Abstract Massive stars are a major source of chemical elements in the cosmos, ejecting freshly produced nuclei through winds and core-collapse supernova explosions into the interstellar medium. Among the material ejected, long-lived radioisotopes, such as60Fe (iron) and26Al (aluminum), offer unique signs of active nucleosynthesis in our galaxy. There is a long-standing discrepancy between the observed60Fe/26Al ratio by γ-ray telescopes and predictions from supernova models. This discrepancy has been attributed to uncertainties in the nuclear reaction networks producing60Fe, and one reaction in particular, the neutron-capture on59Fe. Here we present experimental results that provide a strong constraint on this reaction. We use these results to show that the production of60Fe in massive stars is higher than previously thought, further increasing the discrepancy between observed and predicted60Fe/26Al ratios. The persisting discrepancy can therefore not be attributed to nuclear uncertainties, and points to issues in massive-star models.
more »
« less
Development and applications of accelerator mass spectrometry methods for measurement of 14C, 10Be and 26Al in the CENTA laboratory
Abstract Terrestrial and extraterrestrial radioisotope research has been strongly dependent on the development of analytical methods which would enable to trace radioisotopes at low concentrations in subgram samples (e.g., in tree rings, ice cores, meteorites, etc.). Accelerator mass spectrometry (AMS) has become the most sensitive technique for ultralow-level analysis of long-lived radioisotopes, such as14C,10Be and26Al. We review developments and applications carried out in the CENTA laboratory, and describe a recently installed fully equipped AMS line, designed for analysis of long-lived radioisotopes from tritium to curium.
more »
« less
- Award ID(s):
- 1812374
- PAR ID:
- 10546528
- Publisher / Repository:
- J. Radioanal. Nucl. Chem.
- Date Published:
- Journal Name:
- Journal of Radioanalytical and Nuclear Chemistry
- Volume:
- 333
- Issue:
- 7
- ISSN:
- 0236-5731
- Page Range / eLocation ID:
- 3497 to 3509
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract While modeling the galactic chemical evolution (GCE) of stable elements provides insights to the formation history of the Galaxy and the relative contributions of nucleosynthesis sites, modeling the evolution of short-lived radioisotopes (SLRs) can provide supplementary timing information on recent nucleosynthesis. To study the evolution of SLRs, we need to understand their spatial distribution. Using a three-dimensional GCE model, we investigated the evolution of four SLRs:53Mn,60Fe,182Hf, and244Pu with the aim of explaining detections of recent (within the last ≈1–20 Myr) deposition of live53Mn,60Fe, and244Pu of extrasolar origin into deep-sea reservoirs. We find that core-collapse supernovae are the dominant propagation mechanism of SLRs in the Galaxy. This results in the simultaneous arrival of these four SLRs on Earth, although they could have been produced in different astrophysical sites, which can explain why live extrasolar53Mn,60Fe, and244Pu are found within the same, or similar, layers of deep-sea sediments. We predict that182Hf should also be found in such sediments at similar depths.more » « less
-
Abstract The LEGEND collaboration has been developing a76Ge-based double-beta decay experimental program where precise radiopurity measurements of ultraclean materials are crucial. Ultralow concentrations of thorium and uranium, the main contributors to the detector background via their decay products, can be determined by inductively coupled plasma mass spectrometry (ICPMS) and accelerator mass spectrometry (AMS). Here we shall present recent developments in thorium and uranium mass spectrometry methods, together with basics of separation chemistry applied to process different samples. The new possibilities to measure232Th and238U by ICPMS and AMS at the Comenius University in Bratislava are discussed as well.more » « less
-
Abstract 244Pu has recently been discovered in deep-sea deposits spanning the past 10 Myr, a period that includes two60Fe pulses from nearby supernovae.244Pu is among the heaviestr-process products, and we consider whether it was created in supernovae, which is disfavored by nucleosynthesis simulations, or in an earlier kilonova event that seeded the nearby interstellar medium with244Pu that was subsequently swept up by the supernova debris. We discuss how these possibilities can be probed by measuring244Pu and otherr-process radioisotopes such as129I and182Hf, both in lunar regolith samples returned to Earth by missions such as Chang’e and Artemis, and in deep-sea deposits.more » « less
An official website of the United States government

