Overview of IR magnets andconstruction status
N. Ohuchi

2016/06/14

SuperKEKB Review 2016

1

Contents
1. IR magnets
2. Production of magnets and cryostats
3. Tests and construction schedule
4. Summary

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SuperKEKB Review 20162

Overview of IR magnets
QCS-R Cryostat

QCS-L Cryostat

Helium Vessel

Helium Vessel
QC2LP
4 correctors(a1,b1,a2,b4)

ESR1 Solenoid

ESL solenoid

4 correctors

QC1LP
4 correctors

Leak field(a1,b1,a2,a3)

b3 corrector

cancel coils(b3,b4,b5,b6)

QC2RE

IP
(a1,b1,a2,b4)

QC1LE
4 correctors(a1,b1,a2,b4)

ESR2

QC1RE

(a1,b1,a2,b4)

QC2LE
4 correctors

Helium Vessel

4 correctors(a1,b1,a2,a3)

83 mradLeak fieldcancel coils(b3,b4,b5,b6)

QC1RP
5 correctors

b3 corrector(a1,b1,a2,a3,b4)

QC2RP
4 correctors

HER(a1,b1,a2,a3)

ESR3

Helium Vessel
4 SC main quadrupole magnets: 1 collared magnet, 3 yoked magnets
16 SC correctors: a1, b1, a2, b4
4 SC leak field cancel magnets: b3, b4, b5, b6
1 compensation solenoid
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LER

4 SC main quadrupole magnets: 1 collared magnet, 3 yoked magnets
19 SC correctors: a1, b1, a2, a3, b3, b4
4 SC leak field cancel magnets: b3, b4, b5, b6
3 compensation solenoid

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Overview of IR magnets• Main quadrupoles [QC1, QC2]

− Forming final beam focusing system with quadrupole doublets.

• Correctors [a1, b1, a2, a3, b3, b4]− a1, b1, a2: magnetic alignment of the magnetic center and the mid-plane phaseangle of main quadruple.
− a3, b3: correction of sextupoles induced by magnet construction errors.
− b4:increasing the dynamic transverse aperture (increasing the Touschek life time).

• Compensation solenoid[ESR, ESL]− Canceling the integral solenoid field by the particle detector (Belle II).
− By tuning the Bz’ profile, the beam vertical emittance can be minimized.
− The compensation solenoids are designed to be overlaid on the main quadrupoles
and correctors.
− ESR consists of three solenoid magnets of ESR1, ESR2 and ESR3.

• Leak field cancel coils [b3, b4 , b5, b6]− Canceling the leak field on the electron beam line from QC1P (collared magnet).

•

Total number of the SC devices in two cryostats = 55
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Overview of IR magnets• Main quadrupoles [QC1, QC2]
– QC1L(R)P, QC2L(R)P for the left (right) side cryostat to IP and for the position beam line.
– QC1L(R)E, QC2L(R)E for the left (right) side cryostat to IP and for the electron beam line.
ESR-add
QC2LP

ESL

ESR

QC1LP

QC2RE

QC1RE

QC1RP

QC2LE

QC1LE

QC2RP

IRON

Integral field gradient, (T/m)・m

Magnet type

Z pos. from IP, mm

θ, mrad∆X, mm

∆Y, mm

QC2RE

13.58 [32.41 T/m × 0.419m]

Iron Yoke

2925

0

-0.7

0

QC2RP

11.56 [26.28 × 0.410]

Permendur Yoke

1925

-2.114

0

-1.0

QC1RE

26.45 [70.89×0.373]

Permendur Yoke

1410

0

-0.7

0

QC1RP

22.98 [68.89×0.334]

No Yoke

935

7.204

0

-1.0

QC1LP

22.97 [68.94×0.334]

No Yoke-935-13.65

0

-1.5

QC1LE

26.94 [72.21×0.373]

Permendur Yoke

-1410

0

+0.7

0

QC2LP

11.50 [28.05 × 0.410]

Permendur Yoke

-1925

-3.725

0

-1.5

QC2LE

15.27 [28.44×0.537]

Iron Yoke

-2700

0

+0.7

0

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Overview of IR magnets• Cross section design of main quadrupoles [QC1, QC2]
– The quadrupole magnets are designed with the two layer coils (double pane cake design).
– In the early design, the smaller young modulus of the SC cable than the real cable were applied.
• As the result, 10 units sextupole field by the assembly error of the magnet was induced.
• All magnet cross sections were redesigned, and a3 and b3 correctors have been installed in theright cryostat.

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Overview of IR magnets• Correctors– From space constraint, the SC correctors were designed inside of the quadrupole bores .
– The SC correctors were designed and directly wound on the support bobbin (helium inner

vessel) by BNL under the US-Japan research collaboration• Direct winding method• Multi-layer coil [maximum layer=4 by limiting with the gap distance between the main
quadrupole magnet and the helium inner vessel]• Some correctors were assembled on the outer surface of the main quadrupole magnets.
– Each corrector is excited by the individual bipolar power supply.

QCSL

QCSR

Main Quadrupole

Corrector

Main Quadrupole

Corrector

QC1LP

a1, b1, a2, b4

QC1RP

a1, b1, a2, a3, b4

QC2LP

a1, b1, a2, b4

QC2RP

a1, b1, a2, a3

QC1LE

a1, b1, a2, b4

QC1RE

a1, b1, a2, a3

QC2LE

a1, b1, a2, b4

QC2RE

a1, b1, a2, a3

Between QC1RP and QC2RP

b3

Between QC1RE and QC2RE

b3

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Overview of IR magnets• Direct winding SC Corrector by BNL
a1 corrector winding for QC1LP @BNL

Collared QC2LE

Correctors

Assembly of QC2LE andcorrectors
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Overview of IR magnets• Compensation solenoids [ESL, ESR1, ESR2 and ESR3]••

In the left cryostat, one solenoid (12 small solenoids) is overlaid on QC1LP and QC1LE.
In the right cryostat, the 1st solenoid (15 small solenoids) is overlaid on QC1RP, QC1RE and QC2RP.
̶ The 2nd and 3rd solenoids on the each beam line in the QC2RE vessel.
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Overview of IR magnets• Compensation solenoids [ESL, ESR1]
ESL consists of 12 coils:
Magnet length= 914 mm
Maximum field at 403 A= 3.53 T
Stored Energy= 118 kJ

ESR1 consists of 15 coils:
Magnet length= 1575 mm
Maximum field at 450 A=3.19 T
Stored Energy= 244 kJ

The quench protection system
is reported by X. Wang.

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Overview of IR magnets• Compensation solenoids [ESR2, ESR3]
ESR3 for LER beam line
ESR2
bobbinQC2RE

a1, b1, a2, a3
correctors

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Overview of IR magnets• QC1P leak field cancel magnets
−
−
−
−
−

QC1P for the e+ beam line is non-iron magnet and the e- beam line is very close to QC1P. The leak fields from
QC1P go through the e- beam line.
B3, B4, B5 and B6 components of the leak fields are designed to be canceled with the SC cancel magnets.
By rolling QC1P in design and lower level of the QC1P axis than HER beam line, skew field components are
induced. The cancel magnets are rotated to cancel the skew components in design.
B1 and B2 components are not canceled, and they are included in the optics calculation.
B2 component is used for focusing and defocusing the e- beam.

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Production of magnets and cryostats
QCSL magnet cryostat

Service cryostat

Cryostat

Cross section of QCSL magnet cryostat

2724
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Production of magnets and cryostats• SC magnets– 8 main quadrupole magnets: completed– 35 correctors: completed– 8 leak field cancel magnets: completed– 4 compensation solenoids: 3 solenoids are completed.
• ESR2 for e- beam line will be completed in July.

• Magnet-cryostats– QCSL magnet cryostat was completed, and delivered to KEK at Dec.
25, 2015.
• Constructing the QCSL cryostat started at Nov. 2014, and the cryostat was
expected to be delivered to KEK in March 2015.
• During assembly, several electrical troubles happened.
• Field measurements are now on going.

– QCSR magnet cryostat is now being built.
• The QCSR cryostat will be delivered in November.
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Production of magnets and cryostats
Assembly of the QC1LP, QC2LP, QC1LE, correctors and QC1LP leak field cancel magnets(Front cold mass of QCSL)
QC1LE
a1, b1, a2, b4 correctors

Magnetic shield

QC1LP leak field cancel magnets
QC2LP
a1, b1, a2, b4 correctors
Magnetic shield

QC1LP
a1, b1, a2 correctors
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b4 corrector

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Production of magnets and cryostats
Assembly of the front cold mass of QCSL

Measurement of quadrupole alignment
in the cold mass with the stationary
harmonic coil at room temperature

Iron
SUS
Fixing the magnets with the support
components
Assembling ESL on
the front cold mass
Covering thecold mass withthe helium
vessel andwelding thevessels

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Assembling theradiation shieldof W alloy on
ESL

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Production of magnets and cryostats
Front and rear cold masses of QCSL
Front cold mass

1546

700

Rear cold mass
(QC2LE)
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Production of magnets and cryostats
Assembling the cold masses into the QCSL cryostat
Vacuum vessel
Front cold mass

Rear cold mass
(QC2LE)

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Production of magnets and cryostats• Troubles : Electrical insulation damages during assemblyof the QCSL cryostat– Voltage signal cables in the pipes by welding heat
• Replacement of cables and pipes– ESL solenoid coil
• The SC cable insulation was damaged by the edge of the radiation shield.
• The cold mass was disassembled to find the damaged position.

– ESL SC cable and voltage signal cables in the service cryostat• The cables were damaged by the edge of the SUS plate as the shield to
welding heat.

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Production of magnets and cryostats
The QCSL magnet cryostat was delivered to KEK at Dec. 25, 2015.

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Production of magnets and cryostats
Assembly status of the QCSR magnet cryostat

QC1RE, QC1RP leak fieldcancel magnets andcorrectors

QC1RP, QC2RP andcorrectors

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Tests and construction schedule• The QCSL magnet cryostat is being tested in the experimentallaboratory from Feb. 19th, 2016.
– Cool down test
• Measurement of the temperature profile in the cryostat• Heat load measurements of the cryostat• Results of the cold test is reported by Z. Zong.

– Excitation test
• Excitation of all magnets in the single and combined modes– Field measurements by harmonic coils• Integral field measurements and field profile measurements by two type of harmonic coils• For different inner radius of quadrupole magnets, harmonic coils of three different radii areprepared.

– Quadrupole axis and mid-plane angle by single stretched wire (SSW)• Measurements have been performed with FNAL colleagues under US-Japan researchcollaboration.

– Solenoid field measurement by 3D Hall probe• The measurement system is being prepared, and the measurement will be performed inlast half of this month.
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Production of magnets and cryostats• Problem :– QC1LP leak field cancel magnets compensate the normal andskew field components of C3, C4, C5 and C6 in design.

• a3, a4, a5 and a6 were not cancelled while the normal components were
well cancelled.

Integral field measurement result of cancel sextupole magnet
Measured radius = 12 mm

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Production of magnets and cryostats
Field profile of leak field by QC1LP• Field profile measurements

Field profile of cancel sextupole magnet

2016/06/14– Measurements were performed by
the 20 mm long harmonic coil.
– b3 by the cancel magnet has the
opposite sign to b3 of the leak field
by QC1LP.
– a3 by the cancel magnet has thesame sign to a3 of the leak field by
QC1LP.

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Production of magnets and cryostats• Impact of a3 to e- beam

– In case of no a3 on the e- beam line, Touschek life time is 648.1 sec.
– With measured a3, Touschek life time is reduced to 304.5 sec.

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Production of magnets and cryostats• When the sextupole cancel magnet in QCSR has the same problem– Reduction of Touschek life time is less than the only one side.
– By optimization, the life time is recovered to 599 sec.

The reason of the opposite rotation of
the cancel magnet is under investigation.

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Tests and construction schedule• Major works after Phase-1 commissioning operation to Phase-2̶̶Completion of QCSR magnet cryostat• Assembly of cold mass
• Field measurements at room temperature
Construction of the two cryogenic systems• The cooling power of the refrigerator for QCSL was measured at 2014.
−

Connection between the cryogenic system and the QCSL cryostat−−

The refrigerator was moved to the IR in the Tsukuba experimental hall.
Building the cryogenic system with completion of the QCSR cryostat.

−−−

Field quality by harmonic coils
Magnet alignment by single stretched wire (SSW) under the research collaboration with FNAL
Field profile along the beam lines by Hall probe• The refrigerator for QCSR was kept in a separate building from 25 years ago
after shutting TRISTAN down.
̶

Tests and measurements in the Tsukuba IR• Tuning the operations of two cryogenic systems and cooling two cryostats
down to 4K.
• Excitation tests of 55 SC magnets• Field measurements of 55 magnets on the beam lines.

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Tests and construction schedule• Construction of final focus magnet system in SuperKEKB IR̶̶The magnet-cryostats have the individual cold box.
Construction and process tuning of the two cryogenic system are performed in series.

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Construction Schedule
Construction status of cryogenics
New He compressor building and He tanks for QCSRHe refrigerator
for QCSR

He compressor for QCSR

Relocated from Oho exp. hall to the newcomp. building in Tsukuba exp. hall.

He refrigerator
for QCSL

Additional He gas tank for QCSL
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Tests and construction schedule• Measurements of harmonic coils in SuperKEKB IR̶̶̶̶One unit of measurement system has two harmonic coils.
The harmonic coils are moved by the mover, the movement is measured by the digital scaler.
Two sets of the mover system are prepared for shortening the measurement period.
The harmonic coil measurement is reported by Y. Arimoto.

For QC1P and QC1E
L=600 mm and 20 mm, R=12 mm
For QC2P
L=700 mm and 20 mm, R=25 mm

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For QC2E
30 mm
L=800 mm and 20 mm, R=33

Tests and construction schedule• SSW measurements in SuperKEKB IR̶̶The wire is stretched along the beam line which goes through IP.
Two magnet-cryostats of QCSL/R are aligned to the beam lines with the targets of the cryostats.
The SSW system directly measures the quadrupole field centers and angles with respect to thebeam lines with the precision of ±0.1 mm.

̶̶

SSW measurement is reported by H. Iinuma.

QCSL magnetcryostat

QCSR magnetcryostat

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Construction Schedule
Calendar Year

Calendar Month

2016
5

6

7

8

2017
9

1
0

1
1

1
2

1

2

3

4

5

6

7

8

9

1
0

1
1

Tests and measurements of QCSL Magnet-Cryostat
Installing QCSL into IR
Construction of QCSL cryogenic system
Examination of high pressure gas regulation
Cooling the QCSL cryogenic system and excitation tests
Cooling the system and field measurements of QCSL with Belle

QCSR Magnet-Cryostat to KEK
Installing QCSR into IR
Construction of QCSR cryogenic system
Examination of high pressure gas regulation
Cooling the QCSR cryogenic system and excitation tests
Field measurement of QCSR with Belle

Warm up of QCSL and QCSR, andCooling QCSL and QCSR for Phase-2 operation

Phase-1 commissioning
Phase-2 commissioning

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1
2

Summary• QCSL magnet cryostat was delivered to KEK at Dec. 25,
2015.
– The cold test of the cryostat started from Feb. 19, 2016, andthe field measurements are going on.
– From the field measurements, it turns out that the QC1LP leakfield cancel magnets have wrong rotation.
• The reason of the wrong rotation is under investigation.

• QCSR magnet cryostat is expected to be delivered to KEK
in November 2016.
• Tons of work for completing the final focus system will
be done until June 2017.
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Back up2016/06/14

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Production of magnets and cryostats• Voltage signal cables in the pipes by welding heat
Voltage signal cablesfrom magnets for
detecting quench:
Electrical insulation
was damaged bywelding heat.

Insulation was
melted and bonded
to the inner surfaceof the pipe.

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Production of magnets and cryostats••

The position was specified when the tungsten radiation shields were dismounted
from the ESL.
It was considered that the electrical insulation was damaged by the edge of thetungsten radiation shield during assembly to the ESL.

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Production of magnets and cryostats
Tungsten radiation shield

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Production of magnets and cryostats
Electrical earth fault for the ESL SC cable and the voltage signal
QC2LP signal cable(electrical insulation
was contracted by
heat)

QC2LP
SC cable

QC2LP signal
cable(red)ESL signal
cable
ESL SC cable(black)ESL SC cable(The glass tape for mechanicalprotection was damaged, and the
Kapton tape for electricalinsulation appeared.)
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Field calculation by 3D model
IR 3D model : all magnets with the corrector magnets are included.
• The calculation model is now being refined by Y. Arimoto.

By Y. Arimoto
2016/06/14

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