Configuration for scanning drift tube apparatus: Time-of-flight (TOF) experiment; ultraviolet laser light pulse (1.7 µJ, 5 ns) triggered electron generation on Mg disk used as photoemitter; Mg disk placed at the centre of a stainless steel electrode with 105 mm diameter serving as cathode; detector consisting of a grounded nickel mesh and stainless steel electrode 1 mm behind it; drift length between 7.8 to 58.3 mm; reduced electric field range (E/N) between 1 and 1790 Td