Chapter 5 Web-Based Operations
102
Lynx DSA User's Manual - 9240227J
Coarse Gain
Sets the amplifier’s Coarse Gain. The product of the
Coarse Gain
,
Fine Gain
, and
Input Attenuator
represent the total amplification gain. Coarse Gain can be selected
from 2 to 430.54. Default is 4. Coarse Gain cannot be changed while spectrum
stabilizer is active.
As a general guideline when establishing a working energy range, the best signal to
noise characteristics are obtained when the preamplifier gain (if selectable) is set as
high as possible, Attenuator setting is off (no input/gain attenuation), Fine Gain set
as low as possible, and Coarse Gain set as high as possible.
Fine Gain
Sets the amplifier’s Fine Gain. Fine Gain setting ranges from 0.80000 to 1.20000.
Default is 1.00000. Fine Gain cannot be changed while spectrum stabilizer is active.
Refer to the Coarse Gain setting (above) for additional information.
LLD Mode
The Lower Level Discriminator (LLD) selects the minimum acceptance level for the
input energy signal to be processed. The LLD Mode can be set to
Automatic
or
Manual
. With
Automatic
selected the LLD cutoff is automatically optimized just
above the spectral noise threshold.
Manual
allows the LLD cutoff to be set manually
using the LLD (%) setting as a percentage of the input’s full-scale range.
The LLD (%) manual setting is only used when LLD Mode is set to Manual.
Important:
For some low energy applications even the manual LLD cutoff
may still prevent the processing of extremely low energy
events. For this purpose, in additional to the Manual LLD
Mode and LLD(%) setting, additional parameters are exposed
in the Digital Filter settings to provide extended flexibility
specifically for low energy applications. Please refer to the
Low-Energy Applications
on page 109 for more details.
LLD (%) manual setting
The LLD manual setting is in effect when the LLD Mode is set to
Manual
, and
establishes the minimum acceptance level for the input energy signal to be processed
as a function of percentage of the Input Size, or full scale of the energy range. Range
is 0.0% to 100.0%.
ULD (%) manual setting
The ULD manual setting is in effect at all times; it establishes the maximum
acceptance level for the input energy signal to be processed as a function of
percentage of the Input Size, or full scale of the energy range. Range is 0.0% to
110.0%, however spectral storage above 100.0% is prevented by the storage logic.
Polarity
The Polarity setting sets the detector signal polarity for the rear panel’s ENERGY
input as
Positive
or
Negative
. Typically, the Input Polarity must be set to the polarity
of the preamplifier's output. Default is
Positive
.
