The MCA Widget

Figure 12.1 shows the MCA menu.

Figure 12.1: The MCA Widget

Here is an explanation of the elements:

 Sample time: If set to -1, the sample time is unlimited.

 Update after: The time after which the MCAs are read-out and displayed.

 Total time: The total sample time. This value is resetted by a Clear command.

 The Devices frame

 MCA1: This menubutton specifies the device which parameters are displayed and changed by the widgets in this frame. It does not select an MCA for the measurement. This id done by the Select devices widget of the Options menu.

 2048: The number of channels.

 Window: [0, 2047]: The windows limits. This parameter is used for the display only.

 ROI-1: [650, 750]: The first region of interest. You find the total number of counts, the signal and the background in adjacent label widgets. The background is calculated from a linear interpolation of the first and last point of the region of interest.

 The Counters frame

 C1 (COUNTER_I0): The counters are selected by Select Scan Devices of the Options menu of the toplevel widget. The counter contents are written to the output files. If counters are aliases of MONITOR_MCA, MONITOR2_MCA or MONITOR3_MCA then Online makes sure that these symbols enter the output file, even if other aliases exist.

 Doris: The Doris current [mA]. Depending on the status of the flag Use digital Doris current the value is read from a server via the network or it is a converted analog signal.

 The Output parameters frame

 File name: The current file name. The generic part can be changed by pushing the adjacent button.

 Comment: The comment line is displayed in the graphics screen and written to the output file.

 The Button line

 Start: Starts a MCA run. The button changes to Stop as long as the run is active.

 Log: Switch between linear and logarithmic scales.

 Cursor: Invokes the cursor. It can be used to set the regions of interest.

 Clear: Resets a MCA spectrum. Changes the name of the output file.

 Write: Creates an output file.

 Display:

Options: The menu is displayed in figure 12.2. The items are:

 Select devices: A widget for the selection of the MCA timer and the MCAs which are used.

 Include motors: A flag that determines whether the motor positions are written to the output files.

 Use digital Doris current: If enabled, the Doris current is read from a server via the network. Otherwise an analog signal can be digitized. The associated counter is defined by the symbol DORIS_MCA. The symbol C2C_DORIS_MCA stores the conversion factor which needed for the calculation counts to mA (I[mA] = Counts/C2C/SampleTime).

 Calibration: Invokes a menu that relates channel numbers to energy values.

Figure 12.2: The MCA Options Menu

Figure 12.3 shows the widget that allows you specify the displayed devices.

Figure 12.3: The MCA Select Devices Menu