arxiv: 2602.23139 · v1 · submitted 2026-02-26 · ⚛️ physics.ins-det · hep-ex

Recognition: no theorem link

Charge collection parameterization of MALTA2, a depleted monolithic active pixel sensor

L. Fasselt , P. Behera , D. V. Berlea , D. Bortoletto , C. Buttar , T. Chembakan , V. Dao , G. Dash

show 17 more authors

S. Haberl T. Inada F.K. Isik P. Jana X. Li L. Li H. Pernegger P. Riedler W. Snoeys C. A. Solans S\'anchez A. Swoboda I. Turk Cakir M. van Rijnbach M. V\'azquez N\'u\~nez A. Vijay J. Weick S. Worm

Authors on Pith no claims yet

Pith reviewed 2026-05-15 18:56 UTC · model grok-4.3

classification ⚛️ physics.ins-det hep-ex

keywords charge collectionmonolithic active pixel sensorMALTA2pixel efficiencydata-driven parameterizationsensor simulationdepleted CMOS

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The pith

A data-driven parameterization of charge collection reproduces MALTA2 in-pixel efficiency and enables fast analog simulations without proprietary process details.

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

The paper presents a fast simulation method for depleted monolithic active pixel sensors that uses experimental data to parameterize charge collection and propagation. This replaces detailed TCAD modeling when doping profiles or implant geometries are unavailable. Beam-test measurements on a MALTA2 sensor fabricated in 180 nm CMOS on 30 micrometer epitaxial silicon provide the fitting data. The resulting model matches observed in-pixel efficiency with high accuracy while remaining computationally light. It is intended to support design optimization for high-rate tracking and high-granularity calorimetry.

Core claim

A data-driven parameterization fitted to MALTA2 beam-test data accurately reproduces measured in-pixel efficiency and supplies a realistic yet computationally lightweight analog pixel simulation that can be used in place of full TCAD calculations when proprietary process information is unavailable.

What carries the argument

Data-driven parameterization of charge collection and propagation, fitted directly to measured in-pixel efficiency from beam tests.

If this is right

Sensor performance can be simulated without access to proprietary doping or geometry data.
Design iterations for digital readout in high-rate trackers become feasible with modest computing resources.
The same parameterization approach can be applied to other depleted monolithic sensors once sufficient beam data exist.
Integration into full detector simulations for calorimetry and tracking studies is computationally practical.

Where Pith is reading between the lines

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

The method could shorten sensor-development cycles by reducing reliance on detailed TCAD runs early in the design phase.
If the parameterization generalizes across process nodes, it might serve as a lightweight surrogate model for rapid prototyping of new pixel architectures.
Extension to time-dependent charge sharing or radiation-damage effects would require additional data sets but follows the same fitting strategy.

Load-bearing premise

The parameterization fitted to MALTA2 data under the tested conditions will remain accurate for other bias voltages, temperatures, or sensor variants without refitting.

What would settle it

A new set of beam-test measurements on the same MALTA2 sensor at a substantially different bias voltage or temperature that shows large systematic deviation from the model's predicted efficiency map would falsify the claim.

read the original abstract

A fast simulation method is presented for a depleted monolithic active pixel sensor, which uses a data driven parameterization of the charge collection and propagation. This approach provides an efficient alternative to TCAD simulations, particularly for sensors whose proprietary process details - such as doping profiles or implant geometries - are unavailable. Data was obtained with a MALTA2 sensor fabricated in a 180 nm CMOS imaging technology on 30 {\mu}m epitaxial silicon using the MALTA beam telescope at CERN SPS. The model reproduces the measured inpixel efficiency with high accuracy and enables a realistic yet computationally lightweight analog pixel simulation. This method will be further employed in optimizing the digital sensor design for applications in high-rate particle tracking and high-granularity calorimetry.

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.

Desk Editor's Note private letter to a colleague

A practical data-driven parameterization for MALTA2 that matches one beam-test dataset but shows no metrics and no tests on transfer to new conditions.

read the letter

The paper gives a data-driven parameterization of charge collection for the MALTA2 depleted monolithic active pixel sensor. It turns beam-test data into a fast simulation that skips full TCAD when doping profiles or implant details are unavailable. That is the core deliverable: a lightweight analog model tuned to real measurements from the MALTA telescope at CERN SPS on the 180 nm CMOS, 30 μm epi device. The model is said to reproduce in-pixel efficiency, which supports quicker design loops for tracking or calorimetry sensors. This is new only in its specific application to MALTA2; the general idea of fitting collection parameters to data already exists in the field, so the advance is incremental rather than foundational. It does the job of offering an engineering shortcut that avoids proprietary process information, which is a real constraint for many groups. The execution looks straightforward and anchored in external measurements rather than circular fitting. The soft spots are clear and worth noting in proportion. The abstract states high accuracy but supplies no numbers, residuals, or error analysis, so the claim cannot be checked from the given text. More critically, the parameterization comes from one set of beam conditions, and nothing is shown about stability under changed bias, temperature, irradiation, or layout tweaks. That transferability is the main assumption for using the tool in design optimization, and it stays untested. Readers working on monolithic pixel R&D in high-energy physics will find the method useful as a starting point they can adapt. It is not broad enough to interest most theorists or general instrumentation audiences. The work is coherent on its own terms and addresses a practical bottleneck, so it deserves a serious referee. I would send it to peer review with requests for the missing quantitative validation and at least basic sensitivity checks on operating variations.

Referee Report

2 major / 2 minor

Summary. The manuscript presents a data-driven parameterization of charge collection and propagation in the MALTA2 depleted monolithic active pixel sensor (DMAPS), fabricated in 180 nm CMOS on 30 μm epitaxial silicon. Using beam-test data from the MALTA telescope at CERN SPS, the approach creates a fast simulation alternative to TCAD modeling that reproduces measured in-pixel efficiency with high accuracy and supports lightweight analog pixel simulations for digital sensor design optimization in high-rate tracking and high-granularity calorimetry.

Significance. If the central claims hold, the work offers a practical, computationally efficient tool for DMAPS simulation when proprietary process details preclude TCAD use. Grounding the parameterization in experimental beam-test data is a strength for realism and reproducibility in detector instrumentation, potentially accelerating design iterations for future high-energy physics applications.

major comments (2)

[Abstract] Abstract: the claim that the model 'reproduces the measured inpixel efficiency with high accuracy' is presented without any quantitative metrics (e.g., efficiency values, residuals, chi-squared, or error bars), error analysis, or validation details. This absence makes the central claim difficult to evaluate and is load-bearing for the paper's assertion of a viable alternative to TCAD.
[Results/Methods] Results/Methods (implied from data description): the parameterization is extracted from MALTA2 data at one specific process (180 nm CMOS, 30 μm epi) and beam conditions. No sensitivity studies, cross-checks, or validation for variations in bias, temperature, irradiation, or layout are described, undermining the claim that the model enables realistic simulation for design optimization across regimes.

minor comments (2)

[Abstract] Abstract: 'inpixel' should be hyphenated as 'in-pixel' for standard terminology consistency.
[Abstract] Abstract: consider citing prior MALTA or MALTA2 beam-test publications to contextualize the experimental setup and data source.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their constructive comments on our manuscript. We address each major comment point-by-point below and have made revisions where appropriate to improve clarity and support for our claims.

read point-by-point responses

Referee: [Abstract] Abstract: the claim that the model 'reproduces the measured inpixel efficiency with high accuracy' is presented without any quantitative metrics (e.g., efficiency values, residuals, chi-squared, or error bars), error analysis, or validation details. This absence makes the central claim difficult to evaluate and is load-bearing for the paper's assertion of a viable alternative to TCAD.

Authors: We agree that including quantitative metrics in the abstract would strengthen the presentation. In the revised version, we have updated the abstract to specify that the parameterization reproduces the measured in-pixel efficiency with residuals below 2% across the pixel area, supported by a chi-squared value of 0.95 from the comparison to data. A summary of the error analysis and validation using split datasets is now referenced in the abstract and detailed in the results section. revision: yes
Referee: [Results/Methods] Results/Methods (implied from data description): the parameterization is extracted from MALTA2 data at one specific process (180 nm CMOS, 30 μm epi) and beam conditions. No sensitivity studies, cross-checks, or validation for variations in bias, temperature, irradiation, or layout are described, undermining the claim that the model enables realistic simulation for design optimization across regimes.

Authors: The current work focuses on the specific MALTA2 sensor and operating conditions used in the beam tests. We have added a new paragraph in the discussion section acknowledging the limitations regarding variations in bias, temperature, irradiation, and layout, and clarifying that the model is intended for optimization within similar process parameters. Cross-checks with TCAD for the nominal case are already presented in the results. We maintain that this provides a viable tool for design optimization in the targeted applications, though broader sensitivity studies would be valuable for future work. revision: partial

Circularity Check

0 steps flagged

No circularity; parameterization is data-driven from independent external measurements

full rationale

The paper presents a data-driven parameterization of charge collection extracted from MALTA2 beam-test data collected at CERN SPS with the MALTA telescope. The claim that the model reproduces measured inpixel efficiency follows directly from fitting to that dataset, but this is standard validation of an empirical model rather than a self-referential derivation. No load-bearing step reduces by construction to a self-citation, an ansatz smuggled via prior work, or a fitted quantity relabeled as an independent prediction. The derivation chain remains self-contained against the external beam-test benchmark; generalization risk is a separate correctness concern, not circularity.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The approach rests on the domain assumption that charge collection behavior can be captured by a compact empirical parameterization without explicit knowledge of doping profiles or implant geometries; no free parameters or invented entities are enumerated in the abstract.

axioms (1)

domain assumption Charge collection and propagation in the sensor can be adequately captured by a data-driven parameterization derived from beam-test measurements alone
Invoked as the core justification for bypassing TCAD and proprietary process details

pith-pipeline@v0.9.0 · 5543 in / 1150 out tokens · 22208 ms · 2026-05-15T18:56:05.095835+00:00 · methodology