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GOSIA as a tool for COULEX on exotic beams

GOSIA as a tool for COULEX on exotic beams. Katarzyna Wrzosek Heavy Ion Laboratory Warsaw University. LOW - ENERGY COULOMB EXCITATION:. Well-established method to study collective excitations in nuclei.

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GOSIA as a tool for COULEX on exotic beams

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  1. GOSIA as a tool for COULEX on exotic beams Katarzyna Wrzosek Heavy Ion Laboratory Warsaw University EWON Workshop, Prague, 10-12 May 2007

  2. LOW - ENERGY COULOMB EXCITATION: • Well-established method to study collective excitations in nuclei. • Purely electromagnetic  the only nuclear properties involved are the matrix elements of the electromagnetic multipole moments. EWON Workshop, Prague, 10-12 May 2007

  3. 208Pb • Gamma ray spectrometer EXOGAM – up to 11 segmented Ge clovers (90 and 135) • Particle detector CD-detector - annular, highly segmented double silicon strip detector (DSSD)covered angles: 23,8-54,5 in the LAB ≡ 24-145 in the C.M. frame EWON Workshop, Prague, 10-12 May 2007

  4. SIGMA available spectroscopic data (, BR, ) MINIMALIZATION PROCEDURE Errors estimation set of matrix elements shape parameters for individual states Quadrupole rotational invariant sum rules GOSIA COULEX Analysis Scheme Measured yields Experimental setup geometry:particle and  detectors Level scheme EWON Workshop, Prague, 10-12 May 2007

  5. GOSIA • GOSIA is a Rochester – Warsaw semiclassical coupled-channel Coulomb excitation least-squares search code. • Developed in early eighties by T. Czosnyka, D. Cline, C.Y.Wuand continuously upgraded to fulfill requirements of new experiments. • Used extensively for Coulomb excitation studies of a wide range of nuclei. • Typical use of GOSIA: • Fitting of the matrix elements to the experimental data. • Simulation of the experiments:to predict which  - ray will be observedto check to what extent the observation will depend on individual matrix elements. EWON Workshop, Prague, 10-12 May 2007

  6. AN EXAMPLE:COULOMB EXCITATION OF 74,76Kr @ GANIL • Coulomb excitation is the only method that can directly distinguish between different shapes of the nucleus  ideally suited to verify the shape coexistence scenario in the Kr isotopes. • Shape parameters of the two lowest 0+ states in 74Kr and 76Kr nuclei were inferred from coulomb excitation data. • The Coulomb excitation analysis were performed using the last squares fitting code GOSIA. EWON Workshop, Prague, 10-12 May 2007

  7. 508 keV 770 keV EXPERIMENTS (SPIRAL @ GANIL) 74Kr 76Kr 76Kr + 208Pb(106 pps, 4.4·A MeV) 74Kr + 208Pb (5·105 pps, 4.7·A MeV) E. Clement et al., submitted to Phys Rev C EWON Workshop, Prague, 10-12 May 2007

  8. 39.5° - 49.0° 61.4° - 71.8° 76 Kr 76Kr 71.0° - 87.7° 107.0° - 121.5° EWON Workshop, Prague, 10-12 May 2007

  9. RESULTS EWON Workshop, Prague, 10-12 May 2007

  10. QUADRUPOLE ROTATIONAL INVARIANTSUM RULES model independent description of the nuclear shape is based on a fact, that scalar products of E2 operators are rotational invariants. Operator products may be expressed using the intermediate state expansion formula: EWON Workshop, Prague, 10-12 May 2007

  11. QUADRUPOLE ROTATIONAL INVARIANTSUM RULES model independent description of the nuclear shape To get information on triaxiality the higher order invariant is needed: EWON Workshop, Prague, 10-12 May 2007

  12. RESULTS • The deformation of the 0+1 is very similar in 74Kr and 76Kr. Triaxiality parameter: • the ground state of 76Kr is prolate, while the 0+2 state has an triaxial shape. • Both, the ground state and the 0+2 state of 74Kr are triaxial,but with different  parameter. EWON Workshop, Prague, 10-12 May 2007

  13. CEA Saclay, France E.Clément A.Görgen W.Korten E.Bouchez A.Chatillon A.Hürstel Y.Le Coz A.Obertelli Ch.Theisen J.N.Wilson CEA/DIF, France J.-P. Delaroche M.Girod H.Goutte S.Péru GANIL, Caen, France J.M.Casandjian G. de France HIL Warsaw, Poland T.Czosnyka J.Iwanicki (OLL, Liverpool) P.J.Napiorkowski M.Zielińska (CEA Saclay) Oliver Lodge Lab., Liverpool, UK C.Andreoiu P.A.Butler R.-D.Herzberg D.G.Jenkins G.D.Jones Univ. Of Surrey, Guildford, UK W.N.Catford C.Timis GSI, Darmstadt, Germany F.Becker J.Gerl NBI, Copenhagen, Denmark G.Sleten Collaboration of 74,76Kr Project EWON Workshop, Prague, 10-12 May 2007

  14. ISOLDE (MINIBALL), CERN: J. Cederkall – 108Sn, 110Sn J. Iwanicki - 88Kr, 92Kr A. Hurst - 70Se I. Stefanescu – 68Cu, 70Cu J. Van de Walle – 74Zn GANIL (EXOGAM), FRANCE: E. Bouchez – 76Kr E. Clement – 74Kr M. Zielińska – 44Ar JYVASKYLA, FINLAND F. Becker – 78Kr JAEA, TOKAI, JAPAN: M. Koizumi - 66Zn, 68Zn T. Hayakawa – 78Se A. Osa - 84Kr Y. Toh – 70Ge M. Zielińska – 96Mo ANL (Gammasphere), USA A.Hayes – 178Hf Next experiments ISOLDE (MINIBALL), CERN: E. Clement – 96Sr (Jul 2007) P.Butler, P. Van Duppen - 182,184Hg (Aug 2007) JRA6INTAG List of the experiments where GOSIA was recently used EWON Workshop, Prague, 10-12 May 2007

  15. Warsaw Coulomb Excitation Group@ Heavy Ion Laboratory, Warsaw Univ. • Tomasz Czosnyka • Julian Srebrny • Jędrzej Iwanicki • Paweł Napiorkowski • Magdalena Zielińska (CEA Saclay) • Katarzyna Wrzosek • Katarzyna Hadyńska (UAM, Poznań) • Daniel Piętak (PW, Warsaw) EWON Workshop, Prague, 10-12 May 2007

  16. Thank you EWON Workshop, Prague, 10-12 May 2007

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