The preponderance of matter over antimatter in the early Universe, the dynamics of the supernova bursts that produced the heavy elements necessary for life and whether protons eventually decay -these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our Universe, its current state and its eventual fate. The Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed plan for a world-class experiment dedicated to addressing these questions.Experiments carried out over the past half century have revealed that neutrinos are found in three states, or flavors, and can transform from one flavor into another. These results indicate that each neutrino flavor state is a mixture of three different nonzero mass states, and to date offer the most compelling evidence for physics beyond the Standard Model. In a single experiment, LBNE will enable a broad exploration of the three-flavor model of neutrino physics with unprecedented detail. Chief among its potential discoveries is that of matter-antimatter asymmetries (through the mechanism of charge-parity violation) in neutrino flavor mixing -a step toward unraveling the mystery of matter generation in the early Universe. Independently, determination of the unknown neutrino mass ordering and precise measurement of neutrino mixing parameters by LBNE may reveal new fundamental symmetries of Nature.Grand Unified Theories, which attempt to describe the unification of the known forces, predict rates for proton decay that cover a range directly accessible with the next generation of large underground detectors such as LBNE's. The experiment's sensitivity to key proton decay channels will offer unique opportunities for the ground-breaking discovery of this phenomenon.Neutrinos emitted in the first few seconds of a core-collapse supernova carry with them the potential for great insight into the evolution of the Universe. LBNE's capability to collect and analyze this high-statistics neutrino signal from a supernova within our galaxy would provide a rare opportunity to peer inside a newly-formed neutron star and potentially witness the birth of a black hole.To achieve its goals, LBNE is conceived around three central components: (1) a new, highintensity neutrino source generated from a megawatt-class proton accelerator at Fermi National Accelerator Laboratory, (2) a fine-grained near neutrino detector installed just downstream of the source, and (3) a massive liquid argon time-projection chamber deployed as a far detector deep underground at the Sanford Underground Research Facility. This facility, located at the site of the former Homestake Mine in Lead, South Dakota, is ∼1,300 km from the neutrino source at Fermilab -a distance (baseline) that delivers optimal sensitivity to neutrino charge-parity symmetry violation and mass ordering effects. This ambitious yet cost-effective design incorporates scalability and flexibility and can accommodate a variety of upgrades and contributions.With its exceptional combi...
The NEMO collaboration is looking to measure neutrinoless double beta decay. The search for the effective neutrino mass will approach a lower limit of 0.1 eV. The NEMO 3 detector is now operating in the Frejus Underground Laboratory. The fundamental design of the detector is reviewed and the performances detailed. Finally, a summary of the data collected in the first runs which involve energy and time calibration and study of the background are presented.
The decay of excited states in the waiting-point nucleus 130 Cd 82 has been observed for the first time. An 8 two-quasiparticle isomer has been populated both in the fragmentation of a 136 Xe beam as well as in projectile fission of 238 U, making 130 Cd the most neutron-rich N 82 isotone for which information about excited states is available. The results, interpreted using state-of-the-art nuclear shell-model calculations, show no evidence of an N 82 shell quenching at Z 48. They allow us to follow nuclear isomerism throughout a full major neutron shell from 98 Cd 50 to 130 Cd 82 and reveal, in comparison with 76 Ni 48 one major proton shell below, an apparently abnormal scaling of nuclear two-body interactions. DOI: 10.1103/PhysRevLett.99.132501 PACS numbers: 21.60.Cs, 23.20.Lv, 26.30.+k, 27.60.+j The pioneering work of Goeppert-Mayer [1] and Haxel, Jensen, and Suess [2] in realizing that the experimental evidence for nuclear magic numbers could be explained by assuming a strong spin-orbit interaction constituted a major milestone in our understanding of the internal structure of the atomic nucleus. However, it has been recognized for more than 20 years that the single-particle ordering which underlies the shell structure (and with it the magic numbers) may change for nuclei approaching the neutron dripline. It has been argued that the neutron excess causes the central potential to become diffuse, leading to a modification of the single-particle spectrum of neutron-dripline nuclei [3,4]. In addition, a strong interaction between the energetically bound orbitals and the continuum also affects the level ordering. The consequence of these modifications can be a shell quenching; i.e., the shell gaps at magic neutron numbers are less pronounced in very neutronrich nuclei than in nuclei closer to stability. At the extreme, these gaps may even disappear. Alternatively, the tensor part of the nuclear force has been shown to cause shell reordering for very asymmetric proton and neutron numbers [5,6].The N 82 isotones below the doubly magic nucleus 132 Sn are crucial for stellar nucleosynthesis due to the close relation between the N 82 shell closure and the A 130 peak of the solar r-process abundance distribution. Based on the mass models available at that time, it was shown in the 1990s that the assumption of a quenching of the N 82 neutron shell closure leads to a considerable improvement in the global abundance fit in r-process calculations [7,8], in particular, a filling of the troughs around A 120 and 140. On the other hand, recently, alternative descriptions of the phenomenon have been given without invoking shell quenching at all [9,10]. Unfortunately, the very PRL 99,
In-beam ␥-ray spectroscopy using fragmentation reactions of both stable and radioactive beams has been performed in order to study the structure of excited states in neutron-rich oxygen isotopes with masses ranging from A = 20 to 24. For the produced fragments, ␥-ray energies, intensities, and ␥-␥ coincidences have been measured. Based on this information new level schemes are proposed for
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