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Träfflista för sökning "WFRF:(Borge M. J. G.) srt2:(1985-1989)"

Sökning: WFRF:(Borge M. J. G.) > (1985-1989)

  • Resultat 1-7 av 7
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1.
  • Bjornstad, T., et al. (författare)
  • Study of the Giant Gamow-Teller Resonance in Nuclear Beta-Decay - the Case of Ar-32
  • 1985
  • Ingår i: Nuclear Physics A. - 0375-9474. ; 443:2, s. 283-301
  • Tidskriftsartikel (refereegranskat)abstract
    • Delayed proton and gamma emissions following the β-decay of 32Ar have been studied. The half-life of 32Ar is 98 ± 2 ms, and the T = 2 analogue state in 32Cl lies at the excitation energy 5036 ± 12 keV. From the intensity of the feeding to this state the proton intensities can be converted to an absolute scale leading to a total proton branching ratio of (43 ± 3)%. From proton-gamma coincidence measurements it emerges that (1.9 ± 0.2)% of the protons lead to the first-excited state in 31S. A level scheme up to 8.75 MeV excitation in 32Cl has been constructed and the Gamow-Teller strength function has been deduced. The result is a renormalization of the axial-vector strength to (49 ± 5)% of the free-nucleon value.
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2.
  • Bjornstad, T., et al. (författare)
  • The Doubly Closed Shell Nucleus Sn-132(50)82
  • 1986
  • Ingår i: Nuclear Physics A. - 0375-9474. ; 453:3, s. 463-485
  • Tidskriftsartikel (refereegranskat)abstract
    • The structure of excited states in 132Sn, fed in the β-decay of 132In, has been investigated. Absolute intensities were deduced from γ-singles measurements. From multi-spectrum analysis of γ-lines the half-life of 132In was determined to be 186 ± 22 ms. A level scheme based on γγ and βγ coincidences is presented. The conversion electron spectrum has been studied and internal conversion coefficients deduced for two low-energy transitions. The total decay energy of 132In was determined, from γ-gated β-spectra, to be Qβ = 13.6 ± 0.4 MeV. A lower limit of 6.968 MeV for the neutron separation energy in 132Sn was deduced from the β-delayed neutron spectrum. The experimental results on the level structure of the doubly closed shell nucleus 132Sn show that the shell model is applicable even far from the valley of stability.
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3.
  • Borge, M. J. G., et al. (författare)
  • Study of the Giant Gamow-Teller Resonance in Nuclear Beta-Decay - the Case of Ar-33
  • 1987
  • Ingår i: Physica Scripta. - 0031-8949. ; 36:2, s. 218-223
  • Tidskriftsartikel (refereegranskat)abstract
    • Delayed proton and gamma emissions following the beta decay of 33Ar have been studied. From the calculated intensity of the feeding to the T = 3/2 analogue state in 33C1, the proton intensities have been put on an absolute scale leading to a proton branching ratio of 38.7 ± 1.0%. A proton branch to the first excited state in 32S at 2230.2 keV (1π = 2+) with an intensity of 0.77 ± 0.10% was obtained from gamma singles and proton-gamma coincidence data. The complete spectroscopic information on 33Ar allows the Gamow-Teller (GT) strength function from the gound state and up to 9.25 MeV excitation energy in 33C1 to be deduced. The total strength observed in this interval is 2.90 in absolute units.
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4.
  • Borge, M. J. G., et al. (författare)
  • Beta-Delayed Proton and Alpha Emission in the Decay of Ne-17
  • 1988
  • Ingår i: Nuclear Physics A. - 0375-9474. ; 490:2, s. 287-306
  • Tidskriftsartikel (refereegranskat)abstract
    • The beta-delayed proton and alpha spectra from 17Ne have been studied with Si-detectors. The Gamow-Teller strength in the decay of 17Ne has been extracted and compared with a two-particle-one-hole shell-model calculation. The experimental strength is quenched by a factor of 0.82 with respect to the calculated one. Furthermore, the decay scheme has been improved and is discussed in some detail. The proton emitting levels in 17F are very broad and the line shapes are strongly influenced by phase-space effects. Interference between peaks corresponding to the same intermediate spin is a prominent feature emerging clearly with the good resolution and statistics of the present work.
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5.
  • Borge, M. J. G., et al. (författare)
  • Beta-Delayed Triton Emission in the Decay of He-8
  • 1986
  • Ingår i: Nuclear Physics A. - 0375-9474. ; 460:3, s. 373-380
  • Tidskriftsartikel (refereegranskat)abstract
    • A β-delayed triton branch with an intensity of (0.9 ± 0.1)% has been observed in the decay of 8He. The triton energy spectrum was measured with a specially designed ΔE − E telescope. These data as well as an earlier measured β-delayed neutron spectrum cannot be explained from the known levels in 8Li, but it turns out that the main features of both the delayed triton and the delayed neutron spectra from 8He could be understood if one assumes a new state in 8Li at about 8.8 MeV excitation energy.
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6.
  • Borge, M. J. G., et al. (författare)
  • Limits on Neutrino-Mixing from the Internal Bremsstrahlung Spectrum of I-125
  • 1986
  • Ingår i: Physica Scripta. - 0031-8949. ; 34:6A, s. 591-596
  • Tidskriftsartikel (refereegranskat)abstract
    • The massive antineutrino recently reported by Simpson in an experiment on tritium decay has not been confirmed by experiments on 35S decay. As an independent check, we report here the negative result of a search for the corresponding antiparticle (a massive neutrino) using the decay of 125I. As a by-product, we give accurate data on internal-bremsstrahlung spectra which we have followed over close to four decades in intensity, and we report a new way of measuring its E1/M1 ratio. The experiment provides a new and very accurate value for the 125I-125Te mass difference of 186.1 ± 0.3 keV.
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7.
  • Borge, M. J. G., et al. (författare)
  • The Axial-Vector Strength in the Proton-Rich Argon Isotopes
  • 1989
  • Ingår i: Zeitschrift für Physik A Atomic Nuclei. - 0939-7922. ; 332:4, s. 413-417
  • Tidskriftsartikel (refereegranskat)abstract
    • The proton-rich isotopes32Ar-35Ar represent the first sequence for which the superallowed Gamow-Teller strength is known out toZ− N=4. The results are compared with two sets of predictions from large shell-model calculations, which give systematically different quenching factors, on the average 0.54 and 0.89. Possible reasons for this are discussed. A comparison is also made with the Gamow-Teller strength of proton-rich isotopes of neighbouring elements.
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