1. Belle II status and plans
Christoph Schwanda Institute of High Energy Physics Austrian Academy of Sciences
June 11-15, 2012, Prague, Czech Republic

2. Belle II physics: Searching physics beyond the SM using indirect probes at high energy
Flavor changing neutral currents
(virtual contributions of new, heavy particles in loops)
Precision test of CKM unitarity (search for new CP violating phases)
???
Search for the charged Higgs boson in B  t nu and B  D(*) t nu decays
Search for lepton flavor violation in B and tau decays (SUSY breaking mechanism, right-handed neutrino couplings)
How does the Belle II New Physics reach compare to present facilities (high pT searches at CMS and ATLAS, flavor physics at LHCb)?

3. Search for the charged Higgs boson with B+ ® t+ n
Standard model
Type II Higgs doublet models H-
W.S.Hou, PRD 48, 2342 (1993)
Belle II 5s H+ discovery (50/ab)
14 TeV ATLAS 5s H+ discovery (30/fb)
arXiv: [hep-ex]

4. t lepton flavor violation
t ® lg
SUSY + seesaw
Large LFV
t ® 3l, lh
Neutral Higgs mediated decay
Important when MSUSY >> EW scale
experimental sensivity
mode
Br(t ® mg)
Br(t ® 3l)
mSUGRA + seesaw
10-7
10-9
SUSY + SO(10)
10-8
10-10
SM + seesaw
Non-universal Z’
SUSY + Higgs
The full range of t LFV modes is only accessible at a Super B factory!

5. Belle II physics sensitivity [arXiv:1002.5012[hep-ex]]

6. Building on the success of the KEK B factory…
… accelerator / detector are constructed by upgrading the present facilities

7. SuperKEKB machine parameters
units
LER
HER
Beam energy Eb
3.5 8 4 7
GeV
Half crossing angle φ 11
41.5
mrad
Horizontal emittance εx 18 24
3.2
5.0 nm
Emittance ratio κ
0.88
0.66
0.27
0.25 %
Beta functions at IP
βx*/βy*
1200/5.9
32/0.27
25/0.31 mm
Beam currents Ib
1.64
1.19
3.60
2.60 A
beam-beam parameter ξy
0.129
0.090
0.0886
0.0830
Luminosity L
2.1 x 1034
8 x 1035
cm-2s-1 -
sx~10mm,sy~60nm
Small beam size (“nano-beam”) and higher currents to increase luminosity
Smaller boost to improve LER lifetime e-
60nm
10mm e+

8. From KEKB to SuperKEKB Belle II luminosity goal:
Colliding bunches
New IR
e- 2.6 A
New superconducting /permanent final focusing
quads near the IP
New beam pipe
& bellows
e+ 3.6 A
Belle II luminosity goal:
50 times the Belle dataset
Replace short dipoles with longer ones (LER)
Add / modify RF systems for higher beam current
Low emittance positrons to inject
Positron source
Redesign the lattices of HER & LER to squeeze the emittance
Damping ring
New positron target / capture section
TiN-coated beam pipe with antechambers
Low emittance gun
Low emittance electrons to inject

9. The formal start of the project…
Nov 18, 2011: SuperKEKB groundbreaking
The formal start of the project…

10. Feb 7, 2012: Installation of the first SuperKEKB dipole magnet
The main purpose of this installation was to debug the tools and methods for installing the 4 m LER dipole over the 6 m HER dipole (remain in place).
Installed 2 dipole magnets. The rest of the LER dipoles are scheduled to be installed this year.

11. Detector upgrade Critical issues at L= 8×1035/cm2/s:
Higher background (×10-20)
radiation damage and higher occupancy
fake hits and pile-up noise in EM calorimeter
Higher event rates (×10)
higher rate trigger (L1 trigg. 0.5→30 kHz)
DAQ, computing
Target:
Maintain or improve over Belle I data quality in the high background/ high rate environment II

12. The Belle II detector
CsI(Tl) EM calorimeter: waveform sampling electronics, pure CsI for endcaps
RPC μ & KL counter: scintillator + Si-PM for end-caps
Time-of-Flight, Aerogel Cherenkov Counter → Time-of-Propagation (barrel), prox. focusing Aerogel RICH (forward)
4 layers DS Si vertex detector → 2 layers PXD (DEPFET) + 4 layers DSSD
Central Drift Chamber: smaller cell size, long lever arm

13. Inner tracking (PXD, SVD)
PXD + SVD in Belle II (in Belle only strip layers )
Pixels in novel DEPFET technology: thin (75μm) sensors
give little multiple scattering, close to the IR
Fast strip readout with APV25 chip (50 ns), low occupancy
Improved IP resolution and low momentum tracking (pT < 100MeV), 30% larger eff. of Ks→π+π- with vertex info
DSSD strip layers
pixel layers
Belle
Belle II
σ (μm)
rφ IP resolution
z IP resolution
pβsin5/2θ[GeV/c]
pβsin3/2θ[GeV/c]
Mechanical mockup of pixel detector DEPFET sensor

14. Central drift chamber (CDC)
Extended outer radius, longer lever arm ® improved momentum and dE/dx resolutions
Larger inner radius, smaller cells near beampipe ® more background-hard
Belle
Belle II
inner most sense wire
r=88mm
r=168mm
outer most sense wire
r=863mm
r=1111.4mm
Number of layers 50 56
Total sense wires
8400
14336
Gas
He:C2H6
sense wire
W(Φ30μm)
field wire
Al(Φ120μm)
Belle
normal cell
10~20 mm
18 mm
10 mm
6~8 mm
small cell
Belle II

15. Particle Identification (TOP, ARICH)
„focusing”
aerogel radiator
Hamamatsu HAPD
+ new ASIC
Cherenkov photon
200mm
n~1.05
Endcap PID: Aerogel RICH
Barrel PID: Time of Propagation Counter
Quartz radiator
Focusing mirror
Small expansion block
Hamamatsu MCP-PMT (measure t, x and y)
TOP: reconstructs Cherenkov rings using 3D info from PMTs: x,y and time of photon propagation (40 ps resolution)
ARICH: measures Cherenkov angle. Inhomogeneous aerogel radiator to improve photon resolution
Improved K/π separation in wide momentum range
Quartz radiator
RICH test beam setup
p=3GeV/c2

16. KL and muon detection
End-caps upgrade: Resistive Plate Chambers ® scintillator- based detector
20x background increase in RPCs (worse shielding of neutrons along beams)
Scintillators + SiPM: better beam-background tolerance
Barrel KLM: some RPC layers may be replaced as background increases with luminosity
Iron plate
Aluminium frame
x-strip plane
y-strip plane
Endcap KLM sector

17. The Belle II collaboration
~400 members with ~150 participants from Europe

18. Schedule – beam commissioning starts in JFY 2014
Goal of Belle II/SuperKEKB
Integrated luminosity
(ab-1)
We will reach 50 ab-1
in 2022
9 months/year
20 days/month
Commissioning starts in JFY 2014.
Peak luminosity
(cm-2s-1)
Shutdown
for upgrade
Year

19. Summary
The KEK B factory (KEKB and Belle) undergoes a major upgrade to become a Super B factory (SuperKEKB and Belle II), both accelerator and detector are on schedule for a start in JFY 2014
The upgrade will result in 40x larger event rates, the luminosity goal is 50/ab by 2022
This data sample will allow to probe physics beyond the Standard Model in B and D meson and t lepton decays, these results will complement the searches at hadron colliders
References:
Belle II Technical Design Report [arXiv: [physics.ins-det]]
Belle II Physics [arXiv: [hep-ex]]

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