Production and Decay of Sub-U Isotopes by the Projectile Fragmentation of 1 A·GeV 238 U Experiment March, 2003 Zhong Liu University of Edinburgh

Collaboration University of Edinburgh Z. Liu, P.J. Woods, T. Davinson, A. Robinson, K. Schmidt University of Warsaw, Poland Z. Janas, M. Karny, A. Korgul, J. Kurcewicz, M. Pfützner GSI, Germany F. Attallah, J. Doring, H. Geissel, M. Gorska, M. Hellstrom, C. Mazzocchi, I. Mukha, C. Plettner, E. Roeckl, K. Summerer, E. Badura, K.H. Behr, A. Brühnle, K. Burkhard, W.Hüller, M. Winkler, H. Weick Argonne National Laboratory, USA C. Davids, D. Seweryniak Oak Ridge National Laboratory, USA R. Grzywacz, K. Rykaczewki

Study of p-rich Trans-lead Nuclei Fusion-evaporation Yu.Novikov etal., Nucl. Phys.A 697(2002) Bi: C.N.Davids et al., Phys. Rev. Lett. 76(1996)592

Projectile fragmentation of 238 U Advantages of PF (1) thick target (2) PID on event-by-event basis Drawbacks with 238 U beam (1) lower  due to the strong influence of fission compared to Pb beam H.G Clerc et Al., NPA 590 (1995) 785 (2) charge state distribution C. Scheidenberger et al., NIM B 142(1998) 441 (3) huge energy deposition ratio between implant and decay: ~ 20 GeV / MeV Feasibility ?

FRS Setup

Implant and Decay Setup

Particle Identification (A, Q, Z) A/Q (s2-s4) ( for Q 1 = Q 2 ) Q(Z): difficult Q fluctuates in materials at S0, S2, S4 2 MUSICs used with Nb foil in between: optimised energy loss the Q fluctuation:  B  (  E in S2 degrader)  E in MUSICs and S2 degrader combined to resolve Q(Z)

(1) Select fully stripped ions in both stages Q1=Q2-1 Q1-1=Q2 Z=89 Z=90 Z=91 Z=92

(2) Purification according to position at s4 Ac(Z=89)

(3) Identification of individual isotopes

Production yields for Pa, Th, and Ac (preliminary) Z=91 Z=90Z=89

Some Perspectives Near future: 238 U beam intensity of 10 9 pps new Ac (Z=89) isotopes  emitters: 205, 204 Ac 100 – 1000 ions /shift proton emitters 203 Ac ~50 ions /shift 201 Ac ~5 ions /shift Farther future DSSD equipped with fast-reset PA

Summary PF of 238 U: more favorable for low Z sub-U isotopes PID: production yield PF of 238 U has reached as far as the fusion evaporation reactions for Ac Implant-decay correlations: an existing detection system works HI rate in Si-stack 10 2 – 10 3 pps Imp. Rate 1 – 10 2 pps decay rate 1-10 pps t 1/2 range: 10  1 – 10 2 ms bad energy resolution (FWHM~100 keV) high radioactivity background Perspectives with higher beam intensity and DSSD PF of 238 U will provide new opportunity for study of sub-U isotopes beyond the p-dripline