Neutron interferometric measurement of the scattering length difference between the triplet and singlet states of n-${}^3$He

Abstract

We report a determination of the n-${}^3$He scattering length difference $\Delta b^{\prime }=b_1^{\prime }-b_0^{\prime }=$ ($-5.411$ $\pm$ $0.031$ (statistical) $\pm$ $0.039$ (systematic)) fm between the triplet and singlet states using a neutron interferometer. This revises our previous result $\Delta b^{\prime }=$ (-5.610 $\pm$ $0.027$ (statistical) $\pm$ $0.032$ (systematic) fm obtained using the same technique in 2008. This revision is due to a re-analysis of the 2008 experiment that includes a more robust treatment of the phase shift caused by magnetic field gradients near the ${}^3$He cell. Furthermore, we more than doubled our original data set from 2008 by acquiring six months of additional data in 2013. Both the new data set and a re-analysis of the older data are in good agreement. Scattering lengths of low Z isotopes are valued for use in few-body nuclear effective field theories, provide important tests of modern nuclear potential models and in the case of ${}^3$He aid in the interpretation of neutron scattering from quantum liquids. The difference $\Delta b^{\prime }$ was determined by measuring the relative phase shift between two incident neutron polarizations caused by the spin-dependent interaction with a polarized ${}^3$He target. The target ${}^3$He gas was sealed inside a small, flat windowed glass cell that was placed in one beam path of the interferometer. The relaxation of ${}^3$He polarization was monitored continuously with neutron transmission measurements. The neutron polarization and spin flipper efficiency were determined separately using ${}^3$He analyzers and two different polarimetry analysis methods. A summary of the measured scattering lengths for n-${}^3$He with a comparison to nucleon interaction models is given.

References in corpus (4)

• Nucleon and nucleon-pair momentum distributions in A <= 12 nuclei
• Low energy $n-\nuc{3}{H}$ scattering : a novel testground for nuclear interaction
• Precision Measurement of the n-3He Incoherent Scattering Length Using Neutron Interferometry
• Neutron interferometric measurement of the scattering length difference between the triplet and singlet states of n-${}^3$He

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• Development of Neutron Interferometer using Multilayer Mirrors and Measurements of Neutron-Nuclear Scattering Length with Pulsed Neutron Source
• Measurement of the total neutron scattering cross section ratios of noble gases of natural isotopic composition using a pulsed neutron beam
• Dissipative Superfluidity in a Molecular Bose-Einstein Condensate
• Fundamental Neutron Physics: a White Paper on Progress and Prospects in the US