2,442 research outputs found
A search for neutrino-antineutrino mass inequality by means of sterile neutrino oscillometry
The investigation of the oscillation pattern induced by the sterile neutrinos
might determine the oscillation parameters, and at the same time, allow to
probe CPT symmetry in the leptonic sector through neutrino-antineutrino mass
inequality. We propose to use a large scintillation detector like JUNO or LENA
to detect electron neutrinos and electron antineutrinos from MCi electron
capture or beta decay sources. Our calculations indicate that such an
experiment is realistic and could be performed in parallel to the current
research plans for JUNO and RENO. Requiring at least 5 confidence level
and assuming the values of the oscillation parameters indicated by the current
global fit, we would be able to detect neutrino-antineutrino mass inequality of
the order of 0.5% or larger, which would imply a signal of CPT anomalies.Comment: 14 pages, 10 figure
Nuclear States with Abnormal Radii
The radius of a nuclear state is one of the most important its characteristics. Presently there were developed some methods exploiting special features of the nuclear reactions leading to short â lived excited states and allowing determination of their radii. Evidence of existing nuclear excited states with enhanced radii (size isomers) was obtained
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South Atlantic Variability Arising from AirâSea Coupling: Local Mechanisms and TropicalâSubtropical Interactions
Interannual variability in the southern and equatorial Atlantic is investigated using an atmospheric general circulation model (AGCM) coupled to a slab ocean model (SOM) in the Atlantic in order to isolate features of airâsea interactions particular to this basin. Simulated covariability between sea surface temperatures (SSTs) and atmosphere is very similar to the observed non-ENSO-related covariations in both spatial structures and time scales. The leading simulated empirical coupled mode resembles the zonal mode in the tropical Atlantic, despite the lack of ocean dynamics, and is associated with baroclinic atmospheric anomalies in the Tropics and a Rossby wave train extending to the extratropics, suggesting an atmospheric response to tropical SST forcing. The second non-ENSO mode is the subtropical dipole in the SST with a mainly equivalent barotropic atmospheric anomaly centered on the subtropical high and associated with a midlatitude wave train, consistent with atmospheric forcing of the subtropical SST. The power spectrum of the tropical mode in both simulation and observation is red with two major interannual peaks near 5 and 2 yr. The quasi-biennial component exhibits a progression between the subtropics and the Tropics. It is phase locked to the seasonal cycle and owes its existence to the imbalances between SSTâevaporation and SSTâshortwave radiation feedbacks. These feedbacks are found to be reversed between the western and eastern South Atlantic, associated with the dominant role of deep convection in the west and that of shallow clouds in the east. A correct representation of tropicalâextratropical interactions and of deep and shallow clouds may thus be crucial to the simulation of realistic interannual variability in the southern and tropical Atlantic
Production of <sup>235</sup>Np, <sup>236</sup>Pu and <sup>237</sup>Pu via nuclear reactions on <sup>235,236,238</sup>U and <sup>237</sup>Np targets
A summary of methods for cyclotron production of 235Np (396.1d), 236Pu (2.858y) and 237Pu (45.2d) via nuclear reactions with protons and 3He-ions on 235,236,238U and 237Np targets in wide energy ranges is given. Methods for the chemical separation and purification of these nuclides from the irradiated uranium and neptunium targets are described. Cross sections, yields and radionuclidic purities of 235Np, 236Pu and 237Pu are presented and compared with literature data on the nuclear reactions leading to these radionuclides. The nuclear reactions with the so far highest known yields of 235Np, 236Pu and 237Pu are determined: 236U(p, 2n)235Np, 237Np(p, 2n + pnβ-)236Pu and 237Np(p, n) 237Pu, respectively. The highest radionuclidic purity of 235Np, 236Pu and 237Pu tracers can be reached with the 236U(p, 2n)235Np, 236U(p, nβ -)236Pu and 237Np(3He, t) 237Pu reactions, respectively. In addition new cross sections and yield data of the 236U(3He, p3n)235Np reaction in the energy range 42.4-60 MeV are given.</p
Production of a C-15 radioactive ion beam based on O-18(n, alpha)
.In the context of the SPIRAL2 radioactive beam facility the production rate of the neutron-rich C-15 nucleus by O-18(n,) has been investigated. In a water target of 20 cm(3), enriched in O-18 and placed behind the neutron converter, a rate of a few 10(10) nuclei per second can be reached with 1mA of 40MeV deuterons. A O-18(n,) cross-section based on the activation method is proposed. It is intermediate between the highest and lowest evaluations available to date.Peer reviewe
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