From Magic 208 Pb to the 170 Dy Mid-Shell Paddy Regan WNSL, Yale University, New Haven, CT and Dept. of Physics, University of Surrey, UK e-mail: firstname.lastname@example.org@surrey.ac.uk
Outline Rick’s thesis work (circa 1967, ‘before my time’) A hard act to follow....heavy, neutron-rich DIC around 194 Os (shape shifters). ISOL work, pushing the limits, 182 Yb. Isomer fragentation spectroscopy at GSI – 202 Pt single particle state inversion – 190 W, sub-shell closure ? Towards 170 Dy, best K-isomer and SU(3) Future prospects with RIA and others ?
2 + 2 ->2 + 1 2 + 2 ->0 + 1 Ge arrays and HI beams allow ) coincs. to probe yrast states to ‘high spins’ (12 + in 192 Os currently) and study eg. rotational alignments. Ga.Sp data (2001), Surrey, Legnaro et al. WNSL data, c. 1967
First Identification of 182 Yb: ISOL @ GSI 136 Xe @ 11.4 MeV/u on 186 W. Use GSI online mass-sep + tape- transport system to take A=182 isobars to Total Absorption Spectrometer (TAS). S. Al-Garni et al. Surrey/GSI/Liverpool
S. Al-Garni et al. Surrey/GSI/Liverpool) Yb (Z=70) X rays but lack of e - coincs? Implication: 1 min. isomer populates GSB in 182 Yb. (102, 228 keV) A=182
primary beam Pb @ 1GeV/u Production target Central focus, S2 Final focus, S4 E(Z 2 ) catcher degrader dipole, B scint MW=x,y scint (veto) Use FRS (or LISE3) to ID exotic nuclei. Transport some in isomeric states (TOF~ x00ns). Stop and correlate isomeric decays with nuclei id. eg. R. Grzywacz et al. Phys. Rev. C55 (1997) p1126 -> LISE C.Chandler et al. Phys. Rev. C61 (2000) 044309 ->LISE M. Pfutzner et al. Phys. Lett. B444 (1998) p32 -> FRS
33 ns isomer in 195 Os (last stable 192 Os), useful test of structure in prolate/oblate shape coexistence region. 194 Os Wheldon et al. Phys. Rev. C63 (2001) 011304(R) First id of ‘doubly mid-shell’ nucleus, 170 Dy (N=104, Z=66). K=6 + isomers predicted for well deformed N=104 nuclei. TRS calcs (F.Xu) predict a very ‘stiff’, highly deformed prolate nucleus. Could be the best K-isomer? Data from M.Caamano et al.
Other ways to get around the gamma-flash problem? Segmented germanium detectors and digital electronics for each individual segment. EURYSIS 6 x 6 germanium, Surrey/Liverpool/Darebury UK Gamma-Ray Tracking Project.