Precise <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>Q</mml:mi></mml:math>-value measurements of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Ag</mml:mi><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>112</mml:mn><mml:mo>,</mml:mo><mml:mn>113</mml:mn></mml:mrow></mml:mmultiscripts></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Cd</mml:mi><mml:mprescripts/><mml:none/><mml:mn>115</mml:mn></mml:mmultiscripts></mml:math> with the Canadian Penning trap for evaluation of potential ultralow <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>Q</mml:mi></mml:math>-value <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>β</mml:mi></mml:math> decays
Bibliographic record
Abstract
Background: An ultralow $Q$-value $\ensuremath{\beta}$ decay can occur from a parent nuclide to an excited nuclear state in the daughter such that ${Q}_{\text{UL}}\ensuremath{\lesssim}$ 1 keV. These decay processes are of interest for nuclear $\ensuremath{\beta}$-decay theory and as potential candidates in neutrino mass determination experiments. To date, only one ultralow $Q$-value $\ensuremath{\beta}$ decay has been observed---that of $^{115}\mathrm{In}$ with ${Q}_{\ensuremath{\beta}}=147(10)$ eV. A number of other potential candidates exist, but improved mass measurements are necessary to determine if these decay channels are energetically allowed and, in fact, ultralow.Purpose: To perform precise $\ensuremath{\beta}$-decay $Q$-value measurements of $^{112,113}\mathrm{Ag}$ and $^{115}\mathrm{Cd}$ and to use them in combination with nuclear energy level data for the daughter isotopes $^{112,113}\mathrm{Cd}$ and $^{115}\mathrm{In}$ to determine if the potential ultralow $Q$-value $\ensuremath{\beta}$-decay branches of $^{112,113}\mathrm{Ag}$ and $^{115}\mathrm{Cd}$ are energetically allowed and $\ensuremath{\lesssim}1$ keV.Method: The Canadian Penning Trap at Argonne National Laboratory was used to measure the cyclotron frequency ratios of singly charged $^{112,113}\mathrm{Ag}$ and $^{115}\mathrm{Cd}$ ions with respect to their daughters $^{112,113}\mathrm{Cd}$ and $^{115}\mathrm{In}$. From these measurements, the ground-state to ground-state $\ensuremath{\beta}$-decay $Q$ values were obtained.Results: The $^{112}\mathrm{Ag}\phantom{\rule{4pt}{0ex}}\ensuremath{\rightarrow}\phantom{\rule{4pt}{0ex}}^{112}\mathrm{Cd}$, $^{113}\mathrm{Ag}\phantom{\rule{4pt}{0ex}}\ensuremath{\rightarrow}\phantom{\rule{4pt}{0ex}}^{113}\mathrm{Cd}$, and $^{115}\mathrm{Cd}\phantom{\rule{4pt}{0ex}}\ensuremath{\rightarrow}\phantom{\rule{4pt}{0ex}}^{115}\mathrm{In}\phantom{\rule{4pt}{0ex}}\ensuremath{\beta}$-decay $Q$ values were measured to be ${Q}_{\ensuremath{\beta}}(^{112}\mathrm{Ag})=3990.16(22)$ keV, ${Q}_{\ensuremath{\beta}}(^{113}\mathrm{Ag})=2085.7(4.6)$ keV, and ${Q}_{\ensuremath{\beta}}(^{115}\mathrm{Cd})=1451.36(34)$ keV. These results were compared to energies of excited states in $^{112}\mathrm{Cd}$ at 3997.75(14) keV, $^{113}\mathrm{Cd}$ at 2015.6(2.5) and 2080(10) keV, and $^{115}\mathrm{In}$ at 1448.787(9) keV, resulting in precise ${Q}_{\text{UL}}$ values for the potential decay channels of $\ensuremath{-}7.59(26)$ keV, 6(11) keV, and 2.57(34) keV, respectively.Conclusion: The potential ultralow $Q$-value decays of $^{112}\mathrm{Ag}$ and $^{115}\mathrm{Cd}$ have been ruled out. $^{113}\mathrm{Ag}$ is still a possible candidate until a more precise measurement of the 2080(10) keV, $1/{2}^{+}$ state of $^{113}\mathrm{Cd}$ is available. In the course of this work we have found the ground state mass of $^{113}\mathrm{Ag}$ reported in the 2020 Atomic Mass Evaluation [Wang et al., Chin. Phys. C 45, 030003 (2021)] to be lower than our measurement by 69(17) keV (a $4\ensuremath{\sigma}$ discrepancy).
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.012 | 0.006 |
| Meta-epidemiology (narrow) | 0.006 | 0.010 |
| Meta-epidemiology (broad) | 0.003 | 0.010 |
| Bibliometrics | 0.002 | 0.005 |
| Science and technology studies | 0.011 | 0.009 |
| Scholarly communication | 0.007 | 0.008 |
| Open science | 0.011 | 0.010 |
| Research integrity | 0.007 | 0.010 |
| Insufficient payload (model declined to judge) | 0.014 | 0.007 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; both teacher heads agree on what is shown here.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".