BICEP2. II. EXPERIMENT AND THREE-YEAR DATA SET
Bibliographic record
Abstract
We report on the design and performance of the Bicep 2 instrument and on its three-year data set. Bicep 2 was designed to measure the polarization of the cosmic microwave background (CMB) on angular scales of 1°–5°(ℓ = 40–200), near the expected peak of the B -mode polarization signature of primordial gravitational waves from cosmic inflation. Measuring B -modes requires dramatic improvements in sensitivity combined with exquisite control of systematics. The Bicep 2 telescope observed from the South Pole with a 26 cm aperture and cold, on-axis, refractive optics. Bicep 2 also adopted a new detector design in which beam-defining slot antenna arrays couple to transition-edge sensor (TES) bolometers, all fabricated on a common substrate. The antenna-coupled TES detectors supported scalable fabrication and multiplexed readout that allowed Bicep 2 to achieve a high detector count of 500 bolometers at 150 GHz, giving unprecedented sensitivity to B -modes at degree angular scales. After optimization of detector and readout parameters, Bicep 2 achieved an instrument noise-equivalent temperature of . The full data set reached Stokes Q and U map depths of 87.2 nK in square-degree pixels (5 2 μK) over an effective area of 384 deg 2 within a 1000 deg 2 field. These are the deepest CMB polarization maps at degree angular scales to date. The power spectrum analysis presented in a companion paper has resulted in a significant detection of B -mode polarization at degree scales.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.004 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.003 |
| Science and technology studies | 0.003 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.003 | 0.004 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.008 | 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; 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".