ELFT HÍRADÓ

[Zoltan Mate <mate AT atomki.mta.hu>]

Az MTA Atommagkutató Intézetének előadótermében
(Debrecen, Bem tér 18/c. 12. ép. III. em.)
2012. szeptember 13-án, csütörtökön 11:00-kor


          Siyabonga Ntokozo Thandoluhle MAJOLA
                    (iThemba LABS)
         
      IN A SEARCH FOR TETRAHEDRAL SYMMETRIES IN 156DY

    
címmel előadást tart.
Az előadás előtt 10:30-tól tea, vendégeket szívesen látunk.

                                           Máté Zoltán


Kivonat:
Negative-parity side bands in nuclei localized in the vicinity of N = 90
are known to have strong electric dipole transitions from each level to
the ground-state band, with weak or unseen E2 transitions in the medium
(i.e. approximately 15 h-bar) to low-spin region. These structures have
always been regarded as octupole vibrational bands. On the other hand,
Dudek et al. recently proposed that these structures might be associated
with tetrahedral symmetries, as they have very weak inband E2s [Dud06,
Dud07].
In this study, data from the 148Nd (12C, 4n) 156Dy reaction, taken with
GAMMASPHERE is analysed. We also report an observation of a band with
characteristics of that discussed on the paragraph above i.e. a negative
parity band with missing (or weak) inband transitions E2 at low spin.
Furthermore, the crossing between this band (tetrahedral candidate) and
the two quasi-particle excitation (AE) around spin 13 h-bar  has allowed
the band mixing calculation to be carried out, so that relative quadrupole
moments could be deduced for these bands. However, a non-zero quadrupole
moment has been deduced for our tetrahedral candidate, and this is
incompatible with the tetrahedral shape. We therefore seek for an
alternative description of this band.

[Dud06] J. Dudek et al,. Phys. Rev. Lett. 97, 072501 (2006).
[Dud07] J. Dudek et al,. Phys. Pol. B 38, 1389 (2007).