Eg&g Ortec 458 Service manual

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Model

458

Pulse

Shape

Analyzer

.5^

ORTEC

458

PULSE

SHAPE

ANALYZER

Manual

Change

Sheet

March

8,1972

ECN3

In

Fig.

3.1

on

page

3,

negative-going

pulses

are

shown

for

each

of

the

four

indicated

pulses.

This

is

in

error;

all

four

should

be

positive-going

pulses

and

are

inverted

from

the

waveforms

that

will

be

seeen

on

an

oscil

loscope.

On

Schematic

458-0201-S1,

change

the

connection

from

the

collector

of

Q21

to

the

cathode

of

D24

to

show

that

it

is

actually

connected

from

the

col

lector

of

Q21

to

the

anode

of

D24.

On

Schematic

458-0301-SI,

change

the

value

of

R74

from

1.33K

to

1.47K;

change

the

value

of

C12

from

15

pF

to

10

pF;

add

RMS,

422

ohms

1%,

1/8

W,

MFTO

in

series

between

R31

and

the

junction

of

TP3,R78,

R79,

C11,

and

the

collector

of

Q14.

L

j

Model

458

Pulse

Shape

Analyzer

Operating

and

Service

Manual

Printed

in

U.S.A.

©

ORTEC

Incorporated

1971

993

03C

1171

02

STANDARD

WARRANTY

FOR

ORTEC

INSTRUMENTS

ORTEC

warrants

its

instruments

other

than

preampl

ifier

FET

input

transistors,

vacuum

tubes,

fuses,

and

batteries

to

be

free

from

defects

in

workmanship

and

materials

for

a

period

of

twelve

months

from

date

of

shipment

provided

that

the

equipment

has

been

used

in

a

proper

manner

and

not

subjected

to

abuse.

Repairs

or

replace

ment,

at

ORTEC

option,

wil

l

be

made

on

in-warranty

instruments,

without

charge,

at

the

ORTEC

factory.

Shipping

expense.wi

l

be

to

the

account

of

the

customer

except

in

cases

of

defects

discovered

upon

initial

operation.

Warranties

of

vacuum

tubes

and

semiconductors

made

by

their

manufacturers

wil

l

be

extended

to

our

customers

only

to

the

extent

of

the

manufacturers'

l

iabi

l

ity

to

ORTEC.

Special

ly

selected

vacuum

tubes

or

semiconductors

cannot

be

warranted.

ORTEC

reserves

the

right

to

modify

the

design

of

its

products

without

incurring

responsibil

ity

for

modification

of

previously

manufactured

units.

Since

in

stal

lation

conditions

are

beyond

our

control,

ORTEC

does

not

assume

any

risks

or

l

iabil

ities

associated

with

methods

of

instal

lation

or

with

instal

lation

results.

QUALITY

CONTROL

Before

being

approved

for

shipment,

each

ORTEC

in

strument

must

pass

a

stringent

set

of

qual

ity

control

tests

designed

to

expose

any

flaws

in

materials

or

workmanship.

Permanent

records

of

these

tests

are

maintained

for

use

in

warranty

repair

and

as

a

source

of

statistical

information

for

design

improvements.

ORTEC

must

be

informed

in

writing

of

the

nature

of

the

fault

of

the

instrument

being

returned

and

of

the

model

and

serial

numbers.

Fai

lure

to

do

so

may

cause

unnecessary

delays

in

getting

the

unit

repaired.

Our

standard

procedure

requires

that

instruments

returned

for

repair

pass

the

same

quality

control

tests

that

are

used

for

new-production

instruments.

Instruments

that

are

returned

should

be

packed

so

that

they

wil

l

withstand

normal

transit

handling

and

must

be

shipped

PREPAID

via

Air

Parcel

Post

or

United

Parcel

Service

to

the

nearest

ORTEC

repair

center.

Instru

ments

damaged

in

transit

due

to

inadequate

packing

wi

ll

be

repaired

at

the

sender's

expense,

and

it

wil

l

be

the

sender's

responsibi

lity

to

make

claim

with

the

shipper.

Instruments

not

in

warranty

will

be

repaired

at

the

standard

charge

unless

they

have

been

grossly

misused

or

mishandled,

in

which

case

the

user

wi

ll

be

notified

prior

to

the

repair

being

done.

A

quotation

wil

l

be

sent

with

the

notification.

DAMAGE

IN

TRANSIT

Shipments

should

be

examined

immediately

upon

receipt

for

evidence

of

external

or

concealed

damage.

The

carrier

making

del

ivery

should

be

notified

immediately

of

any

such

damage,

since

the

carrier

is

normal

ly

liable

for

damage

in

shipment.

Packing

materials,

waybi

l

ls,

and

other

such

documentation

should

be

preserved

in

order

to

establ

ish

claims.

After

such

notification

to

the

carrier,

please

notify

ORTEC

of

the

circumstances

so

that

we

may

assist

in

dam

age

claims

and

in

providing

replacement

equipment

if

necessary.

Ill

CONTENTS

Page

WARRANTY

ii

PHOTOGRAPHS

iv

1.

GENERAL

DESCRIPTION

1

2.

SPECIFICATIONS

2

3.

INSTALLATION

3

3.1

General

3.2

Connection

to

Power

3.3

Connection

to

Linear

Amplifier

Output

3

4.

OPERATION

4

4.1

General

4.2

Front

Panel

Controls

4

5.

CIRCUIT

DESCRIPTION

5

5.1

General

5.2

Detailed

Circuit

Description

5

6.

MAINTENANCE

9

6.1

Testing

Performance

6.2

Calibration

Adjustments

6.3

Walk

Adjustment

6.4

Troubleshooting

9

10

7.

APPLICATIONS

11

7.1

Neutron-Gamma

Discrimination

with

Stilbene

and

Liquid

Scintillators

7.2

Neutron—Gamma-Ray

Discrimination

in

Proportional

Counters

7.3

Rise-Time

Discrimination

in

X-Ray

Proportional

Counter

11

13

14

REFERENCES

15

BLOCK

DIAGRAM

and

SCHEMATICS

458-0101-B1

458-0201-SI

458-0301-SI

LIST

OF

FIGURES

Fig.

3.1.

Waveforms

Observed

at

Test

Point

TP1

Fig.

5.1.

458

Timing

Diagram

Fig.

7.1.

Calculated

Response

for

(a)

100

keV

and

(b)

70

keV

Electron

Equivalent

3

6

Energies

Deposited

in

NE-213

12

Fig.

7.2.

Single

Delay

Line

Shaped

Signal

12

Fig.

7.3.

Block

Diagram

for

a

Typical

Neutron-Gamma

Separation

Experiment

13

Fig.

7.4.

Neutron-Gamma

Rise

Time

Spectrum

13

Fig.

7.5.

A

Typical

Neutron

and

Gamma

Rise

Time

Spectrum

from

a

Proton

Recoil

Proportional

Counter

13

Fig.

7.6.

Neutron-Gamma

Discrimination

System

with

Proportional

Counter

13

Fig.

7.7.

Background

Reduction

System

for

an

X-Ray

Proportional

Counter

14

Fig.

7.8.

Suggested

System

for

Setting

the

PSA

Window

of

the

458

14

Fig.

7.9.

Pulse

Shape

Spectrum

Taken

with

Proportional

Counter

System

Shown

in

Fig.

7.8

14

ORTEC^

^

MODEL

458

PULSE

SHAPE

ANALYZER

TIME

RANGE

0,6

0

4

,

0.8

INPUT

DISC.

»Sec

Volts

WALK

UPPER

LEVEL

LOWER

LEVEL

PSA

TIME

WINDOW

INPUT

WINDOW

'

L

Q

N

E

A

G

UL

c

OUTPUT

i

OUTPUT

1

SEIL

iriiniT

Dific.

e.

OliTiniT

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'•fSf*

1

t

-.i-

■#

,L.-

ORTEC

458

PULSE

SHAPE

ANALYZER

1.

GENERAL

DESCRIPTION

The

ORTEC

458

Pulse

Shape

Analyzer

measures

the

fal

l

time

of

an

input

pulse

from

a

shaping

ampl

ifier

and

generates

a

l

inear

output

pulse

with

an

amplitude

that

is

proportional

to

the

fal

l

time.

It

also

includes

a

single

channel

analyzer

that

can

generate

either

of

two

logic

output

pulses,

based

on

the

measured

fal

l

time.

One

of

the

single

channel

logic

outputs

occurs

when

the

time

is

within

the

single-channel

window;

the

other

occurs

when

the

upper

level

setting

is

exceeded.

A

separate

logic

output

occurs

when

the

input

pulse

ampl

itude

exceeds

the

input

discriminator

threshold.

The

ORTEC

458

accepts

input

pulses

from

any

shaping

ampl

ifier,

RC,

active-filter,

or

delay-l

ine.

Its

l

inear

output

is

interpreted

as

a

measurement

of

the

pulse

shape

of

the

input

signal

.

The

output

is

independent

of

the

ampl

itude

of

the

input

and

depends

only

on

the

shape

(waveform)

of

the

input

signal

as

a

function

of

time.

The

shape

of

the

main

shaping

amplifier

output

varies,

depending

on

certain

experimental

conditions.

Although

there

are

several

examples

of

such

variations,

perhaps

the

best

known

is

the

neutron

and

gamma

response

in

certain

scinti

l

lators.

The

conditions

on

the

electronics

in

this

case

are

stringent

because

of

the

nonl

inear

response

of

the

scinti

l

lator

as

a

function

of

neutron

energy.

For

neutrons

with

energies

from

200

keV

to

10

MeV,

the

response

of

an

NE-213

scintil

lator

can

vary

over

a

500:1

range.

The

458

can

operate

satisfactorily

over

a

400:1

dynamic

range

in

these

neutron-gamma

appl

ications,

and

this

has

not

been

possible

heretofore.

This

unit

is

also

appl

icable

for

use

with

gaseous

detectors

for

particle

identification.

Gaseous

detectors

are

designed

so

that

the

charge

col

lection

time

(and

therefore

the

resulting

pulse

shape)

is

influenced

by

the

location

of

the

interaction

within

the

detector,

and

the

interaction

site

is

the

interacting

particle

type.

Another

appl

ication

of

pulse-shape

analysis

is

with

large

Ge(Li)

semiconductor

detectors.

With

the

458

events

that

interact

within

the

desired

portion

of

the

detector

can

be

selected,

and

those

that

occur

in

low

electric-field-strength

regions

can

be

rejected,

thereby

optimizing

the

energy

resolution

of

the

system.

Some

typical

appl

ications

of

the

458

for

timing

ex

periments

are

described

in

Section

7.

The

input

signal

from

the

main

amplifier

covers

the

0-

to

10-V

range.

The

input

discriminator

covers

the

complete,

range

from

20

mV

to

10

V.

The

input

wi

l

be

approxi

mately

symmetrical

for

delay-l

ine

and

active-fi

lter

amp

l

ifier

inputs.

For

classical

RC

fi

ltering

the

fal

l

time

wi

l

be

substantial

ly

longer

than

the

rise

time.

For

al

l

inputs

the

time

range

switch

should

be

set

to

be

equal

to

or

greater

than

the

fal

l

time

of

the

input.

Time

ranges

from

0.2

to

10

ftsec

are

selectable.

A

pulse-shape

analysis

"time

window"

is

provided

for

selection

of

a

time

region

within

the

time

range.

With

this

window

a

logic

gating

pulse

can

be

provided

for

al

l

input

pulses

that

have

a

preselected

shape

within

this

time

region.

In

this

way,

for

example,

al

l

neutron

events

can

generate

a

control

function

through

the

window

output,

whereas

the

gamma-ray

events

wi

l

produce

no

control

outputs.

2.

SPECIFICATIONS

PERFORMANCE

DYNAMIC

RANGE

25

mV

to

10

V

(400:1)

input

pulse

ampl

itude

range.

TIME

MEASUREMENT

ERROR

<5%

for

the

ampl

itude

range

25

mV

to

10

V.

TIME

RANGE

NONLINEARITV

<2%

of

the

time

range

plus

the

effect

of

the

rise

time

of

the

input

amplifier

(~100

nsec).

TIME

RESOLUTION

<2%

of

the

selected

time

range

for

any

input

pulse

ampl

itude

within

the

range

25

mV

to

10

V.

TEMPERATURE

STABILITY

LOWER

LEVEL

10-turn

precision

control

with

1000-

division

locking

direct-reading

dial

to

select

the

minimum

time

of

interest

within

the

time

window.

The

10

turns

cover

the

entire

selected

time

range.

WALK

ADJ

20-turn

control

to

minimize

changes

in

output

for

changes

in

input

amplitude

while

keeping

the

shape

constant.

INPUT

LINEAR

INPUT

0

to

10

V,

either

positive

unipolar

or

bipolar

with

positive

lobe

leading,

from

any

shaping

amp

l

ifier

such

as

delay-l

ine,

active-fi

lter,

or

classical

RC

pulse

shapes

from

0.2

to

10

/tsec;

type

BNC

connector

on

front

panel

.

Input

Discriminator

<0.05%/°C.

Upper

Level

<0.05%/°C.

Lower

Level

<0.05%/°C.

NONLINEARITY

Input

Discriminator

<1%.

Upper

Level

<0.25%.

Lower

Level

<0.25%.

CONTROLS

TIME

RANGE

5-position

front-panel

switch

to

select

time

range

of

0.2,

0.4, 0.6, 0.8,

or

1.0

fisec.

A

2-position

multipl

ier

is

provided

to

select

XI

or

XI0

of

the

selected

time

as

desired.

INPUT

DISC

10-turn

precision

control

with

1000-

division

locking

direct-reading

dial

to

select

the

minimum-

ampl

itude

input

to

be

analyzed.

A

2-position

range

switch

selects

either

a

10-mV

to

100-mV

range

or

a

100-mV

to

10-V

range.

'

PSA

TIME

WINDOW

A

time

window

can

be

selected

within

the

Time

Range

with

the

Lower

Level

and

Upper

Level

controls:

e.g.

,

on

the

1-/tsec

time

range

with

the

Upper

Level

set

at

500

and

the

Lower

Level

set

at

300,

any

input

with

90%

to

10%

fal

l

times

within

300

to

500

nsec

wi

l l

produce

Window

logic

output

pulses.

UPPER

LEVEL

10-turn

precision

control

with

1000-

division

locking

direct-reading

dial

to

select

the

maximum-

time

of

interest

within

the

time

window.

The

10

turns

cover

the

entire

selected

time

range.

OUTPUTS

LINEAR

OUTPUT

0

to

10

V

unipolar

signal

with

ampl

itude

proportional

to

the

90%

to

10%

time

of

the

linear

input;

+12

V

max;

Zq

<1^2,

dc-coupled

and

short-

circuit

protected;

type

BNC

connector

on

front

panel

.

PSA

TIME

WINDOW

Window

A

+5-V

500-nsec

output

pulse

is

provided

when

the

input

pulse

shape

is

between

the

l

imits

set

by

the

Upper

Level

and

Lower

Level

discriminators;

Zq

<1012,

dc-coupled;

type

BNC

connector

on

front

panel

.

UL

Output

A

+5-V

500-nsec

pulse

is

provided

when

the

input

pulse

has

a

90%

to

10%

fal

l

time

greater

than

that

set

by

the

Upper

Level

discriminator;

Zq

<10^2,

dc-

coupled;

type

BNC

connector

on

front

panel

.

INPUT

DISC

A

+5-V

500-nsec

signal

is

provided

when

the

input

ampl

itude

exceeds

the

input

discriminator

set

point;

Zq

<10L2,

dc-coupled;

type

BNC

connector

on

rear

panel

.

ELECTRICAL

AND

MECHANICAL

POWER

REQUIRED

+24

V,

158

mA;

+12

V,

240

mA;

-24

V,

136

mA;

-12

V,

225

mA.

WEIGHT

(Shipping)

~5.75

lb

(~2.6

kg).

WEIGHT

(Net)

-3.75

lb

(-1.7

kg).

DIMENSIONS

Standard

NIM

double-width

module

(2.70

by

8.714

in.)

per

TID-20893

(Rev.).

3.

INSTALLATION

3.1.

GENERAL

The

ORTEC

458

contains

no

internal

power

but

must

be

used

in

conjunction

with

an

ORTEC

401/402

Series

Bin

and

Power

Supply,

which

is

intended

for

rack

mounting.

Therefore

if

other

equipment

is

operated

in

the

same

rack

(particularly

vacuum

tube

equipment)

there

must

be

sufficient

cool

ing

air

circulating

to

prevent

any

local

ized

heating

of

the

al

l-transistorized

circuitry

of

the

458.

The

temperature

of

equipment

mounted

in

racks

can

easi

ly

exceed

the

recommended

maximum

unless

these

pre

cautions

are

taken.

The

458

should

not

be

subjected

to

temperatures

in

excess

of

120°F

(50°C).

To

obtain

maximum

temperature

insensitivity,

the

458

should

not

be

exposed

to

high

velocity

drafts

of

cool

ing

air,

especial

ly

if

the

temperature

of

the

cool

ing

air

is

not

stable.

3.2.

CONNECTION

TO

POWER

The

Power

Supply

to

the

401

Bin

should

be

turned

off

when

modules

are

inserted

or

removed.

ORTEC

modular

instruments

are

designed

so

that

it

is

not

possible

to

overload

the

Power

Supply

with

a

ful

l

complement

of

modules

in

the

Bin.

Since,

however,

this

may

not

be

true

if

the

Bin

contains

modules

other

than

those

of

ORTEC

design,

the

Power

Supply

voltages

should

be

checked

after

the

modules

are

inserted.

The

ORTEC

401

Series

Bin

has

test

points

on

its

Power

Supply

control

panel

to

monitor

the

dc

voltages.

The

Power

Supply

voltages

should

read

within

±0.5%

of

the

nominal

values

for

proper

operation

of

NIM-standard

instruments.

3.3.

CONNECTION

TO

LINEAR

AMPLIFIER

OUTPUT

(a)

Pulse

Shape.

(b)

Baseline

Offset

with

R46

Adjusted

Too

Far

Clockwise.

/

u-y

The

input

to

the

458

is

furnished

through

a

front

panel

BNC

connector.

The

input

circuit

can

accept

0-

to

10-V

unipolar

signals

into

a

1000T2

load.

The

input

operating

range

is

from

100

mV

to

10

V

when

the

Input

Disc

range

switch

is

set

at

10

V.

When

the

switch

is

set

at

0.1.V,

the

input

operating

range

is

from

20

mV

to

10

V,

but

precautions

must

be

observed

to

obtain

this

wider

dynamic

range.

Use

the

fol

lowing

procedure

with

the

switch

set

at

0.1

V:

1.

If

the

l

inear

amplifier

has

a

dc

output

adjustment,

adjust

the

output

level

careful

ly

to

0

+

5

mV.

The

rise

time

of

the

output

pulse

should

be

less

than

1

/tsec.

2.

Use

a

pulse

generator

to

furnish

pulses

through

the

ampl

ifier.

Adjust

the

pulse

generator

ampl

itude

and

the

ampl

ifier

gain

for

an

amplifier

output

of

2

V.

Connect

this

to

the

458

Input.

3.

Connect

an

oscil

loscope

probe

to

test

point

TP1,

accessible

through

the

top

of

the

458.

Set

the

osci

l

loscope

for

0.5

V/division

and

1

^tsec/division.

The

osci

l

loscope

trace

should

be

similar

to

that

shown

in

Fig.

3.1a.

4.

Set

the

osci

lloscope

sensitivity

to

50

mV/division

and

adjust

R46,

located

between

the

test

point

and

the

front

(c)

Baseline

Offset

with

R46

Adjusted

Correctly.

(d)

Baseline

Offset

with

R46

Adjusted

Too

Far

Counterclockwise.

Fig.

3.1.

Waveforms

Observed

at

Test

Point

TP1.

panel,

for

a

zero

basel

ine

offset

simi

lar

to

that

in

Fig.

3.1c.

If

R46

does

not

have

sufficient

range

to

obtain

the

zero

basel

ine

offset,

use

R4

as

a

coarse

adjustment

and

then

complete

the

adjustment

of

R46.

5.

The

Input

Disc

dial

has

1000

divisions,

corresponding

to

its

range

of

100

mV.

Set

the

control

as

desired,

between

100

and

1000

dial

divisions,

to

determine

the

minimum

input

pulse

amplitude

that

wi

l

trigger

a

time

measurement.

4.

OPERATION

4.1.

GENERAL

The

ORTEC

458

Pulse

Shape

Analyzer

measures

the

time

during

which

the

input

waveform

falls

from

90%

of

its

peak

amplitude

to

10%

of

its

peak

amplitude,

pro

viding

the

peak

amplitude

is

sufficient

to

trigger

the

458

input

discriminator.

When

the

shape

of

the

input

pulse

varies,

due

to

the

nature

of

the

information

furnished

into

the

l

inear

ampl

ifier

preceding

the

458,

the

fal

l

time

of

the

pulse

wi

l l

vary

and

wi

l l

provide

a

variation

of

the

l

inear

output

ampl

itude

that

is

proportional

to

the

measured

time.

After

the

decay

time

has

been

converted

into

a

linear

output

pulse,

with

an

ampl

itude

range

of

0

to

10

V

corresponding

to

the

selected

time

range,

the

variety

of

pulse

ampl

itudes

that

are

avai

lable

through

the

l

inear

output

wil

l

reflect

the

nature

of

the

experiment.

For

example,

there

wi

l

be

two

principal

concentrations

of

pulse

heights

for

the

gamma-neutron

appl

ication,

whereas

an

experiment

that

identifies

the

location

of

interaction

in

a

detector

could

provide

a

fairly

equal

distribution

of

ampl

itudes

throughout

the

range,

iftus

the

adjustment

of

the

controls

for

the

single

channel

analyzer

and

the

uses

for

its

logical

outputs

wil

l

depend

upon

the

nature

of

the

experiment.

See

the

appl

ications

in

Section

7

for

further

suggestions.

4.2.

FRONT

PANEL

CONTROLS

TIME

RANGE

The

total

range

for

the

time

measurement

can

be

as

short

as

200

nsec

or

as

long

as

10

/jsec.

The

selected

range

wi

l l

be

converted

to

a

0-

to

10-V

range

of

l

inear

outputs.

The

appropriate

range

wi

ll

be

one

that

is

long

enough

to

accommodate

the

slowest

fal

l

time

but

is

as

short

as

possible

within

this

restriction.

INPUT

DISC

The

input

discriminator

must

be

triggered

by

an

input

pulse

in

order

for

its

fall

time

to

be

measured.

The

ampl

itude

of

the

input

pulse

from

the

l

inear

amplifier

is

the

parameter

that

is

measured

by

this

function.

When

the

sl

ide

switch

is

set

at

1

V,

the

10-turn

potentiometer

can

be

set

for

any

level

between

10

and

1000

dial

divisions,

corresponding

to

an

input

ampl

itude

range

of

100

mV

through

10

V.

For

a

more

precise

setting

at

lower

levels

the

sl

ide

switch

can

be

set

at

0.1

V,

and

the

usable

range

for

the

10-turn

potentiometer

is

then

about

100

dial

divisions

through

1000

divisions,

or

about

10

mV

through

100

mV.

When

the

input

discriminator

is

trig

gered,

there

is

a

logic

output

pulse

through

the

rear

panel

BNC

designated

Input

Disc

Output.

WALK

ADJ

The

purpose

of

this

screwdriver

control

is

to

minimize

the

walk

when

measuring

decay

times

for

differing

input

pulse

ampl

itudes.

See

Section

6

for

cali

bration

information.

PSA

TIME

WINDOW

These

two

10-turn

potentiometers

are

the

controls

that

set

the

two

discriminator

levels

of

the

single

channel

analyzer

that

analyzes

the

l

inear

output

signal

of

the

458.

Since

any

selected

time

range

wil

l

be

converted

into

a

0-

to

10-V

linear

output

range,

the

1000

dial

divisions

on

each

potentiometer

are

directly

the

selected

time

range.

Whatever

their

settings

for

any

specific

appl

ication,

a

linear

output

amplitude

that

exceeds

the

Upper

Level

setting

wi

l

generate

a

logic

output

through

the

UL

connector

and

wil

l

inhibit

a

Window

output.

A

linear

output

ampl

itude

that

exceeds

the

Lower

Level

setting

but

does

not

also

exceed

the

Upper

Level

setting

wi

l l

generate

a

Window

output.

5.

CIRCUIT

DESCRIPTION

5.1.

GENERAL

A

block

diagram,458-0101-B1,

is

included

at

the

back

of

this

manual

.

There

are

also

three

schematics,

458-0201-SI

(Sheets

1

and

2)

and

458-0301-SI.

The

fol

lowing

circuit

description

refers

primarily

to

the

block

diagram.

The

ORTEC

458

Pulse

Shape

Analyzer

consists

of

three

basic

functions:

Input

and

Compression

Circuitry,

Dual

Constant-Fraction

Discriminator,

and

a

Time

to

Pulse

Height

Converter.

These

three

basic

functions

lead

to

the

generation

of

a

l

inear

output.

A

single

channel

analyzer

is

also

included

for

logical

analysis

of

the

l

inear

output

ampl

itudes.

The

input

and

compression

circuitry

provides

isolation

and

transforms

the

input

pulse

height

range

of

20

mV

to

10

V

into

a

range

of

100

mV

to

5

V.

The

effective

compression

is

from

500:1

down

to

only

50:1

in

pulse

height

variation.

The

Dual

Constant-Fraction

Discriminator

generates

two

time

markers.

The

first

time

marker

is

generated

at

a

point

on

the

trai

l

ing

edge

of

the

unipolar

input

pulse

when

the

pulse

has

decayed

to

approximately

90%

of

its

peak

ampl

itude.

The

second

marker

is

generated

when

the

input

pulse

has

decayed

to

approximately

10%

of

its

peak

ampl

itude.

The

Time

to

Pulse

Height

Converter

then

measures

the

time

between

the

90%

and

10%

markers

and

stores

the

time

information

on

a

capacitor.

The

voltage

on

the

capacitor

is

strobed,

shaped,

and

routed

to

the

l

inear

output.

This

voltage

is

in

the

range

of

0'to

10

V,

independent

of

the

input

ampl

itude

from

the

linear

amplifier.

The

Single

Channel

Analyzer

views

the

l

inear

output

signal

ampl

itude

and

generates

a

Window

output

at

strobe

time

if

the

output

amplitude

is

between

the

settings

of

the

Lower

Level

and

Upper

Level

controls

(UL

set

higher

than

LL).

If

the

ampl

itude

is

greater

than

the

setting

of

the

UL,

a

UL

logic

output

is

generated

at

strobe

time

and

a

Window

output

is

inhibited.

5.2.

DETAILED

CIRCUIT

DESCRIPTION

The

input

signal

is

attenuated

by

a

factor

of

2

by

R1

and

R2,

and

is

routed

to

the

input

unity-gain

ampl

ifier,

Q1

to

Q6

and

Q45.

Diodes

D1

and

D2

prevent

the

absolute

ampl

itude

of

the

signal

from

exceeding

10

V.

The

signal

at

the

emitter

of

Q45

is

routed

to

a

1-jusec

delay

l

ine

and

to

a

voltage

comparator,

IC1

.

The

purpose

of

the

com

parator

is

to

generate

a

logic

signal

when

the

input

signal

exceeds

+^

V.

When

the

Input

Disc

range

is

set

for

0.1

V,

the

logic

signal

starts

a

one-shot

multivibrator,

IC2A,

B,

and

C,

to

control

the

gain

in

the

compression

network.

For

this

condition

the

initial

gain

of

the

network

is

10

and

it

is

shifted

to

unity

when

the

input

logic

starts

the

one-shot.

The

signal

compressor

is

essentially

a

l

inear

gate

that

routes

the

signal

through

an

inverting

operational

amp

l

ifier

with

a

gain

of

10

if

the

input

signal

does

not

exceed

-1-1

V,

or

through

another

operational

amplifier

with

unity

gain

if

the

input

signal

does

exceed

-i-l

V.

The

decision

on

whether

or

not

the

input

signal

exceeds

the

-i-1-V

level

is

made

as

previously

described

by

IC1.

The

input

signal

is

delayed

1

fisec

by

DLi

and

inverted

by

operational

amp

l

ifier

0A1.

Thus

the

signal

arrives

at

the

compressor

input

after

the

decision

has

been

made

on

what

the

gain

should

be

(see

the

Timing

Diagram,

Fig.

5.1).

The

compressor

gain

is

changed

for

only

the

0.1-V

position

of

the

Input

Disc

switch.

When

the

switch

is

set

at

10

V,

IC2

Is

disabled

and

the

compressor

gain

is

fixed

at

unity.

Assume

that

the

Input

Disc

switch

is

set

at

0.1

V

and

that

the

input

signal

is

less

than

-i-1

V.

IC2C

wil

l

remain

in

its

low

state

of

approximately

zero

volts.

The

current

through

R33

is

routed

equally

through

R32

and

R34.

The

collector

of

Q9

is

at

approximately

-4

V.

The

base

of

transistor

IC3B

is

biased

at

~-3.3

V.

Thus

transistor

IC3A

is

turned

off

and

IC3B

is

turned

on.

Q10

provides

a

constant

current

through

IC3B

that

divides

approximately

equally

through

IC3E

and

IC3F.

For

these

bias

conditions

IC3E

and

IC3F

form

the

differential

input

to

a

high-gain

operational

ampl

ifier

that

includes

Q11

to

Q15.

The

negative

voltage

signal

from

10

of

0A1

is

converted

to

a

current

signal

through

R27

and

generates

a

voltage

signal

across

R28

of

approximately

(R28/R27)Vio,

or

(10K/-

1

KjVio

=

lOVio.

In

other

words,

the

signal

at

10

of

0A1

is

ampl

ified

by

a

factor

of

10

through

the

compressor.

If

a

signal

of

ampl

itude

greater

than

-i-1

V

is

presented

at

the

input,

the

output

of

the

one-shot

multivibrator

IC2C

is

switched

from

its

low

state

to

its

high

state

{~+2

V).

IC3A

is

turned

on

and

IC3B

is

turned

off.

The

input

signal

then

passes

through

R29

and

R30

to

the

compressor

output

with

a

gain

of

unity.

The

one-shot

IC2C

output

at

8

remains

in

the

high

state

for

approximately

8

/tsec

or

until

the

input

signal

has

completely

disappeared.

This

is

dead

time

and

exists

only

for

those

input

pulses

with

ampl

itudes

between

1

and

10

V

when

the

Input

Disc

switch

is

set

at

0.1

V.

The

output

of

the

compressor

circuit

is

ac-coupled

through

C20

and

routed

to

basel

ine

restorer

Q36

to

Q39,

shown

on

schematic

458-0201-SI,

Sheet

2.

This

is

an

active

type

of

dc

restorer

where

the

signal

basel

ine

at

the

base

of

Q37

is

compared

with

the

voltage

at

the

base

of

Q38.

If

the

signal

basel

ine

is

positive

with

respect

to

ground,

Q37

is

turned

on

and

the

current

through

Q36

is

reduced

to

zero.

For

this

condition

Q39

pul

ls

the

basel

ine

back

toward

7"

90%

7

10%

7

Reset

1

TiSec

Signal

Compressor

Input

Signal

Compressor

(X1

Pos

of

Input

Disc

Only)

Baseline

Restorer

Ouptut

Stretcher

Ouptut

Pulse

Stretcher

&

Linear

Gate

Input

ICG

Timing

Comp

IC7

Timing

Comp

Input

Disc.

Output

I

7

90%

7

10%

7

Reset

TPHC

Start

TPHC

Stop

Start

Tunnel

Diode

Memory

Stop

Inhibit

Gate

Stop

Tunnel

Diode

Memory

Conversion

Cap

Voltage

Gate

Width

Generator

Linear

Output

TPHC

Reset

Window

Output

-

0.5

iusec

'1

Msec

1

Msec

b

I

1

UL

Output

(only

if

UL

Disc,

exceeded)

J

L

Fig.

5.1.

458

Timing

Diagram.

zero

volts.

If

the

basel

ine

goes

negative,

Q37

turns

off

and

approximately

3

mA

of

current

flows

through

Q36

to

bring

the

basel

ine

back

toward

zero

very

rapidly.

After

the

baseline

is

restored,

the

signal

is

routed

into

three

level

discriminators,

IC5, IC6,

and

IC7,

and

to

a

pulse

stretcher,

Q16

through

Q29.

When

the

signal

goes

positive,

stretcher

capacitor

C28

is

charged

by

the

current

through

Q25.

The

voltage

on

C28

is

control

led

by

the

closed-loop

unity-gain

amplifier,

Q23

to

Q28,

which

feeds

the

C28

voltage

back

to

the

gate

of

the

input

differential

pair.

If

the

voltage

on

C28

tries

to

exceed

that

of

the

input

signal,

Q17

turns

on

and

Q16

turns

off

to

reverse-bias

Q19

and

Q20.

With

Q19

and

Q20

turned

off,

the

voltage

on

C28

ceases

to

increase.

All

this

is

the

action

of

the

stretcher

before

the

input

reaches

its

peak.

When

the

input

signal

reaches

its

peak

and

starts

to

decrease,

diode

D24

reverse-

biases.

The

charge

on

C28,

which

is

equal

to

the

peak

amplitude

of

the

input

pulse,

wil

l

remain,

providing

that

the

gate

transistor,

Q22,

is

turned

off

before

the

peak

has

been

reached.

The

voltage

on

C28

is

routed

to

the

output

of

the

stretcher

and

to

the

base

of

Q32

through

the

unity-gain

ampl

ifier,

Q23

to

Q28.

The

gate

signal

for

the

stretcher

is

derived

from

the

level

discriminator,

IC5.

The

positive

signal

comes

from

the

baseline

restorer,

Q36

to

Q39,

to

the

IC5

discriminator.

The

ampl

itude

of

the

signal

that

is

required

to

change

the

IC5

discriminator

state

from

low

to

high

is

determined

by

the

Input

Disc

10-turn

front

panel

control

and

by

the

range

that

is

set

by

its

slide

switch

(a

function

not

shown

on

the

block

diagram).

The

Input

Disc

control

sets

a

positive

voltage

on

2

of

IC5.

When

the

signal

exceeds

the

pin-2

voltage,

IC5

changes

states

from

high

to

low

and

generates

a

negative

output

pulse.

This

negative

pulse

is

inverted

through

IC4A

to

trigger

a

one-shot

multivibrator,

IC4B

and

IC4C.

The

multivibrator

output

is

routed

through

IC4D

and

transistor

Q29

to

the

base

of

Q22,

the

stretcher

gate

transistor.

The

gate

signal

reaching

the

base

of

Q22

is

negative

enough

to

turn

Q22

off.

The

output

of

IC4C

remains

in

the

positive

state

until

the

system

reset

is

generated

(see

Fig.

5.1).

The

one-shot

multivibrator,

IC4B

and

IC4C,

also

triggers

a

second

0.5-/tsec

one-shot

multivibrator,

IC2D,

Q7,

and

Q8.

The

output

at

QBE-

is

routed

to

the

rear

panel

BNC

connector.

Input

Disc

output.

The

stretcher

output

is

routed

to

a

l

inear

gate,

Q32

to

Q35,

which

is

normally

closed.

The

same

signal

that

opened

the

stretcher

is

routed

to

the

base

of

Q34,

which

is

normal

ly

on.

When

Q34

is

turned

on,

its

current

holds

the

base-emitter

junction

of

Q32

reverse-biased,

and

this

prevents

the

stretcher

signal

from

reaching

2

of

IC6

and

IC7.

Before

Q34

is

turned

off

by

the

gate

signal,

a

negative

voltage

is

forced

on

the

base,

of

Q33

which

is

transferred

to

2

of

IC6

and

IC7.

This

causes

discriminators

ICG

and

IC7

toassumea

low

voltage

state

before

gate

Q34

is

opened.

When

the

gate

signal

turns

Q34

off,

the

stretcher

signal

is

routed

through

Q32

and

Q34

to

2

of

ICG

and

IC7.

The

stretcher

signal

at

the

emitter

of

Q33

has

an

ampl

itude

with

reference

to

ground

that

is

approximately

90%

of

the

peak

ampl

itude

of

the

signal

presented

at

3

of

ICG

and

IC7.

The

stretcher

signal

is

presented

to

ICG

without

attenuation,

but

this

signal

is

attenuated

further

so

that

the

stretched

signal

at

2

of

IC7

is

approximately

10%

of

the

peak

ampl

itude

of

the

signal

present

at

3.

The

outputs

of

both

discriminators

remain

in

the

low

state

until

a

time

after

the

peak

of

the

input

signal

.

As

the

input

goes

beyond

the

peak

and

decays

toward

zero,

there

is

a

time

when

the

voltage

on

3

of

ICG

is

equal

to

the

90%

stretched

signal

on

2

of

ICG,

and

ICG

changes

from

its

low

state

to

its

high

state

as

the

pin-3

signal

goes

further

negative.

This

generates

the

first

timing

signal

to

start

the

time

measurement

of

the

input

signal

.

The

second

time

marker

is

generated

by

IC7

as

the

signal

voltage

on

3

goes

more

negative

than

the

10%

stretched

signal

on

its

2.

The

output

transition

of

IC7

is

then

from

its

low

state

to

its

high

state,

the

same

as

previously

described

for

ICG.

This

signal

wil

l

stop

the

time

measure

ment

of

the

input

signal

.

The

output

signals

from

both

ICG

and

IC7

are

differ

entiated,

and

the

positive

transitions

are

fed

through

separate

fast

ampl

ifiers

to

the

start

and

stop

inputs

of

the

Time

to

Pulse

Height

Converter.

The

start

time

marker

that

originated

at

ICG

is

routed

through

fast

ampl

ifier

Q1

and

Q2

(see

schematic

458-0301-S1)

to

the

start

input

tunnel

diode

D2

of

the

TPHC.

The

start

signal

triggers

D2

to

its

high

state,

where

it

remains

until

a

system

reset

is

gen

erated.

The

high

state

of

D2

is

routed

through

the

amp

l

ifier

Q3

to

Q6

to

the

conversion

clamp

Q7

to

Q9

and

to

the

stop

inhibit

clamp

Q17.

When

Q17

turns

on,

current

through

R42

is

rerouted

from

tunnel

diode

D10

through

Q17

and

this

sets

the

proper

bias

current

so

that

the

stop

signal

wil

l

be

able

to

change

the

state

of

D10.

The

start

signal

from

D2

turns

Q5

on.

This

forward-biases

Q7

to

turn

off

Q8

and

conversion

clamp

Q9.

The

conversion

current

source

is

normally

on,

providing

current

to

the

clamp

transistor

Q9E.

Before

the

clamp

Q9

is

turned

off,

the

conversion

capacitor

is

clamped

to

near

zero

volts.

When

the

clamp

is

removed,

the

conversion

current

is

rerouted

from

Q9E

to

the

conversion

capacitors

C7

to

C9.

The

voltage

on

the

conversion

capacitor

is

a

ramp

that

increases

in

a

negative

direction.

As

the

conversion

capacitor

is

being

charged,

the

stop

signal

comes

through

the

fast

ampl

ifier

Q15,

Q16

to

cause

D10

to

change

from

a

low

state

to

a

high

negative

state.

This

transition

is

routed

through

ampl

ifier

Q18

and

Q19

to

a

gate-width

generator

and

to

the

conversion

gate

transistor

Q21

.

The

D10

transition

causes

Q21

to

saturate

and

to

take

all

of

the

conversion

current

that

normal

ly

flows

through

Q22.

At

this

time

the

voltage

on

the

conversion

capacitor

ceases

to

increase.

The

capacitor

charge

is

then

proportional

to

the

time

interval

between

the

start

and

stop

signals.

This

stored

signal

is

routed

through

a

unity-gain

FET

amplifier

Q10

to

Q14

and

Q36.

The

output

at

Q36E

is

fed

to

a

fast

operational

amplifier,

OAl.

Operational

ampl

ifier

OAl

serves

two

purposes.

It

inverts

the

converter

signal

and

serves

as

an

output

l

inear

gate.

The

operational

amplifier

has

two

input

signals,

through

R88

and

R89,

and

two

feedback

paths,

R95

and

R96.

In

the

normal

state

before

a

gate

signal

is

generated,

the

current

from

the

-I-24-V

source

flows

through

034

and

R89

to

forward-bias

D14

and

clamp

the

pin-10

output

of

OAl

to

a

negative

voltage

equal

to

approximately

one

diode

junction.

10

and

the

base

of

Q37

remain

constant

and

inde

pendent

of

the

conversion

voltage

unti

l

a

gate

signal

turns

034

off.

The

gate

signal

originates

from

the

stop

input.

The

stop

input

triggers

a

gate

width

generator

O20

and

Q30

to

032.

The

gate

width

generator

produces

a

gate

signal

at

the

base

of

033

that

is

negative

and

is

about

1

/tsec

wide.

This

negative

signal

turns

033

on

and

034

off.

When

034

turns

off,

the

current

that

normally

forward-biases

D14

is

reduced

to

zero

and

the

conversion

voltage

signal

at

Q36E

causes

a

current

to

flow

through

013

in

the

direction

that

forward-biases

013.

The

current

through

R96

while

034

is

turned

off

is

proportional

to

the

conversion

voltage.

Thus

a

positive

signal,

~1

jjisec

wide,

wi

ll

appear

at

the

base

of

037

and

wi

l

be

proportional

to

the

conversion

voltage

during

the

gate

time.

When

034

is

turned

off

and

the

gate

signal

is

not

present,

the

voltage

on

the

base

of

037

wil

l

be

approximately

zero.

The

positive

conversion

signal

is

routed

through

a

buffer

unity-gain

amplifier

037

to

O40

and

presented

to

the

Linear

Output

connector

on

the

front

panel

.

The

conversion

signal

at

the

036E

output

of

the

FET

ampl

ifier

is

fed

to

a

single

channel

analyzer

(SCA).

The

lower

level

discriminator

of

the

SCA

is

IC1

and

the

upper

level

discriminator

is

IC2.

IC1

is

normally

in

the

high

state

and

IC2

is

in

the

low

state.

If

the

lower

level

discriminator

101

is

switched

to

the

low

state

by

the

signal

on

2

and

the

output

of

the

upper

level

discriminator

102

remains

in

the

low

state,

both

Q41

and

Q42

wi

l l

be

turned

off.

If

Q41

and

Q42

are

both

off

at

the

time

that

the

gate

pulse

turns

Q43

off,

a

positive

transition

wil

l

occur

at

the

base

of

Q49

to

trigger

the

one-shot

Q49

to

Q52

and

to

thus

produce

a

standard

positive

logic

output

through

the

Window

con

nector

on

the

front

panel

.

The

logic

condition

that

produces

a

Window

output

requires

that

the

conversion

signal

be

greater

than

the

lower

level

control

setting

and

less

than

the

upper

level

control

setting.

If

the

conversion

signal

ampl

itude

exceeds

the

setting

of

the

upper

level

control,

Q42

is

turned

on

and

this

prevents

a

Window

output

from

being

generated

at

the

gate

signal

time.

102

is

then

in

a

high

state,

and

a

positive

transition

wil

l

occur

when

the

gate

pulse

turns

Q53

off.

This

positive

transition

triggers

the

one-shot

Q45

to

Q48

to

produce

a

standard

logic

pulse

through

the

UL

output

on

the

front

panel

.

A

logic

pulse

through

the

UL

connector

wil

l

be

furnished

for

each

conversion

signal

that

exceeds

the

UL

control

setting,

including

any

conversion

signal

that

exceeds

the

selected

time

range.

When

an

overrange

occurs,

there

wi

l l

be

no

l

inear

output

but

the

UL

logic

signal

wi

ll

be

strobed

and

wi

l l

furnish

an

output.

The

TPHC

is

reset

to

its

initial

state

by

the

trai

ling

edge

of

the

gate

width

generator

Q32

or

by

an

overrange

signal

from

the

conversion

capacitor

through

Q28

and

Q29.

Either

of

these

signals

wi

l

trigger

reset

generator

Q24

to

Q27.

When

Q26

of

the

reset

generator

is

turned

off,

D2

resets

to

its

initial

low

state;

this

resets

the

conversion

clamp

Q9E

to

zero

volts,

and

Q17

is

turned

off

to

restore

the

stop

inhibit

clamp

and

reset

D10

to

its

low

state.

D10

resets

the

conversion

gate

Q21

to

the

off

state.

A

reset

signal

from

the

reset

generator

is

also

fed

back

to

the

base

of

Q30

to

reset

the

one-shot

that

follows

the

input

discriminator.

The

reset

of

this

one-shot

closes

the

stretcher

gate

and

the

linear

gate

between

the

stretcher

and

IC6and

IC7.

%

6.

MAINTENANCE

6.1.

TESTING

PERFORMANCE

The

fol

lowing

material

wi

l l

aid

in

instal

l

ing

and

checking

out

the

458.

It

consists

of

information

on

front

panel

controls,

waveforms,

test

points,

and

output

connectors.

Test

Equipment

The

following,

or

equivalent,

test

equip

ment

is

needed:

1.

ORTEC

419

Pulse

Generator

2.

ORTEC

410

Ampl

ifier

3.

Tektronix

547

Oscilloscope

4.

100f2

attenuator

box

Preliminary

Procedures

Before

making

the

functional

checks,

take

the

following

preliminary

steps:

1.

Visually

check

module

for

possible

damage

due

to

shipment.

2.

With

power

off,

plug

module

into

an

ORTEC

401/402

Series

Nuclear-standard

Bin

and

Power

Supply,

and

check

for

proper

mechanical

al

ignment.

3.

Switch

ac

power

on,

and

check

the

dc

power

voltage

at

the

test

points

on

the

402

Power

Supply

control

panel

.

Functional

Checks

The

following

checks

should

be

made

to

assure

the

correct

function

of

the

458:

1.

Connect

the

direct

output

of

the

pulse

generator

to

the

osci

lloscope

trigger.

Connect

the

attenuated

output

of

the

pulse

generator

to

the

input

of

the

ampl

ifier.

Place

all

attenuator

switches

on

the

pulse

generator

to

the

Out

position

except

one

X2

switch.

Adjust

the

pulse

generator

output

and/or

amplifier

gain

control

to

achieve

an

amp

l

ifier

output

pulse

height

of

approximately

10

V,

single

delay

l

ine.

2.

Connect

the

ampl

ifier

output

to

the

458

input.

Set

the

458

Time

Range

at

0.2

/tsec

and

the

multipl

ier

at

XI

.

Set

the

Input

Disc

10-turn

dial

at

100

and

the

multipl

ier

at

10

V.

Set

the

Upper

Level

and

Lower

Level

10-turn

dials

at

100.

Connect

the

linear

output

to

the

osci

l

loscope

and

observe

an

output

approximately

7

V

in

amplitude.

Chang

ing

the

Time

Range

switch

in

0.2-/.isec

increments

from

0.2

to

1

.0

should

decrease

the

output

ampl

itude

by

1/2, 1/3, 1/4,

1/8

(approx.).

Changing

the

multiplier

switch

to

XI0

should

decrease

the

output

ampl

itude

by

a

factor

of

10

(approx.).

3.

Connect

the

Upper

Level

output

to

the

oscil

loscope

and

observe

a

0.5-/isec

pulse

approximately

5.0

V

in

ampl

itude.

Adjust

the

Upper

Level

dial

unti

l

the

UL

output

disap

pears.

Connect

the

Window

output

to

the

osci

lloscope

and

observe

a

0.5-/isec

pulse

approximately

5.0

V

in

ampl

itude.

Adjust

the

Lower

Level

dial

unti

l

the

Window

output

disappears.

The

UL

and

LL

dial

readings

should

be

in

direct

proportion

with

the

Linear

output

amplitude

±20

small

dial

divisions.

For

example,

if

the

Linear

output

has

an

ampl

itude

of

7

V,

the

UL

and

LL

dials

should

read

700

±20

smal

l

dial

divisions.

6.2.

CALIBRATION

ADJUSTMENTS

DC

Adjustments

1.

Adjust

R121

unti

l

the

voltage

at

the

base

of

Q35

(458-0201

board)

is-4.2

V.

This

potentiometer

is

located

near

the

rear

panel

on

the

458-0201

board.

2.

Adjust

R29

until

the

voltage

at

the

gate

of

Q11

(458-0301

board)

is

zero

volts

±10

mV.

This

potentiom

eter

is

located

at

the

bottom

of

the

458-0301

board.

3.

Adjust

R32

unti

l

the

voltage

at

TP3

(458-0301

board)

is

zero

volts

±10

mV.

This

potentiometer

is

located

approximately

midway

on

the

458-0301

board.

4.

Adjust

R92

until

the

Linear

output

voltage

is

zero

volts

±2

mV.

This

potentiometer

is

located

at

the

top

of

the

458-0301

board

and

near

the

front

panel

the

operational

amplifier.

AC

Adjustments

1.

For

adjustment

of

R4

and

R46

for

minimum

offset

at

TP1,

fol

low

the

procedure

outl

ined

in

Section

3.3.

2.

Connect

a

probe

to

the

col

lector

of

Q3

(458-0301

board)

and

adjust

R66

until

the

signal

starts

half

firing;

then

back

off

two

turns.

This

potentiometer

is

located

midway

and

to

the

rear

of

the

458-0301

board.

3.

Connect

a

probe

to

the

col

lector

of

Q18

(458-0301

board)

and

adjust

R46

unti

l

the

signal

disappears;

then

back

off

four

turns.

This

potentiometer

is

located

at

the

top

of

the

458-0301

board

and

the

rear

panel

.

These

last

two

adjustments

set

the

tunnel

diode

discrimina

tor

sensitivity

for

the

start

and

stop

inputs

to

the

TPFIC

(458-0301

board).

6.3.

WALK

ADJUSTMENT

Using

the

same

procedure

as

in

"Functional

Checks,"

insert

a

100^2

attenuator

box

between

the

amplifier

output

and

the

input

to

the

458.

Connect

the

Linear

output

to

the

oscil

loscope

with

the

waveforms

centered

on

the

osci

llo

scope

face.

Set

the

Time

Range

to

0.2,

the

multipl

ier

to

XI;

the

Input

Disc

to

100,

and

the

multipl

ier

to

0.1

V.

10

1

.

Switch

in

X10

attenuation

of

the

attenuator

box

and

adjust

C61

for

minimum

change

in

the

output

voltage

as

observed

on

the

osci

lloscope.

C61

is

located

right

above

the

operational

ampl

ifier

on

the

458-0201

board.

2.

Switch

in

X400

attenuation

and

adjust

the

front

panel

walk

adjustment

for

a

minimum

voltage

change.

3.

Switch

in

X20,

X40,

XI00,

and

X200

attenuation.

The

maximum

voltage

change

of

any

of

these

attenuations

should

be

no

more

than

0.5

V,

or

±0.25

V.

6.4.

TROULESHOOTING

If

a

malfunction

has

been

identified

and

the

associated

portions

of

the

458

circuits

have

been

located,

check

the

typical

dc

voltages

for

the

suspected

components

by

comparison

with

the

list

in

Table

6.1.

Note

that

these

are

typical

levels

observed

under

the

fol

lowing

conditions:

Time

Range

set

at

0.1

,

multiplier

set

at

XI,

Input

Disc

set

at

10

V,

UL

and

LL

dials

set

at

10,

Walk

Adj

set

at

midrange.

TABLE

6.1.

TYPICAL

DC

VOLTAGES

TIME

RANGE:

MULTIPLIER:

.2

XI

INPUT

DIS:

RANGE:

100

0.1

V

UL

AND

LL:

INPUT:

010

None

0201

BOARD

0301

BOARD

CHECKPOINT

DC

VOLTAGE

CHECKPOINT

DC

VOLTAGE

Qlb

0

Q25e

-2.98

Qle

-0.63

Q25b

-2.33

Qlc

+

10.6

Q27e

+21.7

Q2e

-0.649

Q27c

+0.57

Q2b

-0.039

Q28b

+0.58

Q2c

+13.5

Q29e

Q3b

+

12.8

Q29b

+2J8.

.

Q3c

+0.56

Q30e

+7TT

Q4e

+22.0

Q30b

+

10.7

Q6e

-8.9

Q30c

0

Q6b

-8.3

Q31b

+10.9

Q6c

-0.725

Q31c

+0.85

Q45c

-11.0

IC4

3

+0.293

OAl

10

+0.055

IC5

3

0

1

+

11

.8

2

+0,08

9

-23.3

7

+2.15

13

-11.0

8

+

10.0

14

0

4

-5.47

ICl

3

-0.39

Q7e

0

2

+0.65

Q7b

+0.74

8

+10.1

Q7c

+0.07

4

-5.71

Q8e

+0.07

7

+2.09

Q32b

-0.04

tC2

9

+

1.82

Q32e

+0.564

8

+0.236

Q33e

-0.071

Q9e

+0,726

Q34e

-4.96

Q9b

0

Q34b

-4.27

Q9c

-4.58

Q34c

+0.183

QlOe

-13.3

Q35c

QlOb

-12.6

Q36e

+

12.2

QIOc

-5.0

Q36b

+

11

.5

Qlle

-13.3

Q37e

+0.61

Qllb

-12.7

Q38e

-0.614

Qllc

-0.746

Q38b

0

Q12e

+13.2

Q39e

-11.6

Q12b

+

12.6

Q39b

-11.0

Q12c

+0.594

Q39c

-0.52

IC3

1

+20.4

ICO

3

0

11

-4.22

2

-0.047

Q13b

+

13.2

7

-0.47

Q13c

+23.2

8

+

10.1

Q16g

-0.04

4

-5.78

Q16d

+20.1

IC7

3

0

017g

-0.04

2

-0.027

017d

+21.3

7

+2.18

018e

-1.92

8

+10.2

018b

-1.25

4

-5.40

Q19e

+20.7

Q40b

0

Q19c

+22.9

Q40e

+0.763

021c

+0.169

Q40c

+0.18

Q21b

-2.32

Q41b

+0.109

021

e

-2.06

Q42b

0

Q22b

-1.37

Q42e

+0.765

022c

-0.980

Q42c

+0.20

023g

-0.03

Q43b

+0.108

023d

+1.98

Q44e

+3.67

023s

+21.1

Q44b

+4.35

024s

+23.2

CHECKPOINT

DC

VOLTAGE

CHECKPOINT

DC

VOLTAGE

Qle

-0.57

Q32c

-0.132

Qlc

0

Q33e

+11.5

Q2e

-0.60

Q33b

+11.4

Q2b

0

a33c

0

Q2c

+

1.17

Q34b

+

10.8

Q3e

+0.52

Q34c

+5.51

03b

-0.048

Q35e

0

Q3c

-11.9

Q35b

0

Q4b

-0.20

OAl

7

+0.193

Q4c

-2.22

10

-0.484

Q5e

-11

.4

1

+22.9

Q5c

+0.72

9

+23.3

Q6b

-10.7

11

+22.9

Q6c

-11.1

13

-10.5

Q7e

+0.72

.Pin

14

-0.521

Q7b

-2.47

Q37e

-0.60

Q7c

0

Q37b

+0.017

Q9c

+

1.38

037c

+10.8

Q9e

+0.01

Q38b

0

Q12e

+

11.6

Q38c

+

13.5

Q12b

+

10.9

Q39b

+

12.8

Q12c

+4.42

Q39c

+0.59

Q36b

-0.74

Q40c

+23.2

Q36c

-10.7

Q40e

0

Q15e

-0.54

ICl

7

+0.83

Q15c

0

8

+9.17

Q16e

-0.54

4

-5.60

Q16b

0

IC2

7

-0.593

Q16c

+

1.19

8

+10.4

Q17e

0'

4

-5.86

Q17c

+1.79

Q41e

0

Q18e

.

+0.50

Q41b

+0.83

Q18b

+0.013

a4ic

+0.05

Q18c

-10.7

Q42e

0

Q19b

-0,20

042b

-0.593

Q19c

-4.8

043e

-0.05

Q20c

0

Q43b

+0.69

Q21c

0

Q44e

0

Q22b

-10.0

Q44b

0

Q24e

+

10.8

Q44c

+1.54

024b

+

10.2

Q45e

0

Q24c

-10.1

Q45c

+

10.8

025b

+11.4

Q46b

0

025c

0

Q47e

0

Q26b

-10.1

Q47b

+0:75

Q26c

-2.17

Q47c

+0.086

.

Q27b

-10.7

Q48e

0

Q27c

0

Q49e

0

Q28e

+2,49

Q49b

0

Q28b

+3.19

Q49c

+

10.8

Q29c

+8.07

'

Q50b

0

030e

0

Q51e

0

Q30c

-5.07

Q51b

-+0.767

Q31e

0

Q51c

+0.089

031

b

-0.13

Q52e

0

032e

0

Q53e

0

Q32b

-0.94

Q53b

+0.64

11

7.

APPLICATIONS

7.1.

NEUTRON-GAMMA

DISCRIMINATION

WITH

STILBENE

AND

LIQUID

SCINTILLATORS

Theory

Neutrons

and

gammas

produce

l

ight

scinti

l

lation

in

NE-213,

NE-218,*

and

Sti

lbene

detectors

with

signifi

cantly

different

decay

characteristics.

The

10%

to

90%

rise

time

(tR)

of

the

integrated

l

ight

from

all

the

scintil

lators

is

approximately

130

nsec

when

excited

with

neutrons

and

approximately

10

nsec

when

excited

with

gamma

rays.'**

The

scintil

lation

is

not

a

simple

expon

ential,

as

is

il

lustrated

by

Kuchnirand

Lynch,'

but

consists

of

a

combination

of

at

least

four

components,

as

il

lustrated

by

their

results

shown

in

Table

7.1.

Table

7.1

SCINTILLATOR

MEAN

LIFE

TIME^

{nsec)

MEAN

DECAY

TIME^

(nsec)

NO.

OF

PHOTOELECTRONS

PER

keV

ENERGY

LOSS^

Tj

Stilbene

0.1

4,05

33

270

2.3

NE

213

1

.66

3.16

32.3

270

1.7

NE

213M

1.34

5.41

30.5

285

1.9

NE

218

1.76

3.58

36.5

288

2.0

Anthracene

-

_

—

3.6

Nal

(TI)

—

8.8

^

For

energy

transfer

from

solvent

to

solute.

^First

3

components

by

the

light

output

in

organic

scintillators.

^Represents

loss

in

the

scintillator

when

coupled

to

an

RCA-8575

photomultiplier

with

good

light

collection.

Three

parameters

determine

the

abi

l

ity

to

distinguish

between

gammas

and

neutrons:

the

total

number

R

of

photoelectrons

produced

at

the

cathode

for

a

given

energy

of

excitation,

the

shape

f(t)

of

the

l

ight

scintil

lation

for

both

neutrons

and

gammas,

and

the

photoelectron

level

/

at

which

the

pulse

shape

information

is

deduced.

If

one

assumes

that

the

neutron

and

gamma

can

be

characterized

with

an

effective

single

decay

time,

the

probabil

ity

distribution

function

for

the

/th

photoelectron

out

of

a

total

of

R

photoelectrons

is

given

by

the

statistical

order

equation^

g(t)

R\

{/■-D!

(/?-/)!

[1

The

fol

lowing

analysis

is

based

on

a

first-order

approxi

mation

of

the

pulse

shape.

If

more

exact

results

are

desired,

refer

to

the

work

of

Kuchnir

and

Lynch.

Assuming

an

effective

exponential

for

the

scinti

l

lation

permits

one

to

obtain

a

better

understanding

of

how

the

three

parameters

affect

the

neutron-gamma

separation.

The

mean

time

for

the

/th

photoelectron

is

given

by^

T

In

R

R-j

=

T

In

1

-

F

(2)

*

Nuclear

Enterprises,

Ltd.,

San

Carlos,

California.

**See

"References"

at

the

end

of

this

section.

where

F

is

the

ratio

of

j/R

or

the

fraction.

The

variance

in

time

of

the

/th

photoelectrons

is

given

by

a.

=

J

(3)

The

width

of

the

time

distribution

varies

directly

with

t

and

the

photoelectron

level

/,

but

inversely

with

R,

the

total

number

of

electrons.

Therefore

as

the

fraction

at

which

the

time

information

is

derived

increases

toward

unity,

the

separation

of

the

neutron

and

gamma

increases,

but

the

time

resolution

is

poorer.

The

object

is

to

choose

a

photoelectron

level

that

wi

ll

minimize

the

overlap

of

rise

time

of

the

neutron

and

gamma-ray

signals.

Kuchnir

and

Lynch'

by

using

the

measured

distributions

and

a

more

general-order

equation

predicted

the

optimum

separation

to

exist

when

the

fraction

of

pulse

height

used

is

between

0.8

and

0.9.

The

458

was

designed

to

take

advantage

of

the

optimum

trigger

point.

Consider

a

typical

example

where

Eqs.

(2)

and

(3)

can

be

used

to

predict

the

separation

of

neutrons

and

gamma

rays.

Assume

the

fol

lowing

experimental

conditions:

1.

The

neutron

pulse

height

is

equal

to

the

gamma-ray

pulse-height

equivalent

of

100

keV

electron

energy

or

500

keV

neutrons.

2.

The

scintil

lator

is

NE-213

on

an

RCA-8575

photo-

multiplier

producing

1.7

photoelectrons/keV

of

electron

energy.

3.

The

effective

decay

of

NE-213

is

130

nsec

for

neutrons

and

10

nsec

for

gamma

rays.

The

variance

for

the

neutron

rise

time

is

calculated

by

"n

"

''10%

*^90%

-'^90%

/

(4)

In

Eq.

(4)

/?

is

1.7

x

100

keV

or

170;

/

=

0.9

x

170,

or

152.

Substituting

the

values

of

R

and

k

in

Eq.

(4)

yields

=

(56x10-')"

n

(tw)

(i?)

56

x

10"'

X

0.22

=

12.2

nsec.

At

=

2.35

X

12.2

=

29

nsec

(FWHM),

12

For

the

gamma

ray

.

I4,5x.0-'I'E

k=Q

a

4.5

X

10

X

0.22

=

0.95

nsec,

y

At

=

0.95

X

2.35

=

2.25

nsec

(FWHM).

The

mean

separation

would

be

f

„

-

f

y

=

120

nsec.

The

calculated

results

are

shown

in

Fig.

7.1a,

with

the

shapes

assumed

to

be

approximately

Gaussian.

Figure

7.1b

i l

lustrates

what

happens

to

the

abi

lity

to

separate

the

neutrons

and

gamma

rays

at

approximately

350

keV

neutron

energy

or

70

keV

equivalent

electron

energy.

The

assumptions

used

to

obtain

Eqs.

(1)

and

(2)

are

repre

sentative

of

first-order

approximations

and

are

presented

here

to

illustrate

the

effect

of

various

parameters

on

the

neutron-gamma

separation.

Gammas

/

\

Neutrons

—

2.2

nsec

/

J

<a)

Gammas

Neutrons

3.5

nsec

40

nsec

(b)

Fig.

7.1.

Calculated

Response

for

(a)

100

keV

and

(b)

70

keV

Electron

Equivalent

Energies

Deposited

in

NE-213.

L_

Proper

Application

of

the

458

The

458

Pulse

Shape

Analyzer

measures

the

90-10%

fall

time

of

the

l

inear

signal

presented

to

its

input.

To

obtain

the

best

time

resolution

a

fast

unipolar

delay-line-shaped

main

amplifier

should

be

used.

The

rise

time

of

the

unipolar

delay-l

ine-

shaped

pulse

should

not

be

greater

than

100

nsec

for

best

results,

and

the

ampl

ifier

should

have

low

noise

characteristics

and

be

operated

at

low

gain.

Figure

7.2

shows

the

process

by

which

a

delay-line-shaped

pulse

is

produced.

Notice

that

the

time

information

is

inverted

in

the

process

of

producing

the

trai

ling

edge

of

the

pulse.

The

time

information

that

occurs

at

the

10%

point

on

the

input

signal

occurs

at

the

90%

level

on

the

trailing

edge,

and

the

time

information

occurring

at

the

90%

level

on

the

input

signal

is

transformed

to

the

10%

level

on

the

trail

ing

edge.

Input

To

Main

Amplifier

Delayed

and

Inverted

Signal

DL-Shaped

Signal

Out

of

Main

Amp.

Fig.

7.2.

Single

Delay

Line

Shaped

Signal.

Consider

the

effect

of

ampl

ifier

noise

on

the

neutron-

gamma

separation

for

a

wide

dynamic

range

of

operation.

Assume

the

fol

lowing

ampl

ifier

noise

characteristics:

Gain

=

10

Rise

time

=

100

nsec

Input

equivalent

noise

(Av)

=

70

x

10"^

V

The

rise-time

noise

is

given

approximately

by

At

=

yjl

G

2.3bAvl{v/tpi),

(5)

where

Av

is

rms

noise

at

the

input,

v

is

the

signal

level

of

interest,

and

tpt

is

the

rise

time.

The

factor

exists

be

cause

of

two-level

measurements

and

the

2.35

converts

the

rms

value

to

FWHIVl.

For

the

example

above

the

time

resolution

at

the

minimum

pulse

height

of

20

mV

is

At

=

\/2

(10)

(2.35)

70

X

10"®/(20

x

lO'VlOO

x

10"')

=

11.5

nsec

(FWHM).

Many

delay-line

amplifiers

have

good

noise

characteristics

for

high

gain,

but

the

noise

increases

very

rapidly

as

the

gain

is

lowered.

From

the

above

example

it

becomes

evident

that

I

13

the

ampl

ifier

must

be

operated

at

minimum

gain

and

must

have

good

noise

characteristic

before

neutrons

and

gammas

can

be

separated

over

the

entire

ranqe

of

20

mV

to

10

V.

The

ORTEC

460

is

the

only

known

delay-l

ine-shaped

amplifier

with

these

characteristics.

The

458

should

be

operated

in

the

X0.1

V

input

discriminator

range

for

the

400:1

dynamic

range.

In

this

position

1000

divisions

is

equivalent

to

100

mV

at

the

input

to

the

458.

The

458

input

discriminator

control

should

be

set

above

the

input

noise

but

not

lower

than

100

divisions

on

the

control

.

The

setup

procedure

in

Section

3.3

should

be

careful

ly

followed

when

using

the

458

in

the

X0.1

V

range.

In

addition,

the

Walk

Adj

should

be

adjusted

for

optimum

walk

over

the

entire

dynamic

range

of

interest.

-

NEUTRON-GAMMA

DISCRIMINATION

EXPERIMENT

NEUTRON

ENERGY

3

■

0.5

MeV

GAMMA

ENERGY

600

keV

COUNT

RATE

=

25,000

cts/sec.

-

GAMMA

:

^^NEUTRON

—.

A

typical

block

diagram

for

a

neutron—gamma-ray

dis

crimination

system

is

shown

in

Fig.

7.3.

The

458

Pulse

Shape

Analyzer

(PSA)

time

window

is

set

on

the

gamma

peak

and

above

any

extraneous

peaks

in

the

time

spectrum

caused

by

amplitude

saturation

of

the

main

amplifier.

A

UL

logic

pulse

is

generated

for

al

l

events

with

rise

times

greater

than

the

UL

control

setting.

Figure

7.4

is

a

typical

spectrum

of

the

458

output

with

a

plutonium-beryll

ium

source.

ORTEC

456

HIGH

VOLTAGE

POWER

SUPPLY

ORTEC

265

PM

BASE

£

^

ORTEC

z

2

ORTEC

458

113

460

PULSE

SHAPE

PREAMP

AMPLIFIER

ANALYZER

WINDOW

OUTPUT

GAMMA

ROUTING

UL.

OUTPUT

NEUTRON

ROUTING

NEUTRONS

GAMMAS

ENERGY

SIGNAL

Fig.

7.3.

Block

Diagram

for

a

Typical

Neutron-Gamma

Separation

Experiment.

Fig.

7.4.

Neutron-Gamma

Rise

Time

Spectrum.

The

suggested

block

diagram

for

the

proportional

counter

system

for

neutron-gamma

discrimination

is

shown

in

Fig.

7.6.

The

460

delay-line-shaped

ampl

ifier

should

have

a

2-;usec

shaped

line

for

optimum

performance.

The

Lower

Level

control

of

the

window

should

be

set

just

below

the

peak

corresponding

to

the

neutron

rise

time

(see

Fig.

7.5),

and

the

UL

control

should

be

set

just

above

the

neutron

peak.

The

majority

of

the

events

causing

a

window

output

wi

l l

correspond

to

neutrons,

and

the

events

causing

a

UL

output

will

correspond

to

gamma

rays.

NEUTRON

EVENT

GAMMA-RAY

EVENT

RISE

TIME

(Asec)

Fig.

7.5.

A

Typical

Neutron

and

Gamma

Rise

Time

Spectrum

from

a

Proton

Recoil

Proportional

Counter.

7.2.

NEUTRON-GAMMA-RAY

DISCRIMINATION

IN

PROPORTIONAL

COUNTERS

Gamma-ray

discrimination

in

proton-recoi

l

proportional

counters

has

been

accomplished

by

several

experimenters.''

Recently

Dbu'

reported

excel

lent

separation

of

neutrons

and

gammas

at

energies

of

10

keV

and

lower.

The

basic

principle

is

that

the

proton

recoi

ls

from

the

neutrons

produce

a

very

short

ionization

path,

whereas

the

electrons

produced

by

the

gammas

wil

l

occur

over

a

relatively

long

path

in

the

chamber.

Thus

the

rise

time

associated

with

the

neutrons

wi

ll

be

less

than

and

also

better

defined

than

the

rise

time

of

the

gamma

event.

This

is

il

lustrated

in

Fig.

7.5.

ORTEC

459

ORTEC ORTEC

Z

D

ORTEC

HIGH

109

PC

460

458

VOLTAGE

PULSE

SHAPE

POWER

PREAMP

AMPLIFIER

ANALYZER

SUPPLY

PROPOR-

TIONAL

ORTEC

427A

DELAY

AMPLIFIER

WINDOW

OUTPUT

NEUTRON

ROUTING

U.L.

OUTPUT

GAMMA

ROUTING

LINEAR

INPUT

Fig.

7.6.

Neutron-Gamma

Discrimination

System

with

Proportional

Counter.

14

7.3.

RISE-TIME

DISCRIMINATION

IN

X-RAY

PROPORTIONAL

COUNTER

Several

experimenters

have

demonstrated

the

abil

ity

to

distinguish

between

soft

x-rays

and

signals

producing

Compton

electrons

by

observing

the

difference

in

the

2-Msec

SHAPING

8-(.isec

TIME

RANGE

rise

time

of

the

generated

signals.

10-13

Lewyn

in

a

recent

publ

ication

attributed

the

major

portion

of

background

in

proportional

counters

to

high-energy

charged

particles

and

to

Compton

electrons

from

gamma

rays

interacting

with

chamber

wal

ls.

Both

sources

of

background

are

reported

to

have

significantly

longer

col

lection

times

than

soft

x-rays.

A

system

for

distinguishing

between

the

x-ray

events

and

the

non-x-ray

background

is

shown

in

Fig.

7.7.

To

set

the

system

shown

in

Fig.

7.7

the

pulse

shape

distribution

of

2

lisec

SHAPING

ORTEC

459

HIGH

VOLTAGE

POWER

SUPPLY

ORTEC

109PC

PREAMP

ORTEC

451

AMPLIFIER

ORTEC

458

PULSE

SHAPE

ANALYZER

WINDOW

OUTPUT

PROPOR

TIONAL

COUNTER

ORTEC

427A

DELAY

AMPLIFIER

LINEAR

INPUT

MCA

Fig.

7.7.

Background

Reduction

System

for

an

X-Ray

Proportional

Counter.

the

x-rays

and

the

background

must

be

determined.

Once

the

distribution

of

pulse

shapes

is

known,

the

PSA

window

of

the

458

can

be

properly

adjusted.

The

suggested

system

for

setting

the

PSA

window

is

shown

in

Fig.

7.8.

In

this

system

the

pulse

shape

spectrum

should

first

be

accumulated

from

the

458

by

exposing

an

x-ray

source

to

the

chamber

with

the

MCA

in

the

nongated

mode.

The

x-ray

pulse

shape

spectrum

should

be

stored

in

one-half

of

the

memory,

and

then

in

the

second

half

of

the

memory

a

pulse

shape

spectrum

should

be

accumulated

by

exposing

a

gamma-ray

source

(^°Co)

to

the

chamber

with

the

MCA

still

In

the

ungated

mode.

If

the

two

spectra

can

be

overlapped,

a

spectrum

such

as

that

shown

in

Fig.

7.9

should

result.

At

this

point

the

decision

must

be

made

on

where

to

set

the

ORTEC

459

ORTEC ORTEC

ORTEC

HIGH

109

PC

451

458

VOLTAGE

PULSE

SHAPE

POWER

PREAMP

AMPLIFIER

ANALYZER

SUPPLY

PROPOR

TIONAL

WINDOW

OUTPUT

GATE

INPUT

'

4.INEAR

INPUT

Fig.

7.8.

Suggested

System

for

Setting

the

PSA

Window

of

the

458.

BACKGROUND

4

Msec

I

8

Msec

I

Fig.

7.9.

Pulse

Shape

Spectrum

Taken

with

Proportional

Counter

System

Shown

in

Fig.

7.8.

PSA

window.

The

Lower

Level

control

should

clearly

be

set

between

the

lowest

peak

and

the

x-ray

peak.

The

Upper

Level

control

then

must

be

set

somewhere

be

tween

the

x-ray

peak

and

the

background

peak.

The

background

efficiency

rejection

can

never

be

100%;

so

other

parameters

of

the

experiment

should

dictate

how

much

of

the

background

to

reject

with

some

sacrifice

of

x-ray

counting

efficiency.

After

the

decision

is

made

as

to

what

point

on

the

pulse

shape

spectrum

the

window

should

set,

the

MCA

should

display

the

unfolded

x-ray

pulse

shape

spectrum.

Place

the

MCA

in

the

gated

mode

and

expose

the

x-ray

source

to

the

chamber.

The

lower

level

and

upper

level

controls

can

now

be

adjusted

to

preselected

points

in

the

spectrum

by

observing

the

minimum

channel

and

maximum

channel

being

stored

in

the

analyzer.

Once

the

PSA

window

is

set,

the

gated

energy

spectrum

(Fig.

7.7)

can

be

taken.

EG&G ORTEC 458 Service manual

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