35 ca decay beta-delayed 1- and 2-proton spokespersons: j. giovinazzo (cenbg), o. tengblab (csic)...
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35Ca decaybeta-delayed 1- and 2-proton
spokespersons: J. Giovinazzo (CENBG), O. Tengblab (CSIC)
institutions:
Centre d’Etudes Nucléaires (Bordeaux) – CNRS / univ. Bordeaux – France
Istituto de Estructura de la Materia (Madrid) – CSIC – Spain
Dep. of Physics and Astronomy (Aarhus) – univ. Aarhus – Denmark
PH department CERN (Geneva) – Switzerland
beta delayed proton(s) emission program31Ar studied at ISOLDE
previous decay studies
Berkeley, J. Aystö et al. (1985)
GANIL, W. Trinder et al. (1999)
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Previous experiments
1985 Berkeley, J. Aystö et al., PRL 55 (1985) 138440Ca(3He,4n) reaction, helium-jet techniquesmall angle proton-proton coincidenceswith E-E silicon telescope
- only -2p measurement (sequential)
- first decay scheme
1999 GANIL, W. Trinder et al., PLB 459 (1999) 6740Ca fragmentation, LISE implantation / decay experimentgamma: 3 Ge (70%) and 2 NaI detectors
- 19 -p() transitions B(GT) (weaker quenching than sd shell)
- no -
- no -2p to excited state in 33Cl
logft(IAS) = 3.09T1/2 = 50 ± 30 msm = 4463 ± 60 keV (IMME)
logft(IAS) = 4.1 missed strength ?T1/2 = 25.7 ± 0.2 msm = 4530 ± 66 keV (IMME)
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31Ar and 35Ca at ISOLDE
current proposal is continuation of -p and -2p decay studies at ISOLDE
31Ar experiment : Phys. Rev. C 87, 055808 (2013)G. T. Koldste, H.O.U. Fynbo, et al.
mainly study of 30S resonances (-p)
nucleosynthesis
-p() and -2p
new experimental methodfor p / estimate
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QEC
0
T = 5/2
IAS
35Ca
35P
34Ar+p
33Cl + 2p
1/2+
1/2+
3/2+
0+
2+
1/2+
3/2+
purpose of the experiment (I)
rich decay schemebeta-gammabeta-proton(-gamma)beta-2proton(-gamma)
decay spectroscopya unique access to drip-line nuclei
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QEC
0
T = 5/2
IAS
35Ca
35P
34Ar + p
33Cl + 2p
1/2+
1/2+
3/2+
0+
2+
1/2+
3/2+
purpose of the experiment (II)
/CE
beta-gamma
coincidences not observed in previousexperiments
unexpected low B(F)strength
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QEC
0
T = 5/2
IAS
35Ca
35P
34Ar + p
33Cl + 2p
1/2+
1/2+
3/2+
0+
2+
1/2+
3/2+
purpose of the experiment (III)
/CE
beta-proton unresolved proton groups (GANIL) improved resol.B(GT) distribution (including - ?)
proton emissionfrom IAS is isospinforbidden T(35PIAS) = 1/2
T(34Args) = ½proton vs gamma emission isospin mixing
p
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QEC
0
T = 5/2
IAS
35Ca
35P
34Ar + p
33Cl + 2p
1/2+
1/2+
3/2+
0+
2+
1/2+
3/2+
purpose of the experiment (IV)
/CE
beta-proton-gamma vs beta-2-protongamma / proton widths in 34Arrp-process: 33Cl(p,)34Ar reaction
p
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QEC
0
T = 5/2
IAS
35Ca
35P
34Ar + p
33Cl + 2p
1/2+
1/2+
3/2+
0+
2+
1/2+
3/2+
purpose of the experiment (V)
/CE
p
beta-2-protonfeeding of excited state in 33Cl ? (seen at Berkeley, not at GANIL)search for a direct 2-proton branch (never evidenced in 2p)
p
2p?
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QEC
0
T = 5/2
IAS
35Ca
35P
34Ar+p
33Cl + 2p
1/2+
1/2+
3/2+
0+
2+
1/2+
3/2+
purpose of the experiment (summary)
beta-gammaand B(F) strength(and B(GT) ? )
beta-2-proton33Cl states feeding and direct 2p
gamma / proton widths, rp process
beta-proton high resol. spectro.B(GT) distribution
beta-(1-/2-)protonE(IAS), masses (IMME)
detailed decay scheme
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detection set-up (I): charged particles
“Silicon-cube” device6 DSSSD for protons high granularity (2p emission angles)
detection efficiency ~60% for 1 proton energy FWHM ~ 25 keV (low noise P.A.)
back-detectors- beta suppression- high-energy protons
ions deposited on athin mylar catcher
catcher
DSSSD
back-plane
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detection set-up (II): gamma-rays
Germanium detectors2 Ge-clusters (si-cube originally designed for 3 Ge-clovers)
(31Ar experiment with 2 MINIBALL clusters)
- high resolution
- efficiency ~10-15%(at 1 MeV)close geometry(~8 cm)
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beam-time request
production with TiC targets (under tests, unknown count rates)
measurements: cycles (T1/2) ~ 1 shift (~20% “duty cycle”)continuous production (100%)
experiment “duty cycle” ~75 %
detection efficiency 1 proton ~50 %2 protons ~25 %
daily count ratesp 2p total 2p direct
with 0.1 35Ca / s 3000 60 0.6 ?
beam-time request- Beam and separator tuning 3 shifts- Set-up tuning and calibration (37,36Ca…) 3 shifts- Experiment (35Ca beam) 24 shifts- Total 30 shifts
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35Ca decaybeta-delayed 1- and 2-proton
spokespersons: J. Giovinazzo (CENBG), O. Tengblab (CSIC)
institutions:
Centre d’Etudes Nucléaires (Bordeaux) – CNRS / univ. Bordeaux – France
Istituto de Estructura de la Materia (Madrid) – CSIC – Spain
Dep. of Physics and Astronomy (Aarhus) – univ. Aarhus – Denmark
PH department CERN (Geneva) – Switzerland
thank you for your attention…