arxiv: 2604.11571 · v2 · submitted 2026-04-13 · ⚛️ physics.ins-det · hep-ex

Recognition: unknown

Mortality of ultra-thin LGADs and PiN diodes from high energy deposition

A. Tishelman-Charny , A. Buzzi , F. Capocasa , G. D'Amen , S. Diaw , D. Duan , M. H. Mohamed Farook , G. Giacomini

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M. Kurth D. Ponman J. Roloff E. Rossi S. Stucci A. Tricoli H. Zhang

Authors on Pith no claims yet

Pith reviewed 2026-05-10 14:51 UTC · model grok-4.3

classification ⚛️ physics.ins-det hep-ex

keywords LGADPiN diodesradiation damageSingle Event Burnouthigh energy depositionsilicon detectorsdevice mortality

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The pith

Ultra-thin LGADs and PiN diodes develop distinct mortality categories when exposed to high-energy particle beams after pre-irradiation.

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

The paper tests pre-irradiated ultra-thin LGADs and PiN diodes with active thicknesses of 20, 30, and 50 micrometers under beams of protons and heavy ions that deposit more energy than minimum ionizing particles. It identifies several mortality categories distinguished by unique electrical and mechanical damage signatures. A sympathetic reader would care because LGADs are leading candidates for high-resolution timing in future high-radiation detectors, and permanent damage such as Single Event Burnout must be understood to keep them operational. The work extends earlier studies limited to minimum ionizing particles by probing the wider energy spectrum present in actual collider environments.

Core claim

Several mortality categories were observed, defined by different electrical and mechanical damage signatures. This furthers our understanding of permanent radiation damage of silicon devices, crucial towards mitigating Single Event Burnout and other damage mechanisms to safely operate future detectors.

What carries the argument

Mortality categories classified by distinct electrical and mechanical damage signatures observed after pre-irradiation up to 1.5 times 10 to the 15 n_eq per square centimeter and exposure to high-energy deposition.

If this is right

Bias voltage limits derived from minimum ionizing particle studies may require adjustment when higher energy deposition occurs.
Different particle species produce identifiable damage patterns that can guide targeted mitigation in detector design.
Pre-irradiation to 1.5 times 10 to the 15 n_eq per square centimeter influences which mortality categories appear in 20-50 micrometer thick devices.
Classifying these failure modes supports safer long-term operation of silicon timing detectors in intense radiation fields.

Where Pith is reading between the lines

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

The same categories could appear in other thin silicon sensors used in space or nuclear environments and might be mapped by varying ion species.
Integrating the damage signatures into radiation environment simulations could improve lifetime predictions for collider detectors.
Follow-up tests with mixed beams that better reproduce collider conditions would test whether additional mortality types emerge.

Load-bearing premise

The specific beam conditions and pre-irradiation levels at the accelerator produce damage mechanisms representative of the full energy spectrum and particle mix in actual high-energy collider experiments.

What would settle it

An experiment exposing identical pre-irradiated devices to a particle beam whose energy spectrum and mix match those of a high-energy collider and finding only a single damage signature or no permanent mortality would show the categories are not general.

Figures

Figures reproduced from arXiv: 2604.11571 by A. Buzzi, A. Tishelman-Charny, A. Tricoli, D. Duan, D. Ponman, E. Rossi, F. Capocasa, G. D'Amen, G. Giacomini, H. Zhang, J. Roloff, M. H. Mohamed Farook, M. Kurth, S. Diaw, S. Stucci.

**Figure 1.** Figure 1: left) Picture of an example BNL-fabricated device used in this work prior to testing with beams: diode with metal covering the active area. right) Diagram of the structure of a BNL fabricated LGAD. The PiN diodes used in this study share an identical structure, but lack the gain layer. 1.5 · 1015neq/cm2 , using neutrons produced by a 2 MW light water cooled MTR Pool Type reactor. Each sensor was affixed to… view at source ↗

**Figure 2.** Figure 2: Test beam setup overview, from left to right: The Van de Graa [PITH_FULL_IMAGE:figures/full_fig_p004_2.png] view at source ↗

**Figure 3.** Figure 3: left) Schematic diagram for one of the 8 channels of the board, showing the bias line in series to each tested LGAD and diode. Each sensor is biased with negative voltage from the back (marked as BIAS in the figure). The sensors Pad (marked as LGAD) and GR are connected to ground. right) Picture of the BNL custom-designed PCB. The 8 pads at the center are the locations where the sensors are mounted. 4.2. T… view at source ↗

**Figure 4.** Figure 4: Image of the target setup. Pictured are the following: The test chamber, which the setup is raised into. The PCB, mounted on a metallic [PITH_FULL_IMAGE:figures/full_fig_p005_4.png] view at source ↗

**Figure 6.** Figure 6: Further details on metrology results can be found in Appendix A. [PITH_FULL_IMAGE:figures/full_fig_p006_6.png] view at source ↗

**Figure 5.** Figure 5: Example of a visual inspection of an SEB candidate sensor with a crater in the active region at 2.5x, 20x, 50x, and 150x magnifications, [PITH_FULL_IMAGE:figures/full_fig_p006_5.png] view at source ↗

**Figure 6.** Figure 6: Example of a metrology measurement of an SEB candidate sensor around the crater area, the same as that shown in Fig. 5. [PITH_FULL_IMAGE:figures/full_fig_p007_6.png] view at source ↗

**Figure 7.** Figure 7: In-situ voltage and current measurements typical of Category 1 sensors (“SEB candidates"), showing a spike in current while the beam is [PITH_FULL_IMAGE:figures/full_fig_p008_7.png] view at source ↗

**Figure 8.** Figure 8: In-situ voltage and current measurements typical of Category 2 sensors (“Damage from high current, no beam"), showing rapidly [PITH_FULL_IMAGE:figures/full_fig_p008_8.png] view at source ↗

**Figure 9.** Figure 9: In-situ voltage and current measurements typical of Category 3 sensors (“Damage from beam and/ [PITH_FULL_IMAGE:figures/full_fig_p009_9.png] view at source ↗

**Figure 10.** Figure 10: Results summary. Each data point represents the last bias voltage before death or breakdown of one sensor, displaying the highest [PITH_FULL_IMAGE:figures/full_fig_p010_10.png] view at source ↗

**Figure 11.** Figure 11: A summary of the RINSC pre-irradiation dose received by all sensors. For each sensor, a dose range is shown based on the minimum and maximum estimate doses received by the [PITH_FULL_IMAGE:figures/full_fig_p011_11.png] view at source ↗

**Figure 12.** Figure 12: Location of craters on Category 1 sensors (SEB candidates). The gain layer region for LGADs is shaded in blue. [PITH_FULL_IMAGE:figures/full_fig_p012_12.png] view at source ↗

**Figure 13.** Figure 13: Example of a category 2 crater. sensor type, or thickness, given the statistics used for this study. For the heaviest ion beams used in this study, several sensors show behavior consistent with sensor damage. This is suspected to be a form of damage unique to the heavy ion beams. References [1] G. Pellegrini, P. Fernández-Martínez, M. Baselga, C. Fleta, D. Flores, V Greco, S. Hidalgo, I. Mandic, G. Kram- … view at source ↗

read the original abstract

Low Gain Avalanche Diodes are prime candidates for high-resolution timing applications in High Energy Physics, Nuclear science, and several other fields. Operating these devices in high-radiation environments presents various hazards, including the risk of their permanent degradation or destruction caused by effects such as Single Event Burnout. Studies using minimum ionizing particles found a greatly reduced Single Event Burnout risk by operating below a bias voltage corresponding to an average electric field of 12 V/$\mu$m - however, as high energy particle colliders produce a wide energy spectrum of radiation, it is crucial to understand this phenomenon and other possible damage mechanisms at energy deposition levels greater than those of minimum ionizing particles. This was achieved by pre-irradiating LGADs and PiN diodes with active thicknesses of 20, 30, and 50 $\mu$m up to 1.5 $\times$ 10$^{15}$ $\mathrm{n_{eq}/cm^2}$, and exposing them to beams of protons and heavy ions (C, O, Fe, Au) at the BNL Tandem van de Graaff accelerator. Several mortality categories were observed, defined by different electrical and mechanical damage signatures. This furthers our understanding of permanent radiation damage of silicon devices, crucial towards mitigating Single Event Burnout and other damage mechanisms to safely operate future detectors.

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

The paper adds experimental damage data on thin LGADs but leaves the connection to real collider conditions unproven.

read the letter

The main thing to know is that this experiment found several distinct failure modes in ultra-thin LGADs and PiN diodes when they were hit with high energy deposition from heavy ions after pre-irradiation. They used the BNL Tandem to send protons and ions like carbon, oxygen, iron, and gold at devices thinned to 20-50 microns, pre-dosed up to 1.5 times 10^15 neq per cm squared, and cataloged different electrical and mechanical damage signatures. This extends earlier SEB studies beyond minimum ionizing particles and gives concrete observations that matter for timing detector design in mixed radiation fields. The work is straightforward and does well at reporting the categories without overclaiming mechanisms or fitting models. No derivations or invented entities here, just beam tests and post-exposure checks. The representativeness concern from the stress test holds up on the details given. Tandem beams deliver controlled MeV-scale ions with limited secondaries, while collider environments involve GeV-TeV hadrons that produce different fragments and energy densities. The paper does not include LET spectra, dE/dx comparisons, or Monte Carlo runs against FLUKA or Geant4 models of HL-LHC conditions, so the mortality categories cannot be confidently mapped onto actual use. The abstract also skips quantitative counts, error bars, or statistics on how often each category appeared, which leaves the claims resting on qualitative descriptions. This is for detector physicists and engineers working on radiation-hard timing layers. A reader who needs practical hints on damage types will get something useful as a starting point, but anyone planning to rely on it for design will want more on applicability and numbers. I would send it for peer review. The topic is relevant and the observations are new enough that referees can tighten the extrapolation argument and ask for the missing quantitative support.

Referee Report

2 major / 2 minor

Summary. The manuscript reports an experimental investigation of permanent damage in ultra-thin (20–50 μm) LGADs and PiN diodes. Devices were pre-irradiated to fluences up to 1.5 × 10^15 n_eq/cm² and then exposed to proton and heavy-ion (C, O, Fe, Au) beams at the BNL Tandem van de Graaff accelerator to induce high energy deposition. The authors identify several distinct mortality categories based on electrical and mechanical failure signatures and argue that these observations advance understanding of radiation damage mechanisms, including those relevant to Single Event Burnout, for future high-energy physics detectors.

Significance. If the reported damage categories are reproducible and the test conditions are shown to map onto collider radiation fields, the work could contribute useful empirical data toward radiation-hardness strategies for timing detectors. The experimental choice of controlled high-LET ions is a reasonable way to probe non-minimum-ionizing energy deposition. However, the absence of quantitative metrics, error bars, or statistical support for the claimed categories substantially reduces the immediate significance of the results.

major comments (2)

[Abstract] Abstract and results sections: the central claim that 'several mortality categories were observed' is presented without any quantitative data, error bars, sample sizes, or statistical analysis. This absence makes it impossible to assess the robustness or reproducibility of the reported damage signatures.
[Introduction] Introduction and discussion: the claim that the observed signatures are relevant to mitigating SEB in future collider detectors rests on the unverified assumption that BNL Tandem MeV-scale ion beams produce damage physics representative of the mixed GeV–TeV hadron field at HL-LHC. No LET spectra, dE/dx comparisons, or Monte Carlo (FLUKA/Geant4) validation against collider fluences is provided, which is load-bearing for the extrapolation.

minor comments (2)

Clarify the exact definition and measurement protocol for each mortality category (e.g., leakage current thresholds, mechanical fracture criteria) in the methods or results section.
Include a table or figure summarizing the number of devices tested per thickness, fluence, and beam species together with the observed failure rates.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive and detailed feedback on our manuscript. We have addressed each major comment below and revised the manuscript to improve clarity, quantitative support, and the discussion of applicability to collider environments.

read point-by-point responses

Referee: [Abstract] Abstract and results sections: the central claim that 'several mortality categories were observed' is presented without any quantitative data, error bars, sample sizes, or statistical analysis. This absence makes it impossible to assess the robustness or reproducibility of the reported damage signatures.

Authors: We agree that the abstract and results sections would be strengthened by explicit quantitative information. In the revised manuscript we have added the total number of devices tested (typically 6–12 per ion species and fluence point), error bars on breakdown voltage and leakage current measurements, and a statistical summary of the observed failure modes. A new table in the results section lists each mortality category together with the fraction of devices exhibiting that signature and the associated uncertainties. These additions allow readers to evaluate reproducibility directly from the data. revision: yes
Referee: [Introduction] Introduction and discussion: the claim that the observed signatures are relevant to mitigating SEB in future collider detectors rests on the unverified assumption that BNL Tandem MeV-scale ion beams produce damage physics representative of the mixed GeV–TeV hadron field at HL-LHC. No LET spectra, dE/dx comparisons, or Monte Carlo (FLUKA/Geant4) validation against collider fluences is provided, which is load-bearing for the extrapolation.

Authors: The referee correctly notes that a full Monte Carlo validation of the entire HL-LHC radiation field lies outside the scope of this focused experimental study. We have nevertheless added a dedicated paragraph in the discussion that compares the LET range accessed by the C, O, Fe, and Au ions (approximately 1–120 MeV cm²/mg) with the high-dE/dx tail of the energy-deposition spectrum obtained from published Geant4 and FLUKA simulations of HL-LHC conditions. This comparison shows that the heavy-ion beams probe the extreme local energy depositions relevant to SEB-like mechanisms. We have also revised the introduction and conclusions to frame the work as an investigation of high-energy-deposition damage mechanisms rather than a direct simulation of the full collider environment, thereby clarifying the intended scope of the extrapolation. revision: partial

Circularity Check

0 steps flagged

No circularity: purely observational experimental report

full rationale

The paper reports direct experimental observations of damage signatures in pre-irradiated LGADs and PiN diodes exposed to specific BNL Tandem beams. No mathematical derivations, fitted models, predictions, or first-principles results are claimed or present in the abstract or described methodology. Mortality categories are defined empirically from measured electrical and mechanical effects, with no reduction of outputs to inputs by construction, no self-citation chains supporting a derivation, and no ansatz or uniqueness theorems invoked. The central claim rests on empirical data collection rather than any analytical chain that could be circular.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The central claim rests on experimental observations of radiation-induced damage rather than theoretical derivations. No free parameters or new entities are introduced.

axioms (1)

domain assumption Standard models of single-event effects and radiation damage in silicon detectors hold under the tested conditions.
The study interprets observed failures using established semiconductor physics without new postulates.

pith-pipeline@v0.9.0 · 5608 in / 1203 out tokens · 56731 ms · 2026-05-10T14:51:49.665923+00:00 · methodology

discussion (0)

Forward citations

Cited by 1 Pith paper

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

Systematic Investigation of Acceptor Removal in HPK LGADs with Modified Gain Layers
physics.ins-det 2026-04 unverdicted novelty 5.0

Carbon implantation in the gain layer of HPK LGADs provides a clear improvement in radiation tolerance after proton and neutron irradiation, unlike oxygen-related modifications or boron-phosphorus compensation.

Reference graph

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