Search results for "silicon"
showing 10 items of 1391 documents
Rayleigh–Bénard instability of Czochralski configuration in a transverse magnetic field
2012
Abstract The linear instability of a rotating conducting liquid cylinder heated from below in a horizontal magnetic field is considered numerically. A condition for the magnetic suppression of the bulk rotation is obtained. If the bulk is rotation dominated then the linear instability is slightly delayed by the field and sets in as a rotating wave. If the bulk is dominated by the magnetic field then the instability has the form of field aligned convection rolls. Outside thin boundary layers the instability then becomes increasingly similar to the onset in a plain channel. The results are discussed in light of previous silicon growth experiments and existing knowledge from related problems.
Unraveling exciton dynamics in amorphous silicon dioxide: Interpretation of the optical features from 8 to 11 eV.
2011
Physical review / B 83, 174201 (2011). doi:10.1103/PhysRevB.83.174201
High-precision X-ray spectroscopy of highly-charged ions at the experimental storage ring using silicon microcalorimeters
2017
Abstract X-ray spectroscopy on highly charged heavy ions provides a sensitive test of quantum electrodynamics in very strong Coulomb fields. One limitation of the current accuracy of such experiments is the energy resolution of available X-ray detectors for energies up to 100 keV. To improve this accuracy, a novel detector concept, namely the concept of microcalorimeters, is exploited for this kind of measurements. The microcalorimeters used in the present experiments consist of silicon thermometers, ensuring a high dynamic range, and of absorbers made of high-Z material to provide high X-ray absorption efficiency. Recently, besides an earlier used detector, a new compact detector design, h…
Forward diffracted parametric X radiation from a silicon single crystal
2005
Experiments were performed with the 855 MeV electron beam of the Mainz Microtron MAMI which focused on still open questions in the X-ray emission process upon traversal of ultra relativistic electrons through single crystals. To elucidate the quest of kinematical versus dynamical production of PXR the radiation from silicon single crystal targets, emitted close to the electron direction, has been studied. The observed interference structures show that PXR is produced in a dynamical process.
Emitter-site specificity of hard x-ray photoelectron Kikuchi-diffraction
2020
New journal of physics 22(10), 103002 (1-13) (2020). doi:10.1088/1367-2630/abb68b
Monte-Carlo calculations of keV electron and positron slowing down in solids
1983
A Monte-Carlo simulation technique based on the screened Rutherford differential cross section for the elastic scattering and Gryzinski's semiempirical expression for the inelastic core and valence electron excitation is used to describe electrons and positrons slowing down in solids. The theoretical results are compared with the experimental backscattering, absorption and transmission results for aluminum, silicon, copper, and gold thin film and semi-infinite targets and good agreement is observed. The simulated stopping profiles are fitted with a simple analytic expression. The profiles are Laplace-transformed to give a useful data base for analyzing phenomena associated with slow positro…
PESIC: An Integrated Front-End for PET Applications
2007
An ASIC front-end has been developed for multi-anode photomultiplier based nuclear imaging devices. Its architecture has been designed to improve resolution and decrease pile-up probability in Positron Emission Tomography systems which employ continuous scintillator crystals. Analog computation elements are isolated from the photomultiplier by means of a current sensitive preamplifier stage. This allows digitally programmable adjustment of every anode gain, also providing better resolution in gamma event position calculation and a shorter front-end deadtime. The preamplifier stage also offers the possibility of using other types of photomultiplier devices such as SiPM. The ASIC architecture…
The melting behaviour of small silicon clusters
1994
Abstract We report an analysis of the melting behaviour of small silicon clusters interacting via a nonlinear interatomic potential with four-body terms. The analysis shows, by means of Monte Carlo and molecular dynamics simulations, that the small silicon clusters undergo, in a vacuum, structural changes from a solid rigid state to a liquid-like state. The melting temperature exhibits a strong variation with cluster size.
The isomeric structure of132Pr
2012
The isomeric structure of the neutron deficient nucleus 132Pr, located in the rare-earth region of the nuclear chart, has been studied with the 98Mo(40Ar,5pn)132Pr reaction at beam energies of 150, 158 and 165 MeV. The experiment was performed at the University of Jyvaskyla, Finland where the 40Ar beam was accelerated onto the target by the K130 cyclotron. The JUROGAM II HPGe detector array was employed in conjunction with the RITU gas-filled recoil separator. The focal-plane chamber housed a multi wire proportional counter and a position-sensitive silicon strip detector used for the implantation and identification of recoiling nuclei. The recoil-isomer tagging technique was used to correla…
Channeling and Radiation of Electrons in Silicon Single Crystals and Si1−xGexCrystalline Undulators
2013
The phenomenon of channeling and the basic features of channeling radiation emission are introduced in a pedestrian way. Both, radiation spectra as well as dechanneling length measurements at electron beam energies between 195 and 855 MeV feature quantum state phenomena for the (110) planar potential of the silicon single crystals. Radiation from a crystalline undulator, produced at the Aarhus University (UAAR), has been investigated at the Mainz Microtron electron accelerator facility MAMI. The 4-period epitaxially grown strained layer Si1−xGex undulator had a period length λu = 9.9 μm. At a beam energy of 375 MeV a broad excess yield around the theoretically expected photon energy of 0.13…