Extending MCAS to hypernuclei and radiative-capture reactions
Istituto Nazionale di Fisica Nucleare, sezione di Padova, via Marzolo 8,
2 School of Physics, University of Melbourne, Victoria 3010, Australia
3 Department of Physics and Electronics, Rhodes University, Grahamstown 6140, South Africa
4 Department of Physics and Astronomy, University of Manitoba, Winnipeg, MB, Canada R3T 2N2
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Using a Multi-Channel Algebraic Scattering (MCAS) approach we have analyzed the spectra of two hypernuclear systems, 9ΛBe and 13ΛC. We have studied the splitting of the two odd-parity excited levels (1/2− and 3/2−) at 11 MeV excitation in 13ΛC, originated by the weak Λ-nucleus spin-orbit force. We have also considered the splittings of the 3/2+ and 5/2+ levels in both 9ΛBe and 13ΛC, finding how they originate from couplings to the collective 2 + states of the core nuclei. In both hypernuclei, we suggest that there could be additional low-lying resonant states in the Λ-nucleus continua. From the MCAS approach one can extract also the full coupled-channel scattering wavefunction to be used in the calculation of various transition matrix elements. As a first application, we have considered the EM-transition matrix elements for the capture reaction α + 3He→7Be+γ.
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