The Spectrum of β Decay: Continuous or Discrete? A Variety of Errors in Experimental Investigation

Abstract

In this paper I will examine how the physics community came to accept the idea of a continuous energy spectrum of electrons emitted in β decay, the spontaneous transformation of an atomic nucleus into another atomic nucleus with the emission of an electron and a neutrino. In this history we shall see several different ways in which scientists went wrong. These include two instances of apparent disagreement between pairs of experimental results in which all of the results were, in fact, correct. One of each discordant pair of results had been misinterpreted. There will also be a case of an incorrect experimental result, which was an artifact produced by the experimental apparatus. It was an unsuccessful attempt to replicate this incorrect result, a discrete energy spectrum in β decay, that led to an experiment which, in retrospect, demonstrated the continuous energy spectrum. This experiment itself initially provided inconsistent results using different detectors. At the time of its publication, however, this experiment did not persuade physicists that the energy spectrum was continuous. I will examine some of the reasons for the lack of acceptance of this result and end my story with the experiment that ultimately resolved the issue. It persuaded the physics community that the energy spectrum in β decay was continuous. The process lasted approximately 30 years.