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The hyporheic zone (HZ) is of major importance for carbon and nutrient cycling as well as for the ecological health of stream ecosystems. However, biogeochemical observations in this ecotone are complicated by a very high spatial heterogeneity and temporal dynamics. Especially the latter are difficult to observe without disturbing the system. In this field study, we tested and combined three less common methods for time-resolved measurements with high vertical resolution. We installed Rhizon samplers for repeated pore-water extraction, an optical sensor unit for in-situ measurements of dissolved oxygen, and a depth-resolved temperature monitoring system in the HZ of a small stream. While Rhizon samplers were found to be highly suitable for pore-water sampling of dissolved solutes, measured gas concentrations, here CH4, showed a strong dependency of the pump rate during sample extraction, and an isotopic shift in gas samples became evident. This was presumably caused by a different behaviour of water and gas phase in the pore-space. The manufactured oxygen-sensor could locate the oxic-anoxic interface with very high precision. This is ecologically important and allows to distinguish aerobic and anaerobic processes. Temperature data could not only be used to estimate vertical hyporheic exchange, but also depicted sedimentation and erosion processes. Overall, the combined approach was found to be a promising tool to acquire data for the quantification of biogeochemical processes in the HZ with high spatial and temporal resolution.

Thermally activated delayed fluorescent (TADF) emitters have become the leading emissive materials for highly efficient organic light-emitting diodes (OLEDs). The deposition of these materials in scalable and cost-effective ways is paramount when looking toward the future of OLED applications. Herein, a simple OLED with fully solution-processed organic layers is introduced, where the TADF emissive layer is ink-jet printed. The TADF polymer has electron and hole conductive side chains, simplifying the fabrication process by removing the need for additional host materials. The OLED has a peak emission of 502 nm and a maximum luminance of close to 9600 cd m$_{−2}$. The self-hosted TADF polymer is also demonstrated in a flexible OLED, reaching a maximum luminance of over 2000 cd m$_{−2}$. These results demonstrate the potential applications of this self-hosted TADF polymer in flexible ink-jet printed OLEDs and, therefore, for a more scalable fabrication process.

Facing the challenges of climate change, policy making relies on sound greenhouse gas (GHG) budgets. Rivers and streams emit large quantities of the potent GHG methane (CH4), but their global impact on atmospheric CH4 concentrations is highly uncertain. In situ data from the hyporheic zone (HZ), where most CH4 is produced and some of it can be oxidized to CO2, are lacking for an accurate description of CH4 production and consumption in streams. To address this, we recorded high-resolution depth-resolved geochemical profiles at five different locations in the stream bed of the river Moosach, southern Germany. Specifically, we measured pore-water concentrations and stable carbon isotopes (δ13C) of dissolved CH4 as well as relevant electron acceptors for oxidation with a 1 cm vertical depth resolution. Findings were interpreted with the help of a numerical model, and 16S rRNA gene analyses added information on the microbial community at one of the locations. Our data confirm with pore-water CH4 concentrations of up to 1000 µmol L−1 that large quantities of CH4 are produced in the HZ. Stable isotope measurements of CH4 suggest that hydrogenotrophic methanogenesis represents a dominant pathway for CH4 production in the HZ of the river Moosach, while a relatively high abundance of a novel group of methanogenic archaea, the Candidatus “Methanomethyliales” (phylum Candidatus “Verstraetearchaeota”), indicate that CH4 production through H2-dependent methylotrophic methanogenesis might also be an important CH4 source. Combined isotopic and modeling results clearly implied CH4 oxidation processes at one of the sampled locations, but due to the steep chemical gradients and the close proximity of the oxygen and nitrate reduction zones, no single electron acceptor for this process could be identified. Nevertheless, the numerical modeling results showed potential not only for aerobic CH4 oxidation but also for anaerobic oxidation of CH4 coupled to denitrification. In addition, the nitrate–methane transition zone was characterized by an increased relative abundance of microbial groups (Crenothrix, NC10) known to mediate nitrate and nitrite-dependent methane oxidation in the hyporheic zone. This study demonstrates substantial CH4 production in hyporheic sediments, a potential for aerobic and anaerobic CH4 oxidation, and underlines the high spatiotemporal variability in this habitat.

Dependent on the specific conditions flat roofs can be well suited for the installation of large photovoltaic systems in urban areas. For urban designers also other aspects, such as the insulation of buildings, cooling, air purification and water retention play an important role besides the ecological energy generation. The combination of photovoltaics and roof greening can therefore be an interesting fusion. It combines the advantages of a green roof with the local electrical energy production at the place of consumption. However, using a conventional photovoltaic system with tilted modules in south or east-west direction on a green roof causes problems, as typical low tilt angels and high ground coverage rates result in an almost complete coverage of the roof surface. Plants, growing in between the covered areas provoke undesirable shading of the collector surface. Only a frequent maintenance procedure, complicated by dense PV system layouts, can avoid a reduction of the energy yield in the course of time. Vertically mounted specially designed bifacial modules are an option to realize photovoltaic power generation in combination with a functional green roof at low maintenance costs. In this paper, we report on the layout and the energy yield of a corresponding system. Custom-made bifacial modules with 20 cells were produced and vertically installed in landscape orientation. The narrow layout of the modules lowers the wind load and reduces the visibility. The enhanced power in the morning and evening of vertically east-west installed modules can additionally lead to higher self-consumptions rates. Despite having some shading and undergrounds with albedo factors of less than 0.2, the bifacial installation with a rated power of 9.09 kWp achieved a specific yield of the 942 kWh/kWp in one year (11.08.2017–10.08.2018). This is close to typical values of 1000 kWh/kWp achieved for south-facing PV systems in the same region. The impact of the greening on the albedo and the system performance is investigated in more detail with two smaller sub-systems. The energy yields of the two bifacial sub-systems are compared to a monofacial, south-facing reference module. The use of silver-leaved plants in this system resulted in higher albedo values and a more resilient roof greening.

For bifacial module arrays three dimensional, reflective elements in between the rows might be an option in order to achieve a low light concentration resulting in a further increased energy harvest. A simulation of such conditions using the optical behavior of real reflecting foils is hardly possible; measurements at real systems would require considerable effort. In this work we present results obtained by a measuring setup with rotating mini modules. In particular the influence of the ground reflection was studied by using various grounds and reflecting elements with different shapes. Prior to the analysis of the reflector elements the measurement setup is described.

The semantic variant of primary progressive aphasia (svPPA) presents with a degradation of semantic knowledge due to atrophy of the anterior temporal lobe and is characterized by impaired confrontation naming and impaired single-word comprehension. So far, little is known about the development of symptoms and their order of occurrence in the preclinical phase, and information regarding written text production is scarce. We had the unique opportunity to analyze the diary of a man written over a time span of 12 years before he was diagnosed with svPPA. We sought to identify the earliest indicators of cognitive change in his diary entries, and to track the important changes over time. Based on transcripts of the entries (one week every six months) we assessed the overall structure, vocabulary, surface dysgraphia and semantic paraphasia, syntax, and morphology. We found changes in all domains up to seven years before the clinical diagnosis. The earliest changes concerned the vocabulary, with decreased variety and increased use of high frequency words. This was followed by syntactic and morphological errors. We found no increase of surface dysgraphia. Semantic paraphasias increased only during the last three years but characterized the entries of the last year. We were therefore able to further corroborate recent findings regarding difficulties in the morpho-syntactic domain in this patient group. In this natural context for written text production, such errors seem, in addition to changes in vocabulary, to be the first error types to appear, possibly as a result of compensating for the degradation of semantic representations.

PV systems using bifacial solar modules have shown an increased energy harvest compared to systems with standard, monofacial panels. The energy yield of bifacial installations is however also heavily dependent on the installation conditions. For free-standing bifacial modules the optimum orientation is a trade-off between the front and rear side output and the efficiency is dependent on factors such as the ground reflectance or the installation height. In extended arrays additional factors such as direct shading and reduced ground albedo due to the adjacent rows have to be considered. Because of the sensitivity on multiple additional factors, compared to monofacial standard installations, the simulation and prediction of a bifacial PV arrays yield is by far more complicated. At present there are only limited simulation tools for bifacial arrays available. Accordingly, also the determination of optimized installation conditions is considerably less straightforward for bifacial installations. Because of the pronounced dependencies also the generalization of field data from specific installations is difficult. In order to obtain more general results, and also to have a sound basis for the verification of simulation models, a systematic variation of the installation parameters is desirable, but difficult to realize in real applications. A small and flexible test array may thus be a promising approach to obtain a fast and flexible testing device, provided that the results can be correlated to measurements at real systems. In particular, the fast change of the installation parameters allows a comparative analysis at virtually unchanged lighting conditions. In this paper we report on a miniaturized test array and relate the results to corresponding values from an installation with bifacial 60 cell modules. The results are of interest with regard to the suitability of such a device as a measurement tool to predict the output and the yield of real installations with bifacial modules.

Background: In neutron-rich nuclei around $N=40$ rapid changes in nuclear structure can be observed. While $^{68}\mathrm{Ni}$ exhibits signatures of a doubly magic nucleus, experimental data along the isotopic chains in even more exotic Fe and Cr isotopes---such as excitation energies and transition strengths---suggest a sudden rise in collectivity toward $N=40$.Purpose: Reduced quadrupole transition strengths for low-lying transitions in neutron-rich $^{58,60,62}\mathrm{Cr}$ are investigated. This gives quantitative new insights into the evolution of quadrupole collectivity in the neutron-rich region close to $N=40$.Method: The recoil distance Doppler-shift (RDDS) technique was applied to measure lifetimes of low-lying states in $^{58,60,62}\mathrm{Cr}$. The experiment was carried out at the National Superconducting Cyclotron Laboratory (NSCL) with the SeGA array in a plunger configuration coupled to the S800 magnetic spectrograph. The states of interest were populated by means of one-proton knockout reactions.Results: Data reveal a rapid increase in quadrupole collectivity for $^{58,60,62}\mathrm{Cr}$ toward $N=40$ and point to stronger quadrupole deformations compared to neighboring Fe isotopes. The experimental $B(E2$) values are reproduced well with state-of-the-art shell-model calculations using the LNPS effective interaction. A consideration of intrinsic quadrupole moments and ${\mathrm{B}}_{42}$ ratios suggest an evolution toward a rotational nature of the collective structures in $^{60,62}\mathrm{Cr}$. Compared to $^{58}\mathrm{Cr}$, experimental ${\mathrm{B}}_{42}$ and ${\mathrm{B}}_{62}$ values for $^{60}\mathrm{Cr}$ are in better agreement with the $E(5)$ limit.Conclusion: Our results indicate that collective excitations in neutron-rich Cr isotopes saturate at $N=38$, which is in agreement with theoretical predictions. More detailed experimental data of excited structures and interband transitions are needed for a comprehensive understanding of quadrupole collectivity close to $N=40$. This calls for additional measurements in neutron-rich Cr and neighboring Ti and Fe nuclei.

Highly charged ions in cold confines High-energy irradiation can strip many electrons away from individual atoms, producing ions with charges of +10 or more. However, many of the interesting properties of such highly charged ions are hard to study or exploit under the extreme conditions needed to prepare them. Schmöger et al. cooled down argon ions with +13 charges from the megakelvin temperatures needed for their generation to millikelvin temperatures appropriate for high-precision spectroscopy. The method relies on sympathetic cooling by a cold sample of singly charged beryllium ions and is likely to be applicable to a broad range of other elements. Science , this issue p. 1233

Preparing highly charged ions (HCIs) in a cold and strongly localized state is of particular interest for frequency metrology and tests of possible spatial and temporal variations of the fine structure constant. Our versatile preparation technique is based on the generic modular combination of a pulsed ion source with a cryogenic linear Paul trap. Both instruments are connected by a compact beamline with deceleration and precooling properties. We present its design and commissioning experiments regarding these two functionalities. A pulsed buncher tube allows for the deceleration and longitudinal phase-space compression of the ion pulses. External injection of slow HCIs, specifically Ar13+, into the linear Paul trap and their subsequent retrapping in the absence of sympathetic cooling is demonstrated. The latter proved to be a necessary prerequisite for the multi-pass stopping of HCIs in continuously laser-cooled Be+ Coulomb crystals. © 2015 AIP Publishing LLC.

The ground state two-proton decay lifetime of Mg19, populated by the one-neutron knockout of an intermediate-energy Mg20 radioactive beam, was measured utilizing a new experimental technique. A thin silicon detector positioned at varying distances (0.0–1.0 mm) downstream of the reaction target measured the energy loss of Mg19 and the two-proton decay product Ne17. The lifetime was deduced from fits to the measured energy-loss line shapes and depended upon the contribution of prompt reaction processes to the yield of Ne17. For relative Ne17 prompt contributions from 82% to 92%, the extracted lifetimes ranged from 1.75+0.43−0.42 to 6.4+2.4−2.7 ps. The results are consistent with the previously reported Mg19 lifetime measurement and serve as both an important complementary study and a validation of this new technique, which can provide lifetime information for short-lived states beyond the proton drip line.

An error in the production process caused the incidence risk ratios in the rightmost column of Table 3 to be displayed incorrectly. Please see the corrected Table 3 here

The Electron Beam Ion Trap (EBIT) of the National Superconducting Cyclotron Laboratory at Michigan State University is used as a charge booster and injector for the currently commissioned rare isotope re-accelerator facility ReA. This EBIT charge breeder is equipped with a unique superconducting magnet configuration, a combination of a solenoid and a pair of Helmholtz coils, allowing for a direct observation of the ion cloud while maintaining the advantages of a long ion trapping region. The current density of its electron beam is a key factor for efficient capture and fast charge breeding of continuously injected, short-lived isotope beams. It depends on the radius of the magnetically compressed electron beam. This radius is measured by imaging the highly charged ion cloud trapped within the electron beam with a pinhole camera, which is sensitive to X-rays emitted by the ions with photon energies between 2 keV and 10 keV. The 80%-radius of a cylindrical 800 mA electron beam with an energy of 15 keV is determined to be r80%= (212±19)μm in a 4 T magnetic field. From this, a current density of j = (454 ± 83)A/cm2 is derived. These results are in good agreement with electron beam trajectory simulations performed with TriComp and serve as a test for future electron gun design developments. © 2014 AIP Publishing LLC.

New facades of high-rise buildings often include renewable energy converters to allow "green building" operation. At the same time, numerous tenants value visual transparency. Transparent solar thermal collectors (TSTCs) aim at decreasing the non-renewable primary energy demand and increasing the visual transparency at the same time. On the one hand, this paper presents the main modelling challenges that arise when considering building facades and especially integrated TSTC systems. New transient systems simulation (TRNSYS) [Beckman, W. A., L. Broman, A. Fiksel, S. A. Klein, E. Lindberg, M. Schuler, and J. Thornton. 1994. "TRNSYS The Most Complete Solar Energy System Modelling and Simulation Software." Renewable Energy 5 (1-4): 486-488] types have been especially developed for this purpose. A simplified model is presented for comparison purposes. On the other hand, the overall performance for a building with facade-integrated TSTC, as measured by its non-renewable prima ry energy demand, is treated. This is achieved by considering a complete simulation model coupling the TSTC, building and heating, ventilation and air conditioning operation. Possibilities for primary energy savings are investigated using the building mass as additional thermal storage.

Neutron decay spectroscopy has become a successful tool to explore nuclear properties of nuclei with the largest neutron-to-proton ratios. Resonances in nuclei located beyond the neutron dripline are accessible by kinematic reconstruction of the decay products. The development of two-neutron detection capabilities of the Modular Neutron Array (MoNA) at NSCL has opened up the possibility to search for unbound nuclei which decay by the emission of two neutrons. Specifically this exotic decay mode was observed in 16Be and 26O., To be published in Acta Physica Polonica B

Production cross sections for neutron-rich nuclei from the fragmentation of a 82Se beam at 139 MeV/u were measured. The longitudinal momentum distributions of 122 neutron-rich isotopes of elements $11 \le Z \le 32$ were determined by varying the target thickness. Production cross sections with beryllium and tungsten targets were determined for a large number of nuclei including several isotopes first observed in this work. These are the most neutron-rich nuclides of the elements $22 \le Z \le 25$ (64Ti, 67V, 69Cr, 72Mn). One event was registered consistent with 70Cr, and another one with 75Fe. A one-body Qg systematics is used to describe the production cross sections based on thermal evaporation from excited prefragments. The current results confirm those of our previous experiment with a 76Ge beam: enhanced production cross sections for neutron-rich fragments near Z=20., Talk given at the 11th International Conference on Nucleus-Nucleus Collisions (NN2012), San Antonio, Texas, USA, May 27-June 1, 2012. To appear in the NN2012 Proceedings in Journal of Physics: Conference Series (JPCS)

Electron beam ion traps (EBITs) are a new tool for charge breeding of rare isotope beams. The ionization efficiency of a new high current EBIT recently built at the MPIK was investigated spectroscopically during its commissioning phase.

A Monte Carlo simulation of a large-area neutron time-of-flight detector, built on the G eant 4 framework, has been compared with an experimental measurement of the B 16 → B 15 + n decay produced from a 55 MeV/u 17C beam. The ability of the Monte Carlo simulation to reproduce the intermediate-energy neutron interactions within the detector has been explored using both the stock G eant 4 physics processes and a custom neutron interaction model, menate _ r . The stock G eant 4 physics processes were unable to reproduce the experimental observables, while excellent agreement was obtained through the inclusion of the menate _ r model within G eant 4. The differences between the two approaches are shown to be related to the modeling of the neutron–carbon inelastic reactions. Additionally, the use of menate _ r provided accurate reproduction of experimental signals associated with neutron scattering within the detector. These results provide validation of the Monte Carlo simulation for modeling measurements of multiple neutrons where the identification and removal of false neutron signals, due to multiple neutron scattering, are required.

We compared the performance of the Meso Scale Diagnostics electrochemiluminescence (MSD) multiplex assay for t-tau and p-tau(231), originally developed for measurement of brain cell extract and tissue cultures, with the established standard method, the Innogenetics ELISA for total and p-tau(181). The methods were also clinically evaluated with 120 samples from our mono center population. The established Innogenetics ELISA procedures have been well optimized to measure patient samples in the normal and pathological range. Compared to the MSD they were superior in the limit of detection for total as well as p-tau. The obtained reference values for our normal controls were in the upper third of the published studies. Innogenetics tau, Innogenetics p-tau(181) and MSD t-tau differentiated the Alzheimer's (n=44) and minimal impairment group (MCI, n=39) from normal controls (n=37), but the MCI group was not statistically different from the normal controls. The MSD multiplex assay measured t-tau adequately but p-tau(231) could not differentiate normal from pathological results in CSF due to the high limit of detection. Both procedures however, have to be further standardized and complemented by adequate internal and external quality control schemes to qualify for routine analysis in a medical laboratory.

The combination of an acute vestibular syndrome with SD usually indicates posterior circulation ischemia [3] . In a series of 83 patients presenting with acute vestibular syndrome, SD was by far the most specific indicator of a central vestibular lesion [3] , which in the context of apoplectiform onset and vascular risk fac-tors is often ischemic in nature. SD is caused by a unilateral or asymmetric deficit of otolith organs or graviceptive pathways projecting to oculomotor and thalamic nuclei (ventral posterolat-eral nucleus) and is most often observed in the context of brain-stem or cerebellar lesions [4]. S D has also rarely been described in peripheral vestibular lesions, e.g. after vestibular neurectomy [5] . In a small case series, Safran et al. [6] reported a case with ves-tibular neuropathy and prominent vertical diplopia due to SD, but no MRI was performed. Thus, abnormalities of the central ves-tibular system may have gone undetected. In the present case, repeated MRI studies with thin sections and combined axial and coronal DWI sequences were without pathological findings after 2 and 5 days. The combination of spontaneous horizontal-torsional nys-tagmus, pathological head impulse test and pathological re-sponse to caloric stimulation suggested a unilateral peripheral vestibular loss, most probably due to vestibular neuritis. The ab-sence of auditory symptoms argues against an ischemic labyrin-thine dysfunction, which only rarely results in isolated loss of vestibular function [7] , and would be expected to be associated with DWI changes in the territory of the anterior inferior cerebel-lar artery. Vestibular disorders account for 1–6.4% of the patients pre-senting with stroke mimics in 2 large series [8, 9] . However, the occurrence of SD in this context has not been evaluated system-atically. In order to increase the sensitivity of lesion identification in the posterior fossa, high-resolution imaging with thin sections and combined axial and coronal DWI sequences as well as dy-namic susceptibility contrast perfusion MRI are usually recom-mended in patients with posterior circulation syndromes [10, 11] .

The two-proton knockout reaction 9Be(26Ne,O2p) was used to explore excited unbound states of 23O and 24O. In 23O a state at an excitation energy of 2.79(13) MeV was observed. There was no conclusive evidence for the population of excited states in 24O., 6 pages, 3 figures, Proc. 9th Int. Spring Seminar on Nucl. Phys. Changing Facets of Nuclear Structure, May 20-34, 2007

Recently, we have reported studies of transport and sorption of heavy metal ions in water-saturated quartz sand columns under relatively fast water flow. In these experiments, clear indications for a fast and strong adsorption of the ions to the sediment could be found. Here we report the findings in a series of other experiments performed under static conditions. In this case, much higher concentrations of ions are adsorbed to the sand and remain immobile over time scales of more than a year. Changes in the MRI contrast observed for the sediment areas with the adsorbed ions indicate rearrangements in the distribution of the ions during the first days after administration to the sediment. EDX-studies of the ion distribution after several days indicate a spatially inhomogeneous distribution of adsorbed ions on the surface of the quartz sand. If the adsorbed ions are subjected to flow, a part of adsorbed ions moves away with the water flow. Also all ions are rapidly accessible to acid leaching.

Angiotensin receptor blockers are potent antihypertensive drugs with very few side effects [1, 2]. No association has been documented between use of angiotensin receptor blockers during the first trimester of gestation and congenital defects. However, there are several reports of malformations and physiologic disturbances, mostly with lethal outcome, in infants exposed to these drugs during the second and third trimesters, as recently reviewed [3, 4]. We report the adverse long-term sequelae noted in an infant following maternal treatment with an angiotensin receptor blocker. A 39-year old woman on treatment with candesartan cilexetil 16 mg once a day [5] for mild essential hypertension became pregnant but the drug was not discontinued. At 31 weeks a male boy weighing 1.65 kg was delivered by cesarian section. The physical examination disclosed climb contractures, skull hypoplasia with microcephaly (head circumference 0.265 m) and moderately underdeveloped calvarial bones. The child developed immediate respiratory distress (treated with oxygen, exogenous surfactant and mechanical respiratory support), arterial hypotension (treated with dopamine and epinephrine), and moderate oliguria (creatinine up to 281 μmol/l, urea up to 15.6 mmol/l and a pathologically increased urinary protein to creatinine ratio of 739 mg/mmol; upper reference 50). His conditions improved during the second week of postnatal life. However, a tendency towards arterial hypertension (mean blood pressure 75–80 mm Hg; upper reference 68) was noted, requiring treatment with the calcium channel blocker amlodipine once a day during 6 weeks. Routine chromosome analysis revealed a normal male karyotype. The boy is currently 34 months of age. Body weight is 11.1 kg (−2.8 SDS), length 0.901 m (−1.5 SDS), head circumference 0.481 m (−2 SDS) and blood pressure slightly elevated (approximately 110/70 mm Hg; upper reference 106/66) and the calvarial bones normally developed. His cognitive and especially his linguistic development are moderately retarded. The physical examination is otherwise normal. Plasma creatinine (36 μmol/l) and urea (6.0 mmol/l) are normal. The urinary protein to creatinine ratio is slightly increased (29 mg/mmol, upper reference 20). Renal ultrasound study demonstrates rather small hyperechogenic kidneys and loss of corticomedullary differentiation. In conclusion during pregnancy the use of drugs that block the renin–angiotensin–aldosterone system, namely angiotensin receptor blockers [3, 4] and converting enzyme inhibitors [4, 6], is strongly cautioned against. Infants surviving the exposition to these agents during the second and third trimesters tend to a chronic kidney disease and a developmental delay. A corresponding long-term follow up is warranted. Giacomo D. Simonetti is currently supported by a scholarship of the Ettore e Valeria Rossi Foundation.

The ground-state configuration of the neutron-rich isotope 23O was analyzed using breakup reactions. The 22O momentum distribution after one-neutron knockout from high-energy 23O projectiles differentiated according to states populated in 22O observed by a coincident measurement of the 22O γ deexcitation. The analysis of the γ ray spectrum revealed three γ ray energies at 1.3, 2.6 and 3.2 MeV corresponding to the known transitions in 22O. A comparison with the experimental data shows that the contribution involving excited states is smaller by a large factor.

NESTER; One-nucleon removal reactions at relativistic energies have been used as spectroscopic tool to obtain information about the ground state properties of several neutron-rich isotopes in the sd-shell. Using the FRS at GSI, the longitudinal momentum distributions of the emerging fragments after one-nucleon removal cross-sections were measured. The relative contributions of the remaining fragments in their ground and excited states have been determined from measurements of gamma rays in coincidence with the longitudinal momentum distributions. The interesting case of 23O will be directly address. The interpretation of our experimental results in the framework of a simple theoretical model will favours a spin and parity assignment of 1/2+ for the 23O ground state in agreement with shell model predictions.

The availability of fast radioactive beams offers the possibility for studies of E1‐strength in projectiles via Coulomb excitation. Theoretical calculations predict that a significant fraction of this strength is shifted towards lower excitation energies in neutron‐rich systems (e.g., [1]). At the NSCL, virtual photon scattering was used to probe the discrete structure of both 18O and 20O for levels in the region between 1 and 8 MeV. Two 1− levels at 5.35(10) and 6.85(5) MeV were observed for the first time in 20O [2]. The observed γ‐ray spectrum for 20O is, in fact, dominated by transitions resulting from E1 excitations to these states. The extracted B(E1) ↑ values of ∼0.062(16) e2fm2 and ∼0.035(9) e2fm2 for the 5.35 and 6.85 MeV levels, respectively, are larger than shell model calculations predict [3, 4]. Such large dipole strengths are not observed for low‐lying 1− states in 18O, indicating a shift of dipole strength towards lower energies as one approaches the neutron drip‐line.

14 pages, 1 table, 2 figures.-- PACS nrs.:27.20.+n; 24.70.+.-- Available online Oct 8, 2001., Dissociation of a 227 MeV/u He-8 beam in a lead target has been studied in a kinematically complete experiment. The results are compared with similar data from the well-known halo nucleus He-6. Coulomb-nuclear interference in the inelastic channel gives evidence for a I-π = 1- resonance in He-8 at E-x = 4.15 MeV. The deduced B(E1) value of 0.38 ± 0.07 e(2) fm(2) indicates a uniform distribution of the four neutrons around the α-particle core., This work was supported by the BMBF under Contracts 06 DA 820, 06 OF 112 and 06MZ 864 and by GSI under Contracts DARICK, OF ELZ,MZKRK and partly supported by the Polish Committee of Scientific Research under Contract PBZ/PB03/113/09, EC under contract ERBCHGE-CT92-0003, CICYT under Contract AEN92-0788-C02-02 (MJGB), WTZ under Contract RUS 674-98 and RFBR under Contract 01-02-16685. One of us (B.J.) acknowledges the support through an Alexander von Humboldt Research Award.

4 pages, 1 table, 4 figures.-- Printed version published Mar 11, 2002.-- PACS nrs: 24.30.Gd; 25.60.-t; 27.20.+n, Low-lying resonance states in He-7(He-6 + n), formed after fragmentation reactions of a 227 MeV/nucleon He-8 beam on a carbon target, have been studied. Coincidences between He-6 nuclei and neutrons, corresponding to the one-neutron knockout channel in He-8, were selected. The relative energy spectrum in the He-6 + n system shows a structure, which is interpreted as the He-7 (Iπ = 3/2(-)) ground state, unbound with 0.43(2) MeV relative to the He-6 + n system and a width of Γ = 0.15(8) MeV overlapping with an excited (Iπ = 1/2(-)) state observed at 1.0(1) MeV with a width of Γ = 0.75(8) MeV., This work was supported by the BMBF under Contracts No. 06 DA 915I, No. 06 OF 838, and No. 06 MZ 864 and by GSI under Contracts No. DA RICK, No. OF ELZK, and No. MZ KRAK and partly supported by the Polish Committee of Scientific Research under Contract No. KBN/2P03B/144/10, by the EC under Contract No. ERBCHGE-CT92-0003, by CICYT under Contract No. AEN92-0788-C02-02 (M. J.G. B.), by RFBR under Contract No. 01-02-16685, and by WTZ under Contract No. RUS 674-98. One of us (B. J.) acknowledges support by Alexander von Humboldt Research.

19 pages, 3 tables, 6 figures.-- PACS nrs.: 27.20.+n; 24.70.+s; 25.06.-t.-- Available online Dec 4, 2000., Dissociation of 227 MeV/u 8He in a carbon target has been studied in kinematically complete experiments. The data include the relative energy spectrum, angular distributions in the neutron knock-out channel (6He+n) as well as diffractive dissociation and inelastic scattering into the (6He+2n) channel. The data are compared with corresponding results from the well-known halo nucleus 6He. In both cases it is found that neutron knock-out is the dominating reaction channel. The relative energy spectrum (6He+n) shows a structure, which is interpreted as being due to the Iπ=3/2− resonance in the 7He ground state with about equal contribution from its Iπ=1/2− spin–orbit partner., The 7He resonance shows a spin alignment similar to that observed in 5He, but with a smaller anisotropy indicating that the structure of the 8He ground state is more complicated than that of 6He., The data in the (6He+2n) channel were used to identify resonances in the excitation energy spectrum of 8He. If the spectrum is interpreted as two overlapping resonances, the spin-parity assignment for these is found to be 2+ and 1−, respectively., This work was supported by the BMBF under Contracts 06 DA 820, 06 OF 474 and 06 MZ 864 and by GSI via Hochschulzusammenarbeitsvereinbarungen under Contracts DA RICK, OF ELZ, MZ KRK and partly supported by the Polish Committee of Scientific Research under KBN grant No. 2 PO3B 14418, EC under contract ERBCHGE-CT92-0003, CICYT under contract AEN92-0788-C02-02 (MJGB) and WTZ under contract RUS 674-98. One of us (B.J.) acknowledges the support through an Alexander von Humboldt Research Award. The authors acknowledge fruitful discussions with Horst Lenske, Sergei Fayans and Leonid Grigorenko.