For the future satellite mission at the second sun–earth Lagrangian point (L2), we need to mitigate phonon propagation created by cosmic rays to superconducting detectors. We simulate phonon ...propagation in silicon substrate and show that putting a metal layer on the substrate or making hole in the substrate reduces the propagation. We also show a function which shows the response of a TES bolometer on a substrate. To validate these theoretical expectations, we make irradiation tests using two types of superconducting detectors: transition edge sensor bolometers and kinetic inductance detectors. From the tests, we show that putting metal can reduce correlations between detectors and number of hit events from charged particles.
Status of the Belle silicon vertex detector Natkaniec, Z.; Aihara, H.; Asano, Y. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2006, Volume:
560, Issue:
1
Journal Article
Peer reviewed
The old silicon vertex detector (SVD1) of the Belle detector, operating at the high-luminosity asymmetric energy e+e− collider KEKB, was replaced by an upgraded version (SVD2) in 2003. The new ...detector has modified geometry and redesigned readout electronics, providing a larger polar angle acceptance, better vertex resolution, improved radiation hardness and reduced dead time. The operation of the detector started successfully in October 2003. The basic concepts of the SVD2 design as well as its performance after 10 months of data taking are described in this paper.
Cosmic microwave background (CMB) radiation is an afterglow from the Big Bang. CMB contains rich information about the early stage of the universe. In particular, odd-parity patterns (
B
-mode) in ...the CMB polarization on a large angular scale would provide an evidence of the cosmic inflation. The aim of the GroundBIRD experiment is to observe the
B
-mode on large angular scales from the ground. One of the most novel characteristics of the telescope used for this experiment is its rapid rotational scanning technique. In addition, the telescope uses cold optics and microwave kinetic inductance detectors. We have developed a telescope mount with a three-axis rotation mechanism (azimuth, elevation, and boresight) and measured the vibration at the focal plane stage at 20 RPM scan rotation rate. We also performed focal plane detector tests on this mount. The tests confirmed the expected response from the geomagnetism associated with the mount rotation. We have also developed a design for the magnetic shields and a detector array on a 3-in wafer. The preparations to begin the observations at the Teide Observatory in the Canary Islands in 2018 are proceeding smoothly.
GroundBIRD is a ground-based experiment designed to detect large angular scale odd-parity patterns in the cosmic microwave background (CMB) polarization (
B
-modes). We employ a high-speed rotation ...scan (20 rpm) instead of the usual left–right azimuthal scan; it allows a significant expansion of the scan range to
60
∘
without any effect from the detector
1
/
f
noise. We use microwave kinetic inductance detectors (MKIDs) arrays with a small telescope; our target multipole (
ℓ
) range is
6
≤
ℓ
≤
300
. We plan to start the test observation in Japan in 2014; these will then be moved to the Atacama highland in Chile for scientific observations.
ABSTRACT We present polarization observations of two Galactic plane fields centered on Galactic coordinates (l, b) = (0°, 0°) and (329°, 0°) at both Q (43 GHz) and W bands (95 GHz), covering between ...301 and 539 square degrees depending on frequency and field. These measurements were made with the QUIET instrument between 2008 October and 2010 December, and include a total of 1263 hr of observations. The resulting maps represent the deepest large-area Galactic polarization observations published to date at the relevant frequencies with instrumental rms noise varying between 1.8 and 2.8 K deg, 2.3-6 times deeper than corresponding WMAP and Planck maps. The angular resolution is 27 3 and 12 8 FWHM at Q and W bands, respectively. We find excellent agreement between the QUIET and WMAP maps over the entire fields, and no compelling evidence for significant residual instrumental systematic errors in either experiment, whereas the Planck 44 GHz map deviates from these in a manner consistent with reported systematic uncertainties for this channel. We combine QUIET and WMAP data to compute inverse-variance-weighted average maps, effectively retaining small angular scales from QUIET and large angular scales from WMAP. From these combined maps, we derive constraints on several important astrophysical quantities, including a robust detection of polarized synchrotron spectral index steepening of 0.2 off the plane, as well as the Faraday rotation measure toward the Galactic center (RM = −4000 200 rad m−2), all of which are consistent with previously published results. Both the raw QUIET and the co-added QUIET+WMAP maps are made publicly available together with all necessary ancillary information.
We report a thermal analysis of a polarization modulator unit (PMU) for use in a space-borne cosmic microwave background (CMB) project. A measurement of the CMB polarization allows us to probe the ...physics of early universe, and that is the best method to test the cosmic inflation experimentally. One of the key instruments for this science is to use a halfwave plate (HWP) based polarization modulator. The HWP is required to rotate continuously at about 1 Hz below 10 K to minimize its own thermal emission to a detector system. The rotating HWP system at the cryogenic environment can be realized by using a superconducting magnetic bearing (SMB) without significant heat dissipation by mechanical friction. While the SMB achieves the smooth rotation due to the contactless bearing, an estimation of a levitating HWP temperature becomes a challenge. We manufactured a one-eighth scale prototype model of PMU and built a thermal model. We verified our thermal model with the experimental data. We forecasted the projected thermal performance of PMU for a full-scale model based on the thermal model. From this analysis, we discuss the design requirement toward constructing the full-scale model for use in a space environment such as a future CMB satellite mission, LiteBIRD.
The readout of transition-edge sensor (TES) bolometers with a large multiplexing factor is key for the next generation cosmic microwave background (CMB) experiment,
Polarbear
-2 (Suzuki in J Low Temp ...Phys 176:719,
2014
), having 7588 TES bolometers. To enable the large arrays, we have been developing a readout system with a multiplexing factor of 40 in the frequency domain. Extending that architecture to 40 bolometers requires an increase in the bandwidth of the SQUID electronics, above 4 MHz. This paper focuses on cryogenic readout and shows how it affects cross talk and the responsivity of the TES bolometers. A series resistance, such as equivalent series resistance of capacitors for LC filters, leads to non-linear response of the bolometers. A wiring inductance modulates a voltage across the bolometers and causes cross talk. They should be controlled well to reduce systematic errors in CMB observations. We have been developing a cryogenic readout with a low series impedance and have tuned bolometers in the middle of their transition at a high frequency (
>
3 MHz).
Polarbear-2
(PB-2) is a next-generation receiver that is part of the Simons Array cosmic microwave background (CMB) polarization experiment which is located in the Atacama desert in Northern Chile. ...The primary scientific goals of the Simons Array are a deep search for the CMB B-mode signature of gravitational waves from inflation and the characterization of large-scale structure using its effect on CMB polarization. The PB-2 receiver will deploy with 1897 dual-polarization sinuous antenna-coupled pixels, each with a directly contacting extended hemispherical silicon lens. Every pixel has dual polarization sensitivity in two spectral bands centered at 95 and 150 GHz, for a total of 7588 transition edge sensor bolometers operating at 270 mK. To achieve the PB-2 detector requirements, we developed a broadband anti-reflection (AR) coating for the extended hemispherical lenses that uses two molds to apply two layers of epoxy, Stycast 1090 and Stycast 2850FT. Our measurements of the absorption loss from the AR coating on a flat surface at cryogenic temperatures show less than 1 % absorption, and the coating has survived multiple thermal cycles. We can control the diameter of the coating within 25
μ
m and translation errors are within 25
μ
m in all directions, which results in less than 1 % decrease in transmittance. We also find the performance of the AR-coated lens matches very well with simulations.
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