Magnetic fields of the optical matching devices used in the positron source of the ILC

Transcription

1 Magnetic fields of the optical matching devices used in the positron source of the ILC Richard Pausch Dresden University of Technology DESY Summer Students Programme 2010 Supervisors: Andreas Schälicke, Andriy Ushakov DESY Zeuthen November 18 th 2010 Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 1/25

2 1 DESY sumer school The Summer School The Linear Collider Group 2 Introduction to the work The International Linear Collider The positron source PPS-SIM 3 Quarter wave transformer (QWT) Design Simulations Function for the fit Results 4 Adiabatic matching device (AMD) Design Simulations Problems Results 5 Conclusions Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 2/25

3 1 DESY sumer school The Summer School The Linear Collider Group 2 Introduction to the work The International Linear Collider The positron source PPS-SIM 3 Quarter wave transformer (QWT) Design Simulations Function for the fit Results 4 Adiabatic matching device (AMD) Design Simulations Problems Results 5 Conclusions Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 2/25

4 DESY - Zeuthen - Summer Students Programme Summer Students Programme every year Duration: 1,5 month from July 20 th to September 9 th Hamburg and Zeuthen Lectures and work in groups Students from all over the world Work in the fields of: experiments in elementary particle physics development of particle accelerators theory of elementary particles computing Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 3/25

5 The Linear Collider Group The Linear Collider Group: dealing with the International Linear Collider as part of the ECFA Study in Zeuthen: Physics studies Positron polarisation R&D for the Very Forward Region of the ILC (forward calorimeter) Detector simulation Beam diagnostics and beam energy measurement Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 4/25

6 The Positron Source Group At the ILC polarized electrons and positrons will be used. Why polarization? suppressing standard model processes enhancing effective luminosity supersymmetry positron source group in Zeuthen: simulation of the positron source developing a software called PPS-SIM optimization of the positron s polarization and yield radiation and activation Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 5/25

7 1 DESY sumer school The Summer School The Linear Collider Group 2 Introduction to the work The International Linear Collider The positron source PPS-SIM 3 Quarter wave transformer (QWT) Design Simulations Function for the fit Results 4 Adiabatic matching device (AMD) Design Simulations Problems Results 5 Conclusions Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 6/25

8 International Linear Collider (ILC) proposed counterpart to the LHC polarized e + e -collisions Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 7/25

9 The positron source 150 GeV e ~147 GeV e Target Pre accelerator ( MeV) Booster Linac (cryomodules to boost energy to 5 GeV) Helical Undulator Collimator (upgrade) OMD Capture RF (125 MeV) e Dump 500 MeV e Dump Pre accelerator ( MeV) Damping Ring Target Dump OMD Capture RF e Dump (125 MeV) aim of the OMD: increase the positron yield (not to scale) several Optical Matching Devices Quarter Wave Transformer, Adiabatic Matching Devise and Lithium Lens Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 8/25

10 PPS-SIM Polarized Positron Source - Simulation optimize the positron source based on Geant4 and ROOT simulation of electromagnetic and hadronic showers polarisation transfer in physics processes particle and spin tracking in electromagnetic fields adjustable geometry and GUI batch mode for high statistics runs only simplified magnetic fields Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 9/25

11 1 DESY sumer school The Summer School The Linear Collider Group 2 Introduction to the work The International Linear Collider The positron source PPS-SIM 3 Quarter wave transformer (QWT) Design Simulations Function for the fit Results 4 Adiabatic matching device (AMD) Design Simulations Problems Results 5 Conclusions Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 10/25

12 Design of the QWT QWT: first two solenoids Solenoid surrounding the RF-cavity Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 11/25

13 Simulations mathematical background: Maxwell s equations B = µ r µ 0 j and B = A Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 12/25

14 Simulations mathematical background: Maxwell s equations B = µ r µ 0 j and B = A ˆ A( r) = d 3 r j( r ) r r A = (0, A ϕ, 0) Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 12/25

15 Simulations mathematical background: Maxwell s equations B = µ r µ 0 j and B = A ˆ A( r) = d 3 r j( r ) r r A = (0, A ϕ, 0) Implemented Formula ( ) A = j µ 0 µ r boundary conditions material properties current densities Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 12/25

16 ^ ^ Simulations Results from FlexPDE finite element method returns discrete data from the grid points QWT - quarter-wave-transformer flux density B_z in T (ovset from axis: 0.5m) Z QWT: Grid#6 P2 Nodes=8029 Cells=3978 RMS Err= 4.8e-5 Surf_Integral= :20:50 9/7/10 FlexPDE 6.13 flux density B_z in T (ovset from axis: 0.5m) from (-0.20,0.005) to (1.50,0.005) 1: dr(aphi)+aphi/r 1 2 QWT - quarter-wave-transformer R e flux density B in T zoom(-0.20,0,0.40,0.35) QWT: Grid#6 P2 Nodes=8029 Cells=3978 RMS Err= 4.8e-5 Z max min :20:50 9/7/10 FlexPDE 6.13 Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 13/25

17 Function for the fit FlexPDE gives discrete data needs to be fitted obvious approach: vector potential A Gauss s law for magnetism B = 0 Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 14/25

18 Function for the fit FlexPDE gives discrete data needs to be fitted obvious approach: vector potential A Gauss s law for magnetism Laplace equation B = 0 2 ψ(r, θ, φ) = 0 Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 14/25

19 Function for the fit FlexPDE gives discrete data needs to be fitted obvious approach: vector potential A Gauss s law for magnetism Laplace equation B = 0 2 ψ(r, θ, φ) = 0 Magnetic field from scalar function B = ψ(r, θ, φ) spherical harmonics Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 14/25

20 Results Work: simple χ 2 function χ 2 = ( ˆB z (ρ, z) B z (ρ, z) fit was done using python and minuit2 for several different currents Final results: 39 parameters for the spherical harmonics linear relationship between current and parameters magnetic flux density is calculable for different currents implemented in PPS-SIM ) 2 Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 15/25

21 Results below 10% deviation on main beamline Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 16/25

22 Results 5 B sim /T B fit /T ρ/cm 0.6 ρ/cm z/m 5 B z /T z/m 5 relativ error in % ρ/cm 0.10 ρ/cm z/m z/m 0 Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 17/25

23 1 DESY sumer school The Summer School The Linear Collider Group 2 Introduction to the work The International Linear Collider The positron source PPS-SIM 3 Quarter wave transformer (QWT) Design Simulations Function for the fit Results 4 Adiabatic matching device (AMD) Design Simulations Problems Results 5 Conclusions Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 18/25

24 Design of the AMD Adiabatic matching device e z, r zoom(-0.04, 00, 0.24, 0.3) 14:27:18 8/11/10 FlexPDE R shaping plates with cuts 5 solenoids pulsed current 2D and 3D model Z e-2 AMD-1: Cycle=56 Time= e-4 dt= e-5 P2 Nodes=11673 Cells=5804 RMS Err= 6.3e-6 Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 19/25

25 4. 0.Z56 3D-Model of the AMD Y X Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 20/25

26 Simulations mathematical background: Gauss law B = µ 0 µ r ( j + j ind. ) + µ 0 µ r ε 0 ε r E t E = A t j ind. = σ E Implemented Function ( ) A µ 0 µ r = j σ A t ε 0ε r 2 A t 2 Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 21/25

27 Problems implementing 2D model implementing 3D model several attempts to include geometry working model implementing physics 2D no influence of the cuts cut simulated by conditions for induced currents implementing physics 3D no simple way to keep the boundary conditions for the induced currents cut has therefor no effect in simulation Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 22/25

28 Problems implementing 2D model implementing 3D model several attempts to include geometry working model implementing physics 2D no influence of the cuts cut simulated by conditions for induced currents implementing physics 3D no simple way to keep the boundary conditions for the induced currents cut has therefor no effect in simulation Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 22/25

29 Problems implementing 2D model implementing 3D model several attempts to include geometry working model implementing physics 2D no influence of the cuts cut simulated by conditions for induced currents implementing physics 3D no simple way to keep the boundary conditions for the induced currents cut has therefor no effect in simulation Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 22/25

30 Problems implementing 2D model implementing 3D model several attempts to include geometry working model implementing physics 2D no influence of the cuts cut simulated by conditions for induced currents implementing physics 3D no simple way to keep the boundary conditions for the induced currents cut has therefor no effect in simulation Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 22/25

31 Problems implementing 2D model implementing 3D model several attempts to include geometry working model implementing physics 2D no influence of the cuts cut simulated by conditions for induced currents implementing physics 3D no simple way to keep the boundary conditions for the induced currents cut has therefor no effect in simulation Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 22/25

32 Results Adiabatic matching device e-2 6. o 5. 4.! / R cm x flux density B / T 13:55:05 9/2/10 FlexPDE 6.13 flux density B_z {fixed range (-0.5e-3, 0.5e-3)} zoom(-0.05, 0, 0.3 max min Scale = E-4 not expected magnitude compared to the simulations of the Lawrence Livermore National Laboratory still open questions Z z / cm AMD-1: Cycle=55 Time= e-3 dt= e-4 P2 Nodes=11513 Cells=5724 RMS Err= 1.6e-5 Vol_Integral= e-8 e-2 Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 23/25

33 Conclusions 1 Quarter Wave Transformer working model good approximation by fit relation between current and parameter included in PPS-SIM 2 Adiabatic Matching Device model included in FlexPDE still open questions about physics Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 24/25

34 Are there any questions? Richard Pausch (TU Dresden) Magnetic fields of the optical matching devices used in the positron source of the ILC 25/25