{"id":"ac81d4a9-5e61-463b-90d0-979150081eee","arxiv_id":"2506.13948","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":10,"one_line_summary":"New cross section data for antimony(p,x) reactions up to 200 MeV, plus a TALYS model tuning that improves fits for tellurium channels but leaves pre-equilibrium physics underdetermined.","lead":"This paper reports new measurements of nuclear reaction cross sections for making the medical isotopes tin-117m and tellurium-119m by firing protons at natural antimony, covering energies up to 200 MeV. It also tests how well the TALYS nuclear reaction code can reproduce these measurements after adjusting model parameters.","discovery_kind":"new_application","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Secondary-particle contamination of the BNL 100–200 MeV Te data is not quantitatively bounded; the fitted TALYS parameters may inherit this systematic.","rationale":"The reader's concern about secondary-particle contamination of the Te channels is directionally correct and identifies the right region of the paper (Sec. IV). However, the reader specifically invokes secondary neutrons as the contamination mechanism for Te. A neutron cannot increase Z from Sb (Z=51) to Te (Z=52) in a single reaction, so this specific mechanism is not physically viable. The broader risk is secondary protons produced in the thick BNL degraders, which can create Te via (p,x) reactions; this risk is not addressed by the paper and is arguably more serious than the neutron channel. Because the paper excludes Sb data above 100 MeV but uses Te data from the same high-energy BNL stack without a quantitative secondary-particle bound, the central modeling claim is conditional rather than established. The concrete FLUKA/MCNP test would settle whether the contamination is negligible. If the test shows negligible secondary Te production, the central claim would be strengthened and the paper could move toward acceptance; if not, the fitted parameters would need re-derivation. Since the reader's verdict is already CONDITIONAL, I recommend no change to the verdict: this concern is a reason for the condition, not a reason to reject the work outright. The experimental dataset itself appears carefully analyzed and valuable; the outstanding issue is the unquantified systematic on the high-energy points that most influence the TALYS optimization.","tokens_in":45582,"tokens_out":10056,"duration_ms":122026,"concrete_test":"Model the BNL stack with FLUKA or MCNP6: 200 MeV protons on the Table XV geometry, scoring secondary proton and neutron spectra at each natSb foil. Fold these spectra with TALYS 1.95 natSb(p,x)119mTe and natSb(n,x)119mTe cross sections (using the paper's optimized parameters and default parameters separately). If the predicted secondary-induced 119mTe yield exceeds ~5% of the measured value at any BNL energy point, the high-energy Te data and the fitted TALYS parameters are not robust; if the yield is below ~1% at all points, the assumption of negligible contamination is validated. Repeat the same check for 117mSn.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The modeling claim rests on the seven Te channels measured at BNL between 102 and 188 MeV. The paper explicitly excludes Sb data above 100 MeV because secondary neutrons produce same-Z Sb nuclei (Sec. IV), but it does not apply an equivalent exclusion or quantitative correction to the Te channels that drive the parameter fit. The BNL stack contains thick aluminum degraders (Table XV, up to ~4.7 g/cm2), which are a plausible source of secondary protons as well as neutrons; secondary protons, unlike neutrons, can produce Te (Z=52) from Sb (Z=51) via (p,x) reactions in downstream foils. No transport calculation, measured secondary-particle fluence, or sensitivity estimate is provided to bound this contribution. If secondary-induced Te production is non-negligible, the fitted rspincut, optical-model, and pre-equilibrium parameters would be biased, and the reported chi2 improvement factors would not be transferable. The paper acknowledges the need for 'further studies of secondary neutron production' and states that stacked-target data 'cannot unambiguously assign' pre-equilibrium parameters, but the high-energy Te data are treated as clean. This is the most load-bearing gap: the BNL points are also the least constrained in beam-energy determination because only one monitor reaction was used, yielding a shallow chi2 minimum (Sec. III C).","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"This paper reports new stacked-target activation measurements of natSb(p,x)117mSn and natSb(p,x)119mTe, together with 22 co-produced residual-product cross sections and monitor-foil cross sections, for proton energies up to 200 MeV from LBNL, LANL, and BNL. The analysis uses a variance-minimization procedure to determine beam current and energy, and the data are compared with TALYS 1.95 calculations. A set of physics-motivated parameter adjustments (rspincut=0.4, spincutmodel=2, w1adjust(n)=2.5, w2adjust(n)=0.6, preeqmode=1, m2constant=2, m2limit=0.8, m2shift=1.8, rpinu=rnupi=rnunu=1.5) is reported to improve reduced chi2 for the dominant Te channels by factors between 2.16 and 56.78, with validation on cumulative and smaller independent channels.","tokens_in":45888,"tokens_out":9044,"duration_ms":94049,"significance":"The experimental dataset is the strongest part of the paper: the activation analysis is detailed, the decay-gamma assignments are documented, monitor foils and variance minimization are used carefully, and the data will be a useful EXFOR entry for medical-isotope production and for testing reaction models. If the modeling improvements were independently confirmed, the spin cut-off and optical-model adjustments would be a valuable step toward better proton-reaction modeling. The modeling conclusions are not yet established at the same level: the parameters are fit to the same data used for the improvement claim, the paper itself acknowledges that pre-equilibrium parameters cannot be uniquely assigned, and the high-energy Te data have not been shown to be free of secondary-particle contamination.","major_comments":[{"comment":"The parameter optimization is driven by the seven Te channels, and the BNL data points at 102-188 MeV are the only high-energy constraints on the pre-equilibrium region. The paper excludes Sb residual data above 100 MeV because of secondary-neutron production (Section IV), but it does not apply an equivalent exclusion or correction to the Te channels. The BNL stack contains thick aluminum degraders (e.g., 4668.98 mg/cm2 in Table XV), which can generate secondary protons; unlike secondary neutrons, secondary protons can produce Te (Z=52) from Sb (Z=51) in downstream foils. No transport calculation, measured secondary fluence, or sensitivity estimate is provided to bound this contribution. If secondary-proton production of Te is not negligible, the fitted rspincut, optical-model, and pre-equilibrium parameters would be biased and the Table VII improvement ratios would not be transferable. Please quantify this contribution or explicitly restrict the high-energy modeling conclusions.","section":"Section IV; Table XV"},{"comment":"There is an inconsistency in the goodness-of-fit definition. Equation (11) includes a factor 1/Nc multiplying the sum over channels, but the weights wc defined in Eqs. (12) and (13) are already normalized so that they sum to unity over channels. With the stated definitions, chi2_tot = (1/Nc) * sum_c chi2_c * wc is not the weighted average implied by the text, and the absolute values in Table V depend on this choice. Although the improvement ratios may be robust to an overall factor, this normalization must be corrected and the quoted values recalculated.","section":"Section IV D, Eqs. (11)-(13)"},{"comment":"The reported improvement factors in Table VII are in-sample: the same 12 independent channels were used both to select the TALYS parameters and to evaluate the fit. The validation channels (Table VIII) are a genuine out-of-sample check within the same dataset, but they were selected after the optimization and are not independent of the experimental conditions. Please present the Table VII ratios as fit diagnostics, add a sensitivity analysis that removes one channel or one energy region at a time, and state explicitly that the parameter set has not been tested on an independent dataset.","section":"Section IV D-F; Table VII"},{"comment":"The BNL points above 100 MeV carry the high-energy part of the modeling claim, but the BNL beam-energy and current determination relies on a single monitor reaction, natCu(p,x)58Co, and the paper notes this gives a relatively shallow reduced-chi2 minimum. The Table II energy uncertainties (e.g., +/-2.1 to +/-3.1 MeV) are propagated, but the normalization of these points is weakly constrained. A sensitivity study showing how the fitted parameters and improvement ratios change under alternative stopping-power adjustments, or with the natCu(p,x)56Co data included as a consistency check, would substantially strengthen the high-energy conclusions.","section":"Section III C; Table II"},{"comment":"The paper's own conclusion that stacked-target measurements 'cannot unambiguously assign the correct pre-equilibrium parameters independently' and that outgoing neutron spectra are needed is an important caveat that is not reflected in the abstract or in the presentation of Table X as the optimized parameter set. The abstract and Section IV F should be revised to present the parameter adjustments as illustrative constraints on TALYS parameters, not as a uniquely determined or globally validated parameter recommendation.","section":"Section V"}],"minor_comments":[{"comment":"The sentence 'The decay gamma spectroscopy used in this research is avalable for access' contains a typo; 'avalable' should be 'available'.","section":"Section V"},{"comment":"In Figure 13, panel (c) is captioned '123mTe' but the plotted curve and the surrounding text concern natSb(p,x)121(m)Te; relabel the panel.","section":"Figure 13"},{"comment":"Table II is very dense and some entries, such as the 117Te rows, have large relative uncertainties; a machine-readable supplement with pointwise cross sections and covariance information would improve usability and reproducibility.","section":"Table II"},{"comment":"The sentence 'The existing experimental data for natCu(p,x)56Co was leveraged as a validation check for the BNL results, but these data were not incorporated into the final calculations' would benefit from a brief description of what the validation check showed, since it is the only consistency check for the BNL normalization.","section":"Section III C"}],"recommendation":"major_revision","confidential_remarks":"The experimental data quality is good and the EXFOR submission is a clear positive. The modeling section needs revision before acceptance: the secondary-particle contamination of the BNL Te data is the main technical risk, and the in-sample nature of the fit should be presented more cautiously. I would be willing to accept after a revision that either provides a quantitative bound on the BNL Te contamination or tempers the modeling claims accordingly; rejection is not warranted on the present evidence."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"The dataset is the real contribution here: 43 energy points across three facilities for natSb(p,x)117mSn and 119mTe, plus 22 co-produced channels and the monitor foil measurements. The activation analysis is careful—the dedicated 2022 LBNL run to resolve the 158.6 keV interference is exactly the kind of follow-up this work needs, and the variance-minimization procedure is well established in the group’s prior papers. The paper is also honest about what it can and cannot claim: it explicitly says stacked-target data cannot unambiguously assign pre-equilibrium parameters, and it flags secondary neutron production as a concern.\n\nThe spin-cutoff finding (rspincut=0.4, spincutmodel=2) is the most interesting physics result, and it agrees with Rodrigo et al.’s independent compilation. That agreement gives it more weight than a pure in-sample fit. The validation against cumulative channels is a reasonable cross-check, even if it is not a truly independent test.\n\nThe soft spot is exactly where the stress-test points. The paper excludes Sb data above 100 MeV because secondary neutrons produce same-Z Sb nuclei, but it keeps the seven BNL Te points that drive the parameter fit. The BNL stack contains aluminum degraders up to 4.7 g/cm2; secondary protons from those degraders can produce Te from Sb, and the paper offers no transport estimate or sensitivity bound to show this is negligible. The BNL energy determination is also the weakest of the three facilities—only one monitor reaction, with a shallow chi2 minimum. Those two issues together mean the high-energy Te data, and by extension the fitted parameters, carry a systematic that is acknowledged in prose but not quantified. This does not sink the experimental dataset, which stands on the lower-energy LANL/LBNL data and the overall consistency, but it does limit how much weight the modeling conclusions should receive.\n\nOne other gap: the paper does not compare its new measurements against existing EXFOR data for these channels. For a nuclear data paper, that comparison is standard practice and would help the reader judge consistency. The promise to upload to EXFOR after publication is good but not the same as showing the comparison now.\n\nThe paper deserves a serious referee. The data are new and useful for medical isotope production, and the modeling exploration is a legitimate step forward even if the parameter set is not uniquely constrained. I would ask the authors to add a quantitative bound on secondary contributions to the BNL Te points, and to include an EXFOR comparison before acceptance. Word to the editor: send it out, but push on the secondary-particle question.","headline":"New cross sections for medically relevant Sn/Te isotopes up to 200 MeV, but the TALYS spin-cutoff and pre-equilibrium claims lean on BNL points that may carry unquantified secondary-particle contamination.","tokens_in":46459,"tokens_out":2383,"would_cite":true,"duration_ms":31449,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":["25.40.-h","25.40.Sc","27.60.+j"],"model":"deepseek-v4-flash","headline":"Proton data on antimony sharpen predictions for two medical isotopes","keywords":["cross section","proton-induced reactions","tin-117m","tellurium-119m","stacked target activation","TALYS","isomeric ratio","Auger therapy"],"falsifier":"Measure the $\\mathrm{^{nat}Sb}(p,x)^{119m}\\mathrm{Te}$ and $\\mathrm{^{nat}Sb}(p,x)^{121m}\\mathrm{Te}$ excitation functions using a target arrangement that suppresses secondary neutrons (for example, thin degraders of low-Z material or an active neutron veto), and compare the results with the stacked-target data presented here. If the tellurium cross sections or isomer ratios shift significantly when the neutron fluence is reduced, the fitted TALYS parameters are biased by neutron-induced contributions and the claimed physical adjustments would need to be revisited.","tokens_in":45427,"feed_emoji":"☢️","tokens_out":3568,"duration_ms":44047,"temperature":0.7,"pith_summary":"This paper reports new measured cross sections for producing the Auger-therapy isotopes $\\mathrm{^{117m}Sn}$ and $\\mathrm{^{119m}Te}$ by proton bombardment of natural antimony, covering incident energies up to 200 MeV, together with 22 co-produced reaction channels. It then uses these data to test and adjust the reaction-model code TALYS 1.95, finding that a set of physically motivated parameter changes greatly improves the modeled excitation functions, especially for tellurium isomers. The measurements matter because $\\mathrm{^{117m}Sn}$ and the $\\mathrm{^{119}Sb}$ daughter of $\\mathrm{^{119m}Te}$ are promising for targeted radiotherapy, and better reaction modeling helps plan isotope production and assess radionuclidic impurities.","feed_headline":"Proton data sharpen medical-isotope reaction models","feed_subtitle":"New antimony cross sections up to 200 MeV cut tellurium fit error by up to 57 times.","key_machinery":"The central object is the spin cut-off parameter $\\sigma^2$, the width of the angular-momentum distribution in TALYS's phenomenological level-density models, together with the weighted $\\chi^2$ goodness-of-fit metric that lets the largest independent channels drive the optimization. The spin cut-off controls how much population flows to high-spin isomers, and reducing it to 0.4 is what repairs the measured $^{119g/m}$Te and $^{121g/m}$Te ground-state-to-isomer ratios. Supporting machinery includes the stacked-target activation method with monitor-foil current and energy characterization by variance minimization, and two channel-weighting schemes (cumulative cross-section and maximum cross-section) that balance the fit between the many low-energy points and the few high-energy points.","core_discovery":"The paper establishes that default TALYS 1.95 systematically overpopulates high-spin isomeric states and underpopulates low-spin ground states in proton-induced reactions on antimony near A = 119-123. A parameter set with reduced spin cut-off ($\\texttt{rspincut}=0.4$), a shell-effect-aware spin-cut-off model ($\\texttt{spincutmodel}=2$), a deeper and narrower imaginary neutron volume potential ($\\texttt{w1adjust}(n)=2.5$, $\\texttt{w2adjust}(n)=0.6$), analytical pre-equilibrium transition rates ($\\texttt{preeqmode}=1$), and adjusted exciton matrix-element parameters ($\\texttt{m2constant}=2$, $\\texttt{m2limit}=0.8$, $\\texttt{m2shift}=1.8$, $\\texttt{rpinu}=\\texttt{rnupi}=\\texttt{rnunu}=1.5$) reduces the reduced-$\\chi^2$ for the tellurium channels by factors between 2.16 and 56.78 relative to defaults. The same parameters improve the overall fit to cumulative validation channels, while some antimony and indium channels fit worse, which the paper attributes to co-production of neutron-deficient products by secondary neutrons in the target stacks.","pith_inferences":["A natural extension of the spin-cut-off result is to test whether $\\texttt{rspincut}=0.4$ also improves isomer-ratio predictions for proton-induced reactions on neighboring target elements such as tin and iodine, which would indicate a generic deficiency in default spin distributions rather than a quirk of antimony.","Because the optimized parameters were chosen to fit tellurium channels specifically, applying them to other targets may overcorrect for spin effects; a cross-validation against independent isomer-ratio data outside the fitted mass region would test the generality of the adjustment.","The paper's secondary-neutron hypothesis could be tested directly by comparing measurements taken with and without high-Z degraders, or by placing neutron detectors around the stack and correlating neutron yield with the excess antimony production.","If the decrease in spin cut-off reflects the prolate deformation neglected by the default model, then independent nuclear-structure calculations of level densities for deformed $^{119,121}$Te could corroborate or refute the physical interpretation of the fitted parameter."],"forward_implications":["The measured $\\mathrm{^{nat}Sb}(p,x)$ cross sections provide new experimental benchmarks for $\\mathrm{^{117m}Sn}$ and $\\mathrm{^{119m}Te}$ production, including contaminant channels such as $\\mathrm{^{113}Sn}$, $\\mathrm{^{121g,m}Te}$, and $\\mathrm{^{123m}Te}$ that affect radionuclidic purity for medical use.","If the optimized TALYS parameters are adopted for proton-induced reactions near $A \\approx 120$-$130$, predicted isomer-to-ground-state ratios for other tellurium and nearby isotopes should improve substantially.","The persistent misfit of neutron-deficient antimony channels is evidence that secondary neutrons generated inside high-energy target stacks measurably contribute to isotope production, so future stacked-target experiments should account for or suppress this neutron field.","The finding that stacked-target activation alone cannot unambiguously determine pre-equilibrium parameters implies that outgoing neutron spectral measurements are needed to fix the underlying physics of the model.","The cross-section dataset, once submitted to the EXFOR database, will serve as a benchmark for future nuclear reaction model evaluations and for isotope-production simulation codes."],"supporting_citations":[{"why":"Establishes the earlier stacked-target measurements and the precedent of adjusting TALYS pre-equilibrium parameters that this work extends.","marker":"[9]"},{"why":"Supplies the IAEA-recommended monitor reactions used to characterize beam current and proton energy in the stacked-target analysis.","marker":"[16]"},{"why":"The TALYS 1.95 manual defines the level-density, pre-equilibrium, and optical-model parameters that the paper adjusts.","marker":"[28]"},{"why":"Provides the recent compilation of spin cut-off parameters that supports the reduction to rspincut=0.4.","marker":"[29]"},{"why":"The Koning-Delaroche optical-model potential is the default whose imaginary neutron-volume terms are modified by w1adjust and w2adjust.","marker":"[31]"},{"why":"Introduces the variance-minimization technique used to reduce energy and current uncertainty in stacked-target experiments.","marker":"[13]"},{"why":"Provides the correlation metrics and sandwich-estimator approach used to quantify correlated uncertainties.","marker":"[15]"},{"why":"Companion prior work that also used measured cross sections to guide TALYS parameter adjustments, providing a comparative baseline.","marker":"[10]"}],"fun_headline_variants":["Proton data slash tellurium model error by up to 57x","Antimony proton cross sections improve TALYS fits 57x","High-spin errors fixed: new proton data for isotope models","Tellurium-119m error drops 57x with new antimony data","Spin-cutoff fix cuts tellurium model error 57x"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The optimized model parameters are trustworthy only if the tellurium reaction channels that drive the fit are produced purely by protons and are not also fed by secondary neutrons created in the target stack.","fun_headline_variants_meta":{"raw":{"variants":["Proton data slash tellurium model error by up to 57x","Antimony proton cross sections improve TALYS fits 57x","High-spin errors fixed: new proton data for isotope models","Tellurium-119m error drops 57x with new antimony data","Spin-cutoff fix cuts tellurium model error 57x"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000644,"raw_usage":{"total_tokens":3001,"prompt_tokens":1024,"completion_tokens":1977,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":640,"completion_tokens_details":{"reasoning_tokens":1882}},"tokens_in":640,"tokens_out":1977,"duration_ms":14488,"temperature":1.0,"reasoning_tokens":1882,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-07T00:25:01.963853+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Measure the $\\mathrm{^{nat}Sb}(p,x)^{119m}\\mathrm{Te}$ and $\\mathrm{^{nat}Sb}(p,x)^{121m}\\mathrm{Te}$ excitation functions using a target arrangement that suppresses secondary neutrons (for example, thin degraders of low-Z material or an active neutron veto), and compare the results with the stacked-target data presented here. If the tellurium cross sections or isomer ratios shift significantly when the neutron fluence is reduced, the fitted TALYS parameters are biased by neutron-induced contributions and the claimed physical adjustments would need to be revisited.","supporting_citations":[{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Establishes the earlier stacked-target measurements and the precedent of adjusting TALYS pre-equilibrium parameters that this work extends."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Supplies the IAEA-recommended monitor reactions used to characterize beam current and proton energy in the stacked-target analysis."},{"cited_title":"Vidmar, M","cited_arxiv_id":null,"evidence_quote":"Provides the recent compilation of spin cut-off parameters that supports the reduction to rspincut=0.4."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"The Koning-Delaroche optical-model potential is the default whose imaginary neutron-volume terms are modified by w1adjust and w2adjust."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Introduces the variance-minimization technique used to reduce energy and current uncertainty in stacked-target experiments."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Provides the correlation metrics and sandwich-estimator approach used to quantify correlated uncertainties."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Companion prior work that also used measured cross sections to guide TALYS parameter adjustments, providing a comparative baseline."}],"review_version":1}