REVIEW 3 major objections 4 minor 40 references
Examining the potential synthesis of new elements with $^{294}$Og
T0 review · 3 major / 4 minor · reviewed 2026-08-12 · deepseek-v4-flash
Pith's one-line read The paper claims that element 119 can be reached by letting freshly made 294Og strike a hydrogen or deuterium target, at roughly one atom every 520 days (173 days with deuterium), and that the same scheme can reach elements 120 and 121.
desk verdict Novel two-stage dual-target route to element 119, but the central feasibility claim rests on unvalidated INCL+ABLA cross sections; the idea is worth a serious but skeptical look. read the letter →
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
What carries the argument
The load-bearing machinery is a two-stage reaction simulation: INCL6.33, an intranuclear cascade model that follows the light projectile's collision with $\^{294}$Og and produces a hot remnant classified by mass, charge, excitation energy, and angular momentum; followed by ABLA, a deexcitation model that decides whether that remnant evaporates particles, emits gamma rays, breaks up, or fissions. The physical device is the dual-target geometry: $\^{294}$Og formed in the $\^{249}$Cf target travels, with the help of a superconducting linear accelerator, to the light-nucleus target within its ~1 ms half-life. Yield estimates come from the INCL+ABLA cross sections inserted into the target-thickness formula $N_{\mathrm{event}} = N_{\mathrm{proj}} \times (1 - e^{-\sigma/T_{\mathrm{thick}}})$.
What would settle it
Measure the evaporation-residue cross section for $\^{294}$Og + p in inverse kinematics at 10-20 MeV; if the element-119 residue cross section is below about 1 mb rather than the predicted ~10 mb, the 520-day estimate becomes a multi-year-or-worse program. A cheaper check is to run the same INCL6.33+ABLA chain against measured p + $\^{238}$U and d + $\^{238}$U evaporation-residue cross sections in the same energy range; a systematic miss by more than a factor of about 5 there would show the superheavy extrapolation is not quantitatively reliable.
Extended reading notes
Core claim
On the paper's own terms, the synthesis of element 119 is 'indeed feasible' using a dual-target scheme. The first target is $\^{249}$Cf, which a $\^{48}$Ca beam converts to $\^{294}$Og; a light-nucleus layer (hydrogen, deuterium, helium-3, helium-4, lithium-7, or lithium-8) is placed immediately behind so that the ~1 ms half-life $\^{294}$Og reacts before it decays. INCL6.33+ABLA calculations yield a $\^{294}$Og + p evaporation-residue cross section peaking around 10 mb near 16 MeV beam energy, and about 30 mb for deuterium, giving an estimated one atom of element 119 every 520 days (hydrogen) or 173 days (deuterium). The paper also finds that lower beam energies favor production of mass-294 and mass-293 isotopes of element 119, while higher energies broaden the isotope distribution and lower the yield, and that helium and lithium targets can reach elements 120 and 121 with cross sections that are lower but not by orders of magnitude.
Load-bearing premise
The whole feasibility estimate rests on the INCL+ABLA computer model, calibrated on lighter nuclei and spallation reactions, remaining quantitatively accurate for 10-20 MeV proton and deuteron collisions with the superheavy nucleus $\^{294}$Og, especially for the chance that the element-119 remnant survives fission instead of breaking apart.
Editorial extensions
If this is right
- Element 119 can be produced in a two-step, dual-target reaction without changing the proven first step, 48Ca + 249Cf producing 294Og.
- With a hydrogen target the predicted production rate is about one atom of element 119 every 520 days; switching to deuterium shortens the estimate to about 173 days.
- The same setup with helium-3, helium-4, lithium-7, or lithium-8 targets is predicted to produce elements 120 and 121, with cross sections lower but not by orders of magnitude.
- The most favorable beam energies give fairly pure production of element 119 with mass 294 or 293; higher energies produce a broader isotope distribution and lower total yield.
- Energy loss of the 294Og projectile inside the light target could roughly halve the average reaction rate, doubling the time to one atom.
Reading between the lines
- The paper's headline rates assume a continuous beam at 9.25 x 10^13 particles per second and quoted target thicknesses; realistic beam duty cycle, target degradation, and chemical separation would likely lengthen the calendar time beyond the 520-day or 173-day numbers.
- The paper notes that 295Og lives about 1000 times longer than 294Og but does not exploit this in the production estimate; a dual-target scheme that could start from a neutron-richer oganesson isotope would presumably yield longer-lived element-119 isotopes.
- The predicted cross sections could be checked on cheaper surrogate systems before a full superheavy run: applying the same INCL+ABLA chain to proton- and deuteron-induced evaporation-residue reactions on the heaviest available actinide targets at 10-20 MeV would either support or undermine the superheavy extrapolation.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. This paper proposes a dual-target scheme for synthesizing element 119: a 48Ca beam produces 294Og via 48Ca + 249Cf, and the freshly produced 294Og is then accelerated in a proposed superconducting linac and directed onto a light target (hydrogen, deuterium, helium, or lithium) for a secondary reaction that would produce Z = 119, 120, or 121. Using the INCL6.33+ABLA models in inverse kinematics, the authors predict a 294Og+p cross section of about 10 mb near 16 MeV for element 119 production, and estimate one 119 isotope every 520 days with a hydrogen target (or roughly 173 days with deuterium) under assumed beam and target parameters. The paper concludes that 'the synthesis of element 119 as designed here is indeed feasible.' The manuscript is a Perspective-style proposal and explicitly labels the cross sections as theoretical in one passage, but the central quantitative claims are not supported by a validated model extrapolation or by a complete, reproducible rate derivation.
Significance. The conceptual idea is interesting and could be significant if the model extrapolation were defensible: it offers a potential alternative to the fusion-evaporation reactions that have failed to reach element 119 for two decades, and it makes concrete, falsifiable predictions for cross sections and rates with several light-ion targets. The paper also has the virtue of explicitly stating that the computed cross sections are theoretical. However, no benchmark against data in the superheavy regime is provided, no uncertainty estimate is given, and the rate calculation is not derived transparently. The proposal's significance therefore remains conditional on addressing these quantitative gaps; as presented, the feasibility claim is not established.
major comments (3)
- [Rate estimate (paragraph after Fig. 3)] The event-rate formula printed in this paragraph, N_event = N_proj * (1 - exp(-sigma/T_thick)), describes a single reaction step, but the quoted value of 2.22e-8 events/s can only be obtained by folding in the 48Ca + 249Cf production step as well as the 294Og + p step. The manuscript lists the 249Cf target thickness (0.34 mg/cm^2) and the liquid hydrogen thickness (100 mg/cm^2) but never states the 48Ca + 249Cf cross section used, nor writes the two-step expression. As written, the calculation is not reproducible, and the units in sigma/T_thick are inconsistent with the stated definition of T_thick as a number of nuclei per unit area. Please give the full two-step formula and all numerical inputs.
- [Figs. 2-4 and concluding paragraph] The central claim that synthesis of element 119 'as designed here is indeed feasible' rests entirely on INCL6.33+ABLA cross sections in a regime where the model is not validated. INCL is a spallation-oriented intranuclear-cascade code benchmarked mainly at incident energies of roughly 100 MeV to several GeV, and no benchmark is shown for 10-100 MeV light-ion reactions on a Z=118 nucleus; the ABLA survival probability for Z=119 evaporation residues depends on fission-barrier inputs that are themselves extrapolated. A factor of 10 error in the ~10 mb cross section changes the quoted 520-day period to about 14 years, crossing the boundary between a feasible and an impractical experiment. The paper's own caveat that 'these cross sections are theoretical and may not directly reflect the actual synthesis rates' is not quantified and is effectively absent from the conclusion. Please add a quantitative uncertainty argument or a validation benchmark, and temper the feasibility statement accordingly.
- [Superconducting linac and recoil re-acceleration paragraph] The feasibility statement assumes that 294Og recoils produced with 0.13 MeV/nucleon in the 249Cf target can be captured and accelerated in a superconducting linac to the roughly 16 MeV/nucleon needed for the secondary reaction. The manuscript gives no discussion of ion extraction, charge-state distribution, charge breeding, transmission efficiency, or losses in this re-acceleration step. These efficiency factors multiply the overall rate and are likely to be substantial; without a quantitative estimate, the statement that the scheme is feasible 'as designed here' is unsupported. Please provide at least an order-of-magnitude analysis of the re-acceleration stage.
minor comments (4)
- [Figs. 2 and 3] The text for Fig. 2 states that the production probability decreases with increasing beam energy, while the text for Fig. 3 states that the total cross section peaks near 16 MeV and declines at higher energies. Please clarify in the text that these are different quantities (probability per reaction versus absolute cross section) so that the apparent tension is resolved.
- [Rate formula definition] The sentence 'This density is derived from dividing the target’s molar mass by the number of target nuclei per unit area' is not correct as phrased; the areal number density is obtained by dividing the target thickness in mass per area by the atomic mass. Please rephrase to avoid the impression that the density and the number of nuclei are divided instead of related.
- [References [22] and [36]] Reference [22] is cited with a 2014 year in the text but the journal volume listed corresponds to 2024; please correct the bibliographic data. Reference [36], used for the 48Ca beam intensity, is a web news source; please provide a primary technical reference or a detailed statement of the beam parameters and their provenance.
- [INCL++6.33 code claim] The statement that INCL++6.33 'now also supports the generation of superheavy elements up to element 119 and beyond' is a code-capability claim; it should be accompanied by a reference to a manual, release note, or validation paper so that readers can identify the exact version and its treatment of superheavy remnants.
Circularity Check
No significant circularity: the 294Og+p cross section and event-rate estimates are model extrapolations, not restatements of fitted inputs; the author-developed INCL+ABLA code is self-cited but not tuned to the target reaction.
full rationale
The central quantity, the ~10 mb 294Og+p evaporation-residue cross section, is produced by the INCL6.33+ABLA model, not fitted to the 294Og+p yields reported here. The paper explicitly states that the ABLA prerequisites are 'predefined, consistent across all systems and energies', and the INCL parameters were fixed in earlier spallation studies; no parameter is adjusted to the target reaction. The event-rate estimate (one element-119 isotope every 520 days with hydrogen, or 173 days with deuterium) is a direct arithmetic conversion using the standard formula Nevent = N_proj × (1 − e^(−σ/T_thick)), with beam intensity and target thickness as inputs; it is therefore a derived projection, not a restatement of the model's input. The self-citations to INCL/ABLA development papers [24-32] are real evidence for the models in the spallation regime, though the application to ~10-100 MeV protons on 294Og is an extrapolation with no in-paper benchmark in the superheavy regime; this is a validation gap and a correctness risk, not circularity. The paper's own caveat that 'these cross sections are theoretical and may not directly reflect the actual synthesis rates' is in tension with the concluding 'indeed feasible' claim, but that mismatch concerns uncertainty quantification, not circular reasoning. One minor non-load-bearing self-citation is the rate formula attributed to a co-author's earlier paper [35]; it does not make the prediction equivalent to the input. Overall: no step reduces to its own input by construction.
Assumptions & free parameters
free parameters (3)
- INCL/ABLA model parameters =
not stated
- Assumed 48Ca beam intensity =
9.25e13 particles/s
- Liquid hydrogen target areal density =
100 mg/cm2
assumptions (3)
- domain assumption INCL6.33+ABLA remains quantitatively predictive when extrapolated from spallation energies to 10-100 MeV light-ion reactions on the superheavy nucleus 294Og, including the survival of Z=119 evaporation residues.
- domain assumption A freshly produced 294Og recoil can be captured, re-accelerated by a superconducting linac, and delivered to a secondary target within its roughly 1 ms half-life with negligible losses.
- domain assumption The first-stage production of 294Og from 48Ca+249Cf is sufficiently understood to be treated as a known input for the second stage.
Cite this review
Pith. "Pith review of Examining the potential synthesis of new elements with $^{294}$Og." pith.science (2026). https://pith.science/paper/WLBT6VA7
@misc{pith2026241113095,
author = {Pith},
title = {Pith review of: Examining the potential synthesis of new elements with $^294$Og},
year = {2026},
howpublished = {\url{https://pith.science/paper/WLBT6VA7}},
note = {Machine review of arXiv:2411.13095}
}
abstract
In the relentless pursuit of expanding the periodic table, the discovery of element 119 remains elusive, despite two decades of dedicated research efforts. The traditional fusion-evaporation approach, although fruitful in the past, now appears to be approaching its operational limits. This scenario sets the stage for considering innovative methodologies essential for further advancements in the field of superheavy elements. Here, we introduce a pioneering strategy aimed at synthesizing element 119 by adapting and extending the nuclear reaction processes previously successful in producing element $^{294}$Og. This involved the fusion of $^{48}$Ca and $^{249}$Cf. Building on this, our novel approach incorporates an additional reactive target -- specifically, hydrogen -- positioned strategically behind the $^{249}$Cf. This configuration is designed to facilitate an immediate secondary reaction of the nascent $^{294}$Og with hydrogen, potentially forging new pathways to element 119. Preliminary insights also suggest that employing isotopes like deuterium or helium-3 as targets may not only enhance the production rates of element 119 but might also pave the way for the synthesis of even heavier elements, extending up to elements 120 and 121. We delve into the technicalities and feasibility of employing a dual-target method using a $^{48}$Ca beam, exploring new horizons in the quest for the superheavy unknown.
Figures
Reference graph
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Reviewed August 12, 2026 · model on record in the stance chip above.
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