Intra-Beam Scattering modeling for SuperB and CLIC Mauro Pivi work performed while at SLAC Tau-Charm @ High Luminosity Workshop 27-30 May, 2013
Analytical IBS in SuperB LER (lattice V12) v=5.812 pm @N=6.5e10 h=2.412 nm @N=6.5e10 Effect is reasonably small. Nonetheless, there are some interesting questions to answer: What will be the impact of IBS during the damping process? Could IBS affect the beam distribution, perhaps generating tails? z=4.97 mm @N=6.5e10 Theo Demma 2012
Intra-Beam Scattering (IBS) Simulation Algorithm: CMAD IBS applied at each element of the Ring CMAD parallel code: Collective effects & MAD Lattice read from MADX files containing Twiss functions and transport matrices At each element in the ring, the IBS scattering routine is called. At each element: Particles of the beam are grouped in cells. Particles inside a cell are coupled Momentum of particles is changed because of scattering. Particles are transported to the next element. Radiation damping and excitation effects are evaluated at each turn. Vertical dispersion is included Code: Electron Cloud + IBS + Radiation Damping & Quantum Excitation M. Pivi, T. Demma (SLAC, LAL), A. Chao (SLAC) 27-30 May, 2013
IBS - Zenkevich-Bolshakov Algorithm For two particles colliding with each other, the changes in momentum for particle 1 can be expressed as: with the equivalent polar angle eff and the azimuthal angle distributing uniformly in [0; 2], the invariant changes caused by the equivalent random process are the same as that of the IBS in the time interval ts SIRE code uses similar implementation (A. Vivoli Fermilab, Y. Papaphilippou CERN) 27-30 May, 2013 Tau-Charm @ high L
IBS modeling: animation http://www-user.slac.stanford.edu/gstewart/movies/particlesimulation_animation/
IBS evaluation in SuperB Parameter Unit Value Energy GeV 4.18 Bunch population 1010 6.5 Circumference m 1257 Emittances (H/V) nm/pm 1.8/4.5 Bunch Length mm 3.99 Momentum spread % 0.0667 Damping times (H/V/L) ms 40/40/20 N. of macroparticles - 105 N. of grid cells 64x64x64 Bane Piwinski IBS-Track/CMAD - IBS-Track - C-MAD One turn evolution: compare codes One turn evolution: compare codes and theory M. Pivi, T. Demma 27-30 May, 2013
IBS evaluation for CLIC DR Energy (GeV) 2.86 emitx (m) 5.554e-11 emity (m) 5.8193 e-13 Deltap 1.209209e-3 sigmaz (m) 0.001461 Ideal lattice CMAD simulations compare with theory: one turn evolution of emittance growth in the CLIC Damping Ring.
IBS Distribution study Parameter c2799 Confidence Z 1857.56 <1e-6 X 1455.68 Y 778.228 0.6920 M. Pivi (SLAC), T. Demma (INFN)
Previous work at CERN: SIRE IBS Distribution study Parameter c2999 Confidence Dp/p 3048.7 <1e-15 X 1441.7 Y 1466.9 Parameter Value Eq. ex (m rad) 2.001e-10 Eq. ey (m rad) 2.064e-12 Eq. sd 1.992e-3 Eq. sz (m) 1.687e-3 A. Vivoli , Y. Papaphilippou CERN
‘Equivalent’ Long term Emittance Evolution in SuperB LER These preliminary simulations are performed using a factor F=10 faster damping time and a factor 10 larger beam intensity tx = 10-1 x 40 ms ty = 10-1x 40 ms ts = 10 -1x 20 ms For SuperB V12 LER Nb= 2x1010 - 12x1010
IBS in SuperB Damping Ring Beam injection with IBS without IBS ex (m) ez (m) Injection 1100e-9 1.5e-4 Extraction w/ IBS 25e-9 3.3e-6 Extraction w/o IBS 23e-9 2.97e-6 Evolution of emittance with radiation damping and IBS Just 1 IP per tun is considered here
IBS evaluation next steps Code validation: benchmark recent experiments made at CesrTA and SLS with simulations Tau-Charm factory estimate gives larger IBS growth than SuperB because of larger beam intensity and lower energy Code predictions: long term beam evolution in Tau-Charm and CLIC Damping Rings Included magnet vertical misalignments and vertical dispersion Next: Include magnet rotation and coupling also to closely benchmark experimental data (CesrTA, SLS)
Summary Developed multi-particle simulation codes for Intra-beam scattering Codes in agreement with theoretical models Estimations for Super-B Plans for methodical evaluation of IBS in Tau-Charm are needed.
Thanks to: M. Boscolo, M. E. Biagini, A. Chao