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  • 97.10  (2)
  • 21.30  (1)
  • 21.60.Cs  (1)
Materialart
Erscheinungszeitraum
Schlagwörter
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 334 (1989), S. 1-9 
    ISSN: 1434-601X
    Schlagwort(e): 21.60.Cs ; 21.60.Gx ; 23.20.-G
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract StrongB(E1) transitions have been recently observed between states in the18O nucleus which follow roughly the energy sequence of a dimolecular α+14C rotator. These findings have been interpreted by Gai et al. as evidence for a molecular dipole degree of freedom being present in the18O nucleus. However, this idea was contradicted by the results of a microscopic multichannel calculation performed by Descouvemont and Baye which was based on elastic α+14C and inelastic α+14C(2+) many-body cluster wave functions. We have improved this study by performing a microscopic multichannel calculation including additionally an+17O many-body fragmentation in order to enlarge our model space by those shell model components which dominate the structure of the (positive parity)18O ground state band. Like Descouvemont and Baye we find a positive parity α+14C molecular band in18O and, additionally, a rather strong collectivity in the lowest 1−, 3− and 5− states in18O. However, since the internal structure is different within these states, the calculated states should not be interpreted as a negative parity α+14C molecular band. In this perspective, the microscopic multichannel calculations do not support the hypothesis of a molecular dipole degree of freedom being present in the18O nucleus.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 342 (1992), S. 133-140 
    ISSN: 1434-601X
    Schlagwort(e): 21.30 ; 67.20 ; 97.60
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract We have studied the helium plasma in the hypernetted-chain-Approximation considering both short-ranged internuclear and long-ranged Coulomb interactions. The optimal two-particle wave function has been determined in HNC/0 approximation. The two-particle distribution functions, which have been calculated in various orders of HNC/n approximations (n=0, 4, 5), are used to determine the pycnonuclear triple-alpha-fusion rate in the density regime 108 g/cm3≤ρ≤1010 g/cm3, in which the fusing of three alpha-particles to form a12C-nucleus plays an important role in the crust evolution of an accreting old neutron star. Our calculation supports the idea that the helium liquid undergoes a phase transition to stable8Be matter at densities slightly lower thanρ≈3×109 g/ cm3 as the plasma induced screening potential then becomes strong enough to bind the8Be ground state.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 324 (1986), S. 147-152 
    ISSN: 1434-601X
    Schlagwort(e): 97.10 ; 97.60
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract We have studied the triple-α-reaction at low temperatures which is of importance on accreting white dwarfs and neutron stars. Although we have improved a recent investigation of Nomoto, Thielemann and Miyaji on several points, we find a reaction rate for the relevant temperature range (T=107−108K) which is rather similar to the previous result. In particular, our improved study confirms that helium might be ignited on accreting white dwarfs at temperaturesT≦4.107 K.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 325 (1986), S. 309-315 
    ISSN: 1434-601X
    Schlagwort(e): 25.40 ; 97.10
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract We have updated and recalculated the21Na(p, γ)22Mg and22Na(p, γ)23Mg reaction rates for temperatures 107–109 K relevant for explosive hydrogen burning in stellar environment. We find the21Na(p, γ)22Mg rate lower than recently suggested. Considering various uncertainties in spin and parity assignments of the low energy22Na+p resonances we present upper and lower limits for the22Na(p, γ)23Mg reaction rate which, however, allows for a meaningful discussion of the consequences of the new rates on the Ne - Na cycle under various stellar conditions.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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