2. Angular momentum population in fragmentation reactions Zsolt Podolyák University of Surrey

3. Which states are populated (spin-parity, energy)? With what cross sections?

4. Fragment Separator (GSI) Relativistic energy fragmentation: primary beam: 208 Pb (1 GeV/u) - ion-by-ion identification - decay out from the isomer is correlated with the fragment - γs measured in the 0-80 μs range (flight-time: ~300 ns)

5. 2 ~15(+3) >20(+7) 5(+5) 7 Isomers observed following fragmentation of 208 Pb and 238 U (Z>60) No. of isomers known(+new) New isomers => nuclear-structure Known isomers => reaction mechanism (angular momentum population What is the production cross section for individual states?

6. I=43/2 Low spin PROTON RICH ~1 ms “Power” of fragmentation

7. Isomeric ratios

8. ● M. Pfützner et al., Phys. Lett. B444 (1998) 32. ■ M. Pfützner et al., Phys. Rev. C65 (2002) 064604. ▲ K. Gladnishki et al., Phys. Rev. C69 (2004) 024617. isomeric ratio:

9. Fragmentation at relativistic energies abrasion ablation

10. Abrasion-ablation model (1-2  /3) k = 2  A>10 “sharp cut-off” approximation: De Jong, Ignatyuk, Schmidt, NP A613 (1997) 435.

11. M. Pfützner et al., Acta Phys. Pol. 32 (2001) 2507.

12. M. Pfützner et al., Phys. Rev. C 65 (2002) 054604. ABRABLA Analytical formulae

13. ρ th -all states with spin higher than the isomer decay into the isomer

15. M. Pfützner et al., Phys. Rev. C 65 (2002) 054604. R exp / ρ the open symbol: known higher-lying isomer (not observed)

16. Nuclear structure has to be considered φ = I isomer /(I parallel +I isomer ) = I isomer / I total ρ exp =R exp /φ ρ exp - the probability of populating states with higher spin than the isomer – can be compared with theory! 196 Pb: A.K.Singh et al., Nucl. Phys. A707 (2002) 3 186 W( 16 O,6n) at 110 MeV; 170 Er( 30 Si,4n) at 144 MeV fusion-evaporation reaction! 196 Pb 270 ns 2.7 MeV 12+

17. 179 W populated in: fragmentation of 208 Pb at 1 GeV/u fusion evaporation: 170 Er( 13 C,4n) at 67 MeV

18. preliminary

24. The highlighted points: Higher lying isomers decay into our isomer preliminary

25. 175Hf 176Ta 179Ta 177Ta The highlighted points: Higher lying isomers decay into our isomer

26.  Hg  Pb  Po 12 + isomers

27.  Hg  Pb  Po 12 + isomers

28. 179 W populated in: fragmentation of 208 Pb at 1 GeV/u fusion evaporation: 170 Er( 13 C,4n) at 67 MeV

29. Conclusions on the reaction mechanism Good agreement between experiment and theory (within a factor of 2-3) predictions for radioactive beams seems to be possible There are new data on: 212 Fr 15 – 213 Fr 29/2 + 212 Ra 8 + 214 Ra 17 – 215 Ra 43/2 – <= HIGHEST SPIN from fragmentation 215 Ac 29/2+ 217 Ac 29/2 + Future:

30. New data on: 212 Fr 15 – 213 Fr 29/2 + 212 Ra 8 + 214 Ra 17 – 215 Ra 43/2 – 215 Ac 29/2+ 217 Ac 29/2 +

31. To be simulated by P. Detistov Surrey/Sofia