Yb Isotopes Research Articles

Compact structures for single-beam magneto-optical trapping of ytterbium.

At present, the best optical lattice clocks are based on the spectroscopy of trapped alkaline-earth-like atoms such as ytterbium and strontium. The development of mobile or even space-borne clocks necessitates concepts for the compact laser-cooling and trapping of these atoms with reduced laser requirements. Here, we present two compact and robust achromatic mirror structures for single-beam magneto-optical trapping of alkaline-earth-like atoms using two widely separated optical cooling frequencies. We have compared the trapping and cooling performance of a monolithic aluminum structure that generates a conventional trap geometry to a quasi-planar platform based on a periodic mirror structure for different isotopes of Yb. Compared to prior work with strontium in non-conventional traps, where only bosons were trapped on a narrow line transition, we demonstrate two-stage cooling and trapping of a fermionic alkaline-earth-like isotope in a single-beam quasi-planar structure.

Fabrication and characterization of highly enriched thin 176Yb targets for the reaction dynamic studies on fission mass distribution

The fabrication, transfer, and storage of a highly enriched isotopic target is very much crucial because of air gases and moistures being chemically active at room temperature. One must limit the amount of time that the target surface is exposed to the atmosphere during the transfer of air sensitive targets. The highly interactive targets are not easy to store for longer time and demand an in-vacuum transfer facility. Getting an alternative technique to remove all such imperative is a need of the hour specially for the nuclear physics community, more particularly for reaction dynamic studies of fission fragment mass distribution induced by stable and radioactive ion beams. Highly enriched materials are rare and very expensive, so an effective and highly efficient technique is needed to deal with such materials. Here, an attempt has been made to fabricate 96.63% enriched thin targets of 176Yb by evaporation techniques enabling ≈129.1 μg/cm2 thickness with a ≈25.93 μg/cm2 carbon backing to increase its stability and durability. Numerous trials have been performed using natural Yb to optimize the evaporation setup and associated growth parameters for efficient Yb isotope deposition with thin film deposition unit and diffusion pump based coating unit at Inter University Accelerator Centre (IUAC), New Delhi. Thickness and elemental composition of the targets have been analysed using characterization techniques such as X-ray diffraction, α-energy loss technique, Rutherford backscattering spectroscopy and energy dispersive X-ray spectroscopy. Essentially no significant impurities are found by these measurements, describing high purity and robustness of the fabricated targets. During the nuclear experiments, 30Si and 16O beams of intensity of the order of ≈1010 particles per second were bombarded on the targets for 5–6 days and no ill effects on the target were observed. Isotopic abundance of the target has been obtained experimentally, which ensured the isotopic purity of the target required for the reaction studies. This article will admire our readers about the qualitative nature of the fabrication technique, measurement and characterization citing valuable insights, aiding in a comprehensive understanding of their quality.

Theoretical analysis of shape transition and axial asymmetry in even-even Yb isotopes

Theoretical analysis of shape transition and axial asymmetry in even-even Yb isotopes

Gamma spectroscopy of even-even Ytterbium isotopes

The even-even Ytterbium isotopes lack spectroscopic information with the increase of the neutron number and they are well deformed nuclei, presenting rotational properties. In this mass region of the nuclear chart predictions have shown rare phenomena related to nuclear structure, such as shape coexistence. In this work the population of excited states were investigated in the even-even Yb isotopes via the 2n-transfer reaction 168-174Yb (18O, 16O) 170-176Yb. The measurements were carried out at the 9 MV Tandem accelerator at the Horia Hulubei National Institute of Physics and Nuclear Engineering (IFIN-HH) in Romania. The deduced gamma-ray angular distributions in the ground state bands are found to correspond with transitions, as expected

Nuclear Structure Investigations in Yb isotopes

The medium-to-heavy mass ytterbium isotopes (70Yb) in the rare-earth mass region are known to be well-deformed nuclei, which can be populated to very high spin, and are predicted to exhibit interesting phenomena, such as shape coexistence. The lack of any experimental information on the structure of the neutron-rich 180Yb isotope and the lifetime of the 21+ state of 178Yb have greatly motivated this study, which can offer useful information for the collective behavior of neutrons and protons in neutron-rich Yb isotopes. A measurement was performed to investigate the population of excited states and a first measurement of the unknown 21+ lifetime of 178Yb by means of a two neutron-transfer reaction 176Yb(18O,16O)178Yb at energies 68-74 MeV using the ROSPHERE array at IFIN-HH, Romania.

Suppression of spectral interference in dual-elemental analysis of single particles using triple quadrupole ICP-MS

Single particle-inductively coupled plasma-mass spectrometry (SP-ICP-MS) was used in the analysis of single particles/cells. Although quadrupole mass analyzers are widely used, the long settling time restricts measurement to single elements in individual particles. Recently, dual-elemental analysis has successfully been developed with the assistance of oxygen gas in the collision cell. This simple approach greatly expands the capability of quadrupole-based ICP-MS.In this study, we adopted bandpass mode in the first quadrupole (Q1) to improve the limit of detection of single particles against spectral interference. A model was developed to explain the rationale behind the selection of quadrupole voltages. The quadrupole voltages were optimized systematically so that the mass bandwidth of Q1 allowed the transmission of two target analytes while the interference species were rejected. As a result, the signal from the polyatomic interference was reduced by 98% with no significant change in the analyte signal.The bandpass mode was further applied to accurately determine the isotope ratio of 109Ag/107Ag in 80-nm Ag nanoparticles, as well as the Ag content in AgSn alloy particles, under the polyatomic interference of 91Zr16O originating from dissolved ions and particles. This technique was further applied to the determination of two Yb isotopes in algal cells with interference from Gd. Results indicate that this approach has great potential for assessing single particles and biological cells in the presence of severe interference from imaging agents, drugs, or biological fluids.

Doppler-dependent fluorescence spectroscopy of Yb atomic gas for trapped-ion experiments

An ion trap-based Quantum system has been one of the leading architectures toward building a scalable and practical quantum computer. The trapped ion system also has been used for precision experiments such as quantum sensing, metrology, and atomic clock. For the ion-trap experiment, searching resonant frequencies of atomic isotopes are essential for selectively ionization and trapping a specific isotope. In this work, we set up an Yb fluorescence spectroscopy for detecting 399 nm photons of 1S0 → 1P1 transition of the Yb gas from a heated oven. We observed the relative frequency differences between the Yb isotopes and calibrated an optical wavemeter comparing with previous literatures. In addition, we obtain characteristic properties of the atomic oven such as gas’ velocity and density distribution at different oven temperatures. Our experiment can offer a relatively simple and cost-efficient apparatus of spectroscopy and can be useful for designing trap devices in the trapped-ion experiment.

Statistical correlations of nuclear quadrupole deformations and charge radii

Shape deformations and charge radii, basic properties of atomic nuclei, are influenced by both the global features of the nuclear force and the nucleonic shell structure. As functions of proton and neutron number, both quantities show regular patterns and, for nuclei away from magic numbers, they change very smoothly from nucleus to nucleus. In this paper, we explain how the local shell effects are impacting the statistical correlations between quadrupole deformations and charge radii in well-deformed even-even Er, Yb, and Hf isotopes. This implies, in turn, that sudden changes in correlations can be useful indicators of underlying shell effects. Our theoretical analysis is performed in the framework of self-consistent mean-field theory using quantified energy density functionals and density-dependent pairing forces. The statistical analysis is carried out by means of the linear least-square regression. The local variations of nuclear quadrupole deformations and charge radii, explained in terms of occupations individual deformed Hartree-Fock orbits, make and imprint on statistical correlations of computed observables. While the calculated deformations or charge radii are, in some cases, correlated with those of their even-even neighbors, the correlations seem to deteriorate rapidly with particle number. The statistical correlations between nuclear deformations and charge radii of different nuclei are affected by the underlying shell structure. Even for well deformed and superfluid nuclei for which these observables change smoothly, the correlation range usually does not exceed $\Delta N=4$ and $\Delta Z=4$, i.e., it is rather short. This result suggests that the frequently made assumption of reduced statistical errors for the differences between smoothly-varying observables cannot be generally justified.

Determination of the Isotopic Composition of Ytterbium by MC-ICP-MS Using an Optimized Regression Model.

In this study, we measure the absolute isotope ratios of ytterbium (Yb) by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) using an optimized regression model for mass bias correction. A rhenium (Re) reference material (NIST SRM 3143), which has been characterized previously, is selected as a primary calibrator to calibrate the absolute Yb isotope ratios for three Yb materials (GSB, Alfa Yb, and GBW). The three-isotope plot for all collected data indicates that the results of Yb isotope ratios obtained are not affected by any polyatomic interferences and the mass-independent isotopic fractionation. Furthermore, the recalibrated Hf historical isotope ratios by using the absolute Yb isotopic composition obtained in this study for the isobaric interference correction on Hf isotopes are in agreement with the original historical values. This work has further demonstrated the applicability of the regression model for the calibrated measurements of absolute isotope ratios using MC-ICP-MS. The three mono-elemental Yb standard solutions are thus proposed as the reference materials for Yb isotope ratio measurements in environmental and geoscience applications.

Observation of Nonlinearity of Generalized King Plot in the Search for New Boson

We measure isotope shifts for neutral Yb isotopes on an ultranarrow optical clock transition S10−P03 with an accuracy of a few hertz. Combined with one of the recently reported isotope-shift measurements of Yb+ on two optical transitions, the result allows us to construct the King plots—a set of scaled isotope shifts data on two different optical transitions plotted in two-dimensional plane. When only the leading-order terms of isotope shifts are taken into account, a King plot should exhibit a linear relation as a result of elimination of the leading nuclear-size dependence. Extremely large nonlinearity unexplainable by a quadratic field shift is revealed, which was proposed previously as a source of the observed nonlinearity of the King plot. We further construct the generalized King plot with three optical transitions so that we can eliminate the contribution arising from a higher-order effect within the standard model. Our analysis of the generalized King plot shows a deviation from linearity at the 3σ level, indicating that there exist at least two higher-order contributions in the measured isotope shifts. Under reasonable assumptions, we obtain the upper bound of the product of the couplings for a new boson, mediating a force between electrons and neutrons—|yeyn|/(ℏc)<1×10−10 for the mass less than 1 keV—with the 95% confidence level, providing an important step toward probing new physics via isotope-shift spectroscopy.2 MoreReceived 18 October 2021Accepted 16 March 2022DOI:https://doi.org/10.1103/PhysRevX.12.021033Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasElectronic structure of atoms & moleculesElectronic transitionsHypothetical particle physics modelsNuclear charge distributionPhysical SystemsAtomsHypothetical particlesTechniquesPrecision measurementsSpectroscopyAtomic, Molecular & OpticalParticles & Fields

Работы по ядерной спектроскопий выполненные с участием Монгольских Сотрудников в ЛЯП

Decay schemes of 150-157Er and 148-161Ho have been studied. β-, γ-, X-rays and conversion electrons were investigated and ten new isotopes and isomeric states were identified at the first time. Endpoint energies of β*-spectrum were measured using an intrinsic germanium detector, and Qec values have been obtained. A group of proton emitters of Au, Ir, Re and Ta have been identified, and the proton drip line was determined. Anisotropics of the gamma rays in well deformed Yb isotopes have been measured from the decay of radioactive Lu oriented at at low temperature. Multipole mixing ratio of the hundreds transitions have been deduced, about 170 of them uniquely and unambiguous spin assignments were made for 30 levels. External perturbations of two 171Yb levels have been observed.&#x0D; Study of the decay for 112-118In isotopes were the first nuclear physics experimental work in Mongolia. Mini-orange β*-spectrometer was constracted in Dubna for the inner conversion electrons measurements for neutron deficit nuclides. Measured conversion coclTicicnts were used for determination the transition mullipolaritics. A specific method for efficiency calibration of mini-orange spectrometer was applied using the continuous β* -spectrum of 90Sr in energy range from 500 to 2200 keV.

A study of some aspects of the nuclear structure in the even–even Yb isotopes

A study of some aspects of the nuclear structure in the even–even Yb isotopes

Precision Determination of Isotope Shifts in Ytterbium and Implications for New Physics.

We report measurements of isotope shifts for the five spinless Yb isotopes on the 6s^{2} ^{1}S_{0}→5d6s ^{1}D_{2} transition using Doppler-free two-photon spectroscopy. We combine these data with existing measurements on two transitions in Yb^{+} [Counts etal. Phys. Rev. Lett. 125, 123002 (2020)PRLTAO0031-900710.1103/PhysRevLett.125.123002], where deviation from King-plot linearity showed hints of a new bosonic force carrier at the 3σ level. The combined data strongly reduce the significance of the new-physics signal. We show that the observed nonlinearity in the joint Yb/Yb^{+} King-plot analysis can be accounted for by the deformation of the Yb nuclei.

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_2O_4)_3 powder sample was measured for 11.3 days with a total Yb exposure of 1.25 kgtimes day. Half-life limits for alpha -decay modes of ^{168}mathrm Yb, ^{170}mathrm Yb, ^{171}mathrm Yb, ^{172}mathrm Yb, ^{173}mathrm Yb, ^{174}mathrm Yb and ^{176}mathrm Yb into the first excited states have been obtained between 6times 10^{14} years and 2times 10^{16} years. These are the first experimental constraints of these decay modes. Double electron capture of ^{168}mathrm Yb and double beta decay of ^{176}mathrm Yb into the first excited 2^+ and 0^+ states could be excluded with limits between 1times 10^{14} years to 8times 10^{16} years. This improves the experimental information on some of the decay modes compared to previous constraints.

Isotope selective three-step photoionization of 176Yb

Atomic vapor laser isotope separation of 176 Y b has been investigated through the density matrix analysis of laser–atom interactions in a three-step photoionization process. For the first time, to our knowledge, the method has been applied for both odd and even isotopes of Yb. The effects of peak power densities of the lasers, bandwidth of the excitation lasers, angular divergence, and number density of the atoms on the degree of enrichment have been studied. Peak power densities of the first, second, and third excitation lasers of 20, 20, and 40 , 000 W / c m 2 , respectively, and full angle divergence of the atomic beam of 120° were found to be optimum for the isotope separation of 176 Y b . The effects of resonant charge exchange collisions and atomic number densities on the degree of enrichment and production rates have also been studied. It has also been observed that the atomic number densities in the laser–atom interaction region should be limited to 1 × 1 0 12 a t o m s / c m 3 to obtain ∼ 90 % degree of enrichment of the 176 Y b isotope. At higher number densities of 1 × 1 0 13 a t o m s / c m 3 , the degree of enrichment decreases to 43.9%. The optimum range of bandwidths of excitation lasers is found be 90–120 MHz. At optimum conditions, the computed production rate of 22 mg/h is in good agreement with the previously reported value of 20 mg/h.

Mass Measurements of Neutron-Deficient Yb Isotopes and Nuclear Structure at the Extreme Proton-Rich Side of the N=82 Shell.

High-accuracy mass measurements of neutron-deficient Yb isotopes have been performed at TRIUMF using TITAN's multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS). For the first time, an MR-TOF-MS was used on line simultaneously as an isobar separator and as a mass spectrometer, extending the measurements to two isotopes further away from stability than otherwise possible. The ground state masses of ^{150,153}Yb and the excitation energy of ^{151}Yb^{m} were measured for the first time. As a result, the persistence of the N=82 shell with almost unmodified shell gap energies is established up to the proton drip line. Furthermore, the puzzling systematics of the h_{11/2}-excited isomeric states of the N=81 isotones are unraveled using state-of-the-art mean field calculations.

Isotope shifts for S01−P0,1o3 Yb lines from multiconfiguration Dirac-Hartree-Fock calculations

Relativistic multiconfiguration Dirac-Hartree-Fock calculations with configuration interaction are carried out for the $^{1}S_{0}$ and $^{3}P_{0,1}^{o}$ states in neutral ytterbium by use of the available grasp2018 package. From the resultant atomic state functions and the ris4 program, we evaluate the mass- and field-shift parameters for the $^{1}S_{0}\ensuremath{-}\phantom{\rule{0.16em}{0ex}}^{3}P_{0}^{o}$ (clock) and $^{1}S_{0}\ensuremath{-}\phantom{\rule{0.16em}{0ex}}^{3}P_{1}^{o}$ (intercombination) lines. We present improved estimates of the nuclear charge parameters ${\ensuremath{\lambda}}^{A,{A}^{\ensuremath{'}}}$ and differences in mean-square charge radii $\ensuremath{\delta}{\ensuremath{\langle}{r}^{2}\ensuremath{\rangle}}^{A,{A}^{\ensuremath{'}}}$ and examine the second-order hyperfine interaction for the $^{3}P_{0,1}^{o}$ states. Isotope shifts for the clock transition have been estimated by three largely independent means from which we predict the unknown clock-line frequencies in bosonic Yb isotopes. Knowledge of these line frequencies has implications for King-plot nonlinearity tests and the search for beyond-standard-model signatures.

Nuclear deformation as a source of the nonlinearity of the King plot in the Yb+ ion

We perform atomic relativistic many-body calculations of the field isotope shifts and calculations of corresponding nuclear parameters for all stable even-even isotopes of Yb$^+$ ion. We demonstrate that if we take nuclear parameters of the Yb isotopes from a range of the state-the-art nuclear models which all predict strong quadrupole nuclear deformation, then calculated non-linearity of the King plot, caused by the difference in the deformation in different isotopes, is consistent with the non-linearity observed in the experiment (Ian Counts {\em et al}, Phys. Rev. Lett. {\bf 125}, 123002 (2020)). The changes of nuclear RMS radius between isotopes extracted from experiment are consistent with those obtained in the nuclear calculations.

High-precision mass measurement of 168Yb for verification of nonlinear isotope shift

The absolute mass value of 168Yb has been directly determined with the JYFLTRAP Penning trap mass spectrometer at the Ion Guide Isotope Separator On-Line (IGISOL) facility. A more precise value of the mass of 168Yb is needed to extract possible signatures of beyond standard model physics from high-precision isotope shift measurements of Yb atomic transition frequencies. The measured mass-excess value, ME(168Yb) = −61579.846(94) keV, is 13 times more precise and deviates from the Atomic Mass Evaluation 2016 value by 1.7σ. The impact on precision isotope shift studies of the stable Yb isotopes is discussed.

Alpha-decay half-life of Hafnium isotopes reinvestigated by a semi-empirical approach

- New estimates of partial α-decay half-life, T1/2, for 156–162,174,176Hf isotopes by a semi-empirical, one-parameter model are given. The used model is based on the quantum mechanical tunneling mechanism through a potential barrier, where the Coulomb, centrifugal and overlapping components to the barrier have been considered within the spherical nucleus approximation. This approach enables to reproduce, within a factor 2, the measured T1/2 of ground-state to ground-state (gs–gs) α-transitions for the artificially produced 156–162Hf isotopes. Half-life predictions for α-transitions from the ground-state of 159,161Hf isotopes to the first gamma-excited level of 155,157Yb isotopes are reported for the first time. The model also provides T1/2-values of (2.43±0.28)×1016 a and (1.47±0.19)×1020 a for the naturally occurring 174Hf and 176Hf isotopes, respectively, in quite good agreement with a number of estimates by other authors. In addition, the present methodology indicates that 174,176Hf isotopes exhibit α-transition to the first gamma-excited level of their daughter Ytterbium isotopes which half-lives are found (0.9±0.1)×1018 a and (0.72±0.08)×1022 a, respectively, with a chance of being measured by improved α-detection and α-spectrometry methods available nowadays.