• the lH2 is not ready, and
  • the trackers are okay
    we have an opportunity to take more solid absorber data.

I think we have to make a decision, as to whether we:

1. run LiH data; showing emittance evolution with 200 and 240 MeV/c
in flip mode
  • we get a few more data points; I note that we have 200 and 240
    MeV/c data in solenoid mode; this would give us comparable data in
    flip mode
2. run empty data; show the difference in performance between empty
absorber and full absorber in flip mode
  • we validate the existing data; we can show the difference between absorber in and absorber out, strengthening the existing data set. I guess there is a risk that colleagues tell us "you never checked the 'null hypothesis'"
3. run the wedge
  • we potentially get measurements in emittance exchange regime

I would appreciate thoughts. We could have a phone call at 15:00 BST
tomorrow (the usual MICE analysis slot) - this is coincident with the
16:00 coffee break at IPAC.

My feeling is:

- (1) is lower priority. It doesn't really give us much - we have detailed dE/dx measurements and scattering measurements at these momenta, and the performance won't be terribly impressive.
- (2) strengthens our existing dataset; mitigates risk
- (3) is likely to lead to another publication.

Other thoughts?


John Nugent
Pavel Snopok

  • Jaroslaw
    • it is important for us to run empty absorber; see the change of phase space distribution provided directly by the absorber
    • do we have sufficient data with the solid absorber data that we have a strong cooling signal
    • we could work on improved matching? could improve momentum scale; could improve alpha
  • Pavel
    • Preference - try the wedge? Question how much data we can get in the time available?
    • Note absorber changeover is 5-10 days; do we want to try the LiH first?
    • Wedge has never had fit test; but geometry is same as LiH disk; could take longer than LiH
    • One setting is probably all they need; use same magnet settings for emittance exchange and reverse emittance exchange
  • Jaroslaw
    • 200 and 240 MeV/c settings would be interesting to finish the momentum scan in flip mode
    • Would prefer to attempt to improve matching and redo data at 140 with LiH
    • Concerned that phase space has a hole in the region of interest
    • Aluminium drowns the effect a bit - significant but not dominant
  • Wedge continues to be interesting
  • Doing "no absorber" would be a good thing, but probably not the crucial thing; "empty absorber" would be acceptable
  • 200 and 240 MeV/c settings not terribly interesting
  • Would like to do LiH at 140 MeV/c with better matching
    • Jaroslaw suspects the current matching leaves voids in the phase space
  • Need more information:
    • How long to do the absorber changeover?
    • How sensitive is the issue of removing the lH2 absorber?
    • Do we really have holes in the phase space that better matching can address?

Updated by Rogers, Chris about 7 years ago · 13 revisions