GRETINA GEB HEADER TYPES

GEB Headers

Detailed information regarding the possible data types, as described by the GRETINA global event builder (GEB) global headers, is available for download (GEBHeaders.pdf).  However, please note the pdf has not yet been updated with the newest Type = 3 data format(s).

Type = 1: Decomposed GRETINA Data

This data type is the decomposed GRETINA data (mode 2) format. Mode 2 data is output from the signal decomposition process, and gives interaction points and energies from a single crystal. The format is defined as a fixed-length C struct (definition found in GRETINA DAQ software in /global/devel/XX-X/decompLib/decompLibApp/gdecomp.h). Two versions of this data format have existed since GEB headers were introduced, with two different struct types. Below is the mode2 data struct used from June 2012-present. For older structs, see the documentation (GEBHeaders.pdf). Definition of Mode2 data formats is controlled by Mario Cromaz (LBNL).

Decomposed GRETINA Data format, June 2012 - now:

Type = 2: Raw GRETINA Data

This data type contains raw (Mode3) data output directly by the GRETINA digitizers. Each event corresponds to a single digitizer channel, and includes a header with timestamp and energy information, as well as a section of trace. The detailed format is presented as a block diagram below:

The energy is a 24-bit 2's complement signed integer, and must be converted to a 32-bit signed integer before use. The detector ID is a compound word consisting of 4 bit-fields as follows:

A sample code to unpack this data is included in the GEBHeaders.pdf file.

Type = 3: Tracked GRETINA Data

This data type contains tracked GRETINA (Mode1) data. Mode1 data is a superset of Mode2 (type 1) data, in that all interaction point information is maintained, and the results of tracking, namely a grouping of interaction points into a gamma-ray event, and a preferred ordering (first-hit identification) of interaction points is included. The structure of this data is similar to mode2, using a fixed length C struct, as defined below (can also be found in GRETINA DAQ software in /global/devel/XX-X/trackLib/trackLibApp/ctk.h). Definition of Mode1 data formats is controlled by T. Lauritsen (ANL).

Type = 4: BGS Raw Data

This data type contains the raw BGS data, which is a simple array of short integers, which is mapped simply to values read from the data acquisition. A parameter list, which simply provides a label to each short integer in the data array provides the framework to unpack the BGS data. The parameter list for the BGS data in the commissioning runs is in the .pdf document. Additional information regarding the BGS data structure can be obtained from H. Crawford (LBNL).

Type = 5: S800 Raw Data

This data type contains the raw S800 data buffers. Description of the complete S800 raw data structure is available on the S800 wiki at https://groups.nscl.msu.edu/opdevtech/wiki/index.php/S800_data_format

Type = 6: NSCL Non-Event Data

This data type contains NSCL non-event data structures, including beginning of run, end of run and scaler NSCL buffers, which are generated by the NSCL readout software. In general, the first 32-bit integers of the payload for a type 6 event will describe the buffer length in bytes, and the buffer packet type, in a RingItemHeader, defined as:

Details regarding the definition of non-event data structures can be found in the NSCL documentation available at:http://docs.nscl.msu.edu/daq/ringbuffer/r17361.html, while the definition of the possible non-event data types is available at: http://docs.nscl.msu.edu/daq/ringtutorial/a1889.html.

Type = 7: GRETINA Scaler Data

This data type contains GRETINA digitizer-level scaler information. These scalers are currently in the testing phase, and will be implemented once testing is complete. 

Type = 8: Bank 88 (formerly 29) Raw GRETINA Data

This data type is structurally identical to type 2 (raw GRETINA, or mode3 data), but has been designated to exclusively identify data originating from Bank88 in the GRETINA DAQ. This is a single digitizer which is used to digitize signals from auxiliary systems which may be useful to improve the resolution of particle-gamma timing, for instance. A new type number was assigned to mark these data as being inappropriate for decomposition, and to funnel these data into the appropriate GRETINA output file.

Type = 9: S800 Processed (Physics) Data

This data type contains post-processed S800 data, which contains the S800 parameters relevant to and required for particle identification (energy loss and time of flight information), and Doppler correction of GRETINA spectra (S800 angles and positions). This is the structure that can be used if GRETINA analysis and S800 analysis are treated somewhat independently, to be able to make the appropriate Doppler corrections and obtain the best possible GRETINA spectra. Data type was defined by D. Weisshaar (NSCL).

Type = 10: Timestamped NSCL Non-Event Data

This data type is identical in format to Type 6 (NSCL Non-Event Data), but was created to reflect a change in the way that NSCL non-event data is sent to the global event builder. Type 6 non-event data was assigned a recent timestamp once it arrived to the global event builder, which could result in trouble with respect to the ordering of scaler packets, etc. In response to this, within the NSCL data acquisition system a change was made to provide non-event data with a valid timestamp before being sent to the global event builder. This data type reflects this change, and should signify that the timestamp of these packets are generated by the NSCL DAQ, and not assigned in the GEB. Questions regarding this data type should be directed to D. Weisshaar (NSCL).

Type = 11: GRETINA GEANT4 Simulation Data

This data type is reserved for simulation data for GRETINA as generated from the GEANT4 simulation of the array. Details on the data format and specifications are pending. This data type is controlled by Lew Riley (Ursinus College).

Type = 12: CHICO Raw Data

This data type is reserved for raw data from the CHICO detector. Details on the data format are pending. This data type is controlled by T. Lauritsen (ANL).

Type = 14: Digital Gammasphere Data (DGS)

This data type is reserved for data related to digital Gammasphere (DGS) and the GTReceiver3 at ANL. Details for this data type are pending. This data type is controlled by T. Lauritsen (ANL).

Type = 15: Digital Gammasphere Trigger Data (DGSTRIG)

This data type is reserved for data related to digital Gammasphere (DGS) trigger information and the GTReceiver4 at ANL. Details for this data type are pending. This data type is controlled by T. Lauritsen (ANL).

Type = 16: Digital FMA Data (DFMA)

This data type is reserved for data related to digital FMA and the GTReceiver4 at ANL. Details for this data type are pending. This data type is controlled by T. Lauritsen (ANL).

Type = 17: Phoswich Wall

This data type is reserved for data related to the Washington University Phoswich Wall particle detector array.  Details for this data type are pending; the data type is controlled by the WashU group of D. Sarantites et al.

Type = 18: Phoswich Wall Auxiliary Data

This data type is reserved for auxiliary data related to the Washington University Phoswich Wall particle detector array.  Details for this data type are pending; the data type is controlled by the WashU group of D. Sarantites et al.

Type = 19: GODDESS

This data type is reserved for data related to the GODDESS particle array.  Details for this data type are pending; the data type is controlled by the Rutgers/ORNL GODDESS team.

Type = 20: ANL LaBr array

This data type is reserved for a LaBr array at ANL.  Details are coming.  The data type is controlled by T. Lauritsen (ANL).

Type = 21: LENDA Neutron Array (NSCL)

This data type is reserved for the LENDA detectors at NSCL.  Details are coming.  The data type is controlled by H. Crawford (NSCL).

Type = 22: GODDESS Auxiliary Data

This data type is reserved for auxiliary data related to the GODDESS particle array.  Details for this data type are pending; the data type is controlled by the Rutgers/ORNL GODDESS team.

Type = 0x2B: GRETINA Energy Digest

This data type contains a list of (Timestamp, Energy, ADC baseline) data output directly by the GRETINA digitizers. Each packet contains several gamma-ray events, without trigger validation, for the core (CC) channel of a single digitizer, and includes a header which replicates the first seven 16-bit words of the Raw GRETINA Data format (see Type 2 above).  The channel entry within the header is set to 0xB indicating it is an energy digest.

If additional GEB header types are required, for new auxiliary detectors, etc., please contact Heather Crawford or Mario Cromaz to obtain a type number.