β -decay half-lives of neutron-rich nuclides in the A=100-110 mass region

β-decay half-lives of neutron-rich nuclides in the A=100-110 mass region have been measured using an implantation station installed inside of the Summing NaI(Tl) (SuN) detector at the National Superconducting Cyclotron Laboratory. Accurate half-lives for these nuclides are important for nuclear astrophysics, nuclear structure, and nuclear technology. The half-lives from the present work are compared with previous measurements, showing overall good agreement

Total absorption spectroscopy of the β decay of Zr 101,102 and Tc 109

20 pags., 9 figs., 5 tabs.The β decay of Zr101,102 and Tc109 was studied using the technique of total absorption spectroscopy. The experiment was performed at the National Superconducting Cyclotron Laboratory using the Summing NaI(Tl) (SuN) detector in the first-ever application of total absorption spectroscopy with a fast beam produced via projectile fragmentation. The β-decay feeding intensity and Gamow-Teller transition strength distributions were extracted for these three decays. The extracted distributions were compared to three different quasiparticle random-phase approximation (QRPA) models based on different mean-field potentials. A comparison with calculations from one of the QRPA models was performed to learn about the ground-state shape of the parent nucleus. For Zr101 and Zr102, calculations assuming a pure shape configuration (oblate or prolate) were not able to reproduce the extracted distributions. These results may indicate that some type of mixture between oblate and prolate shapes is necessary to reproduce the extracted distributions. For Tc109, a comparison of the extracted distributions with QRPA calculations suggests a dominant oblate configuration. The other two QRPA models are commonly used to provide β-decay properties in r-process network calculations. This work shows the importance of making comparisons between the experimental and theoretical β-decay distributions, rather than just half-lives and β-delayed neutron emission probabilities, as close to the r-process path as possible.A.A. acknowledges support from the Spanish Ministerio de Economía y Competitividad under Grants No. FPA2011-24553, No. FPA2014-52823-C2-1-P, and No. FPA2017-83946-C2-1-P and the program Severo Ochoa (SEV-2014-0398). P.S. acknowledges support from MCIU/AEI/FEDER,UE (Spain) under Contract No. PGC2018-093636-B-I00. S.V. acknowledges support from Czech Science Foundation Project No. 19-14048 and the Charles University Project No. UNCE/SCI/013. This work was supported by the National Science Foundation under Grants No. PHY 1565546 (NSCL), No. PHY 1430152 (JINA-CEE), and No. PHY 1350234 (CAREER). This material is based upon work supported by the Department of Energy National Nuclear Security Administration through the Nuclear Science and Security Consortium under Awards No. DE-NA0003180 and/or No. DE-NA000097

Shape coexistence from lifetime and branching-ratio measurements in 68,70Ni

© 2016 The Author(s) Shape coexistence near closed-shell nuclei, whereby states associated with deformed shapes appear at relatively low excitation energy alongside spherical ones, is indicative of the rapid change in structure that can occur with the addition or removal of a few protons or neutrons. Near 68Ni (Z=28, N=40), the identification of shape coexistence hinges on hitherto undetermined transition rates to and from low-energy 0+ states. In 68,70Ni, new lifetimes and branching ratios have been measured. These data enable quantitative descriptions of the 0+ states through the deduced transition rates and serve as sensitive probes for characterizing their nuclear wave functions. The results are compared to, and consistent with, large-scale shell-model calculations which predict shape coexistence. With the firm identification of this phenomenon near 68Ni, shape coexistence is now observed in all currently accessible regions of the nuclear chart with closed proton shells and mid-shell neutrons

The G0 Experiment: Apparatus for Parity-Violating Electron Scattering Measurements at Forward and Backward Angles

In the G0 experiment, performed at Jefferson Lab, the parity-violating elastic scattering of electrons from protons and quasi-elastic scattering from deuterons is measured in order to determine the neutral weak currents of the nucleon. Asymmetries as small as 1 part per million in the scattering of a polarized electron beam are determined using a dedicated apparatus. It consists of specialized beam-monitoring and control systems, a cryogenic hydrogen (or deuterium) target, and a superconducting, toroidal magnetic spectrometer equipped with plastic scintillation and aerogel Cerenkov detectors, as well as fast readout electronics for the measurement of individual events. The overall design and performance of this experimental system is discussed.Comment: Submitted to Nuclear Instruments and Method

An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics

For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types

Gamma-Ray Spectroscopy in Lambda Hypernuclei

The present status of hypernuclear gamma-ray spectroscopy with Hyperball is summarized. We observed two gamma transitions of 16-Lambda-O(1- -> 1-,0-) and obtained the strength of the Lambda-N tensor force. In 10B(K-,pi- gamma) data, we did not observe the spin-flip M1 transition of 10-Lambda-B(2- -> 1-), but gamma rays from hyperfragments such as 7-Lambda-Li(7/2+ -> 5/2+) and 9-Lambda-Be(3/2+ ->1/2+) were observed. In 11B(pi+,K+ gamma) data, we observed six gamma transitions of 11_Lambda-B. We also attempted an inclusive gamma-ray measurement with stopped K- beam.Comment: 10 pages, 9 figures, 8th International Conference on Hypernuclear and Strange Particle Physics (HYP2003), Newport News, Virginia, 14-18 Oct 2003, to appear in Nuclear Physics

A Mini-Neptune from TESS and CHEOPS Around the 120 Myr Old AB Dor Member HIP 94235

The Transiting Exoplanet Survey Satellite (TESS) mission has enabled discoveries of the brightest transiting planet systems around young stars. These systems are the benchmarks for testing theories of planetary evolution. We report the discovery of a mini-Neptune transiting a bright star in the AB Doradus moving group. HIP 94235 (TOI-4399, TIC 464646604) is a V mag = 8.31 G-dwarf hosting a 3.00-0.28+0.32R⊠mini-Neptune in a 7.7 day period orbit. HIP 94235 is part of the AB Doradus moving group, one of the youngest and closest associations. Due to its youth, the host star exhibits significant photometric spot modulation, lithium absorption, and X-ray emission. Three 0.06% transits were observed during Sector 27 of the TESS Extended Mission, though these transit signals are dwarfed by the 2% peak-To-peak photometric variability exhibited by the host star. Follow-up observations with the Characterising Exoplanet Satellite confirmed the transit signal and prevented the erosion of the transit ephemeris. HIP 94235 is part of a 50 au G-M binary system. We make use of diffraction limited observations spanning 11 yr, and astrometric accelerations from Hipparcos and Gaia, to constrain the orbit of HIP 94235 B. HIP 94235 is one of the tightest stellar binaries to host an inner planet. As part of a growing sample of bright, young planet systems, HIP 94235 b is ideal for follow-up transit observations, such as those that investigate the evaporative processes driven by high-energy radiation that may sculpt the valleys and deserts in the Neptune population