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IR Magnets for SuperKEKB KEK, Norihito Ohuchi 1. IR Magnets (ES, - PowerPoint PPT Presentation

SuperB.WS05.Hawaii IR Magnets for SuperKEKB KEK, Norihito Ohuchi 1. IR Magnets (ES, QCS, QC1) 2. Interference between Magnet-Cryostats and Belle 3. Summary SuperB.WS05.Hawaii IR Magnets - Required IR magnets from beam optics


  1. SuperB.WS05.Hawaii IR Magnets for SuperKEKB KEK, Norihito Ohuchi 1. IR Magnets (ES, QCS, QC1) 2. Interference between Magnet-Cryostats and Belle 3. Summary

  2. SuperB.WS05.Hawaii IR Magnets - Required IR magnets from beam optics • Compensation solenoid (SC) – ESR and ESL, canceling the Belle solenoid field • Final focus quadrupole (SC) QCSR and QCSL for both beams, ∫ G dl QCSR = 11.99 (T/m) • m, ∫ G dl QCSL = 14.33 – • Special Quadrupole (NC or SC) QC1RE, QC1LE for HER beam, ∫ G dl QC1RE = 9.00, ∫ G dl QC1LE = 9.92 – • Special Quadrupole (NC) QC2RE, QC2LE, QC2RP and QC2LP, ∫ G dl QC2RE = 7.02, ∫ G dl QC2LE = 6.80, ∫ G dl QC2RP = 3.40, ∫ G dl QC2LP = 4.02 – IP QC2RE e- HER QC1RE QC2LP e+ ESL-1 QCSL 7 mrad 8 mrad Belle solenoid axis Beam-pipe axis QCSR LER ESR-1 QC2RP 22 mrad QC1LE ESR-2 ESL-2 QC2LE 0.0 5000.0 -5000.0

  3. SuperB.WS05.Hawaii IR Magnets - Spatial constraint for the design of the IR magnets • Physical aperture of beams – Determined by the beta function at the components and the beam acceptance (of which main sources are linac beam emittance and injection error). – Improvement of the beam acceptance by the damping ring for the positron beam. • SR envelops from QCS magnets – The intensities of the SR power are 179 kW and 64.6 kW from QCSR and QCSL, respectively. • The interference between the IR magnets and the detector components of Belle Belle boundary QC1R(SC)-cryostat-bore QC1L(SC)-cryostat-bore 150 150 QCSLA QCSR-cryostat-bore QCSRA 100 HER 100 QCSRC QCSLC QCSRI QCSL-cryostat-bore 50 50 QCSLI 0 0 [mm] [mm] LER -50 -50 -100 -100 beam physical aperture SOR from the IP or arc sides of each QCS IP deviation of SOR from the central route -4000.0 0.0 4000.0

  4. SuperB.WS05.Hawaii IR Magnets - Configuration of QCS and ES magnets (in the right side) Magnet Operation Parameters • Compensation solenoid, ESR under the Belle field of 1.5 T – ESR is separated into two coil, ESR-1 and ESR-2. ESR-1 ESR-2 QCS-R – ESR-1 is placed in front of QCS-R, and ESR-2 is overlaid on the outer surface of the QCS-R. I op , A 647.2 647.2 1186.7 – The E.M.F. on the ESR induced by the Belle field is 2.18 × 10 4 N. B max , T 2.76 2.61 4.99 • Final focus quadrupole, QCS-R I op / I c , % 63 60 75 – The magnet consists of six layer coils. Length, mm 100 1000 456 – The operation field gradient is 40.124 T/m, and the effective magnetic length is 0.299 m. O.R., mm 95.5 173.8 116.8 R 219 ESR R 239 ESR-2 QCSR QCSR R 90 R 69 R 50 ESR-1 478 e+ e- R 85 R 209 1378.3 R 194 R 186

  5. SuperB.WS05.Hawaii IR Magnets - Configuration of QCS and ES magnets (in the left side) Magnet Operation Parameters under 1.5 T • Compensation solenoid, ESL-1 and ESL-2 ESL-1 ESL-2 QCS-L The E.M.F. on the ESL is 3.83 × 10 4 N. – I op , A 656.2 656.2 1186.7 • Final focus quadrupole, QCS-L B max , T 4.33 2.93 4.77 – The magnet cross section is the same as the QCS-R. I op / I c , % 80 56 74 – The operation field gradient is 40.124 T/m, and the effective magnetic length is 0.357 m. Length, mm 166 500 514 O.R., mm 94.6 183.6 116.8 R 230 R 250 ESL R 197 ESL-2 QCSL ESL-1 R 69 R 50 21.2 QCSL 500 47.8 R 72 R 90 R 116.1 1036.8

  6. SuperB.WS05.Hawaii IR Magnets - QCS and ES magnets with Belle detector

  7. SuperB.WS05.Hawaii IR Magnets - B z field profile along the Belle axis • The negative peaks are -3.62 T and -1.68 T in the left and the right side with respect to the IP, respectively. • The regions, where the field gradients are large, are closer to the IP than KEKB. Bz profile of SuperKEKB, T Bz-profile.SBWS05 2 Bz profile of KEKB, T 1 0 -1 z , T B -2 -1.68 T -3 -3.20 T -3.62 T -4 -4.40 T -5 -4 -3 -2 -1 0 1 2 3 4 z, m

  8. SuperB.WS05.Hawaii IR Magnets - B z field profile in the Belle detector • The B z profile in the large volume of the Belle detector is almost same as that of KEKB. • In the area near the magnets and the IP, the profile shows a large difference from that of KEKB. – In this area, the field mapping should be performed, again. B z profile from 1.2 T to 1.6 T in the Belle detector Belle Solenoid ESL-2 ESL-1 ESR-1 ESR-2 Belle center

  9. IR Magnets SuperB.WS05.Hawaii - QC1-RE and QC-1LE (Super-conducting or Normal-conducting) • Normal-conducting type – Cu hollow conductor Magnet Parameters (QC-1RE) – Trim and backleg coils for the field correction – Unwanted multipole fields at the fringes (Ex, skew octupole) Normal Super • Super-conducting type G , T/m 12.0 27.67 – Nb-Ti rectangular solid cable L , m 0.75 0.328 – Corrector coils same as the QCS magnets for final alignment – Cryostat inner bore works as the function of the beam pipe. I op , A 3700 539.4 • Careful consideration for the cryostat dislocation induced by the beam pipe. Turns/pole 3 130 – An additional helium refrigerator is needed. – Careful consideration for magnet quench induced by beams since β is maximum at QC1s. Super-conducting QC1-RE Normal-conducting QC1-RE ø570 Cryostat ø420 R 59.17 R 78.17 R 85.17 SC Coil Iron Yoke

  10. SuperB.WS05.Hawaii IR Magnets - QC1-RE and QC1-LE (Super-conducting or Normal-conducting) Normal Super Magnet Parameters G , T/m 15.54 51.34 (QC1-LE) L , m 0.64 0.195 I op , A 1300 419.9 Turns/pole 3 100 Super-conducting QC1-LE Normal-conducting QC1-LE ø420.0 ø300.0 R 17.4 R 26.39 R 32.9 R 34.89 SC Coil Iron Yoke Cryostat

  11. SuperB.WS05.Hawaii Interference between Magnet-Cryostats and Belle - Cryostat design of QCS and ES IP Requirement from the Belle group QCSL-CENTER(z-direction) 969.4 – Redesigning cryostat configuration to ESL-2 ESL-1 reduce the Rad. Bhabha BG 30.00° pointed by M. Sallivan in 6th HLWS, 2004 QCSL 500 21.2 reported by O. Tajima in this meeting QCSL-CENTER(H) Introducing the heavy metal (Tungsten alloy) as one of the magnet structural materials. 97W-4Ni-1Cu Necessary to modify the support system of the liquid helium vessel – Increasing the space between the 130 85 detector and the cryostat for wiring QCS-CENTER 1163.3 ESR-2 the cables 17.00° QCSR ESR-1 ESR and ESL solenoids were calculated again, and the fronts of the cryostats were re-designed. The created space in radial direction : 25 mm for ESR 38 mm for ESL

  12. SuperB.WS05.Hawaii Interference between Magnet-Cryostats and Belle - Support design of QCS and ES • Support system – The system consists of 8 rods (titanium alloy) for one cryostat. • Change of the cryostat weight by the heavy metal – Right : 492 kg ⇒ 608 kg Liquid Helium vessel – Left : 451 kg ⇒ 596 kg 4.7 K • Heat load via 8 rods < 4 W Vacuum vessel – Requirement from the cryogenic system room temp. Left Right 300 K Rod diameter, mm 7 6 4.7 K EMF Rod length, mm 65 65 Calculated stress of rod, N/mm 2 306 290 Allowable stress at R.T., N/mm 2 400 400 W Total heat load (eight rods), W 1.92 1.44

  13. SuperB.WS05.Hawaii Interference between Magnet-Cryostats and Belle - Belle end-cap, QC1 and movable table for IR magnets Cryogenic transfer tube Accelerator components around the Belle end-cap iron yoke ø60.5 ø114.3 • QC1 ø45.3 – The cryostat for the SC QC1 is slightly larger than the NC QC1. ø42.7 ø48.6 • Transfer tube from the cryostat of ES and QCS ø39.4 ø8 – The outer diameter of transfer tube is modified from 216.3 mm (KEKB) to 114.3 mm. • Movable table for the IR magnets – As the material of the table, the thickness of the SUS plate is assumed to be 40 mm as same as that of KEKB. ø72.1 ø76.3

  14. SuperB.WS05.Hawaii Summary  The 3-D field calculations of the QCS and ES magnets have been completed.  These magnets have sufficient operation margin for the Super-KEKB.  The field profile in the Belle was calculated for the modified model of the ES magnets.  This profile around the IP and the cryostats should be checked by the Belle group.  QC1 magnets in the normal-conducting and super-conducting types are designed and compared.  We should do the further study for both magnets, ex., 3-D field calculation, effect of the field profile on the beam optics and handling in the actual operation.  For shielding the Rad. Bhabha BG, application of the heavy metal was studied as the material of the magnet components in the cryostat. The heavy metal does not have a large effect on the cryogenic design at LHe temperature.  The interference between the Belle end-cap iron yoke, cryogenic transfer tube and QC1 is manageable at present.

  15. SuperB.WS05.Hawaii  Additional end cap iron yoke  For the iron yoke of 10 cm thickness in the radial direction, the EMF on the ES is reduced.  ESR: 2.18 × 10 4 N ⇒ 1.00 × 10 4 N, ESL: 3.83 × 10 4 N ⇒ 2.96 × 10 4 N OHO NIKKO SIDE SIDE 17.00° 30.00° ESL 17.00° 17.00° QCS L ESL QC1L QC1R Electron 670 Positron 970 Additional iron yoke 0 1 2

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