ir magnets for superkekb kek, norihito ohuchi 1.ir magnets (es, qcs, qc1) 2.interference between...
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IR Magnets for SuperKEKB
KEK, Norihito Ohuchi
1. IR Magnets (ES, QCS, QC1)2. Interference between Magnet-Cryosta
ts and Belle3. 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
SuperB.WS05.Hawaii
8 mrad
22 mrad
7 mrad
e-
e+
LER
HER
IP
ESR-2
QCSRESR-1
ESL-1
ESL-2
QCSL
QC1LE
QC1REQC2LP
QC2RP
QC2RE
QC2LE
Beam-pipe axis
Belle solenoid axis
0.0 5000.0-5000.0
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
IP
LER
QCSRI
0
50
100
150
-50
-100
[mm]
QCSR-cryostat-bore
QC1R(SC)-cryostat-bore
QCSLA
QCSLC
QCSLI
QCSL-cryostat-bore
QC1L(SC)-cryostat-bore
0
50
100
150
-50
-100
[mm]
QCSRA
QCSRCHER
Belle boundary
0.0 4000.0-4000.0
beam physical aperture
SOR from the IP or arc sides of each QCS
deviation of SOR from the central route
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 ov
erlaid on the outer surface of the QCS-R.– The E.M.F. on the ESR induced by the Belle field is
2.18104N.• Final focus quadrupole, QCS-R
– The magnet consists of six layer coils.– The operation field gradient is 40.124 T/m, and th
e effective magnetic length is 0.299 m.
SuperB.WS05.Hawaii
R 239
R 50
R 69R 90
R 85
R 219
R 209
R 194
R 186
e-
e+
QCSR
ESR
QCSR
ESR-1
ESR-2
1378.3
Magnet Operation Parameters under the Belle field of 1.5 T
ESR-1 ESR-2 QCS-R
Iop, A 647.2 647.2 1186.7
Bmax, T 2.76 2.61 4.99
Iop/Ic, % 63 60 75
Length, mm 100 1000 456
O.R., mm 95.5 173.8 116.8
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 3.83104N.
• Final focus quadrupole, QCS-L– The magnet cross section is the same as the QCS-
R.– The operation field gradient is 40.124 T/m, and the
effective magnetic length is 0.357 m.
SuperB.WS05.Hawaii
Magnet Operation Parameters under 1.5 T
ESL-1
QCSL
ESL-2
1036.8
R 50
R 250R 230
R 197
R 90
R 116.1
47.8
QCSL
ESL
R 72
21.2
R 69
ESL-1 ESL-2 QCS-L
Iop, A 656.2 656.2 1186.7
Bmax, T 4.33 2.93 4.77
Iop/Ic, % 80 56 74
Length, mm 166 500 514
O.R., mm 94.6 183.6 116.8
IR Magnets - Bz 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.
SuperB.WS05.Hawaii
-5
-4
-3
-2
-1
0
1
2
-4 -3 -2 -1 0 1 2 3 4
Bz-profile.SBWS05Bz profile of SuperKEKB, TBz profile of KEKB, T
Bz, T
z, m
-3.62 T
-1.68 T
-4.40 T
-3.20 T
IR Magnets - Bz field profile in the Belle detector
• The Bz 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
Bz 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 sin
ce is maximum at QC1s.
SuperB.WS05.Hawaii
R 78.17
SC Coil
Iron Yoke
R 59.17
R 85.17
ø570Cryostat
ø420
Normal-conducting QC1-RE
Super-conducting QC1-RE
Normal Super
G, T/m 12.0 27.67
L, m 0.75 0.328
Iop, A 3700 539.4
Turns/pole 3 130
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
Normal Super
G, T/m 15.54 51.34
L, m 0.64 0.195
Iop, A 1300 419.9
Turns/pole 3 100
Magnet Parameters(QC1-LE)
R 26.39
R 32.9
R 34.89
ø300.0
R 17.4
Iron Yoke
SC Coil
ø420.0
Cryostat
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) a
s 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 ESR38 mm for ESL
QCS-CENTER
130 85
1163.3
QCSRESR-1
ESR-2
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
Liquid Heliumvessel4.7 K
Vacuum vesselroom temp.
300 K
4.7 KEMF
W
Left Right
Rod diameter, mm 7 6
Rod length, mm 65 65
Calculated stress of rod, N/mm2 306 290
Allowable stress at R.T., N/mm2 400 400
Total heat load (eight rods), W 1.92 1.44
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 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.
SuperB.WS05.Hawaii
Accelerator components around the Belle end-cap iron yoke
ø42.7
ø39.4
ø114.3
ø48.6
ø45.3
ø60.5
ø8
ø76.3
ø72.1
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