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arxiv: 2605.23401 · v1 · pith:XBS2OIPHnew · submitted 2026-05-22 · ⚛️ physics.ins-det · hep-ex

Development of a system for testing full-size CMS LGAD sensors

Kyungmin Lee , Hoyong Jeong , Junho Kim , Seokhyeon Lee , Jaebak Kim , Jae Hyeok Yoo This is my paper

Pith reviewed 2026-05-25 02:59 UTC · model grok-4.3

classification ⚛️ physics.ins-det hep-ex
keywords LGAD sensorsprobe card systemautomated characterizationI-V measurementsC-V measurementsswitching matrixpixelated sensorsquality control
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The pith

A modular probe card system automates electrical characterization of 16x16 LGAD sensor arrays while adding less than 1 nA of leakage current.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper describes the creation of an automated probe card system for characterizing pixelated LGAD sensors used in particle physics experiments. Conventional manual techniques become inadequate as the number of sensors grows and geometries vary, so the authors built a probe card with a switching board that selects any pixel or group for current-voltage and capacitance-voltage measurements. Tests on a 16 by 16 array complete a row-wise scan in about 20 minutes and a full pixel-by-pixel scan in about 340 minutes. The switching matrix adds less than 1 nA of leakage even in the worst-case setup, which stays small relative to normal LGAD pixel leakage. The modular design supports single-pixel, grouped, row-wise, and inter-pixel modes for practical large-scale quality control.

Core claim

The authors developed a modular probe card system consisting of a probe card, switching board, precision measurement instruments, and control software that supports arbitrary pixel selection and flexible measurement configurations on LGAD sensors. Its performance is demonstrated through I-V and C-V measurements of a 16x16 LGAD array. A rapid row-wise I-V scan of the full array completes in approximately 20 minutes, while a pixel-by-pixel I-V scan from 0 to 300 V with 1 V step requires about 340 minutes. The switching matrix introduces less than 1 nA of leakage current even in a conservative worst-case configuration, remaining small compared with the leakage current of a normal LGAD pixel.

What carries the argument

The switching matrix on the board that enables arbitrary pixel selection and multiple measurement modes while contributing less than 1 nA leakage current.

If this is right

  • The system can perform I-V and C-V measurements in single-pixel, grouped, row-wise, and inter-pixel configurations.
  • A full 16x16 array row-wise I-V scan completes in about 20 minutes.
  • A detailed pixel-by-pixel I-V scan from 0 to 300 V with 1 V steps takes about 340 minutes.
  • The modular architecture supports large-scale LGAD sensor quality control and distributed testing environments.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The low added leakage suggests the system could support precision timing studies on LGADs without introducing measurable bias in electrical properties.
  • Similar switching-matrix designs might adapt to automated testing of other pixelated silicon sensors in high-energy physics.
  • Further scaling to arrays larger than 16x16 would require checking whether the matrix leakage stays proportionally small.

Load-bearing premise

The probe card and switching board do not introduce measurement artifacts, damage sensors, or alter their electrical properties beyond the stated leakage contribution during repeated contacts and scans.

What would settle it

Direct comparison of I-V curves on the same LGAD pixel measured manually versus routed through the switching matrix, checking whether the curves match within the expected variation.

read the original abstract

Low-Gain Avalanche Diode (LGAD) sensors, offering timing resolutions of the order of tens of picoseconds, are being widely adopted in particle physics experiments and related applications. As these applications scale to large numbers of sensors with varying pixel geometries, conventional manual characterization techniques become inadequate for large-scale quality control. We present a modular probe card system for automated electrical characterization of pixelated LGAD sensors, consisting of a probe card, a switching board, precision measurement instruments, and control software. The system supports arbitrary pixel selection and flexible measurement config16 urations, including single-pixel, grouped, row-wise, and inter-pixel measurements. Its performance is demonstrated through current-voltage (I-V) and capacitance-voltage (C-V) measurements of a $16 \times 16$ LGAD array. A rapid row-wise current-voltage (I-V) scan of the full array is completed in approximately 20 minutes, while a pixel-by-pixel current-voltage (I-V) scan from 0 to 300 V with a 1 V step requires about 340 minutes. The switching matrix introduces less than 1 nA of leakage current even in a conservative worst-case configuration, remaining small compared with the leakage current of a normal LGAD pixel. The modular architecture and automation capability make the system a practical and scalable solution for large-scale LGAD sensor quality control and distributed testing environments.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

1 major / 3 minor

Summary. The manuscript describes the development of a modular probe-card and switching-matrix system for automated I-V and C-V characterization of 16×16 LGAD sensor arrays. It supports arbitrary pixel selection and multiple modes (single-pixel, grouped, row-wise, inter-pixel), reports scan times of ~20 min for full-array row-wise I-V and ~340 min for pixel-by-pixel I-V (0–300 V, 1 V steps), and claims the switching matrix adds <1 nA leakage even in a conservative worst-case configuration, remaining negligible relative to typical LGAD pixel leakage.

Significance. If the leakage and timing performance claims are substantiated with data, the work provides a practical, scalable tool for large-scale LGAD quality control needed by CMS and similar experiments. The modular architecture and automation address the inadequacy of manual methods for high-volume sensor testing and could support distributed testing setups.

major comments (1)
  1. [Abstract] Abstract: The key claim that the switching matrix introduces less than 1 nA of leakage current in a conservative worst-case configuration is presented without error bars, raw data, validation against known standards, or a description of the exact measurement procedure and configuration used. This is load-bearing for the central performance assertion and leaves open the possibility of unaccounted artifacts from the probe card or switching board.
minor comments (3)
  1. [Abstract] Abstract contains an obvious typographical error: 'flexible measurement config16 urations' should read 'configurations'.
  2. The title refers to 'full-size CMS LGAD sensors' while the reported work uses a 16×16 array; the manuscript should clarify whether the tested array is representative of full-size sensors or note any scaling considerations.
  3. No comparison is provided to existing commercial or laboratory probe systems for LGAD testing, which would help contextualize the reported scan times and leakage performance.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their review and constructive comment. We address the major point below and will revise the manuscript accordingly.

read point-by-point responses

  1. Referee: [Abstract] Abstract: The key claim that the switching matrix introduces less than 1 nA of leakage current in a conservative worst-case configuration is presented without error bars, raw data, validation against known standards, or a description of the exact measurement procedure and configuration used. This is load-bearing for the central performance assertion and leaves open the possibility of unaccounted artifacts from the probe card or switching board.

    Authors: We agree that the abstract presents this key performance claim concisely and without the supporting details requested. The body of the manuscript (in the sections describing the switching matrix characterization and system validation) includes the measurement procedure, worst-case configuration, and comparison to LGAD pixel leakage, along with supporting data. To address the concern directly, we will revise the abstract to briefly reference the validation approach and note that detailed procedures, raw data, and error considerations appear in the main text. This revision will make the abstract self-contained on this point while preserving the original claim, which is substantiated by the measurements reported. revision: yes

Circularity Check

0 steps flagged

No significant circularity detected

full rationale

The manuscript is a descriptive hardware-development report presenting a modular probe-card and switching-matrix system for automated I-V/C-V characterization of 16×16 LGAD arrays. All central claims (scan times, <1 nA added leakage in worst-case configuration, absence of obvious damage) are direct empirical results obtained from the built apparatus; the text contains no equations, parameter fits, derivations, or self-citations that reduce any reported quantity to an input by construction. The work is therefore self-contained against external benchmarks and receives the default non-circularity score.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

No mathematical model, free parameters, or new physical entities are introduced; the paper is an engineering description of a measurement apparatus.

pith-pipeline@v0.9.0 · 5793 in / 982 out tokens · 25239 ms · 2026-05-25T02:59:52.461505+00:00 · methodology

discussion (0)

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