BNMR: Experimental Modes

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This page describes the different Experimental Modes (also known as PPG Modes) available for the bnmr and bnqr experiments. Not all modes are supported for both bnmr and bnqr experiments. New modes are added as needed.

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).

All modes are of Type 1 (c.f. I-musr), type 2 (c.f. TD-Musr), or a combination of both types. All Type 1 modes have a designation starting with "1", e.g. "1a","1f". Similarly all type 2 modes start with a "2", e.g. "2a", "2e". Some modes also have a name, e.g. Mode "10" is called "Scalers", Mode "20" is called "SLR".

Note that the data are saved in different histograms depending on whether the mode is Type 1 or Type 2. The combination modes are given a type designation (1 or 2) according to how their histograms are saved.

Type 1 (I-MUSR)

In Type 1 modes, a variable is incremented between a maximum and a minimum value forming a "scan", which is then repeated. At each increment, one of more PPG Cycles are run, and the data are stored in histogram memory in the frontend. In this mode, the histogram data are output after each increment, and saved as MIDAS-format data by the standard MIDAS logger mlogger. The helicity may be flipped after each complete scan, or, in some modes, after each PPG Cycle. The frontend histogram memory is cleared after the data are output at each scan increment. This MIDAS-format file is then converted to MUD-format by the MIDAS client mdarc.

Type 2 (TD-MUSR)

In Type 2 modes, the scaler data for each PPG Cycle is accumulated in the histogram memory in the frontend. The RF may be turned on for part of the cycle. The histogram memory is only cleared at the begin-of-run, and the histograms are accumulated within the frontend. Periodically, the data is read out bymdarc, and saved directly into MUD format.

Full list of modes

Click here to see a full list of experimental modes, or use the modes webpage for more detailed information about each mode.

Changing the mode

The available experimental modes are displayed on the modes webpage, and the mode can be changed using the the modes webpage, the settings webpage, or the mode changer python script. Each mode has its own set of run parameters, which are displayed on the settings webpage.

Adding a new mode

See the adding a new mode page.