New experiment on the neutron radiative decay

TL;DR

This paper discusses the development of a new experiment aimed at precisely measuring the radiative decay branch of neutrons, building on previous experiments that suggested a possible deviation from theoretical predictions.

Contribution

The paper introduces a new experimental setup designed to measure the radiative neutron decay with 1% precision, improving upon previous measurements.

Findings

Previous experiments set upper limits and observed decay events.

Measured B.R. was approximately twice the theoretical value.

New experiment aims to confirm or refute deviation from the standard model.

Abstract

The report is dedicated to the preparation of the new experiment on the neutron radiative decay what is conducted for the last years. We started the experimental research of this neutron decay branch with the experiment conducted at ILL in 2002 and continued in another experiment at the second and third cycles at the FRMII reactor of the Technical University of Munich in 2005. In the first experiment we succeeded in measuring only the upper limit on the relative intensity (B.R.) of the radiative neutron decay and in the second we succeeded in discovering events of radiative neutron decay and measure its B.R.=(3.2+-1.6)10-3 (with C.L.=99.7% and gamma quanta energy over 35 keV). The obtained average B.R. value was approximately twice the theoretical value calculated earlier within the framework of the standard electroweak model. However, due to significant experimental error it would be preliminary to deduce that based on this finding a deviation from the standard model has been observed. To prove or disprove the existence of a deviation it is necessary to conduct a new experiment that would allow to measure the radiative peak in timing spectra with precision in the order of 1%. By the present time we have prepared a new experiment the main result of which would be the measurement of B.R. for the radiative branch of neutron decay with this precision.