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Spins, Moments and Charge Radii Beyond 48 Ca INTC-P-313. M.L. Bissell - On behalf of COLLAPS . Program initiated with IS-484 - “ Ground-state properties of K-isotopes from laser and β -NMR spectroscopy ” Extended with I-117 - “Moments, Spins and Charge Radii Beyond 48 Ca.”

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## Spins, Moments and Charge Radii Beyond 48 Ca INTC-P-313

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**Spins, Moments and Charge Radii Beyond 48CaINTC-P-313**M.L. Bissell - On behalf of COLLAPS**Program initiated with IS-484 - “Ground-state properties**of K-isotopes from laser and β-NMR spectroscopy” Extended with I-117 - “Moments, Spins and Charge Radii Beyond 48Ca.” Substantial theoretical interest and recent developments encourage us to bring forward part of this program Background**Whilst β-decay spectroscopy, deep inelastic scattering and**Coulomb-excitation experiments have all provided evidence for a sub-shell closure at N=32, no direct experimental evidence exists for such a closure at N=34. New magic numbers N = 32, 34 Maierbecket al., Phys. Lett. B 675, 22 (2009) -> 55Ti has a 1/2−ground state. GXPF1A predicts this , KB3G predicts 5/2 − A.Gade, T. Glasmacher, Progress in Particle and Nuclear Physics 60, 161–224 (2008) 54Ca is “the key nucleus for a search for the new magic number N=34.”**Gaute Hagen (Oak Ridge) :**“ I think it would really great idea for a proposal to measure the neutron rich calciums. We can within coupled-cluster theory compute radii, masses, spectra and moments of 39,40,41,47,48,49,51,50,52,53,54,55,59,60,61Ca. So basically its only a few calciums we cannot compute at the moment. To have experiments measure radii and moments of the n-Ca would be of really huge interest for the theory community and provide tests for ab-initio approaches. ” Ca: An ideal testing ground for theory**Existing charge radii of Ca are probably the most**theoretically investigated of any isotopic chain: Ca: An ideal testing ground for theory I.Talami, Nucl. Phys. A 423, 189 (1984) -> Linear + Parabolic + OES Each of these terms related to particular components of the interaction used.**Fe -> Normal OES**Mn -> Downturn at N=31 but could be just OES. IS-508 will extend this beyond N=32 Charge radii beyond 48Ca K -> Preliminary results indicate a downturn at N=32. Statistics to be improved.**Yields**Only old SC yields available on the database: 49Ca 2.5x105 /uC Old design UCx 49Ca 1.4x107 /uC Ta (Should be equivalent to new UCx) 51Ca 1.0x104 /uC Ta powder (last yield measurements for 51K claimed we had approximately equal amount of K and Ca) 52Ca 1.0x102 /uCT. Stora- Yield will be 1 order of magnitude higher than this. (All yield measurements at the PSB have been in the 1x103 range.) + Possible factor of 10 from RILIS**Stage 1 – Optical detection**Optical detection efficiency for K improved from 1 : 300 k to 1 in 20 k + low background . ∫η(new) dx / ∫η(existing) dx ≈14 For Cd we observed 1 in 6k -> 1 in 4k for Ca**What is possible?**Strong ionic J=1/2 to J=3/2 393.4 nm transition. 4 shifts on 52Ca with 1k ions /μC 3 Such spectra required to reduce systmatics + 5 shifts for 51Ca + 1 shift for 49Ca + 3 offline shifts directly prior to the run for stable measurements. Stage 1 total 18 online shifts + 3 offline.**Stage 2 – Radioactive detection**Radioactive detection of Optically pumped ions after state selective Charge exchange (ROC) The theoretical possibilities: 1 ion/s of an even isotope over 5 shifts. An additional 18 shifts53,54Ca**Why is stage 2 stage 2?**• ROC is not ideally suited to odd cases. We must introduce multiple pumping. • In the previous setup it was not possible to reliably focus both the ion and atom beam onto the detectors. -> Shutdown will be an ideal time to develop this.**Summary of Request**• Stage 1 – Investigation of N=32 • 18 shifts withUCx and RILIS prior to shutdown . • Stage 2 – Investigation of N=34 • 18 shifts with UCx and RILIS after the shutdown .**Collaboration**M. L. Bissell,1K. Blaum,2 I. Budincevic,1 N.Frömmgen,3 R.F. Garcia Ruiz,1 Ch. Geppert,3 M. Hammen,3 M. Kowalska,4 K. Kreim,2 P. Lievens,5 R. Neugart,3 G. Neyens,1 W. Nörtershäuser,3 J. Papuga1, M.M. Rajabali1 and D. T. Yordanov4

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