Electric dipole excitations and related structures in atomic nuclei
Final Report Abstract
During the second funding period we continued and extended the previously obtained results. In particular, we developed new experimental techniques which provide access to additional observables on the detailed structure of electric dipole excitations. This includes the SONIC@HORUS setup at IKP in Cologne and the γγ coincidence setup γ3 at HIGS in Durham, NC, USA. Both setups consist of a combination of two different types of detectors and the acquisition of coincidences: HPGe detectors and Si detectors for the SONIC@HORUS setup and HPGe detectors plus LaBr detectors in the case of the γ3 setup. By means of these new experimental techniques we were able to study the decay behavior of 1- states in greater detail and compared them to calculations on basis of the microscopic multi-phonon approach. The topics of our investigations covered the γ-decay behavior of the Pygmy Dipole Resonance, the decay pattern of two-phonon 1- excitations of nuclei in different mass regions, the population of low-lying 1- states via new reaction mechanisms like the (d,p) reaction, and lifetime measurements using the DSAM technique. In a complementary approach we studied the dipole response to an additional hadronic probe, namely protons at intermediate energy, for the nucleus 140Ce and compared the results to previous results from αscattering and real-photon scattering experiments. For the theoretical description of the observed properties we collaborated with a number of different researchers all over the world. We applied the algebraic interacting boson model as well as microscopic approaches like the quasiparticle phonon model, the random-phase approximation and the relativistic quasiparticle time-blocking approximation.
Publications
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Phys. Rev. C 85 (2012) 064315
S. Pascu, J. Endres, N.V. Zamfir, and A. Zilges
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Phys. Rev. C 85 (2012) 064331
J. Endres, D. Savran, P.A. Butler, M.N. Harakeh, S. Harissopulos, R.-D. Herzberg, R. Krücken, A. Lagoyannis, E. Litvinova, N. Pietralla, V.Yu. Ponomarev, L. Popescu, P. Ring, M. Scheck, F. Schlüter, K. Sonnabend, V.I. Stoica, H.J. Wörtche, and A. Zilges
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Nucl. Phys. A 906 (2013) 94
V. Derya, J. Endres, M. Elvers, M.N. Harakeh, N. Pietralla, C. Romig, D. Savran, M. Scheck, F. Siebenhühner, V.I. Stoica, H.J. Wörtche, and A. Zilges
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Phys. Rev. C 88 (2013) 041303(R)
M. Spieker, D. Bucurescu, J. Endres, T. Faestermann, R. Hertenberger, S. Pascu, S. Skalacki, S. Weber, H.-F. Wirth, N.-V. Zamfir, and A. Zilges
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Prog. Part. Nucl. Phys. 70 (2013) 210
D. Savran, T. Aumann, and A. Zilges
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Phys. Lett. B 730 (2014) 288
V. Derya, D. Savran, J. Endres, M.N. Harakeh, H. Hergert, J.H. Kelley, P. Papakonstantinou, N. Pietralla, V.Yu. Ponomarev, R. Roth, G. Rusev, A.P. Tonchev, W. Tornow, H.J. Wörtche, and A. Zilges
