Tue·Apr 3, 2018Tuesday·April 3, 2018

1. 01*

   ${}^9$Be+${}^{120}$Sn scattering at near-barrier energies within a four body model

   A. Arazi · J. Casal🇮🇹 · M. Rodríguez-Gallardo🇪🇸 · J. M. Arias🇪🇸 · R. Lichtenthäler Filho · D. Abriola🇦🇷 · O. A. Capurro · M. A. Cardona · P. F. F. Carnelli · E. de Barbará🇦🇷 · J. Fernández Niello · J. M. Figueira🇦🇷 and 5 other authors

   Cross sections for elastic and inelastic scattering of the weakly-bound ${}^9$Be nucleus on a ${}^{120}$Sn target have been measured at seven bombarding energies around and above the Coulomb barrier. The elastic angular distributions are analyzed with a four-body continuum-discretized coupled-channels (CDCC) calculation, which considers ${}^9$Be as a three-body projectile ($\alpha$ + $\alpha$ + n). An optical model analysis using the São Paulo potential is also shown for comparison. The CDCC analysis shows that the coupling to the continuum part of the spectrum is important for the agreement with experimental data even at energies around the Coulomb barrier, suggesting that breakup is an important process at low energies. At the highest incident energies, two inelastic peaks are observed at 1.19(5) and 2.41(5) MeV. Coupled-channels (CC) calculations using a rotational model confirm that the first inelastic peak corresponds to the excitation of the 2${}_1^{+}$ state in ${}^{120}$Sn, while the second one likely corresponds to the excitation of the 3${}_1^{-}$ state.

   nucl-exnucl-thPRC(2018)·30 citations
2. 02*

   Excitation of ${}^{229}$Th nuclei in laser plasma: the energy and half-life of the low-lying isomeric state

   P.V. Borisyuk · E.V. Chubunova · N.N. Kolachevsky · Yu.Yu. Lebedinskii · O.S. Vasiliev · E.V. Tkalya

   The results of experimental studies of the low-energy isomeric state in the ${}^{229}$Th nucleus are presented. The work is consisted of several stages. During the first stage ${}^{229}$Th nuclei were excited with the inverse internal conversion to the low-lying isomeric level in plasma that was formed by laser pulse at the ${}^{229}$Th-containing target surface. Then thorium ions having excited nuclei were extracted from the plasma by an external electrical field and implanted into thin SiO${}_2$ film grown on a silicon substrate (that is a dielectric material with about 9 eV band-gap). Gamma decay of isomeric nuclei was registered during the second stage by the general methods of the electron spectroscopy after the photon-electron emission from the silicon substrate. Substitution of the photon registration with the electron one allowed us to increase the desired signal by several orders of magnitude and detect the ${}^{229}$Th nuclei decay. During the third stage the electron spectra from standard Xe VUV source was obtained that allowed determining the energy of photons. In order to prove that the detected signal is caused by isomeric ${}^{229}$Th nuclei decay a series of experiments was carried. The analysis of electron spectra gives the following results: the energy of the nuclear transition is $E_{\text{is}}=7.1{(}_{-0.2}^{+0.1})$~eV, the half-life of the isomeric level in bare nucleus in vacuum is $T_{1/2}=1880\pm 170$~s, the reduced probability of the isomeric nuclear transition is $B_{\text{W.u.}}(M1;3/2^{+}\to 5/2^{+})=(3.3\pm 0.3)\times 10^{-2}$.

   ↳ nucl-thnucl-exphysics.opticsphysics.plasm-ph12 citations
3. 03*

   Medium-induced gluon emission via transverse and longitudinal scattering in dense nuclear matter

   Le Zhang🇨🇳 · De-Fu Hou🇨🇳 · Guang-You Qin🇨🇳

   We study the medium-induced gluon emission from a hard quark jet traversing the dense nuclear matter within the framework of deep inelastic scattering off a large nucleus. We extend the previous work and compute the single gluon emission spectrum including both transverse and longitudinal momentum exchanges between the hard jet parton and the medium constituents. On the other hand, with only transverse scattering and using static scattering centers for the traversed medium, our induced gluon emission spectrum in the soft gluon limit reduces to the Gyulassy-Levai-Vitev one-rescattering-one-emission formula.

   ↳ nucl-thhep-phnucl-exPRC(2018)·9 citations
4. 04*

   Measurement of radon-induced backgrounds in the NEXT double beta decay experiment

   NEXT Collaboration: P. Novella🇪🇸 · B. Palmeiro🇪🇸 · A. Simón🇪🇸 · M. Sorel🇪🇸 · C. Adams🇺🇸 · P. Ferrario🇪🇸 · G. Martínez-Lema🇪🇸 · F. Monrabal🇺🇸 · G. Zuzel🇵🇱 · J.J. Gómez-Cadenas🇪🇸 · V. Álvarez🇪🇸 · L. Arazi🇮🇱 and 69 other authors

   The measurement of the internal ${}^{222}$Rn activity in the NEXT-White detector during the so-called Run-II period with ${}^{136}$Xe-depleted xenon is discussed in detail, together with its implications for double beta decay searches in NEXT. The activity is measured through the alpha production rate induced in the fiducial volume by ${}^{222}$Rn and its alpha-emitting progeny. The specific activity is measured to be $(38.1\pm 2.2(stat.)\pm 5.9(syst.))$~mBq/m${}^3$. Radon-induced electrons have also been characterized from the decay of the ${}^{214}$Bi daughter ions plating out on the cathode of the time projection chamber. From our studies, we conclude that radon-induced backgrounds are sufficiently low to enable a successful NEXT-100 physics program, as the projected rate contribution should not exceed 0.1~counts/yr in the neutrinoless double beta decay sample.

   ↳ physics.ins-dethep-exnucl-exJHEP(2018)·42 citations
5. 05*

   Event patterns from negative pion spectra in proton-proton and nucleus-nucleus collisions at SPS

   Ya-Hui Chen🇨🇳 · Fu-Hu Liu🇨🇳 · Edward K. Sarkisyan-Grinbaum🇨🇭

   Rapidity-dependent transverse momentum spectra of negatively charged pions measured at different rapidities in proton-proton collisions at the Super Proton Synchrotron (SPS) at various energies within its Beam Energy Scan (BES) program are investigated by using one- and two-component standard distributions where the chemical potential and spin property of particles are implemented. The rapidity spectra are described by a double-Gaussian distribution. At the stage of kinetic freeze-out, the event patterns are structured by the scatter plots in the three-dimensional subspaces of velocity, momentum and rapidity. The results of the studies of the rapidity-independent transverse mass spectra measured at mid-rapidity in proton-proton collisions are compared with those based on the similar transverse mass spectra measured in the most central beryllium-beryllium, argon-scandium and lead-lead collisions from the SPS at its BES energies.

   ↳ nucl-thhep-exhep-phnucl-exCPC(2018)·4 citations
6. 06*

   Mobility and Clustering of Barium Ions and Dications in High Pressure Xenon Gas

   E. Bainglass🇺🇸 · B.J.P. Jones🇺🇸 · F. W. Foss Jr🇺🇸 · M. N. Huda🇺🇸 · D. R. Nygren🇺🇸

   The clustering and drift properties of barium ions in xenon gas are explored theoretically, using density functional theory and computational ion mobility theory, with the goal of better understanding barium ion transport for neutrinoless double beta decay. We derive the equilibrium conformations, energies and entropies of molecular ions in the Ba${}^{+}$-Xe and Ba${}^{++}$-Xe systems, which yield a predictive model of cluster formation in high pressure gas. We calculate ion-neutral interaction potential curves for these species and use them to predict effective molecular ion mobilities. Our calculation consistently reproduces experimental data on effective mobility and molecular ion formation for the Ba${}^{+}$ system, and predicts strong cluster formation in the Ba${}^{++}$ system, dominated by stable [BaXe${}_6$]${}^{++}$,[BaXe${}_7$]${}^{++}$, [BaXe${}_8$]${}^{++}$ and [BaXe${}_9$]${}^{++}$ complexes in the range of interest. Some implications for barium tagging in gas-phase neutrinoless double beta decay experiments are discussed, and the first predictions of pressure-dependent mobility of the doubly charged Ba${}^{++}$ species are presented.

   ↳ physics.ins-dethep-exnucl-exphysics.chem-phPRA(2018)·19 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.