13 research outputs found
EBEX: a balloon-borne CMB polarization experiment
EBEX is a NASA-funded balloon-borne experiment designed to measure the polarization of the cosmic microwave background (CMB). Observations will be made using 1432 transition edge sensor (TES) bolometric detectors read out with frequency multiplexed SQuIDs. EBEX will observe in three frequency bands centered at 150, 250, and 410 GHz, with 768, 384, and 280 detectors in each band, respectively. This broad frequency coverage is designed to provide valuable information about polarized foreground signals from dust. The polarized sky signals will be modulated with an achromatic half wave plate (AHWP) rotating on a superconducting magnetic bearing (SMB) and analyzed with a fixed wire grid polarizer. EBEX will observe a patch covering ~1% of the sky with 8' resolution, allowing for observation of the angular power spectrum from l = 20 to 1000. This will allow EBEX to search for both the primordial B-mode signal predicted by inflation and the anticipated lensing B-mode signal. Calculations to predict EBEX constraints on r using expected noise levels show that, for a likelihood centered around zero and with negligible foregrounds, 99% of the area falls below r = 0.035. This value increases by a factor of 1.6 after a process of foreground subtraction. This estimate does not include systematic uncertainties. An engineering flight was launched in June, 2009, from Ft. Sumner, NM, and the long duration science flight in Antarctica is planned for 2011. These proceedings describe the EBEX instrument and the North American engineering flight
A high-resolution pointing system for fast scanning platforms: The EBEX example
The E and B experiment (EBEX) is a balloon-borne telescope designed to
measure the polarization of the cosmic microwave background with 8' resolution
employing a gondola scanning with speeds of order degree per second. In January
2013, EBEX completed 11 days of observations in a flight over Antarctica
covering 6000 square degrees of the sky. The payload is equipped with
two redundant star cameras and two sets of three orthogonal gyroscopes to
reconstruct the telescope attitude. The EBEX science goals require the pointing
to be reconstructed to approximately 10" in the map domain, and in-flight
attitude control requires the real time pointing to be accurate to
0.5 . The high velocity scan strategy of EBEX coupled to its float
altitude only permits the star cameras to take images at scan turnarounds,
every 40 seconds, and thus requires the development of a pointing system
with low noise gyroscopes and carefully controlled systematic errors. Here we
report on the design of the pointing system and on a simulation pipeline
developed to understand and minimize the effects of systematic errors. The
performance of the system is evaluated using the 2012/2013 flight data, and we
show that we achieve a pointing error with RMS=25" on 40 seconds azimuth
throws, corresponding to an error of 4.6" in the map domain.Comment: 14 pages, Proceedings of the 2015 IEEE Aerospace Conferenc
Software systems for operation, control, and monitoring of the EBEX instrument
We present the hardware and software systems implementing autonomous
operation, distributed real-time monitoring, and control for the EBEX
instrument. EBEX is a NASA-funded balloon-borne microwave polarimeter designed
for a 14 day Antarctic flight that circumnavigates the pole. To meet its
science goals the EBEX instrument autonomously executes several tasks in
parallel: it collects attitude data and maintains pointing control in order to
adhere to an observing schedule; tunes and operates up to 1920 TES bolometers
and 120 SQUID amplifiers controlled by as many as 30 embedded computers;
coordinates and dispatches jobs across an onboard computer network to manage
this detector readout system; logs over 3~GiB/hour of science and housekeeping
data to an onboard disk storage array; responds to a variety of commands and
exogenous events; and downlinks multiple heterogeneous data streams
representing a selected subset of the total logged data. Most of the systems
implementing these functions have been tested during a recent engineering
flight of the payload, and have proven to meet the target requirements. The
EBEX ground segment couples uplink and downlink hardware to a client-server
software stack, enabling real-time monitoring and command responsibility to be
distributed across the public internet or other standard computer networks.
Using the emerging dirfile standard as a uniform intermediate data format, a
variety of front end programs provide access to different components and views
of the downlinked data products. This distributed architecture was demonstrated
operating across multiple widely dispersed sites prior to and during the EBEX
engineering flight.Comment: 11 pages, to appear in Proceedings of SPIE Astronomical Telescopes
and Instrumentation 2010; adjusted metadata for arXiv submissio
EBEX: A balloon-borne CMB polarization experiment
EBEX is a NASA-funded balloon-borne experiment designed to measure the
polarization of the cosmic microwave background (CMB). Observations will be
made using 1432 transition edge sensor (TES) bolometric detectors read out with
frequency multiplexed SQuIDs. EBEX will observe in three frequency bands
centered at 150, 250, and 410 GHz, with 768, 384, and 280 detectors in each
band, respectively. This broad frequency coverage is designed to provide
valuable information about polarized foreground signals from dust. The
polarized sky signals will be modulated with an achromatic half wave plate
(AHWP) rotating on a superconducting magnetic bearing (SMB) and analyzed with a
fixed wire grid polarizer. EBEX will observe a patch covering ~1% of the sky
with 8' resolution, allowing for observation of the angular power spectrum from
\ell = 20 to 1000. This will allow EBEX to search for both the primordial
B-mode signal predicted by inflation and the anticipated lensing B-mode signal.
Calculations to predict EBEX constraints on r using expected noise levels show
that, for a likelihood centered around zero and with negligible foregrounds,
99% of the area falls below r = 0.035. This value increases by a factor of 1.6
after a process of foreground subtraction. This estimate does not include
systematic uncertainties. An engineering flight was launched in June, 2009,
from Ft. Sumner, NM, and the long duration science flight in Antarctica is
planned for 2011. These proceedings describe the EBEX instrument and the North
American engineering flight.Comment: 12 pages, 9 figures, Conference proceedings for SPIE Millimeter,
Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy V
(2010
First implementation of TES bolometer arrays with SQUID-based multiplexed readout on a balloon-borne platform
EBEX (the E and B EXperiment) is a balloon-borne telescope designed to measure the polarisation of the cosmic microwave background radiation. During a two week long duration science flight over Antarctica, EBEX will operate 768, 384 and 280 spider-web transition edge sensor (TES) bolometers at 150, 250 and 410 GHz, respectively. The 10-hour EBEX engineering flight in June 2009 over New Mexico and Arizona provided the first usage of both a large array of TES bolometers and a Superconducting QUantum Interference Device (SQUID) based multiplexed readout in a space-like environment. This successful demonstration increases the technology readiness level of these bolometers and the associated readout system for future space missions. A total of 82, 49 and 82 TES detectors were operated during the engineering flight at 150, 250 and 410 GHz. The sensors were read out with a new SQUID-based digital frequency domain multiplexed readout system that was designed to meet the low power consumption and robust autonomous operation requirements presented by a balloon experiment. Here we describe the system and the remote, automated tuning of the bolometers and SQUIDs. We compare results from tuning at float to ground, and discuss bolometer performance during fligh
The EBEX Balloon-borne Experiment - Optics, Receiver, and Polarimetry
The E and B Experiment (EBEX) was a long-duration balloon-borne cosmic microwave background (CMB) polarimeter that flew over Antarctica in 2012. We describe the experiment's optical system, receiver, and polarimetric approach and report on their in-flight performance. EBEX had three frequency bands centered on 150, 250, and 410 GHz. To make efficient use of limited mass and space, we designed a 115 cm2 sr high-throughput optical system that had two ambient temperature mirrors and four antireflection-coated polyethylene lenses per focal plane. All frequency bands shared the same optical train. Polarimetry was achieved with a continuously rotating achromatic half-wave plate (AHWP) that was levitated with a superconducting magnetic bearing (SMB). This is the first use of an SMB in astrophysics. Rotation stability was 0.45% over a period of 10 hr, and angular position accuracy was 0.\ub001. The measured modulation efficiency was above 90% for all bands. To our knowledge the 109% fractional bandwidth of the AHWP was the broadest implemented to date. The receiver, composed of one lens and the AHWP at a temperature of 4 K, the polarizing grid and other lenses at 1 K, and the two focal planes at 0.25 K, performed according to specifications, giving focal plane temperature stability with a fluctuation power spectrum that had a 1/f knee at 2 mHz. EBEX was the first balloon-borne instrument to implement technologies characteristic of modern CMB polarimeters, including high-throughput optical systems, and large arrays of transition edge sensor bolometric detectors with multiplexed readouts
The EBEX Balloon-borne Experiment - Gondola, Attitude Control, and Control Software
The E and B Experiment (EBEX) was a long-duration balloon-borne instrument designed to measure the polarization of the cosmic microwave background (CMB) radiation. EBEX was the first balloon-borne instrument to implement a kilopixel array of transition edge sensor (TES) bolometric detectors and the first CMB experiment to use the digital version of the frequency domain multiplexing system for readout of the TES array. The scan strategy relied on 40 s peak-to-peak constant-velocity azimuthal scans. We discuss the unique demands on the design and operation of the payload that resulted from these new technologies and the scan strategy. We describe the solutions implemented, including the development of a power system designed to provide a total of at least 2.3 kW, a cooling system to dissipate 590 W consumed by the detectors' readout system, software to manage and handle the data of the kilopixel array, and specialized attitude reconstruction software. We present flight performance data showing faultless management of the TES array, adequate powering and cooling of the readout electronics, and constraint of attitude reconstruction errors such that the spurious B-modes they induced were less than 10% of the CMB B-mode power spectrum with r = 0.05
The performance of the bolometer array and readout system during the 2012/2013 flight of the e and B experiment (EBEX)
EBEX is a balloon-borne telescope designed to measure the polarization of the
cosmic microwave background radiation. During its eleven day science flight in
the Austral Summer of 2012, it operated 955 spider-web transition edge sensor
(TES) bolometers separated into bands at 150, 250 and 410 GHz. This is the
first time that an array of TES bolometers has been used on a balloon platform
to conduct science observations. Polarization sensitivity was provided by a
wire grid and continuously rotating half-wave plate. The balloon implementation
of the bolometer array and readout electronics presented unique development
requirements. Here we present an outline of the readout system, the remote
tuning of the bolometers and Superconducting QUantum Interference Device
(SQUID) amplifiers, and preliminary current noise of the bolometer array and
readout system.Comment: 15 pages, 12 figures, SPIE conference proceeding
A cryogenic half-wave plate polarimeter using a superconducting magnetic bearing
We present the design and measured performance of the superconducting magnetic bearing (SMB) that was used successfully as the rotation mechanism in the half-wave plate polarimeter of the E and B Experiment (EBEX) during its North American test flight. EBEX is a NASA-supported balloon-borne experiment that is designed to measure the polarization of the cosmic microwave background. In this implementation the half-wave plate is mounted to the rotor of an SMB that is operating at the sink temperature of 4 K. We demonstrate robust, remote operation on a balloon-borne payload, with angular encoding accuracy of 0.01°. We find rotational speed variation to be 0.2% RMS. We measure vibrational modes and find them to be consistent with a simple SMB model. We search for but do not find magnetic field interference in the detectors and readout. We set an upper limit of 3% of the receiver noise level after 5 minutes of integration on such interference. At 2 Hz rotation we measure a power dissipation of 56 mW. If this power dissipation is reduced, such an SMB implementation is a candidate for low-noise space applications because of the absence of stick-slip friction and low wear