EG&G ORTEC 553 Manual de operação e serviço - Página 6
Procurar online ou descarregar pdf Manual de operação e serviço para Instrumentos de medição EG&G ORTEC 553. EG&G ORTEC 553 16 páginas. Timing single-channel analyzer
Imprimir páginaORTEC 553 TIMING SINGLE-CHANNEL ANALYZER
1.
DESCRIPTION
1.1.
PURPOSE
The ORTEC 553 Timing Single-Channel Analyzer pro
vides a versatile group of related signal derivation func
tions. It can be used as either a single-channel analyzer
or as an Integral discriminator. The principal output,
furnished as both a NIM-standard fast negative signal
and a NIM-standard slow positive signal, can be used for
accurate timing information. In addition, a separate NIM-
standard slow positive output is furnished separately for
each response by the upper level discriminator in the
module.
The output signal is internally generated and its timing
relative to that of the input signal is derived accurately,
using a time recognition technique called Constant-
Fraction Discrimination. This technique provides unex
celled timing on either unipolar or bipolar signals which
displaces <±3 ns for an input amplitude variation as great
as 100:1. This eliminates the degradation of time resolu
tion for varying input amplitudes that is characteristic
of leading-edge time recognition.
The 553 accepts either unipolar or bipolar input pulses
having either PC or delay-line pulse-shaping waveforms.
It examines the amplitude of each input pulse and
generates appropriate output pulses separately for SCA
and ULD responses. The SCA output is delayed from the
time of recognition (at 50% of full amplitude on the
trailing edge of the input positive waveform). The delay is
adjusted on the front panel between 100 ns and 1.1 ns so
that the output time can be normalized to its application.
The instrument is designed to meet the recommended
interchangeability standards of ERDA Report TID-20893
(Rev). An ORTEC 401/402 Series Bin and Power Supply
provides all the necessary power through the rear panel
power connector. All signal levels and impedances are
compatible with other ORTEC NIM modules.
1.2.
MODES OF OPERATION
The 553 has a front panel switch that selects the integral
mode of operation or either of two types of differential
single-channel analysis modes. For Normal operation,
each of the discriminator levels is adjusted independ
ently through the full dynamic range of 0 to 10 V. For
Window operation, the range of the lower level control is
0 to 10 V and the range of the upper level (or window)
control is the adjusted lower level plus 0 to 1 V.
Integral Mode Operation
In the integral mode, the 553
generates an output through both the Pos Out and Neg
Out connectors on the front panel if the input pulse
amplitude exceeds the adjusted lower level threshold;
the range is 0 to 10 V.
Normal Mode Operation
In the normal mode, the 553
generates an output through both the Pos Out and Neg
Out connectors on the front panel if the input pulse
amplitude exceeds the adjusted lower level but does not
exceed the adjusted upper level threshold. In this mode,
each threshold is adjusted independently in the range of
0 to 10 V, and the upper level must be set higher than the
lower level to permit the SCA outputs to be generated.
Window Mode Operation
In the window mode, the 553
generates an output through both the Pos Out and Neg
Out connectors on the front panel if the input pulse
amplitude exceeds the adjusted lower level threshold,
but by an amount that is less than the adjusted window
width. The range of the lower level control is 0 to 10 V,
and the range of the upper level control is 0 to 1 V above
the lower level. This mode is especially adapted to high-
resolution spectroscopy because the very narrow win
dows that are required can be obtained easily and
reproducibly.
1.3.
OUTPUT PULSE TIMING
The Pos Out and Neg Out pulses from the 553 are
generated at a delay (with internal strobe) following the
precise constant-fraction time recognition, which occurs
at 50% of the peak amplitude on the trailing edge of the
input pulse. The delay interval is adjustable through a
range of 0.1 to 1.1 ^iS. The front panel Delay control is a
1-turn potentiometer that is marked in linear increments
to read the adjusted delay directly.
For any mode of operation, a signal is furnished through
the UL Out connector on the rear panel when the upper
level discriminator is triggered on the leading edge of the
input signal. Each of these outputs is a NIM-standard
positive signal that can be used for any desired external
application.
1.4.
LOWER LEVEL REFERENCE
A rear panel 2-position locking toggle switch selects
either the front panel Lower Level control or the voltage
signal applied through the rear panel LL Ref connector
as the reference level for the lower level discriminator.
This permits flexibility in operation, where an external
reference source can furnish the lower level threshold
from a stepped- or sliding-voltage source to automati
cally sweep the SCA response through a spectral range
of 0 to 10 V.
The selected source for the Lower Level Reference is
effective for all three operating modes.