# Analysis

## User Guide

### UI Overview

The Analysis system in mvme is designed to allow

- flexible parameter extraction from raw readout data.
- calibration and additional processing of extracted parameters.
- accumulation and visualization of processed data.

The user interface follows the structure of data flow in the system: the Events and Modules defined in the VME configuration are shown in the top-left tree.

The bottom-left tree contains the raw histograms used to accumulate the unmodified data extracted from the modules.

The next column (Level 1) contains calibration operators in the top view and calibrated histograms in the bottom view.

Fig. 24 Analysis UI Block Diagram

Note

To get a set of basic data extraction filters, calibration operators and histograms right-click on a module an select Generate default filters.

User Levels are used to structure the analysis and it’s completely optional to have more than two of them. Additional levels can be added/removed using the + and - buttons at the top-right. Use the Level Visibility button to select which levels are shown/hidden.

The UI enforces the rule that operators can use inputs from levels less-than or equal to their own level. This means data should always flow from left to right. This restriction does not apply to data sinks in the bottom tree. These can be freely placed on any userlevel in the bottom tree.

Operators can be moved between levels by dragging and dropping them.

Fig. 25 Analysis UI Screenshot

The Calibration for mdpp16.amplitude is selected. Its input is shown in green. Operators using the calibrated data are shown in a light blueish color.

Selecting an object will highlight its input data sources in green and any operators using its output in blue.

### Adding new objects

Right-click in any of the views and select New to add new operators and histograms. A dialog will pop up with input fields for operator specific settings and buttons to select the operators inputs.

Clicking any of the input buttons will make the user interface enter “input select mode”. In this mode valid outputs for the selected input are highlighted.

Fig. 26 Input select mode

Adding a 1D Range Filter to Level 2. Valid inputs are highlighted in green.

Click an input node to use it for the new operator. The Parent Event specifies the event context in which the operator will be executed. The system tries to pick the correct event based on the input selected. Manually setting the parent event might be needed when doing cross-event analysis, e.g. creating an operator which takes inputs from two unrelated events.

If required fill in any additional operator specific data and accept the dialog. The operator will be added to the system and will immediately start processing data if a DAQ run or replay is active.

For details about data extraction refer to Data Sources. Descriptions of available operators can be found in Operators. For details about 1D and 2D histograms check the Data Sinks section.

### Working with histograms

1D and 2D histograms are shown in the bottom row of the user interface. Raw 1D histograms are grouped by module in the bottom-left L0 Raw Data Display area. Higher level data displays are grouped by histogram type.

New histograms can be added by right-clicking in one of the data display areas, selecting New and choosing the histogram type.

#### 1D

1D histograms can take full arrays as input parameters. Internally an array of histograms of the same size as the input array will be created.

Double-click on the H1D node to open the histogram array widget:

Fig. 27 1D Histogram Array Widget

- The histogram index can be changed using the spinbox in the top-right corner.

- Zooming is achieved by dragging a rectangle using the left mouse button. Zoom levels are stacked. Click the right mouse button to zoom out one level.

- Press the Info button to enable an info display at the bottom-right of the window. This will show the current cursor coordinates and the corresponding bin number.

- Y-Scale

  Toggle between linear and logarithmic scales for the Y-Axis.

- Gauss

  Fit a gauss curve through the currently visible maximum value.

- Rate Est.

  Rate Estimation feature.

  Refer to Rate Estimation Setup for a how-to guide.

- Clear

  Clears the current histogram.

- Export

  Allows exporting to PDF and various image formats. Use the file type selection in the file dialog to choose the export format.

- Save

  Saves the histogram data to a flat text file.

- Subrange

  Allows limiting the range of data that’s accumulated. Only input values falling within the specified interval will be accumulated.

  This does not affect the histogram resolution: the full range of bins is still used with the limits given by the subrange.

- Resolution

  Change the resolution of the histogram in powers of two from 1 bit to 20 bits.

  This will not rebin existing data. Instead the histogram is cleared and new data is accumulated using the newly set resolution.

- Calibration

  This button is enabled if the histograms input is a Calibration Operator and allows to directly modify the calibration information from within the histogram:

  > Fig. 28 Calibration adjustment from within the histogram display

  The two inputs in the Actual column refer to the current x-axis scale. The inputs in the Target column are used to specify the desired x-axis values.

  Click on one of the Actual inputs and then press the Vis. Max button to fill in the x-coordinate of the currently visible maximum value. Then enter the new x-coordinate value in the Target box and press Apply.

  In the example above it is known that the peak should be at `x = 600.0`. The current x-coordinate of the peak was found using the Vis. Max button. Pressing Apply will modify the calibration for that particular histogram.

  To see a list of calibration values for each channel open the Analysis UI (`Ctrl+2`), right-click the Calibration Operator and select Edit.

- 2D combined view

  A combined view of the histograms of an array of parameters can be opened by right-clicking a H1D node and selecting Open 2D Combined View. This option will open a 2D histogram with one column per 1D histogram in the array.

  The X-axes of the 1D histograms are plotted on the combined views Y-axis, the values of the histograms are plotted in Z.

  This view allows to quickly see if any or all channels of a module are responding.

Fig. 29 2D Combined View of MDPP-16_SCP amplitude values

Channels 0 and 8 are producing data with visible peaks at around 0 and 230.

#### 2D

2D histograms take two single values as their inputs: the X and Y parameters to accumulate. When selecting the inputs you will need to expand other operators and select the desired index directly.

Fig. 30 Adding a 2D Histogram

Expand operator outputs and select individual indices for both axes.

Optional range limits can be specified for the axes. If enabled only values falling within the given interval will be accumulated.

Double-click on a H2D node to open the histogram widget:

Fig. 31 2D Histogram Widget

- Zooming is achieved by dragging a rectangle using the left mouse button. Zoom levels are stacked. Click the right mouse button to zoom out one level.

- Press the Info button to show histo and cursor coordinate information at the bottom of the window.

- Z-Scale

  Toggle between linear and logarithmic scales for the Z-Axis.

- X- and Y-Proj

  Create the X/Y-Projection and open it in a new 1D histogram window. The projection will follow any zooming/scrolling done in the 2D histogram.

- Slice X / Slice Y

  Slices the histogram along the respective axis. The visible resolution of the chosen axis determines the number of slices. Slices are displayed in a 1D histogram window.

- Clear

  Clears the histogram.

- Export

  Allows exporting to PDF and various image formats. Use the file type selection in the file dialog to choose the export format.

- Subrange

  Allows limiting the range of data that’s accumulated. Only input values falling within the specified interval will be accumulated.

  This does not affect the histogram resolution: the full range of bins is still used with the limits given by the subrange.

  Can optionally create a new histogram with the specified limits instead of modifying the current one. The newly created histogram will be added to the analysis.

- Resolution

  Change the resolution of the histograms axes in powers of two from 1 bit to 13 bits.

  This will not rebin existing data. Instead the histogram is cleared and new data is accumulated using the newly set resolution.

### Condition System

Since mvme-1.5 the analysis system supports conditional evaluation/skipping of operators and data sinks.

Conditions are a special kind of operator producing only a single output value: the boolean result of evaluating the condition. Each condition can be applied to multiple operators and/or data sinks. Multiple conditions can be applied to the same object in which case the logical AND of all condition outputs is used to decide whether the operator should be run.

Currently 1d-interval, 2d-polygon and boolean expression conditions are implemented.

#### Creating and editing conditions

1d interval and 2d polygon conditions can be created and edited from within histogram windows. Use the “Interval Conditions” or “Polygon Conditions” buttons to start the respective editor.

A new condition created this way will use the same input arrays as the histogram where the editor was started. The new condition will be placed in a common directory on the same userlevel as the histogram used to create the condition.

Fig. 32 Polygon Condition Editor

Expression conditions are created the same way as other operators: using the context menu and selecting `New -> Expression Condition`.

#### Using conditions

Once you have created one or more condtions you can apply them to operators and (histogram) sinks using the right-click context menu and selecting “conditions”. This works the same way as the input selection when creating operators. If multiple conditions are applied to the same operator they all have to evaluate to true in the current event for the operator to be executed.

#### Condition based listfile filtering

Note

Condition based listfile filtering is implemented for the MVLC only.

Since mvme-1.10 analysis conditions can be used to filter input listfiles and produce smaller output files which are faster to re-analyze than the original input file.

For each readout event defined in the VME config a condition can be selected. During a replay with filtering enabled only those events for which the selected condition evaluates to true are written to the output file.

To use the feature first create a condition used for filtering, e.g. a simple interval condition, then load a listfile and press the `Listfile Filtering` button in the analysis window.

Fig. 33 Listfile filtering setup. `event0` is filtered by the condition `interval0`, `event1` is not filtered.

In the dialog that opens up a single condition can be selected for each defined event. If no condition is selected the respective event will always end up in the output listfile. For a condition to show up in the selection box it has to run in the same event context as the respective event.

Optionally set a prefix for the output listfile filename. To guarantee uniqueness a timestamp string is appended to the filename prefix.

Make sure the `Enable filtering` box is checked then accept the dialog and start the replay. The current output filename will be printed to the mvme log window.

### Inspecting Dependencies

Since version 1.5 mvme includes a dependency graph viewer for analysis objects. It allows to visualize the data path and any active conditions affecting the processing. The graph can be opened from within histogram windows using the `Dependency Graph` button via the right-click context menu in the main analysis window.

Fig. 34 Dependency graph for a 2D histogram. Active conditions in the data path are grouped together in the grey box.

Within the graph double-clicking on histograms or other sinks opens the respective view, while double clicks on other objects start the appropriate editor. Ctrl-clicking navigates to the graph for the clicked object.

## System Details

As outlined in the introduction the analysis system is a set of interconnected objects with data flowing from Sources through Operators into Sinks.

The system is structured the same way as the VME Configuration: VME modules are grouped into events. An event contains the modules that are read out on activation of a certain trigger condition. The result of the readout is the modules event data (basically an array of 32-bit words). This module event data is the input to the analysis system.

When processing data from a live DAQ run or from a listfile replay the analysis system is “stepped” in terms of events: in each step all the Data Sources attached to a module get passed the modules event data. The task of each source is to extract relevant values from its input data and make these values available to subsequent operators and sinks.

After all sources have processed the module event data, the dependent operators and sinks are stepped in order. Each object consumes its input and generates new output or in the case of sinks accumulates incoming data into a histogram.

Fig. 35 Example analysis dataflow

### Parameter Arrays

The transport container carrying data between objects is the Parameter Array:

Parameter Array
size | unit label
Parameters
0 | value | valid | limits
1 | value | valid | limits
2 | value | valid | limits
… |  |  |
size-1 | value | valid | limits

The size of parameter arrays is determined at analysis startup time and is constant throughout the run. The unit label is a string which currently can be set through the use of the Calibration Operator. The index of a parameter in the array is usually the channel address that was extracted from the modules data.

Each parameter has the following attributes:

- value (double)

  The parameters data value.

- valid (bool)

  True if the parameter is considered valid, false otherwise.

  A parameter can become invalid if for example a data source did not extract a value for the corresponding channel address or an operator wants to explicitly filter out the address or could not calculate a valid result for the input value.

- limits (two doubles)

  Two double values forming the interval `[lowerLimit, upperLimit)` that the parameters value should fall into. This is used by histogram sinks and calibration operators to determine the parameters range and thus calculate the binning.

### Connection types

Different operators have different requirements on their input types. The Calibration Operator for example can use whole parameter arrays as its input, transforms each data value and produces an output array of the same size as the input size.

Other operators can only act on individual values and thus connect directly to a specific index into the parameter array. An example is the 2D Histogram Sink: it requires exactly two input values, X and Y, neither of which can be an array.

Fig. 36 Example of different input types

Each Operator implementation decides which types of input connections it accepts. Some operators even change the type of inputs they accept based on the first input type that is connected (they either accept full arrays for all their inputs or single values for all their inputs).

The Analysis UI will highlight valid input nodes in green when selecting an operators input.

## Data Sources

Analysis Data Sources attach directly to a VME module. On every step of the analysis system they’re handed all the data words produced by that module in the corresponding readout cycle. Their job is to extract data values from the raw module data and produce an output parameter array.

### Filter Extractor

The Filter Extractor uses a list of bit-level filters to classify input words and extract address and data values.

#### Filter Basics

A single filter consists of 32 characters used to match a 32-bit data word. The filter describes the static parts of the data used for matching and the variable parts used for data extraction. The first (leftmost) character of a filter line matches bit 31, the last character bit 0.

The following characters are used in filter strings:

Character | Description
--- | ---
`0` | bit must be cleared
`1` | bit must be set
`A` | address bit
`D` | data bit
others | don’t care

The following conventions are used in the default filters that come with mvme:

- `X` is used if any bit value is allowed.
- `O` (the letter) is used to denote the position of the overflow bit.
- `U` is used to denote the position of the underflow bit.
- `P` is used to denote the position of the pileup bit.

These characters are merely used to make it easier to identify certain bits when editing a filter. With regards to matching any character other than `0` or `1` means that any bit value is allowed.

Example: The default Amplitude filter for the MDPP-16_SCP:

    0001 XXXX PO00 AAAA DDDD DDDD DDDD DDDD

The filter above contains a 4-bit address and a 16-bit data value. The positions of the pileup and overflow bits are marked using `P` and `O`. This helps when adjusting the filter to e.g. match only pileup data (replace the `P` with a `1`).

The number of address bits (`A`) determine the size of the Filter Extractors output array.

Data extraction from an input data word is done by keeping only the bits matching the address or data mask and then right shifting to align with the 0 bit.

Note

Address and data bit masks do not need to be consecutive. `A0AA` will produce 3-bit address values by gathering all extracted `A` bits on the right: `0AAA`.

Each filter has an optional word index attached to it. If the word index is set to a value >= 0, then the filter can only produce a match on the module data word with the same index.

#### Multiple filter words

The Filter Extractor implementation allows combining multiple 32-bit filters to match and extract data from multiple input words.

Filters are tried in order. If a previously unmatched filter produces a match no further filters will be tried for the same data word.

Once all individual filters have been matched the whole combined filter matches and address and data values can be extracted.

When extracting values the filters are again used in order: the first filter produces the lowest bits of the combined result, the result of the next filter is left-shifted by the amount of bits in the previous filter and so on.

Note

The maximum number of bits that can be extracted for address and data values is limited to 64.

See Timestamp extraction for an example of how a multiword filter can be used.

#### Matching and data extraction

During a DAQ run or a replay the Filter Extractor gets passed all the data that was produced by a single module readout (Event Data). Each data word is passed to the internal filter.

Once the filter has completed Required Completion Count times, address and data values will be extracted.

The data value is cast to a double and a uniform random value in the range `[0, 1)` is added. This resulting value is stored in the output parameter array at the index specified by the extracted address value.

#### User Interface

In the Analysis UI right-click a Module and select New -> Filter Extractor to add a new filter.

Fig. 37 Filter Extractor UI

Use the + and - symbols to add/remove filter words. The spinbox right of the filter string lets you specify a word index for the corresponding filter.

Required Completion Count allows you to specify how many times the filter has to match before it produces data. This completion count starts from 0 on every module event and is incremented by one each time the complete filter matches.

If Generate Histograms is checked raw and calibrated histograms will be created for the filter. Unit Label, Unit Min and Unit Max are parameters for the Calibration Operator.

Predefined filters can be loaded into the UI using the Load Filter Template button.

### MultiHit Extractor

The Filter Extractors are limited to a single hit per extracted (channel) address. If multiple hits per address can occur in the same event the MultiHit Extractor can be used to gain access to these hits.

#### Properties

- filter

  A single bit-level filter specifying the bit-pattern to match and the position and number of address and data bits.

- maxHits

  Maximum number of hits to record per address. The total number of hits will be counted in a separate hitCounts array.

- shape

  - Array per Hit

    Hit0 for all addresses is stored in the first array, hit1 in the second, etc. A total of `maxHits` arrays is created each of length .

  - Array per Address

    Hits for the same address are recorded in an array of length `maxHits`. Creates a total of arrays.

Diagram showing the number and size of the MultiHit Extractor output arrays depending on the selected shape type:

                    Array per Hit
                  =================

              +----------------------+ <---.
        hit0  |                      |     |
              +----------------------+     |
              +----------------------+     |
        hit1  |                      |  maxHits
              +----------------------+  arrays
                        ...                |
              +----------------------+     |
        hitN  |                      |     |
              +----------------------+ <---'

              ^                      ^
              '----len=2^addrBits----'

              +----------------------+
    hitCounts |                      |
              +----------------------+

              ^                      ^
              '----len=2^addrBits----'

                    Array per Address
                  =====================

              +----------------------+ <------.
      hits[0] |                      |        |
              +----------------------+        |
              +----------------------+        |
      hits[1] |                      |   2^addrBits
              +----------------------+     arrays
                        ...                   |
              +----------------------+        |
      hits[N] |                      |        |
              +----------------------+ <------'

              ^                      ^
              '------len=maxHits-----'

              +---------------------------+
    hitCounts |                           |
              +---------------------------+

              ^                           ^
              '------len=2^addrBits-------'

## Operators

The following operators are currently implemented in mvme:

### Calibration

The calibration operator allows to add a unit label to a parameter array and to calibrate input parameters using unitMin and unitMax values.

Each input parameters `[lowerLimit, upperLimit)` interval is mapped to the outputs `[unitMin, unitMax)` interval.

With calibrate():

    Out = (In - lowerLimit) * (unitMax - unitMin) / (upperLimit - lowerLimit) + unitMin

Limits can be specified individually for each address in the input array. Use the Apply button to set all addresses to the global min and max values.

Fig. 38 Calibration UI

Note

Calibration information can also be accessed from adjacent 1D histograms. Refer to Working with 1D Histograms for details.

### Previous Value

Outputs the input array from the previous event. Optionally outputs the last input that was valid.

Fig. 39 Behaviour of Previous Value over time.

If keepValid is set the output will always contain the last valid input values.

This operator can be combined with the Difference Operator to accumulate the changes of a parameter across events. See Rate Estimation Setup for an example.

### Difference

Produces the element-wise difference of its two inputs A and B:

The output unit label is taken from input A. If `A[i]` or `B[i]` are invalid then `Out[i]` will be set to invalid:

    Out.Unit = A.Unit
    Out[i].lowerLimit = A[i].lowerLimit - B[i].upperLimit
    Out[i].upperLimit = A[i].upperLimit - B[i].lowerLimit
    Out[i].value      = A[i].value - B[i].value

### Sum / Mean

Calculates the sum (optionally the mean) of the elements of its input array.

This operator produces an output array of size 1.

When calculating the mean the number of valid input values is used as the denominator.

### Aggregate Operations

This operator combines various aggegrate functions in a single operator: `sum`, `mean`, `min`, `max`, `sigma`, `multiplicity`, `min x`, `max x`, `mean x`, `sigma x`. The output is always an array of size 1.

The input values used for the selected calculation can optionally be filtered by threshold limits: values that fall outside the threshold range are not used for the calculation of the result. The threshold can be either a lower limit, an upper limit or both. Lower and upper limits are inclusive.

#### Operations

- sum

  Sum of all array elements.

- mean

  Sum of valid array elements divided by the number of valid elements.

- min

  Minimum value in the input array.

- max

  Maximum value in the input array.

- sigma

  Standard deviation of the array elements.

- multiplicity

  The number of valid array elements. Example: determine the number of responding channels in an event.

- min x

  Zero based index of the minimum value in the array.

- max x

  Zero based index of the maximum value in the array.

- mean x

  Mean over the x values: `sum(input[i] * i) / sum(input[i])`.

- sigma x

  Standard deviation of the x values.

### Array Map

Allows selecting and reordering arbitrary indices from a variable number of input arrays.

The mappings are created via the user interface:

Fig. 40 Array Map UI

- Use the + and - buttons to add/remove inputs. The elements of newly added inputs will show up in the left Input list.
- Select elements in the Input and Output lists and use the arrow buttons to move them from one side to the other.

Multiple items can be selected by control-clicking, ranges of items by shift-clicking. Both methods can be combined to select ranges with holes in-between them. Focus a list and press `Ctrl-A` to select all items.

### 1D Range Filter

Deprecated since version 1.14: Use the new condition system and optionally the ConditionFilter instead.

Keeps values if they fall inside (optionally outside) a given interval. Input values that do not match the criteria are set to invalid in the output.

### 2D Rectangle Filter

Deprecated since version 1.14: Use the new condition system and optionally the ConditionFilter instead.

Produces a single valid output value if both inputs satisfy an interval based condition.

### Condition Filter

Copies data input to output if the corresponding element of the condition input is valid.

### Expression Operator

This operator uses the exprtk library to compile and evaluate C-like, user-defined expressions.

The operator supports multiple inputs and outputs. The definition of the outputs is done using an exprtk script, which means arbitrary calculations can be performed to calculate the number of outputs, their sizes and their parameter limits.

During analysis runtime a second script, the step script, is evaluted each time event data is available. The script calculates and assigns parameter values to the operators output arrays.

Details about the syntax and semantics are provided in the online help in the Expression Operator user interface.

### ScalerOverflow

The ScalerOverflow operator outputs a contiguous value given an input value that overflows. This can be used to handle data like module timestamps which wrap after a certain time.

## Data Sinks

mvme currently implements the following data sinks:

### 1D Histogram

Accumulates incoming data into 1D histograms. Accepts a full array or an individual value as input. If given a full array the number of histograms that will be created is equal to the array size.

See Working with 1D histograms for usage details.

### 2D Histogram

Accumulates two incoming parameters into a 2D histogram. On each event input data will only be accumulated if both the X- and Y inputs are valid.

See Working with 2D histograms for details.

### Export Sink

Implements data export to binary files and C++/Python example code generation.

This operator does not create an exported version of all the readout data but instead lets the user select a specific subset of analysis data arrays - all belonging to modules in the same VME event - to be exported to a binary file on disk. Additionally skeleton code can be generated and used as a base for reading in the generated file and working with the data.

For a complete, network-based readout data export including ROOT tree generation see EventServer.

The Export Sink has a variable number of data input arrays that will be written to disk. Additionally a single parameter condition input can be used to pre-filter data: output data will only be generated if the condition input is valid.

For each DAQ run or replay an export file named data_<runid>.bin is generated and the data from each event is appended to that file. If zlib compression is enabled the extension .bin.gz is used.

The inputs define the layout of the exported data (in the case of the “Plain/Full” format the export file contains plain, packed C-structs).

Use the “C++ & Python Code” button to generate code examples showing how to read and work with export data.

To compile the C++ code run `cmake . && make` inside the export directory. The CMake file will try to find a ROOT installation using the environment variable `${ROOTSYS}` and will search for zlib in the standard system paths.

Most of the generated executables take an export binary file as their first command line argument, e.g:

    ./root_generate_histos my_run_001.bin.gz

### Rate Monitor

The rate monitor uses its input values as precalculated rates or calculates the rate using the difference of successive input values. Rate values are kept in a circular buffer and a plot of the rate over time can be displayed.

Details can be found in the Rate Monitor user interface.

## Conditions

See Condition System for a general description of how conditions work in mvme.

### Interval Condition (1D Gates)

Accepts a parameter array as the single input value. Holds an interval for each member of the input array.

When being evaluated the Interval Condition checks if each input parameter value is inside its respective interval. The final condition result is the logical OR over the individual interval checks.

Note: intervals are interpreted as half-open with the lower border considered part of the interval.

### Polygon Condition

A two-dimensional condition checking if the input coordinates are contained within a polygon.

### Expression Condition

Higher level condition, accepting multiple other conditions as its input. Uses the exprtk library to evaluate a user-defined expression. The expression result becomes the conditions output value.

## Readout Data Preprocessing

The standard data path into the analysis is straighforward: a readout parser component interprets the data stream and produces reassembled module data buffers which are then handed to the analysis system:

    raw readout data -> readout_parser -> analysis

Using the Event Settings dialog in the Analysis UI, the following additional processing steps can be enabled.

### Multi Event Processing

The purpose of Multi Event Processing module is to split multievent data obtained from VME block reads into separate, individual events.

Multievent data can be read out from mesytec modules if `multi event mode (0x6036=0xb)` is enabled and `max transfer data (0x601A)` is set to a value greater than 1. With this setup each VME block read from the module will yield up to the number of events specified in `max transfer data` provided the module has enough events buffered up. This way of reading out modules can dramatically improve performance as the modules can make full use of their internal buffers and less individual VME transfers are used to read out the same number of events. The drawbacks are that non-perfect trigger handling can lead to unsynchronized events across modules and that data processing becomes more complicated.

Splitting is performed on the module data as shown in the diagram below:

     multievent
    +-----------+                 split0           split1          split2
    | m0_event0 |              +------------+   +-----------+   +-----------+
    | m0_event1 |              |            |   |           |   |           |
    | m0_event2 |              | m0_event0  |   | m0_event1 |   | m0_event2 |
    |           | == split ==> | m1_event0  |   | m1_event1 |   | m1_event2 |
    | m1_event0 |              |            |   |           |   |           |
    | m1_event1 |              |            |   |           |   |           |
    | m1_event2 |              +------------+   +-----------+   +-----------+
    +-----------+

In the example the input multievent data obtained from a single event readout cycle is split into three separate events.

Data splitting is performed by using analysis DataFilters to look for module header words. If the filter contains the matching character `S` it is used to extract the size in words of the following event. Otherwise each of the following input data words is tried until the header filter matches again and the data in-between the two header words is assumed to be the single event data.

    +-----------+
    |m0_header  | <- Filter matches here. Extract event size if 'S' character in
    |m0_e0_word0|    filter, otherwise try the following words until another match is
    |m0_e0_word1|    found or there is no more input data left.
    |m0_e0_word2|
    |m0_header1 | <- Filter matches again
    |m0_e1_word0|
    |m0_e1_word1|
    |m0_e1_word2|
    +-----------+

When using mesytec modules the correct header filters for the modules are setup by default and just enabling `Multi Event Processing` in the `Event settings` dialog is enough to make the splitter system work. For non-mesytec modules the header filter bitmask can be specified in the `Module Settings` dialog found in the context menu of each module in the analysis UI.

Note

When using the MVLC VME Controller a info/debug system for the readout_parser and the multi_event_splitter is available via `Debug & Stats -> Debug next buffer`.

### Event Builder

Since version 1.4.7 mvme contains a timestamp based EventBuilder module which can be enabled if using the MVLC VME Controller. The purpose of the EventBuilder is to create optimally matched events across modules while tolerating non-perfect trigger setups.

Note

In mvme-1.15.2 the EventBuilder has been reimplemented to yield better results while also having a simpler configuration. The description below refers to this new implementation.

The EventBuilder algorithm works as follows:

1. Recording phase

   1. Record incoming module data into memory buffers.
   2. Extract an event timestamp for each module.
   3. Apply the configured module timestamp offsets.
   4. Record all extracted stamps in a list. This can be seen like a virtual module containing the timestamps of all incoming modules.

2. Yield data

   1. Pick the oldest stamp from the virtual stamp list. This is the reference stamp for this cycle.

   2. Ensure all modules have at least one timestamp that is too far in the future to be included in the output event. If this is not the case no data can be flushed yet and the yield phase terminates.

   3. Discard module data that is too old to fall into a modules timestamp match window.

   4. For each module pick the first recorded stamp that falls into the match window. Use the corresponding module data for the output event.

      Break if a match was found or the next recorded module stamp is too far in the future.

   5. If there is at least one module with non-empty output data, yield the output event.

   6. Remove the used reference stamp from the stamp list.

   7. Repeat until no timestamp match is possible anymore, meaning there is no more data or all data is too far in the future.

Note

Timestamp extraction is currently hard-coded to work with the non-extended 30 bit timestamps of mesytec modules.

Event building is only implemented for the mesytec MVLC controller.

Event Building can be enabled in the `Event Settings` dialog. The timestamp offset and match windows can be set in `Event Settings -> Event Builder Settings`.

Fig. 41 Event Builder Settings

A tool to monitor the EventBuilder operation is available via the `Event Builder Monitor` button in the analysis window. This monitor prints internal counters and shows timestamp delta histograms for all module pairs.

Fig. 42 Event Builder Monitor

## More UI structuring and interactions

### Directories

Analysis Directory objects can be created in all but the first userlevels (L > 0). Directories are placed in either the top or bottom trees and keep that assignment throughout their lifetime. Directories can contain any analysis objects from the corresponding tree and other subdirectories.

Creating a new directory is done via New -> Directory in the context menu.

A directory can serve as the destination of a Drag and Drop operation. All moved objects will be reparented to this destination directory.

### Drag and Drop

Objects can be moved in-between trees by dragging and dropping. Selected objects from the source tree will be moved to the destination tree. If the destination is a directory all dropped objects will be reparented into that directory.

### Plot Grid

A plot grid is a view for existing 1D and 2D histograms. A plot grid for an array of 1D histograms can be created on the fly via the context menu entry Open in Plot Grid. Alternatively a new, empty grid object can be created using New -> Plot Grid in the Data Display area.

H1D and H2D objects can be added to the grid by dragging them from the analysis trees onto the grid view.

Use Save View in the grid widgets toolbar to permanently save the view in the analysis setup.

The arrangement of plots in the grid can be changed by selecting Edit in the toolbar, then dragging plots into the desired order. Right-clicking a plot in Edit mode allows to set a custom plot title or remove the plot from the grid view.

### Multiselections

By holding Ctrl and clicking analysis objects it is possible to create a (cross-tree) multiselection. Combine holding Ctrl and Shift at the same time to add ranges of objects to an existing selection.

Note

Cross-tree multiselections do not apply to drag and drop operations as these start and end on specific trees. Thus using a cross-tree selection as the source of a drag operation would be counterintuitive.

### Copy/Paste

Object selections can be copied to clipboard by using Ctrl-C or choosing Copy in a context menu.

Pasting is done via Ctrl-V or Paste in a trees or directories context menu.

If a selection containing internally connected objects is pasted the connections will be restored on the newly created copies of the original objects. This way a network of operators and sinks can be duplicated quickly as only the “external” inputs will need to be reconnected on the copies.

If a directory has been copied the paste operation will create clones of the directory and all of its subobjects.

Copy/paste of data sources is possible but newly pasted objects will not be assigned to a specific module yet.

### Import/Export

A way to share parts of an analysis is to export a cross-tree multiselection to file and later on import from file. Use the Export and Import toolbar entries in the analysis UI to perform these actions.

The behavior is similary to the copy/paste operations: all selected objects will be exported to file. On import clones of these objects are created, internal connections are restored and all objects are placed in the same userlevels as their originals.

### Loading foreign analysis files

Internally VME modules are uniquely identified by a UUID and the module type name. This information is stored in both the VME and analysis configs.

When opening (or importing from) a “foreign” analysis file, module UUIDs and types may not match. In this case auto-assignment of analysis objects to VME modules is tried first. If auto-assignment is not possible the unassigned objects are collected under a special node in the top left tree of the analysis window. Data sources from these unassigned modules can be dragged onto modules existing in current DAQ setup to assign them.