Interaction Region Construction
towards Phase 2
21th KEKB Accelerator Review Committee
KEK, 13-15 June 2016
Ken-ichi Kanazawa
forKEKB Vacuum GroupIR Technical Meeting Member
IR Installation Meeting Member
SVD/IR Mechanics Meeting Member
1

Contents• Outline from Phase 1 to Phase 2• Phase 2 hardware– QCS– Moving stage– BEAST II– IP chamber– Bellows unit
– QCS beam pipe
– RVC
– Concrete shield• Issues relating to IR vacuum• Summary2

Outline from Phase 1 to Phase 2Phase 1 IR with concrete shields

3Outline from Phase 1 to Phase 2

Phase 1 IR without concrete shields

R sideOho side

BEAST detectors

L sideNikko side

IP chambers for Phase 14

Outline from Phase 1 to Phase 2

Schematic drawing
Phase 1

Belle II
QCS beam pipe

QCS beam pipe

w/o VXD (Phase 2)
w. VXD (Phase 3)

IP chamber

Moving stage

QCSL

Bellows unit
RVC
QCSR

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

Moving stage5

OutlinefromPhase 1 toPhase 2

RVC installation
QCS beam pipe installation

6

Phase 2 hardware

QCSL

QCSL

SupportN. Ohuchi

7

Phase 2 hardware

Installation of the Moving Stage (L side)

Setting linear guides

Making a flat floor
Install Moving stage

Set base plates

Fill with mortar

The moving stage
for R side hadalready been
fabricated. It will be
installed at IR early
September (2016),
after floor work.
H. Yamaoka

8Phase 2 hardware

BEAST II~ 1m

320 mmCovered with CFRP

C. Marinas
9Phase 2 hardware

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 centralpart+Ridges: to keep thedirection of scatteredphotons away from Be(~10 µm)

Negligible trap of HOM atthe central part.

~10 µm10

Phase 2 hardware

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

The IP chamber for Phase 2 iscompleted. The IP chamber for
Phase 3 is needed before
September 2017 when theassembly of VXD starts. Therefore,
without feedback from Phase 2experiences, the next chamber for
Phase 3 must be fabricated.
11Phase 2 hardware

Bellows unit between IP chamber and QCS
CrCu

BPM pick-up
CrCu

QCS
sideCooling channel

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

This unit will be fabricated during 2016 Sep – 2017 May .
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Phase 2 hardware

Beam pipes for QCS
QCSL positron pipe was fabricated in FY 2015. Other three will be fabricated till June 2017.
Helium vessel

QC2LP

Bellowswith Oring seal

QC2LE

Beam pipe with a 4 mm thick wall, andwith water cooling channels therein.
Inside: Cu (+TiN) coated.

BPM

QC1LP

QC1LE

QCSL Cryostat

O-ring seal
betweenbeam pipes
and thecryostat.

Heavy metal cap replaces
the original cap after fieldmeasurement.
13Phase 2 hardware

RVC

AIM with RVC was approved at 18th B2GM (18-21 June 2014).
Emergency procedure when RVC is stuck was agreed.
• Left-hand side: Make a space for hand access by removingsome electronics of CDC, and detach RVC from QCSL.
• Right-hand side: Pull out VXD with QCSR.

DESY
The first mock-up tovalid the mechanism.

The second (~ final) product and their test mock-up.
The following slides show how RVC works.

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Picture 14 -19: How RVC works.

Two bellows units are attached to a single
flange with a retainer.

Karsten Gadow | KEK&DESY EVO Meeting | 01.06.2012 | Page 15

Picture 15

These components rotate to catchthe bellows flange.

Karsten Gadow | KEK&DESY EVO Meeting | 01.06.2012 | Page 16

Picture 16

Karsten Gadow | KEK&DESY EVO Meeting | 01.06.2012 | Page 17

Picture 17

Cylinderfor dry N2(about 50bar)

Thesecomponents
shift to press
the bellows
flange to thecryostat.

Karsten Gadow | KEK&DESY EVO Meeting | 01.06.2012 | Page 18

Picture 18

This large
screw nut
turns to lockthemechanism.

Karsten Gadow | KEK&DESY EVO Meeting | 01.06.2012 | Page 19

Picture 19

Karsten Gadow | KEK&DESY EVO Meeting | 01.06.2012 | Page 20

Phase 2 hardware

RVC: scheduling2015 Now(February) (KEK Vacuum group and Belle-II group)• Boundary conditions related to the QCS cryostat is nearly fixed.
• Space allocation around the right-hand side RVC is still under discussion. This will bediscussed 8-9 May by Belle-II Members.
2015 June – December (KEK and DESY)• Design of RVC (DESY) → Nearly complete (DESY)• Design of the bellows unit (KEK/DESY) → Not finished (KEK)• Design of the front cap of QCS (KEK/DESY) → Not finished (KEK)2016 (DESY and KEK)
• Fabrication and Laboratory test of RVC (DESY) → In progress (DESY)• Fabrication of the bellows unit (KEK/DESY) →2016 Sep – 2017 May (KEK)• Fabrication of the front cap of QCS (KEK/DESY) →2016 Sep – 2017 May (KEK)2017 March – April (before Phase 2)(KEK and DESY) → 2017 July
• Installation of RVC
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Phase 2 hardware

Concrete shield for Phase 2 and 3
Floor block1. Floor block to fill agap between theaccelerator floor and thedetector. This was set
March 2014.

Gate shield

4. Add 45 cm
concrete on the
top of the gateshield (2017).

3. Extension of thewall of theexperimental hall
(2015).

2. A concrete toreduce the front
aperture of thegate shield. The
frontend block of
the gate shield
will be modified
to attach thisconcrete (2017).

5. 80 cm thick concrete wall to cover the gap between the accelerator tunnel ceiling and the gate
shield (2015).
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Phase 2 hardware

MARS simulation•Beam loss estimation: Y. Ohnishi, Y.
Funakoshi•Simulation: T. Sanami•Condition: Full spec (Phase 3)
Requirement: Warning area (less than
1.5 µSv/h) during Phase 2
Since the target luminosity inPhase 2 is 1/80 of that in Phase 3,
The requirement will be satisfied.
If necessary, we will add a local
shield around the radiation source.
1 ~ 10 µSv/h ⊂ General radiation
area (1.5 ~ 20 µSv/h)23

Issues relating to IR vacuum

Vacuum system of IRNo vacuum
pumps in thisregion

24Issues relating to IR vacuum

Pressure distribution
SuperKEKB IR positron line 1000 A*hrs pressures

1.E-04

1.E-05Total
H2Pressure (mbar)

1.E-06

COCO2
CH4

1.E-07

1.E-08

1.E-09

1.E-10
-1500

-1000

-500

0500

1000

1500

Distance (cm)Thanks to J. Carter (ANL), M. Ady, R. Kersevan, and P. Chiggiato (CERN)

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Issues relating to IR vacuum

Pressure distribution• With the simulation software MolFlow andSynRad, a pressure distribution around IP wasestimated.
• The result is consistent with our previous
rough estimation.
• Though the effect of this locally high pressure
on the average pressure is not significant, acareful consideration on possible othereffects is necessary.
26

Issues relating to IR vacuum

Electron cloud in QC1RP• To evaluate the electron cloud density around IR is arecommendation at the last KEKB Accelerator Review Committee.
• J. A. Crittenden pointed out in the IPAC2015 paper (TUPTY081) that
if photon scattering is considered, the number of synchrotron light
photon incident on the QC1RP chamber is 30 times larger
compared with the case of no photon scattering. This suggests ahigh electron cloud density in the QC1RP chamber. And combinedwith a large vertical beta-function in QC1RP, this local cloud may
become a serious source of the beam blow-up. (TUPTY080)• The cross check of this claim is not yet completed.
• The positron beam pipes for QCS cryostat will be TiN coated.
• Continuous effort to understand the electron cloud in the final
focus magnets in necessary.

27

Summary• Outline from Phase 1 to Phase 2 is explained.
• Hardware for Phase 2 is prepared according tothe operational schedule.
• The IP chamber for Phase 2 is completed.
However, the next chamber for Phase 3 must beprepared without feedback from Phase 2experiences.
• The effect of a high pressure at IP and theelectron cloud in QCS should be carefully studied.
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