A concept of experimental study of physical properties of entangled electron spin states (enton quasiparticles) in a solid has been suggested in this paper. In order to conduct such investigations we designed the experimental setup and created spin electron detectors of the next generation. The previous types of detectors didn’t meet all our requirements. The two Mott detectors simultaneously measured spin polarization of electrons during test measurements. The results show that Bell inequalities are satisfied in a traditional measurement mode without temporal pulse coincidence that corresponds to measurement mode of particles not being in the entangled state. The usage of pulse coincidence mode will allow establishing the fact of the Bell’s inequalities violation and will proof the existence of entangled electron spin states in a solid. Further measurements at different pulse durations in the pulse coincidence mode and also measurements at different energies and incidence angles will allow determining the lifetime, energy and dispersion of entangled states in a solid.