LYSO and BGO scintillators by different photomultipliers (PMTs), triggered studies to understand the problem. For that purpose the photoelectron number was measured by two different methods: the direct one based on a comparison of the full energy peak to that of the single photoelectron and by a method based on the pulse height resolution of the peak due to the light pulser. In this study, a significant number of different PMTs from Photonis and Hamamatsu were used. We concluded that the number of photoelectrons measured by means of the direct method was higher than the number of photoelectrons calculated from the pulse height resolution of the light pulser peak for all of the PMTs but XP2020Q. It leads to a large dispersion in the estimated light output for a given scintillator. In detail, the light output of BGO and LSO determined with the R6231 and R2059 PMTs is comparable to those measured with XP2020Q PMT and the S3590-18 pin photodiode, when photoelectron number is calculated from the pulse height resolution. Further in-depth studies of the photoelectron number at different bias voltages suggested that the effect is related to the space charge created in the dynode structure of the PMTs. Operation of PMTs at lower bias/gain minimizes this effect; thus, low noise electronics are recommended to determine the single photoelectron peak under these conditions. Moreover, the absolute light output of scintillators is affected by differences in the quantum efficiency calibrations by Photonis and Hamamatsu. View full abstract»

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  • Design, Simulation, Fabrication, and Preliminary Tests of 3D CMS Pixel Detectors for the Super-LHC

    Page(s): 2897 - 2905
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1071 KB) |  | HTML iconHTML  

    The Super-LHC upgrade puts strong demands on the radiation hardness of the innermost tracking detectors of the CMS, which cannot be fulfilled with any conventional planar detector design. The so-called 3D detector architectures, which feature columnar electrodes passing through the substrate thickness, are under investigation as a potential solution for the closest operation points to the beams, where the radiation fluence is estimated to reach 1016 neq/cm2. Two different 3D detector designs with CMS pixel readout electronics are being developed and evaluated for their advantages and drawbacks. The fabrication of full-3D active edge CMS pixel devices with p-type substrate has been successfully completed at SINTEF. In this paper, we study the expected post-irradiation behaviors of these devices with simulations and, after a brief description of their fabrication, we report the first leakage current measurement results as performed on wafer. View full abstract»

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  • Carrier-Removal Comparison (n/p) and Functional Testing of Si and SiC Power Diodes

    Page(s): 2906 - 2914
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (863 KB) |  | HTML iconHTML  

    Commercial Si and 4H-SiC Schottky barrier power diodes were irradiated in the mixed neutron and gamma-ray radiation field of The Ohio State University research reactor (OSURR). The forward I-V characteristics were measured before and immediately after each successive irradiation, and the carrier-removal rates were compared, on the basis of NIEL, to a previous study, for which the same diode models were irradiated with a 203 MeV proton beam. In addition, a number of SiC Schottky barrier diodes were also irradiated in the OSURR and subsequently functionally tested in half-wave rectifier circuits, for which the voltage and current waveforms in the circuit were recorded. The results from the functional testing of these half-wave rectifier circuits were analyzed using results from I-V characterization, PSpice simulations, and an analytical formulation. View full abstract»

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  • High Radiation Sensitivity of Chiral Long Period Gratings

    Page(s): 2915 - 2922
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    The radiation sensitivity of chiral long period gratings was investigated for the first time. After a Co-60 gamma dose of 100 kGy they show radiation-induced changes of their transmission dip wavelength of up to 10 nm, which is 100 to 1000 times higher than the radiation-induced wavelength shift of different fiber Bragg grating types. They can therefore be used as radiation sensors down to doses of 10 Gy or even below, but not for accurate dose measurements since the size of the wavelength shift after a certain dose still depends on the radiation dose rate. Chiral gratings made of eight single mode fiber types with differences of their radiation-induced attenuation of several orders of magnitude were investigated in order to look for a correlation between dip wavelength shift and fiber attenuation. However, the dip wavelength curves do not show exactly the same order as the fiber attenuation curves. A theory that can exactly predict all properties of the chiral gratings might enable us to specify from our results an optimized fiber for the production of gratings that can also be used for radiation dosimetry. View full abstract»

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  • An Approach to Single Event Testing of SDRAMs

    Page(s): 2923 - 2928
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (866 KB) |  | HTML iconHTML  

    A unique testing approach based on error-pattern identification with a graphical mapping and color-coding of the full SDRAM memory during single-event characterization is proposed. Results about unique SEFI modes and the role of temperature are discussed. View full abstract»

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  • Optical Absorption of Proton Irradiated Colloidal CdSe/ZnS Core/Shell Nanocrystals

    Page(s): 2929 - 2932
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (677 KB) |  | HTML iconHTML  

    The excitonic transition observed in the optical absorption spectra of CdSe/ZnS core/shell nanocrystals is investigated as a function of 2 MeV proton irradiation dose. Samples of three different nanocrystal diameters were prepared by embedding the nanocrystals into a UV curable resin. The integrated area of the exciton peak is obtained after irradiating the samples with several irradiation fluences ranging between 1.0×1013 cm-2 to 9.5×1015 cm-2. The results indicate that nanocrystals with larger diameter (~4.40 nm) are more irradiation tolerant while the excitonic transition is completely degraded in nanocrystals with diameter of ~2.10 nm. View full abstract»

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  • A Generalized Linear Model for Single Event Transient Propagation in Phase-Locked Loops

    Page(s): 2933 - 2947
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1252 KB) |  | HTML iconHTML  

    A first-order linear model is formulated in closed-form for the examination of transient propagation through charge pump phase-locked loops (PLL). As a result, a novel PLL design parameter-the PLL critical time constant-is discovered as the primary factor influencing extraneous transient generation and propagation through the PLL independent of technology node. Various simulations and experiments have been performed on PLL circuits designed in 130 nm and 90 nm technology nodes. Using the described simulation and laser two-photon absorption (TPA) techniques, the generalized model is shown to accurately predict the output phase displacements and critical time constant of the PLL following transient perturbations, validating the analytical results independent of technology and without the need for calibration parameters. Moreover, the characteristic critical time constant is shown to be valuable for identifying and evaluating the single-event vulnerabilities in charge pump PLL designs. View full abstract»

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  • Heavy Ion Testing With Iron at 1 GeV/amu

    Page(s): 2948 - 2954
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (602 KB) |  | HTML iconHTML  

    A 1 GeV/amu 56Fe ion beam allows for true 90° tilt irradiations of various microelectronic components and reveals relevant upset trends at the GCR flux energy peak. Three SRAMs and an SRAM-based FPGA evaluated at the NASA Space Radiation Effects Laboratory demonstrate that a 90° tilt irradiation yields a unique device response. These tilt angle effects need to be screened for, and if found, pursued with radiation transport simulations to quantify their impact on event rate calculations. View full abstract»

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  • High Resolution Stroboscopic Neutron Radiography at the FRM-II ANTARES Facility

    Page(s): 2955 - 2962
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3137 KB) |  | HTML iconHTML  

    The rapidly developing field of high resolution neutron radiography primarily concentrates on non-destructive studies of stationary objects with relatively long exposure times required to achieve adequate neutron statistics. The combination of a high intensity neutron beam with a high temporal and spatial resolution detector, enables the investigation of dynamic processes in a stroboscopic mode, where image frames are synchronized with the sample or acquired continuously at high acquisition frame rates. Although neutron statistics in the acquisition frames as short as <; 10 μs is considered quite low (typically <; 1000 n/cm2 at the sample), repetitive processes can still be studied with high resolution by integrating a large number of frames synchronized to the process. In this paper we demonstrate the stroboscopic imaging capabilities of the highly collimated thermal neutron beamline ANTARES together with a high resolution detector with neutron-sensitive microchannel plates and the Medipix2 readout. The dynamics of water uptake due to capillary forces as well as the two-phase flow of an air-water mixture is investigated, and stroboscopic imaging of an operating beam chopper and a spinning fan is performed, with sub-100-μm spatial resolution and with acquisition frames varying between 10 μs and 200 ms. The results of these experiments demonstrate the future potential for performing high resolution neutron radiography of fast and/or repetitive processes, such as water flow and uptake, operation of fuel injection nozzles, as well as many others. View full abstract»

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  • A Double-Gain, Large Dynamic Range Front-end ASIC With A/D Conversion for Silicon Detectors Read-Out

    Page(s): 2963 - 2970
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (684 KB) |  | HTML iconHTML  

    We present a prototype of an application specific integrated circuit (ASIC) featuring an input dynamic range of more than 52 pC. The ASIC is designed to read out signals from large-capacitance silicon detectors used in Si-W calorimeters for high-energy astroparticle physics experiments. The ASIC features a double-gain Charge Sensitive Amplifier (CSA), which uses a real-time automatic gain selection circuitry to switch between the input ranges of [0-2.4 pC] and [0-52.6 pC]. A Correlated Double Sampling (CDS) filter follows the CSA and completes the front-end chain. A complete analog channel dissipates 2.8 mW. The present prototype also includes 9 cyclic ADC channels, in view of the final objective of this project, which will be a 16-channel chip with digitized outputs. View full abstract»

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  • Low-Noise Analog ASIC for Silicon and CdTe Sensors

    Page(s): 2971 - 2977
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (645 KB) |  | HTML iconHTML  

    We report on the recent development of a 32-channel low-noise analog front-end ASIC "KW03" for hard X-ray and gamma-ray detectors. The ASIC aims for the readout of strip or pixel (pad) detectors utilizing silicon and cadmium telluride (CdTe) as detector materials. Each readout channel includes a charge-sensitive amplifier, bandpass filters and a sample-and-hold circuit. It also includes a leakage current compensation and pole-zero cancellation circuits to meet the various detector requirements. The equivalent noise level of a typical channel reaches 89 e- @ 0 pF (rms) and shows an input-capacitance characteristic of 7.5 e-/pF between 0 pF and 10 pF with a power consumption of 3 mW per channel. We mounted the ASIC on a low-temperature co-fired ceramic (LTCC) package and evaluated the spectral performance by combining with a CdTe diode detector. As a result, the gamma-ray spectrum of radioactive source 241 Am was obtained with a good energy resolution of 2.23 keV (FWHM) for gamma rays of 59.5 keV at -20°C. View full abstract»

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  • Guard Ring Simulations for n-on-p Silicon Particle Detectors

    Page(s): 2978 - 2986
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (794 KB) |  | HTML iconHTML  

    We propose a new guard ring geometry for n-on-p silicon particle detectors for high luminosity applications. The performance of the guard ring structure is evaluated with simulations up to a radiation fluence of 1 x 1015 neq/cm2 using an existing three level trap model for p-type FZ silicon. The post-irradiation performance improvement of guard rings with floating field plates pointing towards the sensitive region is demonstrated. The breakdown behavior of the guard ring structure is studied as a function of oxide charge, field plate length, and oxide thickness. View full abstract»

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IEEE Transactions on Nuclear Science focuses on all aspects of the theory and applications of nuclear science and engineering, including instrumentation for the detection and measurement of ionizing radiation; particle accelerators and their controls; nuclear medicine and its application; effects of radiation on materials, components, and systems; reactor instrumentation and controls; and measurement of radiation in space.

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