A strategy for alignment of the T2 protect monitor, T2 target, and T2 Collimator A was discussed today and decided upon by Yuri Bylinski, Isaac Earle, Yi-Nong Rao, and Roman Ruegg.  The purpose of the adjustment is to try to reduce the amount of beam lost as it passes through the T2 area (presumably being blocked by the collimator because it is not possible to steer the beam through all three devices in their current configuration).  Keeping in mind that changing the elevation of Collimator A would be prohibitively time consuming it was decided that the protect monitor and target both be adjusted upwards 3.0mm compared to where they were during the 2016 running period.  This will result in the following elevations (all w.r.t. the T2 target flange).  The T2 profile monitor elevation will also be adjusted to match the target elevation.  

T2 Protect Monitor:  1833.5mm (1833.2mm from protect monitor flange)

T2 Target: 1836.5mm 

T2 Collimator A:  1834.7mm  (1834.5mm from collimator flange;  This is the current collimator elevation, measurement taken by Tom Lyth in Feb 2009)

These values are similar to what were used in 2009 during which time TNF neutron flux rates were acceptable (>800), and centered beam spots were achieved.  During the 2016 running period the beam spot on target was also roughly centered.  At both times the target was approximately 3mm lower than the protect which seems to indicate the beam is travelling at a downwards angle, possibly not correctable with available tuning.  This is a departure from the strategy in the last few years when the target and protect monitor were adjusted downwards to bring them closer to the beam plane (they had risen due to movement of the T2 monolith).  This is now thought to have been a mistake because it made it difficult to steer beam through the collimator.

Beam will be started with T2 in Position 2 (new target, never seen beam), then after a few days the target assembly will be moved to the hot cell to check the beam spot to confirm alignment and make changes if the strategy needs adjusting.

A PDF copy of Yi-Nong's summary is also attached.