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Nuclear Data Sheets for A=170☆

Nuclear structure data pertaining to all nuclei with mass number A=170 have been evaluated, and incorporated into the ENSDF data file. This evaluation supersedes the previous evaluation (Coral M. Baglin), Nuclear Data Sheets 96, 611 (2002), (cutoff date 15 August 2002) and subsequent updates of the ENSDF file for Yb to Dy (cutoff 15 April 2010), Lu (cutoff 8 October 1998), Pt (cutoff 17 February 1999) and Ta, Os (cutoff 7 April 1998). Since the previous evaluation, {sup 170}Gd has been observed and the ground state T{sub 1/2} measured. New excited states have also been observed in the neutron rich {sup 170}Dy. The ground state T{sub 1/2} of {sup 170}Tb has been determined, however, there are currently still no excited states observed in this nucleus. There remains some uncertainty in the ground state and longer-lived isomer in {sup 170}Ir which could warrent further experimental investigation.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Structural and physical properties of the new intermetallic compound Yb{sub 3}Pd{sub 2}Sn{sub 2}

The crystal structure of the ternary intermetallic compound Yb{sub 3}Pd{sub 2}Sn{sub 2} has been determined ab initio from powder X-ray diffraction data. The compound crystallizes as a new structure type in the orthorhombic space group Pbcm and lattice constants a=0.58262(3), b=1.68393(8), c=1.38735(7) nm. Yb{sub 3}Pd{sub 2}Sn{sub 2} is composed of a complex {sub {infinity}}[Pd{sub 2}Sn{sub 2}]{sup {delta}-} polyanionic network in which the Yb ions are embedded. A comparison between this structure and those of Eu{sub 3}Pd{sub 2}Sn{sub 2} and Ca{sub 3}Pd{sub 2}Sn{sub 2}, other novel polar intermetallic compounds, was made. DC susceptibility and {sup 170}Yb Moessbauer spectroscopic measurements indicate a close-to divalent Yb behavior. Moreover, a hybridization between 4f and conduction electrons is suggested by electronic structure calculations and heat capacity measurements. - Graphical Abstract: Polyanionic networks for Yb{sub 3}Pd{sub 2}Sn{sub 2} and Eu{sub 3}Pd{sub 2}Sn{sub 2}. Highlights: > We determined ab initio the crystal structure of the novel ternary Yb{sub 3}Pd{sub 2}Sn{sub 2} stannide. > This structure has been compared with those of other polar 3:2:2 stannides discovered in this work. > Measurements of physical properties on Yb{sub 3}Pd{sub 2}Sn{sub 2} point to a close-to-divalent Yb ion. > Electron structure calculation and heat capacity indicate some hybridization between 4f and conduction electrons.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Investigation of the neutron activation of endohedral rare earth metallofullerenes

Endohedral lanthanide metallofullerenes and their water-soluble biocompatible derivatives have been synthesized. The effect that fast-neutron irradiation has on the stability and nuclear physical properties of endohedral metallofullerenes that are used as magnetocontrast materials ({sup 46}Sc, {sup 140}La, {sup 141}Nd, {sup 153}Sm, {sup 152}Eu, {sup 154}Eu, {sup 153}Sm, {sup 160}Tb, {sup 169}Yb, {sup 170}Tm (isomers I and III), and {sup 177}Lu) is studied. Our hypothesis, according to which carbon-shell relaxation is based on the fast nonradiative processes of an electron shake-off type, is confirmed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Photoassociative production of ultracold heteronuclear ytterbium molecules

We report observations of photoassociation (PA) spectra near the intercombination line in isotopic mixtures of ultracold ytterbium gases. Several heteronuclear bound states have been found for the excited {sup 170}Yb{sup 174}Yb and {sup 174}Yb{sup 176}Yb molecules. We develop a single-channel mass-scaled interaction model for the excited state molecule which well reproduces the measured bound state energies. This is an important step toward optical control of interactions in mixtures of ultracold ytterbium gases using heteronuclear optical Feshbach resonances. The model developed is applicable in collisions of other similar systems, such as cadmium and mercury.

74 ATOMIC AND MOLECULAR PHYSICS↗

Probing New Bosons and Nuclear Structure with Ytterbium Isotope Shifts

In this Letter, we present mass-ratio measurements on highly charged Yb 42+ ions with a precision of 4 ×10 -12 and isotope-shift measurements on Yb + on the 2 S 1/2 → 2 D 5/2 and 2 S 1/2 → 2 F 7/2 transitions with a precision of 4 ×10 -9 for the isotopes 168,170,172,174,176 Yb. We present a new method that allows us to extract higher-order changes in the nuclear charge distribution along the Yb isotope chain, benchmarking ab initio nuclear structure calculations. Additionally, we perform a King plot analysis to set bounds on a fifth force in the keV/c 2 to MeV/c 2 range coupling to electrons and neutrons.

74 ATOMIC AND MOLECULAR PHYSICS↗

Search for rare alpha and double beta decays of Yb isotopes to excited levels of daughter nuclei

A search for alpha and double beta decays of ytterbium isotopes was performed with an ultra low-background high purity germanium detector at Gran Sasso Underground Laboratory (Italy). A 194.7 g Yb 2 (C 2 O 4 ) 3 powder sample was measured for 11.3 days with a total Yb exposure of 1.25 kg×day. Half-life limits for α-decay modes of 168 Yb, 170 Yb, 171 Yb, 172 Yb, 173 Yb, 174 Yb and 176 Yb into the first excited states have been obtained between 6 × 10 14 years and 2 × 10 16 years. These are the first experimental constraints of these decay modes. Double electron capture of 168 Yb and double beta decay of 176 Yb into the first excited 2 + and 0 + states could be excluded with limits between 1 × 10 14 years to 8 × 10 16 years. This improves the experimental information on some of the decay modes compared to previous constraints.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗