Speaker
Pierre Delahaye
(Grand Accelerateur National d'Ions Lourds (FR))
Description
In this contribution we discuss the potentials of a new technique of optical orientation of radioactive ions trapped in an open Paul trap, permitting to reach a very high degree of polarization, for beta decay experiments.
More precisely, laser polarization of the alkali-earth ions 23Mg+ and 39Ca+ in a Paul trap and detection of the emitted electron and recoil ion shall enable the measurement of the so-called D correlation. D is a triple correlation of the form <**J**> (**pe** x **pnu**) with pe and pnu being the momenta of the electron and the neutrino, and J the nuclear spin. The D correlation violates Time reversal. While such violation is predicted to occur in the Standard Model via the quark mixing mechanism, experimental constraints are 5 to 10 orders of magnitude lower [1].There is a large window in which D, R correlations and neutron EDM searches can contribute to the search for other sources of CP violation at a much higher level, which could explain for example the large matter-antimatter asymmetry observed in the universe. The best constraints so far on D arise from the neutron decay and are of the order of 2×10-4 on coupling constants of interactions violating T [2]. Lower constraints have been obtained from hyperon, Kaon, and nuclear decays. The latter were derived from the decay of 19Ne yielding a constraint of 6×10-4, limited by statistics [3]. With the expected rates from the upgraded SPIRAL facility at GANIL, an experiment aiming at D-correlation measurement with an unprecedented sensitivity of the order of 10-4 can be conceived. It is envisaged to perform a proof-of-principle of the laser polarization method at ISOLDE, using the COLLAPS laser setup, together with an optimized trapping setup inspired by the one of LPCTrap [4].
[1]: G. Ban et al., Nucl. Phys. A 827, 422c (2009)
[2]: J. Beringer et al, (Particle Data Group) Phys. Rev. D 86 (2012) 010001
[3]: F. P. Calaprice, Hyp. Interact. 22 (1985) 83
[4]: G. Ban et al, Ann. Phys. (Berlin) 525(2013)576
Authors
Etienne Lienard
(Universite de Caen (FR))
Pierre Delahaye
(Grand Accelerateur National d'Ions Lourds (FR))
Co-authors
Gerda Neyens
(Katholieke Universiteit Leuven (BE))
Klaus Blaum
(Max-Planck-Gesellschaft (DE))
Mark Bissell
(Katholieke Universiteit Leuven (BE))
Martin Gonzalez-Alonso
(IPN Lyon)
Nathal Severijns
(Katholieke Universiteit Leuven (BE))
