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Precise measurements of half-lives and branching ratios for two mirror decays involving 23 Mg and 27 Si Ccile Magron CEN Bordeaux-Gradignan European Nuclear Physics Conference 2015 2 O UTLINE OF THE TALK o Purpose of this work o JYFL13

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CΓ©cile Magron CEN Bordeaux-Gradignan European Nuclear Physics Conference 2015

Precise measurements of half-lives and branching ratios for two mirror 𝛾 decays involving 23Mg and 27Si

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SLIDE 2

OUTLINE OF THE TALK

  • Purpose of this work
  • JYFL13 experiment
  • Analysis and results

2

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SLIDE 3
  • Standard Model describes 3 of the 4 fundamental interactions:
  • Strong interaction
  • Electromagnetic interaction
  • Weak interaction

PURPOSE OF THIS WORK

3

p u d u n u d d e+ πœ‰e W+ pion decay super-allowed Fermi transitions 0+ β†’ 0+ free neutron decay nuclear mirror beta transitions

Ξ² decays

  • Two hypotheses of the SM can be tested:
  • Conserved Vector Current (CVC)
  • Unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) matrix
  • J. C. Hardy and I. S. Towner, Phys. Rev. C91, 025501 (2015).
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SLIDE 4

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  • CVC hypothesis: Gv unique for all beta transitions

PURPOSE OF THIS WORK

theoretical corrections experimental parameters

𝑔𝑒 = 𝑔 𝑹𝑭𝑫 (1 + 𝑄

𝐹𝐷) π‘ΌπŸ πŸ‘

π‘ͺ. 𝑺. ℱ𝑒 = 𝑔𝑒 1 + πœ€π‘†

β€²

1 + πœ€π‘‚π‘‡

π‘Š βˆ’ πœ€π· π‘Š

ℱ𝑒0 = β„±π‘’π»π‘Š

2|𝑁𝐺 0|2 1 + 𝑔 𝐡 𝑔 π‘Š

𝝇2 = 𝑑𝑑𝑒 π»π‘Š

2(1 + βˆ†π‘† π‘Š)

constant for mirror transitions

𝒀′𝑢+𝟐

π’‚βˆ’πŸ 𝑩

𝒀𝑢

𝒂 𝑩

π‘ΌπŸ πŸ‘ 𝑹𝑭𝑫 π‘ͺ. 𝑺. 𝜹

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SLIDE 5
  • Unitarity of the CKM matrix
  • First raw: π‘Š

𝑣𝑒 2 + π‘Š 𝑣𝑑 2 + π‘Š 𝑣𝑐 2 = 1

5

PURPOSE OF THIS WORK

π‘Š

𝑣𝑒 2 = π»π‘Š 𝐻𝜈 2

: main term

  • Current values for 5 mirror transitions:
  • ℱ𝑒0 = 6173 22 s (0.4% precision)
  • π‘Š

𝑣𝑒 = 0.9719 17 (0.2% precision)

Need for better precision to compete with super-allowed transitions

Quark mixing matrix: π‘Š

𝐷𝐿𝑁 =

π‘Š

𝑣𝑒

π‘Š

𝑣𝑑

π‘Š

𝑣𝑐

π‘Š

𝑑𝑒

π‘Š

𝑑𝑑

π‘Š

𝑑𝑐

π‘Š

𝑒𝑒

π‘Š

𝑒𝑑

π‘Š

𝑒𝑐

  • N. Severijns et al., Phys. Rev. C78, 055501 (2008).
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SLIDE 6

JYFL13 EXPERIMENT (23Mg, 27Si)

6

  • Performed at JyvΓ€skylΓ€ University (Finland) with IGISOL

𝒒 + π‘Άπ’ƒπŸπŸ‘

𝟐𝟐 πŸ‘πŸ’

β†’ π‘΅π’‰πŸπŸ

πŸπŸ‘ πŸ‘πŸ’

+ 𝒐 𝒒 + π‘©π’ŽπŸπŸ“

πŸπŸ’ πŸ‘πŸ–

β†’ π‘»π’‹πŸπŸ’

πŸπŸ“ πŸ‘πŸ–

+ 𝒐

  • Observed decays:

𝑇𝑗

14 27

β†’ π΅π‘šβˆ—

13 27

+ 𝒇+ + πœ‰π‘“ ↓ π΅π‘š

13 27

+ 𝜹 𝑁𝑕

12 23

β†’ π‘‚π‘βˆ—

11 23

+ 𝒇+ + πœ‰π‘“ ↓ 𝑂𝑏

11 23

+ 𝜹

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SLIDE 7

7

Ge tape transport system plastic scintillator (inside)

  • Half-lives:
  • Ξ²+ particles detected with plastic

scintillator

  • Branching ratios:
  • Ξ³ rays recorded with germanium

detector (Ge) precisely calibrated in efficiency (10-3)

  • Two data acquisitions:
  • a scaler for half-lives (fast)
  • a list mode for branching ratios

(slow)

JYFL13 EXPERIMENT (23Mg, 27Si)

  • B. Blank et al., NIM A 776 (2015).
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SLIDE 8

8

ANALYSIS AND RESULTS

Focus on 23Mg analysis

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SLIDE 9

8

time (s) time (s) counts

1 2 3 4 without DT correction with DT correction Background Accumulation Tape move Decay (~10 π‘ˆ1 2

)

4 1 2 3

fit of the decay part

Focus on 23Mg analysis

  • Half-life:

ANALYSIS AND RESULTS

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SLIDE 10

8

time (s)

Focus on 23Mg analysis

  • Half-life:

ANALYSIS AND RESULTS

same analysis for all runs

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SLIDE 11

9

Focus on 23Mg analysis

  • Half-life:
  • No systematic dependence on analysis and experiment parameters:
  • beginning and end of the fit,
  • number of nuclei in the decay phase,
  • background,
  • high voltage.

T1/2 = 11.3028 Β± 0.0043 s (0.04% precision)

ANALYSIS AND RESULTS

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SLIDE 12

9

Focus on 23Mg analysis

  • Half-life:
  • No systematic dependence on analysis and experiment parameters:
  • beginning and end of the fit,
  • number of nuclei in the decay phase,
  • background,
  • high voltage.

T1/2 = 11.3028 Β± 0.0043 s (0.04% precision)

  • Branching ratio:

23Mg 23Na

stable B.R.g.s. ~ ~ 91 91,2% Ξ³ 44 440 ke keV B.R.exc ~ ~ 8, 8,7% 𝐢. 𝑆.𝑓𝑦𝑑

𝐢. 𝑆.𝑕.𝑑. = 1 βˆ’ 𝑂𝛿,𝑒𝑓𝑒𝑓𝑑𝑒𝑓𝑒 πœπ›Ώ 1 𝑂

𝛾,𝑒𝑓𝑒𝑓𝑑𝑒𝑓𝑒

ANALYSIS AND RESULTS

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SLIDE 13

10

  • New T1/2 averages:
  • 23Mg: 3 times more

precise T1/2 = 11.3085(133) s

CONCLUSIONS

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SLIDE 14

10

  • New T1/2 averages:
  • 23Mg: 3 times more

precise T1/2 = 11.3085(133) s

  • 27Si: twice more precise

T1/2 = 4.1166(74) s

CONCLUSIONS

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SLIDE 15

10

  • To continue:
  • better precision for

branching ratio of

23Mg

  • measure ρ

coefficients for these nuclei

CONCLUSIONS

  • N. Severijns et al., Phys. Rev. C78,

055501 (2008).

  • New T1/2 averages:
  • 23Mg: 3 times more

precise T1/2 = 11.3085(133) s

  • 27Si: twice more precise

T1/2 = 4.1166(74) s

  • ld values
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SLIDE 16

11

Thank you for your attention

  • B. Blank, M. Gerbaux, J. Giovinazzo, S. GrΓ©vy, H. GuΓ©rin, T. Kurtukian-Nieto

CEN Bordeaux Gradignan, F-33175 Gradignan, France

  • A. de Roubin

Max-Plank-Institut FΓΌr Kernphysik, G-69029 Heidelberg, Germany

  • T. Eronen, D. Gorelov, J. Hakala, V. Kolhinen, J. Koponen, I. Moore, H. PenttilΓ€, I.

Pohjalainen, J. Reinikainen, M. Reponen, S. Rinta-Antila, A. Voss JYFL, FI-40014 JyvΓ€skylΓ€, Finland

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SLIDE 17

Backup

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SLIDE 18

Dead time correction: 𝑑 = 𝑑𝑖𝑀 1 βˆ’ 𝑑𝑖𝑀 βˆ— πΈπ‘ˆ π‘ˆ

π‘π‘—π‘œ

𝑑𝑖𝑀: channel value, number of counts before correction, πΈπ‘ˆ: dead time of the run, π‘ˆ

π‘π‘—π‘œ: time per channel.

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SLIDE 19

Systematic errors

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SLIDE 20

Precision on Vud for the different decays

  • J. Hardy