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update on STEP III. M. Apollonio University of Oxford. the case for STAGE III. first demonstration of cooling with solid absorber(s) ?. Chosen configuration must comply with coil/physics constraints : 1- max current 2- temp. margin 3- b (min) minimise m.s. Matching Coils currents.
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update on STEP III M. Apollonio University of Oxford am041207
the case for STAGE III first demonstration of cooling with solid absorber(s) ? am041207
Chosen configuration must comply with coil/physics constraints:1- max current2- temp. margin3- b(min) minimise m.s. Matching Coils currents Set up a procedure to find the right MC currents for a matched beam:a) b (trk1-2)=1/k, a=0b) fix b(min) B (T) b(m) Z (m) am041207
800 mm am041207
(b) (a) 800 mm (a) (b) emi=10 mm rad T=98.4 % T=97.9 % am041207
NB: beta_min = 49 cm (was 60cm at CM14) means M1 1.4x, M2 0.7x main issues • current increase: is it within tolereances? • magnet forces? • MC distance = 800 mm. Can it be changed? 300 A! am041207
emittance growth in vacuum DeT/eT=2.8% eT (final)/eT (initial) ei=1.0 cm rad 0 1 2 3 4 5 6 Z (m) DeT/eT 2.8 % Z (m) am041207 eT (cm rad)
: emittance evolution in a cylindrical symmetric channel non uniform Bz can cause e growth (e.g. flip region) ecalc9 eT (m rad) MUC-NOTE 0071 prediction Most of the effect explained am041207 Z (m)
(a) 13 cm LiH absorber in the middle am041207
emi vs Z Pz vs Z Beta= 70cm -3% -7.3% Beta= 50 cm -3% am041207
vacuum (no absorbers) LiH absorber LiH absorber - vacuum am041207
emi. % variation vacuum growth subtracted equilibrium am041207
Conclusion • Slow B flip emi growth. Has to be minimized • a single absorber seems to work better • the middle point cannot have a low beta cooling effect reduced • reduce beta_centre increase M1 currents forces • better to place abs inside the II solenoid uneasy 6) transmission: large radius spool piece doesn’t seem to create dramatic effects am041207