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BNMR and BNQR Experiments at TRIUMF

This is the main page of the documentation for the Data Acquisition System (DAQ) for the BetaNMR (BNMR) and BetaNQR (BNQR) experiments at TRIUMF

Click here for a full list of all the pages in the BNMR documentation.


The Data Acquisition System is based on the MIDAS data acquisition package.

There are two separate beamlines, BNMR and BNQR, each with its own experimental setup :

  • bnmr running on the BNMR high-voltage platform
  • bnqr running on the BNQR high-voltage platform

Each experimental setup has its own #Hardware Components (i.e. a VME crate containing DAQ modules). Each runs as a separate MIDAS experiment named bnmr or bnqr. DAQ software specific to these experiments (MIDAS clients) run the experiments - see #Software Components. Experimenters control the experiment using the MIDAS Web Server (mhttpd).

Beam Control

The main TRIUMF EPICS Control System is used to control the beam, which can be switched to either experiment's beamline. There are two Beam Modes that the experiments can be run in:

single channel mode
where the beam is sent to one beamline (channel) only, either BNMR or BNQR. Only one of the DAQ systems bnmr or bnqr is active.
dual channel mode
where the beam is switched between the two beamlines (channels) BNMR and BNQR at regular intervals. Both DAQ systems bnmr and bnqr are active.

Experimental modes

For both experiments, two types of environment are defined (cf MUSR experiments):

  • Integral or TI (Type 1)
  • Time Differential or TD (Type 2)

There are two separate concepts that use similar naming schemes (e.g. 1f, 20) - the timing of pulses issued by the PPG and the name of the overall experimental mode. The overall mode determines both which timing scheme is run, as well as which hardware is scanned during the run (e.g. RF frequency, Na cell voltage). Multiple experimental modes may use the same PPG timing scheme (e.g. modes 1c, 1d, 1e, 1n use the PPG timing scheme called 1n).

Below is a full list of experimental modes, with the most common ones highlighted in bold. More details about each mode can be found on the BNMR mode changer page and the BNQR mode changer page.

Experimental modes
Mode name PPG timing BNMR? BNQR? Comment
10 10 No RF, nothing scanned
1a 1a Scan RF frequency
1b 1b Scan RF frequency
1c 1n Scan settings on a Camp device
1d 1n Scan the laser intensity
1e 1n Scan the magnetic field strength
1f 1f Scan RF frequency
1g 20 Scan RF frequency
1j 20 Scan settings on a Camp device
1n 1n Scan the Rb cell voltage or any other EPICS device
1w 1w Parametric scan of RF frequencies
1x 1f Scan RF frequency with one region at higher resolution
20 20 Nothing scanned
2a 2a Scan RF frequency
2b 2b Scan RF frequency
2d 1b RF on, nothing scanned
2e 2e Scan RF frequency
2f 2f Scan RF frequency
2h 20 Read alpha channels from scalers
2s 2s Spin-echo
2w 2w RF Wurst modulation

Any of these modes may be run in single channel mode. Only Type 2 modes may be run in dual channel mode.

Users change which mode is active using the webpages for each experiment, which in turn interact with the mode changer python script.

Hardware Components

DAQ hardware components for each DAQ system (BNMR/BNQR) include the following VME modules:

Table 2: VME Modules for each Experiment
Module Description VME Base Address BNMR? BNQR? Manual
SIS3801 version E multichannel scaler A 0x2800 SIS3801 manual (PDF)
SIS3801 version E multichannel scaler B 0x1800
SIS3820 multichannel scaler B 0x38000000 SIS3820 manual (PDF)
PPG (Pulseblaster) Pulse Programmer 0x8000 PPG manual (PDF) Spincore Pulseblaster (PDF)
PSM Pol Synthesizer module (RF) 0x820000 PSM
PSMII Pol Synthesizer module II (RF) 0x820000
PSMIII Pol Synthesizer module III(RF) 0x820000
NIMIO32 Input/Output Register 0x100000 NIMIO32
MVME162 68040 board (VxWorks) that runs CAMP ✓ (bnmrvw) ✓ (polvw)
VMIC Linux machine in VME crate that runs frontend ✓ (lxbnmr) ✓ (lxbnqr)

The connections between the DAQ VME Modules are shown in BNMR DAQ Hardware Connections.

Software Components

The DAQ system is based on the MIDAS package. Data acquisition software to run the bnmr and bnqr experiments has been written to run under MIDAS. This includes the frontend, custom logger etc. This software is mostly common to both experiments, with the differences between each experiment handled by Midas ODB settings (most things) and a compile-time flag (choosing whether to build the febnmr or febnqr frontend).

The experiment is controlled using the MIDAS webserver (mhttpd). Due to the large number of experimental parameters required, Midas custom pages have been written for the experimenters to control and monitor their experiment.

The custom logger (mdarc/midbnmr) saves the data into MUSR MUD format files, and the MUSR CAMP slow control system is used for slow controls. Analysis is done by physica.

The DAQ software components are started by the script start-all and stopped by the script kill-all. These include standard MIDAS utilities (e.g. mhttpd, mlogger, mserver) as well as components specific to the bnmr and bnqr experiments.

The main DAQ software components specific to the bnmr and bnqr experiments are shown in the table below. A full ist can be found on the software overview page.

Table 3: DAQ Software Components
Component Host Experiment Purpose
Midas frontends
febnmr_32bit.exe lxbnmr bnmr the frontend sets up, reads out hardware modules, sends histograms.
The frontend code for both experiments is identical.
febnqr_32bit.exe lxbnqr bnqr
Midas clients - configuration isdaq01 both changes between experimental modes and between real/test runs isdaq01 both generates PPG program based on user-specified ODB parameters; reports calculated quantities in the ODB; sets up links in the ODB that should be stored in MUD files isdaq01 both low-level conversion of PPG program to PPG bytecode
Midas clients - logging
bnxr_logger.exe isdaq01 both writes data to MUD files. Reads information from midas banks (for scaler histograms), EPICS, and CAMP
logger_cleanup.exe isdaq01 both cleans up and archives any saved run files that were not properly archived. Run by user occasionally as needed. isdaq01 both responds to comments written by user in text box on the status page, saving to disk and/or midas banks
autorun isdaq01 both automatic run controller
scripts isdaq01 both scripts perform important functions e.g. kill-all, start-all. Scripts run at the begin and end of each run send information to the elog etc.
camp bnmrvw bnmr MUSR slow control system
polvw bnqr

Click the links in the above table for more details of each program.

Not listed above are various automated test programs for both the C++ and python programs. There are also some interactive test programs for debugging hardware issues.

Note that the DAQ was rewritten in 2020. Details of the rewritten in 2020. Details of the differences between the new DAQ (documented here) and legacy DAQ (documentation removed) can be found on the 2020 rewrite page.

DAQ Summary

The VMIC front end computer
  • runs the frontend code which
    • controls PSM,PPG, VMEIO, Scaler modules
    • acquires data from SIS MCS (scaler) module(s), builds histograms
    • uses channel access to control EPICS variable(s) (e.g. helicity)
    • periodically sends the data out into the data buffer
The host computer (isdaq01)
  • runs all other software components which
    • acquire the data from the data buffer
    • log the data
    • monitor the experiment
    • start/stop runs


In this document, " bnmr or bnqr " may be written as " bn[mq]r "

For example, directories :

/home/bnmr/online/bnmr spc and spc /home/bnqr/online/bnqr

are referred to by shortcuts such as

space /home/bn[nm]r/online/b[nm]r spc and spc ~/online/b[nm]r

Alternatively, these directories may be written as

  • /home/<experiment>/online/<beamline>
  • /home/<expt>/online/<beamline>
  • ~/online/<beamline>

where <experiment> <expt> and <beamline> are bnmr or bnqr.