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8th International Conference on Radioactive Nuclear Beams (RNB8), Grand Rapids : États-Unis (2009)
Correlation measurement in the $\beta$ decay of trapped $^{6}$He ions
E. Liénard1, G. Ban1, D. Durand1, X. Fléchard1, F. Mauger1, A. Méry2, O. Naviliat-Cuncic1, D. Rodríguez, J.-C. Thomas2, P. Velten1
SPIRAL Collaboration(s)

The LPCTrap facility coupled to the low-energy beam line LIRAT of the SPIRAL installation at GANIL is a transparent Paul trap designed to perform in-trap decay experiments [1]. The first detection setup installed at this facility has been designed in order to precisely determine the b-n angular correlation coefficient abn in the pure Gamow-Teller decay of 6He [2]. This coefficient constitutes a sensitive observable to search for exotic couplings in the weak interaction. In the case of 6He decay, a deviation of abn from the Standard Model value (-1/3) would imply the existence of a tensor like interaction mediated by new bosons called leptoquarks. The detection setup arranged in a back to back configuration enables to measure the positions and the energies of the b particle and the recoiling ion. This allows the full reconstruction of the decay kinematics and a proper event selection. During the first data taking at GANIL, up to 105 decay coincidences between the b particles and the recoiling ions were recorded, which corresponds to a statistical uncertainty of 2% on the correlation parameter. The detailed analysis of these data was performed using a realistic simulation of the experiment, which accounts for several factors like the phase space of the decaying ions, the RF field effect on the recoil motion and the characteristics of the detection setup. In this contribution, the uncertainties induced on abn by these main systematic effects will be discussed. During the last experiment, more than 2 x 106 coincident events were recorded, which should enable to achieve a 0.5 % statistical precision on the measurement of abn.
1 :  LPCC - Laboratoire de Physique Corpusculaire de Caen
2 :  GANIL - Grand Accélérateur National d'Ions Lourds
Interactions fondamentales
Physique/Physique Nucléaire Expérimentale