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Low-energy fission investigated in reactions of 750 AMeV 238U-ions on 208Pb. II: Isotopic distributions |
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| Authors: | C Donzaud S Czajkowski P Armbruster M Bernas C Böckstiegel P Dessagne H Geissel E Hanelt A Heinz C Kozhuharov C Miehé G Münzenberg M Pfützner W Schwab C Stéphan K Sümmerer L Tassan-Got B Voss |
| Institution: | (1) IPN Orsay, IN2P3, CNRS, F-91406 Orsay Cedex, France, FR;(2) GSI Darmstadt, HGF, Postfach 110552, D-64220 Darmstadt, Germany, DE;(3) CENBG Bordeaux-Gradignan, IN2P3, CNRS, BP 120, F-33170 Gradignan Cedex, France, FR;(4) IReS Strasbourg, IN2P3, CNRS, F-67037 Strasbourg Cedex, France, FR;(5) TH Darmstadt, Institut für Kernphysik, Schlossgartenstrasse 9, D-64289 Darmstadt, Germany, DE;(6) IFD, University Warsaw, Pl-00681 Warsaw, Hoza 69, Poland, PL |
| Abstract: | Projectile fission of 750 AMeV 238U-ions interacting with a Pb target was studied by means of the spectrometer FRS, GSI-Darmstadt. One of the two fission fragments was detected with a transmission of few percent and identified in mass and charge. Low-energy fission (E* < 25 MeV) events were selected by their magnetic rigidity. Whereas the production of asymmetric fission events is dominated by the GDR excitation, very asymmetric fission and symmetric fission take place after a GQR or DGDR excitation or after a nuclear interaction. Cross sections of more than 250 isotopes were measured. Isotopic distributions of low-energy fission were reconstructed for elements from Se to Te. The fission modes SI, SII and SL were clearly shown in these distributions and in the mass and TKE distributions. Charge polarization and mass dispersion were deduced for each fission mode. Finally, the characteristics of the low-energy fission process explain the production rates of neutron-rich species. Received: 14 July 1997 / Revised version: 6 October 1997 |
| Keywords: | PACS:25 85 -W Fission reactions |
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