5/15/14 WR The Phoswich Wall – features, applications, performance Walter Reviol and Demetrios Sarantites (Washington University) ATLAS User Workshop, ANL, May 2014 Plastic – CsI(Tl) phoswich Angle range: 9º ≤ θ ≤ 72º 4 PMT’s, 64 pixels each Sub-pixel positioning resolution: Δx ≈ 1 mm Tailored to run with a 4π γ-ray array Coincidence measurement: particle TLF – γ PLF

5/15/14 WR 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 Hyball + CLARION detector combination particle TLF − γ PLF coincidences 136 Xe + 13 C, E lab = 560 MeV (ATLAS) Channel of interest: 137 Xe 83 Microball + Gammasphere Allmond et al., PRC 86 (2012); Radford et al., EPJA 15 (2002) [principle of experiment] gate 929 gate 1180 gate 533 (narrow) gate 1220

5/15/14 WR3 333 Transfer reaction vs. spontaneous fission Selectivity (can dial state of interest) Vast amount of information 248 Cm SF Daly et al. PRC 59, 3066 (1999) 136 Xe + 13 C  137 Xe + 12 C Allmond et al., PRC 86, (R) (2012) 137 Xe

5/15/14 WR Lessons learned so far Using comparatively heavy targets ( 13 C, 9 Be) is a good way of studying high-j, high-ℓ states; complementary to (d,p), (α, 3 He) Combining HPGe array and Phoswich Wall (Microball) is beneficial for studying heavy nuclei; here the density of states is high Using the selectivity of transfer reactions allows to improve level schemes previously studied via SF, fusion-evaporation, or deep-inelastic collisions; for example, the transition intensity helps to determine the state’s parity New tasks Extract nucleon-transfer spectroscopic factors from dσ/dΩ CoM,PLF ; based on TLF angular-distribution data Explore the potential of cluster transfer, e.g., 142 Ce( 7 Li,α) 145 Pr; suppress incomplete-fusion channels, get a handle on 3 H spectroscopic factors

5/15/14 WR 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 Lab,TLF, we then calculate Θ CoM,PLF (since we are dealing with a binary reaction). If only PLF is excited, Θ CoM,PLF (θ TLF ) and E Lab,TLF (θ Lab,TLF ) are single curves. (If TLF is excited too, two curves are obtained, and the one corresponding to the higher E Lab,TLF is picked.) The derived quantity is dσ/dΩ CoM,PLF (θ Lab,TLF ). (What angle ranges can be covered?)

5/15/14 WR Example: study of one-proton transfer in heavy rare-earth nuclei 1)Ground-state to ground-state Q value in MeV 2)Nitride target 3)CARIBU beam BeamTargetPLF + TLFQ gg 1) BeamTarg.PLF + TLFQ gg 142 Ce 14 N 2)143 Pr + 13 C Ce 3)14 N 149 Pr + 13 C Ce 14 N 141 La + 15 O Ce 14 N 147 La + 15 O Ce 14 N 143 Ce + 13 N Ce 14 N 149 Ce + 13 N Ce 14 N 141 Ce + 15 N Ce 14 N 147 Ce + 15 N4.378 Red Case of interest: location of πh 11/2, occupancy of πg 7/2 vs. N Experimental issue: separate C from N and O (20 MeV < E Lab,TLF < 150 MeV) ~~

5/15/14 WR Phoswich Wall in-beam performance (Notre Dame FN Tandem) Scattering experiments: α’s, heavy ions off 197 Au (5 – 6 energies) 197 Au(α,p) 202 Hg (27 MeV) consider energy deposited in CsI(Tl) gating Findings: Ions are well separated down to low energies ( 14 N: E dep = 8.46 MeV) Some may be mass-identifiable at higher energies ( 7 Li vs. 6 Li) A: Fast, B: Early, C: Late

5/15/14 WR8 888 Used square masks of different sizes The algorithm is pulse-height independent Applying the algorithm gives uniform distributions 4.8 x 4.8 mm 2 mask Phoswich Wall 252 Cf tests: the position algorithm

5/15/14 WR Summary and Outlook  The Phoswich Wall was designed for strongly inverse kinematics binary reactions near the Coulomb barrier. It is not a “stand-alone” device. The new device is, in a sense, the successor for Microball/Hyball.  Starter experiments are: 7 Li breakup/transfer and single-nucleon transfer studies, the latter with comparatively heavy targets. Projectile Coulomb excitation will be performed simultaneously, large angles θ Lab,TLF favor safe Coulex (not discussed).  The PID among the particles of interest is as good as expected. The fast- plastic and CsI(Tl) components are calibrated. The device is ready for production runs. The readout is VME based and can be easily coupled to the Myriad system of DGS and to Gretina (not discussed).  High-quality stable and CARIBU reaccelerated beams from ATLAS are crucial (timing, beam spot).

5/15/14 WR10 Acknowledgement Very valuable discussions with J.M. Allmond and D.C. Radford are gratefully acknowledged. Thanks for your attention!

5/15/14 WR11 Backup Slides

5/15/14 WR125/15/14 WR12 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 on studying odd-Z nuclei: 10 Be - 9 Be distinction: by ΔE (except at large θ), γ rays.

5/15/14 WR135/15/14 WR13 1p 1/2 1p 3/2 1s 1/ N 11 B cross sections to j > states are higher (like 16 O) cross sections to j < states are higher (like 12 C) Franley & Phillips, NPA 324, 193 (1979) 1, 2: initial, final bound state no extra angular momentum (that would influence the phase of the distorted wave)

5/15/14 WR145/15/14 WR14 Q-value considerations for studying odd-Z nuclei in the rare-earth region 1)Q value in MeV 2)Also considered as incomplete-fusion channel 3)Odd-N nucleus, for comparsion only BeamTargetPLF + TLFQ gg 1) BeamTargetPLF + TLFQ gg 142 Ce 7 Li 145 Pr + α Ce 7 Li 151 Pr + α Ce 7 Li 144 Pr + αn 2) Ce 7 Li 150 Pr + αn Ce 7 Li 143 Pr + α2n 2) Ce 7 Li 149 Pr + α2n Ce 7 Li 143 Ce + 6 Li 3) Ce 7 Li 149 Ce + 6 Li Ce 7 Li 141 La + 8 Be Ce 7 Li 147 La Ce 11 B 143 Pr + 10 Be Ce 11 B 149 Pr Ce 14 N 143 Pr + 13 C Ce 14 N 149 Pr Ce 3 He 143 Pr + d Red: suggested cases for a simultaneous study

5/15/14 WR15 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°)

5/15/14 WR165/15/14 WR165/15/14 WR165/15/14 WR165/15/14 WR16 Phoswich Wall Tilted “Gobbi” geometry Average target­­­-detector distance: 55 mm Angle range: 9º ≤ θ ≤ 72º Multi-anode PMT (H8500): # pixels: 64 active fraction of surface: 0.89 pixel size: 6.02 × 6.02 mm 2 Phoswich: 12 μm fast plastic, 2.2 mm CsI(Tl) Optical cross talk: sub-pixel positioning Expect: Δθ ≈ 1°, Δφ(θ) ≈ 4°­ - 1° Microball: Δθ ≈ 18°

5/15/14 WR175/15/14 WR17 Phoswich Wall 252 Cf tests: particle identification (PID) gating Gates: Fast (A), Early (B), Late (C) Pixel neighbor pulse heights are added in ASIC chip readout (so-called PSD chip) Early (B) (A) Late (C) Early (B)

5/15/14 WR185/15/14 WR Ce + 14 N → 137 Xe + 13 C, E lab = 560 MeV ΔE* = MeV ( 13 C: 1/2 + ) ΔE Lab,TLF ≈ 5.5 MeV Good separation at the smaller angles ε ≈ π

5/15/14 WR195/15/14 WR195/15/14 WR19 Δθ Lab ≈ 1° ↔ Δθ CoM ≈ 2° 142 Ce + 14 N → 137 Xe + 13 C, E lab = 560 MeV