B. G. Yerozolimsky

Corrigendum: Corrected value of the beta-emission asymmetry in the decay of polarized neutrons measured in 1990

Abstract A correction is noted to a previously published value of the asymmetry coefficient in the beta decay of polarized neutrons.

Free neutron decay: a review of the contemporary situation

Abstract Experimental data on neutron decay parameters are reviewed. These are the neutron lifetime and various angular correlations between spin and momenta of the particles involved in neutron decay. The restrictions on scalar and tensor terms in the weak Hamiltonian, as well as possible admixtures by V + A currents, resulting from neutron decay experiments, are discussed. Reasonable agreement with the predictions of the V − A theory can be certified.

Experimental value of GA/GV from a measurement of both P-odd correlations in free-neutron decay

A new experimental value of the fundamental weak-interaction parameter λ=GA/GV (−1.2686±0.0046) is obtained for the first time by an original method that consists in measuring both P-odd correlations in free-neutron decay.

Problems of precise neutron beam polarization measurements

Abstract A detailed analysis of current methods of neutron beam polarization is presented and the main problems which are seen on the way of reaching the level of accuracy of 0.1% are discussed. A recently developed approach based on the use of the Stern–Gerlach effect suitable for investigating of large cross sections of neutron beams is described.

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

We describe an apparatus used to measure the electron-antineutrino angular correlation coefficient in free neutron decay. The apparatus employs a novel measurement technique in which the angular correlation is converted into a proton time-of-flight asymmetry that is counted directly, avoiding the need for proton spectroscopy. Details of the method, apparatus, detectors, data acquisition, and data reduction scheme are presented, along with a discussion of the important systematic effects.

Estimation of scalar and tensor weak-interaction constants on the basis of recent neutron experimental data

The contributions of scalar and tensor interactions associated with right-handed neutrinos to the effective hadron-lepton Hamiltonian are estimated on the basis of modern measurements of the neutron lifetime and correlations in the beta decay of a free neutron.

An experiment to measure λ=GA/GV from a combination of angular correlation coefficients in the beta decay of polarized neutrons

Abstract A technique is described which allows us to measure the ratio λ = G A / G V of the weak axial-vector and vector coupling constants in neutron decay without any measurement of the neutron beam polarization. λ is determined from a combination of the parity-odd angular correlations σ → · p → e and σ → · p → ν between the neutron spin σ → and the electron momentum p → e and the anti-neutrino momentum p → ν , respectively, both of which are measured in a single experiment using the same neutron beam. A description of the experiment and the results of the first run at the cold neutron beam facility at the Institut Laue–Langevin are presented.

Proposed Measurement of the Beta-Neutrino Correlation in Neutron Decay

Currently, the beta-neutrino asymmetry has the largest uncertainty (4 %) of the neutron decay angular correlations. Without requiring polarimetry this decay parameter can be used to measure λ (ga/gv), test Cabibbo-Kobayashi-Maskawa (CKM) unitarity limit scalar and tensor currents, and search for Charged Vector Current (CVC) violation. We propose to measure the beta-neutrino asymmetry coeffcient, a, using time-of-flight for the recoil protons. We hope to achieve a systematic uncertainty of σa / a ≈ 1.0 %. After tests at Indiana University’s Low Energy Neutron Source (LENS), the apparatus will be moved to the National Institute of Standards and Technology (NIST) where the measurement can achieve a statistical uncertainty of 1 % to 2 % in about 200 beam days.