1 / 25

Jeff Tostevin Department of Physics School of Electronics and Physical Sciences

Reactions using nucleon knockout RISING Workshop Surrey, 29 th -30 th March 2004. Jeff Tostevin Department of Physics School of Electronics and Physical Sciences University of Surrey, UK. A. P 0. P ||. One- and two-nucleon knockout reactions.

barbie
Télécharger la présentation

Jeff Tostevin Department of Physics School of Electronics and Physical Sciences

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Reactions using nucleon knockout RISING Workshop Surrey, 29th-30th March 2004 Jeff Tostevin Department of Physics School of Electronics and Physical Sciences University of Surrey, UK RISING Workshop, Surrey, 29th-30th March 2004

  2. A P0 P|| One- and two-nucleon knockout reactions Peripheral collisions (E  50A MeV; MSU, RIKEN, GSI) g heavy mass A residue is detected, with coincident -ray detection A+xN T+xN light target T=9Be,12C Sudden removal of nucleons Target T left in g.s. or excited state Events contributing will be both break-up and stripping both of which leave a mass A residue in the final state RISING Workshop, Surrey, 29th-30th March 2004

  3. One- and two nucleon knockout – to date One-nucleon knockout predominantly – proof of purpose and of accuracy Light nucleus sector – p and sd-shell (Ni looked at but not optimum detection/resolution) Small number of final states and gamma-rays Semi-classical (eikonal) reaction theory seems to work quantitatively. RISING Workshop, Surrey, 29th-30th March 2004

  4. Orientation for magnitudes - extreme sp model Single neutron removal from 23O  [1d5/2]6 [2s1/2] n sp(2s1/2)=64 mb 2s1/2 Sn=2.7 MeV sp(1d5/2)=23 mb 1d5/2 Sn=5.5 MeV -n = 6 sp(1d5/2)+sp(2s1/2) = (138 + 64) = 202 mb typical cross sections 20 – 30 mb RIKEN (PRL 88 (‘02) 142502) 72 MeV/u + 12C target; -n = 233(37)mb RISING Workshop, Surrey, 29th-30th March 2004

  5. Single-neutron knockout from 17C =0,2 admixture =0,2 admixture =2 pure V. Maddalena et al. PRC 63 (2001) 024613 RISING Workshop, Surrey, 29th-30th March 2004

  6. Spectroscopic factor - occupancy of the state Structure – we probe single particle overlaps Nucleon removal from A+1 will leave mass A residue in the ground or an excited state - amplitude for finding nucleon with sp quantum numbers ,j, about core state c in A+1 is Usual to write RISING Workshop, Surrey, 29th-30th March 2004

  7. Experimental v shell model spectroscopic factors Can define reduction factor th Shell model structure plus eikonal reaction More bound systems P.G. Hansen and J.A.Tostevin, ARNPS 53 (2003), 219 RISING Workshop, Surrey, 29th-30th March 2004

  8. Rs factors – deviations from the shell model RISING Workshop, Surrey, 29th-30th March 2004

  9. 30S 28S 26P 28P 24Si 26Si 2n from neutron deficient Two nucleon knockout – go south, or west Z 2p from neutron rich 34Si 32Al 34Al 28Mg 30Mg 32Mg 28Na 30Na 32Na 26Ne 30Ne 28Ne N RISING Workshop, Surrey, 29th-30th March 2004

  10. 2p knockout – production or detailed spectroscopy? reaction mechanism is? production rate R production rate R/1000 30Ne 32Mg could gain x100 rate 2p knockout (~1mb) e.g.Coulex 30Ne D. Bazin et al., PRL 91 (2003) 012501. RISING Workshop, Surrey, 29th-30th March 2004

  11. 40 2s1/2 1d5/2 1p1/2 20 1p3/2 0 2p removal Two nucleon knockout – reaction mechanism 23O  21O 28Mg  26Ne -1n n + 21O -1n 1  22O 2+ 0+ D. Bazin et al., PRL 91 (2003) 012501 RISING Workshop, Surrey, 29th-30th March 2004

  12. 1 2 c A p particles q particles Direct two nucleon knockout – uncorrelated Estimate assuming removal of a pair of uncorrelated nucleons - contribution from direct 2N removal D. Bazin et al., PRL 91 (2003) 012501 RISING Workshop, Surrey, 29th-30th March 2004

  13. 1 2 c A Uncorrelated two proton removal D. Bazin et al., PRL 91 (2003) 012501 28Mg 26Ne(inclusive) with weights 0+: 1.33 to the 26Ne 2+: 1.67 final states 4+: 3.00 RISING Workshop, Surrey, 29th-30th March 2004

  14. 1 2 c A Correlated two proton removal amplitudes of nucleon- pair wave functions about core configurations c. Spin states populated There is now no SF factorisation J.A. Tostevin et al., RNB6 proceedings, in press RISING Workshop, Surrey, 29th-30th March 2004

  15. 28Mg 26Ne(0+) C(2s1/2)2 = – 0.305 C(1d3/2)2 = – 0.301 C(1d5/2)2 = – 1.05 Shell model (sd-shell) 2N amplitudes 28Mg 26Ne(2+) C(1d3/2)2 = – 0.050 C(d5/2,d3/2)= + 0.374 C(1d5/2)2 = – 0.637 C(s1/2,d5/2)= – 0.061 C(s1/2,d3/2)= – 0.139 28Mg 26Ne(4+) C(d5/2,d3/2) = 0.331 C(1d5/2)2 = 1.596 B.A. Brown, private communication RISING Workshop, Surrey, 29th-30th March 2004

  16. SthSexpSthexpth unc. corr. (mb) (mb) 0+ 1.33 2.4(5)1.83 0.70(15) 0.53 2+ 1.67 0.3(5)0.55 0.09(15) 0.16 4+ 3.00 2.0(3)1.79 0.58(9)0.52 2+ - 0.5(3)0.76 0.15(9) 0.22 Inclusive cross section (in mb)1.50(10) 1.43 Cross sections – correlated and uncorrelated 28Mg 26Ne(0+, 2+, 4+) S = (in mb) / 0.29 J.A. Tostevin, G. Podolyák, et al., RNB6 proceedings, in press, and in preparation RISING Workshop, Surrey, 29th-30th March 2004

  17. P0 Nature of the two-nucleon correlations Removed nucleon pair are spatially correlated but no restriction on pair spin S or relative orbital angular momentum in formalism. All contributing pair wave functions are included. Unlike.e.g. (p,t) reaction – where angular momentum selection on the p | t  vertex selects nn pair in S=0, T=1, relative s-state configuration. Can assess by projecting [ T=1, S=0,  =0 ] relative motion component from the pair wave functions  Sth(rel) RISING Workshop, Surrey, 29th-30th March 2004

  18. SthSexpSth rel corr. 0+ 1.60 2.4(5)1.83 2+ 0.14 0.3(5)0.55 4+ 2.00 2.0(3)1.79 2+ 0.46 0.5(3)0.76 Cross sections – relative s-state correlations 28Mg 26Ne(0+, 2+, 4+ ,2+) D. Bazin et al., PRL 91 (2003) 012501 J.A. Tostevin, G. Podolyák, et al., RNB6 proceedings, in press, and in preparation RISING Workshop, Surrey, 29th-30th March 2004

  19. RISING Workshop, Surrey, 29th-30th March 2004

  20. Energy/nucleon 1.05 GeV 250 MeV 2.10 GeV Test case - earlier data from Berkeley (~10%) Kidd et al., Phys Rev C 37 (1988) 2613 2N removal from 12C B.A. Brown, 2N amplitudes J.A. Tostevin et al., RNB6 proceedings, in press and in preparation RISING Workshop, Surrey, 29th-30th March 2004

  21. b Surface localisation of knockout reactions 12Be+9Be  11Be(gs)+X, 80A MeV Eikonal theory: localisation provided by core survival requirement c 12Be v 9Be RISING Workshop, Surrey, 29th-30th March 2004

  22. Skyrme Hartree-Fock radii and densities (1) W.A. Richter and B.A. Brown, Phys. Rev. C67 (2003) 034317 RISING Workshop, Surrey, 29th-30th March 2004

  23. Skyrme Hartree-Fock radii and densities (2) B.A. Brown, S. Typel, and W.A. Richter, Phys. Rev. C65 (2002) 014612 RISING Workshop, Surrey, 29th-30th March 2004

  24. neutron • proton Weakly bound states – with good statistics Reduction Factor Rs P.G. Hansen and J.A.Tostevin, ARNPS 53 (2003), 219 RISING Workshop, Surrey, 29th-30th March 2004

  25. neutron • proton More strongly bound states – deep hole states Reduction Factor Rs inclusive P.G. Hansen and J.A.Tostevin, ARNPS 53 (2003), 219 RISING Workshop, Surrey, 29th-30th March 2004

More Related