Fri·Aug 28, 2015Friday·August 28, 2015

1. 01*

   Study of B meson production in pPb collisions at sqrt(s_NN) = 5.02 TeV using exclusive hadronic decays

   CMS Collaboration

   The production cross sections of the B+, B0, and B0s mesons, and of their charge conjugates, are measured via exclusive hadronic decays in pPb collisions at the center-of-mass energy sqrt(s_NN) = 5.02 TeV with the CMS detector at the CERN LHC. The data set used for this analysis corresponds to an integrated luminosity of 34.6 inverse nanobarns. The production cross sections are measured in the transverse momentum range between 10 and 60 GeV/c. No significant modification is observed compared to proton-proton perturbative QCD calculations scaled by the number of incoherent nucleon-nucleon collisions. These results provide a baseline for the study of in-medium b quark energy loss in PbPb collisions.

   nucl-exhep-exPRL(2016)·89 citations
2. 02*

   On the proton charge extensions

   Jesse R. Stryker🇺🇸 · Gerald A. Miller🇺🇸

   We examine how corrections to $S$-state energy levels, $E_{nS}$, in hydrogenic atoms due to the finite proton size are affected by moments of the proton charge distribution. The corrections to $E_{nS}$ are computed moment by moment. The results demonstrate that the next-to-leading order term in the expansion is of order $r_p/a_B$ times the size of the leading order $⟨r_p^2⟩$ term. Our analysis thus dispels any concern that the larger relative size of this term for muonic hydrogen versus electronic hydrogen might account for the current discrepancy of proton radius measurements extracted from the two systems. Furthermore, the next-to-leading order term in powers of $r_p/a_B$ that we derive from a dipole proton form factor is proportional to $⟨r_p^3⟩$, rather than $⟨r_p^4⟩$ as would be expected from the scalar nature of the form factor. The dependence of the finite-size correction on $⟨r_p^3⟩$ and higher odd-power moments is shown to be a general result for any spherically symmetric proton charge distribution. A method for computing the moment expansion of the finite-size correction to arbitrary order is introduced and the results are tabulated for principal quantum numbers up to $n=7$.

   ↳ hep-phnucl-exnucl-thphysics.atom-phPRA(2016)·4 citations
3. 03*

   Improvements to TITAN's Mass Measurement and Decay Spectroscopy Capabilities

   D. Lascar · A.A. Kwiatkowski · M. Alanssari · U. Chowdhury · J. Even · A. Finlay · A.T. Gallant · M. Good · R. Klawitter · B. Kootte · T. Li K.G. Leach · A. Lennarz and 8 other authors

   The study of nuclei farther from the valley of $\beta$-stability goes hand-in-hand with shorter-lived nuclei produced in smaller abundances than their more stable counterparts. The measurement, to high precision, of nuclear masses therefore requires innovations in technique in order to keep up. TRIUMF's Ion Trap for Atomic and Nuclear science (TITAN) facility deploys three ion traps, with a fourth in the commissioning phase, to perform and support Penning trap mass spectrometry and in-trap decay spectroscopy on some of the shortest-lived nuclei ever studied. We report on recent advances and updates to the TITAN facility since the 2012 EMIS Conference. TITAN's charge breeding capabilities have been improved and in-trap decay spectroscopy can be performed in TITAN's electron beam ion trap (EBIT). Higher charge states can improve the precision of mass measurements, reduce the beam-time requirements for a given measurement, improve beam purity and opens the door to access, via in-trap decay and recapture, isotopes not available from the ISOL method. This was recently demonstrated during TITAN's mass measurement of ${}^{30}$Al. The EBIT's decay spectroscopy setup was commissioned with a successful branching ratio and half-life measurement of ${}^{124}$Cs. Charge breeding in the EBIT increases the energy spread of the ion bunch sent to the Penning trap for mass measurement so a new Cooler Penning Trap (CPET), which aims to cool highly charge ions with an electron plasma, is undergoing online commissioning. Already, CPET has demonstrated the trapping and self-cooling of a room-temperature electron plasma which was stored for several minutes. A new detector has been installed inside the CPET magnetic field which will allow for in-magnet charged particle detection.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.B(2016)·8 citations
4. 04*

   The excitation functions of 187Re(n,2n)186m,gRe Reactions

   Xiao-Long Huang🇨🇳 · Meng-Xiao Kang · Li-Le Liu🇨🇳 · Ji-Min Wang · Li-Yang Jiang🇨🇳 · Xiong-Jun Chen🇨🇳

   A new value for the emission probability of 137.144keV g-ray of 186gRe decay are re-recommended to be 9.47+-0.03 (%). From this new g-ray emission probability, the measured cross sections for 187Re(n,2n)186mRe and 187Re(n,2n)186gRe reactions around 14MeV are evaluated, and the total cross section for 187Re(n,2n)186m+gRe reaction at 14.8MeV is recommended to be 2213+-116 mb. The UNF code are adopted to calculate the total cross sections for 187Re(n,2n)186m+gRe reaction below 20 MeV fitting to the recommended value 2213+-116 mb at 14.8MeV using a set of optimum neutron optical potential parameters which obtained on the relevant experimental data of Re. Then the isomeric cross section ratios for 187Re(n,2n)186m,gRe reaction are calculated using the method of Monte Carlo calculations based on the nuclear statistical theory. Combining these two calculated results, the excitation functions for 187Re(n,2n)186mRe and 187Re(n,2n)186gRe reactions are obtained. The obtained results are in good agreement with the available experimental data, which indicates that present method is useful to deduce the isomeric cross sections for (n,2n) reaction.

   ↳ nucl-thnucl-exCPC(2016)·1 citation
5. 05*

   PALS investigations of free volumes thermal expansion of J-PET plastic scintillator synthesized in polystyrene matrix

   A. Wieczorek🇵🇱 · B. Zgardzińska🇵🇱 · B. Jasińska🇵🇱 · M. Gorgol🇵🇱 · T. Bednarski🇵🇱 · P. Białas🇵🇱 · E. Czerwiński🇵🇱 · A. Gajos🇵🇱 · D. Kamińska🇵🇱 · Ł. Kapłon🇵🇱 · A. Kochanowski🇵🇱 · G. Korcyl🇵🇱 and 16 other authors

   The polystyrene dopped with 2,5-diphenyloxazole as a primary fluor and 2-(4-styrylphenyl)benzoxazole as a wavelength shifter, prepared as a plastic scintillator was investigated using positronium probe in wide range of temperatures from 123 to 423 K. Three structural transitions at 260 K, 283 K and 370 K were found in the material. In the o-Ps intensity dependence on temperature, the significant hysteresis is observed. Heated to 370 K, the material exhibits the o-Ps intensity variations in time.

   ↳ physics.ins-detnucl-exNukleonika(2015)·8 citations
6. 06*

   Nuclear forces and their impact on neutron-rich nuclei and neutron-rich matter

   K. Hebeler🇩🇪 · J.D. Holt🇨🇦 · J. Menendez🇯🇵 · A. Schwenk🇩🇪

   We review the impact of nuclear forces on matter at neutron-rich extremes. Recent results have shown that neutron-rich nuclei become increasingly sensitive to three-nucleon forces, which are at the forefront of theoretical developments based on effective field theories of quantum chromodynamics. This includes the formation of shell structure, the spectroscopy of exotic nuclei, and the location of the neutron dripline. Nuclear forces also constrain the properties of neutron-rich matter, including the neutron skin, the symmetry energy, and the structure of neutron stars. We first review our understanding of three-nucleon forces and show how chiral effective field theory makes unique predictions for many-body forces. Then, we survey results with three-nucleon forces in neutron-rich oxygen and calcium isotopes and neutron-rich matter, which have been explored with a range of many-body methods. Three-nucleon forces therefore provide an exciting link between theoretical, experimental and observational nuclear physics frontiers.

   ↳ nucl-thnucl-exAnn.Rev.Nucl.Part.Sci.(2015)·259 citations
7. 07*

   How well do we understand Beryllium-7 + proton -> Boron-8 + photon? An Effective Field Theory perspective

   Xilin Zhang🇺🇸 · Kenneth M. Nollett🇺🇸 · D. R. Phillips🇺🇸

   We have studied the 7Be(p,photon)8B reaction in the Halo effective field theory (EFT) framework. The leading order (LO) results were published in Phys.Rev.C89,051602(2014) after the isospin mirror process, 7Li(n,photon)8Li, was addressed in Phys.Rev.C89,024613(2014). In both calculations, one key step was using the final shallow bound state asymptotic normalization coefficients (ANCs) computed by ab initio methods to fix the EFT couplings. Recently we have developed the next-to-LO (NLO) formalism (to appear soon), which could reproduce other model results by no worse than 1% when the 7Be-p energy was between 0 and 0.5 MeV. In our recent report (arXiv:1507.07239), a different approach from that in Phys.Rev.C89,051602(2014) was used. We applied Bayesian analysis to constrain all the NLO-EFT parameters based on measured S-factors, and found tight constraints on the S-factor at solar energies. Our S(E=0 MeV)= 21.3 + - 0.7 eV b. The uncertainty is half of that previously recommended. In this proceeding, we provide extra details of the Bayesian analysis, including the computed EFT parameters' probability distribution functions (PDFs) and how the choice of input data impacts final results.

   ↳ nucl-thastro-ph.SRnucl-exEPJ Web Conf.(2016)·7 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.