Muon Halo Meeting Notes
2/26/20

Mike Wallbank (local)
Yagmur (local)
Patricia, Alex, Evan (remote)

Tom, me, Alyssa, Jason (local)

Mike W. presents background slides for experiment.
Expected/hopeful total particles for experiment presented.

Halo is in upper-west location of detector, i.e. above but in-line with secondary beam; note that secondary target production aperture is upward-facing.

Halo hit plots not being re-made after every potential improvement. Need to do that so we can tell if it helps.

NOvA DAQ not designed for running conditions in MCenter; front-end boards shutting off too frequently and dumping data due to high halo rate. Detector is not continuously live during spill, parts of detector are dead.

One FEB for half-plane (64 planes total).

32 GeV 7.5E8 best running mode in terms of FEB shutoff; only 64 was tuned however, during the scan. 1E8 too low rate to be worth it.

Metric to show # of live FEBs has been lost in most recent firmware update.

Initial spike in beam spill rate at detector is problematic and severe. Could be discontinuity in MECAR table, or beam position.

Secndary beam flux per proton on primary target is factor of 2 lower in reality than in simulation.

In real world, closing MC6V collimator does cut down on rate and muon halo. In simulation, doesn't have an effect on muon halo.

Muon momentum must be at least 5 GeV based on detector behavior.

Get real-time halo plot going so I can see if I can move it with the trims. Should probably run low rate on target so FEB shutoff doesn't artifact the plot.

Tom: turn off analyzer, secondary trims and quads, reduce rate so we don't get FEB shutoff. Scan momentum to see if halo moves. MC6D return yoke could be moving halo particles. Momentum scan changes MC6D.

Halo appears to be parallel to secondary beam? Not upward angle? Low-enough angle that we're limited by angular resolution of detector.

Does G4BL include field in magnet steel? Mike will check.

Tom suggested action items for upcoming week:
Do MC6D scan with all other secondary magnets off to see if halo changes/moves.
Fix MC6SC, re-do target position and angle scan.
EE Support meaure magnet impedance to make sure coil-to-coil short is ruled out.