| Abstract: | Uniform P-47 powder scintillators can be prepared with reproducible mass thicknesses by sedimenting the powder in an 0·01% solution of formvar in chloroform. A reflecting coating can be glued by floating a 60 nm aluminium film on the scintillation layer in an 0·1% solution of gelatine in water. The optimum thickness of P-47 for 20–100 keV electrons increases slower than the electron range due to the absorption and scattering of light with increasing thickness. An aluminium coating increases the light output by a factor 1·85 for 20 keV and 1·4 for 100 keV electrons. The noise of the emitted light quanta and the photomultiplier detection system shows a minimum for the optimum thickness of largest light output and is only a factor 1·3–1·6 larger than the calculated shot noise of the incident electron beam. |
