Cyclotron Institute TAMU - Radiation Effects Testing Facility

CONTROL SOFTWARE USERS GUIDE

(Written by Vladimir Horvat - updated on October 28, 2021)

Set Options

The purpose of this dialog box is to set the user options (preferences and tolerances).

Preferences:

The ion detector counts measured over consecutive one-second intervals can be automatically logged in the run file during each run.
If the previous check box is checked, diagnostic messages normally included in the log file will be duplicated in the run file for easier synchronization with the ion detector counts.
Contents of the run file (run report) can be displayed automatically as the run ends. If so selected, the file will be opened by Notepad in a separate window.
Contents of the run file (run report) can be printed automatically as the run ends. Please keep in mind that two separate electronic copies of each run report are kept on the Seuss computer. An additional copy to a flash drive can easily be made at any time, so that printing hardcopies may not be necessary.
If you are an experienced user of the program and do not want to be bothered by the information presented in pop-up windows (message boxes) that require only the acknowledgement, you may opt out. If so selected, the same information will be either displayed on the status bar or not displayed at all. Keep in mind that a message displayed on the status bar will be overwritten by the next one and could easily go unnoticed.
If you are an experienced user of the program and do not even want to be bothered by the warnings presented in a pop-up windows (message boxes) that require only the acknowledgement, you may opt out. If so selected, the same warnings will be either displayed on the status bar or not displayed at all. Keep in mind that a message displayed on the status bar will be overwritten by the next one and could easily go unnoticed. Opting out of pop-up warnings is NOT RECOMMENDED.
You may opt in to verify that the installed hardware is responding properly to the program.
You may force Seuss to use the legacy method (pre-2020) to calculate energy loss and range. For this option to take effect, you must also take one of the seven actions that trigger recalculation of these quantities. These actions will be listed in a pop-up window when this option is selected or unselected.

Tolerances:

When the beam uniformity is below the specified value, it is displayed on white background in the Seuss window.
When the beam central shift is above the specified value, it is displayed on white background in the Seuss window.
When the beam axial gain is above the specified value or below its reciprocal value, it is displayed on white background in the Seuss window. The default value is 2.00, which is appropriate in most cases. However, in a run with a high-flux proton beam from the K150 cyclotron, the outer ion detectors are usually set to measure a much smaller fraction of the ions compared to the central detector, and the central detector may or may not be in use. This is done in order to maintain accurate dosimetry and to preserve the ion detectors. Under these circumstances, large values of axial gain are to be expected.
Calibration factor is a statistically more reliable value of axial gain. When it differs from the current value of axial gain, by a percentage larger than the one specified here, it is displayed on white background in the Seuss window. At the time of pre-run diagnostic this is reported by means of a pop-up window (message box) as a warning. A large discrepancy between the axial gain and the calibration factor indicates that the reported beam fluence may not be accurate. However, occasional large discrepancies between the axial gain and the calibration factor are to be expected when the beam flux is low, because in that case the axial gain is subject to large statistical fluctuations. The default tolerated mismatch value is 20%, which is appropriate in most cases. However, in a run with a high-flux proton beam from the K150 cyclotron, a much larger mismatch between the axial gain and the calibration factor is to be expected in certain modes of operation.

Options related to the beam flux are specified by separately specifying the mantissa and the power of ten. The result in standard notaion is displayed in the following read-only box.

When the beam flux is below the specified level, it is displayed on white background in the Seuss window. At the time of pre-run diagnostic this is reported by means of a pop-up window (message box) as a warning.
When the beam flux is above the specified level, it is displayed on white background in the Seuss window. At the time of pre-run diagnostic this is reported by means of a pop-up window (message box) as a warning.
When the beam flux is below the specified level, a pop-up window (message box) with a warning is displayed at the time of pre-run diagnostic. It should be noted that the beam parameters, such as uniformity, central shift, axial gain, flux, and fluence are determined based on the number of ions detected by the ion detectors each second. That number is distributed according to the Poisson distribution, with standard deviation equal to the square root of the mean value (i.e., 1% at 10000 counts per second, 10% at 100 counts per second, or 100% at 1 count per second). Low beam flux results in the low number of counts in the ion detectors each second, which in turn results in large statistical fluctuations of the beam parameters that are calculated based on these numbers.
When the number of detected ions per second is above the specified level, the upstream shutter (S1) will close after 60 seconds of idle time in order to reduce the damage to the ion detectors. For the same reason, the Control Positioning window will open at run end. Namely, performance of the ion detectors deteriorates as a function of the number of detected ions. At some point the detectors no longer count the ions with 100% efficiency and have to be replaced. The procedure may take as long as one hour, provided that the spare detectors are available. Rebuilding the detectors may take much longer than that.

The remaining options are related to positioning.

When the coordinate (S) of the selected degrader does not have an integer value, it means that the degrader is not centered around the beam axis. As a result, its frame may stop a fraction of ions that would otherwise reach an ion detector. Consequently, the measured beam parameters may be inaccurate. If S deviates from its closest integer value by more than the specified amount, a pop-up window (message box) with a warning is displayed at the time of pre-run diagnostic.
For the measurements in the vacuum chamber, the minimum acceptable apertures of the horizontal and vertical slits can be specified. Narrow slits may result in excessive slit scattering and an excessive spread of energy loss of the ions. When the actual values are below the specified values, a pop-up window (message box) with a warning is displayed at the time of pre-run diagnostic.

Buttons:

Click the Apply button to accept the input values.
Click the Cancel button to ignore any changes made.
Click the Defaults button to replace the specified values of the parameters with their default values. The default values are deemed to be reasonable. They should be altered only to address a specific need or to adapt to some extraordinary circumstances. Changing the parameters just to avoid the pop-up windows (message boxes) at the time of pre-run diagnostic is not recommended.
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