GENERAL
FEATURES
Tritium efficiency in tritium window................................ 60% Typ.
Background noise in tritium window...............16cpm Typ. (R331)
18cpm Typ. (R331-05)
Tritium end point (T.E.P.) voltage.................................. 1700V Typ.
Dark pulse summation at T.E.P. voltage..............3
×
10
4
cpm Max.
Figure of merit (E
2
/B).......................................................... 200 Typ.
Parameter
R331-05
300 to 650
R331
Unit
nm
nm
—
mm dia.
Spectral Response
Wavelength of Maximum Response
Photo-
cathode
Minimum Useful Area
Window
Material
Dynode
Direct
Interelectrode
Capacitances
Base
Weight
Suitable Socket
—
—
—
—
pF
pF
—
g
—
420
Bialkali
46
Concave-Convex
Linear focused
12
2
2.5
21-pin glass base
151
E678-21A (Supplied)
160 to 650
Synthetic silica
(Frosted)
Material
Material
Shape
Structure
Number of Stages
Anode to Last Dynode
Anode to All Other
Electrodes
PHOTOMULTIPLIER TUBES
R331, R331-05
Information furnished by HAMAMATSU is believed to be reliable. However, no responsibility is assumed for possible inaccuracies or omissions. Specifications are
subject to change without notice. No patent rights are granted to any of the circuits described herein.
1998 Hamamatsu Photonics K.K.
Subject to local technical requirements and regulations, availability of products included in this promotional material may vary. Please consult with our sales office.
For Liquid Scintillation Counting
Bialkali Photocathode, 51mm (2 Inch) Diameter, 12 Stages, Head-On Type
Figure 1: Typical Spectral Response
TPMHB0505EA
The R331 and the R331-05 are 51mm (2 Inch) diameter series pho-
tomultiplier tubes specifically developed for the liquid scintillation count-
ing. They feature low background noise, high tritium efficiency, good
linearity and high gain. The R331 uses a synthetic silica input window
and the R331-05 uses a low K content borosilicate glass input window,
both with a frosted surface and convex-concave shape. They offer min-
imized glass scintillations and high collection efficiency.
Low K content
borosilicate
glass (Frosted)
100
10
1
0.1
0.01
200
400
600
800
WAVELENGTH (nm)
C
Q
CATHODE
RADIANT
SENSITIVITY
R331-05
R331
QUANTUM
EFFICIENCY