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Channel Photomultipliers
Channel Photomultipliers
Overview and Specifications
.
C H A N N E L
P H O T O M U L T I P L I E R
C P M
Description
PerkinElmer
Optoelectronics, for-
merly EG&G Optoelectronics, is
pleased to introduce the Channel
Photomultiplier (CPM), a new ultra
high sensitivity optical detector
which replaces conventional photo-
multipliers (PMTs) and avalanche
photo diodes (APDs). This device
uses a unique detector principle, re-
sulting in a compact design with ul-
tra high gain, high dynamic range,
extremely low dark current, and fast
response.
This
high-performance detector offers
fundamental advantages for analytical
instrumentation applications such as
emission spectroscopy, flourescence,
atomic absorption spectroscopy, and
bio and chemo luminescence. The
CPM also delivers important advan-
tages in life science products, indus-
trial and medical equipment, and high-
energy physics.
Features
• Ultra high anode sensitivity
up to 10
7
A/W
• Extremely low dark current,
typically 3pA @ 10
6
gain
• Very low equivalent
noise input (down to 10
-17
W)
• Very high stability in dark current
(no ”bursts”)
• High gain exceeding 10
8
• Very high dynamic range
• Compact dimensions
• Wide spectral response through
multiple window materials
• High resolution
• Fast response time
• High immunity to magnetic fields
• Rugged design
When
compared to conventional
PMTs, the CPM improves anode
sensitivity by one order of magni-
tude, while lowering dark current by
one to two orders of magnitude. The
noise level shows extreme stability
over time, with no ”bursts.” The
extremely low dark current results in
a higher dynamic range than con-
ventional PMTs and extends detec-
table limits for many applications.
The
CPM can be used in analog-DC
mode, single photon counting mode,
and in nuclear spectroscopy (when
coupled to scintillation materials like
BGO, LSO, Nal, etc.). PerkinElmer
Optoelectronics offers a choice of
window materials and photocatho-
des to cover the spectrum from
115 nm (UV range) to 900 nm (NIR).
The
new detector is a small, head-on
type with a total diameter of 10.5 mm
including encapsulation. PerkinElmer
Optoelectronics also offers custom
configurations for specific applica-
tions.
P R I N C I P L E
Principle of Operation
O F
O P E R A T I O N
Physical Specification
Cathode Channel-Entrance
Channel-End Anode
The
CPM, like conventional photo-
multiplier tubes, converts a very low
light level into photoelectrons by a
semitransparent photocathode de-
posited on the inner surface of the
entrance window. On their way from
the cathode to the anode the photo-
electrons pass through a narrow, se-
miconductive channel. Each time the
electrons hit the inner wall of the
curved channel, multiple secondary
electrons are emitted. This effect oc-
curs multiple times along the path,
leading to an avalanche effect with a
gain exceeding 10
8
. The curved sha-
pe of the glass tube improves the
multiplication effect.
-HV
red
-HV +50…+300 V
blue
-20…-50 V
black
Coax
100 V
1 Mohm
-HV
Proposal for Power Supply
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)
High stability in dark current level
As
a result of the semiconductive inner surface of the CPM, no charge-up effects occur at the glass surface. This
results in a very high stability of the dark current level over time, with no sudden changes (bursts). The semiconductive
surface also causes high-light recovery times to be extremely small.
Fig. 3: Typical photo electron spectrum
2000
PMT
CPM
1500
Excellent photon counting resolution
At
gains exceeding 10
7
the single photo electron pulse is
perfectly separated from the electrical noise, due to a sa-
turation effect of the channel. The CPM exhibits single
photon resolution with excellent peak to valley ratios.
Fig. 3 shows the single photo electron spectrum taken
from a multi-channel analyzer compared to a conventional
photomultiplier (Fig. 3).
Counts
1000
500
Choice of entrance window
0
0
50
100
150
Channel
200
250
300
Fig. 4.1: Typical spectral response
100
The
CPM is available with different window materials,
which are:
MgF
2
, Quartz, UV-glass, and Borosilicate glass. The com-
bination of different photocathodes and entrance windows
results in a spectral range from 115 nm to 900 nm. Other
window materials and photocathode combinations are
available on a custom basis (Fig. 4.1 and 4.2).
Quantumefficency (%)
10
1
C 973
C 952
Available related products
C 922
C 911
0.1
100
200
300
400
500
600
700
800
Wavelength (nm)
C 972
900
Fig. 4.2: Typical spectral response
100
• High Voltage supply
CHV 30N (supplies 1 CPM, negative output voltage),
CHV 30P (supplies 1 CPM, positive output voltage),
J4-3N (supplies 10 to 15 CPMs)
10
C 943
C 944
1
C 942
C 962
0.1
100
200
300
400
500
600
700
800
900
Wavelength (nm)
• CPM Modules
MP900-series: Photoncounting module with
TTL output, including CPM,
electronic and high voltage
MD900-series: DC module including high
voltage supply, amplifier,
I/U converter, output 0 to 10 V,
bandwidth 1kHz
MH900-series: High voltage module,
including CPM and
high voltage power supply
• CPM Formats
Quantumefficency (%)
EU
PerkinElmer Optoelectronics GmbH
Heimann Opto
65020 Wiesbaden, Germany
PO-Box 3007
http://www.perkinelmer.com/opto
USA
PerkinElmer Optoelectronics
2175 Mission College Blvd.
Santa Clara, CA 95054
Tel. ++1 (408) 565 - 0830
Fax ++1 (408) 565 - 0703
http://www.perkinelmer.com/opto
/
3
“ C900-series
1
/
2
“ C1300-series
3
/
4
“ C1900-series
1
Datasheets on request
CPM C900 Series
1/3” CPM Channel Photomultipliers
·
·
·
·
High Sensitivity Optical Detector
Extremely High Gain
Ultra Low Noise
1/3 Inch, Head-On Type
Technical Specifications
Dimensions (mm)
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