131 research outputs found

    The development of a position-sensitive CZT detector with orthogonal co-planar anode strips

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    We report on the simulation, construction, and performance of prototype CdZnTe imaging detectors with orthogonal coplanar anode strips. These detectors employ a novel electrode geometry with non-collecting anode strips in one dimension and collecting anode pixels, interconnected in rows, in the orthogonal direction. These detectors retain the spectroscopic and detection efficiency advantages of single carrier (electron) sensing devices as well as the principal advantage of conventional strip detectors with orthogonal anode and cathode strips, i.e. an N×N array of imaging pixels are with only 2N electronic channels. Charge signals induced on the various electrodes of a prototype detector with 8×8 unit cells (1×1×5 mm3)are compared to the simulations. Results of position and energy resolution measurements are presented and discussed

    Analog processing of signals from a CZT strip detector with orthogonal coplanar anodes

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    We present the requirements, design, and performance of an analog circuit for processing the non-collecting anode strip signals from a cadmium zinc telluride (CZT) strip detector with orthogonal coplanar anodes. Detector signal simulations and measurements with a prototype are used to define the range of signal characteristics as a function of location of the gamma interaction in the detector. The signals from the non- collecting anode strip electrodes are used to define two of the three spatial coordinates including the depth of interaction, the z dimension. Analog signal processing options are discussed. A circuit to process the signals from the non- collecting anode strips and extract from them the depth of interaction is described. The circuit employs a time-over- threshold (TOT) measurement. The performance of the detector prototype with a preliminary version of this circuit is presented, and future development work is outlined

    Energy and position resolution of a CdZnTe gamma-ray detector with orthogonal coplanar anodes

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    We report on the simulation, construction and performance of prototype CZT imaging detectors employing orthogonal coplanar anodes. These detectors employ a novel electrode geometry with non-collecting anode strips in 1D and collecting anode pixels, interconnected in rows, in the orthogonal dimensions. These detectors retain the spectroscopic and detection efficiency advantages of single carried charge sensing devices as well as the principal advantage of conventional strip detectors with orthogonal anode and cathode strips, i.e. an N X N array of imagin pixels are realized with only 2N electronic channels. Charge signals induced on the various electrodes of a prototype detector with 8 X 8 unit cells are in good agreement with the simulations. The position resolution is about 1 mm in the direction perpendicular to the pixel lines while it is of the order of 100 micrometers in the other direction. Energy resolutions of 0.9 percent at 662 keV, 2.6 percent at 122 keV and 5.7 percent at 60 keV have been obtained at room temperature

    Einfluss des eingeatmeten Staubes, bei Verarbeitung des Eisen, auf die interstizialmuskulatur der isolierten Froschzunge

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    Na model-sistemu izoliranih pluća ispitivan je toksični utjecaj prašine koja se stvara pri obradi željeza. Osim ispitivanja suspenzije ukupne prašine, ispitivano je osam kemijski čistih, topljivih komponenata prašine aplicirane na alveolarnu i pleuralnu stranu. Pluća su ravnomjerno koaksijalna stimulirana a bio je ispitivan uzajamni utjecaj stimulacije i efekti supstanca. Prašina i posebno topljivi ioni metala, koji u obliku oksida dolaze kao njene glavne komponente, aplicirani na pleuralnu stranu dovode do spazma glatke muskulature izoliranih pluća i povećanja izazvanih kontrakcija. Ukoliko se spomenute supstance apliciraju na alveolarnu stranu, kako pri obavljanju posla obično dolazi u kontakt sa sluznicom, prašina iz krečane izaziva jak spazam a prašina iz koksare relaksaciju pluća. Od osam ispitivanih komponenata željezo i nikal redovito dovode do spazma a magnezij i mangan do relaksacije kada dođu u kontakt s alveolama pluća. Pri prosuđivanju djelovanja raznih prašina treba voditi računa ne samo o njihovom djelovanju kao faktoru pneumokonioza nego i o njihovom akutnom farmakološkom efektu.Die toxische Wirkung des Staubes, der sich während der Eisenverarbeitung bildet, wurde an isolierter Lunge die als Modell-System diente untersucht. Neben der Untersuchung der gesamten Staubsuspension, wurden auch einige (8) an die alveolare und pleurale Seite applizierte chemisch-reine Staubkomponenten untersucht. Die Lunge wurde gleichmässig koaxial stimuliert und der Einfluss der Stimulation und der Substanzeffekte geprüft. Der Staub und besonders seine Hauptkomponenten die, an pleuraler Seite appliziert wurden, führten einerseits zum Spasmus der glatten Muskulatur der isolierten Lunge und andererseits zur Vergrösserung der herbeigeführten Kontraktionen. Wenn die genannten Substanzen an die alveolare Seite appliziert wurden, rufte der Staub der Kalkgrube (Kreöana) einen starken Spasmus hervor, weil der Staub aus der »Kokerei« (Koksara) eine Relaxation der Lunge herbei führte. Von acht geprüften Komponenten Eisen und Nickel führen, in der Regel, zum Spasmus, und Magnesium und Mangan zur Relaxation wenn sie mit den Lungenalveolen in Kontakt kommen. Bei der Beurteilung der Wirkung verschiedener Staube muss man nicht nur von ihrer Wirkung als Faktor der Pneumokoniose Rechnung führen, sondern auch von ihren akuten pharmakologischen Effekt

    Digital synthesis of pulse shapes in real time for high resolution radiation spectroscopy

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    Techniques have been developed for the synthesis of pulse shapes using fast digital schemes in place of the traditional analog methods of pulse shaping. Efficient recursive algorithms have been developed that allow real time implementation of a shaper that can produce either trapezoidal or triangular pulse shapes. Other recursive techniques are presented which allow a synthesis of finite cusp-like shapes. Preliminary experimental tests show potential advantages of using these techniques in high resolution, high count rate pulse spectroscopy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31506/1/0000428.pd

    Three-dimensional imaging and detection efficiency performance of orthogonal coplanar CZT strip detectors

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    We report on recent three-dimensional imaging performance and detection efficiency measurements obtained with 5 mm thick prototype CdZnTe detectors fabricated with orthogonal coplanar anode strips. In previous work, we have shown that detectors fabricated using this design achieve both very good energy resolution and sub-millimeter spatial resolution with fewer electronic channels than are required for pixel detectors. As electron-only devices, like pixel detectors, coplanar anode strip detectors can be fabricated in the thickness required to be effective imagers for photons with energies in excess of 500 keV. Unlike conventional double-sided strip detectors, the coplanar anode strip detectors require segmented contacts and signal processing electronics on only one surface. The signals can be processed to measure the total energy deposit and the photon interaction location in three dimensions. The measurements reported here provide a quantitative assessment of the detection capabilities of orthogonal coplanar anode strip detectors

    Charge calibration of CsI(Tl)/photodiode spectroscopy systems

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    A charge calibration method for spectroscopy systems that use inorganic scintillators, photodiodes, and charge-sensitive preamplifiers is presented. The shaped square wave (SSW) method accounts for ballistic deficit when long decay time constants are present. The SSW method is demonstrated for CsI(T1) and compared to other calibration methods.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30115/1/0000491.pd

    Digital techniques for real-time pulse shaping in radiation measurements

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    Recursive algorithms for real-time digital pulse shaping in pulse height measurements have been developed. The differentiated signal from the preamplifier (exponential pulse) is amplified and then digitized. Digital data are deconvolved so that the response of the high-pass network is eliminated. The deconvolved pulse is processed by a time-invariant digital filter which allows trapezoidal/triangular or cusp-like shapes to be synthesized. A prototype of a digital trapezoidal processor was built which is capable of sampling and processing digital data in real time at clock rates up to 50 MHz.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31113/1/0000009.pd

    Pulse-Shape discrimination with the Counting Test Facility

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    Pulse shape discrimination (PSD) is one of the most distinctive features of liquid scintillators. Since the introduction of the scintillation techniques in the field of particle detection, many studies have been carried out to characterize intrinsic properties of the most common liquid scintillator mixtures in this respect. Several application methods and algorithms able to achieve optimum discrimination performances have been developed. However, the vast majority of these studies have been performed on samples of small dimensions. The Counting Test Facility, prototype of the solar neutrino experiment Borexino, as a 4 ton spherical scintillation detector immersed in 1000 tons of shielding water, represents a unique opportunity to extend the small-sample PSD studies to a large-volume setup. Specifically, in this work we consider two different liquid scintillation mixtures employed in CTF, illustrating for both the PSD characterization results obtained either with the processing of the scintillation waveform through the optimum Gatti's method, or via a more conventional approach based on the charge content of the scintillation tail. The outcomes of this study, while interesting per se, are also of paramount importance in view of the expected Borexino detector performances, where PSD will be an essential tool in the framework of the background rejection strategy needed to achieve the required sensitivity to the solar neutrino signals.Comment: 39 pages, 17 figures, submitted to Nucl. Instr. Meth.
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