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Exotic neutron-rich nuclei

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Presentation on theme: "Exotic neutron-rich nuclei"— Presentation transcript:

1 Exotic neutron-rich nuclei
Phil Walker University of Surrey production reactions angular momentum structure decay

2 Chart of nuclides I K

3 4-quasiparticle K-isomers in hafnium (Z=72)
178Hf Hf expt. calc. stability Walker and Dracoulis, Hyp. Int. 135 (2001) 83

4 190W116 anomaly Podolyak et al., Phys Lett B491 (2000) 225

5 prolate-oblate shape change
190Re115 192Re117 188Ta115 190Ta117 Total Routhian Surfaces: Walker and Xu, Phys Rev C74 (2006) 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)

6 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

7 RISING at GSI: 105 Ge crystals

8 Steer et al., submitted to PRL
204Pt Steer et al., submitted to PRL

9

10 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

11 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

12 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

13 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.,

14 Fragment Separator coupled to Experimental Storage Ring at GSI
isomer ground state [Attallah et al., Nucl. Phys. A701 (2002) 561c]

15 potential for new isomers and ground-state masses with storage rings at FAIR

16 neutron radioactivity
unique to isomers? n high-spin isomer threshold A – 1 + n gs A β NB: mono-energetic neutrons ~1MeV

17 Coulomb and centrifugal barriers

18 the angular-momentum dimension with 238U projectile fragmentation
Rexp = 7% % 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]

19 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


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