1. C. Rogers, ASTeC Intense Beams Group Rutherford Appleton Laboratory
MICE Descope - Options
C. Rogers,
ASTeC Intense Beams Group
Rutherford Appleton Laboratory

2. MICE Descope

3. MICE Descope Options SS2 in downstream, no SS1
Measurement can be a difference measurement, i.e. absorber in vs absorber out
Upstream diagnostics for beam sampling or to control systematic due to instability in input beam
SS2 in upstream, no SS1
Tracker straight tracks for x, x', y, y'
EMR range for pz
TOF12 augments downstream PID and downstream pz
Use SS1 and SS2
Largely ruled out on grounds of risk
Should establish existence of viable optics

4. SS2 in downstream Questions
Can we find a viable optics to match to FCU? ?
Can we reconstruct well enough in the Quads+diffuser OR do a difference (absorber in vs out) measurement?
Durga

5. SS2 in upstream Questions
Can we get sufficient downstream detector performance?
Rogers/Francois
Does the beam scrape too much in TKD?
Rogers

6. SS2 in upstream Questions Can we get a reasonable optics?
Is the risk of further issues with SS1 too great?

7. Timescales Decision point is 27th May
Need to have main physics inputs ~ 20th May
Would like to see some convergence by ~ 13th May

8. C. Rogers, ASTeC Intense Beams Group Rutherford Appleton Laboratory
SS2 Upstream Option
C. Rogers,
ASTeC Intense Beams Group
Rutherford Appleton Laboratory

9. SS2 in upstream position

10. Revised TKD In primary absorber coordinate system:
Secondary absorber z = 1938 to 1976 mm
Stations at z = 2000, 2100, 2200 mm
Is more space needed (e.g. radiation shutters? He window?)
100 mm station spacing
500 micron spatial resolution
5 mrad scattering * 100 mm => 500 micron width for projected scattering distribution
x' resolution ~ 5 mrad * sqrt(2) = ~7 mrad
Straight tracks => 2 stations to make a straight track, 3rd station for redundancy/noise rejection
Is this sufficient redundancy?
Nb stations downstream see more scattering due to upstream stations
How much RF noise? Do we need extra shielding?
Use TOF2 and especially EMR for noise rejection
Very clear time resolved tracks in EMR...

11. Energy straggling in TOF2
F. Drielsma
F. Drielsma
Energy straggling through TOF2 makes noise on pz measurement in EMR
Gives ~ 1.4 MeV/c RMS for pz > 150 MeV/c
Gives ~ 2-4 MeV/c RMS for pz in range 100 – 150 MeV/c
One could remove TOF2; but energy straggling is not so big and it provides a nice redundancy/validation

12. Energy straggling in KL
F. Drielsma
F. Drielsma
Energy straggling through KL makes noise on pz measurement in EMR
Gives ~ 4.1 MeV/c RMS for pz > 150 MeV/c
Plan to use KL to characterise the beam
Consider KL-less arrangement for measurements which require improved pz resolution

13. Pz Reconstruction in EMR
F. Drielsma
F. Drielsma
Pz reconstruction width < 2 % for pz > 100 MeV/c
Compares well with tracker pz resolution at 4 T

14. Optics Using modified version of 200 MeV/c Demo latticeRF RF
TKD SA FC PA FC SA
Using modified version of 200 MeV/c Demo lattice
Remove SSD, keep currents/etc same
Nb some residual field in TKD
Can certainly optimise e.g. FCD
Asymmetry in the lattice optics
Could recover a bit by tweaking FC optics
RMS beam radius < 80 mm in TKD region

15. Optics Radial distribution at TKD 93 % of beam is transported to TKD
85 % of beam is transported through TKD fiducial cut
Again, could tweak the FC to move the focus back a bit

16. Emittance Reduction Descope BaselineRF RF
TKD
TKD SA FC PA FC SA
Descope
Baseline
See expected good emittance reduction in upstream region
No longer see emittance reduction in downstream secondary absorber
Beta is too high here?

17. Amplitude change Descope Baseline
Number of muons in each amplitude bin
Green – upstream
Blue - downstream

18. Ratio Descope Baseline Histogram
Consider the number of muons in each amplitude bin, n
Histogram is n(downstream)/n(upstream)
Line
Consider the number of muons with amplitude <= bin edge, N
Line is N(downstream)/N(upstream)

19. Effect of tracker radius
No radius cut
Radius cut
Tracker radius has little effect on core emittance reduction
Line has very similar trajectory

20. ToDo Reoptimise focus coil to move focus downstream
Does this “break” the lattice/cell argument?
Full resolution analysis/emittance calculation
Doing combined detector fit? Etc.