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Hunting for the long-lived isomer 188 Hf

Investigating isomer 188Hf, key to ground-state phase transition, high-K state coupling schemes, and new mass discoveries. Utilize ESR and Schottky spectroscopy in CERN experiments.

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Hunting for the long-lived isomer 188 Hf

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  1. Hunting for the long-lived isomer 188Hf Kulikov Ivan December 2017, CERN

  2. Motivation N=116 is critical point for ground-state prolate-oblate phase transition Schematic angular-momentum coupling schemes of high-K state in a deformed nucleus, where, in the absence of collective rotation (R), the total particle angular momentum (J) would precess around the nuclear symmetry axis. G.D. Dracoulis et al., Rep. Prog. Phys. 79 (2016) 076301

  3. Motivation ▪ ● □ ○ experiment calculated 186Hf (N=114), 188Hf (N=116): combination of high spin and low energy half-lives of minutes expected Dracoulis, Walker, Kondev, Rep. Prog. Phys. 79 (2016) 076301

  4. Advantages The identification of isomeric states in the ESR is an indispensable complementary approach to the conventional γ –spectroscopy. The latter is very efficient for searching isomers with half-lives of below about a second, whereas the Schottky spectroscopy does not have an upper lifetime limit for such investigations.

  5. Tools Storage Ring ESR Linear Accelerator UNILAC Fragment Separator FRS Production target Heavy-Ion Synchrotron SIS

  6. Tools 1036 mg/cm29Be 220 mg/cm2Nb backing Shottky mass measurement magnetic setting of FRS-ESR Bρ= 8.1 Tm 208Pb beams with energy 471 MeV/u

  7. Productiontarget 188Hf Excited fragment Heavy-Z projectile ɣ p 9Be n 208Pb Low-Z target p ɣ Fragmentation

  8. Fragment Separation Bρ–ΔE–Bρ in-Flight separation H. Geissel, et al., Physics Research B70 (1992) within ~ 150 ns

  9. electron collector electron gun high voltage platform electron beam magnetic field ion beam ESR Schottky Mass Spectrometry

  10. E122 184Hf A = 184, q = 72+ m2 g Ta bare (single ions) 0 Hf 2.5 MeV 10-second snapshots time (minutes) 10 2.5 MeV T1/2 ≈ 12 min 20 frequency ● first observation of m2 isomer ● long-lived β-decaying isomer Reed et al., Phys. Rev. Lett. 105 (2010) 172501

  11. Conclusion 19 new masses of nuclides

  12. Thanks Os 190 Os 191 Os 195 Os 192 Os 194 Os 193 Os 189 Os 188 Os 196 Re 189 Re 190 Re 194 Re 191 Re 193 Re 192 Re 188 Re 187 W 188 W 189 W 190 W 192 W 191 W 187 W 186 Nuclideswithunknownmasses Ta 187 Ta 188 Ta 189 Ta 191 Ta 190 Ta 186 Ta 185 Hf 186 Hf 187 Hf 188 Hf 190 Hf 189 Hf 185 Hf 184 188Hf isomer

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