Hardware Options
Lynx DSA User's Manual - 9240227J
113
Manual Ratio
The Gain Ratio can be manually entered when the Ratio Mode is set to
Manual
, or
automatically calculated by the Lynx when the Ratio Mode is set to
Automatic
. The
Gain ratio value is interpreted by the stabilizer as the ratio to maintain between the
two windows (ratio = upper window / lower window). For instance, a value of 1.000
would be appropriate for a pure Gaussian peak
Status
The Status is a read-only indicator that displays the current status reported by the
Lynx’s stabilizer logic. Status will indicate “Fault” when a stabilizer fault condition
is detected.
Correction
The Correction value is a read-only parameter that reports the current level of
correction being applied to the system gain as a percentage of the allowed full-scale.
Draw Stabilization Region
Selecting “On” will paint the two stabilization windows on the PHA spectrum display
to help the user fine-tune the proper location for the stabilization. This option should
be disabled once the setup for stabilization has been completed.
Reset button
During the normal course of operation, if the stabilization algorithm attempts to set a
correction value that is beyond its allowable range (
±
10% for NaI range or
±
1% for
Ge range), the Lynx will assert an over/under-range fault. Additionally, the Lynx will
switch the stabilizer mode from
On
to
Hold
.
Under normal temperature variations the amount of gain compensation necessary to
maintain a stable storage location should be well within the allowed stabilization
range. An over/under-range fault may be an indication of faulty electronics and thus
requires operator intervention. The fault will remain asserted until (a) the operator
acknowledges the fault by pressing the Reset, or the Stabilizer Mode is turned to
Off
.
Typical Stabilizer Setup Sequence
The stabilizer should be turned On only after all other adjustments have been made.
For typical operation the Ratio Mode should be set to
Automatic
.
In brief, when the stabilizer in the Lynx is first turned
On
, and acquisition has been
enabled, the stabilization algorithm establishes a reference by taking snapshots of the
data relationship between the upper and lower sampling windows. Thereafter, the
algorithm is designed to maintain the data relationship between two windows as close
to the reference as possible by manipulating the internal gain control within an
allowable range.
A typical sequence for setting up the spectrum stabilizer is as follows:
1.
While acquiring in PHA, adjust the coarse gain, fine gain, detector's high
voltage (for NaI), etc. to select the desired energy range for PHA. For best
results, the settings should be selected so that the Fine Gain is at or near its
mid-range.
