half-lives and branching ratios for two mirror decays involving 23 - PowerPoint PPT Presentation

Precise measurements of half-lives and branching ratios for two mirror 𝛾 decays involving 23 Mg and 27 Si Cécile Magron CEN Bordeaux-Gradignan European Nuclear Physics Conference 2015

2 O UTLINE OF THE TALK o Purpose of this work o JYFL13 experiment o Analysis and results

3 P URPOSE OF THIS WORK o Standard Model describes 3 of the 4 fundamental interactions: • Strong interaction p n • Electromagnetic interaction • Weak interaction β decays u u d d u d W + e + pion super-allowed Fermi free neutron nuclear mirror transitions 0 + → 0 + decay decay beta transitions 𝜉 e o 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. C 91 , 025501 (2015).

4 P URPOSE OF THIS WORK o CVC hypothesis: G v unique for all beta transitions 𝑔𝑢 = 𝑔 𝑹 𝑭𝑫 (1 + 𝑄 𝐹𝐷 ) 𝑼 𝟐 𝟑 experimental parameters 𝑪. 𝑺. theoretical corrections constant for mirror 𝑊 − 𝜀 𝐷 𝑊 ′ ℱ𝑢 = 𝑔𝑢 1 + 𝜀 𝑆 1 + 𝜀 𝑂𝑇 transitions 𝑑𝑡𝑢 0 | 2 1 + 𝑔 𝝇 2 = 2 |𝑁 𝐺 ℱ𝑢 0 = ℱ𝑢𝐻 𝑊 𝐵 𝑔 𝑊 ) 𝑊 2 (1 + ∆ 𝑆 𝐻 𝑊 𝑩 𝒀 𝑶 𝒂 𝑼 𝟐 𝟑 𝑹 𝑭𝑫 𝑪. 𝑺. 𝜹 𝑩 𝒀′ 𝑶+𝟐 𝒂−𝟐

5 P URPOSE OF THIS WORK o Unitarity of the CKM matrix Quark mixing matrix: 𝑊 𝑊 𝑊 𝑣𝑒 𝑣𝑡 𝑣𝑐 2 + 𝑊 2 + 𝑊 2 = 1 • First raw: 𝑊 𝑊 𝑊 𝑊 𝑊 𝐷𝐿𝑁 = 𝑣𝑒 𝑣𝑡 𝑣𝑐 𝑑𝑒 𝑑𝑡 𝑑𝑐 𝑊 𝑊 𝑊 𝑢𝑒 𝑢𝑡 𝑢𝑐 2 2 = 𝐻 𝑊 𝑊 : main term 𝑣𝑒 𝐻 𝜈 o Current values for 5 mirror transitions: Need for better • ℱ𝑢 0 = 6173 22 s (0.4% precision) precision to compete • 𝑊 𝑣𝑒 = 0.9719 17 (0.2% precision) with super-allowed transitions N. Severijns et al. , Phys. Rev. C 78 , 055501 (2008).

6 JYFL13 EXPERIMENT ( 23 Mg , 27 Si ) o Performed at Jyväskylä University (Finland) with IGISOL 𝟑𝟒 𝑶𝒃 𝟐𝟑 𝟑𝟒 𝑵𝒉 𝟐𝟐 𝒒 + → + 𝒐 𝟐𝟐 𝟐𝟑 𝟑𝟖 𝟑𝟖 𝑩𝒎 𝟐𝟓 𝑻𝒋 𝟐𝟒 𝒒 + → + 𝒐 𝟐𝟒 𝟐𝟓 o Observed decays: + 𝒇 + + 𝜉 𝑓 + 𝒇 + + 𝜉 𝑓 23 23 𝑂𝑏 ∗ 27 27 𝐵𝑚 ∗ 𝑁𝑕 → 𝑇𝑗 → 12 11 14 13 ↓ ↓ 23 27 𝑂𝑏 + 𝜹 𝐵𝑚 + 𝜹 11 13

7 JYFL13 EXPERIMENT ( 23 Mg , 27 Si ) o Half-lives: • β + particles detected with plastic plastic scintillator tape transport Ge scintillator (inside) system o Branching ratios: • γ rays recorded with germanium detector (Ge) precisely calibrated in efficiency (10 -3 ) B. Blank et al. , NIM A 776 (2015). o Two data acquisitions: • a scaler for half-lives (fast) • a list mode for branching ratios (slow)

8 A NALYSIS AND RESULTS Focus on 23 Mg analysis

8 A NALYSIS AND RESULTS Focus on 23 Mg analysis o Half-life: 1 without DT correction with DT correction 3 1 Background counts Accumulation 2 Tape move 3 Decay ( ~10 𝑈 1 2 4 ) 2 4 time (s) time (s) fit of the decay part

8 A NALYSIS AND RESULTS Focus on 23 Mg analysis o Half-life: time (s) same analysis for all runs

9 A NALYSIS AND RESULTS Focus on 23 Mg analysis o 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. T 1/2 = 11.3028 ± 0.0043 s (0.04% precision)

9 A NALYSIS AND RESULTS Focus on 23 Mg analysis o 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. T 1/2 = 11.3028 ± 0.0043 s (0.04% precision) 23 Mg o Branching ratio: B.R. exc ~ ~ 8, 8,7% 𝑂 𝛿,𝑒𝑓𝑢𝑓𝑑𝑢𝑓𝑒 1 𝐶. 𝑆. 𝑕.𝑡. = 1 − 𝜁 𝛿 𝑂 B.R. g.s. ~ ~ 91 91,2% 𝛾,𝑒𝑓𝑢𝑓𝑑𝑢𝑓𝑒 440 ke 44 keV γ 𝐶. 𝑆. 𝑓𝑦𝑑 stable 23 Na

10 C ONCLUSIONS o New T 1/2 averages: • 23 Mg: 3 times more precise T 1/2 = 11.3085(133) s

10 C ONCLUSIONS o New T 1/2 averages: • 23 Mg : 3 times more precise T 1/2 = 11.3085(133) s • 27 Si : twice more precise T 1/2 = 4.1166(74) s

10 C ONCLUSIONS o New T 1/2 averages: • 23 Mg : 3 times more precise T 1/2 = 11.3085(133) s • 27 Si : twice more precise T 1/2 = 4.1166(74) s o To continue: • better precision for branching ratio of old values 23 Mg • measure ρ coefficients for these nuclei N. Severijns et al. , Phys. Rev. C 78 , 055501 (2008).

11 Thank you for your attention B. Blank, M. Gerbaux, J. Giovinazzo, S. Grévy, H. Guérin, T. Kurtukian-Nieto CEN Bordeaux Gradignan, F-33175 Gradignan, France A. de Roubin Max-Plank-Institut Für Kernphysik, G-69029 Heidelberg, Germany T. Eronen, D. Gorelov, J. Hakala, V. Kolhinen, J. Koponen, I. Moore, H. Penttilä, I. Pohjalainen, J. Reinikainen, M. Reponen, S. Rinta-Antila, A. Voss JYFL, FI-40014 Jyväskylä, Finland

Backup

Dead time correction: 𝑑𝑖𝑤 𝑑 = 1 − 𝑑𝑖𝑤 ∗ 𝐸𝑈 𝑈 𝑐𝑗𝑜 𝑑𝑖𝑤 : channel value, number of counts before correction, 𝐸𝑈 : dead time of the run, 𝑈 𝑐𝑗𝑜 : time per channel.

Systematic errors

Precision on Vud for the different decays J. Hardy