Parity violation in neutron spin rotation

Snow, W. M.

doi:10.1016/j.nima.2009.07.056

Cited by 8 publications

(4 citation statements)

References 45 publications

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“…Ideally, the resulting asymmetry in the count rates given by Eq. (20) isolates the component of the rotated neutron spin in the plane normal to the neutron momentum. The PA product of the polarizing power of the polarizer and the analyzing power of the analyzer is related as usual to the measured asymmetries by Eqs.…”

Section: B Polarizer-analyzer Product Measurementmentioning

confidence: 99%

“…12 Experiments to measure parity-odd spin rotation on resonances in atomic 13 and nuclear systems, including neutron spin rotation of epithermal neutrons passing through nuclear targets possessing compound nuclear resonances, [14][15][16][17] have also been described in the literature. Brief descriptions of the experimental technique and apparatus to measure slow neutron spin rotation have appeared 5, [18][19][20] and an extensive discussion of an earlier version of this apparatus appears in a Ph.D. thesis, 21 but to our knowledge, a full description of an apparatus to measure parity-odd neutron rotary power with high sensitivity using slow neutrons has not appeared before in the scientific literature.…”

Section: Introductionmentioning

confidence: 99%

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A slow neutron polarimeter for the measurement of parity-odd neutron rotary power

Snow

Anderson

Barrón‐Palos

et al. 2015

Review of Scientific Instruments

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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.

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Section: B Polarizer-analyzer Product Measurementmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A slow neutron polarimeter for the measurement of parity-odd neutron rotary power

Snow

Anderson

Barrón‐Palos

et al. 2015

Review of Scientific Instruments

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“…Experimental technique and measurement. The experimental technique has been presented in [37,38] and only an overview is given here. The apparatus shown in Fig.…”

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confidence: 99%

Upper bound on parity-violating neutron spin rotation inHe4

Snow

Bass

et al. 2011

Phys. Rev. C

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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.

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“…Measuring a very small spin-rotation angle of 10 −7 rad/m is very challenging and requires an apparatus that distinguishes the small parity-violating rotations from rotations that arise from residual magnetic fields. The apparatus consists of an upgraded version of that used in the previous NSR measurement [40][41][42]. The old apparatus consisted of a neutron supermirror polarizer, an adiabatic RF spin-flipper, nonmagnetic neutron guides, spin transport, an adiabatic spin rotator, a neutron supermirror polarization analyzer, and a current-mode ion chamber [41,42].…”

Section: Methodsmentioning

confidence: 99%

Neutron spin rotation measurements

et al. 2019

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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.

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Parity violation in neutron spin rotation

Cited by 8 publications

References 45 publications

A slow neutron polarimeter for the measurement of parity-odd neutron rotary power

A slow neutron polarimeter for the measurement of parity-odd neutron rotary power

Upper bound on parity-violating neutron spin rotation inHe4

Neutron spin rotation measurements

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