19329844
Overview of the Atacama Cosmology Telescope: receiver, instrumentation, and telescope systems
The Atacama Cosmology Telescope was designed to measure small-scale anisotropies in the cosmic microwave background and detect galaxy clusters through the Sunyaev-Zel'dovich effect. The instrument is located on Cerro Toco in the Atacama Desert, at an altitude of 5190 m. A 6 m off-axis Gregorian telescope feeds a new type of cryogenic receiver, the Millimeter Bolometer Array Camera. The receiver features three 1000-element arrays of transition-edge sensor bolometers for observations at 148 GHz, 218 GHz, and 277 GHz. Each detector array is fed by free space millimeter-wave optics. Each frequency band has a field of view of approximately 22' × 26'. The telescope was commissioned in 2007 and has completed its third year of operations. We discuss the major components of the telescope, camera, and related systems, and summarize the instrument performance.
119489530
Breaking the 'redshift deadlock' - I. Constraining the star formation history of galaxies with submillimetre photometric redshifts
Future extragalactic submillimetre and millimetre surveys have the potential to provide a sensitive census of the level of obscured star formation in galaxies at all redshifts. While in general there is good agreement between the source counts from existing Submillimetre Common User Bolometer Array (SCUBA; 850-µm) and Max Planck Millimetre Bolometer Array (MAMBO; 1.25-mm) surveys of different depths and areas, it remains difficult to determine the redshift distribution and bolometric luminosities of the submillimetre and millimetre galaxy population. This is principally due to the ambiguity in identifying an individual submillimetre source with its optical, IR or radio counterpart which, in turn, prevents a confident measurement of the spectroscopic redshift. Additionally, the lack of data measuring the rest-frame FIR spectral peak of the submillimetre galaxies gives rise to poor constraints on their rest-frame FIR luminosities and star formation rates. In this paper we describe Monte Carlo simulations of ground-based, balloon-borne and satellite submillimetre surveys that demonstrate how the restframe FIR‐submillimetre spectral energy distributions (250‐850 µm) can be used to derive photometric redshifts with an rms accuracy of ±0.4 over the range 0 3 × 10 12 L� ) with an accuracy of ∼20 per cent.
118673948
The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) 2005: A 4 deg2 Galactic Plane Survey in Vulpecula (ℓ = 59°)
We present the first results from a new 250, 350, and 500 μm Galactic plane survey taken with the Balloon-borne Large-Aperture Submillimeter Telescope (BLAST) in 2005. This survey's primary goal is to identify and characterize high-mass protostellar objects (HMPOs). The region studied here covers 4 deg^2 near the open cluster NGC 6823 in the constellation Vulpecula (l = 59°). We find 60 compact sources (<60'' diameter) detected simultaneously in all three bands. Their SEDs are constrained through BLAST, IRAS, Spitzer MIPS, and MSX photometry, with inferred dust temperatures spanning ~12-40 K assuming a dust emissivity index β = 1.5. The luminosity-to-mass ratio, a distance-independent quantity, spans ~0.2-130 L_☉ M^(−1)_☉. Distances are estimated from coincident ^(13)CO(1→ 0) velocities combined with a variety of other velocity and morphological data in the literature. In total, 49 sources are associated with a molecular cloud complex encompassing NGC 6823 (distance ~2.3 kpc), 10 objects with the Perseus arm (~8.5 kpc), and one object is probably in the outer Galaxy (~14 kpc). Near NGC 6823, the inferred luminosities and masses of BLAST sources span ~40-10^4 L_☉ and ~15-700 M_☉, respectively. The mass spectrum is compatible with molecular gas masses in other high-mass star-forming regions. Several luminous sources appear to be ultracompact H II regions powered by early B stars. However, many of the objects are cool, massive gravitationally bound clumps with no obvious internal radiation from a protostar, and hence excellent HMPO candidates.
14017836
The Balloon-borne Large-Aperture Submillimeter Telescope for polarization: BLAST-pol
The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) is a sub-orbital experiment designed to study the process of star formation in local galaxies (including the Milky Way) and in galaxies at cosmological distances. Using a 2m Cassegrain telescope, BLAST images the sky onto a focal plane, which consists of 270 bolometric detectors split between three arrays, observing simultaneously in 30% wide bands, centered at 250, 350, and 500 μm. The diffraction-limited optical system provides a resolution of 30" at 250 μm. The pointing system enables raster-like scans with a positional accuracy of ~30", reconstructed to better than 5" rms in postflight analysis. BLAST had two successful flights, from the Arctic in 2005, and from Antarctica in 2006, which provided the first high-resolution and large-area (~0.8−200 deg2) submillimeter surveys at these wavelengths. As a pathfinder for the SPIRE instrument on Herschel, BLAST shares with the ESA satellite similar focal plane technology and scientific motivation. A third flight in 2009 will see the instrument modified to be polarization-sensitive (BLAST-pol). With its unprecedented mapping speed and resolution, BLAST-pol will provide insights into Galactic star-forming nurseries, and give the necessary link between the larger, coarse resolution surveys and the narrow, resolved observations of star-forming structures from space and ground based instruments being commissioned in the next 5 years.
111165820
BLASTbus electronics: general-purpose readout and control for balloon-borne experiments
We present the second generation BLASTbus electronics. The primary purposes of this system are detector readout, attitude control, and cryogenic housekeeping, for balloon-borne telescopes. Readout of neutron transmutation doped germanium (NTD-Ge) bolometers requires low noise and parallel acquisition of hundreds of analog signals. Controlling a telescope's attitude requires the capability to interface to a wide variety of sensors and motors, and to use them together in a fast, closed loop. To achieve these different goals, the BLASTbus system employs a flexible motherboard-daughterboard architecture. The programmable motherboard features a digital signal processor (DSP) and field-programmable gate array (FPGA), as well as slots for three daughterboards. The daughterboards provide the interface to the outside world, with versions for analog to digital conversion, and optoisolated digital input/output. With the versatility afforded by this design, the BLASTbus also finds uses in cryogenic, thermometry, and power systems. For accurate timing control to tie everything together, the system operates in a fully synchronous manner. BLASTbus electronics have been successfully deployed to the South Pole, and own on stratospheric balloons.
119263001
The Balloon-borne Large Aperture Submillimeter Telescope: BLAST
The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) is a suborbital surveying experiment designed to study the evolutionary history and processes of star formation in local galaxies (including the Milky Way) and galaxies at cosmological distances. The BLAST continuum camera, which consists of 270 detectors distributed between three arrays, observes simultaneously in broadband (30%) spectral windows at 250, 350, and 500 μm. The optical design is based on a 2 m diameter telescope, providing a diffraction-limited resolution of 30'' at 250 μm. The gondola pointing system enables raster mapping of arbitrary geometry, with a repeatable positional accuracy of ~30''; postflight pointing reconstruction to 5'' rms is achieved. The onboard telescope control software permits autonomous execution of a preselected set of maps, with the option of manual override. In this paper we describe the primary characteristics and measured in-flight performance of BLAST. BLAST performed a test flight in 2003 and has since made two scientifically productive long-duration balloon flights: a 100 hr flight from ESRANGE (Kiruna), Sweden to Victoria Island, northern Canada in 2005 June; and a 250 hr, circumpolar flight from McMurdo Station, Antarctica, in 2006 December.
119647577
Reply to comment on ‘Using cold atoms to measure neutrino mass’
We discuss questions raised concerning the proposal of kinematically reconstructing the neutrino mass using an ultracold source of tritium atoms (Otten E W 2011 New J. Phys. 13 078001). We provide further details about our two-dimensional fit and emphasize the importance of simultaneously utilizing information from both the neutrino mass squared peak and the β-spectrum. We also explain how the simulation evolved over various drafts of the paper, and we comment on future directions for additional simulation work, including more detailed simulations of spectrometers and electromagnetic field variations.
5706423
BLIND ANALYSIS IN NUCLEAR AND PARTICLE PHYSICS
▪ Abstract During the past decade, blind analysis has become a widely used tool in nuclear and particle physics measurements. A blind analysis avoids the possibility of experimenters biasing their result toward their own preconceptions by preventing them from knowing the answer until the analysis is complete. There is at least circumstantial evidence that such a bias has affected past measurements, and as experiments have become costlier and more difficult and hence harder to reproduce, the possibility of bias has become a more important issue than in the past. We describe here the motivations for performing a blind analysis, and give several modern examples of successful blind analysis strategies.
118025418
The Sudbury Neutrino Observatory at turn-on
39057593
Solving the solar neutrino problem.
Building a detector the size of a 10-story building two kilometers underground is a strange way to study solar phenomena. Yet that has turned out to be the key to unlocking a decades-old puzzle about the physical processes occurring inside the sun. English physicist Arthur Eddington suggested as early as 1920 that nuclear fusion powered the sun, but efforts to confirm critical details of this idea in the 1960s ran into a stumbling block: experiments designed to detect a distinctive by-product of solar nuclear fusion reactions—ghostly particles called neutrinos—observed only a fraction of the expected number of them. It was not until 2002, with the results from the underground
118349856
The Sudbury Neutrino Observatory
This review paper provides a summary of the published results of the Sudbury Neutrino Observatory (SNO) experiment that was carried out by an international scientific collaboration with data collected during the period from 1999 to 2006. By using heavy water as a detection medium, the SNO experiment demonstrated clearly that solar electron neutrinos from 8B decay in the solar core change into other active neutrino flavors in transit to Earth. The reaction on deuterium that has equal sensitivity to all active neutrino flavors also provides a very accurate measure of the initial solar flux for comparison with solar models. This review summarizes the results from three phases of solar neutrino detection as well as other physics results obtained from analyses of the SNO data.