Current status of the Ali CMB Polarization Telescope focal plane camera

Abstract The Cosmology Large Angular Scale Surveyor (CLASS) is a four-telescope array observing the largest angular scales (2≲ ℓ ≲ 200) of the cosmic microwave background (CMB) polarization. These scales encode information about reionization and inflation during the early universe. The instrument stability necessary to observe these angular scales from the ground is achieved through the use of a variable-delay polarization modulator as the first optical element in each of the CLASS telescopes. Here, we develop a demodulation scheme used to extract the polarization timestreams from the CLASS data and apply this method to selected data from the first 2 yr of observations by the 40 GHz CLASS telescope. These timestreams are used to measure the 1/f noise and temperature-to-polarization (T → P) leakage present in the CLASS data. We find a median knee frequency for the pair-differenced demodulated linear polarization of 15.12 mHz and a T → P leakage of <3.8 × 10−4 (95% confidence) across the focal plane. We examine the sources of 1/f noise present in the data and find the component of 1/f due to atmospheric precipitable water vapor (PWV) has an amplitude of 203 ± 12 μ K RJ s for 1 mm of PWV when evaluated at 10 mHz; accounting for ∼17% of the 1/f noise in the central pixels of the focal plane. The low levels of T → P leakage and 1/f noise achieved through the use of a front-end polarization modulator are requirements for observing of the largest angular scales of the CMB polarization by the CLASS telescopes.

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A pixel space method for testing dipole modulation in the CMB polarization

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz3627 ◽

2020 ◽

Vol 492 (3) ◽

pp. 3994-4004

Author(s):

Shamik Ghosh ◽

Pankaj Jain

Keyword(s):

Cosmic Microwave Background ◽

Focal Plane ◽

Microwave Background ◽

Power Asymmetry ◽

Planck Data ◽

Real Effect ◽

Cmb Polarization ◽

Dipole Modulation ◽

Space Method ◽

Cmb Temperature

ABSTRACT We introduce a pixel space method to detect dipole modulation or hemispherical power asymmetry in the cosmic microwave background (CMB) polarization. The method relies on the use of squared total polarized flux whose ensemble average picks up a dipole due to the dipole modulation in the CMB polarization. The method is useful since it can be easily applied to partial sky. We define several statistics to characterize the amplitude of the detected signal. Through simulations, we show that the method can be used to reliably extract the signal at a 2.7σ level or higher in future CORE-like missions, assuming that the signal is present in the CMB polarization at the level detected by the Planck mission in the CMB temperature. An application of the method to the 2018 Planck data does not detect a significant effect, when taking into account the presence of correlated detector noise and residual systematics in the data. Using the Full Focal Plane 10, we find the presence of a very strong bias that might be masking any real effect.

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HgCdTe MBE Technology : A Focus On Chemical Doping

MRS Proceedings ◽

10.1557/proc-302-423 ◽

1993 ◽

Vol 302 ◽

Cited By ~ 1

Author(s):

Owen K. Wu

Keyword(s):

Double Layer ◽

Focal Plane ◽

Memory Effects ◽

Current Status ◽

Chemical Doping ◽

Mbe Growth ◽

Heterojunction Structure ◽

P Type ◽

Growth Technology

ABSTRACTHgCdTe MBE technology is becoming a mature growth technology for infrared focal plane array applications. The ability to dope HgCdTe with In(n-type) and As(p-type) dopants in-situ provides greater flexibilities for fabricating heterojunction devices. In this paper, we will first discuss the current status of HgCdTe MBE growth and then focus on the key results in the control of In(n-type) doping, various approaches and breakthroughs in the growth of As(p-type) doped HgCdTe and issues related to doping such as memory effects and dopants activation. In addition, device results from double layer heterojunction structure(DLHJ) will be briefly discussed.

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Physics of the cosmic microwave background anisotropy

International Journal of Modern Physics D ◽

10.1142/s0218271815300049 ◽

2015 ◽

Vol 24 (02) ◽

pp. 1530004 ◽

Cited By ~ 9

Author(s):

Martin Bucher

Keyword(s):

Cosmic Microwave Background ◽

Frequency Spectrum ◽

Early Universe ◽

Cosmological Models ◽

Experimental Techniques ◽

Current Status ◽

Microwave Background ◽

Cosmic Microwave Background Anisotropy ◽

Cmb Polarization ◽

Modern Cosmology

Observations of the cosmic microwave background (CMB), especially of its frequency spectrum and its anisotropies, both in temperature and in polarization, have played a key role in the development of modern cosmology and of our understanding of the very early universe. We review the underlying physics of the CMB and how the primordial temperature and polarization anisotropies were imprinted. Possibilities for distinguishing competing cosmological models are emphasized. The current status of CMB experiments and experimental techniques with an emphasis toward future observations, particularly in polarization, is reviewed. The physics of foreground emissions, especially of polarized dust, is discussed in detail, since this area is likely to become crucial for measurements of the B modes of the CMB polarization at ever greater sensitivity.

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Next generation sub-millimeter wave focal plane array coupling concepts: an ESA TRP project to develop multichroic focal plane pixels for future CMB polarization experiments

10.1117/12.2231267 ◽

2016 ◽

Cited By ~ 3

Author(s):

N. Trappe ◽

M. Bucher ◽

P. De Bernardis ◽

J. Delabrouille ◽

P. Deo ◽

...

Keyword(s):

Millimeter Wave ◽

Focal Plane ◽

Focal Plane Array ◽

Next Generation ◽

Cmb Polarization

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HgCdTe MBE Technology: A Focus on Chemical Doping

MRS Proceedings ◽

10.1557/proc-299-175 ◽

1994 ◽

Vol 299 ◽

Author(s):

Owen K. Wu

Keyword(s):

Double Layer ◽

Focal Plane ◽

Memory Effects ◽

Current Status ◽

Chemical Doping ◽

Mbe Growth ◽

Heterojunction Structure ◽

P Type ◽

Growth Technology

AbstractHgCdTe MBE technology is becoming a mature growth technology for infrared focal plane array applications. The ability to dope HgCdTe with In(n-type) and As(p-type) dopants in-situ provides greater flexibilities for fabricating heterojunction devices. In this paper, we will first discuss the current status of HgCdTe MBE growth and then focus on the key results in the control of In(n-type) doping, various approaches and breakthroughs in the growth of As(p-type) doped HgCdTe and issues related to doping such as memory effects and dopants activation. In addition, device results from double layer heterojunction structure(DLHJ) will be briefly discussed.

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The Space Infrared Telescope Facility (SIRTF)

International Astronomical Union Colloquium ◽

10.1017/s0252921100077034 ◽

1990 ◽

Vol 123 ◽

pp. 193-203

Author(s):

Giovanni G. Fazio ◽

Peter Eisenhardt

Keyword(s):

Infrared Spectrum ◽

Focal Plane ◽

Infrared Astronomy ◽

Current Status ◽

Earth Orbit ◽

Paper Briefly ◽

Infrared Telescope ◽

Telescope Facility ◽

Imaging And Spectroscopy ◽

Infrared Telescope Facility

AbstractThe Space Infrared Telescope Facility (SIRTF) is a one-meter class observatory for infrared astronomy that will be launched into high earth orbit by NASA in the late 1990’s. SIRTF’s three focal plane instruments will permit imaging and spectroscopy over most of the infrared spectrum with sensitivities of 100 to 10,000 times their predecessors. This paper briefly reviews SIRTF’s capabilities, science objectives, and current status.

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