7 research outputs found
Apple II direct memory access interface to acquire neutron scattering time of flight spectra
No full text
PRISMA - a spectrometer for the measurement of coherent excitations on a pulsed spallation neutron source
No full textThe measurement of nuclear and magnetic excitation spectra from single crystal samples remains central to condensed matter physics. The requirements in terms of the range and resolution of the scattering vector Q and energy transfer h ω are reviewed and typical experiments with a well defined cross-section are chosen. The performance and limitations of existing instruments are reviewed. A design for a new spectrometer, PRISMA, to be installed on the UK spallation neutron source, ISIS, is presented. Its performance for chosen experiments is given in terms of the Q and h ω range covered in a single scan, the resolution and the count rate
Single particle dynamics in molecular systems: fluid and solid hydrogen sulphide
No full textDottorato di ricerca in fisica. 12. ciclo. A. a. 1998-99. Relatori Carla Andreani, Emanuele Pace e Francesco Cilloco. Coordinatore Piergiorgio PicozzaConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome; Biblioteca Nazionale Centrale - P.za Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal
Confocal, wide band spectral reflection microscope, and relevant spectral imaging method
No full textThis invention concerns a wideband spectral reflectance confocal microscope comprising a laser source (LS), a beam expander (BE) inserted immediately after the laser source (LS), a beam splitter (BS) in an adequately transparent material through the whole spectral interval emitted by the laser source (LS), a system (OB1) to focus the laser beam on the sample (S) presenting a working distance greater than 5mm and a numerical aperture greater than 0.25, a collection system (M, OB2, PH) and an analysis system (AS) of the laser beam reflected by the sample and transmitted by the beam splitter (BS), said analysis system (AS) comprising a chromatic dispersion subsystem capable of forming the spectrum to be analysed, the microscope being characterized in that: said laser source (LS) is a source that emits simultaneously at several wavelengths in the visible and infrared regions; said focusing system (OB1 ) is free of chromatic aberration; said beam splitter (BS) is positioned at 45° in respect of the laser beam direction; said collection system (M, OB2, PH) is free of chromatic aberration; so that at each analysed point of the sample (S) corresponds unambiguously a frequency response spectrum collected by the collection system (M, OB2, PH). The invention concerns as well a spectral imaging method of a sample (S) by means of a wideband spectral reflectance confocal microscope, besides the utilisation of the microscope of this invention for the same imaging
Information-theory-based solution of the inverse problem in classical statistical mechanics
No full textWe present a procedure for the determination of the interaction potential from the knowledge of the radial pair distribution function. The method, realized inside an inverse Monte Carlo simulation scheme, is based on the application of the maximum entropy principle of information theory and the interaction potential emerges as the asymptotic expression of the transition probability. Results obtained for high density monoatomic fluids are very satisfactory and provide an accurate extraction of the potential, despite a modest computational effort
