Introduction: The Blaubeuren meteorite was discovered in 1989 in southern Germany by a homeowner digging a cable trench in his garden, though it remained unrecognized as a meteorite until 2020. It is an H4-5 ordinary chondrite breccia weighing over 30 kg and the largest recovered stony meteorite in Germany [1]. 14C-10Be dating revealed a terrestrial age of 9.2 ± 0.3 ka. Repeated search campaigns by private meteorite hunters led to a newly recognized specimen in a forest close to the city of Schelklingen, ~3 km from the find location of the Blaubeuren meteorite.Figure 1: Cut face of the new specimen. The metal grains are remarkably unweathered.Results: To verify a potential relationship to Blaubeuren, the new specimen has been studied using various techniques (optical and electron microscopy, bulk chemical, radionuclide [14C, 26Al, 41Ca] and noble gas analyses). It is an only moderately weathered single stone with a mass of ~17 g showing remnants of weathered fusion crust. Its O isotopic composition places it in the field of H chondrites. Petrographic study shows a rock with chondrules and chondrule relics (Figure 2) and an only slightly weathered interior (W1/2) [2]. The rock is unbrecciated at the thin section scale. Olivine grains show mosaicism indicating a shock degree of C-S4 [3]. The mean composition of olivine is Fa18.4±0.3 and the low-Ca pyroxenes have a mean composition of Fs16.1±0.3. The terrestrial age of the specimen has been determined by 14C-dating and found to be 9.4±1.3 ka. Preliminary noble gas data give gas retention ages of ~3.1 Ga and ~3.7 Ga for 4He and 40Ar, respectively, and cosmogenic 3He, 21Ne, and 38Ar concentrations 2–4× lower than measured for Blaubeuren. Cosmogenic radionuclides (26Al/27Al and 41Ca/40Ca) of the Schelklingen specimen are comparable to those of Blaubeuren [1] pointing to similar recent exposure conditions.Figure 2: (a) Cross-polarized photograph of an area in the new specimen from close to Schelklingen with a chondrule and more metamorphosed material. (b) Cross-polarized photograph of an area in the Blaubeuren meteorite showing various types of chondrules and relics thereof.Discussion: A comparison of the newly found specimen found close to Schelklingen with Blaubeuren shows a very similar mineralogy. Major differences compared to the Blaubeuren meteorite are that the newly found specimen shows (1) a significantly lower degree of terrestrial weathering, (2) a higher shock degree (C-S4 versus C-S2 for Blaubeuren), and (3) lower cosmogenic noble gas concentrations. The significantly fresher appearance of the new specimen may be attributed to different alteration conditions on the different locations (forest slope vs. soil inside a valley for Blaubeuren). This could have resulted in lower soil moisture and therefore favorable preservation of the Schelklingen specimen as the type and extent of terrestrial alteration depends on various aspects [4]. Differences in the shock degree can easily be explained by heterogeneity at the sample size studied because shock effects can vary from clast to clast at the cm-scale [5]. Thus, C-S4 shocked clasts may well be present elsewhere in the main mass of Blaubeuren. The differences in the cosmogenic noble gas concentrations of Blaubeuren and the new specimen may indicate they originated from strongly different depths within a large meteoroid (i.e., >120 cm radius). This, however, is not consistent with the similar cosmogenic radionuclide data obtained for both meteorites. Instead, this could suggest a more complex exposure history, (1) either on the parent body with Blaubeuren having experienced pre-exposure close to the surface or (2) that the meteoroid was a rubble pile consisting of individual fragments that experienced individual exposure histories. We consider it extremely unlikely that Blaubeuren and the new Schelklingen specimen originate from different meteoroids, which impacted Earth roughly at the same time and same place: Although. H ordinary chondrites represent the second most abundant class of meteorite falls [6,7], finding two meteorites from separate fall events within ~3 km seems statistically not favorable.Conclusion: The new Schelklingen specimen and the Blaubeuren meteorite may be part of the same strewn field and therefore of the same meteoroid with a complex exposure history impacting Earth about 9 ka ago. Their differences in the shock degree and weathering may be explained by sample heterogeneity (as typical for breccias) at the cm-scale and different alteration conditions during the ~9 ka of terrestrial weathering.References: [1] Bischoff, A. et al. (2022) Meteoritics & Planetary Science 57:136-153. [2] Wlotzka, F. (1993). A weathering scale for the ordinary chondrites. Meteoritics, vol. 28, no. 3, volume 28, page 460-460, 28. [3] Stöffler, D., Hamann, C., & Metzler, K. (2018). Shock metamorphism of planetary silicate rocks and sediments: Proposal for an updated classification system. Meteoritics & Planetary Science, 53(1), 5-49. [4] Bland, P. A., et al. (2006). Meteorites and the early solar system II, 1, 853-867. [5] Sharp, T. G., & DeCarli, P. S. (2006). Meteorites and the early solar system II, 943, 653-677. [6] Kouvatsis, I., & Hofmann, B. A. (2020). Meteoritics & Planetary Science, 55(1), 67-76. [7] The Meteorite Bulletin Database, 2026; https://www.lpi.usra.edu/meteor/

Elmshorn fell April 25, 2023, about 30 km northwest of the city of Hamburg (Germany). Shortly after the fall, 21 pieces were recovered totaling a mass of 4277 g. Elmshorn is a polymict and anomalous H3-6 chondritic, fragmental breccia. The rock is a mixture of typical H chondrite lithologies and clasts of intermediate H/L (or L, based on magnetic properties) chondrite origin. In some of the 21 pieces, the H chondrite lithologies dominate, while in others the H/L (or L) chondrite components are prevalent. The H/L chondrite assignment of these components is based on the mean composition of their olivines in equilibrated type 4 fragments (similar to Fa(21-22)). The physical properties like density (3.34 g cm(-3)) and magnetic susceptibility (log chi <5.0, with chi in 10(-9) m(3) kg(-1)) are typical for L chondrites, which is inconsistent with the oxygen isotope compositions: all eight O isotope analyses from two different fragments clearly fall into the H chondrite field. Thus, the fragments found in the strewn field vary in mineralogy, mineral chemistry, and physical properties but not in O isotope characteristics. The sample most intensively studied belongs to the stones dominated by H chondrite lithologies. The chemical composition and nucleosynthetic Cr and Ti isotope data are typical for ordinary chondrites. The noble gases in Elmshorn represent a mixture between cosmogenic, radiogenic, and primordially trapped noble gases, while a solar wind component can be excluded. Because the chondritic rock of Elmshorn contains (a) H chondrite parent body interior materials (of types 5 and 6), (b) chondrite parent body near-surface materials (of types 3 and 4), (c) fragments of an H/L chondrite (dominant in many stones), (d) shock-darkened fragments, and (e) clasts of various types of impact melts but no solar wind-implanted noble gases, the different components cannot have been part of a parent body regolith. The most straightforward explanation is that the fragmental breccia of Elmshorn represents a reaccreted rock after a catastrophic collision between an H chondrite parent body and another body with H/L (or L) chondrite characteristics but with deviating O isotope values (i.e. that of H chondrites), complete disruption of the bodies, mixing, and reassembly. This is the only straightforward way that the implantation of solar wind gases could have been avoided in this kind of complex breccia. The gas retention ages of about 2.8 Gyr possibly indicate the closure time after the catastrophic collision between H and H/L (or L) chondrite parent bodies, while the cosmic ray exposure age for Elmshorn, which had a preatmospheric radius of 25-40 cm, is similar to 17-20 Myr.

In 1889 the German poet and novelist Theodor Fontane wrote the popular literary ballad "Herr von Ribbeck auf Ribbeck im Havelland." The Squire von Ribbeck is described as a gentle and generous person, who often gives away pears from his pear trees to children passing by and continued donating pears after his death. Now, 135 years later the rock called Ribbeck is giving us insight into processes that happened 4.5 billion years ago. The meteorite Ribbeck (official find location: 52 degrees 37 ' 15 '' N, 12 degrees 45 ' 40 '' E) fell January 21, 2024, and has been classified as a brecciated aubrite. This meteoroid actually entered the Earth's atmosphere at 00:32:38 UTC over Brandenburg, west of Berlin, and the corresponding fireball was recorded by professional all sky and video cameras. More than 200 pieces (two proved by radionuclide analysis to belong to this fresh fall) were recovered totaling about 1.8 kg. Long-lived radionuclide and noble gas data are consistent with long cosmic ray exposure (55-62 Ma) and a preatmospheric radius of Ribbeck between 20 and 30 cm. The heavily brecciated aubrite consists of major (76 +/- 3 vol%) coarse-grained FeO-free enstatite (En99.1Fs<0.04Wo0.9), with a significant abundance (15.0 +/- 2.5 vol%) of albitic plagioclase (Ab95.3 An2.0Or2.7), minor forsterite (5.5 +/- 1.5 vol%; Fo99.9) and 3.5 +/- 1.0 vol% of opaque phases (mainly sulfides and metals) with traces of nearly FeO-free diopside (En53.2Wo46.8) and K-feldspar (Ab4.6Or95.4). The rock has a shock degree of S3 (U-S3), and terrestrial weathering has affected metals and sulfides, resulting in the brownish appearance of rock pieces and the partial destruction of certain sulfides already within days after the fall. The bulk chemical data confirm the feldspar-bearing aubritic composition. Ribbeck is closely related to the aubrite Bishopville. Ribbeck does not contain solar wind implanted gases and is a fragmental breccia. Concerning the Ti- and O-isotope compositions, the data are similar to those of other aubrites. They are also similar to E chondrites and fall close to the data point for the bulk silicate Earth (BSE). Before the Ribbeck meteoroid entered Earth's atmosphere, it was observed in space as asteroid 2024 BX1. The aphelion distance of 2024 BX1's orbit lies in the innermost region of the asteroid belt, which is populated by the Hungaria family of minor planets characterized by their E/X-type taxonomy and considered as the likely source of aubrites. The spectral comparison of an average large-scale emission spectrum of Mercury converted into reflectance and of the Ribbeck meteorite spectrum does not show any meaningful similarities.

The occurrence of enhanced concentration of the radium triplet 226Ra, 228Ra and 224Ra is a frequently observed property of highly saline anoxic deep water as used e.g. in geothermal plants. In the present study we develop a model to explain the observed activity levels in the brines. The model considers processes at the rock-fluid interface of the aquifer like alpha recoil, sorption and surface precipitation and is implemented by means of a Monte Carlo simulation.The outcomes of the simulations indicate the dominating role of fine-grained constituents of the reservoir rock, e.g. claystone with enhanced specific activities of the natural decay chains. Mass fractions of such material in the order of a few percent are sufficient to result in radium fluid concentrations >1 Bq l−1.Also a generally valid relation between the Th/U ratio in the aquifer rock and the 228Ra/226Ra activity ratio in the fluid was found. This link improves the agreement between radium fluid data and the mean Th/U ratio of the Earth's crust.The 224Ra/228Ra fluid ratios reflect the transport time from the location of last radium release to the sampling point.The model findings were applied to a well investigated aquifer used in a geothermal plant in the North German Basin. An eight component system of the aquifer rock was established as the basis for the simulation of the radium concentrations in the deep fluid. The comparison between simulation and fluid analyses revealed a degree of radium sorption of about 50 %, which is necessary to match the model's results with the measurements. On the other hand, the 228Ra/226Ra fluid ratio of the brine was well reproduced by the simulation, showing the suitability of the model even in complex heterogeneous reservoirs. From the 224Ra/228Ra fluid ratios a transition from pore-to fracture-guided transport < 10 m distance from the production well is suggested.Precipitates from such deep fluids occurring after changes of the thermodynamic conditions are able to accumulate radium isotopes in Ba/Sr-sulphate phases. The time dependence of the radioactive disequilibrium between 226Ra, 228Ra and its child 228Th in such scales is described by a mathematical model and is applied to two different uptake models. Based on this approach, age determinations on precipitates found in different components of a geothermal plant are conducted. They reveal the triggering of scale formation due to modifications in the plant. The results are suitable for drawing conclusions about the operation of the system, which result in a reduction in the amount of scale and a reduction in downtimes.

The occurrence of enhanced concentration of the radium triplet Ra-226, Ra-228 and Ra-224 is a frequently observed property of highly saline anoxic deep water as used e.g. in geothermal plants. In the present study we develop a model to explain the observed activity levels in the brines. The model considers processes at the rock-fluid interface of the aquifer like alpha recoil, sorption and surface precipitation and is implemented by means of a Monte Carlo simulation. The outcomes of the simulations indicate the dominating role of fine-grained constituents of the reservoir rock, e.g. claystone with enhanced specific activities of the natural decay chains. Mass fractions of such material in the order of a few percent are sufficient to result in radium fluid concentrations >1 Bq l(-1). Also a generally valid relation between the Th/U ratio in the aquifer rock and the Ra-228/Ra-226 activity ratio in the fluid was found. This link improves the agreement between radium fluid data and the mean Th/U ratio of the Earth's crust. The Ra-224/Ra-228 fluid ratios reflect the transport time from the location of last radium release to the sampling point. The model findings were applied to a well investigated aquifer used in a geothermal plant in the North German Basin. An eight component system of the aquifer rock was established as the basis for the simulation of the radium concentrations in the deep fluid. The comparison between simulation and fluid analyses revealed a degree of radium sorption of about 50 %, which is necessary to match the model's results with the measurements. On the other hand, the Ra-228/Ra-226 fluid ratio of the brine was well reproduced by the simulation, showing the suitability of the model even in complex heterogeneous reservoirs. From the Ra-224/Ra-228 fluid ratios a transition from pore-to fracture-guided transport < 10 m distance from the production well is suggested. Precipitates from such deep fluids occurring after changes of the thermodynamic conditions are able to accumulate radium isotopes in Ba/Sr-sulphate phases. The time dependence of the radioactive disequilibrium between Ra-226, Ra-228 and its child Th-228 in such scales is described by a mathematical model and is applied to two different uptake models. Based on this approach, age determinations on precipitates found in different components of a geothermal plant are conducted. They reveal the triggering of scale formation due to modifications in the plant. The results are suitable for drawing conclusions about the operation of the system, which result in a reduction in the amount of scale and a reduction in downtimes.

This study focusses on dose rate determination in complex settings in two drill cores from the site of Niederweningen, northern Switzerland. A crosscheck with a certified standard material and neutron activation analyses (NAA) reveals an overall good performance of high-resolution gamma spectrometry (HR-GS) when determining dose rate-relevant elements. A second focus is on average water content during burial, by comparing measured sediment moisture with water uptake capability. Furthermore, layer models are used to investigate the impact of inhomogeneous stratification on dose rate. Finally, different scenarios to correct for radioactive disequilibrium in the uranium decay chain are investigated. While most of the applied corrections appear to have only a minor to moderate effect on age calculation, the results for one core are contradictory. Possibly, some of the applied correction scenarios are not reflecting the complex natural setting sufficiently, in particular average sediment moisture during burial and the timing of radioactive disequilibrium might be incorrectly estimated. While deposition in one core can be quite securely attributed to the period 100–70 ka, assigning the sediment sequence in the other core to the time between ca. 130 ka and 90 ka remains to some extent insecure.

The Azraq oasis in the Eastern Desert of Jordan has produced considerable stone artefacts attributed to the early Palaeolithic, yet relatively few data are available regarding the chronology and palaeoenvironmental contexts of the remains. In this study, we present stratigraphic, sedimentological, and micropalaeontological analyses of the Late Acheulean site SM1 located within the former Shishan Marsh, which we combine with geochronological and sedimentological data from 13 neighbouring geological exposures to reconstruct landscape evolution at the western margin of the Shishan Marsh. We then discuss the Late Quaternary palaeolandscapes of the Greater Azraq Oasis Area over the past c. 350 ka. Our work demonstrates that the central Azraq Basin experienced three local wetting-drying cycles since the late Middle Pleistocene that would have dramatically shifted the quantity and distribution of freshwater resources , ranging from expansive wetland landscapes to desert refugia characterised by isolated spring pools—changes that would have significantly impacted the mobility decisions and settlement patterns of Palaeolithic inhabitants. Our study highlights that developing long-term records of human-environment dynamics in arid environments requires a mosaic approach to palaeoenvironmental reconstruction that is nested within a well-developed understanding of landscape evolution.

The discovery of a tusk and a rib of a straight-tusked elephant within layer 13 II-2c3 of the famous Lower Palaeolithic archaeological site Schöningen (district Helmstedt, Lower-Saxony, Germany) provided the reason for studying the climatic and ecological conditions of this part of the Middle Pleistocene Reinsdorf sequence in high resolution in relation to new chronometric data. Sediment, pollen, aquatic microfossil (diatoms, ostracods, gyrogonites of charophytes) and micro mammalian analyses provide evidence for a strong environmental change and landscape opening following the post-temperate boreal forest phase of the Reinsdorf Interglacial. Palynological and palaeontological evidence from this horizon suggest increasing dryness and seasonality. The high proportions of non-arboreal pollen including Poaceae as well as a major decrease of thermophile tree taxa indicate the development of zonal steppe environments. The assemblage of small mammal remains includes indicators of temperate as well as cold climatic conditions. A bone tool together with flint artefacts clearly show the presence of hominins in this context. Based on palaeoecological evidence and new luminescence dating, previous correlations of the Reinsdorf sequence to Marine Isotope Stage (MIS) 9 and thus of the interglacial sediments to MIS 9e are confirmed and the onset of the first post-interglacial steppe phase represented by layer 13 II-2c3 to MIS 9d is proposed.

On September 12, 2019 at 12:49:48 (UT) a bolide was observed by hundreds of eye-witnesses from the Netherlands, Germany, Belgium, Denmark and the UK. One day later a small meteorite stone was found by accident in Flensburg. The presence of short-lived cosmogenic radionuclides with half-lives as short as 16 days proves the recent exposure of the found object to cosmic rays in space linking it clearly to the bolide event. An exceptionally short exposure time of similar to 5000 years was determined. The 24.5 g stone has a fresh black fusion crust, a low density of <2 g/cm(3), and a magnetic susceptibility of log chi = 4.35 (chi in 10(-9) m(3)/kg). The rock consists of relict chondrules and clusters of sulfide and magnetite grains set in a fine-grained matrix. The most abundant phases are phyllosilicates. Carbonates (similar to 3.9 vol.%) occur as calcites, dolomites, and a Na-rich phase. The relict chondrules (often surrounded by sulfide laths) are free of anhydrous silicates and contain abundant serpentine. Lithic clasts are also surrounded by similar sulfide laths partly intergrown with carbonates. Mn-53-Cr-53 ages of carbonates in Flensburg indicate that brecciation and contemporaneous formation of the pyrrhotite-carbonate intergrowths by hydrothermal activities occurred no later than 4564.6 +/- 1.0 Ma (using the angrite D'Orbigny as the Mn-Cr age anchor). This corresponds to 2.6 +/- 1.0 or 3.4 +/- 1.0 Ma after formation of CAIs, depending on the exact absolute age of CAIs. This is the oldest dated evidence for brecciation and carbonate formation, which likely occurred during parent body growth and incipient heating due to decay of Al-26. In the three oxygen isotope diagram, Flensburg plots at the O-16-rich end of the CM chondrite field and in the transition field to CV-CK-CR chondrites. The mass-dependent Te isotopic composition of Flensburg is slightly different from mean CM chondrites and is most similar to those of the ungrouped C2 chondrite Tagish Lake. On the other hand, Ti-50 and Cr-54 isotope anomalies indicate that Flensburg is similar to CM chondrites, as do the similar to 10 wt.% H2O of the bulk material. Yet, the bulk Zn, Cu, and Pb concentrations are about 30% lower than those of mean CM chondrites. The He, Ne, and Ar isotopes of Flensburg show no solar wind contribution; its trapped noble gas signature is similar to that of CMs with a slightly lower concentration of Ne-20(tr). Based on the bulk H, C, and N elemental abundances and isotopic compositions, Flensburg is unique among chondrites, because it has the lightest bulk H and N isotopic compositions of any type 1 or 2 chondrite investigated so far. Moreover, the number of soluble organic compounds in Flensburg is even lower than that of the brecciated CI chondrite Orgueil. The extraordinary significance of Flensburg is evident from the observation that it represents the oldest chondrite sample in which the contemporaneous episodes of aqueous alteration and brecciation have been preserved. The characterization of a large variety of carbonaceous chondrites with different alteration histories is important for interpreting returned samples from the OSIRIS-REx and Hayabusa 2 missions. (C) 2020 The Authors. Published by Elsevier Ltd.

AbstractAm 2. April 2021 starb Siegfried Niese, der sich über Jahrzehnte am Forschungsstandort Rossendorf für die radiochemische Analytik eingesetzt hat.

We conducted a comprehensive radiation hazard assessment of the Tokyo Olympic Games (Tokyo 2020, postponed to 2021). Our combined experimental and literature study focused on both external and internal exposure to ionizing radiation for athletes and visitors of the Games. The effective dose for a visit of 2 weeks ranges from 57 to 310 μSv (including flight dose). The main contributors to the dose are cosmic radiation during the flights (approximately 10-81%), inhalation of natural radon (approximately 9-47%), and external exposure (approximately 8-42%). In this complex exposure, anthropogenic radionuclides from the Fukushima nuclear accident (2011) always play a minor role and have not caused a significant increase of the radiological risk compared to pre-Fukushima Japan. Significantly elevated air dose rates were not measured at any of the Tokyo Olympic venues. The average air dose rates at the Tokyo 2020 sites were below the average air dose rates at the sites of previous Olympic Games. The level of radiological safety of foods and water is very high in Japan, even for athletes with increased water and caloric demands, respectively.

On August 8, 2019, an explosion of a military missile occurred at the Nenoksa (also transcribed as Nyonoksa) Missile Test Center (Russian Federation). Russian authorities confirmed a release of radioactive material in the course of this incident, which fueled rumors that it could have involved a nuclear-propelled missile of the Burevestnik/Skyfall type. In this study, our radioanalytical efforts are summarized searching for the "smoking gun" of the incident. These included the gamma-measurements of air filters from two vessels that were in some proximity to the event as well as one Greek high-volume air filter. In addition, we tested the hypothesis that radioactive Ar-42 may have been used to operate a radiothermal generator. If the incident had released Ar-42, it may have become detectable by measuring characteristic gamma radiation emitted from a tank containing liquefied atmospheric argon. No traces whatsoever were found that could provide clues about the release. It is possible that the presumably small amounts of radionuclides released from either a small nuclear reactor or a powerful radionuclide source dispersed quickly over Russian territory to non-detectable levels before reaching any of our assayed samples.

Time-dependent changes in dose rates generally need to be considered in luminescence dating due to the dynamic character of the geosphere. Nevertheless, this aspect is rather marginally treated in the literature. The present paper describes the methodology of including temporal variations of overburden, moisture content and radionuclide activity into the calculation of dating results. Consideration of possible occurrences of variable dose rates has consequences for fieldwork procedures as well as for the choice of appropriate methods of radionuclide determination. A program code for age calculation by luminescence methods called ADELE v2017 is presented which implements several examples of temporal dose rate variations and layered structures with inhomogeneous distribution of dose rate relevant elements. The impact of variable dose rates on age data is illustrated by applying ADELE v2017 to several case studies.

. The relevant interaction energies for astrophysical radiative capture reactions are very low, much below the repulsive Coulomb barrier. This leads to low cross sections, low counting rates in γ-ray detectors, and therefore the need to perform such experiments at ion accelerators placed in underground settings, shielded from cosmic rays. Here, the feasibility of such experiments in the new shallow-underground accelerator laboratory in tunnels VIII and IX of the Felsenkeller site in Dresden, Germany, is evaluated. To this end, the no-beam background in three different types of germanium detectors, i.e. a Euroball/Miniball triple cluster and two large monolithic detectors, is measured over periods of 26–66 days. The cosmic-ray induced background is found to be reduced by a factor of 500–2400, by the combined effects of, first, the 140 meters water equivalent overburden attenuating the cosmic muon flux by a factor of 40, and second, scintillation veto detectors gating out most of the remaining muon-induced effects. The new background data are compared to spectra taken with the same detectors at the Earth’s surface and at other underground sites. Subsequently, the beam intensity from the cesium sputter ion source installed in Felsenkeller has been studied over periods of several hours. Based on the background and beam intensity data reported here, for the example of the 12 C(α,γ) 16 O reaction it is shown that highly sensitive experiments will be possible.

In this study, we report results of the analysis of a particularly interesting scaling sample from the geothermal plant in Neustadt-Glewe in northern Germany, which contained 19% Galena (PbS) and 81% of a heterogeneous assemblage of (Ba,Sr)SO 4 crystals with varying compositions, 0.15 < X Ba < 0.53. A main fraction of the sample (~56%) has a barite content of X Ba ≈ 0.32. We try to relate the solid composition of the (Ba,Sr)SO 4 solid-solution to the conditions at the geothermal plant concerning temperature, pressure, and solution composition, and discuss it with respect to the challenges in modelling the composition of (Ba,Sr)SO 4 solid-solutions on the basis of thermodynamic mixing models. We note that considerable uncertainties are related to the description of (Ba,Sr)SO 4 formation by means of thermodynamic models. The scaling composition observed in this study would be in line with endmember solubilities as predicted by the PhreeqC-Pitzer database for 70 °C and an interaction parameter, a 0 = 1.6. According to such a model, the scaling heterogeneity would reflect bimodal precipitation behaviour due to various degrees of depletion of the brine with respect to X (Ba) (aq) . Minor fluctuations in X (Ba) (aq) : 0.0017 < X (Ba) (aq) < 0.0042 explain the full range of observed solid compositions. The choice especially of the interaction parameter seems to some extent arbitrary. This knowledge gap strongly limits the interpretation of (Ba,Sr)SO 4 compositions. Thus, it is not possible to distinguish between kinetic and thermodynamic effects on partitioning or to use the solid-solution composition to draw conclusions about the precipitation conditions (e.g. Temperature).

Forty-eight samples made of CaF2, LiF and YVO4 were placed inside the KSTAR Tokamak and irradiated by neutrons and charged particles from eight plasma pulses. The aim was to provide information for plasma diagnostics. Due to the short pulse durations, the activities induced in the samples were low and therefore measurements were performed in five low-background underground laboratories. Details of the underground measurements, together with data on the quality control amongst the radiometric laboratories, are presented.

The concentration of Ra-226, Ra-228 and Ra-224 in geothermal brines is caused to a high extent by -recoil processes at the mineral/fluid interface in the aquifer. A Monte Carlo code for the prediction of the activity concentrations and the isotope ratios was developed and tested on single and multi component systems, respectively. The simulations consider the chemical behaviour of released recoil nuclei in the solution as well as the statistical character of the recoil process. Analytical data of Radium isotopes in a geothermal fluid of the North German Basin were well reproduced by this model. Highly radioactive fracture fillings in the granite of Soultz-sous-Forets could be excluded as a source of the Radium concentration in the associated brine.

The Ca-40(alpha, gamma)(44) Ti reaction is believed to be the main production channel for the radioactive nuclide Ti-44 in core-collapse supernovae. Radiation from decaying Ti-44 has been observed so far two supernova remnants, and precise knowledge of the Ti-44 production rate may help improve supernova models. The Ca-40(alpha, gamma)(44) Ti astrophysical reaction rate is determined by a number of narrow resonances. Here, the resonance triplet at E-alpha = 4497, 4510, and 4523 keV is studied both by activation, using an underground laboratory for the gamma counting, nuclear reactions. The strengths of the three resonances are determined to be omega gamma = (0.92 +/- 0.20), (6.2 +/- 0.5), and (1.32 +/- 0.24) eV, respectively, a factor of 2 more precise than before. The strengths of this resonance triplet may be used in future works as a point of reference. In addition, the present new data directly affect the astrophysical reaction rate at relatively high temperatures (above 3.5 GK).

The ${}^{40}$Ca($\ensuremath{\alpha},\ensuremath{\gamma}$)${}^{44}$Ti reaction is believed to be the main production channel for the radioactive nuclide ${}^{44}$Ti in core-collapse supernovae. Radiation from decaying ${}^{44}$Ti has been observed so far for two supernova remnants, and precise knowledge of the ${}^{44}$Ti production rate may help improve supernova models. The ${}^{40}$Ca($\ensuremath{\alpha},\ensuremath{\gamma}$)${}^{44}$Ti astrophysical reaction rate is determined by a number of narrow resonances. Here, the resonance triplet at ${E}_{\ensuremath{\alpha}}=4497$, 4510, and 4523 keV is studied both by activation, using an underground laboratory for the $\ensuremath{\gamma}$ counting, and by in-beam $\ensuremath{\gamma}$ spectrometry. The target properties are determined by elastic recoil detection analysis and by nuclear reactions. The strengths of the three resonances are determined to be $\ensuremath{\omega}\ensuremath{\gamma}=(0.92\ifmmode\pm\else\textpm\fi{}0.20)$, $(6.2\ifmmode\pm\else\textpm\fi{}0.5)$, and $(1.32\ifmmode\pm\else\textpm\fi{}0.24)$ eV, respectively, a factor of 2 more precise than before. The strengths of this resonance triplet may be used in future works as a point of reference. In addition, the present new data directly affect the astrophysical reaction rate at relatively high temperatures (above 3.5 GK).