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Fragment Separator and Spectroscopic Analysis of Nuclei with 208Pb and 212Pb Ions

This study addresses the production and spectroscopic analysis of exotic nuclei around 208Pb and implanted 212Pb ions. Focus is placed on fragmentation and fission decay studies, examining both internal isomers and beta decay patterns. Experimental methods include passive and active stopper techniques with various beam types (208Pb and 238U). Key findings involve the energies, transition rates, and shell-model calculations for isotopes such as 205Au, 202Os, and nuclei near the N=126 shell closure. The work highlights the importance of improved measurements and future experimental setups.

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Fragment Separator and Spectroscopic Analysis of Nuclei with 208Pb and 212Pb Ions

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  1. Structure close to 208Pb Zsolt Podolyák

  2. The fragment separator 370 implanted 212Pb ions! Time from production to spectroscopic analysis: ~ 300 ns fragmentation or fission Decay studies: -internal (isomers) -beta decay M. Pfützner et al., Phys. Lett. B 444 (1998) 32. Very sensitive method

  3. ‘passive stopper’ experiments Exp. #3: 238U beam Exp. (test) #2: 238U beam Experiment #1 208Pb beam 208Hg, 209Tl Spokesperson: #1,2 Zs. Podolyák, #3 J.J. Valiente-Dobon, G. Benzoni Analysis by S. Steer (N<=126), N. Al-Dahan (N>126), T.Swan (σ)

  4. ‘active stopper’ experiments 208Pb beam 203,205,(206)Au 198,202Ir 200Os 194,196,198Re 190,192Ta Spokespersons: P.H. Regan & J. Benlliure Analysis by N. Alkhomashi, N. Al-Dahan, G. Farrelly, A.I. Morales et al.,

  5. N=126 nuclei below 208Pb (what was known) + 207Tl: D. Eccleshall, M. J. L. Yates, Phys. Lett. 19, 301 (1965). 206Hg: B.Fornal et al. Phys. Rev. Lett. 87(2001) 212501. Z=81 Z=80 Z=79 Z=78

  6. Particle identification GSI

  7. 204Pt 205Au 203Ir

  8. 205Au: three proton-hole nucleus Active stopper exp. Gammas Charged particles Zs. Podolyák et al., Phys. Lett. B 672 (2009) 116.

  9. Shell-model calculations (M.Górska, H.Grawe, H. Maier, A.Brown) • and (d):TBME from L.Rydstrom et al, NPA512(1990)217 (based on Kuo-Brown interaction) • (b) and (c): three TBMEs modified • Δ(d3/2 h11/2; d3/2 h11/2)7- = +135 keV • Δ(s1/2 d5/2; s1/2 d5/2)2+,3+ =+230 keV (monopole only) • Δ(d3/2 h11/2; s1/2 h11/2)6- changed to +0.160 MeV (fit for B(E2) • Good description of energies and B(EL)s S.Steer et al., Phys. Rev C78 (2008) 061302(R)

  10. 205Au πh11/2-2 s1/2-1 Orig. SM Mod. SM πh11/2-1 s1/2-2 πd3/2-1 s1/2-2 B(E2): 3.1 1.2(2) 1.7 W.u. Calc. H. Grawe

  11. 203Ir Mod. SM Orig. SM

  12. Future: further ‘down’ along the N=126 line (acc. exp.) 205Au: beta decay from 205Pt => will fix the πs1/2 orbital 203Ir: beta decay from 203Os (νg9/2) => will fix the πd3/2,πs1/2,πh11/2 202Os: isomeric decay I=(5),(7),(10) 202Os: beta decay of 203Ir (νg9/2) 8+ 2685 10+ 2673 8- 2558 5- 1932 7- 1893 shell model 4+ 1555 2+ 1181 202Os 0+ 0

  13. N>126, Z<82 nuclei (238U beam) Δq=0

  14. 206Hg 208Hg 209Tl N. Al-Dahan et al.

  15. Shell-model calc. (H. Grawe) TBME: from E.K. Warburton, PRC44, (1991) 233; are based on the Kuo-Herling realistic int. Single particle energies: 207Tl and 209Pb exp.

  16. ( νg29/2) states; 2+ mixed with πs-11/2d-13/2 B(E2)=1.22 W.u. SM B(E2)=1.95(39)-1.58(22) W.u. exp.

  17. 209Tl: Isomer: 17/2+; ( νg29/2) (πs-11/2) B(E2)=0.96 W.u. SM B(E2)=1.87(22)-1.51(18) W.u. exp. 17/2+->13/2+Δ 13/2+->9/2+ 137 keV 9/2+->7/2+Δ, allowed M1 7/2+->3/2+ 661 keV 3/2+->1/2+ 324 keV E2(+M1) 209Tl: previously from (t,α) and alpha decay. (t,α): C. Ellegaard, P.D. Barnes and E.R. Flynn, Nucl. Phys. A259 (1976) 435.

  18. N>126, Z<82 nuclei Mass measurement of 208Hg (GSI storage ring) ~1/(Δl+Δn) proton neutron i13/2 i11/2 g9/2 g9/2 Z=82 N=126 s1/2 p1/2 d3/2 f5/2 L. Chen et al., PRL102 (2009) 122503.

  19. N. Al-Dahan et al. submitted to PRL

  20. An example of an N=125 nucleus: 204Au Beta decay: A.I. Morales, J. Benlliure et al., Acta Phys. Pol. B 40, 867 (2009) Isomer: S.J. Steer et al., Int. J. Mod. Phys. E18, 1002 (2009) Shell model: M. Gorska T1/2=10(2) s 1-: 186, 336, 437, 686 keV

  21. Seniority isomers in n-rich Pb isotopes S350 experiment – 2.5g/cm2 Be target, 2g/cm2 S1 degrader, 0.7g/cm2 S2 degrader - Setting on 215Pb Pb isotopes

  22. 214,216Pb isotopes: neutron g29/2 8+ isomers J-J. Valiente-Dobon, G. Benzoni, Sept. 2009 Preliminary Partial statistics

  23. Population of isomers by two-proton knockout reaction in 206Hg Isomeric ratios fig. Exp. Theory 3.1 4.7 -> 4.3 22 19 -> 18 Total 10+ 5- (with feeding) E.Simpson, J.A. Tostevien et al.

  24. Summary: • Info through isomeric decays in: • - N=126: 205Au, 204Pt, 203Ir • - N=128: 208Hg, 209Tl • Comparison with shell-model • New measurements 214,216Pb • -future: higher beam intensity • AIDA • DESPEC

  25. The RISING Collaboration

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