Electron-Neutrino Angular Correlation in the Decay of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">He</mml:mi></mml:mrow><mml:mrow><mml:mn>6</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>

Vise, J.B.; Rustad, B.M.

doi:10.1103/physrev.132.2573

Cited by 17 publications

(19 citation statements)

References 30 publications

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“…The average background rate of the data taking runs was 0.8±0.1 Hz, which is consistent with the average of the rates of the background runs. Combining all the background run data after shielding the bellows, we still observed a small decay structure with a half-life of 507 (27) ms and an amplitude of 6.3(3) times the value of the constant background in the background runs. While this is most probably still coming from 6 He that is being pumped away it could also be the result of some beam-related activation.…”

Section: Systematic Uncertaintiesmentioning

confidence: 90%

Precision measurement of the6He half-life and the weak axial current in nuclei

et al. 2012

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Background: The beta decays of 3 H and 6 He can play an important role in testing nuclear wave-function calculations and fixing low-energy constants in effective-field theory approaches. However, there exists a large discrepancy between previous measurements of the 6 He half-life.Purpose: Our measurement aims at resolving this long-standing discrepancy in the 6 He half-life and providing a reliable f t-value and Gamow-Teller matrix element for comparison with theoretical ab-initio calculations.Method: We measured the 6 He half-life by counting the beta-decay electrons with two scintillator detectors operating in coincidence.Results: The measured 6 He half-life is 806.89 ± 0.11stat +0.23 −0.19 syst ms corresponding to a relative precision of 3 × 10 −4 . Calculating the statistical rate function we determined the f t-value to be 803.04 +0.26 −0.23 s. Conclusions: Our result resolves the previous discrepancy by providing a higher-precision result with careful analysis of potential systematic uncertainties. The result provides a reliable basis for future precision comparisons with ab-inito calculations.

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Section: Systematic Uncertaintiesmentioning

confidence: 90%

Precision measurement of the6He half-life and the weak axial current in nuclei

et al. 2012

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“…The electroweak interaction is described by the standard model (Salam and Ward, 1964;Weinberg, 1967). The symmetries of the underlying SU L (2) × U (1) gauge group determine the properties of the interaction and generate the intermediate vector bosons.…”

Section: A the V-a Theorymentioning

confidence: 99%

“…The structure of the vector and axial vector hadronic currents, consistent with Lorentz invariance and including recoil terms, has the general form (Fujii and Primakoff, 1959;Goldberger and Treiman, 1958;Weinberg, 1958) …”

Section: G Higher-order Correctionsmentioning

confidence: 99%

Tests of the standard electroweak model in nuclear beta decay

2006

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We review the current status of precision measurements in allowed nuclear beta decay, including neutron decay, with emphasis on their potential to look for new physics beyond the standard electroweak model. The experimental results are interpreted in the framework of phenomenological model-independent descriptions of nuclear beta decay as well as in some specific extensions of the standard model. The values of the standard couplings and the constraints on the exotic couplings of the general beta decay Hamiltonian are updated. For the ratio between the axial and the vector couplings we obtain C A /C V = −1.26992(69) under the standard model assumptions. Particular attention is devoted to the discussion of the sensitivity and complementarity of different precision experiments in direct beta decay. The prospects and the impact of recent developments of precision tools and of high intensity low energy beams are also addressed.

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“…For such transitions, the experiment described here was the first performed after decades following the last measurements of the beta-neutrino angular correlation in the β decay of 6 He [14][15][16] and 23 Ne [17,18]. Another new experiment, measuring the β−α−α correlation from trapped 8 Li ions, has recently reported the first results [19].…”

Section: Measurements In the Decay Of 6 Hementioning

confidence: 99%

“…The measurement presented here, performed with a different and independent method, confirms the result of Johnson et al It is to be recalled that the reduced chi-square χ 2 /ν = 0.92 for 105 degrees of freedom obtained in the present work corresponds to a P-value of 0.71. This is to be compared to a P-value of 0.055 for the Johnson et al experiment, with Figure 8 From top to bottom: a βν experimental values in pure GT transitions from [14,17,18] (left panel), [19], present work, [15], and [16] (right panel). The error bars show the quadratic sums of statistical and systematic uncertainties.…”

Section: Sourcementioning

confidence: 99%

Precision measurements in nuclear ‐decay with LPCTrap

et al. 2013

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The experimental achievements and the current program with the LPCTrap device installed at the LIRAT beam line of the SPIRAL1-GANIL facility are presented. The device is dedicated to the study of the weak interaction at low energy by means of precise measurements of the β−ν angular correlation parameter. Technical aspects as well as the main results are reviewed. The future program with new available beams is briefly discussed. The β−ν angular correlationThe structure of the weak interaction remains an important topic in the area of fundamental interaction physics. In particular, at low energies, there are nowadays ambitious experimental programs to search for "exotic" currents beyond the V-A theory [1,2]. Such studies have recently made significant progress with the advent of improved trapping techniques [3,4]. These sophisticated setups allow the production of β-decay sources almost at rest and confined in small volumes that can be surrounded by suitable detectors [5,6]. We describe here the achievements made with the LPCTrap setup installed at GANIL 1 . The experimental program is dedicated to precision measurements of the β−ν angular correlation parameter.From a theoretical point of view, the generalization of Fermi's theory leads to consideration of five different Lorentz invariant contributions in the transition amplitude describing nuclear beta decay, which are referred to as scalar (S), vector (V), tensor (T), axial-vector (A) and pseudoscalar (P). The search for S and T exotic contributions can be performed through a precise measurement of the β−ν angular correlation parameter, a βν . For allowed transitions and nonoriented nuclei, this parameter can be directly inferred from an events distribution linked to the angular correlation between the leptons [7]. GANIL: Grand Accélérateur National d'Ions LourdsSince neutrinos are difficult to detect, a sensitive observable for a β−ν angular correlation measurement is a kinematic parameter of the recoiling daughter nucleus. If the β particles and the recoil ions are detected in coincidence and the relative time of flight (ToF) is measured between the two particles, the expected distribution of events in the electron energy and recoil ion time of flight, t, is for all solid angles detected:where T e , E e and r(t) denote the kinetic and total energies of the β particle and the recoil ion momentum, respectively. Q is the energy available in the transition, K is a constant and F(± Z, E e ) is the Fermi function (β − and β + decays). The parameter a βν and the Fierz interference term b depend on the coupling constants, C i and C i (i = S, V, T, A), associated to the different contributions [7]:

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Electron-Neutrino Angular Correlation in the Decay ofHe6

Cited by 17 publications

References 30 publications

Precision measurement of the6He half-life and the weak axial current in nuclei

Precision measurement of the6He half-life and the weak axial current in nuclei

Tests of the standard electroweak model in nuclear beta decay

Precision measurements in nuclear ‐decay with LPCTrap

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