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Reaction Dynamics studies with 6,7 Li and 9 Be nuclei at Pelletron, Mumbai, India

Reaction Dynamics studies with 6,7 Li and 9 Be nuclei at Pelletron, Mumbai, India. Vivek Parkar University of Huelva, Spain. Previous affiliation : Bhabha Atomic Research Centre, Mumbai, India. Outline of Talk:. Introduction to 14UD Pelletron facility, Mumbai, India

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Reaction Dynamics studies with 6,7 Li and 9 Be nuclei at Pelletron, Mumbai, India

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  1. Reaction Dynamics studies with 6,7Li and 9Be nuclei at Pelletron, Mumbai, India Vivek Parkar University of Huelva, Spain Previous affiliation : Bhabha Atomic Research Centre, Mumbai, India 6th Dec 2011 ISOLDE Workshop, CERN

  2. Outline of Talk: • Introduction to 14UD Pelletron facility, Mumbai, India • Studies with stable weakly bound (6,7Li and 9Be) nuclei: • Fusion cross-sections • Inclusive and exclusive breakup • Dipole Polarizabilities of 7Li and 9Be • Future prospects with light RIBsat ISOLDE

  3. Started in 1988

  4. A] Basic Research • Reaction studies near barrier • Fission studies • Nuclear Structure • Atomic Physics • Radio Chemistry studies • Magnetism • B] Applied Research • Radiation damage studies • Radiation Biology • Accelerator Mass Spectroscopy (AMS) • Track etched membrane • Bio-environmental studies http://www.tifr.res.in/~pell

  5. Reactions with stable weakly bound nuclei Advantagelarge intensity and good beam quality Low breakup threshold Stable ions 6Li a+d, Sad=1.48 MeV 7Li a+t, Sat=2.47 MeV 9Be a+a+n, San=1.57 MeV • Study effect of breakup channel on elastic scattering and fusion cross-sections • Inclusive and exclusive breakup studies Next step: Reaction dynamics with light RIBs

  6. Fusion cross-sections from online and offline g-ray measurements Fusion in presence of breakup channel enhance fusion due to coupling OR suppress fusion due to loss of flux Motivation : 6,7Li+144,152Sm 6,7Li+90Zr 6,7Li+198Pt 6,7Li+165Ho 6,7Li+159Tb 9Be+124Sn 9Be+89Y Online g-ray technique: When ER is short lived (few secs)  g-ray de-excitation from the excited states of that ER Offline g-ray technique: When ER is long lived (few mnts - days)  Measurement of g-rays after beta decay/Electron capture sFusion = ΣsER

  7. Target & Catcher F.C. Beam Evaporation Residue Measurement Off-beam intensities of charac- teristic g-lines from b decay of ER and half-life were measured

  8. P. K. Rath et al., PRC 79, 051601R (2009) (Rapid Communication)

  9. Projectile breakup vs. target deformation Suppression (~28%) at E>Vb breakup Enhancement at E<Vb  target deformation Effect of breakup and deformation coexist P. K. Rath et al., Nucl Phys. A (Accepted)

  10. V.V.Parkar et al., PRC 82, 054601(2010) C. Palshetkar et al.,PRC 82, 044608 (2010)

  11. Systematic of fusion suppression factor (i) For a particular projectile, the suppression factor is more or less independent of the product ZPZT, (ii) suppression increases with decreasing breakup threshold of the projectile.

  12. Exploring fusion at deep sub-barrier energies New sensitive off-beam method KX - g rays coincidence A. Lemasson et al., NIMA 598, 445 (2009) A. Shrivastava et al., PRL 103, 232702 (2009)

  13. Inclusive and Exclusive breakup study 6Li+65Cu 6Li+209Bi 6,7Li+90Zr 9Be+89Y

  14. (a) (b) 7Li 6Li DE (arb. unit) a t,d,p E (arb. unit) (c) (d) Measurements: typical 2D spectra • Beam:6Li, Pelltron @TIFR • Energy: 24-50 MeV • Target:209Bi ~330 mg/cm2 self-supporting • 4 telescopes of SSB

  15. Inclusive alpha production • No evaporation alpha; Eaevp<Eacent • sincla~ direct reaction

  16. Universal behaviour of inclusive alpha cross-sections

  17. Complete reaction picture for 6Li+209Bi Below barrier, sa = sReaction Otherwise, sCF+sa= sReaction S. Santra et al., Phys. Rev. C (Submitted)

  18. Exclusive breakup study of 6Li M1 250 6Li Beam (~40nA) FC 209Bi (1 mg/cm2) 100 T1(a) 100 M2 100 T2(d) T3(a) T4(d) Detectors: 2 telescopes (DE: ~ 33mand E: ~500m), 2 telescopes (DE:~150mand E: ~1000m), and 2 single monitors (E ~2000m) of Si surface barrier detectors Measured: Light charged particles in singles as well as coincidence, in list mode Angular range: 50o-170o. Energy: 36 and 40 MeV

  19. Projectile breakup Direct breakup: Projectile breaks up directly into fragments at any excitation energy larger than breakup threshold. a 209Bi 6Li d 6Li Sequential breakup: Projectile excited to resonant state followed by breakup, or it can exchange a few nucleon with the target and then breaks up. 209Bi a 209Bi a 6Li n 6Li p d 5Li 6Li* 6Li*

  20. T1 @ 55o T2 @ 65o Counts Ch. No. Typical two dimensional spectra with and without coincidence conditions.

  21. Inclusive and exclusive a-production • CDCC results with full coupling agrees with the average of two sets of experimental data for 3+ resonant state • Total sad (theory) << sa(incl) • sap(exp) + sad(th)<< sa(incl) • Other possible sources : (1) (6Li,4He) (2) (6Li,5Hen+4He) (3) (6Li,7Li4He+t) (4) partial fusion (d-cap) S. Santra et al., PLB 677, 139 (2009)

  22. Elastic scattering Dipole polarizability of 7Li, 9Be

  23. Introduction • Centre of matter distributions and centre of charge distributions of a nucleus do not coincide (e.g. deuteron, 7Li, 6He, 11Li etc.) in the presence of strong electric field. • Transition between states of opposite parity. (For normal nuclei states of opposite parity are at high excitation energy) • For weakly bound nuclei  low breakup threshold, continuum states of opposite parity are nearby. • The effect is very small. (2% change in elastic cross section of d + 208Pb (αd=0.70 fm3), Similar effect expected for 7Li + 208Pb (α7Li =0.018-0.048 fm3).

  24. Experimental Details • Beam:-7Li Target :-enriched 208Pb (on Carbon backing) Beam energies :-E7Li= 18-28 MeV (All energies below Coulomb Barrier) T1: + 400 T4: + 1600 7Li Beam FC 208Pb T2: - 400 T3: - 1600

  25. Measured Spectra

  26. CDCC Calculation Details • The diagonal and coupling potentials calculated using cluster folding method, a Va r R t Vt 208Pb R – 7Li - target separation r - separation between clusters. Continue……

  27. A value of DP found from a precise measurement of elastic scattering data to be, a = 0.045 fm3 Loosely bound unstable nuclei (e.g. 6He, 11Li, 11Be) DP effect more important. Polarizability parameter a V. V. Parkar et al., Phys. Rev. C (Rapid Com.), 78, 021601R (2008)

  28. For 9Be : S. K. Pandit et al., Phys. Rev. C (Rapid Com.), 84, 031601R (2011)

  29. Future prospective at ISOLDE • Reactions with 8,9,11Li and 7,10,11,12,14Be on similar targets to study complete reaction dynamics and compare with existing 6,7Li and 9Be data • Dipole polarizability studies for number of nuclei GLORIA Array @ UHU, Spain

  30. Team Members S. Kailas, A. Chatterjee, S. Santra, A. Shrivastava, K. Mahata, K. Ramachandran, V. Jha, B. J. Roy, S. K. Pandit, P. K. Rath Nuclear Physics Division, BARC, Mumbai V. Nanal, R. G. Pillay, R. Palit DNAP, TIFR, Mumbai

  31. THANK YOU

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