Production of ATLAS ITk- Japan contributions 29 March 2021, TCHoU Workshop
Shigeki Hirose (U. Tsukuba)

■ ATLAS experiment at LHC
44 m

25 m

Large Hadron Collider (LHC)• Circumference = 27 km• 𝑝𝑝 collision at 𝑠 = 13 TeV• Bunch per 25 ns• ATLAS detector– Targets high-𝑝T objects from decays of heavy particles– Severe environment of 𝑝𝑝 collisions due to QCD→ Track finding performance of ID is essential for any physics analyses

29-Mar-2021

Shigeki Hirose, University of Tsukuba TCHoU Workshop

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■ Upgrades for HL-LHCToday• High-luminosity LHC from 2027 to 2038
– Collect ×10 more data with ×3 higher instantaneous luminosity– Diverse physics opportunities; Higgs self coupling, SM precision tests,
new heavy particle searches such as SUSY, LQ, ...
New muon chambers inthe inner barrel region
Our contributions
All-silicon inner tracker(pixel + strip)

29-Mar-2021

High Granularity Timing
Detector with LGAD
(𝜎𝑡 ~50 ps)

Shigeki Hirose, University of Tsukuba TCHoU Workshop

Better performancetrigger DAQ &electronics systems

3/13

■ ATLAS Inner Tracker (ITk)Strip
Gas detector
StripPixelPixel
ATLAS-TDR-030 (2017)

JINST 3 S08003 (2008)• The ID needs to be replaced before HL-LHC– Tolerance to higher particle density and radiation fluences
Current ID

Sensor typeITkn+-in-n (pixel)

n+-in-pp+-in-n (strip)
Coverage|η| < 2.5
|η| < 4.0
Thickness (innermost)
200 μm
100 μmPixel size (innermost) 50×250 μm2 25×100 μm2
Surface~60 m2~180 m2# of channels
86M
5060M

• Very challenging upgrade project! Collab. with 65 institutes– Stable production & solid QC/QA procedures are essential
29-Mar-2021

Shigeki Hirose, University of Tsukuba TCHoU Workshop

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■ Strip sensor QC/QA
Barrel stave• 20,800 sensors are going to be
produced since July 2021
– Sensor QC/QA is important!

~10 cm(1280 strips)• QC: inspection for all main sensors– Shared with Canada, UK, US and JapanJapan• Visual inspection• Metrology• Strip test
All done at HPK

US (Santa Cruz)• Thickness• IV stability

Moduleproduction sites* In charge of 6,000 sensors• QA: performance monitoring after irradiation– Irradiate protons (Japan & UK), neutrons (Slovenia) or gammas (Czechia)
70 MeV proton beam at CYRIC, Tohoku U– Dedicated “QA pieces” are sampled for every ~40 sensors
29-Mar-2021

Shigeki Hirose, University of Tsukuba TCHoU Workshop

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■ QC machine at HPK• We established an automated QC machine at HPK– Used for VI and metrology (strip tests are done with HPK’s equipment)
Camera (Nikon D5600)

Auto-focus(for metrology)

••

Lens
x2 for VC
x10 for metrology

XY stage

29-Mar-2021

Shigeki Hirose, University of Tsukuba TCHoU Workshop

6/13■ Results from pre-production

K. Saito, JPS Fall 2020 [14pSF-07]

75.5 μm• Sensor photo for visual inspection– Possible to catch images of very fine objects (like strip defects)• Metrology– Bowing is at most ~100 μm (requirement = 200 μm)• QC flows were tested during sensor pre-production– 318 wafers were inspected for just three days!
29-Mar-2021

Shigeki Hirose, University of Tsukuba TCHoU Workshop

7/13

■ Sensor QA

Test chip (TC)
Bias resistance
8×8 mm2 mini diode

IV/CVInterstrip
characteristics

Punch-throughprotection
Coupling capacitance

Oxidethickness

Mini sensor(1×1 cm2)
for CCE• Inspection for basic silicon properties using QA pieces– Test chip: various structures dedicated to every measurement– Mini diode: for IV/CV characteristics with the simple structure– Mini sensor: 1×1 cm2 strip sensor for charge collection efficiency• Irrad. up to 1.6×1015 neq/cm2  1.5×[total fluence at HL-LHC]
29-Mar-2021

Shigeki Hirose, University of Tsukuba TCHoU Workshop

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■ Irradiation tests
Samples fixed ona G-10 plateProton
beamUnirrad.

Irrad.
Requirement (at 500 V)• ~40 samples were irradiated at CYRIC in 2020
K. Saito, JPS Spring 2021 [13aT3-02]• Measurement system established at KEK– Systematic measurements can be performed for test chip (4 h/sample)
and mini sensors (1.5 h/sample)• Overall good performance was confirmed

T. Ishii, JPS Spring 2021 [13aT3-03]– Issues observed during the pre-production QA were fed-back to theproduction as well as improvements on the measurement method
29-Mar-2021

Shigeki Hirose, University of Tsukuba TCHoU Workshop

9/13

■ Pixel detector production• Japan is responsible for producing 2,000 modules
Flip-chip

SensorModule assembly

Inspection

Readout test

Flex. circuit

ASICs@ Qualified vendors@ REPIC / KEK• Qualification for flip-chip vendors has been recently completed– A Japanese vender was selected (together with a few other venders)T. Kumakura, JPS Spring 2021 [12pT3-07]
K. Tsuri, JPS Spring 2021 [12pT3-08]• Production for a module needs to be done within 4 days andwith a precision of O(10 μm)– Well-defined procedures + full validation with dummy / pre-producedmodules are mandatory
29-Mar-2021

Shigeki Hirose, University of Tsukuba TCHoU Workshop

10/13

■ Module production

StencilSensor + ASIC D. Kobayashi, JPS Fall 2020
[14pSF-06]

Well controlled
amount of glue

Moduleassembled!
(after wirebonding...)• Assembly is now being done at a clean room of KEK• Procedure has been well developed over years– Realised the position precision of ±50 μm and bowing within ±25 μm– Japan is the first qualified group as the module assembly site!

• About 10 modules have been already assembled withprototype sensors + ASICs
29-Mar-2021Shigeki Hirose, University of Tsukuba TCHoU Workshop

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■ Readout test

S. Fujii, JPS Spring 2021 [12pT3-13]

Stability of leakage current

0.2 nA

8 hours

SMD parts onflex are visible𝑥• Readout test with X-rays– A dedicated X-ray irradiation system has been installed– Stopped by materials but at least ~10 hits/pixel can beexpected in 5 mins.

• Burn-in: stability test for 8 hours is required– Established the method at -10℃ → To be -15℃
29-Mar-2021

Shigeki Hirose, University of Tsukuba TCHoU Workshop

12/13■ Summary• ITk is a key for successful physics at HL-LHC ATLAS– Huge all-silicon tracker with 180 m2• Japan group is strongly contributing to the project– Strip: playing a key role in the sensor QC/QA; ready toentre the production phase from July (for 3.8 years)– Pixel: responsible for the entire production flow; preproduction will start this year
→ Also planning to (re-)ramp up activities at CERN for
preparation of module installation– U. Tsukuba is one of the key players (5 students + 2 staffs)• The entire ITk will be ready by the middle of 2026
– Be prepared for start of the HL-LHC operation in 2027!
29-Mar-2021

Shigeki Hirose, University of Tsukuba TCHoU Workshop

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