分类： 天文学 >> 天文学 提交时间： 2023-02-19
John W. Appel
Charles L. Bennett
Michael K. Brewer
Ricardo Bustos
Manwei Chan
David T. Chuss
Joseph Cleary
Jullianna D. Couto
Sumit Dahal
Rahul Datta
Kevin Denis
Joseph Eimer
Thomas Essinger-Hileman
Kathleen Harrington
Jeffrey Iuliano
Yunyang Li
Tobias A. Marriage
Carolina Núñez
Keisuke Osumi
Ivan L. Padilla
摘要： The current and future cosmic microwave background (CMB) experiments fielding kilo-pixel arrays of transition-edge sensor (TES) bolometers require accurate and robust gain calibration methods. We simplify and refactor the standard TES model to directly relate the detector responsivity calibration and optical time constant to the measured TES current $I$ and the applied bias current $I_{\mathrm{b}}$. The calibration method developed for the Cosmology Large Angular Scale Surveyor (CLASS) TES bolometer arrays relies on current versus voltage ($I$-$V$) measurements acquired daily prior to CMB observations. By binning Q-band (40GHz) $I$-$V$ measurements by optical loading, we find that the gain calibration median standard error within a bin is 0.3%. We test the accuracy of this "$I$-$V$ bin" detector calibration method by using the Moon as a photometric standard. The ratio of measured Moon amplitudes between detector pairs sharing the same feedhorn indicates a TES calibration error of 0.5%. We also find that for the CLASS Q-band TES array, calibrating the response of individual detectors based solely on the applied TES bias current accurately corrects TES gain variations across time but introduces a bias in the TES calibration from data counts to power units. Since the TES current bias value is set and recorded before every observation, this calibration method can always be applied to raw TES data and is not subject to $I$-$V$ data quality or processing errors.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Carolina Núñez
John W. Appel
Michael K. Brewer
Sarah Marie Bruno
Rahul Datta
Charles L. Bennett
Ricardo Bustos
David T. Chuss
Sumit Dahal
Kevin L. Denis
Joseph Eimer
Thomas Essinger-Hileman
Kyle Helson
Tobias Marriage
Carolina Morales Pérez
Ivan L. Padilla
Matthew A. Petroff
Karwan Rostem
Duncan J. Watts
Edward J. Wollack
摘要： The Cosmology Large Angular Scale Surveyor (CLASS) is a polarization-sensitive telescope array located at an altitude of 5,200 m in the Chilean Atacama Desert and designed to measure the polarized Cosmic Microwave Background (CMB) over large angular scales. The CLASS array is currently observing with three telescopes covering four frequency bands: one at 40 GHz (Q); one at 90 GHz (W1); and one dichroic system at 150/220 GHz (HF). During the austral winter of 2022, we upgraded the first 90 GHz telescope (W1) by replacing four of the seven focal plane modules. These new modules contain detector wafers with an updated design, aimed at improving the optical efficiency and detector stability. We present a description of the design changes and measurements of on-sky optical efficiencies derived from observations of Jupiter.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Rui Shi
Tobias A. Marriage
John W. Appel
Charles L. Bennett
David T. Chuss
Joseph Cleary
Joseph Eimer
Sumit Dahal
Rahul Datta
Francisco Espinoza
Yunyang Li
Nathan J. Miller
Carolina Núñez
Ivan L. Padilla
Matthew A. Petroff
Deniz A. N. Valle
Edward J. Wollack
Zhilei Xu
摘要： In this paper, we explore the power of the cosmic microwave background (CMB) polarization (E-mode) data to corroborate four potential anomalies in CMB temperature data: the lack of large angular-scale correlations, the alignment of the quadrupole and octupole (Q-O), the point-parity asymmetry, and the hemispherical power asymmetry. We use CMB simulations with noise representative of three experiments -- the Planck satellite, the Cosmology Large Angular Scale Surveyor (CLASS), and the LiteBIRD satellite -- to test how current and future data constrain the anomalies. We find the correlation coefficients $\rho$ between temperature and E-mode estimators to be less than $0.1$, except for the point-parity asymmetry ($\rho=0.17$ for cosmic-variance-limited simulations), confirming that E-modes provide a check on the anomalies that is largely independent of temperature data. Compared to Planck component-separated CMB data (SMICA), the putative LiteBIRD survey would reduce errors on E-mode anomaly estimators by factors of $\sim 3$ for hemispherical power asymmetry and point-parity asymmetry, and by $\sim 26$ for lack of large-scale correlation. The improvement in Q-O alignment is not obvious due to large cosmic variance, but we found the ability to pin down the estimator value will be improved by a factor $\gtrsim100$. Improvements with CLASS are intermediate to these.
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