Update on JLEIC Electron Collider Ring Design Fanglei

Update on JLEIC Electron Collider Ring Design Fanglei Lin JLEIC R&D Meeting, July 19, 2018

General Information What has not been changed － Arc and straight FODO cells, arc bending radius is still 155. 5 m What is new － Dogleg is implemented in the electron spin rotator • Pro: a lot of space ~200 m is saved in the ion collider ring • Con: If we bring the full-size booster back to the loop and still put it on the top of collider rings, then the transfer of ion beam between booster and collider ring will need cross the electron beam line (Tim has another better idea !) － Local chromaticity compensation blocks are removed • Pro: natural chromaticities and length of electron ring are reduced significantly • Con: not good control of beam smear at the IP － Maximum strength of quadrupole magnets are controlled under 21 T/m at 12 Ge. V － Maximum strength of sextupole magnets are 578 T/m 2 at 12 Ge. V － Figure-8 crossing angle 77. 4 (was 81. 7 ) － Circumference 2256. 6 m, arc 893. 0 m, straight 235. 3 m. JLEIC R&D Meeting, July 19, 2018 2

Layout (06/26/2018 Lattice) Top view tor ta ro pin S R=155. 5 m Arc 77. 4 r tato o nr Spi ~55 m IP Side view 1. 5 m, assumed historically JLEIC R&D Meeting, July 19, 2018 3

Geometry 175 feet JLEIC R&D Meeting, July 19, 2018 Courtesy of Dave Fazenbaker 4

Complete Optics JLEIC R&D Meeting, July 19, 2018 5

Spin Rotator (w/ Dogleg) Sol. 1 + dec. skew quads + matching quads Vertical dogleg 1 JLEIC R&D Meeting, July 19, 2018 Horizontal DBA 1 Sol. 2 + dec. skew quads + matching quads Horizontal DBA 2 6

Ring Parameters Ge. V/c 5 m 2256. 57 Straights’ crossing angle deg 77. 4 Beta stars at IP *x, y cm 10/2 Maximum horizontal / vertical functions x, y m 487 / 438 Maximum horizontal / vertical dispersion Dx, y m 0. 44 / 0. 61 Electron beam momentum Circumference Horizontal / vertical betatron tunes x, y 56(. 97) / 50(. 15) Horizontal / vertical chromaticities x, y -123 / -129 Momentum compaction factor 9. 7 10 -4 Transition energy tr JLEIC R&D Meeting, July 19, 2018 32. 06 7

Radiation integrals JLEIC R&D Meeting, July 19, 2018 8

Calculations of Radiation Integrals ELEGANT MAD-X Radiation integrals New ring w/ doglegs New ring w/o doglegs (flat ring) My calculation New ring w/ doglegs New ring w/o doglegs (flat ring) 2. 433238954 2. 338955 2. 2985199422 2. 42430733784 0. 1088678918 0. 1004062968 0. 1004063 0. 108867891827 0. 100406296833 0. 001282574552 0. 001180017127 0. 001180017 0. 00128257455184 0. 00118001712642 0 0 -1. 134862 e-05 1. 734674875 e-5 1. 391437783 e-5 1. 293093 e-05 1. 11545639884 e-05 1. 11503694624 e-05 4. 6374720204 e-06 0 JLEIC R&D Meeting, July 19, 2018 9

Beam Parameters Beam energy Ge. V 3 5 6. 8 9 10 12 Beam current A 3 3 3 0. 98 0. 64 0. 31 Total SR power MW 0. 37 2. 88 9. 84 9. 87 9. 82 9. 87 Energy loss per turn Me. V 0. 12 0. 96 3. 3 10. 1 15. 3 31. 8 Energy spread 10 -4 2. 8 4. 6 6. 3 8. 4 9. 3 11. 2 Transverse damping time ms 363 78 31 13 10 6 Longitudinal damping time ms 181 39 16 7 5 3 Normalized Horizontal Emittance um 9. 2 43 107 249 341 589 Normalized Vertical Emittance um 3. 8 18 45 103 142 245 JLEIC R&D Meeting, July 19, 2018 10

Reduce the vertical bending angle in the spin rotator by a factor of 1. 3 Complete the ring optics Additional changes: － One quad need increase length from 0. 73 to 1 cm to control the maximum strength < 21 T/m at 12 Ge. V JLEIC R&D Meeting, July 19, 2018 11

Layout w/ Small Vertical Bending Top view tor ta ro pin S R=155. 5 m Arc 77. 4 r tato o nr Spi ~55 m IP Side view 1. 2 m < 1. 5 m JLEIC R&D Meeting, July 19, 2018 12

Complete Optics JLEIC R&D Meeting, July 19, 2018 13

Spin Rotator (w/ Dogleg) Sol. 1 + dec. skew quads + matching quads Vertical dogleg 1 JLEIC R&D Meeting, July 19, 2018 Horizontal DBA 1 Sol. 2 + dec. skew quads + matching quads Horizontal DBA 2 14

Ring Parameters Ge. V/c 5 m 2256. 61 Straights’ crossing angle deg 77. 4 Beta stars at IP *x, y cm 10/2 Maximum horizontal / vertical functions x, y m 487 / 438 Maximum horizontal / vertical dispersion Dx, y m 0. 44 / 0. 47 Electron beam momentum Circumference Horizontal / vertical betatron tunes x, y 57(. 08) / 50(. 41) Horizontal / vertical chromaticities x, y -124 / -129 Momentum compaction factor 9. 97 10 -4 Transition energy tr JLEIC R&D Meeting, July 19, 2018 31. 67 15

Beam Parameters Beam energy Ge. V 3 5 6. 8 9 10 12 Beam current A 3 3 3 1 0. 66 0. 32 Total SR power MW 0. 37 2. 88 9. 53 9. 75 9. 81 9. 86 Energy loss per turn Me. V 0. 12 0. 93 3. 2 9. 75 14. 9 30. 8 Energy spread 10 -4 2. 8 4. 6 6. 3 8. 3 9. 3 11. 1 Transverse damping time ms 375 81 32 14 10 6 Longitudinal damping time ms 187 40 16 7 5 3 Normalized Horizontal Emittance um 9. 6 44 111 258 354 612 Normalized Vertical Emittance um 1. 1 5. 0 12. 5 28. 9 39. 7 6. 9 JLEIC R&D Meeting, July 19, 2018 16

Synchrotron Radiation Energy (Ge. V) 5 6. 8 10 12 Current (A) 3 Length Bending angle m rad 3 0. 66 0. 32 Bending radius Sagitta Synchrotron radiation density m cm k. W/m Bxarc? 3. 6 0. 037 98. 2 1. 65 2. 74 9. 38 9. 65 9. 70 BXDS 1? 3. 6 0. 023 158. 9 1. 02 1. 05 3. 58 3. 68 3. 70 BXDS 2? 3. 6 0. 014 257. 2 0. 63 0. 40 1. 37 1. 41 BYSR 1? 3. 6 0. 034 107. 3 1. 51 2. 30 7. 85 8. 08 8. 12 BXSR 1? 2 0. 038 52. 1 1. 00 9. 74 33. 31 34. 28 34. 46 BXSP 1 3 0. 0375 80 1. 41 4. 13 14. 54 14. 62 BXSP 2 0. 5 0. 0025 200 0. 016 0. 66 2. 26 2. 33 2. 34 BXSPL 3 0. 04 75 1. 50 4. 70 16. 08 16. 54 16. 63 JLEIC R&D Meeting, July 19, 2018 17

Chromatic Tune and * (@ 5 Ge. V) (-7, +9)σp JLEIC R&D Meeting, July 19, 2018 18

Summary Electron ring lattice with doglegs can be designed to satisfy the layout and emittance requirements. Missing － Crab cavity locations which need large beta functions － DA JLEIC R&D Meeting, July 19, 2018 19

Thank You for Your Attention ! JLEIC R&D Meeting, July 19, 2018 20