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Hall, G.

Publications and source records attributed to Hall, G..

33 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Design and Performance of the First BICEP Array Receiver

Branches of cosmic inflationary models, such as slow-roll inflation, predict a background of primordial gravitational waves that imprints a unique odd-parity “B-mode” pattern in the Cosmic Microwave Background (CMB) at amplitudes that are within experimental reach. The BICEP/Keck (BK) experiment targets this primordial signature, the amplitude of which is parameterized by the tensor-to-scalar ratio r, by observing the polarized microwave sky through the exceptionally clean and stable atmosphere at the South Pole. B-mode measurements require an instrument with exquisite sensitivity, tight control of systematics, and wide frequency coverage to disentangle the primordial signal from the Galactic foregrounds. BICEP Array represents the most recent stage of the BK program and comprises four BICEP3-class receivers observing at 30/40, 95, 150 and 220/270 GHz. The 30/40 GHz receiver will be deployed at the South Pole during the 2019/2020 austral summer. After 3 full years of observations with 30,000+ detectors, BICEP Array will measure primordial gravitational waves to a precision σ(r) between 0.002 and 0.004, depending on foreground complexity and the degree of lensing removal. Here in this paper, we give an overview of the instrument, highlighting the design features in terms of cryogenics, magnetic shielding, detectors and readout architecture as well as reporting on the integration and tests that are ongoing with the first receiver at 30/40 GHz.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2019

Microwave Multiplexing on the Keck Array

In this paper, we describe an on-sky demonstration of a microwave-multiplexing readout system in one of the receivers of the Keck Array, a polarimetry experiment observing the cosmic microwave background at the South Pole. During the austral summer of 2018–2019, we replaced the time-division multiplexing readout system with microwave-multiplexing components including superconducting microwave resonators coupled to radio frequency superconducting quantum interference devices at the sub-Kelvin focal plane, coaxial-cable plumbing and amplification between room temperature and the cold stages, and a SLAC Microresonator Radio Frequency system for the warm electronics. In the range 5–6 GHz, a single coaxial cable reads out 528 channels. The readout system is coupled to transition-edge sensors, which are in turn coupled to 150-GHz slot-dipole phased-array antennas. Observations began in April 2019, and we report here on an initial characterization of the system performance.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2019

Review of hydrodynamic instability experiments in inertially confined fusion implosions on National Ignition Facility

Hydrodynamic instabilities are a major factor in degradation of inertial confinement fusion (ICF) implosions. In the highest performing implosions on National Ignition Facility, yield amplification (YA) due to alpha particle heating approached ~3, while YA of ~15–30 is needed for ignition. Understanding and mitigation of the instabilities are critical to achieving ignition. This article reviews several experimental platforms that have been developed to directly measure these instabilities in all phases of ICF implosions. Measurements of ripple-shock propagation at OMEGA laser has provided results on initial seeds for the instabilities in three ablators—plastic (CH), beryllium, and high-density carbon. Additionally, at the ablation front, instability growth of pre-imposed modulations was measured in the linear regime using the hydrodynamic growth radiography platform. This platform was extended for modulation growth of 'native roughness' modulations and engineering features (fill tubes and capsule support membranes or 'tents'). Several new experimental platforms have or are being developed to measure instability growth at the ablator–ice interface. In the deceleration phase of implosions, complementary 'self-emission' and 'self-backlighting' platforms were developed to measure low-mode asymmetries and high-mode perturbations near peak compression.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2019

BICEP2/Keck Array XI: Beam Characterization and Temperature-to-Polarization Leakage in the BK15 Data Set

Precision measurements of cosmic microwave background (CMB) polarization require extreme control of instrumental systematics. In a companion paper we have presented cosmological constraints from observations with the BICEP2 and Keck Array experiments up to and including the 2015 observing season (BK15), resulting in the deepest CMB polarization maps to date and a statistical sensitivity to the tensor-to-scalar ratio of σ ( r ) = 0.020. In this work we characterize the beams and constrain potential systematic contamination from main beam shape mismatch at the three BK15 frequencies (95, 150, and 220 GHz). Herein far-field maps of 7360 distinct beam patterns taken from 2010–2015 are used to measure differential beam parameters and predict the contribution of temperature-to-polarization leakage to the BK15 B -mode maps. In the multifrequency, multicomponent likelihood analysis that uses BK15, Planck , and Wilkinson Microwave Anisotropy Probe maps to separate sky components, we find that adding this predicted leakage to simulations induces a bias of Δ r = 0.0027 ± 0.0019. Future results using higher-quality beam maps and improved techniques to detect such leakage in CMB data will substantially reduce this uncertainty, enabling the levels of systematics control needed for BICEP Array and other experiments that plan to definitively probe large-field inflation.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2018

Results from the CBC3 readout ASIC for CMS 2S-modules

The CBC3 is the latest version of the CMS Binary Chip for readout of the outer radial region of the upgraded CMS Tracker at the High Luminosity LHC. This 254-channel, 130 nm CMOS ASIC is designed to be bump-bonded to a substrate to which sensors will be wire-bonded. It will instrument double-layer 2S-modules, containing two overlaid silicon microstrip sensors, aligned with a parallel orientation. On-chip logic identifies Level-1 trigger primitives from high transverse-momentum tracks by selecting correlated clusters in the two sensors. The CBC3 was delivered in late 2016; wafer probing and performance tests have been carried out. Several prototype modules using the CBC3 have been produced and tested in the lab and in different beams. The results show that the CBC3 satisfies CMS requirements and only small corrections are needed for the final version of the chip for production.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

A Measurement of the Cosmic Microwave Background B-mode Polarization Power Spectrum at Subdegree Scales from Two Years of polarbear Data

We report an improved measurement of the cosmic microwave background B-mode polarization power spectrum with the Polarbear experiment at 150 GHz. By adding new data collected during the second season of observations (2013–2014) to re-analyzed data from the first season (2012–2013), we have reduced twofold the band-power uncertainties. The band powers are reported over angular multipoles 500⩽ℓ⩽2100, where the dominant B-mode signal is expected to be due to the gravitational lensing of E-modes. We reject the null hypothesis of no B-mode polarization at a confidence of 3.1σ including both statistical and systematic uncertainties. We test the consistency of the measured B-modes with the Λ Cold Dark Matter (ΛCDM) framework by fitting for a single lensing amplitude parameter A {sub L} relative to the Planck 2015 best-fit model prediction. We obtain A{sub L}=0.60{sub −0.24}{sup +0.26}(stat){sub −0.04}{sup +0.00}(inst) ± 0.14(foreground) ± 0.04(multi), where A{sub L}=1 is the fiducial ΛCDM value.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

POLARBEAR-2: an instrument for CMB polarization measurements

POLARBEAR-2 (PB-2) is a cosmic microwave background (CMB) polarization experiment that will be located in the Atacama highland in Chile at an altitude of 5200 m. Its science goals are to measure the CMB polarization signals originating from both primordial gravitational waves and weak lensing. PB-2 is designed to measure the tensor to scalar ratio, r, with precision σ(r) > 0:01, and the sum of neutrino masses, Σm z , with σ(Σmv) < 90 meV. To achieve these goals, PB-2 will employ 7588 transition-edge sensor bolometers at 95 GHz and 150 GHz, which will be operated at the base temperature of 250 mK. Science observations will begin in 2017.

36 MATERIALS SCIENCE↗
DOE OSTI2016

The Polarbear-2 and the Simons Array experiments

Here, we present an overview of the design and status of the POLARBEAR-2 and the Simons Array experiments. POLARBEAR- 2 is a Cosmic Microwave Background polarimetry experiment which aims to characterize the arc-minute angular scale B-mode signal from weak gravitational lensing and search for the degree angular scale B-mode signal from inflationary gravitational waves. The receiver has a 365 mm diameter focal plane cooled to 270 milli-Kelvin. The focal plane is filled with 7,588 dichroic lenslet-antenna coupled polarization sensitive Transition Edge Sensor (TES) bolometric pixels that are sensitive to 95 GHz and 150 GHz bands simultaneously. The TES bolometers are read-out by SQUIDs with 40 channel frequency domain multiplexing. Refractive optical elements are made with high purity alumina to achieve high optical throughput. The receiver is designed to achieve noise equivalent temperature of 5.8 µK CMB √s in each frequency band. POLARBEAR-2 will deploy in 2016 in the Atacama desert in Chile. The Simons Array is a project to further increase sensitivity by deploying three POLARBEAR-2 type receivers. The Simons Array will cover 95 GHz, 150 GHz and 220 GHz frequency bands for foreground control. The Simons Array will be able to constrain tensor-to-scalar ratio and sum of neutrino masses to σ(r) = 6×10 $-$3 at r = 0.1 and Σm ν (σ = 1) to 40 meV.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS1999

Chemical Gas Sensors for Aeronautics and Space Applications III

Aeronautic and space applications require the development of chemical sensors with capabilities beyond those of commercially available sensors. Areas of interest include launch vehicle safety monitoring, emission monitoring, and fire detection. This paper discusses the needs of aeronautic and space applications and the point-contact sensor technology being developed to address these needs. The development of these sensors is based on progress in two types of technology: 1) Micromachining and microfabrication technology to fabricate miniaturized sensors. 2) The development of high temperature semiconductors, especially silicon carbide. Sensor development for each application involves its own challenges in the fields of materials science and fabrication technology. The number of dual-use commercial applications of this microfabricated gas sensor technology make this area of sensor development a field of significant interest.

Hunter, G. W.↗
NASA NTRS1990

Development and Application of Microfabricated Chemical Gas Sensors For Aerospace Applications

Aerospace applications require the development of chemical sensors with capabilities beyond those of commercially available sensors. In particular, factors such as minimal sensor size, weight, and power consumption are particularly important. Development areas which have potential aerospace applications include launch vehicle leak detection, engine health monitoring and control, and fire detection. Sensor development for these applications is based on progress in three types of technology: 1) Micromachining and microfabrication (Microsystem) technology to fabricate miniaturized sensors. 2) The use of nanocrystalline materials to develop sensors with improved stability combined with higher sensitivity. 3) The development of high temperature semiconductors, especially silicon carbide. Sensor development for each application involves its own challenges in the fields of materials science and fabrication technology. This paper discusses the needs of space applications and the point-contact sensor technology being developed to address these needs. Sensors to measure hydrogen, hydrocarbons, nitrogen oxides (Nox, carbon monoxide, oxygen, and carbon dioxide are being developed. A description is given of each sensor type and its present stage of development. Demonstration and application these sensor technologies will be described. The demonstrations range from use of a microsystem based hydrogen sensor on the Shuttle to engine demonstration of a nanocrystalline based sensor for NO, detection. It is concluded that microfabricated sensor technology has significant potential for use in a range of aerospace applications.

Hunter, G. W.↗
NASA NTRS1980

Cost projections for Redox Energy storage systems

A preliminary design and system cost analysis was performed for the redox energy storage system. A conceptual design and cost estimate was prepared for each of two energy applications: (1) electric utility 100-MWh requirement (10-MW for ten hours) for energy storage for utility load leveling application, and (2) a 500-kWh requirement (10-kW for 50 hours) for use with a variety of residential or commercial applications, including stand alone solar photovoltaic systems. The conceptual designs were based on cell performance levels, system design parameters, and special material costs. These data were combined with estimated thermodynamic and hydraulic analysis to provide preliminary system designs. Results indicate that the redox cell stack to be amenable to mass production techniques with a relatively low material cost.

Michaels, K.↗
NASA NTRS1978

GSFC Systems Test and Operation Language (STOL) functional requirements and language description

The Systems Tests and Operation Language (STOL) provides the means for user communication with payloads, applications programs, and other ground system elements. It is a systems operation language that enables an operator or user to communicate a command to a computer system. The system interprets each high level language directive from the user and performs the indicated action, such as executing a program, printing out a snapshot, or sending a payload command. This document presents the following: (1) required language features and implementation considerations; (2) basic capabilities; (3) telemetry, command, and input/output directives; (4) procedure definition and control; (5) listing, extension, and STOL nucleus capabilities.

Desjardins, R.↗
NASA NTRS1977

Airborne HCl - CO sensing system

A system for measuring air pollutants in-situ using an aircraft was designed, fabricated, and tested. The system is based upon a technique called Gas Filter Correlation (GFC) which provides for high sensitivity and specificity in the presence of interfering species. This particular system was designed for measuring hydrochloric acid and carbon monoxide gases emitted from rocket exhaust effluents.

Bartle, E. R.↗