Spin Manipulation by Use of Nuclear Quadrupole Interactions – Quarks and Medium Effects in the Nucleus

Abstract

The alignment correlation terms in the β-ray angular distributions from the purely spin aligned mirror pair 12B(Iπ= 1+ T1/2 = 20.2ms) and 12N(Iπ = 1+,T1/2 = 11.0ms)were precisely measured to place a new limit on the G-parity conservation law. For the creation of the alignment, the spin manipulation technique was applied, which utilized the nuclear quadrupole interactions. The - parity violating induced tensor coefficient was determined to be 2MfT/fa = -0,15 ± 0,12 ± 0,05 (theor.), which is consistent with the theoretical prediction based on QCD in which 2MfT/fA is proportional to the mass difference between up and down quarks which constitute the nucleon. Also determined the axial charge to be y= 4,90±0,10 (90% CL). From the result, we have found that the nucleon mass inside the nucleus is reduced (16 4)% relative to the free nucleon mass