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Precision measurement of the half-life and branching ratio of the T=1/2 mirror β decay of 37 K T. Kurtukian-Nieto , P. Ascher, B. Blank, G. Canchel, M. Gerbaux, J. Giovinazzo, S. Grévy Centre d'Etudes Nucléaires de Bordeaux-Gradignan, France A. Bacquias IPHC Strasbourg, France H. Bouzomita, G. F. Grinyer, J. C. Thomas GANIL Caen, France C. Couratin, X. Flechard, E. Lienard LPC-Caen, France I. Matea IPN-Orsay, France J. Liendo Universidad Simon Bolivar, Venezuela Contact person CERN-Isolde: M. Kowalska 41st Meeting of the INTC. CERN, November 3 rd , 2011

Precision measurement of the half-life and branching ratio of the T=1/2 mirror β decay of 37 K T. Kurtukian-Nieto, P. Ascher, B. Blank, G. Canchel, M

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Page 1: Precision measurement of the half-life and branching ratio of the T=1/2 mirror β decay of 37 K T. Kurtukian-Nieto, P. Ascher, B. Blank, G. Canchel, M

Precision measurement of the half-life and branching ratio of the T=1/2 mirror β decay of

37KT. Kurtukian-Nieto, P. Ascher, B. Blank, G. Canchel, M. Gerbaux, J. Giovinazzo, S. Grévy

Centre d'Etudes Nucléaires de Bordeaux-Gradignan, France

A. BacquiasIPHC Strasbourg, France

H. Bouzomita, G. F. Grinyer, J. C. Thomas

GANIL Caen, France

C. Couratin, X. Flechard, E. LienardLPC-Caen, France

I. MateaIPN-Orsay, France

J. LiendoUniversidad Simon Bolivar, Venezuela

Contact person CERN-Isolde: M. Kowalska

41st Meeting of the INTC. CERN, November 3rd, 2011

Page 2: Precision measurement of the half-life and branching ratio of the T=1/2 mirror β decay of 37 K T. Kurtukian-Nieto, P. Ascher, B. Blank, G. Canchel, M

Teresa Kurtukian Nieto November 3rd, 2011 2CERN-INTC-P-311

Measurements needed :• Qvalue• Branching ratio of super-allowed transition• -decay half-life• - angular correlation coefficient

QEC

T1/2

BR

Superallowed Mixed Mirror β decay

ft = f(Qec) * T1/2 / BR

O. Naviliat-Cuncic and N. Severijns PRL 102, 142302 (2009)

consistent test of CVC from a set of nuclear transitions other than super-allowed pure Fermi

Page 3: Precision measurement of the half-life and branching ratio of the T=1/2 mirror β decay of 37 K T. Kurtukian-Nieto, P. Ascher, B. Blank, G. Canchel, M

Teresa Kurtukian Nieto November 3rd, 2011 3CERN-INTC-P-311

Introduction: quark-mixing matrix CKM

b

s

d

VVV

VVV

VVV

b

s

d

tbtstd

cbcscd

ubusud unitarity condition: 1VVV 2

ub2

us2

ud

O. Naviliat-Cuncic, N. Severijns

Page 4: Precision measurement of the half-life and branching ratio of the T=1/2 mirror β decay of 37 K T. Kurtukian-Nieto, P. Ascher, B. Blank, G. Canchel, M

Teresa Kurtukian Nieto November 3rd, 2011 4CERN-INTC-P-311

2011

Least known quantity: Fermi / Gamow-Teller ratio second least known quantity: half-lives

Existing measurements

2009

JYFL ISOLDE

xxxxxx

Page 5: Precision measurement of the half-life and branching ratio of the T=1/2 mirror β decay of 37 K T. Kurtukian-Nieto, P. Ascher, B. Blank, G. Canchel, M

Teresa Kurtukian Nieto November 3rd, 2011 5CERN-INTC-P-311

Why to measure 37K ?

T=1/2, decay is predominantly 3/2+ to 3/2+ mixed Fermi/GT decay

Correlation measurements to be performed:

• our collaboration E. Lienard et al.

@ GANIL 19Ne,35Ar,29P,37K,39Ca

• D. Melconian et al. @ TRIUMF 2012

using laser-cooled 37K

(Melconian PhDThesis (2005), AIP C. Proc.1342 (2011) 53

Arxiv: 1108.2530v1 [nucl-ex] 11 Aug 2011)

Aim:• ΔT1/2 ~ 0.1 %

• ΔB.R. ~ 0.1 %

Page 6: Precision measurement of the half-life and branching ratio of the T=1/2 mirror β decay of 37 K T. Kurtukian-Nieto, P. Ascher, B. Blank, G. Canchel, M

Teresa Kurtukian Nieto November 3rd, 2011 6CERN-INTC-P-311

Our recent efforts : 38-39Ca

ISOLDE 2007

Blank et al., EPJ A 44,363 (2010)

38Ca T1/2 = 443.8 ± 1.9 ms

Page 7: Precision measurement of the half-life and branching ratio of the T=1/2 mirror β decay of 37 K T. Kurtukian-Nieto, P. Ascher, B. Blank, G. Canchel, M

Teresa Kurtukian Nieto November 3rd, 2011 7CERN-INTC-P-311

Our recent efforts : 38-39Ca

ISOLDE 2007

Blank et al., EPJ A 44,363 (2010)

39Ca T1/2 = 860.7 ± 1.0 ms

Page 8: Precision measurement of the half-life and branching ratio of the T=1/2 mirror β decay of 37 K T. Kurtukian-Nieto, P. Ascher, B. Blank, G. Canchel, M

Teresa Kurtukian Nieto November 3rd, 2011 8CERN-INTC-P-311

Half-life and BR measurement of 37K

radioactiveions

detection- gas counter- germanium

GSI tapesystem

Experimental procedure:• production with Ti target• separation with HRS/GPS A=37

• only 37Ca T1/2=181.1(10) ms • accumulation on tape during 1 s• tape transport into setup• after 2.5 s, measurement for 20T1/2

• tape move and new cycle starts

Detection setup at LA1 beamline

Page 9: Precision measurement of the half-life and branching ratio of the T=1/2 mirror β decay of 37 K T. Kurtukian-Nieto, P. Ascher, B. Blank, G. Canchel, M

Teresa Kurtukian Nieto November 3rd, 2011 9CERN-INTC-P-311

β detection setup

4π gas counter • two single-wire gas counter

• P5 (95% Ar, 5% CH4) or CF4

• moving tape passes through a slit between the two detectors

• thin aluminised Mylar entrance windows allows to detect low-energy β particles

• Active volume 2 x 37.4 cm3

Advantage of using a gas counter:

•Electronic thresholds:

• For the gas counter operated in the plateau region, the electronic detection threshold is too low for losses from that source to have any effect on the overall efficiency.

• Plastic scintillatior and photomultipliers tubes impose a non-negligible low-energy electronic thresholds.

Page 10: Precision measurement of the half-life and branching ratio of the T=1/2 mirror β decay of 37 K T. Kurtukian-Nieto, P. Ascher, B. Blank, G. Canchel, M

Teresa Kurtukian Nieto November 3rd, 2011 10CERN-INTC-P-311

Measurements with• a fast DAQ system - two electronic chains: 4 μs and 8 μs fixed dead-time • a listmode DAQ system - half-life measurement with 100μs DT - γ-ray measurement for branching ratio

search for systematic errors:

- different CFD thresholds- different detector HV- different gas flow- different cycle times

Experimental details

beam

detection- gas counter- germanium

GSI tapesystem

Detection setup at LA1 beamline

Page 11: Precision measurement of the half-life and branching ratio of the T=1/2 mirror β decay of 37 K T. Kurtukian-Nieto, P. Ascher, B. Blank, G. Canchel, M

Teresa Kurtukian Nieto November 3rd, 2011 11CERN-INTC-P-311

Beam request

• cycle length: 1s + 2.5s + 20T1/2 = 28 s• effective rate: 1000 37K decays detected/cycle

• i.e. count rate: few 103 37K per second• 3 days of effective counting: ~ 7.7 million 37K decays• 2 days search for systematic errors ~ 13 million 37K decays (total) ΔT1/2 < 0.1 %• within 5 days (15 shifts) ~ 40 000 β-γ for 2796 keV ε=0.3% ΔBR < 0.1 %• 1 shift to optimise production-----------------------------------------------------------------------------Total request: 16 shifts

Aim:• T1/2 ~ 0.1 %• BR ~ 0.1 %

Accumulation Decay of 37Ca

Measuring time

Page 12: Precision measurement of the half-life and branching ratio of the T=1/2 mirror β decay of 37 K T. Kurtukian-Nieto, P. Ascher, B. Blank, G. Canchel, M

Thank Thank you you

Page 13: Precision measurement of the half-life and branching ratio of the T=1/2 mirror β decay of 37 K T. Kurtukian-Nieto, P. Ascher, B. Blank, G. Canchel, M

Teresa Kurtukian Nieto November 3rd, 2011 13CERN-INTC-P-311

4π gas counter

anode wire

Thin windows

tape

Gas counter halves

• two single-wire gas counter

• P5 (95% Ar, 5% CH4) or CF4

• moving tape passes through a slit between the two detectors

• thin aluminised Mylar entrance windows allows to detect low-energy β particles

• Active volume 2 x 37.4 cm3

Page 14: Precision measurement of the half-life and branching ratio of the T=1/2 mirror β decay of 37 K T. Kurtukian-Nieto, P. Ascher, B. Blank, G. Canchel, M

Teresa Kurtukian Nieto November 3rd, 2011 14CERN-INTC-P-311

Contaminants expected

Page 15: Precision measurement of the half-life and branching ratio of the T=1/2 mirror β decay of 37 K T. Kurtukian-Nieto, P. Ascher, B. Blank, G. Canchel, M

Teresa Kurtukian Nieto November 3rd, 2011 15CERN-INTC-P-311

Experimental setup at JYFL

Page 16: Precision measurement of the half-life and branching ratio of the T=1/2 mirror β decay of 37 K T. Kurtukian-Nieto, P. Ascher, B. Blank, G. Canchel, M

Teresa Kurtukian Nieto November 3rd, 2011 16CERN-INTC-P-311

preli

minary

JYFL 2009

T1/2 = 4123.4(51) msT1/2 = 2546.4(18) ms

T. Kurtukian Nieto, A. Bacquias et al.

Our recent efforts : 29P and 31S