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Recent Few-Body Activities at TUNL and HI g S

Recent Few-Body Activities at TUNL and HI g S. Werner Tornow. Duke University & Triangle Universities Nuclear Laboratory. Content. A. TUNL: Polarized Neutrons. 1. n-p A y ( q ) at E n =12 MeV 2. n-d A y ( q ) between E n =19 and 22.5 MeV

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Recent Few-Body Activities at TUNL and HI g S

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  1. Recent Few-Body Activities at TUNL and HIgS Werner Tornow Duke University & Triangle Universities Nuclear Laboratory

  2. Content A. TUNL: Polarized Neutrons 1. n-p Ay(q) at En=12 MeV 2. n-d Ay(q) between En=19 and 22.5 MeV 3. n-3He Ay(q) between En=2.26 and 5.54 MeV B. HIgS: Linearly Polarized Gamma-rays • g-d breakup photon analyzing power SL(q) from 2.4 to 10 MeV • g-3He three-body breakup photon analyzing power SL(q) at 15 and 12.8 MeV

  3. Nijm PWA n-p

  4. R. Machleidt: pNN coupling constant to correctly reproduce the quadrupole moment of the deuteron [0.276(2) fm2]. Nijmegen: =13.47+-0.11 =13.54+-0.05 13.9 13.3 VPI: creates problems for the 3P0 NN phase shifts (too large!) at low energies. and Assume charge splitting of pNN: 3P0 and are o.k.

  5. / CD Bonn 13.6 / 13.6 Nijm PWA 13.6 / 14.0 13.6 / 14.4 All low-energy n-p AY(q) data require

  6. Witala n-d n-d n-d

  7. AV18 Witala .… Fit Ay qc.m.

  8. AV18 Witala …. Fit

  9. TUNL data Pisa calc. p-3He p-3He

  10. TUNL data Pisa calc. p-3He p-3He

  11. NN Interactions in 3N and 4N Systems d d n p n p 3N: 1 pn + 1pp 1 pn + 1 nn p + n + 3He 3He p p n p p n 1 pn + 2 pp p + n + 2 pn + 1 nn 4N: 3H 3H n n p n n p n + 1 pn + 2 nn p + 2 pn + 1 pp

  12. Fonseca …. Hale RM Ay 180 qc.m.

  13. HIgS (High-Intensity Gamma-ray Source) at Duke/TUNL • Nearly Mono-energetic g-rays • Tunable Energies • Energy resolution selected by collimator size • Linearly and Circularly Polarized g-rays • High Beam Intensities • Pulsed Beam • TOF Techniques to reduce non-beam related backgrounds

  14. (2) 1.2-GeV Booster Injector (3a) Building extension + booster radiation shielding (3b) LTB Transfer Line (3c) BTR Transfer Line (1) RF System with HOM Damping (3e) Radiation shielding over SR east arc 3(d) Modifications to SR NSS Upgraded Facility

  15. Upgrade Schedule • Commissioning of Booster July-August 2006 • Commissioning of Booster and Ring with OK-4—September-November Nuclear Physics Program begins-December, 2006 • Dec. 06  May 07 Linear Pol.- Below 65 MeV, >2x108 g/s • Sept. 07  Circ. Pol. Up to 110 MeV, >108 g/s • These are TOTAL intensities. Beam on target is: • TOTAL x 1.5 x % resolution (ex. 5% res. at 100 MeV: 7.5 x 106 g/s) • Expect to have energies up to 160 MeV by Spring 09

  16. Few-Body Physics @ HIgS • Resolve long standing cross section problems. • Perform Precision tests of few-body theory including EFTs and 3-body force models using polarized beams and targets. • Measure fundamental properties such as the electric polarizabilities for 3He and 4He via Compton scattering. • Measure the GDH sum rule integral below pion threshold for d and 3He.

  17. Two-Body System • Gamma-Deuteron Breakup at Low Energies

  18. Detector Geometry : 3He scintillator 1 : neutron detector (lab) 2 4 : Asymmetry 3 :g-ray linear polarization : Analyzing power

  19. W. Tornow, C. Howell, V. Litvinenko, J. Kelley, et al.

  20. The cross section and the linear analyzing power

  21. Blowfish Detector Array Norum/Weller

  22. The Gerasimov-Drell-Hearn (GDH) Sum Rule for Deuteron P/A(E) are the total cross sections for the absorption of circularly polarized photons on a target with spin Parallel/Antiparallel to the spin of the photon;  = anomalous magnetic moment (of the deuteron). d = -0.143 m IGDH Predicted = 0.65b

  23. THE GDH INTEGRAND FOR THE DEUTERON NEAR PHOTODISINTEGRATION THRESHOLD Contributions are expected from s-waves and p-waves (notation 2S+1LJ) M1 terms: 1S0 and 3S1 E1 terms: 1P1, 3P0, 3P1, and 3P2 Expect the “spin-flip” E1 term 1P1 ~ 0. ThensP - sA = p/2k2 { - 1S02 – 3/2 3S12 - 3P02 – 3/2 3P12 + 5/2 3P22 } Expect 3P0 ~ 3P1 ~ 3P2 , and 3S1 ~ 0. So that sP - sA = p/2k2 { - 1S02 } Also, with 3S1 ~ 0 we have: s(M1) = p/6k2 {1S02 } Which gives the result: sP - sA = -3 s(M1)

  24. Tornow’s Group Norum/Weller’s Group

  25. Three-Body Photodisintegration of 3He • Reaction: g + 3He  p+ p + n • Eg=15 MeV • Tornow’s Group MeV

  26. Detector Geometry : 3He scintillator 1 : neutron detector (lab) 2 4 : Asymmetry 3 :g-ray linear polarization : Analyzing power

  27. n+p+p g+3He Deltuva et al.

  28. Photon Analyzing Power for 3He(g,pp)n

  29. Time-of-Flight vs. SEp Spectra g n g n

  30. Time-of-Flight Spectra

  31. Photon Analyzing Power for 3He(g,pp)n • For neutrons in the energy range 1.23 to 4.80 MeV, s-weighted average of the photon analyzing power: • Theoretical prediction: SL(qn=90°) = 0.949 • Experimental result: SL(qn=90°) = 0.95±0.01

  32. Three-Body Photodisintegration of 3He • Target: 3He-Xe gas scintillator • 47 atm 3He, 3 atm Xe • Not enough stopping power for high-energy protons: they don’t deposit all of their energy: Edge effects: Scintillator housing g-ray beam

  33. Three-Body Photodisintegration of 3He • Reaction: g + 3He  p+ p + n • Eg=12.8 MeV • Weller’s Group MeV

  34. The upgraded BLOWFISH array and a 6.5 cm gas cell containing 2500 psi of 3He was used to measure the 3He(g,n)pp reaction with 12.8 MeV linearly polarized g rays.

  35. Two-Body Photodisintegration of 3He • Reaction: g + 3He  p + d • Q = -5.49 MeV • Observable: Total cross section • Measured at Eg = 8.0, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, 12.0, 12.5, 13.0, 14.0, 15.0, and 16.0 MeV (13 energies) • Previously measured using a variety of techniques (bremsstrahlung photons, virtual photons from e-3He scattering, pd capture via detailed balance); results in disagreement

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