## Screening and Relativistic Effects on Beta SpectraIn interpreting data on beta ray spectra, apparent deviations from the Fermi allowed form may be caused by neglect of the effect of screening by atomic electrons and by use of the nonrelativistic approximation to the Coulomb factor. The effect of the screening on the Coulomb factor h25 been calculated approximately for arbitrary Z, using a method based on the Thomas Fermi screened potential. The effect of screening is found to be an increase in the number of both positrons and electrons at low energies. Numerical results are given for S35, Cu64, and RaE. By use of a better approximation to the relativistic Coulomb correction factor, the error incurred by using the nonrelativistic form is estimated for various emitters. It is found that for sufficiently thin sources of Cu64 (for example) the neglect of the screening and relativistic effects contributes a considerable fraction of the apparent deviation from the Fermi theory. |

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accuracy accurate actual amplitude at infinity applied arbitrary assumed potential beta better approximation calculation cent constant Cook and Langer Coulomb correction factor Coulomb factor Coulomb potential Cu64 positrons decreases deviate from linearity deviations difference D(r direction discrepancy effect of screening electron and positron electron curve emitters equal error exactly expected experimental explain expression fact Fermi allowed Fermi plot Fermi theory Figure follows formula given gives higher energy increase increase the numbers interpreted Kurie plot low energies neglecting neglecting screening nonrelativistic approximation number of particles obtained origin positron curve positrons and electrons pure Coulomb field quantity radius rae spectrum rapidly ratio region relativistic corrections relativistic effects relativity correction rise screened potential screening and relativistic screening and relativity screening correction seems shifted potential shows sources spectra square straight line T-Kev Table taken term Thomas-Fermi unit various wave function WKB method