Fri·Feb 26, 2016Friday·February 26, 2016

1. 01*

   Muon Flux Measurements at the Davis Campus of the Sanford Underground Research Facility with the Majorana Demonstrator Veto System

   N. Abgrall🇺🇸 · E. Aguayo🇺🇸 · F.T. Avignone III🇺🇸 · A.S. Barabash🇷🇺 · F.E. Bertrand🇺🇸 · A.W. Bradley🇺🇸 · V. Brudanin🇷🇺 · M. Busch🇺🇸 · M. Buuck🇺🇸 · D. Byram🇺🇸 · A.S. Caldwell🇺🇸 · Y-D. Chan🇺🇸 and 62 other authors

   We report the first measurement of the total MUON flux underground at the Davis Campus of the Sanford Underground Research Facility at the 4850 ft level. Measurements were done with the Majorana Demonstrator veto system arranged in two different configurations. The measured total flux is (5.31+/-0.17) x 10^-9 muons/s/cm^2.

   nucl-exhep-exphysics.ins-detAstropart.Phys.(2017)·59 citations
2. 02*

   Unexpectedly large charge radii of neutron-rich calcium isotopes

   R.F. Garcia Ruiz🇧🇪 · M. L. Bissell🇧🇪 · K. Blaum🇩🇪 · A. Ekstrom🇺🇸 · N. Frommgen🇩🇪 · G. Hagen🇺🇸 · M. Hammen🇩🇪 · K. Hebeler🇩🇪 · J.D. Holt🇨🇦 · G.R. Jansen🇺🇸 · M. Kowalska🇨🇭 · K. Kreim🇩🇪 and 10 other authors

   Despite being a complex many-body system, the atomic nucleus exhibits simple structures for certain "magic" numbers of protons and neutrons. The calcium chain in particular is both unique and puzzling: evidence of doubly-magic features are known in 40,48Ca, and recently suggested in two radioactive isotopes, 52,54Ca. Although many properties of experimentally known Ca isotopes have been successfully described by nuclear theory, it is still a challenge to predict their charge radii evolution. Here we present the first measurements of the charge radii of 49,51,52Ca, obtained from laser spectroscopy experiments at ISOLDE, CERN. The experimental results are complemented by state-of-the-art theoretical calculations. The large and unexpected increase of the size of the neutron-rich calcium isotopes beyond N = 28 challenges the doubly-magic nature of 52Ca and opens new intriguing questions on the evolution of nuclear sizes away from stability, which are of importance for our understanding of neutron-rich atomic nuclei.

   nucl-exnucl-thNat.Phys.(2016)·365 citations
3. 03*

   A physical zero-knowledge object-comparison system for nuclear warhead verification

   Sébastien Philippe · Robert J. Goldston · Alexander Glaser · Francesco d'Errico

   Zero-knowledge proofs are mathematical cryptographic methods to demonstrate the validity of a claim while providing no further information beyond the claim itself. The possibility of using such proofs to process classified and other sensitive physical data has attracted attention, especially in the field of nuclear arms control. Here we demonstrate a non-electronic fast neutron differential radiography technique using superheated emulsion detectors that can confirm that two objects are identical without revealing their geometry or composition. Such a technique could form the basis of a verification system that could confirm the authenticity of nuclear weapons without sharing any secret design information. More broadly, by demonstrating a physical zero-knowledge proof that can compare physical properties of objects, this experiment opens the door to developing other such secure proof-systems for other applications.

   ↳ physics.ins-detnucl-exphysics.soc-phNature Commun.(2016)·6 citations
4. 04*

   Investigating multi-channel quantum tunneling in heavy-ion fusion reactions with Bayesian spectral deconvolution

   K. Hagino🇯🇵

   Excitations of colliding nuclei during a nuclear reaction considerably affect fusion cross sections at energies around the Coulomb barrier. It has been demonstrated that such channel coupling effects can be represented in terms of a distribution of multiple fusion barriers. We here apply a Bayesian approach to analyze the so called fusion barrier distributions. This method determines simultaneously the barrier parameters and the number of barriers. We particularly investigate the ${}^{16}$O+${}^{144}$Sm and ${}^{16}$O+${}^{154}$Sm systems in order to demonstrate the effectiveness of the method. The present analysis indicates that the fusion barrier distribution for the former system is most consistent with three fusion barriers, even though the experimental data show only two distinct peaks.

   ↳ nucl-thnucl-exphysics.data-anPRC(2016)·8 citations
5. 05*

   Large-scale shell-model analysis of the neutrinoless $\beta \beta$ decay of ${}^{48}$Ca

   Y. Iwata🇯🇵 · N. Shimizu🇯🇵 · T. Otsuka🇯🇵 · Y. Utsuno🇯🇵 · J. Menendez🇯🇵 · M. Honma🇯🇵 · T. Abe🇯🇵

   We present the nuclear matrix element for the neutrinoless double-beta decay of ${}^{48}$Ca based on large-scale shell-model calculations including two harmonic oscillator shells ($sd$ and $pf$ shells). The excitation spectra of ${}^{48}$Ca and ${}^{48}$Ti, and the two-neutrino double-beta decay of ${}^{48}$Ca are reproduced in good agreement to experiment. We find that the neutrinoless double-beta decay nuclear matrix element is enhanced by about 30\% compared to $pf$-shell calculations. This reduces the decay lifetime by almost a factor of two. The matrix-element increase is mostly due to pairing correlations associated with cross-shell $sd$-$pf$ excitations. We also investigate possible implications for heavier neutrinoless double-beta decay candidates.

   ↳ nucl-thhep-exhep-phnucl-exPRL(2016)·108 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.