936 research outputs found
Accurate mass measurements of Ne, Na, Mg performed with the {\sc Mistral} spectrometer
The minuteness of the nuclear binding energy requires that mass measurements
be highly precise and accurate. Here we report on new measurements Mg
and Na performed with the {\sc Mistral} mass spectrometer at {\sc
Cern}'s {\sc Isolde} facility. Since mass measurements are prone to systematic
errors, considerable effort has been devoted to their evaluation and
elimination in order to achieve accuracy and not only precision. We have
therefore conducted a campaign of measurements for calibration and error
evaluation. As a result, we now have a satisfactory description of the {\sc
Mistral} calibration laws and error budget. We have applied our new
understanding to previous measurements of Ne, Na and
Mg for which re-evaluated values are reported.Comment: submitted to Nuclear Physics
National Space Transportation Systems Program mission report
The STS 41-C National Space Transportation Systems Program Mission Report contains a summary of the major activities and accomplishments of the eleventh Shuttle flight and fifth flight of the OV-099 vehicle, Challenger. Also summarized are the significant problems that occurred during STS 41-C, and a problem tracking list that is a complete list of all problems that occurred during the flight. The major objectives of flight STS 41-C were to successfully deploy the LDEF (long duration exposure facility) and retrieve, repair and redeploy the SMM (Solar Maximum Mission) spacecraft, and perform functions of IMAX and Cinema 360 cameras
Ferromagnetism in substituted zinc oxide
Room-temperature ferromagnetism is observed in (110) oriented ZnO films
containing 5 at % of Sc, Ti, V, Fe, Co or Ni, but not Cr, Mn or Cu ions. There
are large moments, 1.9 and 0.5 muB/atom for Co- and Ti-substituted oxides,
respectively. Sc-substituted ZnO shows also a moment of 0.3 muB/Sc.
Magnetization is very anisotropic, with variations of up to a factor three
depending on the orientation of the applied field relative to the R-cut
sapphire substrates. Results are interpreted in terms of a spin-split donor
impurity band model, which can account for ferromagnetism in insulating or
conducting high-k oxides with concentrations of magnetic ions that lie far
below the percolation threshold. The variation of the ferromagnetism with
oxygen pressure used during film growth is evidence of a link between
ferromagnetism and defect concentration.Comment: 15 pages, 4 figure
National Space Transportation Systems Program mission report
The major activities and accomplishments of this first Spacelab mission using Orbiter vehicle 102. The significant configuration differences incorporated prior to STS-9 include the first use of the 3 substack fuel cells, the use of 5 cryo tanks sets and the addition of a galley and crew sleep stations. These differences combined with the Spacelab payload resulted in the heaviest landing weight yet flown. The problems that occurred are cited and a problem tracking list of all significant anomalies tht occurred during the mission is included. Scientific results of experiments conducted are highlighted
Search for supernova-produced 60Fe in a marine sediment
An 60Fe peak in a deep-sea FeMn crust has been interpreted as due to the
signature left by the ejecta of a supernova explosion close to the solar system
2.8 +/- 0.4 Myr ago [Knie et al., Phys. Rev. Lett. 93, 171103 (2004)]. To
confirm this interpretation with better time resolution and obtain a more
direct flux estimate, we measured 60Fe concentrations along a dated marine
sediment. We find no 60Fe peak at the expected level from 1.7 to 3.2 Myr ago.
However, applying the same chemistry used for the sediment, we confirm the 60Fe
signal in the FeMn crust. The cause of the discrepancy is discussed.Comment: 15 pages, 5 figures, submitted to PR
Q-Value and Half-Lives for the Double-Beta-Decay Nuclide 110Pd
The 110Pd double-beta decay Q-value was measured with the Penning-trap mass
spectrometer ISOLTRAP to be Q = 2017.85(64) keV. This value shifted by 14 keV
compared to the literature value and is 17 times more precise, resulting in new
phase-space factors for the two-neutrino and neutrinoless decay modes. In
addition a new set of the relevant matrix elements has been calculated. The
expected half-life of the two-neutrino mode was reevaluated as 1.5(6) E20 yr.
With its high natural abundance, the new results reveal 110Pd to be an
excellent candidate for double-beta decay studies
Preparation of cooled and bunched ion beams at ISOLDE-CERN
Abstract.: At ISOLDE a new RadioFrequency Quadrupole ion Cooler and Buncher (RFQCB) is being constructed to improve ion optical properties of low-energy RIBs. The new features of the mechanical design and the status of the test bench, which will serve to test the device, will be presented in this contributio
First direct mass-measurement of the two-neutron halo nucleus 6He and improved mass for the four-neutron halo 8He
The first direct mass-measurement of He has been performed with the
TITAN Penning trap mass spectrometer at the ISAC facility. In addition, the
mass of He was determined with improved precision over our previous
measurement. The obtained masses are (He) = 6.018 885 883(57) u and
(He) = 8.033 934 44(11) u. The He value shows a deviation from
the literature of 4. With these new mass values and the previously
measured atomic isotope shifts we obtain charge radii of 2.060(8) fm and
1.959(16) fm for He and He respectively. We present a detailed
comparison to nuclear theory for He, including new hyperspherical harmonics
results. A correlation plot of the point-proton radius with the two-neutron
separation energy demonstrates clearly the importance of three-nucleon forces.Comment: 4 pages, 2 figure
Precision Mass Measurements of 129-131Cd and Their Impact on Stellar Nucleosynthesis via the Rapid Neutron Capture Process
Masses adjacent to the classical waiting-point nuclide 130Cd have been
measured by using the Penning- trap spectrometer ISOLTRAP at ISOLDE/CERN. We
find a significant deviation of over 400 keV from earlier values evaluated by
using nuclear beta-decay data. The new measurements show the reduction of the N
= 82 shell gap below the doubly magic 132Sn. The nucleosynthesis associated
with the ejected wind from type-II supernovae as well as from compact object
binary mergers is studied, by using state-of-the-art hydrodynamic simulations.
We find a consistent and direct impact of the newly measured masses on the
calculated abundances in the A = 128 - 132 region and a reduction of the
uncertainties from the precision mass input data
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