Abstract
As COVID-19 outbreak enters its second phase of lockdown ease, healthcare plans involve elective surgery re-establishment to provide essential life-saving care. Patients are increasingly ...requesting information about their facility's readiness for safely performing surgery. This information should be open and transparent including patient's education with objective data regarding the state of the pandemic in the country and the control measures undertaken by the facility.
The electromagnetic form factors of the proton and neutron encode information on the spatial structure of their charge and magnetization distributions. While measurements of the proton are relatively ...straightforward, the lack of a free neutron target makes measurements of the neutron's electromagnetic structure more challenging and more sensitive to experimental or model-dependent uncertainties. Various experiments have attempted to extract the neutron form factors from scattering from the neutron in deuterium, with different techniques providing different, and sometimes large, systematic uncertainties. We present results from a novel measurement of the neutron magnetic form factor using quasielastic scattering from the mirror nuclei ^{3}H and ^{3}He, where the nuclear effects are larger than for deuterium but expected to largely cancel in the cross-section ratios. We extracted values of the neutron magnetic form factor for low-to-modest momentum transfer, 0.6<Q^{2}<2.9 GeV^{2}, where existing measurements give inconsistent results. The precision and Q^{2} range of these data allow for a better understanding of the current world's data and suggest a path toward further improvement of our overall understanding of the neutron's magnetic form factor.
When protons and neutrons (nucleons) are bound into atomic nuclei, they are close enough to feel significant attraction, or repulsion, from the strong, short-distance part of the nucleon-nucleon ...interaction. These strong interactions lead to hard collisions between nucleons, generating pairs of highly energetic nucleons referred to as short-range correlations (SRCs). SRCs are an important but relatively poorly understood part of nuclear structure1-3, and mapping out the strength and the isospin structure (neutron-proton (np) versus proton-proton (pp) pairs) of these virtual excitations is thus critical input for modelling a range of nuclear, particle and astrophysics measurements3-5. Two-nucleon knockout or 'triple coincidence' reactions have been used to measure the relative contribution of np-SRCs and pp-SRCs by knocking out a proton from the SRC and detecting its partner nucleon (proton or neutron). These measurements6-8 have shown that SRCs are almost exclusively np pairs, but they had limited statistics and required large model-dependent final-state interaction corrections. Here we report on measurements using inclusive scattering from the mirror nuclei hydrogen-3 and helium-3 to extract the np/pp ratio of SRCs in systems with a mass number of three. We obtain a measure of the np/pp SRC ratio that is an order of magnitude more precise than previous experiments, and find a marked deviation from the near-total np dominance observed in heavy nuclei. This result implies an unexpected structure in the high-momentum wavefunction for hydrogen-3 and helium-3. Understanding these results will improve our understanding of the short-range part of the nucleon-nucleon interaction.
Glycaspis brimblecombei Moore (Hemiptera: Aphalaridae) is an invasive psyllid introduced into the Mediterranean area, where it affects several species of Eucalyptus. Psyllaephagus bliteus Riek ...(Hymenoptera: Encyrtidae) is a specialized parasitoid of this psyllid that was accidentally introduced into Italy in 2011. We developed a model of this host–parasitoid system that accounts for the influence of environmental conditions on the G. brimblecombei population dynamics and P. bliteus parasitism rates in the natural ecosystem. The Lotka–Volterra-based model predicts non-constant host growth and parasitoid mortality rates in association with variation in environmental conditions. The model was tested by analyzing sampling data collected in Naples in 2011 (before the parasitoid was present) and defining several environmental patterns, termed Temperature-Rain or T-R patterns, which correspond to the host growth rate. A mean value of the host growth rate was assigned to each T-R pattern, as well as a variation of the parasitoid mortality rate based on temperature thresholds. The proposed model was applied in simulation tests related to T-R patterns carried out with a data series sampled between June 2014 and July 2015 in five Italian sites located in Campania, Lazio, Sicily, and Sardinia regions. The simulation results showed that the proposed model provides an accurate approximation of population trends, although oscillation details may not be apparent. Results predict a 64% reduction in G. brimblecombei population density owing to P. bliteus parasitoid activity. Our results are discussed with respect to features of the host–parasitoid interaction that could be exploited in future biological control programs.
The ICARUS T600 detector, with about 500 tons of active mass, is the largest Liquid Argon Time Projection Chamber (LAr TPC) ever realised. In 2013 ICARUS concluded an about 4 years long experiment ...with the T600 detector at the LNGS underground laboratory, taking data both with the CNGS neutrino beam and cosmic rays. This very successful experiment demonstrated the high spatial and energy resolutions, electron/photon separation and particle identification capabilities (via dE/dx vs range measurements) of the LAr technology. ICARUS Collaboration refurbished the T600 at CERN, in order to move it to FNAL in the framework of the SBN experiment, to serve as far detector in studies on the short baseline neutrino oscillations. A fundamental part of ICARUS is the light collection system, made of 360 Hamamatsu R5912-MOD, 8 in. diameter, PMT's. This system is dedicated to three tasks: the generation of a light based trigger signal, the identification of the time of occurrence (t0) of each interaction with high time precision and the initial recognition of event topology for fast event selection purposes.
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