Pseudomagnetic effects for resonance neutrons

Abstract

A general theory of pseudomagnetic effects on the propagation of polarized neutrons through a polarized target using multi-resonance approach is presented. Some applications related to proposed searches for time reversal invariance violation in neutron scattering are considered.

Nuclear spin dependence of time reversal invariance violating effects in neutron scattering

“…They cannot be calculated due to a complex structure of compound resonances, therefore, they can be obtained only from experiments which are sensitive to the values and signs of amplitudes of neutron widths. For example, as was mentioned above, they can be obtain from angular distributions of γ rays in resonance neutron radiative capture reactions or by measuring of pseudomagnetic neutron spin rotation in the vicinity of p-wave resonances [15].…”

Neutron spin dynamics in polarized targets

“…Therefore, the smaller value means better sensitivity for spin related observables (TRIV effect, in particular). The largest part of b come from b 3 component, which can be reduced by adjusting external magnetic field (see [14] and references therein). The second large part comes from b 2 , which also can be reduced by adjusting the value of the second rank of the parget polarization P 2 .…”

“…[5] and references therein) demonstrated the existence of a class of experiments that are free from false asymmetries, to design the experiment and to control the possible systematic effects one has to have a detailed description of neutron spin dynamics in targets with arbitrary polarization. The propagation of polarized neutrons through polarized target in relation to TRIV experiments have been studied in many papers (see, for example [5,[9][10][11][12][13][14] and references therein), however these studies have been done with the focus on the case of vector polarized target. However, even for 100% vector polarized target with spin I > 1/2, the higher rank tensor polarizations may coexist and to be rather large.…”

Polarized Lanthanum Target for the T-violation Search in Slow Neutron Transmission

“…In experimental configuration sensitive to the P-odd and T-odd asymmetry, a spin rotation of the incident neutron is unavoidable because of a pseudomagnetic field induced by the polarized nuclei [6]. The field strength in the LaAlO 3 crystal is estimated to be roughly less than 0.2 T [7,8]. If we apply the external magnetic field as low as the psudomagnetic field, it is expected to cancel out the effect of the psudomagnetic rotation.…”