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