1

Beamline

Day Time Presenter Topic

Thurs 9:00 C.Booth MICE Target

Wed 16:00 K.Tilley Recent Beamline Design Work

Wed 16:30 T.Roberts MICE Beamline Performance + Emittance Analysis

MICE Collaboration Meeting, RAL, Oct2004

Status of Target Design

Chris Booth

Sheffield

28th October 2004

Diaphragm spring

Target

Array of coils Magnet(s)

Position measurement

Schematic design

Linear Drive

Draft Specification• Transit: 40 mm

• Entry ≥ 5 mm into beam in ≤ 2 ms(see plot)

• Cycle time: 20 ms

• Positioning accuracy: 0.5 mm

• Timing accuracy: ~ 0.2 ms

• Frequency: (baseline) 1 to 3 Hz on demand

• (optimal) 1 to 50 Hz

• Maximum proton rate: 1.41012 per second

• Must operate in vacuum and radiation environment

• Must not interfere with ISIS operation!!

Target edge trajectoryWith spring

45

50

55

60

65

70

75

80

0 5 10 15 20 25 30

t (ms)

Posi

tion

(mm

)

beam

target

Diaphragm Spring suspension• Frictionless “bearing” allowing vertical movement• Must keep armature on axis to 0.2 mm (for magnet and position monitor)• Design of small spring obtained from Tom Bradshaw (RAL)• Scaled up to allow ≥40 mm travel• Finite element studies to check stress and lifetime issues (Lara Howlett)• Be-Cu sheet procured• Wire-erosion performed in Eng. Dept. workshop

Linear Drive (1)• Tests with first prototype

– Moving magnet shuttle (2 magnets)– Static single/double coil excitation– No commutator

~ radial field

S N N S

(Armature)

…however!• Current armature/coil design does not give required

acceleration

– 280 N kg–1 at 20 A mm–2

– Need ~950 N kg–1

revised armature design current density 35 A mm–2 for short pulses. Thus

effective cooling essential (proposing placing coils in conductive resin, surrounded by water cooling jacket…)

Improved armature design

soft iron Nd-Fe-B magnets

Sectored magnets – fixed together with aircraft glue

Also, other materials eg. SmCo?

x o o x o o

Coils

Armature

o x x o x x

x o o x o o

x o o x o o

Coils

Armature

o o x o o x

x x o x x o

“3-phase” drive

x o o x o o

Coils

Armature

x o x x o x

o x o o x o

x o o x o o

Coils

Armature

x o o x o o

o x x o x x

1 3

42

Magnetic actuator plus Hall switches bipolar drive

Radiation concerns• Studying documented radiation hardnesses

of target systems/components

• expected to be dominated by beam loss

produced during target insertion

• hope to make measurements at ISIS in

spring

Plans for next months• Complete revised design

- Optimised coil, armature design

- 3-phase switched drive circuit

• Currently mounting 1st prototype vertically on diaphragm springs

- Measure lateral stability

- Debug position readout system, check read speed

- Develop cooling and temperature measurement system

- Switch to new drive as soon as available

• Develop control hardware & software

paul drumm, mutac jan 2003 13

Recent Beamline Design Work

Kevin Tilley , ISIS , RAL

• Recent beamline revisions

• Description of SEPT04 beamline design

• Aims

• Calculation of beam momentas

• Envelopes and assessment with Turtle

• Future Plans

1

paul drumm, mutac jan 2003 14

Recent Design Revisions

JAN04 → first, new design concept

(JAN04A → lower emittance, higher Good Mu rate example)

MAR04 → Realistic geometry/constraints, C2H4 Mu purity

JUNE04 → Modified for correct definition

(JUNE04A → proposed chgs to lower TOF0, incr Good Mu)

… to Current work -

2

radmmyn 6,

paul drumm, mutac jan 2003 15

Motivations for new design - SEPT04

• To reduce muon design momentum from 236 → 206MeV/c

• Maintain (usual cut)

whilst at the same time, set the design for:-

• Low TOF0 singles rate

• High Good-muon rate.

radmmyn 6,

3

paul drumm, mutac jan 2003 16

Muon Momenta's

Defining the beamline momentums

For at 206MeV/c at exit of Pb, working backwards through the Pb and the C2H4 gives a value of 233MeV/c needed after the decay solenoid. [NB energy loss due to PIDs etc not included]

radmmyn 6,

4

Pion Momentum

For both a lower TOF0 singles rate, and for a high intensity final muon beam, we can use the high intensity working point relation from similar beamlines (PSI uE1/uE4 & RAL-RIKEN): -> 390MeV/c

Graph taken from PSI,SIN Users Handbook

yx ,

paul drumm, mutac jan 2003 17

Results of Optics work (Pi+Decay Sectn)

7

Q1'

Q2'

Q3'Q1 Q2 Q3 B1 Solenoid

Vertical Half-width

(cm)

HorizontalHalf-width

(cm)

25

0

25

16mz

Q1'

Q2'

Q3'

Q1'

Q2'

Q3'

Q1'

Q2'

Q3'Q1 Q2 Q3 B1 Solenoid

Vertical Half-width

(cm)

HorizontalHalf-width

(cm)

25

0

25

16mz

Now 3.7Tesla

• Full width beam profile

• Shows p0 @390Mev/c

paul drumm, mutac jan 2003 18

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)

HorizontalHalf-width

(cm)

25

0

25

16mz

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)

HorizontalHalf-width

(cm)

25

0

25

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)

HorizontalHalf-width

(cm)

25

0

25

16mz

Results of Optics work (Muon Extraction)

• RMS beam profile

• Shows p0 @220Mev/c

• Showing yx

8

paul drumm, mutac jan 2003 19

Assessment with TTL

Looking at usual momentum width, +/-1% ~ 206MeV/c:

(i) Beam & emittance > Pb.

xx' larger distribution (improvable with quad optics)

yy' 5.9pi & well matched~206MeV/c

347.0' rmsrms yy

mmradyy rmsrmsRQD 9.5)( ' radmmyn 9.5,

NB. Overall beam distribution: still has previous aberrations.

9

(ii) Indications of effect on TOF0 rates

Total particles (from 10^6 initial pions) at proposed TOF0 position [JUNE04 75423] -> [SEPT04 13864]

(iii) Indication of Good muon intensities?

Total muons in desired matched yy' distribution (usual cuts, & from 10&7 initial pions): [JUNE04 2574] -> [SEPT04 3423]

?

as desired

indicative

as desired

as desired

paul drumm, mutac jan 2003 20

Future design tasks

• PID/Beamline materials revision

• Switch to Q4-Q9 DFD FDF for better balancing (usual cut)

• Find reason for (& solve?) current aberrations in wider beam distribution ie:-

• making <p>=p-design

• attend to xx', yy' aberrations (improving match for wider dp/p)

• Produce various (p, ) cases as required for MICE

• Beam steering correction schemes (using trim coils on Quads etc.)

And as always…

• Continue TTL (/other) v g4beamline comparisons (and then improving realism of the design/evaluation codes)

yx

n

14

MICE Beamline Performance & Emittance Analysis

Tom RobertsMuons, Inc.

October 27, 2004

Summary of this Simulation

• The SEPT04 magnet currents/positions (optics) but also:– First guess of the beamline vacuum, windows, air

gaps. Also inclusion of PID materials in beamline.• More detailed implementation of Tracker1 and Tracker2

– Vacuum with windows– 5 planes, 1.5 mm scintillator each, located as in the

TRD• TRD configurations for everything except a few minor

things (absorber and RF window shapes, RF Cavity size, Cherenkov2 modeled as a circle)

The additional effect of the vacuum windows, air gaps & PID materials in this simulation.

μ+ central momentum in Tracker1 – design 206 MeV/c

μ+ central momentum in Tracker1 – achieved 183 MeV/c

This highlights the potential for further differences, betweenthe design goals and the results of this current simulation.

Summary of Rates

Description LAHET MARS Geant4

TOF0 2173 2676 2548

TOF1 513 631 601

Tracker1 462 569 542

Tracker2 343 442 402

TOF2 339 418 398

Good μ+ 336 414 394

Values are events per millisecond of Good Target and good RF.

Good μ+ = TargetDet & TOF0 & TOF1 & Tracker1 & Tracker2 & TOF2 & TOF1(μ+) & TOF2(μ+)

Emittance Computation - method

• SEPT04 beamline optics + PIDs, air & vacuum windows• Absorbers are empty, no RF• Analysis chain: g4beamline → for009sum → ecalc9f → excel• for009sum combines multiple FOR009.DAT files, and imposes cuts:

– Require through tracks (hits in all 10 Tracker stations)– Ptot cut, applied in the first region (Tracker1a)

• All cuts in ecalc9f are disabled (except PID), so the only cuts are:– Require each track to be a μ+ in all 10 Tracker stations– Require through tracks (hits in all 10 Tracker stations)– Ptot cut in Tracker1a (+/-5MeV/c ~ momentum of interest)

• A shell script was used to automate the interface to ecalc9f and connect the analysis chain together

Emittance Computation

Transverse Emittance in various Ptot bins

0

2

4

6

8

10

12

29 30 31 32 33 34 35 36 37 38 39 40 41 42

Position along Z (meters from ISIS Target)

Ep

erp

(m

m r

ad

) 165 MeV/c

175 MeV/c

185 MeV/c

195 MeV/c

205 MeV/c

215 MeV/c

Emittance @ 205MeV/c ≈ 8.2 pi mm rad

Conclusions

• The SEPT04 beamline optics were assessed, adding also the PIDs, air & vacuum windows in this simulation.

• TOF0 rates are lower than JUNE04 at ~ 2.5MHz

• The Good muon count is comparable to JUNE04.

• In this analysis, the input emittance for the bin +/-5MeV/c

about 205MeV/c is ~ 8.2 pi mm rad.

• The transverse emittance computed here increases in the empty cooling channel, at all momentums considered.

• A further beamline optics which accounts fully for the PID, air & vacuum windows should be produced and re-evaluated.