Singleneutron structure of neutronrich nuclei near 132 Sn

Single-neutron structure of neutron-rich nuclei near 132 Sn Jolie A. Cizewski Department of Physics & Astronomy Rutgers University

Collaboration RIBENS/Center of Excellence Rutgers University J. A. C. , R. Hatarik, P. O’Malley, Steve Pain, T. Swan ORNL D. W. Bardayan, J. C. Blackmon, F. Liang, C. D. Nesaraja, D. Shapira, M. S. Smith Univ. Tennessee K. Y. Chae, Kate L. Jones, Z. Ma, B. H. Moazen Tennessee Tech Ray Kozub, J. Shriner, D. Sissom ORAU C. Matei University of Surrey J. S. Thomas Colorado School of Mines K. Chipps, L. Erikson, R. J. Livesay Ohio University A. Adekola Warsaw W. Krolas Funded in part by the U. S. DOE Office of Science & NNSA/SSAA and the National Science Foundation. INPC Jun 2007

Fundamental Questions in Nuclear & Astro Physics • Origin of elements • Limits of nuclear existence • Evolution of shell structure INPC Jun 2007

Measuring (d, p) on Rare Isotopes near Shell Closures HRIBF yields N=82 Neutron magic-number nuclei at waiting points Measure (d, p) reactions with unstable beams n n INPC Jun 2007 Measure single-neutron energies + spectroscopic strengths Provide data to understand r process nucleosynthesis

Transfer measurements around 132 Sn Double shell closure Z=50, N=82 132 Sn(d, p)133 Sn, 130 Sn(d, p)131 Sn and 134 Te(d, p)135 Te measurements completed 124 Sn 130 Te 131 Sn 135 Te 133 Sn Te Sb Z = 50 Sn In Stable Doubly magic N = 82

132 Sn(d, p) kinematics @ 4. 7 A-Me. V Forward qc-o-m ↔ backward qlab Energy (Me. V) At backward qlab cross section very small and Eproton very small. At forward qlab Eproton rises quickly with angle (d. E/dq is large). 20 15 Want to measure around 90 o. ds/d. W (mb/sr) Angle (deg) 10 5 0 INPC Jun 2007 30 60 90 qlab (deg) 120 150

ORRUBA: Oak Ridge Rutgers University Barrel Array • Flexible design for measuring ejectiles from transfer reactions in inverse kinematics • Resistive and non-resistive Si detectors (1000 mm, 500 mm and 65 mm) • ORRUBA gives ~80% f coverage over the range 47° → 132° • 288 electronics channels (conventionally instrumented)

132 Sn(d, p) detectors Plan View Beam View ORRUBA telescopes ORRUBA 1000μm �� 6 x ORRUBA 1000μm � 5 x 5 cm 2 telescopes ORRUBA telescopes Beam � Beam SIDAR �� ORRUBA 1000μm ORRUBA telescopes INPC Jun 2007

132 Sn(d, p) ORRUBA detectors (back angles) SIDAR detectors (back angles) INPC Jun 2007 photo

What should one expect to see? 1 i 13/2 Should be strongest in N=82 (d, p) (�=1 and �=3) 3 p 1/2 3 p 3/2 2 f 5/2 2 f 7/2 1 h 9/2 82 1 h 11/2 2 d 3/2 3 s 1/2 2 d 5/2 1 g 7/2 INPC Jun 2007 Two neutron holes in 130 Sn (g. s. ) 80

N=83 Systematics Only weak evidence for p 1/2 state Tentatively assigned f 5/2; other candidates at higher energies INPC Jun 2007

132 Sn(d, p): “all” ORRUBA detectors (11/2 -) 14 3700 12 Ep(Me. V) (d, p) to ground state 10 (5/2 -) (1/2 -) (9/2 -) 2004. 6 1655. 7 1560. 9 8 (3/2 -) 853. 7 6 (7/2 -) 0. 0 1. 45 s (d, p) to 1 st ex state 4 2 (d, p) to 5/2 - state (d, p) to 1/2 - state ? 0 60 INPC Jun 2007 70 80 90 100 110 p (deg) 120 130 140

133 Sn 90 Excitation Energy ORRUBA detectors 80 Preliminary Fit known levels: g. s. , 853. 7 -ke. V and 2004. 6 ke. V 70 Counts 60 g. s 50 (p 1/2) candidate: Ex= 1390 (40) ke. V 40 30 20 10 0 0 20 40 60 80 100 120 140 160 180 Ex (channels) INPC Jun 2007

134 Te(d, p): Q-value spectrum ≈1. 8 Me. V (f 5/2 ? ) ≈1 Me. V ≈0. 66 Me. V (p 1/2) (p 3/2) PRELIMINARY: 35 single strip 30 Counts 25 20 Co. M resolution ≈250 ke. V (FWHM) 15 10 5 INPC Jun 2007 -4 -3 -2 -1 Q value (Me. V) 0 1 g. s. (f 7/2)

N=83 Single Particle Energies Previously two (unhappy) alternatives: • • SPEs straight from experiment i. e. including the p 1/2 at 1656 ke. V. OR Extract from states in other nuclei e. g. Z=54, 56 isotones Sakar and Sakar Phys. Rev. C 64 014312 (2001). • • INPC Jun 2007 NOW correct SPE’s Calculations of masses, other nuclear properties Nuclear astrophysics

RY A IN M LI E R P 130 Sn(d, p)131 Sn N=81 Fwd ORRUBA #1, MCP coinc. , narrow TAC window 4679(41) 4018(28) 3417(23) 2680(23) 131 Sn* (ke. V) Energies from 4 -6 detectors Calibrations: 132 Sn(d, p)133 Sn 130 Te(d, p)131 Te Counts 2 H(132 Sn, p)133 Sn Systematic error: 30 ke. V (g. s. ) Q (ke. V) INPC Jun 2007

Summary: n 132 n n 134 n n 130 n n Sn(d, p): Confirm 3 previously measured states Populate (p 1/2) state (for first time) at Ex=1390(40) ke. V Better agreement with systematics and theory Te(d, p): Candidate for f 5/2 at ≈1. 8 Me. V Sn(d, p): States above N=82 gap: “Same” spectrum Ex>2. 6 Me. V as 133 Sn Work in progress: Analysis of all detectors, all experiments n. Angular distributions n n n To support p 1/2 assignment of 1390 -ke. V state in 133 Sn For all states populated in 133 Sn, 135 Te, 131 Sn Spectroscopic factors n. Elastic scattering in forward angle detectors n INPC Jun 2007

Thank you Single-neutron structure of neutron-rich nuclei near 132 Sn Work supported in part by the U. S. Department of Energy and National Science Foundation INPC Jun 2007