1. The interaction region and BEAST II
S. Tanaka (KEK)

2. KEK VXD group
S.Tanaka (VXD assembly coordinator: BP, shields, PXD liaison)
H. Nakayama(BG simulation, BEASTII+BG monitors)
K.Hara(SVD group leader)
T.Tsuboyama (SVD)
K.Nakamura (SVD)
T. Kohriki (mechanics designer: BP, CDC, TOP. ARICH)
S.Koike (VXD mechanics designer)
N.Sato(SVD mechanics engineer)
K.Kanazawa (machine group: BP design)

3. SuperKEKB (KEKB upgrade)
e- (7 GeV)
Boosted U(4s) production by asymmetric e+e- collider
√s ~10.58GeV
Target luminosity: 8・1035cm-2s-1
40 times higher than KEKB
Nano beam scheme
e+ (4 GeV)
e- (7 GeV)
e+ (4 GeV)
Y(4S)
dz~cbgtB
Y(4S)
~200mm (Belle)
~130mm (Belle II)
SuperKEKB bg=0.28 : e-(7GeV), e+ (4GeV)
KEKB bg=0.42: e-(8GeV), e+ (3.5GeV)
LER (3.5 GeV -> 4GeV):
• Longer Touschek lifetime ∝ E 3
• Intra-beam scattering effect to emittance
HER (8 GeV -> 7GeV):
• Lower emittance linac beam ∝ 1/E 2
• Lower Synchrotron radiation loss

4. DEPFET pixels as a vertex detector for the Belle II experiment
Nano beam scheme
Lorentz
factor
Beam current
Beam-beam parameter
correction coefficient
s: Beam size
b function: aperture of beam
parameters
KEKB
SuperKEKB
units
LER
HER
Beam energy Eb
3.5 8 4
7.007
GeV
Half crossing angle φ 11
41.5
mrad
# of Bunches N
1584
2500
Horizontal emittance εx 18 24
3.2
5.3 nm
Beta functions at IP
βx*/βy*
1200/5.9
3.2/0.27
2.5/0.30 mm
Beam currents Ib
1.64
1.19
3.6
2.6 A
Vertical Beam Size
sy*
0.94
0.048
0.062 um
Luminosity L
2.1 x 1034
8 x 1035
cm-2s-1
This is comparison table for KEKB and superKEKB
Important changes are smaller Beta function at IP and Beam currents
×20 ×2
2013/9/3
DEPFET pixels as a vertex detector for the Belle II experiment

5. 83 mrad
Effective bunch length
Vertical beam size
KEKB
superKEKB

6. BelleII Design
8m×8m×8m
～1500ton
Magnetic field：
1.5T

7. Vertex detector upgrade
Belle II: Pixels (2 layers) + SVD (4 layers)
Belle: SVD (4 layers)
DSSD strip layers
pixel layers
DEPFET Pixel Mockup
Inner most layer: 2cm (Belle) -> 1.4cm (BelleII)
Outer coverage: 8cm (Belle) -> 13.5cm (BelleII)
Silicon Vertex Detector
Beam pipe inner radius: 10mm (15mm : Belle)

8. Belle II pixel detector
Belle II environment:
- Occupancy : 0.4 hits/mm2/s
- average particle momentum: ~500 MeV
- Radiation tolerance: > 1Mrad/year
- Acceptance:
- Higher vertex resolution -> lower material budget
(~0.21 % X0 for layer)
To achieve 10 mm spatial resolution , pixel size is determined as ~50 x 50 mm 2
(Since Lorentz boost factor on Belle II is 67 % of Belle case, vertex resolution should
be better according to this )

9. DEPFET pixels as a vertex detector for the Belle II experiment
PXD readout
Two layers
R=14 mm 8 ladders,
R = 22mm 12 ladders
1 MB/ev.
100 kB/ev.
256 lines
1st:50 x 55 µm²
2nd:50 x 70 µm²
Event Builder
512 lines
1st:50 x 60 µm²
2nd: 50 x 85 µm²
Data reduction by RoI scheme
80Gbit/s
4 Gbit/s by
Zero suppression
2013/9/3
DEPFET pixels as a vertex detector for the Belle II experiment

10. Performance Beam test by 120 GeV pion beam Position resolution =8mm
S/N=30~40
Total
Cluster=1
Cluster=2
6 mm gate length
4GeV electron beam test of VXD (2 PXD+ 4 SVD)
with mini Belle II DAQ is scheduled in Jan
4 mm gate length
(Baseline)
(gq ~ 1/L 3/2: L is gate length)

11. Injection BG Continuous injection from 2004
The injection BG is vetoed by revolution signal from machine.
(The beam life time is ~600s for LER by Touschek effect)
PXD case : to avoid injection hits
Normal operation:
Signal charge drifts into internal gate
Gated operation
Charges from background drift directly to clear gate

12. BG sources and Radiation tolerance
Radiation environment
4-fermion final state QED process
Touschek effect
Beam-gas interactions
Synchrotron radiation
Radiative Bhabha scattering
Occupancy by each BG source: PXD case
Synchrotron radiation(very preliminary): 0.14 %
(one ladder in horizontal plane: ~1.8%)
Still under investigation

13. BG reduction

14. VXD mechanics

15. Overview of beam pipe designTa Ti Be Ti Ta
All of connection steps have
been tested before production
Inner design: (Machine group)
Outer design: (Belle group)

16. IP mechanics
Beryllium
PXD mount
block
2013/9/3

17. VXD assembly steps
Those procedure will be validated on BEAST assembly

18. Current VXD design Koike BWD PXD service is just mirror image of FWD
VXD mockup

19. VXD mechanics sub-parts preparation
Milestone:
2014 Autumn SVD ladder mount
test start (2015 Jan. start)
2015 Summer VXD assembly
2016 Feb. BEAST (Belle II w/o VXD)
Two sets of Beam pipes, heavy metal shields and CFRP supports
Producing beam pipes:
~2014 Mar. Beam pipe for BEAST (2014 Jul. on global schedule)
~2015 Mar. Beam pipe for physics run (2015 Jul. on global schedule)
Heavy metal shields
~2014 Mar. Shields for BEAST
~2015 Mar. Shields for physics run
End-flange, CFRP support cone, CFRP outer cover
~2014 Mar. one of support parts (for physics run)
~2014 summer second set production (for back-up, BEAST)
Production takes 2 month
Schedule tight
Rough estimation of production period and cost have already done for each products

20. BEAST

21. S.Vahsen (Hawaii)

22. BEAST Setup Design is ongoing. Phase II Phase I
Belle is roll –in position.
No VXD detectors
Phase I
Main task is vacuum scrubbing of beam pipe.
Belle will not roll-in

23. Sensor activities SR measurement by SDD, diamond sensor
Radiation monitor and deciding beam abort
PIN Diode Radiation Dose Monitors
BGO Crystal Luminosity Monitor
Neutron detection by MicroTPC
Thermal neutron detector (He-3 gas chamber)

24. BEAST phase 2 (2016 Feb.) DAQ commissioning
CDC, TOP, ARICH, ECL,KLM (some test ladders of SVD+PXD?)
BG monitoring
Measuring BG at each sub-detector position -> NSM2, EPICS(machine)
Measuring Injection noise (veto timing study)
Setting abort signal to machine for safety VXD operation
Hardwired optical line to machine
Movable mask control study
Measuring each BG component
Optimizing mask control procedure
Cooling test of VXD area (option)

25. Belle/KEKB communication BELLE-1 KEKB control
Belle solenoid field sensor, power outage
Belle_abort
Beam current/ lifetime measurement
BEAM abort
system
Hard-wired
Belle_abort
SVD BG monitor
(PIN,RADFET,RTD)
Injection_inhibit
PIN diode
Injection
system
Inj. eff.
Injection_inhibit
Beam loss collimators
HV control
CDC leak current
CDC current alarm
(“beep sounds”)
CDC
ECL BG level
ECL BG monitor
CATV
CATV display
(oscilloscope monitor)
Injection_veto signals are OR’ed in Belle Elec.Hut and sent to KEKB with hard-wired cables.
Sakai-san’s IOC (Input Output Controller) writes NSM info on a KEKB-EPICS node on Tsukuba-B3
TOF single rate, Injection veto
TRG
Collimator control (BCG)
Data Quality Monitor,
Uehara-monitor,
(NSM)
KEKBlog
(EPICS)
Luminosity,
z-vertex,
Sub-detector BG levels, etc..
Conceptual discussion is just starting now

26. Thank you!

27. Snapshot of VXD mechanics preparation
VXD assembly procedure has almost defined
Beam pipe production (2012 Oct- )
1st pipe for BEAST will be produced by March 2014.
(2nd for physics: ready in March 2015)
All of production tool have prepared and mock-up test finished
Heavy metal part production (2013 Oct-, final 2D design before Dec. )
1st production for BEAST will be done by March.
2nd production for physics run is schedule in next year. Then KEK-MPI group is keep discussing to optimize fine assembly work.
CFRP part production (2013 Oct-)
1st production (for physics) should finished in this fiscal year (takes 3month after order)
End-flange production (Al or SUS)
1st production (for physics) should finished in this fiscal year (takes 2 month)
Need optimization of some function for service (fixing or thermal isolation )
BP+HM+PXD assembly (schedule in 2015 Aug)
Assembly procedure have prepared including service work
Service space
Space requirement by each service have almost finalized.
Discussion of service work procedure is ongoing

28. KEKB-Belle interface

29. KEKB operation using Belle information
Belle information is used by KEKB for
abort the beam(s)
stop/resume injection
optics knob tuning (by Kekb Commissioning Group)
open/close collimator (by Belle Commissioning Group)
etc..

30. BelleKEKB BELLE_ABORT INJECTION_INHIBIT
Issued by SVD hardware/software abort system
Belle solenoid field monitor, power outage
INJECTION_INHIBIT
Issued by SVD software abort system, HV system during ramp. Up
CDC dark current?
“CDC current limiter beep sounds” in KEKB control room
Display in KEKB control room, showing video of oscilloscope monitor
Showing timing structures, rather than trend
TOF single rate, ECL BG monitor (pure CSI), SVD BG monitor(PIN diode)
injection veto signal provided
Information sent from Belle-NSM to KEKBlog:EPICS
Rather slow update (<1Hz , or slower)
z-vertex, luminosity, sub-detector BG levels, etc…

31. KEKBBelle TRG system receives following information from KEKB
RF clock
Revolutional signal
Injection signal for generating injection veto
~50us prior to injection

32. Belle solenoid field sensor, power outage Belle_abort
KEKB control
Belle solenoid field sensor, power outage
Belle_abort
Beam current/ lifetime measurement
BEAM abort
system
Hard-wired
Belle_abort
SVD BG monitor
(PIN,RADFET,RTD)
Injection_inhibit
PIN diode
Injection
system
Inj. eff.
Injection_inhibit
Beam loss collimators
HV control
CDC leak current
CDC current alarm
(“beep sounds”)
CDC
ECL BG level
ECL BG monitor
CATV
CATV display
(oscilloscope monitor)
Injection_veto signals are OR’ed in Belle Elec.Hut and sent to KEKB with hard-wired cables.
Sakai-san’s IOC (Input Output Controller) writes NSM info on a KEKB-EPICS node on Tsukuba-B3
TOF single rate, Injection veto
TRG
Collimator control (BCG)
Data Quality Monitor,
Uehara-monitor,
(NSM)
KEKBlog
(EPICS)
Luminosity,
z-vertex,
Sub-detector BG levels, etc..

33. Info. used for KEKB collimator control
Speed
Where
Who
CDC dark current limiter
Real time
“Beep sound” in KEKB control room
Belle
SVD PIN diodes
CATV display
Collimator loss monitor
Slow
Loss monitor display?
Collimator group
Injection efficiency
Injector system display?
Injector group
Beam lifetime
Main display?
Detector BG level
(SVD, CDC, …)
BCG monitor
BelleKEKBlog
(NSMEPICS)
<~1Hz
At SuperKEKB, all information should be provided to the collimator control algorithm. Those information should be summarized and shown on BCG monitor.

34. What’s new at SuperKEKB/Belle-II
Not only VXD but also TOP might be killed. Loss at |s|~1m is also dangerous.
Beam_abort
Issued by PXD, SVD, IR loss monitor (, and other sub-detectors?)
Injection_inhibit
Collimator control
(Semi-)automatic control algorithm?
“Beep sound”, “oscilloscope monitor” are good for human eye/ear, but we also need to provide necessary information (as digital data) to the algorithm
IR loss distribution might tell us which BG source and which collimator to close

35. Collimator algorithm Optimization of 20~30 parameters Evaluated by:
Asymmetric widths might be needed
Evaluated by:
beam lifetime
IR loss (Should be weighted by loss position)
loss at the final collimator
Required measurements
Beam current, loss monitor at all collimators,
IR loss monitor, sub-detector BG level measurements
Quick enough feedback to perform iteration of collimator adjustments (moving 20um takes ~200ms)
Tsukuba-hall radiation level monitor

36. - For Touschek/Coulomb/RBB BG sensor, above positions are proposed.
(6 or 8 sensors in phi direction for each z position)
- Type of sensor
Need quick feedback for collimator adjustment (espc. z=+-120cm)
PIN diode? Diamond? Specifications?
Thin plastic scintillator?
Neutron sensor?

37. IR Service space

38. Narrowest space between QCS and CDC

39. PXD+SVD service
Latest service space estimation with support structure around VXD is ongoing

41. PXD and SVD docks
SVD dock
PXD dock
SVD and PXD dock space requirements will be taken in CDC design.

43. Space request by cooling pipes