14/01/2008MICE CM23 - Beam Line Parallel Session1 Simulations: tools and status Marco Apollonio, Imperial College - London

14/01/2008MICE CM23 - Beam Line Parallel Session2 - G4Beamline: see presentation - ORBIT: see presentation - Turtle - Spreadsheets for BL

14/01/2008MICE CM23 - Beam Line Parallel Session3 Optimising the BeamLine with MINUIT+Turtle

14/01/2008MICE CM23 - Beam Line Parallel Session4 ( ,P) matrix P(MeV/c)  (mm rad) (7.1,207) 10

14/01/2008MICE CM23 - Beam Line Parallel Session5 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

14/01/2008MICE CM23 - Beam Line Parallel Session6 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 an external 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... )

14/01/2008MICE CM23 - Beam Line Parallel Session7 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 BL 1.Up Stream Beam Line 2.Transfer 3.Down Stream Beam Line Dipole1 Dipole2 alpha  0 alpha  a0 beta  b0

14/01/2008MICE CM23 - Beam Line Parallel Session8 Up Stream BeamLine Optimisation

14/01/2008MICE CM23 - Beam Line Parallel Session initial pions Not much to optimise The spirit is a proof of principle

14/01/2008MICE CM23 - Beam Line Parallel Session10 Original Configuration After Optimisation NOTA BENE: this is the MATRIX for PIONS while optimisation tries to make BETA(mu) flat in the solenoid Bsol=4.2 T Bsol=4.4 T TRANSPORT: Matrix Evolution

14/01/2008MICE CM23 - Beam Line Parallel Session11 Down Stream BeamLine Optimisation

14/01/2008MICE CM23 - Beam Line Parallel Session muons traced, <15 min Initial TR=4.2% Final TR = 3.7% Some results DS section Q optimised using SIMPLEX algorithm Aim at  0 = 82.7 cm  0 = 0.44 as 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 required However  reaches the required value

14/01/2008MICE CM23 - Beam Line Parallel Session13 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= 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 P E E-03 2 P E E E-01 3 P E E-03 4 P E E E-01 5 P E E-02 6 P E E E-02 CHISQUARE = E+01 NPFIT = ********************************************** * * * Function minimization by SUBROUTINE HFITV * * Variable-metric method * * ID = 0 CHOPT = 0 * * * ********************************************** Convergence when estimated distance to minimum (EDM).LT. 0.10E+01 FCN= 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 P E E-04 2 P E E E E-02 3 P E E-03 4 P E E P E E-02 6 P E E E-01 CHISQUARE = E+01 NPFIT = y’ x’

14/01/2008MICE CM23 - Beam Line Parallel Session14 P (GeV/c) 215 MeV/c x (cm) y(cm) at the end of the line [u.s. of the diffuser]

14/01/2008MICE CM23 - Beam Line Parallel Session15 NO CUTS DP/P<10% (P=215 MeV/c)

14/01/2008MICE CM23 - Beam Line Parallel Session16 mline%20-%20optics/some_reference_data.htm Beamline with Kevin’s parameters with MINUIT optimisation

14/01/2008MICE CM23 - Beam Line Parallel Session17 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

14/01/2008MICE CM23 - Beam Line Parallel Session18 Spreadsheets for BL selection

14/01/2008MICE CM23 - Beam Line Parallel Session19 calculates the local momentum according to a material budget table dE/dX table (specific for material) magnet rescaling table

14/01/2008MICE CM23 - Beam Line Parallel Session20 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

14/01/2008MICE CM23 - Beam Line Parallel Session21 the END

14/01/2008MICE CM23 - Beam Line Parallel Session22 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 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 MeV/c and uniform Δp/p =± 2.5%. The full width pion beam profile is shown in Figure 7.4 ‑ mm mm 3000 mm 4400 mm x’=34mrad y’=23mrad ex=0.085 mm rad ey=0.014 mm rad e4D~0.023 mm rad extra slides [on initial Beam Emittance] Q1 Q2