OSIRIS II collaboration

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					                   OSIRIS II collaboration

Nuclear Physics Division, Warsaw University
 Ch. Droste, E. Grodner, M. Kowalczyk, J.Mierzejewski,
T. Morek, J. Srebrny, M. Sałata, P. Tarnowski, I. Zalewska

A. F. Ioffe Physical-Technical Institute St.-Petersburg
A. A. Pasternak

Heavy Ion Laboratory, Warsaw University
J. Kownacki, A. Kordyasz, P. Napiorkowski, M. Wolińska-Cichocka

The A. Sołtan Institute for Nuclear Studies, Świerk
M. Kisieliński, R. Kaczarowski, W. Płóciennik, E. Ruchowska, A. Wasilewski

Łódź University
J. Perkowski

Department of Physics and Astronomy, SUNY at Stony Brooks
D. B. Fossan, T. Koike, K. Starosta
D.B. Fossan,

Thanks are due to :
IKF Julich (R. Lieder) for OSIRIS frame, BGO ball , electronics
                         and 6 ACS Ge spectrometers ( + 3 Ge)
Nuclear Physics Institute - Kraków (W. Męczyński)
                           for 2 ACS Ge spectrometers
NORDBAL collaboration and Jyvaskyla for 2 ACS and 4 Ge detectors

Recent theoretical and experimental works have attracted
attention to the problem of chirality in atomic nuclei with odd
numbers of protons and neutrons. In these nuclei the total
nuclear spin is built from the valence proton and valence
neutron momenta and angular momentum of the even-even
core. These three vectors can be mutually perpendicular and
coupled in two manners forming systems (left- and right-
handed) with opposite chirality in the intrinsic frame of the
nucleus. In the laboratory frame it manifests itself as the
presence of two rotational bands, nearby degenerated, with the
same parities. The study of the chiral twin bands is in its very
early stage. For example, there is a lack of data on the
lifetimes of states belonging to the chiral bands. Such data
carry important information on nuclear wave functions.
      We plan to study lifetimes in the 130La and 132La nuclei in
which candidates for chiral bands have been found.
      The 132La and 128Cs nuclei were produced in
  Sn(14N,4n)132La reaction. E(14N) = 75 MeV
  Sn(10B,4n)128Cs reaction. E(10B) = 55 MeV

The Warsaw Cyclotron and the OSIRIS II multidetector
spectrometer were used
           HISTORY of CHIRALITY in Nuclear Physics

1. New phenomena of chiral symmetry breaking
   first theoretical prediction Frauendorf, Meng 1997
   reinterpretation of Pr data     Petrache et al. (1996)

2. Experimental identification of chiral doublets based
   on energy levels only
   - about 10 cases for A  130                 2001-2003

4. CPHC model formulated and firstly applied
   to 132La       K. Starosta et al.                 2002

5. First lifetime measurements in supposed chiral bands
      La – Warsaw Cyclotron and OSIRIS II,DSAM 2003
6. New third band in         La , OSIRIS II          2003
7.     Cs lifetime maeasurements
     – Warsaw Cyclotron and OSIRIS II,DSAM           2004

8. Chirality confirmed and survived ! ?              2004
Last preliminary results on 128Cs -- June 2004 run

First results shows that in 128Cs differences in B(E2) values between the “yrast”
band (band 1) and supposed partner chiral band (band 2 ) are much smaller than
in the case of 132La( see attached figures)

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