Multipole resonances in open shell deformed nuclei

Distribution and values of the multipole resonances (MR) strengths in open shell nuclei, especially in deformed ones, represent a challenge to the theory. Some advance in the interpretation of MR in these nuclei could be achieved in particle - core coupling (PCC) version of shell model (SM), where energy spreading of final nuclei states is taken into account. This paper presents an attempt to get a realistic description of lℎ/2πω MR characteristics in deformed 24Mg and 26Mg nuclei with open valent shell. The resonance wave functions for lℎ/2πω isovector excitation of 24Mg and 26Mg were obtained in PCC on the basis |(J'T'E')x(j'):J-T□ which contains all states| |(J'T'E')□ of A=23 or A=25 nuclei with noticeable spectroscopic factors for pick-up reactions. The ground states both investigated nuclei as well as states of daughter nuclei are deformed. In PCC basis were obtained wave functions of all lℎ/2πω MR of magnesium isotopes and form factors of these resonances as momentum transfer functions. The contributions of orbital and spin intranucleus currents into form factors were analysed. The energy distributions of E1 strengths at photo point in 24Mg and 26Mg nuclei achieved in PCC are in a good agreement with observed photonuclear data, revealing the priority of energy spread of final nuclei states in forming the MR distribution for open shell nuclei. Calculated M6 from factors spreading explains the main feature of experimental data for stretched states in 24Mg and 26Mg nuclei. (authors)