Simulations: tools and status

14/01/2008 MICE CM23 - Beam Line Parallel Session 1

Simulations:tools and statusMarco Apollonio, Imperial College - London


- G4Beamline: see presentation- ORBIT: see presentation- Turtle- Spreadsheets for BL


Optimising the BeamLine with MINUIT+Turtle


(,P) matrixP(MeV/c)(mm rad)

140 200 240

2

6 (7.1,207)

10


Pros & Cons

Turtle has been used since ever to design the reference Beam Line: P = 207 MeV/c (d.s. of the diffuser), emi_N=7 mm rad Turtle is a ray-tracing code, well established and capable of dealing with materials along the line.

It is not as sexy as G4 based codes and its I/O is pretty cumbersome, also the deck (system) is quite a pain in the neck ...

... however it works, it is fast and we don’t need a very sophisticated code at this stage

But we need the flexibility to change initial parameters of the beamline and find the currents for our magnets.

So far Optimisation has been done manually: a painstaking (and long) job


Optimisation via MINUIT is possible albeit not straightforward

As far as I know Turtle source code is not accessible: it comes as a black box, you change the deck and run it at your convenience

To dribble this problem I have used a main code that uses Turtle (Linux) as anexternal function and changes the magnet parameters in the deck as long as the optimisation goes (via a shell script)

A routine is used to calculate:- 4D normalized emittance, beta, alpha- beta_x, alpha_x, beta_y, alpha_y- muon transmission

These quantities can be used to force the beamline to reach some goal values. In the early days the goal was increasing Transmission, here it should be possible to shape the optics of the beam (we don’t do miracles though ... )


OUTPUT u.s.of the diffuser

INPUT: beamline u.s.Section

Q4 Q5 Q6 Q7 Q8 Q9

Q1 Q2 Q3 Sol

Beam Line is defined by 3 decks describing 3 elements of MICE BL1. Up Stream Beam Line

2. Transfer

3. Down Stream Beam Line

Dip

ole1

Dip

ole2

alpha0

alphaa0beta b0


Up Stream BeamLine Optimisation


100000 initial pionsNot much to optimiseThe spirit is a proof of principle


Original Configuration After OptimisationNOTA BENE: this is the MATRIX for PIONSwhile optimisation tries to make BETA(mu) flat in the solenoid

Bsol=4.2 T Bsol=4.4 T

TRANSPORT: Matrix Evolution


Down Stream BeamLine Optimisation


10000 muons traced, <15 minInitial TR=4.2% Final TR = 3.7%

Some resultsDS section Q4-5-6-7-8-9 optimisedusing SIMPLEX algorithm

Aim at 0 = 82.7 cm0 = 0.44as from diffuser prescriptions

Code tries to minimise the function((-0)/0.5)2 + ((-0)/0.04)2

Initial quadrupole currents

Initial emi_N, beta (4D,x,y), alpha(4D,x,y)

Aimed values: beta0, alpha0

final emi_N, beta (4D,x,y), alpha(4D,x,y)

Minimisation seems unable to get =0.44, it sets at around 0. no matter which precision is requiredHowever reaches the required value


''

2

2

1exp

2

2'

2

2

xxxx

xyxxNorm

x (cm)

y (cm)

********************************************** * * * Function minimization by SUBROUTINE HFITV * * Variable-metric method * * ID = 0 CHOPT = 0 * * * ********************************************** Convergence when estimated distance to minimum (EDM) .LT. 0.10E+01

FCN= 143.4691 FROM MIGRAD STATUS=CONVERGED 453 CALLS 454 TOTAL EDM= 0.12E-05 STRATEGY=1 ERROR MATRIX UNCERTAINTY= 2.9%

EXT PARAMETER STEP FIRST NO. NAME VALUE ERROR SIZE DERIVATIVE 1 P1 68.371 2.4827 -0.32050E-01 -0.21101E-03 2 P2 -0.86933 0.94910E-01 -0.39128E-03 -0.10718E-01 3 P3 4.6328 1.6825 0.48669E-02 -0.15841E-03 4 P4 3.4303 0.71097E-01 0.31790E-03 -0.14099E-01 5 P5 60.499 1.2328 0.74829E-02 0.10867E-02 6 P6 -0.15806 0.27740E-01 -0.61581E-04 -0.30442E-02

CHISQUARE = 0.1435E+01 NPFIT = 106

68.3 -0.86 4.63 3.43 60.49 -0.15 0.975016 2.07481 4.224281

********************************************** * * * Function minimization by SUBROUTINE HFITV * * Variable-metric method * * ID = 0 CHOPT = 0 * * * ********************************************** Convergence when estimated distance to minimum (EDM) .LT. 0.10E+01

FCN= 78.47191 FROM MIGRAD STATUS=CONVERGED 252 CALLS 253 TOTAL EDM= 0.23E-04 STRATEGY=1 ERROR MATRIX UNCERTAINTY= 2.9%

EXT PARAMETER STEP FIRST NO. NAME VALUE ERROR SIZE DERIVATIVE 1 P1 125.27 4.4452 0.67998E-01 0.87830E-04 2 P2 0.96546E-01 0.91543E-01 -0.15508E-02 0.70039E-02 3 P3 0.81872 0.88086 -0.22246E-02 -0.74252E-03 4 P4 3.3471 0.68870E-01 -0.13344E-02 -0.10475 5 P5 -32.680 0.59870 0.15268E-02 -0.68178E-02 6 P6 0.37815 0.21789E-01 0.38693E-03 0.77574E-01

CHISQUARE = 0.1019E+01 NPFIT = 83

125.2 0.09 0.81 3.34 32.67 0.37 0.857006 1.09118 2.22163

y’

x’


P (GeV/c)

215 MeV/c

x (cm)

y(cm)

at the end of the line [u.s. of the diffuser]


NO CUTSDP/P<10% (P=215 MeV/c)


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)


(cm)

25

0

25

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)


(cm)

25

0

25

16mz

q4

q5

q6

q7

q8

q9

-25

-20

-15

-10

-5

0

5

10

15

20

25

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Diffuser

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)


(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)


(cm)

25

0

25

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)


(cm)

25

0

25

16mz

q4

q5

q6

q7

q8

q9

-25

-20

-15

-10

-5

0

5

10

15

20

25

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)


(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)


(cm)

25

0

25

B2

Q4

Q5

Q6

Q7

Q8

Q9

PbPT

B1B2 Q4 Q5 Q6 Q7 Q9Q8

Pb.Disk

Vertical Half-width

(cm)


(cm)

25

0

25

16mz

q4

q5

q6

q7

q8

q9

-25

-20

-15

-10

-5

0

5

10

15

20

25

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Diffuser

http://www.isis.rl.ac.uk/accelerator/MICE/Task%20Notes%20and%20Specifications/beamline%20-%20optics/some_reference_data.htm

Beamline with Kevin’s parameters with MINUIT optimisation


Where do we go from here?

- the idea is that this system can be used to optimise the missing beam lines

- driving parameters are the BETA,ALPHA u.s. of the diffuser (for different and P)

- force the BL to reach those values and also try to maximize transmission


Spreadsheets for BL selection

http://mice.iit.edu/bl/Documentation/index_doc.html


calculates the local momentumaccording to a material budget table

dE/dX table (specific for material)

magnet rescaling table


Summary• All conventional magnets up and running• Solenoid down

– reduced rate• need to increase pion production

– target studies & improvement• tool to define beamlines by rescaling currents

currently used• tool (TTL + MINUIT) under test to optimise

future configurations


the END


The following two figures show the second order TRANSPORT beam profiles, corresponding to the above beam line optics (7.1π, 200MeV/c case). The initial pion source from the target occupied half widths of 0.255 cm and 0.1 cm in x and y (respectively) and 33.0 mrad and 14 mrad in x’ and ,y’, with a mean momentum of 444.71 MeV/c and uniform Δp/p =± 2.5%. The full width pion beam profile is shown in Figure 7.4 4.‑

2573 mm101.5 mm

3000 mm 4400 mm

x’=34mrad y’=23mrad

ex=0.085 mm radey=0.014 mm rade4D~0.023 mm rad

extra slides [on initial Beam Emittance]

Q1 Q2

Simulations: tools and status

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