Workflow conveniences

A handful of beamline-honed conveniences that make the browser-and-plot loop faster: run-quality columns, field read from the data log, a log-count diagnostic, plain-text export, and a measuring cursor. Each is described below with the question it answers.

Run-quality columns

The Data Browser shows Run, Title, T, and B by default. Right-click any column header and choose Add column… to add a run-quality column; the chosen set is remembered with the project. Two are worth knowing:

  • Good Events (MEv) — the total counts inside the good-bin range, summed over the forward and backward groups, in millions of events. This is the number that governs the statistical reach of a run: a fit’s parameter errors scale roughly as \(1/\sqrt{N}\), so a run with 8 MEv reaches about \(\sqrt{8/2}=2\times\) tighter than one with 2 MEv. It differs from Counts (MEv), which sums every bin including the pre-\(t_0\) and dead tail — Good Events is what actually enters the asymmetry.

  • Events/frame — Good Events divided by the number of acquisition frames, a rate-independent measure of how much beam each run collected. Use it to spot a short or beam-starved run in a temperature series before you trust its fit.

Removing a column is the same menu (Remove from Data Browser).

Field from the data log

A run’s B value normally comes from the file header — the setpoint. When the magnet is ramping or drifting, the logged field is the honest one. Options → Use field from log replaces the B column with the mean of the magnetic-field log channel, exactly as Use temperature from log does for T. Log-sourced cells are tinted and read-only (editing a measured mean is meaningless); turn the option off to return to the header value and the editable cell.

The choice can be made per run from the run-information dialog, and for a co-added run the field is the event-weighted mean of its constituents. When a run carries no field log, the header value stands — there is no silent substitution.

As with temperature, the displayed B value is what a batch parameter trend plots and exports: a field trend follows the logged field when this option is on (see How the T / B abscissa is sourced).

Log-count diagnostic

Switch the time view to Raw Counts and tick Log scale. A pure muon-decay histogram is

\[N(t) = N_0\,e^{-t/\tau_\mu} + b,\]

so on a logarithmic count axis it is a straight line of slope \(-1/\tau_\mu\). That makes three faults jump out that are invisible on a linear axis:

  • a mis-placed \(t_0\) kinks the line at early time;

  • a wrong background \(b\) bends the tail upward as the exponential dies and the constant takes over;

  • deadtime at high instantaneous rate flattens the earliest bins.

None of these need a fit to see — the log-count view is the standard first look at a freshly grouped run. Empty bins (zero counts) have no logarithm and are simply dropped from the plot.

Plain-text data export

The Export… button on the plot offers two destinations. Export to GLE… writes the full .gleplot package as before. Export plotted data (text)… writes just the data — no GLE script, no compile — for loading into any other program. Choose:

  • Data only — time, asymmetry, and error columns;

  • Data + fit — the data file plus a .fit sidecar of the fitted curve;

  • Fit only — the fitted curve alone.

Tick Limit to current x-range to export only the window you are looking at. Every file carries the same commented provenance header as the GLE sidecars — run number, grouping, \(\alpha\), deadtime — so an exported spectrum stays self-describing. Exporting one curve prompts for a filename; exporting several prompts for a folder.

A measuring cursor

Hovering over a plotted curve snaps the cursor to the nearest data point and reports, in the status bar:

  • the point itself, \(t\) and \(A\);

  • the signal-to-noise \(|A/\sigma|\) there — a quick “is this feature real?” before you commit to a fit;

  • a parabolic peak: the sub-bin position and height of a local maximum, fitted from the point and its two neighbours. This reads a line in an FFT or MaxEnt spectrum, or an avoided-level-crossing (ALC) resonance centre, to better than the bin spacing without setting up a fit;

  • a windowed average \(\langle A\rangle \pm \sigma\) over the visible x-range — the level of a baseline, an asymmetry plateau, or an ALC/repolarisation step, with the same error-on-the-mean a time-integral would give.

The readouts appear only on a single-curve view, where the snap is unambiguous; on stacked subplots the cursor reports its raw position.