Status of Progress on Beamline Design.

1
Status of Progress on Beamline Design.

• Review RAL Design Codes
• Status at Abingdon Meeting
• Motivations aims RE redesigning layout.
• Design of Present Layout Results
• Future Plans Required Inputs
• Suggested Steps towards new baseline.

• Kevin Tilley , ISIS , RAL

2
RAL Design Codes
Review RAL Design TOOLs
Two codes are used for designing and optimising
the beamline for MICE- TRANSPORT TURTLE see
eg. http//people.web.psi.ch/rohrer_u/turtle.htm
.
Both codes use a standard accelerator formalism.
Beamline components are treated as lumped
elements and particles coordinates are calculated
by applying a transformation which represents
each element -
TRANSPORT treats the full phase space of the
beam, to provide easily visualised beam profiles
- Fitting routines are also intrinsic to the
program.
TURTLE tracks individual particles based on the
common formalism. It also handles apertures,
decays and multiple scattering, and outputs
particle distributions at arbitrary points.
3
Status at Abingdon Meeting
50cm Y 0cm X 50cm
Pion Injection Decay Solenoid. (PION Profile)

Muon Extraction (MUON Profile)
50cm Y 0cm X 50cm
Scheme to generate and
simultaneously match into MICE-
4
Aims after Abingdon
These were a collection of suggestions made at
and shortly after the Abingdon collaboration
meeting .

• Make certain design changes to become more
  realistic for MICE-

• Distribute above design and work to obtain
  convergence between codes.

• ? In order to aid above objective.
• Use intial beam distribution flat distribution,
  2mm2, flat in ?p/p.
• No fringe fields in use except for solenoids.

5
Design of Present Layout
Sidetrack Design Process-
Pion Injection Decay Section-
1. First magnet group studied in TRANSPORT to
maximise pion acceptance. 2. Quadrupole Q3 and
decay solenoid studied to seek pion focus in
B2. 3. Pion injection optimised in TURTLE to
remove particle loss study pion B2 focus
Muon Extraction-
4. Initial Setup- Full distribution of muons at
end of decay section found from TURTLE.
5. Estimate of required (? beam
radius R focus) before scatterer made to
achieve the simultaneous and
beam matching into MICE. Initial Q4-Q9
arrangement found by focussing full muon source
as above before scatterer.
6. Iteration- a. Beamline re-run in TURTLE
subset of above muon distribution _at_ p0 which
reaches scatterer, used as new source. b. New
Q4-Q9 beamline arrangement for found
in TRANSPORT back to 6a!
Scattering Assessment-
7. Final muon distribution taken into separate
TURTLE file. Scatterer length estimated and then
iterated for
8. Long solenoid (presently only the spectrometer
solenoid) used to assess goodness of match of
beam.
6
Present design (PiDecay Sectn)
50cm Y 0cm X 50cm
0m (TGT)
7.434m 9.512m
15.182m
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Present design (Muon Extraction)
50cm Y 0cm X 50cm

• RMS Beam Profile
• Shows p0240Mev/c
• Collimation in x.

RRMS (27.2m) designed ? 5.76cm
15.182m 17.565m 20.537m
23.332m 26.3m 27.214m 28.489m
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Assessment with TTL
from TURTLE in 3rd/2nd Order ! from 10M
intial pions. Example plots-
gt Scatterer and 15cm channel radius
(spectrometer) Solenoid.
eg. lt Scatterer
z28.489m 0pi 71,957 mu
? Used as agreed End point for COMPARING CODES
(TR,KT)
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Future Design Plans
Problems with this present design - a.
Weve achieved some of the requests from
November, and indeed others not listed ) ,
however some problems need more attention.

• Make allowance for TOF PID needs after B2.

Disappointingly, it was found the design code
TURTLE cannot output path length data when
particle decays are switched on. Thus it was not
possible to compute times of flight.

• Pion beam focus at B2 (to aid pion/muon purity)

The pion focus has been improved in B2, however
without quads after the decay solenoid, its
difficult to make an ideal focus within B2 at the
high solenoid field used.

• Muon momentum P0 240Mev/c.

• The dipole B2s field is set for p0240Mev/c,
  however the whole beamline favours supply of p0
  260Mev/c muons !!!

• ? We LOOSE p0240Mev/c muons at present !!!

? Rescale pion injection, rescale muon
extraction? Increase p0 flux.
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Future Design Plans
Problems with this present design -b.

• Scatterer scheme not yet fully implemented.

Scatterer included for first time. Assessment in
TURTLE shows that muon beam before scatterer
scatterer length not yet as required. ? not yet
properly matched ? potential beamloss.
lt Scatterer
gt Scatterer
gt 15cm Spec. Solenoid
? UNMATCHED LIKELY BEAMLOSS !
..WE SEE THAT THIS IMPLEMENTATION IS NOT YET
COMPLETE
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Future Design Plans
Towards a Baseline Design...
Two Major Assumptions Made For/Towards a
Baseline Design-

• We assume we will be focusing and matching the
  beam in the muon extraction using Q35 Quadrupoles
  and not Coils.
• We assume we will not be designing an achromatic
  muon extraction (ie. there may be some residual
  dispersion in the muon beam).

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Future Design Plans
Plus other important inputs needed...
Source...?

• The field level of the entrance spectrometer
  end coil ? Fixed 4 T
  or can we use it for muon beam matching ?
• Proximity of scatterer to spectrometer end
  coil.
• Approx. allowable proximity of Q7-Q9 to spec.
  sol end coils.
• Current Pion-Muon purity OK ?
• Confirm mean muon p0 240Mev/c correct before
  scatterer?
• Agreement on dipole quadrupole fringe field
  parameters.
• Approx. TOF0,1 separation needed in quadrupole
  line for PID ?
• Double-check on hall-layout! (synchrotron side
  MICE-hall side)
• Approx. allowable proximity of B1,B2 to decay
  solenoid.
• Others!

PF ? KL/PF ?
PF /TJR/ KT ? BP ? KT / TJR TJR ? KT TJR ..

• A workplan ?!!!.

PD/KT/TR ?
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Possible baseline layouts
Possibilities being considered-
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Steps Towards New Baseline ?
In order to make progress towards new layout for
a Technical Document in March a timeplan is
proposed...
(This is newly proposed and still must be
discussed and agreed !!)
End Date ??
Responsible ?

• Gain increased convergence between TURTLE
  /GEANT4
• Obtain assumptions / inputs for redesign
• Revise update layout
• Make final evaluation of performance / small
  changes
• Complete writeup to New Technical Reference
  Document

2nd Feb 2nd Feb 25th Feb 15th March 22nd March
TJR / KT ALL KT TJR / KT ALL
at Latest!
or Earlier?
or Earlier?
NB- End Date does not imply workstage is
perfected but should be taken as the date at
which the best available design, assessment or
writeup is adopted and forwarded for the next
stage to begin.
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Summary

• Motivations behind present layout described.
• Beamline layout and results as assessed by
  TURTLE given.
• Comparisons between TURTLE /GEANT4 are ongoing
  (see talk by TR)
• Some assumptions external inputs needed
  before able to develop new redesigned - baseline.
• Would like to draw up workplan, timescale seems
  very tight before March.