Teresa Kurtukian-Nieto
Centre d’Etudes Nucléaires de Bordeaux Gradignan
Precision half-life determination of the
superallowed 0+ →0+ β+-emmiters 42Ti,38Ca,30S
and the mirror β transitions of 39Ca, 31S and 29P
Workshop of ESNT: Isospin symmetry and its breaking in nuclear structure
CEA/SPhN-Saclay, April 29th 2011
Teresa Kurtukian Nieto, CENBG April 29th 2011 2CEA/SPhN Workshop of the ESNT
Experimental ft measurements
T1/2
QEC
BR
0+
0+
Precision measurements required:
QEC → mass measurements: f ~ Q5
T1/2, BR → -decay studies: t = T1/2 / BR
to test Ft value required relative precision ~10-3
22 2
1
1 /1 a vv F R f f
ktg M
F
Mirror Transitions T=1/2
22
1
1v F R
ktg M
F
Super Allowed Fermi 0+ → 0+
Teresa Kurtukian Nieto, CENBG April 29th 2011 3CEA/SPhN Workshop of the ESNT
• typical setup:
- beam purification system: traps
- beta detector
- gamma detectors
Half-life measurements:Experimental details
JYFL – IGISOL
ISOLDE / CERN
JYFL – IGISOL
ISOLDE / CERN
Teresa Kurtukian Nieto, CENBG April 29th 2011 4CEA/SPhN Workshop of the ESNT
JYFLTRAP
detector
Gedetectors
Tapetransportsystem
Typical setup: JYFL – IGISOL
Teresa Kurtukian Nieto, CENBG April 29th 2011 5CEA/SPhN Workshop of the ESNT
detection setup- plastic scintillator- germanium
tape transport system
Typical setup: JYFL – IGISOL
Teresa Kurtukian Nieto, CENBG April 29th 2011 6CEA/SPhN Workshop of the ESNT
Typical setup: ISOLDE / CERN
radioactiveions
detection- gas counter- germanium
GSI tapesystem
Teresa Kurtukian Nieto, CENBG April 29th 2011 7CEA/SPhN Workshop of the ESNT
Half-life measurements:Experimental details
measurement principle
cycles- isotope accumulation
- purification - transport
- decay measurement- remaining activity evacuation
measurement principle
cycles- isotope accumulation
- purification - transport
- decay measurement- remaining activity evacuation
• different fixed dead times: 2 s, 8 s, 100s
• different detector high-voltages
• different detection thresholds
Teresa Kurtukian Nieto, CENBG April 29th 2011 8CEA/SPhN Workshop of the ESNT
•Data analysis:
• cycle selection: no beam, detector sparking…
• half-life cuts: test of dead time correction
• half-life as a function of background, of rate, of detector settings
Is there any dependence of the half-life of these parameters?
error budget
Half-life measurements:Experimental details
Super Allowed Fermi 0+ → 0+
Teresa Kurtukian Nieto, CENBG April 29th 2011 10CEA/SPhN Workshop of the ESNT
all nuclei of interest
Experimental quantities:• Q values: traps, high precision “easily” reachable• half-lives: feasible• branching ratios: hard part…
Error budget
Super Allowed Fermi 0+ → 0+: 42Ti
Teresa Kurtukian Nieto, CENBG April 29th 2011 12CEA/SPhN Workshop of the ESNT
Beam purification: JYFLTRAP
Teresa Kurtukian Nieto, CENBG April 29th 2011 13CEA/SPhN Workshop of the ESNT
Typical spectrum: one run
Teresa Kurtukian Nieto, CENBG April 29th 2011 14CEA/SPhN Workshop of the ESNT
Implantation on the tape?
Teresa Kurtukian Nieto, CENBG April 29th 2011 15CEA/SPhN Workshop of the ESNT
2s
8s
100s
Dead time correction: part 1
Teresa Kurtukian Nieto, CENBG April 29th 2011 16CEA/SPhN Workshop of the ESNT
test of dead time correction
Dead time correction: part 2
Teresa Kurtukian Nieto, CENBG April 29th 2011 17CEA/SPhN Workshop of the ESNT
Different experimental conditions:
thresholds and high-voltages
Teresa Kurtukian Nieto, CENBG April 29th 2011 18CEA/SPhN Workshop of the ESNT
• counting statistics: 0.45• dead time correction: 0.01• experimental parameters (threshold, HV): 0.00• T1/2 as function of background: 0.00• T1/2 as function of counting rate: 0.00• “wrong” implantation: 0.00--------------------------------------------------------------------Total: 0.45
T1/2(42Ti) = 208.14 ± 0.45 ms
Error budget
Teresa Kurtukian Nieto, CENBG April 29th 2011 19CEA/SPhN Workshop of the ESNT
T. Kurtukian Nieto et al., PRC80 (2009) 035502
BR = 48.2(15)%
611 keV
Ft = 3114(79)
Half-life of 42Ti:
JYFL 2008
42Ti T1/2 = 208.14 ± 0.45 ms (2.16 ‰)
Teresa Kurtukian Nieto, CENBG April 29th 2011 20CEA/SPhN Workshop of the ESNT
Half-life of 42Ti:
Super Allowed Fermi 0+ → 0+: 38Ca
Teresa Kurtukian Nieto, CENBG April 29th 2011 22CEA/SPhN Workshop of the ESNT
Half-life of 38Ca:
ISOLDE 2007
38Ca T1/2 = 443.8 ± 1.9 ms Blank et al., EPJ A 44,363 (2010)
Teresa Kurtukian Nieto, CENBG April 29th 2011 23CEA/SPhN Workshop of the ESNT
Half-life of 38Ca:
Super Allowed Fermi 0+ → 0+: 30S
Teresa Kurtukian Nieto, CENBG April 29th 2011 25CEA/SPhN Workshop of the ESNT
Half-life measurements : 30S
JYFL 2009
Teresa Kurtukian Nieto, CENBG April 29th 2011 26CEA/SPhN Workshop of the ESNT
Half-life measurements : 30S
30S T1/2 = 1175.9 ± 1.7 ms (1.45 ‰) Souin, et al., EPJA (2011)
30P (T1/2 = 148.88 ± 0.24 s) as contamination as daughter
need to characterize bothcontributions
- filiation of 30Sno additional parameter
- production (mass separator)background constraintrequired
example ru
n
Teresa Kurtukian Nieto, CENBG April 29th 2011 27CEA/SPhN Workshop of the ESNT
Half-life measurements : 30S
Teresa Kurtukian Nieto, CENBG April 29th 2011 28CEA/SPhN Workshop of the ESNT
Error budget
sensitive improvement for half-lives
some difficult work to do for branching ratios
2007
2011
Mirror decayMirror decay
Teresa Kurtukian Nieto, CENBG April 29th 2011 30CEA/SPhN Workshop of the ESNT
Mirror decayMirror decay
Measurements required:• -decay Q value• super-allowed branching ratio• -decay half-life• - angular correlation coefficient
N. Severijns, O. Naviliat-Cuncic
Teresa Kurtukian Nieto, CENBG April 29th 2011 31CEA/SPhN Workshop of the ESNT
Status in 2009
Experimental quantities:
• half-lives: feasible
Teresa Kurtukian Nieto, CENBG April 29th 2011 32CEA/SPhN Workshop of the ESNT
Mirror transitions: Half-lives of 39Ca
Blank et al., EPJ A 44,363 (2010)
Teresa Kurtukian Nieto, CENBG April 29th 2011 33CEA/SPhN Workshop of the ESNT
T. Kurtukian Nieto, A. Bacquias et al.
T1/2 = 2546.4(18) ms
Mirror transitions: Half-life of 31S:
JYFL 2009
Teresa Kurtukian Nieto, CENBG April 29th 2011 34CEA/SPhN Workshop of the ESNT
JYFL 2009
Mirror transitions: Half-life of 29P:
preli
minary
T. Kurtukian Nieto, A. Bacquias et al.
Teresa Kurtukian Nieto, CENBG April 29th 2011 35CEA/SPhN Workshop of the ESNT
Error budget
2009
2011
Branching Ratio MeasurementsBranching Ratio Measurements
• Need to know the efficiency with a precision of 0.1%
• calibration programme of a monocristal detector:
- source measurements - MC simulations
Ge
Capot Al
Detector scheme
J. Souin
RX of the detector
Scanning done with a collimated 137Cs (CSNSM Orsay)
HPGe
X-Y table 137Cs collimated (477MBq)
J. Souin
Teresa Kurtukian Nieto, CENBG April 29th 2011 39CEA/SPhN Workshop of the ESNT
Determination of the germanium active volumen
Front cap
Length of the hole (13.6mm larger than
expected)
J. Souin
Scanning done with collimated 137Cs source
Teresa Kurtukian Nieto, CENBG April 29th 2011 40CEA/SPhN Workshop of the ESNT
Calibration programme at Bordeaux
Gamma sources (with BR know with high precition) done at ISOLDE:
75Se, 27Mg, 24Na, 66Ga, 56Co
133Ba,60Co,207Bi,137Ce,
152Eu,88Y,
85Sr,51Cr,54Mn,57Co
Teresa Kurtukian Nieto, CENBG April 29th 2011 41CEA/SPhN Workshop of the ESNT
Summary : 0+->0+
2007
2011
Teresa Kurtukian Nieto, CENBG April 29th 2011 42CEA/SPhN Workshop of the ESNT
Summary Mirror Transitions
2009
2011
Teresa Kurtukian Nieto, CENBG April 29th 2011 43CEA/SPhN Workshop of the ESNT
The End
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