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Structure of Potassium and Calcium isotopes studied by Collinear Laser Spectroscopy

This study delves into the structure of potassium and calcium isotopes through Collinear Laser Spectroscopy, presenting selected results and conclusions. The technique detects resonantly excited ions, measures hyperfine splitting, and determines key properties of exotic isotopes. Motivated by interactions beyond N=28, the research focuses on the evolution of proton and neutron orbits in K and Ca isotopes, showcasing precise measurements and revealing insights into their nuclear structure. By examining magnetic moments, g-factors, and charge radii, the study sheds light on the behavior of odd isotopes and the magicity at N=32 and N=34. Model-independent approaches and theoretical calculations enhance the understanding of these isotopes, offering valuable contributions to nuclear physics research.

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Structure of Potassium and Calcium isotopes studied by Collinear Laser Spectroscopy

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  1. Structure of Potassium and Calcium isotopes studied by Collinear Laser Spectroscopy Gerda Neyens ISOLDE WORKSHOP 2014

  2. Collinear laser spectroscopy Motivationtostudy K and Ca region Selectedresultsfor K isotopes Selectedresultsfor Ca isotopes Conclusions and outlook

  3. Collinear laser spectroscopy at CRIS at COLLAPS detect a resonantlyexcited ion continuum Hyperfine splitting (100 MHz) atomic excited state λ2 second step laser photon laser photon (eV – 108 MHz) excited state detect fluorescence photons Hyperfine splitting atomic ground state λ1 laser photon Atomic ground state • low background • bunchedbeams • new detectionsystem • high resolution (~ 50MHz) • needabout 10.000 ions/s from ISOLDE • atoms or ions • very low background • high resolution (~ 30 MHz) • (seeposter 36 byR. De Groote) • needabout 100 ions/s from ISOLDE • atoms (and ions)

  4. Collinear laser spectroscopy Measure in a model-independent way 4 properties of anexoticisotope/isomer: - the nuclear spin I - the magneticdipole moment m - the electricquadrupolemoment Q (ifelectronic and nuclear spin J,I>1/2) - the isotope shift  nuclear charge radius byresonantexcitation of hyperfine transitions in anatom or ion. J. Papuga et al., PRL 110, 172503 (2013)

  5. Motivation: p-n interaction beyond N=28 p-n interaction in N=Z Stable isotopes Ca Z = 20 Experiment K Z = 19 N=Z N = 32 N = 28 Neutron orbits 40 Proton orbits 1f5/2 2p1/2 N = 20 32 2p3/2 28 1f7/2 40 20 20 1d3/2 2s1/2 28

  6. K-isotopes: sensitive to the evolution of proton orbits 2753 2788 2p3/2 2522 1/2+ 1f7/2 20 20 1d3/2 2s1/2 Excitation energy [keV] 980 975 855 715 672 561 474 334 345 3/2+ NR U Exp. NR U Exp. NR U Exp. NR U Exp. 45K 41K 43K 39K Otsuka et al., PRL 87, 2001, 082502 Otsuka et al., PRL 95, 2005, 232502 I = 3/2 strong attractiveinteractionbetweenp1d3/2 and n1f7/2  gap betweenpd3/2 and ps1/2 decreases

  7. K-isotopes: sensitive to the evolution of proton orbits 2753 2788 2522 1f7/2 • I=1/2 becomes g.s. in 47K Excitation energy [keV]  What if n2p3/2 gets filled ?? 980 975 855 715 672 561 466 474 360 334 345 312 320 74 78 81 ? ? Exp. NR U Exp. NR U NR U Exp. NR U Exp. NR U Exp. NR U Exp. NR U Exp. 49K 51K 45K 47K 41K 43K 39K 2p3/2 1d3/2 interactionstrongestbetween2s1/2and 2p3/2 2s1/2 I = 1/2 Touchard et al., PLB 108 (1982) 169 1/2+ 3/2+

  8. Ca-isotopes: sensitive to the neutron orbits, are N=32 and N=34 magic ? Nature 502 (2013) 207 Nature 498 (2013) 347 • Energy of 2+ state in even Ca establishes • magicity at N=32 and N=34 • massmeasurements up to N=34 establish • magicity at N=32

  9. RESULTS Ip=1- Ip=7/2- Ip=1/2+ Ip=3/2- Ip=3/2- Ip=0- Ip=3/2+ K. Kreim et al., PLB 731, 97 (2014) R. F. Garcia Ruiz et al., submitted to PRC

  10. Magneticmoments and g-factors of odd K • 47, 49K dominatedby hole in s1/2orbit • 49K wave functionstrongly mixed with d3/2 Calculations: SDPF-MU, Utsunoet al., PRC 86 (2012) SDPF-NR and SDPF-U, Nowacki, Poves, PRC79(2009) sdforprotons pffor neutrons J. Papuga et al., PRL110, 172503 (2013)

  11. Occupation of ps1/2 and pd3/2 as function of N 28 20 1d3/2 2p3/2 Only at N=28 and N=30 inversion of proton level occupations 1f7/2 fullyoccupied 1d3/2 1d3/2 hole in d3/2 (normal) 2s1/2 hole in s1/2 (inverted) J. Papuga et al., PRC90, 034321 (2014)

  12. Evolution of proton s1/2-d3/2gap throughDE(1/2+-3/2+) Model-independent determination of g.s spin of 49K = ½+, 51K = 3/2+ N Shell model with effective interactions Ab initio (Gorkov-Green`s function) V. Somà, T. Duguet and C. Barbieri tobemeasured ! J. Papuga et al., PRC90, 034321 (2014)

  13. Isomer shift of 38g,mK: effect of p-n correlations at N=Z 1f7/2 • increased radius • dueto 1p-1h • p and n excitations • in the 0+ state 38Km Ip=0+ 20 20 Proton Neutron Ip=3+ 38Kg 1d3/2 2s1/2 0+ 38Kg charge radius relativeto38Kg 38Km 3+ Frequencyrelativetocentroid of 38Kg (MHz) M.L. Bissell et al., PRL113 (2014) 052502

  14. Root mean square charge radii from Z=18 to Z=26 charge radii relativeto N=28 Fe Mn Cr Ti Ca Sc K Ar • strong Z-dependence below N=28 • little Z-dependenceabove N=28 • no signature of ‘magicity’ at N=32 K. Kreim et al., PLB 731, 97 (2014)

  15. Spin determination of 51Ca: I=3/2 From the constant ratio of hyperfine parameters: A(S1/2) / A(P3/2) = const. 1f7/2 • onlyfor I=3/2 the ratio fits correctly • for49Ca and 51Ca 51Ca, I=3/2 2p3/2 photoncounts R. F. Garcia Ruiz et al., submitted to PRC frequency (MHz)

  16. g-factor of odd-A Ca: sensitive to odd neutron 39Ca 2p3/2 1f7/2 20 20 1d3/2 2s1/2 Effectivesingle-particleg factor R. F. Garcia Ruiz et al., submitted to PRC

  17. g-factor of odd-A Ca: sensitive to odd neutron 41Ca ------ 47Ca 2p3/2 1f7/2 20 20 1d3/2 2s1/2 Effectivesingle-particleg factor R. F. Garcia Ruiz et al., submitted to PRC

  18. g-factor of odd-A Ca: sensitive to odd neutron 49Ca 51Ca 2p3/2 1f7/2 20 20 1d3/2 2s1/2 2p1/2 51Ca mixing with configurations from higher n(pf) orbits Effectivesingle-particleg factor R. F. Garcia Ruiz et al., submitted to PRC

  19. Magnetic moments of odd-Ca: probing the wave function and testing nuclear theories. • Alltheoriesfail below N=25 • (needexcitationsacross N,Z=20) • goodreproductionfor47,49,51Ca • largermixing in 51Ca wave function • with NN+3N calculations Quadrupole moments of odd-Ca: follow seniority scheme when filling f7/2 and p3/2 orbits  confirms dominant single particlebehavior R. F. Garcia Ruiz et al., submitted to PRC

  20. Charge radii of Ca isotopes  no signaturefor shell closure at N=32 ? to be published

  21. Conclusions and outlook • K isotopes: • magneticmoments, spins and charge radii measured up to N=32 • no Q-moments (small) • re-inversion (back tonormal) of proton levels beyond N=30 • enhanced p-n correlations at N=Z • Ca isotopes: • magneticmoments, spins and radii measured up to N=32 • Q-moments of allodd-even isotopes up to N=31 • g-factors reveallessmagicity at N=32 than at N=28 • Q-momentsreveal dominant single-particlebehavior • radii do not show evidenceformagic N=32  extendmeasurementsto N=34 ! • recent resultson Mn isotopes: seeposter 34 by H. Heylen

  22. J. Papuga, R. Garcia Ruiz, H. Heylen, W. Gins, M. Bissell, G. Neyens K. Kreim, K. Blaum, R. Neugart R. Sanchez, C. Geppert, L. Grob, N. Frommen, W. Nörtershäuser D. Yordanov, M. Kowalska Thank you for your attention!

  23. Setup – Ion beam ISOLDE (Isotope Separator On-Line DEvice) Surface Ion Source HRS (High Resolution Separation) (1.4 GeV)

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