MEIC New Baseline: Luminosity Performance and Upgrade Path

New MEIC Baseline New major components: Energy range: Design points: Electron collider ring: PEP-II magnet Ion collider ring: super-ferric magnet Ring circumference: ~2200 km Single booster ring: 285 MeV to 8 GeV Electron ring RF: PEP-II, 476 MHz (to be decided) Energy range: Electron: 3 to 12 GeV Proton: (8) 20 to 100 GeV Lead ions: ? to 40 GeV Design points: Low energy: 30 GeV x 4 GeV (space charge dominated) Medium energy: 85 GeV x 6 GeV (beam-beam dominated) High energy: 100 GeV x 8 GeV (synchrotron radiation dominated) (another set? (20x3), 50x5, 100x5, 100x10, proton 50x5 deuterium, 67x10 He3, 40x5 Pb, 40x10 Pb )

Low Energy (Ecm~21.9 GeV) Point Parameters Detector type Full acceptance Large Acceptance Proton Electron Beam energy GeV 30 4 Collision frequency MHz 750 Particles per bunch 1010 0.37 2.5 Beam Current A 0.44 3 Polarization % > 70 ~ 80 RMS bunch length cm 1.2 emittance, normalized µm rad 0.35 / 0.12 74 / 24.7 Horizontal and vertical β* 6 / 2 6.9 / 2.3 4 / 0.8 2.8 / 0.93 Spot size at IP, horiz. and vert. µm 25.6 / 8.5 16.2 / 5.4 Vertical beam-beam tune shift 0.013 0.017 Laslett tune shift 0.06 Very small Distance from IP to 1st FF quad m 7 3.5 4.5 Hour-glass effect 0.77 0.51 Luminosity per IP, 1033 cm-2s-1 1.9 3.1 Slide 3 3

Medium Energy (Ecm~45.2 GeV) Point Parameters Detector type Full acceptance Large Acceptance Proton Electron Beam energy GeV 85 6 Collision frequency MHz 750 Particles per bunch 1010 0.42 2.5 Beam Current A 0.5 3 Polarization % > 70 ~ 80 RMS bunch length cm 2 1.2 emittance, normalized µm rad 0.3 / 0.06 130 / 26 0.35 / 0.06 Horizontal and vertical β* 10 / 2 7.5 / 1.5 6 / 1.2 4 / 0.8 Spot size at IP, horiz. and vert. µm 18.2 / 3.6 28.8 / 5.8 14.2 / 2.8 21 / 4.2 Vertical beam-beam tune shift 0.007 0.03 0.008 0.027 Laslett tune shift 0.028 Very small Distance from IP to 1st FF quad m 7 3.5 4.5 Hour-glass effect 0.85 0.71 Luminosity per IP, 1033 cm-2s-1 4.6 6.9 Slide 4 4

High Energy (Ecm~56.6 GeV) Point Parameters Detector type Full acceptance Large Acceptance Proton Electron Beam energy GeV 100 8 Collision frequency MHz 750 Particles per bunch 1010 0.42 1.46 Beam Current A 0.5 1.75 Polarization % > 70 ~ 80 RMS bunch length cm 2 1.2 emittance, normalized µm rad 0.45 / 0.09 290 / 58 Horizontal and vertical β* 10 / 2 7.5 / 1.5 6 / 1.2 4 / 0.8 Spot size at IP, horiz. and vert. µm 20.6 / 4.1 37.3 / 7.5 15.9 / 3.2 27.2 / 5.4 Vertical beam-beam tune shift 0.002 0.018 Laslett tune shift 0.02 Very small Distance from IP to 1st FF quad m 7 3.5 4.5 Hour-glass effect 0.85 0.7 Luminosity per IP, 1033 cm-2s-1 1.7 2.6 Slide 5 5

Reusing PEPP-II RF: 748 MHz  476 MHZ Number of bunches in the ring is reduced by 36% Same current, bunch intensity is increased by 36% Same current, beam-beam parameter is increased by 36% To the first order, In a beam-beam limited parameter regime, the luminosity is decreased by 36% In a non-beam-beam-limited parameter regime, the luminosity is increased by 36%

Low Energy (Ecm~21.9 GeV) Point Parameters @ 476 MHz Detector type Full acceptance Large Acceptance Proton Electron Beam energy GeV 30 4 Collision frequency MHz 476 Particles per bunch 1010 0.37 2.8 2.9 Beam Current A 0.28 2.1 2.2 Polarization % > 70 ~ 80 RMS bunch length cm 1.2 emittance, normalized µm rad 0.35 / 0.12 74 / 24.7 Horizontal and vertical β* 6 / 2 6.9 / 2.3 4 / 0.8 2.8 / 0.93 Spot size at IP, horiz. and vert. µm 25.6 / 8.5 16.2 / 5.4 Vertical beam-beam tune shift 0.015 0.017 Laslett tune shift 0.06 Very small Distance from IP to 1st FF quad m 7 3.5 4.5 Hour-glass effect 0.77 0.51 Luminosity per IP, 1033 cm-2s-1 1.35 2.3 Slide 7 7

Medium Energy (Ecm~45.2 GeV) Point Parameters @ 476 MHz Detector type Full acceptance Large Acceptance Proton Electron Beam energy GeV 85 6 Collision frequency MHz 476 Particles per bunch 1010 0.66 3.9 Beam Current A 0.5 3 Polarization % > 70 ~ 80 RMS bunch length cm 2 1.2 emittance, normalized µm rad 0.3 / 0.06 130 / 26 0.35 / 0.12 74 / 24.7 Horizontal and vertical β* 10 / 2 7.5 / 1.5 6 / 1.2 4 / 0.8 Spot size at IP, horiz. and vert. µm 18.2 / 3.6 28.8 / 5.8 14.2 / 2.8 21 / 4.2 Vertical beam-beam tune shift 0.011 0.047 0.042 Laslett tune shift 0.028 Very small Distance from IP to 1st FF quad m 7 3.5 4.5 Hour-glass effect 0.85 0.71 Luminosity per IP, 1033 cm-2s-1 7.1 10.8 Slide 8 8

High Energy (Ecm~56.6 GeV) Point Parameters @ 476 MHz Detector type Full acceptance Large Acceptance Proton Electron Beam energy GeV 100 8 Collision frequency MHz 476 Particles per bunch 1010 0.66 2.3 Beam Current A 0.5 1.75 1.46 Polarization % 70 ~ 80 > 70 RMS bunch length cm 2 1.2 emittance, normalized µm rad 0.45 / 0.09 290 / 58 Horizontal and vertical β* 10 / 2 7.5 / 1.5 6 / 1.2 4 / 0.8 Spot size at IP, horiz. and vert. µm 20.6 / 4.1 37.3 / 7.5 15.9 / 3.2 27.2 / 5.4 Vertical beam-beam tune shift 0.003 0.028 0.004 0.025 Laslett tune shift 0.02 Very small Distance from IP to 1st FF quad m 7 3.5 4.5 Hour-glass effect 0.85 0.7 Luminosity per IP, 1033 cm-2s-1 2.7 4.0 Slide 9 9

Consideration of MEIC Upgrade Path Present approach First stage baseline (MEIC) up to 100 GeV x 12 GeV (10 years) Energy upgrade (EIC) up to 250 GeV x 20 GeV Alternative approach First stage baseline (MEIC) up to 100 GeV x 10 GeV (5 years) Luminosity upgrade (HL-MEIC) same, luminosity x 3~4 (5 years) Energy upgrade (HE-MEIC=EIC) up to 250 GeV x 14(?) GeV What is the first stage baseline? Very conservative, all based on “ready-to-build” technologies Acceptable starting performance Significant relaxation of the machine design Minimum technical uncertainty and R&D requirement (weak cooling) Minimum cost (PEP-II RF station (476 MHz)

Consideration of MEIC Upgrade Path What constitutes a luminosity upgrade? (A factor of 4) Doubled the bunch repetition rate (476 MHz  952 MHz) Increase of the beam current Reduction of beam emittance (better cooling? Better electron lattice?) Redesign of IR (beta-star reduction by a factor 2?), including DA Unmatched beam size? More aggressive hour-glass effect? A little large beam-beam? Space charge compensation? Electron lens? Small cost (a fraction of energy upgrade cost)

Low Energy (Ecm~21.9GeV) Parameters Detector type: full acceptance Phase 1 Luminosity upgrade Proton Electron Beam energy GeV 30 4 Collision frequency MHz 476 952 Particles per bunch 1010 0.26 3.9 0.43 2.9 Beam Current A 0.2 3 0.65 4.5 Polarization % > 70 ~ 80 70 RMS bunch length cm 2 1.2 emittance, normalized µm rad 0.6 / 0.2 74 / 24.7 0.35 / 0.12 Horizontal and vertical β* 6 / 2 12 / 4 4.2 / 1.4 4.8 / 1.6 Spot size at IP, horiz. and vert. µm 33.6 / 11.2 21.4 / 7.2 Vertical beam-beam tune shift 0.012 0.015 0.019 Laslett tune shift 0.05 Very small 0.062 Distance from IP to 1st FF quad m 7 3.5 Hour-glass effect 0.91 0.67 Luminosity per IP, 1033 cm-2s-1 0.95 3.7 Slide 12 12

Medium Energy (Ecm~45.2 GeV) Parameter Detector type: full acceptance First Stage Luminosity Upgrade Proton Electron Beam energy GeV 85 6 Collision frequency MHz 476 952 Particles per bunch 1010 0.66 2.9 0.79 2.6 Beam Current A 0.5 2.2 1.2 4 Polarization % > 70 ~ 80 RMS bunch length cm 2 emittance, normalized µm rad 0.5 / 0.1 160 / 32 0.4 / 0.08 130 / 26 Horizontal and vertical β* 18.5 / 3.7 7.5 / 1.5 6 / 1.2 9 / 1.8 Spot size at IP, horiz. and vert. µm 32 / 6.6 20 / 4 25.8 / 5.15 Vertical beam-beam tune shift 0.012 0.015 0.008 0.038 Laslett tune shift 0.026 Very small 0.04 Distance from IP to 1st FF quad m 7 3.5 Hour-glass effect 0.87 0.82 Luminosity per IP, 1033 cm-2s-1 3.1 12.1 ~3.9 Slide 13 13

High Energy (Ecm~56.6 GeV) Parameter Detector type: full acceptance First Stage Luminosity Upgrade Proton Electron Beam energy GeV 100 8 Collision frequency MHz 476 Particles per bunch 1010 0.66 2.3 0.92 Beam Current A 0.5 1.75 0.7 Polarization % > 70 ~ 80 RMS bunch length cm 2 1.2 emittance, normalized µm rad 0.6 / 0.12 290 / 58 0.3 / 0.06 180 / 36 Horizontal and vertical β* 25 / 5 7.5 / 1.5 6 / 1.2 Spot size at IP, horiz. and vert. µm 37.5 / 7.5 14.5 / 1.5 26.3 / 5.0 Vertical beam-beam tune shift 0.008 0.005 0.062 Laslett tune shift 0.016 Very small 0.04 Distance from IP to 1st FF quad m 7 3.5 Hour-glass effect 0.89 0.81 Luminosity per IP, 1033 cm-2s-1 1.8 7.2 ~4 Slide 14 14