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Wallner A, Faestermann T, Feige J, Feldstein C, Knie K, Korschinek G, Kutschera W, Ofan A, Paul M, Quinto F, Rugel G, Steier P. Abundance of live ²⁴⁴Pu in deep-sea reservoirs on Earth points to rarity of actinide nucleosynthesis. Nat Commun 2015; 6:5956. [PMID: 25601158 PMCID: PMC4309418 DOI: 10.1038/ncomms6956] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2014] [Accepted: 11/26/2014] [Indexed: 11/09/2022] Open
Abstract
Half of the heavy elements including all actinides are produced in r-process
nucleosynthesis, whose sites and history remain a mystery. If continuously produced,
the Interstellar Medium is expected to build-up a quasi-steady state of abundances
of short-lived nuclides (with half-lives ≤100 My), including actinides
produced in r-process nucleosynthesis. Their existence in today’s
interstellar medium would serve as a radioactive clock and would establish that
their production was recent. In particular 244Pu, a radioactive
actinide nuclide (half-life=81 My), can place strong constraints on recent
r-process frequency and production yield. Here we report the detection of
live interstellar 244Pu, archived in Earth’s deep-sea
floor during the last 25 My, at abundances lower than expected from continuous
production in the Galaxy by about 2 orders of magnitude. This large discrepancy may
signal a rarity of actinide r-process nucleosynthesis sites, compatible with
neutron-star mergers or with a small subset of actinide-producing supernovae. The build-up of short-lived nuclides in the interstellar medium tells
us about production frequency and yield of heavy elements by nucleosynthesis. Wallner
et al. find a low abundance of live interstellar 244Pu detected from the
deep-sea floor, suggesting a rarity for r-process nucleosynthesis sites.
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Affiliation(s)
- A Wallner
- 1] Department of Nuclear Physics, Australian National University, Canberra, Australian Capital Territory 0200, Australia [2] VERA Laboratory, Faculty of Physics, University of Vienna, Währinger Strasse 17, A-1090 Vienna, Austria
| | - T Faestermann
- Physik Department, Technische Universität München, D-85747 Garching, Germany
| | - J Feige
- VERA Laboratory, Faculty of Physics, University of Vienna, Währinger Strasse 17, A-1090 Vienna, Austria
| | - C Feldstein
- Racah Institute of Physics, Hebrew University, Jerusalem 91904, Israel
| | - K Knie
- 1] Physik Department, Technische Universität München, D-85747 Garching, Germany [2] GSI Helmholtz-Zentrum für Schwerionenforschung GmbH, Planckstrasse 1, 64291 Darmstadt, Germany
| | - G Korschinek
- Physik Department, Technische Universität München, D-85747 Garching, Germany
| | - W Kutschera
- VERA Laboratory, Faculty of Physics, University of Vienna, Währinger Strasse 17, A-1090 Vienna, Austria
| | - A Ofan
- Racah Institute of Physics, Hebrew University, Jerusalem 91904, Israel
| | - M Paul
- Racah Institute of Physics, Hebrew University, Jerusalem 91904, Israel
| | - F Quinto
- VERA Laboratory, Faculty of Physics, University of Vienna, Währinger Strasse 17, A-1090 Vienna, Austria
| | - G Rugel
- Physik Department, Technische Universität München, D-85747 Garching, Germany
| | - P Steier
- VERA Laboratory, Faculty of Physics, University of Vienna, Währinger Strasse 17, A-1090 Vienna, Austria
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Ofan A, Lilienblum M, Gaathon O, Sehrbrock A, Hoffmann A, Bakhru S, Bakhru H, Irsen S, Osgood RM, Soergel E. Large-area regular nanodomain patterning in He-irradiated lithium niobate crystals. Nanotechnology 2011; 22:285309. [PMID: 21646696 DOI: 10.1088/0957-4484/22/28/285309] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Large-area ferroelectric nanodomain patterns, which are desirable for nonlinear optical applications, were generated in previously He-implanted lithium niobate crystals by applying voltage pulses to the tip of a scanning force microscope. The individual nanodomains were found to be of uniform size, which depended only on the inter-domain spacing and the pulse amplitude. We explain this behavior by the electrostatic repulsion of poling-induced buried charges between adjacent domains. The domain patterns were imaged by piezoresponse force microscopy and investigated by domain-selective etching in conjunction with focused ion beam etching followed by scanning electron microscopy imaging. In order to optimize the He-irradiation parameters for easy and reliable nanodomain patterning a series of samples subjected to various irradiation fluences and energies was prepared. The different samples were characterized by investigating nanodomains generated with a wide range of pulse parameters (amplitude and duration). In addition, these experiments clarified the physical mechanism behind the facile poling measured in He-irradiated lithium niobate crystals: the damage caused by the energy loss that takes place via electronic excitations appears to act to stabilize the domains, whereas the nuclear-collision damage degrades the crystal quality, and thus impedes reliable nanodomain generation.
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Affiliation(s)
- A Ofan
- Center for Integrated Science and Technology, Columbia University, New York, NY 10027, USA.
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Nassar H, Paul M, Ahmad I, Ben-Dov Y, Caggiano J, Ghelberg S, Goriely S, Greene JP, Hass M, Heger A, Heinz A, Henderson DJ, Janssens RVF, Jiang CL, Kashiv Y, Nara Singh BS, Ofan A, Pardo RC, Pennington T, Rehm KE, Savard G, Scott R, Vondrasek R. 40Ca(alpha, gamma)44Ti reaction in the energy regime of supernova nucleosynthesis. Phys Rev Lett 2006; 96:041102. [PMID: 16486801 DOI: 10.1103/physrevlett.96.041102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2005] [Indexed: 05/06/2023]
Abstract
The 44Ti(t1/2=59 yr) nuclide, an important signature of supernova nucleosynthesis, has recently been observed as live radioactivity by gamma-ray astronomy from the Cas A remnant. We investigate in the laboratory the major 44Ti production reaction 40Ca(alpha, gamma)44Ti (Ec.m. approximately 0.6-1.2 MeV/u by direct off-line counting of 44Ti nuclei. The yield, significantly higher than inferred from previous experiments, is analyzed in terms of a statistical model using microscopic nuclear inputs. The associated stellar rate has important astrophysical consequences, increasing the calculated supernova 44Ti yield by a factor approximately 2 over previous estimates and bringing it closer to Cas A observations.
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Affiliation(s)
- H Nassar
- Racah Institute of Physics, Hebrew University, 91904 Jerusalem, Israel
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