GISMO, a 2 mm Bolometer Camera Optimized for the Study of High Redshift Galaxies

The 2 mm spectral range provides a unique terrestrial window enabling ground based observations of the earliest active dusty galaxies in the universe and thereby allowing a better constraint on the star formation rate in these objects. We have built GISMO (the Goddard-IRAM Superconducting 2-Millimeter Observer), a 2 mm, 128 element superconducting Transition Edge Sensor (TES) based bolometer camera for the IRAM 30 m telescope in Spain. The camera uses an 8×16 planar array of multiplexed TES bolometers, which incorporates our recently designed Backshort Under Grid (BUG) architecture, described elsewhere. The optical design incorporates a 100 mm (4 inches) diameter silicon lens cooled to 4 K, which provides the required fast beam of 0.9 λ/D. With this spatial sampling, GISMO will be very efficient at detecting sources serendipitously in large sky surveys, while the capability for diffraction-limited observations is preserved. With the background limited performance of the detectors, the camera provides significantly greater imaging sensitivity and mapping speed at this wavelength than has previously been possible. The major scientific driver for the instrument is to provide the IRAM 30 m telescope with the capability to rapidly observe galactic and extragalactic dust emission, in particular from high-z Ultra Luminous Infrared Galaxies (ULIRGs) and quasars, even in the summer season. The instrument will fill in the SEDs of high redshift galaxies at the Rayleigh-Jeans part of the dust emission spectrum, even at the highest redshifts. Our source count models predict that GISMO will serendipitously detect one galaxy every four hours on the blank sky, and that one quarter of these galaxies will be at a redshift of z 6.5. We expect to install GISMO at the 30 m telescope in the second half of 2007.      

Performance of TES X-ray Microcalorimeters with a Novel Absorber Design

Superconducting transition-edge sensor (TES) microcalorimeters have demonstrated the Constellation-X requirements for spectral resolution, speed, and pixel size in a close-packed geometry. We will present our recent breakthrough energy resolution with sensors that have all gold and bismuth-gold absorbers. This has been enabled by cantilevered absorbers that make contact to the TES only in regions that are not part of the active thermometer. With this approach, rapid thermalization of the x-ray energy is achieved and interaction between the absorber and TES sensor films is avoided. This design allows us to obtain uniform high performance and is compatible with large-format, high fill-factor arrays. We will discuss this design, the results we have achieved in 8×8 arrays of these pixels, and the dependence of the performance on the geometry of the absorber contact area and on stress within the sensor.      

Design and Fabrication Highlights Enabling a 2 mm, 128 Element Bolometer Array for GISMO

The Backshort-Under-Grid (BUG) superconducting bolometer array architecture is intended to be highly versatile, operating over a large range of wavelengths and background conditions. To validate the basic array design and to demonstrate its applicability for future kilopixel arrays, we will demonstrate a 128-element bolometer array optimized for 2 mm wavelength using a new Goddard Space Flight Center instrument, GISMO (Goddard IRAM Superconducting 2-Millimeter Observer). The design considerations unique to GISMO and laboratory experimental results will be discussed.      

Design of the Cryogen-Free Cryogenic System for the CUORE Experiment

We present here the final design of the cryogenic system where the CUORE detector will be installed in 2010. It is a large cryogen-free cryostat cooled by pulse tubes and by a high-power dilution refrigerator. To avoid radioactive background, about 15000 kg of lead will be cooled to below 1 K and only few construction materials are acceptable. The detector assembly will have a total mass of about 1500 kg and must be cooled to less than 10 mK in a vibration-free environment. We discuss the adopted technical solutions, the results of the preliminary thermal analysis of the system, and its expected performance.      

MUSTANG 2: A Large Focal Plane Array for the 100 m Green Bank Telescope

This paper describes MUSTANG 2, a 338 element focal plane array that is being built for the Green Bank Telescope. Each element consists of a profiled feedhorn coupled to two transition edge sensor bolometers, one for each polarization. Initial deployment will be with 32 detectors, but once fully populated, MUSTANG 2 will be capable of mapping a \(8'\times 8'\) area to \(23~\upmu \) Jy in 1 h with good image fidelity on angular scales from \(9''\) to \(6'\) . As well as an instrument overview, the choice of bandpass and the design of the feeds, detectors and readout are given.     

Design and Realization of the Control and Measurement System of the Wuhan Pulsed High Magnetic Field Facility

A user-friendly Control and Measurement System (CMS) is designed and realized at the Wuhan High Magnetic Field Center (WHMFC). Structure and functions of the CMS system are described in detail. Three kernel parts of CMS are discussed. The success of the comprehensive system test shows that the CMS is effective and reliable.     

Two features of the uniaxial compression of a glassy epoxy resin: the yield stress rate-dependence and the volumetric instability

We report the results of uniaxial compressive tests on a DGEBA epoxy resin at room temperature, well below its glass transition. We first focus on the strength, defined as the stress value corresponding to either a maximum or a flattening of the stress-strain curve, which, for this polymer, may be taken to be coincident with the yield stress, as often assumed for many thermosets. Within the strain rate range (1.E?6 s^?1, 2.E?3 s^?1) we confirm the linear trend relating the logarithm of the strain rate to the yield stress, as already been observed by other investigators even for the same epoxy resin; instead, at strain rates below \(\dot{\varepsilon} _{0} \approx 1.\mathrm{E}{-}6~\mathrm{s}^{-1}\), we found a negligible rate-dependence, as our data indicate a lowest limit of the yield stress, of about 87 MPa. On the basis of these results, we propose how to extend to the viscoplastic regime of deformation a nonlinear viscoelastic model previously put forward.Secondarily, within the viscoelastic range, at a stress level significantly lower than the yield stress, our measurements show a mild volumetric instability, allowed by the free lateral expansion, not ascribable to any macroscopic structural effect; such a behaviour has never been reported in the literature, to the best of our knowledge.     

An Analytical Determination of the Flexure of the 3·5 m Primary and 1 m Test Mirror of the ESO's New Technology Telescope for Passive Support and Active Control

Abstract

The active optics control concept of the ESOs 3·5 m New Technology Telescope (NTT) is based on the correction of aberrations by pre-calibrated changes of the axial forces that provide passive astatic support of the primary. The corrected aberrations are the basic orders of spherical aberration, ordinary astigmatism, triangular and quadratic astigmatism, and furthermore, coma up to the fifth order. This paper is concerned with the analytical determination of the force changes necessary, in either certain groups or the entirety of the supports, to produce any one of these aberration modes. The calibration is derived for two meniscus-shaped mirrors, the NTT primary of aspect ratio 1 : 15 and a thin test mirror of 1 m diameter and aspect ratio 1 : 56, designed to prove the control principle. The theoretical approaches used are adapted to the different stress distributions resulting from the different mirror shapes. Realized as flexural Fourier modes, the generated aberrations are orthogonal to each other and therefore exclude operative interference. The deviations from the desired radial laws amount to very few percent at most. Preparatory to this analysis, the paper treats both the passive axial supports and the radial edge support of the primary. A novel solution for the latter restricts the unavoidable flexural coma to low orders that are readily correctable by active control. Wherever possible, the analytical results are compared with related finite-element results obtained by other authors.     

Dynamic Optimal Design for the Reliability of a Mechanical System

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Performance improvement and analysis of a 1.6 μm continuous-wave modulation laser absorption spectrometer system for CO2 sensing

In a previous study, we developed a 1.6 μm continuous-wave (cw) modulation laser absorption spectrometer system for CO(2) sensing and demonstrated the measurement of small fluctuations in CO(2) corresponding to a precision of 4 parts per million (ppm) with a measurement interval of 32 s. In this paper, we present the process to achieve this highly specific measurement by introducing important points, which have not been shown in the previous study. Following the results of preliminary experiments, we added a function for speckle averaging on the optical antenna unit. We additionally came up with some ideas to avoid the influences of etalon effects and polarization dependence in optical components. Because of the new functions, we realized a calibration precision of 0.006 dB (rms), which corresponds to a CO(2) concentration precision of less than 1 ppm for a 2 km path. We also analyzed the CO(2) sensing performance after the improvements described above. The measured short time fluctuation of the differential absorption optical depth was reasonably close to that calculated using the carrier-to-noise ratio of the received signal.     

Electrical and Thermal Characterization of Membrane-Isolated, Antenna-Coupled, TES Bolometers for the SPIDER Experiment

We have fabricated and measured the thermal and DC electrical properties of transition-edge sensing (TES) bolometers to be employed on the SPIDER experiment, a balloon-based observatory for studying the polarization of the cosmic microwave background (CMB). The bolometers consist of Al and Ti thermistors in series and a termination resistor which couples to an on-chip, polarization sensitive, 150 GHz slot-array antenna through a superconducting microstrip transmission line. Several important parameters were measured. Transition temperature measurements were performed by measuring the Johnson noise in the Ti thermistor. Current-voltage characteristic measurements were performed at various temperatures allowing for the deduction of the thermal conductance and the temperature coefficient of resistance. Electrical noise equivalent power was measured to sub-Hertz frequencies. Finally, the time constant of the bolometers was measured within the Al and Ti transitions where electrothermal feedback speeds up the bolometer response compared with the natural time constant measured just above the Ti transition temperature. The results of these measurements are within the design specifications for SPIDER.      

Fuzzy Reliability Design for the Interference Articulation of a Roller Shaft

1 IntroductionA flour-milling machine is the most important piece of equipment for a mill, and the roller for the flour-milling machine is a key element. At present, most rollers are manufactured by using interference articulation between the roller and the shaft. As feed and distance between the rollers are of a certain randomness and fuzziness, the actual working torque of a roller is random and fuzzy. In addition, the interference quantities, modulus of elasticity and strength limits are al…     

Elementary Excitations, Spectral Weights and Experimental Signatures of a Supersolid and a Fulde-Ferrell-Larkin-Ovchinnikov State

We construct a Ginsburg Landau (GL) theory to study the phases of liquid, solid, superfluid, especially a possible supersolid and phase transitions among these phases in a unified framework. In this GL, we put the two competing orders between the solid component and the superfluid component on the same footing. We only introduce two parameters: v which is the repulsive interaction between the normal component and the local superfluid mode and g which is a periodically changing chemical potential for the local superfluid mode. The microscopic origins of v and g are given. By using this GL action, we study the superfluid to supersolid transition, normal solid to the supersolid transition and analyze the conditions for the existence of the supersolid. The non-classical rotational inertial (NCRI) in the SS state is calculated and found to be isotropic in bcc and fcc lattice, but weakly anisotropic in hcp lattice. We study the elementary low energy excitation inside a supersolid. We find that there are one upper branch and one lower branch longitudinal “supersolidon” modes inside the SS, while the transverse modes in the SS stay the same as those inside the NS. We also determine the corresponding spectral weights of the two branches. We work out the experimental signatures of these elementary excitations in Debye-Waller factor, density-density correlation, vortex loop interaction and specific heat. The estimated excess entropy due to vacancies seems consistent with data measured in the specific experiment in Helium 4. Detecting the two supersolidon modes by various equilibrium and thermodynamic experiments such as X-ray scattering, neutron scattering, acoustic wave attenuation and heat capacity can prove or disapprove the existence of a supersolid in Helium 4. A toy model of supersolid wavefunction is analyzed. The difference and similarities with lattice supersolid are clearly demonstrated. Elementary excitations inside a Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state of superfluid are also discussed.     

Empirical likelihood confidence intervals for the endpoint of a distribution function

Estimating the endpoint of a distribution function is of interest in product analysis and predicting the maximum lifetime of an item. In this paper, we propose an empirical likelihood method to construct a confidence interval for the endpoint. A simulation study shows the proposed confidence interval has better coverage accuracy than the normal approximation method, and bootstrap calibration improves the accuracy.     

The Decay of a Quantized Vortex Ring and the Influence of Tracer Particles

We capture the decay of a quantized vortex ring in superfluid helium-4 by imaging particles trapped on the vortex core. The ring shrinks in time, providing direct evidence for the dissipation of energy in the superfluid. The ring with trapped particles collapses more slowly than predicted by an available theory, but the collapse rate can be predicted correctly if the trapping of the particles on the core is taken into account. We theoretically explore the conditions under which particles may be considered passive tracers of quantized vortices and estimate, in particular, that their dynamics on the large-scale is largely unaffected by the burden of trapped particles if the latter are spaced by more than ten particle diameters along the vortex core, at temperatures between 1.5 K and 2.1 K.     

Design and Application of a Freestanding Sensor Based on 3ω Technique for Thermal-Conductivity Measurement of Solids, Liquids, and Nanopowders

A practical and reusable freestanding sensor based on the 3ω technique is fabricated by encapsulating a nano-thick nickel detector between two pieces of Kapton film. Because of the protection of the Kapton layer, the mechanical strength and applicability of the sensor are greatly improved compared with the traditional 3ω sensor. Furthermore, the nondestructive thermal-conductivity characterization for solids, liquids, and nanopowder specimens based on the 3ω technique is first realized. However, the introduction of the additional protective film also induces an undesirable decrease in accuracy for the thermal-conductivity measurement. This article discusses the underlying reason for this decreased accuracy and accordingly proposes an error correction scheme for accurate determination of the thermal conductivity.     

Development and Characterization of Microcalorimeters for a Next Generation 187Re Beta-Decay Experiment

It has been demonstrated in the past that observing the β-decay spectrum of ¹⁸⁷Re with microbolometers provides a suitable method to determine the mass of the electron anti-neutrino from β-endpoint measurements. In a first step, with the experiment MIBETA a sensitivity of m _νe≤15 eV/c² was achieved. To compete with the sensitivity of m _νe≤2.2 eV/c² established by the Mainz/Troitsk tritium β-decay experiment and the limit of m _νe≤0.2 eV/c² aimed at with KATRIN, a new experiment MARE has been initiated. As a first stage (MARE-1), 300 detectors consisting of silicon implanted thermistors, produced by NASA/GSFC, and absorbers of AgReO₄ crystals will be mounted. To optimize the experimental setup, a test array was equipped with 10 AgReO₄ crystals of various size and shape. The influence of the crystal quality as well as of different types of resin on rise time and energy resolution was investigated.      

Thermal and Structural Analysis of Interaction Cavity and Its Effect on the Operating Mode Excitation for a 120 GHz, 1 MW Gyrotron

Thermal and structural analysis for a 120 GHz, 1 MW gyrotron interaction cavity and the effect of structural deformation on the operational mode excitation is presented. Finite element analysis codes ANSYS and COSMOS have been used for the thermal and structural simulation. The values of the water flow rate and the hydraulic diameter of the outer jacket have been optimized. The effect of the maximum radial expansion of the interaction cavity on eigenfrequency and mode excitation has also been analyzed. The change in eigenfrequency for the operating mode due to thermal expansion is 0.606 GHz. This value is very near the theoretically calculated value and under the tolerance limit of the maximum frequency deviation for the gyrotron operating mode.     

30 Years of Research on Entry Mode and Performance Relationship: A Meta-Analytical Review

Almost 30 years after Anderson and Gatignon systematically conceptualized various entry modes, the scholarly research on their performance effects has accumulated a large amount of empirical evidence. However, research has progressed in a somewhat fragmented manner where the cumulative impact of entry modes is difficult to discern and the entry-performance relationship still remains a conundrum in IB research. This study consolidates and meta-analyzes the empirical findings reported from 44 independent studies. While the results show an overall significant effect of entry modes on performance, more fine-tuned meta-analyses unravel that the effects of entry modes vary with the performance types and a number of plausible contingencies. Findings are discussed in terms of implications for future research and limitations.