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

¹ Tulane University, New Orleans, LA 70118, USA
² Hamilton College, Clinton, NY 13323, USA
³ National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
⁴ DePauw University, Greencastle, IN 46135, USA
⁵ Indiana University, Bloomington, IN 47408, USA

^a e-mail: few@tulane.edu
^b e-mail: Current address: University of Washington, Seattle, WA, USA
^c e-mail: Current address: NIST, Gaithersburg, MD, USA
^d e-mail: Current address: Lawrence Livermore National Laboratory, Livermore, CA, USA

Published online: 12 December 2019

Abstract

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 obtained the result a = 0.1090 +/- 0.0030 (stat) +/- 0.0028 (sys), the most precise to date. The second run on the new NG-C high flux beam line promises an improvement in precision to ¡ 2%. In addition we show that an improved measurement of the neutrino asymmetry (B-coefficient) can be made using the aCORN apparatus on a highly polarized neutron beam.