Electron Scattering From a High Momentum Neutron in Deuterium

The deuterium nucleus is a system of two nucleons (proton and neutron) bound together. The configuration of the system is described by a quantum-mechanical wave function and the state of the nucleons at a given time is not known a priori. However, by detecting a backward going proton of moderate momentum in coincidence with a reaction taking place on the neutron in deuterium, the initial state of that neutron can be inferred if we assume that the proton was a spectator to the reaction. This method, known as spectator tagging, was used to study the electron scattering from high-momentum neutrons in deuterium. The data were taken with a 5.765 GeV polarized electron beam on a deuterium target in Jefferson Laboratory\u27s Hall B, using the CLAS detector. The accumulated data cover a wide kinematic range, reaching values of the invariant mass of the unobserved final state W* up to 3 GeV. A data sample of approximately 5 · 105 events, with protons detected at large scattering angles (as high as 136°) in coincidence with the forward electrons, was selected. The product of the neutron structure function with the initial nucleon momentum distribution F2n · S was extracted for different values of W*, backward proton momenta ps and momentum transfer Q2. The data were compared to a calculation based on the spectator approximation and using the free nucleon form factors and structure functions. A strong enhancement in the data, not reproduced by the model, was observed at cos (θpq ) \u3e −0.3 (where θpq is the proton scattering angle relative to the direction of the momentum transfer) and can be associated with the contribution of final state interactions (FSI) that were not incorporated into the model. The bound nucleon structure function F2n was studied in the region cos(θpq) \u3c −0.3 as a function of W* and scaling variable x*. At high spectator proton momenta the struck neutron is far off its mass shell. At ps \u3e 400 MeV/c the model overestimates the value of F2n in the region of x* between 0.25 and 0.6. A modification of the bound neutron structure is one of possible effects that can cause the observed deviation

Gigahertz (GHz) hard x-ray imaging using fast scintillators

Gigahertz (GHz) imaging technology will be needed at high-luminosity X-ray and charged particle sources. It is plausible to combine fast scintillators with the latest picosecond detectors and GHz electronics for multi-frame hard Xray imaging and achieve an inter-frame time of less than 10 ns. The time responses and light yield of LYSO, LaBr_3, BaF_2 and ZnO are measured using an MCP-PMT detector. Zinc Oxide (ZnO) is an attractive material for fast hard X-ray imaging based on GEANT4 simulations and previous studies, but the measured light yield from the samples is much lower than expected

Gigahertz (GHz) hard x-ray imaging using fast scintillators

Gigahertz (GHz) imaging technology will be needed at high-luminosity X-ray and charged particle sources. It is plausible to combine fast scintillators with the latest picosecond detectors and GHz electronics for multi-frame hard Xray imaging and achieve an inter-frame time of less than 10 ns. The time responses and light yield of LYSO, LaBr_3, BaF_2 and ZnO are measured using an MCP-PMT detector. Zinc Oxide (ZnO) is an attractive material for fast hard X-ray imaging based on GEANT4 simulations and previous studies, but the measured light yield from the samples is much lower than expected

All-sky Medium Energy Gamma-ray Observatory: Exploring the Extreme Multimessenger Universe

The All-sky Medium Energy Gamma-ray Observatory (AMEGO) is a probe class mission concept that will provide essential contributions to multimessenger astrophysics in the late 2020s and beyond. AMEGO combines high sensitivity in the 200 keV to 10 GeV energy range with a wide field of view, good spectral resolution, and polarization sensitivity. Therefore, AMEGO is key in the study of multimessenger astrophysical objects that have unique signatures in the gamma-ray regime, such as neutron star mergers, supernovae, and flaring active galactic nuclei. The order-of-magnitude improvement compared to previous MeV missions also enables discoveries of a wide range of phenomena whose energy output peaks in the relatively unexplored medium-energy gamma-ray band

Increase of Energy Potential of Russian Forest resources due to Climate Change and CO

Biofuels are an important energy source, currently providing about 10% of the world energy demand, including 2% of global electricity generation and the same share of total liquid fuel consumption. Wood fuel in Russia is one of the most affordable and most important type of renewable energy resources. In this paper we study the possible changes in energy potential of Russia's forest resources as a result of changes in the atmosphere and climate. The estimates of the global dioxide concentrations dynamics and mean annual air temperature change over the Russian territory for the period up to 2050 are developed using the MPEI models of the carbon cycle and regional climate. The calculations show that the change of net primary productivity of forests of Russia as a result of the CO2 abundance increase in the atmosphere, as well as of the increase of the air temperature and rainfall will enhance available energy resources of wood fuel by mid-century by more than 9 million tons of coal equivalent (Mtce)

Effect of Cold Swaging on the Bulk Gradient Structure Formation and Mechanical Properties of a 316-Type Austenitic Stainless Steel

The present study aimed to discover the effect of cold swaging reduction on the bulk gradient structure formation and mechanical properties of a 316-type austenitic stainless steel. The initial rod was subjected to radial swaging until 20–95% reduction of initial rod diameter, at room temperature. According to finite element simulation, higher plastic strain was accumulated in the surface layer compared to the center region during swaging. Microstructural investigations revealed three-stage gradient structure formation in the center and edge regions of the deformed rod. Meanwhile, cold swaging resulted in the development of strong 111ǁBA, 001ǁBA, and weak 111ǁBA texture components in the center and edge, respectively. Significant tensile strengthening was observed after cold swaging. For instance, the yield strength (YS) increased from 820 MPa to 930 MPa after 40–80% reduction respectively, without the loss of ductility (δ–14%). This unique aspect of the mechanical behavior was attributed to the gradient structure of the cold swaged material and explained in detail

A Framework for Integrated Modeling of Perturbations in Atmospheres for Conjunction Tracking (IMPACT)

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140430/1/6.2014-1771.pd