MAXIMUM RATINGS (Absolute Maximum Values at 25

°C)

Parameter

Value

Unit

Supply Voltage

Ambient Temperature

Vdc

Vdc

mA

°C

1250

250

0.1

-80 to +50

Between Anode and Cathode

Between Anode and Last Dynode

PHOTOMULTIPLIER TUBE R2949

CHARACTERISTICS (at 25

°C)

Table 1: Voltage Distribution Ratio

Parameter

Min.

Unit

Cathode

Sensitivity

Anode

Sensitivity

Time

Anode Current

%

µA/lm

mA/W

mA/W

mA/W

mA/W

mA/W

—

µA/lm-b

A/lm

A/W

A/W

A/W

A/W

A/W

—

cps

cps

nA

W

ns

ns

%

%

—

140

—

—

—

—

—

0.1

—

1000

—

—

—

—

—

—

—

—

—

—

—

—

—

—

Max.

—

—

—

—

—

—

—

—

—

—

—

—

—

—

—

—

500

—

25

—

—

—

—

—

Typ.

25.3

200

18

52

68

41

3.5

0.3

7.5

2000

1.8

5.2

6.8

4.1

3.5

1.0

300

3

2

1.2

2.2

22

0.1

1.0

Quantum

Efficiency

Radiant

with R-68 Filter

Radiant

Anode Pulse

Current Hysteresis

Voltage Hysteresis

at 255nm

at 194nm

at 254nm

at 400nm

at 633nm

at 852nm

at 194nm

at 254nm

at 400nm

at 633nm

at 852nm

at +25

°C

at -20

°C

NOTES

A: Averaged over any interval of 30 seconds maximum.

B: The light source is a tungsten filament lamp operated at

a distribution temperature of 2856K. Supply voltage is

100 volts between the cathode and all other electrodes

connected together as anode.

C: Red/white ratio is the quotient of the cathode current

measured using a red filter interposed between the light

source and the tube by the cathode current measured

with the filter removed under the same conditions as

Note B.

D: 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 conditions as Note B.

E: Measured with the same light source as Note B and with

the anode-to-cathode supply voltage and voltage

distribution ratio shown in Table 1.

F: Measured with the same supply voltage and the voltage

distribution ratio as Note E after 30 minute storage in

the darkness.

G: 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

ldb = Anode dark current (after 30 minute storage)

in darkness) 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 wavelength of peak response.

H: The rise time is the time for the output pulse to rise from

10% to 90% of the peak amplitude when the entire pho-

tocathode is illuminated by a delta function light pulse.

J: The electron transit time is the interval between the

arrival of delta function light pulse at the entrance

window of the tube and the time when the anode output

reaches the peak amplitude.

In measurement, the

whole photocathode is illuminated.

K. Hysteresis is temporary instability in anode current after

light and voltage are applied.

(1) Current Hysteresis

The tube is operated at 750 volts with an anode current of 1

microampere for 5 minutes. The light is then removed from

the tube for a minute. The tube is then re-illuminated at the

previous light level for a minute to measure the variation.

(2)Voltage Hysteresis

The tube is operated at 300 volts with an anode current of

0.1 microampere for 5 minutes. The light is then removed

from the tube and the supply voltage is quickly increased to

800 volts. After a minute, the supply voltage is reduced to

the previous value and the tube is re-illuminated for a

minute to measure the variation.

Supply Voltage= 1000Vdc

K: Cathode, Dy: Dynode, P: Anode

Electrodes

Distribution

Ratio

K

Dy1

1

Dy2

1

Dy3

1

Dy4

1

Dy5

1

Dy6

1

Dy7

1

Dy8

1

Dy9

11

P

ENI =

2q•ldb•G•

∆f

S

Hysteresis =

× 100 (%)

Imax. - Imin.

Ij

Imin.

Ii

Imax.

05

6

TIME