Half-lives ought to be accurate, and preferably precise as well. This contribution discusses cases of long-lived radionuclides used in measurements with accelerator mass spectrometry (AMS), where multiple half-life measurements on specific radionuclides do not agree within the stated uncertainties. This we call "unsettled" half-lives. We include also some cases where only very old half-life measurements (>50 years ago) exist, sometimes only one single measurement. Half-life measurements of the following radionuclides are being discussed: Si-32, Mn-53, Ni-59, Se-79, Cs-135, Sm-146, and Po-209. These radionuclides are of interest for a variety of applications with AMS where accurate half-life values would be important.

Stellar abundances of cerium are of high current interest based both on observations and theoretical models, especially with regard to the neutron -magic 140Ce isotope. A large discrepancy of s -process stellar models relative to cerium abundance observed in globular clusters was highlighted, pointing to possible uncertainties in experimental nuclear reaction rates. In this work, the stellar neutron capture cross section of the stable cerium isotopes 136Ce, 138Ce, 140Ce, and 142Ce, were remeasured. A natCe sample was irradiated with quasi-Maxwellian neutrons at kT = 34.2 keV using the 7Li(p, n) reaction. The neutron field with an intensity of 3-5 x 1010 n/s was produced by irradiating the liquid -lithium target (LiLiT) with a mA proton beam at an energy (1.92 MeV) just above the threshold at Soreq Applied Research Accelerator Facility (SARAF). The activities of the natCe neutron capture products were measured using a shielded high purity germanium detector. Cross sections were extracted relative to that of the 197Au(n, gamma) reaction and the Maxwellian-averaged cross section (MACS) of the Ce isotopes were derived. The MACS values extracted from this experiment are generally consistent with previous measurements and show for 140Ce a value eta 15% smaller than most recent experimental values.

The global nature of the interaction of the heliosphere and the Local Interstellar Medium (LISM) is among one of the most outstanding space physics problems of today. Ultimately, our magnetic bubble is upheld by the expanding solar wind born in the solar corona that is now accessible by Parker Solar Probe. At the other extreme boundary, a completely new regime of physical interactions is at work that shape the unseen global structure of the entire heliosphere. Voyager 1 and 2 are soon nearing their end of operations inside of 170 AU and their payloads dedicated to planetary science have uncovered a region of space that defies our understanding. At the same time, IBEX and Cassini have obtained complementary “inside-out” ENA images of the heliospheric boundary region that cannot be fully explained. An Interstellar Probe through the heliospheric boundary, in to the LISM would be the first dedicated mission to venture into this largely unexplored frontier of space. With a dedicated suite of in-situ and remote-sensing instrumentation, such a probe would not only open the door for a new regime of space physics acting at the boundary and in other astrospheres, but would also obtain the very first images from the outside of the global structure of the heliosphere that, in context with the in-situ measurements would enable a quantum leap in understanding the global nature of our own habitable astrosphere. Beyond the Heliopause, the Interstellar Probe would offer the first sampling of the properties of the Local Interstellar Cloud and interstellar dust that are completely new scientific territories. Relatively modest contributions across divisions would offer historic science returns, including a flyby of one or two Kuiper Belt Objects, first insights in to the structure of the circum-solar dust disk, and the first measurements of the Extra-galactic Background Light beyond the obscuring Zodiacal cloud. In summary, an Interstellar Probe would represent humanity’s first step in to the galaxy and become the farthest space exploration ever undertaken. The idea of an Interstellar Probe and a Solar Probe shares a common beginning as two of the “Special Probes” that the Simpson Committee carried forward in their Interim Report to the Space Studies Board in 1960. Since then, an Interstellar Probe has scientifically been highly rated in the Solar and Space Physics Decadal Surveys, but the lack of propulsion technologies and launch vehicles have presented a stumbling block for its realization. However, this bottleneck is now being removed with the development of the Space Launch System (SLS) Block 2 with first launch projected to end of the 2020’s. A study funded by NASA is now progressing towards its third year of developing realistic mission architectures for an Interstellar Probe using technology ready for launch beginning 2030. An SLS Block 2, with an Atlas Centaur 3rdstage, a Star 48 4th stage could propel a spacecraft up to about 8.5 AU/year, which would be more than twice the fastest escaping spacecraft (Voyager 1 at 3.6 AU/year). The scenario would use a direct inject to Jupiter followed by a Jupiter Gravity assist powered by the 4th stage. The mission trade space is bound by requirements to be able to operate out to 1000 AU, 600 W of power beginning of mission, and survive up to 50 years. Here, we discuss the outstanding science questions that could be addressed by a mission to the LISM, notional science payload and report on realistic mission architectures, design concepts and trades, enabling technologies, and programmatic challenges.

Environmental detection of trace isotopes 233U and 236U are important forensic signatures for identifying uranium ore materials or tracking anthropogenic releases from weapons fallout or nuclear reprocessing. Currently, Accelerator Mass Spectrometry (AMS) is the only method sensitive enough to detect signatures of 233U/U and 236U/U at the natural level due to the molecular interferences of 232ThH and 235UH, respectively, often present in conventional mass spectrometry. In this work, we detail the AMS capabilities of actinides developed at the University of Notre Dame's Nuclear Science Laboratory (NSL). For the first time in our laboratory, we have measured isotopic ratios of 236U/U and explored additional signatures of 233U and decay chain products 231Pa and 230Th in both natural ore material and two National Bureau of Standards samples. In this work we estimate a system sensitivity for 236U/U of 1.4×10-11 and characterize the simultaneous detection of 233U, 231Pa, and 230Th.

A mission that traverses through our solar system, past the boundaries of our heliosphere, and out of our habitable astrosphere to the very local interstellar medium (VLISM) provides a unique opportunity for various in-situ and remote observations during this long journey. The Interstellar Probe mission concept explores a near term, pragmatic basis for designing such a mission, prioritizing critical science measurements while identifying and working with the engineering constraints that come with a long duration mission operating far away from Earth. One of the many challenges of such a mission is selecting instrumentation that will collectively meet science requirements over a long baseline. In order to accomplish this, a variety of instruments will be need to be included in the payload, while keeping in mind size, mass, and power constraints for the mission. These may include particle and field sensors, imaging spectrometers, spectrographs, mass spectrometers, and dust analyzers.Magnetometers (MAG), placed on a boom away from the spacecraft, will be one of the most critical instruments in the payload. With the exception of composition analysis and particle detection, magnetometers are capable of answering many questions related to the nature of the heliosphere, VLISM, and interactions between the two. While both vector helium magnetometers and fluxgate magnetometers have heritage, due to the lengthy duration of this mission fluxgates may provide a more reliable instrument.Another set of critical instruments will be a particle suite that covers a wide range of energies. Particle sensors will play a key role in learning more about our heliosphere and VLISM, providing insight into everything but the neutral hydrogen wall. The suite would most likely include four sensors. First, a plasma system (PLS) would detect thermal ions and electrons up through light pick-up ions (PUI) with energies in the 10s-10000s eV. Detecting energetic ions, electrons, inner source PUIs, and PUI in the ISM would require an energetic particle system and dedicated pick-up ion instrument (EPS and PUI) for particles with energies 10s-1000s keV. A cosmic ray system (CRS) would account for the highest energy particles, observing anomalous cosmic rays (ACRs) and galactic cosmic rays (GCRs) with energies most likely ranging from 1-1000 MeV. Each of these systems would need as close to full coverage of the sky as possible, most likely achieved through angular coverage provided by a spinning spacecraft.The final particle and field sensor that might be included on such a mission is a plasma wave instrument (PWI). This would support measurements made by the magnetometers and particle suite, enabling a better understanding of the size and shape of the heliosphere, particle acceleration in shock regions and the heliosheath, the structure and nature of the heliopause, and properties of the VLISM and GCR spectra outside the heliopause. While the measurements would most likely be made with four components spaced 90° from each other, all perpendicular to ram direction, determining the length and type of antenna used for this instrument is a trade between plasma wave science, guidance navigation and control capabilities, and mission operations.Another critical sensor suite would involve energetic neutral atom (ENA) imagers, where the suite might include one or more imagers designed to image at different energy levels (the low energy ENA-L at 10-2000 eV, medium energy ENA-M at 0.5-15 keV, and high energy ENA-H at 1-100 keV). ENA imagers would result in a better understanding of the force balance and ENA ribbon, as well as solar/heliosphere/VLISM interaction and influence on each other. In particular, an ENA-H that has the capability to point back at our heliosphere once we are well into the VLISM would allow scientists to gain insight into what our astrosphere looks like from the outside. While the two lower energy ENA imagers would only require noseward hemisphere angular coverage, in order to perform the study of the heliosphere from the outside the ENA-H would need full sky coverage with a sun exclusion zone.A neutral mass spectrometer (NMS) would provide key compositional insight during the mission by measuring neutral gas and dust in the VLISM, as well as the neutral hydrogen wall and neutral ISM gas and dust inside the heliosphere. Direct measurements of elemental and isotopic gas compositions of the VLISM would place an important constraint on models of stellar nucleosynthesis which holds implications for the formation of matter in the galaxy. This would enable a much better understanding of the properties and potential history of the ISM as a whole. The instrument would be placed facing the ram direction. Co-boresighted to perform complementary measurements to the NMS would be an Interstellar Dust Analyzer (IDA), which would further establish properties of the VLISM and how it affects our heliosphere. It would also provide important insight into the formation of planetary systems through the examination of interplanetary dust.There are additional choices that could augment these core instruments, including a Lyman-alpha spectrograph (LYA) to provide vital information about interplanetary and VLISM hydrogen phasespace density, imaging spectrometers in the ultraviolet/visible/infrared (UVS/VIR) to study planet formation in the solar system by examining the debris disk and potential nearby Kuiper Belt objects and dwarf planets, and a visIR spectral mapper (IRM) to observe the diffuse red-shifted light emitted by the universe beyond the dominant Zodiacal cloud foreground that obfuscates such studies when performed within our heliosphere.Taking the science objectives into account along with size, mass, and power constraints, two example payloads were developed for the Interstellar Probe concept study: one baseline payload which focuses on heliophysics objectives and an augmentation payload which accommodates a visNIR imager and the visIR mapper for performing a dwarf planet flyby and studying the extragalactic background light in addition to core heliophysics instrumentation. This presentation provides an overview of these example payloads, their accommodation on the spacecraft, and reliability issues associated with requiring up to 50 years of functionality.

Tests and calibrations described in E. E. Kading [] and the extraction of quantitative results from the experiment reported therein are considered unreliable. Published by the American Physical Society 2024

During its evolution, the Sun and its protective magnetic bubble – the heliosphere - has completed nearly twenty revolutions around the Galactic Core. During this “Solar Journey” it has plowed through widely different interstellar environments that have all shaped the system we live in today. The orders-of-magnitude differences in interstellar properties have had dramatic consequences for the penetration of interstellar material and have affected elemental and isotopic abundances, atmospheric evolution and perhaps even conditions for habitability. As far as we know, only some 60, 000 years ago, the Sun entered what we call the Local Interstellar Cloud (LIC), and in less than 1,900 years the Sun will be entering a very different interstellar environment that will continue to shape its evolution and fate.The Interstellar Probe is a pragmatic mission with a possible launch already in the next decade that would explore the heliospheric boundary and how it interacts with the Very Local Interstellar Medium (VLISM) to understand the current state along this Solar Journey and, ultimately understand where our home came from, and where we are going. During its 50-year nominal design life, it would go far beyond where the Voyager missions have gone, out to about 400 astronomical units (au) and likely survive out to 1000 au. Therefore, the Interstellar Probe mission would represent humanity’s first explicit step in to the galaxy and become NASA's boldest step in space exploration.When the Voyager missions traversed the heliospheric boundary with their very limited payload it became clear that we are faced with a whole new regime of space physics that is not only decisive for our own heliosphere, but also for understanding the physics of other astrospheres as well. Today we still do not understand the force that is upholding the magnetic shell (the heliosheath) around our heliosphere, or the mechanisms that shield the solar system from galactic cosmic rays, and many other mysteries. Once beyond where the furthest Voyager spacecraft will cease operations (likely at ~170 au), Interstellar Probe would step in to the unknown, traverse the hydrogen wall and the complex magnetic topology at the very edge of the Sun’s sphere of influence, and then directly sample for the first time the interstellar material that has made all of us. There, measurements of the unperturbed gas, plasma, and fields would allow accurate determination of the current state of the LIC and how it affects the global heliosphere. Measurements of unshielded interstellar dust and galactic cosmic rays would provide unprecedented information on stellar and galactic evolution. The physical processes that occur as the solar wind and magnetic field interact with VLISM would also provide the only directly measurable prototypes for understanding the astrospheres surrounding other stars that control the atmospheres and habitability of their exoplanets. All this newly acquired knowledge would then enable an understanding of the current state of the heliosphere and the VLISM, and how they interact, which ultimately can be used to extrapolate the understanding of our system back to the past and into the future.At the same time, the outward trajectory is a natural opportunity for exploring one of the ~4,000 Kuiper Belt Objects or ~130 dwarf planets similar to and beyond Pluto and determine the large-scale structure of the circum-solar dust disk to provide the ground truth for planetary system formation in general. Once beyond the obscuring dust, the infrared sky would open a window to early galaxy formation.An Interstellar Probe has been discussed and studied since 1960, but the stumbling block has always been propulsion. Now this hurdle has been overcome by the availability of new and larger launch vehicles. An international team of scientists and experts are now in the final year of a NASA-funded study led by The Johns Hopkins University Applied Physics Laboratory (APL) to develop pragmatic example mission concepts for Interstellar Probe with a nominal design lifetime of 50 years. Together with the Space Launch System (SLS) Program Office at NASA’s Marshall Space Flight Center, the team has analyzed dozens of launch configurations and demonstrated that asymptotic speeds in excess of 7.5 au per year can be achieved using existing or near-term propulsion stages with a powered or passive Jupiter Gravity Assist (JGA). These speeds are more than twice that of the fastest escaping man-made spacecraft to date, which is Voyager 1 currently at 3.59 au/year. Launching near the nose direction of the heliosphere, Interstellar Probe would therefore reach the Termination Shock (TS) in less than 12 years and cross the Heliopause into the VLISM after about 16 years from launch.In this presentation we provide an overview and update of the study, the science mission concept, the compelling discoveries that await, and the associated example science payload, measurements and operations ensuring a historic data return that would push the boundaries of space exploration by going where no one has gone before.

The NASA Space Launch System (SLS) capabilities for launching heavy payloads with high injection velocities will enable a variety of exploration missions that would not otherwise be considered. In this paper, the Interstellar Probe mission is described and an enhanced version of the NASA SLS is presented.

Oxytocin (OXT) has been frequently linked to prosocial behaviors and emotions, especially empathy. Psychopathy is a disorder characterized in part by chronic antisocial behavior and lack of empathy. Yet, there is a dearth of research examining OXT and empathy in psychopathic samples. The current meta-analysis (k = 17; n = 1151), therefore, was conducted via an extensive multi-source literature review on administered OXT and empathy in non-clinical samples, followed by a review of prior research related to the biological bases of psychopathy. We found that administered intranasal OXT has a significant, small positive effect (Cohen's d = 0.24) on empathy-related performance in non-clinical, mostly male samples. Our findings serve as cautious call for future research examining the possibility of OXT administration as treatment for psychopathic individuals although the effect may not be large and may mainly affect “cognitive empathy,” which data indicates is less impaired in psychopathic individuals compared to “emotional empathy.” Future studies should consider that OXT could exacerbate maladaptive symptoms such as aggression, but more data are needed. Future research should employ reliable and generalizable empathy measures and always examine how empathy subtypes and gender may interact differentially with OXT administration.

The thermodynamical conditions and the neutron density produced in a laser-induced implosion of a deuterium-tritium (DT) filled capsule at the National Ignition Facility (NIF) are the closest laboratory analog of stellar conditions. We plan to investigate neutron-induced reactions on 40Ar, namely the 40Ar(n, 2n)39Ar(t1/2 =268 y), the 40Ar(n, γ)41Ar(110 min) and the potential rapid two-neutron capture reaction 40Ar(2n, γ)42Ar(33 y) in an Ar-loaded DT capsule. The chemical inertness of noble gas Ar enables reliable collection of the reaction products.

Accelerator mass spectrometry (AMS) was born in the late 1970s, when it was realized at nuclear physics laboratories that the accelerator systems can be used as a sensitive mass spectrometer to measure ultralow traces of long-lived radioisotopes. It soon became possible to measure radioisotope to-stable-isotope ratios in the range from 10-12 to 10-16 by counting the radioisotope ions "atom by atom" and comparing the count rate with ion currents of stable isotopes (1.6 mu A 1/4 1 x 1013 singly charged ions/s). It turned out that electrostatic tandem accelerators are best suited for this, and there are now worldwide about 160 AMS facilities based on this principle. This review presents the history, technological developments, and research areas of AMS through the 45 yr since its discovery. Many different fields are touched by AMS measurements, including archaeology, astrophysics, atmospheric science, biology, climatology, cosmic-ray physics, environmental physics, forensic science, glaciology, geophormology, hydrology, ice core research, meteoritics, nuclear physics, oceanography, and particle physics. Since it is virtually impossible to discuss all fields in detail in this review, only specific fields with recent advances are highlighted in detail. For the others, an effort is made to provide relevant references for in-depth studies of the respective fields.

The interaction of our protective heliosphere and the Very Local Interstellar Medium (VLISM) is the least explored and most rewarding frontier of space physics.New evidence amplifies the central role of the heliosphere in the evolution of the solar system along its 4.6billion-year journey around the galaxy.In addition to the dense clouds of plasma, gas and dust seeding the early proto solar nebula, recent supernovae have left the entire solar system exposed to extreme fluxes of interstellar material and cosmic radiation with far-reaching implications.Our current knowledge lacks the direct measurements necessary to understand how our star upholds its vast heliosphere and its potentially game-changing role in the evolution of our galactic home.Interstellar Probe provides new, required measurements over more than a solar cycle to uncover the physical processes starting near the Sun responsible for creating our dynamic heliosphere.In April 2022, the pragmatic Interstellar Probe Mission Concept Study was completed after four years, detailing a Large Strategic heliophysics mission that would transect the heliosphere from 1 au to the VLISM.Its journey provides rich science for generations across heliophysics and presents an opportunity to push the frontier of space exploration farther than ever done before.Modest crossdivisional investments enable high-value planetary science and astrophysics, deepening our understanding of the emergence of our habitable planetary system.A trajectory through the forward hemisphere of the heliosphere would be accomplished by a launch in the 2036-2042 timeframe using conventional chemical propulsion and a heavy-lift launch vehicle, such as the Space Launch System (SLS).A Jupiter Gravity Assist could propel an 860-kg spacecraft with an 87-kg payload of ten instruments delivering a unified view of the global heliosphere, reaching the VLISM after 16 years.The spacecraft is designed to a 50-year nominal lifetime using modern-day technology based on successful missions like New Horizons.Two next-generation Radioisotope Thermal Generators (RTGs) would ensure 300 We at end of nominal mission at 375 au and could enable exploration even beyond 500 au.

Accelerator Mass Spectrometry (AMS) with 53Mn has geological applications as a chronometer for exposure and burial times for discontinuously deposited sediments. It has also been used to search for evidence of recent supernovae events, and proposed as a proxy to monitor the variation in the galactic cosmic ray spectrum over time. The current sensitivity limit amongst active facilities is 53Mn/55Mn = 3 x 10-13 while a sensitivity of 53Mn/55Mn = 1 x 10-13 is necessary to fully exploit 53Mn's capabilities. At the University of Notre Dame's Nuclear Science Laboratory (NSL), a 10 MV tandem accelerator and a Browne-Buechner Spectrograph operated as a gas-filled magnet were used to separate 53Mn from 53Cr. Samples covering ranges of 53Mn/55Mn = 10-10 - 10-8 were measured for the first time at the NSL using various settings resulting in a background level of 53Mn/55Mn = 6.2(3) x 10-11. Analysis of the results, descriptions of experimental settings, and further explorations will be presented in this paper.

The cross-section of the thermal neutron capture 41 Ar(n,γ) 42 Ar( t 1/2 =32.9 y) reaction was measured by irradiating a 40 Ar sample at the high-flux reactor of Institut Laue-Langevin (ILL) Grenoble, France. The signature of the two-neutron capture has been observed by measuring the growth curve and identifying the 1524.6 keV γ-lines of the shorter-lived 42 K(12.4 h) β − daughter of 42 Ar. Our preliminary value of the 41 Ar(n,γ) 42 Ar thermal cross section is 240(80) mb at 25.3 meV. For the first time, direct counting of 42 Ar was performed using the ultra-high sensitivity technique of noble gas accelerator mass spectrometry (NOGAMS) at Argonne National Laboratory, USA.

We report on experiments at the Soreq Applied Research Accelerator Facility Liquid-Lithium Target (SARAF-LiLiT) laboratory dedicated to the study of s-process neutron capture reactions. The kW-power proton beam at 1.92 MeV (1-2 mA) from SARAF Phase I yields high-intensity 30 keV quasi-Maxwellian neutrons (3-5 1010 n/s). The high neutron intensity enables Maxwellian averaged cross sections (MACS) measurements of samples with short-lived decay products. Neutron capture reactions on natSe and natCe were investigated by activation in the LiLiT neutron beam and γ-spectrometry measurements of their decay products.

The conditions of tests and calibrations described in the article E.E Kading et al. [Phys. Rev. Res. 2, 023279 (2020)] show striking flaws. The interpretation and extraction of quantitative results from this experiment are considered unreliable. All results of cross sections based on the results described in this article must be disregarded.

As the scope of Accelerator Mass Spectrometry (AMS) expands, there is an increased need to extend the capability of isobaric separation to the medium-heavy mass region. Existing AMS facilities are limited in their ability to separate radioactive nuclei in the A = 100-200 range of interest from their neighboring stable isobars, as such measurements require higher energies than available in most facilities. ATLAS is one of the highest energy system used for AMS based experiments and has enabled isobaric discrimination for medium to heavy nuclides, notably via the Gas-Filled Magnet technique. A preparatory experiment performed in November, 2019, successfully demonstrated isobaric separation of 92Zr-92Mo using the Argonne Gas-Filled Analyzer (AGFA) with high magnetic rigidity. Since that time, MONICA, an eight-anode ionization chamber that measures both energy loss and position with two sets of split anodes, has been developed to aid in AMS experiments at AGFA and has undergone four commissioning runs at the Nuclear Science Laboratory at the University of Notre Dame utilizing Si, Fe/Ni, and Mn beams. This report presents the AGFA AMS run (November 2019) and the subsequent commissioning runs of the MONICA detector, including preliminary measurements on the long-lived isotopes 39Ar (268 y) and for the first time on 42Ar (33 y).

Franz Käppeler and collaborators showed in the 1980’s that the ^7 Li( p , n ) ^7 Be reaction can be used to produce a flux of neutrons having a stellar-like energy distribution, closely similar to that contributing to the slow ( s ) neutron capture process in massive stars. The Liquid-Lithium Target (LiLiT) at Phase I of the Soreq Applied Research Accelerator Facility (SARAF) was designed following the same physical principle. Owing to the high proton beam intensity of SARAF and the power dissipation of LiLiT, the facility provided a neutron intensity more than one order of magnitude higher than available with conventional solid Li targets. We review here our first collaboration with Franz Käppeler and his group, the LiLiT design and nuclear astrophysics research accomplished in recent years at the SARAF-LiLiT facility. An outlook to the research program with SARAF Phase II, currently in construction, is presented.