Thu·Oct 22, 2015Thursday·October 22, 2015

1. 01*

   Concerning the variability of beta-decay measurements

   P.A. Sturrock🇺🇸 · E. Fischbach🇺🇸 · A. Parkhomov🇷🇺 · J.D. Scargle🇺🇸 · G. Steinitz🇮🇱

   Many experiments have been carried out to study the beta-decay rates of a variety of nuclides, and many - but not all - of these experiments yield evidence of variability of these rates. While there is as yet no accepted theory to explain patterns in the results, a number of conjectures have been proposed. We discuss three prominent conjectures (which are not mutually exclusive) - that variability of beta-decay rates may be due to (a) environmental influences, (b) solar neutrinos, and (c) cosmic neutrinos. We find evidence in support of each of these conjectures.

   nucl-exhep-ph11 citations
2. 02*

   Measurement of the absolute differential cross section of proton-proton elastic scattering at small angles

   D. Mchedlishvili🇬🇪 · D. Chiladze🇬🇪 · S. Dymov🇷🇺 · Z. Bagdasarian🇬🇪 · S. Barsov🇷🇺 · R. Gebel🇩🇪 · B. Gou🇨🇳 · M. Hartmann🇩🇪 · A. Kacharava🇩🇪 · I. Keshelashvili🇩🇪 · A. Khoukaz🇩🇪 · P. Kulessa🇵🇱 and 29 other authors

   The differential cross section for proton-proton elastic scattering has been measured at a beam energy of 1.0 GeV and in 200 MeV steps from 1.6 to 2.8 GeV for centre-of-mass angles in the range from 12-16 degrees to 25-30 degrees, depending on the energy. Absolute normalisations of typically 3% were achieved by studying the energy losses of the circulating beam of the COSY storage ring as it passed repeatedly through the windowless hydrogen target of the ANKE magnetic spectrometer. It is shown that the data have a significant impact upon a partial wave analysis. After extrapolating the differential cross sections to the forward direction, the results are broadly compatible with the predictions of forward dispersion relations.

   nucl-exnucl-thPLB(2016)·9 citations
3. 03*

   Nuclear Data Needs and Capabilities for Applications

   Lee Bernstein🇺🇸 · David Brown🇺🇸 · Aaron Hurst🇺🇸 · John Kelly🇺🇸 · Filip Kondev🇺🇸 · Elizabeth McCutchan🇺🇸 · Caroline Nesaraja🇺🇸 · Rachel Slaybaugh🇺🇸 · Alejandro Sonzogni🇺🇸

   The Workshop on Nuclear Data Needs and Capabilities for Applications (NDNCA) was held at Lawrence Berkeley National Laboratory (LBNL) on 27-29 May 2015. The goals of NDNCA were compile nuclear data needs across a wide spectrum of applied nuclear science, and to provide a summary of associated capabilities (accelerators, reactors, spectrometers, etc.) available for required measurements. This document represents the results of the workshop and a compilation of other recent documents assessing nuclear data needs for the above-mentioned applications.

   nucl-exphysics.ins-det10 citations
4. 04*

   Roy-Steiner-equation analysis of pion-nucleon scattering

   Martin Hoferichter🇺🇸 · Jacobo Ruiz de Elvira🇩🇪 · Bastian Kubis🇩🇪 · Ulf-G. Meißner🇩🇪

   We review the structure of Roy-Steiner equations for pion-nucleon scattering, the solution for the partial waves of the t-channel process $\pi \pi \to \bar{N}N$, as well as the high-accuracy extraction of the pion-nucleon S-wave scattering lengths from data on pionic hydrogen and deuterium. We then proceed to construct solutions for the lowest partial waves of the s-channel process $\pi N\to \pi N$ and demonstrate that accurate solutions can be found if the scattering lengths are imposed as constraints. Detailed error estimates of all input quantities in the solution procedure are performed and explicit parameterizations for the resulting low-energy phase shifts as well as results for subthreshold parameters and higher threshold parameters are presented. Furthermore, we discuss the extraction of the pion-nucleon $\sigma$-term via the Cheng-Dashen low-energy theorem, including the role of isospin-breaking corrections, to obtain a precision determination consistent with all constraints from analyticity, unitarity, crossing symmetry, and pionic-atom data. We perform the matching to chiral perturbation theory in the subthreshold region and detail the consequences for the chiral convergence of the threshold parameters and the nucleon mass.

   ↳ hep-phhep-latnucl-exnucl-thPhys.Rept.(2016)·324 citations
5. 05*

   An apparatus for studying electrical breakdown in liquid helium at 0.4 K and testing electrode materials for the SNS nEDM experiment

   T. M. Ito🇺🇸 · J. C. Ramsey🇺🇸 · W. Yao🇺🇸 · D. H. Beck🇺🇸 · V. Cianciolo🇺🇸 · S. M. Clayton🇺🇸 · C. Crawford🇺🇸 · S. A. Currie🇺🇸 · B. W. Filippone🇺🇸 · W. C. Griffith🇬🇧 · M. Makela · R. Schmid and 5 other authors

   We have constructed an apparatus to study DC electrical breakdown in liquid helium at temperatures as low as 0.4 K and at pressures between the saturated vapor pressure and $\sim$600 torr. The apparatus can house a set of electrodes that are 12 cm in diameter with a gap of $1-2$ cm between them, and a potential up to $\pm 50$ kV can be applied to each electrode. Initial results demonstrated that it is possible to apply fields exceeding 100 kV/cm in a 1 cm gap between two electropolished stainless steel electrodes 12 cm in diameter for a wide range of pressures at 0.4 K. We also measured the current between two electrodes. Our initial results, $I<1$ pA at 45 kV, correspond to a lower bound on the effective volume resistivity of LHe of ${\rho }_V>5\times 10^{18}$ $\Omega \cdot$cm. This lower bound is 5 times larger than the bound previously measured. We report the design, construction, and operational experience of the apparatus, as well as initial results.

   ↳ physics.ins-detnucl-exRev.Sci.Instrum.(2016)·29 citations
6. 06*

   Etaprime interactions with nucleons and nuclei

   Steven D. Bass🇦🇹 · Pawel Moskal🇵🇱

   We summarise recent progress in theory and experiment towards understanding etaprime meson interactions with nucleons and nuclei. Highlights include the production mechanism of etaprime mesons in proton-proton collisions close to threshold, the etaprime effective mass shift in nuclei and the determination of the etaprime-nucleon scattering length in free space.

   ↳ hep-phnucl-exnucl-thActa Phys.Polon.B(2016)·11 citations
7. 07*

   Watson's theorem and the $N\Delta (1232)$ axial transition

   L. Alvarez-Ruso🇪🇸 · E. Hernández🇪🇸 · J. Nieves🇪🇸 · M.J. Vicente Vacas🇪🇸

   We present a new determination of the $N\Delta$ axial form factors from neutrino induced pion production data. For this purpose, the model of Hernandez {\it et al.} [Phys. Rev. D76, 033005 (2007)] is improved by partially restoring unitarity. This is accomplished by imposing Watson's theorem on the dominant vector and axial multipoles. As a consequence, a larger $C_5^A(0)$, in good agreement with the prediction from the off-diagonal Goldberger-Treiman relation, is now obtained.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2016)·54 citations
8. 08*

   Measurements of effective delayed neutron fraction in a fast neutron reactor using the perturbation method

   Hao-Jun Zhou · Yan-Peng Yin · Xiao-Qiang Fan · Zheng-Hong Li · Yi-Kang Pu

   The perturbation method is proposed to obtain the effective delayed neutron fraction (\b{eta}eff) of a cylindrical highly enriched uranium reactor. Based on the reactivity measurements with and without a sample at a designable position using the positive periodic technique, the reactor reactivity perturbation {\Delta}h̊o} of the sample in \b{eta}eff units is measured. The simulation of the perturbation experiments are performed by MCNP program. The PERT card is used to provide the difference dk of effective neutron multiplication factors with and without the sample inside the reactor. Based on the relationship between the effective multiplication factor and the reactivity, the equation \b{eta}eff =dk/{\Delta}h̊o} is derived. In this paper, the reactivity perturbations of 13 metal samples at the designable position of the reactor are measured and calculated. The average \b{eta}eff value of the reactor is given as 0.00645, and the standard uncertainty is 3.0%. Additionally, the perturbation experiments for \b{eta}eff can be used to evaluate the reliabilities of the delayed neutron parameters. This work showed that the delayed neutron data of 235U and 238U from G.R.Keepin's publication are more reliable than those from ENDF-B6.0, ENDF-B7.0, JENDL3.3 and CENDL2.2.

   ↳ physics.ins-detnucl-exCPC(2016)·0 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.