STJ Quick Start Guide v 2.01
April 1, 2021
Page 22
REGION OF INTEREST (ROI) AND CALIBRATION
The ROI tool below the histogram is used to select peaks of interest and calibrate the gain on a per-
channel basis.
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Note that for multi-channel systems we recommend using the GainMatch tool instead of the
ROI tool to calibrate all active channels at once
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Edit the Lower and Upper fields to place an ROI that encloses the peak of interest.
Alternatively, use the mouse right-button context menu to place a cursor on the peak and then
select Auto Adjust ROI over that cursor.
•
Enter the desired energy in the Calib. (KeV) field and press Calibrate ROI to automatically
adjust the Preamp Gain setting for the selected channel. The peak should jump to the desired
energy when new data is acquired.
Fig 12: Here is a similar MCA histogram to the one displayed in Fig 11, but this time the peak has been calibrated to 1 keV and the
STJ Relay has been enabled, i.e. WITHOUT additional noise from the ‘dummy detector’ circuit. Note that now the Mean is 999.98
eV, and the FWHM is 2.86 eV.
GAINMATCH PANEL
The GainMatch tool provides an automated sequence runs through several ROI calibration iterations for
all active channels. We recommend using this tool to quickly calibrate gain on a per-channel basis in multi-
channel systems.
•
We recommend checking the Optimize Gain box. If this box is unchecked, the tool will attempt
to calibrate only the Digital Gain while keeping the Analog Gain constant, which can lead to
unexpected results if the original peak energy is significantly different than the desired energy.
