1,721,093 research outputs found
A wide-band low-noise charge amplifier with High Electron Mobility Transistor input stage
No full textWe present the design and performance of a wide-band amplifier for radiation detectors employing an High Electron Mobility Transistor at its input. An Equivalent Noise Charge of less than 150 rms electrons has been measured at room temperature with RC-CR shaping ranging from 100 ns down to 10 ns. The particular requirements and advantages for using HEMTs as front-end device in charge amplifier are analysed
A low noise silicon detector preamplifier system for room temperature x-ray spectroscopy
No full textThe design and performances of a system for high resolution X-ray spectroscopy are presented. The detector is a low capacitance diode built on high resistivity silicon. The signal preamplification is made by means of an ultra-low noise charge amplifier of new conception. Presently the system exhibits an equivalent noise charge of 61 r.m.s. electrons at 297 K and 32 r.m.s. electrons at 223 K. It is shown how an improvement down to 30 r.m.s. electrons at room temperature is expected employing an integrated transistor on the detector chip
Resolution Limits of Silicon Detectors and Electronics for Soft X Ray Spectroscopy at non Cryogenic Temperatures
No full textThis paper deals with the limits of the resolution achievable in soft X-ray spectroscopy using silicon detectors of different dimensions (pad, pixel and drift detectors) operated at non-cryogenic temperatures. The role of the front-end electronics in achieving high resolution is examined with special care. It is found that in a common experimental setup the ultimate performance of the spectrometer is not limited by the thermal and shot white noises: the main contribution to the resolution performance arises from the non-white component of parallel noise due to the dielectric losses in the passive devices connected to the preamplifier input, especially when the detector leakage current is in the pA range. By using high quality feedback capacitors we have obtained significant improvements in the resolution performance. With a ceramic feedback capacitor and a commercial device as input transistor we have obtained' at room temperature an Equivalent Noise Charge as low as 15 electrons rms (130 eV FWHM). We discuss the ultimate limits and the perspectives for room temperature operation of silicon soft X-ray detectors
Criteria of choice of the front-end transistor for low-noise preamplification of detector signals at sub-microsecond shaping times for X- and γ-ray spectroscopy
No full textWe present an analysis of the electronic noise contributions which limit the resolution of X- and γ-ray spectrometers employing semiconductor detectors operating at room temperature and at signal processing times in the sub-microsecond range. The figures of merit of the front-end transistors, relevant to attain the highest resolution, are put in evidence. It is shown how the correlation between the gate and drain current noises in FETs plays a significant role in the equivalent noise charge of a charge preamplifier. Some state of the art devices, belonging to different technologies, JFET, MOSFET, MESFET and HFET, are examined
An HEMT Input Charge Preamplifier for Nanoseconds Signal Processing Time
No full textThe capabilities of the high electron mobility transistor (HEMT) as front end device in charge preamplifiers for radiation detectors have been experimentally tested. We present the design and performance of a fast low-noise charge preamplifier having an HEMT as input transistor. An equivalent noise charge of 139 rms electrons, i.e., 1.13 keV FWHM in silicon detectors, has been measured at room temperature with 10 ns RC-CR shaping and 1 pF input capacitance
A Method for the Determination of the Noise Parameters in Preamplifying Systems for Semiconductor Radiation Detectors
No full textIn this paper a method for disentangling the various noise components in semiconductor radiation detector-amplifier systems is described and experimentally tested. A charge amplification scheme is adopted for the measurements. It is shown how an accurate estimate of the series and parallel white noise, 1/f series noise, and f parallel noise can be quickly obtained through a multiparameter least-squares interpolation of the equivalent noise charge data of the system
A compact VLSI dc restorer for multichannel X-gamma ray detectors
No full textWe present a compact, fully integrated, low power baseline restorer for radiation detector readout ASICs. The proposed circuit has been designed, simulated, and layed out using a 0.35 um CMOS technology. It features an area occupancy of 90 x 100 um2 and a power consumption of 90 uW for 3.3 V power supplies, which makes it suitable for highly packed multichannel detector readouts. In the paper the principle of operation of the circuit as well as the results of the simulations are discussed
Silicon detector system for high rate EXAFS applications
No full textA multichannel silicon pad detector for EXAFS (Extended X-ray Absorption Fine Structure) applications has been designed and built. The X-ray spectroscopic measurements demonstrate that an adequate energy resolution of 230 eV FWHM (corresponding to 27 rms electrons in silicon) can be achieved reliably at -35 °C. A resolution of 190 eV FWHM (corresponding to 22 rms electrons) has been obtained from individual pads at -35 °C. At room temperature (25 °C) an average energy resolution of 380 eV FWHM is achieved and a resolution of 350 eV FWHM (41 rms electrons) is the best performance. A simple cooling system constituted of Peltier cells is sufficient to reduce the reverse currents of the pads and their related shot noise contribution, in order to achieve resolutions better than 300 eV FWHM which is adequate for the EXAFS applications
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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