This is an attempt to provide an introduction to the nscope control program for Pixie16 modules in PXI crates developed at NSCL/MSU. Hopefully with the aid of this guide you can quickly get started to looking at data with the Pixie16 modules.
The program is graphically driven but responses to input will be displayed graphically or in the terminal. Typically terminal output consists of results from booting and MCA runs.
The file menu contains three options. The first option is loading the DSP parameter set file through a file open dialog box. This sets the location of the file for use when booting the pixie16 modules.
- After loading a DSP parameter set file (*.set) you must still boot the modules by clicking on the "boot" button.
The second menu option exits the program and the third menu option displays the nscope version number and intended purpose
The channel setup menu contains most Pixie16 parameters that can be set on a channel-by-channel basis. Each menu item in the channel setup menu refers to a class object tasked with inspecting and changing specific parameters associated with the menu parameter. For example, the Energy Filter menu item activates a separate pop-up window to control the energy rise time and energy flattop parameters which affect the energy determination in the Pixie16 module.
The last menu item "Save2File" saves the current set of Pixie16 parameters from the modules to a *.set file for later use. In this manner multiple acquisition modes can be configured before the start of an experiment and the change between the two can be accomplished simply by booting the modules with the appropriate *.set file.
- The *.set file must have a size of exactly 120 k. Anything else suggests a corrupted set file. If you are having problems with nscope check the size of the set file.
- The channel parameters are firmware dependent. In the documentation of each class of nscope a statement is provided as to what firmware parameters are being altered.
- For most parameters there is not an automatic readback of the parameter value from the module. To obtain the current value in the module you must load the parameter again. This is particularly important in the energy filter where there is a limit on the sum of the rise time and gap setting that varies as a function of the filter range.
The module setup menu contains two items to control most Pixie16 module level parameters. The module variables menu item provides a drop down box to set various parameters that require numerical values.
The ModCsrb menu controls the bit sets for the module csrband includes things such as external triggering, multiple crate acquisitions, ... See your firmware for more details concerning the operation of each bit.
- Parameters, especially module csrb parameters, are firmware dependent. Please check your firmware to ensure you are changing the appropriate parameter.
The run control menu list contains the commands to accumulate data with Pixie16 through nscope:
- Find tau - attempts to automatically determine a value of tau based on the incoming signals.
- Start Run - start an MCA run within a given module. You can retrieve histograms from the MCA run by clicking the GetHisto button when nscope is running.
- Start Baseline Run - starts a run to record the baselines in a particular channel. You can retrieve the baselines by clicking on the Get Baselines button
- FindTau is not very robust yet, further development is underway.
- Do not attempt to change parameters while the system is running. Corrupting the DSP parameters is possible.
The Scope menu items control the time width of the bins in the trace display. The minimum time difference is 60 ns.
There are four buttons that are always present on the nscope display
The first button is always the boot button and controls the booting of the Pixie16 modules.
The second button is called either:
- Read Wf - retrieves a waveform from Pixie16, default action For weak sources it is time consuming to repeatedly click the "capture trace" function since more than likely you'll retrieve a baseline trace. Therefore, a maximum of NUMBERofTRACES (currently set to 500) traces are retrieved until one trace satisfies hard coded trigger conditions (not necessarily the ones that pixie16 is currently using. Defined in the Main::NewTrace function
- End Run - terminates CA run in current module, activated after clicking "Start Run" from Run Control menu
- End Baseline - terminates baseline run in current module, activated after clicking "Start Baseline Run" from Run Control menu
The third button is called either:
- Analyze WF - based on the current parameters for trigger and energy filter displays the trapezoidal filters.
- Read Histo - gets MCA spectrum from current channel, activated after clicking "Start Run" from Run Control menu
- Get Baseline - gets baseline spectrum from current channel,activated after clicking "Start Baseline Run" from Run Control menu
The fourth button is called:
- Save - saves the current spectrum to ascii formant with specified filename in dialog box. This function allows for a user defined output format in case the default ROOT formats accessed by right-clicking on the histogram are not appropriate.
Certain portions of the nscope program are necessarily dependent on the local method of installing and running the codes at the home institution. The following is hopefully a comprehensive list of the items that need to be changed to ensure that the program will compile and run successfully:
- The directories containing XIA source code must be updated in the Makefile
- The ROOT framework should be accessible from the command line
- The path to the PlxApi library should be updated in the Makefile.
- The directories of the FILE_SAVE and FILE_OPEN commands in Main.cpp should be altered.
- Symbolic links from the directory that nscope is run from to the pxisys.ini file should be provided. (The pxisys.ini file provided in the XIA firmware is appropriate).
This section attempts to describe some of the known features of the code:
- The Pixie16 manual mentions this but I feel that not enough attention is drawn to it. If the clock distribution settings are set incorrectly on the Pixie16 boards, the computer may not boot.
- For most parameter settings, a read back of the value is not performed after setting the value in the Pixie16 module. Load the parameter to check its value in Pixie16. This can be important in the energy filter since the range parameter influences the total amount of time available for the rise time and flat top.
- The lock file that prevents multiple processes from attempting to talk to Pixie16 has been disabled. Do not try to start multiple programs each attempting to talk to the Pixie16 crate (for example, nscope and readout).
- Do not attempt to change parameters while Pixie16 is running.
- Typically, loading parameters is necessary before changing the values.