Search results for "Synchrotron"
showing 10 items of 307 documents
Time-of-flight photoelectron momentum microscopy with 80–500 MHz photon sources: electron-optical pulse picker or bandpass pre-filter
2021
Journal of synchrotron radiation 28(6), 1891 - 1908 (2021). doi:10.1107/S1600577521010511
X-ray thermal-diffuse-scattering study of soft modes in paraelectricBaTiO3
1995
Anomalous x-ray thermal diffuse scattering (TDS) from the paraelectric ${\mathrm{BaTiO}}_{3}$ has been measured as a function of temperature using synchrotron radiation. Sheets of intensities that were previously reported have been confirmed. The origin of the observed TDS intensities is attributed to the soft on-(100) TA modes and overdamped [010${]}_{\mathrm{TO}}$ mode for reduced wave vector qg0.25 and 0.25, respectively. In agreement with the previous neutron inelastic scattering experiment, our results support the notion of the one-dimensionally correlated optic motion of atoms.
Inclusive Pion Double Charge Exchange on Light Nuclei above 0.5 GeV
1995
Inclusive double charge exchange (DCX) reaction A(π −, π +) X on 6Li and 16O was for the first time measured at incident kinetic energy T 0 = 1.1 GeV ( ≈ 5°) for outgoing particle momentum region where additional pion production is kinematically forbidden. The experiment was performed at secondary π − beam of the ITEP proton synchrotron using the 3m magnet spectrometer. The measured double differential cross section at 1.1 GeV together with our previous results at 0.6 and 0.75 GeV [1] and with the lower energy data [2] and [3] shows rather slow decrease with energy. This result is in contradiction with the fast fall of small angle DCX cross section calculated [4] in the standard mechanism o…
Collective effects inνν¯synchrotron radiation from neutron stars
1999
We have considered the collective effects in $\ensuremath{\nu}\overline{\ensuremath{\nu}}$ synchrotron radiation from an ultrarelativistic degenerate electron gas in neutron stars with strong magnetic fields. For this problem we apply a calculation method which explicitly makes use of the fact that the radiating electron moves semiclassically, but takes into account the interaction among particles in a quantum way. First we apply this method to calculate $\ensuremath{\nu}\overline{\ensuremath{\nu}}$ synchrotron radiation by an ultrarelativistic electron in vacuum and we compare this result with that obtained previously by other techniques. When a degenerate plasma is considered, we show tha…
Plasma effects on neutrino-antineutrino synchrotron radiation in dense matter
2000
Abstract We consider plasma effects on ν ν synchroton radiation from ultrarelativistic, degenerate electrons in neutron stars with strong magnetic fields. Under typical conditions for such stars, a semiclassical calculation can be performed, in which electrons are considered to move along classical paths. We show that collective effects in the plasma lead to an essential enhancement (about three times) of the vector weak-current contributions to neutrino pair emissivity.
Emittance Growth by Synchrotron Radiation in a Double-Sided Microtron
1999
Here we present results of calculations of emittance growth caused by quantum fluctuations of synchrotron radiation (QFSR) for a 1.5 GeV double-sided microtron (DSM). We did both semi-analytical estimations, employing known Twiss parameters for the DSM orbits, and a computer simulation of these stochastic effects using the program SYTRACE. This showed that the normalized emittance growth was within reasonable limits, by a factor of about 1.5, thus permitting e.g. the installation of small aperture linacs on the DSM axes.
Spectral and morphological analysis of the remnant of Supernova 1987A with ALMA and ATCA
2014
We present a comprehensive spectral and morphological analysis of the remnant of Supernova (SN) 1987A with the Australia Telescope Compact Array (ATCA) and the Atacama Large Millimeter/submillimeter Array (ALMA). The non-thermal and thermal components of the radio emission are investigated in images from 94 to 672 GHz ($\lambda$ 3.2 mm to 450 $\mu$m), with the assistance of a high-resolution 44 GHz synchrotron template from the ATCA, and a dust template from ALMA observations at 672 GHz. An analysis of the emission distribution over the equatorial ring in images from 44 to 345 GHz highlights a gradual decrease of the east-to-west asymmetry ratio with frequency. We attribute this to the shor…
Stability and nature of the volume collapse of ε-Fe2O3 under extreme conditions
2018
Iron oxides are among the major constituents of the deep Earth’s interior. Among them, the epsilon phase of Fe2O3 is one of the less studied polymorphs and there is a lack of information about its structural, electronic and magnetic transformations at extreme conditions. Here we report the precise determination of its equation of state and a deep analysis of the evolution of the polyhedral units under compression, thanks to the agreement between our experiments and ab-initio simulations. Our results indicate that this material, with remarkable magnetic properties, is stable at pressures up to 27 GPa. Above 27 GPa, a volume collapse has been observed and ascribed to a change of the local env…
Sprouting and intussusceptive angiogenesis in postpneumonectomy lung growth: mechanisms of alveolar neovascularization
2013
In most rodents and some other mammals, the removal of one lung results in compensatory growth associated with dramatic angiogenesis and complete restoration of lung capacity. One pivotal mechanism in neoalveolarization is neovascularization, because without angiogenesis new alveoli can not be formed. The aim of this study is to image and analyze three-dimensionally the different patterns of neovascularization seen following pneumonectomy in mice on a sub-micron-scale. C57/BL6 mice underwent a left-sided pneumonectomy. Lungs were harvested at various timepoints after pneumonectomy. Volume analysis by microCT revealed a striking increase of 143 percent in the cardiac lobe 14 days after pneum…
Sub-nanosecond resolution x-ray magnetic circular dichroism photoemission electron microscopy of magnetization processes in a permalloy ring
2005
Fast magnetization processes in a microstructured permalloy ring with 80 µm o.d. and 30 nm thickness have been observed by photoemission electron microscopy exploiting x-ray magnetic circular dichroism as the magnetic contrast mechanism. As a high speed probe we employed synchrotron radiation pulses at the ESRF (Grenoble) operated in 16-bunch mode, yielding photon pulses of 105 ps FWHM with a period of 176 ns. Fast magnetic field pulses have been generated by means of current pulses through coplanar waveguides with the magnetic structure being lithographically prepared on their surface. A stroboscopic pump–probe set-up with a variable time delay between the field pulse and photon pulse allo…