Comments on measurements of W-values in tissue-equivalent gas for alpha particles

The author reviews measurements of W-values in tissue-equivalent gas for alpha particles, and considers discrepancies and possible sources of error. He concludes that methods of measuring W which involve the passage of the alpha particles through an absorber and hence the creation of an unknown number of low-energy particles are unsuitable for giving universally consistent results. It is suggested that some form of track segment technique to give values of w should be developed; a highly refined version of the cloud chamber approach is also suggested, but it is urged that at least one other, completely independent, method would appear to be highly desirable. (UK)