We report an upper bound on parity-violating neutron spin rotation in 4 He. This experiment is the most sensitive search for neutron-weak optical activity yet performed and represents a significant advance in precision in comparison to past measurements in heavy nuclei. The experiment was performed at the NG-6 slow-neutron beamline at the National Institute of Standards and Technology (NIST) Center for Neutron Research. Our result for the neutron spin rotation angle per unit length in 4 He is dφ/dz = [+1.7 ± 9.1(stat.) ± 1.4(sys.)] × 10 −7 rad/m. The statistical uncertainty is smaller than current estimates of the range of possible values of dφ/dz in n+ 4 He.
We present the design, description, calibration procedure, and an analysis of systematic effects for an apparatus designed to measure the rotation of the plane of polarization of a transversely polarized slow neutron beam as it passes through unpolarized matter. This device is the neutron optical equivalent of a crossed polarizer/analyzer pair familiar from light optics. This apparatus has been used to search for parity violation in the interaction of polarized slow neutrons in matter. Given the brightness of existing slow neutron sources, this apparatus is capable of measuring a neutron rotary power of dϕ/dz = 1 × 10(-7) rad/m.
We propose to perform the first measurement of the neutron–neutron scattering cross section in the through-channel of the pulsed aperiodic reactor YAGUAR (Snezhinsk, Russia). Such a measurement directly determines the neutron–neutron scattering length, and by comparison with the proton–proton scattering length bears upon the issue of charge symmetry of the nuclear force. The proposed experimental set-up, as well as modelling of the neutron density and of the frequency of neutron–neutron collisions is described. Experimental results are reported on the formation and optimization of the thermal neutron field inside the through-channel of the reactor YAGUAR. The instantaneous value of 1.1 × 1018 cm−2 s−1 obtained for the thermal neutron flux density is large enough to perform the first direct neutron–neutron scattering length measurement.
We present a search for possible spin dependent interactions of the neutron with matter through exchange of spin 1 bosons with axial vector couplings as envisioned in possible extensions of the Standard Model. This was sought using a slow neutron polarimeter that passed transversely polarized slow neutrons by unpolarized slabs of material arranged so that interactions would tilt the plane of polarization and develop a component along the neutron momentum. The result for the rotation angle, φ = [2.8 ± 4.6(stat.) ± 4.0(sys.)] × 10 −5 rad/m is consistent with zero. This result improves the upper bounds on the neutron-matter coupling g 2 A by about three orders of magnitude for force ranges in the mm -µm regime.in the 1 meV to 1 eV range and with very weak couplings to matter has begun to attract renewed scientific attention. Particles which might act as the mediators are sometimes referred to generically as WISPs (Weakly-Interacting sub-eV Particles) [1,2] in recent theoretical literature. Many theories beyond the Standard Model, including string theories, possess extended symmetries which, when broken at a high energy scale, lead to weakly-coupled light
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.