Département de Physique Nucléaire

Institut de recherche sur les lois fondamentales de l'Univers

The physics motivations of this experiment are similar to those of HAPPEx2. Experimentally the only difference is the use of a Helium 4 target which gives us a complementary sensitivity to the weak form factors of the nucleon. Indeed the spin 0 nature of Helium 4 nucleus prevents from a magnetic coupling with the electron beam and gives rise to a pure electric contribution in the cross section. The corresponding strange matrix element is thus parametrized by the electric strange form factor only, G_E^s(Q2).

With its low Q2 kinematics (0.1 GeV2), the Helium4 experiment access to the first non zero moment of the electric strange form factor: the strange radius.

Proposal (psorpdf).