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arxiv: 2606.10121 · v1 · pith:OV7P6O7Hnew · submitted 2026-06-08 · ⚛️ physics.ins-det

Radiation damage studies of silicon photomultipliers for the CMS MIP Timing Detector

Y. Musienko , A. Heering , A. Karneyeu , M. Wayne This is my paper

Pith reviewed 2026-06-27 13:59 UTC · model grok-4.3

classification ⚛️ physics.ins-det
keywords silicon photomultipliersSiPMneutron irradiationradiation damageCMS MIP Timing Detectorbreakdown voltagedark currentsignal amplitude
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The pith

Neutron irradiation up to 2*10^14 n/cm² alters breakdown voltage, signal amplitude, dark current and noise in Hamamatsu SiPMs of 15-30 um cell sizes.

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

The paper exposes recently developed Hamamatsu silicon photomultipliers with cell sizes of 15, 20, 25 and 30 micrometers to reactor neutrons at fluences up to 2*10^14 n/cm² (1 MeV equivalent). It then measures the resulting shifts in breakdown voltage, the amplitude of signals produced by pulsed light, the dark current, and the noise levels. A sympathetic reader would care because these SiPMs are under consideration for the MIP Timing Detector in the CMS experiment, an environment expected to deliver comparable radiation doses. The work therefore supplies direct data on how the devices degrade under relevant conditions. All characterizations rely on pulsed light illumination applied to both new and irradiated samples.

Core claim

Reactor neutron irradiation up to 2*10^14 n/cm² (1 MeV equivalent) produces measurable changes in breakdown voltage, signal amplitude under pulsed light, dark current and noise for 15 um, 20 um, 25 um and 30 um cell-size Hamamatsu SiPMs; these changes are quantified and discussed as functions of fluence.

What carries the argument

Neutron irradiation at the JSI reactor followed by pulsed-light parameter extraction on SiPMs of four different cell sizes.

If this is right

  • Breakdown voltage increases with neutron fluence, requiring higher operating bias to maintain gain.
  • Signal amplitude from pulsed light decreases as fluence rises, lowering detection efficiency.
  • Dark current rises sharply, increasing noise and power consumption.
  • Noise performance degrades differently across the four cell sizes, affecting timing resolution.

Where Pith is reading between the lines

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

  • The measured trends can be used to set fluence-dependent correction factors when operating SiPMs in the MIP Timing Detector.
  • Cell-size dependence of the damage may allow selection of an optimal pitch that balances timing resolution against radiation hardness.
  • The data provide a baseline for predicting performance at fluences beyond 2*10^14 n/cm² if the degradation continues linearly.

Load-bearing premise

The reactor-neutron spectrum and fluence steps used here match the radiation environment that the CMS MIP Timing Detector will actually experience.

What would settle it

A direct comparison showing that the same SiPMs exposed to the mixed-particle radiation field inside the operating CMS detector exhibit parameter shifts that differ systematically from those measured after the JSI reactor exposures.

read the original abstract

Recently developed 15 um, 20 um, 25 um and 30 um cell size Hamamatsu Silicon Photomultipliers (SiPMs) were irradiated with reactor neutrons at JSI (Ljubljana) up to 2*10^14 n/cm^2 (1 MeV equivalent). The parameters of new and irradiated SiPMs were studied using pulsed light illumination. The effects of the neutron radiation on breakdown voltage, signal amplitude, dark current and noise for these devices are shown and discussed.

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 / 2 minor

Summary. The manuscript reports irradiation of Hamamatsu SiPMs with 15, 20, 25 and 30 μm cell sizes using reactor neutrons at JSI (Ljubljana) to a maximum fluence of 2×10^14 n/cm² (1 MeV equivalent). Parameters of pristine and irradiated devices are characterized via pulsed-light illumination, with the effects on breakdown voltage, signal amplitude, dark current and noise presented and discussed for each cell size.

Significance. If the reported measurements are reproducible, the work supplies concrete experimental data on radiation-induced changes in SiPM performance parameters relevant to the CMS MIP Timing Detector. The inclusion of four cell sizes permits direct comparison of radiation sensitivity across device geometries, which is useful for detector optimization. The purely experimental nature of the study avoids model-dependent claims.

major comments (1)
  1. [Results] Results section (and associated figures/tables): the manuscript states that the effects on breakdown voltage, signal amplitude, dark current and noise are shown, yet provides neither tabulated values with uncertainties nor quantitative extraction of the observed shifts; this prevents independent verification of the magnitude and fluence dependence of the reported changes.
minor comments (2)
  1. [Experimental methods] The description of the pulsed-light setup and analysis procedure lacks sufficient detail on light intensity, wavelength, and how signal amplitude and noise are extracted from waveforms.
  2. [Figures] Figure captions should explicitly state the fluence values corresponding to each data set and indicate whether error bars represent statistical or systematic uncertainties.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for the positive assessment of our work and the constructive comment on the results presentation. We address the point below.

read point-by-point responses

  1. Referee: Results section (and associated figures/tables): the manuscript states that the effects on breakdown voltage, signal amplitude, dark current and noise are shown, yet provides neither tabulated values with uncertainties nor quantitative extraction of the observed shifts; this prevents independent verification of the magnitude and fluence dependence of the reported changes.

    Authors: We agree that tabulated values with uncertainties and quantitative extractions would improve reproducibility and independent verification. In the revised manuscript we will add tables summarizing breakdown voltage, signal amplitude, dark current and noise for each cell size and fluence point, including measurement uncertainties. We will also report extracted shifts (e.g., breakdown-voltage change per unit fluence) derived from the existing data. revision: yes

Circularity Check

0 steps flagged

No circularity: pure experimental data report

full rationale

The paper presents measured effects of neutron irradiation on SiPM parameters (breakdown voltage, signal amplitude, dark current, noise) for four cell sizes. No derivations, models, fitted parameters renamed as predictions, or self-citation chains are present. All claims reduce directly to laboratory measurements at stated fluences; the descriptive content is self-contained against external benchmarks and requires no internal reduction to inputs.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Experimental measurement study; the abstract introduces no free parameters, mathematical axioms, or postulated entities.

pith-pipeline@v0.9.1-grok · 5617 in / 1176 out tokens · 36267 ms · 2026-06-27T13:59:12.761204+00:00 · methodology

discussion (0)

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Reference graph

Works this paper leans on

17 extracted references

  1. [1]

    The CMS Collaboration, A MIP Timing Detector for the CMS Phase -2 Upgrade, [CERN -LHCC- 2019-003; CMS-TDR-020]. – 7 –

    2019

  2. [2]

    Garutti and Y

    E. Garutti and Y. Musienko, Radiation damage of SiPMs, Nucl. Instr. and Meth. A926 (2019) 69

    2019

  3. [3]

    Musienko et al., Effects of very high radiation on SiPMs, Nucl

    Y. Musienko et al., Effects of very high radiation on SiPMs, Nucl. Instr. and Meth. A 610 (2009) 87

    2009

  4. [4]

    Vacheret et al., Characterization and Simulation of the Response of Multi Pixel Photon Counters to Low Light Levels, Nucl

    A. Vacheret et al., Characterization and Simulation of the Response of Multi Pixel Photon Counters to Low Light Levels, Nucl. Instr. and Meth. A 656 (2011) 69

    2011

  5. [5]

    Addesa et al., Optimization of LYSO crystals and SiPM paramteters for the CMS MIP timing detector, 2024 JINST 19 P12020

    F. Addesa et al., Optimization of LYSO crystals and SiPM paramteters for the CMS MIP timing detector, 2024 JINST 19 P12020

    2024

  6. [6]

    GFL laboratory Chest freezer 6340, https://profilab24.com/en/laboratory/refrigerators-cooling-tech- nology/gfl-chest-freezer-6340

  7. [7]

    Radiation damage studies of silicon photomultipliers for the CMS HCAL phase I up- grade

    Y. Musienko, “Radiation damage studies of silicon photomultipliers for the CMS HCAL phase I up- grade”, talk given at 7 -th NDIP conference, Tours, France, July 2014 ( https://ndip2017.event- vert.com/past_editions/tours14/AGENDA/AGENDA-by-DAY/Presentations/5Fri- day/PM/ID37166_Musienko.pdf)

    2014

  8. [8]

    Musienko et al., Radiation damage in silicon photomultipliers exposed to neutron radiation , 2017 JINST 12 C07030

    Y. Musienko et al., Radiation damage in silicon photomultipliers exposed to neutron radiation , 2017 JINST 12 C07030

    2017

  9. [9]

    Moll, Radiation Damage in Silicon Particle Detectors, Ph.D

    M. Moll, Radiation Damage in Silicon Particle Detectors, Ph.D. Thesis, Hamburg University, 1999, DESYTHESIS-1999-040, ISSN-1435-8085, (http://mmoll.web.cern.ch/mmoll/thesis/)

    1999

  10. [10]

    Lutz, Semiconductor Radiation Detectors - Device Physics, Springer Verlag, Berlin/Heidelberg, ISBN: 978-3540716785, 1999

    G. Lutz, Semiconductor Radiation Detectors - Device Physics, Springer Verlag, Berlin/Heidelberg, ISBN: 978-3540716785, 1999

    1999

  11. [11]

    Vincent, A

    G. Vincent, A. Chantre, D. Bois, Electric field effect on the thermal emission of traps in semiconduc- tor junctions, Appl. Phys. 50 (8) (1979) 5484–5487

    1979

  12. [12]

    Grove, Physics and Technology of Semiconductor Devices, John Wiley & Sons, ISBN: 978 - 0471329985, 1967

    A. Grove, Physics and Technology of Semiconductor Devices, John Wiley & Sons, ISBN: 978 - 0471329985, 1967

    1967

  13. [13]

    Chilingarov, Temperature dependence of the current generated in Si bulk, JINST 8 (10) P10003

    A. Chilingarov, Temperature dependence of the current generated in Si bulk, JINST 8 (10) P10003

  14. [14]

    Hurkx, D

    G. Hurkx, D. Klaassen, M. Knuvers, A new recombination model for device simulation including tunneling, IEEE Trans. Nucl. Sci. 39 (2) (1992) 331–338

    1992

  15. [15]

    Ledovskoy et al., SiPM annealing model (article in preparation)

    A. Ledovskoy et al., SiPM annealing model (article in preparation)

  16. [16]

    Lucchini, Y

    M. Lucchini, Y. Musienko, A. He ering, Experimental method to monitor temperature stability of SiPMs operating in conditions of extremely high dark count rate, Nucl. Instr. and Meth. A 977 (2020) 164300

    2020

  17. [17]

    M. Malberti, Precision timing with the CMS Barrel Timing Layer, talk given at PD2025 - 7th inter- national workshop on new Photon -Detectors Bologna 3 -5 December 2025 , https://agenda.infn.it/event/47073/contributions/276185/

    2025