Bogdan Fornal. Institute of Nuclear Physics, Polish Academy of Sciences Krakow, Poland

Transcription

1 Bogdan Fornal Institute of Nuclear Physics, Polish Academy of Sciences Krakow, Poland Collaboration: IFJ PAN Krakow - ANL Argonne - ANU Canberra The Nuclear Structure Workshop at the Weizmann Institute, April 11-12, 2011, Rehovot, Israel

2 Outline How to access excited structures in the neutron-rich nuclei lying south of 208 Pb deep-inelastic reactions fragmentation reactions New yrast structures in nuclei located south of 208 Pb Empirical shell model calculations around 208 Pb and the comparison with experiment for nuclei below 208 Pb Realistic V low-k shell model calculations in the vicinity of 208 Pb and their predictive power Perspectives for the spectroscopic studies south-east of 208 Pb

3 How to access YRAST states in neutron-rich nuclei south of 208 Pb

4 Experimental techniques used to access YRAST states in neutron-rich nuclei near 208 Pb deep-inelastic processes occurring during heavy- ion reactions prompt gamma-ray spectroscopy isomer gamma-ray spectroscopy fragmentation reactions at intermediate energies isomer gamma-ray spectroscopy

5 Deep-inelastic heavy-ion reactions a tool for gamma-ray spectroscopy of neutron-rich nuclei γ-ray array (e.g.,gs, GASP, EUROB.,AGATA) γ-ray array + magnetic spectr. e.g., CLARA+PRISMA, EXOGAM+VAMOS

6 Experimental technique that we used to access YRAST states in neutron-rich nuclei around 208 Pb: γ-ray spectroscopy of deep-inelastic reaction products following the reactions 208 Pb+ 238 U or 48 Ca+ 238 U

7 N/Z equilibration line for 208 Pb+ 238 U 208 Pb U 208 Pb N/Z equilibration line for 48 Ca+ 238 U 48 Ca U 48 Ca 238 U

8 Product distribution in deep-inelastic reactions of 208 Pb+ 238 U and 48 Ca+ 238 U 48 Ca U N/Z equilibration line for 48 Ca+ 238 U N/Z equilibration line for 208 Pb+ 238 U 208 Pb U

9 The level scheme of 203Hg from the 48Ca + 238U reactions studied by using γ γ γ coincidence thick-target technique with GAMMASPHERE

10 Spectrum gated on gamma rays below the isomer in 209Tl using the thick-target GAMMASPHERE data from 208Pb+238U reaction from GAMMASPHERE at Argonne from RISING at GSI N. Al-Dahan et al., Phys. Rev. C. 40, (R) (2009).

11 The nuclei around 208 Pb, produced in deep-inelastic reactions 48 Ca+ 238 U and 208 Pb+ 238 U, in which we have identified yrast structures by using γ γ γ coincidence thick-target technique with GAMMASPHERE 48 Ca U Bi Pb Tl Hg Po Pb U

12 Results on the most neutron-rich nuclei around 208Pb produced in the 208Pb + 238U reaction and studied by using the γ γ γ coincidence thick-target technique with GAMMASPHERE Hg B. Fornal et al., Phys. Rev. Lett. 87 (2001) 210Pb G. Lane et al., Nucl. Phys. A682 (2001) Pb G. Lane et al., Phys. Lett. B (2005) 209Tl 208Hg B. Fornal et al., Proc. Vietri Conf. (2010)

13 Results on neutron-rich nuclei around 208Pb produced in the 48Ca + 238U reaction and studied by using the γ γ γ coincidence thick-target technique with GAMMASPHERE Hg B. Szpak et al., submitted to Phys. Rev. C 204Hg G. Lane at al.., in preparation. 205Tl J. Wrzesinski et al., Eur. Phys. J. A (2004)

14 The modified Kuo-Herling empirical interaction For spin-parity assignments we used as a guidance the results of shell model calculations with the modified Kuo-Herling interaction in the configuration space Z<82 and N<126. We modified the original Kuo-Herling interaction in order to account for: recent revison of the 207 Tl mass; recently located yrast states in 204 Pt, 205 Au, 205 Pb, 206 Pb, 206 Tl, 206 Hg.

15 Comparison between the experiment and results of calculations with the modified Kuo-Herling interaction for magic neutron-hole or proton-hole nuclei lying near 208Pb

16 203Hg Spin-parity assignments based on the comparison with the modified Kuo-Herling shell model calculations Kuo-Herling modified experiment Hg

17 Comparison between the experiment and results of calculations with the modified Kuo-Herling interaction for neutron-hole proton-hole Hg isotopes Mapa nuklidow

18 Spin-parity assignments based on the comparison with the modified Kuo-Herling shell model calculations for nuclei lying east and south-east of 208Pb

19 Realistic shell model calculations using a V low-k approach a theoretical framework for microscopic shell-model calculations starting from the free nucleon nucleon potential M.Hjorth-Jensen, T.T.S.Kuo, E.Osnes, Physics Reports 261, (1995). A.Covello, L.Coraggio, A.Gargano, N.Itaco, Prog. Part. Nucl. Phys. 59, 404 (2007). L.Coraggio, A.Covello, A.Gargano, N.Itaco, T.T.S Kuo Prog. Part. Nucl. Phys. 62, 135 (2009). S.K. Bogner, R.J. Furnstahl, A. Schwenk Prog. Part. Nucl. Phys. 65, 94 (2010).

20 To get the V low-k effective interaction we used: Computational Environment for Nuclear Structure (CENS) Authors: T. Engeland, M.Hjorth-Jensen and G.R. Jansen Reference article: M.Hjorth-Jensen, T.T.S.Kuo, E.Osnes, Physics Reports 261, (1995) CD-Bonn potential, Λ=2.2 fm -1, model spaces: (Z=50-82, N=82-126), (Z=50-82, N= ) For shell-model calculations we used: computer code OXBASH, B. A. Brown, A. Etchegoyen, W. D. M. Rae, N. S. Goldwin, W. A. Richter, C. H. Zimmerman, W. E. Ormand, and J. S. Winfield, MSU-NSCL Report No. 524, s.p.s. energies from experiment; for Z 82 and N 126 the TBME s multiplied by (132/208) 1/3

21 Comparison between the experiment and realistic Vlow-k shell model calculations for the magic neutronhole or proton-hole nuclei lying near 208Pb

22 Comparison between the experiment and realistic Vlow-k shell model calculations for neutron-hole proton-hole Hg isotopes

23 Comparison between the experiment and realistic Vlow-k shell model calculations for nuclei lying east and south-east of 208Pb

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25 Perspectives for accessing neutron-rich nuclei near 208Pb by using a radioactive beam of 132Sn ine l on i t ra 238 U b i l ui 8 b+ q e 20 P Z N/ for Let s consider reactions: 208Pb 132Sn + 208Pb ine l on b i t ra 208 P b i l ui n + q e 2S Z r 13 / N fo + 238U

26 Deep-inelastic reaction 132Sn + 208Pb at Ebeam=750 MeV with an intermediate-thick target The kinematics is favorable for stopping Pb-like neutron-rich nuclei in the target 206Au 131I

27 Conclusions and Outlook Gamma-ray spectroscopic studies with deep-inelastic reactions provide means for accessing yrast structures in nuclei located south of doubly magic 208 Pb. New yrast structures identified in 203,204,206,208 Hg, 205,209 Tl and 210,211 Pb form a very good testing ground for the V low-k realistic shell model calculations in the regions of neutron-rich nuclei. Calculations with the V low-k realistic interaction around 208 Pb provide a good description of yrast states in the Z=82 Pb isotopes, N=126 isotones and nuclei with Z<82 and N>126. It is less satisfactory for the nuclides from the region Z<82 and N<126 (having neutron and proton holes)

28 Collaborators B. Szpak, K.H. Maier, R. Broda, W. Krolas, T. Pawlat, J. Wrzesinski, B. Fornal IFJ PAN Krakow, Poland R.V.F. Janssens, S. Zhu, M.P. Carpenter, D. Seweryniak et al. ANL Argonne, USA G. Lane, G. Dracoulis et al. ANU Canberra, Australia