1 / 30

Nele Kesteloot

Coulomb excitation of 196,198,200,202 Po studied at REX-ISOLDE with the Miniball γ spectrometer. Nele Kesteloot

xiu
Télécharger la présentation

Nele Kesteloot

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Coulomb excitation of 196,198,200,202Po studied at REX-ISOLDE with the Miniball γspectrometer Nele Kesteloot B. Bastin, Y. Blumenfeld, N. Bree, P. Butler, E. Clement, J. Diriken, A. Dorsival, V. Fedosseev, L. Gaffney, T. Giles, T. Grahn, A. Herlert, M. Huyse, J. Iwanicki, J. Konki,T. Kröll, R. Krucken, B. Laurent, N. Lecesne, B. Marsh, P. Molkanov, E. Piselli, E. Rapisarda, P. Reiter, M. Scheck, M. Seidlitz, M. Seliverstov, M. Sferrazza, B. Siebeck, M. Sjodin, T. Stora, J. Taprogge, H. Tornqvist, E. Traykov, J. Van de Walle, P. Van Duppen, D. Voulot, N. Warr, F. Wenander, K. Wrzosek and M. Zielinska

  2. Outline • The polonium isotopes • The Miniballdetectionsetup • Experimentalcampaign • Preliminaryresultson196Po • X rays • Resultson200Po • Hg coulexresults • Future perspectives Isolde Workshop 2012

  3. The polonium isotopes The Miniballdetectionsetup Experimentalcampaign Resultson200Po Future perspectives Hg coulexresults The polonium isotopes A.M. Oros et al NPA 645:107 (1999) (π1h9/2)2 R. Julin et al JPG 27:R109 (2001) Shape coexistence Generalized seniority Change in nuclear structure T.E. Cocolios et al. PRL 106:052503 (2011) M.D. Seliverstov et al., in preparation N = 116 Transition expected around 200Po Isolde Workshop 2012

  4. The polonium isotopes The Miniballdetectionsetup Experimentalcampaign Resultson200Po Future perspectives Hg coulexresults Why Coulomb excitation? At Po Rn Z = 85 Z = 84 Z = 86 αdecay R. Julin et al, JPG 27 (2001) R109 K. Helariutta et al, EPJA 6 (1999) 289 A. Maj et al, NPA 509 (1990) 413 W. Younes et al, PRC 52 (1995) R1723 N. Bijnens et al, PRL 75 (1995) 4571 J. Wauters et al, PRL 72 (1994) 1329 In beam β decay N. Bijnens et al, PRL 75 (1995) 4571 Lifetimemeasurements T. Grahn et al, PRL 97 (2006) 062501 T. Grahn et al, PRC 80 (2009) 014323 Laser spectroscopy T.E. Cocolios et al PRL 106,052503 (2011) Coulomb excitation Isolde Workshop 2012

  5. The polonium isotopes The Miniballdetectionsetup Experimentalcampaign Resultson200Po Future perspectives Hg coulexresults The Miniball detection setup EP θP 200Po 570 MeV target 104Pd2 mg/cm2 ET Isolde Workshop 2012

  6. The polonium isotopes The Miniballdetectionsetup Experimentalcampaign Resultson200Po Future perspectives Hg coulexresults Kinematics Particle gamma eventsfor196Po on104Pd Counts /MeV/strip 196Po 104Pd Isolde Workshop 2012

  7. The polonium isotopes The Miniballdetectionsetup Experimentalcampaign Resultson200Po Future perspectives Hg coulexresults Typical gamma spectra Particle gamma events, Dopplercorrectedforprojectile 196Po on104Pd 198Po on94Mo 463 keV 2+0+196Po 605 keV 2+0+198Po 871 keV 2+0+94Mo 556 keV 2+0+104Pd 200Po on104Pd 202Po on94Mo 677 keV 2+0+202Po 556 keV 2+0+104Pd 666 keV 2+0+200Po 871 keV 2+0+94Mo Isolde Workshop 2012

  8. The polonium isotopes The Miniballdetectionsetup Experimentalcampaign Resultson200Po Future perspectives Hg coulexresults Preliminary results on 196Po: Gamma spectra Particle gamma events Doppler correctedforprojectile 891 4+ 859.1 2+ 196Po 558 0+ 463.1 2+ 104Pd 196Po 196Po Laser ON Laser OFF Xrays 0 0+ 196Po 196Po 196Tl 104Pd 196Tl 2-ground state7+isomer 196Po 196Po Isolde Workshop 2012

  9. The polonium isotopes The Miniballdetectionsetup Experimentalcampaign Resultson200Po Future perspectives Hg coulexresults Preliminary results on 196Po: X rays 891 4+ 859.1 2+ Conversion of observed196Po gamma rays X rays 558 0+ 463.1 2+ 0 0+ 196Po Conversion of observed196Tl gamma rays Atomic production of K vacancy in ion-atom collision Theoretical formula for cross section Use laser ON/OFF data Discrepancy between theory and experiment E0 transition 0+2 0+1 Empirical correction using 202Po Isolde Workshop 2012

  10. The polonium isotopes The Miniballdetectionsetup Experimentalcampaign Resultson200Po Future perspectives Hg coulexresults Results on 200Po • Analysis in final stage • BUT: on hold • Preliminary result for atomic X rays used • <0+1||E2||2+1> is stable • B(E2;0+2+) = 35(5) W.u. • <2+1||E2||2+1> is negative • Large uncertainty • Consistent with zero Isolde Workshop 2012

  11. The polonium isotopes The Miniballdetectionsetup Experimentalcampaign Resultson200Po Future perspectives Hg coulexresults B(E2) values in 182,184Hg 182Hg 184Hg N. Bree, K. Wrzosek-Lipska private communication Isolde Workshop 2012

  12. The polonium isotopes The Miniballdetectionsetup Experimentalcampaign Resultson200Po Future perspectives Hg coulexresults Quadrupole sum rules method Overall deformation Triaxiality • Oblatedeformation of ground state • Excited 0+2 is more deformedthanground state • 0+2 state canbetriaxiallydeformed in 184Hg AHg AHg D. Cline, Ann Rev Nucl Part Sci 36 (1986) 683 N. Bree, K. Wrzosek-Lipska private communication Isolde Workshop 2012

  13. The polonium isotopes The Miniballdetectionsetup Experimentalcampaign Resultson200Po Future perspectives Hg coulexresults Future perspectives • Experimental campaigns (2009 and 2012) very succesful • Analysis will yield a lot of information • B(E2;0+2+) values of 196,198,200,202Po • Quadrupole moments of first 2+ state in 196,198,200,202Po • Comparison of our B(E2;0+2+) value for 196Po with result from lifetime experiment T. Grahn et al, PRC 80 (2009) 014323 • Parasitic information on196Tl • Resultswillbecompared to theoretical models • Beyondmean field calculations • Symmetryguided models Isolde Workshop 2012

  14. Thank you for your attention!

  15. Parasitic data on 196Tl 394.2 7+ Single gamma spectrum 0 2- 196Tl 5-,6,7- 2346 505 426 keV 7- 1841 5- 1757 695 Counts/keV 1061.6 4+ 635 keV 505 keV 1036.2 1+,2+ 695 keV 635 611 2+ 426.3 426 611 keV 0 0+ 196Hg Energy (keV) Isolde Workshop 2012

  16. Extracted matrix elements in 182-186Hg Isolde Workshop 2012

  17. Extracted matrix elements in 182-186Hg Isolde Workshop 2012

  18. 196Tl level scheme Isolde Workshop 2012

  19. 196Tl decay Isolde Workshop 2012

  20. Ranges in Gosia Particle detector Obtain sensitivity on the diagonal matrix element of the first excited state by scanning the center of mass range! Isolde Workshop 2012

  21. Coincidence spectrum Isolde Workshop 2012

  22. Summary of information Isolde Workshop 2012

  23. Unobserved transitions: upper limits • Upper limit = number of counts that would give rise to a peak above the background • Same integration window as in main peak (30 keV) • UPL = N + 3σ • Correct for detection efficiency 611keV transition:UPL = 587 cts 666 keV transition:N = 8.31(10).103 cts Isolde Workshop 2012

  24. First order solution in Gosia 2 • Disregard X rays and higher lying states • Normalize projectile to target excitation • <0+||E2||2+> = 1.03(8) eb • <2+||E2||2+> = 0.55 eb • = starting point for Gosia 1 2+ 666 8.79(10).104 0+ 200Po <2+||E2||2+> [eb] 2+ 556 1.762(15).105 0+ <0+||E2||2+> [eb] 104Pd Isolde Workshop 2012

  25. Gosia 1 • Gosia input • 6 experiments • 5 experiments for 5 angular ranges (no X rays) • 6th experiment with total yield for 2+0+ and X rays • 6 states • Virtual 1+ state to simulate E0 transition • 2 buffer states • 9 data points • 7 yields • 1 known branching ratio • 1 known matrix element (<0+||E2||2+> = 1.03(8) eb) • 7 free matrix elements • Couple <0+1||E2||2+1> and <2+1||E2||4+1> • Treat virtual M1 matrix elements as one matrix element Isolde Workshop 2012

  26. Gosia 1: solutions Isolde Workshop 2012

  27. The polonium isotopes The Miniballdetectionsetup Preliminaryresultson196Po X rays Resultson200Po Future perspectives Atomic production of K-vacancy in ion-atom collision • Theoretical formula • Empirical correction • Based on experimental data in Po region • Comparison with 188Hg coulex data • Geometrical correction • Range of particle detector • Estimate: 5.6(21).103 J.D. Garcia et al, RMP 45 No 2 (1973) 111 Range particle detector Method: N.Bree 2010 Isolde Workshop 2012

  28. The polonium isotopes The Miniballdetectionsetup Preliminaryresultson196Po X rays Resultson200Po Future perspectives Gosia analysis E0 Unobserved Upper limit Conversion coefficient BR=1.16(42) 5944 • Normalisation to target excitation • Virtual 1+ state • Buffer states 0.11 α=0.11 1086 1715 α=0.01479 5944 18112 1.3(2).104 α=0.0126 8.8(1).104 Gosia: T. Czosnkyka, D. Cline, C.Y. Wu Bull. Amer. Phys. Soc. 28, 745 (1983) Isolde Workshop 2012

  29. The polonium isotopes The Miniballdetectionsetup Preliminaryresultson196Po X rays Resultson200Po Future perspectives Preliminary results of the Gosia analysis • Gosia 1 & 2 analysis in progress • <0+1||E2||2+1> is stable • B(E2;0+2+) = 35(5) W.u. • <2+1||E2||2+1> is negative • Large uncertainty • Consistent with zero Isolde Workshop 2012

  30. The polonium isotopes The Miniballdetectionsetup Experimentalcampaign Resultson200Po Future perspectives Hg coulexresults X rays Particle particle gamma events Doppler corrected for projectile = 202Po 1302.5 2+ 1248.6 4+ 677.2 2+ Xrays 0 0+ 202Po 202Po 94Mo Isolde Workshop 2012

More Related