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Precision mass measurements of n-rich nuclei between N=50 and 82.

Precision mass measurements of n-rich nuclei between N=50 and 82. Juha Äystö Department of Physics, University of Jyväskylä , Finland Helsinki Institute of Physics, Helsinki, Finland. Short overview on the experimental approach Penning trap mass measurements on n-rich nuclei

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Precision mass measurements of n-rich nuclei between N=50 and 82.

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  1. Precisionmassmeasurements of n-richnucleibetween N=50 and 82. JuhaÄystöDepartment of Physics, University of Jyväskylä, Finland Helsinki Institute of Physics, Helsinki, Finland • Short overview on the experimental approach • Penning trap mass measurements on n-rich nuclei • Impact of improved knowledge of masses • Fine structure of mass surface vs. nuclear structure • two-neutron separation energies • odd-even staggering and pairing • Conclusions and outlook

  2. RIs (T1/2≈100 ms)

  3. Penningtrap • Split ring electrode: • Dipolar RF • Quadrupolar RF • Coupling at nc • Homogenous B, quadrupolar V • Three eigenmotions • Axial (nz) • Magnetron (n- = 1 kHz) • Modified cyclotron (n+ =1 MHz) SIDEBAND MASS SPECTROMETRY:

  4. JYFLTRAP @ IGISOL3fastuniversalmethod • RFQ + 2 Penning traps • Isobaric/-meric cleaning • Mass measurements -fast, universal T. Eronen et al., Eur. Phys. J. A 48 (2012) 46

  5. Beam purification • Sideband cooling technique (G. Savard et al., Phys. Lett. A 158 (1991) 247) • R = M/DM up to 105

  6. Precision trap – TOF-ICR

  7. JYFLTRAP massmeasurements SnSbTe rp, νp process 3. 132Sn region 58Ni 2. N≈60 subshell 0+→ 0+IMME mirror 1. N=50 shellclosure • Nuclear structure • Nuclear astrophysics (r process) • Fundamentalsymmetries ~0.1…20 keV precision (10-9…10-7)

  8. Production in p-fissionrefs.: V. Rubchenya, J. Äystö, Eur. Phys. J. A 48 (2012) 44H. Penttilä et al., Eur. Phys. J. A 48 (2012) 43 45Rh 60 62 64 66 68 70 72

  9. Differencebetween 2003 mass data from the PT data From a reviewby A. Kankainen, J. Äystö and A. Jokinen, J. Phys. G. submitted 2012. =(N-Z)/2

  10. deformed N=60 region JYFLTRAP TITAN; new ISOLTRAP

  11. Chargeradii and two-neutronbindingenergies

  12. S2nversusprotonnumber

  13. Neutron-rich masses close to 132Sn J. Hakala, J. Dobaczewski et al., submitted to PRL (2012); arXiv:1203.0958 Isomers! (T1/2 > 100 ms) T1/2 ≈100 ms Agreement with ISOLTRAP data Is PERFECT! ISOLTRAP JYFLTRAP

  14. Evolution of shellstructure at Z=50 and N=82 Two-protonshellgap for Z=50 Two-neutronshellgap for N=82 50 Shell gap 82

  15. …theory vs. experiment ? Correlationsareveryimportant !! M. Bender, G. F. Bertsch, and P.-H. Heenen. Global study of quadrupole correlation effects. Phys. Rev. C, 73 (2006) 034322 S. Goriely, N. Chamel, and J. M. Pearson Skyrme-Hartree-Fock-Bogoliubov nuclear mass formulas: Crossing the 0.6 Mev accuracy threshold with microscopically deduced pairing. Phys. Rev. Lett., 102 (2009)152503

  16. Odd-evenstaggering (OES);a measure of empiricalpairinggap 3-point formula OES mostlydepends on the intensity of nucleonic pairing correlations in nucleibut is also affected by the polarisationeffects! OES(Nodd) measure of pairingeffects OES(Neven)  impactedbysingle particlestatesaround Fermi level

  17. d5/2 g7/2

  18. Odd-evenstaggeringacross the N=82 shellclosure J. Hakala, J. Dobaczewski et al., arXiv:1203.0958

  19. Our QRPA calculationsreproduce the behavior seen in experiment. We trace the cause to the difference in neutron pairing below and above N=82. Coulomb Excitation of Radioactive 132,134,136Te Beams and the Low BE2 of 136Te PHYSICAL REVIEW LETTERS 88 (2002) 222501 D. C. Radford,et al.

  20. Sphericalself-consistentcalculationusing Sly4 energydensityfunctional plus contactpairing Dobaczewski, Flocard, Treiner, Nucl. Phys. A 422(1984)103 Conclusion: The N=81-83 asymmetry in staggeringindicates - exclusion of pure surfacepairingforce - significantrole for polarizationeffects for Te and Xe!

  21. 1 mb 1 mb

  22. Fall of 2012: IGISOL and JYFLTRAP willoperate @ MCC30 & K130 cyclotrons Specialissue for IGISOL Science Laser hut Penningtraps RFQ-buncher

  23. Summary • Our knowledge of binding energies of neutron-rich nuclei has experienced a major revision during the last five years due to Penning-trap technique • Long isotopic chains from Ni to Pr , excluding iodine, measured at three Penning trap facilities: Jyvaskyla, CERN-ISOLDE and Argonne • Masses of over 300 nuclides produced in fission with  uncertainties of 10 keV or less have become available. • The present data set provides: • A challenge for future development of mass models and theories • Higher sensitivity to reveal shape transitions and (sub)shell closures by mass differentials • A new tool to study odd-even staggering of binding energy as a probe for pairing effects in n-rich nuclei (in particular close to drip-line!)

  24. Thank you for your attention! …and T. Eronen, A. Kankainen, A. Jokinen and colleagues at

  25. masses vs. twodifferentr-processpaths P.A. Seeger, W.A. Fowler, and D.D. Clayton. Nucleosynthesis of heavy elements by neutron Capture, Astrophys. J. Suppl. Ser., 11:121, 1965. V. Bouquelle, N. Cerf, M. Arnould, T. Tachibana, and S. Goriely. Single and multi-event canonical r-process, Astron. Astrophys., 305:1005, jan 1996.

  26. Ion Guide (Light ion induced fusion) Ions. Atoms too,but they’re lost.

  27. Continuous RF excitation 200 ms 131In states g.s: 9/2+, 280 ms 1/2-, 302(32) keV, 350 ms 21/2+, 3764(88) keV, 320 ms Purificationcycles + pulsed RF excitation 25-150-15 ms JYFLTRAP result: E*(1/2-)=365(8) keV To bepublishedby A. Kankainen et al. (1/2-)

  28. Isomers can be separated (500 ms) T. Eronen et al., NIM B 266 (2008) 4527 1.7 Hz, 233 keV/c2

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