M A I N
F E A T U R E S
Compact Size
The
CPM is one of the smallest head-
on type detectors, with a 10.5 mm
diameter including encapsulation. The
photocathode has a useful diameter
of more than 5 mm. The tube is smal-
ler, easier to use, and more rugged
than discrete dynode types. Only a
single high voltage supply of up to
3000 volts is necessary; no external
voltage divider network is required.
A variety of different sizes will be avai-
lable soon (
1
/
2
” and
3
/
4
”).
Unpotted
1
/
3
inch Channel Photomultiplier
Fig. 1: Typical current amplification
1 E+09
1 E+08
Current Amplification
1 E+07
9 mm
Ultra high anode sensitivity
1 E+06
1 E+05
1 E+04
1 E+03
1 E+02
1000
1500
2000
Bias Voltage (V)
2500
3000
At
the maximum bias voltage of 3000 V,
gains can exceed 10
8
. At 2400 V, an-
ode sensitivity is typically 3 x 10
6
A/W
at a wavelength of 410 nm with a bi-
alkali photocathode. This performan-
ce surpasses conventional PMTs by
one to two orders of magnitude and
beats APDs by approximately five or-
ders of magnitude (Fig. 1).
Fig. 2: Typical anode dark current
1 E-05
1 E-06
1 E-07
1 E-08
1 E-09
1 E-10
1 E-11
1 E-12
1000
C 972
C 962
C 952
C 942
C 922
C 911
1500
2000
Bias Voltage (V)
2500
3000
Extremely low dark current
The
electron multiplication in the
channel is virtually silent, so dark cur-
rent depends only on the photoca-
thode material, leakage currents are
negligible. Bialkali photocathodes ex-
hibit typical dark count rates of 10
cps at a gain of 3 x 10
8
, while UV ca-
thodes have dark count rates below 1
cps. In analog DC mode, the typical
dark noise for a bialkali photocathode
is 20 pA at a gain of 10
7
. In general,
the noise level of the PerkinElmer
Optoelectronics CPM is one to two
orders of magnitude lower than dyn-
ode PMTs, resulting in a significant-
ly higher dynamic range (Fig.2).
Dark Current (A)
PERKINELMER [ PERKINELMER OPTOELECTRONICS ]
