Pre-Linac simulations in G4beamline Alex Bogacz & Yves Roblin Kevin B. Beard Muons,Inc. & Alex Bogacz & Yves Roblin Jefferson Lab LEMC2009 workshop 8-12 Jun 2009

pre-accelerator linac - not very relativistic Morteza Aslaninejad, Cristian Bontoiu Jürgen Pozimski, Ajit Kurup Imperial College, London, UK 0.6 GeV/pass 3.6 GeV 0.9 GeV 244 MeV 146 m 79 m 2 GeV/pass 264 m 12.6 GeV Mm = 105.658 MeV Etotal: 244 MeV → 900 MeV P: 220 MeV/c → 894 MeV/c KE: 138 MeV → 794 MeV

Longitudinal phase-space tracking IDS erms A = (2.5)2 e normalized emittance: ex/ey mmrad 4.8 30 longitudinal emittance: el (el = sDp sz/mmc) momentum spread: sDp/p bunch length: sz mm 27 0.07 176 150 0.17 442 ELEGANT (Fieldmap) OptiM (Matrix)

Solenoid Linac (244 -909 MeV) 6 short cryos 15 MV/m 8 medium cryos 17 MV/m 11 long cryos 1.1 Tesla solenoid 1.4 Tesla solenoid 2.4 Tesla solenoid Transverse acceptance (normalized): (2.5)2eN = 30 mm rad Longitudinal acceptance: (2.5)2 sDpsz/mmc = 150 mm 146 Sat Dec 13 22:36:02 2008 OptiM - MAIN: - D:\IDS\PreLinac\Sol\Linac_sol.opt 12 5 BETA_X&Y[m] DISP_X&Y[m] BETA_X BETA_Y DISP_X DISP_Y

Why another simulation? OptiM – fast, interactive, design, matrix based 0th order design tool, symplectic soft edge solenoids, very good at tuning (free) GPT – good at tracking ($) G4beamline – tracking, Geant4 particle decays & interactions, energy depositions, showers, etc., not so good at tuning (free & open source) http://g4beamline.muonsinc.com

Solenoid Model (Superfish) outer coil shield inner coil ‘Soft-edge’ Solenoid

Two-cell cavity (201 MHz) – COMSOL Morteza Aslaninejad Cristian Bontoiu Jürgen Pozimski

Field maps solenoid Bz single RF cell Ez double RF cell Ez

g4beamline 2.08 counterwound solenoid RF cell valve assembly flux return shield conductors stainless pipe RF cell Virtual detectors LEMC2009 workshop 8-12 Jun 2009

upper middle lower LEMC2009 workshop 8-12 Jun 2009

Simple Phasing via spreadsheet 0o≡on crest L=2λ c=λf z=cβt Ez(z,t) ≈ qEzo cos(2πf t + φ) cos(π z/L) +L/2 ΔE ≈ ∫ Ez(z,z/cβ) dz -L/2 ΔE ≈ -2qEzo L cos(π/ 2β) cos(φ) β2/(π (1-β2) ΔE ≈ -2qEzo L cos(π/ 2β) cos(φ) β2/(π (1-β2) Ti ≈ Ti-1+ (zi - zi-1)/(cβi-1) LEMC2009 workshop 8-12 Jun 2009 Muons, Inc. ΔE ≈ ∫ Ez(z,z/cβ) dz Ez(z,t) ≈ qEzo cos(2πf t + φ) cos(π z/L) Ti ≈ Ti-1+ (zi - zi-1)/(cβi-1)

Linac parameters Muons, Inc.

phases partially adjusted Longitudinal phases partially adjusted phases from spreadsheet LEMC2009 workshop 8-12 Jun 2009 Muons, Inc.

Comparison of GPT, OptiM, g4beamline KE[MeV] z[cm] G4beamline w/adj. φ's OptiM G4beamline w/OptiM's φ's KE[MeV] LEMC2009 workshop 8-12 Jun 2009 z[cm] Muons, Inc.

Ez Ez LEMC2009 workshop 8-12 Jun 2009 Muons, Inc.

LEMC2009 workshop 8-12 Jun 2009 Sep 14, 2010 Muons, Inc.

Fine tuning is still in progress Synchrotron motion ~ oncrest Pz ~ 1 synch period LEMC2009 workshop 8-12 Jun 2009 t t Muons, Inc. G4beamline model is working well and in general agreement with other simulations Essential step toward our long term goal of complete end-to-end simulations Fine tuning is still in progress Will soon begin particle interactions with the hardware

Transverse motion GPT G4beamline y[m] LEMC2009 workshop 8-12 Jun 2009 z[m] z[m] Muons, Inc.

G4beamline improvements from this work: fieldmap timeOffset fixed (simple bug fix) pillbox autoTune being added (tune for max,min ΔE or Δt rather than assume Δv=0) LEMC2009 workshop 8-12 Jun 2009 Muons, Inc.

Linac – near term plans optical rematch of linac to cooling channel greatly improve RF phasing capability of G4beamline optical rematch of linac to cooling channel optimize longitudinal and transverse acceptance determine energy deposition in components prepare the transfer line to RLA I

LEMC2009 workshop 8-12 Jun 2009 Sep 14, 2010 Muons, Inc.