Measurement of the parity-violating asymmetry in the reactions of cold polarized neutrons and light nuclei ~6Li, ~(10)B

摘要

We present two measurements of parity-violating secondary particle emission asymmetry in the reactions of polarized cold neutrons and light nuclei. We aim at studies of the neutral weak currents in nucleon-nucleon interaction. First, we describe the triton emission asymmetry in the ~6Li(n, a)~3H reaction. It is equal to α_(P zodd)~(6Li) = _(8.8 ± 2.1) _ 10~(-8). Second, we present the γ-rays emission asymmetry in the nuclear reaction ~(10)B(n, a)~7 Li~* γ→~7 Li(g.s.). The result is a_(P-odd)~(10B) = +(0.8 ± 3.9) .10~(-8). Using these values, we constrain the weak neutral current constant in framework of the cluster model f_π~(6Li) ≤ 1.1 _ 10~(-7) and f_π~(10B)≤2.4 _ 10~(-7) (at 90% c.l.). Both these constrains contradict to "the best" DDH value of f_π~(DDH)= 4.6 _ 10~(-7).