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Title: 12C and the {beta}-decays of 12B and 12N

Abstract

The {beta}-decays of the mirror nuclei 12B and 12N are used to extract spectroscopic information on 12C. 0+, 1+ and 2+ states. Recent results are summarized and new data and future plans are discussed.

Authors:
 [1]
  1. Department of Physics and Astronomy, University of Aarhus, 8000 Aarhus C (Denmark)
Publication Date:
OSTI Identifier:
20798549
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 831; Journal Issue: 1; Conference: International conference on frontiers in nuclear structure, astrophysics, and reactions - FINUSTAR, Isle of Kos (Greece), 12-17 Sep 2005; Other Information: DOI: 10.1063/1.2200941; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; BETA DECAY; BORON 12; CARBON 12; CARBON 19; ENERGY LEVELS; MIRROR NUCLEI; NITROGEN 12; NUCLEAR STRUCTURE

Citation Formats

Fynbo, H. O. U. 12C and the {beta}-decays of 12B and 12N. United States: N. p., 2006. Web. doi:10.1063/1.2200941.
Fynbo, H. O. U. 12C and the {beta}-decays of 12B and 12N. United States. doi:10.1063/1.2200941.
Fynbo, H. O. U. Wed . "12C and the {beta}-decays of 12B and 12N". United States. doi:10.1063/1.2200941.
@article{osti_20798549,
title = {12C and the {beta}-decays of 12B and 12N},
author = {Fynbo, H. O. U.},
abstractNote = {The {beta}-decays of the mirror nuclei 12B and 12N are used to extract spectroscopic information on 12C. 0+, 1+ and 2+ states. Recent results are summarized and new data and future plans are discussed.},
doi = {10.1063/1.2200941},
journal = {AIP Conference Proceedings},
number = 1,
volume = 831,
place = {United States},
year = {Wed Apr 26 00:00:00 EDT 2006},
month = {Wed Apr 26 00:00:00 EDT 2006}
}
  • Two complementary experimental techniques have been used to extract precise branching ratios to unbound states in {sup 12}C from {sup 12}N and {sup 12}B {beta}-decays. In the first the three {alpha}-particles emitted after {beta}-decay are measured in coincidence in separate detectors, while in the second method {sup 12}N and {sup 12}B are implanted in a detector and the summed energy of the three {alpha}-particles is measured directly. For the narrow states at 7.654 MeV (0{sup +}) and 12.71 MeV (1{sup +}) the resulting branching ratios are both smaller than previous measurements by a factor of {approx_equal} 2. The experimental resultsmore » are compared to no-core shell model calculations with realistic interactions from chiral perturbation theory, and inclusion of three-nucleon forces is found to give improved agreement.« less
  • The ratio of inclusive electron scattering cross sections for 15N/12C was determined in the kinematic range 0.8<2 GeV and 0.2<1 GeV2 using 2.285 GeV electrons and the CLAS detector at Jefferson Lab. The ratio exhibits only slight resonance structure, as predicted by a phenomenological model, and also by quark-hadron duality. Within the super-scaling quasi-elastic model, slight evidence is found for a 1 MeV lower effective nucleon binding energy in 15N than in 12C. Ratios of 4He/12C using 1.6 to 2.5 GeV electrons are in good agreement with the phenomenological model.
  • The heavy-ion radiative capture reaction, 12C(12C,{gamma}), has been investigated at beam energies around 16 MeV. Three different experiments were performed. Capture cross-sections were obtained by measuring fused 24Mg residues using the FMA at ANL. These were found to significantly exceed values reported earlier. Subsequently, the decay pathways associated with radiative capture were studied in two separate measurements: one with the high-resolution Gammasphere array and a second with a high efficiency BGO array, where gamma rays were recorded in coincidence with 24Mg residues detected at the focal plane of the DRAGON recoil separator at TRIUMF. Both measurements indicate that a substantialmore » fraction of the decay is mediated through high-lying doorway states, possibly associated with the long-predicted shape-isomeric band in 24Mg.« less
  • The heavy ion radiative capture reaction 12C(12C,{gamma}) has been investigated around a beam energy of 16 MeV. The total cross-section has been measured with the Fragment Mass Analyser at Argonne National Laboratory and found to be somewhat larger than has previously been measured. A subsequent measurement with the Gammasphere array has shown that a considerable proportion of this extra cross-section relates to a highly non-statistical decay through high-lying states in 24Mg.
  • The High Acceptance DiElectron Spectrometer (HADES) has been constructed at the SIS accelerator (GSI, Darmstadt) to investigate electron-positron pairs produced in proton, pion and heavy-ion induced reactions. The physics programme of HADES is focused on in-medium properties of light vector mesons. In this contribution the HADES experiment is outlined and first results obtained for 12C + 12C collisions at 2 AGeV are presented.