1. Andrew Stuchbery Department of Nuclear Physics, The Australian National University Canberra, ACT 0200, Australia Excited-state g-factor measurements: Recoil in Vacuum with CARIBU beams

2.  Physics goal: nuclear structure between 100 Sn and 132 Sn 252 Cf + Gammasphere A.G. Smith et al. PLB 591, 55 (2004) Behavior of neutron-rich g factors An example: g factors of n-rich isotopes between Z=40 and Z=50. Why are some g(2 + ) smaller than in the stable isotopes? Use RIV on CARIBU beams to extend and improve precision of data. ** Simultaneous measurement of B(E2) and g factor **

3. RIV g-factor measurements : concept W(  ,  p   ) =  kq  (2k+1)  kq (  p ) G k F k Q k D k* (  p  ,  ,0) q0 132 Te beam scattered 132 Te 12 C recoil  p,  p )  ray emitted at angle (  ,   ) g factors from a B(E2) experiment Measure azimuthal angular correlations – Gammasphere+ Hercules (say) Attenuation coefficient due to RIV: contains information about the nuclear moment J electron spin randomly oriented I nuclear spin aligned by reaction F = I + J

4. RIV example with weak radioactive beams: 136 Te 1. Apparatus: Clarion+Hyball at HRIBF 3. Extracting g factors from G k values 2. Correlation data give G k values Technique applicable for lifetimes ~ 1 ps <  < ~ 100 ps

5. Lines are empirical fits to where An excellent model fit can also be obtained Proof of concept and field calibration: ~ 2 MeV/A Ru and Pd beams RIV in the A ~ 100 region @ ANU Heliotrope (poor man’s CD) Azimuthal angular correlations 96 Ru 104 Ru Extracted attenuation coefficients 4 Ge detectors

6. Summary Behavior of g factors in n-rich nuclei near A=100 contrasts with stable isotopes and is not well understood RIV experiments measure azimuthal angular correlations under conditions similar to a B(E2) measurement Our understanding of the RIV fields is sufficient to make g-factor measurements on cases accessible with CARIBU