Measurement of the β–ν correlation coefficienta_βνin the β decay of trapped⁶He⁺ions

Abstract

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Tensor Interaction Limit Derived From theα−β−ν¯Correlation in TrappedLi8Li1, Segel2, Scielzo3 et al. 2013Phys. Rev. Lett.361300View full textAdd to dashboardCite

“…The α particles emitted from the 8 Be * breakup are in the easily-measurable 1.5-MeV range and when emitted along the direction of a 12-keV 8 Be * recoil differ in energy by 400 keV and when emitted perpendicular to the recoil direction deviate from 180 • by 7 • . These kinematic shifts are much larger than those in other precision β-ν correlation experiments that have measured the nuclear recoil directly [4,[6][7][8] or have determined the nuclear recoil from delayed-particle emission [17][18][19][20].…”

“…A single measurement of the β-ν angular correlation in the β decay of 6 He reported in 1963 [4] (with additional radiative corrections recognized in 1998 [5]) has considerable influence on the C T limits. The only other β-ν angular correlation measurement that limits the tensor admixture to significantly less than 10% is a second measurement of the 6 Li recoil spectrum from 6 He decay that reports a 3.1% (1σ) uncertainty on the β-ν correlation coefficient [6]. In the present work, a result of similar precision on a different nucleus, 8 Li, is obtained by measuring the delayed-α energy spectra.…”

“…Recent measurements of the β-ν angular correlation coefficient performed with atom traps [7,8] and with ion traps [6] have achieved ∼1% precision and several proposed experiments [9,10] are aiming at 0.1% precision.…”

Prospects for precision measurements in nuclear decay in the LHC era

“…A measurement of a in the β decay of 6 He has also been carried out at GANIL by the Caen group [74] using the transparent Paul trap [70]. Since this measurement records the position and energy of the β particle and the position and time-of-flight of the 6 Li recoils detected in coincidence with the β particles, the kinematics is over determined allowing the construction of the neutrino invariant mass [75] and enabling the control of background and instrumental effects.…”

“…Three data production runs have been completed with this setup including a measurement of the shake-off probability of the singly bound electron in the recoiling ions following β decay [76]. A relative statistical error of 2% has been obtained from the analysis of the first run [74] with a systematic error of comparable size. Since no limit on tensor couplings has been quoted in Ref.…”