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DOE OSTI2019

Performance of the Gemini Planet Imager Non-redundant Mask and Spectroscopy of Two Close-separation Binaries: HR 2690 and HD 142527

The Gemini Planet Imager (GPI) contains a 10-hole non-redundant mask (NRM), enabling interferometric resolution in complement to its coronagraphic capabilities. The NRM operates both in spectroscopic (integral field spectrograph, henceforth IFS) and polarimetric configurations. NRM observations were taken between 2013 and 2016 to characterize its performance. Most observations were taken in spectroscopic mode, with the goal of obtaining precise astrometry and spectroscopy of faint companions to bright stars. We find a clear correlation between residual wavefront error measured by the adaptive optic system and the contrast sensitivity by comparing phase errors in observations of the same source, taken on different dates. We find a typical 5σ contrast sensitivity of (2–3) × 10 –3 at $~λ/D$. We explore the accuracy of spectral extraction of secondary components of binary systems by recovering the signal from a simulated source injected into several data sets. We outline data reduction procedures unique to GPI's IFS and describe a newly public data pipeline used for the presented analyses. We demonstrate recovery of astrometry and spectroscopy of two known companions to HR 2690 and HD 142527. NRM+polarimetry observations achieve differential visibility precision of σ ~ 0.4% in the best case. We discuss its limitations on Gemini-S/GPI for resolving inner regions of protoplanetary disks and prospects for future upgrades. We summarize lessons learned in observing with NRM in spectroscopic and polarimetric modes.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2018

Observation and interpretation of negative remanent magnetization and inverted hysteresis loops in a thin film of La 0.7 Sr 0.3 MnO 3

The observation of inverted magnetic hysteresis loops and negative magnetic remanence (NRM) in a 7.6 nm thin film of La 0.7 Sr 0.3 MnO 3 grown on SrTiO 3 substrates is reported here. The film was grown employing pulsed laser deposition and characterized by reflection high-energy electron diffraction during growth and using x-ray reflectivity measurements post-growth. Magnetic properties of the film were measured from 5 K to 400 K under both the field-cooled (FC) and zero-field-cooled (ZFC) conditions. The observed results of inverted magnetic hysteresis loops and NRM are interpreted in terms of the co-existence of a magnetically inhomogeneous region consisting of superparamagnetic spin clusters with a blocking temperature $T_B$ = 240 K and the ferromagnetic state with an ordering temperature $T_C$ = 290 K. Hysteresis loop inversion is observed in the temperature region of $T_B < T < T_C$ whereas NRM appears in the mixed superparamagnetic and ferromagnetic states for $T < T_C$ down to 5 K. These observations of hysteresis loop inversion and NRM are related to the magneto-static interaction between the superparamagnetic and ferromagnetic phases leading to anti-alignment of spin of both magnetic phases with respect to each other.

inverted hysteresis loop↗

DOE OSTI2017

CAMTA-Mediated Regulation of Salicylic Acid Immunity Pathway Genes in Arabidopsis Exposed to Low Temperature and Pathogen Infection

Arabidopsis thaliana calmodulin binding transcription activator (CAMTA) factors repress the expression of genes involved in salicylic acid (SA) biosynthesis and SA-mediated immunity in healthy plants grown at warm temperature (22°C). This repression is overcome in plants exposed to low temperature (4°C) for more than a week and in plants infected by biotrophic and hemibiotrophic pathogens. Here, we present evidence that CAMTA3-mediated repression of SA pathway genes in nonstressed plants involves the action of an N-terminal repression module (NRM) that acts independently of calmodulin (CaM) binding to the IQ and CaM binding (CaMB) domains, a finding that is contrary to current thinking that CAMTA3 repression activity requires binding of CaM to the CaMB domain. Induction of SA pathway genes in response to low temperature did not occur in plants expressing only the CAMTA3-NRM region of the protein. Mutational analysis provided evidence that the repression activity of the NRM was suppressed by action of the IQ and CaMB domains responding to signals generated in response to low temperature. Plants expressing the CAMTA3-NRM region were also impaired in defense against the bacterial hemibiotrophic pathogen Pseudomonas syringae pv tomato DC3000. Our results indicate that the regulation of CAMTA3 repression activity by low temperature and pathogen infection involves related mechanisms, but with distinct differences.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2019

Reduced Nonradiative Energy Loss Caused by Aggregation of Nonfullerene Acceptor in Organic Solar Cells

Abstract Reducing energy loss ( E loss ) is of critical importance to improving the photovoltaic performance of organic solar cells (OSCs). Although nonradiative recombination () is investigated in quite a few works, the method for modulating is seldom reported. Here, a new method of depressing E loss is reported for nonfullerene OSCs. In addition to ternary‐blend bulk heterojunction (BHJ) solar cells, it is proved that a small molecular material (NRM‐1) can be selectively dispersed into the acceptor phase in the PBDB‐T:IT‐4F‐based OSC, resulting in lower and , and hence a significant improvement in the open‐circuit voltage ( V OC ); under an optimal feed ratio of NRM‐1, an enhanced power conversion efficiency can also be gained. Moreover, the role of NRM‐1 in the method is illustrated and its applicability for several other representative OSCs is validated. This work paves a new pathway to reduce the E loss for nonfullerene OSCs.

Qin, Yunpeng↗

DOE OSTI2018

Nuclear Rocket Motors: Development Status and Application Prospects

The possibility and expediency of using nuclear rocket motors at the present stage of development of rocketspace technology as part of conventional and advanced space means, including the upper stages of carrier rockets and acceleration blocks, reusable interorbital tugs, and a motor assembly of the piloted Martian expedition complex are discussed. It is shown that because of high cost it is not expedient to use NRM in single-use booster blocks and multi-use tugs for transport operations in near-Earth space, since the specific cost of delivering a useful load into high working orbits increases by a factor of 1.5 or more as compared with transport means based on oxygen-hydrogen rocket motors. At the same time, their use for the Martian expedition complex makes it possible to improve considerably the design characteristics of the complex (starting mass and expedition duration) as compared with non-nuclear motor systems.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

DOE OSTI2020

Effects of Oxygen Modification on the Structural and Magnetic Properties of Highly Epitaxial La0.7Sr0.3MnO3 (LSMO) thin films

Abstract La 0.7 Sr 0.3 MnO 3 , a strong semi-metallic ferromagnet having robust spin polarization and magnetic transition temperature ( T C ) well above 300 K, has attracted significant attention as a possible candidate for a wide range of memory, spintronic, and multifunctional devices. Since varying the oxygen partial pressure during growth is likely to change the structural and other physical functionalities of La 0.7 Sr 0.3 MnO 3 (LSMO) films, here we report detailed investigations on structure, along with magnetic behavior of LSMO films with same thickness (~30 nm) but synthesized at various oxygen partial pressures: 10, 30, 50, 100, 150, 200 and 250 mTorr. The observation of only ( 00 l ) reflections without any secondary peaks in the XRD patterns confirms the high-quality synthesis of the above-mentioned films. Surface morphology of the films reveals that these films are very smooth with low roughness, the thin films synthesized at 150 mTorr having the lowest average roughness. The increasing of magnetic T C and sharpness of the magnetic phase transitions with increasing oxygen growth pressure suggests that by decreasing the oxygen growth pressure leads to oxygen deficiencies in grown films which induce oxygen inhomogeneity. Thin films grown at 150 mTorr exhibits the highest magnetization with T C = 340 K as these thin films possess the lowest roughness and might exhibit lowest oxygen vacancies and defects. Interpretation and significance of these results in the 30 nm LSMO thin films prepared at different oxygen growth pressures are also presented, along with the existence and growth pressure dependence of negative remanent magnetization (NRM) of the above-mentioned thin films.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2018

Insights into the magnetic dead layer in La 0.7 Sr 0.3 MnO 3 thin films from temperature, magnetic field and thickness dependence of their magnetization

Experimental investigations of the magnetic dead layer in 7.6 nm thick film of La 0.7 Sr 0.3 MnO 3 (LSMO) are reported. The dc magnetization ( M ) measurements for a sample cooled to T = 5 K in applied field H = 0 reveal the presence of negative remanent magnetization (NRM) in the M vs. H (magnetic field) measurements as well as in the M vs. T measurements in H = 50 Oe and 100 Oe. The M vs. T data in ZFC (zero-field-cooled) and FC (field-cooled) protocols are used to determine the blocking temperature T B in different H . Isothermal hysteresis loops at different T are used to determine the temperature dependence of saturation magnetization ( M S ), remanence (MR) and coercivity HC. The M S vs. T data are fit to the Bloch law, M S ( T ) = M 0 ( 1 – BT 3/2 ), showing a good fit for T < 100 K and yielding the nearest-neighbor exchange constant J/k B ≅ 18 K. The variations of T B vs. H and H C vs. T are well described by the model often used for randomly oriented magnetic nanoparticles with magnetic domain diameter ≈ 9 nm present in the dead-layer of thickness d =1.4 nm. Finally, the data available from literature on the thickness ( D ) variation of Curie temperature ( T C ) and M S of LSMO films grown under 200, 150, and 0.38 mTorr pressures of O 2 are analyzed in terms of the finite-size scaling, with M S vs. D data fit to M S ( D ) = M S (b)(1-d / D ) yielding the dead layer thickness d = 1.1 nm, 1.4 nm and 2.4 nm respectively. Brief discussion on the significance of these results is presented.

36 MATERIALS SCIENCE↗

DOE OSTI2022

The CMS Magnetic Field Measuring and Monitoring Systems

This review article describes the performance of the magnetic field measuring and monitoring systems for the Compact Muon Solenoid (CMS) detector. To cross-check the magnetic flux distribution obtained with the CMS magnet model, four systems for measuring the magnetic flux density in the detector volume were used. The magnetic induction inside the 6 m diameter superconducting solenoid was measured and is currently monitored by four nuclear magnetic resonance (NMR) probes installed using special tubes outside the barrel hadron calorimeter. Two more NRM probes were installed at the faces of the tracking system. The field inside the superconducting solenoid was precisely measured in 2006 in a cylindrical volume of 3.448 m in diameter and 7 m in length using 10 three-dimensional (3D) B-sensors based on the Hall effect. These B-sensors were installed on each of the two propeller arms of an automated field-mapping machine. In addition to these measurement systems, a system for monitoring the magnetic field during the CMS detector operation has been developed. Inside the solenoid in the horizontal plane, 4 3D B-sensors were installed at the faces of the tracking detector. Twelve 3D B-sensors were installed on the surfaces of the flux-return yoke nose disks. Seventy 3D B-sensors were installed in the air gaps of the CMS magnet yoke. A specially developed flux loop technique was used for the most complex measurements of the magnetic flux density inside the steel blocks of the CMS magnet yoke. The flux loops are installed in 22 sections of the flux-return yoke blocks. The areas enclosed by these coils varied from 0.3 to 1.59 m$^{2}$ in the blocks of the barrel wheels and from 0.5 to 1.12 m$^{2}$ in the blocks of the yoke endcap disks. The development of these systems and the results of the magnetic flux density measurements across the CMS magnet are presented and discussed in this review article.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2016

Snake River Plain FORGE: Site Characterization Data

The site characterization data used to develop the conceptual geologic model for the Snake River Plain site in Idaho, as part of phase 1 of the Frontier Observatory for Research in Geothermal Energy (FORGE) initiative. This collection includes data on seismic events, groundwater, geomechanical models, gravity surveys, magnetics, resistivity, magnetotellurics (MT), rock physics, stress, the geologic setting, and supporting documentation, including several papers. Also included are 3D models (Petrel and Jewelsuite) of the proposed site. Data for wells INEL-1, WO-2, and USGS-142 have been included as links to separate data collections. These data have been assembled by the Snake River Geothermal Consortium (SRGC), a team of collaborators that includes members from national laboratories, universities, industry, and federal agencies, lead by the Idaho National Laboratory (INL). Other contributors include the National Renewable Energy Laboratory (NREL), Lawrence Livermore National Laboratory (LLNL), the Center for Advanced Energy Studies (CEAS), the University of Idaho, Idaho State University, Boise State University, University of Wyoming, University of Oklahoma, Energy and Geoscience Institute-University of Utah, US Geothermal, Baker Hughes Campbell Scientific Inc., Chena Power, US Geological Survey (USGS), Idaho Department of Water Resources, Idaho Geological Survey, and Mink GeoHydro.

15 GEOTHERMAL ENERGY↗