Precision mass measurements of neutron-rich rare isotopes approaching the r-process path with the Canadian Penning Trap mass spectrometer
Bibliographic record
Abstract
The masses of 15 neutron-rich nuclei were measured using the Canadian Penning Trap mass spectrometer (CPT) located at the Californium Rare Isotope Breeder Upgrade (CARIBU) facility at Argonne National Laboratory to an average mass precision of $\delta m/m \approx 10^{-7}$. This includes masses of five previously unmeasured ground-state nuclei and one of a newly resolved isomer. Generally good agreement is reached when comparing the data set in this thesis with previously established mass measurements. CARIBU provides neutron-rich radioactive beams in the vicinity of A=105 and A=140, originating from the spontaneous fission of 252Cf. In this thesis, isotopes with fission branches as low as 3.3E-4 products per 100 decays (150Ba) and half-lifes as low as 222 ms (142I) have been reached. \\ This thesis provides a thorough discussion of the precision mass measurement process, from ion production at CARIBU, to detection at the CPT where a time-of-flight-ion cyclotron resonance (ToF-ICR) technique is employed to determine the cyclotron frequencies of trapped ion species. Limitations of the measurement technique with respect to the current CPT system at CARIBU are discussed, and a new phase-imaging-ion cyclotron resonance (PI-ICR) procedure is introduced.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
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".