Die Messung von Gamow-Teller- und Fermi-Übergangsstärken im Massenbereich von A = 26 bis 178 und Extraktion von Kernmatrixelementen für den doppelten Beta-Zerfall

In dieser Arbeit werden Experimente mit Ladungsaustauschreaktionen beschrieben, analysiert und ausgewertet. Gegenstand der Untersuchungen sind Kerne, die u.a. im Hinblick auf die Neutrinophysik von Interesse sind. Die Experimente ermöglichen einen detaillierteren Einblick in die Kernstruktur einfacher und doppelter Beta-Zerfallskerne als bisherige Untersuchungen. Die Experimente wurden am Research Center for Nuclear Physics der Osaka Universität, Japan durchgeführt. Es werden die Ergebnisse für die Analyse des Galliums vorgestellt und deren Auswirkungen auf die Neutrinoexperimente GALLEX und SAGE diskutiert. Vor dem Hintergrund des doppelten Beta-Zerfalls werden die Ergebnisse der Untersuchungen an Isotopen Ge-76, Se-82, Zr-96 und Mo-100 vorgestellt und diskutiert. Im weiteren werden die Analysen der Isotope im Massenbereich von A=26 bis 178 erläutert, die dem Verständnis des Zusammenhangs zwischen Beta-Zerfall und Ladungsaustauschreaktionen dienen

The Chiral Magnetic Effect and Axial Anomalies

We give an elementary derivation of the chiral magnetic effect based on a strong magnetic field lowest-Landau-level projection in conjunction with the well-known axial anomalies in two- and four-dimensional space-time. The argument is general, based on a Schur decomposition of the Dirac operator. In the dimensionally reduced theory, the chiral magnetic effect is directly related to the relativistic form of the Peierls instability, leading to a spiral form of the condensate, the chiral magnetic spiral. We then discuss the competition between spin projection, due to a strong magnetic field, and chirality projection, due to an instanton, for light fermions in QCD and QED. The resulting asymmetric distortion of the zero modes and near-zero modes is another aspect of the chiral magnetic effect.Comment: 33 pages, 5 figures, to appear in Lect. Notes Phys. "Strongly interacting matter in magnetic fields" (Springer), edited by D. Kharzeev, K. Landsteiner, A. Schmitt, H.-U. Ye

Search for gravitational waves from Scorpius X-1 in the second Advanced LIGO observing run with an improved hidden Markov model

We present results from a semicoherent search for continuous gravitational waves from the low-mass x-ray binary Scorpius X-1, using a hidden Markov model (HMM) to track spin wandering. This search improves on previous HMM-based searches of LIGO data by using an improved frequency domain matched filter, the J-statistic, and by analyzing data from Advanced LIGO's second observing run. In the frequency range searched, from 60 to 650 Hz, we find no evidence of gravitational radiation. At 194.6 Hz, the most sensitive search frequency, we report an upper limit on gravitational wave strain (at 95% confidence) of h095%=3.47×10-25 when marginalizing over source inclination angle. This is the most sensitive search for Scorpius X-1, to date, that is specifically designed to be robust in the presence of spin wandering. © 2019 American Physical Society

Search for Tensor, Vector, and Scalar Polarizations in the Stochastic Gravitational-Wave Background

The detection of gravitational waves with Advanced LIGO and Advanced Virgo has enabled novel tests of general relativity, including direct study of the polarization of gravitational waves. While general relativity allows for only two tensor gravitational-wave polarizations, general metric theories can additionally predict two vector and two scalar polarizations. The polarization of gravitational waves is encoded in the spectral shape of the stochastic gravitational-wave background, formed by the superposition of cosmological and individually unresolved astrophysical sources. Using data recorded by Advanced LIGO during its first observing run, we search for a stochastic background of generically polarized gravitational waves. We find no evidence for a background of any polarization, and place the first direct bounds on the contributions of vector and scalar polarizations to the stochastic background. Under log-uniform priors for the energy in each polarization, we limit the energy densities of tensor, vector, and scalar modes at 95% credibility to Ω0T<5.58×10-8, Ω0V<6.35×10-8, and Ω0S<1.08×10-7 at a reference frequency f0=25 Hz. © 2018 American Physical Society

On the progenitor of binary neutron star merger GW170817

On 2017 August 17 the merger of two compact objects with masses consistent with two neutron stars was discovered through gravitational-wave (GW170817), gamma-ray (GRB 170817A), and optical (SSS17a/AT 2017gfo) observations. The optical source was associated with the early-type galaxy NGC 4993 at a distance of just ∼40 Mpc, consistent with the gravitational-wave measurement, and the merger was localized to be at a projected distance of ∼2 kpc away from the galaxy's center. We use this minimal set of facts and the mass posteriors of the two neutron stars to derive the first constraints on the progenitor of GW170817 at the time of the second supernova (SN). We generate simulated progenitor populations and follow the three-dimensional kinematic evolution from binary neutron star (BNS) birth to the merger time, accounting for pre-SN galactic motion, for considerably different input distributions of the progenitor mass, pre-SN semimajor axis, and SN-kick velocity. Though not considerably tight, we find these constraints to be comparable to those for Galactic BNS progenitors. The derived constraints are very strongly influenced by the requirement of keeping the binary bound after the second SN and having the merger occur relatively close to the center of the galaxy. These constraints are insensitive to the galaxy's star formation history, provided the stellar populations are older than 1 Gyr

Synthesis method for crystalline hollow titania micron-cubes

We report the synthesis of novel micron-sized titania cubes comprising a hematite core and a titania shell. Single core particles are entirely coated with a homogeneous titania shell of tunable thickness. Our convenient and straightforward synthesis method is mediated by the surfactant cetyltrimethylammonium bromide (CTAB) and proceeds under ambient conditions. Subsequent calcination transforms the amorphous titania shell to anatase/rutile titania; dissolution of the hematite core eventually results in hollow porous titania cubes. The resulting core–shell and hollow titania cubes display the tendency to align face-to-face, indicating their potential for utilization in close-packed arrays

Synthesis method for crystalline hollow titania micron-cubes

We report the synthesis of novel micron-sized titania cubes comprising a hematite core and a titania shell. Single core particles are entirely coated with a homogeneous titania shell of tunable thickness. Our convenient and straightforward synthesis method is mediated by the surfactant cetyltrimethylammonium bromide (CTAB) and proceeds under ambient conditions. Subsequent calcination transforms the amorphous titania shell to anatase/rutile titania; dissolution of the hematite core eventually results in hollow porous titania cubes. The resulting core–shell and hollow titania cubes display the tendency to align face-to-face, indicating their potential for utilization in close-packed arrays

Studies on the double-β\beta decay nucleus 64Zn^{64}Zn using the (d,2He^{2}He) reaction

The (d,2He) charge-exchange reaction on the double-beta decay (beta beta) nucleus 64Zn has been studied at an incident energy of 183 MeV. The two protons in the 1S0 state (indicated as 2He) were both momentum analyzed and detected simultaneously by the BBS magnetic spectrometer and its position-sensitive detector. 2He spectra with a resolution of about 115 keV (FWHM) have been obtained allowing identification of many levels in the residual nucleus 64Cu with high precision. 64Zn is one of the rare cases undergoing a beta beta decay in beta+ direction. In the experiment presented here, Gamow-Teller (GT+) transition strengths have been extracted. Together with the GT- transition strengths from 64Ni(3He,t) data to the same intermediate nucleus 64Cu, the nuclear matrix elements of the beta beta decay of 64Zn have been evaluated. Finally, the GT± distributions are compared with shell-model calculations and a critical assessment is given of the various residual interactions presently employed for the pf shel