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Bertram Blank
CEN Bordeaux-Gradignan
• two-proton radioactivity
• experiments with silicon detectors
• TPC results
• Future studies
NUSTAR meeting, GSI, March 2-4, 2011
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fission break-up of nucleus
 two light nuclei
alpha emission of 4He
2 protons + 2 neutrons
beta +
proton  neutron
+ light particles
beta -
neutron  proton
+ light particles
Gamma nuclear rearrangement
+ gamma ray
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V. Goldanskii….1960
One-proton radioactivity
nucleus  proton
+ nucleus – 1p
Two-proton radioactivity
nucleus  two protons
+ nucleus – 2p
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• • • observation of two-proton radioactivity
data taken with silicon (strip) detectors
45Fe
1
0
0
J. Giovinazzo et al., 2002
• total decay energy
• half-life
• branching ratio
• daughter information
1
2
3
4
Energy (MeV)
5
6
M. Pfützner et al., 2002
  discovery of two-proton radioactivity
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• • • observation of two-proton radioactivity
data taken with silicon (strip) detectors
54Zn
B. Blank et al., 2005
• total decay energy
• half-life
• branching ratio
• daughter information
48Ni
C. Dossat et al., 2005
 discovery of two-proton radioactivity
for 54Zn and evidence for 48Ni
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• • • Comparison with theory
45Fe
Grigorenko et al.
Brown and Barker
Rotureau et al.
agreement with 3-body model,
SMEC, and R-matrix model
54Zn
48Ni
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• • • new development…
However:
- only total decay energy,
half-life, no beta,
daughter decay
- no individual energies
- no proton-proton angle
TPC
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• • • Time projection chambers
TPC sur LISE3 au GANIL
technology: MGMS
+ GEMs
electronics: ASICs
B. Blank et al.
OTPC at NSCL/MSU
technology:
CCD camera
+ PM
M. Pfützner, K. Miernik et al.
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•••
45Fe
two-proton event in CENBG TPC at GANIL
implantation
decay
Energy on X strips
J. Giovinazzo et al., PRL 99 (2007) 102501
Energy on Y strips
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•••
45Fe
two-proton events in OTPC of Warsaw at NCSL
M. Pfützner et al.
Daughter decay
2p
45Fe
2p
p
Daughter decay
45Fe
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•••
45Fe
two-proton correlations with OTPC at NSCL
K. Miernik et al.,
PRL 99 (2007) 192501
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• • • 3D reconstruction of
45Fe
events from GANIL
12
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• • • Energy sharing and angular distribution
Grigorenko et al.
exp.
energy fraction (%)
• perfect energy
sharing between
the two protons
• A two-hump
structure is observed,
as predicted by the
model of Grigorenko
L. Audirac et al.
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•••
54Zn
two-proton event in TPC of CENBG
P. Ascher et al.
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• • • Energy sharing between the two protons from
• perfect energy
sharing between
the two protons
• perfect agreement
with 3-body model
(L.V. Grigorenko et al.
54Zn
2D projection
P. Ascher et al.
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• masses of nuclei beyond drip line:
measurement of decay Q value
• pairing in nuclei:
emission pattern
• sequence of single-particle levels:
angular distribution of protons
• composition of wave function:
angular distribution of protons
• tunneling process:
change of deformation
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CEN Bordeaux-Gradignan (France)
GANIL Caen (France)
IAP Bucharest (Romania)
Warsaw University (Poland)
NSCL-MSU (USA)
University of Santiago di Compostella (Spain)
IPN Orsay (France)
LPC Caen (France)
KU Leuven (Belgium)
Warsaw University (Poland), GSI Darmstadt (Allemagne),
CEN Bordeaux-Gradignan (France), GANIL Caen (France),
ORNL (Tennessee / USA), Edinburg University (UK)
Warsaw University (Poland), MSU (USA),
ORNL (Tennessee / USA), University of Tennessee (USA)
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• • • Future…
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• • • Two-proton radioactivity experiments at the BigRIPS
• Nuclei of interest: 59Ge, 63Se, 67Kr
• Production: 78Kr fragmentation at 360 MeV/u, 100pnA
• Separation: BigRIPS
• Detection: standard BigRIPS detection + silicon telescope with DSSSD (1mm)
+ Germanium detectors
• Settings: 59Ge, rate = 9 ppd (CENBG, Stolz et al. + EPAX2)
• Settings: 63Se, rate = 6 ppd (Stolz et al. + EPAX2)
• Settings: 67Kr, rate = 4 ppd (Stolz et al. + EPAX2)
• New isotopes: 59Ge, 63Se, 68,67Kr
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• • • FAIR + SFRS
5*1011 pps of primary beam, 600 MeV/A, 4 seconds per pulse
4 g/cm2 of Be
58Ni:
• 48Ni: 7*10-4 pps  70 per day
78Kr:
• 59Ge: 1*10-2 pps  1000 per day (EPAX / 10)
• 63Se: 5*10-3 pps  500 per day (EPAX / 10)
• 67Kr: 2*10-3 pps  200 per day (EPAX / 10)
92Mo:
• 70Sr: 5*10-5 pps  5 per day
• 71Sr: 1*10-3 pps  100 per day
• 74Zr: 2*10-5 pps  2 per day
• 75Zr: 6*10-4 pps  60 per day
• 78Mo: 6*10-6 pps  0.6 per day
• 79Mo: 1*10-4 pps  10 per day
124Xe:
• 97Sn: 6*10-6 pps  0.6 per day
• 98Sn: 1*10-4 pps  10 per day
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• • • New TPC based on ASICs and a pad structure
 General electronics for TPCs: GET  16384 channels
J. Pibernat, CENBG
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• • • Very short-lived two-proton emitters:
19Mg
Identification of
fragments
17Ne
FRS
protons
Reaction 20Mg→19Mg→17Ne+p+p
Fragmentation
Mg→et Ne+p+p+n
I. Mukha
al.
20
17
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• • • Vertex distributions of
19Mg
2p-decays
Vertex distribution of
17Ne+p+p events from
short-lived resonances
Half-life value of 19Mgg.s.
T1/2=4.0(15) ps
No measurement of
proton energies
 spectrometer approach??
R3B???
21Si, 25S, 30Ar, 34Ca, 38Ti…
I. Mukha et al.
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ab
st
ra
ex ct
t e su
nd bm
ed is
to sio
M n
ar de
ch ad
15 li
ne
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