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arxiv: 2606.27064 · v1 · pith:AJIRPEUPnew · submitted 2026-06-25 · ⚛️ nucl-ex · physics.ins-det

Half-Life Measurements of ¹¹⁰Sn, ¹¹³Sn, ^(117m)Sn, and ^(123m)Sn Produced via Photon Activation of Natural Tin

O Nusair , D Devries , M Toto-Gonzalez This is my paper

Pith reviewed 2026-06-26 01:38 UTC · model grok-4.3

classification ⚛️ nucl-ex physics.ins-det
keywords half-life measurementtin isotopes117mSnphoton activationgamma-ray spectroscopynuclear data evaluationisomeric state
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The pith

The half-life of 117mSn is measured as 13.95 days, longer than the 13.76 days recommended by Nuclear Data Sheets.

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

The paper measures the ground-state half-lives of 110Sn and 113Sn along with the isomeric half-lives of 117mSn and 123mSn by activating natural tin with photons and tracking gamma emissions over months. Three of the four results match existing Nuclear Data Sheets values within combined uncertainties. The 117mSn result of 13.95 days deviates from the recommended 13.76 days by a z-score large enough to indicate a systematic difference rather than random fluctuation. Such a discrepancy matters because half-life data enter calibration standards, radiation dosimetry calculations, and models of stellar nucleosynthesis that rely on tin isotopes.

Core claim

Independent half-life determinations from photon-activated natural tin yield 4.165(25) h for 110Sn, 116.08(94) d for 113Sn, 13.95(1) d for 117mSn, and 39.95(12) min for 123mSn. The first three and the last agree with NDS values within uncertainties, while the 117mSn value differs from 13.76(4) d at a statistically significant level, pointing to a possible systematic offset in prior evaluations.

What carries the argument

Gaussian peak fitting applied to the time series of counts in the 158.56 keV gamma transition to construct the decay curve for 117mSn.

If this is right

  • Applications that use 117mSn decay data for dosimetry or calibration would shift if the longer half-life is adopted.
  • Nuclear data evaluations should re-examine the 117mSn entry in light of the new measurement.
  • The three isotopes whose half-lives agree can serve as cross-checks for future activation experiments.
  • Photon activation of natural tin provides a practical route for producing these isotopes without chemical separation.

Where Pith is reading between the lines

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

  • A confirmed longer half-life for 117mSn would alter the weighting of this isomer in any cumulative yield calculations that combine multiple production paths.
  • The same activation-plus-spectroscopy method could be applied to other tin isomers whose evaluated half-lives rest on single older datasets.
  • If the discrepancy survives further checks, it may trace to differences in how background subtraction or dead-time corrections were handled in earlier work.

Load-bearing premise

The selected gamma-ray peaks arise solely from the listed transitions of the target isotopes with no significant overlapping lines or time-varying background contributions from contaminants.

What would settle it

An independent half-life measurement of 117mSn performed with a different production route or detector that returns a value statistically consistent with 13.76 d would falsify the reported discrepancy.

Figures

Figures reproduced from arXiv: 2606.27064 by D Devries, M Toto-Gonzalez, O Nusair.

Figure 1
Figure 1. Figure 1: PHITS Sato et al. (2024) simulation of the irradiation setup. The plate-based tantalum converter (blue disks) is cooled by water flowing between the [PITH_FULL_IMAGE:figures/full_fig_p003_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: PHITS Sato et al. (2024) simulation results for a 40 MeV electron beam (directed from left to right along the [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: Energy calibration curve obtained by fitting channel centroids (blue [PITH_FULL_IMAGE:figures/full_fig_p004_3.png] view at source ↗
Figure 5
Figure 5. Figure 5: Efficiency calibration curve obtained by fitting the empirical function to measured full-energy peak efficiencies from a 229Th disk source. The top panel shows the data with the fitted function, while the bottom panel presents standardized residuals with a shaded ±3σ band. The fit quality is characterized by a chi-square of χ 2 = 14.374 with NDF = 5. 2.3. Overview of Spectral Evolution [PITH_FULL_IMAGE:fi… view at source ↗
Figure 4
Figure 4. Figure 4: Resolution calibration curve showing the measured standard devia [PITH_FULL_IMAGE:figures/full_fig_p004_4.png] view at source ↗
Figure 6
Figure 6. Figure 6: Full γ spectra collected at 1 hour (red), 5 hours (blue), and 50 hours (green) post-irradiation. Counting times were 3, 20, and 60 minutes, respectively. Isotopes contributing major peaks are labeled. where η is the mixture weight, C is the net area under the peak with µ channels as the peak centroid, σ the peak width, τ1,2 the tail parameters, and b, c the background terms. Centroid, width, tail parameter… view at source ↗
Figure 7
Figure 7. Figure 7: Twenty sequential γ-ray spectra for 110Sn, recorded between 6 h 8 min and 7 h 14 min post-irradiation. The panels are arranged to reflect the temporal evolution of the spectra, progressing from the top-left to the bottom-right across rows. The dominant peak at channel 1118.38 corresponds to the 280.49 keV transition of 110Sn. Each spectrum was acquired over a 180 s live counting interval. The detector dead… view at source ↗
Figure 8
Figure 8. Figure 8: Sequential spectra for 117mSn between 5–15.5 hours (top-left to bottom-right panels) post-irradiation, fitted with a triple-Gaussian model. The main peak at channel (peak centroid) 631.663 corresponds to 158.56 keV (117mSn), flanked by peaks at channels 621.955 (156.2 keV) and 638.784 (160.34 keV), from 117mSn and 123mSn, respectively. 6 [PITH_FULL_IMAGE:figures/full_fig_p006_8.png] view at source ↗
Figure 9
Figure 9. Figure 9: illustrates the decay behavior of 110Sn derived from the 280.49 keV γ line. The fit quality is characterized by χ 2 /ndf = 388.4/325 and p = 8.96 × 10−3 , indicating a sta￾tistically acceptable model. The extracted half-life is: T1/2 110Sn g.s.  = (4.165 ± 0.025) h, which is in close agreement with the NDS recommended value of (4.154 ± 0.004) h Gürdal and Kondev (2012). 3.2. 113Sn Decay Analysis [PITH_FU… view at source ↗
Figure 10
Figure 10. Figure 10: shows the activity-versus-time dataset and the single-exponential fit for the 391.697 keV line of 113Sn. The fit quality is evident (χ 2 /ndf = 471.9/457, p = 0.305), indi￾cating that a single-component exponential decay adequately describes the data over the acquisition period. From the fit to Eq. (9), we obtain: T1/2 113Sn g.s.  = (116.08 ± 0.94) d. (10) This value agrees with the evaluated recommendat… view at source ↗
Figure 12
Figure 12. Figure 12: shows the decay analysis for 123mSn based on its characteristic 160.34 keV γ emission. The fit was per￾formed following the same iterative correction approach, yield￾ing χ 2 /ndf = 15.73/17 and p = 0.543. The extracted half-life is: T1/2 123mSn = (39.95 ± 0.12) min. Compared to the NDS recommended value of (40.06 ± 0.02) min Chen (2021), the difference is small. 3.5. Summary of Results [PITH_FULL_IMAGE:… view at source ↗
Figure 11
Figure 11. Figure 11: presents the decay analysis for 117mSn using the 158.56 keV line. The fit quality is evident (χ 2 /ndf = 312.4/305, p = 0.389), and the extracted half-life is: T1/2 117mSn = (13.95 ± 0.01) d. Compared to the NDS recommended value of (13.76 ± 0.04) d Blachot (2002), the deviation is small but statisti￾cally significant. Such differences can propagate into decay￾correction protocols and dosimetric calculat… view at source ↗
read the original abstract

We report independent determinations of the ground-state half-lives of $^{110}$Sn, $^{113}$Sn, and the isomeric states $^{117\mathrm{m}}$Sn (J$^{\pi} = 11/2^{-}$) and $^{123\mathrm{m}}$Sn (J$^{\pi} = 3/2^{+}$), produced via photon activation of natural tin using a TT-300HE Rhodotron accelerator. The activated samples were monitored over several months using a high-purity germanium (HPGe) detector. Time-dependent $\gamma$-ray spectra were analyzed using Gaussian peak fitting for the \SI{280.49}{keV}, \SI{391.697}{keV}, \SI{158.56}{keV}, and \SI{160.34}{keV} transitions, yielding half-lives of \SI{4.165(25)}{h} for $^{110}$Sn, \SI{116.08(94)}{d} for $^{113}$Sn, \SI{13.95(1)}{d} for $^{117\mathrm{m}}$Sn, and \SI{39.95(12)}{min} for $^{123\mathrm{m}}$Sn. Agreement with Nuclear Data Sheets (NDS) recommended values is generally observed for $^{110}$Sn, $^{113}$Sn, and $^{123\mathrm{m}}$Sn, with deviations consistent within combined uncertainties when quantified using standardized differences (z-scores). In contrast, $^{117\mathrm{m}}$Sn exhibits a statistically significant deviation from the evaluated value of \SI{13.76(4)}{d}, with a z-score indicating a discrepancy well beyond expected statistical fluctuations. This result suggests a systematic difference warranting further investigation, with potential implications for applications relying on precise decay data, including calibration, dosimetry, and astrophysical modeling.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

1 major / 0 minor

Summary. The manuscript reports independent half-life measurements for 110Sn (4.165(25) h), 113Sn (116.08(94) d), 117mSn (13.95(1) d), and 123mSn (39.95(12) min) produced by photon activation of natural tin on a Rhodotron accelerator. Time series of HPGe gamma spectra are analyzed via Gaussian peak fitting to the 280.49 keV, 391.697 keV, 158.56 keV, and 160.34 keV transitions, respectively; the resulting values are compared to NDS recommendations via z-scores, showing agreement within uncertainties for three isotopes but a statistically significant deviation for 117mSn.

Significance. If the 117mSn discrepancy is confirmed after validation of the spectral analysis, the result would warrant updating the evaluated half-life and could affect applications in calibration, dosimetry, and astrophysical modeling. The work supplies new experimental data from a controlled activation setup and direct decay-curve fitting, providing a useful independent check on existing evaluations.

major comments (1)
  1. [Abstract] Abstract (spectral analysis paragraph): The reported 13.95(1) d value for 117mSn and its z-score discrepancy with the NDS value of 13.76(4) d are extracted solely from Gaussian fits to the 158.56 keV transition. Because natural tin and bremsstrahlung activation open multiple (γ,n), (γ,p), and isomeric channels, the manuscript must explicitly demonstrate that this peak receives no measurable contribution from overlapping transitions, contaminants, or time-dependent backgrounds; without such verification (e.g., multi-component fits, purity tests, or background spectra), the deviation cannot be attributed unambiguously to a true half-life difference rather than an analysis artifact. This assumption is load-bearing for the central claim of a systematic discrepancy.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their careful review and constructive comments on our work. We address the major comment below.

read point-by-point responses

  1. Referee: [Abstract] Abstract (spectral analysis paragraph): The reported 13.95(1) d value for 117mSn and its z-score discrepancy with the NDS value of 13.76(4) d are extracted solely from Gaussian fits to the 158.56 keV transition. Because natural tin and bremsstrahlung activation open multiple (γ,n), (γ,p), and isomeric channels, the manuscript must explicitly demonstrate that this peak receives no measurable contribution from overlapping transitions, contaminants, or time-dependent backgrounds; without such verification (e.g., multi-component fits, purity tests, or background spectra), the deviation cannot be attributed unambiguously to a true half-life difference rather than an analysis artifact. This assumption is load-bearing for the central claim of a systematic discrepancy.

    Authors: We agree that explicit verification of peak purity for the 158.56 keV transition is necessary to support the claimed discrepancy. The full manuscript describes the use of Gaussian fitting on time-series HPGe spectra and notes consistency with known decay schemes, but we acknowledge that additional explicit checks (such as background spectra, multi-component fits, and contaminant searches) were not highlighted sufficiently. In the revised manuscript we will add a dedicated paragraph and supporting figure(s) detailing these purity tests, including results from attempts to fit additional components and examination of possible overlapping transitions from other Sn isotopes or activation products. This will allow unambiguous attribution of the observed deviation. revision: yes

Circularity Check

0 steps flagged

No circularity: purely experimental half-life extraction from direct decay curves

full rationale

The paper performs photon activation of natural tin followed by time-series HPGe gamma spectroscopy. Half-lives are obtained by Gaussian peak fitting to extract count rates for specific transitions (280.49 keV, 391.697 keV, 158.56 keV, 160.34 keV) and then fitting exponential decay curves to those rates. These measured values are compared to external NDS recommended values using z-scores. No derivation, ansatz, parameter fitting to a subset, or self-citation chain is present; the central results are independent experimental outputs with no reduction to the paper's own inputs by construction.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

No free parameters, axioms, or invented entities are identifiable from the abstract alone; the analysis relies on standard nuclear spectroscopy practices whose details are not supplied.

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