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Nuclear Experiment (nucl-ex) updates on the arXiv.org e-print archive

Published: 2018-02-22T20:30:00-05:00

First Result on the Neutrinoless Double Beta Decay of $^{82}$Se with CUPID-0. (arXiv:1802.07791v1 [nucl-ex])

We report the result of the search for neutrinoless double beta decay of $^{82}$Se obtained with CUPID-0, the first large array of scintillating Zn$^{82}$Se cryogenic calorimeters implementing particle identification. We observe no signal in a 1.83 kg$\cdot$yr $^{82}$Se exposure and we set the most stringent lower limit on the \onu $^{82}$Se half-life T$^{0\nu}_{1/2}>$ 2.4$\cdot \mathrm{10}^{24}$ yr (90\% C.I.), which corresponds to an effective Majorana neutrino mass m$_{\beta\beta} <$ (376-770) meV depending on the nuclear matrix element calculations. The heat-light readout provides a powerful tool for the rejection of \al\ particles and allows to suppress the background in the region of interest down to (3.6$^{+1.9}_{-1.4}$)$\cdot$10$^{-3}$\ckky, an unprecedented level for this technique.

Work of a multi-cathode counter in a single electron counting mode. (arXiv:1802.07879v1 [physics.ins-det])

We describe a work of a multi-cathode counter of the developed design in a single electron counting mode with a cathode made of aluminum alloy. The results of the calibration of the counter are presented. The coefficient of gas amplification was found from the calibration spectra. The electric fields and operation of this detector in two configurations are described and the original idea to find the effect from electrons emitted from the surface of a cathode by difference of the rates measured in two volume configurations is expounded. Furthermore, the advantage of using a multi-cathode counter for measurement of the intensity of single electron emission from a metal is explained.

Searching for the rules that govern hadron construction. (arXiv:1802.08131v1 [hep-ph])

Just as Quantum Electrodynamics describes how electrons are bound in atoms by the electromagnetic force, mediated by exchange of photons, Quantum Chromodynamics (QCD) describes how quarks are bound inside hadrons by the strong force, mediated by exchange of gluons. At face value, QCD allows hadrons constructed from increasingly many quarks to exist, just as atoms with increasing numbers of electrons exist, yet such complex constructions seemed, until recently, to not be present in nature. In what follows we describe advances in the spectroscopy of mesons that are refining our understanding of the rules for building hadrons from QCD.

Results of the first user program on the Homogenous Thermal Neutron Source HOTNES (ENEA / INFN). (arXiv:1802.08132v1 [nucl-ex])

The HOmogeneous Thermal NEutron Source (HOTNES) is a new type of thermal neutron irradiation assembly developed by the ENEA-INFN collaboration. The facility is fully characterized in terms of neutron field and dosimetric quantities, by either computational and experimental methods. This paper reports the results of the first "HOTNES users program", carried out in 2016, and covering a variety of thermal neutron active detectors such as scintillators, solid-state, single crystal diamond and gaseous detectors.

$^4{\rm He}$ vs. $^4{\rm Li}$ and production of light nuclei in relativistic heavy-ion collisions. (arXiv:1802.08212v1 [nucl-th])

We propose to measure the yields of $^4{\rm He}$ and $^4{\rm Li}$ in relativistic heavy-ion collisions to clarify a mechanism of light nuclei production. Since the masses of $^4{\rm He}$ and $^4{\rm Li}$ are almost equal, the yield of $^4{\rm Li}$ predicted by the thermal model is 5 times bigger than that of $^4{\rm He}$ which reflects the different numbers of internal degrees of freedom of the two nuclides. Their internal structure is, however, very different: the alpha particle is well bound and compact while $^4{\rm Li}$ is weakly bound and loose. Within the coalescence model the ratio of yields of $^4{\rm Li}$ to $^4{\rm He}$ is shown to be significantly smaller than that in the thermal model and the ratio decreases fast from central to peripheral collisions of relativistic heavy-ion collisions because the coalescence rate strongly depends on the nucleon source radius.

Neutron stars exclude light dark baryons. (arXiv:1802.08244v1 [hep-ph])

Exotic new particles carrying baryon number and with mass of order the nucleon mass have been proposed for various reasons including baryogenesis, dark matter, mirror worlds, and the neutron lifetime puzzle. We show that the existence of neutron stars with mass greater than 0.7 $M_\odot$ places severe constraints on such particles, requiring them to be heavier than 1.2 GeV or to have strongly repulsive self-interactions.

A Search for deviations from the inverse square law of gravity at nm range using a pulsed neutron beam. (arXiv:1712.02984v2 [nucl-ex] UPDATED)

We describe an experimental search for deviations from the inverse square law of gravity at the nanometer length scale using neutron scattering from noble gases on a pulsed slow neutron beamline. By measuring the neutron momentum transfer ($q$) dependence of the differential cross section for xenon and helium and comparing to their well-known analytical forms, we place an upper bound on the strength of a new interaction as a function of interaction length $\lambda$ which improves upon previous results in the region $\lambda < 0.1\,$nm, and remains competitive in the larger $\lambda$ region. A pseudoexperimental simulation developed for this experiment and its role in the data analysis described. We conclude with plans for improving sensitivity in the larger $\lambda$ region.