Motor controllers
Experiment → LI20 → MC03 (M5: EDC vertical) / MC02 (M7: EDC horizontal)
Introduction/Setup Description
The EDC screen is an electron spectrometer screen designed to measure 'low-energy' scattered electrons that either do not reach the beam dump or require less background noise to be measured.
The EDC screen mount holds two screens in a W-shaped holder. Both are DRZ standard. The setup is mounted on a horizontal and vertical stage (both motorized UTS stages).
Figure 1: Photos of installation during August downtime, looking from wall side (left) and showing the field of view in August on the Mako camera (right).
Dimensions and Location
Distance to infinite energy axis: http://physics-elog.slac.stanford.edu/facetelog/show.jsp?dir=/2022/32/09.08&pos=2022-08-09T23:57:00
z-position of screen relative to dipole: http://physics-elog.slac.stanford.edu/facetelog/show.jsp?dir=/2022/32/09.08&pos=2022-08-09T14:59:07
Screen dimensions: http://physics-elog.slac.stanford.edu/facetelog/show.jsp?dir=/2022/14/06.04&pos=2022-04-06T10:41:49
The screens have markings every 0.5 inches.
That along with the motion of the holder itself, dipole and quadrupole scans should be sufficient to get a decent energy calibration.
Energy estimates
Energy estimates based on distance measurements: http://physics-elog.slac.stanford.edu/facetelog/show.jsp?dir=/2022/32/12.08&pos=2022-08-12T14:25:00
Depending on dipole settings we should be able to see < 1 GeV up to the primary electron beam at 10 GeV.
Motor positions
Check Reference Motor Positions for most recents numbers.
Current OUT position is 90 in vertical and 75 in horizontal.
The vertical field of view is about 215 mm at the imaging plane. The screen is about 190 mm long, so we have 25 mm vertical drive to select a suitable energy range.
The low IN position (screen low → lower energies) is at 51 mm vertical and 44 horizontal. The high IN position (seeing higher energies) is at 26 mm vertical.
For the vertical motion positive numbers are further down in real space. For horizontal higher numbers are towards the aisle side.
To see the main beam 0 in vertical. To clear the beam just about by a few mm 10 in vertical.
http://physics-elog.slac.stanford.edu/facetelog/show.jsp?dir=/2021/32/11.08&pos=2021-08-11T23:13:18
These positions might change as the beam is being tweaked.
Camera triggers
The camera triggers are the same as for the dump table in general.
Find them at Main screen → Event → Profile Monitor →SIOC:LI20:PM02 → Dump_Table
Note that all dump table diagnostics use the same trigger, so changing TDES will affect those as well.
Remote light for reference
A light can be activated remotely to visually check the position of the screen and confirm motors are moving (and to take reference images).
The light is just a lamp attached to the top view port of the chamber. It is plugged in to the PDC power strip.
It can be found under:
Main screen → Experimenter → LI20 → PDC Power Strip → EDC Chamber Lights
Note: the light reaches all the way to the butterfly chamber. As a result, signal on DTOTR1 and other cameras might be affected. Coordinate use, especially during beam times.
Relevant PVs
Changelog
August 2022: Distance measurements and overview of changes http://physics-elog.slac.stanford.edu/facetelog/show.jsp?dir=/2022/32/09.08&pos=2022-08-09T15:00:03
April 2022: Distance measurements http://physics-elog.slac.stanford.edu/facetelog/show.jsp?dir=/2022/14/06.04&pos=2022-04-06T10:41:49
Oct/Nov 2021: The camera has been replaced by a Manta G895-B and a Navitar lens with 50 mm focal length and f 0.95, which optimises the field of view and collection efficiency.
Aug 2021: The screen is imaged via a mirror by a Mako G125-B with a small X mm lens (check with Erik) that sits outside of the EDC at a window port.
Shift summaries
Diagnostic checkout: http://physics-elog.slac.stanford.edu/facetelog/show.jsp?dir=/2021/32/12.08&pos=2021-08-12T10:04:37