A very exotic decay mode at the proton drip-line, \(\beta\)-delayed \(\gamma\)-proton decay, has been observed in the \(\beta\) decay of the \(T_z\) = -2 nucleus \(^{56}\)Zn. Three \(\gamma\)-proton ...sequences have been observed following the \(\beta\) decay. The fragmentation of the IAS in \(^{56}\)Cu has also been observed for the first time. The results were reported in a recent publication. At the time of publication the authors were puzzled by the competition between proton and \(\gamma\) decays from the main component of the IAS. Here we outline a possible explanation based on the nuclear structure properties of the three nuclei involved, namely \(^{56}\)Zn, \(^{56}\)Cu and \(^{55}\)Ni, close to the doubly magic nucleus \(^{56}\)Ni. From the fragmentation of the Fermi strength and the excitation energy of the two populated 0\(^{+}\) states we could deduce the off-diagonal matrix element of the charge-dependent part of the Hamiltonian responsible for the mixing. These results are compared with the decay of \(^{55}\)Cu with one proton less than \(^{56}\)Zn. For completeness we summarise the results already published.
A study of the \(\beta\) decay of the proton-rich \(T_{z}\) = -2 nucleus \(^{56}\)Zn has been reported in a recent publication. A rare and exotic decay mode, \(\beta\)-delayed \(\gamma\)-proton ...decay, has been observed there for the first time in the \(fp\) shell. Here we expand on some of the details of the data analysis, focussing on the charged particle spectrum.
We report the observation of a very exotic decay mode at the proton drip-line, the \(\beta\)-delayed \(\gamma\)-proton decay, clearly seen in the \(\beta\) decay of the \(T_z\) = -2 nucleus ...\(^{56}\)Zn. Three \(\gamma\)-proton sequences have been observed after the \(\beta\) decay. Here this decay mode, already observed in the \(sd\)-shell, is seen for the first time in the \(fp\)-shell. Both \(\gamma\) and proton decays have been taken into account in the estimation of the Fermi (F) and Gamow Teller (GT) strengths. Evidence for fragmentation of the Fermi strength due to strong isospin mixing is found.
Phys.Lett. B633 (2006) 469-473 Fano-resonances are investigated as a new continuum excitation mode in exotic
nuclei. By theoretical model calculations we show that the coupling of a single
particle ...elastic channel to closed core-excited channels leads to sharp
resonances in the low-energy continuum. A signature for such bound states
embedded in the continuum (BSEC) are characteristic interference effects
leading to asymmetric line shapes. Following the quasiparticle-core coupling
model we consider the coupling of 1-QP (one-quasiparticle) and 3-QP components
and find a number of long-living resonance structures close to the particle
threshold. Results for 15C are compared with experimental data, showing that
the experimentally observed spectral distribution and the interference pattern
are in qualitative agreement with a BSEC interpretation.
Fano-resonances are investigated as a new continuum excitation mode in exotic nuclei. By theoretical model calculations we show that the coupling of a single particle elastic channel to closed ...core-excited channels leads to sharp resonances in the low-energy continuum. A signature for such bound states embedded in the continuum (BSEC) are characteristic interference effects leading to asymmetric line shapes. Following the quasiparticle-core coupling model we consider the coupling of 1-QP (one-quasiparticle) and 3-QP components and find a number of long-living resonance structures close to the particle threshold. Results for 15C are compared with experimental data, showing that the experimentally observed spectral distribution and the interference pattern are in qualitative agreement with a BSEC interpretation.
The beta-delayed neutron emission probability, P-n, of very neutron-rich nuclei allows us to achieve a better understanding of the nuclear structure above the neutron separation energy, S-n. The ...emission of neutrons can become the dominant decay process in neutron-rich astrophysical phenomena such as the rapid neutron capture process (r-process). There are around 600 accessible isotopes for which beta-delayed one-neutron emission (beta 1n) is energetically allowed, but the branching ratio has only been determined for about one third of them. beta 1n decays have been experimentally measured up to the mass A similar to 1 5 0, plus a single measurement of Tl-210. Concerning two-neutron emitters (beta 2n), similar to 3 0 0 isotopes are accessible and only 24 have been measured so far up to the mass A = 100. In this contribution, we report recent experiments which allowed the measurement of beta 1n emitters for masses beyond A > 200 and N > 1 2 6 and identified the heaviest beta 2n emitter measured so far, Sb-136.
Experimental signatures of the dynamical correlations of a core with a single-particle neutron have been found in light neutron-rich nuclei investigated via the (7Li,7Be)c harge-exchange reactions at ...around 8MeV/u. Of particular astrophysical relevance are low-lying narrow resonances (Γ ∼ 200 keV FWHM) BSEC (Bound States Embedded in the Continuum). Because of their long lifetime BSEC states are likely to effect the capture rates in any scenario for nucleosynthesis in neutron-rich environment. They have been observed in the continuum of 11Be and 15C nuclei. A microscopic nuclear structure model based on QRPA theory, which takes into account Dynamical Core Polarisation (DCP) correlations, gives a suitable description of these resonances as well as single-particle states of the studied systems. In this context, high-energy narrow structures populated in nuclei having an integer number of α-particles plus three neutrons are good BSEC candidates and can be systematically investigated.
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