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Recent Experimental Results from HELIOS

Recent Experimental Results from HELIOS. A new approach to reactions in inverse kinematics. A. H. Wuosmaa Western Michigan University. Why still study nucleon transfer?. Renewed emphasis on transfer reactions with RIBS :

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Recent Experimental Results from HELIOS

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  1. Recent Experimental Results from HELIOS A new approach to reactions in inverse kinematics A. H. Wuosmaa Western Michigan University

  2. Why still study nucleon transfer? • Renewed emphasis on transfer reactions with RIBS: • Properties of nuclei far from stability, esp. near “closed” shells (spins, parities, spectroscopic factors, s.p. energies, residual interactions) • Importance of the tensor interaction • Test/tune new shell-model interactions • Broader applications: • e.g. astrophysics, stewardship (“surrogates” for capture reactions) Life is muchmore difficult with inverse kinematics and radioactive beams

  3. Evolution of 1s1/2-0d5/2 splitting outside N=8 ?? (1,2,3,4)- 0d5/2 neutron has j(n)=j> 0.74 5/2+ 0.33 (0,1)- 0.00 1/2+ 0.87 1/2+ ?? (1,2)- 0.17 (2,3)- 0.00 5/2+ 14B(Sn=0.97) 17O(Sn=4.14) 16N(Sn=2.49) 15C(Sn=1.22) p(p1/2)2 p(p1/2) p(p3/2)4 p(p3/2)3 j(p)=j< attraction j(p)=j> repulsion j(p)=j> repulsion j(p)=j< attraction =( J(p),J(n) one j>otherj<:attraction J(p),J(n) both j>or j<:repulsion

  4. (d,p) reaction in different frames OUT IN 1H v0 qCM CM frame 2H vlab qLAB Laboratory frame- “normal” kinematics Laboratory frame- “Inverse” kinematics vlab qLAB

  5. The HELIOS approach to inverse kinematics Uniform magnetic field B Emitted here z Beam Axis Detected here Cyclotron orbit We measure: Elab, z, TOF We deduce: ECM ,qCM For a given state For two states at fixed z

  6. Advantages to the HELIOS approach for (d,p) “Conventional” – measure at fixed qLAB HELIOS – measure at fixed z dEP/dqLAB=175 keV/deg EP(MeV) EP(MeV) 5 MeV 1.4 MeV dEP/dz=17.5 keV/mm Cos(qCM) Cos(qCM) qLAB(deg) z (m)

  7. HELIcalOrbit Spectrometer -HELIOS BMAX=2.85 T 2.35 m 0.9 m Silicon Array Target Beam Laser rangefinder X-Y-q positioning stage J.P. Schiffer, RIA equipment workshop 1999, AHW et al, NIMPRA 580, 1290 (2007) J. C. Lighthall et al, NIMPRA 622, 97 (2010)

  8. Spectrometer completed in August 2008

  9. Excitation energy in 29Si 0.00 A/q=1, 1 turn protons from 28Si+12C 1.27 2.03 A/q=1, 2 turns (A/q=2, 1 turn) Residual a source background 3.62 3.07 4.94 T(ns) 6.38 6.19 6.71 7.79 28Si(d,p)29Sicommissioning-it works! J. C. Lighthall et al, NIMPRA 622, 97 (2010)

  10. 28Si(d,p)29Si Excitation-energy spectrum Typical resolution ~ 120 keV FWHM Best resolution ~ 80 keV FWHM J. C. Lighthall et al, NIMPRA 622, 97 (2010)

  11. Exotic behavior in 16C? Valence neutrons Core 16C No hindrance, and no exotic behavior. Study with 15C(d,p)16C

  12. 15C(d,p)16C with HELIOS 1.5-2M 15C/s @ 8.2 MeV/u Proton energy-position correlation (d,p) samples the n(1s1/2) content of the wave functions for positive-parity states 16C Excitation-energy spectrum PRL 105, 132501 (2010)

  13. L=0 L=2 L=0 L=2 15C(d,p)16C results Shell model – WBP interaction Experiment Shell model works well – no need for exotica! PRL 105, 132501 (2010)

  14. 19O(d,p)20O – further into the sd shell 200k-300k 19O/s @ 6.6 MeV/u Proton energy versus position 20O excitation energy ν(0d5/2)35/2ν(sd)→ν(sd)4 states in 20O C. R. Hoffman et al., PRC 85, 054318 (2012)

  15. What we can learn from 19O(d,p)20O L=2 L=0+2 Orbital vacancy G+ Cross section (mb/sr) Center-of-mass angle (deg) 19O excitation energy (MeV) Solid: L=0; hatched L=2 Angular distributions and neutron vacancies from 19O(d,p)20O C. R. Hoffman et al., PRC 85, 054318 (2012)

  16. Preliminaryexcitation-energy spectrum 13B(d,p)14B G<150 keV G~200 keV 20-40k 13B/s @15.7 MeV/u Sn=0.969 Broad l=0 and 2 states expected with Jπ=(0,1,2,3)- Red – 14B Blue – 13B EX (14B) (MeV)

  17. L=0 L=2 L=0+2 2- 0.0 13B(d,p)14B Preliminary L=0 L=2 Shell model with WBT interaction 1- 0.65 ds/dW (mb/sr) Experiment Sn 3- 1.38 (2-) G~1MeV Preliminary! Preliminary! 4- 2.08 OMPs fit 30 MeV d+12C, p+12,13C elastic scattering at 15 MeV/u qc.m. (deg)

  18. 136Xe(d,p)137Xe with HELIOS– approaching 132Sn Proton energy versus position 137Xe excitation energy B. P. Kay et al, PRC 84, 024325 (2011)

  19. What we can learn from 136Xe(d,p)137Xe 136Xe(d,p)137Xe angular distributions and orbital-energy trends near N=82 B. P. Kay et al, PRC 84, 024325 (2011)

  20. A variety of measurements • 28Si(d,p)29Si – Aug. 2008 (first commissioning)* • 12B(d,p)13B– March 2009 (RIB commissioning)* • 17O(d,p)18O – Aug. 2009 (unbound states in 18O) • 15C(d,p)16C – Sep. 2009 (exotic behavior in 16C)* • 130,136Xe(d,p)131,137Xe – Nov. 2009 (S.P. states near N=82)* • 86Kr(d,p)87Kr – Feb. 2010 (S.P. states near N=50) • 14C(6Li,d)18O – March 2010, (a-cluster states in 18O: d not p!) • 19O(d,p)20O – Sep. 2010 (structure of 20O)* • 28Si(d,3He)27Al, 28Si(d,t)27Si – May 2011 (commissioning of forward-hemisphere configuration) • 13B(d,p)14B– Nov. 2011 (structure of 14B) • 17N(d,p)18N– March 2012 (structure of 18N) *Published or In Press

  21. Summary • HELIOS provides a new approach to studying reactions in inverse kinematics • Alleviates problems with light particle identificationand gives improved excitation-energy resolution and straightforward determination of CM quantities • Can obtain data with quality approaching that of normal-kinematics measurements • The method can be applied to a variety of other inverse-kinematic reactions in addition to (d,p) • Other examples are being considered at HIE-ISOLDE, SPIRAL2, ReA3/FRIB

  22. Many thanks to: 2M. Alcorta, 2B. B. Back, 2S. I. Baker, 1S. Bedoor, 2P. F. Bertone, 3B. A. Brown, 2J. A. Clark, 2,4C. M. Deibel, 5P. Fallon, 6S. J. Freeman, 2C. R. Hoffman, 2B. P. Kay, 2,7H. Y. Lee, 1,2J. C. Lighthall, 5A. O. Macchiavelli, 1,2S. T. Marley, 2K. E. Rehm, 2J. P. Schiffer, 1D. V. Shetty, 8M. Wiedeking 1Department of Physics, Western Michigan University, Kalamazoo, Michigan 49008-5252, USA 2Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA 3Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA 4Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, Michigan 48824, USA 5Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA 6Department of Physics, University of Manchester 7LANSCE-NS, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA 8Lawrence Livermore National Laboratory, Livermore, California 94551, USA

  23. And… The HELIOS Collaboration S. Bedoor, J. C. Lighthall, S. T. Marley, D. Shetty, J. R. Winkelbauer (SULI student), A. H. Wuosmaa Western Michigan University B. B. Back, S. Baker, C. M. Deibel, C. R. Hoffman, B. Kay, H. Y. Lee, C. J. Lister, P. Mueller, K.E. Rehm, J. P. Schiffer, K. Teh, A. Vann (SULI student) Argonne National Laboratory S. J. Freeman University of Manchester Work supported by the U. S. Department of Energy, Office of Nuclear Physics, under contract numbers DE-FG02-04ER41320 (WMU) and DE-AC02-06CH11357 (ANL) Also, special thanks to: N. Antler, Z. Grelewicz, S. Heimsath, J. Rohrer, J. Snyder

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