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14–16 Dec 2021
Europe/Zurich timezone

Weak interaction studies with 32Ar decay

15 Dec 2021, 09:30
12m

Speaker

Federica Vera Cresto (LPC Caen - CENBG)

Description

Nuclear beta decay has represented for more than half a century a blooming testing ground for the Standard Model (SM), contributing particularly to the development of the theory of the electroweak interaction. The broad variety of nuclear states and beta transitions provide a highly remarkable tool to be competitive with high-energy physics experiments in searching for the possible presence of non-SM contributions to the firmly established vector - axial-vector (V-A) description of the weak interaction [1]. Particularly, the joined experimental determination of the beta-neutrino angular correlation coefficient (aβν) and the correlated Fierz term (bF) in pure Fermi and Gamow-Teller transitions directly allows to set new stringent limits on the existence of scalar and tensor currents, respectively.

The most forthcoming way to retrieve aβν would be to measure the correlation between the leptons emitted in the decay; yet, as a direct measurement of the neutrino is almost impossible, the aβν coefficient can be determined from the recoil of the daughter nucleus, which can be measured either directly by means of trap measurements or via the kinematic shift it induces on the energy distribution of the β-delayed particles emitted in case of unstable daughter nuclei, as foreseen in the WISArD experiment at CERN.

The WISArD (Weak Interaction Studies with 32Ar Decay) experiment [2] aims at a precise measurement of both the aβν and the bF coefficients for both Fermi and Gamow-Teller transitions by using, differently from previous measurements [3], the kinematic energy shift of the β-delayed protons emitted in the same or the opposite direction to the β-particle from 32Ar. A proof-of-principle experiment, though limited in statistics and performed via a still rudimental experimental set-up, has been successfully accomplished at ISOLDE in November 2018, already leading to the third best measurement of aβν for Fermi transitions [4]. After determining and estimating the systematic errors, a consistent upgrade of the experimental set-up has been commissioned and realized through the past two years, potentially permitting to reach the aimed precision of the permil level on the determination of both aβν and bF. In this talk, the new experimental campaign conduced at ISOLDE in October 2021, along with the enhancements in the newly dedicated detection set-up, will be presented and the first preliminary results will be discussed.

[1] V. Cirigliano, A. Garcia et al., arXiv:1907.02164

[2] B. Blank et al., CERN-INTC-2016 (2016)

[3] E. G. Adelberger et al., Phys. Rev. Lett. 83, 1299 (1999)

[4] V. Araujo-Escalona et al., PCR 101, 055501 (2020)

Author

Federica Vera Cresto (LPC Caen - CENBG)

Co-authors

Dr Dalibor Zakoucky (NPI CAS Rez) Dr Maud Versteegen (CENBG) Simon Vanlangendonck (KU Leuven) Dr Nathal Severijns (KU Leuven) Mr Mathieu Roche (CENBG) Dr Marcin Pomorski (CENBG) Dr Etienne Lienard (LPC Caen) Dr Stephane Grevy (CENBG) Dr Jerome Giovinazzo (CENBG) Dr Mathias Gerbaux (CENBG) Dr Dinko Atanasov (CENBG) Dr Bertram Blank (CENBG) Mr Philippe Alfaurt (CENBG) Dr Pauline Ascher (CENBG) Mr Laurent Daudin (CENBG) Dr Xavier Flechard (LPC Caen) Dr Teresa Kurtukian Nieto (CENBG)

Presentation materials