Kinetic inductance detectors (KIDs) show promise as a competitive technology for astronomical observations over a wide range of wavelengths. We are interested in comparing the fundamental limitations ...to the sensitivity of KIDs with that of transition edge sensors (TESs) at millimeter wavelengths, specifically over the wavelengths required for studies of the Cosmic Microwave Background (CMB). We calculate the total fundamental noise arising from optical and thermal excitations in TESs and KIDs for a variety of bath temperatures and optical loading scenarios for applications at millimeter wavelengths. Special consideration is given to the case of ground-based observations of 100 GHz radiation with a 100 mK bath temperature, conditions consistent with the planned second module of the QUBIC telescope, a CMB instrument. Under these conditions, a titanium nitride KID with optimized critical temperature pays a few percent noise penalty compared to a typical optimized TES.
We forecast constraints on cosmological parameters enabled by three surveys conducted with SPT-3G, the third-generation camera on the South Pole Telescope. The surveys cover separate regions of 1500, ...2650, and 6000 \({\rm deg}^{2}\) to different depths, in total observing 25% of the sky. These regions will be measured to white noise levels of roughly 2.5, 9, and 12 \(\mu{\rm K-arcmin}\), respectively, in CMB temperature units at 150 GHz by the end of 2024. The survey also includes measurements at 95 and 220 GHz, which have noise levels a factor of ~1.2 and 3.5 times higher than 150 GHz, respectively, with each band having a polarization noise level ~\(\sqrt{\text{2}}\) times higher than the temperature noise. We use a novel approach to obtain the covariance matrices for jointly and optimally estimated gravitational lensing potential bandpowers and unlensed CMB temperature and polarization bandpowers. We demonstrate the ability to test the \(\Lambda{\rm CDM}\) model via the consistency of cosmological parameters constrained independently from SPT-3G and Planck data, and consider the improvement in constraints on \(\Lambda{\rm CDM}\) extension parameters from a joint analysis of SPT-3G and Planck data. The \(\Lambda{\rm CDM}\) cosmological parameters are typically constrained with uncertainties up to ~2 times smaller with SPT-3G data, compared to Planck, with the two data sets measuring significantly different angular scales and polarization levels, providing additional tests of the standard cosmological model.
Latest Progress on the QUBIC Instrument Ghribi, A.; Aumont, J.; Battistelli, E. S. ...
Journal of low temperature physics,
2014/9, Letnik:
176, Številka:
5-6
Journal Article
Recenzirano
QUBIC is a unique instrument that crosses the barriers between classical imaging architectures and interferometry taking advantage from both high sensitivity and systematics mitigation. The ...scientific target is to detect primordial gravitational waves created by inflation by the polarization they imprint on the cosmic microwave background—the holy grail of modern cosmology. In this paper, we show the latest advances in the development of the architecture and the sub-systems of the first module of this instrument to be deployed at Dome Charlie Concordia base—Antarctica in 2015.
Including millimeter-wave (mm-wave) data in multi-wavelength studies of the variability of active galactic nuclei (AGN) can provide insights into AGN physics that are not easily accessible at other ...wavelengths. We demonstrate in this work the potential of cosmic microwave background (CMB) telescopes to provide long-term, high-cadence mm-wave AGN monitoring over large fractions of sky. We report on a pilot study using data from the SPTpol instrument on the South Pole Telescope (SPT), which was designed to observe the CMB at arcminute and larger angular scales. Between 2013 and 2016, SPTpol was used primarily to observe a single 500 deg^2 field, covering the entire field several times per day with detectors sensitive to radiation in bands centered at 95 and 150 GHz. We use SPT 150 GHz observations to create AGN light curves, and we compare these mm-wave light curves to those at other wavelengths, in particular gamma-ray and optical. In this Letter, we focus on a single source, PKS 2326-502, which has extensive, day-timescale monitoring data in gamma-ray, optical, and now mm-wave between 2013 and 2016. We find PKS 2326-502 to be in a flaring state in the first two years of this monitoring, and we present a search for evidence of correlated variability between mm-wave, optical R band, and gamma-ray observations. This pilot study is paving the way for AGN monitoring with current and upcoming CMB experiments such as SPT-3G, Simons Observatory, and CMB-S4, including multi-wavelength studies with facilities such as VRO-LSST.
Digital frequency multiplexing (dfMux) is a readout architecture for transition edge sensor-based detector arrays and is used on telescopes including SPT-3G, POLARBEAR-2, and LiteBIRD. Here, we ...present recent progress and plans for development of a sub-Kelvin SQUID architecture for digital frequency multiplexed bolometers. This scheme moves the SQUID from the 4 K stage to the 250 mK stage, adjacent to the bolometers. Operating the SQUID on the detector stage may offer lower noise and greater scalability. Electrical performance will be improved as a result of decreased wiring length and reduced parasitics, allowing for higher multiplexing factors and lower bolometer R_normal . These performance improvements will enable ultra-large focal planes for future instruments such as CMB-S4.
We present measurements of the properties of thin film superconducting Mo, Mo2N and Mo2N/Mo/Mo2N trilayers of interest for microwave kinetic inductance detector (MKID) applications. Using microwave ...resonator devices, we investigate the transition temperature, energy gaps, kinetic inductance, and internal quality factors of these materials. We present an Usadel-based interpretation of the trilayer transition temperature as a function of trilayer thicknesses, and a 2-gap interpretation to understand the change in kinetic inductance and internal resonance quality factor (Q) as a function of temperature.
We present a search for anisotropic cosmic birefringence in 500 deg\(^2\) of southern sky observed at 150 GHz with the SPTpol camera on the South Pole Telescope. We reconstruct a map of cosmic ...polarization rotation anisotropies using higher-order correlations between the observed cosmic microwave background (CMB) \(E\) and \(B\) fields. We then measure the angular power spectrum of this map, which is found to be consistent with zero. The non-detection is translated into an upper limit on the amplitude of the scale-invariant cosmic rotation power spectrum, \(L(L+1)C_L^{\alpha\alpha}/2\pi < 0.10 \times 10^{-4}\) rad\(^2\) (0.033 deg\(^2\), 95% C.L.). This upper limit can be used to place constraints on the strength of primordial magnetic fields, \(B_{1 \rm Mpc} < 17 {\rm nG} \) (95% C.L.), and on the coupling constant of the Chern-Simons electromagnetic term \(g_{a\gamma} < 4.0 \times 10^{-2}/H_I \) (95% C.L.), where \(H_I\) is the inflationary Hubble scale. For the first time, we also cross-correlate the CMB temperature fluctuations with the reconstructed rotation angle map, a signal expected to be non-vanishing in certain theoretical scenarios, and find no detectable signal. We perform a suite of systematics and consistency checks and find no evidence for contamination.
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