Measurement of P-odd asymmetry of γ-quanta emission in the nuclear reaction 10B(n,α)7Li* → γ+ 7Li(g.s.)

We present results of measurement of the P-odd asymmetry alpha(P-odd) of gamma-quanta emission in the nuclear reaction B-10(n,alpha)Li-7*->gamma+Li-7(g.s.) with polarized cold neutrons. The experiment was carried out using a new version of the integral measuring method. The frequency of neutron spin-flip is higher in this method than the typical reactor power noise frequency; this condition decreases experimental uncertainties. The result is alpha(10B)(p-odd) = +(0.8 +/- 3.9) x 10(-8); "zero" experiments are taken into account. Using this value, we constrain the weak neutral current constant in the framework of the cluster model to f(pi)(10B)<= 2.4 x 10(-7) (at 90% c.l.). This constraint does not contradict the estimation obtained from the nuclear reaction Li-6(n,alpha)H-3:f(pi)(6Li) <= 1.1 x 10(-7) (at 90% c.l.). However, both these constraints contradict the "best" value of the Quark model by Desplanques, Donoughe, and Holstein f.DDH = 4.6 x 10(-7). (C) 2009 Elsevier B.V. All rights reserved.