Optical studies for the super separator spectrometer S3

International audienceS3 (Super Separator Spectrometer) [1] is a future device designed for experiments with the high intensity heavy ion stable beams of SPIRAL2 [2] at GANIL (Caen, France). It will include a target resistant to these very high intensities, a first stage momentum achromat for primary beam extraction and suppression, a second stage mass spectrometer and a dedicated detection system. This spectrometer includes large aperture quadrupole triplets with embedded multipolar corrections. To enable the primary beam extraction one triplet has to be opened on one side, which requires an appropriate design of such a multipolar magnet. The final mass separation power required for S3 needs a careful design of the optics with a high level of aberration correction. Multiple symmetric lattices were studied for this purpose. A 4-fold symmetric lattice and the achieved results are described in this paper

Dynamic redox conditions control late Ediacaran metazoan ecosystems in the Nama Group, Namibia

The first appearance of skeletal metazoans in the late Ediacaran (~550 million years ago; Ma) has been linked to the widespread development of oxygenated oceanic conditions, but a precise spatial and temporal reconstruction of their evolution has not been resolved. Here we consider the evolution of ocean chemistry from ~550 to ~541. Ma across shelf-to-basin transects in the Zaris and Witputs Sub-Basins of the Nama Group, Namibia. New carbon isotope data capture the final stages of the Shuram/Wonoka deep negative C-isotope excursion, and these are complemented with a reconstruction of water column redox dynamics utilising Fe-S-C systematics and the distribution of skeletal and soft-bodied metazoans. Combined, these inter-basinal datasets provide insight into the potential role of ocean redox chemistry during this pivotal interval of major biological innovation.The strongly negative δ13C values in the lower parts of the sections reflect both a secular, global change in the C-isotopic composition of Ediacaran seawater, as well as the influence of 'local' basinal effects as shown by the most negative δ13C values occurring in the transition from distal to proximal ramp settings. Critical, though, is that the transition to positive δ13C values postdates the appearance of calcified metazoans, indicating that the onset of biomineralization did not occur under post-excursion conditions.Significantly, we find that anoxic and ferruginous deeper water column conditions were prevalent during and after the transition to positive δ13C that marks the end of the Shuram/Wonoka excursion. Thus, if the C isotope trend reflects the transition to global-scale oxygenation in the aftermath of the oxidation of a large-scale, isotopically light organic carbon pool, it was not sufficient to fully oxygenate the deep ocean.Both sub-basins reveal highly dynamic redox structures, where shallow, inner ramp settings experienced transient oxygenation. Anoxic conditions were caused either by episodic upwelling of deeper anoxic waters or higher rates of productivity. These settings supported short-lived and monospecific skeletal metazoan communities. By contrast, microbial (thrombolite) reefs, found in deeper inner- and mid-ramp settings, supported more biodiverse communities with complex ecologies and large skeletal metazoans. These long-lived reef communities, as well as Ediacaran soft-bodied biotas, are found particularly within transgressive systems, where oxygenation was persistent. We suggest that a mid-ramp position enabled physical ventilation mechanisms for shallow water column oxygenation to operate during flooding and transgressive sea-level rise. Our data support a prominent role for oxygen, and for stable oxygenated conditions in particular, in controlling both the distribution and ecology of Ediacaran skeletal metazoan communities

Indirect rp-Process Rate Measurements

International audienc

S3: The Super Separator Spectrometer for SPIRAL2 stable beams

S3 CollaborationInternational audienceS3 (Super Separator Spectrometer) is a device designed for experiments with the very high intensity stable beams of LINAG, the superconducting linear accelerator of GANIL, which will be built in the framework of SPIRAL2. These beams, which will provide ions with A/Q = 3 in SPIRAL2 phase one, can reach intensities up to 1mA for light ions, A<50. These unprecedented intensities open new opportunities in several physics domains, e.g. super-heavy and very-heavy nuclei, spectroscopy at and beyond the drip line, isomers and ground state properties, multi-nucleon transfer and deep-inelastic reactions. An international collaboration has been formed to propose physics experiments and develop technical solutions for this new instrument

The Super Separator Spectrometer (S3) for SPIRAL2 stable beams

International audienceS3 (Super Separator Spectrometer) is a device designed for experiments with the very high intensity stable beams of LINAG, the superconducting linear accelerator of GANIL, which will be built in the framework of SPIRAL2. These beams can reach intensities exceeding 100pμA for lighter ions. These unprecedented intensities open new opportunities in several physics domains, e.g. super-heavy and very-heavy element properties, spectroscopy at and beyond the dripline, isomer and ground state properties, and the products of multi-nucleon transfer and deep-inelastic reactions. An international collaboration has been formed for proposing physics experiments and developing technical solutions for this new instrument. We present here the optical layout of the spectrometer and the studies of its multipole magnets

Alphaparticle capture reactions in inverse kinematics relevant to p process nucleosynthesis

Expérience GANIL/Spectromètre LISE3International audienc