{"id":"bdc691d5-5433-400a-b868-1fa9ae811b4a","arxiv_id":"2603.20019","paper_version":2,"verdict":"ACCEPT","confidence":"HIGH","novelty_score":5.0,"correctness_risk":"low","formal_verification":"none","parameter_count":3,"one_line_summary":"A 30-ton WbLS detector was designed, constructed, commissioned with pure water, injected to 1% WbLS, and shown to operate stably with the expected light-yield rise on cosmic muons.","lead":"BNL built and commissioned a 30-ton water-based liquid scintillator (WbLS) detector prototype with 36 PMTs, circulation/purification plant, and dual muon/source triggers. It is an intermediate scale-up step that tests hybrid Cherenkov-scintillation readout and metal-loading for future kiloton neutrino detectors.","discovery_kind":"extension","skeptic_critique":{"model":"grok-4.5","headline":"No significant objection identified","rationale":"The manuscript is an instrumentation report that promises and delivers exactly the engineering milestone described in the abstract. All quantitative claims that appear (PMT TTS, SPE gain stability, truncated-mean muon light yield before/after injection) are backed by the figures and text of Secs. 3, 7 and 10. The purification plant is described in detail but correctly labeled as not yet commissioned; therefore the long-term optical-clarity assumption is not load-bearing for the paper’s actual claim. The concrete test above simply re-verifies the strongest short-term stability evidence already presented. No adjustment to the reader’s ACCEPT / HIGH-confidence verdict is warranted.","tokens_in":18748,"tokens_out":432,"duration_ms":4820,"concrete_test":"Re-extract the daily SPE-mean time series for every active channel from the raw calibration runs spanning 14 Apr–21 Jul 2025 (the interval of Fig. 18) and recompute the relative RMS variation after the 7 May injection; if any channel exceeds 10% RMS or shows a secular drift larger than the pre-injection baseline, the short-term stability claim would need qualification.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The paper’s central claim is limited to successful design, construction, commissioning with pure water, staged injection to 1% WbLS, and short-term stable operation (SPE gains constant to a few percent, muon light-yield rise as expected). That claim is directly supported by the hardware description (Secs. 2–7), commissioning timeline (Sec. 8), injection protocol (Sec. 9), and the muon/SPE data of Sec. 10 and Figs. 18–24. The reader’s weakest assumption—long-term steel/WbLS compatibility under the still-uncommissioned NF+SEA+Gd loops—is real but is explicitly scoped out of the present paper (abstract, Sec. 1, Sec. 11). No internal inconsistency or unsupported engineering assertion appears in the delivered results.","agreement_with_reader":"agree"},"referee_report":{"model":"grok-4.5","summary":"The manuscript describes the design, construction, commissioning, and initial operation of a 30-ton Water-based Liquid Scintillator (WbLS) prototype at BNL. It covers the stainless-steel tank and 36-PMT geometry, PMT characterization (gain and TTS), multi-loop circulation and purification plant (nanofiltration, Molecular Band-pass Gd system, Sequential Exchange Array), slow-control and DAQ systems, SPE calibration (source-tagged and random-trigger), pure-water commissioning, staged injection to 1% WbLS, and short-term performance monitored with cosmic muons. The central claim is that the detector was successfully built, commissioned with water, injected, and operated stably on the timescale of days to months, with SPE gains constant to a few percent and the expected rise in muon light yield. Detailed optical and long-term stability analyses, and commissioning of the full purification loops, are deferred to future papers.","tokens_in":18919,"tokens_out":1112,"duration_ms":8662,"significance":"If the reported engineering and short-term operational results hold, the work is a concrete, order-of-magnitude scale-up from the existing 1-ton BNL demonstrator and supplies practical design data (PMT supports and seals, dual-trigger logic, SEA resin capacity, NF membrane selection, injection protocol) needed for kiloton-scale concepts such as Theia and BUTTON. Strengths include explicit exclusion of failed channels, continuity checks between two SPE calibration methods, real-time muon monitoring of the water-to-WbLS transition, and transparent scoping of uncommissioned subsystems. The paper is primarily a hardware and operations report rather than a physics-result paper, but it is a necessary intermediate milestone for the global WbLS R&D program.","major_comments":[{"comment":"Secs. 2 and 4.1–4.3 and the abstract state that the nanofiltration, Gd Molecular Band-pass, and full SEA loops have been tested but not yet commissioned, while the tank places WbLS in direct contact with passivated 316L stainless steel (no liner). The short-term SPE and muon data of Sec. 10 (days to months) therefore cannot yet demonstrate the long-term optical clarity and chemical stability that the purification plant is designed to guarantee. The manuscript should either (a) add a quantitative upper limit on optical degradation or metal-ion leaching from the pure-water and post-injection periods already recorded, or (b) state more explicitly in the abstract and conclusion that long-term steel/WbLS compatibility remains an open claim pending future runs with the full purification system online.","section":null},{"comment":"Sec. 10 and Figs. 22–24 report truncated-mean charge and mean photoelectron yield for crossing muons before and after injection, but do not convert these quantities into an absolute light yield (photons/MeV or PE/MeV) or quote an attenuation length. Without at least a first-order absolute scale (or a clear statement that absolute calibration is deferred), the claim that the light-yield rise is “as expected” remains qualitative. A short absolute-scale estimate, even if preliminary and Monte-Carlo-dependent, would make the performance section load-bearing rather than purely relative.","section":null}],"minor_comments":[{"comment":"Abstract and Sec. 1: the sentence “Results from the analysis of data collected in the two detectors will follow in future publications” is repeated almost verbatim; one occurrence is sufficient.","section":null},{"comment":"Fig. 1 caption and Sec. 2: “nanofiltration and Gd systems are planned to be commissioned in future runs” should be cross-checked against Sec. 4, which states they have already been tested; clarify the distinction between “tested” and “commissioned.”","section":null},{"comment":"Sec. 4.3: the tank is described as 304 stainless steel while Sec. 2 states 316L; reconcile the alloy grade.","section":null},{"comment":"Sec. 4.1.1 and Fig. 8: “NF$” appears to be a typesetting artifact for a membrane name; correct or expand the label.","section":null},{"comment":"Sec. 7: the 210Pb source is later called an “alpha lightbulb”; introduce the colloquial name once for clarity.","section":null},{"comment":"Fig. 23 caption mentions only side PMTs while the text discusses both side and bottom; align caption and text.","section":null},{"comment":"Scattered typographical issues (missing spaces after periods, “Scintillationsignals,” “Adetectordeploying,” “WbLSisattractive,” etc.) should be cleaned in a final proof-reading pass.","section":null}],"recommendation":"minor_revision","confidential_remarks":"The paper is a solid instrumentation report appropriate for JINST. The two major comments are scoped so that they can be addressed by modest text additions or a short absolute-scale estimate without new data-taking; I would not insist on full long-term purification results before acceptance. Fit to the journal is good."},"author_rebuttal":null,"desk_editor":{"model":"grok-4.5","letter":"This is a clean instrumentation paper that does exactly what the abstract says: design, build, commission, inject, and run a 30-ton WbLS tank at BNL. The new pieces are the order-of-magnitude scale-up from their own 1-ton prototype, the direct-contact passivated 316L tank (no liner), the 36-PMT geometry tuned for in-ring/out-ring Cherenkov vs scintillation separation, the staged 1% injection protocol, and the full purification plant (NF membrane selection, SEA resin capacity, Gd band-pass) that is built but not yet commissioned.\n\nWhat they do well is straightforward and useful. PMT characterization (gain to ~10^7, TTS ~2.8 ns), SPE calibration with both the alpha-tagged source and later random triggers (Polya fits, continuity after the source PMT flooded), and continuous muon light-yield monitoring through the pure-water baseline, the injection transient, and the first days of 1% WbLS are all documented with clear figures. Three dead channels are simply excluded. The injection-transition light-yield curve (sharp rise, dip, recovery) is explained by micelle mixing and trigger logic and checked with Monte Carlo; that is honest engineering, not hand-waving. Citations to the 1-ton work and the broader Theia/Eos/ANNIE program are appropriate and not circular.\n\nThe soft spot is real but scoped correctly: long-term optical clarity and chemical stability of WbLS against bare stainless steel under continuous NF+SEA+Gd purification is still unproven. Only days-to-months of pure-water and post-injection data are shown; the purification loops themselves are deferred to future runs. The paper never claims otherwise. Free parameters (target mass fraction, nominal gain, resin capacity) are engineering choices, not hidden fits.\n\nThis is for people building hybrid optical detectors or metal-loaded scintillator systems who need the practical details of a multi-ton tank, circulation plant, and DAQ. It is not a physics-results paper and does not pretend to be. A serious editor should send it to referees; the work is reproducible, the claims match the data, and the limitations are stated. I would cite the hardware description and the short-term stability numbers when discussing WbLS scale-up.","headline":"Solid, honest 30-ton WbLS hardware paper that delivers the scale-up it promises; short-term data support the claims, long-term purification is correctly deferred.","tokens_in":19668,"tokens_out":567,"would_cite":true,"duration_ms":5824,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"grok-4.5","headline":"A 30-ton water-based liquid scintillator detector has been built, filled, and run stably as a bridge to kiloton-scale hybrid neutrino detectors.","keywords":["water-based liquid scintillator","WbLS","neutrino detector","photomultiplier tubes","nanofiltration","gadolinium loading","detector commissioning","hybrid Cherenkov-scintillation"],"falsifier":"Sustained multi-month running of the full purification plant (nanofiltration + sequential exchange array + Gd band-pass) at design turnover rates that fails to keep absorption length and light yield stable would falsify the claim that the medium remains viable at this scale.","tokens_in":19668,"feed_emoji":"⚛️","tokens_out":624,"duration_ms":5828,"temperature":0.7,"pith_summary":"This paper reports that a 30-ton water-based liquid scintillator (WbLS) detector was designed, constructed, commissioned with pure water, injected to 1% WbLS, and operated with stable photomultiplier response. WbLS mixes nanometer-scale scintillator micelles into water so that Cherenkov and scintillation light can both be recorded and their ratio tuned; metal loading further allows neutron tagging. The work is presented as the necessary intermediate step between a long-running 1-ton prototype and future multi-kiloton experiments that would use the same medium. Cosmic-muon data show the expected rise in light yield after injection, while single-photoelectron gains remain constant to within a few percent over months. Detailed physics analyses and full purification-system results are deferred to later papers; the present claim is that the hardware, circulation plant, and calibration chain work at this scale.","feed_headline":"30-ton water-based scintillator detector runs stably after injection","feed_subtitle":"Bridge from 1-ton prototypes toward kiloton hybrid neutrino detectors that separate Cherenkov and scintillation light","key_machinery":"The 30-ton stainless-steel tank instrumented with a geometrically arranged 36-PMT array (bottom spiral plus four side rows) that spatially separates Cherenkov-ring and isotropic scintillation light, together with the dual-loop circulation system (sequential exchange array, nanofiltration, and Gd band-pass) that keeps the medium clear and chemically tunable.","core_discovery":"The authors establish that a 30-ton WbLS detector, instrumented with 36 submerged 10-inch photomultipliers and a multi-loop purification plant, can be commissioned with pure water, injected to 1% WbLS, and operated with stable PMT gains and the expected increase in cosmic-muon light yield, thereby demonstrating that the technology scales from the 1-ton level toward kiloton detectors.","pith_inferences":[],"forward_implications":[],"fun_headline_variants":["BNL's 30-ton WbLS detector runs stable after 1% injection","30-ton water-based scintillator scales past 1-ton prototypes","Hybrid Cherenkov-scintillator detector operates at 30-ton scale","Stable PMT gains confirm WbLS path to kiloton neutrino detectors","30-ton prototype validates tunable WbLS for MeV-GeV detection"],"cache_read_input_tokens":16512,"weakest_assumption_plain":"Long-term optical clarity and chemical stability of WbLS sitting directly against passivated stainless steel without a liner can be maintained by the purification loops that have been built but not yet fully commissioned for continuous runs.","fun_headline_variants_meta":{"raw":{"variants":["BNL's 30-ton WbLS detector runs stable after 1% injection","30-ton water-based scintillator scales past 1-ton prototypes","Hybrid Cherenkov-scintillator detector operates at 30-ton scale","Stable PMT gains confirm WbLS path to kiloton neutrino detectors","30-ton prototype validates tunable WbLS for MeV-GeV detection"]},"model":"grok-4.5","effort":"low","cost_usd":0.004528,"raw_usage":{"total_tokens":1306,"prompt_tokens":731,"num_sources_used":0,"completion_tokens":103,"cost_in_usd_ticks":45280000,"prompt_tokens_details":{"text_tokens":731,"audio_tokens":0,"image_tokens":0,"cached_tokens":256},"completion_tokens_details":{"audio_tokens":0,"reasoning_tokens":472,"accepted_prediction_tokens":0,"rejected_prediction_tokens":0}},"tokens_in":731,"tokens_out":103,"duration_ms":4115,"temperature":1.0,"reasoning_tokens":472,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-07-13T21:44:02.640190+00:00","model_set":{"reader":"grok-4.5"},"falsifier":"Sustained multi-month running of the full purification plant (nanofiltration + sequential exchange array + Gd band-pass) at design turnover rates that fails to keep absorption length and light yield stable would falsify the claim that the medium remains viable at this scale.","supporting_citations":[],"review_version":1}