Belle II Status

Toru Iijima

Belle II spokesman (2019.6 - )Nagoya University

July 8, 2019
The 23rd KEKB Accelerator Review Committee

Note: physics-related plots are internal and will be updated for LP2019

2New Belle II Management• Spokesperson: Toru Iijima• Deputy spokes: Karim Trabelsi• Assist the spokesperson in performing tasks

that require the spokesperson’s attention orauthority.

• Project Manager: Yutaka Ushiroda• Financial Officer: Shoji Uno• IB chair/deputy: Gagan Mohanty / Takeo Higuchi(newly elected by IB)• EB chair: Michael Roney• Physics Coordinator: Alessandro Gaz (newlyelected by IB)• TB chair/deputy: Peter Krizan / Carlos Marinas

We thank Tom Browder for
his years of leadership !

Communication between
SuperKEKB and Belle II• BCG (Belle II Commissioning Group) shift• 1 shifter in the ACC control room
• Several Belle II people (incl. Run coordinator, BCG) attend the
KCG meeting.

• Belle II Monday meeting (every week)• Invite SuperKEKB people to present status• EB meeting invites Tobiyama-san and some SuperKEKB people.
• MDI (Machine Detector Interface) meeting to discuss mitigationof machine background.

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Belle II Collaboration• 984 active members• 333 graduate students• 115 institutes(B2MM on June 20, 2019)• 26 countries

45Phase 2 in a nut shell
1. Achieve a machine luminosity of O(10^34/cm^2/sec) andsee a clear path to further improvement.
2. Examine the VXD background to verify that we caninstall the VXD *at the start of phase 3* and thenoperate it for the initial first few years of phase 3.

First collision(April 26, 2018)

Specific luminosity improved

New collision scheme Initial data of ~500pb-1confirmed to work
recorded, and particle
rediscoveries made.
!", !±Belle IIPreliminary

Installed detectors worked, although somefixes were necessary.

Preparation for Phase 3Vertex detector (instead of background monitors) is installed
Nov. 27, 2018

ARICH cooling reinforced

2018/9/5

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Start of the Phase 3 Run

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Status of physics run
Recovery fromQCS quench
Normal run resumed-60 MeV run
QCS PS trouble#bunch: 789 → 1576
HER continuous injection
LER continuous injection
Data taking in platinum week
Recovery from fire accident
1st collision

8Belle II is working “basically”
PXDDAQ

9KLM

PXD before May 28

SVD

TRG

CDCTOPECL

A-RICH10But, not always …
YSUB
PXD

SALS !

CDC ttlost/b2ldown
TOP BUSYECL BUSYtsoltt
/Y
SUB
TRG

HV TRIP !
Belle II is still in learning stage, and need get more matured.
• More debugging• More sustainable operation (slow control, HLT, …)• More people at Gemba• Data quality assurance• Documentation
Yet a child ?

PXD (before May 28)

Carsten Niebuhr

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SVD in Phase 3• SVD operation has been very smoothand stable. No major issue has beenencountered.

Cluster efficiency
fraction of times a cluster is foundwithin ±0.5mm from extrapolation• Excellent performance: cluster efficiency
above 99% in L3-L6 and on n/p- side.

• Occupancy• Current offline occupancy is ⪍ 0.3%

• Extrapolation: 1.6% (2020), 2.6% (2021)•limit for good tracking (2-3%)
Online data rate will be also OK up to2021 (w/ possible improvements forbandwidth limitations)

Cluster position resolution

CDC in Phase 3J. Kumar et al (CMU)
verified that dE/dx isunchanged

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ARICH in Phase 3• ARICH operation is stable.
✓ No major problems in DAQ and robust
against beam background.
✓ No major concerns in the near future.
• ARICH data is generally has better quality
compared to Phase 2 (full operation, better
threshold settings etc.).
✓ #(photons) is 20% larger than in Phase 2,
consistent with MC.
• Alignment and calibration are on-going.

S. Nishida, S. Korpar et al.

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Charged Hadron ID• Charged hadron ID is made by combining information from CDC(dE/dx), TOP and ARICH.
• Significant improvement in Data/MC agreement in recent calibrated Phase 3 data.
K eff. vs π fake w/ K/π tracks from D* decays
Combined PID

Need more studies to understand difference
between the two Φ angle regions(conventional vs. other types of MCP-PMTs)

TOP only15

ECL• Electromagnetic Calorimeter (ECL) works stably. All counters are working• Pile-up noise is monitored by the width of pedestals.
• No extra noise from continuous injection with a proper veto applied.
• Pile-up noise still large in the barrel and backward escape regions.

• ECL provides accurate luminosity•measurements in real time.
Accuracy of the online luminosity
measurements is estimated to be
1.87%.

Loff/Lon

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KLM (MuID)

Need a sample oftagged muons inthe lower
momentum region
such as J/ψ’s inhadronic events

A. Martini etal (Roma Tre)17

An issue (software?)in the forward endcap.

Beam background issues

Listen to Nakayama-san’s talk !

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Recent PXD issues (I)

Carsten Niebuhr

19Recent PXD issues (II)SR background was observed during βy* = 2mm operation

Carsten Niebuhr

20Physics Targets at LP2019

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Preliminary!

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Guilia Casarosa, Gaetano de Marino

Preliaryinm!

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Toward 2020, 2021
Competition with LHCb will be tough !

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Toward 2020, 2021
Competition with LHCb will be tough !

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Toward 2020, 2021
Competition with LHCb will be tough !

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Toward 2020, 2021
Competition with LHCb will be tough !

Before they resume in 2021, we want
• demonstrate performance (quality) of Belle II ⪆ Belle• catch up LHCb (and also Belle, BaBar)

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Toward 2020, 2021
Competition with LHCb will be tough !

Before they resume in 2021, we want
• demonstrate performance (quality) of Belle II ⪆ Belle• catch up LHCb (and also Belle, BaBar)

We want 200 - 400 fb-1 by 2020 summer

24Luminosity Projection

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Shown by Morita-sanat B2GM

Note: L=1.2x1034cm-2s-1@ βy* = 2mm
already (w/o Belle II)

Assumption• No machine study time for future beam development

Can we have moreaggressive plan ?

• Detector background independent of βy*• x2 improvement of CDC current limit• No current limit for protecting detectorNeed continuous efforts to reduce background on Belle II side.

Belle II work in 2020 or 2021

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• Installation of full PXD• Replacement of TOP “conventional” MCP-PMT• Required time for replacement:• 4 months for TOP MCP-PMT replacement alone.
• 9 months for PXD replacement and PXD+TOP MCP-PMT• We preparer detectors as early as possible, and install them as late as possible.
• The earliest possible shutdown in 2021 spring. Decision ti be made in June 2020.
eff(π) / eff0(π) for B→Kπ

QE / QE0x ~0.95 2020 summerx ~0.7 2021 summer

Summary• Belle II has started taking data with full detector (except for part ofPXD) since March 25, 2019.

• Belle II runs smoothly, although we still need improve for more stableand sustainable running.

• Belle II has accumulated >6 fb-1, which will produce some first physicspapers.

• It is essential to improve detector background (CDC and TOP) to ramp
up the peak and integrated luminosity.

• Protection of Belle II against QCS quench etc. is also important.
Tough competition with LHCb

• We are happy to discuss with SuperKEKB colleagues how to optimize
the future run plan.

Backup!28

Belle II work in summer shutdown

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