3/1/13 WR, DGS111 Inverse-kinematic studies with Gretina and Phoswich Wall Walter Reviol and Demetrios Sarantites (Washington University) Gretina Workshop, ANL, March 2013 Plastic-CsI(Tl) phoswich Angle range: 8º ≤ θ ≤ 74º 4 PMT’s, 64 pixels each Pixel size: 6 x 6 mm Sub-pixel positioning resolution

3/1/13 WR, DGS222 Some one-neutron transfer studies near 132 Sn 134 Te + 13 C, E lab = 565 MeV, I= 3·10 5 s -1 (Holifield) Channel of interest: 135 Te 83 CLARION + Hyball detector combination γ PLF − particle TLF coincidences 136 Xe + 13 C, E lab = 560 MeV (ATLAS) Channel of interest: 137 Xe 83 Gammasphere + Microball Allmond et al., PRC 86 (2012); Radford et al., EPJA 15 (2002) [principle of experiment] gate 929 gate 1180 gate 533 (narrow) gate 1220

3/1/13 WR, DGS33 3 Next: 139 Xe 85 − level confirmation and spectroscopic factor No theory yet, but this argument can be made: The N = 83, 85 nuclei are cases for the emergence of collectivity just above 132 Sn. A phenomenological model (coupling i 13/2 states to quadrupole and octupole vibrations) was used. The lowest 13/2 + states ought to be rather pure (little admixture of 3 −,f 7/2 ). Hence S-factor data help to improve shell model calculations for 132 Sn and neighboring nuclei. Heyde et al., PLB 57, 429 (1975) Data for Xe are, in general, sparse compared to heavier isotones. ?

3/1/13 WR, DGS444 Re-accelerated CARIBU beams, some nuclei of interest, and related parameters: single-particle transfer and both safe and unsafe Coulex 1)Beam intensity in 10 5 s -1 (Cf252-upgrade-proposal-final-Rev4.pdf) 2)Q values and energies in MeV BeamIntens. 1) TargetPLFQ gg 2) E Coul,lab 2) E beam 2) θ graz,lab TLF 138 Xe C 139 Xe º 138 Xe7.2 9 Be 139 Xe º 138 Xe7.2 9 Be 139 Xe Xe C 141 Xe º 140 Xe B 141 Cs º Large TLF angles = safe, small TLF angles = unsafe Coulex Red: for 13/2 + in 139 Xe,  = 17 mb (Ptolemy DWBA code)

3/1/13 WR, DGS55 Symbols Open: Raman et al., ADNDT 78 (2001) Full: recent RIB Coulex experiments Sn and Te: Radford et al. (Holifield) Xe: Kröll et al. (REX-ISOLDE) AIP Conf. Proc. 1012, 84 (2008) “N > 82 Anomaly” (Radford et al.) Large error for 138 Xe suggests new measurement. “Standard” SM calculations aren’t able to reproduce small 136 Te B(E2). B(E2;0 + →2 1 + ) values in Sn region around N = 82

3/1/13 WR, DGS66666 Acknowledgement Very valuable discussions with J.M. Allmond and D.C. Radford are gratefully acknowledged. Thanks for your attention!

3/1/13 WR, DGS77777 Summary  The Phoswich Wall is, in a sense, the successor for Microball/Hyball. The experiments discussed are logic continuations of the inverse- kinematic radioactive-beam experiments pioneered by the group at ORNL-HRIBF.  The starter experiment would be neutron-transfer (and simultaneous Coulex) studies using a 138 Xe beam from CARIBU and a 13 C target. As for the transfer, the focus is on i 13/2 physics.  For the very asymmetric “inverse” reactions the coverage, 8º ≤ θ ≤ 74º, of the Phoswich Wall can probably not be met by any other detector.  The Phoswich Wall will be keeping up with future high-intensity radioactive-beam experiments (and stable-beam experiments).

3/1/13 WR, DGS8 Backup Slides

3/1/13 WR, DGS99 1p 1/2 1p 3/2 1s 1/ C 9 Be (cross sections to j > states are higher) (cross sections to j < states are higher) Franley et al., NPA 324, 193 (1979)

3/1/13 WR, DGS10 Observations Assignment for 13/2 + ( keV) uses in part systematics. Distinction between 13/2 + and 13/2 - ( keV) is not firm. Issues Populate preferably 13/2 +. Spin assignment by γ−particle angular correlations. Fragmentation of i 13/2 strength. 248 Cm source experiment

3/1/13 WR, DGS11 Faller et al., PRC 38, 905 (1988) 11 B( 140 Xe, 141 Cs) 10 Be or 14 N( 140 Xe, 141 Cs) 13 C, one-proton transfer πh 11/2 Negative-parity states in the isotopic chain on both sides of the N = 82 “mark” Additional thoughts: 10 Be - 9 Be distinction: by ΔE (except at large θ), γ rays.

3/1/13 WR, DGS12 Comment on Coulomb excitation 134,136 Te + nat C, E lab = 396 MeV, I= 10 5 s -1 (A=136) 12 C-γ coincidences with CLARION + Hyball (Hyball rings 1 – 3; 4° ≤ θ C ≤ 44°)

3/1/13 WR, DGS13 Some one-neutron transfer studies near 132 Sn - continued 134 Te + 13 C, CLARION + Hyball Use Hyball rings 3, 4: 28° ≤ θ C ≤ 60° 12 detectors/ring, same set of angles ɸ C For each event: reaction plane w/ angle ɸ C Use the CLARION ring with θ γ = 90° 5 detectors with different angles ɸ γ Construct angular correlations: Δ ɸ = ɸ γ − ɸ C, 5 · 12 = 60 data points TLF-γ angular correlations Allmond et al., PRC 86 (2012)

3/1/13 WR, DGS14 High-l states are strongly populated in inverse-kinematics reactions w/ C or Be targets. Let’s focus on the i 13/2 and f 7/2 orbitals A = 137 (N = 83): Isospin dependent modification of residual interaction A ≥ 139 (N ≥ 83): Shape evolution with N A focus in studies of A ≥ 139 Xe’s is the angular distribution of candidate 13/2 →11/2 transitions and, perhaps, their linear polarization 13/2 + : only one state not seen in SF. But the decay intensity is very different (compared to SF). 143 Xe: levels seen in SF experiment. But no assignments made. Onset of collectivity.

3/1/13 WR, DGS15 What can be determined and how? For every excited state of the PLF, the Q value is obtained from the level energy and the calculated Q gg value (Q = Q gg – E lev ). From θ TLF,Lab, we then calculate θ PLF,CoM (since we are dealing with a binary reaction). If only PLF is excited, θ PLF,CoM (θ TLF,Lab ) and E TLF,Lab (θ TLF,Lab ) are single curves (if TLF is excited too, two curves are obtained, and the one corresponding to the lower E PLF,CoM is picked). What angle ranges can be covered?

3/1/13 WR, DGS16 Ordinate: Degree or MeV ε ≈ π

3/1/13 WR, DGS17 Design requirements for the Phoswich Wall The main application is in reverse-kinematics binary reactions. An example: 13 C( 140 Xe, 141 Xe) 12 C (CARIBU). Details: The observables are TLF particles and coincident PLF γ rays ( 12 C − 141 Xe γγ). The important derived quantity is dσ/dΩ PLF,CoM (θ) → spectroscopic factors/ANC’s. Δθ ~ 1º and Δφ(θ) = 4º to 1º. Microball/Hyball segmentation (Δθ = 18º on average) is inadequate. High rate capability due to high “pixilation”. Z-identification of TLF’s, hence use phoswich detectors. No 4π coverage (e.g. 12 C θ graz,lab = 40.3° for 465 MeV 140 Xe + 13 C). Optimal Doppler correction of PLF γ rays comes for free.