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 = (T/m)  m, ∫G dl QCSL = 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 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 SuperB.WS05.Hawaii

IR Magnets - Configuration of QCS and ES magnets (in the right side) Compensation solenoid, ESR –ESR is separated into two coil, ESR-1 and ESR-2. –ESR-1 is placed in front of QCS-R, and ESR-2 is overlaid on the outer surface of the QCS-R. –The E.M.F. on the ESR induced by the Belle field is 2.18  10 4 N. Final focus quadrupole, QCS-R –The magnet consists of six layer coils. –The operation field gradient is T/m, and the effective magnetic length is m. SuperB.WS05.Hawaii Magnet Operation Parameters under the Belle field of 1.5 T ESR-1ESR-2QCS-R I op, A B max, T I op /I c, % Length, mm O.R., mm

IR Magnets - Configuration of QCS and ES magnets (in the left side) Compensation solenoid, ESL-1 and ESL-2 –The E.M.F. on the ESL is 3.83  10 4 N. Final focus quadrupole, QCS-L –The magnet cross section is the same as the QCS-R. –The operation field gradient is T/m, and the effective magnetic length is m. SuperB.WS05.Hawaii Magnet Operation Parameters under 1.5 T ESL-1ESL-2QCS-L I op, A B max, T I op /I c, % Length, mm O.R., mm

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 T and 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. SuperB.WS05.Hawaii T T T T

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. SuperB.WS05.Hawaii ESR-2ESR-1ESL-1ESL-2 Belle Solenoid Belle center B z profile from 1.2 T to 1.6 T in the Belle detector

IR Magnets - QC1-RE and QC-1LE (Super-conducting or Normal-conducting) Normal-conducting type –Cu hollow conductor –Trim and backleg coils for the field correction –Unwanted multipole fields at the fringes (Ex, skew octupole) Super-conducting type –Nb-Ti rectangular solid cable –Corrector coils same as the QCS magnets for final alignment –Cryostat inner bore works as the function of the beam pipe. Careful consideration for the cryostat dislocation induced by the beam pipe. –An additional helium refrigerator is needed. –Careful consideration for magnet quench induced by beams since  is maximum at QC1s. SuperB.WS05.Hawaii Normal-conducting QC1-RE Super-conducting QC1-RE NormalSuper G, T/m L, m I op, A Turns/pole3130 Magnet Parameters (QC-1RE)

IR Magnets - QC1-RE and QC1-LE (Super-conducting or Normal-conducting) SuperB.WS05.Hawaii Normal-conducting QC1-LE Super-conducting QC1-LE NormalSuper G, T/m L, m I op, A Turns/pole3100 Magnet Parameters (QC1-LE)

Interference between Magnet-Cryostats and Belle - Cryostat design of QCS and ES Requirement from the Belle group –Redesigning cryostat configuration to reduce the Rad. Bhabha BG pointed by M. Sallivan in 6th HLWS, 2004 reported by O. Tajima in this meeting Introducing the heavy metal (Tungsten alloy) as one of the magnet structural materials. Necessary to modify the support system of the liquid helium vessel –Increasing the space between the detector and the cryostat for wiring the cables 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 97W-4Ni-1Cu 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 –Left : 451 kg  596 kg Heat load via 8 rods < 4 W –Requirement from the cryogenic system SuperB.WS05.Hawaii LeftRight Rod diameter, mm76 Rod length, mm65 Calculated stress of rod, N/mm Allowable stress at R.T., N/mm Total heat load (eight rods), W

Interference between Magnet-Cryostats and Belle - Belle end-cap, QC1 and movable table for IR magnets QC1 –The cryostat for the SC QC1 is slightly larger than the NC QC1. Transfer tube from the cryostat of ES and QCS –The outer diameter of transfer tube is modified from mm (KEKB) to 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. SuperB.WS05.Hawaii Accelerator components around the Belle end-cap iron yoke Cryogenic transfer tube

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 Additional iron yoke