Thu·Apr 23, 2015Thursday·April 23, 2015

1. 01*

   Total Absorption Spectroscopy Study of ${}^{92}$Rb Decay: A Major Contributor to Reactor Antineutrino Spectrum Shape

   A.-A. Zakari-Issoufou · M. Fallot · A. Porta · A. Algora · J.L. Tain · E. Valencia · S. Rice · V.M Bui · S. Cormon · M. Estienne · J. Agramunt · J. Äystö and 35 other authors

   The antineutrino spectra measured in recent experiments at reactors are inconsistent with calculations based on the conversion of integral beta spectra recorded at the ILL reactor. ${}^{92}$Rb makes the dominant contribution to the reactor spectrum in the 5-8 MeV range but its decay properties are in question. We have studied ${}^{92}$Rb decay with total absorption spectroscopy. Previously unobserved beta feeding was seen in the 4.5-5.5 region and the GS to GS feeding was found to be 87.5(25)%. The impact on the reactor antineutrino spectra calculated with the summation method is shown and discussed.

   nucl-exhep-exPRL(2015)·88 citations
2. 02*

   The Analog Front-end Prototype Electronics Designed for LHAASO WCDA

   Cong Ma🇨🇳 · Lei Zhao🇨🇳 · Yu-Xiang Guo🇨🇳 · Jian-Feng Liu🇨🇳 · Shu-Bin Liu🇨🇳 · Qi An🇨🇳

   In the readout electronics of the Water Cerenkov Detector Array (WCDA) in the Large High Altitude Air Shower Observatory (LHAASO) experiment, both high-resolution charge and time measurement are required over a dynamic range from 1 photoelectron (P.E.) to 4000 P.E. The Analog Front-end (AFE) circuit is one of the crucial parts in the whole readout electronics. We designed and optimized a prototype of the AFE through parameter calculation and circuit simulation, and conducted initial electronics tests on this prototype to evaluate its performance. Test results indicate that the charge resolution is better than 1% @ 4000 P.E. and remains better than 10% @ 1 P.E., and the time resolution is better than 0.5 ns RMS, which is better than application requirement.

   ↳ physics.ins-detnucl-exCPC(2016)·7 citations
3. 03*

   Standard Electroweak Interactions in Gravitational Theory with Chameleon Field and Torsion

   A. N. Ivanov🇦🇹 · M. Wellenzohn🇦🇹

   We propose a version of a gravitational theory with the torsion field, induced by the chameleon field. Following Hojman et al. Phys. Rev. D17, 3141 (1976) the results, obtained in Phys. Rev. D90, 045040 (2014), are generalised by extending the Einstein gravity to the Einstein-Cartan gravity with the torsion field as a gradient of the chameleon field through a modification of local gauge invariance of minimal coupling in the Weinberg-Salam electroweak model. The contributions of the chameleon (torsion) field to the observables of electromagnetic and weak processes are calculated. Since in our approach the chameleon-photon coupling constant beta_(gamma) is equal to the chameleon-matter coupling constant beta, i.e. beta_(gamma) = beta, the experimental constraints on beta, obtained in terrestrial laboratories by T. Jenke et al. (Phys. Rev. Lett. 112, 115105 (2014)) and by H. Lemmel et al. (Phys. Lett. B743, 310 (2015)), can be used for the analysis of astrophysical sources of chameleons, proposed by C. Burrage et al. (Phys. Rev. D79, 044028 (2009)), A.-Ch. Davis et al. (Phys. Rev. D80, 064016 (2009), and in references therein, where chameleons induce photons because of direct chameleon-photon transitions in the magnetic fields.

   ↳ gr-qchep-phnucl-exPRD(2015)·7 citations
4. 04*

   First detection of tracks of radon progeny recoils by MIMAC

   Q.Riffard (1) · D. Santos (1) · G. Bosson (1) · O. Bourrion (1) · T. Descombes (1) · C. Fourel (1) · O. Guillaudin (1) · J.-F. Muraz (1) · P. Colas (2) · E. Ferrer-Ribas (2) · I. Giomataris (2) · J. Busto (3) and 4 other authors

   The MIMAC experiment is a $\mu$-TPC matrix project for directional dark matter search. Directional detection is a strategy based on the measurement of the WIMP flux anisotropy due to the solar system motion with respect to the dark matter halo. The main purpose of MIMAC project is the measurement of the energy and the direction of nuclear recoils in 3D produced by elastic scattering of WIMPs. Since June 2012 a bi-chamber prototype is operating at the Modane underground laboratory. In this paper, we report the first ionization energy and 3D track observations of nuclear recoils produced by the radon progeny. This measurement shows the capability of the MIMAC detector and opens the possibility to explore the low energy recoil directionality signature.

   ↳ astro-ph.IMnucl-exphysics.ins-detJINST(2017)·29 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.