1,721,370 research outputs found
AN APPARATUS FOR SCINTIGRAPHIC ANALYSIS, PARTICULARLY A MAMMOGRAPH,WITH SUB-MILLIMETRIC SPATIAL RESOLUTION
No full textA scintigraphic mammograph with sub-millimetric spatial resolution adapted to detect gamma radiations with 30 KeV to 2 MeV energy, comprising a sensitive head section (10) with a box shaped shielding container (16) co-operating with a standard pressure member and receiving the following essential components combined together in the following succession: an apertured collimator (11), of a high atomic number material, adapted to collimate the gamma radiation emissions from the body organ being investigated; a scintillating crystal and fluorescent fiber structure adapted to convert the gamma radiations emitted from the concerned body organ into light radiations; a multi-anode or crossed wire photo-multiplier or position sensitive solid state detector, which receives the light radiations emitted from said scintillating crystals and fluorescent fibers and generates signals proportional to the received light radiations; a hardware assembly adapted to perform conversion and integration of all signals generated by said photo-multiplier assembly from an analog to a digital format as well as their amplification in order to subsequently couple them to an electronic processor which processes and displays then on a suitable monitor in the form of an image of the concerned body organ
Charged and neutral double pion photoproduction cross-sections in the gamma-ray energy range (600 - 900) MeV.
No full text
Radon gamma-ray spectrometry with YAP : Ce scintillator
No full textThe detection properties of a YAP:Ce scintillator (YAlO3:Ce crystal) optically coupled to a Hamamatsu H5784 photomultiplier with standard bialkali photocathode have been analyzed. In particular, the application to radon and radon-daughters gamma-ray spectrometry was investigated. The crystal response has been studied under severe extreme conditions to simulate environments of geophysical interest, particularly those found in geothermal and volcanic areas. Tests in water up to a temperature of 100degreesC and in acids solutions such as HCl (37%), H2SO4 (48%) and HNO3 (65%) have been performed. The measurements with standard radon sources provided by the National Institute for Metrology of Ionizing Radiations (ENEA) have emphasized the non-hygroscopic properties of the scintillator and a small dependence of the light yield on temperature and HNO3. The data collected in this first step of our research have pointed out that the YAP:Ce scintillator can allow high response stability for radon gamma-ray spectrometry in environments with large temperature gradients and high acid concentrations. (C) 2002 Elsevier Science B.V. All rights reserved
Linear array of Si-Ge heterojunction photodetectors monolithically integrated with silicon CMOS readout electronics
No full textWe describe a linear array of Ge-Si heterojunction photodiodes monolithically integrated on a complementary metaloxide-semiconductor (CMOS) integrated circuit for detection and imaging in the near infrared. Detectors are realized by thermal evaporation of Ge films at the end of the standard CMOS process on substrates held at low temperature (300 degreesC). Each of the 64 detectors is connected to a front-end stage for photocurrent integration and analog-to-digital conversion
Polycrystalline germanium enables near-IR photodetectors integrated with silicon CMOS electronics - A near-IR imaging chip based on polycrystalline germanium on silicon opens new frontiers for integrated optoelectronics.
No full textMonolithic integration of near-infrared Ge photodetectors with Si complementary metal-oxide-semiconductor readout electronics
No full textUsing a low-temperature technology for polycrystalline Ge deposition, we report on the monolithic integration of an array of near-infrared Ge photodiodes on Si complementary metal-oxide-semiconductor (CMOS) electronics. The integrated microsystem consists of a linear array of 120x120 mum(2) pixels, an analog CMOS multiplexer and a transimpedance amplifier. The resulting photoresponse covers the near-infrared up to 1.6 mum. (C) 2002 American Institute of Physics
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
- …
