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

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Presentation on theme: "Single-neutron structure of neutron-rich nuclei near 132 Sn Jolie A. Cizewski Department of Physics & Astronomy Rutgers University."— Presentation transcript:

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

2 INPC Jun 2007 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.

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

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

5 Transfer measurements around 132 Sn 124 Sn In Sb Te 130 Te 131 Sn 133 Sn Sn Z = 50 N = 82 135 Te StableDoubly magic 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

6 INPC Jun 2007 132 Sn(d,p) kinematics @ 4.7 A-MeV Forward  c-o-m ↔ backward  lab At backward  lab cross section very small and E proton very small. At forward  lab E proton rises quickly with angle (dE/d  is large). Want to measure around 90 o. 5 10 15 20 30 60 90 120 150 d  d  (mb/sr)  lab (deg) 0 Energy (MeV) Angle (deg)

7 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  m, 500  m and 65  m) ORRUBA gives ~80%  coverage over the range 47° →132° 288 electronics channels (conventionally instrumented)

8 INPC Jun 2007 132 Sn(d,p) detectors Plan ViewBeam View ORRUBA 1000μm ORRUBA telescopes Beam SIDAR ORRUBA telescopes 5x5cm 2 telescopes ORRUBA telescopes ORRUBA 1000μm 6 x ORRUBA 1000μm 5x5cm 2 telescope

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

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

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

12 INPC Jun 2007  p (deg) E p (MeV) 14 12 10 8 6 4 2 60 70 80 90 100 110 120 130 140 0 (d,p) to ground state (7/2-) (3/2-) (9/2-) (5/2-) (11/2-) (1/2-) 3700 2004.6 1560.9 853.7 0.0 1.45s 1655.7 (d,p) to 1st ex state (d,p) to 5/2- state (d,p) to 1/2- state ? 132 Sn(d,p): “all” ORRUBA detectors

13 INPC Jun 2007 133 Sn Excitation Energy Ex (channels) g.s ORRUBA detectors Counts Preliminary Fit known levels: g.s., 853.7-keV and 2004.6 keV (p 1/2 ) candidate: E x = 1390 (40) keV 90 80 70 60 50 40 30 20 10 0 0 20 40 60 80 100 120 140 160 180

14 INPC Jun 2007 134 Te(d,p): Q-value spectrum ≈0.66 MeV (p 3/2 ) g.s. (f 7/2 ) ≈1 MeV (p 1/2 ) ≈1.8 MeV (f 5/2 ?) -3-210 Q value (MeV) 5 10 15 20 25 30 35 -4 Counts PRELIMINARY: single strip CoM resolution ≈250 keV (FWHM)

15 INPC Jun 2007 N=83 Single Particle Energies Previously two (unhappy) alternatives: SPEs straight from experiment i.e. including the p 1/2 at 1656 keV. OR Extract from states in other nuclei e.g. Z=54, 56 isotones Sakar and Sakar Phys. Rev. C64 014312 (2001). NOW correct SPE’s Calculations of masses, other nuclear properties Nuclear astrophysics

16 INPC Jun 2007 130 Sn(d,p) 131 Sn N=81 Fwd ORRUBA #1, MCP coinc., narrow TAC window 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* (keV) Energies from 4-6 detectors Calibrations: 132 Sn(d,p) 133 Sn 130 Te(d,p) 131 Te Systematic error:  30 keV Counts Q (keV) (g.s.) 2 H( 132 Sn,p) 133 Sn PRELIMINARY

17 INPC Jun 2007 Summary: 132 Sn(d,p): Confirm 3 previously measured states Populate (p 1/2 ) state (for first time) at E x =1390(40) keV Better agreement with systematics and theory 134 Te(d,p): Candidate for f 5/2 at ≈1.8 MeV 130 Sn(d,p): States above N=82 gap: “Same” spectrum E x >2.6 MeV as 133 Sn Work in progress: Analysis of all detectors, all experiments Angular distributions To support p 1/2 assignment of 1390-keV state in 133 Sn For all states populated in 133 Sn, 135 Te, 131 Sn Spectroscopic factors Elastic scattering in forward angle detectors

18 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


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