Oxford Instruments TC 154A User manual

INSTRUCTION
MANUAL
TC
1
54A/TC
155A
PLUG-ON
PREAMPLIFIER

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WARRANTY
E’
Oxfotd
Instruments
mc
warrants
that
the
products
or
components
manufactured
by
it shali
be
free
[
from
defects
in
material
or
workmanship
for
a period
of
one
year from
the
date
of
delivery
to
purchaser.
lf
such
product
or
component
is
determined to
be
defective
by
Oxford
lnstruments
mc,
its
sole
warranty
obligation
shaii
be
Iimited
to
either
replacing
or
repairing
such
defective
product
or
[
component
or
ailowing credit
therefor,
at Oxford’s
option.
Such
warranty
is
further
conditionai
the
purchaser
giving
prompt
notice
of any
such
defect
and
satisfactory
proof
thereof
to
Oxford’s
Customer
Service
Manager.
thereafter
upon
Oxford’s
approvai,
the
purchaser
shail
return
such
F
defective
product
or
component
to Oxfords
factoty
at
Oak
Ridge,
Tennessee,
ali
transportation
U
charges
prepaid.
Oxford
sha)l
be
responsible
oniy
for
transpottation
charges
incurred
in
returning
such
product
or
component
to
purchaser.
Ali
customs,
brokerage
and
duty
charges
shali
be
at
the
expense
r
of
the
purchaset.
Damage
in
transit
due
to
inadequate
packaging
wiil
be
repaired
at the
purchaser’s
[
expense.
Any
repaits
or
repiacements
by
the
purchaser
without
Oxford’s
approvai,
any
wiilful
abuse
or
any
evidence
that
the
product
or
component
was
not
properly used
and
maintained
would
automaticaliy
void
this
warranty.
Oxford
lnstruments
mc
makes
no
warranty
whatsoever
in
respect
to products
or
components not
manufactured
by
it,
but
iristead,
the
appiicable warranties,
if
any,
of
the
respective
manufacture
fl
thereof
shaii
apply.
Likewise
fuses,
batteries,
and
input
transistors
in
Iow-noise
preamplifiers
ate
LI
specificaiiy
exciuded
from
this
warranty.
1H15
WARRANW
IS
IN
LIEU
OF
ALL
OTHER
WARRANTIE5,
EXPRES5ED
OR
IMPLIED,
STATUTORY
OR
OTHERWISE,
INCLUDING
WARRANW
OF
MERCHANTABILITY
AND
FITNESS.

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TABLE OF
CONTENIS
Section
Page
7.0
INTRODUCTION
1
2.0
SPECIFICATIONS
1
3.0
CONTROLS
AND
CONNECTORS
2
4.0
OPERATING
INSTRUCTIONS
2
4.1
CONNECTION
TO HV
SUPPLY
3
4.2
CONNECTION
TO
lHE
MAIN
AMPLIFIER
3
5.0
EXTERNAL
PREAMPLIFIER
POWER
SOURCE
3
6.0
SERVICING
5
7.0
SHIPPING
DAMAGE
5
8.0
WARRANTY
6

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1.0
INTRODUCTION
The
TC
154A
and
TC
155A preamplifiers
are intended
to
work
with
scintillation
detectors
usíng
12-pin
and
14-pin
photomultiplier
fP-M)
tubes,
respectively.
Each
unit contains
a
charge—sensitive
preamplifier
circuit
on
an etched
cir—
cuit
board
and
a
P-M
tube
base
as
an integral
assembly.
Total
resistance
of
the
bleeder
string
is
nominally
1
M-ohm.
In
the standard
assemblies,
preamplifier
power
is
furnished
by
the
P-M
HV
supply through
the
bleeder
string.
However,
the
preamplifier
can
be
powered
by
the
main
amplifier
power
supply
if
desired.
See
Section
4.2.
lhe preamplifier
alone
requires
10V
@
300pA.
It
contains
no
internal
pulse
shaping
and
must
be
used
with
a
main
amplifier
which
contains
appropriate
shaping
networks.
2.0
SPECIFICATIONS
INPUT POLARITY
Negative
only.
OUTPUT
SIGNAL
CHARACTERISTICS
Polarity
Positive
only.
Risetime
0.05
sec
or
deternined
by
rise
time
of
scintillation
counter,
whichever
is greater.
Decay
Time
100
psec.
Impedance
5O.
DYNAMIC
RANGE
4V.
SIABILITY
0.1%
drift
in
output
voltage
per
24
hours.
TEMPERATURE
COEFFICIENT
O.Ol%/°C
ovet
a
00
to
50°C
range.
INTEGRAL
NONLINEARITY
7-V
Pulse
0.1%
rms
or
less.
SENSIIIVITY
2OmV/picocoulomb;
3.2niV/electron.
CHANGE
IN
SENSIIIVITY
vs.
Less
than
20%
decrease
over
a
DETECTOR
PLUS
CABLE
CAPACITANCE
l000pF
range.
NOISE
Referred
to
Input
Less
than
7
X
10-15
Coulombs
mis
for detectors
up
to
5OpF
wlth
0.8
usec
bipolar
Gaussian
shaplng.

2
E
E
Referred
to
Output
Less
than 20V
rms
under
condi
tions
described
above.
L
PERMISSIBLE
COUNI
RATE
0.2V
Output
Pulses
Limited
by
pulse
pile—up
in
main
amplifier.
CONTROLS
AND
CONNECTORS
Focus
Screwdriver
adjustable
poten
tiometer
(TC
155A
only).
P-M
Voltage
SHV
(Startronics
7758).
Output
Signal
BNC
fUG-1094/U).
P-M
Socket
TC
154A
Modified
72-pin
tube
socket.
TC
155A
Modified
14-pin
tube
socket.
[
POWER
REQUIREMENTS
High
Voltage
O
to +2kV
at
2mA
(maximum).
Preamplifier
Receives
power
from
ground
return
of dynode
resistors,
0.5mA
mmi
mum
operating
current.
ACCESSORIES
Instruction
manual.
NET WEIGHT
12
oz
(0.3 kg).
SHIPP1NG
WEJGHT
1
lb
12
oz
(0.7 kg).
WARRANTY
One
year.
t
3.0
CONTROLS
AND
CONNECIORS
E
Both the
TC
155A
and
IC
754A
contam
an
SHV
recepticle
for
high-voltage
connec
tion
and
a
BNC
recepticle
for
signal output.
A
screwdriver-adjustable
focus
[
control
is
available
on
the
TC
155A.
lhe
preamplifier section
is
in the
ground
return
of the
1W
bleeder
string
and
requires
no
additional
power.
4.0
0PERITING
INSTRUCTIONS
Since
the
preamplifier
contains
no
shaping network,
the
unit
must
be
used
E
with
a
main
amplifier
containing
one.
lraditionally,
bipolar
shaping
is
used
with
scintillation
counters.
lhe
fl
shaping
networks
which
give
the
best
results
with
NaI
(11)
are
delay
lines
with
a
0.8
to 1
sec
period,
or
dc
networks
with
0.25
to
0.5
i.isec
time
constants.
At
high
count
rates,
unipolar
shaping
can
give
better
resolution
than
bipolar
shaping,
but
only
if
the
main
amplifier
(1)
can
tolerate
large
overlods
with
out
generating
spurious
pulses.
(2)
contains
a pole/zero
canceilation
network,
and
(3)
contains
or
is
used
wjth
a baseline
restorer.
lhe
TENNELEC
TC
2O2BLR,
TC
2O3BLR,
TC
217,
TC
213,
TC
214,
and
TC
22OBLR
amplifiers
meet
these
re
quirements
and
the
instruction
manuais
associated
with
them
give
instructions
for
setting
the
pole/zero
cancellation
network.
[

3
4.7
CONNECTION
TO
HV
SUPPLY
lhe
assembly
is
connected
to
the
HV
supply
through
a
coaxial cable
(not
fur
nished).
Since
the bleeder
string
is
nominally
1
Meg,
the
current
dtain
will
be
2mA
at
2kV.
lhe unit
will
not
operate
properly
with
less
than
500V
because
not
enough
current
will
be
furnished
to
the
preamplifier
circuit.
4.2
C0NNECTION
TO
lHE
MAIN
AMPLIFIER
lhe
preamplifier
is
connected
to the
main
amplifier
through
a
coaxial
cable.
For
runs up
to
25
feet
(7.5
meters),
any convenient
coaxial cable
may
be
used.
For
longer
runs,
50-ohm
cable
(RG-58C/U)
should
be
used
and
it
should
not
be
terminated
at
the
main
amplifier
end. In
electrically
noisy
environments,
double-shield
cable
(RG—55B/U)
is
pteferred.
For
long
cable
runs,
changing
R7
(Fig.
1)
from
47
ohms
to
91
ohms will
allow
the
use
of
93-ohm
cable
such
as
RG-62A/U
fsingly
shielded)
or
RG-71B/U
fdoubly
shielded).
5.0
EXTERNAL
PREAMPLIFIER
POWER
SOURCE
A
simplified
circuit
diagram
which illustrates
the
power
supply
connections
is
shown
in Fig.
7.
lhere
are
four
ways in
which
the
preamplifier
can
re
ceive
its
power:
1.
From
the
bleeder
string.
At
least
0.5mA
drain
is
required,
of
which
200A for
more)
is
used
by
the zener
diode
D5
and
300i.A
by
the
preamplifier.
2.
From the
8+
terminal;
this
is
not
brought
out
to
a
connector,
but
can
be.
If
this
is
done,
any
voltage
from
+12
to
+24
can
be
used
to
power
the
unit.
It
is
not necessary
to
disconnect
the
bleeder
string
from
its
connection,
but
it
can
be,
if
desired.
In
this
case, the
end
of the
bleeder
string
must
be
grounded.
3.
From
the
8—
tenninal.
This
is
not
brought
out
to
a
connector,
but
can
be.
If
this
is
done,
any
voltage
from -72
to
-24
can
be
used
to
power
the
unit.
When
this
is
done
the
zener
diode 05
be
comes
forward
biased
and
the
+70V
point
in
Fíg.
7
goes to
-0.6V.
It
is
not
necessary
to
disconnect
the
bleeder
string
from
this
point
unless
the bleeder
current
exceeds
the
8-
drain
current,
in
which
case
05
should
be
short—circuited.
4.
Through
the output
signal
cable.
In
this
instance,
C6
and
C7
fFig.
7)
should
be
short-circuited
by
a
0.2” jumper fpads
on
the
circuit
board
have been
furnished
for
this
purpose)
and
the net
work
shown
in
Fig.
2
added
to
the
main
amplifier.
When
powered
in
this
way,
the
drain
on
the
main
amplifier
power
supply
is
about
3mA.
lhis current
is
large
enough
to
overcome
the
P-M
tube bleeder
current,
making
it
unnecessary
to
disconnect
it
from
the
+70V
point
fwhich,
in
this
instance,
becomes
-0.6V.

4
FOCUS
PREAMPLI
FIER
D2 1N47
BLEEDER
STRING
CONNECTION
1500
+70V
D5 7N5241
I)
77UTPUT
C8
0.01 pF
1500
Li
Fig.
7. Simplified
circuit
diagram
showing
power
connections.