1 2 0 D O C U M E N T 1 2 5 S E P T E M B E R 1 9 2 3
The arrangement
The execution proceeded thus:
1) Checking of electroscope for isolation. (It was always charged with an ebonite
rod up to graduation mark 20.) After 12 hrs it rises very well to graduation mark 18.
2) Checking to what extent the hard radiation that still diffusely penetrates
through the lead screen P unloads the electroscope: The tube would be switched on
(1½ milliamperes at about 60 kilovolts, the Rh excitation potential is 19 kilovolts),
the electroscope is charged to 20 and the drop is observed; from many trials, there
a drop of 0.0004 scale graduations per second; hence very small. For this exper-
iment, the lead slit S was obstructed by thick lead. Now it was opened, in order
3) to check how quickly the secondary radiation on the slit edges and in the air
in front of the electroscope discharges the electroscope. The secondary radiator
wasn’t there yet. This scattering Z (dependent on the angle formed between the ion-
ization chamber and the primary beam) was, in the two extreme cases:
ionization-chamber beam = 90° Z1 = 0,001 scale graduations per sec
ionization-chamber beam = 15° Z2 = 0,028 scale graduations per sec
Both figures are each averages of 6 trials; the measured times are distributed,
e.g., thus: 10′35″, 10′20″, 10′48″, 10′24″, 11′0″,10′31″.
4) Then the secondary radiator was put into the beam path at the 90° position
and measured alternately without molybdenum foil and with molybdenum foil
(d = 0.04 mm); thus resulted:
Without foil 0.050 scale graduations per sec Z1 = 0.049
With foil 0.015 -”- Z2 = 0.014
The measured times were: Without foil With foil
1′20″ 4′38″
1′25″ 4′33″
1′25″ 4′41″
1′16″ 4′25″
Previous Page Next Page