Fri·Sep 28, 2018Friday·September 28, 2018

1. 01*

   Sensitivity study for the ${}^{12}$C($\alpha ,\gamma$)${}^{16}$O astrophysical reaction rate

   R. J. Holt🇺🇸 · B. W. Filippone🇺🇸 · Steven C. Pieper🇺🇸

   The ${}^{12}$C($\alpha ,\gamma$)${}^{16}$O reaction has a key role in nuclear astrophysics. A multilevel R-matrix analysis was used to make extrapolations of the astrophysical S factor for this reaction to the stellar energy of 300 keV. The statistical precision of the S-factor extrapolation was determined by performing multiple fits to existing randomized E1 and E2 ground state data, according to experimental errors. The impact of a future proposed experiment at Jefferson Laboratory (JLab) was assessed within this framework. The proposed JLab experiment will make use of a high-intensity low-energy bremsstrahlung beam that impinges on an oxygen-rich single-fluid bubble chamber in order to measure the total cross section for the inverse ${}^{16}$O($\gamma ,\alpha$)${}^{12}$C reaction. The importance of low energy data as well as high precision data was investigated.

   nucl-ex7 citations
2. 02*

   Production cross section and decay study of ${}^{243}$Es and ${}^{249}$Md

   R. Briselet (1)🇫🇷 · Ch. Theisen (1)🇫🇷 · M. Vandebrouck (1)🇫🇷 · A. Marchix (1)🇫🇷 · M. Airiau (1)🇫🇷 · K. Auranen (2)🇫🇮 · H. Badran (2)🇫🇮 · D. Boilley (3 and 4)🇫🇷 · T. Calverley (2 and 5)🇫🇮 · D. Cox (2 and 5)🇫🇮 · F. Déchery (1 and 6)🇫🇷 · F. Defranchi Bisso (2)🇫🇮 and 33 other authors

   In the study of the odd-$Z$, even-$N$ nuclei ${}^{243}$Es and ${}^{249}$Md, performed at the University of Jyväskylä, the fusion-evaporation reactions ${}^{197}$Au(${}^{48}$Ca,2$n$)${}^{243}$Es and ${}^{203}$Tl(${}^{48}$Ca,2$n$)${}^{249}$Md have been used for the first time. Fusion-evaporation residues were selected and detected using the RITU gas-filled separator coupled with the focal-plane spectrometer GREAT. For ${}^{243}$Es, the recoil decay correlation analysis yielded a half-life of $24\pm 3$s, and a maximum production cross section of $37\pm 10$ nb. In the same way, a half-life of $26\pm 1$ s, an $\alpha$ branching ratio of 75 $\pm$ 5%, and a maximum production cross section of 300 $\pm$ 80 nb were determined for ${}^{249}$Md. The decay properties of ${}^{245}$Es, the daughter of ${}^{249}$Md, were also measured: an $\alpha$ branching ratio of 54 $\pm$ 7% and a half-life of 65 $\pm$ 6 s. Experimental cross sections were compared to the results of calculations performed using the KEWPIE2 statistical fusion-evaporation code.

   nucl-exPRC(2019)·14 citations
3. 03*

   Measurements of Fourier harmonics of azimuthal anisotropy in Pb+Pb and Xe+Xe collisions

   Klaudia Burka🇵🇱

   The high-statistics data sets collected by the LHC experiments during the heavy-ion runs allow for a detailed study of the azimuthal anisotropy of charged particles. This report presents the selected results of $v_n$ measured in Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV and Xe+Xe collisions at $\sqrt{s_{\mathrm{NN}}}=5.44$ TeV, with emphasis on the higher order Fourier coefficients, $v_n$, sensitive to initial state fluctuations of the medium created in ultra-relativistic heavy-ion collisions.

   nucl-exhep-ex0 citations
4. 04*

   Towards TUCAN's Search for the Neutron Electric Dipole Moment

   Wolfgang Schreyer · TUCAN collaboration

   The TRIUMF ultracold advanced neutron (TUCAN) collaboration is a transpacific collaboration with the objective to measure the neutron electric dipole moment. We aim for an unprecedented sensitivity of $10^{-27}e$cm, an improvement by a factor of 30 over the current upper limit for this elusive quantity. To achieve this goal, we are planning a next-generation source for ultracold neutrons, based on a new, dedicated neutron spallation source at TRIUMF, liquid deuterium as cold moderator, and superfluid helium as ultracold-neutron converter. To operate at the full beam power of 20kW, a ${}^3$He fridge will provide a cooling power of 10W at 0.8K, cooling the converter to a temperature of 1.1K.

   ↳ physics.ins-detnucl-ex1 citation
5. 05*

   Manifestation of important role of nuclear forces in emission of photons in scattering of pions off nuclei

   Sergei P. Maydanyuk (1 and 2)🇨🇳 · Peng-Ming Zhang (1)🇨🇳 · Li-Ping Zou (1) ((1) Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China, (2) Institute for Nuclear Research, National Academy of Sciences of Ukraine, Ukraine)🇨🇳

   Bremsstrahlung of photons emitted during the scattering of ${\pi }^{+}$-mesons off nuclei is studied for the first time. Role of interactions between ${\pi }^{+}$-mesons and nuclei in the formation of the bremsstrahlung emission is analyzed in details. We discover essential contribution of emitted photons from nuclear part of Johnson-Satchler potential to the full spectrum, in contrast to the optical Woods-Saxon potential. We observe unusual essential influence of the nuclear part of both potentials on the spectrum at high photon energies. This phenomenon opens a new experimental way to study and check non-Coulomb and nuclear interactions between pions and nuclei via measurements of the emitted photons. We provide predictions of the bremsstrahlung spectra for pion scattering off ${}^{44}\mathrm{Ca}$.

   ↳ nucl-thhep-phnucl-exPRC(2018)·11 citations
6. 06*

   Conditional recovery of time-reversal symmetry in many nucleus systems

   Yoritaka Iwata🇯🇵 · Paul Stevenson🇬🇧

   Propagation of non-topological soliton in many-nucleus systems is studied based on time-dependent density functional calculations with focusing on mass and energy dependence. The dispersive property and the nonlinearity of the system, which are inherently included in the nuclear density functional, are essential factors to form a non-topological soliton. On the other hand the soliton propagation is prevented by the charge equilibration dynamics, and the competition possibly appears. In this article, based on the energy-dependence of the two competitive factors, the concept of conditional recovery of time-reversal symmetry is proposed in many nucleus systems. It clarifies a possibility of preserving nuclear medium inside natural or artificial nuclear reactors, under a suitable temperature. From an astrophysical point of view, the existence of the low-temperature solitonic core of compact stars is suggested.

   ↳ nlin.PSastro-ph.HEnucl-exnucl-thNew J.Phys.(2019)·5 citations
7. 07*

   Light-Neutrino Exchange and Long-Distance Contributions to $0\nu 2\beta$ Decays: An Exploratory Study on $\pi \pi \to ee$

   Xu Feng🇨🇳 · Lu-Chang Jin🇺🇸 · Xin-Yu Tuo🇨🇳 · Shi-Cheng Xia🇨🇳

   We present an exploratory lattice QCD calculation of the neutrinoless double beta decay $\pi \pi \to ee$. Under the mechanism of light-neutrino exchange, the decay amplitude involves significant long-distance contributions. The calculation reported here, with pion masses $m_{\pi }=420$ and 140 MeV, demonstrates that the decay amplitude can be computed from first principles using lattice methods. At unphysical and physical pion masses, we obtain that amplitudes are $24\%$ and $9\%$ smaller than the predication from leading order chiral perturbation theory. Our findings provide the lattice QCD inputs and constraints for effective field theory. A follow-on calculation with fully controlled systematic errors will be possible with adequate computational resources.

   ↳ hep-lathep-phnucl-exnucl-thPRL(2019)·48 citations
8. 08*

   The KATRIN Neutrino Mass Measurement: Experiment, Status, and Outlook

   Gregg B. Franklin🇺🇸

   The Karlsruhe Tritium Neutrino (KATRIN) experiment will provide a measurement of the effective electron-neutrino mass, $m({\nu }_e)$, based on a precision measurement of the tritium beta decay spectrum near its endpoint. The effective mass is an average of the neutrino mass eigenvalues $m_i$ weighted by the flavor-mass mixing parameters $U_{ei}$ according to the relation $m^2({\nu }_e)={\sum }_{i=1}^3|U_{ei}{|}^2{m}_i^2$. The KATRIN apparatus uses a windowless gaseous tritium source (WGTS) and a spectrometer based on the MAC-E filter concept to measure the beta energy spectrum. The KATRIN program is designed to reach a mass sensitivity of 0.2~eV (90\% C.L.). The collaboration has completed a series of commissioning measurements and is moving into the first running of tritium. The KATRIN measurement technique, early commissioning results, and the future outlook will be presented.

   ↳ physics.ins-dethep-exnucl-ex6 citations
9. 09*

   Quantum decay law: Critical times and the Equivalence of approaches

   D. F. Ramírez Jiménez🇨🇴 · N. G. Kelkar🇨🇴

   Methods based on the use of Green's functions or the Jost functions and the Fock-Krylov method are apparently very different approaches to understand the time evolution of unstable states. We show that the two former methods are equivalent up to some constants and as an outcome find an analytic expression for the energy density of states in the Fock-Krylov amplitude in terms of the coefficients introduced in the Green's functions and the Jost functions methods. This model-independent density is further used to obtain an analytical expression for the survival amplitude and study its behaviour at large times. Using these expressions, we investigate the origin of the oscillatory behaviour of the decay law in the region of the transition from the exponential to the non-exponential at large times. With the objective to understand the failure of nuclear and particle physics experiments in observing the non-exponential decay law predicted by quantum mechanics for large times, we derive analytical formulae for the critical transition time, $t_c$, from the exponential to the inverse power law behaviour at large times. Evaluating ${\tau }_c=\Gamma t_c$ for some particle resonances and narrow nuclear states which have been tested experimentally to verify the exponential decay law, we conclude that the large time power law in particle and nuclear decay is hard to find experimentally.

   ↳ quant-phhep-phnucl-exnucl-thJ.Phys.A(2019)·17 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.