Sujet d'ordre g

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PROCON 2003, Legnaro-Padova, Italy
February 12-15 ,2003
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Decay properties of neutron deficient light nuclei

• Global properties

b-delayed charged particle emission

• b (C.E.) emission

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21Mg, 25Si and 26P nuclei


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stable nuclei
b emitters
b-a emitters
b-p emitters
b-2p emitters
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Production of neutron deficient nuclei at GANIL
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Detection set-up
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Identification and counting rate 26P example
Counting rates
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Analysis of b-delayed proton spectra
b coincidence in E4
b energy deposit in E3
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Identification of g transitions
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21Mg decay scheme
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25Si decay scheme
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26P decay scheme
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Mirror asymmetry principle

• Charge independence hypothesis of nuclear
  interactions symmetry of analog b transitions

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Systematics of experimental d values (A?40)

• Allowed Gamow-Teller transitions (log(ft)lt6)

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Mirror asymmetry in the b decay of A21 A25
nuclei
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Spectroscopic studies of neutron deficient nuclei

• Suitability of the fragmentation production
  method associated with the spectroscopic study of
  neutron deficient light nuclei

• good selectivity and production rates

• good agreement between experimental results and
  shell model calculations (nuclear structure and b
  decay strength)

• access to decay properties of exotic nuclei
  (21Mg, 25Si, 26P, 22Al, 27S)

• complementarity with in-beam studies

• Perspectives

• Rare decay modes study of the 2p radioactivity

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Collaboration
B. Blank, G. Canchel, S. Czajkowski, J.
Giovinazzo, CENBG Bordeaux - France
L. Achouri, LPC Caen - France
J. Äystö, P. Dendoveen, J. Honkanen, J. Jokinen,
University of Jyväskylä - Finland
R. Béraud, A. Ensallem, IPN Lyon - France
A. Laird, University of Edinburgh United Kingdom
M. Lewitowicz, F. de Oliveira-Santos, M. Stanoiu,
GANIL Caen France
C. Longour, IReS Strasbourg France
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21Mg, 25Si and 26P nuclei
26P
25Si
DM (MeV)
21Mg
Z
N
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Half-life of 26P
Time correlation procedure
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Analysing procedure

• detector calibration (g sources, known b-g and
  b-p transitions)

• Ng and Np number of counts in spectra

• Nimpl number of implanted ions

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Identification of b-(2)p transitions
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Mirror asymmetry sources
Origin and consequences of the isospin
non-conservation in nuclear interactions
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Coulomb effects
Mirror asymmetry in allowed Gamow-Teller
transitions
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Binding energy effects
The last proton of the b emitting nucleus is
less bound than the last neutron of the b-
emitting nucleus Sp lt Sn-
? radial overlap mismatch of wave functions in
the b decay W lt W- i.e. d gt 0
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Systematic approach of binding energy effects
How to see the binding energy effects on the
radial overlap of the nucleon wave functions?

• decreasing of d as Ji is increasing i.e. as the
  centrifugal barrier is increasing

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