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arxiv: 2606.25093 · v1 · pith:D3H44TMCnew · submitted 2026-06-23 · ⚛️ nucl-ex · nucl-th

Low lying excitations in ¹⁵⁰Pm

A. Pal , S. Basak , T. Bhattacharjee , Nazira Nazir , G. H. Bhat , S. Jehangir , D. Kumar , A. Saha
show 14 more authors
S. S. Alam D. Banerjee A. Das A. Adhikari A. Gupta S. Das A. Bisoi Y. Sapkota S. Sharma S. Samanta S. Chatterjee R. Raut S. S. Ghugre J. A. Sheikh
This is my paper

Pith reviewed 2026-06-25 21:17 UTC · model grok-4.3

classification ⚛️ nucl-ex nucl-th
keywords 150Pmlow-lying excitationsodd-odd nucleusgamma-ray spectroscopyshell modelisomeric statequasiparticle configurations
0
0 comments X

The pith

The odd-odd nucleus 150Pm has a 1- ground state, a 2- state near 50 keV, and a low-lying 6- isomer.

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

This paper maps the low-lying energy levels in the odd-odd nucleus 150Pm using proton-induced gamma-ray spectroscopy. It places 15 new levels and 16 new gamma rays in the level scheme and makes tentative spin-parity assignments to several low states based on coincidence data, excitation functions, and angular distributions. Comparisons with large-basis shell model and projected shell model calculations support the observed structures. Understanding these excitations matters because odd-odd nuclei exhibit complex spectra from the coupling of unpaired nucleons, which tests nuclear models. The work suggests specific ground-state properties and emerging bands built on two-quasiparticle configurations.

Core claim

The present work indicates 1- ground state, a 2- state close to the ground state (~50 keV) and a low lying 6- isomeric state in this odd-odd nucleus along with emerging band structures developed with two quasiparticle configurations.

What carries the argument

Gamma-gamma coincidence spectroscopy combined with relative excitation functions at different beam energies and limited angular distribution data, interpreted through shell model calculations.

If this is right

  • Confirms 1- as the ground state spin-parity for 150Pm.
  • Places a 2- state approximately 50 keV above the ground state.
  • Identifies a low-lying 6- isomeric state.
  • Reveals band structures arising from two-quasiparticle configurations.
  • Provides lifetime estimates for two excited levels using generalized centroid difference analysis.

Where Pith is reading between the lines

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

  • The observed pattern of states may appear in other odd-odd nuclei in the same mass region.
  • These levels could affect beta-decay properties or reaction rates involving 150Pm.
  • Further coincidence data with better statistics could confirm or refine the band structures.

Load-bearing premise

The tentative spin-parity assignments to the low-lying states rely on limited angular distribution data and supporting information.

What would settle it

A precise measurement of the ground-state spin or the energy and spin of the proposed isomer that contradicts the 1-, 2-, or 6- assignments would falsify the claims.

Figures

Figures reproduced from arXiv: 2606.25093 by A. Adhikari, A. Bisoi, A. Das, A. Gupta, A. Pal, A. Saha, D. Banerjee, D. Kumar, G. H. Bhat, J. A. Sheikh, Nazira Nazir, R. Raut, S. Basak, S. Chatterjee, S. Das, S. Jehangir, S. S. Alam, S. Samanta, S. S. Ghugre, S. Sharma, T. Bhattacharjee, Y. Sapkota.

Figure 1
Figure 1. Figure 1: FIG. 1: (Color online) Low lying level structure of [PITH_FULL_IMAGE:figures/full_fig_p003_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2: (Color online) The [PITH_FULL_IMAGE:figures/full_fig_p004_2.png] view at source ↗
Figure 1
Figure 1. Figure 1: Among the second set of γ lines, which have no connec￾tion with γ rays of the first set, the 128.3 keV transition and the γ rays in coincidence with 128.3 keV were placed on the ground state, considering the earlier propositions by Bucurescu et al., based on both (p, nγ) and (d,α) reac￾tions. However, the 177.2 keV and the transitions which are in coincidence with 177.2 keV, are tentatively placed on the 6… view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3: (Color online) The results from angular distribution [PITH_FULL_IMAGE:figures/full_fig_p006_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: FIG. 4: (Color online) The contours have been drawn from the [PITH_FULL_IMAGE:figures/full_fig_p007_4.png] view at source ↗
Figure 6
Figure 6. Figure 6: FIG. 6: (Color online) The timing analysis with the 832- [PITH_FULL_IMAGE:figures/full_fig_p008_6.png] view at source ↗
Figure 5
Figure 5. Figure 5: FIG. 5: (Color online) The timing analysis with the 156- [PITH_FULL_IMAGE:figures/full_fig_p008_5.png] view at source ↗
Figure 7
Figure 7. Figure 7: FIG. 7: (Color online) The PRD values (solid circles) obtained [PITH_FULL_IMAGE:figures/full_fig_p008_7.png] view at source ↗
Figure 9
Figure 9. Figure 9: FIG. 9: (Color online) The lifetime analysis of 159-177 keV [PITH_FULL_IMAGE:figures/full_fig_p009_9.png] view at source ↗
Figure 8
Figure 8. Figure 8: FIG. 8: (Color online) The lifetime analysis of 166-128 keV [PITH_FULL_IMAGE:figures/full_fig_p009_8.png] view at source ↗
Figure 10
Figure 10. Figure 10: FIG. 10: (Color online) The lifetime analysis of 192-270 keV [PITH_FULL_IMAGE:figures/full_fig_p010_10.png] view at source ↗
Figure 11
Figure 11. Figure 11: FIG. 11: (Color online) Proposed band-like structures in [PITH_FULL_IMAGE:figures/full_fig_p013_11.png] view at source ↗
Figure 12
Figure 12. Figure 12: FIG. 12: (Color online) Low lying level structure of the neighbors of [PITH_FULL_IMAGE:figures/full_fig_p013_12.png] view at source ↗
Figure 14
Figure 14. Figure 14: FIG. 14: (Color online) Projected energies are shown before [PITH_FULL_IMAGE:figures/full_fig_p015_14.png] view at source ↗
Figure 13
Figure 13. Figure 13: FIG. 13: The negative parity levels in [PITH_FULL_IMAGE:figures/full_fig_p015_13.png] view at source ↗
Figure 15
Figure 15. Figure 15: FIG. 15: (Color online) Comparison of experimentally observed level energies of negative parity bands B1, B2, and B3, and [PITH_FULL_IMAGE:figures/full_fig_p016_15.png] view at source ↗
read the original abstract

The low lying excitations in odd-odd $^{150}$Pm have been studied through proton induced reaction with an array of five Compton suppressed Clover HPGe and one segmented planar Ge detectors. The relative excitation functions for the observed $\gamma$ rays have been studied using singles data at two beam energies of 8~MeV and 9~MeV. 16 new $\gamma$ rays and 15 new levels have been placed in the level scheme of $^{150}$Pm based on $\gamma-\gamma$ coincidence data. The relative intensities for the observed $\gamma$ rays have been determined using total and gated projections. Tentative spin-parity assignments were made to few low lying excitations of $^{150}$Pm, using limited angular distribution data and other information. Lifetimes were estimated for two excited levels in this nucleus using using generalized centroid difference analysis, applied in the nanosecond range, with Ge detectors. Large basis shell model and projected shell model calculation were performed to interpret the experimentally observed levels. The present work indicates 1$^-$ ground state, a 2$^-$ state close to the ground state ($\sim$50~keV) and a low lying 6$^-$ isomeric state in this odd-odd nucleus along with emerging band structures developed with two quasiparticle configurations.

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 / 3 minor

Summary. The paper reports an experimental study of low-lying excitations in odd-odd 150Pm via proton-induced reactions at 8 and 9 MeV using five Compton-suppressed Clover HPGe detectors and one segmented planar Ge detector. From γ-γ coincidence data, 16 new γ rays and 15 new levels are placed in the level scheme. Relative intensities are determined from total and gated projections, and relative excitation functions are examined. Tentative J^π assignments are made to a few low-lying states (including a 1− ground state, a 2− state near 50 keV, and a 6− isomeric state) using limited angular distribution data and other information. Lifetimes of two levels are estimated via generalized centroid difference analysis in the nanosecond range. Results are compared to large-basis shell-model and projected shell-model calculations to interpret two-quasiparticle configurations and emerging band structures.

Significance. If the tentative assignments hold, the work supplies new experimental constraints on the structure of 150Pm, a nucleus with sparse prior data on low-lying states. The addition of 15 levels, lifetime estimates, and model comparisons helps map two-quasiparticle excitations in this odd-odd system. The experimental methods (coincidence spectroscopy, intensity measurements, and ns-range lifetime analysis with Ge detectors) are standard and the assignments are explicitly labeled tentative, reducing circularity risk with the calculations.

major comments (1)
  1. [Abstract] Abstract: The headline indications of a 1− ground state, ~50 keV 2− state, and low-lying 6− isomer are load-bearing for the claimed configurations and band structures, yet rest on tentative assignments from 'limited angular distribution data and other information'. A dedicated subsection or figure presenting the angular-distribution coefficients (A2, A4), fit quality, and alternative J^π possibilities is required to assess whether these assignments can be considered reliable enough to support the stated conclusions.
minor comments (3)
  1. [Abstract] Abstract: Typo 'using using generalized centroid difference analysis' should be corrected.
  2. The manuscript should include the complete level scheme, representative coincidence spectra, and a table of new γ-ray energies, intensities, and placements to allow independent verification of the 16 new transitions and 15 new levels.
  3. Uncertainties on relative intensities, excitation-function ratios, and lifetime values are not mentioned in the abstract; these should be reported explicitly with the data.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for the careful review and for recognizing the significance of the new experimental constraints on 150Pm. We address the single major comment below.

read point-by-point responses

  1. Referee: [Abstract] Abstract: The headline indications of a 1− ground state, ~50 keV 2− state, and low-lying 6− isomer are load-bearing for the claimed configurations and band structures, yet rest on tentative assignments from 'limited angular distribution data and other information'. A dedicated subsection or figure presenting the angular-distribution coefficients (A2, A4), fit quality, and alternative J^π possibilities is required to assess whether these assignments can be considered reliable enough to support the stated conclusions.

    Authors: We agree that the angular-distribution analysis supporting the tentative J^π assignments requires more explicit documentation. Although the manuscript already qualifies these assignments as tentative and notes the limited nature of the data, we will add a dedicated subsection (with an accompanying table or figure) that reports the measured A2 and A4 coefficients, the quality of the Legendre-polynomial fits, and the alternative J^π values that were considered and rejected on the basis of the available information. This addition will be placed in the Results section and will allow readers to evaluate the assignments independently. The revision will be incorporated in the next version of the manuscript. revision: yes

Circularity Check

0 steps flagged

No significant circularity; experimental placements and tentative assignments derive directly from coincidence and angular data, with models used only for post-hoc interpretation.

full rationale

The paper reports new γ-γ coincidence placements, relative intensities, excitation functions, and limited angular distributions from proton-induced reactions. Tentative J^π values and the indicated 1^-, 2^-, and 6^- states follow from those measurements plus 'other information,' without any parameter fitting to the new data that would render subsequent model comparisons circular. Shell-model and projected-shell-model calculations are invoked solely to interpret the observed levels after the experimental scheme is constructed; no self-citation chain, self-definitional loop, or fitted-input-called-prediction pattern appears in the derivation. The central claims therefore remain externally falsifiable against the raw coincidence and angular data.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Abstract-only review; no explicit free parameters, axioms, or invented entities listed. Shell model calculations implicitly rely on effective interactions and model spaces from prior literature.

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