Recommended voltage divider
Type A for maximum gain
K D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 A
K: photocathode Dn: dynode A: anode
Anode luminous sensitivity :
Supply voltage :
Continuous anode current :
Voltage between :
D1 and photocathode :
consecutive dynodes :
anode and D10 :
Ambient temperature :
short operation (< 30 mn) :
continuous operation & storage : min.:
þ Characteristic measured and mentioned on the test ticket of each tube.
• Luminous sensitivity is measured with a tungsten filament lamp with a colour temperature of 2856 ± 5 K. The blue
sensitivity, expressed in A/lmF ("F" as in Filtered) is measured with a tungsten filament lamp with a colour
temperature of 2856 ± 5 K. Light is transmitted through an interference filter.
‚ Dark current is measured at ambient temperature, after the tube has been in darkness for approximately 1 min.
Lower value can be obtained after a longer stabilisation period in darkness (approx. 30 min.).
ƒ Pulse amplitude resolution for 137Cs is measured with a NaI(Tl) cylindrical scintillator with a diameter of 50 mm and a
height of 50 mm. The count rate used is about 104 cps.
„ The mean pulse amplitude deviation is measured by coupling a NaI(Tl) scintillator to the window of the tube. Long
term (16h) deviation is measured by placing a 137Cs source at a distance from the scintillator such that the count
rate is ~ 104 c/s, corresponding to an anode current of ~ 300 nA. The mean pulse amplitude deviation after change
of count rate is measured with a 137Cs source at a distance from the scintillator such that the count rate can be
changed from 104 to 103 c/s, corresponding to an anode current of ~ 1 µA and 0.1 µA respectively. Both tests are
carried out according to ANSI-N42-9-1972 of IEEE recommendations.
… To obtain a peak pulse current greater than that obtainable with divider A, it is necessary to increase the
inter-dynode voltage progressively. Divider circuit C is an example of a progressive divider, giving a compromise
between gain, speed and linearity. other dividers can be conceived to achieve other compromises. It is generally
recommended that the voltage ratio between two successive stages is less than 2.
† Measured with a pulse light source, with a pulse duration (FWHM) of approximately 1ns., the cathode being
completely illuminated. The rise time is determined between 10 % and 90 % of the anode pulse amplitude. The
signal transit time is measured between the instant at which the illuminating pulse of the cathode becomes
maximum, and the instant at which the anode pulse reaches its maximum. Rise time, pulse duration and transit time
vary with respect to high tension supply voltage Vht as (Vht)-½.