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Title: Sub-Barrier Coulomb Excitation of {sup 110}Sn and Its Implications for the {sup 100}Sn Shell Closure

Abstract

The first excited 2{sup +} state of the unstable isotope {sup 110}Sn has been studied in safe Coulomb excitation at 2.82 MeV/u using the MINIBALL array at the REX-ISOLDE post accelerator at CERN. This is the first measurement of the reduced transition probability of this state using this method for a neutron deficient Sn isotope. The strength of the approach lies in the excellent peak-to-background ratio that is achieved. The extracted reduced transition probability, B(E2:0{sup +}{yields}2{sup +})=0.220{+-}0.022e{sup 2}b{sup 2}, strengthens the observation of the evolution of the B(E2) values of neutron deficient Sn isotopes that was observed recently in intermediate-energy Coulomb excitation of {sup 108}Sn. It implies that the trend of these reduced transition probabilities in the even-even Sn isotopes is not symmetric with respect to the midshell mass number A=116 as {sup 100}Sn is approached.

Authors:
 [1];  [2]; ;  [3]; ;  [4];  [5];  [6];  [7];  [8];  [9];  [10]; ; ; ;  [11];  [12]; ;  [1]; more »;  [7];  [13] « less
  1. PH Department, CERN 1211, Geneva 23 (Switzerland)
  2. (Sweden)
  3. Physics Department, University of Lund (Sweden)
  4. Oliver Lodge Laboratory, University of Liverpool (United Kingdom)
  5. Physics Department and Center of Mathematics for Applications, University of Oslo (Norway)
  6. TRIUMF, Vancouver (Canada)
  7. Gesellschaft fuer Schwerionenforschung (GSI), Darmstadt (Germany)
  8. (Germany)
  9. Department of Physics and Astronomy, University of Edingburgh (United Kingdom)
  10. Saha Institute of Nuclear Physics, Kolkata 700064 (India)
  11. Institute of Nuclear Physics, University of Cologne (Germany)
  12. IPN Orsay, Orsay (France)
  13. Physics Department, Ludwig-Maximilian University, Munich (Germany) (and others)
Publication Date:
OSTI Identifier:
20951273
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Letters; Journal Volume: 98; Journal Issue: 17; Other Information: DOI: 10.1103/PhysRevLett.98.172501; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; CERN; COULOMB EXCITATION; NEUTRON-DEFICIENT ISOTOPES; PROBABILITY; SHELL MODELS; TIN 100; TIN 108; TIN 110

Citation Formats

Cederkaell, J., Physics Department, University of Lund, Ekstroem, A., Fahlander, C., Hurst, A. M., Butler, P. A., Hjorth-Jensen, M., Ames, F., Banu, A., Institute for Nuclear Physics, University of Mainz, Davinson, T., Pramanik, U. Datta, Eberth, J., Reiter, P., Warr, N., Weisshaar, D., Franchoo, S., Georgiev, G., Koester, U., Gorska, M., Kester, O., and Habs, D. Sub-Barrier Coulomb Excitation of {sup 110}Sn and Its Implications for the {sup 100}Sn Shell Closure. United States: N. p., 2007. Web. doi:10.1103/PHYSREVLETT.98.172501.
Cederkaell, J., Physics Department, University of Lund, Ekstroem, A., Fahlander, C., Hurst, A. M., Butler, P. A., Hjorth-Jensen, M., Ames, F., Banu, A., Institute for Nuclear Physics, University of Mainz, Davinson, T., Pramanik, U. Datta, Eberth, J., Reiter, P., Warr, N., Weisshaar, D., Franchoo, S., Georgiev, G., Koester, U., Gorska, M., Kester, O., & Habs, D. Sub-Barrier Coulomb Excitation of {sup 110}Sn and Its Implications for the {sup 100}Sn Shell Closure. United States. doi:10.1103/PHYSREVLETT.98.172501.
Cederkaell, J., Physics Department, University of Lund, Ekstroem, A., Fahlander, C., Hurst, A. M., Butler, P. A., Hjorth-Jensen, M., Ames, F., Banu, A., Institute for Nuclear Physics, University of Mainz, Davinson, T., Pramanik, U. Datta, Eberth, J., Reiter, P., Warr, N., Weisshaar, D., Franchoo, S., Georgiev, G., Koester, U., Gorska, M., Kester, O., and Habs, D. Fri . "Sub-Barrier Coulomb Excitation of {sup 110}Sn and Its Implications for the {sup 100}Sn Shell Closure". United States. doi:10.1103/PHYSREVLETT.98.172501.
@article{osti_20951273,
title = {Sub-Barrier Coulomb Excitation of {sup 110}Sn and Its Implications for the {sup 100}Sn Shell Closure},
author = {Cederkaell, J. and Physics Department, University of Lund and Ekstroem, A. and Fahlander, C. and Hurst, A. M. and Butler, P. A. and Hjorth-Jensen, M. and Ames, F. and Banu, A. and Institute for Nuclear Physics, University of Mainz and Davinson, T. and Pramanik, U. Datta and Eberth, J. and Reiter, P. and Warr, N. and Weisshaar, D. and Franchoo, S. and Georgiev, G. and Koester, U. and Gorska, M. and Kester, O. and Habs, D.},
abstractNote = {The first excited 2{sup +} state of the unstable isotope {sup 110}Sn has been studied in safe Coulomb excitation at 2.82 MeV/u using the MINIBALL array at the REX-ISOLDE post accelerator at CERN. This is the first measurement of the reduced transition probability of this state using this method for a neutron deficient Sn isotope. The strength of the approach lies in the excellent peak-to-background ratio that is achieved. The extracted reduced transition probability, B(E2:0{sup +}{yields}2{sup +})=0.220{+-}0.022e{sup 2}b{sup 2}, strengthens the observation of the evolution of the B(E2) values of neutron deficient Sn isotopes that was observed recently in intermediate-energy Coulomb excitation of {sup 108}Sn. It implies that the trend of these reduced transition probabilities in the even-even Sn isotopes is not symmetric with respect to the midshell mass number A=116 as {sup 100}Sn is approached.},
doi = {10.1103/PHYSREVLETT.98.172501},
journal = {Physical Review Letters},
number = 17,
volume = 98,
place = {United States},
year = {Fri Apr 27 00:00:00 EDT 2007},
month = {Fri Apr 27 00:00:00 EDT 2007}
}
  • The reduced transition probabilities between the first excited 2{sup +} state and the 0{sup +} ground state, B(E2;0{sup +}{yields}2{sup +}), have been measured in {sup 106,108,110}Sn using sub-barrier Coulomb excitation in inverse kinematics at REX-ISOLDE. The results are, B(E2;0{sup +}{yields}2{sup +}) = 0.220(22), 0.226(17), and 0.228(32)e{sup 2}b{sup 2}, for {sup 110}Sn, {sup 108}Sn, and {sup 106}Sn, respectively. The results for {sup 106,108}Sn are preliminary. De-excitation {gamma}-rays were detected by the MINIBALL Ge-array. The B(E2) reveals detailed information about the nuclear wave function. A shell model prediction based on an effective CD-Bonn interaction in the {nu}(0g{sub 7/2},2s,1d,0h{sub 11/2}) model space usingmore » e{sub eff}{sup {nu}} = 1.0 e follows the experimental values for the neutron rich Sn isotopes, but fails to reproduce the results presented here.« less
  • Rare isotope beams of neutron-deficient {sup 106,108,110}Sn from the fragmentation of {sup 124}Xe were employed in an intermediate-energy Coulomb excitation experiment. The measured B(E2,0{sub 1}{sup +}{yields}2{sub 1}{sup +}) values for {sup 108}Sn and {sup 110}Sn and the results obtained for the {sup 106}Sn show that the transition strengths for these nuclei are larger than predicted by current state-of-the-art shell-model calculations. This discrepancy might be explained by contributions of the protons from within the Z=50 shell to the structure of low-energy excited states in this region.
  • The effect of the shell structure of colliding nuclei in calculating the entrance channel on the ensuing evolution of the product system is investigated. The entrance channel is calculated under the assumption of the nose-to-nose orientation of colliding nuclei. The following three reactions involving nuclei that are deformed in the ground state are considered: {sub 42}{sup 100}Mo + {sub 42}{sup 100}Mo {yields} {sub 84}{sup 100}Po, {sub 42}{sup 100}Mo + {sub 46}{sup 100}Pd {yields} {sub 88}{sup 210}Ra, and {sub 46}{sup 110}Pd + {sub 46}{sup 110}Pd {yields} {sub 92}{sup 220}U. The state of the system at the point of touching is determinedmore » by the results obtained by calculating the entrance reaction channel. The shape of the system is specified by three collective coordinates (deformation parameters). The evolution of collective coordinates of the system is described in terms of Langevin equations. The potential energy of the system of colliding nuclei is calculated with allowance for their shell structure. It is shown that allowance for individual features of interacting nuclei in the entrance channel of the fusion-fission reactions makes it possible to obtain, for the reactions being considered, cross sections for evaporation-residue formation that are closer to available experimental data than their liquid-drop counterparts.« less
  • Gamma-ray transitions have been identified for the first time in the extremely neutron-deficient (N=Z+2) nucleus {sup 110}Xe, and the energies of the three lowest excited states in the ground-state band have been deduced. The results establish a breaking of the normal trend of increasing first excited 2{sup +} and 4{sup +} level energies as a function of the decreasing neutron number as the N=50 major shell gap is approached for the neutron-deficient Xe isotopes. This unusual feature is suggested to be an effect of enhanced collectivity, possibly arising from isoscalar n-p interactions becoming increasingly important close to the N=Z line.
  • The 2{sub 1}{sup +} states of {sup 114,116}Sn were excited in two consecutive experiments by means of Coulomb excitation in inverse kinematics on a {sup 58}Ni target. A precise determination of the reduced transition probability B(E2; 0{sub g.s.}{sup +}{yields}2{sub 1}{sup +}) of {sup 114}Sn relative to the well-known 2{sub 1}{sup +} excitation strength in {sup 116}Sn was achieved by comparing the relative projectile to target 2{sub 1}{sup +}{yields}0{sub g.s.}{sup +} decay intensities. The obtained B(E2{up_arrow}) value of 0.232(8) e{sup 2}b{sup 2} for {sup 114}Sn confirms the tendency of large B(E2{up_arrow}) values for the light tin isotopes below the midshell {supmore » 116}Sn that has been observed recently in various radioactive ion beam experiments. The result establishes most clearly the discrepancy between the current B(E2{up_arrow}) value predictions from large-scale shell-model calculations and the experimental deviation, which commences already for the stable {sup 114}Sn isotope.« less