MCA

Invokes the multi channel analyzer menu. The menu supports the readout of 8 ADCs. Each ADC has its own calibration constants, regions of interest an and window limits. The supported devices are the MCA_8701 module (VME), which servers as a histogramming memory for the 8701 and 8715 ADCs of Canberra, and the LeCroy 3512 ADC (CAMAC) with the histogramming memory.

mca [/exec] [/...]

If the qualifier /exec is supplied, the measurement is executed without passing control to the menu.

The /doris_digital qualifier directs Online to read the Doris current from the Web. An averaged value is also written to the output file.

The MCA menu is controlled by various parameters. They can be specified interactivly, by qualifiers or by symbols. Qualifiers have higher precedence than symbols. The qualifier names and the corresponding symbols are related in the following way, e.g.: the counter for the Doris current can be supplied as qualifier "/_doris=c12" or as symbol "doris_mca=c12" (The symbol definitions should be done in exp_ini.exp). Notice that the qualifier starts with a "_" and that the symbol ends with "_MCA". The symbols and qualifiers are described below, together with the menu items.

The menu is displayed in table 14.10.

Table 14.2: The MCA Menu

 

                              * MCA MENU * 
  Status:              Idle            Total Time:             0             
  Elapsed Time:        0               Dead Time[%]:           0           
  Sample_Time_MCA:     -1              Remaining:              0             
  Update Time:         1               Refresh Cycle:          5 
  Scale Factor:        1.25            Scale Type:             linear     

  ADC:       MCA1                      Counts:      0       
  X_Min:     1         Max: 8192      
  Roi_1 Min: 1         Max: 8192       Cnts/Bg/Net: 0        /0        /0       
  Roi_2 Min: 1         Max: 8192       Cnts/Bg/Net: 0        /0        /0       
  Calibration: 
  Channel 1: 0     Energy 1: 0         Channel 2: 0       Energy 2: 0         

  Counts Monitor:  0        /0         Doris [mA]: 0              
  File Name:       SCAN_MCA_0002       CDT [%]:    0                
  Generic Name:    scan_mca            Include Motor Positions:    Yes        
  Comment:                                                           
  SPECTRA> |                                                  |
-------------------------------------------------------------------------------
  PF1 - Start/Stop,  PF2 - Store,      PF3 - Zoom,      PF4 - Exit            
  KP_Enter - Cursor, KP0 - Display,    KP5 - Clear MCA, KP_Period - Toggle ADCs
  KP7 - Set x-win.,  KP9 - Reset x-w., KP1 - Calibrate, KP3 - Reset Calibration
  F1  - Set Roi-1,   F2  - Reset Roi-1,F3/F4 - ~ Roi-2, F5  - Toggle Counts/Cps

The description of the menu items follows. Qualifiers and symbols, that predefine menu parameters, are given in parentheses. Let's look at an example: The sample time can be set by overtyping the corresponding menu item or it can be supplied as a qualifier, e.g.:

mca/_sample_time=5

or the sample time can be given by a symbol. The file /online_dir/exp_ini.exp is the right place for the symbol definition:

sample_time_mca = 5

If the MCA menu is used interactivly, only some symbols are needed. The qualifiers have been provided to control the MCA operation in automatic routines (/exec).

 Status
Can be idle or busy. The state is changed by PF1.

 Total Time
The total data collection time since the program start or the last clear command.

 Dead Time
The dead time in per cent. It is calculated from the elapsed time and the time that the timer was active.

Output files contain the live-time, which is live = real - deadtime. With real-time being the total gate time.

 Sample Time MCA
(/_sample_time=..., sample_time_mca)
The data collection time that is used, if the user presses PF1. If it is set to -1, there is no time limit and the measurment is controlled by PF1 only.

ONLINE uses a timer (/_timer=timer_id, timer_mca) to gate the ADC. The timer can be dummy.

If /_life_time=nsec (_lt) is specified instead of /_sample_time, online does a dead time correction after nsec seconds expired. That means, the timer is restarted with time_corr = nsec*(100/(100-ratio_cdt[%]) - 1).

 Remaining
The number of seconds that still need to be counted down.

 Update Time
(/_update_time=...)
The time between two updates.

 Refresh Cycle
(/_refresh_cycle=...)
The number of updates before the graphics screen is refreshed. The default is 5.

 Scale Factor
The scale factor is used for the y-axis when the mca_scan is auto-scaled. The default is 1.25 providing 25% room for updates between the screen is refreshed.

 Scale Type
`Linear or logarithmic. The default is linear.

 ADC
(/_adc=adc_id, adc_mca)
VME: The name of a MCA board. Up to 8 ADCs may be specified to MCA, by qualifiers (/_adc2=..., /_adc3=..., etc.) or symbols (adc2_mca, adc3_mca, etc.).

CAMAC: The name of the LeCroy 3512 ADC. The specification of the memory is also needed (/_memory=memory_id, memory_mca).

In general the ADCs are selected by symbol definitions in /online_dir/exp_ini.exp, e.g.:

adc_mca = mca1
sample_time_mca = -1
channels_mca = 1024
timer_mca = t1

These definitions are sufficient to start the MCA menu for a single ADC. The sample time -1 means that the MCA runs until it is stopped by pressing PF1.

The key KP_PERIOD toggles through the list of ADCs.

 X_Min, X_Max
(/_x_max=..., x_max_mca, ~min~)
The x-window. The default is the total range. The values can be overwritten or they can be set with the cursor. The cursor function is called by KP_ENTER. The user has to set two marker. The window limits are updated with KP7. The key KP9 resets the x-window to the default.

If the window limits are specified by hand, by overtyping the menu items, the screen has to be refreshed by KP0 before the new values are in effect.

 ROI_1, ROI_2
The regions of interest. They can be specified by hand or with markers. The keys F1 and F3 set the ROIs, F2 and F4 reset them. The menu displays the total counts in the regions of interest, the background and the net counts. The background is calculated by drawing a line from the first to the last point of a region of interest.

 Calibration
After supplying c1, c2, e1, e2 an ADC may be calibrated by pressing KP1. KP3 resets the calibration. C1 and c2 may be set with the cursor.

 Monitor Counts
(/_monitor=counter_id, monitor_mca)
(/_monitor2=counter_id, monitor2_mca)
The contents of the counters monitor_mca and monitor2_mca.

 Doris
(/_doris=counter_id, doris_mca)
The DORIS current, measured by counter DORIS_MCA. The menu displays the current current value. ONLINE creates the symbol current_doris_mca to store the DORIS current which is averaged for sample_time_total_mca seconds.

 CDT
(/_cdt=counter_id, cdt_mca,
/_a_c2t_cdt=xval, a_c2t_cdt_mca
/_b_c2t_cdt=xval, b_c2t_cdt_mca
The counter CDT_MCA measures the composite deadtime. The constants a_c2t_cdt_mca and a_c2t_cdt_mca convert the counts to seconds: dead_time = (counts - gate*offset)*b_c2t_cdt + gate*a_c2t_cdt.

 File Name
The name of the SCANs that store the data consist of a generic part and a number. ONLINE determines the generic part by translating the symbol generic_mca_name. The default generic name is scan_mca. The number is incremented after the MCA is cleared. It is also incremented, if the STORE routine is called more that once between two clears.

 Include Motor Positions
(/_include_motors=1 or 0)
If toggled to yes, the motor positions are included in the output file.

 Comment
(/_comment=...)
A line of comment which is written to the output file.

 Keypad keys The meaning of the keys is described below. Their names can also be entered as a SPECTRA command (KP, is KP_COMMA and ENTER is KP_ENTER).

 PF1
Starts/stops the MCA

 PF2
Produces an output file. The qualifier /store triggers the output, if MCA is run in the /exec mode.

 PF3
Enters the zoom function. The window is shifted by the left- and right-arrow, the size of the window is changed by the up- and down-arrow. The window limits remain valid when the zoom function returns.

 PF4
Exit

 Ctrl-W
Refreshes the alpha screen.

 KP_ENTER
Calls the cursor routine. Markers can be set that are the input for Calibrate, New x-window or New ROI.

 KP0
Refreshes the graphical screen.

 KP5
Clears the MCA. The data set number is incremented. Window limits and regions of interest stay as they are.

 KP_PERIOD
Toggles through the available ADCs.

 KP1
Calibrate: Uses channel-1,energy-1,channel-2 and energy-2 to calculate a new scale for the x-axis. The calibration constant are stored in preserved symbols (cal_c1_$adc\_name$, cal_e1_$adc\_name$, cal_c2_$adc\_name$, cal_e2_$adc\_name$).

 KP3
Resets the calibration.

 KP7
Sets the x-window with markers. Markers have been set by the cursor.

 KP9
Resets the x-window limits.

 F1
Uses the markers to set the 1$^{st}$ region of interest.

 F2
Resets the 1$^{st}$ region.

 F3
Uses the markers to set the 2$^{nd}$ region of interest.

 F4
Resets the 2$^{nd}$ region.

The following symbols are involved:

 adc_mca
adc_mca2
...
The ADCs, for VME the device names of the multichannel analyzer cards, e.g.: MCA1. At most 8 different ADCs can be used.

 cal_c1_$adc\_name$
cal_c2_$adc\_name$
cal_e1_$adc\_name$
cal_e2_$adc\_name$
The calibration constants. They are optional. The symbols are created by ONLINE. They are preserved.

 cdt_mca
Counter that measures the composite dead time.

 a_c2t_cdt_mca
b_c2t_cdt_mca
The constants a_c2t_cdt_mca and a_c2t_cdt_mca convert the counts to seconds: dead_time = (counts - gate*offset)*b_c2t_cdt + gate*a_c2t_cdt.

 channels_mca
One of 256, 512, 1024, 2048, 4096, 8192. Applies to all ADCs.

 counts_monitor_mca, counts_monitor2_mca
The monitor counts, created by ONLINE.

 current_doris_mca
The DORIS current, averaged over a run, in mA (factor 5000), created by ONLINE.

 doris_mca
An optional counter that measures the DORIS current.

 generic_mca_name
Used by ONLINE to create the file name, default SCAN_MCA.

 interrupt_mca
Is set to '1', if an /exec MCA run has been interrupted by pressing the space bar. Otherwise the symbol does not exist.

 memory_mca
The device name of the histogramming memory, needed for measurements with the LeCroy 3512 ADC.

 monitor_mca, monitor2_mca
Optional monitor counters.

 sample_time_mca
The sample time, if set to '-1', the MCA runs forever.

 sample_time_total_mca
The total sample time, created by ONLINE.

 scan_name_mca

 scan_name_mca2

 ...
The current scan names, created by ONLINE.

 scan_number_mca
The current SCAN number, created by ONLINE.

 timer_mca
The timer that is used to gate the ADC and the counters, for VME systems the timer can be DUMMY, i.e.: timer_mca = dummy.

 x_min_mca
x_max_mca
The window limits.