1,

In accordance with the Absolute Maximum rating system as defined

by the Electronic Industries Association Standard RS-239A, formu-

lated by the JEDEC Electron Tube Council.

2.

This value is the average over any 30 second interval.

3.

This value is calculated from the typical anode luminous responsiv-

ity value using a conversion factor of 857 lumens per watt.

4.

Under the following conditions: Light source is a tungsten-filament

lamp operated at a color temperature of 2856 K. The value of light

flux incident on the cathode is 10

5.

This value is calculated from the typical cathode luminous respon-

sivity value using a conversion factor of 857 lumens per watt.

6.

Under the following conditions: Light source is a tungsten-filament

lamp operated at a color temperature of 2856 K. The value of light

flux incident on the cathode is 10

between cathode and all other electrodes connected as anode.

7. Under the following conditions: Light incident on the cathode is

transmitted through a blue filter (Corning C.S. 5-58, polished to 1/2

stock thickness) from a tungsten-filament lamp operated at a color

temperature of 2856 K. The light flux incident on the filter is 10

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lumen; 200 volts are applied between cathode and all other elec-

trodes connected as anode.

8. The light flux incident on the cathode is 10

voltage E is adjusted to obtain an anode responsivity of 20 amperes

per lumen. Dark current is then measured with no light incident on

the tube.

9.

Equivalent Anode Dark Current Input (EADCI) is defined as the input

flux in lumens or watts at a specific wavelength which results in an

increase in the anode current of the photomultiplier tube just equal

to the anode dark current. EADCI in watts is calculated from the

EADCI value in lumens using a conversion factor of 857 lumens per

watt.

10. Calculated from typical values using the following formula:

11. Using a delta function light pulse of approximately one nanosecond

duration, anode-pulse rise time is measured between 10% and 90%

of the maximum anode pulse height. During the measurement the

incident light fully illuminated the photocathode.

12. The electron transit time is the time interval between the arrival of a

delta function light pulse at the entrance window of the tube and the

time at which the output pulse at the anode terminal reaches peak

amplitude. The transit time is measured under conditions with the

incident light fully illuminating the photocathode.

13. Tested with a supply voltage of 700 volts and a

source of sufficient intensity to produce approximately 10,000 cps

under the photopeakfrom the photomultiplier tube under test when

positioned on the backside of a 1-1/2” diameter by 1-1/2” high

Nal(TI) scintillator (BURLE 1501 or equivalent).

The faceplate end of the scintillator shall be optically coupled to the

faceplate of the PMT with mineral oil. The

centered with respect to the scintillator which, in turn, shall be

centered on the faceplate of the PMT. The anode of the PMT under

test is connected to a shunt RC network whose time constant is

10 ± 2 microseconds, a scintillation-counter preamplifier (Nuclear

Data Model 520, or equivalent), and a multichannel analyzer (Nu-

clear Data Model 100, or equivalent). Pulse-height resolution is

defined as the fractional full-width half-maximum of the 0.662 MeV

photopeak. Pulse height is defined as the signal in millivolts devel-

oped by the photopeak across a 290 ± 10 pF capacitor in the anode

circuit shunt RC network. See Figure 8 for test circuit utilized.

Operating Considerations

Average Anode Current

The operating stability of the tube is dependent on the magnitude

of the average anode current. The use of an average anode

current well below the maximum rated value of 0.50 milliampere

is recommended when stability of operation is important. When

maximum stability is required, the average anode current should

not exceed 1 microampere.

Peak Anode Current

By adjusting the voltage division ratios of the standard recom-

mended voltage divider, improved linearity can be obtained for

high peak anode currents. A strongly tapered divider, e.g. 2,1, 1,

1, 1, 1, 1,1.5,2.0,3.0,4.0 is suggested when high peak currents

are anticipated.

Operating Voltages

In general, the operating potential between anode and cathode

should not be less than 500 volts. The operating voltages can be

supplied by a voltage divider network applied across a regulated

dc power supply. A typical voltage-divider arrangement is shown

in Figure 7. The choice of resistance values for the voltage-divider

string is usually a compromise. If low values of resistance per

stage are utilized, the power drawn from the supply and the

required wattage rating of the resistors increase. Photomultiplier

noise may also increase, due to heating, if the divider network is

mounted near the tube. The use of high values of resistance per

stage may cause deviation from linearity if the voltage-divider

current is not maintained at a value of at least 10 times that of the

maximum average anode current and may limit current response

to pulsed light.

When the ratio of peak anode current to average anode current is

high, non-inductive capacitors should be employed across the

latter stages of the tube. The values of these capacitors should be

chosen so that sufficient charge is available to prevent a change

of more than a few percent in the interstage voltages throughout

the pulse duration.

The high voltages used to operate these tubes are very danger-

ous. Care should be taken in the design of apparatus to prevent

the operator from coming in contact with these high voltages.

High voltages may appear at points in the circuit which are

normally at low potential, because of defective circuit parts or

incorrect circuit connections. Therefore, before any part of the

circuit is touched, the power supply switch should be turned off

and both terminals of any capacitors grounded.

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