Measurement of the Half-Life of Fe-60 for Early Solar System and Stellar Models. Presentation given on May 5, 2016 as part of the requirements to earn a Ph.D. degree at the University of Notre Dame.
Triggered Star Formation inside the Shell of a Wolf–Rayet Bubble as the Origi...Sérgio Sacani
A critical constraint on solar system formation is the high Al 26 /27Al abundance ratio of ´ - 5 10 5 at the time of
formation, which was about 17 times higher than the average Galactic ratio, while the 60Fe/56Fe value was about
´ - 2 10 8, lower than the Galactic value. This challenges the assumption that a nearby supernova (SN) was
responsible for the injection of these short-lived radionuclides into the early solar system. We show that this
conundrum can be resolved if the solar system was formed by a triggered star formation at the edge of a Wolf–
Rayet (W–R) bubble. 26Al is produced during the evolution of the massive star, released in the wind during the
W–R phase, and condenses into dust grains that are seen around W–R stars. The dust grains survive passage
through the reverse shock and the low-density shocked wind, reach the dense shell swept-up by the bubble, detach
from the decelerated wind, and are injected into the shell. Some portions of this shell subsequently collapse to form
the dense cores that give rise to solar-type systems. The subsequent aspherical SN does not inject appreciable
amounts of Fe 60 into the proto–solar system, thus accounting for the observed low abundance of Fe 60 . We discuss
the details of various processes within the model and conclude that it is a viable model that can explain the initial
abundances of Al 26 and Fe 60 . We estimate that 1%–16% of all Sun-like stars could have formed in such a setting of
triggered star formation in the shell of a W–R bubble.
Colloquium given at the Caltech star formation group (Feb. 24, 2015) and NASA/JPL (Feb. 26, 2015). The presentation features recent research highlights by myself and collaborators and is intended for a non-expert astronomy audience.
Trap and Transfer. Two-Step Hole Injection Across the Sb2S3/CuSCN Interface i...kamatlab
Trap and Transfer. Two-Step Hole Injection Across the Sb2S3/CuSCN Interface in Solid State Solar Cells. ACS Nano, 2013, ASAP.
DOI: 10.1021/nn403058f
In solid-state semiconductor-sensitized solar cells, commonly known as extremely thin absorber (ETA) or solid-state quantum dot sensitized solar cells (QDSCs), transfer of photogenerated holes from the absorber species to the p-type hole conductor plays a critical role in the charge separation process. Using Sb2S3 (absorber) and CuSCN (hole conductor), we have constructed ETA solar cells exhibiting a power conversion efficiency of 3.3%. The hole transfer from excited Sb2S3 into CuSCN, which limits the overall power conversion efficiency of these solar cells, is now independently studied using transient absorption spectroscopy. In the Sb2S3 absorber layer, photogenerated holes are rapidly localized on the sulfur atoms of the crystal lattice, forming a sulfide radical (S−•) species. This trapped hole is transferred from the Sb2S3 absorber to the CuSCN hole conductor with an exponential time constant of 1680 ps. This process was monitored through the spectroscopic signal seen for the S−• species in Sb2S3, providing direct evidence for the hole transfer dynamics in ETA solar cells. Elucidation of the hole transfer mechanism from Sb2S3 to CuSCN represents a significant step toward understanding charge separation in Sb2S3 solar cells, and provides insight into the design of new architectures for higher efficiency devices.
Discovery and properties of the earliest galaxies with confirmed distancesSérgio Sacani
Surveys with James Webb Space Telescope (JWST) have discovered candidate galaxies in
the first 400 Myr of cosmic time1-5
. The properties of these distant galaxies provide initial
conditions for understanding early galaxy formation and cosmic reionisation6
. Preliminary
indications have suggested these candidate galaxies may be more massive and abundant
than previously thought1,7-9
. However, without spectroscopic confirmation of their
distances to constrain their intrinsic brightnesses, their inferred properties remain
uncertain. Here we report on four galaxies located in the JWST Advanced Deep
Extragalactic Survey (JADES) Near-Infrared Camera (NIRCam) imaging with
photometric redshifts � ∼ �� − �� subsequently confirmed by JADES JWST NearInfrared Spectrograph (NIRSpec) observations10. These galaxies include the first redshift
� > �� systems both discovered and spectroscopically confirmed by JWST. Using stellar
population modelling, we find the galaxies typically contain a hundred million solar masses
in stars, in stellar populations that are less than one hundred million years old. The
moderate star formation rates and compact sizes suggest elevated star formation rate
surface densities, a key indicator of their formation pathways. Taken together, these
measurements show that the first galaxies contributing to cosmic reionisation formed
rapidly and with intense internal radiation fields.
Energetic eruptions leading to a peculiar hydrogen-rich explosion of a massi...Sérgio Sacani
Every supernova so far observed has been considered to be the terminal explosion of a star. Moreover, all supernovae with absorption lines in their spectra show those lines decreasing in velocity over time, as the ejecta expand and thin, revealing slower-moving material that was previously hidden. In addition, every supernova that exhibits the absorption lines of hydrogen has one main light-curve peak, or a plateau in luminosity, lasting approximately 100 days before declining1. Here we report observations of iPTF14hls, an event that has spectra identical to a hydrogen-rich core-collapse supernova, but characteristics that differ extensively from those of known supernovae. The light curve has at least five peaks and remains bright for more than 600 days; the absorption lines show little to no decrease in velocity; and the radius of the line-forming region is more than an order of magnitude bigger than the radius of the photosphere derived from the continuum emission. These characteristics are consistent with a shell of several tens of solar masses ejected by the progenitor star at supernova-level energies a few hundred days before a terminal explosion. Another possible eruption was recorded at the same position in 1954. Multiple energetic pre-supernova eruptions are expected to occur in stars of 95 to 130 solar masses, which experience the pulsational pair instability2–5. That model, however, does not account for the continued presence of hydrogen, or the energetics observed here. Another mechanism for the violent ejection of mass in massive stars may be required.
EXTINCTION AND THE DIMMING OF KIC 8462852Sérgio Sacani
To test alternative hypotheses for the behavior of KIC 8462852, we obtained measurements of the star
over a wide wavelength range from the UV to the mid-infrared from October 2015 through December
2016, using Swift, Spitzer and at AstroLAB IRIS. The star faded in a manner similar to the longterm
fading seen in Kepler data about 1400 days previously. The dimming rate for the entire period
reported is 22.1 ± 9.7 milli-mag yr−1
in the Swift wavebands, with amounts of 21.0 ± 4.5 mmag in
the groundbased B measurements, 14.0 ± 4.5 mmag in V , and 13.0 ± 4.5 in R, and a rate of 5.0 ± 1.2
mmag yr−1 averaged over the two warm Spitzer bands. Although the dimming is small, it is seen at
& 3 σ by three different observatories operating from the UV to the IR. The presence of long-term
secular dimming means that previous SED models of the star based on photometric measurements
taken years apart may not be accurate. We find that stellar models with Tef f = 7000 - 7100 K and
AV ∼ 0.73 best fit the Swift data from UV to optical. These models also show no excess in the
near-simultaneous Spitzer photometry at 3.6 and 4.5 µm, although a longer wavelength excess from
a substantial debris disk is still possible (e.g., as around Fomalhaut). The wavelength dependence of
the fading favors a relatively neutral color (i.e., RV & 5, but not flat across all the bands) compared
with the extinction law for the general ISM (RV = 3.1), suggesting that the dimming arises from
circumstellar material
Plenary lecture of the XIV SBPMat Meeting, given by Prof. Ichiro Takeuchi (University of Maryland, USA) on September 30, 2015, in Rio de Janeiro (Brazil).
Eu-doped strontium iodide single crystal growth has reached maturity and prototype SrI2(Eu)-based gamma ray spectrometers provide detection performance advantages over standard detectors. SrI2(Eu) offers a high, proportional light yield of >80,000 photons/MeV. Energy resolution of <3% at 662 keV with 1.5” x 1.5” SrI2(Eu) crystals is routinely achieved, by employing either a small taper at the top of the crystal or a digital readout technique. These methods overcome light-trapping, in which scintillation light is re-absorbed and re-emitted in Eu2+-doped crystals. Its excellent energy resolution, lack of intrinsic radioactivity or toxicity, and commercial availability make SrI2(Eu) the ideal scintillator for use in handheld radioisotope identification devices. A 6-lb SrI2(Eu) radioisotope identifier is described.
Spirals and clumps in V960 Mon: signs of planet formation via gravitational i...Sérgio Sacani
The formation of giant planets has traditionally been divided into two pathways: core accretion and gravitational instability. However, in recent years, gravitational instability has become less favored, primarily due
to the scarcity of observations of fragmented protoplanetary disks around young stars and low occurrence rate
of massive planets on very wide orbits. In this study, we present a SPHERE/IRDIS polarized light observation
of the young outbursting object V960 Mon. The image reveals a vast structure of intricately shaped scattered
light with several spiral arms. This finding motivated a re-analysis of archival ALMA 1.3 mm data acquired
just two years after the onset of the outburst of V960 Mon. In these data, we discover several clumps of continuum emission aligned along a spiral arm that coincides with the scattered light structure. We interpret the
localized emission as fragments formed from a spiral arm under gravitational collapse. Estimating the mass of
solids within these clumps to be of several Earth masses, we suggest this observation to be the first evidence of
gravitational instability occurring on planetary scales. This study discusses the significance of this finding for
planet formation and its potential connection with the outbursting state of V960 Mon.
Triggered Star Formation inside the Shell of a Wolf–Rayet Bubble as the Origi...Sérgio Sacani
A critical constraint on solar system formation is the high Al 26 /27Al abundance ratio of ´ - 5 10 5 at the time of
formation, which was about 17 times higher than the average Galactic ratio, while the 60Fe/56Fe value was about
´ - 2 10 8, lower than the Galactic value. This challenges the assumption that a nearby supernova (SN) was
responsible for the injection of these short-lived radionuclides into the early solar system. We show that this
conundrum can be resolved if the solar system was formed by a triggered star formation at the edge of a Wolf–
Rayet (W–R) bubble. 26Al is produced during the evolution of the massive star, released in the wind during the
W–R phase, and condenses into dust grains that are seen around W–R stars. The dust grains survive passage
through the reverse shock and the low-density shocked wind, reach the dense shell swept-up by the bubble, detach
from the decelerated wind, and are injected into the shell. Some portions of this shell subsequently collapse to form
the dense cores that give rise to solar-type systems. The subsequent aspherical SN does not inject appreciable
amounts of Fe 60 into the proto–solar system, thus accounting for the observed low abundance of Fe 60 . We discuss
the details of various processes within the model and conclude that it is a viable model that can explain the initial
abundances of Al 26 and Fe 60 . We estimate that 1%–16% of all Sun-like stars could have formed in such a setting of
triggered star formation in the shell of a W–R bubble.
Colloquium given at the Caltech star formation group (Feb. 24, 2015) and NASA/JPL (Feb. 26, 2015). The presentation features recent research highlights by myself and collaborators and is intended for a non-expert astronomy audience.
Trap and Transfer. Two-Step Hole Injection Across the Sb2S3/CuSCN Interface i...kamatlab
Trap and Transfer. Two-Step Hole Injection Across the Sb2S3/CuSCN Interface in Solid State Solar Cells. ACS Nano, 2013, ASAP.
DOI: 10.1021/nn403058f
In solid-state semiconductor-sensitized solar cells, commonly known as extremely thin absorber (ETA) or solid-state quantum dot sensitized solar cells (QDSCs), transfer of photogenerated holes from the absorber species to the p-type hole conductor plays a critical role in the charge separation process. Using Sb2S3 (absorber) and CuSCN (hole conductor), we have constructed ETA solar cells exhibiting a power conversion efficiency of 3.3%. The hole transfer from excited Sb2S3 into CuSCN, which limits the overall power conversion efficiency of these solar cells, is now independently studied using transient absorption spectroscopy. In the Sb2S3 absorber layer, photogenerated holes are rapidly localized on the sulfur atoms of the crystal lattice, forming a sulfide radical (S−•) species. This trapped hole is transferred from the Sb2S3 absorber to the CuSCN hole conductor with an exponential time constant of 1680 ps. This process was monitored through the spectroscopic signal seen for the S−• species in Sb2S3, providing direct evidence for the hole transfer dynamics in ETA solar cells. Elucidation of the hole transfer mechanism from Sb2S3 to CuSCN represents a significant step toward understanding charge separation in Sb2S3 solar cells, and provides insight into the design of new architectures for higher efficiency devices.
Discovery and properties of the earliest galaxies with confirmed distancesSérgio Sacani
Surveys with James Webb Space Telescope (JWST) have discovered candidate galaxies in
the first 400 Myr of cosmic time1-5
. The properties of these distant galaxies provide initial
conditions for understanding early galaxy formation and cosmic reionisation6
. Preliminary
indications have suggested these candidate galaxies may be more massive and abundant
than previously thought1,7-9
. However, without spectroscopic confirmation of their
distances to constrain their intrinsic brightnesses, their inferred properties remain
uncertain. Here we report on four galaxies located in the JWST Advanced Deep
Extragalactic Survey (JADES) Near-Infrared Camera (NIRCam) imaging with
photometric redshifts � ∼ �� − �� subsequently confirmed by JADES JWST NearInfrared Spectrograph (NIRSpec) observations10. These galaxies include the first redshift
� > �� systems both discovered and spectroscopically confirmed by JWST. Using stellar
population modelling, we find the galaxies typically contain a hundred million solar masses
in stars, in stellar populations that are less than one hundred million years old. The
moderate star formation rates and compact sizes suggest elevated star formation rate
surface densities, a key indicator of their formation pathways. Taken together, these
measurements show that the first galaxies contributing to cosmic reionisation formed
rapidly and with intense internal radiation fields.
Energetic eruptions leading to a peculiar hydrogen-rich explosion of a massi...Sérgio Sacani
Every supernova so far observed has been considered to be the terminal explosion of a star. Moreover, all supernovae with absorption lines in their spectra show those lines decreasing in velocity over time, as the ejecta expand and thin, revealing slower-moving material that was previously hidden. In addition, every supernova that exhibits the absorption lines of hydrogen has one main light-curve peak, or a plateau in luminosity, lasting approximately 100 days before declining1. Here we report observations of iPTF14hls, an event that has spectra identical to a hydrogen-rich core-collapse supernova, but characteristics that differ extensively from those of known supernovae. The light curve has at least five peaks and remains bright for more than 600 days; the absorption lines show little to no decrease in velocity; and the radius of the line-forming region is more than an order of magnitude bigger than the radius of the photosphere derived from the continuum emission. These characteristics are consistent with a shell of several tens of solar masses ejected by the progenitor star at supernova-level energies a few hundred days before a terminal explosion. Another possible eruption was recorded at the same position in 1954. Multiple energetic pre-supernova eruptions are expected to occur in stars of 95 to 130 solar masses, which experience the pulsational pair instability2–5. That model, however, does not account for the continued presence of hydrogen, or the energetics observed here. Another mechanism for the violent ejection of mass in massive stars may be required.
EXTINCTION AND THE DIMMING OF KIC 8462852Sérgio Sacani
To test alternative hypotheses for the behavior of KIC 8462852, we obtained measurements of the star
over a wide wavelength range from the UV to the mid-infrared from October 2015 through December
2016, using Swift, Spitzer and at AstroLAB IRIS. The star faded in a manner similar to the longterm
fading seen in Kepler data about 1400 days previously. The dimming rate for the entire period
reported is 22.1 ± 9.7 milli-mag yr−1
in the Swift wavebands, with amounts of 21.0 ± 4.5 mmag in
the groundbased B measurements, 14.0 ± 4.5 mmag in V , and 13.0 ± 4.5 in R, and a rate of 5.0 ± 1.2
mmag yr−1 averaged over the two warm Spitzer bands. Although the dimming is small, it is seen at
& 3 σ by three different observatories operating from the UV to the IR. The presence of long-term
secular dimming means that previous SED models of the star based on photometric measurements
taken years apart may not be accurate. We find that stellar models with Tef f = 7000 - 7100 K and
AV ∼ 0.73 best fit the Swift data from UV to optical. These models also show no excess in the
near-simultaneous Spitzer photometry at 3.6 and 4.5 µm, although a longer wavelength excess from
a substantial debris disk is still possible (e.g., as around Fomalhaut). The wavelength dependence of
the fading favors a relatively neutral color (i.e., RV & 5, but not flat across all the bands) compared
with the extinction law for the general ISM (RV = 3.1), suggesting that the dimming arises from
circumstellar material
Plenary lecture of the XIV SBPMat Meeting, given by Prof. Ichiro Takeuchi (University of Maryland, USA) on September 30, 2015, in Rio de Janeiro (Brazil).
Eu-doped strontium iodide single crystal growth has reached maturity and prototype SrI2(Eu)-based gamma ray spectrometers provide detection performance advantages over standard detectors. SrI2(Eu) offers a high, proportional light yield of >80,000 photons/MeV. Energy resolution of <3% at 662 keV with 1.5” x 1.5” SrI2(Eu) crystals is routinely achieved, by employing either a small taper at the top of the crystal or a digital readout technique. These methods overcome light-trapping, in which scintillation light is re-absorbed and re-emitted in Eu2+-doped crystals. Its excellent energy resolution, lack of intrinsic radioactivity or toxicity, and commercial availability make SrI2(Eu) the ideal scintillator for use in handheld radioisotope identification devices. A 6-lb SrI2(Eu) radioisotope identifier is described.
Spirals and clumps in V960 Mon: signs of planet formation via gravitational i...Sérgio Sacani
The formation of giant planets has traditionally been divided into two pathways: core accretion and gravitational instability. However, in recent years, gravitational instability has become less favored, primarily due
to the scarcity of observations of fragmented protoplanetary disks around young stars and low occurrence rate
of massive planets on very wide orbits. In this study, we present a SPHERE/IRDIS polarized light observation
of the young outbursting object V960 Mon. The image reveals a vast structure of intricately shaped scattered
light with several spiral arms. This finding motivated a re-analysis of archival ALMA 1.3 mm data acquired
just two years after the onset of the outburst of V960 Mon. In these data, we discover several clumps of continuum emission aligned along a spiral arm that coincides with the scattered light structure. We interpret the
localized emission as fragments formed from a spiral arm under gravitational collapse. Estimating the mass of
solids within these clumps to be of several Earth masses, we suggest this observation to be the first evidence of
gravitational instability occurring on planetary scales. This study discusses the significance of this finding for
planet formation and its potential connection with the outbursting state of V960 Mon.
Phenomics assisted breeding in crop improvementIshaGoswami9
As the population is increasing and will reach about 9 billion upto 2050. Also due to climate change, it is difficult to meet the food requirement of such a large population. Facing the challenges presented by resource shortages, climate
change, and increasing global population, crop yield and quality need to be improved in a sustainable way over the coming decades. Genetic improvement by breeding is the best way to increase crop productivity. With the rapid progression of functional
genomics, an increasing number of crop genomes have been sequenced and dozens of genes influencing key agronomic traits have been identified. However, current genome sequence information has not been adequately exploited for understanding
the complex characteristics of multiple gene, owing to a lack of crop phenotypic data. Efficient, automatic, and accurate technologies and platforms that can capture phenotypic data that can
be linked to genomics information for crop improvement at all growth stages have become as important as genotyping. Thus,
high-throughput phenotyping has become the major bottleneck restricting crop breeding. Plant phenomics has been defined as the high-throughput, accurate acquisition and analysis of multi-dimensional phenotypes
during crop growing stages at the organism level, including the cell, tissue, organ, individual plant, plot, and field levels. With the rapid development of novel sensors, imaging technology,
and analysis methods, numerous infrastructure platforms have been developed for phenotyping.
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana Luísa Pinho
Functional Magnetic Resonance Imaging (fMRI) provides means to characterize brain activations in response to behavior. However, cognitive neuroscience has been limited to group-level effects referring to the performance of specific tasks. To obtain the functional profile of elementary cognitive mechanisms, the combination of brain responses to many tasks is required. Yet, to date, both structural atlases and parcellation-based activations do not fully account for cognitive function and still present several limitations. Further, they do not adapt overall to individual characteristics. In this talk, I will give an account of deep-behavioral phenotyping strategies, namely data-driven methods in large task-fMRI datasets, to optimize functional brain-data collection and improve inference of effects-of-interest related to mental processes. Key to this approach is the employment of fast multi-functional paradigms rich on features that can be well parametrized and, consequently, facilitate the creation of psycho-physiological constructs to be modelled with imaging data. Particular emphasis will be given to music stimuli when studying high-order cognitive mechanisms, due to their ecological nature and quality to enable complex behavior compounded by discrete entities. I will also discuss how deep-behavioral phenotyping and individualized models applied to neuroimaging data can better account for the subject-specific organization of domain-general cognitive systems in the human brain. Finally, the accumulation of functional brain signatures brings the possibility to clarify relationships among tasks and create a univocal link between brain systems and mental functions through: (1) the development of ontologies proposing an organization of cognitive processes; and (2) brain-network taxonomies describing functional specialization. To this end, tools to improve commensurability in cognitive science are necessary, such as public repositories, ontology-based platforms and automated meta-analysis tools. I will thus discuss some brain-atlasing resources currently under development, and their applicability in cognitive as well as clinical neuroscience.
The ability to recreate computational results with minimal effort and actionable metrics provides a solid foundation for scientific research and software development. When people can replicate an analysis at the touch of a button using open-source software, open data, and methods to assess and compare proposals, it significantly eases verification of results, engagement with a diverse range of contributors, and progress. However, we have yet to fully achieve this; there are still many sociotechnical frictions.
Inspired by David Donoho's vision, this talk aims to revisit the three crucial pillars of frictionless reproducibility (data sharing, code sharing, and competitive challenges) with the perspective of deep software variability.
Our observation is that multiple layers — hardware, operating systems, third-party libraries, software versions, input data, compile-time options, and parameters — are subject to variability that exacerbates frictions but is also essential for achieving robust, generalizable results and fostering innovation. I will first review the literature, providing evidence of how the complex variability interactions across these layers affect qualitative and quantitative software properties, thereby complicating the reproduction and replication of scientific studies in various fields.
I will then present some software engineering and AI techniques that can support the strategic exploration of variability spaces. These include the use of abstractions and models (e.g., feature models), sampling strategies (e.g., uniform, random), cost-effective measurements (e.g., incremental build of software configurations), and dimensionality reduction methods (e.g., transfer learning, feature selection, software debloating).
I will finally argue that deep variability is both the problem and solution of frictionless reproducibility, calling the software science community to develop new methods and tools to manage variability and foster reproducibility in software systems.
Exposé invité Journées Nationales du GDR GPL 2024
This presentation explores a brief idea about the structural and functional attributes of nucleotides, the structure and function of genetic materials along with the impact of UV rays and pH upon them.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Remote Sensing and Computational, Evolutionary, Supercomputing, and Intellige...University of Maribor
Slides from talk:
Aleš Zamuda: Remote Sensing and Computational, Evolutionary, Supercomputing, and Intelligent Systems.
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Inter-Society Networking Panel GRSS/MTT-S/CIS Panel Session: Promoting Connection and Cooperation
https://www.etran.rs/2024/en/home-english/
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Comparing Evolved Extractive Text Summary Scores of Bidirectional Encoder Rep...University of Maribor
Slides from:
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Track: Artificial Intelligence
https://www.etran.rs/2024/en/home-english/
1. Measurement of the Half-Life of 60
Fe for Early
Solar System and Stellar Models
Karen M. Ostdiek
Nuclear Science Laboratory, University of Notre Dame
Notre Dame, Indiana U.S.A.
May 5, 2016
2. Motivation from Nuclear Astrophysics for 60
Fe
Possible Production Sites for 60Fe
Weak s-process, successive neutron
captures on 58Fe.
Massive AGB stars -
13C(α, n)16O
Core Collapse Supernova -
22Ne(α, n)25Mg.
Karen Ostdiek Measuring the Half-life of 60
Fe 2/ 35
3. Motivation from Nuclear Astrophysics & Evidence of 60
Fe
Evidence of 60Fe
Less of 60Ni granddaughter
product in meteorite inclusions.
γ decay observed in Galaxy.
Increased concentration in
ocean crust samples.
Superimposed 60
Fe decay lines, W. Wang, et al. Astro.
and Astrophys. 469. (2007).
Unequilbrated Ordinary Chondrites, R. K. Mishra, et al.
Astrophys. Journal. Letters. 714. (2010).
K. Knie, et al. Phys. Rev. Letters. 93. (2004).
Fitoussi, et al. Phys. Rev. Letters. 101. (2008)
Karen Ostdiek Measuring the Half-life of 60
Fe 3/ 35
5. Previous Half-life Measurements
Roy & Kohman, 1957:
∼ 3 · 105 years
factor of 3 uncertainty
Kutschera, et. al, 1984:
(1.49 ± 0.27) · 106 years
Rugel, et. al, 2009:
(2.62 ± 0.04) · 106 years
Karen Ostdiek Measuring the Half-life of 60
Fe 5/ 35
6. Measuring long half-lives and ‘making’ a Sample
A = dN
dt = λN = ln2
t1/2
N
Karen Ostdiek Measuring the Half-life of 60
Fe 6/ 35
7. Samples for Activity and AMS Experiments
Original material from PSI copper beam stop (bombarded by
protons for 12 years).
Karen Ostdiek Measuring the Half-life of 60
Fe 7/ 35
9. Ascertaining the Activity - Sample Evaporation
VERA “Fe-1” 13 mL sample evaporated to
point source.
Contains ∼ 1.4 · 1014 60
Fe atoms.
Karen Ostdiek Measuring the Half-life of 60
Fe 9/ 35
10. Ascertaining the Activity - Decay Scheme for 60
Fe
Karen Ostdiek Measuring the Half-life of 60
Fe 10/ 35
11. Ascertaining the Activity - Decay Scheme for 60
Fe
Direct Decay: Roy and
Kohman
Karen Ostdiek Measuring the Half-life of 60
Fe 11/ 35
12. Ascertaining the Activity - Decay Scheme for 60
Fe
Direct Decay: Roy and
Kohman
Grow-in Decay:
Kutschera, et al., Rugel,
et al., and Wallner, et al.
Karen Ostdiek Measuring the Half-life of 60
Fe 12/ 35
13. Ascertaining the Activity - Detailed Decay and Sample Prep.
60Fe
0+
2+
60Co
5+
2.62 Myr
10.5 min
1925.28 days
58 keV
Zoomed in on Direct Decay
Isomeric Decay of 60m
Co = Internal Conversion.
2 HPGe Planar detectors with
thin Be windows.
Total Efficiencies of 10% based
on 241Am.
Karen Ostdiek Measuring the Half-life of 60
Fe 13/ 35
14. Ascertaining the Activity - Results
Background line at 63 keV is from 234Th in the 238U decay chain
Increase in continuum is from bremsstralung photons.
Activity Corrected = (9.7926 ± 0.0031) decays/second
Karen Ostdiek Measuring the Half-life of 60
Fe 14/ 35
15. Now on to part two...
Concentration 60/56 × (# of 59Fe atoms added) = # of 60Fe atoms
Karen Ostdiek Measuring the Half-life of 60
Fe 15/ 35
16. Identifying 60
Fe - Facilities
Karen Ostdiek Measuring the Half-life of 60
Fe 16/ 35
17. Identifying 60
Fe - Second Stripper
Karen Ostdiek Measuring the Half-life of 60
Fe 17/ 35
18. Identifying 60
Fe - Wien Filter
Karen Ostdiek Measuring the Half-life of 60
Fe 18/ 35
19. Identifying 60
Fe - AMS Beam Line
Karen Ostdiek Measuring the Half-life of 60
Fe 19/ 35
20. Identifying 60
Fe - Separating by Position
Karen Ostdiek Measuring the Half-life of 60
Fe 20/ 35
21. Identifying 60
Fe - Separating by Position
Karen Ostdiek Measuring the Half-life of 60
Fe 21/ 35
22. Identifying 60
Fe - Separating by Energy
Energy = 112 MeV using 8.5 MV, Second stripper, 9+ to 16+
Karen Ostdiek Measuring the Half-life of 60
Fe 22/ 35
23. Identifying 60
Fe - Finding Concentration
Concentration 60/56 × (# of 59Fe atoms added) = # of 60Fe atoms
Concentration 60/56 = (Count60/time) × (1/Transmission) × (1/I56)
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24. Identifying 60
Fe - 60
Fe Spectra and Results
Blank (background) concentration
= ∼ 10−12 60Fe/56Fe
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25. Identifying 60
Fe - 60
Fe Spectra and Results
Fe-4 (unscaled) concentration =
(8.243 ± 0.910) × 10−10 60Fe/56Fe
Fe-4 (scaled) concentration =
(2.095 ± 0.331) × 10−9 60Fe/56Fe
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26. Identifying 60
Fe - 60
Fe Spectra and Results
Fe-1 (unscaled) concentration =
(8.408 ± 0.211) × 10−7 60Fe/56Fe
Fe-1 (scaled) concentration =
(2.066 ± 0.242) × 10−6 60Fe/56Fe
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27. Preliminary Result & Conclusion
60
Fe t1/2: (2.29 ± 0.27) · 106
years
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28. Combined Results with Wallner, et al.
t1/2 =
ln 2 · (1.145 × 1015 atoms)
9.7926 Bq
= (2.57 ± 0.11) × 106
years
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29. Preliminary Results from May 3-4, 2016
Mass 58
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30. Preliminary Results from May 3-4, 2016
Fe-1:
Preliminary Scaled Concentration
= (2.218 ± 0.112) × 10−6
Preliminary Half-Life =
(2.46 ± 0.12) × 106 years.
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31. Summary
Activity
Built low-background counting station
Measured 60m
Co state, combining for the first time with AMS
Results for Fe-1 = 9.7926 Bq
AMS
Development 60
Fe beam and AMS settings
Recommissioned second stripper for higher energy beams
Only lab to have measure Fe-1 sample directly
Results=2.218 × 10−6
Concentration
Results: 60Fe half-life = 2.46 million years
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32. Thank You!!!
Collaborators:
Tyler Anderson
William Bauder
Matthew Bowers
Adam Clark
Philippe Collon
Wenting Lu
Austin Nelson
Daniel Robertson
Michael Skulski
Rugard Dressler - PSI
John Greene - ANL
Walter Kutschera - VERA
Michael Paul - Racah Inst.
Dorothea Schumann - PSI
Toni Wallner - ANU
Others: NSL Staff:
Bryan Ostdiek Jeff Holdeman
Ed Lamere Jim Kaiser
Mike Moran Jerry Lingle
Mallory Smith Brad Mulder
Matt Sanford
Ed Stech
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33. Measuring the Activity - Old Lead Castles
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34. Measuring the Activity - Testing Lead Bricks
Tested almost 100 Lead bricks, including several half-bricks, each
measured for 8 hours.
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35. Measuring the Activity - Testing Lead Bricks
Tested almost 100 Lead bricks, including several half-bricks.
137Cs - in dirt and dust, 235U - in “modern” Lead bricks, Pb X ray,
and ROI.
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36. Measuring the Activity - Testing Lead Bricks
Tested almost 100 Lead bricks, including several half-bricks.
137Cs - in dirt and dust, 235U - in “modern” Lead bricks, Pb X ray,
and ROI.
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37. Measuring the Activity - Lead Castle renovations
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38. Measuring the Activity - “New” Lead Castle
2 HPGe Planar detectors with
thin Be windows (courtesy of
ANL)
Total Efficiencies of both
Detectors near 58 keV ∼10%
based on the 59.54 keV decay
in 241Am
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39. Preliminary Results & Conclusions
Small deviations in 60Fe/56Fe concentrations lead to significant
changes in half-life.
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