In a recent paper by Kutschera et al. a weighted mean value for the half-life of 60Fe has been given with (2.60 +/- 0.05) Ma. Since this value cannot be understood from the available literature, one has to consider modifications in the Paul-Scherrer-Institute/Technical University of Munich (PSI-TUM) value. For this measurement the PSI group has later on published a number of decaying nuclei with a larger error. Here we give an updated value for the measured 60Fe activity. This leads to a PSI-TUM value of (2.61 +/- 0.05) Ma, which in turn results in a weighted average including available values from the literature which is identical to the weighted average of Kutschera et al., cited above.

In this review we describe the Accelerator Mass Spectrometry activities in Munich and some of the achievements of the past 40 years. These comprise subjects in geology, technetium distribution in the environment, dosimetry and atomic bomb survivors, input into the Solar System from close and recent supernovae, the search for primordial superheavy nuclei, the search for violations of the Pauli exclusion principle as well as the determination of the half-life of beryllium-10, a cosmogenic isotope extensively used for geology and other sciences.

The long-lived fission product technetium-99 (99Tc, t 1/2 = (2.111 ± 0.012) × 105 years) was successfully detected in small-volume (10 L, and 1 g, respectively) environmental samples such as Pacific Ocean and river water, Antarctic snow, and peat. Its presence in the environment is almost exclusively of anthropogenic origin and the determined levels are attributed to nuclear weapons testing in the 1950s and 60s as no local contamination source is known to be present at these sampling sites. A unique capability for Accelerator Mass Spectrometry (AMS) measurements of environmental 99Tc at unprecedented sensitivity was established, first using the Gas-filled Analysing Magnet System (GAMS, Germany) and after its shutdown, at the Heavy Ion Accelerator Facility (HIAF, Australia). New chemical extraction and measurement techniques, including improved non-isotopic normalisation, enabled detection limits as low as 0.6 femtograms (fg) per sample for Antarctic snow, and enhancement of precision from 30% (GAMS) to 16% (HIAF). The rather high concentrations of about 280 fg (99Tc) per g (dry mass) measured in peat indicate Tc accumulation in this archive, which opens the possibility of studying its migration behaviour even under reducing conditions. Furthermore, it allowed deduction of an improved estimate of the global 99Tc inventory to (120-190) TBq. The first direct detection of 99Tc at 8 fg L-1 in river water highlights the need for further studies in urban areas to evaluate potential contributions from nuclear medicine. The achieved sensitivity allows monitoring of on-going releases, improving the risk assessment of releases from nuclear waste repositories and tracer applications in environmental sciences.

We describe the recent experiments which claimed an observation of a tetra-neutron signal. Production reactions like transfer, knockout, fragmentation or photodisintegration have been used at very different experiments and facilities to form systems just made of neutrons. As a possible explanation of the partly contradicting results we suggest that some observed the bound ground state and some an unbound but still correlated state of the four neutrons at different exitation energy. We also refer to some of the theoretical works.

The efficiency of the weak s process in low-metallicity rotating massive stars depends strongly on the rates of the competing ^{17}O(α,n)^{20}Ne and ^{17}O(α,γ)^{21}Ne reactions that determine the potency of the ^{16}O neutron poison. Their reaction rates are poorly known in the astrophysical energy range of interest for core helium burning in massive stars because of the lack of spectroscopic information (partial widths, spin parities) for the relevant states in the compound nucleus ^{21}Ne. In this Letter, we report on the first experimental determination of the α-particle spectroscopic factors and partial widths of these states using the ^{17}O(^{7}Li,t)^{21}Ne α-transfer reaction. With these the ^{17}O(α,n)^{20}Ne and ^{17}O(α,γ)^{21}Ne reaction rates were evaluated with uncertainties reduced by a factor more than 3 with respect to previous evaluations and the present ^{17}O(α,n)^{20}Ne reaction rate is more than 20 times larger. The present (α,n)/(α,γ) rate ratio favors neutron recycling and suggests an enhancement of the weak s process in the Zr-Nd region by more than 1.5 dex in metal-poor rotating massive stars.

Radioactive nuclei with lifetimes on the order of millions of years can reveal the formation history of the Sun and active nucleosynthesis occurring at the time and place of its birth1,2. Among such nuclei whose decay signatures are found in the oldest meteorites, 205Pb is a powerful example, as it is produced exclusively by slow neutron captures (the s process), with most being synthesized in asymptotic giant branch (AGB) stars3-5. However, making accurate abundance predictions for 205Pb has so far been impossible because the weak decay rates of 205Pb and 205Tl are very uncertain at stellar temperatures6,7. To constrain these decay rates, we measured for the first time the bound-state β- decay of fully ionized 205Tl81+, an exotic decay mode that only occurs in highly charged ions. The measured half-life is 4.7 times longer than the previous theoretical estimate8 and our 10% experimental uncertainty has eliminated the main nuclear-physics limitation. With new, experimentally backed decay rates, we used AGB stellar models to calculate 205Pb yields. Propagating those yields with basic galactic chemical evolution (GCE) and comparing with the 205Pb/204Pb ratio from meteorites9-11, we determined the isolation time of solar material inside its parent molecular cloud. We find positive isolation times that are consistent with the other s-process short-lived radioactive nuclei found in the early Solar System. Our results reaffirm the site of the Sun's birth as a long-lived, giant molecular cloud and support the use of the 205Pb-205Tl decay system as a chronometer in the early Solar System.

Stable Tl205 ions have the lowest known energy threshold for capturing electron neutrinos (νe) of Eνe≥50.6 keV. The Lorandite Experiment (LOREX), proposed in the 1980s, aims at obtaining the longtime averaged solar neutrino flux by utilizing natural deposits of Tl-bearing lorandite ores. To determine the νe capture cross section, it is required to know the strength of the weak transition connecting the ground state of Tl205 and the 2.3 keV first excited state in Pb205. The only way to experimentally address this transition is to measure the bound-state beta decay (βb) of fully ionized Tl81+205 ions. After three decades of meticulous preparation, the half-life of the βb decay of Tl81+205 has been measured to be 291−27+33 days using the Experimental Storage Ring (ESR) at GSI, Darmstadt. The longer measured half-life compared to theoretical estimates reduces the expected signal-to-noise ratio in the LOREX, thus challenging its feasibility. Published by the American Physical Society 2024

Stable ^{205}Tl ions have the lowest known energy threshold for capturing electron neutrinos (ν_{e}) of E_{ν_{e}}≥50.6  keV. The Lorandite Experiment (LOREX), proposed in the 1980s, aims at obtaining the longtime averaged solar neutrino flux by utilizing natural deposits of Tl-bearing lorandite ores. To determine the ν_{e} capture cross section, it is required to know the strength of the weak transition connecting the ground state of ^{205}Tl and the 2.3 keV first excited state in ^{205}Pb. The only way to experimentally address this transition is to measure the bound-state beta decay (β_{b}) of fully ionized ^{205}Tl^{81+} ions. After three decades of meticulous preparation, the half-life of the β_{b} decay of ^{205}Tl^{81+} has been measured to be 291_{-27}^{+33}  days using the Experimental Storage Ring (ESR) at GSI, Darmstadt. The longer measured half-life compared to theoretical estimates reduces the expected signal-to-noise ratio in the LOREX, thus challenging its feasibility.

A study of the N = 81 odd-odd nucleus 140Pr with the 142Nd(d, alpha) reaction at 18-MeV incident energy is presented. A distorted-wave Born approximation analysis of measured angular distributions has been performed for 23 excited states up to Ex = 1.35 MeV, yielding information on the spin, parity, and sometimes on the simple proton-neutron structure of these states. The observed structure is discussed in comparison with that of other N = 81 isotones, from 136Cs to 144Eu, and with shell-odel calculations.

Isospin symmetry is used to fit the precisely known Q_EC -values of lighter T_Z=0,-1 and T_Z=-1/2 β -emitters and to extrapolate them up to Z=50 . For the T=1 emitters the half-lives of the pure 0^+→ 0^+ Fermi decays are calculated and compared with experimentally known values, even for the heaviest cases where the experimental uncertainties are still rather large. For the T = 1/2 emitters only the Fermi component of the transitions can be predicted, but with the experimental half-lives the ratio of Gamow–Teller to Fermi strength can be determined.

The efficiency of the weak $s$ process in low-metallicity rotating massive stars depends strongly on the rates of the competing $^{17}\mathrm{O}(\ensuremath{\alpha},n)^{20}\mathrm{Ne}$ and $^{17}\mathrm{O}(\ensuremath{\alpha},\ensuremath{\gamma})^{21}\mathrm{Ne}$ reactions that determine the potency of the $^{16}\mathrm{O}$ neutron poison. Their reaction rates are poorly known in the astrophysical energy range of interest for core helium burning in massive stars because of the lack of spectroscopic information (partial widths, spin parities) for the relevant states in the compound nucleus $^{21}\mathrm{Ne}$. In this Letter, we report on the first experimental determination of the $\ensuremath{\alpha}$-particle spectroscopic factors and partial widths of these states using the $^{17}\mathrm{O}(^{7}\mathrm{Li},t)^{21}\mathrm{Ne}$ $\ensuremath{\alpha}$-transfer reaction. With these the $^{17}\mathrm{O}(\ensuremath{\alpha},n)^{20}\mathrm{Ne}$ and $^{17}\mathrm{O}(\ensuremath{\alpha},\ensuremath{\gamma})^{21}\mathrm{Ne}$ reaction rates were evaluated with uncertainties reduced by a factor more than 3 with respect to previous evaluations and the present $^{17}\mathrm{O}(\ensuremath{\alpha},n)^{20}\mathrm{Ne}$ reaction rate is more than 20 times larger. The present $(\ensuremath{\alpha},n)/(\ensuremath{\alpha},\ensuremath{\gamma})$ rate ratio favors neutron recycling and suggests an enhancement of the weak $s$ process in the Zr-Nd region by more than 1.5 dex in metal-poor rotating massive stars.

Background: Globular clusters show strong correlations between different elements, such as the well-known sodium-oxygen anticorrelation. One of the main sources of uncertainty in this anticorrelation is the $^{22}$Ne($p,\gamma$)$^{23}$Na reaction rate, due to the possible influence of an unobserved resonance state at $E_\mathrm{x} = 8862$ keV ($E_\mathrm{r, c.m.} = 68$ keV). The influence of two higher-lying resonance states at $E_\mathrm{x} = 8894$ and $9000$ keV has already been ruled out by direct $^{22}$Ne($p,\gamma$)$^{23}$Na measurementsPurpose: To study excited states in $^{23}$Na above the proton threshold to determine if the unconfirmed resonance states in $^{23}$Na exist. Methods: The non-selective proton inelastic scattering reaction at low energies was used to search for excited states in $^{23}$Na above the proton threshold. Protons scattered from various targets were momentum-analysed in the Q3D magnetic spectrograph at the Maier-Leibnitz Laboratorium, Munich, Germany. Results: The resonance states previously reported at $E_\mathrm{x} = 8862$, $8894$ and $9000$ keV in other experiments were not observed in the present experiment at any angle. This result, combined with other non-observations of these resonance states in most other experiments, results in a strong presumption against the existence of these resonance states. Conclusions: The previously reported resonance states at $E_\mathrm{x} = 8862$, $8894$ and $9000$ keV are unlikely to exist and should be omitted from future evaluations of the $^{22}$Ne($p,\gamma$)$^{23}$Na reaction rates. Indirect studies using low-energy proton inelastic scattering are a simple and yet exceptionally powerful tool in helping to constrain astrophysical reaction rates by providing non-selective information of the excited states of nuclei.

Background: Globular clusters show strong correlations between different elements, such as the well-known sodium-oxygen anticorrelation. One of the main sources of uncertainty in this anticorrelation is the 22Ne(p, gamma) 23Na reaction rate, due to the possible influence of an unobserved resonance state at Ex = 8862 keV (Er,c.m. = 68 keV). The influence of two higher-lying resonance states at Ex = 8894 and 9000 keV has already been ruled out by direct 22Ne(p, gamma) 23Na measurements.Purpose: The purpose of this paper is to study excited states in 23Na above the proton threshold to determine if the unconfirmed resonance states in 23Na exist.Methods: The nonselective proton inelastic-scattering reaction at low energies was used to search for excited states in 23Na above the proton threshold. Protons scattered from various targets were momentum-analyzed in the Q3D magnetic spectrograph at the Maier-Leibnitz Laboratorium, Munich, Germany.Results: The resonance states previously reported at Ex = 8862, 8894, and 9000 keV in other experiments were not observed in the present experiment at any angle. This result, combined with other nonobservations of these resonance states in most other experiments, results in a strong presumption against the existence of these resonance states.Conclusions: The previously reported resonance states at Ex = 8862, 8894, and 9000 keV are unlikely to exist and should be omitted from future evaluations of the 22Ne(p, gamma) 23Na reaction rates. Indirect studies using low-energy proton inelastic scattering are a simple and yet exceptionally powerful tool in helping to constrain astrophysical reaction rates by providing nonselective information of the excited states of nuclei.

Globular clusters contain multiple stellar populations, with some previous generation of stars polluting the current stars with heavier elements. Understanding the history of globular clusters is helpful in understanding how galaxies merged and evolved and therefore constraining the site or sites of this historic pollution is a priority. The acceptable temperature and density conditions of these polluting sites depend on critical reaction rates. In this paper, three experimental studies helping to constrain astrophysically important reaction rates are briefly discussed.

Background: Globular clusters show strong correlations between different elements, such as the well-known sodium-oxygen anticorrelation. One of the main sources of uncertainty in this anticorrelation is the $^{22}\mathrm{Ne}(p,\ensuremath{\gamma})^{23}\mathrm{Na}$ reaction rate, due to the possible influence of an unobserved resonance state at ${E}_{x}=8862$ keV (${E}_{\mathrm{r},\mathrm{c}.\mathrm{m}.}=68$ keV). The influence of two higher-lying resonance states at ${E}_{x}=8894$ and 9000 keV has already been ruled out by direct $^{22}\mathrm{Ne}(p,\ensuremath{\gamma})^{23}\mathrm{Na}$ measurements.Purpose: The purpose of this paper is to study excited states in $^{23}\mathrm{Na}$ above the proton threshold to determine if the unconfirmed resonance states in $^{23}\mathrm{Na}$ exist.Methods: The nonselective proton inelastic-scattering reaction at low energies was used to search for excited states in $^{23}\mathrm{Na}$ above the proton threshold. Protons scattered from various targets were momentum-analyzed in the Q3D magnetic spectrograph at the Maier-Leibnitz Laboratorium, Munich, Germany.Results: The resonance states previously reported at ${E}_{x}=8862$, 8894, and 9000 keV in other experiments were not observed in the present experiment at any angle. This result, combined with other nonobservations of these resonance states in most other experiments, results in a strong presumption against the existence of these resonance states.Conclusions: The previously reported resonance states at ${E}_{x}=8862$, 8894, and 9000 keV are unlikely to exist and should be omitted from future evaluations of the $^{22}\mathrm{Ne}(p,\ensuremath{\gamma})^{23}\mathrm{Na}$ reaction rates. Indirect studies using low-energy proton inelastic scattering are a simple and yet exceptionally powerful tool in helping to constrain astrophysical reaction rates by providing nonselective information of the excited states of nuclei.

We used the ^{138}Ba(d,α) reaction to carry out an in-depth study of states in ^{136}Cs, up to around 2.5 MeV. In this Letter, we place emphasis on hitherto unobserved states below the first 1^{+} level, which are important in the context of solar neutrino and fermionic dark matter (FDM) detection in large-scale xenon-based experiments. We identify for the first time candidate metastable states in ^{136}Cs, which would allow a real-time detection of solar neutrino and FDM events in xenon detectors, with high background suppression. Our results are also compared with shell-model calculations performed with three Hamiltonians that were previously used to evaluate the nuclear matrix element (NME) for ^{136}Xe neutrinoless double beta decay. We find that one of these Hamiltonians, which also systematically underestimates the NME compared with the others, dramatically fails to describe the observed low-energy ^{136}Cs spectrum, while the other two show reasonably good agreement.

In this article we try to summarize all information, gathered in the last three decades, on short-lived (order of Myr) radionuclides found in the Solar System with interstellar origin, most probably due to stellar processes like supernovae. The most important isotope is ^60 Fe, but we discuss also information on ^26 Al, ^244 Pu and ^53 Mn. We describe the environment of the Solar System during the past ≈ 10 Myr as well as the likely locations where the supernovae occured. Confirming evidence has been found in the composition and energy distribution of galactic cosmic rays. Finally, we discuss the effects that the recent supernova activity might have had on Earth’s climate and biosphere.

More than 200 states up to 4.1 MeV excitation have been populated in 168Er with the 170Er(p, t) reaction at 25 MeV incident energy. About 80 of these states, with 0+ and 2+ assignments, were reported in a previous publication [D. Bucurescu et al., Phys. Rev. C 73, 064309 (2006)]. The present work considerably enriches the knowledge of this nucleus. A multistep coupled-channels analysis of the angular distributions is now presented for all the states observed in this experiment. Spin and parity values between 0+ and 7- are newly assigned for more than 100 states. For the states already reported in the ENSDF database with J & pi; values there is a good agreement with our values. The 168Er nucleus remains one of the best experimentally known nuclei for states with low and medium spins below 4 MeV excitation energy, representing a challenge for future microscopic structure model calculations aiming to disentangle the contributions of different excitation degrees of freedom.

Investigations of neutron-rich nuclei, particularly those that lie in regions of the nuclear chart known for a high probability of isomeric states forming, are of vital importance to the understanding of nuclear astrophysical processes. Studies of these nuclei, such as 190 Re, can be used to validate and improve theoretical models of such processes. A polarised-beam experiment has been performed using the Munich Q3D magnetic spectrograph in order to investigate the energy-level structure of 190 Re. An excitation-energy spectrum has been produced, allowing for energies to be assigned to observed states. Through comparison between measured and calculated differential cross-sections and vector analysing powers, the process of assigning spin and parity to newly observed states, and confirming the assignments for previously observed states, is underway.