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Binary Reaction Spectroscopy from A=100-200

Binary Reaction Spectroscopy from A=100-200. Paddy Regan Dept. of Physics, University of Surrey, Guildford, GU2 7XH, UK e-mail: p.regan@surrey.ac.uk. Problems with neutron-rich spectroscopy ? Production (RIBs, fission, binary reactions). Small cross-sections, need high efficiencies.

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Binary Reaction Spectroscopy from A=100-200

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  1. Binary Reaction Spectroscopy from A=100-200 Paddy Regan Dept. of Physics, University of Surrey, Guildford, GU2 7XH, UK e-mail: p.regan@surrey.ac.uk

  2. Problems with neutron-rich spectroscopy ? • Production (RIBs, fission, binary reactions). • Small cross-sections, need high efficiencies. • Identification (N,Z) • lots of products, need clean id or ‘tags’ (e.g. isomers) • Population in (Ex,I) plane (reaction selection) • need to know spin/excitation energy range of products

  3. Aim? To perform high-spin physics in stable and neutron rich nuclei. Problem: Fusion makes proton-rich nuclei. Solutions? (a)fragmentation (b) binary collisions/multi-nucleon transfer Modified from Introductory Nuclear Physics, Hodgson, Gadioli and Gadioli Erba, Oxford Press (2000) p509 See eg. Bock et al., Nukleonika 22 (1977) p529 Broda et al. Phys. Rev Lett. 74 (1995) p868 Juutinen et al. Phys. Lett. 386B (1996) p80 Wheldon et al. Phys. Lett. 425B (1998) p239 Cocks et al. J. Phys. G26 (2000) p23 Krolas et al. Acta. Phys. Pol. B27 (1996) p493 Asztalos et al. Phys. Rev. C60(1999) 044307

  4. (iii) (ii) (i) Ebeam ~15-20% above Coulomb barrier beam target Z N Can not use fusion-evaporation reactions to study high-spin states (and thus vibrational-rotational transitions, alignments etc.) in beta-stable and neutron-rich systems. Use deep-inelastic reactions.

  5. z x q1 q2 f1 f2 y

  6. 198Pt +136Xe, 850 MeV

  7. 8+ dominated by Coulex in 198Pt. High-spin isomers kill prompt DIC

  8. BLFs TLFs elastics 100Mo + 136Xe @ 750 MeV GAMMASPHERE + CHICO

  9. BLFs TLFs elastics

  10. Wilczynski Plot

  11. Isomer gating very useful in DIC experiments. Test with known case…..

  12. Pt+Xe Mo+Xe

  13. Semi - classicall y the max. peripheral ang. mom. is A . A ( ) B T l 0 . 219 R E V and max CM CM A A B T The grazing angle where the DIC cross - section is max. is given by the distance of closest approach, d , where ( ) 2 Z Z e graz 1 / 3 1 / 3 1 2 d . 1 cosec 1 . 25 A A fm B T 4 E 2 0 k In the rolling mode limit, l is split into l , l and max tlf blf the relative ang. mom. between th e two fragments. ö ç ÷ ç ÷ 2 1 2 1 ç ÷ l l l l ç ÷ tlf max blf max 1 1 7 7 A A 3 3 ç ÷ 1 B 1 T ç ÷ A A è ø T B = m - m = + æ ö q é ù ì ü ç ÷ = + = + í ý ê ú ç ÷ pe î þ ë û è ø æ ö æ ç ÷ ç ÷ ç ÷ = = ç ÷ æ ö æ ö ç ÷ ç ÷ ç ÷ + + ç ÷ ç ÷ ç ÷ è ø è ø è ø

  14. Kinematics and angular mom. input calcs (assumes ‘rolling mode’) for 136Xe beam on 100Mo target. Estimate ~ 25hbar in TLF for ~25% above Coul. barrier. For Eb(136Xe)~750 MeV, in lab qblf~30o and qtlf~50o. 100Mo +136Xe (beam) DIC calcs.

  15. Future plans? High spins (SD at I~25) in 99,100Mo. (cf. 136Xe beam with 208Pb and 238U (fission prob)

  16. Podolyak et al. Phys. Lett. 491B (2000) 225

  17. New isomer in 195Os confirmed ‘in-beam’ CHICO+GAMMASPHERE Dobon, Wheldon, Regan et al.,

  18. beam-like fragment isomers.

  19. Target-like fragment isomers

  20. Identification of new isomeric state in 136Ba, N=80 isotone.

  21. N=80 isotonic chain, 10+ isomers Q. Why does Ex(10+) increase while E(2+) decreases ?

  22. Structure of 8+ appears to change from 134Xe -> 136Ba ?

  23. 82Se+192Os GaSp backed target data (Podolyak, Mohammadi, DeAngelis et al.) 1565 keV gate 2+->0+ in 86Kr Double gate on 143 and 298 keV in 188W. 432 keV 6+ in 188W

  24. many thanks to...... • Jose Javier Valiente Dobon (Pt)+ Arata Yamamoto (Mo)Zsolt Podolyak, Saeed Mohammadi, Chris Pearson, Scott Langdown, Karin Andgren (Surrey). Furong Xu (Bejing). • Carl Wheldon (Surrey -> GSI) Spokesperson for 136Xe+198Pt. • CHICO + GAMMASPHERE Experiments • Rochester (Chin-Yen Wu, Doug Cline, Adam Hayes, Hui Hua, Ray Teng et al.,) • LBNL (Augusto Macchiavelli, Paul Fallon, I-Yang Lee, Mario Cromaz) • Manchester. (John Smith, Sean Freeman, Ravi Chakrawarthy) • Daresbury (Dave Warner), • Paisley (Bob Chapman, Xiaoying Liang) • Vibrator-Rotator (E-GOS) plots, Con Beausang, Rick Casten, Victor Zamfir, Jing-Ye Zhang.

  25. NUSTAR’05International Conference onNUclear STructure, Astrophysics and Reactions The University of Surrey, Guildford, UK5-8 January 2005

  26. See strong lines in 84,86Kr (binary partners of 190,188W). Identify first three states in 188W. GaSp 82Se+192Os (backed target) GaSp, Podolyak, Mohammadi et al.,

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