m.apollonioImperial College - London1 M. Apollonio University of Oxford the MICE diffuser: issues and operation MICE beamline review Nov. 16 th 2007 Imperial College, London

m.apollonioImperial College - London2 Layout purpose of the diffuser (MD) positioning along the line (z coordinate) radius choice thickness choice operations summary

m.apollonioImperial College - London3 purpose z position radius thickness operations summary MICE wants to measure cooling i.e. a reduction in normalized transverse emittance   must reach values up to 10 mm rad (NF)  

m.apollonioImperial College - London4 purpose z position radius thickness operations summary MICE beamline (trace space) emittance of  =1.4 mm rad (norm. transv. emittance) ~ 3 mm 200 MeV/c purpose of MD is to inflate initial emittance in a controlled fashion multiple scattering with some material along the beamline

m.apollonioImperial College - London5 purpose z position radius thickness operations summary z-position determines the upstream  function z DIFF out of the 1 st spectrometer  too large  at the last triplet of Q-poles  scraping optimal choice turns out to be: z=-6010 mm Z Z=0

m.apollonioImperial College - London6 purpose z position radius thickness operations summary 23.4 cm 21.2 cm 17.3 cm 11 cm C. Rogers MICE note mm just outside 1 st solenoid inside 1 st solenoid

m.apollonioImperial College - London7 purpose z position radius thickness oeprations summary 1 st issue diffuser inside the solenoid insertion/extraction mechanism with high B field on

m.apollonioImperial College - London8 purpose z position radius thickness operations summary z position fixed poses constraints to R diff R MAX = 15.5 cm

m.apollonioImperial College - London9 purpose z position radius thickness operations summary what happens if R<R MAX ? or, what drives our choice of R DIFF ? large amplitudes miss the disc  bias which R ?

m.apollonioImperial College - London10 purpose z position radius thickness operations summary Pz=209 MeV/c, B=4 T Pz=148 MeV/c, B=2.9 T Pz=267 MeV/c, B=4 T single disc tapered discs emi=10mm rad emi(R)/emi(R=30 cm) R_diff (cm) compare emi inflation to the case of large R(30 cm) Rdiff ~ 15 cm

m.apollonioImperial College - London11 purpose z position radius thickness operations summary 2 nd issue choosing max possible R for diffuser disc mechanical limitations: 1) changeable disc 2) external annulus fixed on the catcher

m.apollonioImperial College - London12 purpose z position radius thickness operations summary cross section of the actual disc + annulus in the diffuser catcher changeable disc fixed annulus catcher external envelope

m.apollonioImperial College - London13 purpose z position radius thickness operations summary determine thicknesses (T)   =1.4 mm rad x x’

m.apollonioImperial College - London14 purpose z position radius thickness operations summary determine thicknesses (T) find  1,  1 and t 207 MeV/c 200 MeV/c MeV/c Da1a1 a2a2 a3a3 RF 1 RF 2

m.apollonioImperial College - London15 purpose z position radius thickness operations summary 18 configurations studied: 1) P = 140, 200, 240 MeV/c (in the absorber centre) ∙FULL, EMPTY absorbers 2)  = 2.8, 6, 10 mm rad show group of similar solutions group into 5 thicknesses (+empty station)

m.apollonioImperial College - London16 MICE-NOTE-BEAM-0176 purpose z position radius thickness operations summary amended machined in MW

m.apollonioImperial College - London17 purpose z position radius thickness operations summary momentum before  D  upstream face of D  upstream face of D goal emittance

m.apollonioImperial College - London18 purpose z position radius thickness operations summary

m.apollonioImperial College - London19 purpose z position radius thickness operations summary 3 rd issue many thicknesses selection mechanism [mechanical issues being discussed in P. Lau talk]

m.apollonioImperial College - London20 purpose z position radius thickness operations summary a) select thickness = rotate main carousel b) lock/unlock lead plate onto disc catcher c) insert disc in the solenoid bore [mechanical issues in P. Lau talk]

m.apollonioImperial College - London21 purpose z position radius thickness operations summary summary lead discs needed to inflate emittance optimal z position inside solenoid bore 5 thicknesses chosen to meet MICE requirements: ( ,p) matrix demands system to: - select thickness from a main support (carousel) - transfer it to a catcher - insert into bore all remotely controlled and working in high B field current design meets all criteria