We describe an experimental search for deviations from the inverse square law of gravity at the nanometer length scale using neutron scattering from noble gases on a pulsed slow neutron beamline. By measuring the neutron momentum transfer (q) dependence of the differential cross section for xenon and helium and comparing to their well-known analytical forms, we place an upper bound on the strength of a new interaction as a function of interaction length λ which improves upon previous results in the region λ < 0.1 nm, and remains competitive in the larger λ region. A pseudoexperimental simulation developed for this experiment and its role in the data analysis described. We conclude with plans for improving sensitivity in the larger λ region.

We are searching for an unknown force that could couple to mass using neutron scattering from a noble gas. The neutron is a chargeless massive particle with a long lifetime, which consequently is suitable for the precision measurement of a small interaction with a range of the order of 1 nm by measurements of the momentum transfer distribution. We measured neutron scattering at the low-divergence beam branch on the BL05 NOP beamline in the Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC). We measured 10 5 scattering events and report our most recent analysis.

Precision measurements of slow neutron cross sections with atoms have several scientific applications. In particular the n-4 He s-wave scattering length is important to know both for helping to constrain the nuclear three-body interaction and for the proper interpretation of several ongoing slow neutron experiments searching for other types of neutron-atom interactions. We present new measurements of the ratios of the neutron differential scattering cross sections for natural isotopicabundance mixtures of the noble gases He, Ar, Kr, and Xe to natural isotopic abundance Ne.These measurements were performed using a recently developed neutron scattering apparatus for gas samples located on a pulsed slow neutron beamline which was designed to search for possible exotic neutron-atom interactions and employs both neutron time of flight information and a position -sensitive neutron detector for scattering event reconstruction. We found agreement with the literature values of scattering cross sections inferred from Ar/Ne, Kr/Ne and Xe/Ne differential cross section ratios over the q range of 1 − 7 nm −1 . However for the case of He/Ne we find that the cross section inferred differs by 11.3% (7.6 σ) from previously-reported values inferred from neutron phase shift measurements, but is in reasonable agreement with values from other measurements.The very large discrepancy in the He/Ne ratio calls for a new precision measurement of the n-4 He scattering length using neutron interferometry.

We are searching for a possible deviation from Newtonian gravity at the nm length scale using neutron scattering techniques. The neutron is a chargeless and massive particle thereby lending itself to use as a probe for weakly coupled interactions at length scales of ∼1 nm that would otherwise be masked by electromagnetic effects. By analyzing the q-dependence of the intensity distribution of scattered neutrons, we can place an upper limit on the size of such a new interaction. We performed a neutron experiment for this purpose at the low-divergence beam branch on the BL05 NOP beamline in the Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC). We report our recent analysis efforts.

We are searching for an unknown force that could couple to mass using neutron scattering from a noble gas. The neutron is a chargeless massive particle with a long lifetime, which consequently is suitable for the precise measurement of a small interaction with a range of the order of 1nm by measurements of the momentum transfer distribution. We measured neutron scattering at the low-divergence beam branch on the BL05 NOP beamline in the Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC). We report recent experimental data.