The goal of the FNAL E989 experiment is to measure the muon magnetic anomaly to unprecedented accuracy and precision at the Fermi National Accelerator Laboratory. To meet this goal, the time and space averaged magnetic environment in the muon storage volume must be known to better than 70 ppb. Anew pulsed proton nuclear magnetic resonance (NMR) magnetometer was designed and built at the University of Washington, Seattle to track the temporal stability of the 1.45 T magnetic field in the muon storage ring at this precision. It consists of an array of 378 petroleum jelly based NMR probes that are embedded in the walls of muon storage ring vacuum chambers and custom electronics built with readily available modular radio frequency (RF) components. We give NMR probe construction details and describe the functions of the custom electronic subsystems. The excellent performance metrics of the magnetometer are discussed, where after 8 years of operation the median single shot resolution of the array of probes remains at 650 ppb.

Neutron spin rotation is expected from quark-quark weak interactions in the standard model, which induce weak interactions among nucleons that violate parity. We present the results from an experiment searching for the effect of parity violation via the spin rotation of polarized neutrons in a liquid 4He medium. The value for the neutron spin rotation angle per unit length in 4He, d ϕ / d z = [ + 2.1 ± 8.3 (stat.) - 0.2 + 2.9 (sys.) ] × 10 - 7 rad/m, is consistent with zero. The result agrees with the best current theoretical estimates of the size of nucleon-nucleon weak amplitudes from other experiments and with the expectations from recent theoretical approaches to weak nucleon-nucleon interactions. In this paper we review the theoretical status of parity violation in the n → + 4He system and discuss details of the data analysis leading to the quoted result. Analysis tools are presented that quantify systematic uncertainties in this measurement and that are expected to be essential for future measurements.

The neutron spin rotation (NSR) collaboration used parity-violating spin rotation of transversely polarized neutrons transmitted through a 0.5 m liquid helium target to constrain weak coupling constants between nucleons. While consistent with theoretical expectation, the upper limit set by this measurement on the rotation angle is limited by statistical uncertainties. The NSR collaboration is preparing a new measurement to improve this statistically-limited result by about an order of magnitude. In addition to using the new high-flux NG-C beam at the NIST Center for Neutron Research, the apparatus was upgraded to take advantage of the larger-area and more divergent NG-C beam. Significant improvements are also being made to the cryogenic design. Details of these improvements and readiness of the upgraded apparatus are presented. We also comment on how recent theoretical work combining effective field theory techniques with the 1/Nc expansion of QCD along with previous NN weak measurements can be used to make a prediction for dϕ/dz in 4He. An experiment using the same apparatus with a room-temperature target was carried out at LANSCE to place limits on parity-conserving rotations from possible fifth-force interactions to complement previous studies. We sought this interaction using a slow neutron polarimeter that passed transversely polarized slow neutrons by unpolarized slabs of material arranged so that this interaction would tilt the plane of polarization and develop a component along the neutron momentum. The results of this measurement and its impact on the neutron-matter coupling gA2 from such an interaction are presented. The NSR collaboration is also preparing a new measurement that uses an upgraded version of the room-temperature target to be run on the NG-C beamline; and it is expected to constrain gA2 by at least two additional orders of magnitude for λc between 1 cm and 1 μm.

The Apache Point Observatory Lunar Laser-ranging Operation (APOLLO) has entered its tenth year of a steady observation campaign, primarily in pursuit of improved tests of gravitation. APOLLO achieves millimeter-level range precision, routinely ranges to all five reflectors on the Moon, and has seen strong evidence for degradation of reflector performance.

Polarized slow neutrons can be used to conduct sensitive searches for subtle spin-dependent neutron interactions in matter. A brief overview of the theoretical context in which such searches are important is given. We present the result of a recent measurement of neutron spin rotation in liquid helium that constrains possible exotic long-range parity-odd interactions between the neutron and matter from the exchange of spin 1 bosons of meV-scale masses. The experiment also places the first upper bound to our knowledge on what may be called “in-matter”gravitational torsion. Finally, we discuss a proposed search for a possible parity-even exotic interaction of polarized neutrons with matter from spin 1 boson exchange with axial couplings for boson masses in the meV range.

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.

In order to constrain weak coupling constants between nucleons, the Neutron Spin Rotation (NSR) collaboration has placed an experimental upper bound on the parity-violating spin rotation of transversely polarized neutrons transmitted through liquid helium. These measurements also place limits on the existence of possible long-range parity-odd forces [1]. Particular attention has been paid to reducing possible systematic errors below the statistical precision of the measurement. In addition, simulations of the beam transport and target interactions have been used to investigate systematic errors from small-angle scattering in the target and help plan the next generation experiment. The recent experiment performed on the NG6 neutron beam at the NIST Center for Neutron Research (NCNR) yielded a statisticallylimited rotation angle of dφ/dz = [+1.7 ± 9.1(stat.)± 1.4(sys.)] × 10−7 rad/m [2]. The NSR collaboration is currently upgrading the apparatus to accept the higher flux and increased phase-space of the new NGC beam at the NCNR.