Measurement of Conversion Coefficients in Normal and Triaxial Strongly Deformed Bands in \u3csup\u3e167\u3c/sup\u3eLu

Internal conversion coefficients have been measured for transitions in both normal deformed and triaxial strongly deformed bands in 167Lu using the Gammasphere and ICE Ball spectrometers. The results for all in-band transitions are consistent with E2 multipolarity. Upper limits are determined for the internal conversion coefficients for linking transitions between TSD Band 2 and TSD Band 1, the nw = 1 and nw = 0 wobbling bands, respectively

Breakdown of \u3cem\u3eK\u3c/em\u3e Selection in \u3csup\u3e178\u3c/sup\u3eHf

Coulomb activation of the four quasiparticle Kπ = 16+ 178Hf isomer (t 1/2 = 31 y) has led to the measurement of a set of Eλ matrix elements coupling the isomer band to the ground band. The present data combined with earlier 178Hf Coulomb excitation data have probed the K components in the wave functions and revealed the onset and saturation of K mixing in low-K bands, whereas the mixing is negligible in the high-K bands. The implications can be applied to other quadrupole-deformed nuclei

Spin Dependence of \u3cem\u3eK\u3c/em\u3e Mixing, Strong Configuration Mixing, and Electromagnetic Properties of \u3csup\u3e178\u3c/sup\u3eHf

The combined data of two Coulomb excitation experiments has verified the purely electromagnetic population of the Kπ = 4+, 6+, 8−, and 16+rotational bands in 178Hf via 2≤ν ≤14 K-forbidden transitions, quantifying the breakdown of the K-selection rule with increasing spin in the low-K bands. The γ -, 4+, and 6+bands were extended, and four new states in a rotational band were tentatively assigned to a previously known Kπ = 0+band. The quasiparticle structure of the 6+(t1/2= 77 ns) and 8−(t1/2= 4 s) isomer bands were evaluated, showing that the gyromagnetic ratios of the 6+ isomer band are consistent with a pure π 7/2+[404], π 5/2+[402] structure. The 8−isomer band at 1147 keV and the second 8−band at 1479 keV, thought to be predominantly ν 7/2-[514], ν 9/2+[624] and π 9/2-[514], π 7/2+[404], respectively, are mixed to a degree approaching the strongmixing limit. Based on measured (Kπ = 16+‖E2‖Kπ = 0+) matrix elements, it was shown that heavy-ion bombardment could depopulate the 16+isomer at the ∼1% level, although no states were found that would mediate photodeexcitation of the isomer via low-energy x-ray absorption

Angle-integrated measurements of the 26Al (d, n)27Si reaction cross section: a probe of spectroscopic factors and astrophysical resonance strengths

Measurements of angle-integrated cross sections to discrete states in 27Si have been performed studying the 26Al (d, n) reaction in inverse kinematics by tagging states by their characteristic $\gamma$ -decays using the GRETINA array. Transfer reaction theory has been applied to derive spectroscopic factors for strong single-particle states below the proton threshold, and astrophysical resonances in the 26Al (p,$\gamma$) 27Si reaction. Comparisons are made between predictions of the shell model and known characteristics of the resonances. Overall very good agreement is obtained, indicating this method can be used to make estimates of resonance strengths for key reactions currently largely unconstrained by experiment

Open data from the third observing run of LIGO, Virgo, KAGRA, and GEO

The global network of gravitational-wave observatories now includes five detectors, namely LIGO Hanford, LIGO Livingston, Virgo, KAGRA, and GEO 600. These detectors collected data during their third observing run, O3, composed of three phases: O3a starting in 2019 April and lasting six months, O3b starting in 2019 November and lasting five months, and O3GK starting in 2020 April and lasting two weeks. In this paper we describe these data and various other science products that can be freely accessed through the Gravitational Wave Open Science Center at https://gwosc.org. The main data set, consisting of the gravitational-wave strain time series that contains the astrophysical signals, is released together with supporting data useful for their analysis and documentation, tutorials, as well as analysis software packages

Search for eccentric black hole coalescences during the third observing run of LIGO and Virgo

Despite the growing number of binary black hole coalescences confidently observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include the effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that have already been identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total source-frame mass M > 70 M⊙) binaries covering eccentricities up to 0.3 at 15 Hz emitted gravitational-wave frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place a conservative upper limit for the merger rate density of high-mass binaries with eccentricities 0 < e ≤ 0.3 at 16.9 Gpc−3 yr−1 at the 90% confidence level

Search for collective and non-collective band structures in 123^{123}Xe

International audienceThe nuclei in the mass region A ≃125 lie between the spherical Sn nuclei(Z=50) and strongly deformed Ce nuclei(Z=58) and are therefore, transitional with respect to their shapes at low and high angular momenta. In this mass region, there exists a unique parity intruder orbital h11/2 which is accessible to both the protons and neutrons. These h11/2 nucleons have opposite deformation driving effects; neutrons drive the nucleus towards the oblate shape whereas the protons favour the prolate shape. Thus, the outcome of this interplay makes this region very interesting to study shape evolutions from lower to higher spins as the nucleus can have a prolate, an oblate or a triaxial shape depending on the alignment of the h11/2 nucleons[1]

Search for collective and non-collective band structures in 123^{123}Xe

International audienc

Effect of a Triaxial Nuclear Shape on Proton Tunneling: The Decay and Structure of 145Tm

Gamma rays deexciting states in the proton emitter Tm145 were observed using the recoil-decay tagging method. The Tm145 ground-state rotational band was found to exhibit the properties expected for an h11/2 proton decoupled band. In addition, coincidences between protons feeding the 2+ state in Er144 and the 2+→0+ γ-ray transition were detected, the first measurement of this kind, leading to a more precise value for the 2+ excitation energy of 329(1) keV. Calculations with the particle-rotor model and the core quasiparticle coupling model indicate that the properties of the πh11/2 band and the proton-decay rates in Tm145 are consistent with the presence of triaxiality with an asymmetry parameter γ≈20°

Structure changes in (160)Er from low to ultrahigh spin

A spectroscopic investigation of the gamma decays from excited states in Er-160 has been performed in order to study the changing structural properties exhibited from low spin up toward ultrahigh spin (I similar to 60 h). The nucleus Er-160 was populated by the reaction Cd-116(Ca-48,4n gamma) at a beam energy of 215 MeV, and resulting gamma decays were studied using the Gammasphere spectrometer. New rotational structures and extensions to existing bands were observed, revealing a diverse range of quasiparticle configurations, which are discussed in terms of the cranked shell model. At spins around 50h there is evidence for oblate states close to the yrast line. Three rotational bands that have the characteristics of strongly deformed triaxial structures are observed, marking a return to collectivity at even higher spin. The high-spin data are interpreted within the framework of cranked Nilsson-Strutinsky calculations