IR Assembly

22nd KEKB Accelerator Review Committee
KEK, 14-16 March 2018
Accelerator Laboratory
Ken-ichi Kanazawa
ForAll persons working at IR
22nd MAC 2018

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Contents• Assembly for Phase 2• BEAST II installation– IP chamber– BPM-bellows tube

• QCS cryostat parts exchange– New cryostat head
– QCS beam pipe
– RVC•••••

QCS-BEAST II connection
IR after QCS-BEAST II connection
Water cooling troubles
Concrete radiation shield for Phase 2
Summary
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Assembly for Phase 2

Schematic drawing
Phase 1Belle II
QCS beam pipe

QCS beam pipe

w. Beast II (Phase 2)
w. VXD (Phase 3)

IP chamber

Moving stage

BPM-bellows tube
QCSL RVC
QCSR

QCS: Final focus superconducting magnet system
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RVC: Remote vacuum connection

Moving stage

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BEAST II installation

IP chamber: Design feature
HIP = Hot Isostatic
Pressing~10 µmOnly taper parts are
exposed to direct
synchrotron radiationfrom the last bend.
Taper: to reduce thenumber of photons
entering into the central
part+Ridges: to keep thedirection of scatteredphotons away from Be(~10 µm)~10 µmBeam space design with minimum trapof HOM at the central part.
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BEAST II installation

IP chamber•The central straight part consists ofdouble tube. Paraffin runs betweenthem.
•Outer Be: 0.4 mm thick•Inner Be: 0.6 mm thick•Gap: 1 mm

Without feedback from Phase 2experiences, the next chamber for
Phase 3 must be fabricated.
BEAST II
Photo by M. Tobiyama

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BEAST II installation

BPM-bellows tube between IP chamber and QCS
CrCu

BPM pick-up
CrCu

QCS
sideBellows unit with aconventional RF-bridge.
A comb-type structure cannot
give a sufficient flexibility fora small diameter.

Cooling channel

22nd MAC 20186Beast II installation

Connecting BPM-bellows tube
Beast II assembling group strongly suggested that
it is practically impossible to connect BPM-bellows
tubes to the IP chamber after BEAST II is installed
into Belle (especially in FWD).
Therefore, The tubes were connected to the IP
chamber before BEAST II installation.

BPM-bellows tubes (about 14cm long) set on a flange for
RVC

Travel limiter to limit thelongitudinal displacement of thebellows.
It was found a cable for thenearby BPM feedthrough must beconnected before this limiter isset.
Photo by M. Tobiyama
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Beast II installation

Connecting BPM-bellows tube
Cable cage

FWD
The vacuum flanges of IP chamber isabout 8 cm behind the cable cage.
The cable cage interferedwith connecting work. It is
temporally removed.

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Photo by M. Tobiyama
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Beast II installation

Connecting BPM-bellows tube

BWD
The vacuum flanges of IP chamber isin front of the cable cage.

Vacuum leak check

Work summary
Not a few issues didn’t follow an original scenario. Serious discussion based on thisexperience is necessary for Phase 3.
Photo by M. Tobiyama
22nd MAC 20189Beast II installation (Nov. 18, 2017)

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Photo by M. Tobiyama
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QCS cryostat parts exchange

New cryostat head
Replace the head of the cryostat witha new one which has a W-alloy face.
The face is machined to install RVC onit.
RVC: Remote Vacuum
Connection (picture later)

Exchange the cryostat head

Leak check of thecryostat
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QCS cryostat parts exchange

Beam pipes for QCS
Beam pipe is made of stainless steel, with a 4 mm thick wall, and with water coolingchannels therein. Inside is Cu (+TiN) coated. It is fixed to the QCS cryostat.
Helium vessel

QC2LP

Bellowswith Oring seal

QC2LE

BPM

QC1LP

QC1LE

QCSL Cryostat
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O-ring seal
betweenbeam pipes
and thecryostat.

Heavy metal cap replaces
the original cap after fieldmeasurement.
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QCS cryostat parts exchange

QCS beam pipe installation
Set beam pipeSI
G10 spacer
Beam pipe

BPM

Attach BPM
and leak check

Connect
BPM cable

Beam pipe is inserted using
a special toolService window on the QCSR cryostat
used to manually guide the beam
pipe and toattach BPM
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Leak check ofthe cryostat
Photo by Y. Arimoto
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QCS cryostat parts exchange

QCS beam pipe installation

QCSL BPM

Since QCSL has no service windows, thecryostat was disassembled for this work.
Magnet group checked marker positions on
the cryostat after re-assembling. Roughly
speaking, the front body is rotated anticlockwise by 0.7 mrad seen from IP. The
consistency of the measurement with themechanical tolerance of the cryostat design isnot yet given.
22nd MAC 2018Work summary
1. The front nitrogen-shield of QCSR
were not in the correct position, andinterfered with beam pipes. Theinterference was removed by remachining the shield.
2. The outside space of G10 spacers
was different from available
drawings. The spacers were remachined.
Photo by Y. Arimoto
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QCS cryostat parts exchange

RVC

RVC is a mechanism introduced byBelle group to disconnect QCS from
VXD by a remote manipulation.
RVC was designed and produced by
DESY.

RVC on the new
QCS head

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Photo by DESY

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QCSR-Beast II connection (Jan. 9, 2018)

QCSR head

FWD CDC tunnel

QCSR proceeding

QCSR connectedto Beast II

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Photo by I. Nakamura

QCSL-Beast II connection (Jan. 15, 2018)

Trouble!! A number of contact
fingers are out of place.

Contact fingers were miraculously
put in order by Karsten (DESY)

KarstenLeak checking scene
Photo by I. Nakamura

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QCS-Beast II connection
Work summary• Just before QCSL-Beast II connection, it was found that contact fingers of one BPMbellows tube were out of place. This seems to be caused by an accidental largeturning of the RVC flange. Happily enough, this was repaired by Karsten. We
should be careful not to cause the same trouble for Phase 3.
• At the first trial of QCSL move-in, cooling pipes for the BPM-bellows tube designed
by KEK interfered with RVC, and RVC was not able to catch the flange of BPMbellows tubes. This is caused by miss-estimation of the RVC volume in designing
the cooling tubes. The interference was not serious to cause any mechanicaldamage. The cooling tubes were replaced with those prepared by DESY.
• RVC worked completely well.

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IR after QCS-BEAST II connection
L-side（Nikko-side, D1-side, BWD）

R-side (Oho-side, D2-side, FWD)

All magnets are re-installed, all beam pipes are connected. Cabling and other works aregoing on.
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Water cooling troubles•On Feb. 16, cooling water was flowed, with a pressure less than 4.5 bar. After about one our, a water
sensor of CDC (backward) got alarmed. After searching work, it was found the cooling line of the HER
bellows outer at BWD, most probably its flex part, shows a leak of 2 Pa m3 sec-1, using a pressurized
nitrogen of 5 bar.
–••

On Feb. 16, cooling water was flowed to QCSL beam pipe, but water froze. This is caused insufficient prewarm-up of the pipe. By this accident, it was necessary to warm up QCSL temporally.
–

Before flowing water to QCS beam pipe, flow room-temperature nitrogen at least 10 hours.

–In case the water stops, nitrogen will be purged.

On Mar. 5, after cooling water was flowed, HV trip happened at some layers of CDC without any alarm by awater sensor. After checking work, it was found the cooling line of the LER bellows outer at FWD shows aleak of 3x10-2 Pa m3 sec-1.
–••

We decided to use (cooled) nitrogen gas for the leaked line (Suggested by T. Kageyama).

We decided to use room-temperature nitrogen gas for this line for safety.

Nitrogen is supplied from the Belle cryogenic system.
Snoop criterion: If the leak rate measured by gas is less than 10-3 ~ 10-2 Pa m3 sec-1 , water does not leak.

Back-up for gas cooling• Apply a water circulation driven below atmospheric pressure.
• A chiller by this method is commercially available. We started a study to construct a realistic system.
• Apply a liquid seal.
• Mock-up test is successful. A present concern is about the material property of the seal.
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Water cooling troubles

Cooling lines

Almost leaked at FWD

Drawing by K. Gadow
Leaked at BWD
We cannot access these coolingtubes without separating QCS
from BEAST II.
Photo by I. Nakamura
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Water cooling troubles

Why gas cooling: simulation conditions
Inlet

OutletBellows
Heat load: 1000 W/m2

Outside surface: 25℃
Cooled by convection: 5W/m2/K

Heat load: 2500 W/m2
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RF finger
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Water cooling troubles

Simulation byK. Watanabe

Why gas cooling
Flow rate

RF finger

Bellows

Pressure（MPa）
Outlet Temp

Water

1.7 l/min(30 C)

39.9 C69.2 C

In: 0.3062, Out: 0.3013
30.11 CGas -10.25 l/s(30 C)

87.3 C107.2 C

In: 0.1019, Out: 0.1013
53.9-60.6 C

Gas-2

0.40 l/s(30 C)

66.6 C90.6 C

In: 0.2036, Out: 0.2013
37.6-42.8 C

Gas-3

0.52 l/s(30 C)

57.6 C

83.4 C

In: 0.3068, Out: 0.3013
34.0-37.0 C

No cooling

0.01 l/s(30 C)

177.6 C

179.5 C

Gas-4

0.52 l/s(20 C)

48.1 C

75.6 C

Possible flow rate

In: 0.3071, Out: 0.3013
23.4-27.3 C

The value of temperatures is not important, since we don’tknow the actual heat load.
The important point is that gas cooling is not so bad
compared with water cooling.
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Concrete radiation shield for Phase 2(1) The front end of the existing gate shield was newly designed to have a narrow opening.

(2) Polyethylene layer between the shield and the end yoke of the detector.
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Concrete radiation shield for Phase 2（3）Additional shields on top of the existing shield, and at the boundary between
the experimental hall and the accelerator tunnel.

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Concrete radiation shield for Phase 2

New shields at L-side.
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Conclusion• Now IR is ready for Phase 2.
– Beams will judge our ambitious designs.
– Experiences during construction should bereviewed carefully and be reflected for Phase 3
preparation.

• As to water leak trouble, we chose a merit ofensuring beam-tuning time than a risk ofbellows heat-up.
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