Development of TACTIC: a novel detector for nuclear astrophysics
Bibliographic record
Abstract
Active-target detectors play a significant role in low-energy nuclear physics. The ability to utilise low intensity radioactive beams and a flexible choice of target gas enable these detectors to make direct measurements of a variety of nuclear reactions. This thesis focuses on the development and commissioning of TACTIC, a cylindrical active-target TPC. The design of TACTIC is suitable for the cross section measurement of alpha-induced charged particle reactions at low centre of mass energies. The measurements rely on the identification of charged particles by means of differential energy loss in the detection medium. In order to detect the reaction products over a wide range of energies, the novel μ-RWELL (micro-Resistive WELL) detectors are used as the gas multiplication stage. A unique concentric cathode cage configuration is also used to trap the ionisation electrons from the unreacted beam ions, which enables TACTIC to accommodate higher beam intensities (> 10^6 pps), compared to other active target detectors. Furthermore, an adjustable extended gas target allows simultaneous cross section measurements at multiple centre of mass energies. A detailed characterisation of the detector and the first successful cross section measurement at the TRIUMF ISAC-I facility are documented in this work. The astrophysically important 23Na(α, p)26Mg reaction was studied in inverse kinematics as a commissioning experiment. \n \nThis thesis also includes the study of the μ-RWELL detectors with the test chamber, which is a planar analogue of TACTIC. A series of alpha and 55Fe X-ray source tests were used to study the performance and optimum operating conditions of the μ-RWELL detectors in terms of gas gain and energy resolution achievable as well as the low-energy detection capability (∼ few keV) in different gas mixtures of interest. The installation marked the very first integration of the state-of-the-art μ-RWELL technology inside a cylindrical geometry for charged particle tracking.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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 teacher head, 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".