{"id":"c350a633-f19b-4778-ad4a-5c05e76c7c0d","arxiv_id":"2607.03265","paper_version":1,"verdict":"ACCEPT","confidence":"HIGH","novelty_score":5.0,"correctness_risk":"low","formal_verification":"none","parameter_count":4,"one_line_summary":"FINER's 210–350 GHz SIS receiver has reached commissioning-level noise (~100 K) and ~20 dB digital sideband rejection, targeting five-fold wider instantaneous bandwidth than ALMA for z>10 galaxy spectroscopy on the LMT.","lead":"A Japanese-led team is building FINER, a dual-band millimeter receiver for Mexico's Large Millimeter Telescope that aims for roughly five times ALMA's instantaneous bandwidth. Lab tests already show the higher-frequency channel meets commissioning noise and sideband-rejection targets, with first light planned for 2026 to hunt oxygen and carbon lines in galaxies beyond redshift 10.","discovery_kind":"new_method","skeptic_critique":{"model":"grok-4.5","headline":"No significant objection identified","rationale":"The Reader correctly isolates the laboratory performance numbers as the strongest claim and correctly flags the on-sky projections as contingent. Because the paper never claims those projections have already been realized, the contingency does not undermine the central laboratory result. For an instrumentation-status paper of this genre the evidence is sufficient; no load-bearing technical flaw requires a change of verdict.","tokens_in":8705,"tokens_out":293,"duration_ms":4022,"concrete_test":"Confirm that the laboratory TRX and SRR values cited in Section 2 and Figure 1 are the same numbers that will be used as the baseline for the 2026 commissioning report; any later on-sky degradation larger than ~20 % would simply update the projections without invalidating the present laboratory claim.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The paper is a standard instrumentation-status proceeding whose central claim is laboratory performance of the Band 6+7 receiver (TRX ~100 K, analog SRR ~10 dB enhanced to ~20 dB by DSBS). That claim is presented as already measured and is not circular. The on-sky sensitivity projections in Figure 2 are explicitly labeled as estimates that rest on unmeasured aperture efficiency, pointing, and atmospheric stability once installed; they are not asserted as demonstrated results. No internal inconsistency or unsupported quantitative claim appears in the strongest claim itself.","agreement_with_reader":"agree"},"referee_report":{"model":"grok-4.5","summary":"The manuscript presents the development status of the Far-Infrared Nebular Emission Receiver (FINER) for the LMT, comprising dual-polarization 2SB SIS receivers covering 120–210 GHz and 210–350 GHz, warm optics for simultaneous two-band observations, and a 10.24 GHz digital spectrometer array with digital sideband separation (DSBS). The central technical claim is that the 210–350 GHz (Band 6+7) receiver has reached commissioning-level laboratory performance: TRX ≈ 100 K and analog SRR ≈ 10 dB, improved to ≈ 20 dB with DSBS. The paper also outlines integrated system testing at NAOJ/ATC, commissioning plans for 2026, and estimated 5σ line sensitivities for [O III] 88 µm at z ≈ 10 under stated LMT site assumptions, including a further ~√2 gain from a previously published data-scientific noise-removal method.","tokens_in":8812,"tokens_out":1109,"duration_ms":22786,"significance":"If the laboratory performance holds on-sky, FINER would provide a northern-hemisphere spectral-scanning capability with roughly five times the instantaneous bandwidth of current ALMA, at a collecting area ~40% of ALMA and under the LMT’s atmospheric conditions. That combination is scientifically well motivated by the need for [O III] 88 µm and [C II] 158 µm spectroscopy of luminous z ≳ 10 galaxies identified by JWST and forthcoming wide-field surveys. The manuscript’s strengths are concrete: measured (not merely designed) TRX and SRR values for Band 6+7, explicit use of DSBS to raise SRR, and sensitivity forecasts that propagate those numbers under stated site parameters rather than free-floating claims. The work is therefore a useful status report that anchors subsequent commissioning and first-look science.","major_comments":[{"comment":"Section 2 states that Band 6+7 has achieved commissioning-level performance with TRX ∼ 100 K and analog SRR ∼ 10 dB (enhanced to ∼ 20 dB by DSBS), but the manuscript itself contains no frequency-dependent TRX or SRR curves, no measurement bandwidth, and no statement of how TRX was extracted (Y-factor load temperatures, IF range, LO settings). The quantitative claim is load-bearing for both the abstract and the Figure 2 forecasts; either a summary plot/table of the laboratory data or a clear pointer to the exact measured quantities (with uncertainty) should appear in this paper rather than being deferred entirely to Kang et al. (this conference).","section":null},{"comment":"Figure 2 and the accompanying text present 5σ line sensitivities under TRX = 100 K, SRR = 10/20 dB, PWV = 2.0 mm, elevation 60°, and surface accuracy 100 µm, plus a further ∼√2 from noise removal. The system-temperature formula, the precise way SRR enters the noise budget, and the aperture-efficiency assumption are not written out. Because the figure is used to argue detectability of GN-z11-like lines in 10 h, the calculation should be reproducible from the text alone (even if only by citing a standard radiometer equation with the adopted parameters listed).","section":null}],"minor_comments":[{"comment":"Abstract and §1: “approximately five times wider than current ALMA capabilities” should specify the comparison baseline (e.g., single ALMA baseband width vs. FINER’s simultaneous USB+LSB coverage per polarization) so the factor is unambiguous.","section":null},{"comment":"Figure 1 caption: the continuous-wave injection for DSBS gain calibration is mentioned; a one-sentence note on how often the complex gains are re-measured would help readers assess operational overhead.","section":null},{"comment":"Figure 2: the vertical axis label “5σ Sensitivity of Emission Line [mJy]” and the overlaid atmospheric transmission curve are useful; ensure the final production version has legible axis fonts and that the three SRR/noise-removal cases are distinguishable in grayscale.","section":null},{"comment":"§2: Band 4+5 status is only briefly noted (waveguide components done, mixers under fabrication; interim MMIC 125–163 GHz). A short table or sentence on expected delivery relative to the 2026 installation would clarify the dual-band first-light configuration.","section":null},{"comment":"References: several “this conference” citations (Kang et al., Hagimoto et al.) are appropriate for a proceedings volume; if the manuscript is submitted to a journal, replace or supplement them with archival DOIs or arXiv identifiers when available.","section":null},{"comment":"Typographical: the footnote marker after “√2” and the asterisk defining ALMA band nomenclature appear slightly out of place in the compiled text; check numbering and placement in the final PDF.","section":null}],"recommendation":"minor_revision","confidential_remarks":"This is a solid instrumentation status report whose central laboratory claim is not circular and is presented with appropriate caveats on on-sky performance. It is closer to a conference proceedings contribution than a full instrument paper; if the target venue expects archival-level characterization (full TRX/SRR vs. frequency, stability, etc.), the authors will need the Kang et al. data folded in. I see no reason to reject or demand major redesign of the science case."},"author_rebuttal":null,"desk_editor":{"model":"grok-4.5","letter":"This is a clean instrumentation-status proceeding. The one new, concrete result is that the 210–350 GHz (Band 6+7) 2SB SIS receiver has already reached commissioning-level performance in the lab: TRX ≈ 100 K and analog SRR ≈ 10 dB, raised to ≈ 20 dB by the DRS4 digital sideband-separation path. That measurement, plus the simultaneous two-band warm-optics layout and the 10.24 GHz spectrometer array, is what the paper actually delivers.\n\nThey do the engineering work carefully. The integrated ATC setup is described with enough detail to be useful, the DSBS calibration method is standard and correctly applied, and Figure 2 propagates the measured numbers under stated LMT site assumptions without over-claiming. The science motivation (z > 10 [O III] and [C II] scanning) is clear and the first-look target list is sensible. Citations to the predecessor B4R, the noise-removal paper, and the ALMA WSU context are appropriate; nothing looks circular.\n\nSoft spots are exactly the ones you expect for a pre-install status paper. Band 4+5 mixers are still being fabricated, so they will fly a temporary MMIC. The sensitivity curves rest on the usual unmeasured quantities once the dewar is on the LMT (aperture efficiency, pointing, real atmospheric stability). The √2 noise-removal factor is taken from earlier B4R work and is labeled as such. None of these are hidden or load-bearing errors; they are simply the difference between lab commissioning and on-sky verification planned for 2026.\n\nThis is for the millimeter-instrumentation and high-z spectroscopy communities who need to know what will be available on the LMT and what technology is feeding into ALMA WSU. It is not a discovery paper and does not pretend to be. A serious editor should send it to referees; the measurements are real, the writing is proportional, and the gaps are honestly stated. I would cite the TRX/SRR numbers and the dual-band architecture when discussing northern-hemisphere spectral-scanning capability.","headline":"Solid lab status report: Band 6+7 already hits commissioning TRX ~100 K and DSBS-boosted SRR ~20 dB; on-sky claims remain forecasts.","tokens_in":9650,"tokens_out":546,"would_cite":true,"duration_ms":5709,"reading_group":"no","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"grok-4.5","headline":"A new wideband millimeter receiver for the LMT has reached commissioning-level performance and aims for five-times-ALMA instantaneous bandwidth to study early galaxies.","keywords":["millimeter and submillimeter instrumentation","heterodyne receiver","SIS receiver","LMT","ALMA Wideband Sensitivity Upgrade","high redshift","galaxy formation","interstellar medium"],"falsifier":"Once installed, a 10-hour on-source spectral scan of a known several-mJy [O III] target at z ≈ 10 (e.g., GN-z11) either detects the line at the predicted 5σ level under the stated weather and surface conditions, or it does not.","tokens_in":9604,"feed_emoji":"📡","tokens_out":1085,"duration_ms":9859,"temperature":0.7,"pith_summary":"JWST has found more luminous galaxies in the early Universe than expected, and millimeter spectroscopy of redshifted far-infrared lines such as [O III] 88 µm and [C II] 158 µm is needed to understand how they grew so fast. This paper presents FINER, a dual-receiver system for the Large Millimeter Telescope covering 120–350 GHz (ALMA Bands 4+5 and 6+7) with warm optics that allow simultaneous two-band observations. The 10.24 GHz digital spectrometer array, together with digital sideband separation, is designed to give roughly five times the instantaneous bandwidth of current ALMA. Laboratory tests already show the higher-frequency receiver reaches commissioning-level noise temperature of about 100 K and sideband rejection of about 10 dB, improved to about 20 dB by digital processing. Installation is planned for 2026; the authors outline integrated testing, noise-removal methods, and first-look targets at redshift greater than 10, with projected sensitivity that could detect several-mJy lines such as those from GN-z11 in about 10 hours on-source.","feed_headline":"Wideband LMT receiver hits lab specs for early-galaxy scans","feed_subtitle":"Band 6+7 reaches ~100 K noise and 20 dB sideband rejection; five-times-ALMA bandwidth planned for 2026","key_machinery":"The dual-polarization sideband-separating SIS receivers (IF 3–21 GHz) paired with the 10.24 GHz digital spectrometer array that implements digital sideband separation (DSBS). DSBS compensates amplitude and phase imbalances to raise sideband rejection from ~10 dB to ~20 dB, producing more uniform sensitivity across the wideband where atmospheric transmission varies.","core_discovery":"The 210–350 GHz (Band 6+7) SIS receiver of FINER has already reached commissioning-level laboratory performance: receiver noise temperature approximately 100 K and analog sideband rejection ratio approximately 10 dB, further enhanced to approximately 20 dB by the digital sideband-separation functionality of the DRS4 spectrometer array. Combined with the 10.24 GHz-wide backend and dual-band warm optics, the system is designed to deliver an instantaneous bandwidth about five times wider than current ALMA while remaining sensitive enough for deep spectral scans of z > 10 galaxies once installed on the LMT in 2026.","pith_inferences":["If the laboratory SRR and TRX transfer to the telescope, FINER will fill a northern-sky gap left by ALMA for time-critical or large-area spectroscopic follow-up of JWST/Euclid/Roman candidates.","The same high-Jc SIS mixer techniques and DSBS backend developed for FINER are natural precursors for the ALMA Wideband Sensitivity Upgrade, so laboratory lessons here may accelerate that upgrade.","A successful on-sky demonstration of the noise-removal method at Band 6+7 would make similar post-processing standard for other single-dish wideband spectrometers."],"forward_implications":["FINER can become the most sensitive millimeter spectral-scanning facility in the northern hemisphere for redshifted [O III] and [C II] lines.","Simultaneous two-band observations and five-times-wider instantaneous bandwidth will reduce the number of tunings needed for blind or multi-line redshift searches.","Digital sideband separation plus data-scientific noise removal can push effective sensitivity by an additional factor of roughly √2 beyond the raw receiver performance.","First-look deep spectra of a few z > 10 galaxies will test whether the rapid growth of luminous early systems can be diagnosed with ground-based millimeter lines."],"fun_headline_variants":["FINER 210-350 GHz SIS hits 100 K noise and 20 dB rejection","LMT FINER Band 6+7 reaches commissioning lab performance","Digital sideband separation lifts FINER rejection to 20 dB","Wideband FINER backend targets 5x ALMA span for z>10 scans","Dual-band warm optics ready for FINER LMT first light 2026"],"cache_read_input_tokens":128,"weakest_assumption_plain":"The projected on-sky line sensitivities assume that the laboratory noise temperature, sideband rejection, and noise-removal gain will hold under real LMT conditions after 2026 installation, even though aperture efficiency, pointing, and atmospheric stability have not yet been measured with FINER itself.","fun_headline_variants_meta":{"raw":{"variants":["FINER 210-350 GHz SIS hits 100 K noise and 20 dB rejection","LMT FINER Band 6+7 reaches commissioning lab performance","Digital sideband separation lifts FINER rejection to 20 dB","Wideband FINER backend targets 5x ALMA span for z>10 scans","Dual-band warm optics ready for FINER LMT first light 2026"]},"model":"grok-4.5","effort":"low","cost_usd":0.004586,"raw_usage":{"total_tokens":1359,"prompt_tokens":796,"num_sources_used":0,"completion_tokens":107,"cost_in_usd_ticks":45860000,"prompt_tokens_details":{"text_tokens":796,"audio_tokens":0,"image_tokens":0,"cached_tokens":256},"completion_tokens_details":{"audio_tokens":0,"reasoning_tokens":456,"accepted_prediction_tokens":0,"rejected_prediction_tokens":0}},"tokens_in":796,"tokens_out":107,"duration_ms":4009,"temperature":1.0,"reasoning_tokens":456,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-07-12T03:40:34.940571+00:00","model_set":{"reader":"grok-4.5"},"falsifier":"Once installed, a 10-hour on-source spectral scan of a known several-mJy [O III] target at z ≈ 10 (e.g., GN-z11) either detects the line at the predicted 5σ level under the stated weather and surface conditions, or it does not.","supporting_citations":[],"review_version":1}