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