Theory of a High Dispersion Double Focusing Beta-Ray Spectrometer

A ``flat'' high dispersion double focusing beta‐ray spectrometer is proposed and results of computations are presented. The high dispersion is achieved by making the electrons orbit around the field axis more than once. The source and detector are displaced radially, in opposite directions, from the stationary circular orbit. A suitable baffle is mounted between the source and detector to shield the detector against unwanted electrons. The electron‐optical properties are almost the same as for the $\pi \sqrt{2}$ spectrometer except that the dispersion is increased. Numerical results are presented for two instruments with focusing angles of 565.88° and 909.02°, with respective dispersions of 21.5 and 50.6, to be compared with a dispersion of 4 for the $\pi \sqrt{2}$ spectrometer.