1. Flavour Physics Belle II experiment at SuperKEKB Tsukuba, Japan
Upgrade of KEKB, 40x luminosity: 8 x 1035 cm-2s-1
First beam: February 2016
First Physics: End of 2018
Belle II Collaboration: 100 Institutions, ~600 physicists
Major upgrade of Belle (pixel detector, tracking, TOP)
MPP’s contribution: DEPFET pixel detector
Director: Allen Caldwell,
Group leader: Hans-Günther Moser
+ 2 senior, 3 postdoc, ~3 PhD, ~ master
Nano Beams: 10µm x 60nm
Increase beam current (x2)
Reduce asymmetry (boost)
KEB:
bg = (8 GeV, 3.5 GeV)
SuperKEKB:
bg = 0.28 (7 GeV, 4 GeV)

2. Physics at B-factories
Main Motivation: CP-violation
Measurements of CKM matrix elements and angles of the unitarity triangle
Measurements of rare decays (e.g., Btn, Dtn)
Others (t,..)
Motivation for upgrade: Test Standard Model (SM) as precisely as possible
=> Overconstrain unitarity triangle
=> Look for deviations from SM
=> Increase sensitivity for rare decays
=> Indirect discovery of New Physics via loops (need high precision)
Nobel Prize 2008: Kobayashi & Maskawa
Confirmation of CKM theory by BaBar & Belle
<= Babar/Belle 2015
(~1.5 ab-1)
With 50 ab-1 (same central values)
With 50 ab-1 =>

3. Time dependent measurements of CP violation
U(4S) decaying into B0B0 pairs
Oscillation induced CP violation as function of decay time difference
Boosted CMS to measure decay time by decay length reconstruction
Bphys
Btag
Dt probability parametrization

4. Vertexing @ Belle II σ [µm] Higher background ( 10-20)
Higher event rate ( 10)
Improvements to the tracking detectors:
new drift chamber
improved SVD (DSSD with fast readout)
2 layers of DEPFET pixel sensors
Critical issues at L= 8 x 1035/cm2/sec:
Significant improvement in z-vertex resolution
PXD+SVD
15mm
30mm
Belle
Belle II
pbsin(q) [GeV/c]
0.4
2.0
0.8
1.2
1.6
100 20 50
σ [µm]
PXD

5. DEPFET Sensors Development of MPP and MPI Semiconductor lab
(now independent)
Active pixel sensor
20 µs frame readout
Gating
75 µm sensor thickness
Including frame & ASICs:
0.21 % X0
30 wafers produced
Prototypes completed
High yield >50% for 99% good pixels

6. Support & Assembly MPP Tasks: Mechanical support Kapton attachment
Gluing of two modules to a ladder
Assembly of ladder on support

7. CO2 Cooling PXD and SVD will be cooled by a 2-phase CO2 .
Copy of the cooling plant used for ATLAS IBL: 3 kW cooling power at -35oC
Chiller
Pump unit
Accumulator
Control Cabinet
Components were manufactured and tested in the MPP workshop
Plant completed & commissioned, shipment to KEK in August 2016

8. Services & Installation
Service routing and interface boxes for the PXD:
Power and data cables for the 40 PXD modules
CO2 transfer lines for cooling of PXD and SVD
VXD installation procedure:
Decouples VXD installation from QCS magnets.
Remote connection of the beam pipe (by DESY)

9. Beam Test of Sensors
April 2016: combined PXD and VXD beam test at DESY
Inner and outer layer modules mounted on a cooling block.
Completed by 4 SVD layers and a beam telescope.
Cd source
14 µm (pitch:50 µm)
8 µm (pitch 60 µm)
Position resolution of an inner module for tracks at normal incidence measured at a beam test.
Hit map showing beam spot

10. Belle Analysis B0 → r+r-
Precision improvement with respect to the previously published result is factor 2
(Most precise measurement of B0 → r+r-), PRD 93, (2016)
Increase of data, simultaneous extraction of observables and analysis optimization for high signal yield.
Input for measurements of angle f2 of the Unitarity Triangle
Isospin analysis: f2= (93.7 ± 10.6)°
S(U3) flavor analysis: f2= (93.7 ± 10.6)°
Isospin
SU3

11. Belle Analysis: B0→ w Ks This decay proceeds via loop diagram
First evidence for CP violation in B0 → ωK0S, PRD 90, (2014)
It is possibly affected by new particles in various extension of the Standard Model
Sensitive to sin(2f1)
Simultaneous analysis of B0 → ωK0S and B+ → ωK+
B(B0 →ωK0) = (4.5 ± 0.4 (stat) ± 0.3 (syst)) x 10-6
B(B+ →ωK+) = (6.8 ± 0.4 (stat) ± 0.4 (syst)) x 10-6
A(B0 →ωK0S) = ± 0.19(stat) ± 0.05(syst)
S(B0 →ωK0S) = ± 0.32(stat) ± 0.05(syst)
A(B+ →ωK+) = ± 0.04(stat) ± 0.01(syst)
Further published results:
PRD 88, (2013) B0 → p+p- : Branching ration and time dependent CP asymmetry
PRD 89, (2014) B0→ r0r0: Branching ration and fraction of longitudinal polarization
PRD 93, (R) (2016) First measurement of B(B0 → y(2S) p0)

12. All tracks used apart from the ones from Ks
Physics Preparation
L. Li Gioi
Kinematic fit: J/y → m m
Vertexing
Kinematic vertex fits
Kfit : for decay side
RAVE for tag side fit (inclusive) (from CMS)
Belle II
Shift = 2.0 mm
Resolution = 22 mm
Belle
Shift = 0.2 mm
Resolution = 63 mm
Tag side vertex fit
Belle II
Shift = 1.0 mm
Resolution = 63 mm
All tracks used apart from the ones from Ks
Belle
Shift = 29 mm
Resolution = 89 mm

13. Belle II Physics Preparation
Flavor tagging
B-flavor tagging determines if a B meson is a B0 or anti-B0
It is based on trained multivariate methods
Efficiency: 35 %
Sensibly better than Belle: 29 %
Efficiency = 35 %
Belle = 29 %
B0tag B0tag

14. Schedule IR 6 Oct 2015 February 2016: first beam in SuperKEKB
February – June commissioning and BEAST I
beam currents of ~ 1A reached
December Belle II roll in
June 2017 – April. 2018: SuperKEKB commissioning
(with Quads & Beast II, no VXD)
October 2017: PXD at KEK, integration with SVD (VXD)
May –Sept installation of VXD
October physics run with full Belle II
IR 6 Oct 2015
IR and Belle II in park position, Oct 2015
Signals from two injected bunches by CLAWS
(talk by F. Simon)

15. Summary Main activities at MPP for Belle/Belle II: Belle analysis
Belle II physics preparation
Vertexing, tracking, flavour tagging
Contribution to computing
Slow control software (EPICs)
(Component) Database
Design and construction of PXD system components:
Kapton tapes (Design)
CO2 cooling plant
Module & ladder assembly and tooling
Module testing and characterization
Ladder support structure and assembly
General work for services layout
Integration procedure (AIM)
Schedule
Series assembly of modules & ladders: 2016/2017
Shipment of PXD to KEK: October 2017
First physics data: October 2018