Hit-rate capability of a silicon strip detector module for decay positron detection in the J-PARC muon $g-2$/EDM experiment

Hiroshi Sendai; Hiroshi Yamaoka; Hiroyuki A. Torii; Junichi Suzuki; Junji Tojo; Katsunori Awa; Koichiro Shimomura; Maki Sakakibara; Manobu M. Tanaka; Masayoshi Shoji

REVIEW 3 major objections 5 minor 16 references

A silicon-strip detector module loses only 10% of hits at the 1.4 MHz rate required for the J-PARC muon g-2/EDM experiment, a loss the authors judge negligible for track reconstruction.

Reviewed by Pith at T0; open to challenge. T0 means a machine referee read the full paper against a public rubric. the ladder, T0–T4 →

Challenge this review Re-run · record.json Download PDF Read on arXiv ↗

T0 review · grok-4.5

2026-07-12 13:50 UTC pith:LIUWM6CR

load-bearing objection Solid beam-test measurement of 10% pile-up loss at the design 1.4 MHz rate for the production quarter-vane; the leap to “satisfies g-2 track reconstruction” is still deferred. the 3 major comments →

arxiv 2606.16347 v2 pith:LIUWM6CR submitted 2026-06-15 physics.ins-det

Hit-rate capability of a silicon strip detector module for decay positron detection in the J-PARC muon g-2/EDM experiment

Ryuto Azuma , Katsunori Awa , Shunsuke Doi , Yowichi Fujita , Seiso Fukumura , Yu Goto , Ryotaro Honda , Sohtaro Kanda

show 29 more authors

Tetsuichi Kishishita Tatsuya Kume Tsutomu Mibe Yukiharu Murata Shoichiro Nishimura Shinji Ogawa Yuta Okazaki Naohito Saito Maki Sakakibara Osamu Sasaki Taiki Sato Yutaro Sato Yoshiaki Seino Hiroshi Sendai Koichiro Shimomura Shohei Shirabe Masayoshi Shoji Patrick Strasser Taikan Suehara Shiori Sugahara Junichi Suzuki Toshikazu Takatomi Manobu M. Tanaka Junji Tojo Hiroyuki A. Torii Takashi Yamanaka Hiroshi Yamaoka Takayuki Yamazaki Tamaki Yoshioka

This is my paper

classification physics.ins-det

keywords silicon strip detectorhit-rate capabilitypile-upmuon g-2EDMpositron trackingJ-PARCSliT ASIC

verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved

The pith

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

The J-PARC muon g-2/EDM experiment needs a silicon-strip tracker that can still find positron tracks when individual sensor strips are hit at up to 1.4 MHz. The authors built the smallest unit of that detector (a “quarter-vane” of four sensors plus custom front-end ASICs) and tested it in a pulsed muon beam whose instantaneous rates span the design value. By counting hits as a function of time after the beam pulse and fitting a simple pile-up model, they extract a maximum hit-loss of 10% at 1.4 MHz. Because a typical signal track produces roughly fifty hits, that fractional loss is argued to leave track-finding efficiency essentially intact, satisfying the experiment’s key rate requirement.

Core claim

Under beam conditions that produce a maximum instantaneous hit rate of 1.4 MHz per strip, the measured efficiency loss due to analog pile-up is 10%. With approximately fifty hits expected per positron track in the momentum range of interest, this loss is stated to have a negligible effect on track reconstruction, so the developed quarter-vane module meets the hit-rate specification of the J-PARC muon g-2/EDM experiment.

What carries the argument

The pile-up model f(t)=p0(1-p1 e^{-t/τ})e^{-t/τ}+p2 fitted to the observed decay-time spectra; the free parameter p1 is the maximum fractional hit loss at the highest rate and is the single number used to judge compliance with the 1.4 MHz requirement.

Load-bearing premise

That a simple multiplicative pile-up factor correctly describes the dominant loss and that a 10% hit loss remains negligible once full track-finding with realistic analog waveforms is performed.

What would settle it

A full end-to-end simulation that injects the measured analog waveforms into the planned track-finding algorithm and shows that the reconstruction efficiency at 1.4 MHz falls well below the design requirement would falsify the claim that 10% hit loss is negligible.

Watch this falsifier — get emailed when new claim-graph text bears on it.

If this is right

The quarter-vane architecture and SliT128D front-end can be replicated for the full 40-vane detector without redesign for rate.
A 10% hit-loss budget can be used as a quantitative acceptance criterion for future production modules.
Offline ToT cuts that already achieve signal-to-noise >9e4 can be retained without further tightening for high-rate running.
The measured 75 ns CR-RC pulse width is confirmed to be short enough for the design rate.

Where Pith is reading between the lines

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

If the forthcoming waveform-level track-finding study confirms the 10% figure, the same module can be considered for other high-rate muon or positron experiments that face similar instantaneous densities.
Residual beam-synchronous noise from the electrostatic kicker, even when mitigated, may still set a practical lower limit on usable ToT thresholds in the real experiment.
Because the loss scales linearly with rate, modest reductions in early-time muon density (e.g., by beam-shaping) would yield proportional gains in hit efficiency.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit.

Desk Editor's Note

Solid beam-test measurement of 10% pile-up loss at the design 1.4 MHz rate for the production quarter-vane; the leap to “satisfies g-2 track reconstruction” is still deferred.

read the letter

This is a clean instrumentation paper that delivers the first quantitative pile-up loss curve for the production SliT128D quarter-vane under high-rate muon-decay conditions. That is the new result: at the 1.4 MHz design rate they extract a maximum efficiency loss of 10% from a transparent exponential-plus-rate-proportional-loss fit (eq. 4.1) to the time spectra, binned by hits per channel. Noise, ToT calibration, and the ToT>20 ns cut are documented with figures; the fit describes the data well. For anyone building or reviewing the J-PARC muon g-2/EDM tracker this is useful, self-contained data.

What it does well is keep the claim proportional to the measurement. They show the loss scales roughly with rate, quote the 10% number at the relevant bin, and note that ~50 hits per signal track make a 10% hit loss unlikely to kill reconstruction. The hardware description (sensor, FPC, ASIC boards, FRBS, cooling) is clear and the MuSEUM beam conditions are realistic enough for a rate test.

The soft spot is exactly the one the stress-test flags, and the authors already own it: the consistency check with the full analog-waveform track-finding simulation “remains a future work.” So the step from “10% hit loss measured here” to “module satisfies the experiment’s requirements” is still an assertion, not a demonstrated reconstruction efficiency. Minor operational caveats (kicker off, analysis window starting 400 ns after the second bunch, 1.7 T vs 3 T environment) exist but do not look load-bearing for the rate measurement itself. The functional form of the pile-up model is standard and fits; I would not over-weight residual non-exponential backgrounds without evidence they matter.

This is for the collaboration and for people who care about high-rate silicon strip systems. It is not a physics result and does not claim to be. Math and data look solid; citations are appropriate. I would send it to peer review without hesitation—JINST-style instrumentation papers live on exactly this kind of beam-test characterization. Engage if you need the number or the module description; otherwise it is a solid reference, not required reading outside the experiment.

Referee Report

3 major / 5 minor

Summary. The manuscript reports the design and beam-test evaluation of a silicon-strip “quarter-vane” module for the positron tracking detector of the J-PARC muon g−2/EDM experiment. Four Hamamatsu S13804 sensors (190 μm pitch) are read out by SliT128D ASICs (200 MHz sampling, CR-RC shaping ~75 ns) and an FPGA board. Using the MuSEUM surface-muon setup at MLF H-line, the authors measure equivalent noise charge, calibrate ToT-to-charge, apply a ToT > 20 ns cut, and extract pile-up loss from time spectra. Fitting the rate-proportional model of Eq. (4.1) to multi-hit samples yields a maximum efficiency loss of ~10 % at the design rate of 1.4 MHz per strip (corresponding to ~3 hits/event). They conclude that, given ~50 hits per signal track, this loss has negligible impact on track reconstruction and that the module meets experimental requirements.

Significance. A quantitative, beam-based demonstration of hit-rate capability at the design instantaneous rate is an essential milestone for the J-PARC g−2/EDM tracking system. The work supplies concrete numbers (ENC ≈ 0.200 fC, MIP ToT ≈ 60 ns, S/N after cut > 9×10^4, p1 ≈ 0.10 at 1.4 MHz) obtained with the production-version ASIC and the actual quarter-vane geometry. These results are directly usable by the collaboration for rate budgeting and for validating the analog-waveform simulation already cited in Ref. [16]. The measurement is therefore of clear practical value to the experiment and of interest to the broader silicon-strip instrumentation community facing high-rate environments.

major comments (3)

[§4.4 / Conclusions] §4.4 and Conclusions: The central claim that “a 10 % loss of hits o has a negligible impact on track reconstruction efficiency” and that “the developed detector module satisfies the performance requirements” rests on an unquantified assertion. The paper itself states that a consistency check with the analog-waveform track-finding simulation “remains a future work.” Without that (or an equivalent quantitative reconstruction study under the measured loss), the leap from measured hit loss to experimental readiness is not yet demonstrated. Either perform/report the check or qualify the claim to the measured hit-level efficiency alone.
[§4.4, Eq. (4.1)] §4.4, Eq. (4.1): The multiplicative dead-time model f(t)=p0(1−p1 e^{−t/τ})e^{−t/τ}+p2 is fitted successfully, but its validity under the actual g−2/EDM conditions (3 T helical orbits, different positron spectrum, continuous rather than pulsed high-rate environment after injection) is not established. Residual beam-synchronous noise (even with the kicker off), non-exponential backgrounds after the 55 mm Al absorber, or pulse-shape differences could bias p1. A short discussion of systematic uncertainty on the extracted 10 % figure, or a cross-check with an independent pile-up estimator, would strengthen the result.
[§3 / §4.4] §3 and §4.4: The analysis window begins 400 ns after the second muon bunch and the electrostatic kicker of another beam line had to be turned off. Both choices remove conditions that will be present (or different) in the storage-ring environment. The paper should quantify how sensitive the extracted p1 is to the choice of t=0 and to residual synchronized noise, so that the reader can judge the robustness of the 1.4 MHz result.

minor comments (5)

[§1.3] Title of §1.3 contains a duplicated “of of”.
[Fig. 9] Figure 9 y-axis label “Number of channels / event” is ambiguous; clarify whether it is occupancy or channel multiplicity.
[§4.4] The correspondence “3 hits/event ↔ 1.4 MHz” assumes pure exponential decay with the rest-muon lifetime; a one-sentence derivation or reference would help the reader.
[References] Reference [16] is cited for the track-finding simulation; if a public note or arXiv version exists, add the identifier for reproducibility.
[§2.1 / [9]] In §2.1 the sensor model is given as S13804; the Hamamatsu link in [9] should be checked for permanence or replaced by a stable citation.

Circularity Check

0 steps flagged

No circularity: hit-rate capability is measured from beam data with a simple phenomenological fit; the 10% loss figure is not forced by construction or self-citation.

full rationale

This is an instrumentation performance paper. The central claim (maximum efficiency loss of ~10% at 1.4 MHz) is obtained by fitting the phenomenological form f(t)=p0(1-p1 e^{-t/τ})e^{-t/τ}+p2 to measured time spectra of hits under MuSEUM beam conditions, then reading p1 at the hit multiplicity that corresponds to the target rate. The functional form is an assumption about rate-proportional pile-up, not a definition that makes p1 tautological; the data could have returned a different p1. Self-citations (SliT ASIC [7], sensor prototype [10], track-finding simulation [16]) supply prior hardware characterization or note that a full reconstruction consistency check remains future work; none of them define or force the measured 10% figure. There is no self-definitional loop, no fitted parameter renamed as an independent prediction of the same quantity, and no uniqueness theorem imported from the authors. The paper is self-contained against its own beam data. Score 0.

Axiom & Free-Parameter Ledger

4 free parameters · 4 axioms · 0 invented entities

The result rests on standard detector-physics assumptions (MIP charge, muon lifetime, exponential decay) plus a simple phenomenological pile-up model whose free parameters are fitted to the beam data. No new physical entities are postulated.

free parameters (4)

p1 (maximum efficiency loss at t=0) = 0.09671 ± 0.00181 (example 3-hit sample); ~0.10 at 1.4 MHz
Fitted free parameter in eq. (4.1) that directly becomes the quoted 10% loss; extracted channel-by-channel from the time-spectrum data.
p0, p2 (normalization and constant background)
Additional free parameters of the same fit; needed to isolate p1 but not themselves the physics claim.
comparator threshold = 0.413 MIP
Set by hand to 0.413 MIP after test-pulse calibration; affects which hits enter the efficiency calculation.
ToT lower cut = 20 ns
Chosen at 20 ns to maximize S/N after inspecting beam-on vs beam-off distributions; post-selection cut.

axioms (4)

domain assumption Muon lifetime is fixed at the PDG rest-frame value 2.1969811 μs (dilated only by the known beam momentum).
Used as a fixed parameter in every time-spectrum fit (§4.4).
ad hoc to paper Pile-up loss is proportional to instantaneous hit rate, leading to the multiplicative factor (1-p1 e^{-t/τ}).
Phenomenological model introduced in eq. (4.1); not derived from first-principles waveform simulation in this paper.
domain assumption A typical signal positron track (200–275 MeV/c) produces approximately 50 hits on the detector.
Taken from the experiment’s design studies; used to argue that 10% hit loss is negligible (§4.4).
domain assumption Equivalent noise charge ~0.2 fC is negligible compared with the 0.413 MIP threshold.
Measured and used to justify that electronics noise does not dominate the efficiency loss (§4.1).

pith-pipeline@v1.1.0-grok45 · 13309 in / 2635 out tokens · 26124 ms · 2026-07-12T13:50:15.847713+00:00 · methodology

0 comments

read the original abstract

In the J-PARC muon $g-2$/EDM experiment, a silicon strip detector will be used to detect positrons from muon decays. The detector consists of planes of detector modules arranged radially. The expected maximum hit rate reaches 1.4~MHz per sensor strip, and achieving high detection efficiency even under such hit-rate conditions is a key performance requirement. We have developed the smallest unit of the detector module, and its performance was evaluated using a muon beam at the J-PARC MLF H-line. The specifications of the detector module and the evaluated hit-rate capability are described in this article.

discussion (0)

Reference graph

Works this paper leans on

16 extracted references · 1 linked inside Pith

[1]

D. P. Aguillard, et al., Measurement of the positive muon anomalous magnetic moment to 127 ppb, Phys. Rev. Lett. 135 (2025) 101802

2025
[2]

G. W. Bennett, et al., Final report of the E821 muon anomalous magnetic moment measurement at BNL, Phys. Rev. D 73 (2006) 072003

2006
[3]

Aliberti, et al., The anomalous magnetic moment of the muon in the Standard Model: an update, Physics Reports 1143 (2025) 1–158

R. Aliberti, et al., The anomalous magnetic moment of the muon in the Standard Model: an update, Physics Reports 1143 (2025) 1–158

2025
[4]

G. W. Bennett, et al., Improved limit on the muon electric dipole moment, Phys. Rev. D 80 (2009) 052008

2009
[5]

Adelmann, et al., Search for a muon EDM using the frozen-spin technique (2021)

A. Adelmann, et al., Search for a muon EDM using the frozen-spin technique (2021). arXiv:2102.08838

Pith/arXiv arXiv 2021
[6]

Abe, et al., A new approach for measuring the muon anomalous magnetic moment and electric dipole moment, Prog

M. Abe, et al., A new approach for measuring the muon anomalous magnetic moment and electric dipole moment, Prog. Theor. Exp. Phys. 2019 (2019) 053C02

2019
[7]

Kishishita, et al., SliT: A strip-sensor readout chip with subnanosecond time walk for the J-PARC muon𝑔−2/EDM experiment, IEEE Trans

T. Kishishita, et al., SliT: A strip-sensor readout chip with subnanosecond time walk for the J-PARC muon𝑔−2/EDM experiment, IEEE Trans. Nucl. Sci. 67 (2020) 2089–2095

2020
[8]

Strasser, et al., Precision measurements of muonium and muonic helium hyperfine structure at J-PARC, The European Physical Journal D 79 (2025) 20

P. Strasser, et al., Precision measurements of muonium and muonic helium hyperfine structure at J-PARC, The European Physical Journal D 79 (2025) 20

2025
[9]

https://www.hamamatsu.com/jp/en/product/optical-sensors/photodiodes/si-photodiode-array/si-strip- detector/S13804.html (2023)

2023
[10]

Aoyagi, et al., Performance evaluation of a silicon strip detector for positrons/electrons from a pulsed a muon beam, JINST 15 (2020) P04027

T. Aoyagi, et al., Performance evaluation of a silicon strip detector for positrons/electrons from a pulsed a muon beam, JINST 15 (2020) P04027. – 11 –

2020
[11]

Arai, et al., Fine-flexible printed circuit board for particle physics experiment (in Japanese), Tech

D. Arai, et al., Fine-flexible printed circuit board for particle physics experiment (in Japanese), Tech. Rep. 134, Fujikura giho (2021)

2021
[12]

Uchida, Hardware-Based TCP Processor for Gigabit Ethernet, IEEE Trans

T. Uchida, Hardware-Based TCP Processor for Gigabit Ethernet, IEEE Trans. Nucl. Sci. 55 (2008) 1631–1637

2008
[13]

Nakayoshi, et al., DAQ-Middleware: Progress and status, J

K. Nakayoshi, et al., DAQ-Middleware: Progress and status, J. Phys.: Conf. Ser. 331 (2011) 022023

2011
[14]

https://www.kel.jp/product/product_detail/id=398 (2025)

2025
[15]

N.Kawamura,etal.,Newconceptforalarge-acceptancegeneral-purposemuonbeamline,Progressof Theoretical and Experimental Physics 2018 (11) (2018) 113G01

2018
[16]

Chetri, et al., GPU-based track-finding for the J-PARC muon𝑔−2/EDM experiment, JINST 21 (2026) P01006

H. Chetri, et al., GPU-based track-finding for the J-PARC muon𝑔−2/EDM experiment, JINST 21 (2026) P01006. – 12 –

2026

[1] [1]

D. P. Aguillard, et al., Measurement of the positive muon anomalous magnetic moment to 127 ppb, Phys. Rev. Lett. 135 (2025) 101802

2025

[2] [2]

G. W. Bennett, et al., Final report of the E821 muon anomalous magnetic moment measurement at BNL, Phys. Rev. D 73 (2006) 072003

2006

[3] [3]

Aliberti, et al., The anomalous magnetic moment of the muon in the Standard Model: an update, Physics Reports 1143 (2025) 1–158

R. Aliberti, et al., The anomalous magnetic moment of the muon in the Standard Model: an update, Physics Reports 1143 (2025) 1–158

2025

[4] [4]

G. W. Bennett, et al., Improved limit on the muon electric dipole moment, Phys. Rev. D 80 (2009) 052008

2009

[5] [5]

Adelmann, et al., Search for a muon EDM using the frozen-spin technique (2021)

A. Adelmann, et al., Search for a muon EDM using the frozen-spin technique (2021). arXiv:2102.08838

Pith/arXiv arXiv 2021

[6] [6]

Abe, et al., A new approach for measuring the muon anomalous magnetic moment and electric dipole moment, Prog

M. Abe, et al., A new approach for measuring the muon anomalous magnetic moment and electric dipole moment, Prog. Theor. Exp. Phys. 2019 (2019) 053C02

2019

[7] [7]

Kishishita, et al., SliT: A strip-sensor readout chip with subnanosecond time walk for the J-PARC muon𝑔−2/EDM experiment, IEEE Trans

T. Kishishita, et al., SliT: A strip-sensor readout chip with subnanosecond time walk for the J-PARC muon𝑔−2/EDM experiment, IEEE Trans. Nucl. Sci. 67 (2020) 2089–2095

2020

[8] [8]

Strasser, et al., Precision measurements of muonium and muonic helium hyperfine structure at J-PARC, The European Physical Journal D 79 (2025) 20

P. Strasser, et al., Precision measurements of muonium and muonic helium hyperfine structure at J-PARC, The European Physical Journal D 79 (2025) 20

2025

[9] [9]

https://www.hamamatsu.com/jp/en/product/optical-sensors/photodiodes/si-photodiode-array/si-strip- detector/S13804.html (2023)

2023

[10] [10]

Aoyagi, et al., Performance evaluation of a silicon strip detector for positrons/electrons from a pulsed a muon beam, JINST 15 (2020) P04027

T. Aoyagi, et al., Performance evaluation of a silicon strip detector for positrons/electrons from a pulsed a muon beam, JINST 15 (2020) P04027. – 11 –

2020

[11] [11]

Arai, et al., Fine-flexible printed circuit board for particle physics experiment (in Japanese), Tech

D. Arai, et al., Fine-flexible printed circuit board for particle physics experiment (in Japanese), Tech. Rep. 134, Fujikura giho (2021)

2021

[12] [12]

Uchida, Hardware-Based TCP Processor for Gigabit Ethernet, IEEE Trans

T. Uchida, Hardware-Based TCP Processor for Gigabit Ethernet, IEEE Trans. Nucl. Sci. 55 (2008) 1631–1637

2008

[13] [13]

Nakayoshi, et al., DAQ-Middleware: Progress and status, J

K. Nakayoshi, et al., DAQ-Middleware: Progress and status, J. Phys.: Conf. Ser. 331 (2011) 022023

2011

[14] [14]

https://www.kel.jp/product/product_detail/id=398 (2025)

2025

[15] [15]

N.Kawamura,etal.,Newconceptforalarge-acceptancegeneral-purposemuonbeamline,Progressof Theoretical and Experimental Physics 2018 (11) (2018) 113G01

2018

[16] [16]

Chetri, et al., GPU-based track-finding for the J-PARC muon𝑔−2/EDM experiment, JINST 21 (2026) P01006

H. Chetri, et al., GPU-based track-finding for the J-PARC muon𝑔−2/EDM experiment, JINST 21 (2026) P01006. – 12 –

2026