Exotic neutron-rich nuclei Phil Walker University of Surrey production reactions angular momentum structure decay
Chart of nuclides I K
4-quasiparticle K-isomers in hafnium (Z=72) 178Hf 188Hf expt. calc. stability Walker and Dracoulis, Hyp. Int. 135 (2001) 83
190W116 anomaly Podolyak et al., Phys Lett B491 (2000) 225
prolate-oblate shape change 190Re115 192Re117 188Ta115 190Ta117 Total Routhian Surfaces: Walker and Xu, Phys Rev C74 (2006) 067303 Walker and Xu, Phys Lett B635 (2006) 286 Projected Shell Model: Sun, Walker, Xu and Liu, Phys Lett B659 (2008) 165 Stevenson separable interaction: Stevenson et al., Phys Rev C72 (2005) 047303
Projectile-fragmentation reactions at GSI ion-by-ion mass and charge identification in the FRS Ge detectors isomers and ground states reach the final focus in ~300 ns
RISING at GSI: 105 Ge crystals
Steer et al., submitted to PRL 204Pt Steer et al., submitted to PRL
Passive Stopper measurements: g-rays from isomer with T1/2 for 10 ns 1 ms. Active Stopper measurements: b -particles, i.c. electrons, T1/2 ms →mins
Active Stopper Spectroscopy of 205Au Podolyak et al., submitted to PLB T1/2 = 10.4 s K-electrons L-electrons T1/2Weiss(E3(94)) = 7.49 s T1/2Weiss(M4(921)) = 10.6 s Eg(exp)(11/2-3/2+) = 912 keV B(M4; 11/2- 3/2+) = 0.95 W.u. Direct measure of h11/2→d3/2 proton hole energy difference
β decay with active stopper: N. Alkhomashi, P. H. Regan et al β decay with active stopper: N. Alkhomashi, P.H. Regan et al., to be published 188Ta → 188W 190Ta → 190W 192Ta → 192W
Nuclei of focus in the A~200 region for Active Stopper measurements 203,205,(206)Au 213Bi 204Pt 198,202Ir 200Os 194,196,198Re 190,192Ta Spokespersons: P.H. Regan & J. Benlliure Analysis by N. Alkhmashi, N. Al-Dahan, G. Farrelly, A. Morales et al.,
Fragment Separator coupled to Experimental Storage Ring at GSI isomer ground state [Attallah et al., Nucl. Phys. A701 (2002) 561c]
potential for new isomers and ground-state masses with storage rings at FAIR
neutron radioactivity unique to isomers? n high-spin isomer threshold A – 1 + n gs A β NB: mono-energetic neutrons ~1MeV
Coulomb and centrifugal barriers
the angular-momentum dimension with 238U projectile fragmentation Rexp = 7% 3% 215Ra 214Ra 15 times more than expected new data 148Tb 27 ħ spin (ħ) see also: Pal and Palit Phys. Lett. B665 (2008) 164 [Podolyak et al., Phys. Lett. B632 (2006) 203]
Exotic neutron-rich nuclei focus on A ~ 190 – 210 shell gaps r-process nucleogenesis shape changes projectile-fragmentation reactions isomer spectroscopy gamma-ray detection conversion-electron detection storage-ring observation (neutron radioactivity) (high-spin population) thanks to: Paddy Regan Zsolt Podolyak and many others