Beam Loss Monitor Software Guide

Transcription

1 Version 1.0 Beam Loss Monitor Software Guide James Leaver 5th December Operating Procedure In order to run the Beam Loss Monitor software, the user should complete the following steps: 1. Open a new terminal window on one of the PCs in the MICE Local Control Room. 2. Log in to the Target PC by entering the command: $ ssh -XY mice@ password: micetargetdaq1 3. Launch the beam loss applications with default configuration options by entering the command: $ ~/ MICESoftware / utility_scripts / StartBeamLossMonitor. bash 4. Use the Beam Loss Monitor application to view the beam loss and Target position signals (see Section 1.1). 5. Use the Beam Loss Event Counter application to keep track of the number of Target dips (see Section 1.2). 1.1 Beam Loss Monitor A screen-shot of the Beam Loss Monitor application is shown in Figure 1. The Signals panel to the left of the window contains a list of all the signals that are currently being acquired. By clicking on the entries in this list, the user can select which data are plotted on the graph in the Raw Data Display tab. Signal traces are added to the plot in the order in which they are highlighted; if a particular trace is obscured, simply deselect and then reselect the corresponding signal in order to bring it to the front of the display. The traces may be normalised by clicking on the Normalise check box, and the range of the x-axis can be specified by entering lower and upper limits in the X-Axis Min and X-Axis Max controls. Note that none of the display controls have any effect on the data that are recorded to disk. 1

2 Figure 1: A screen-shot of the Beam Loss Monitor application, showing the Raw Data Display tab. When launched using the StartBeamLossMonitor.bash script in Step 3 of Section 1, the program automatically starts acquiring data with default configuration options. The user should therefore ignore the Initialise, Start and Stop buttons. 2

3 Figure 2: A screen-shot of the Beam Loss Monitor application, showing the Logs tab. The displayed Target depth and beam loss values are dummy data, as the Target was not operational when the screen-shot was captured. The Beam Loss Monitor application also performs rudimentary data analysis, and the output may be viewed in the Logs tab (see Figure 2). This contains two graphs, the upper of which shows the maximum dip depth of the Target (measured in mm from the centre of the beam line). The lower graph shows the nominal beam loss value for each of the beam loss signals that are currently highlighted in the Signals list. These values are calculated by subtracting the mean background from the spill signal obtained during the period when the Target is dipping, and integrating the result. Both graphs log data as a function of time, where the number of records is specified by the Record Length control. Up to 9999 samples per plot may be displayed, equivalent to ~6 hours of normal running time (this constraint is imposed purely to limit CPU usage). At the end of a run, the application should be stopped by closing the window via the standard top-right X button. 1.2 Beam Loss Event Counter A screen-shot of the Beam Loss Event Counter application is shown in Figure 3. The Beam Loss Monitor Event Count indicator contains the total number of events (equivalent to the total number of Target dips) that have been recorded using the Target DAQ system. The Run Counter displays the number of events that have been recorded since the application was 3

4 Figure 3: A screen-shot of the Beam Loss Event Counter application. launched. This value may be reset at any time by clicking on the Reset button. Both counters automatically update at a nominal time interval of 2s. It is recommended that the user make a note of the Beam Loss Monitor Event Count in the MICE log book at the start and end of each run. At the end of a run, the application should be stopped by closing the window via the standard top-right X button. 2 Log Messages While the Beam Loss Monitor application is running, any log messages will be written to the console. During normal operation, messages of three main types may be observed: [ INFO - BeamLossMonitorUI ] - ( BeamLossMonitorUI. ui.h :438) - Read timeout This means that the DAQ system is not receiving triggers. If the Target is not dipping, this is normal and the message can be ignored. If the Target is dipping, the trigger source should be investigated. [ WARN - BeamLossEventAnalyserBackSubInt ] - ( src / Common / BeamLossEventAnalyserBackSubInt. cc :447) - Event contains no valid background beam loss data [ WARN - BeamLossEventAnalyserBackSubInt ] - ( src / Common / BeamLossEventAnalyserBackSubInt. cc :374) - Beam loss data not recorded for entire ' beam on ' period [ WARN - BeamLossEventAnalyserBackSubInt ] - ( src / Common / BeamLossEventAnalyserBackSubInt. cc :404) - Beam loss background data not recorded for entire ' beam on ' period Messages of this type indicate that the acquired beam loss data are not compatible with the analysis technique used to calculate nominal beam loss values (see Section 1.1). This typically means that an insufficient number of complete spills are being recorded per readout event (several complete spills are required, in addition to the one corresponding to the Target dip, in order to calculate the mean background signal). As this is dependent on the current ISIS running mode, the user normally cannot take any action; instead, the beam loss values displayed in the Logs tab of the Beam Loss Monitor application (see Figure 2) should just be ignored. 4

5 [ FATAL - BeamLossMonitorUI ] - ( BeamLossMonitorUI. ui.h :404) - ========================================================... ======================================================== Exception of type : MICE :: DAQmxException Raised in function : void MICE :: PCI6254Interface :: InitialiseEvent () in file : src / Common / PCI6254Interface.cc, line : 216 With message : Failed to start readout task - Error message : RLP Invoke Node <err > The DMA channel could not allocate a large enough buffer. Try using a smaller buffer size. ========================================================... Note that... indicates additional log text which has been omitted for clarity (the user should only be concerned with the Exception of type: MICE::DAQmxException section). This error will be printed to the console, and will also appear as a pop-up message window from the Beam Loss Monitor application (it may appear twice in succession). When the pop-ups are closed (by clicking on the OK button), the application will exit. The message refers to a flaw in the drivers for the NI DAQ card used to read the beam loss signals, and there is currently no guaranteed technique for restoring the system when the problem occurs. The user should attempt to restart the application (as described in Section 1), but if the message appears repeatedly then it will be necessary to reboot the Target PC. 3 Output Data Data acquired by the Beam Loss Monitor application are written to the directory / home / mice / MICESoftware / data The data read out at each trigger are written to separate event files. These are stored in a number of sub-directories, named according to the format: YYYY_MM_DD XXXXXX where YYYY_MM_DD is a time-stamp (year, month, day) and XXXXXX is an index. New sub-directories are generated whenever: The Beam Loss Monitor application is launched. If a folder with the current time-stamp and index already exists then the index is incremented, otherwise the index is set to zero. The current sub-directory is full (contains 1000 event files). The index is incremented. The date changes. The time-stamp is updated, and the index set to zero. The event files themselves are named according to the format: 5

6 event_yyyyyy.< FileExt > where YYYYYY is the event file index (0-999 in each sub-directory), and <FileExt> is the file type. Currently, <FileExt> may be either ascii (plain text file) or gz (gzip archive), where gz is the default. The data in each event file are formatted as follows: Header entries (one line each): - header_ length - header_ version - generator ( stand_ alone or DATE_ DAQ ) - time_ stamp - sample_ clock_ rate - number_of_samples_per_channel - number_of_fixed_channels - number_of_beam_position_channels - number_of_beam_loss_channels - channel_ names ( tab separated list ) Channel data (tab separated columns, one line per sample): - Columns 0 to ( number_of_fixed_channels - 1) : ' Fixed ' channels ( i. e. always present ). Currently Sample, BeamIntensity and TargetPosition. - Columns ( number_of_fixed_channels ) to ( number_of_fixed_channels + number_of_beam_position_channels - 1) : A potentially variable number of beam position signals. - Columns ( number_of_fixed_channels + number_of_beam_position_channels ) to ( number_of_fixed_channels + number_of_beam_position_channels + number_of_beam_loss_channels - 1) : A potentially variable number of beam loss signals. Currently TotalBeamLoss, BLM7SUM and BLM8SUM. Analysis data (one line each): - analyser_ type - maximum_target_dip_depth - beam_ loss_ values ( tab separated list, one for each beam loss signal ) 4 Conguration The StartBeamLossMonitor.bash script used in Step 3 of Section 1 specifies the default configuration files that will be used to initialise the Beam Loss Monitor and Beam Loss Event Counter applications. It should not be necessary for the user to change these files, but if the need arises it is possible to select different configurations by editing the paths in the following lines of the script: 6

7 BEAM_LOSS_MONITOR_CONFIG_FILE =" $HOME / MICESoftware / BeamLossMonitorSoftware / ConfigFiles / BeamLossMonitorHandlerDescriptions / Default / DefaultBeamLossMonitorHandlerDescription. xml " BEAM_LOSS_EVENT_COUNTER_CONFIG_FILE =" $HOME / MICESoftware / BeamLossMonitorSoftware / ConfigFiles / BeamLossEventCounterDescriptions / Default / DefaultBeamLossEventCounterDescription. xml " All of the configuration files are written in XML format and they are located in various subdirectories of the folder ~/ MICESoftware / BeamLossMonitorSoftware / Configfiles It is unlikely that the user will ever need to modify any configuration files, but a description of their contents is provided in Sections for reference. 4.1 Beam Loss Monitor Handler Description This is the type of configuration file accepted by the Beam Loss Monitor application. The default version is ~/ MICESoftware / BeamLossMonitorSoftware / Configfiles / BeamLossMonitorHandlerDescriptions / Default / DefaultBeamLossMonitorHandlerDescription. xml Its various XML elements are described below: <PCI6254DescriptionFile>: The full path to an NI DAQ card hardware configuration file (see Section 4.2). <BeamLossEventDescriptionFile>: The full path to a readout data format configuration file (see Section 4.3). <BeamLossRecorderType>: Specifies the type of output files that should be created. Currently supported options are GZ_RECORDER (for gzip archived output, default setting), ASCII_RECORDER (for plain text output) and NULL_RECORDER (for no output). <OutputDataPath>: This is where the output files are generated. Default setting is / home / mice / MICESoftware / data 4.2 PCI6254 Description This describes the basic hardware setup of the NI DAQ card. The default version is ~/ MICESoftware / BeamLossMonitorSoftware / Configfiles / PCI6254Descriptions / Test / ExamplePCI6254Description. xml 7

8 Its various XML elements are described below: <NumReadoutChannels>: The number of channels that should be read out. <ReadoutChannelName Channel="N">: The hardware channel name of channel N (e.g. Dev1/ai0 ). This maps physical channels to software channels. <MinInputVoltage>: Minimum expected input voltage. <MaxInputVoltage>: Maximum expected input voltage. <SampleClkSource>: The only useful option is OnboardClock. <SampleClkRate>: The sample clock rate. <NumSamplesPerEvent>: Number of samples read out per trigger. <TriggerSource>: Hardware input used for the trigger (normally /Dev1/PFIO ). If set to NULL, disables the trigger ( free running mode). <ReadTimeout>: How long the software will wait for data when a read is attempted. 4.3 Beam Loss Event Description This maps readout channels to actual physical signals. The default version is ~/ MICESoftware / BeamLossMonitorSoftware / Configfiles / BeamLossEventDescription / Test / ExampleBeamLossEventDescription. xml Its various XML elements are described below: <BeamIntensityChannel>: The index of the channel used for the beam intensity signal. <TargetPositionChannel>: The index of the channel used for the Target position signal. <NumBeamPositionMonitors>: The number of beam position signals that are being read. <BeamPositionChannel Monitor="N">: The index of the channel used for beam position signal N. <BeamPositionChannelName Monitor="N">: The name of beam position signal N. <NumBeamLossMonitors>: The number of beam loss signals that are being read. <BeamLossChannel Monitor="N">: The index of the channel used for beam loss signal N. <BeamLossChannelName Monitor="N">: The name of beam loss signal N. <EventAnalyserType>: Specifies the type of analyser that will be used to calculate nominal beam loss and maximum Target dip depth. Currently supported options are BACK_SUB_INT_ANALYSER (default background subtraction and integration method) and NULL_ANALYSER (a dummy analyser which performs no calculations). 8

9 4.4 Beam Loss Event Counter Description This is the type of configuration file accepted by the Beam Loss Event Counter application. The default version is ~/ MICESoftware / BeamLossMonitorSoftware / Configfiles / BeamLossEventCounterDescriptions / Default / DefaultBeamLossEventCounterDescription. xml Its various XML elements are described below: <PriorEventCount>: The initial number of events (i.e. the number of events which do not have corresponding event files in the default output data directory). 108,285 events were recorded prior to establishing final configuration options for the NI-card-based Target DAQ system. <CurrentDataPath>: Must be set to the current output data directory. <UpdateInterval>: The time interval at which the current event count is recalculated. 9