Diapositive 1

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Exotic Nuclei group at CENBG

• members B. Blank N. Adimi
• G. Canchel A. Bey
• J. Giovinazzo J. Souin
• I. Matea
• research topics
• strong interaction two-proton emission
• - from nuclear ground states
• - from excited states
• weak interaction mirror symmetry studies
• 0 ? 0 b decay CVC, CKM matrix
• implication in construction of SPIRAL2
• experimental sites GANIL
• JYFL

Bertram Blank, NuPPEC meeting, Bordeaux, 27/10/06
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0 ? 0 b decays CVC, CKM, exotic currents
3073.5 (12) s (1) 3074.4 (12) s
(1,2)
Measurements - Q value
- T1/2 - branching
ratios
? Vud00 0.9738(4) (1)
0.9736(3) (1,2,3) VusK 0.2200(23)
(PDG) 0.2254(21) (4) VubB
0.00367(47) (PDG) ?
0.9987(11)
( 2? shift)

• (1) Towner and Hardy, PRL 94 (2003) 092501, PRC
  71 (2005) 055501
• (2) Savard et al., PRL 95 (2005) 102501
• (3) Marciano Sirlin, PRL 96 (2006) 032002
• (4) E865, KTeV, NA48, KLOE
• (PDG) Particle Data Group, S. Eidelman et al.,
  PLB 592 (2004) 1

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0 ? 0 b decays Physics output

• 1. Vud matrix element (? test of unitarity)
• 2. test of CVC (constancy of Ft0? 0 values)
• 3. right-handed currents
• -0.0005 lt ? lt 0.0015 (90 C.L.)
• 4. scalar currents

Ad 3 Left Right Symm.-models W1 WL cos? - WR
sin? W2 WL sin? WR cos? ? m12 / m22
0.011
Ad 4 scalar currents
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62Ga Experiments at GSI and at Jyväskylä

• 40Ca on 28Si

• p on 64Zn

Measurements of half-life, b-decay branching
ratios, b-decay Q value
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Experimental results half-life
T1/2(JYFL) (116.12 0.15) ms
T1/2 (GSI) (116.19 0.04) ms
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Final half-life result
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Branching ratios

• 954 keV 0.11(4)
• Ground-state branch 99.8(1)

• Search for isospin forbidden 0 ? 0 transition
• via 2 methods
• direct search
• coincidence with 954 keV
• ?BR limit 0.039 at 95 confidence level

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Q value measurement with JYFLtrap
T. Eronen et al., PLB
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Final result for 62Ga
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Recent measurement for half-life of 38Ca at ISOLDE
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Future studies

• half-life of 26Si, 42Ti at IGISOL
• half-life of 18Ne, 34Ar, 38Ca at SPIRAL or
  ISOLDE
• branching ratios of 18Ne, 34Ar at LISE3
• branching ratios of 42Ti at KVI
• mass measurements under way at JYFLtrap and
  ISOLTRAP
• in parallel theoretical effort to better
  determine the dc
• correction term (Nadya Smirnova, Philippe
  Quentin et al.)

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exotic radioactivities
Discovered in the 1980's
- predicted in the 1960's by Goldanskii
Discovered in 2002
Why so late?

• very small production cross sections (fb pb)
• two-proton drip line is much further away from
  stability

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identification matrix
GANIL 2000 22 45Fe identified
Conditions on 8 identification parameters ?
Background free spectra
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two-proton decay of iron-45
GANIL
J. Giovinazzo et al.
? signature of direct 2p emission from the
ground state of 45Fe
M. Pfützner et al.
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two-proton radioactivity of zinc-54
54Zn Ep (1.48 0.02) MeV T1/2 3.2
ms BR2p 87 52Ni T1/2 30 20
ms (C. Dossat, PhD 40.8 ? 0.2 ms)

• no ? coincidence
• narrow peak
• observation of 2p daughter decay

1.8 - 0.8
10 - 17
?observation of a second two-proton emitter
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One decay event

• identification of four 48Ni
• three decays with ? particle and
• high energy
• one event compatible with
• 2p radioactivity
• ? no conclusive picture, but

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Comparison with theory
agreement with 3-body model, SMEC, and R-matrix
model with p-p resonance
54Zn
45Fe
Grigorenko et al. Brown and Barker Rotureau et al.
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Comparison with theory
48Ni
agreement with 3-body Model, SMEC, and R-matrix
model with p-p resonance
Grigorenko et al. Brown and Barker Rotureau et al.
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time projection chamber for 2p studies
aim measurement of individual proton energies
and proton-proton angle g distinction between
correlated 2He or uncorrelated 3-body
decay principle of detection implantation in
gas volume traces in 3D of protons g X-Y
detector g Z from time projection technol
ogy MGMS
GEMs electronics ASICs
2p emitter
electric field
protons
identification of implanted isotopes
drift of ionisation electrons
X-Y detector
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Time projection chamber
Drift volume
Hybrid card
TPC
Mount of electronics
GEM
strip-strip detector
Experiment in september 2006
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Results for Chromium-43 and Iron-45
X
Y
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Iron-45 event
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Iron-45 event
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SPIRAL2 construction

• CENBG is responsible of
• task other beams other targets
• development of target ion source ensembles
  for
• - fusion-evaporation reactions
• - transfer reactions
• - deep inelastic reactions
• ? plans to setup a mass separator
• target ion source
• - test stability of targets
• - develop new concepts for target/catcher
  cooling
• technical responsibility Laurent Serani
• development of the ISOL DESIR facility
• - (preliminary) study of building
• - layout of beam lines
• - development of high-efficiency
  charged-particle setup
• technical responsibility Franck Delalee

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The DESIR facility
Experimental area
GANIL today
DESIR
CIME
Production building
LIRAT
LINAG
F. Delalee, CENBG
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Off the valley of stability...
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two-proton decay of iron-45 from GANIL 2004
45Fe
peak energy 1.15 0.01 MeV in the expected
range for 2p emission Brown 1.15(9)
MeV Ormand 1.28(18) MeV Cole 1.22(5) MeV 2p
branching ratio 59(7) peak width 60
keV 50 narrower than bp g no b
pile-up half-life 2.5 ms compatible with
Q2p no b coincidence ltlt 1 probability for b
decay daughter decay in agreement with bp
decay of 43Cr in energy and time
43Cr
(C. Dossat, PhD 21.1? 0.4 ms)
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time projection chamber for 2p studies
1500 electronics channels
GEM Gas electron multiplier
beam
Hybrid boards
Hybrid boards
Daughter boards
Daughter boards