Transcript GOSIA as a tool for COULEX on exotic beams Katarzyna Wrzosek

GOSIA
as a tool for COULEX
on exotic beams
Katarzyna Wrzosek
Heavy Ion Laboratory
Warsaw University
EWON Workshop, Prague, 10-12 May 2007
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
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
COULEX Analysis Scheme
Measured
 yields
Level scheme
available
spectroscopic
data
(, BR, )
Experimental
setup geometry:
particle and 
detectors
MINIMALIZATION
PROCEDURE
Errors estimation
GOSIA
set of matrix
elements
Quadrupole
rotational invariant
sum rules
shape parameters
for individual
states
EWON Workshop, Prague, 10-12 May 2007
SIGMA
GOSIA




GOSIA is a Rochester – Warsaw semiclassical coupledchannel Coulomb excitation least-squares search code.
Developed in early eighties by
T. Czosnyka, D. Cline, C.Y.Wu
and continuously upgraded to fulfill requirements of new
experiments.
Used extensively for Coulomb excitation studies of a wide
range of nuclei.
Typical use of GOSIA:
1.
Fitting of the matrix elements to the experimental data.
2.
Simulation of the experiments:
to predict which  - ray will be observed
to check to what extent the observation will depend on
individual matrix elements.
EWON Workshop, Prague, 10-12 May 2007
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
EXPERIMENTS (SPIRAL @ GANIL)
508 keV
770 keV
74Kr
74Kr
76Kr
76Kr
+ 208Pb
(5·105 pps, 4.7·A MeV)
+ 208Pb
(106 pps, 4.4·A MeV)
E. Clement et al., submitted to Phys Rev C
EWON Workshop, Prague, 10-12 May 2007
76 Kr
76Kr
39.5° - 49.0°
61.4° - 71.8°
71.0° - 87.7°
EWON Workshop, Prague, 10-12 May 2007
107.0° - 121.5°
RESULTS
EWON Workshop, Prague, 10-12 May 2007
QUADRUPOLE ROTATIONAL
INVARIANT SUM 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
QUADRUPOLE ROTATIONAL INVARIANT
SUM 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
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
Collaboration of 74,76Kr Project
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
EWON Workshop, Prague, 10-12 May 2007
List of the experiments
where GOSIA was recently used
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 (Aug 2007)
EWON Workshop, Prague, 10-12 May 2007
182,184Hg
JRA6
INTAG
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
Thank you
EWON Workshop, Prague, 10-12 May 2007