The Construction and Commissioning of the Belle II iTOP Counter - - PowerPoint PPT Presentation

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The Construction and Commissioning of the Belle II iTOP Counter - - PowerPoint PPT Presentation

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The Construction and Commissioning of the Belle II iTOP Counter Boqun Wang on Behalf of Belle II iTOP Group Department of Physics, University of Cincinnati July 31, 2017 DPF 2017, Fermilab, US _ _ Belle II 1 Belle II Experiment Belle

slide-1
SLIDE 1

The Construction and Commissioning of the Belle II iTOP Counter

Boqun Wang

  • n Behalf of Belle II iTOP Group

Department of Physics, University of Cincinnati July 31, 2017 DPF 2017, Fermilab, US

1

Belle II

_ _

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SLIDE 2

Belle II Experiment

2

Nano-beam

  • Belle is a B-factory operated on

Y(4S) resonance energy, collected ~1.0 ab-1 of data

  • Successful physics achievements:

direct CP violation in B decays, D meson mixing, new (X, Y, Z) hadrons, measurement of CKM matrix, etc.

  • Belle II is an upgrade of Belle
  • Target integrated luminosity: ~50

ab-1 and peak luminosity: 8 x 1035 cm-2s-1 (by using nano-beam technology)

  • Physics run: ~ 2018
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SLIDE 3

Principles of iTOP Detector

3

cosθc = 1/nβ π and K have different θc Different hit positions and arrival times of photons top-view side-view

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SLIDE 4

Procurement of Synthetic Fused Silica (Quartz)

  • Two bars, one mirror and one prism per module.
  • Totally 16 modules and 1 spare module.
  • Acceptance test:
  • For 32+ bars: chip inspection, bulk

transmittance, internal surface reflectance.

  • For 16+ mirrors: chip inspection, reflectivity,

position of optical axis, focal point and focal length, spherical aberration, astigmatism

  • For 16+ prisms: chip inspection, transmission,

angle of tilted surface.

  • Surface flatness, surface roughness, parallelism,

perpendicularity and chamfer specs were qualified by vender.

Interferograms of one of the bar surfaces from metrology report 4

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SLIDE 5

QA: Quartz Bar

Bulk Transmission Internal Reflectivity 5

Requirement: Bulk Transmittance: > 98.5 %/m Internal Reflectivity: > 99.9 %

Bulk Transmittance [%/m] Internal Reflectivity [%]

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SLIDE 6

QA: Mirror & Prism

6

6495 6500 6505 6510 6515 6520 6525 S N

  • 2

S N

  • 3

S N

  • 4

S N

  • 6

S N

  • 7

S N

  • 8

S N

  • 1

S N

  • 1

1 S N

  • 1

2 S N

  • 1

5 S N

  • 5

S N

  • 1

3 S N

  • 1

4 S N

  • 1

6 S N

  • 1

7 S N

  • 1

8 S N

  • 1

9 S N

  • 2

Radius [mm] 81 82 83 84 85 86 87 88 89 SN-002 SN-003 SN-004 SN-006 SN-007 SN-008 SN-010 SN-011 SN-012 SN-015 SN-005 SN-013 SN-014 SN-016 SN-017 SN-018 SN-019 SN-020 Reflectivity [%]

Specification Radius: 6500 ± 100 mm Reflectivity: > 85 %

Angle of tilted face: 18.07 ± 0.04 deg ( ± 144 arcsec)

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SLIDE 7

Alignment & Gluing

7

Procedure:

  • 1. adjust surfaces positions using laser

displacement sensor and micrometers

  • 2. adjust surfaces angles using autocollimator

and micrometers

  • 3. repeat steps 1, 2
  • 4. insert shims, tape joint
  • 5. apply epoxy (EPOTEK 301-2) to joint
  • 6. clean excess glue after curing and final

inspection

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SLIDE 8

After Gluing

8

Long time exposure with laser input from prism end Laser scattering on the surface and inside the bar

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SLIDE 9

Quartz Bar Box (QBB) Assembly

9

Use vacuum based lifting jig to move glued optics to QBB assembly table

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SLIDE 10

Front-End Electronics

10 MCP-PMT: 4 x 4 anodes 27.6 x 27.6 mm2 23.0 x 23.0 mm2 active QE requirement: > 24% at peak λ > 28% average PMT module Boardstack

For each iTOP module: 4 boardstacks 8 PMT modules 32 MCP-PMTs 512 readout channels

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SLIDE 11

Installation

11

All module installed by May 2016

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SLIDE 12

Readout System

Transition from Full Waveform to Region of Interest & Feature Extraction

12

IRSX: Waveform sampling ASIC

  • Operated at 2.7GSa/s sampling rate in TOP
  • 12bit resolution
  • ~600MHz analog bandwidth
  • 32768 samples storage depth
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SLIDE 13

Global Cosmic Ray Test

13

  • Global cosmic ray data taking

started since July 3, 2017

  • Outer detectors including TOP

joined the data taking

  • Rough number of photon hits

per events agrees with MC

  • More detailed analyses are
  • ngoing

slot5 Entries 32505 Mean 24.94 Std Dev 14.81

10 20 30 40 50 60 70 80 90 100 200 400 600 800 1000 1200

slot5 Entries 32505 Mean 24.94 Std Dev 14.81

slot 5

Very rough result

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SLIDE 14

More Ongoing Work

Channel by Channel Time Alignment Understanding laser data 14 Laser fibers installed for each module

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SLIDE 15

Summary

15

  • iTOP is a new type of ring-image Cherenkov detector for Belle II. It

provides particle identification ability in the barrel region.

  • The construction of all modules took ~18 months. They’re all installed to

Belle II and cabled, being tested.

  • The global cosmic ray data taking with other detectors started on July 3,
  • 2017. The analysis of cosmic data is ongoing.
  • Excellent Kaon identification efficiency of 93% at a rather low 4% pion

misidentification probability (88%, 9% respectively at Belle) over the wide momentum range is expected (see backup slides).

  • First collision data of phase 2 will be taken early 2018.
  • Belle II will take physics data with all sub-detectors installed in late 2018.
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SLIDE 16

Backup

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SLIDE 17

Expected Performance

17

  • Simulation performed in the Belle II software framework
  • Excellent K identification efficiency (small pi misidentification

probability) over wide momentum range

  • Belle II: 93% (4%)
  • Belle: 88% (9%)

]

2

Momentum [GeV/c 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 Efficiency 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

kaons pions

)>0 π TOP L(K)-L(

]

2

Momentum [GeV/c 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 Efficiency 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

kaons pions

)>0 π TOP+ARICH+dE/dx L(K)-L(

0.3

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SLIDE 18

Readout System

Improve low PMT gain: use template fit to waveform data

MCP-PMT Life Extension