Diapositive 1

1

• Spectroscopy studies by ? decay
• Proton-rich nuclei NZ
• Deformation in the mass region A75
• Fundamental aspects of weak interaction, test of
  CVC
• Neutron-rich nuclei Z20
• effective interaction in the mass region A50

Cécile Jollet, IReS Strasbourg, TAS Workshop,
Caen March 31, 2004
2
? decay general features
Spectroscopy ? detection of ?, and delayed
particules (neutrons or protons, and ?-rays) ?
Informations provided
Mass excess Half-life T1/2 ? feedings I? ft
f(Z,Q?-Ex) T1/2 / I? ft Cste / Mif2
? Matrix elements, nuclear configurations
3
1-Proton-rich nuclei NZ, A75
Theoretical and experimental works in this
region ? shape isomerism or shape coexistence ?
strongly deformed ground states
Hamamoto, Sarriguren ? Shape of the GT strength
distribution depends on the shape of parent
nucleus ground state

• In this region, large part of the GTGR is
  accessible by ? decay
• Estimate the deformation by measuring the
  complete B(GT)
• distribution

Good efficiency for ? detection on the whole QEC
window ? construction of a new Total Absorption
gamma Spectrometer (TAgS)
?Installation of TAgS at ISOLDE in 2001 ?Study
by ? decay 72,73,74,75Kr and 76,77,78Sr Detectio
n TAgS Ge detectors (X, ?) and plastic
scintillators (?)
I. Hamamoto et X. Z. Zhang, Z. Phys. A353 (1995)
145.
4
Total Absorption gamma Spectrometer (TAgS)
(Madrid, Strasbourg, Surrey, Valence)
NaI monocrystal (diameter38cm, length38cm) 8
PMTs 5
TAgS properties Energy resolution 7.1 at 662
keV 5.4 at 1332 keV Efficiency at
662 keV 95(8) total
83(7) photopeak Solid Angle 97 of 4?
New beam line
5
1-Proton-rich nuclei NZ, A75
E. Poirier et al., PRC69,034307 (2004)
E. Nácher et al., submitted to PRL
Shape mixing
Prolate shape

• Results in good agreement with theory and with
  previous experiments
• ? decay studies ? value and sign of the
  deformation
• ? validation of TAgS spectroscopy

6
1- Proton-rich nuclei NZ Fundamental aspect of
weak interaction
V-A theory, hyp the Vector Current is conserved
(CVC) ?vector part of weak interaction not
influenced by strong interaction To test CVC
study of superallowed Fermi ? transitions 0?0
? Ft ft (1?r) (1-?c) cste (?r, ?c are
correction terms)
We need to determine the complete decay scheme,
?r and ?c TAgS ? measure branching ratios and
T1/2 with the required precision Current
measurement with TAgS study of 62Ga
7
2-Neutron-rich nuclei A50, Z20
Neutron-rich nuclei ? large Q?-Sn energy
window We need efficient neutron and gamma
detection ? direct knowledge of I?, Pxn and Ex
Non nat
?
?
8
2-Neutron-rich nuclei A50, Z20
TONNERRE Detector (LPC Caen, IFIN Bucarest) En
0.2-7 MeV ? 11 at 1 MeV
Experimental setup at ISOLDE
Low energy neutron detectors (x8) (IReS) En
0.05-3.0 MeV ? 0.5 at 1 MeV
Ge Clusters (x2) (MINIBALL collaboration) ? 5
at 1.3 MeV and 4?? (start n-TOF) ? 70
9
2-Neutron-rich nuclei A50, Z20
Preliminary results
In red new ? transitions In green new neutron
emitter states and transitions 52K decay ?
detection of both low and high energy
neutrons 53K decay ? only part of the
statistics Comparison with theory for 51,52,53Ca
in progress (E. Caurier, F. Nowacki, IReS)
10
Conclusions Perspectives
We have 2 experimental setup which are performing
to explore the nuclear structure ?TAgS
?LEND-TONNERRE coupling
Efficient neutron detection Effective
interaction, shell order Neutron-rich nuclei near
the closed shell ?35,36Al, Cu, Zn
High ? efficiency study of NZ nuclei ?
deformation A80 ? CVC test 74Rb ? mirror
decays 71Kr, 75Sr
Such investigations can be performed using any
low energy beams at ISOLDE, Ganil, Alto
11
Production yield information
ISOLDE http//isolde.web.cern.ch/isolde/ Ulli
Koster SPIRAL http//www.ganil.fr/operation/avail
able_beams/ radioactive_beams.htm ALTO Fadi
Ibrahim (preliminary estimation)
12
Collaboration

• Algora J.C. Angélique G. Ban P. Baumann
  F. Benrachi C. Borcea
• M.J.G. Borge A. Buta D. Cano-Ott J.C
  Caspar E. Caurier S. Courtin
• P. Dessagne J. Devin D. Etasse L.M.
  Fraile F. Perrot W. Gelletly S. Grévy
• G. Heitz C. Jollet A. Jungclaus F.R.
  Lecolley E. Liénard G. Le Scornet
• F. Maréchal C.Miéhé E. Nacher F. Negoita
  F. Nowacki N. Orr E. Poirier
• M. Ramdhane B. Rubio M.D. Salsac P.
  Sarriguren J.L. Tain O. Tengblad
• C. Weber
• The IReS workshop and the ISOLDE Collaboration

13
(No Transcript)
14
Neutrons transmission
15
Efficiency of neutrons detector Tonnerre, LEND