EG&G ORTEC 552 Manuale operativo e di servizio - Pagina 7
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Stampa la pagina1.2. LOWER-LEVEL REFERENCE
A rear panel toggle switch selects either the front panel
Lower-Level control or the voltage signal furnished
through the rear panel LL Ref connector as the reference
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 automatically sweep the SCA
response through a spectral range. The selected source
for the lower-level reference is effective for all three
operating modes.
1.3.
OUTPUT STROBE
A rear panel toggle switch selects either an internal
strobe, based on a delayed trigger derived from the input
signal, or a strobe pulse that is furnished through the
rear panel Strobe In connector to determine when the
channel B outputs are to be generated. This has no effect
on the channel A output, which is generated promptly
at the constant-fraction trigger. When external strobe
is used, the input signal must be received within 10 yus
after the trigger time or the channel B outputs will not be
generated. When the internal strobe is used, the Delay
control on the front panel can be adjusted to set the de
lay time from the trigger point to the channel B output in
the range of 0.1 through 1.1 ^s.
1.4. CONSTANT-FRACTION TECHNIQUE
Both output channels derive information that uses the
constant-fraction technique, which is an ORTEC devel
opment. It consists of comparing the amplitude along
the decay of a pulse to a selected fraction of the peak
amplitude of the same pulse. Thus, through a wide range
of input pulse peak amplitudes, the timing information
is obtained with precision.
The reference fractions that are available in both output
channels indicate the percentage of amplitude decay
from the peak toward the ground reference level. Thus
a setting of 10% in either channel selects a trigger point
at 90% of the peak amplitude for that channel, or a setting
of 20% selects a trigger point at 80% of the peak ampli
tude.
2. SPECIFICATIONS
2.1. PERFORMANCE
INPUT DYNAMIC RANGE
200:1.
PULSE-PAIR RESOLVING TIME Output pulse width
plus Delay (selected by front panel Delay control or by
external strobe input) plus 200 ns for NIM-standard fast
negative output or plus 740 ns for NIM-standard slow
positive output. Minimum resolving time for negative
output, 260 ns; for positive output, 800 ns.
THRESHOLD TEMPERATURE INSTABILITY ^0.005%/
°C of full scale, 0 to 50° 0.
DISCRIMINATOR NONLINEARITY
^±0.25% of full
scale (Integral) for each discriminator.
DELAY TEMPERATURE INSTABILITY ^±0.01 %/°C of
full scale, 0 to 50°C, measured at full scale.
DELAY NONLINEARITY ^±2% of delay range.
WINDOW WIDTH INCONSISTENCY <±0.1% variation
of full-scale window width over the 0-to 10-V linear range.
MINIMUM INPUT THRESHOLD
40 mV,
TIME SHIFT vs PULSE HEIGHT (Walk) (Specified for
Channels A and B at 50% fraction.)
Walk (ps)
Input
Oynamic Range
System 1*
System II**
10:1
±500
±2000
50:1
±1500
±2500
100:1
±2000
±3000
200:1
±2500
±8000
*Uslng the bipolar output of an ORTEC 460 Amplifier, single
delay-line mode, integrate <0.1
with delay line 1 ^s.
**Using an ORTEC 472A Amplifier, unipolar output, 0.5 mS
shaping.
2.2. CONTROLS
UPPER LEVEL Front panel 10-turn potentiometer deter
mines the window width (0 to +1 V) in the Window mode
or the Upper Level (0 to +10 V) in the Normal and Integral
modes (not used to determine SCA outputs during Inte
gral mode operation).
LOWER LEVEL Front panel 10-turn potentiometer ad
justable from 40 mV to 10 V; when the rear panel LL Ref
switch is set for Int, determines the threshold setting for
the Lower-Level discriminator; when the LL Ref switch is
set at Ext, this control is ineffective.
MODE Front panel 3-position locking toggle switch
selects one of three operating modes:
INT (Integral) LL sets a single discriminator threshold
(40 mV to 10 V) and UL is not used to determine an SCA
response.
NORM (Normal) UL and LL are independently adjust
able levels; UL range 0 to +10 V; LL range 40 mV to 10 V.
WIN (Window) LL sets the baseline level (40 mV to 10
V) and UL sets the window width (LL to LL+1 V).
ATTN
Front panel 3-position locking toggle switch
selects an attenuation factor for the input signals:
XI
Input signals not attenuated.
X10 Input signals are attenuated by a factor of 1/10.
X100 Input signals are attenuated by a factor of 1/100.
DELAY Front panel 10-turn potentiometer for continu
ously adjustable delay for channel B output, using inter
nal strobe; range 0.1 to 1.1 ms.
WALK ADJ (A and B) Independent front panel screw
driver adjustments on front panel for precise setting of
walk compensation in each output channel. The Walk
Adj B control is ineffective when the B Fraction switch
is set at its Bl position.
LL REF MODE Rear panel 2-position locking toggle
switch selects either the front panel LL control or the