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Lepton Collider (FCC-ee) Baseline V1.0 Parameters (30 June 2020)

This page contains the CDR FCC-ee baseline parameters.

The FCC-ee lepton collider will be design to provide e+e- collisions with centre-of-mass energies from 88 to 365 GeV. The centre-of-mass operating points with the most physics interest are around 91 GeV (Z pole), 160 GeV (W<sup+W- pair-production threshold), 240 GeV (ZH production) and 340 - 365 GeV (ttbar threshold and above). The machine should accomodate at least two experiments operated simultaneously and deliver peak luminosities above $ 1 \times 10^{34} cm^{-2}s^{-1}$ per experiment at the ttbar threshold and the highest ever luminosities at lower energies.

The layout of the FCC-ee collider will be compatible with an energy frontier (order of 100 TeV) hadron collider (FCC-hh) that should be installed and operated after the end of the FCC-ee physics research programme.

The parameter table shows the machine parameters for different beam energies.

Parameter Unit Z WW ZH ttbar 1st year ttbar
Circumference km 97.756
Bending radius km 10.76
Free length to IP $l*$ m 2.2
Solenoid field at IP T 2.0
Full crossing angle at IP $\Theta$ mrad 30
Synchrotron radiation power / beam MW 50
Beam energy GeV 45.6 80 120 175 182.5
Beam current mA 1 390 147 29 6.4 5.4
Bunches / beam # 16 640 2 000 328 59 48
Average bunch spacing ns 19.6 163 994 2 763a) 3 396a)
Bunch population $10^{11}$ 1.7 1.5 1.8 2.2 2.3
Horizontal emittance $\epsilon_x$ nm 0.27 0.84 0.63 1.34 1.46
Vertical emittance $\epsilon_y$ pm 1.0 1.7 1.3 2.7 2.9
Arc cell phase advances deg 60/60 60/60 90/90 90/90 90/90
Momentum compaction $\alpha_p$ $10^{-6}$ 14.8 14.8 7.3 7.3 7.3
Arc sextupole families # 208 292
Horizontal $\beta^*_x$ m 0.15 0.2 0.3 1.0
Vertical $\beta^*_y$ mm 0.8 1.0 1.0 1.6
Horizontal size at IP $\sigma^*_x$ $\mu$m 6.4 13.0 13.7 36.7 38.2
Vertical size at IP $\sigma^*_y$ nm 28 41 36 66 68
Energy spread (SR/BS) $\sigma_\delta$ % 0.038/0.132 0.066/0.131 0.099/0.165 0.144/0.186 0.150/0.192
Bunch length (SR/BS) $\sigma_z$ mm 3.5/12.1 3.0/6.0 3.15/5.3 2.01/2.62 1.97/2.54
Piwinski angle (SR/BS) $\Phi$   8.2/28.5 3.5/7.0 3.4/5.8 0.8/1.1 0.8/1.0
Length of interaction area $L_i$ mm 0.42 0.85 0.90 1.8 1.8
Hourglass factor $R_{HG}$   0.95 0.89 0.88 0.84 0.84
Crab sextupole strengthb % 97 87 80 40 40
Energy loss / turn GeV 0.036 0.34 1.72 7.8 9.2
RF frequency MHz 400 400/800
RF voltage GV 0.1 0.75 2.0 4.0/5.4 4.0/6.9
Synchrotron tune $Q_s$   0.0250 0.0506 0.0358 0.0818 0.0872
Longitudinal damping time turns 1 273 236 70.3 23.1 20.4
RF bucket height % 1.9 3.5 2.3 3.36 3.36
Energy acceptance (DA) % $\pm$ 1.3 $\pm$1.3 $\pm$ 1.7 -2.8 / +2.4 -2.8 / +2.4
Polarisation time without wigglers $t_p$ min 15 000 900 120 18.0 14.6
Luminosity / IP $10^{34} / cm^2s $ 230 28 8.5 1.8 1.55
Horizontal tune $Q_x$   269.139 269.124 389.129 389.108
Vertical tune $Q_y$   269.219 269.199 389.199 389.175
Allowable e+e-% charge asymmetry % $\pm$5 $\pm$3
Lifetime by radiative Bhaba scattering min 68 59 38 40 39
Lifetime due to beamstrahlung min > 200 > 200 18 24 18
a) A half ring is filled with the common RF scheme. b) Relative to the geometrical strength $k_2 = (\Theta_x \beta^*_x \beta_{y,sext})^{-1} \sqrt{\beta^*_x / \beta_{x,sext}}$.

-- JohannesGutleber - 2020-07-01 -- JohannesGutleber - 2021-01-06

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Topic revision: r1 - 2021-01-06 - JohannesGutleber
 
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