Minutes of meeting held on 13 Aug 2020
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https://beamdocs.fnal.gov/AD-public/DocDB/ShowDocument?docid=8630

(1) Phil gave a talk on the new MI8 collimators.
    (i) The existing two pairs of collimators are at MI-8. Each pair
    consists of one big block that scrapes on one edge of the beam and
    the other big block scrapes the other side. Another pair is at 90 deg phase
    advance from this pair of collimators.  Each collimator is
    4 T of steel.
    (ii) The present collimators are at 836/838
    (iii) They have been very successful. They have done a great job
    of scraping beam before it hits the ring collimators. Factors of 3
    to 5 reduction in losses in the ring because of these collimators.
    (iv) The existing collimators are too small. They do not contain
    enough of the hadronic shower.
    (v) They are too hot to move/replace.
    (vi) Plan is to add new collimators upstream.
    (vii) We are close to limit for increasing the beam intensity.
    
    (viii) The new collimators are single pass for 8 GeV beam.
           (a) Two stage collimators do not work because there isn't
    	   enough deflection from the primary. Thin scraper becomes 1
    	   m long which makes them full collimators. Prefer the same
    	   style of collimators as presently used in
    	   Recycler. Collimators will have to be 20 T scale to better
    	   contain hadronic showers.
	   (b) The aperture will be as small as possible for
           containment of the out scatter.
	   (c) The core box will be tapered upstream and downstream
           to match changing beta functions. This has not
           been done before. This means good orbit control is
           required.
	   (d) The new collimators will be about 1.5 m in length. Sim
	   required for final length
	   (e) There is some confidence in beta functions. There will
           be a lattice monitoring system to try to control the
           lattice. The degree of uncertaintly is within how they tune
           things.
   (ix) The MI-8 can't be as tall as the Recycler collimator but has
         the same concept: only the central third moves vertically.
   (x) The beam centre is 2 ft from the floor and wall. Need space on
   the aisle space for RECO.
   (xi) Installation location
   	(a) Want < 1m disperson.
	(b) Best location for low dispersion is at 823 to 827 which is
	far enough from Booster. The other low dispersion locations are
	too close to Booster or too close to the existing collimators
	(too hot to work).
   (xii) There is an advantage of having 45 deg phase advance from the
   old collimators. You can get a nice octagon collimation
   pattern in phase space. Right now putting the new collimators at 825 and 827 is
   preferred choice.
   (xiii) There is 5.2 m of open space in each location. Strawman
   design of two mobile collimators plus a fixed mask at each
   location.  Mask to absorb outscatter.
   (xiv) Toy simulation consists of coll1 and coll2 and mask
   downstream. Sim as follows:
      (a) Pencil beam strikes col2
      (b)  There is beam leakage out of col2 and a mask.
      (c) Loss pattern argues for not having a longitudinal gap
   between col 2 and mask.
      (d) Require real simulation to figure out the length of the collimator.
      (e) Back scatter is coming back from col2.
   (xv) Time scale to install: Depending on the division's
   budget. Potentially, installation in 2021 shutdown. It is basically an
   improved copy of the Recycler collimators.