Transcript Exotic Nuclei group at CENBG

Exotic Nuclei group at CENBG
members:
B. Blank
G. Canchel
J. Giovinazzo
I. Matea
• research topics:
strong interaction:
weak interaction:
N. Adimi
A. Bey
J. Souin
two-proton emission
- from nuclear ground states
- from excited states
mirror symmetry studies
0+  0+ b decay: CVC, CKM matrix
• implication in construction of SPIRAL2
• experimental sites:
GANIL
JYFL
ISOLDE
GSI
(MSU, KVI)
Bertram Blank, NuPPEC meeting, Bordeaux, 27/10/06
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

Vud0+0+
VusK
= 0.9738(4)
(1)
0.9736(3) (1,2,3)
= 0.2200(23)
(PDG)
0.2254(21) (4)
VubB
= 0.00367(47)

(PDG)
2
2
2
2
V
=
V
+
V
+
V
i ui ud us ub = 0.9967(13)
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
0+  0+ b decays: Physics output
1. Vud matrix element ( test of unitarity)
2. test of CVC (constancy of Ft0+ 0+ values)
W1 = WL cos - WR sin
W2 = WL sin + WR cos
 = m12 / m22
3. right-handed currents:
-0.0005 <  < 0.0015
Ad 3: Left Right Symm.-models
(90% C.L.)
4. scalar currents:
 CS  CS'
0.005  Re 
 C
V

(90% CL)

.004
 < 00.011

Ad 4: scalar currents
62Ga:
Experiments at GSI and at Jyväskylä
• p on 64Zn
• 40Ca on 28Si
Measurements of half-life, b-decay branching ratios, b-decay Q value
Experimental results: half-life
T1/2(JYFL) = (116.12 ± 0.15) ms
T1/2 (GSI) = (116.19 ± 0.04) ms
Final half-life result
JYFL
GSI
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
Q value measurement with JYFLtrap
T. Eronen et al., PLB
Final result for 62Ga
Recent measurement for half-life of 38Ca at ISOLDE
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 c
correction term (Nadya Smirnova, Philippe Quentin et al.)
Why so late?
• very small production cross sections (fb – pb)
• two-proton drip line is much further away from stability
Primary beam:
58Ni @ 75 MeV/A
intensity: 3 - 4 mAe
spectrometer LISE3 :
degrader Be (50 mm)
Wien filter
SISSI target:
natNi 200 mg/cm2
silicon telescope
identification of
implanted fragments
DSSSD (X-Y): 2 x 16 x 3 mm
- veto for light particles
- residual energy, x-y position
- energy loss
- time of flight:
micro-channel plate detectors
RF cyclotron
detection
setup
GANIL 2000
22 45Fe identified
Conditions on 8 identification
parameters
 Background free spectra
GANIL
GSI
decay of 45Fe
four 2p decay
events
J. Giovinazzo et al.
1
 signature of direct 2p
emission from the ground
state of 45Fe
00
6
1
2
3
Energy (MeV)
M. Pfützner et al.
4
5
54Zn:
Ep
= (1.48 ±0.02) MeV
T1/2 = 3.2 +1.8
- 0.8 ms
BR2p = 87 +10
- 17 %
52Ni:
T1/2 = 30 ± 20 ms
(C. Dossat, PhD: 40.8  0.2 ms)
• no b coincidence
• narrow peak
• observation of 2p daughter decay
observation of a second
two-proton emitter
One decay event:
• identification of four 48Ni
• three decays with b particle and
high energy
• one event compatible with
2p radioactivity
 no conclusive picture, but…
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.
48Ni
agreement with 3-body
Model, SMEC, and
R-matrix model with p-p
resonance
Grigorenko et al.
Brown and Barker
Rotureau et al.
aim
measurement of individual proton energies and proton-proton angle
g distinction between correlated 2He or uncorrelated 3-body decay
principle of
detection
2p emitter
implantation in
gas volume
traces in 3D of
protons
g X-Y detector
g Z from time
projection
technology: MGMS
+ GEMs
electronics: ASICs
protons
drift of
ionisation
electrons
identification of
implanted
isotopes
Time projection chamber
TPC
Drift volume
Hybrid card
Mount of electronics
GEM
strip-strip detector
d = 70mm
Experiment in september 2006…
d = 200mm
43Cr:
X
45Fe:
X
Y
2p
Y
X
Y
b2p
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
The DESIR facility
Experimental area
GANIL today
DESIR
CIME
LIRAT
Production building
LINAG
F. Delalee, CENBG
Two-proton emitter
with even Z
45Fe
peak energy:
in the expected
Brown:
Ormand:
Cole:
1.15 ± 0.01 MeV
range for 2p emission:
1.15(9) MeV
1.28(18) MeV
1.22(5) MeV
2p branching ratio:
59(7) %
peak width:
60 keV
half-life:
2.5
50 % narrower than bp
g no b pile-up
ms
compatible with Q2p
no b coincidence
<< 1% probability for b decay
43Cr
daughter decay:
in agreement with bp decay
of 43Cr in energy and time
(C. Dossat, PhD: 21.1 0.4 ms)
1500 electronics channels
beam
GEM: Gas electron multiplier
Hybrid
boards
Hybrid
boards
Daughter
boards
Daughter
boards