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At least 73 records · Page 4

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NASA NTRS1994

The Meteoritical Bulletin, no. 76, 1994 January: The U.S. Antarctic Meteoritie Collection

The Meteoritical Bulletin number 76 contains a list of all classified meteorites collected by the United States' Antarctic meteroite program as of the summer of 1993. The compilation includes available information on classification, mass, weathering, olivine and pyroxene composition, Al-26 activities, natural thermoluminescence levels, pairing, collection location and references to published descriptions for 5537 meteorite specimens. A list of the properties of metallic meteorites and a list of the most significant meteorites by class are also included.

Grossman, Jeffrey N.↗

NASA NTRS2002

Structure of the Highly Sheared Tropical Storm Chantal During CAMEX -4

On 20 August 2001 during the Convection and Moisture Experiment 4 (CAMEX-4) and NOAA Hurricane Field Program (HFP2001), the NASA high-altitude ER-2 and medium-altitude DC-8, and lower-altitude NOAA P3 aircraft conducted a coordinated Quantitative Precipitation Estimation (QPE) mission focused on convection in Tropical Storm Chantal. This storm first became a depression on 14 August, a tropical storm on 17 August, and it maintained maximum winds of about 65-70 mph during 19-20 August with minimum pressures ranging from 1008 mb on 19 August to 1001 mb late on 20 August. The storm was westward moving and was forecasted to intensify and landfall near the Yucatan-Belize border late on 20 August. Chanter failed to intensify and instead exhibited a highly sheared structure with an open low-level circulation and intense convection well to the northeast of this circulation center. The NASA ER-2 and DC-8 aircraft were closely coordinated with the NOAA P3 (NOAA-42). The NASA aircraft collected remote sensing and in situ data sets, while the P3 collected lower level in situ and radar data; both the DC-8 and P3 released 7 and 24 dropsondes, respectively. These aircraft measurements provided a unique opportunity to examine the structure of a sheared system and why it did not develop as forecasted a few days earlier. This paper will describe a preliminary study of the precipitation and wind structure provided by the NASA aircraft within the context of the NOAA P3 measurements.

Heymsfield, Gerald M.↗

DOE OSTI2023

Data-driven acoustic measurement of moisture content in flowing biomass

Measuring the moisture content in flowing biomass is critical to processes such as liquid biofuel conversion, such as biogasoline, biodiesel, bio jet kerosene, etc. However, biomass tends to flow in aggregates, which results in significant inhomogeneities in the amount of biomass flowing in front of a sensor at a given time, and there can be significant overlap in the material properties of dry vs wet biomass, leading to poor signal-to-noise ratio. We present a technique for identifying biomass moisture content using a series of acoustic pitch-catch measurements to quantify the sound speed and acoustic amplitude through the biomass, in conjunction with classical machine learning techniques, including Naive Bayes, Random Forest, and K-Nearest Neighbors classification. We amplify the differences between the acoustic measurements in different moisture levels by collecting a series of pulse-echo measurements, which we sort in order of ascending sound speed. We test the accuracy of the technique on experimentally-prepared batches of corn stover biomass with specified moisture levels and measure the average error in the estimated moisture level as a function of the number of pitch-catch measurements used. We observe average estimation errors as low as 6.7% by increasing the number of measurements and optimizing the hyperparameters. This work presents a novel method determining moisture content in flowing biomass with inhomogeneous flow. Additionally, this technique has application in optimizing biomass conversion processes, as well as other fields including, paper production, natural fiber processing, and mineral extraction.

09 BIOMASS FUELS↗

NASA NTRS2014

Unmanned Aircraft System (UAS) Delegation of Separation in NextGen Airspace

The purpose of this study was to determine the feasibility of unmanned aircraft systems (UAS) performing delegated separation in the national airspace system (NAS). Delegated separation is the transfer of responsibility for maintaining separation between aircraft or vehicles from air navigation service providers to the relevant pilot or flight operator. The effects of delegated separation and traffic display information level were collected through performance, workload, and situation awareness measures. The results of this study show benefits related to the use of conflict detection alerts being shown on the UAS operator's cockpit situation display (CSD), and to the use of full delegation. Overall, changing the level of separation responsibility and adding conflict detection alerts on the CSD was not found to have an adverse effect on performance as shown by the low amounts of losses of separation. The use of conflict detection alerts on the CSD and full delegation responsibilities given to the UAS operator were found to create significantly reduced workload, significantly increased situation awareness and significantly easier communications between the UAS operator and air traffic controller without significantly increasing the amount of losses of separation.

NextGen↗

DOE OSTI2022

$\mathrm{α}$ decay of the longest-lived Cm isotope: $^{247}_{96}\mathrm{Cm}$

We report alpha decay of 247 Cm was studied fifty years ago using a 1.6 Bq source containing 99.4 % 247 Cm and levels in 243 Pu were deduced. Using the same source, γ-ray spectra were measured with a more efficient Ge detector. A γ-ray spectrum was also measured in coincidence with α particles for a period of two months and has 80 times more counts than the previously published spectrum. Gamma-ray energies were determined with higher precision and four new γ rays were identified. A new high-energy γ ray of 564.5 keV was observed, which is interpreted as a transition between a level at 564.5 keV and the ground state of 243 Pu. The 564.5-keV level has been tentatively assigned to the 7/2 - [743] Nilsson state.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

NASA NTRS1994

Collection requirements for trace-element analyses of extraterrestrial samples

Trace-element abundances have proven important in understanding the evolution of and interrelationships between different meteorites. Preliminary investigations of the trace-element contents of interplanetary dust particles indicate that trace-element abundances will prove equally important in distinguishing between micrometeorites of different types, comparing the interplanetary dust to the meteorites, and assessing the degree of thermal alteration experienced either on the parent body or during the collection process. Sample collection, delivery, and curation must be accomplished in a manner to avoid contamination with even trace amounts of the elements to be analyzed. The present SXRF sensitivity for micrometeorite analysis is of order 1 femtogram, but anticipated improvements in sensitivity will require sample contamination substantially below this level. Sample collection and handling equipment should be constructed from materials selected for ultrahigh purity, and serious consideration should be given in selecting the particular set of elements from which the collection apparatus is composed so as not to compromise useful information.

Flynn, George J.↗

NASA NTRS2023

Impact of Satellite Orbit Drift on Modis Earth Scene Observations Used in Calibration of the Reflective Solar Bands

After more than 20 years in orbit, NASA’s Terra and Aqua satellites have both started drifting away from their historically maintained orbits. The MODIS instruments on Terra and Aqua continue to collect valuable Earth observation data, but the changing orbits present a challenge for maintaining accurate calibration. The MODIS reflective solar bands (RSB), spanning the wavelength range from 412 nm to 2130 nm, are calibrated on orbit using a combination of regular data collections from an on-board solar diffuser, the Moon, and pseudo-invariant Earth scenes. Starting in the Collection 6 Level 1B (L1B) data products, the RSB calibration began using data from desert targets for a few of the visible bands to better track changes in the response versus scan angle that could not be captured by the on-board calibration. The use of Earth scene data has been extended recently for Terra MODIS calibration in Collection 6.1 (C6.1) and the upcoming Collection 7 (C7) L1B to also include data from ocean scenes and deep convective clouds (DCC). Drifts in both the orbit inclination and ground track of Terra and Aqua lead to changes in the solar illumination angles and satellite view angles of the Earth scenes. We discuss how these orbital changes impact the desert and DCC targets used for MODIS RSB calibration and present the accompanying changes made to our C6.1 and C7 calibration algorithms. We also discuss remaining future challenges, such as better characterization of bi-directional reflectance distribution functions, and possible alternative calibration strategies.

MODIS↗

DOE OSTI2024

Nuclear structure of 157 Sm via 𝛽−decay of 157 Pm

Excited states of the neutron-rich nucleus 157 Sm were populated through the 𝛽−decay of 157 Pm , which has a tentatively assigned ground-state spin and parity of 𝐽 𝜋 =(5/2 − ). Over 30 levels have been observed, 16 of which are new, and over 45 new 𝛾-ray transitions have been placed in the level scheme. An evolution in the ground-state configurations for 𝑁 = 95 nuclei from 5/2 − ⁢[523] (Er/Yb), to 5/2 + ⁢[642] (Dy), to 3/2 − ⁢[521] (Sm/Gd) can be explained based on increasing deformation from 𝑍 = 70 to 𝑍 = 62 and the fact that these three orbitals are energetically close to each other at deformations near 𝛽 2 ≈ 0.25–0.3. Finally, tentative spin and parity assignments are made for most of the states below 1500 keV based on the decay properties of the levels and using excitation-energy systematics of the various orbitals observed in 𝑁 = 95 nuclei.

beta decay↗

NASA NTRS1994

Variation of Great Lakes Water Levels Derived from Geosat Altimetry

A technique for using satellite radar altimetry data to estimate the temporal variation of the water level in moderate to large lakes and enclosed seas is described. Great Lakes data from the first 2 years of the U.S. Navy's Geosat Exact Repeat Mission (November 1986 to November 1988), for which there is an improved orbit, are used to demonstrate the technique. The Geosat results are compared to the lake level data collected by the Great Lakes Section, National Ocean Service, National Oceanic and Atmospheric Administration, and are found to reproduce the temporal variations of the five major lakes with Root-Mean-Square error (RMS) ranging from 9.4 to 13.8 cm and a combined average of 11.1 cm. Geosat data are also analyzed for Lake St. Clair, representing a moderate-sized lake, with a resulting rms of 17.0 cm. During this study period, the water level in the Great Lakes varied in a typical annual cycle of about 0.2 m (0.5 in for Lake Ontario) superimposed on a general decline of approximately 0.5 m. The altimeter data reproduced the general decline reasonably well for all the lakes, but the annual cycle was obscured in some lakes due to systematic errors in the altimeter data. Current and future altimetry missions will have markedly improved accuracy which will permit many moderate (25 km diameter) or larger lakes or enclosed seas to be routinely monitored.

Morris, Charles S.↗

DOE OSTI2021

Calendar Year 2020 Post-Closure Monitoring Report for Corrective Action Unit 99: Rainier Mesa/Shoshone Mountain, Underground Test Area, Nevada National Security Site, Nevada (Rev. 1)

This report presents the results of monitoring conducted for water quality, water levels, and institutional controls in calendar year (CY) 2020 by the U.S. Department of Energy (DOE), Environmental Management (EM) Nevada Program’s Underground Test Area (UGTA) Activity at Corrective Action Unit (CAU) 99, Rainier Mesa/Shoshone Mountain (RM/SM), at the Nevada National Security Site (NNSS), Nevada. This report also presents analytical laboratory results (including results of quality assurance/quality control samples, such as field duplicates [FDs]), and verification of use restrictions (URs), institutional controls, and water usage. Groundwater samples were collected; water levels were measured; and well site surveillance was conducted in support of the Underground Test Area Closure Report (CR) for Corrective Action Unit 99: Rainier Mesa/Shoshone Mountain, Nevada National Security Site, Nevada (DOE/EMNV, 2020). Rainier Mesa (RM) was the site of 61 underground nuclear tests, and Shoshone Mountain (SM) was the site of 6 underground nuclear tests. As a result of these activities, which took place from 1957 to 1992, radionuclides (RNs) were released in the subsurface in the vicinity of the detonations. These 67 underground nuclear tests are associated with 66 specific corrective action site (CAS) numbers, as listed in the Federal Facility Agreement and Consent Order (FFACO) (1996, as amended). Two tests, HURON LANDING and DIAMOND ACE (conducted simultaneously), are included within one CAS. The CR (DOE/EMNV, 2020) establishes the regulatory boundaries and regulatory boundary objectives, monitoring program, UR boundaries and URs, and other institutional controls agreed to by EM Nevada Program and the Nevada Division of Environmental Protection (NDEP) for closure of CAU 99. Regulatory boundaries for the RM/SM CAU were established to protect receptors of groundwater from RN contamination within the three downgradient groundwater basins that receive recharge from RM. The SM regulatory boundary was established to verify that RN contamination does not reach the lower carbonate aquifer below SM. The UR boundaries were established based on contaminant simulation forecasts from the flow and transport simulations with consideration of site-specific topographical controls. The URs associated with the UR boundaries were identified to protect onsite workers and the public from inadvertent exposure to contaminated groundwater as forecasted to occur assuming current conditions. The UR is intended to restrict activities that might expose workers to contaminated groundwater within the UR area. In addition to the URs, other institutional controls are established to monitor and limit access to groundwater. These include federal ownership and management in perpetuity, controlled access of the NNSS and surrounding areas, and reporting water use on the NNSS and surrounding hydrographic basins.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2021

CY2020 Annual Closure Monitoring Report for Corrective Action Unit 98: Frenchman Flat, Underground Test Area, Nevada National Security Site, Nevada (January 2020–December 2020, Revision 1)

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2025

Quenching of the octupole rotational band in 71 Ge

The main goal of this study was to enhance the knowledge of the properties of the known octupole rotational band in 71 Ge, including transition rates, and to investigate whether the band persists to higher spin. An experiment at Florida State University using the 62 Ni ( 14 C, 𝛼⁢𝑛) reaction at 50 MeV was used to produce 71 Ge at high spin. An array of ten Compton-suppressed Ge detectors, consisting of three Clover detectors and seven single-crystal detectors, was used to measure the 𝛾 decays in coincidence. An analysis of the resulting coincidence spectra resulted in the placement of 13 additional transitions in the 71 Ge level scheme, one of which (1092 keV) extends the octupole band to a (35/2 − ) state at 8206 keV. However, calculations of the kinematic moment of inertia show that the 1092-keV transition disrupts the rigid rotational pattern and is likely associated with a band crossing, potentially quenching the octupole deformation. Transition strengths inferred from lifetime measurements in the octupole band are not well reproduced by either shell-model calculations using the JUN45 interaction or a semimicroscopic cluster model, while those for the 𝜈⁢𝑔 9/2 band are in good agreement with the corresponding shell-model predictions. Comparisons between the octupole band in 71 Ge and negative-parity bands based on 3 − octupole states in some neighboring even-even nuclei show both similarities and differences. Systematic trends within the 𝜈⁢𝑔 9/2 bands among odd-𝐴 Ge isotopes point to increased collectivity near 𝑁 = 40.

59 ≤ A ≤ 89↗

DOE OSTI2023

Level scheme study of Mo 91 : Weak-coupling approximation in the N = 50 region

The level scheme of 91 Mo has been studied using the GALILEO γ-ray spectrometer at Laboratori Nazionali di Legnaro, INFN. Five transitions together with four levels are identified for the first time by the γ-γ coincidence measurement, considerably enriching the negative band in 91 Mo. Furthermore, the discrepancy in the previous parity assignments for the states higher than 3807.5 keV has been clarified with the help of new experimental results. A shell-model calculation employing the JUN45 interaction is performed in order to get a further understanding of the level structure of 91 Mo. Being close to N=50 shell closure, the weak-coupling approximation between the valence g 9/2 neutron-hole with the even-even core ( 92 Mo) is discussed in 91Mo.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2022

β decay of Ba 141

The β-decay strength function of nuclides produced in fission is important as it dictates the distribution of decay energy between electrons, neutrinos, and γ rays and so is critical for calculating decay heat in reactors and for estimating the reactor antineutrino spectrum. Several experimental techniques are available to determine this strength function, including electron spectroscopy, γ-ray calorimetry (TAGS spectroscopy), and detailed, high-resolution spectroscopy with modern large high-purity germanium arrays. This work investigates the decay of the well-known and strongly produced fission fragment 141 Ba. A beam of 141 Cs was implanted at the target position of the Gammasphere and the subsequent decay of the daughter 141 Ba was studied. Extensive decay spectroscopy was possible up to the decay Q value of 3.197(7) MeV, including a significant extension of the level scheme and detailed angular correlation measurements for all levels with greater than 0.25% β feeding. The distribution of the β-decay strength was then inferred and compared to previous calorimetric studies. In conclusion, the agreement was excellent and provides a benchmark for comparing strength function methods and data for a more detailed understanding of the structure of 141 La.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2025

Emerging tension between isospin symmetry and nuclear deformation at 𝐴 = 78

Since the nuclear interaction is, to first order, isospin independent, simple relationships can be derived for 𝐸⁢2 strengths across isobaric analog states within an isobaric triplet. At the same time, there is a well-known relationship between the 2 + excitation energy and the 𝐵(𝐸⁢2;2 + → 0 + ) transition strength in deformed even-even nuclei. Here, we highlight a tension between these two trends in the 𝐴 = 78 isobaric triplet. Recent level-energy determinations indicate that the proton-rich member of the triplet, 78 Zr, is strongly deformed while recent lifetime measurements in 78 Sr and 78 Y, as extrapolated into 78 Zr, would imply that 78 Zr is weakly deformed. Furthermore, we explore the implications of this apparent contradiction and explore potential solutions.

59 ≤ A ≤ 89↗

DOE OSTI2021

Ground-state and decay properties of neutron-rich 106 Nb

The ground-state properties of neutron-rich 106 Nb and its β decay into 106 Mo have been studied using the CARIBU radioactive-ion-beam facility at Argonne National Laboratory. Niobium-106 ions were extracted from a 252 Cf fission source and mass separated before being delivered as low-energy beams to the Canadian Penning Trap, as well as the X-Array and SATURN β-decay-spectroscopy station. The measured 106 Nb ground-state mass excess of –66202.0(13) keV is consistent with a recent measurement but has three times better precision; this work also rules out the existence of a second long-lived, β-decaying state in 106 Nb above 5 keV in excitation energy. The decay half-life of 106 Nb was measured to be 1.097(21) s, which is 8% longer than the adopted value. Here, the level scheme of the decay progeny, 106 Mo, has been expanded up to ≈ 4 MeV. The distribution of decay strength and considerable population of excited states in 106 Mo of J ≥ 3 emphasizes the need to revise the adopted J π = 1 – ground-state spin-parity assignment of 106 Nb; it is more likely to be J ≥ 3.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2022

Coulomb excitation of 102 Ru with 12 C and 16 O

Here, the Coulomb excitation of 102 Ru was performed with beams of 12 C and 16 O ions. The beam particles scattered at forward angles were momentum analyzed with a magnetic spectrograph. The resolution achieved enabled the populations of the $2^{+}_{1}$ state, the unresolved $2^{+}_{2}$/ $4^{+}_{1}$, and $2^{+}_{4}$/$3^{-}_{1}$, doublets of states, and the $3^{-}_{2}$ state to be determined as a function of the scattering angle. These populations are compared with gosia calculations, yielding B(E2; $2^{+}_{1}$→$0^{+}_{1}$) = 41.5 ± 2.3 W.u., B(E2; $2^{+}_{2}$→$0^{+}_{1}$) = 1.75 ± 0.11 W.u., B(E3; $3^{-}_{1}$→$0^{+}_{1}$) = 31.5 ± 3.5 W.u., and B(E3; $3^{-}_{2}$→$0^{+}_{1}$) = 6.8 ± 0.5 W.u. The B(E3; $3^{-}_{1}$→$0^{+}_{1}$) value is significantly larger than previously measured. The weakly populated $2^{+}_{3}$ state, presumed to be a member of the band built on the $0^{+}_{2}$ state, was observed clearly for a single angle only, and a fit to its population results in B(E2; $2^{+}_{3}$→$0^{+}_{1}$) = 0.053 ± 0.011 W.u. Using the known γ -ray branching ratios for the $2^{+}_{3}$ level, the B(E2; $2^{+}_{3}$→$0^{+}_{2}$) value is calculated to be 18 ± 4 W.u., substantially less than the B(E2; $2^{+}_{1}$→$0^{+}_{1}$) . This suggests that the deformation of the $0^{+}_{2}$ state is lower than that of the $0^{+}_{1}$ state. The results are compared with beyond-mean-field calculations with the Gogny-D1S interaction using the symmetry-conserving configuration-mixing method.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2024

Transition width of the of the $J$ $π$ = $1$ – two-phonon state of $88$ $Sr$

The ground-state decay width of the two-phonon $J$ $π$ = $1$ – , 4742 keV state of 88 Sr has been determined with the relative self-absorption method combined with a monoenergetic photon beam. This width is important to determine the decay transition strengths into the ground state and the one-phonon $2$$^{+}_{1}$ and $3$$^{–}_{1}$ levels which are required to verify the two-phonon character of the $J$ $π$ = $1$ – state. Here, the experiment was performed at the High Intensity γ-ray Source (HI⁢ γ⁢S) using a novel experimental approach to adapt the relative self-absorption method to monoenergetic photon beams. The result for the ground-state decay width is, thus, independent of any calibration standard and confirms the two-phonon character of the 88 Sr, $J$ $π$ = $1$ – , 4742 keV state within an improved uncertainty.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗