Beamline Session
MICE Collaboration Meeting CERN
Tues am. 30/03/04. Room 6-02-24.
Talk #
Time
Presenter
Talk Title
1
9:00
C. Booth
MICE Target Development Status
2
9:15
T.J.Roberts
Target Source Calculations
3
9:30
P.Soler
Particle ID Along The Beamline
4
9:45
K.Tilley
Design Concept and New Baseline Description
10:30
Coffee
5
10:45
T.J.Roberts
Beamline Performance with New Magnet Descriptions.
6
11:30
All/K.Tilley
General Discussion
1
MICE Target
Status
Chris Booth
30th March 2004
The challenge
• ISIS beam shrinks from 73 mm to 55 mm radius
during acceleration
• Target must remain outside beam until 2 ms before
extraction
• Then enters 5mm (into halo)
• Must be out of beam by next injection
• Beam cycle length 20 ms
• Target operation “on demand”, 1 to 10 (or 50) Hz
The challenge (continued)
• Operation in vacuum
– No lubricated bearings
– No convective cooling
• Operation in radiation environment
• Must cause minimal vibration
• Must be completely reliable and
maintenance-free
Basic drive specifications
• Travel >25 mm
• Peak acceleration (min.) ~1 mm ms-2
=1000 ms-2 =100 g
• Rep. rate
o On demand 1 Hz  10 Hz ( 50Hz?)
o (Machine cycle length 20 ms)
Ideal target motion
80
Position (mm)
75
70
65
beam
60
ideal
55
50
45
0
5
10
15
t (ms)
•
Infinite acceleration!
20
25
30
Diaphragm spring
Array of coils
Current design:
Moving magnet
Target
N
S
Section
Advantages
• Lower mass – light moving magnet (sintered neodymium-iron-boron)
• Stationary windings – more power, many cooling options
• Larger travel possible
Disadvantages
• Multiple coils
• More sophisticated power supply & commutator required
• Phase and amplitude control required
Control ideas
• 2 levels
– Rapid hardware position feedback to ensure 1-pulse stability.
– Pulse-to-pulse monitoring (software) to provide slow
adjustments.
Position monitoring requirements
• For monitoring - Precision 0.2 mm, sampled every 0.1 ms
• For drive phase control - Precision ~ mm, timing ~ 0.2 ms ?
Position monitoring method?
• LVDT (Linear Variable Differential Transformer)
– Good precision, but not fast enough
• Optical encoder
– Excellent precision, probably not fast enough,
not radiation hard
• Capacitive sensor?
– Precision, stability, speed not yet clear!
• Magnetic sensor?
– Is electronics rad hard?
Next steps
• Continue design studies with EEE
– Build prototype magnet/coil system
• Design/make/acquire diaphragm springs with
sufficient travel
• Develop fast position sensing
• Interface to power supply/driver
• Implement 2-stage feedback
• Test and characterise
Timetable??
• First prototype
Summer 04
• Develop control
Autumn 04
• System tests
Winter 04-05
• Cooling, stability tests
Spring-Summer 05
• Rad-hard components
Spring-Summer 05
• Interfaces with ISIS
Spring-Summer 05
• Implement improvements
Summer 05
• Final device construct/test
Autumn-Winter 05
• Install
Winter-Spring 06
MICE Target Development
Chris Booth & team
• Proposed activities April – August:
As per timeline.
• Any useful inputs from the Collaboration?
Alternative Position Sensing Ideas…?
MICE Target Source
Calculations
Tom Roberts
Illinois Institute of Technology
March 30, 2004
Model of Target and ISIS Beam
Parameter
Value
Protons in Bunch
2.5E13
Bunch Frequency
1.5 MHz
Good Target & Good RF
Duty Factor
Beam Radius
0.001
37.5 mm
Target Area
2 mm2
Beam Area
4418 mm2
Beam Density Factor*
0.1
Protons/sec on Target
1.4E12
* Estimate of: (beam density at target)/(average beam density)
Outline of Computation
• Select beamline tune, determine an enclosing target
acceptance (Pmin, Pmax, x’min, x’max, y’min,y’max)
• Use LAHET, MARS, and g4beamline (Geant4) to
determine pi+ that enter the target acceptance per
proton on target
• Use g4beamline to generate 20M pi+ into the target
acceptance, and determine how may good mu+ they
produce.
• Model the ISIS beam and target to determine the rate of
protons on target.
• Put the above values together to determine the absolute
rate of good-mu+/millisecond.
Target Particle Production
Particles into acceptance per millisecond of good target.
Particle
MARS
Geant4
pi-
3.2E5
2.8E5
e-
4.6E3
1.5E4
e+
0
1.6E4
gamma
7.0E5
5.6E5
1.1E6
9.7E5
7.2E6
4.1E6
6.2E6
3.6E6
pi+
LAHET
7.8E5
n
p
3.7E5
Target Source/Physics Work
Tom Roberts & team
• Proposed activities April – August:
Only nominally minor refinements...
• Any inputs requested from Collaboration?
None suggested.
Particle ID in the MICE Beamline
Paul Soler, Kenny Walaron
University of Glasgow and
Rutherford Appleton Laboratory
MICE Collaboration Meeting
30 March 2004.
Aims
• Carry out particle identification in the MICE
beamline using scintillation detectors.
• Use dE/dx signature to differentiate between
protons and pions/muons at different positions along
beamline: e.g. before Q1 and at input and output of
solenoid.
• Use PID information to qualify and monitor beamline
simulation.
Caveat: More a statement of intentions than results.
20
Scintillator layout
Would aim to have as little segmentation as possible
If rate proves to be a problem, perform segmentation, with smaller
segmentation in centre. For example:


Waveguides
PMTs

Scintillator
Waveguides
PMTs
Double sided readout allows to measure energy, independent of
position of particle along scintillator.
21
GEANT4 Beamline Simulation

MICE beam simulation prepared in GEANT4 (see Tom
Roberts presentation 24/9/03 and 14/1/04) showed
differences between G4 and other simulations:
Location
LAHET
geant4
After Q4
2114
1345
After Q5
1467
933
After Q6
1264
804
After Q7
444
282
After Q8
348
222
After Q9
336
214
After Tracker1
321
204
Good μ+ (40°)
157
100
Good μ+ (90°)
170
108
Good μ+ (no LH2, no RF)
178
113
57% difference!
Need to validate
simulations by
measuring rates,
profiles and
particle ID along
beamline.
22
MICE Beamline
New beamline layout
(Tilley/Roberts)
PID scintillators?
Q1
Q2
Q3
TOF1
TOF1
Diffuser2
B1
Decay
Solenoid
Proton
Absorber
B2
Q4 Q4 Q5 Q6 Q7 Q8
23
Conclusions



MICE beam simulation prepared in GEANT4 by Tom
Roberts to be used for beam and PID studies
Have started working with it, but still need to learn
more about programme and try to run different
configurations.
In the process of including particle ID elements to
enable design of scintillators (ie. segmentation,
thickness) to cope with particle rates.
24
Particle ID along beamline
Paul Soler, Kenny & team
• Proposed activities April – August:
* Experience with g4beamline
* Evaluation of JAN04/MAR04, for rates/beamsizes,
possible PID positions/segmentation. etc
• Any useful inputs from the Collaboration?
Other detector ideas to handle high rates near target ~ 1GHz?!
ie Cherenkov detector??
Design Concept & New Baseline Description.
• Brief Review of Design Concept:
• Beam Matching & Emittance Provision
• Design Concept
• New Baseline Description:
• Pre-amble: Abingdon & JAN04
• Inputs for Revising Layout
• Design of Present Layout & Results.
• Summary
Kevin Tilley , ISIS , RAL
paul drumm, mutac jan 2003
26
Design Concept ‘Lite’
Scheme to provide
simulateously:x’/y’
1
 RQD   0     0  2
2
1. Focus
Beam
with
0 , 0  0
Rbeam
x/y
MICE
ACCEPTANCE
2.  RQD &   
match ,   0
A
Matched after passing thru’
required scatterer
2


00
 0  

 0 0
 0  
This is the driving Design Concept in this design work:
To use ‘Beamsize’ & ‘Scatterer thickness’ to provide both
beam matching, & required emittance generation.
[Above figure illustrates case match region immediately follows scatterer]
paul drumm, mutac jan 2003
27
Inputs for Revised Layout
Collection of the Major inputs compiled after January ’04: ….
• Incorporate further changes to become more realistic for MICE:• Focusing and matching with Q35 Quads affirmed & not coils.
• Not designing achromatic muon extraction (maybe some residual dispersion…)
• Extend B1 – Decay Sol distance to fit wall-hole geometry (hole ≈ 650mm)
• Muon purity as high as possible (C2H4 absorber, pion focus at B2?)
• TOF0 – TOF1 Q4/Q5, Q8/Q9. Min Sepn 6.9m JAN04. TOF length 15cm.
• Q9 Saturation: Q9 – Start / End Coil 1.1 distance no closer than JAN04 (Q9 0.08T)
→ End / Q9MP – St/EC 1.1 ≥ 1.2169m
• Minimum Physical Pb. to Start / EC 1.1 distance:
EC-VacCh ~ 0.195 + TrServ ~ 0.03 + UpStrDtrSh ~ 0.15 + Space → Take 0.390m.
(here it is thus after Cherenkov & before any Upstream Detector Shielding)
• Max Additional total lengthwise movement of beamline/MICE – 2.00m
• Initial Muon Momentum Pu = 260Mev/c, for 236.5Mev/c after Pb (aiming at ctr A.v.p for p ref=200)
• Design for suitability at
 n , RMS  6 mm rad
• Spectrometer End Coils NOT available for beam matching.
• Quadrupole / Dipole FFs neglected. Use magnet effective lengths.
paul drumm, mutac jan 2003
28
Muon Extn Design:
Difficulties with finite Pb, - End Coil Seperation :
- First assessment of revising matching conditions before
scatterer, based on free field region Pb → EC. start. Clearly
approximation, and ‘maybe pessimistic?
R   RQD (  match 
• Finite distance to matching region (EndCoils here) means
incoming beam must be heavily converging into scatterer in
order that still converging to matched focus at EC.
d  0.390m, 6 , 236.5Mev / c

R  8.110cm
  833cm mrad!
12
Q
4
D
7
1
Q
5
T
F
0
?
Q
6
Q
7
C
D
8
1
D
9
1
D
1
1
4
Q
8
D
1
2
0
 12  
(d ) 2
 match
)
 RQD d
 match
Q
9
TD
F1
13
?0
P
b
P
T
immediately
before the scatterer...
 n, RMS  6 mm rad
paul drumm, mutac jan 2003
29
End Product Design Layout
d  0.0 m !
( Pb. currently within MICE!)
paul drumm, mutac jan 2003
30
Assessment with TTL
NET. after the Scatterer, and
Going into the Experiment…
WELL MATCHED
BEAM @ ~ 212Mev/c
+/-1% ~
212Mev/c.
+/-1% ~
Higher p ~
237Mev/c.
<p>~237Mev/c, Δp/p~11.6%:
paul drumm, mutac jan 2003
PARTIALLY MATCHED?
CMPT @ ~ 237Mev/c
31
Assessment with TTL
… First Estimate of where this might cover on the A.v.p momentum correlation chart?-
265Mev/c
<p> =237Mev/c
212Mev/c
209Mev/c
0.046
A  (   ) 
2
2
x
paul drumm, mutac jan 2003
2
y
(x2  y2 )

2




particle on
boundary
matched
rms ellipse

2 rms

 @  n,rms  5.2 , p  212Mev / c  A2  0.046
32
Summary
• Design Concept described.
• Motivations behind present baseline layout given.
• New ‘Baseline’ described.
• Current beamline provides <p>~237Mev/c, Δp/p~11.6%:
•Well matched component at 212Mev/c @  n, RMS  5.2 mm rad
•Partially matched dominating higher momentum component.
•Intention to revise for well matched @ 236.5Mev/c.
• Current modelling forced Pb-EC → 0 based on scheme.
Clearly one priority to consider same finite d cases including MICE
(EC/SS) FFs
• Incorporates most of other inputs.
paul drumm, mutac jan 2003
33
Design Concept & New Baseline Description
Kevin Tilley
• Any inputs need discussed by Collaboration?
1. Can we live with the present Good-beam ≠ p-peak ?
→ whatever accomodation: N(Good(μ) @ p – specified - lowered
(→ benefit from MAR04 Evaln of N(Good) @ 212 for current #s.
(Could also study benefit simplistically Good-beam = p-peak, as only chg!).
2. Affirm (how?) aiming ‘directly’ for Correlation? Never ‘quite’ understood <p> > ≠p-ref (mgt currents)
Design Concept & New Baseline Description
Kevin Tilley
Proposed activities April – August:
1a. Accelerator physics issues for Good-beam = p-peak, if sanctioned.
“SHOW-STOPPER SCENARIO”
- present known alleviating factors: RIKEN dec ch.-like ?
B2-angle.
1b. Study acceptable beamline changes affect on wall-hole position, if sanctioned.
“PROBLEM-’LITE’ SCENARIO”. (Ideally preferred if own constraints werent prob)
1c. Study potential future beamline changes to accommodate.
“PROBLEM-LIVEWITH SCENARIO”.
2. Reach agreement/incorp explicit fringe fields in bends/quads → minor revision?
(see also CodeConvergences)
2/3a.Investigate accurately affect of MICE FF on match & update min. Pb dists to end
coils for 6π (+).
2/3b.Investigate actual Pb thickness for 200ref-p, 236.5Mev/c (Avp) match.
(3a&3b) → Nominal Pb. position / weight support rqst for ReEn VacCh specs.
4. Exploring limits of available design 4 MICE (difft ref-Momentum, achievable
emittances (Pb-l), rates etc)? Achievable patch on A.v.p correlation?.
Code Convergences? (even whilst g4beamline evaln soon exceed potential realism
TTL, also even with statement g4beamline view as future final optimiser) – Э 2x+
support for continuing comparing ‘now’+. “In parallel” tho since accepted eg. not
priority in view of answering immediate engineering q’s (eg. wall hole, Pb? ….)
Schedule plans with collaborators  (TJR, PS etc, as necessary).
MICE Beamline
Performance with New
Magnet Descriptions
Tom Roberts
Illinois Institute of Technology
March 30, 2004
Progression of Magnet Descriptions
• JAN04 was designed using block fields, except for the
DecaySolenoid which used the coil field (no iron)
• In the New York Meeting I applied a simple Laplace
solution for the fringe fields of B1 and B2; since then I
have implemented COSY-style fringe fields for bends
and quads
• Full “rounded +” apertures in the muon quads Q4-Q9
(Q1-Q3 have circular apertures)
• Good magnetic map of the DecaySolenoid, including its
iron
• Good magnetic map of the upstream and downstream
magnetic shields
Comparison of Laplace to COSY-style fringe fields
Fringe Field Computation Comparison
RAL Type I Bend (H=152 mm)
1.2
1
COSY By (x=0, y=0)
B (Tesla)
0.8
COSY Bz (x=0, y=50)
0.6
Block Field Edge
0.4
Laplace By (x=0, y=0)
0.2
Laplace Bz (x=0, y=50)
0
-0.2 0
200
400
600
800
1000
-0.4
Z (mm)
All computations have the same integral By dz.
Downstream Magnetic Shield
(r and z scales are different)
Effects of the Improved Descriptions
Description
Factor
Cumulative
JAN04 (block fields)
1.00
1.00
Full apertures in the muon quads
Q4-Q9
1.17
1.17
COSY-style fringe fields in Bends
and Quads
1.42
1.65
Iron in DecaySolenoid
1.02
1.67
Magnetic shielding upstream and
downstream
0.97
1.62
Factor is from the good-mu+ rate.
Results
JAN04 tune, 6π mm-rad input emittance, no LH2, no RF.
Normalization
Program
Good mu+ per ms
LAHET
304
MARS
419
g4beamline
375
Major Variables:
• Beamline tune can vary rates by a factor of ~6 (tuning for
lower input emittance yields higher good mu+/proton)
• Target dip height directly affects protons on target (must
keep ISIS losses within bounds)
Because of the large variations in yield for different tunes,
and the need to keep ISIS losses to a minimum, an easilyadjustable insertion depth for the target is essential.
Beamline Performance/New Mgt Descriptions
Tom Roberts
• Any inputs need discussed by Collaboration?
1. Required beam rate? 600 Gd /sec? Know: – st. retune/cte studying/…invoke Tgt depths etc. if less.
Know Why: – st. to know context ie. apply to all Emittances/extnl constraints?
MINIMUM?
(maximum?)
2. Acceptable purities? Can go worse? Worst eg. ~ Mu/Pion @ TOF0, TOF1 etc?.
Beamline Performance/New Mgt Descriptions
Tom Roberts
Proposed activities April – August:
1.
Evaluate new layout MAR04 / 5.3.
2.
Reach agreement for explicit fringe fields in bends/quads
.(see also CodeConvergences)
3.
Appropriate integration with g4mice? Layouts, detectors?
(detectors: – TOF 2 utility?.)
Coding folding in issues also?? boundary point /
Code Convergences? (even whilst g4beamline evaln soon
exceed potential realism TTL, also even with statement
g4beamline view as future final optimiser) – Э 2x+ support for
continuing comparing ‘now’+. “In parallel” tho since accepted eg.
not priority in view of answering immediate engineering q’s (eg.
wall hole, Pb? ….)
Schedule plans with collaborators  (KT, PS etc, as necessary)
Beamline Technical Baseline
Tech Reference is not complete:
– Review what is presented;
But only by KT
after Session 
– Identify what is missing and who is charged to
Suggestions by
prepare it;
KT below….
• 1.4 Beam line Layout - Some minor mods – KT responsibility for
• 1.5 Expected Performance – To be updated with MAR04 – TJR agreed to provide.
• “MISSING/AWOL”: Re-insert as 1.6? Diagnostics? – Paul Soler/ PD ?
Beamline Technical Baseline
Tech Reference is not complete:
– Identify what is agreed (or not) as the
baseline
Following
aforementioned
suggested
mods to TRD →
BECOMES
DESCRIPTION
OF CURRENT
BASELINE ??.