Dafne Upgrade with large Piwinsky angle and crab waist P. Raimondi Gruppo1 Nov.2006.
Status of EuCARD WP11.2.2 LHC Crab Waist
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Transcript of Status of EuCARD WP11.2.2 LHC Crab Waist
Status of EuCARD WP11.2.2LHC Crab Waist
Frank Zimmermann
Input to EuCARD2011 Meeting, CNRS, Paris, 13 May 2011
crab waist for the LHC• initial delay due to difficulty / impossibility of
recruiting a fellow at CERN• two mitigations:
– contributions by external experts • Dmitry Shatilov (BINP) visiting Mikhail Zobov at INFN-LNF
twice , in fall 2010 and winter 2011 • Kazuhito Ohmi (KEK) visiting Frank Zimmermann at CERN
twice, in summer 2010 and winter 2011
– recruitment of doctoral student instead of fellow• Jose Abelleira started at CERN in November 2010
crab waist for the LHC weak-strong beam-beam studies by Shatilov & Zobovusing Lifetrac code (Shatilov, Part.Accel.52:65-93,1996)• crab-waist (CW) application to “quasi-round” beams:
in terms of luminosity lifetime, resonance suppression and halo control, CW for HL-LHC efficient only when operating with rather flat beams of x/y≥ 10 [PRST-AB 14, 014001 (2011)]• luminosity gain from a longitudinally uniform or “trapezium” (as compared to Gaussian) profile for equal bunch charge and beam-beam tune shift, in the regime w>1: For w=2: 10% gain from the flatter beam profile. For w=5: 25% gain. For w>>1 asymptotic gain of 41%.
assumed “LHC” parameters:x,y =0.5 nm , E = 7 TeVx = 30 cm, y = 7.5 cm, x/y=2,z = 11.8 cm, c= 315 rad ( =1.5), Nb = 4.0x1011,Qs =0.002, Qx,y ~ -0.0065,single IP
frequency-map analysis of Lifetrac simulation
M. Zobov, D. Shatilov, et al, PRST-AB 14, 014001 (2011)
collisions withcrossing angle
crab crossing
resonances
resonancefree!
crab waist
resonances
crab waist for the LHC
Table "flat / Gauss" profiles, geometrical factors.Slashes in the table separate "flat / trapezium“profiles of the strong bunch; the weak bunch is trapezium in all cases. Angles are measured in units of 3.48E-4 rad (nominal value).====================================================================Angle | ksi_x | ksi_y | Lumi | Lumi/ksi_y |-------|---------------|---------------|-------------|-------------| 0 | 0.997 / 0.997 | 0.997 / 0.997 | 1.01 / 1.01 | 1.01 / 1.01 | 1 | 1.184 / 1.153 | 1.070 / 1.059 | 1.13 / 1.12 | 1.06 / 1.06 | 2 | 1.077 / 1.077 | 1.101 / 1.086 | 1.21 / 1.19 | 1.10 / 1.10 | 3 | 0.905 / 0.936 | 1.087 / 1.076 | 1.25 / 1.22 | 1.15 / 1.13 | 4 | 0.821 / 0.854 | 1.068 / 1.063 | 1.26 / 1.23 | 1.18 / 1.16 | 5 | 0.775 / 0.807 | 1.059 / 1.052 | 1.27 / 1.24 | 1.20 / 1.18 | 6 | 0.748 / 0.777 | 1.050 / 1.045 | 1.28 / 1.24 | 1.22 / 1.19 | 7 | 0.726 / 0.756 | 1.043 / 1.039 | 1.28 / 1.25 | 1.23 / 1.20 | 8 | 0.714 / 0.743 | 1.038 / 1.034 | 1.29 / 1.25 | 1.24 / 1.21 | 9 | 0.704 / 0.731 | 1.034 / 1.030 | 1.29 / 1.25 | 1.25 / 1.21 | 10 | 0.696 / 0.725 | 1.030 / 1.027 | 1.29 / 1.25 | 1.25 / 1.22 | 15 | 0.674 / 0.695 | 1.020 / 1.017 | 1.29 / 1.25 | 1.26 / 1.23 | 20 | 0.667 / 0.685 | 1.014 / 1.012 | 1.29 / 1.25 | 1.27 / 1.24 | 25 | 0.657 / 0.686 | 1.011 / 1.009 | 1.29 / 1.25 | 1.28 / 1.24 | 30 | 0.640 / 0.680 | 1.009 / 1.008 | 1.29 / 1.25 | 1.28 / 1.24 |==================================================================== 0 | 0.996 / 0.997 | 0.998 / 0.998 | 1.01 / 1.01 | 1.01 / 1.01 | 1 | 1.115 / 1.096 | 1.121 / 1.101 | 1.13 / 1.12 | 1.01 / 1.02 | 2 | 1.093 / 1.082 | 1.095 / 1.084 | 1.21 / 1.19 | 1.10 / 1.10 | 3 | 1.046 / 1.044 | 1.045 / 1.043 | 1.25 / 1.22 | 1.19 / 1.17 | 4 | 1.025 / 1.025 | 1.024 / 1.023 | 1.26 / 1.23 | 1.23 / 1.20 | 5 | 1.015 / 1.015 | 1.014 / 1.014 | 1.27 / 1.24 | 1.25 / 1.22 | 10 | 1.002 / 1.002 | 1.002 / 1.001 | 1.29 / 1.25 | 1.29 / 1.25 | 15 | 1.000 / 0.999 | 0.999 / 0.999 | 1.29 / 1.25 | 1.29 / 1.25 | 20 | 0.999 / 0.998 | 0.999 / 0.998 | 1.29 / 1.25 | 1.29 / 1.25 | 25 | 0.998 / 0.998 | 0.998 / 0.998 | 1.29 / 1.25 | 1.29 / 1.25 | 30 | 0.998 / 0.998 | 0.998 / 0.998 | 1.29 / 1.25 | 1.29 / 1.25 |====================================================================
1 IP
2 IPsx/ycrossing
LHC CW: longitudinal profile for w>1
trapezium shape of weak bunch
D.Shatilov, M. Zobov
1.29 instead of 1.41 due to trapezium shape
crab waist for the LHC beam-beam & optics studies by K. Ohmi
using BBSS code• strong-strong beam-beam simulations: - “various collision schemes (CC, CW) for HL-LHC have feasibility from the view of beam-beam; a beam-beam parameter ξ=0.03/IP is challengeable”• effect of kinematic term, quadrupole fringe fields,
and nonlinear multipole errors on LHC dynamic aperture with crab waist: -LHC crab waist scheme requires local chromaticity correction and local nonlinearity corrections- effects of kinematic term & quadrupole fringe are weak
K. Ohmi
K. Ohmi
K. Ohmi
K. Ohmi
WP11 doctoral student Jose Abelleira (EPFL Lausanne) - started at CERN on 1 November 2010. - thesis topic: study of a high-luminosity LHC upgrade based on large Piwinski angle, flat beams, and crab waists- achievements:
• getting familiar with accelerator physics and with design concepts of final-focusing systems (LHC, LC, muon collider)• learning some important tools : MAD-X, PTC and MAPCLASS.• JUAS in January 2011• practicing with local chromatic correction of LHeC L-R e- final focus: momentum bandwidth without and with chromatic correction, and higher-order optimization of the sextupole positions and strengths with PTC and MAPCLASS-plan: • apply similar design concept to the much more complicated LHC high-luminosity upgrade, especially, as a next step, organize its chromaticity correction in view of a possible LHC crab waist scheme
crab waist for the LHC
-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1
x 10-3
0
0.5
1
1.5
2
2.5
dp
beta
* (u
m)
bandwidth
momentum bandwidth without & with sextupoles
optics with location of 4 sextupoles
x (w/o sext)
x (w sext)y (w/o sext)
y (w sext)
order 1 2 3 4 5
x [m] (=0) 9.2 28.3 175.0 179.5 181.4
y [m] (=0) 4.6 8.5 85.4 87.5 88.2
x [m] (=3x10-4) 11.1 28.9 175.1 179.5 181.5
y [m] (=3x10-4) 4.6 8.5 85.4 87.5 88.2
effect of higher-order aberrations with MAPCLASS – further optimization needed
crab waist for LHC: L-R LHeC e- beam final-focus modelJ. Abelleira, R. Tomas, E. Marin