Peter Mason

Modeling and characterization of the SPIDER half-wave plate

Spider is a balloon-borne array of six telescopes that will observe the Cosmic Microwave Background. The 2624 antenna-coupled bolometers in the instrument will make a polarization map of the CMB with approximately one-half degree resolution at 145 GHz. Polarization modulation is achieved via a cryogenic sapphire half-wave plate (HWP) skyward of the primary optic. We have measured millimeter-wave transmission spectra of the sapphire at room and cryogenic temperatures. The spectra are consistent with our physical optics model, and the data gives excellent measurements of the indices of A-cut sapphire. We have also taken preliminary spectra of the integrated HWP, optical system, and detectors in the prototype Spider receiver. We calculate the variation in response of the HWP between observing the CMB and foreground spectra, and estimate that it should not limit the Spider constraints on inflation.

A cryogenic rotation stage with a large clear aperture for the half-wave plates in the Spider instrument

We describe the cryogenic half-wave plate rotation mechanisms built for and used in Spider, a polarization-sensitive balloon-borne telescope array that observed the cosmic microwave background at 95 GHz and 150 GHz during a stratospheric balloon flight from Antarctica in January 2015. The mechanisms operate at liquid helium temperature in flight. A three-point contact design keeps the mechanical bearings relatively small but allows for a large (305 mm) diameter clear aperture. A worm gear driven by a cryogenic stepper motor allows for precise positioning and prevents undesired rotation when the motors are depowered. A custom-built optical encoder system monitors the bearing angle to an absolute accuracy of ±0.1(∘). The system performed well in Spider during its successful 16 day flight.

CMB polarimetry with BICEP: instrument characterization, calibration, and performance

Bicep is a ground-based millimeter-wave bolometric array designed to target the primordial gravity wave signature on the B-mode polarization of the cosmic microwave background (CMB) at degree angular scales. Currently in its third year of operation at the South Pole, Bicep is measuring the CMB polarization with unprecedented sensitivity at 100 and 150 GHz in the cleanest available 2% of the sky, as well as deriving independent constraints on the diffuse polarized foregrounds with select observations on and off the Galactic plane. Instrument calibrations are discussed in the context of rigorous control of systematic errors, and the performance during the first two years of the experiment is reviewed.

Preliminary results of the Spacelab 2 superfluid helium experiment

An experiment to investigate the properties of superfluid helium in a microgravity environment flew on the Shuttle on the Spacelab 2 mission in July and August of 1985. This paper summarizes the flight experiment and describes some preliminary results.

Absolute polarization angle calibration using polarized diffuse Galactic emission observed by BICEP

We present a method of cross-calibrating the polarization angle of a polarimeter using Bicep Galactic observations. Bicep was a ground based experiment using an array of 49 pairs of polarization sensitive bolometers observing from the geographic South Pole at 100 and 150 GHz. The Bicep polarimeter is calibrated to ±0.01 in cross-polarization and less than ±0.7° in absolute polarization orientation. Bicep observed the temperature and polarization of the Galactic plane (R.A = 100° ~ 270° and Dec. = -67° ~ -48°). We show that the statistical error in the 100 GHz Bicep Galaxy map can constrain the polarization angle offset of Wmap W band to 0.6° ± 1.4°. The expected 1σ errors on the polarization angle cross-calibration for Planck or EPIC are 1.3° and 0.3° at 100 and 150 GHz, respectively. We also discuss the expected improvement of the Bicep Galactic field observations with forthcoming Bicep2 and Keck observations.

Studying extragalactic background fluctuations with the Cosmic Infrared Background ExpeRiment 2 (CIBER-2)

Fluctuations in the extragalactic background light trace emission from the history of galaxy formation, including the emission from the earliest sources from the epoch of reionization. A number of recent near-infrared measure- ments show excess spatial power at large angular scales inconsistent with models of z < 5 emission from galaxies. These measurements have been interpreted as arising from either redshifted stellar and quasar emission from the epoch of reionization, or the combined intra-halo light from stars thrown out of galaxies during merging activity at lower redshifts. Though astrophysically distinct, both interpretations arise from faint, low surface brightness source populations that are difficult to detect except by statistical approaches using careful observations with suitable instruments. The key to determining the source of these background anisotropies will be wide-field imaging measurements spanning multiple bands from the optical to the near-infrared. The Cosmic Infrared Background ExpeRiment 2 (CIBER-2) will measure spatial anisotropies in the extra- galactic infrared background caused by cosmological structure using six broad spectral bands. The experiment uses three 2048 x 2048 Hawaii-2RG near-infrared arrays in three cameras coupled to a single 28.5 cm telescope housed in a reusable sounding rocket-borne payload. A small portion of each array will also be combined with a linear-variable filter to make absolute measurements of the spectrum of the extragalactic background with high spatial resolution for deep subtraction of Galactic starlight. The large field of view and multiple spectral bands make CIBER-2 unique in its sensitivity to fluctuations predicted by models of lower limits on the luminosity of the first stars and galaxies and in its ability to distinguish between primordial and foreground anisotropies. In this paper the scientific motivation for CIBER-2 and details of its first flight instrumentation will be discussed, including detailed designs of the mechanical, cryogenic, and electrical systems. Plans for the future will also be presented.

Measuring Light from the Epoch of Reionization with CIBER, the Cosmic Infrared Background Experiment

University of WashingtonUltraviolet emission from the first generation of stars in th e Universe ionized the intergalacticmedium in a process which was completed by z ∼ 6; the wavelength of these photons has beenredshifted by (1+z)into the near infrared today and can be measured using instruments situatedabovethe Earth’s atmosphere. First flying in February2009, the Cosmic InfraredBackgroundEx-periment (CIBER) comprises four instruments housed in a single reusable sounding rocket bornepayload. CIBER will measure spatial anisotropies in the extragalactic IR background caused bycosmological structure from the epoch of reionization using two broadband imaging instruments,make a detailed characterizationof the spectral shape of the IR backgroundusing a low resolutionspectrometer, and measure the absolute brightness of the Zodical light foregroundwith a high res-olution spectrometerin each of our six science fields. This p aperpresents the scientific motivationfor CIBER and details of its first two flights, including a revi ew of the published scientific resultsfrom the first flight and an outlook for future reionization sc ience with CIBER data.Cosmic Radiation Fields: Sources in the early UniverseNovember 9-12, 2010DESY, Germany

The cosmic infrared background experiment-2 (CIBER-2) for studying the near-infrared extragalactic background light

We present the current status of the Cosmic Infrared Background ExpeRiment-2 (CIBER-2) project, whose goal is to make a rocket-borne measurement of the near-infrared Extragalactic Background Light (EBL), under a collaboration with U.S.A., Japan, South Korea, and Taiwan. The EBL is the integrated light of all extragalactic sources of emission back to the early Universe. At near-infrared wavelengths, measurement of the EBL is a promising way to detect the diffuse light from the first collapsed structures at redshift z∼10, which are impossible to detect as individual sources. However, recently, the intra-halo light (IHL) model is advocated as the main contribution to the EBL, and our new result of the EBL fluctuation from CIBER-1 experiment is also supporting this model. In this model, EBL is contributed by accumulated light from stars in the dark halo regions of low- redshift (z<2) galaxies, those were tidally stripped by the interaction of satellite dwarf galaxies. Thus, in order to understand the origin of the EBL, both the spatial fluctuation observations with multiple wavelength bands and the absolute spectroscopic observations for the EBL are highly required. After the successful initial CIBER- 1 experiment, we are now developing a new instrument CIBER-2, which is comprised of a 28.5-cm aluminum telescope and three broad-band, wide-field imaging cameras. The three wide-field (2.3×2.3 degrees) imaging cameras use the 2K×2K HgCdTe HAWAII-2RG arrays, and cover the optical and near-infrared wavelength range of 0.5–0.9 μm, 1.0–1.4 μm and 1.5–2.0 μm, respectively. Combining a large area telescope with the high sensitivity detectors, CIBER-2 will be able to measure the spatial fluctuations in the EBL at much fainter levels than those detected in previous CIBER-1 experiment. Additionally, we will use a linear variable filter installed just above the detectors so that a measurement of the absolute spectrum of the EBL is also possible. In this paper, the scientific motivation and the expected performance for CIBER-2 will be presented. The detailed designs of the telescope and imaging cameras will also be discussed, including the designs of the mechanical, cryogenic, and electrical systems.

Science and Applications of HE-II in Space

He II has played and will continue to play a significant role in space, both as a cryogen and as a subject of experiment in its own right. Major applications include the completed Infrared Astronomical Satellite and the Spacelab 2 Infrared Telescope missions. Planned missions include the NASA Cosmic Background Experiment, the Space IR Telescope and the Large Deployable Reflector as well as the European Space Agencies’ Infrared Space Observatory. Science experiments include the completed Superfluid Helium in Zero Gravity Experiment and the planned Superfluid Helium On- Orbit Transfer and Lambda Point experiments. In all of these missions, the unique properties of He II play an essential role. This paper describes past and future applications and experiments on helium II in the space environment.

Superfluid Helium Experiment for Spacelab 2

Development of the Space Shuttle will make it relatively easy for scientists to conduct experiments in space. Recognizing this fact, the National Aeronautics and Space Administration and the European Space Agency have jointly developed the Spacelab as a facility for use by scientists. The first two Spacelab flights are scheduled for 1983. Of the thirteen experiments selected for Spacelab 2, two will use superfluid helium as a cryogen. This paper describes an experiment (entitled Superfluid Helium Experiment or SFHE) to study the properties of superfluid helium in zero gravity and demonstrate operation of a versatile, reusable superfluid helium experiment facility. The second experiment, the Small Infrared Telescope Experiment, which has been described elsewhere [1], will use superfluid helium as a cryogen to cool the telescope to 2 to 3 K.