The Primordial Inflation Polarization ExploreR (PIPER) is a balloon-borne instrument optimized to measure the polarization of the CMB at large angular scales. It will map 85% of the sky over a series of conventional balloon flights from the Northern and Southern hemispheres, measuring the B-mode polarization power spectrum over a range of multipoles from 2-300 covering both the reionization bump and the recombination peak, with sensitivity to measure the tensor-to-scalar ratio down to r = 0.007. PIPER will observe in four frequency bands centered at 200, 270, 350, and 600 GHz to characterize dust foregrounds. The instrument has background-limited sensitivity provided by fully cryogenic (1.7 K) optics focusing the sky signal onto kilo-pixel arrays of time-domain multiplexed Transition-Edge Sensor (TES) bolometers held at 100 mK. Polarization sensitivity and systematic control are provided by front-end Variable-delay Polarization Modulators (VPMs). PIPER had its engineering ight in October 2017 from Fort Sumner, New Mexico. This papers outlines the major components in the PIPER system discussing the conceptual design as well as specific choices made for PIPER. We also report on the results of the engineering flight, looking at the functionality of the payload systems, particularly VPM, as well as pointing out areas of improvement.
The Primordial Inflation Polarization ExploreR (PIPER) is a balloon-borne telescope designed to measure the polarization of the Cosmic Microwave Background on large angular scales. PIPER will map 85% of the sky at 200, 270, 350, and 600 GHz over a series of 8 conventional balloon flights from the northern and southern hemispheres.
The first science flight will use two 32 × 40 arrays of backshort-under-grid transition edge sensors, multiplexed in
the time domain, and maintained at 100 mK by a Continuous Adiabatic Demagnetization Refrigerator. Front-
end cryogenic Variable-delay Polarization Modulators provide systematic control by rotating linear to circular polarization at 3 Hz. Twin telescopes allow PIPER to measure Stokes I, Q, U , and V simultaneously. The telescope is maintained at 1.5 K in an LHe bucket dewar. Cold optics and the lack of a warm window permit sensitivity at the sky-background limit. The ultimate science target is a limit on the tensor-to-scalar ratio of
r ∼ 0.007, from the reionization bump to l ∼ 300. PIPER’s first flight will be from the Northern hemisphere, and
overlap with the CLASS survey at lower frequencies. We describe the current status of the PIPER instrument.
The Primordial Inflation Explorer is an Explorer-class mission to measure the gravity-wave signature of primordial inflation through its distinctive imprint on the linear polarization of the cosmic microwave background. PIXIE uses an innovative optical design to achieve background-limited sensitivity in 400 spectral channels spanning 2.5 decades in frequency from 30 GHz to 6 THz (1 cm to 50 micron wavelength). Multi-moded non-imaging optics feed a polarizing Fourier Transform Spectrometer to produce a set of interference fringes, proportional to the difference spectrum between orthogonal linear polarizations from the two input beams. Multiple levels of symmetry and signal modulation combine to reduce the instrumental signature and confusion from unpolarized sources to negligible levels. PIXIE will map the full sky in Stokes I, Q, and U parameters with angular resolution 2.6 deg and sensitivity 0.2 µK per 1 deg square pixel. The principal science goal is the detection and characterization of linear polarization from an inflationary epoch in the early universe, with tensor-to-scalar ratio r < 10<sup>-3</sup> at 5 standard deviations. In addition, PIXIE will measure the absolute frequency spectrum to constrain physical processes ranging from inflation to the nature of the first stars to the physical conditions within the interstellar medium of the Galaxy. We describe the PIXIE instrument and mission architecture with an emphasis on the expected level of systematic error suppression.
The Primordial Inflation Polarization Explorer (Piper) is a balloon-borne cosmic microwave background (CMB) polarimeter designed to search for evidence of inflation by measuring the large-angular scale CMB polarization signal. Bicep2 recently reported a detection of B-mode power corresponding to the tensor-to-scalar ratio r = 0:2 on 2 degree scales. If the Bicep2 signal is caused by inflationary gravitational waves (IGWs), then there should be a corresponding increase in B-mode power on angular scales larger than 18 degrees. Piper is currently the only suborbital instrument capable of fully testing and extending the Bicep2 results by measuring the B-mode power spectrum on angular scales ϴ =~0:6° to 90°, covering both the reionization bump and recombination peak, with sensitivity to measure the tensor-to-scalar ratio down to r = 0:007, and four frequency bands to distinguish foregrounds. Piper will accomplish this by mapping 85% of the sky in four frequency bands (200, 270, 350, 600 GHz) over a series of 8 conventional balloon flights from the northern and southern hemispheres. The instrument has background-limited sensitivity provided by fully cryogenic (1.5 K) optics focusing the sky signal onto four 32x40-pixel arrays of time-domain multiplexed Transition-Edge Sensor (TES) bolometers held at 140 mK. Polarization sensitivity and systematic control are provided by front-end Variable- delay Polarization Modulators (VPMs), which rapidly modulate only the polarized sky signal at 3 Hz and allow Piper to instantaneously measure the full Stokes vector (I; Q;U; V ) for each pointing. We describe the Piper instrument and progress towards its first flight.
The Primordial Inflation Polarization Explorer (PIPER) is a balloon-borne instrument to measure the gravitational wave signature of primordial inflation through its distinctive imprint on the polarization of the cosmic microwave background. PIPER combines cold (1.5 K) optics, 5120 bolometric detectors, and rapid polarization modulation using VPM grids to achieve both high sensitivity and excellent control of systematic errors. A series of flights alternating between northern and southern hemisphere launch sites will produce maps in Stokes I, Q, U, and V parameters at frequencies 200, 270, 350, and 600 GHz (wavelengths 1500, 1100, 850, and 500 μm) covering 85% of the sky. The high sky coverage allows measurement of the primordial B-mode signal in the `reionization bump" at multipole moments <i>l</i> < 10 where the primordial signal may best be distinguished from the cosmological lensing foreground. We describe the PIPER instrument and discuss the current status and expected science returns from the mission.
The Primordial Inflation Explorer is an Explorer-class mission to measure the gravity-wave signature of primordial
inflation through its distinctive imprint on the linear polarization of the cosmic microwave background. PIXIE
uses an innovative optical design to achieve background-limited sensitivity in 400 spectral channels spanning 2.5
decades in frequency from 30 GHz to 6 THz (1 cm to 50 μm wavelength). Multi-moded non-imaging optics
feed a polarizing Fourier Transform Spectrometer to produce a set of interference fringes, proportional to the
difference spectrum between orthogonal linear polarizations from the two input beams. The differential design
and multiple signal modulations spanning 11 orders of magnitude in time combine to reduce the instrumental
signature and confusion from unpolarized sources to negligible levels. PIXIE will map the full sky in Stokes I,
Q, and U parameters with angular resolution 2.°6 and sensitivity 0.2 μK per 1° square pixel. The principal
science goal is the detection and characterization of linear polarization from an inflationary epoch in the early
universe, with tensor-to-scalar ratio r < 10<sup>-3</sup> at 5 standard deviations. We describe the PIXIE instrument and
mission architecture needed to detect the signature of an inflationary epoch in the early universe using only 4
The Primordial Inflation Explorer (PIXIE) is an Explorer-class mission to map the absolute intensity and linear
polarization of the cosmic microwave background and diffuse astrophysical foregrounds over the full sky from
frequencies 30 GHz to 6 THz (1 cm to 50 μm wavelength). PIXIE uses a polarizing Michelson interferometer with 2.7 K
optics to measure the difference spectrum between two orthogonal linear polarizations from two co-aligned beams.
Either input can view either the sky or a temperature-controlled absolute reference blackbody calibrator. The multimoded
optics and high etendu provide sensitivity comparable to kilo-pixel focal plane arrays, but with greatly expanded
frequency coverage while using only 4 detectors total. PIXIE builds on the highly successful COBE/FIRAS design by
adding large-area polarization-sensitive detectors whose fully symmetric optics are maintained in thermal equilibrium
with the CMB. The highly symmetric nulled design provides redundant rejection of major sources of systematic
uncertainty. The principal science goal is the detection and characterization of linear polarization from an inflationary
epoch in the early universe, with tensor-to-scalar ratio r << 10<sup>-3</sup>. PIXIE will also return a rich data set constraining
physical processes ranging from Big Bang cosmology, reionization, and large-scale structure to the local interstellar
The Kepler Science Operations Center (SOC) is responsible for the configuration and management of the
SOC Science Processing Pipeline, processing of the science data, distributing data and reports to the Science
Office, exporting processed data for archiving to the Data Management Center at the Space Telescope Science
Institute, and generation and management of the target and aperture definitions. We present an overview of
the SOC procedures and workflows for the data the SOC manages and processes. There are several levels of
reviews, approvals, and processing for the various types of data. We describe the process flow from data
receipt through data processing and export, as well as the procedures in place for accomplishing the tasks. The
tools used to accomplish the goals of <i>Kepler</i> science operations will be presented and discussed as well. These
include command-line tools and graphical user interfaces, as well as commercial products. The tools provide a
wide range of functionality for the SOC including pipeline operation, configuration management, and process
workflow implementation. For a demonstration of the Kepler Science Operations Center's processes,
procedures, and tools, we present the life of a quarter's worth of data, from target and aperture table
generation through archiving the data collected with those tables.
We describe our ongoing project to build a far-infrared polarimeter for the HAWC instrument on SOFIA. Far-IR
polarimetry reveals unique information about magnetic fields in dusty molecular clouds and is an important
tool for understanding star formation and cloud evolution. SOFIA provides flexible access to the infrared as
well as good sensitivity to and angular resolution of continuum emission from molecular clouds. We are making
progress toward outfitting HAWC, a first-generation SOFIA camera, with a four-band polarimeter covering 50 to
220 microns wavelength. We have chosen a conservative design which uses quartz half-wave plates continuously
rotating at ~0.5 Hz, ball bearing suspensions, fixed wire-grid polarizers, and cryogenic motors. Design challenges
are to fit the polarimeter into a volume that did not originally envision one, to minimize the heating of the
cryogenic optics, and to produce negligible interference in the detector system. Here we describe the performance
of the polarimeter measured at cryogenic temperature as well as the basic method we intend for data analysis.
We are on track for delivering this instrument early in the operating lifetime of SOFIA.
The Primordial Inflation Polarization Explorer (PIPER) is a balloon-borne instrument designed to search for
the faint signature of inflation in the polarized component of the cosmic microwave background (CMB). Each
flight will be configured for a single frequency, but in order to aid in the removal of the polarized foreground
signal due to Galactic dust, the filters will be changed between flights. In this way, the CMB polarization at a
total of four different frequencies (200, 270, 350, and 600 GHz) will be measured on large angular scales. PIPER
consists of a pair of cryogenic telescopes, one for measuring each of Stokes Q and U in the instrument frame.
Each telescope receives both linear orthogonal polarizations in two 32 × 40 element planar arrays that utilize
Transition-Edge Sensors (TES). The first element in each telescope is a variable-delay polarization modulator
(VPM) that fully modulates the linear Stokes parameter to which the telescope is sensitive. There are several
advantages to this architecture. First, by modulating at the front of the optics, instrumental polarization is
unmodulated and is therefore cleanly separated from source polarization. Second, by implementing this system
with the appropriate symmetry, systematic effects can be further mitigated. In the PIPER design, many of the
systematics are manifest in the unmeasured linear Stokes parameter for each telescope and thus can be separated
from the desired signal. Finally, the modulation cycle never mixes the Q and U linear Stokes parameters, and
thus residuals in the modulation do not twist the observed polarization vector. This is advantageous because
measuring the angle of linear polarization is critical for separating the inflationary signal from other polarized
The Mid-Infrared Instrument (MIRI) is a 5 to 28 micron imager and spectrometer that is slated to fly aboard the JWST in
2013. Each of the flight arrays is a 1024×1024 pixel Si:As impurity band conductor detector array, developed by Raytheon
Vision Systems. JPL, in conjunction with the MIRI science team, has selected the three flight arrays along with their spares.
We briefly summarize the development of these devices, then describe the measured performance of the flight arrays along
with supplemental data from sister flight-like parts.
Multi-wavelength imaging polarimetry at far-infrared wavelengths has proven to be an excellent tool for studying
the physical properties of dust, molecular clouds, and magnetic fields in the interstellar medium. Although these
wavelengths are only observable from airborne or space-based platforms, no first-generation instrument for the
Stratospheric Observatory for Infrared Astronomy (SOFIA) is presently designed with polarimetric capabilities.
We study several options for upgrading the High-resolution Airborne Wideband Camera (HAWC) to a sensitive
FIR polarimeter. HAWC is a 12 × 32 pixel bolometer camera designed to cover the 53−215 μm spectral range
in 4 colors, all at diffraction-limited resolution (5−21 arcsec). Upgrade options include: (1) an external set of
optics which modulates the polarization state of the incoming radiation before entering the cryostat window;
(2) internal polarizing optics; and (3) a replacement of the current detector array with two state-of-the-art
superconducting bolometer arrays, an upgrade of the HAWC camera as well as polarimeter. We discuss a range
of science studies which will be possible with these upgrades including magnetic fields in star-forming regions
and galaxies and the wavelength-dependence of polarization.
The Wide-field Infrared Survey Explorer (WISE) is a NASA MidEx mission which will survey the entire sky at 3.3, 4.7,
12 and 23 microns. As with most all-sky surveys, WISE results will address many fundamental topics, but the
passbands and sensitivity are particularly well suited to study the distribution and evolutionary history of brown dwarfs
and ultra-luminous IR galaxies. The two long wavelength bands will use 1024x1024 Si:As BIB detectors manufactured
by DRS Sensors & Targeting Systems. NASA ARC has optimized the operating parameters as well as conducted
detailed cryogenic performance and radiation testing of a prototype array. Dark current, noise performance, and radiation
test results will be reported.
The Submillimeter High Angular Resolution Camera II (SHARC-II) is a 32 x 12 pixel submillimeter camera that is used with the ten-meter diameter Caltech Submillimeter Observatory (CSO) on Mauna Kea. SHARC-II can be operated at either 350 or 450 microns. We are developing an optics module that we will install at a position between the SHARC-II camera and the focus of the CSO's secondary mirror. With our module installed, SHARC-II will be converted into a sensitive imaging polarimeter. The basic idea is that the module will split the incident beam coming from the secondary into two orthogonally polarized beams which are then re-imaged onto opposite ends of the “long and skinny” SHARC-II bolometer array. When this removable polarimetry module is in use, SHARC-II becomes a dual-polarization 12 x 12 pixel polarimeter. (The central 12 x 8 pixels of the SHARC-II array will remain unused.) Sky noise is a significant source of error for submillimeter continuum observations. Because our polarimetry module will allow simultaneous observation of two orthogonal polarization components, we will be able to eliminate or greatly reduce this source of error. Our optical design will include a rotating half-wave plate as well as a cold load to terminate the unused polarization components.
We describe the development, construction, and testing of two 384 element arrays of ion-implanted semiconducting cryogenic bolometers designed for use in far-infrared and submillimeter cameras. These two dimensional arrays are assembled from a number of 32 element linear arrays of monolithic Pop-Up bolometer Detectors (PUD) developed at NASA/Goddard Space Flight Center. PUD technology allows the construction of large, high filling factor, arrays that make efficient use of available focal plane area in far-infrared and submillimeter astronomical instruments. Such arrays can be used to provide a significant increase in mapping speed over smaller arrays. A prototype array has been delivered and integrated into a ground-based camera, the Submillimeter High Angular Resolution Camera (SHARC II), a facility instrument at the Caltech Submillimeter Observatory (CSO). A second array has recently been delivered for integration into the High-resolution Airborne Widebandwidth Camera (HAWC), a far-infrared imaging camera for the Stratospheric Observatory for Infrared Astronomy (SOFIA). HAWC is scheduled for commissioning in 2005.
The Stratospheric Observatory For Infrared Astronomy's (SOFIA's) High resolution Airborne Wideband Camera (HAWC) will use an ion-implanted silicon bolometer array developed at NASA's Goddard Space Flight Center (GSFC). The GSFC Pop-Up Detectors (PUDs) use a unique "folding" technique to enable a 12 x 32 element close-packed array of bolometers with a filling factor greater than 95%. The HAWC detector uses a resistive metal film on silicon to provide frequency independent, ~50% absorption over the 40 - 300 micron band. The silicon bolometers are manufactured in 32-element rows within silicon frames using Micro Electro Mechanical Systems (MEMS) silicon etching techniques. The frames are then cut, "folded", and glued onto a metallized, ceramic, thermal bus "bar". Optical alignment using micrometer jigs ensures their uniformity and correct placement. The rows are then stacked side-by-side to create the final 12 x 32 element array. A kinematic Kevlar suspension system isolates the 200 mK bolometer cold stage from the rest of the 4K detector housing. GSFC - developed silicon bridge chips make electrical connection to the bolometers, while maintaining thermal isolation. The Junction Field Effect Transistor (JFET) preamplifiers for all the signal channels operate at 120 K, yet they are electrically connected and located in close proximity to the bolometers. The JFET module design provides sufficient thermal isolation and heat sinking for these, so that their heat is not detected by the bolometers. Preliminary engineering results from the flight detector dark test run are expected to be available in July 2004. This paper describes the array assembly and mechanical and thermal design of the HAWC detector and the JFET module.
HAWC (High-resolution Airborne Wideband Camera) is a facility science instrument for SOFIA (Stratospheric Observatory for Infrared Astronomy). It is a far-infrared camera designed for diffraction-limited imaging in four spectral passbands centered at wavelengths of 53, 89, 155, and 216 μm. Its detector is a 12x32 array of bolometers cooled to 0.2 K by an adiabatic demagnetization refrigerator. In this paper, we report on the development and testing of the instrument and its subsystems.
Testing of a 40 to 125 μm Ge:Sb photoconductor array for AIRES (Airborne Infra-Red Echelle Spectrometer) is described. The prototype array is a 2×24 module which can be close-stacked with other modules to provide larger two-dimensional formats. Collecting cones on a 0.08 inch pitch concentrate incident radiation into integrating cavities containing the detectors. The array is read out by two Raytheon SBRC 190 cryogenic multiplexers that also provide a CTIA (capacitive transimpedance amplifier) unit cell for each detector. We have conducted a series of tests to evaluate the array dark current, responsivity and detective quantum efficiency.
The SBRC 190 cryogenic readouts were developed for use in far-infrared arrays of Ge:Sb and Ge:Ga photoconductor detectors. The SBRC 190 provides an AC-coupled CTIA (capacitive trans-impedance amplifier) unit cell for each detector and multiplexes up to 32 detectors. This paper presents our test results characterizing and optimizing the performance of these novel devices. We discuss their basic behavior and investigate their performance in different clocking schemes.
A far-infrared polarimeter, Hale, will be proposed for the next round of instruments for SOFIA. Key features are: simultaneous detection of two components of polarization; detector arrays providing >4000 pixels on the sky; and four passbands between 53 μm and 215 μm, a range characterized by strong dependence of polarization on wavelength. At 53 μm the diffraction-limited resolution, 1.2 λ/D, will be 5.2 arcsec. In all passbands the systematic errors in polarization will be Δ(P) < 0.2%, Δθ< 2 °.
We have designed and prototyped an array of Ge:Sb photoconductors for use in AIRES, the Airborne InfraRed Echelle Spectrometer, on SOFIA. The 16 X 24 flight array will operate between 33 micrometers and 120 micrometers . In this paper we discuss the testing of a 3 X 3 prototype array and the resulting design of the flight array.
In this paper we present the considerations for design and assembly of a stressed gallium doped germanium photoconductor array for the Airborne InfraRed Echelle Spectrometer on SOFIA. This 8 X 12 element array will cover the wavelength range from 125 to 210 micrometers . The considerations cover the aspects of the mechanical design for stressing the detectors in a uniform way, assembly of the components, contacting them electrically with minimized stray capacitance, and the layout of the light collecting cone assembly.
The South Pole has been identified as an excellent submillimeter site. Submillimeter continuum work at the South Pole promises to address several essential issues in astronomy including the morphology of the magnetic field in the galactic center and the search for protogalaxies. Here we will discuss the Submillimeter Polarimeter for Antarctic Remote Observing (SPARO), the first sub-kelvin cryostat designed for operation in the hostile Antarctic winter environment. We have implemented several novel design concepts, including a vapor cooled <SUP>4</SUP>He cryostat and a capillary fed pumped <SUP>4</SUP>He stage, in order to construct a long holdtime system with simplified operation.
The University of Chicago polarimeter, Hertz, is designed for observations at the Caltech Submillimeter Observatory in the 350 micrometer atmospheric window. Initial observations with this instrument, the first array polarimeter for submillimeter observations, have produced over 700 measurements at 3(sigma) or better. This paper summarizes the characteristics of the instrument, presents examples of its performance including polarization maps of molecular clouds and regions near the Galactic center, and outlines the opportunities for improvements with emphasis on requirements for mapping widely extended sources.