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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Tellurium Goes for a Ride on the “Ferrous” Wheel: Interactions of Te(VI) and Te(IV) with Fe(II)-Bearing Minerals

Compared to more abundant metalloids (e.g., As, Se, and Sb), little is known regarding the biogeochemistry of tellurium (Te), a critical metal whose use in CdTe photovoltaic solar cells is driving increasing global demand for this element. In this study, to understand the redox behavior of Te under ferrugenic/sulfidogenic conditions, we examined the potential for reduction of Te(VI) and Te(IV) in aqueous suspensions containing Fe(II) as siderite, vivianite, green rust, magnetite, or mackinawite; Fe(II)-bearing minerals which are often formed during microbial reduction of Fe(III) oxides. In the mackinawite systems, complete reduction of Te(VI) or Te(IV) to Te(0) was observed within 12 h, and near complete reduction (>90% Te(0)) was observed within 2.5 days in the green rust systems. In the presence of siderite, complete reduction of Te(VI) or Te(IV) to Te(0) occurred within 60 days. We observed >60% reduction of Te(VI) to Te(IV) within 2.5 days in the magnetite system, but Te(0) did not form until 120 days; however, complete reduction to Te(0) was observed within 120 days when starting with Te(IV). With vivianite there was >80% reduction of Te(VI) to Te(IV) within 12 h, without further reduction to Te(0) over the duration of the experiment (120 days); in the Te(IV)-vivianite system, there was no evidence of Te(IV) reduction within 120 days. The reduction of Te(VI) and Te(IV) in soils and sediments has been largely attributed to direct reduction by microbes; however, the reduction of Te(VI) and Te(IV) by Fe(II)-bearing minerals suggests that abiotic or coupled biotic-abiotic processes may also play a critical role in Te redox chemistry in natural and engineered environments.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

The Post‐Perovskite Transition in Fe‐ and Al‐Bearing Bridgmanite: Effects on Seismic Observables

Abstract The primary phase of the Earth’s lower mantle, (Al, Fe)‐bearing bridgmanite, transitions to the post‐perovskite (PPv) phase at Earth’s deep mantle conditions. Despite extensive experimental and ab initio investigations, there are still important aspects of this transformation that need clarification. Here, we address this transition in (Al 3+ , Fe 3+ )‐, (Al 3+ )‐, (Fe 2+ )‐, and (Fe 3+ )‐bearing bridgmanite using ab initio calculations and validate our results against experiments on similar compositions. Consistent with experiments, our results show that the onset transition pressure and the width of the two‐phase region depend distinctly on the chemical composition: (a) Fe 3+ ‐, Al 3+ ‐, or (Al 3+ , Fe 3+ )‐alloying increases the transition pressure, while Fe 2+ ‐alloying has the opposite effect; (b) in the absence of coexisting phases, the pressure‐depth range of the Pv‐PPv transition is likely too broad to cause a sharp D” discontinuity (<30 km); (c) the average Clapeyron slope of the two‐phase regions are consistent with previous measurements, calculations in MgSiO 3 , and inferences from seismic data. In addition, (d) we observe a softening of the bulk modulus in the two‐phase region. The consistency between our results and experiments gives us the confidence to proceed and examine this transition in aggregates with different compositions computationally, which will be fundamental for resolving the most likely chemical composition of the D" region by analyses of tomographic images.

Geochemistry & Geophysics↗
DOE OSTI2025

Secondary corundum‐bearing assemblages in Allende Ca,Al‐rich inclusions: Mineralogy, petrology, oxygen, and aluminum–magnesium isotope systematics

Here, we report on the mineralogy, petrology, oxygen, and aluminum–magnesium isotopic systematics of the secondary corundum-bearing assemblages in type B CAIs 3529Z and 3529G and fluffy type A (FTA) CAI ALH-2 from Allende (CV > 3.6). In 3529Z and 3529G, 2–5 μm-sized euhedral-to-subhedral corundum grains associate with secondary alumoåkermanite [(Ca,Na) 2 AlSi 2 O 7 ], grossular, spinel, grossite, celsian, kushiroite, and wadalite. In ALH-2, 2–5 μm-sized euhedral-to-subhedral corundum grains associate with secondary grossular, nepheline, spinel, and kushiroite. In 3529Z and 3529G, corundum and associated secondary grossite, spinel, alumoåkermanite, grossular, and kushiroite have similar 16 O-poor compositions (Δ 17 O = −2.2 ± 1.5‰); primary spinel is 16 O-rich (Δ 17 O ~ −23‰); Al,Ti-diopside shows a range of Δ 17 O (from ~ −24‰ to ~ −15‰); anorthite and melilite are 16 O-depleted to various degrees (−6.5‰ ≤ Δ 17 O ≤ −4.5‰ and Δ 17 O = −2.7 ± 0.8‰, respectively). In ALH-2, corundum shows a range of Δ 17 O, from ~ −9‰ to ~ −1‰; primary hibonite and spinel are 16 O-rich (Δ 17 O ~ −23‰); melilite and perovskite are 16 O-poor (Δ 17 O = −2.6 ± 1.5‰ and −3.1 ± 1.3‰, respectively). On the Al-Mg isotope diagram ( 26 Mg* versus 27 Al/ 24 Mg), primary Al,Ti-diopside, hibonite, melilite, and spinel in the Allende CAIs studied along the canonical isochron with inferred initial 26 Al/ 27 Al ratio [( 26 Al/ 27 Al) 0 ] of ~5 × 10 −5 . All secondary minerals have resolved excesses of 26 Mg*: alumoåkermanite, corundum, and grossite plot below the canonical isochron, whereas most spinel analyses plot above it. An internal isochron defined by the coexisting secondary corundum and alumoåkermanite in 3529Z has ( 26 Al/ 27 Al) 0 = (7.5 ± 2.6) × 10 −7 . We conclude that the corundum-bearing assemblages in Allende CAIs resulted from metasomatic alteration of primary melilite and anorthite, ~4–5 Ma after their crystallization. Metasomatic alteration of CAIs in the Allende parent asteroid by an aqueous fluid having Δ 17 O of ~ −3 ± 2‰ modified the O-isotope composition of their primary melilite, anorthite, and Ti-rich pyroxene; O-isotope compositions of primary hibonite, spinel, and low-Ti pyroxene escaped this modification.

Geosciences↗
DOE OSTI2022

Effects of Water Contamination on Micropitting and Rolling Contact Fatigue of Bearing Steels

Abstract In this research, the effects of water contamination in oil were investigated on two kinds of failures that occur in bearing steel: micropitting and rolling contact fatigue. Whereas the presence of water in the oil had little effect on the generation of surface wear in these experiments, increases in the occurrences of micropitting and rolling contact fatigue were observed due to the presence of either dissolved or free water in lubricants. Additionally, the presence of white etching matter at crack interfaces was observed and evaluated. The experimental results showed that water content can be considered as a significant factor that accelerates the formation of micropitting and fatigue cracks in rolling bearings.

Engineering↗
DOE OSTI2026

Microwave-Assisted Hydrogen Generation from Hydrocarbon-Bearing Reservoir Rocks: Stage-Dependent Thermal Runaway and In-Situ Carbonate Engineering

Microwave-assisted hydrogen generation from hydrocarbon-bearing reservoir rocks is strongly influenced by mineralogy, methane activation, carbonate reactions, and thermal runaway behavior. This study investigates a new approach in which carbonate phases are generated in-situ through the reaction of internally produced CO2 with Ca(OH)2 under microwave heating conditions. The objective is to evaluate how rock mineralogy, methane injection, and Ca(OH)2 addition influence hydrogen generation, carbon redistribution, and stage-dependent reaction pathways during microwave exposure. Microwave heating experiments were conducted using Permian Basin reservoir rocks under three experimental conditions: rock-only experiments under Ar atmosphere, CH4–Ar experiments without additive, and CH4–Ar experiments containing 5 wt% Ca(OH)2. Methane-assisted experiments were performed under continuous injection of 30 standard cubic centimeters per minute (sccm) CH4 and 30 sccm Ar. Based on thermal runaway behavior, each experiment was divided into three operational stages: Before Thermal Runaway (BR), After Thermal Runaway–Decrease in Microwave Power (ARD), and After Thermal Runaway– Increase in Microwave Power (ARI). Temperature and gas composition were continuously monitored throughout the experiments. The rock-only experiments demonstrated that hydrogen generation can occur intrinsically from hydrocarbon-bearing rocks under microwave heating, even without externally injected methane. However, hydrogen production did not correlate solely with kerogen content, indicating that mineralogy strongly influences hydrogen-generation pathways. Correlation analyses suggested that kerogen decomposition initially generated CH4, CO, and CO2, followed by secondary hydrocarbon reactions associated with H2 and C2 hydrocarbon formation. Methane-assisted experiments substantially increased hydrogen production; however, identical methane injection rates produced significantly different hydrogen yields among the rock samples, confirming that mineralogical composition controls methaneconversion behavior under microwave heating conditions. The addition of Ca(OH)2 significantly altered carbon evolution behavior in a stage-dependent manner. During the BR stage, Ca(OH)2 reduced gas-phase CO2 production, particularly in carbonate-rich rocks, indicating favorable conditions for in-situ carbonation and carbonate deposition prior to extensive thermal decomposition. The suppression of CO2 during BR became more pronounced with increasing carbonate content of the rock system. After thermal runaway, carbonate-containing systems exhibited enhanced hydrogen generation behavior, suggesting that carbonatederived mineral transformations and carbonate-mediated reactions contribute to high-temperature hydrogen-generation pathways. In carbonate-poor rocks, Ca(OH)2 addition enabled simultaneous URTeC 4493775 2 enhancement of hydrogen production and partial suppression of CO2 release during the post-runaway stages. Overall, the results demonstrate that microwave-assisted hydrogen generation is governed by dynamically evolving interactions among kerogen decomposition, methane activation, mineral transformations, carbonate formation/decomposition, and thermal runaway behavior. This work introduces in-situ carbonate engineering with Ca(OH)2 as a strategy for coupling hydrogen generation with partial insitu carbon management under microwave heating conditions.

03 NATURAL GAS↗
DOE OSTI2026

AmeriFlux FLUXNET-1F CA-PB1 Polar Bear 1 - Peat Plateau

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site CA-PB1 Polar Bear 1 - Peat Plateau. This is the FLUXNET version of the carbon flux data for the site CA-PB1 Polar Bear 1 - Peat Plateau produced by applying the standard ONEFlux (1F) software. Site Description - Ontario Ministry of Environment and Climate Change's Environmental Monitoring and Reporting Branch has established five carbon flux monitoring towers in Ontario’s Far North as part of its Climate Change Modelling and Monitoring program. These long term monitoring stations measure carbon exchange and a suite of soil and meteorological parameters over peatland ecosystems to better understand carbon cycling in Ontario’s Far North. Information produced by these monitoring stations will assist the province in land use planning and the development of climate change adaptation strategies.

Humphreys, Elyn [Carleton University]↗
DOE OSTI2026

AmeriFlux FLUXNET-1F CA-PB2 Polar Bear 2 - Fen

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site CA-PB2 Polar Bear 2 - Fen. This is the FLUXNET version of the carbon flux data for the site CA-PB2 Polar Bear 2 - Fen produced by applying the standard ONEFlux (1F) software. Site Description - Ontario Ministry of Environment and Climate Change's Environmental Monitoring and Reporting Branch has established five carbon flux monitoring towers in Ontario’s Far North as part of its Climate Change Modelling and Monitoring program. These long term monitoring stations measure carbon exchange and a suite of soil and meteorological parameters over peatland ecosystems to better understand carbon cycling in Ontario’s Far North. Information produced by these monitoring stations will assist the province in land use planning and the development of climate change adaptation strategies.

Humphreys, Elyn [Carleton University]↗
DOE OSTI2022

ORNL Production of Iodine Bearing Wasteforms

As part of the FY22 Material Recovery and Waste Form Development campaign, ORNL has prepared a new set of iodine-bearing sorbents.. Four canisters were machined and loaded with ~30 g each of iodine-bearing silver mordenite at varying degrees of sorbent saturation via hot isostatic pressing (HIP).

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Reduction of Hg(II) by Fe(II)-Bearing Smectite Clay Minerals

Aluminosilicate clay minerals are often a major component of soils and sediments and many of these clays contain structural Fe (e.g., smectites and illites). Structural Fe(III) in smectite clays is redox active and can be reduced to Fe(II) by biotic and abiotic processes. Fe(II)-bearing minerals such as magnetite and green rust can reduce Hg(II) to Hg(0); however, the ability of other environmentally relevant Fe(II) phases, such as structural Fe(II) in smectite clays, to reduce Hg(II) is largely undetermined. We conducted experiments examining the potential for reduction of Hg(II) by smectite clay minerals containing 0–25 wt% Fe. Fe(III) in the clays (SYn-1 synthetic mica-montmorillonite, SWy-2 montmorillonite, NAu-1 and NAu-2 nontronite, and a nontronite from Cheney, Washington (CWN)) was reduced to Fe(II) using the citrate-bicarbonate-dithionite method. Experiments were initiated by adding 500 µM Hg(II) to reduced clay suspensions (4 g clay L−1) buffered at pH 7.2 in 20 mM 3-morpholinopropane-1-sulfonic acid (MOPS). The potential for Hg(II) reduction in the presence of chloride (0–10 mM) and at pH 5–9 was examined in the presence of reduced NAu-1. Analysis of the samples by Hg LIII-edge X-ray absorption fine structure (XAFS) spectroscopy indicated little to no reduction of Hg(II) by SYn-1 (0% Fe), while reduction of Hg(II) to Hg(0) was observed in the presence of reduced SWy-2, NAu-1, NAu-2, and CWN (2.8–24.8% Fe). Hg(II) was reduced to Hg(0) by NAu-1 at all pH and chloride concentrations examined. These results suggest that Fe(II)-bearing smectite clays may contribute to Hg(II) reduction in suboxic/anoxic soils and sediments.

58 GEOSCIENCES↗
DOE OSTI2021

Reduction of Vanadium(V) by Iron(II)-Bearing Minerals

Fe(II)-bearing minerals (magnetite, siderite, green rust, etc.) are common products of microbial Fe(III) reduction, and they provide a reservoir of reducing capacity in many subsurface environments that may contribute to the reduction of redox active elements such as vanadium; which can exist as V(V), V(IV), and V(III) under conditions typical of near-surface aquatic and terrestrial environments. To better understand the redox behavior of V under ferrugenic/sulfidogenic conditions, we examined the interactions of V(V) (1 mM) in aqueous suspensions containing 50 mM Fe(II) as magnetite, siderite, vivianite, green rust, or mackinawite, using X-ray absorption spectroscopy at the V K-edge to determine the valence state of V. Two additional systems of increased complexity were also examined, containing either 60 mM Fe(II) as biogenic green rust (BioGR) or 40 mM Fe(II) as a mixture of biogenic siderite, mackinawite, and magnetite (BioSMM). Within 48 h, total solution-phase V concentrations decreased to <20 µM in all but the vivianite and the biogenic BiSMM systems; however, >99.5% of V was removed from solution in the BioSMM and vivianite systems within 7 and 20 months, respectively. The most rapid reduction was observed in the mackinawite system, where V(V) was reduced to V(III) within 48 h. Complete reduction of V(V) to V(III) occurred within 4 months in the green rust system, 7 months in the siderite system, and 20 months in the BioGR system. Vanadium(V) was only partially reduced in the magnetite, vivianite, and BioSMM systems, where within 7 months the average V valence state stabilized at 3.7, 3.7, and 3.4, respectively. The reduction of V(V) in soils and sediments has been largely attributed to microbial activity, presumably involving direct enzymatic reduction of V(V); however the reduction of V(V) by Fe(II)-bearing minerals suggests that abiotic or coupled biotic–abiotic processes may also play a critical role in V redox chemistry, and thus need to be considered in modeling the global biogeochemical cycling of V.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

KELT-11 b: Abundances of Water and Constraints on Carbon-bearing Molecules from the Hubble Transmission Spectrum

In the past decade, the analysis of exoplanet atmospheric spectra has revealed the presence of water vapor in almost all the planets observed, with the exception of a fraction of overcast planets. Indeed, water vapor presents a large absorption signature in the wavelength coverage of the Hubble Space Telescope’s (HST) Wide Field Camera 3 (WFC3), which is the main space-based observatory for atmospheric studies of exoplanets, making its detection very robust. However, while carbon-bearing species such as methane, carbon monoxide, and carbon dioxide are also predicted from current chemical models, their direct detection and abundance characterization has remained a challenge. Here we analyze the transmission spectrum of the puffy, clear hot-Jupiter KELT-11 b from the HST WFC3 camera. We find that the spectrum is consistent with the presence of water vapor and an additional absorption at longer wavelengths than 1.5 μm, which could well be explained by a mix of carbon bearing molecules. CO{sub 2}, when included is systematically detected. One of the main difficulties to constrain the abundance of those molecules is their weak signatures across the HST WFC3 wavelength coverage, particularly when compared to those of water. Through a comprehensive retrieval analysis, we attempt to explain the main degeneracies present in this data set and explore some of the recurrent challenges that are occurring in retrieval studies (e.g., the impact of model selection, the use of free versus self-consistent chemistry, and the combination of instrument observations). Our results make this planet an exceptional example of a chemical laboratory to test current physical and chemical models of the atmospheres of hot Jupiters.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

Turbomachine with internal bearing and rotor-spline interface cooling and systems incorporating the same

Aspects of the present disclosure include turbomachines designed and configured for high temperature and pressure operation and increased power level output that minimize pressure vessel design requirements, and increase dry gas seal reliability. In some examples, a first radial bearing is located in a high temperature and/or pressure region of the turbomachine between a rotor of the machine and a dry gas seal while other bearings are located outside of the high pressure region.

Fairman, Kevin D.↗
DOE OSTI2022

System and method for monitoring a wind turbine pitch bearing

A system and method for monitoring a pitch system of a wind turbine includes monitoring, via one or more first sensors, at least one electrical condition of the pitch system. The method also includes monitoring, via one or more second sensors, at least one mechanical condition of the pitch system. Further, the method includes receiving, via a controller communicatively coupled to the one or more first and second sensors, sensor signals representing the at least one electrical condition and the at least one mechanical condition of the pitch system. Thus, the method includes determining, via the controller, a bearing condition of a pitch bearing of the pitch system based on the at least one electrical condition and the at least one mechanical condition of the pitch system.

He, Lijun↗
DOE OSTI2021

An improved specimen preparation method for marine shallow gas-bearing sand sediments and its validations

Instabilities of shallow gas-charged seabed are potential geological hazards in ocean engineering. In practice, the conventional field sampling techniques failed to obtain undisturbed gas-bearing sediments from the seabed for laboratory mechanical testing because of sensitive gas exsolution and escape from sediments. However, preparation of representative remoulded gas-charged specimens is a challenging issue, because it is rather difficult to quantitatively control the gas content and obtain uniform distribution of gas bubbles within the specimen. Given the above problems, this work proposes a reliable approach to reconstitute the high-saturation specimen of gas-charged sediments in the laboratory by an improved multifunction integrated triaxial apparatus (MITA). This apparatus is developed based on an advanced stress path triaxial system by introducing a temperature-controlled system and a wave-monitoring system. The temperature-controlled system is used to accurately mimic the in situ environments of sediments in the seabed. The wave-monitoring system is utilized to identify exsolution point of free gas and examine the disturbance of gas to specimens during gas exsolution. The detailed procedure of gassy specimen preparation is introduced. Then, the quality of prepared specimens using our improved apparatus is validated by the high-resolution micro-X-ray computed tomography (μCT) scanning test, from which bubble occurrence and size distribution within the gassy sand specimen can be obtained; and preliminary mechanical tests on gassy sand specimens with various initial saturation degrees are performed. The proposed specimen preparation procedure succeeds in proving the postulated occurrence state of gas bubbles in coarse-grained sediments and accurately controlling the gas content.

58 GEOSCIENCES↗
DOE OSTI2026

Oxidation of biogenic U(IV) mediated by iron-bearing clay minerals, iron-reducing bacteria, and organic ligands

Bioreduction of hexavalent uranium (U(VI)) to tetravalent uranium (U(IV)) by dissimilatory metal-reducing bacteria (DMRB) is considered an effective strategy for uranium immobilization in contaminated environments. However, U(IV) can be reoxidized to U(VI) under fluctuating redox conditions and remobilized. This work investigates the oxidation behavior of biogenic U(IV) in the presence of bioreduced iron-bearing clay minerals (rNAu-2), iron-reducing bacteria (Shewanella putrefaciens CN32), and organic ligands (ethylenediaminetetraacetic acid (EDTA) and citrate). Results demonstrate that the presence of CN32 significantly inhibits U(IV) oxidation. rNAu-2 exerted a context-dependent influence on U(IV) oxidation: its effect was masked by bicarbonate-promoted U(VI) mobilization in the absence of active CN32, but became detectable when CN32-mediated microbial protection slowed U(IV) oxidation. EDTA and citrate markedly accelerate U(IV) oxidation via formation of soluble U(IV)-ligand complexes, changing U(IV) redox potentials, and by promoting clay mineral dissolution that enhances Fe(II)/Fe(III) redox cycling. Collectively, our findings constrain the roles that clay minerals, iron-reducing bacteria, and organic ligands play in governing U(IV) stability, emphasizing the need to account for these factors in developing robust bioremediation strategies.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2025

Foil Bearing Supported Compressor-Expander

R&D Dynamics Corporation (RDD) is developing a fuel cell system compressor-expander designed for heavy-duty vehicle applications. The system emphasizes high reliability, versatility, long service life, and cost-effective mass production. Its design integrates a high-speed centrifugal compressor/expander, oil-free foil air/gas bearings, a direct current permanent magnet (DCPM) motor, and an inverter utilizing silicon carbide (SiC) switches. Key advantages include high efficiency, compact size and reduced weight, enhanced reliability, and elimination of oil contamination risks. The technology targets multiple sectors such as long-haul semi-trucks, mining and construction equipment, power generation, data centers, marine systems, and other heavy machinery. Evaluation units are ready for shipment, and manufacturing capabilities are currently being developed. Contract Number: DE-EE0009617 (2021).

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2026

Rapid and Efficient Deposition of Metal Oxide Coatings for Bearings and Gears in Harsh Environments

The objective of this project is to develop Tribocoating; an innovative, rapid, low-cost, energy-efficient, and environmentally friendly coating technology designed to enhance the performance and durability of bearings and gears operating under harsh conditions. Tribocoating creates protective metal-oxide tribofilms through in-situ tribosintering of nanocrystals (NCs). Components are simply run in a nano-enabled Tribocoating fluid prior to deployment; no surface pretreatment, coating equipment, or external energy input is required.

17 WIND ENERGY↗
DOE OSTI2024

Spectroscopic analysis of Pu-bearing compounds in double-walled cells

Spectroscopic analysis of radiological materials has been historically limited to radiological labs with older or less advanced scientific instrumentation. The development of double-walled cells (DWCs) at the Savannah River National Laboratory (SRNL) has enabled Pu-bearing compounds to be removed from radiological laboratories and studied in our radiologically clean spectroscopy laboratory with state-of-the-art instrumentation. In this manuscript, we discuss the contributions of DWCs that have allowed the application of Raman spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), diffuse reflectance spectroscopy (DRS) in the shortwave infrared, and gamma spectroscopy at SRNL. Significant advances have been made in the understanding of the thermal decomposition of Pu(III) and Pu(IV) oxalates, alpha-induced damage to the PuO 2 crystal lattice, and the effect of calcination temperatures on the quality of PuO 2 . These techniques have enabled methods to conduct PuO 2 age dating since last calcination and estimate the calcination temperature with Raman spectroscopy and DRS. Additional spectroscopic information measured with DRIFTS has enabled the observation of the evolution of carbon species with calcination temperature, while gamma spectroscopy provides information on age dating since last purification.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗