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The Coulomb dissociation of 14Be

The Coulomb dissociation of 14Be. 宋玉收 哈尔滨工程大学 2013.1 上海. Contents. The background and the motivation The objective The contents of the experimental research Experiment solution Beam application. The background and the motivation. Low-lying dipole excitation mechanism;

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The Coulomb dissociation of 14Be

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  1. The Coulomb dissociation of 14Be 宋玉收 哈尔滨工程大学 2013.1 上海

  2. Contents • The background and the motivation • The objective • The contents of the experimental research • Experiment solution • Beam application

  3. The background and the motivation • Low-lying dipole excitation mechanism; • Scarcity of experimental results and large uncertainty of existed experimental data (14Be); • Theoretical calculation need more experimental support • Different from 11Li and 6He, three-body model or five-body model; • valence neutron and excited-core configuration ; • Coulomb excitation has larger cross section and is feasible for drip-line nuclei research at RIBLL;

  4. M. Labiche et. al, prl86.600.2001 68Ni、130,132Sn Coulomb dissociation

  5. prl86.600.2001 • Invariant mass spectrum; • Large (2s1/2)2 admixture; • prl86.600.2001, npa658.31.1999 • Enhanced low-lying strength of E1; • Large uncertainty of the exp. data; • No quantitative spectroscopic factor discussion in detail; • The peak position and integration of the energy spectrum deviate from the theoretical result; • No 2-n correlation discussion;

  6. Rrms (exp.) → • S2n (exp.) and Microscopic calculations (Cluster dynamics) prc52.704.1995, prc53.708.1996 Quantum Monte Carlo A-nucleon calculations (Many-body problem) npa654.157c.1999 semi-phenomenological description (npa706.48.2002) S2n=0.9MeV spectrum (exp.) peak position+ model

  7. S2n=0.9MeV S2n=1.34MeV S2n=1.34MeV, Rrms=3.10±0.15fm spectrum (exp.) peak position+ model • The narrow B(E1) shape is quite different from other Borromean halo nuclei; • vary the binding energy, the radius, and the admixture of different components of WF; • initial and final state WF considered;

  8. Integration of the excitation strength Similar as 8He and more complicated than 11Li, 6He.

  9. 1s1/2 0d5/2 0p1/2 0p3/2 s01/2 n complicated core structure should be considered 14Be S2n 13Be s-wave bound state 13Be 0d5/2 closed p shell? magic number loss or excited core? closed p shell

  10. In 2000’s 14Be Coulomb break up (14Be+Pb) prl86.600.2001 • 14Be nuclear break up (14Be+C, 14Be+p) • Rrms=3.25±0.11fm, npa875.8.2012 • The first 2+ state of 14Be, plb654.160.2007 • cluster breakup of 14Be, prc70.024608.2004 • systematic study of 14Be+C, npa791.267.2007 • Coulomb dissociation of Heavier nuclei close to neutron drip line • 31Ne Coulomb Breakup,PRL 103, 262501 (2009) • 19,20,22C Nuclear Breakup, N.Kobayashi et al., PRC, in press • Kinematically complete measurement of Coulomb Breakupof 22C, 19B, Production of 25,26O @SAMURAI@RIBF May 2012

  11. The objective • The correlation (spatial) of two valence neutrons by sum rule; • Spectroscopic factor of 2s1/2 and 1d5/2; • To verify the two-neutron bonding energy S2n; • To discuss the reasonability of 3-body and 5-body14Be model by the energy spectrum and neutron-removal cross section; • 12Be core is inert or not; • To understand systematically about the soft E1 excitation of 2-n halo nuclei like 6He, 11Li, 14Be; npa706.48.2002

  12. The contents of the experimental research • The kinematically complete measurement of the break up of 14Be on Pb target; • The angular distribution of 12Be+n+n in mass center coordinate; • Angular distribution of valence neutrons; • To reconstruct the invariant mass spectrum of 14Be; • To eliminate the nuclear interaction contribution from the transition strength by neglecting non-peripheral collision; • To obtain the reduce transition strength B(E1) by the virtual photon model;

  13. n 14Be 12Be n 12Be n n n 12Be n  Pb (high Z target ) Invariant Mass M 14Be* 12Be+n+n 14Be  Excitation Energy E*

  14. 11Li EMD reconstruction

  15. Spectroscopic factor Energy weighted sum rule (EWSR , non-model dependent) prc70.054606.2004

  16. M. Labiche et. al, prl86.600.2001 simulation EMD on Pb n-n correlated Non-correlated (independent particle model, 12=90。) Non-energy weighted sum rule (NEWS) r1=r2=r (3-body cluster calculation ) 12=?90 degree 2n correlated? npa542.310.1999

  17. Inert core? jkps61.27.2012 npa875.8.2012, Rmexp=3.25±0.11fm discrepancy

  18. the relation between binding energy, spectroscopic factor, and deformation coefficient . S2n core-excited probability

  19. MuNCos PPAC Si CsI Pb target Experiment solution • Experimental setup • PPAC • Forward ion telescope • MunCos

  20. level scheme of 12Be • Some problems to be pay more attention • No gamma detector presented; • 14Be、12Be particle identification, and coincidence between production ions and neutrons; • The influence of neutrons produced in the telescope on the detection of the break-up neutrons; • Position resolution and efficiency of detectors ahead target; • Target thickness

  21. 14.4/hour*200hour=2880 Beam application 200enA 的18O 作为入射初级束，3500um 的9Be 作为初级靶，降能器为2000um 的Al，分离提纯后的14Be，能量为35AMeV，能量展宽约8MeV（~1.6%），流强约为20 pps.

  22. Thanks

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