17 research outputs found
Silicon detectors for gamma-ray and beta spectroscopy
No full textLarge active volume Si(Li) detectors were successfully developed for gamma-ray spectrometry at room temperature that show a sufficient efficiency and an energy resolution that is better than scintillation detectors. The higher efficiency of the proposed detectors with respect to normal silicon diodes is achieved by increasing the active volume. For this purpose special attention is given to the selection of the initial material which has to show homogeneous electrophysical parameters, low concentration of oxygen impurities and high structural perfection. The technique of using lithium ions is used as these drift into large depths and hence the profile of the impurity distribution is optimized
Radiation hardness of silicon detectors based on pre-irradiated silicon
No full textRadiation hardness of planar detectors processed from pre-irradiated and thermo-annealed n-type FZ silicon substrates, and standard FZ as a reference, was studied. The high purity n-Si wafers with carrier concentration 4.8x1011 cm-3 were pre-irradiated in Kiev’s nuclear research reactor by fast neutrons to fluence of about 1016 neutrons/cm2 and thermo-annealed at a temperature of about 850 1C. Silicon diodes were fabricated from standard and pre-irradiated silicon substrates by IRST (Italy). All diodes were subsequently irradiated by fast neutrons at Kiev and Ljubljana nuclear reactors. The dependence of the effective doping concentration as a function of fluence (Neff = f(F)) was measured for reference and pre-irradiated diodes. Pre-irradiation of silicon improves the radiation hardness by decreasing the acceptor introduction rate (b), thus mitigating the depletion voltage (Vdep) increase. In particular, b in reference samples is about 0.017 cm-1, and for pre-irradiated samples is about 0.008 cm-1. Therefore, the method of preliminary irradiation can be useful to increase the radiation hardness of silicon devices to be used as sensors or detectors in harsh radiation environments
Study of Neutron Pre-Irradiated Silicon for Nuclear Detectors
No full textThe ways of increasing the radiation hardness of silicon were considered. It was then experimentally shown that a preliminary irradiation of the bulk silicon introduces sinks for radiation defects that leads to an increased radiation hardness of the silicon. Neutron transmutation doping of silicon can be considered as one form of preliminary radiation. It was shown that for neutron transmutated silicon the carrier removal rate in NTD after γ-irradiation is more than one order of magnitude smaller than in a standard reference specimen, but the carriers removal rate after neutron irradiation is approximately a factor of two less
A dataflow IR for memory efficient RIPL compilation to FPGAs
No full textField programmable gate arrays (FPGAs) are fundamentally different to fixed processors architectures because their memory hierarchies can be tailored to the needs of an algorithm. FPGA compilers for high level languages are not hindered by fixed memory hierarchies. The constraint when compiling to FPGAs is the availability of resources.
In this paper we describe how the dataflow intermediary of our declarative FPGA image processing DSL called RIPL (Rathlin Image Processing Language) enables us to constrain memory. We use five benchmarks to demonstrate that memory use with RIPL is comparable to the Vivado HLS OpenCV library without the need for language pragmas to guide hardware synthesis. The benchmarks also show that RIPL is more expressive than the Darkroom FPGA image processing language
Mathematical analysis of the stability of heart-rate dynamics in postinfarction patients
No full textSemiconductor sensors for dosimetry of epithermal neutrons
No full textMinimum energy of neutron to displace atoms in silicon crystals are equal to 200 eV. Due to this fact testing our p-i-n diodes under irradiation by the epithermal neutrons was carried out. The more advanced p-i-n diodes on the base of high purity silicon were used at present work, and, as a result, we have obtained considerably more sensitive sensors for more wide range of neutron doses. The sensitivity of sensors is 0.14 V/Gy for average neutron energy of 24 keV
Dose dependence of the concentration of carriers in high resistivity SI irradiated by 24 GeV protons and properties of the detectors on its base
No full textRecent advancements in the development of radiation hard semiconductor detectors for S-LHC.
No full textThe proposed luminosity upgrade of the Large Hadron Collider (S-LHC) at CERN will demand the innermost layers of the vertex detectors to sustain fluences of about 1016 hadrons/cm2. Due to the high multiplicity of tracks, the required spatial resolution and the extremely harsh radiation field new detector concepts and semiconductor materials have to be explored for a possible solution of this challenge. The CERN RD50 collaboration “Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders” has started in 2002 an R&D program for the development of detector technologies that will fulfill the requirements of the S-LHC. Different strategies are followed by RD50 to improve the radiation tolerance. These include the development of defect engineered silicon like Czochralski, epitaxial and oxygen-enriched silicon and of other semiconductor materials like SiC and GaN as well as extensive studies of the microscopic defects responsible for the degradation of irradiated sensors. Further, with 3D, Semi-3D and thin devices new detector concepts have been evaluated. These and other recent advancements of the RD50 collaboration are presented and discussed
Development of radiation tolerant semiconductor detectors for the Super-LHC.
No full textThe envisaged upgrade of the Large Hadron Collider (LHC) at CERN towards the Super-LHC (SLHC) with a 10 times increased luminosity of 1035 cm−2 s−1 will present severe challenges for the tracking detectors of the SLHC experiments. Unprecedented high radiation levels and track densities and a reduced bunch crossing time in the order of 10 ns as well as the need for cost effective detectors have called for an intensive R&D program. The CERN RD50 collaboration “Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders” is working on the development of semiconductor sensors matching the requirements of the SLHC. Sensors based on defect engineered silicon like Czochralski, epitaxial and oxygen enriched silicon have been developed. With 3D, Semi-3D and thin detectors new detector concepts have been evaluated and a study on the use of standard and oxygen enriched p-type silicon detectors revealed a promising approach for radiation tolerant cost effective devices. These and other most recent advancements of the RD50 collaboration are presented
