1,732 research outputs found
The strength of beta-decays to the continuum
The beta-strength in beta-delayed particle decays has up to now been defined
in a somewhat ad hoc manner that depends on the decay mechanism. A simple,
consistent definition is presented that fulfils the beta strength sum rules.
Special consideration is given to the modifications needed when employing
R-matrix fits to data. As an example the 11Be(beta-p) decay is investigated
through simple models.Comment: 18 pages, 4 figure
Classification of three-body quantum halos
The different kinds of behaviour of three-body systems in the weak binding
limit are classified with specific attention to the transition from a true
three-body system to an effective two-body system. For weakly bound Borromean
systems approaching the limit of binding we show that the size-binding energy
relation is an almost universal function of the three s-wave scattering lengths
measured in units of a hyperradial scaling parameter defined as a mass weighted
average of two-body equivalent square well radii. We explain why three-body
halos follow this curve and why systems appearing above reveal two-body
substructures. Three-body quantum halos 2-3 times larger than the limit set by
zero hypermoment are possible
Three-body effects in the Hoyle-state decay
We use a sequential -matrix model to describe the breakup of the Hoyle
state into three particles via the ground state of . It
is shown that even in a sequential picture, features resembling a direct
breakup branch appear in the phase-space distribution of the
particles. We construct a toy model to describe the Coulomb interaction in the
three-body final state and its effects on the decay spectrum are investigated.
The framework is also used to predict the phase-space distribution of the
particles emitted in a direct breakup of the Hoyle state and the
possibility of interference between a direct and sequential branch is
discussed. Our numerical results are compared to the current upper limit on the
direct decay branch determined in recent experiments
The size of two-body weakly bound objects : short versus long range potentials
The variation of the size of two-body objects is investigated, as the
separation energy approaches zero, with both long range potentials and short
range potentials having a repulsive core. It is shown that long range
potentials can also give rise to very extended systems. The asymptotic laws
derived for states with angular momentum l=1,2 differ from the ones obtained
with short range potentials. The sensitivity of the asymptotic laws on the
shape and length of short range potentials defined by two and three parameters
is studied. These ideas as well as the transition from the short to the long
range regime for the l=0 case are illustrated using the Kratzer potential.Comment: 5 pages, 3 figures, submitted to Physical Review Letter
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