aCORN: An experiment to measure the electron-antineutrino correlation coefficient in free neutron decay

Collett, B.; Bateman, Fred; Bauder, W.; Byrne, J.; Byron, W. A.; Chen, Wangchun; Darius, G.; DeAngelis, C.; Dewey, M. S.; Gentile, Thomas R.; Hassan, Md. T.; Jones, G. L.; Komives, A.; Laptev, A.; Mendenhall, M. P.; Nico, J. S.; Noid, G.; Park, H.; Stephenson, E. J.; Stern, I.; Stockton, K. J. S.; Trull, C.; Wietfeldt, F. E.; Yerozolimsky, B. G.

doi:10.1063/1.4996542

Cited by 6 publications

(3 citation statements)

References 19 publications

(15 reference statements)

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“…Our result from the NG-6 run is a = −0.1090 ± 0.0030(stat) ± 0.0028(sys). Additional details on the design, construction, alignment, and calibration of the aCORN apparatus and individual components, and analysis of systematic effects, can be found in previous publications [15,19,18,20].…”

Section: Experiments and Resultsmentioning

confidence: 99%

aCORN: Measuring the electron-antineutrino correlation in neutron beta decay

et al. 2019

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The aCORN experiment uses a novel asymmetry method to measure the electron-antineutrino correlation (a-coefficient) in free neutron decay that does not require precision proton spectroscopy. aCORN completed two physics runs at the NIST Center for Neutron Research. The first run on the NG-6 beam line in 2013-2014 obtained the result a = 0.1090 +/-0.0030 (stat) +/-0.0028 (sys), a total uncertainty of 3.8%. The second run on the new NG-C high flux beam line promises an improvement in precision to < 2%.PRESENTED AT CIPANP2018 1 current address:

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Section: Experiments and Resultsmentioning

confidence: 99%

aCORN: Measuring the electron-antineutrino correlation in neutron beta decay

et al. 2019

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“…In the most recent experiments proton loss by scattering or absorption was evaluated using the Monte Carlo computer code SRIM [21]. Proton loss using a 600 mm 2 , 1000 μm thick depletion layer surface barrier detector has also been studied in detail in the aCORN project to measure the electron-antineutrino angular correlation coefficient 'a' [22]. The Nab project, designed to measure both 'a' and the Fierz interference term 'b' for neutron decay, proposes to detect protons using a segmented silicon detector [23].…”

Section: Measuring the Neutron Lifetimementioning

confidence: 99%

The neutron lifetime anomaly and charge exchange collisions of trapped protons

Byrne

Worcester

2019

J. Phys. G: Nucl. Part. Phys.

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Measurements of the neutron lifetime have improved dramatically in accuracy in recent decades and provide data of crucial significance to particle physics and cosmology. Although experimental results with standard deviations of order 0.1% have been claimed, nevertheless the two main measurement techniques, the beam method and the bottle method, give results that differ by about 1% or four standard deviations. This troubling discrepancy could either be a hint of new physics, or of unidentified event losses in the two different types of particle trap that have been employed. A possible source of proton losses in the beam method arises from charge exchange collisions between residual gas molecules and protons stored in a quasi-Penning trap. Using published charge exchange cross sections, evaluations were made of the effectiveness of a number of gases commonly present as residual gas in high vacuum systems for bringing about proton loss. It is demonstrated that in many cases, these losses are significant for neutron lifetime measurements in vacua down to 10−11 mm Hg when 0.1% accuracy in the neutron lifetime is sought. Methods to correct for charge exchange losses are proposed.

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“…The "a Correlation in Neutron Decay" (aCORN) experiment measured the beta decay coefficient a, which characterizes the angular correlation between the electron and electron-antineutrino momenta following neutron beta decay. [1,2] The experiment used a vertically oriented magnetic field to direct the beta electrons to a backscatter-suppressed spectrometer [3] and protons to a biased surface barrier detector. [4] The experiment only detects electrons in one direction, so it is very sensitive to the spin polarization of the neutrons via the neutrino asymmetry coefficient.…”

Section: Introductionmentioning

confidence: 99%

Neutron Polarimetry Using a Polarized 3He Cell for the aCORN Experiment

Schafer,

Byron,

Chen

et al. 2020

Preprint

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The neutron polarization of the NG-C beamline at the NIST Center for Neutron Research was measured as part of the aCORN neutron beta decay experiment. Neutron transmission through a polarized 3 He spin filter cell was recorded while adiabatic fast passage (AFP) nuclear magnetic resonance (NMR) reversed the polarization direction of the 3 He in an eight-step sequence to account for drifts. The dependence of the neutron transmission on the spin filter direction was used to calculate the neutron polarization. The time dependent transmission was fit to a model which included the neutron spectrum, and 3 He polarization losses from spin relaxation and AFP-NMR. The polarization of the NG-C beamline was found to be |P n | ≤ 4 × 10 −4 with 90 % confidence.

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aCORN: An experiment to measure the electron-antineutrino correlation coefficient in free neutron decay

Cited by 6 publications

References 19 publications

aCORN: Measuring the electron-antineutrino correlation in neutron beta decay

aCORN: Measuring the electron-antineutrino correlation in neutron beta decay

The neutron lifetime anomaly and charge exchange collisions of trapped protons

Neutron Polarimetry Using a Polarized 3He Cell for the aCORN Experiment

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