The top mounting plate can be positioned whenever the techs come to do it. The machining and materials from UVA have arrived and are ready. This includes the bottom target tri-winged frame and the new aluminum feet holders. The threaded feet are also finished from FNAL. The dowel pins should be done soon. After this the lifter frame should go in and then the magnet can in principle go into position. In order for us to be ready for that we want new PTFE seals which are more radiation resistant. We need to clean and prep the magnet and can, and to do the docdock survey.
1.) Survey on docdock with full system open (no nose, no nitrogen shield, no beam windows). Survey the magnet aperture, the target insert along X only, and the outside fiducials (can and top flange). The primary goal of this survey is to generate fiducials on the can and top flange to help align when going into position in the cave.
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For SpinQuest it will be difficult to get the positioning of the target perfectly aligned with the beam. This is because all fiducials that we can get while the system is warm and open will change once we are running with liquid helium. We have X, Y positioning measured from averaged vertex reconstruction but this takes at least 1 month of data to produce, and this will only give the mean with a very large variance. This means we need to get the information we need from the survey and the final set of surveys will need to contain some cold target information. The precision in the target cell to beamline positioning needs to be good to mitigate large absolute errors while running. This is estimated to be on the sub-millimeter level (based on simulations being confirmed). There are several factors that can lead to false asymmetries relating to this precision. There can be a bias produced in the detector if there the beam is off center. There can be less polarized scattering if the beam is not aligned and missing part of the target (beam profile dependent, also being checked). There can be greater scattering off the aluminum ladder on one side as compared to the other. Most of these manifest from X being off but if Y is off over 1 mm then the same issues start to manifest with the ladder as well but this may not result in false asymmetry and only result in additional heat load to the coils. During our discussions with the survey crew it was suggested to install transparent windows so we could do an optical survey on the magnet and target cells while cold. This would be great to do but I do not think this is possible at FNAL. I don't believe we would ever pass a safety review to do that. The next best option is to do surveys using liquid nitrogen. We could calculate the level of contraction for both LN2 and LHe. We can then measure the contraction during an open system survey with LN2 in the magnet and in a nose with a window on it. The set of survey would go like this: 1.) Survey on docdock with fully open system (no nose, no nitrogen shield, no beam windows). Survey the magnet aperture, the target insert along X only, and the outside fiducials (can and top flange). The primary goal of this survey is to generate fiducials on the can and top flange to help align when going into position in the cave. This part of the survey should
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Use the leveling pads to level the magnet on the docdock before survey. This survey
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is plumb not the top flange is slightly off level. Working on the docdock for
this survey will have the advantage of space unlike in the cave. We can also
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