Gamow—Teller

Fermi selection rules and Gamow-Teller (GT) selection rules are alternative sets of rules for allowed beta transitions both are currently believed to be valid, so that a transition allowed according to either set is actually allowed. 

Thus, in order to understand such environments it is necessary to calculate complete network of the competitions between neutron capture and beta decay as well as their corrections for the thermal population of excited states. With regard to this latter correction it is particularly important to know the low-energy level structure of nuclei away from stability. This structure will affect the beta decay properties differently from the neutron capture properties. In a separate contribution to this conference, [TAK85] we will discuss the corrections for beta decay. Basically this becomes important if a low-lying excited state can undergo a Gamow-Teller allowed decay. The... 

Examples of large-basis shell-model calculations of Gamow-Teller 6-decay properties of specific interest in the astrophysical s-and r- processes are presented. Numerical results are given for i) the GT-matrix elements for the excited state decays of the unstable s-process nucleus "Tc and ii) the GT-strength function for the neutron-rich nucleus 130Cd, which lies on the r-process path. The results are discussed in conjunction with the astrophysics problems. 

We have again utilized the Lanczos algorithm to compute the B strength function for the l3°Cd(0+) l30In(1 + ) Gamow-Teller transitions. Low-... 

We discuss RPA calculations of the Gamow-Teller properties of neutron-rich nuclei to study the effect of B"delayed fission and neutron emission on the production of Th, U and Pu chronometric nuclei in the astrophysical r-process. We find significant differences in the amount of -delayed fission when compared with the recent calculations of Thielemann et al. (1983). 

Only Gamow Teller (GT) allowed 0-decay is studied in this work as it plays the dominant role in the specified mass range. The experimentally studied nuclei are assumed to be... 

Random Phase Approximation Calculations of Gamow-Teller /3-Strength Functions in the A = 80-100 Region with Woods-Saxon Wave Functions... 

Sn have concentrated recently to study "quenching" of Gamow-Teller (GT)... 

S. Towner, "A Mass Dependence in Hindrance Factors for Favoured Gamow-Teller Transitions", to be published. 

Beta-decay half-lives for the neutron-rich isotopes measured in this experiment are compared with previous measurements when they exist. Theoretical predictions for Gamow-Teller beta decay are also provided for... 

For the nuclei studied in this experiment the dominant decay mode is Gamow-Teller beta decay.Partial halflives corresponding to Gamow-Teller beta decay calculated in a spherical shell model formalism [Bro85] are shown in Table I.The calculated lifetimes are with one exception(17C) all shorter than the measured lifetimes. 

This has contribution from the allowed transitions by Fermi and Gamow-Teller (GT) operators. They have the form... 

Gamow-Teller with g = Ca For Fermi coupling, there is no change in the (total) angular momentum between the initial and final states of the nuclei (AJ = 0). 

The Fermi and Gamow-Teller rules correspond respectively to the emission of an electron-neutrino pair in a singlet or triplet state. Convincing evidence has accumulated that transitions of the type 0->0, No and 0- 1, No both occur with high probability, so that the general beta-interaction may contain both scalar and tensor terms. 

Tvpe of transition Fermi rules Gamow-Teller rules ... 

The decay of He to the ground state of Li is superallowed and is the most important evidence for the Gamow-Teller type of coupling in beta-decay. The Fermi allowed decay which would be expected from He to its isobar state at 3.57 MeV in Li is just energetically impossible. No trace of gamma radiation in the He decay has been found, nor has any transition to the 2.189 MeV level (/ = 3 ) been seen. 

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