# update on STEP III - PowerPoint PPT Presentation

1 / 15

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.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

update on STEP III

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

## 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)

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)

0 1 2 3 4 5 6

Z (m)

DeT/eT

2.8 %

Z (m)

am041207

: emittance evolution in a cylindrical symmetric channel

non uniform Bz can cause

e growth (e.g. flip region)

ecalc9

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

(b) 13 cm LiH absorber in the II solenoid

am041207

vacuum (no absorbers)

LiH absorber

LiH absorber - vacuum

am041207

emi. % variation

vacuum growth subtracted

equilibrium

am041207

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