Detection of X rays in the Neutron-Deficient Polonium Coulomb Excitation Experiments

1. Detection of X rays in the Neutron-Deficient Polonium Coulomb ExcitationExperiments Nele Kesteloot IKS KU Leuven SCK• CEN

2. Outline • The polonium isotopes • Experimentalcampaign • X rays • Overview • Origin • K-vacancycreation in collision • Corrections • Normalization • 206Po • 188Hg • E0 transitions • Otherpitfalls • Outlook Miniball Workshop 2013 - CERN

3. The polonium isotopes Experimental campaign X rays Other pitfalls Outlook 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 Miniball Workshop 2013 - CERN

4. The polonium isotopes Experimental campaign X rays Other pitfalls Outlook Experimental campaign Miniball Workshop 2013 - CERN

5. The polonium isotopes Experimental campaign X rays Other pitfalls Outlook X rays – Overview 196Po on 104Pd 198Po on 94Mo 200Po on 104Pd 202Po on 104Pd 202Po on 94Mo 206Po on 104Pd Miniball Workshop 2013 - CERN

6. The polonium isotopes Experimental campaign X rays Other pitfalls Outlook X rays – Origin 1137 0+ Conversion of observed200Po gamma rays X rays 2+ 666 0 0+ 200Po Atomic production of K vacancy in ion-atom collision E0 transition 0+2 0+1 Miniball Workshop 2013 - CERN

7. The polonium isotopes Experimental campaign X rays Other pitfalls Outlook X rays – K-vacancy creation in collision • Ion-atom collision gives rise to production of K vacancy • Theoretical formula • Scale proton-induced cross section to heavy projectile • Change reference frame • K-vacancy in projectile • Energy per nucleon remains unaltered • Very sensitive to beam energy • Take energy loss in target into account J.D. Garcia et al, RMP 45 No 2 (1973) 111 Miniball Workshop 2013 - CERN

8. The polonium isotopes Experimental campaign X rays Other pitfalls Outlook X rays – Corrections H.-H. Behncke et al., Z. Phys. A 289 (1979) 333 • Empiricalcorrection 132Xe projectile on target with Z protons σexp/ σ th Sexp = 0.070(15) 2.4 MeV/u 3.6 MeV/u 4.7 MeV/u 5.9 MeV/u Z 208Pb projectile on target with Z protons σexp/ σ th Z Miniball Workshop 2013 - CERN

9. The polonium isotopes Experimental campaign X rays Other pitfalls Outlook X rays – Corrections • Geometricalcorrection Detection range in center-of-mass frame Sdet = 0.1439(18) Miniball Workshop 2013 - CERN

10. The polonium isotopes Experimental campaign X rays Other pitfalls Outlook X rays – Normalization 1667.4 4+ 1434.4 4+ 202Po on 104Pd 206Po on 104Pd 1302.5 2+ 1248.6 2+ 1177.8 4+ 1162.2 2+ 1585.2 (3,4)+ 1546.3 4+ • No observed low-lying excited 0+ states • X rays • Conversion of observed gamma lines • K-vacancy creation in ion-atom collision 700.7 2+ 677.2 2+ 0 0+ 0 0+ 202Po 206Po Miniball Workshop 2013 - CERN

11. The polonium isotopes Experimental campaign X rays Other pitfalls Outlook X rays – Normalization • Compare to X rays in Hg coulex • Scale to 188Hg Weighted average: 2.82(49) Weighted average: 0.55(11) Miniball Workshop 2013 - CERN

12. The polonium isotopes Experimental campaign X rays Other pitfalls Outlook X rays – E0 transitions in Po Miniball Workshop 2013 - CERN

13. The polonium isotopes Experimental campaign X rays Other pitfalls Outlook X rays – E0 transitions in Hg Observed X rays / Expected X rays (%) 114Cd 107Ag 120Sn 114Cd 107Ag 120Sn 112Cd 107Ag 120Sn 112Cd 188Hg 186Hg 184Hg 182Hg Miniball Workshop 2013 - CERN

14. The polonium isotopes Experimental campaign X rays Other pitfalls Outlook Other pitfalls • Gamma raydetection efficiency • Rapidlyvarying at low energies • Needforgood efficiency calibration curve • 152Eu and 133Ba sources • Coincidencemethod • Random subtraction • Big amount of randoms at low energies • Number of X raysvery sensitive to p/r scaling factor! • Correct propagation of error bars is crucial • Fit of X-raypeaks Miniball Workshop 2013 - CERN

15. The polonium isotopes Experimental campaign X rays Other pitfalls Outlook Conclusion and Outlook • Multiple origins for X rays in coulex data • Conversion of gamma lines • E0 transition between two 0+ states • K-vacancy creation in ion-atom collision • Theory as qualitative basis • 206Po/188Hg as normalization • Correct assessment of X rays is crucial • Number of E0 transitions determines population of 0+2 state • Influence on extracted matrix elements • Normalization factors in other data sets • Pbcoulex • Rncoulex Miniball Workshop 2013 - CERN

16. Thank you! N. Bree H. De Witte J. Diriken L. Gaffney M. Huyse P. Van Duppen K. Wrzosek-Lipska B. Bastin E. Clement N. Lecesne V. Fedosseev B. Marsh E. Piselli E. Rapisarda M. Seliverstov T. Stora D. Voulot F. Wenander T. Kröll, Technische Universität Darmstadt P. Butler, University of Liverpool M. Scheck, University of West Scotland, Paisley M. Zielinska, CEASaclay T. Grahn J. Konki J. Pakarinen P. Reiter B. Siebeck N. Warr Miniball Workshop 2013 - CERN

17. γγ coincidences in 198Po 1158.4 4+ 1039.1 2+ 816 0+ 604.9 2+ 0 0+ 198Po Gateon 605 keV Number of counts / 2 keV Gamma energy (keV) Miniball Workshop 2013 - CERN

18. γγ coincidences in 196Po 891 4+ 859.1 2+ 558 0+ 463.1 2+ 0 0+ 196Po Gateon 463 keV Miniball Workshop 2013 - CERN