30 research outputs found
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Precise Measurement of B-mode polarization signal from the cosmic microwave background with Polarbear and the Simons Array
No full textThroughout history, human beings have always sought to answer the question ''what was the origin of the universe?'' The Cosmic Microwave Background (CMB) is one of the most essential scientific tools that will help us better understand the universe. The temperature maps of the CMB have allowed us to study the nature of the early universe through the standard ΛCDM model as well as to describe its evolution. Nevertheless, many questions remain. The next step in finding the answer lies in the measurement of the B-mode polarization of the CMB. These faint signals from the primordial universe are expected to be key pieces of evidence of the inflationary gravitational wave. Successful detection of this B-mode polarization would not only serve as direct evidence of the inflation theory but also lead to constraining of inflationary model and the energy scale of inflation. Moreover, the gravitational lensing of CMB E-mode polarization to B-mode polarization signal at small angular scales will allow us to trace back to the distribution of matter in our universe.This dissertation describes the details of the Polarbear instrument which is designed to detect CMB B-mode polarization. The results from the first and second observational season are also described. Furthermore, this dissertation discusses the development of the Simons Array instrument, which is the expansion of Polarbear with expanded capabilities and increased sensitivity. The Simons Array is scheduled to deploy in 2018
Spatial, socio-economic and demographic variation of childlessness in India: A special reference to reproductive health and marital breakdown
No full textBackground/Objective India observe double burden of fertility – childlessness along with high fertility, which brings it close to a developed country. Childlessness has serious demographic, social and health implications. We explored spatial variation of childlessness women in India along with several socio-economic and demographic correlates. Further we examined maternal and reproductive health problems among childless women and linkages between marital breakdown (divorce) and childlessness, in comparison to fertile women.
Methods Cross-sectional data from 27,505 currently married women, aged 21-49 years, who were interviewed in 1998-99 National Family Health Survey (NFHS-2). These women had been filtered out from all India samples (90,303) based on criteria such as, age more than 20 years, currently not using any family planning methods, marital duration more than 3 years and staying with their husband. Multiple logistic regression analysis was used to estimate the prevalence odds ratios for childlessness, adjusting for various covariates.
Results Overall, 7% of currently married women in India were childless. Southern (10.9) and Western (10.7) region shows highest percentage of childless women while central region exhibits lowest (4.7%) percentage of childlessness. Andhra Pradesh state shows highest percent of childless women (13.3%) followed by Goa (11.8%). Women with high school complete and above education (OR:1.16;p=0.053), women belonging to other religion (OR:1.51;p=0.004), women belonging to other (general) caste (OR:1.20;p=0.007), women belonging to higher standard of living households (OR:1.30;p<0.0001), currently not working women (OR:1.42;p<0.0001), spousal age gap of 15 years and above (OR:1.55;p<0.0001) were more likely to be childless whereas women in rural area (OR:0.53;p<0.0001) and Muslims women (OR:0.53;p<0.0001) were almost half likely to be childless than their counterparts.
Maternal health problems, self reported reproductive health problems and violence against women also emerged significantly higher among childless women than fertile women. Autonomy, examined in terms of women’s decision-making on what to cook and obtaining health care, we found childless women in both type of decision-making are behind the fertile women. The study also found that there is a more than five-fold gap in childlessness between divorced women (37.8%) and currently married women (7%).
GJMEDPH 2012; Vol. 1, issue 6
1Population Council, New Delhi, India 2 South Asia Network for Chronic Disease, Public Health Foundation of India, New Delhi, India
3 Dept. of Mathematical Demography and Statistics, International Institute for Population Sciences, Mumbai, India
*Corresponding Author
South Asia Network for Chronic Disease (SANCD),
Public Health Foundation of India (PHFI),
First Floor, C-1/52 Safdarjung Development Area,
New Delhi 110016, INDIA [email protected] or [email protected]
Conflict of Interest—none
Author’s Contribution
PA conceived and designed the study, analyzed and interpreted the data, and wrote and drafted the manuscript; SU and SA helped for important intellectual content of the manuscript; all authors are responsible for final editing and approval of the manuscript.
1 www.gjmedph.com Vol. 1, No. 6 2012
Conclusion The study has clearly brought out various dimensions of childlessness at the national and state level. Our study indicates wide differences in the prevalence of childlessness among women by their place of residence, religion, caste/tribe status, educational attainment and standard of living. Along with population problems of high fertility in India, the issue of childlessness should also be considered in a more rational manner. More medical facilities especially infertility clinics are needed to address the problems. Going through the miserable situation of childless women in India regarding their poor health, lack of autonomy and social problems, attention is needed to mitigate the psychosocial trauma associated with childlessness
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Understanding the Phase of Responsivity and Noise Sources in Frequency-Domain Multiplexed Readout of Transition Edge Sensor Bolometers
No full textCosmic microwave background (CMB) experiments have deployed focal planes with O(104) transition edge sensor (TES) bolometers cooled to sub-Kelvin temperatures by multiplexing the readout of many TES channels onto a single pair of wires. Digital Frequency-domain Multiplexing (DfMux) is a multiplexing technique used in many CMB polarization experiments, such as the Simons Array, SPT-3 G, and EBEX. The DfMux system studied here uses LC filters with resonant frequencies ranging from 1.5 to 4.5 MHz connected to an array of TESs. Each detector has an amplitude-modulated carrier tone at the resonant frequency of its accompanying LC resonator. The signal is recovered via quadrature demodulation where the in-phase (I) component of the demodulated current is in phase with the complex admittance of the circuit and the quadrature (Q) component is orthogonal to I. Observed excess current noise in the Q component is consistent with fluctuations in the resonant frequency. This noise has been shown to be non-orthogonal to the phase of the detector’s responsivity. We present a detailed analysis of the phase of responsivity of the TES and noise sources in our DfMux readout system. Further, we investigate how modifications to the TES operating resistance and bias frequency can affect the phase of noise relative to the phase of the detector responsivity, using data from Simons Array to evaluate our predictions. We find that both the phase of responsivity and phase of noise are functions of the two tuning parameters, which can be purposefully selected to maximize signal-to-noise (SNR) ratio
Constraints on axion-like polarization oscillations in the cosmic microwave background with POLARBEAR
No full textVery light pseudoscalar fields, often referred to as axions, are compelling
dark matter candidates and can potentially be detected through their coupling
to the electromagnetic field. Recently a novel detection technique using the
cosmic microwave background (CMB) was proposed, which relies on the fact that
the axion field oscillates at a frequency equal to its mass in appropriate
units, leading to a time-dependent birefringence. For appropriate oscillation
periods this allows the axion field at the telescope to be detected via the
induced sinusoidal oscillation of the CMB linear polarization. We search for
this effect in two years of POLARBEAR data. We do not detect a signal, and
place a median upper limit of on the sinusoid amplitude
for oscillation frequencies between and
, which corresponds to axion masses between and . Under the
assumptions that 1) the axion constitutes all the dark matter and 2) the axion
field amplitude is a Rayleigh-distributed stochastic variable, this translates
to a limit on the axion-photon coupling .Comment: 17 pages, 5 figures, 2 tables. Published in Physical Review
Design and performance of a gain calibration system for the POLARBEAR-2a receiver system at the Simons Array cosmic microwave background experiment
No full textWe present an advanced system for calibrating the detector gain responsivity with a chopped thermal source for POLARBEAR-2a, which is the first receiver system of a cosmic microwave background (CMB) polarimetry experiment: the Simons Array. Intensity-to-polarization leakage due to calibration errors between detectors can be a significant source of systematic error for a polarization-sensitive experiment. To suppress this systematic uncertainty, POLARBEAR-2a calibrates the detector gain responsivities by observing a chopped thermal source before and after each period of science observations. The system includes a high-temperature ceramic heater that emits blackbody radiation covering a wide frequency range and an optical chopper to modulate the radiation signal. We discuss the experimental requirements of gain calibration and system design to calibrate POLARBEAR-2a. We evaluate the performance of our system during the early commissioning of the receiver system. This calibration system is promising for the future generation of CMB ground-based polarization observations
Design and performance of a gain calibration system for the POLARBEAR-2a receiver system at the Simons Array cosmic microwave background experiment
No full textWe present an advanced system for calibrating the detector gain responsivity with a chopped thermal source for POLARBEAR-2a, which is the first receiver system of a cosmic microwave background (CMB) polarimetry experiment: the Simons Array. Intensity-to-polarization leakage due to calibration errors between detectors can be a significant source of systematic error for a polarization-sensitive experiment. To suppress this systematic uncertainty, POLARBEAR-2a calibrates the detector gain responsivities by observing a chopped thermal source before and after each period of science observations. The system includes a high-temperature ceramic heater that emits blackbody radiation covering a wide frequency range and an optical chopper to modulate the radiation signal. We discuss the experimental requirements of gain calibration and system design to calibrate POLARBEAR-2a. We evaluate the performance of our system during the early commissioning of the receiver system. This calibration system is promising for the future generation of CMB ground-based polarization observations
Development of an optical detector testbed for the Simons Observatory
No full textThe Simons Observatory (SO) is a cosmic microwave background (CMB) survey experiment with three small-aperture telescopes and one large-aperture telescope, which will observe from the Atacama Desert in Chile. In total, SO will field over 60,000 transition edge sensor (TES) bolometers in six spectral bands centered between 27 and 280 GHz in order to achieve the sensitivity necessary to measure or constrain numerous cosmological quantities, as outlined in The Simons Observatory Collaboration et al. (2019). To verify consistency of fabrication and performance in line with our sensitivity requirements, we will perform in-lab optical tests on isolated SO detectors as well as full detector arrays. The tests include beam measurements, bandpass measurements, and polarization measurements, among others. Here, we will describe the development of a cryogenic testbed that enables optical characterization of SO's detectors. We include the infrared filtering strategy to allow suitable cryogenic performance, design and implementation of the test equipment used in characterization, and the preliminary results from our validation of the testbed's cryo-optical performance...
Multichroic dual-polarization bolometric detectors for studies of the cosmic microwave background
No full textWe are developing multi-chroic antenna-coupled Transition Edge Sensor (TES) focal planes for Cosmic Microwave Background (CMB) polarimetry. In each pixel, a dual polarized sinuous antenna collects light over a two-octave frequency band. Each antenna couples to the telescope with a contacting silicon lens. The antenna couples the broadband RF signal to microstrip transmission lines, and then filter banks split the broadband signal into several frequency bands. A TES bolometer detects the power in each band and polarization. We will describe the design of
this device and demonstrate its performance with optical data measured using prototype pixels. Our measurements show low ellipticity beams, low cross-polarization, and properly partitioned bands in banks of 2, 3, and 7 filters. Finally, we will describe how we will upgrade the POLARBEAR CMB experiment using the focal planes of these detectors to increase the experiment’s mapping speed and its ability to discriminate between the CMB and polarized foregrounds
Data acquisition and management system for the CMB polarization experiment: Simons Array
No full textA Measurement of Atmospheric Circular Polarization with POLARBEAR
No full textInternational audienceAt millimeter wavelengths, the atmospheric emission is circularly polarized owing to the Zeeman splitting of molecular oxygen by the Earth's magnetic field. We report a measurement of the signal in the 150 GHz band using 3 yr of observational data with the Polarbear project. Nonidealities of a continuously rotating half-wave plate (HWP) partially convert circularly polarized light to linearly polarized light. While Polarbear detectors are sensitive to linear polarization, this effect makes them sensitive to circular polarization. Although this was not the intended use, we utilized this conversion to measure circular polarization. We reconstruct the azimuthal gradient of the circular polarization signal and measure its dependency from the scanning direction and the detector bandpass. We compare the signal with a simulation based on atmospheric emission theory, the detector bandpass, and the HWP leakage spectrum model. We find the ratio of the observed azimuthal slope to the simulated slope is 0.92 ± 0.01(stat) ± 0.07(sys). This ratio corresponds to a brightness temperature of 3.8 mK at the effective band center of 121.8 GHz and bandwidth of 3.5 GHz estimated from representative detector bandpass and the spectrum of Zeeman emission. This result validates our understanding of the instrument and reinforces the feasibility of measuring the circular polarization using the imperfection of continuously rotating HWP. Continuously rotating HWP is popular in ongoing and future cosmic microwave background experiments to modulate the polarized signal. This work shows a method for signal extraction and leakage subtraction that can help measure circular polarization in such experiments
