{"id":"f4caafd3-9cc9-47c8-b6d4-d5c0bf6261f2","arxiv_id":"1908.02485","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":6.0,"correctness_risk":"low","formal_verification":"none","parameter_count":7,"one_line_summary":"111Cd has no 3/2+ 755-keV level; the 753-keV state is 5/2+, and its g factor and lifetime favor shell-model and particle-rotor descriptions over particle-vibration.","lead":"Coulomb excitation and gamma-ray measurements on 111Cd show that a level previously listed as 3/2+ at 755 keV does not exist, and the observed 753-keV state is 5/2+. New magnetic moments and lifetimes for excited states favor shell-model over particle-vibration descriptions of this weakly collective nucleus.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The 755-keV non-observation claim lacks a quantitative detection limit; with a 2.1 keV separation from the strong 752.8-keV peak, a weak 754.9-keV component could be hidden, so absence does not yet prove misidentification.","rationale":"The reader correctly identifies the absence-of-evidence premise as load-bearing. I make it more specific: because 752.8 and 754.9 keV are separated by only 2.1 keV, the statement that only one peak is observed is not a quantitative null result unless a second peak is explicitly fit and excluded. Reanalysis with a fixed 754.9-keV component would settle this. I also flag the explicit caveat in Sec. IV.B.4 that the 753-keV lifetime is at the limit of the DBLS technique and cannot be determined reliably, which sits uneasily with the quoted 4.0(16) ps in Table V and affects the B(E2) and collectivity interpretation; this should be reconciled, but it is secondary to the 755-state question. The shell-model comparison concerns (unpublished SR88MHJM modifications, unavailable DBLS code, and the 5/2+3 g-factor discrepancy) do not affect the experimental negative claim. Since the requested sensitivity analysis is straightforward and the rest of the evidence is consistent, the existing CONDITIONAL verdict remains appropriate and no change to the reader's verdict is needed.","tokens_in":20210,"tokens_out":8302,"duration_ms":93765,"concrete_test":"Perform a two-peak likelihood fit to the 660-820 keV regions of the present +65-degree particle-gamma spectrum (Fig. 2 inset) and the Chamoli natural-Cd spectrum (Fig. 3), fixing a second transition at 754.9 keV with the same line-shape function as the 752.8-keV peak, and extract a 90% confidence upper limit on its intensity. Then fold that limit through the Coulomb-excitation kinematics and detector efficiencies used in Secs. III.A-D to convert counts to a B(E2; 3/2+ to 1/2+) upper limit. If the implied limit leaves even an uncollective 3/2+ candidate undetectable, the non-observation claim is under-powered; if the limit is below about 1 W.u., the misidentification conclusion is quantitatively supported.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central negative result (Secs. III.B and V) is that the reported 3/2+ 754.9-keV level does not exist and was a misidentification of the 5/2+ 752.8-keV state. The evidence is the absence of a 754.9-keV gamma ray in the present particle-gamma spectra (Fig. 2), the Chamoli natural-Cd spectrum (Fig. 3), and a decay measurement, but no detection limit is derived anywhere in the paper. The two possible lines are only 2.1 keV apart, and the 752.8-keV peak is strong; with HPGe resolution near 750 keV being roughly 2 keV, a weak 755-keV component could hide under the side of the 752.8-keV peak and survive a single-peak fit. The paper never performs a two-peak fit with a line fixed at 754.9 keV, so the displayed spectra do not quantify the maximum permissible intensity of such a component. Without an upper limit, non-observation only excludes a 755 state that is populated strongly enough and decays by an unobscured ground-state branch. A 3/2+ state with small B(E2) to the ground state could remain hidden, and the particle-vibration prediction of a second 3/2+ near 700 keV would not be falsified. A quantitative sensitivity analysis is the missing link in the argument.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper reports a Coulomb-excitation study of 111Cd using particle-gamma coincidence, angular correlations, transient-field g-factor measurements, and Doppler-broadened line shape lifetime measurements. The main experimental claims are: (i) the 752.8-keV 5/2+ state is the only strongly excited level near 755 keV, with an E2 angular correlation confirming its spin; (ii) the reported 3/2+ state at 754.9 keV is a misidentification of this state; and (iii) g(5/2+_3) = +0.5(2) and tau = 4.0(1.0 stat, 1.2 syst) ps. The paper then compares these results with particle-vibration, particle-rotor, and large-scale shell-model calculations. It concludes that the particle-vibration model cannot explain the level structure or g factors, the particle-rotor model has partial success, and the SR88MHJM shell-model reproduces much of the low-excitation structure and g factors.","tokens_in":20544,"tokens_out":5585,"duration_ms":60686,"significance":"The experimental result, if correct, removes a low-lying 3/2+ state from the 111Cd level scheme and thereby removes one of the apparent correspondences between 111Cd and 113Cd; this directly bears on the interpretation of Cd as vibrational. The new g factor and lifetime for the 753-keV state add data at a point where the particle-vibration model fails. The shell-model calculations are cross-checked with previous work, use standard effective charges and g_s quenching rather than fitted observables, and use a published Hamiltonian; the energy RMS deviation of 69 keV is a genuine success. However, the central negative claim (non-existence of the 755-keV level) currently lacks a quantitative detection limit, so the paper needs one more analysis step before the conclusion is fully load-bearing.","major_comments":[{"comment":"The conclusion that the 754.9-keV 3/2+ state is a misidentification of the 752.8-keV 5/2+ state rests on the non-observation of a 754.9-keV line, but no detection limit or two-peak fit is reported anywhere in the paper. With the 752.8-keV peak being strong and the separation only 2.1 keV, a weak 754.9-keV component could hide under the side of the 752.8-keV peak and survive a single-peak fit. Please report an upper limit on the 754.9-keV intensity from a two-peak fit in at least one of the spectra (or state quantitatively what population and ground-state branch are excluded), and soften the claim accordingly if no limit can be derived.","section":"Sec. III.B, Figs. 2 and 3"},{"comment":"The paper reports tau = 4.0(1.0 stat, 1.2 syst) ps for the 753-keV state and uses this lifetime to derive B(E2) values referenced in Tables IX and X, but Sec. IV.B.4 states that the lifetime is at the limit of the DBLS technique and therefore cannot be determined reliably. This inconsistency needs to be resolved: either the lifetime is an adopted result with well-defined validity conditions, or the B(E2) values based on it should carry the same caveat and should not be presented as firm experimental constraints on the models.","section":"Sec. IIID and Sec. IV.B.4, Tables V, IX, X"}],"minor_comments":[{"comment":"Table V reports the 753-keV lifetime as 4.0(16) ps, while the text reports 4.0(±1.0 statistical ±1.2 systematic) ps; the table should give both components or clearly state the combined uncertainty convention.","section":"Table V"},{"comment":"In Table IV, the row for the 752.8-keV state lists only the present measurement and an 'Adopted' value that is identical to it; 'Adopted' is misleading when there is no previous measurement to average with the present result.","section":"Table IV"},{"comment":"The inset caption states that 'no peak at 754.9 keV' is seen; it would be more accurate to say that no statistically significant peak is observed at that energy, pending the upper-limit analysis requested above.","section":"Fig. 2 inset"}],"recommendation":"major_revision","confidential_remarks":"The central concern is the unquantified negative observation; the requested upper-limit analysis is straightforward from the existing spectra and does not require new data. I would support publication after that addition. No concerns about novelty or attribution."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Dear colleague,\n\nWhat you should know: this is a solid experimental paper that probably corrects Nuclear Data Sheets and adds the first g-factor and DBLS lifetime for the 5/2+ 753-keV state in 111Cd. The theoretical comparisons are honest but are the softer half of the paper.\n\nThe experiments are the real content. They confirm the E2 character of the 753-keV transition via angular correlations, measure τ = 4.0(1.0 stat, 1.2 syst) ps, and obtain g = +0.5(2). The case against the originally listed 3/2+ 755-keV state is supported by three independent datasets: your own spectra, the Chamoli natural-Cd data, and a decay measurement, with the early McDonald-Porter work seeing a single peak near 750 keV. That is genuinely persuasive.\n\nThe softest spot is the one the stress-test picks up: there is no quantitative detection limit for a 754.9-keV component. The 752.8-keV peak is strong, the separation is only 2.1 keV, and HPGe resolution at that energy is about 2 keV, so a weakly populated level could hide. The paper never fits a two-peak spectrum with the contaminant fixed at 754.9 keV, and without an upper limit the non-observation argument rests on an assumption about how strongly such a state would be populated. I think that assumption is reasonable if the 755-keV state is the analogue of the strongly excited 681-keV 3/2+ in 113Cd, but the authors should have quantified it. This is a moderate weakness, not a fatal one.\n\nTwo smaller issues: the g factor has 40% relative uncertainty and the DBLS has 30% systematic, so the shell-model underprediction of g(5/2+3) by about two sigma may not mean much. And the SR88MHJM Hamiltonian modifications remain unpublished, with the DBLS code promised elsewhere; that makes the theory less reproducible than the experiment.\n\nWho should read this: nuclear-structure people working on Cd isotopes, g factors, or weak collectivity. It will not settle the vibrational-versus-rotational debate, but it is an honest increment. I would send it to a serious referee with a request for a detection-limit analysis and for the model input details. The central experimental claim is sound.","headline":"A careful experimental study that likely removes a phantom 755-keV level in 111Cd and adds a new g-factor point, though the non-observation claim would be airtight only with a quantitative upper limit.","tokens_in":21182,"tokens_out":3608,"would_cite":true,"duration_ms":34752,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":["21.10.Ky","21.10.Tg","25.70.De","27.60.+j"],"model":"deepseek-v4-flash","headline":"The paper argues that the reported 3/2+ 755-keV state in 111Cd is a misidentification of the 5/2+ 753-keV state, and that shell-model calculations best describe the low-excitation structure.","keywords":["nuclear g factors","Coulomb excitation","cadmium-111","particle-vibration model","particle-rotor model","shell-model calculations","Doppler-broadened line shape","level misidentification"],"falsifier":"Look for a resolved 755-keV gamma ray in 111Cd with high statistics and high resolution, for example in beta-decay or (n,γ) data free of Coulomb-excitation population assumptions; a distinct 755-keV ground-state transition whose intensity is comparable to the 753-keV transition would overturn the misidentification claim. A Coulomb-excitation run with much higher statistics that still shows only one peak near 755 keV would support it.","tokens_in":20009,"feed_emoji":"🧲","tokens_out":10983,"duration_ms":105901,"temperature":0.7,"pith_summary":"This paper reports new spectroscopy of the weakly collective nucleus 111Cd using Coulomb-excitation angular correlations, transient-field g-factor measurements, and Doppler-broadened line-shape lifetimes. It argues that the previously listed 3/2+ state at 755 keV does not exist; the single 753-keV transition belongs to a 5/2+ state with g = +0.5(2) and mean lifetime about 4.0 ps. The authors show that the particle-vibration model, the traditional framework for cadmium isotopes, cannot reproduce the measured g factors or the absence of a second low-lying collective 3/2+ state. A particle-rotor picture does better on magnetic properties but not on the energy spectrum. Large-scale shell-model calculations with the SR88MHJM Hamiltonian reproduce the signs and rough magnitudes of the measured g factors and much of the low-excitation structure, pointing to a microscopic rather than vibrational origin for the collectivity.","feed_headline":"The 755-keV state in 111Cd was a misidentified 753-keV level","feed_subtitle":"New g-factor and lifetime data show a single 5/2+ state at 753 keV; only the shell model reproduces its magnetic moment.","key_machinery":"The load-bearing apparatus is a set of coincident measurements on Coulomb-excited 111Cd recoils: particle-γ angular correlations distinguish E2 from M1 multipolarity and confirm the spin of the 753-keV state; the transient-field technique measures the Larmor precession and yields the g factor; and Doppler-broadened line-shape fits, benchmarked on known even-cadmium lifetimes, give the state lifetime. On the theory side, the comparison turns on the particle-vibration coupling strength $\\xi = 2.2$, a deformed single-particle (Nilsson-type) description at small deformation, and the SR88MHJM shell-model Hamiltonian, an 88Sr-core interaction with orbits up to Z = 50 and N = 82. These tools work together to show that the three models make different predictions for the sign of $g(5/2^+_3)$, the location of the second 3/2+ state, and the E2 strengths, so the measurements can discriminate among them.","core_discovery":"The central experimental discovery is that the previously reported pair of states near 755 keV in 111Cd is actually a single level: the 753-keV 5/2+ state. The angular correlation of its ground-state transition is E2, confirming the 5/2+ assignment, and no 755-keV gamma ray appears in the present data, in natural-cadmium Coulomb-excitation data, or in a decay measurement. The new g factor of this state is +0.5(2), and its mean lifetime from Doppler-broadened line-shape analysis is 4.0(1.0 stat, 1.2 syst) ps, corresponding to a B(E2) of 11.2 W.u. The paper argues that the absence of the 3/2+ state, the positive g factor of the 5/2+3 state, and the strong ground-state E2 strengths are not explained by the particle-vibration model, are qualitatively accommodated by a particle-rotor picture with small deformation, and are best matched by shell-model calculations, which reproduce the signs of all measured g factors and the overall low-lying level pattern.","pith_inferences":["If the removal of the 755-keV level is confirmed, the absence of a 3/2+ analogue to the 113Cd 681-keV state suggests that the particle-core coupling changes sharply between neighbouring odd cadmium isotopes.","The two-standard-deviation gap between the shell-model and measured g factor of the 5/2+3 state may be a sensitive benchmark for interactions that include proton-intruder configurations, which the present model space excludes.","A direct test of the rotational-band interpretation would be to measure the g factor and B(E2) of the tentatively assigned 7/2+ 1047-keV state; a rotational assignment predicts a specific small positive g and a strong E2 transition within the band.","The same experimental combination could be applied to 113Cd to test whether its 681-keV 3/2+ state is the true analogue and to resolve the reported discrepancy between its lifetime and its B(E2) strength."],"forward_implications":["The 755-keV 3/2+ level should be removed from 111Cd level schemes; only the 5/2+ 753-keV state remains near that energy.","The 753-keV 5/2+ state has g = +0.5(2) and a mean lifetime of 4.0(1.0 stat, 1.2 syst) ps, corresponding to a moderately collective B(E2) of about 11 W.u.","The particle-vibration model fails on the sign of $g(5/2^+_3)$ and predicts a second low-lying collective 3/2+ state that is not observed, disfavoring the vibrational interpretation for 111Cd.","A particle-rotor picture with small quadrupole deformation accounts qualitatively for the magnetic moments but cannot reproduce the full energy spectrum.","Shell-model calculations reproduce the signs and approximate magnitudes of measured g factors and key E2 strengths, making the microscopic approach the most promising route for understanding collectivity in this nucleus."],"supporting_citations":[{"why":"The evaluated level scheme containing the reported 3/2+ 755-keV state and the multipolarity assignments re-examined here.","marker":"[24]"},{"why":"The earlier Coulomb-excitation measurement that saw a single peak near 750 keV, supporting the energy misidentification.","marker":"[28]"},{"why":"Natural-cadmium particle-γ coincidence data that show no 755-keV peak and calibrate the transient field for Cd in iron.","marker":"[27]"},{"why":"A decay measurement that also finds a single transition at this energy, independently supporting non-observation of the 755-keV level.","marker":"[25]"},{"why":"The prior g-factor study that set up the particle-rotor versus particle-vibration comparison and the search for the 3/2+ analogue in 111Cd.","marker":"[23]"},{"why":"The earlier transient-field g-factor results for 111Cd low states with which the present measurements are combined.","marker":"[31]"},{"why":"Establishes the SR88MHJM shell-model Hamiltonian and its g-factor systematics for odd cadmium isotopes, the basis for the microscopic comparison.","marker":"[21]"},{"why":"Provides the shell-model code used to perform the large-scale calculations.","marker":"[53]"},{"why":"Supplies the stopping-power tables used in the Doppler-broadened line-shape lifetime fits.","marker":"[30]"}],"fun_headline_variants":["111Cd's 755-keV state is a mirage—real level is 753 keV","New data show 111Cd's 755-keV state is really its 753-keV level","111Cd: 755-keV state was misidentified—it's actually 753 keV","Shell model scores for 111Cd: single 5/2+ state at 753 keV","Magnetic moment and lifetime pin down 111Cd's 753-keV 5/2+ state"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The load-bearing premise is an absence of evidence: the 755-keV transition was not seen in any of three datasets, so the argument assumes a real 3/2+ 755-keV level would have been populated strongly enough by Coulomb excitation and would have decayed with a visible ground-state branch.","fun_headline_variants_meta":{"raw":{"variants":["111Cd's 755-keV state is a mirage—real level is 753 keV","New data show 111Cd's 755-keV state is really its 753-keV level","111Cd: 755-keV state was misidentified—it's actually 753 keV","Shell model scores for 111Cd: single 5/2+ state at 753 keV","Magnetic moment and lifetime pin down 111Cd's 753-keV 5/2+ state"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000507,"raw_usage":{"total_tokens":2572,"prompt_tokens":1149,"completion_tokens":1423,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":765,"completion_tokens_details":{"reasoning_tokens":1295}},"tokens_in":765,"tokens_out":1423,"duration_ms":13353,"temperature":1.0,"reasoning_tokens":1295,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-14T14:43:14.994551+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Look for a resolved 755-keV gamma ray in 111Cd with high statistics and high resolution, for example in beta-decay or (n,γ) data free of Coulomb-excitation population assumptions; a distinct 755-keV ground-state transition whose intensity is comparable to the 753-keV transition would overturn the misidentification claim. A Coulomb-excitation run with much higher statistics that still shows only one peak near 755 keV would support it.","supporting_citations":[{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"The evaluated level scheme containing the reported 3/2+ 755-keV state and the multipolarity assignments re-examined here."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"The earlier Coulomb-excitation measurement that saw a single peak near 750 keV, supporting the energy misidentification."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Natural-cadmium particle-γ coincidence data that show no 755-keV peak and calibrate the transient field for Cd in iron."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"A decay measurement that also finds a single transition at this energy, independently supporting non-observation of the 755-keV level."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"The prior g-factor study that set up the particle-rotor versus particle-vibration comparison and the search for the 3/2+ analogue in 111Cd."},{"cited_title":"Schmidt, K","cited_arxiv_id":null,"evidence_quote":"The earlier transient-field g-factor results for 111Cd low states with which the present measurements are combined."},{"cited_title":"Bandyopadhyay, S","cited_arxiv_id":null,"evidence_quote":"Establishes the SR88MHJM shell-model Hamiltonian and its g-factor systematics for odd cadmium isotopes, the basis for the microscopic comparison."},{"cited_title":"Raghavan, Atomic Data and Nuclear Data Tables 42, 189 (1989)","cited_arxiv_id":null,"evidence_quote":"Provides the shell-model code used to perform the large-scale calculations."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Supplies the stopping-power tables used in the Doppler-broadened line-shape lifetime fits."}],"review_version":1}