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MAXIMUM RATINGS (Absolute Maximum Values)
Parameter Value
Supply Voltage
Between Anode and Cathode
Between Anode and Last Dynode
1250
250
0.1
–80 to +50
Vdc
Vdc
mA
Average Anode Current
Unit
Ambient Temperature
CHARACTERISTlCS (at 25 )
NOTES
Parameter
Min. Max.
R928
Typ.
Cathode Sensitivity
Anode Dark Current
F
After 30 minute Storage in the darkness 3 50
Anode Current Stability
L
A:
B:
C:
D:
E:
Averaged over any interval of 30 seconds maximum.
The light source is a tungsten filament lamp operated at a distribution tem-
perature of 2856K. Supply voltage is 100 volts between the cathode and
all other electrodes connected together as anode.
Red/White ratio is the quotient of the cathode current measured using a
red filter(Toshiba R-68) interposed between the light source and the tube
by the cathode current measured with the filter removed under the same
conditions as Note B.
The value is cathode output current when a blue filter(Corning CS-5-58
polished to 1/2 stock thickness) is interposed between the light source and
the tube under the same condition as Note B.
Measured with the same light source as Note B and with the voltage distri-
bution ratio shown in Table 1 below.
F:
G:
H:
I:
Measured with the same supply voltage and voltage distribution ratio as
Note E after removal of light.
Measured at a supply voltage adjusted to provide an anode sensitivity of
100 A/lm.
ENI is an indication of the photon-limited signal-to-noise ratio. It refers to
the amount of light in watts to produce a signal-to-noise ratio of unity in the
output of a photomultiplier tube.
where q = Electronic charge (1.60 10
-19
coulomb).
ldb = Anode dark current(after 30 minute storage) in amperes.
G = Gain.
f = Bandwidth of the system in hertz. 1 hertz is used.
S = Anode radiant sensitivity in amperes per watt at the wave-
length of peak response.
The rise time is the time for the output pulse to rise from 10% to 90% of the
peak amplitude when the entire photocathode is illuminated by a delta
function light pulse.
ENI =
S
2q
.
ldb
.
G
.
f
Current Hysteresis
Voltage Hysteresis
0.1
1.0
Radiant at 194nm 18
Red/White Ratio
C
0.3
Blue
D
8
254nm 52
400nm 74
633nm 41
852nm 3.5
Anode Pulse Rise Time
I
2.2
Electron Transit Time
J
22
Transit Time Spread (TTS)
K
1.2
Time Response
E
Electrode K Dy1 Dy2 Dy3 Dy4 Dy5 Dy6 Dy7 Dy8 Dy9 P
Distribution
Ratio
1111111111
SuppIy Voltage : 1000Vdc
K : Cathode, Dy : Dynode, P : Anode
Quantum Efficiency at Peak Wavelength
140 250
25.4
(at 260nm)
0.2
Anode Sensitivity
Gain
E
ENI(Equivalent Noise Input)
H
Unit
PHOTOMULTlPLlER TUBES R928, R955
Luminous
B
Radiant at 194nm 1.8 10
5
254nm
400nm
633nm
852nm
Luminous
E
2500400
5.2 10
5
7.4 10
5
4.1 10
5
3.5 10
4
1.0 10
7
1.3 10
-16
Min. Max.
R955
Typ.
350 nA
0.1
1.0
%
%
43 mA/W
0.3
8 A/lm-b
56 mA/W
74 mA/W
41 mA/W
3.5 mA/W
2.2
22
1.2
ns
ns
ns
140 250 A/lm
29.0
(at 220nm)
%
0.2
4.3 10
5
A/W
2500 A/lm400
5.6 10
5
A/W
7.4 10
5
A/W
4.1 10
5
A/W
3.5 10
4
A/W
1.0 10
7
1.3 10
-16
W
Table 1:Voltage Distribution Ratio