JLEIC Reaching 140 GeV CM Energy: Concept and Luminosity Estimate Yuhong Zhang April 18, 2019

Road to 140 GeV CM Energy Two roads to 400 GeV protons Standard approach Increase maximum proton energy to 400 GeV in the collider ion ring No change of the electron energy/complex Two roads to 400 GeV protons Present footprint: 6 T / 200 GeV  12 T / 400 GeV Large footprint (deep tunnel): about 1.5 times large  8 T / 400 GeV Same design concepts “Many-small-bunch” approach for high luminosity Multi-staged electron cooling (particularly DC cooling) Figure-8 rings for high polarizations Full-acceptance/Forward-tagging oriented IR design Other gradients: crab crossing Rules of Parameters In principle, follows the pre-CDR design range/limits There are other alternate ways, but not considered here This study: shows the performance range based on reasonable estimate, not rigorously defendable

A Few Key Parameters Electron beam parameters: No Change Proton/Ion beam parameters Still up to 0.75 A, and up to 476 MHz rep rate DC cooling always available ERL cooling during collision up to ~150 GeV 0.5/0.5 mm mrad by 8 GeV/4.3 MeV DC cooling (limited by Space Charge, could go down if DC cooling at ~10 GeV/5.5 MeV) Lower emittance at collision (0.5/0.1 mm mrad) at lower energy (<100 GeV) by ERL cooler Lower current ~0.75/2 A for 150 GeV proton beam with ERL cooling Ion Injector complex and beam formation (Jiquan Guo’s presentation) Basically the same, but higher extraction energy of HEB (~25 GeV, rap range ~16) Proposing DC cooling at 10 GeV/5.5 MeV

Large aperture magnets A Few Key Parameters Energy (GeV) βx* (cm) βy* (cm) Up to 100 8 1.3 100 to 200 21 1.6 200 to 400 40 3 Collision/IP parameter Magnet strength vs. proton energy Increase focusing length to preserve detector acceptance Matching under no ERL cooling Emittance grow during beam store if there is no high energy ERL cooling Beam spot size matched at IP for better beam-beam mitigation (the condition may be relaxed if the beam with a larger spot size has much smaller beam-beam tune-shifts compared to limit of the parameter) Aperture in (ion) upper-stream final focusing magnets must be watched 3 cm and 4 cm Large aperture magnets Down stream 

JLEIC Luminosity Calculation of average luminosity takes into accounts Beam formation time: 5 min (with a full size high energy booster) No full-size HEB With high energy cooling, 2 hrs beam store, (120 min / 125 min ~ 96%) (vs. 80%) Without high energy cooling, 1 hrs beam store, (60 min / 65 min ~ 92%) (vs. 67%) Operation duty factor: 75%

JLEIC Luminosity With ERL cooling

Luminosity “Leveling” (Optimization) Proton (300 GeV) Electron (5 GeV) Time Emittance Current βx*/βy* b-b Instant Lumi min mm mrad A cm 1033 /cm2/s 0.5/0.5 0.58 83/16.6 5 0.9/0.5 40/3 0.015/0.0056 1.3 13.4/2.75 0.136/0.137 7.57 20 1.8/0.5 0.008/0.0043 0.015/0.0079 2.4 26.0/2.75 0.143/0.104 5.45 10.07 35 2.4/0.5 0.006/0.0037 0.015/0.0091 3.2 35.5/2.75 0.146/0.091 4.62 11.37 50 2.9/0.5 0.005/0.0034 0.014/0.0094 3.6 43.5/2.75 0.148/0.083 4.15 11.50 65 3.4/0.5 0.004/0.0032 0.012/0.0088 50.5/2.75 0.149/0.077 3.84 10.62 Average luminosity: 3.45 7.28

Bring Average Luminosity at 200 x 12 GeV Above 1033 Not matching beam spot sizes at IP  beam-beam parameters an order of magnitude small Increase proton beam current to 1 A  Large cooled emittance, less space charge Short beam store to 30 min  less DC cooling If not including 75% operation duty factor, average luminosity is already at 1x1033 Optimized Bunch rep rate MHz 475/4 = 119 476/4 = 119 Proton beam current A 0.75 1 Proton emittance at start of counting at end of counting mm mrad 1.5 / 0.5 1.9 / 1 3.5 / 1 Proton beam spot size at IP at start of counting µm 44 / 8.8 73.7 / 8.8 58.7 / 8.8 Electron beam spot size at IP at start of counting 44 / 88 Mismatching Up to 1.33 Proton beam-beam at IP at start of counting 0.003 / 0.0017 0.0008 / 0.0011 0.002 / 0.008 0.002 / 0.0007 Electron beam-beam at IP at start of counting 0.013 / 0.013 0.014 / 0.0083 0.017 / 0.025 0.01 / 0.017 Store time min 60 30 Average luminosity (including 75% DF) , 1033 1/cm2/s 0.74 1.00

Large Footprint (1.5x) with Deep Tunnel Energy Current footprint Large footprint (1.5x) Emittance Current (GeV) (mm mrad) A 3 17.9 >3.6 5.3 4 42.5 12.6 5 83 24.6 6 143 7 228 3.33 67.5 8 340 1.95 101 9 484 1.22 2.74 10 664 0.8 197 1.8 11 884 0.55 262 1.23 12 1147 0.39 0.87 Assuming same linear SR power (10 kW/m), thus total SR power at ~15 MW

JLEIC Luminosity (Large Footprint) Calculation of average luminosity takes into accounts Beam formation time: 5 min (with a full size high energy booster) No full-size HEB With high energy cooling, 2 hrs beam store, (120 min / 125 min ~ 96%) (vs. 80%) Without high energy cooling, 1 hrs beam store, (60 min / 65 min ~ 92%) (vs. 67%) Operation duty factor: 75%

JLEIC Luminosity

JLEIC Parameters and Luminosity Performance 04/18/2019 CM energy GeV 21.9 44.7 63.3 89.4 98   p e E Beam energy 40 3 100 5 200 10 12 Collision freq MHz 476 476/4=119 Particles/bunch 1010 0.59 3.9 0.98 4.7 8.9 3.93 4.2 2.05 Beam current A 0.45 0.75 3.6 0.57 1.7 0.8 0.39 Polarization % 85 >85 >80 ~80 Bunch length cm 2.5 1 3.2 Norm. emitt, x µm 0.5 18 0.65 83 1.26 1.5 664 1145 Norm. emitt, y 0.2 0.13 16.6 133 229 Horizontal β* 8 30 5.72 21 14.5 19.2 4 27.5 Vertical β* 1.3 9.8 0.93 1.6 2.2 2.3 3.3 Beam-beam, x 0.015 0.12 0.045 0.136 0.006 0.022 0.003 0.013 0.01 0.15 0.0135 0.041 0.0065 0.120 0.002 Laslett tune-shift 0.055 small 0.018 0.0039 Small 0.0051 0.0052 Hour-glass (HG) 0.85 0.73 0.84 0.66 0.67 Peak lumi., w/HG 1033/cm2s 14.6 9.84 3.8 1.31 Average lumi.* 10.5 8.2 1.9 0.74 * Average luminosity was calculated assuming a one or two hour proton beam store without or with high energy bunched beam electron cooling respectively plus 5 min beam formation time (mainly due to detector overhead), and a 75% duty factor of machine operation.

JLEIC Parameters and Luminosity Performance 03/29/2019 CM energy GeV 21.9 44.7 63.3 89.4 98   p e E Beam energy 40 3 100 5 200 10 12 Collision freq MHz 476 476/2=238 476/4=119 Particles/bunch 1010 0.59 3.9 0.98 4.7 1.97 6.8 3.93 4.2 2.05 Beam current A 0.45 0.75 3.5 2.58 0.8 0.39 Polarization 85% >85% >80% ~80% Bunch length cm 2.5 1 2.1 4 Norm. emitt, hori. μm 0.5 18 0.65 83 0.96 3.1 664 1145 Norm. emitt, vert. 0.2 3.6 0.13 16.6 0.25 1.5 133 229 Horizontal β* 8 30 5.72 21 11.2 9.1 6.6 Vertical β* 1.3 9.8 0.93 1.6 1.1 1.65 1.15 Beam-beam, hori. 0.015 0.12 0.045 0.09 0.003 0.02 0.0013 0.014 Beam-beam, vert. 0.01 0.15 0.013 0.041 0.008 0.065 0.001 0.0005 0.012 Laslett tune-shift 0.055 small 0.018 Small 0.0014 Hour-glass (HG) 0.85 0.73 0.82 0.67 Peak lumi., w/HG 1033/cm2s 3.2 14.7 15.5 1.9 0.86 Average lumi.* 2.3 10.6 9.3 0.71 * Average luminosity was calculated assuming a one or two hour proton beam store without or with high energy bunched beam electron cooling respectively plus 5 min beam formation time (mainly due to detector overhead), and a 75% duty factor of machine operation.