Article
Astronomy & Astrophysics
Xilu Wang, Adam M. Clark, John Ellis, Adrienne F. Ertel, Brian D. Fields, Brian J. Fry, Zhenghai Liu, Jesse A. Miller, Rebecca Surman
Summary: Pu-244 has been found in deep-sea deposits from the past 10 million years, including two Fe-60 pulses from nearby supernovae. The origin of Pu-244, one of the heaviest r-process products, is debated. It could have been created in supernovae, although nucleosynthesis simulations suggest otherwise, or in an earlier kilonova event that spread Pu-244 in the nearby interstellar medium, later swept up by supernova debris. To investigate these possibilities, measurements of Pu-244, I-129, and Hf-182 in lunar regolith samples and deep-sea deposits are suggested.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Y. W. Hao, Y. F. Niu, Z. M. Niu
Summary: The sensitivity of rare-earth peak abundances to nuclear masses has been studied in different astrophysical scenarios. The most impactful nuclei are found along the r-process paths at r-process freeze-out and when the neutron-capture timescale is approximately 3 times the β-decay timescale (τn/γ ≈ 3τβ), corresponding to the beginning and completion of rare-earth peak formation, respectively. In astrophysical scenarios with fission involved, the sensitivities of nuclei along the r-process path at freeze-out are masked by the significant contribution of fission products to the rare-earth peak abundances. This study provides recommended targets for future research and enhances understanding of the formation mechanism and diagnostic efficacy of the rare-earth peak as an r-process site.
Article
Multidisciplinary Sciences
A. Wallner, M. B. Froehlich, M. A. C. Hotchkis, N. Kinoshita, M. Paul, M. Martschini, S. Pavetich, S. G. Tims, N. Kivel, D. Schumann, M. Honda, H. Matsuzaki, T. Yamagata
Summary: By studying samples of Fe-60 and Pu-244 in Pacific Ocean crust, researchers have detected two influxes of 60Fe to Earth in the last 10 million years, accompanied by lower quantities of Pu-244. The similar Pu-244/Fe-60 influx ratios of both events suggest that supernovae explosions may not be the primary source of r-process nucleosynthesis.
Article
Astronomy & Astrophysics
Xilu Wang, Adam M. Clark, John Ellis, Adrienne F. Ertel, Brian D. Fields, Brian J. Fry, Zhenghai Liu, Jesse A. Miller, Rebecca Surman
Summary: The astrophysical sites where r-process elements are synthesized are still uncertain, but neutron star mergers and certain core-collapse supernovae are possible sources. Recent discoveries of Fe-60 and Pu-244 on Earth and the Moon suggest that astronomical explosions, possibly supernovae, have occurred near Earth within the last few million years. This has led to discussions on the origins of r-process elements and the potential history of the solar neighborhood, with the focus on distinguishing between supernova and kilonova scenarios for the synthesis of these elements.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
O. Just, V. Vijayan, Z. Xiong, S. Goriely, T. Soultanis, A. Bauswein, J. Guilet, H. -Th. Janka, G. Martinez-Pinedo
Summary: We investigate the nucleosynthesis and kilonova properties of binary neutron star merger models that lead to intermediate remnant lifetimes until black hole formation. Our study provides a consistent end-to-end modeling of the system and its observables, using a combination of hydrodynamics, nucleosynthesis, and radiative transfer tools. Our findings show that asymmetric progenitors lead to shorter remnant lifetimes and enhanced ejecta masses, while the integrated production of lanthanides and heavier elements in such binary systems is subsolar, suggesting a subdominant contribution to r-process enrichment. The complexity of the models is taken into account in estimating kilonova light curves, which show promising agreement with observations at later times but exhibit inconsistencies at early times.
ASTROPHYSICAL JOURNAL LETTERS
(2023)
Article
Multidisciplinary Sciences
J. Ochoa, E. Monteblanco, L. Cerpa, A. Gutarra-Espinoza, L. Aviles-Felix
Summary: A rare-earth-rich site containing significant quantities of light and heavy rare-earth elements has been discovered in Capacsaya, Peru. The associated mineral with the rare-earth elements was identified as K-feldspar. Through electrostatic separation, efficient separation of the K-feldspar phase was achieved within a certain particle size range.
SN APPLIED SCIENCES
(2022)
Article
Chemistry, Analytical
Benjamin D. Roach, Kayron T. Rogers, N. Alex Zirakparvar, Jeffrey S. Delashmitt, Shalina C. Metzger, Benjamin T. Manard, Tamara J. Keever, Joseph M. Giaquinto, Cole Hexel
Summary: This study presents the application of a novel analytical approach for fast evaluation of burn-up in spent nuclear fuel. The method uses an automated online separation-direct analysis technique to simultaneously measure the isotopic compositions and concentrations of Nd, Pu, and U, enabling the determination of burn-up in as little as 4.5 hours per sample with expanded uncertainties as low as 1.2% using only 1 μg of fuel. The burn-up values obtained by this method have the lowest reported uncertainties to date when compared with an ultra-high precision methodology.
Article
Geography, Physical
Sarah Kamleitner, Susan Ivy-Ochs, Lucia Manatschal, Naki Akcar, Marcus Christl, Christof Vockenhuber, Irka Hajdas, Hans-Arno Synal
Summary: This study evaluates glacial landforms preserved within the former LGM Rhine glacier and the eastern lobes of the LGM Reuss glacier system to understand LGM glacier dynamics. Through geomorphological mapping and new dating techniques, it is determined that the Rhine and Reuss glaciers reached their LGM maximum positions around 26-22 ka and 25/24 +/- 2 ka respectively. The glaciers showed subsequent oscillations, with late LGM readvances occurring after 20.6 +/- 1.7 ka and 20.8 +/- 1.3 ka for the Rhine and Reuss glaciers. The results provide valuable insights into the glacial history of the Alpine forelands.
Article
Instruments & Instrumentation
Marcus Christl, Philip Gautschi, Sascha Maxeiner, Arnold Milenko Mueller, Christof Vockenhuber, Hans-Arno Synal
Summary: Compact, low-energy accelerator mass spectrometry (AMS) has become one of the most sensitive, selective, and robust techniques for analyzing heavy and long-lived radionuclides. This study focuses on the analytical capabilities of the compact AMS system MILEA, specifically for 236U analyses. The setup for actinide analyses and the technical setup for 23xU/238U (x = 3, 6, 5) are discussed, followed by a detailed investigation of the background and sensitivity for 236U/238U. The results demonstrate that the ETH Zurich MILEA system is well-suited for fast, reliable, high-sensitivity, and nearly background-free analyses of 236U/238U in environmental samples.
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS
(2023)
Article
Geography, Physical
Hans Fernandez-Navarro, Juan-Luis Garcia, Samuel U. Nussbaumer, Dmitry Tikhomirov, Francia Perez, Isabelle Gartner-Roer, Marcus Christl, Markus Egli
Summary: This study reconstructed glacier fluctuations during the latest Holocene using Terrestrial Cosmogenic Nuclides (10Be) dating of boulders on moraines in central Chile. The findings reveal at least two maximum glacier advances by the Universidad Glacier in the 13th-16th centuries and the early to mid-19th century. These fluctuations were attributed to the equatorward shift of the Southern Westerly Winds (SWW), influenced by the long-term negative phase of the Southern Annular Mode (SAM) and associated humid and cold conditions in central Chile. The glacier chronology aligns with other regions, showing the culmination of the latest Holocene glacial maximum in the mid-19th century followed by accelerated ice loss in a warming world since the mid-20th century.
QUATERNARY SCIENCE REVIEWS
(2023)
Article
Chemistry, Analytical
Shan Xing, Chenyang Peng, Marcus Christl, Keliang Shi, Hans-Arno Synal, Xiaolin Hou
Summary: A new method was developed for simultaneous determination of transuranium nuclides using 300 kV AMS after sequential chemical separation. The method showed consistent chemical behaviors of Np and Pu on the TK200 column and Am and Cm on the DGA column during the separation process. The detection limits for all radionuclides were below femtogram level.
ANALYTICAL CHEMISTRY
(2023)
Article
Soil Science
Joanna Beata Kowalska, Markus Egli, Martina Vogtli, Dmitry Tikhomirov, Beata Labaz, Marcus Christl, Jaroslaw Waroszewski
Summary: Loess deposits are important archives for studying deposition and erosion events. Long-term erosion rates are crucial for understanding loess stability and soil evolution. This study used meteoric Be-10 to analyze its distribution, determine erosion rates, and assess soil thickness and stability over time.
Article
Geography, Physical
Pavel Samonil, Jakub Jaros, Pavel Danek, Dmitry Tikhomirov, Vojtech Novotny, George Weiblen, Marcus Christl, Markus Egli
Summary: Trees play an important role in hillslope dynamics by mechanically disturbing the soil. This study focuses on determining soil erosion rates and the role of trees in hillslope processes in a tropical forest in Papua New Guinea.
Article
Geosciences, Multidisciplinary
Marjolaine Verret, Cassandra Trinh-Le, Warren Dickinson, Kevin Norton, Denis Lacelle, Marcus Christl, Richard Levy, Tim Naish
Summary: Continental-scale ice sheets have covered Antarctica since around 33.9 million years ago. The sequence of events that led to the persistent ice sheet in East Antarctica remains disputed. By assessing meteoric beryllium-10 profiles, researchers have found that the polar aridity in high elevations of East Antarctica began in the late Miocene. This finding suggests that the McMurdo Dry Valleys may be more susceptible to climate change than previously believed.
Article
Geography, Physical
Anders Romundset, Naki Akcar, Ola Fredin, Jane L. Andersen, Fredrik Hogaas, Marcus Christl, Serdar Yesilyurt, Christian Schluchter
Summary: This study describes the thinning and final decay of the Scandinavian Ice Sheet in the Gudbrandsdalen area in central southern Norway. The research was based on surface exposure dating, radiocarbon dating, and mapping of ice-dammed lakes. The results indicate that the ice sheet remained above 1800 m a.s.l. during the Younger Dryas and experienced rapid thinning during the Early Holocene. The final stage of deglaciation involved the formation of large ice-dammed lakes.
QUATERNARY SCIENCE REVIEWS
(2023)
Article
Geochemistry & Geophysics
Urs Ramsperger, Daniele De Maria, Philip Gautschi, Sascha Maxeiner, Arnold Milenko Muller, Hans-Arno Synal, Lukas Wacker
Summary: A newly developed compact AMS system, LEA, is tested and compared with the state-of-the-art AMS system MICADAS, which has a precision performance of better than 1% for modern C-14. The main difference between these two systems is the acceleration voltage, which has been reduced from 200 kV in MICADAS to 50 kV in LEA. By measuring exactly the same samples on both systems, it is found that the LEA system is fully operational and its performance is comparable to that of the MICADAS system.
Article
Geochemistry & Geophysics
Amaneh Kaveh-Firouz, Jean-Pierre Burg, Negar Haghipour, Sanjay Kumar Mandal, Marcus Christl, Ali Mohammadi
Summary: The study focuses on the tectonic and climatic controls on landscape evolution in the NNW Iranian Plateau and west Alborz region. By analyzing erosion rates and topographic/climatic metrics, the researchers found that erosion rates were low in the Plateau and relatively high in the west Alborz, with sediment fluxes controlled by topographic parameters and surface uplift and active thrust-faulting in the respective regions. Climate had a secondary role in erosion rates. Exhumation rates were also calculated and showed an increase during the collision between Arabia and Eurasia. The study highlights the importance of understanding the interplay between tectonic and climatic factors in shaping landscapes.
Article
Geosciences, Multidisciplinary
Giulia Sinnl, Florian Adolphi, Marcus Christl, Kees C. Welten, Thomas Woodruff, Marc Caffee, Anders Svensson, Raimund Muscheler, Sune Olander Rasmussen
Summary: During the last glacial, Greenland experienced a cold stadial phase with two short warm interstadials. Greenland ice-core calcium data shows two periods of high atmospheric dust loading, which is not well understood. The Chinese Hulu Cave speleothems also exhibit an climate signal during the same time. Antarctic ice cores show a relative warming, interpreted as a counterpart to a cool phase in the Northern Hemisphere. New Be-10 datasets from Greenland and Antarctic ice cores are examined to test the agreement between different timescales. Evidence of an event similar to the Maunder Solar Minimum is found in the new Be-10 datasets, supporting a synchronization with the Chinese speleothem around 22 kyr b2k. The offset between the Greenland ice-core chronology and the Antarctic chronology is determined to be 125 +/- 40 years, and the offset between the speleothem and ice-core timescales is determined to be 375 years for GICC05 and 225 years for WD2014, respectively.
CLIMATE OF THE PAST
(2023)
Article
Chemistry, Analytical
Shan Xing, Chenyang Peng, Marcus Christl, Keliang Shi, Hans-Arno Synal, Xiaolin Hou
Summary: Accelerator mass spectrometry (AMS) is a highly sensitive technique for measuring long-lived actinides. A new method was developed for simultaneous determination of transuranium nuclides (Np, Pu, Am, and Cm isotopes) using 300 kV AMS. The method uses sequential chemical separation and tracers for monitoring yield. The established method has high detection efficiency and has been successfully applied in nuclear forensic investigation.
ANALYTICAL CHEMISTRY
(2023)
