1. LLNL-PRES-654342 This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. Lawrence Livermore National Security, LLC ATLAS Users Meeting 2014 May 15, 2014

2. Lawrence Livermore National Laboratory LLNL-PRES-654342 2  Motivation and experimental approach  Initial focus  A case study in details  Summary

3. Lawrence Livermore National Laboratory LLNL-PRES-654342 3  Evolution of nuclear quadrupole collectivity Shape transition and shape coexistence in neutron-rich nuclei with A ~ 100 Nuclear structure sensitive to the occupancy level of the h 11/2 neutron and g 9/2 proton orbitals Manifestations are (1) the sudden onset of quadrupole deformation in Sr and Zr isotopes, (2) the emerging  degree of freedom in Mo – Ru region, and (3) the predicted triaxial shape transition from prolate to oblate in Ru – Pd region Ideal testing ground for various theoretical models, including the nuclear density functional theory Milestone NS9 for 2018 defined by NSAC Subcommittee on Performance Measures

4. Lawrence Livermore National Laboratory LLNL-PRES-654342 4  Probe the shape transition and shape coexistence in nuclei by measuring their electromagnetic properties using the sub-barrier Coulomb excitation method Extract the transition and static matrix elements for the  -ray transitions measured by (Digital) Gamasphere or GRETINA /CHICO2

5. Lawrence Livermore National Laboratory LLNL-PRES-654342 5  Shape transition and shape coexistence in 96,98 Y Both have long-lived isomers with the same decay mode and similar lifetime of those for the ground states but different spin and shape The ground states have spin 0 – and the characteristics of spherical shape 96m Y (T 1/2 = 9.6 s) has spin 8 + with E ex = 1130 keV and intrinsic Q 0 = – 1.40 b (Laser spectroscopy) 98m Y (T 1/2 = 2.0 s) has spin (4 or 5) with E ex = 410 keV and intrinsic Q 0 = 3.12 b (Laser spectroscopy)

6. Lawrence Livermore National Laboratory LLNL-PRES-654342 6  K  = 5 + for 98m Y (T 1/2 = 2.0 s) at E ex = 410 keV  Intrinsic Q 0 = 3.12 b  420 MeV 98m Y on 208 Pb of 1 mg/cm 2  7 days of beam-on-target with intensity ~ 2,000 pps  Integrate the scattered angle from 40 o to 70 o  10%  efficiency Transiti on Cross section (mb) Counts 6  5 144635 7  6 4.520 7  5 90397 8  7 14.966 8  6 25.2111 9  8 0.201 9  7 19.586 10  9 1.88 10  8 6.328

7. Lawrence Livermore National Laboratory LLNL-PRES-654342 7  Provide the precision measured electromagnetic properties for neutron-rich nuclei with A ~ 100 to test and improve the predictability of nuclear models such as nuclear density functional theory  An example is given to illustrate the study of the electromagnetic properties for the available isomeric beams at CARIBU Quadrupole collectivity can be studied for the excited states with spin up to 10 for the well-deformed 98m Y The transition and static matrix elements can be determined for transitions with the cross section as low as 10 mb within a reasonable time frame