On the Collision of α particles with Hydrogen Atoms.

The chapter gives an account of some experiments on the collision of α particles with hydrogen atoms, using the scintillation method. With the microscope used at that time the counting of scintillations was a difficult and trying experience, but during the last year by the use of holoscopic lenses of large aperture and suitable eyepieces, recently constructed in this country, it has been found possible to improve greatly the ease and certainty of counting such weak scintillations. The accurate determination of the relation between the number and angle of ejection of the H atoms for different speeds of the α particles is of great importance in order to throw light on the nature and distribution of the forces. The relation between the number of H atoms shot out at different angles with the primary beam of α rays for different velocities of the particle is under direct examination by Mr. Chadwick and Mr. Bieler using the scintillation method.