MICE Collaboration Meeting March 29 - April 1, CERN MICE alignment, tolerances and supports Tuesday March 30 Room Edgar Black/IIT March Room

Alignment considerations What are we aligning A thought on alignment reference Considerations for tolerances Features of integration, design requirements Proposed designs solutions Support structures & transport concepts

What are we aligning The MICE cooling channel: 3-AFC modules 2-RFCC modules all the up beam and down beam measuring devices 2- Spectrometer detector modules 2- of each cherenkov, TOF, calorimeter and shielding The vacuum vessels in the cooling channel and the detectors constitute the structural support for the above components and are the essential reference for the alignment A major engineering challenge on alignment are the super conducting magnets by their shrinkage during cooling and by their large magnetic forces

Magnets lattice with shrinking estimated values ( black color numbers are the initial dimensions for alignment at room temperature) additional alignments are preformed after shrinkage.

Assembled MICE experiment lattice

Reference for the alignment The beam to be processed is the reference to which the lattice shall be aligned to It is proposed that line representing the center of the beam be the initial reference for alignment Targets installed on the outside of the modules vacuum vessels are calibrated to the line representing the beam inside This targets will be referenced to surveyors fixed bench marks in the RAL facility.

Tolerances considerations It is established that the modules vacuum vessels are the structural supports for the magnets they are the fulcrum for the alignment of MICE which demand careful selection of tolerances for their construction Industry has advanced on the tooling and the methodology for the fabrication of this vessels as shown in the samples on next pages

Custom engineered chambers are designed and manufactured using state of the art metal machining equipment as well as conventional machining and welding tools. Chamber fabrication tolerances have been optimized for cost-effectiveness and reproducibility. Unless specified otherwise the typical dimensional tolerances applied to all chamber fabrications shall be as follows... Chambers 24 inches in length or shorter will carry a ±0.02 inch linear tolerance. Chambers longer than 24 inches but shorter than 72 inches will carry a ±0.06 inch linear tolerance. All chambers will carry a minimum ±0.50° angular tolerance. Deviations from these specifications must be discussed with the MDC technical sales engineers for feasibility and cost

A, B and C are focal points. The Base flange sealing surface rests on a Reference plane. The zero point (0,0,0) is selected for symmetry and simplicity Ports are aimed at various focal points within the chamber. Chamber Cross Section with zero point The central reference point, or zero point, is given XYZ coordinates of (0,0,0). All focal point dimensions are measured from the zero point. Port lengths and angles are measured from focal points.

Example: Select Port Number 14 Port 14 spherical coordinates The polar angle of a port is measured in a vertical cutting plane that includes the focal point of the port and the centerline of the port. The azimuthal angle of a port is measured as a projection of the port centerline onto a horizontal focal plane that includes the focal point of the port. Port 14 is aimed at focal point C The cutting plane is vertical and passes through C The cutting plane is rotated about a vertical line through C to include the centerline of Port 14 The polar angle of 25° is measured in the cutting plane The azimuthal angle of 55° is measured in the focal plane

Integration of modules Ones the modules vacuum vessels are fabricated to specs the assembly between modules shall have the following requirements: 1. Primarily maintain the required separation to permit the extraction or removal of the AFC modules 2.Rigidly lock the vessels against internal and external forces in all directions 3.Maintain the vacuum inside the vessels and 4.provide a quick mean for the assemble and disassemble of the module form the lattice Several concepts are in consideration as presented on the next page proposed solutions

Proposed solutions Flex plates at the ends of the vessels

Existing design with a Gap of 9.7mm only

Option 1 – bellow type retractable seal

Option 2 – concertina type retractable seal Variation of the previous to facilitate assembly

Belt clamp arrangement Few bolts to clamp

Support structures & transport concepts For access to the inside of the AFC or RFCC modules for tuning, maintenance or other reasons, requires to remove any one of the modules from the lattice for each case; however, it will be to own advantage no to remove the RFCC after it is being tuned and aligned. The performance of this operation requires a careful controlled guided movement so not to tilt or twist the module within the narrow < 2cm gaps at each side The center of gravity of each module shall be carefully evaluated for the location and design of their support Several concepts are to be evaluated against the following requirements: 1.The modules support structures shall have provisions to allow anchoring at the in and out of the lattice positions 2.Shall provide means for the alignment of the module within a given value TBD