We 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.
We present a precise thermometry system to monitor room-temperature components of a telescope for radio-astronomy such as cosmic microwave background (CMB) observation. The system realizes precision of 1 mKs on a timescale of 20 s at 300 K. We achieved this high precision by tracking only relative fluctuation and combining thermistors with a low-noise measurement device. We show the required precision of temperature monitors for CMB observation and introduce the performance of our thermometry system. This precise room-temperature monitoring system enables us to reduce the low-frequency noise in a wide range of radio-astronomical detector signals observation and to operate a large detector array perform at its designed high sensitivity.
The Simons Array is an experiment located in the Atacama Desert in Chile that will measure the polarization anisotropy of the Cosmic Microwave Background. It consists of three telescopes that house the receivers POLARBEAR-2A, POLARBEAR-2B and POLARBEAR-2C, which will observe the CMB at 90, 150, 220 and 270 GHz with over 22,000 Transition Edge Sensor (TES) bolometers. Each receiver contains a focal plane composed of seven hexagonal arrays of lenslet-coupled sinuous antenna bolometers, with each dichroic pixel containing four TESs. The readout system uses Superconducting Quantum Interference Devices for signal amplification and digital frequency-domain multiplexing with a multiplexing factor of 40. The sensitivity of the Simons Array instruments is governed by the detectors’ noise level and the telescope optical throughput, thus an on-site signal to noise characterization is essential to evaluate the instrument. We present the post-deployment measured readout noise and methods used to improve the noise performance of POLARBEAR-2A detectors, which measure radiation in the 90 and 150 GHz bands.
LiteBIRD, the Lite (Light) satellite for the study of B-mode polarization and Inflation from cosmic background Radiation Detection, is a space mission for primordial cosmology and fundamental physics. JAXA selected LiteBIRD in May 2019 as a strategic large-class (L-class) mission, with its expected launch in the late 2020s using JAXA's H3 rocket. LiteBIRD plans to map the cosmic microwave background (CMB) polarization over the full sky with unprecedented precision. Its main scientific objective is to carry out a definitive search for the signal from cosmic inflation, either making a discovery or ruling out well-motivated inflationary models. The measurements of LiteBIRD will also provide us with an insight into the quantum nature of gravity and other new physics beyond the standard models of particle physics and cosmology. To this end, LiteBIRD will perform full-sky surveys for three years at the Sun-Earth Lagrangian point L2 for 15 frequency bands between 34 and 448 GHz with three telescopes, to achieve a total sensitivity of 2.16 μK-arcmin with a typical angular resolution of 0.5° at 100 GHz. We provide an overview of the LiteBIRD project, including scientific objectives, mission requirements, top-level system requirements, operation concept, and expected scientific outcomes.
The Simons Observatory (SO) will be a cosmic microwave background (CMB) survey experiment with three small-aperture telescopes (SATs) and one large-aperture telescope (LAT), 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. The SATs are optimized for a primordial gravitational wave signal in a parity odd polarization power spectrum at a large angular scale. We will present the latest status of the SAT development.
LiteBIRD has been selected as JAXA’s strategic large mission in the 2020s, to observe the cosmic microwave background (CMB) B-mode polarization over the full sky at large angular scales. The challenges of LiteBIRD are the wide field-of-view (FoV) and broadband capabilities of millimeter-wave polarization measurements, which are derived from the system requirements. The possible paths of stray light increase with a wider FoV and the far sidelobe knowledge of -56 dB is a challenging optical requirement. A crossed-Dragone configuration was chosen for the low frequency telescope (LFT : 34–161 GHz), one of LiteBIRD’s onboard telescopes. It has a wide field-of-view (18° x 9°) with an aperture of 400 mm in diameter, corresponding to an angular resolution of about 30 arcminutes around 100 GHz. The focal ratio f/3.0 and the crossing angle of the optical axes of 90◦ are chosen after an extensive study of the stray light. The primary and secondary reflectors have rectangular shapes with serrations to reduce the diffraction pattern from the edges of the mirrors. The reflectors and structure are made of aluminum to proportionally contract from warm down to the operating temperature at 5 K. A 1/4 scaled model of the LFT has been developed to validate the wide field-of-view design and to demonstrate the reduced far sidelobes. A polarization modulation unit (PMU), realized with a half-wave plate (HWP) is placed in front of the aperture stop, the entrance pupil of this system. A large focal plane with approximately 1000 AlMn TES detectors and frequency multiplexing SQUID amplifiers is cooled to 100 mK. The lens and sinuous antennas have broadband capability. Performance specifications of the LFT and an outline of the proposed verification plan are presented.
LiteBIRD is a JAXA-led Strategic Large-Class mission designed to search for the existence of the primordial gravitational waves produced during the inflationary phase of the Universe, through the measurements of their imprint onto the polarization of the cosmic microwave background (CMB). These measurements, requiring unprecedented sensitivity, will be performed over the full sky, at large angular scales, and over 15 frequency bands from 34 GHz to 448 GHz. The LiteBIRD instruments consist of three telescopes, namely the Low-, Medium-and High-Frequency Telescope (respectively LFT, MFT and HFT). We present in this paper an overview of the design of the Medium-Frequency Telescope (89{224 GHz) and the High-Frequency Telescope (166{448 GHz), the so-called MHFT, under European responsibility, which are two cryogenic refractive telescopes cooled down to 5 K. They include a continuous rotating half-wave plate as the first optical element, two high-density polyethylene (HDPE) lenses and more than three thousand transition-edge sensor (TES) detectors cooled to 100 mK. We provide an overview of the concept design and the remaining specific challenges that we have to face in order to achieve the scientific goals of LiteBIRD.
The Simons Array upgrades the POLARBEAR experiment, which measures the cosmic microwave background from the Atacama Desert in Chile, with three newly developed receivers. Each receiver has 7,588 transition-edge sensor bolometers with a raw data rate of approximately 20 MB/s. This significantly increased data rate required us to develop a new data-acquisition (DAQ) and data-management system. As the network bandwidth from our observatory to our data-storage sites outside Chile is not high enough to send all the raw data, we compress the raw data on-site. The expected yearly compressed data rate is approximately 60 TB from each receiver. We have also developed a new housekeeping DAQ system. The new housekeeping DAQ system is a distributed system to handle the various newly added monitoring systems and to better understand our instruments and environments. Those data can also be fetched by another module for real-time monitoring of our instrument from all over the world with latencies on the order of minutes. We deployed the first receiver in late 2018 and started the commissioning of the DAQ system. The DAQ system has been working without significant problems and already accumulates a considerable amount of the new receiver data from the commissioning observations. In this presentation, we summarize and report the status of the new systems.
LiteBIRD is a candidate for JAXA’s strategic large mission to observe the cosmic microwave background (CMB) polarization over the full sky at large angular scales. It is planned to be launched in the 2020s with an H3 launch vehicle for three years of observations at a Sun-Earth Lagrangian point (L2). The concept design has been studied by researchers from Japan, U.S., Canada and Europe during the ISAS Phase-A1. Large scale measurements of the CMB B-mode polarization are known as the best probe to detect primordial gravitational waves. The goal of LiteBIRD is to measure the tensor-to-scalar ratio (r) with precision of r < 0:001. A 3-year full sky survey will be carried out with a low frequency (34 - 161 GHz) telescope (LFT) and a high frequency (89 - 448 GHz) telescope (HFT), which achieve a sensitivity of 2.5 μK-arcmin with an angular resolution 30 arcminutes around 100 GHz. The concept design of LiteBIRD system, payload module (PLM), cryo-structure, LFT and verification plan is described in this paper.
POLARBEAR is a cosmic microwave background (CMB) polarization experiment located in the Atacama desert in Chile. The science goals of the POLARBEAR project are to do a deep search for CMB B-mode polarization created by inflationary gravitational waves, as well as characterize the CMB B-mode signal from gravitational lensing. POLARBEAR-1 started observations in 2012, and the POLARBEAR team has published a series of results from its first two seasons of observations, including the first measurement of a non-zero B-mode polarization angular power spectrum, measured at sub-degree scales where the dominant signal is gravitational lensing of the CMB. The Simons Array expands POLARBEAR to include an additional two telescopes with next-generation POLARBEAR-2 multi-chroic receivers, observing at 95, 150, 220, and 270 GHz.
The POLARBEAR-2A focal plane has 7,588 transition-edge sensor bolometers, read out with frequency-division multiplexing, with 40 frequency channels within the readout bandwidth of 1.5 to 4.5 MHz. The frequency channels are defined by a low-loss lithographed aluminum spiral inductor and interdigitated capacitor in series with each bolometer, creating a resonant frequency for each channel's unique voltage bias and current readout. Characterization of the readout includes measuring resonant peak locations and heights and fitting to a circuit model both above and below the bolometer superconducting transition temperature. This information is used determine the optimal detector bias frequencies and characterize stray impedances which may affect bolometer operation and stability. The detector electrical characterization includes measurements of the transition properties by sweeping in temperature and in voltage bias, measurements of the bolometer saturation power, as well as measuring and removing any biases introduced by the readout circuit. We present results from the characterization, tuning, and operation of the fully integrated focal plane and readout for the first POLARBEAR-2 receiver, POLARBEAR-2A, during its pre-deployment integration run.
POLARBEAR-2 is a new receiver system, which will be deployed on the Simons Array telescope platform, for the measurement of Cosmic Microwave Background (CMB) polarization. The science goals with POLARBEAR-2 are to characterize the B-mode signal both at degree and sub-degree angular-scales. The degree-scale polarization data can be used for quantitative studies on inflation, such as the reconstruction of the energy scale of inflation. The sub-degree polarization data is an excellent tracer of large-scale structure in the universe, and will lead to precise constraints on the sum of the neutrino masses. In order to achieve these goals, POLARBEAR-2 employs 7588 polarization-sensitive antenna-coupled transition-edge sensor (TES) bolometers on the focal plane cooled to 0.27K with a three-stage Helium sorption refrigerator, which is ~6 times larger array over the current receiver system. The large TES bolometer array is read-out by an upgraded digital frequency-domain multiplexing system capable of multiplexing 40 bolometers through a single superconducting quantum interference device (SQUID).
The first POLARBEAR-2 receiver, POLARBEAR-2A is constructed and the end-to-end testing to evaluate the integrated performance of detector, readout, and optics system is being conducted in the laboratory with various types of test equipments. The POLARBEAR-2A is scheduled to be deployed in 2018 at the Atacama desert in Chile. To further increase measurement sensitivity, two more POLARBEAR-2 type receivers will be deployed soon after the deployment (Simons Array project). The Simons Array will cover four frequency bands at 95GHz, 150GHz, 220GH and 270GHz for better control of the foreground signal. The projected constraints on a tensor-to-scalar ratio (amplitude of inflationary B-mode signal) is σ(r=0.1) = $6.0 \times 10^{-3}$ after foreground removal ($4.0 \times 10^{-3}$ (stat.)), and the sensitivity to the sum of the neutrino masses when combined with DESI spectroscopic galaxy survey data is 40 meV at 1-sigma after foreground removal (19 meV(stat.)).
We will present an overview of the design, assembly and status of the laboratory testing of the POLARBEAR-2A receiver system as well as the Simons Array project overview.
Y. Inoue, P. Ade, Y. Akiba, C. Aleman, K. Arnold, C. Baccigalupi, B. Barch, D. Barron, A. Bender, D. Boettger, J. Borrill, S. Chapman, Y. Chinone, A. Cukierman, T. de Haan, M. Dobbs, A. Ducout, R. Dünner, T. Elleflot, J. Errard, G. Fabbian, S. Feeney, C. Feng, G. Fuller, A. Gilbert, N. Goeckner-Wald, J. Groh, G. Hall, N. Halverson, T. Hamada, M. Hasegawa, K. Hattori, M. Hazumi, C. Hill, W. Holzapfel, Y. Hori, L. Howe, F. Irie, G. Jaehnig, A. Jaffe, O. Jeong, N. Katayama, J. Kaufman, K. Kazemzadeh, B. Keating, Z. Kermish, R. Keskitalo, T. Kisner, A. Kusaka, M. Le Jeune, A. Lee, D. Leon, E. Linder, L. Lowry, F. Matsuda, T. Matsumura, N. Miller, K. Mizukami, J. Montgomery, M. Navaroli, H. Nishino, H. Paar, J. Peloton, D. Poletti, G. Puglisi, C. Raum, G. Rebeiz, C. Reichardt, P. Richards, C. Ross, K. Rotermund, Y. Segawa, B. Sherwin, I. Shirley, P. Siritanasak, N. Stebor, R. Stompor, J. Suzuki, A. Suzuki, O. Tajima, S. Takada, S. Takatori, G. Teply, A. Tikhomirov, T. Tomaru, N. Whitehorn, A. Zahn, O. Zahn
POLARBEAR-2 (PB-2) is a cosmic microwave background (CMB) polarization experiment that will be located in the Atacama highland in Chile at an altitude of 5200 m. Its science goals are to measure the CMB polarization signals originating from both primordial gravitational waves and weak lensing. PB-2 is designed to measure the tensor to scalar ratio, r, with precision σ(r) > 0:01, and the sum of neutrino masses, Σmz, with σ(Σmv) < 90 meV. To achieve these goals, PB-2 will employ 7588 transition-edge sensor bolometers at 95 GHz and 150 GHz, which will be operated at the base temperature of 250 mK. Science observations will begin in 2017.
LiteBIRD is a next generation satellite aiming for the detection of the Cosmic Microwave Background (CMB) B-mode polarization imprinted by the primordial gravitational waves generated in the era of the inflationary universe. The science goal of LiteBIRD is to measure the tensor-to-scaler ratio r with a precision of δr < 10-3♦, offering us a crucial test of the major large-single-field slow-roll inflation models. LiteBIRD is planned to conduct an all sky survey at the sun-earth second Lagrange point (L2) with an angular resolution of about 0.5 degrees to cover the multipole moment range of 2 ≤ ℓ ≤ 200. We use focal plane detector arrays consisting of 2276 superconducting detectors to measure the frequency range from 40 to 400 GHz with the sensitivity of
3.2 μK·arcmin. including the ongoing studies.
N. Stebor, P. Ade, Y. Akiba, C. Aleman, K. Arnold, C. Baccigalupi, B. Barch, D. Barron, S. Beckman, A. Bender, D. Boettger, J. Borrill, S. Chapman, Y. Chinone, A. Cukierman, T. de Haan, M. Dobbs, A. Ducout, R. Dunner, T. Elleflot, J. Errard, G. Fabbian, S. Feeney, C. Feng, T. Fujino, G. Fuller, A. Gilbert, N. Goeckner-Wald, J. Groh, G. Hall, N. Halverson, T. Hamada, M. Hasegawa, K. Hattori, M. Hazumi, C. Hill, W. Holzapfel, Y. Hori, L. Howe, Y. Inoue, F. Irie, G. Jaehnig, A. Jaffe, O. Jeong, N. Katayama, J. Kaufman, K. Kazemzadeh, B. Keating, Z. Kermish, R. Keskitalo, T. Kisner, A. Kusaka, M. Le Jeune, A. Lee, D. Leon, E. Linder, L. Lowry, F. Matsuda, T. Matsumura, N. Miller, J. Montgomery, M. Navaroli, H. Nishino, H. Paar, J. Peloton, D. Poletti, G. Puglisi, C. Raum, G. Rebeiz, C. Reichardt, P. Richards, C. Ross, K. Rotermund, Y. Segawa, B. Sherwin, I. Shirley, P. Siritanasak, L. Steinmetz, R. Stompor, A. Suzuki, O. Tajima, S. Takada, S. Takatori, G. Teply, A. Tikhomirov, T. Tomaru, B. Westbrook, N. Whitehorn, A. Zahn, O. Zahn
The Simons Array is a next generation cosmic microwave background (CMB) polarization experiment whose science target is a precision measurement of the B-mode polarization pattern produced both by inflation and by gravitational lensing. As a continuation and extension of the successful POLARBEAR experimental program, the Simons Array will consist of three cryogenic receivers each featuring multichroic bolometer arrays mounted onto separate 3.5m telescopes. The first of these, also called POLARBEAR-2A, will be the first to deploy in late 2016 and has a large diameter focal plane consisting of dual-polarization dichroic pixels sensitive at 95 GHz and 150 GHz. The POLARBEAR-2A focal plane will utilize 7,588 antenna-coupled superconducting transition edge sensor (TES) bolometers read out with SQUID amplifiers using frequency domain multiplexing techniques. The next two receivers that will make up the Simons Array will be nearly identical in overall design but will feature extended frequency capability. The combination of high sensitivity, multichroic frequency coverage and large sky area available from our mid-latitude Chilean observatory will allow Simons Array to produce high quality polarization sky maps over a wide range of angular scales and to separate out the CMB B-modes from other astrophysical sources with high fidelity. After accounting for galactic foreground separation, the Simons Array will detect the primordial gravitational wave B-mode signal to r > 0.01 with a significance of > 5σ and will constrain the sum of neutrino masses to 40 meV (1σ) when cross-correlated with galaxy surveys. We present the current status of this funded experiment, its future, and discuss its projected science return.
The Simons Array is an expansion of the POLARBEAR cosmic microwave background (CMB) polarization experiment currently observing from the Atacama Desert in Northern Chile. This expansion will create an array of three 3.5m telescopes each coupled to a multichroic bolometric receiver. The Simons Array will have the sensitivity to produce a ≥ 5σ detection of inationary gravitational waves with a tensor-to-scalar ratio r ≥ 0:01, detect the known minimum 58 meV sum of the neutrino masses with 3σ confidence when combined with a next-generation baryon acoustic oscillation measurement, and make a lensing map of large-scale structure over the 80% of the sky available from its Chilean site. These goals require high sensitivity and the ability to extract the CMB signal from contaminating astrophysical foregrounds; these requirements are met by coupling the three high-throughput telescopes to novel multichroic lenslet-coupled pixels each measuring CMB photons in both linear polarization states over multiple spectral bands. We present the status of this instrument already under construction, and an analysis of its capabilities.
Y. Inoue, N. Stebor, P. A. Ade, Y. Akiba, K. Arnold, A. Anthony, M. Atlas, D. Barron, A. Bender, D. Boettger, J. Borrilll, S. Chapman, Y. Chinone, A. Cukierman, M. Dobbs, T. Elleflot, J. Errard, G. Fabbian, C. Feng, A. Gilbert, N. Halverson, M. Hasegawa, K. Hattori, M. Hazumi, W. Holzapfel, Y. Hori, G. Jaehnig, A. Jaffe, N. Katayama, B. Keating, Z. Kermish, Reijo Keskitalo, T. Kisner, M. Le Jeune, A. Lee, E. Leitch, E. Linder, F. Matsuda, T. Matsumura, X. Meng, H. Morii, M. Myers, M. Navaroli, H. Nishino, T. Okamura, H. Paar, J. Peloton, D. Poletti, G. Rebeiz, C. Reichardt, P. Richards, C. Ross, D. Schenck, B. Sherwin, P. Siritanasak, G. Smecher, M. Sholl, B. Steinbach, R. Stompor, A. Suzuki, J. Suzuki, S. Takada, S. Takakura, T. Tomaru, B. Wilson, A. Yadav, H. Yamaguchi, O. Zahn
POLARBEAR-2 (PB-2) is a cosmic microwave background (CMB) polarization experiment for B-mode detection. The PB-2 receiver has a large focal plane and aperture that consists of 7588 transition edge sensor (TES) bolometers at 250 mK. The receiver consists of the optical cryostat housing reimaging lenses and infrared filters, and the detector cryostat housing TES bolometers. The large focal plane places substantial requirements on the thermal design of the optical elements at the 4K, 50K, and 300K stages. Infrared filters and lenses inside the optical cryostat are made of alumina for this purpose. We measure basic properties of alumina, such as the index of refraction, loss tangent and thermal conductivity. All results meet our requirements. We also optically characterize filters and lenses made of alumina. Finally, we perform a cooling test of the entire optical cryostat. All measured temperature values satisfy our requirements. In particular, the temperature rise between the center and edge of the alumina infrared filter at 50 K is only 2:0 ± 1:4 K. Based on the measurements, we estimate the incident power to each thermal stage.
For the next generation of Cosmic Microwave Background (CMB) experiments, kilopixel arrays of Transition Edge Sensor (TES) bolometers are necessary to achieve the required sensitivity and their science goals. We are developing read-out electronics for POLARBEAR-2 CMB experiment, which multiplexes 32-TES bolometers through a single superconducting quantum interface device (SQUID). To increase both the bandwidth of the SQUID electronics and the multiplexing factor, we are modifying cold wiring and developing LC filters, and a low-inductance superconducting cable. Using these components, we will show frequency domain multiplexing up to 3 MHz.
We present the mission design of LiteBIRD, a next generation satellite for the study of B-mode polarization and inflation from cosmic microwave background radiation (CMB) detection. The science goal of LiteBIRD is to measure the CMB polarization with the sensitivity of δr = 0:001, and this allows testing the major single-field slow-roll inflation models experimentally. The LiteBIRD instrumental design is purely driven to achieve this goal. At the earlier stage of the mission design, several key instrumental specifications, e.g. observing band, optical system, scan strategy, and orbit, need to be defined in order to process the rest of the detailed design. We have gone through the feasibility studies for these items in order to understand the tradeoffs between the requirements from the science goal and the compatibilities with a satellite bus system. We describe the overview of LiteBIRD and discuss the tradeoffs among the choices of scientific instrumental specifications and strategies. The first round of feasibility studies will be completed by the end of year 2014 to be ready for the mission definition review and the target launch date is in early 2020s.
POLARBEAR-2 is a next-generation receiver for precision measurements of polarization of the cosmic microwave background, scheduled to deploy in 2015. It will feature a large focal plane, cooled to 250 milliKelvin, with 7,588 polarization-sensitive antenna-coupled transition edge sensor bolometers, read-out with frequency domain multiplexing with 32 bolometers on a single SQUID amplifier. We will present results from testing and characterization of new readout components, integrating these components into a scaled-down readout system for validation of the design and technology.
POLARBEAR-2 is a ground based cosmic microwave background (CMB) radiation experiment observing from Atacama, Chile. The science goals of POLARBEAR-2 are to measure the CMB polarization signals originating from the inflationary gravity-wave background and weak gravitational lensing. In order to achieve these science goals, POLARBEAR-2 employs 7588 polarization sensitive transition edge sensor bolometers at observing fre quencies of 95 and 150 GHz with 5.5 and 3.5 arcmin beam width, respectively. The telescope is the off-axis Gregorian, Huan Tran Telescope, on which the POLARBEAR-1 receiver is currently mounted. The polarimetry is based on modulation of the polarized signal using a rotating half-wave plate and the rotation of the sky. We present the developments of the optical and polarimeter designs including the cryogenically cooled refractive optics that achieve the overall 4 degrees field-of-view, the thermal filter design, the broadband anti-reflection coating, and the rotating half-wave plate.
We propose an innovative demodulation scheme for coherent detectors used in cosmic microwave background polarization experiments. Removal of non-white noise, e.g., narrow-band noise, in detectors is one of the key requirements for the experiments. A combination of modulation and demodulation is used to extract polarization signals as well as to suppress such noise. Traditional demodulation, which is based on the two-point numerical differentiation, works as a first-order high pass filter for the noise. The proposed demodulation is based on the three-point numerical differentiation. It works as a second-order high pass filter. By using a real detector, we confirmed significant improvements of suppression power for the narrow-band noise. We also found improvement of the noise floor, which is from the stronger suppression to the tail of 1/f noise.
K. Arnold, P. A. Ade, A. Anthony, D. Barron, D. Boettger, J. Borrill, S. Chapman, Y. Chinone, M. Dobbs, J. Errard, G. Fabbian, D. Flanigan, G. Fuller, A. Ghribi, W. Grainger, N. Halverson, M. Hasegawa, K. Hattori, M. Hazumi, W. Holzapfel, J. Howard, P. Hyland, A. Jaffe, B. Keating, Z. Kermish, T. Kisner, M. Le Jeune, A. Lee, E. Linder, M. Lungu, F. Matsuda, T. Matsumura, N. Miller, X. Meng, H. Morii, S. Moyerman, M. Myers, H. Nishino, H. Paar, E. Quealy, C. Reichardt, P. Richards, C. Ross, A. Shimizu, C. Shimmin, M. Shimon, M. Sholl, P. Siritanasak, H. Spieler, N. Stebor, B. Steinbach, R. Stompor, A. Suzuki, T. Tomaru, C. Tucker, O. Zahn
The POLARBEAR Cosmic Microwave Background (CMB) polarization experiment is currently observing from the Atacama Desert in Northern Chile. It will characterize the expected B-mode polarization due to gravitational lensing of the CMB, and search for the possible B-mode signature of inflationary gravitational waves. Its 250 mK focal plane detector array consists of 1,274 polarization-sensitive antenna-coupled bolometers, each with an associated lithographed band-defining filter. Each detector’s planar antenna structure is coupled to the telescope’s optical system through a contacting dielectric lenslet, an architecture unique in current CMB experiments. We present the initial characterization of this focal plane.
Polarimeters used in cosmic microwave background (CMB) experiments must be well calibrated to measure
faint CMB polarization patterns with low systematic errors. Polarimeter characteristics generally vary with
the incident load temperature (Tload). Therefore, re-producing the observing conditions in the laboratory is an
important concern. For polarimeters, we developed a characterization system with cryogenically cooled loads.
The loads generate unpolarized radiation (15 K and 30 K), comparable to the typical sky temperature of the
best sites on the ground, e.g., the Atacama Desert in Chile (Tload ∼ 15 K). The radiation from the loads is
reflected by a metal mirror in the cryostat, yielding partially polarized radiation (600 mK), entering a feed horn
on the polarimeter. Rotation of the mirror alters the incident angle of the polarization and causes periodic
switching of the load temperature for Y -factor measurements. We demonstrated the validity of the system using
a polarimeter developed for an upgrade of QUIET (QUIET-II), which can obtain the Stokes parameters I, Q,
and U simultaneously. The system characterized all the necessary properties, e.g., the responses for I, Q, and
U, and their crosstalk. In addition, a wide range of polarimeter bias conditions was surveyed. The principle of
the characterization system is not limited to a particular frequency or detection scheme. Thus, various types of
state-of-the-art detectors can be calibrated by using this system.
Zigmund Kermish, Peter Ade, Aubra Anthony, Kam Arnold, Darcy Barron, David Boettger, Julian Borrill, Scott Chapman, Yuji Chinone, Matt Dobbs, Josquin Errard, Giulio Fabbian, Daniel Flanigan, George Fuller, Adnan Ghribi, Will Grainger, Nils Halverson, Masaya Hasegawa, Kaori Hattori, Masashi Hazumi, William Holzapfel, Jacob Howard, Peter Hyland, Andrew Jaffe, Brian Keating, Theodore Kisner, Adrian Lee, Maude Le Jeune, Eric Linder, Marius Lungu, Frederick Matsuda, Tomotake Matsumura, Xiaofan Meng, Nathan Miller, Hideki Morii, Stephanie Moyerman, Mike Myers, Haruki Nishino, Hans Paar, Erin Quealy, Christian Reichardt, Paul Richards, Colin Ross, Akie Shimizu, Meir Shimon, Chase Shimmin, Mike Sholl, Praween Siritanasak, Helmuth Spieler, Nathan Stebor, Bryan Steinbach, Radek Stompor, Aritoki Suzuki, Takayuki Tomaru, Carole Tucker, Oliver Zahn
We present the design and characterization of the POLARBEAR experiment. POLARBEAR will measure the polarization of the cosmic microwave background (CMB) on angular scales ranging from the experiment’s 3.5’ beam size to several degrees. The experiment utilizes a unique focal plane of 1,274 antenna-coupled, polarization sensitive TES bolometers cooled to 250 milliKelvin. Employing this focal plane along with stringent control over systematic errors, POLARBEAR has the sensitivity to detect the expected small scale B-mode signal due to gravitational lensing and search for the large scale B-mode signal from inflationary gravitational waves. POLARBEAR was assembled for an engineering run in the Inyo Mountains of California in 2010 and was deployed in late 2011 to the Atacama Desert in Chile. An overview of the instrument is presented along with characterization results from observations in Chile.
POLARBEAR-2 (PB-2) is a cosmic microwave background (CMB) polarization experiment observing at Atacama plateau in Chile. PB-2 is designed to improve the sensitivity to measure the CMB B-mode polarization by upgrading the current POLARBEAR-1 receiver that is currently mounted on the Huan Tran telescope. The improvements in PB-2 include, i) the dual band observations at 95 GHz and 150 GHz in each pixel using an sinuous antenna, ii) the increase of the total number of detectors, 7588 Al-Ti bilayer transition-edge sensor (TES) bolometers, iii) the bath temperature of bolometers at 100mK in the second phase of observation (300mK in the first phase.) With the expected sensitivity of 5.7 μK √ s, PB-2 is sensitive to a tensor-to-scalar ratio, r, of 0.01 at 95% confidence level (CL) and constrains the sum of neutrino masses as 90meV by PB-2 alone and 40meV by combining PB-2 and Planck at 68% CL. We schedule to deploy in 2014.
LiteBIRD [Lite (Light) satellite for the studies of B-mode polarization and Inflation from cosmic background
Radiation Detection] is a small satellite to map the polarization of the cosmic microwave background (CMB)
radiation over the full sky at large angular scales with unprecedented precision. Cosmological inflation, which
is the leading hypothesis to resolve the problems in the Big Bang theory, predicts that primordial gravitational
waves were created during the inflationary era. Measurements of polarization of the CMB radiation are known as
the best probe to detect the primordial gravitational waves. The LiteBIRD working group is authorized by the
Japanese Steering Committee for Space Science (SCSS) and is supported by JAXA. It has more than 50 members
from Japan, USA and Canada. The scientific objective of LiteBIRD is to test all the representative inflation models that satisfy single-field slow-roll conditions and lie in the large-field regime. To this end, the requirement
on the precision of the tensor-to-scalar ratio, r, at LiteBIRD is equal to or less than 0.001. Our baseline design
adopts an array of multi-chroic superconducting polarimeters that are read out with high multiplexing factors in
the frequency domain for a compact focal plane. The required sensitivity of 1.8μKarcmin is achieved with 2000
TES bolometers at 100mK. The cryogenic system is based on the Stirling/JT technology developed for SPICA,
and the continuous ADR system shares the design with future X-ray satellites.
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