Novel Linac II Electrode Geometry for Creating An Axial Field in a Multipole Ion Guide
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Bibliographic record
Abstract
Tandem instruments, such as triple-quadrupole or quadrupole-time-of-flight mass spectrometers, often use collisional damping ion guides for the purpose of cooling and focusing the primary ion beam, or as a collision cell for tandem mass spectrometry experiments. A small axial field to reduce the ion residence time in such devices can give considerable improvements in performance. Reduction of the residence time reduces adduct formation caused by unwanted gas-phase reactions and allows multiple reaction monitoring (MRM) and some other types of scan to be carried out more rapidly without the risk of reaction cross-talk. Here we propose a novel electrode arrangement for creation of a suitable axial field in a multipole ion guide without significantly reducing the m/z window. As an example, a second set of four electrodes is added to an existing quadrupole collision cell. The same DC potential is applied to all four extra electrodes, which are shaped in the longitudinal direction to create a suitable axial field inside the device. The potential of these electrodes and the DC bias of the main rods determine the axial field strength. The idea was tested on a modified quadrupole collision cell of a MALDI-QqTOF instrument and experimental results are presented here, as well as a simplified theory of operation.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.007 | 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 it