A capacitor discharge, quasi-trapezoidal pulse generator for particle extraction

In the CERN SPS Accelerator two methods for particle extraction are used. One of these methods, called Slow Extraction, delivers extracted beams with a duration of up to several seconds to the majority of experiments. The other one, the Fast Resonant Extraction, providing particle bursts with a duration of a few milliseconds, is used for neutrino experiments. For the latter kind of extraction a quadrupole magnet is installed, which is connected to a high voltage pulse generator delivering quasi-trapezoïdal current pulses. The pulse generator is a capacitor discharge system generating current pulses, with a rising slope having 2 different gradients, of which the second one is approximately zero. The falling slope is obtained through natural decay in a freewheel circuit. The use of modern GTO (Gate Turn Off) power switches resulted in a much simpler circuit than the use of standard thyristors would have permitted

High power semiconductor switches in the 12 kV, 50 kA pulse generator of the SPS beam dump kicker system

Horizontal deflection of the beam in the dump kicker system of the CERN SPS accelerator is obtained with a series of fast pulsed magnets. The high current pulses of 50 kA per magnet are generated with capacitor discharge type generators which, combined with a resistive free-wheel diode circuit, deliver a critically damped half-sine current with a rise-time of 25 ms. Each generator consists of two 25 kA units, connected in parallel to a magnet via a low inductance transmission line

The future of the SPS injection channel

The SPS accelerator will be used as injector for the LHC and has to be adapted to the LHC requirements. The tight specification on beam blow-up in the SPS requires a reduction of the magnetic field ripple of the SPS injection kicker magnets to less than ±0.5 %. The bunch spacing of the LHC ion beam requires a reduction of the kicker magnets' rise time from 145 ns to less than 115 ns. To obtain the shorter rise time the existing kicker magnets have to be reduced in length and the characteristic impedance has to be increased. The resulting loss in magnetic field has to be compensated by the installation of additional magnets. Results of studies on the required kicker strengths and physical apertures for the different types of beam and corresponding operational modes are shown. Changes to the Pulse Forming Network (PFN) and the option of using Pulse Forming Lines (PFL) are presented. Results of first magnet measurements are shown

Genera of phytopathogenic fungi: GOPHY 3

This paper represents the third contribution in the Genera of Phytopathogenic Fungi (GOPHY) series. The series provides morphological descriptions, information about the pathology, distribution, hosts and disease symptoms for the treated genera, as well as primary and secondary DNA barcodes for the currently accepted species included in these. This third paper in the GOPHY series treats 21 genera of phytopathogenic fungi and their relatives including: Allophoma, Alternaria, Brunneosphaerella, Elsinoe, Exserohilum, Neosetophoma, Neostagonospora, Nothophoma, Parastagonospora, Phaeosphaeriopsis, Pleiocarpon, Pyrenophora, Ramichloridium, Seifertia, Seiridium, Septoriella, Setophoma, Stagonosporopsis, Stemphylium, Tubakia and Zasmidium. This study includes three new genera, 42 new species, 23 new combinations, four new names, and three typifications of older names

Benthic microbial biogeographic trends in the North Sea are shaped by an interplay of environmental drivers and bottom trawling effort

Microbial composition and diversity in marine sediments are shaped by environmental, biological, and anthropogenic processes operating at different scales. However, our understanding of benthic microbial biogeography remains limited. Here, we used 16S rDNA amplicon sequencing to characterize benthic microbiota in the North Sea from the top centimeter of 339 sediment samples. We utilized spatially explicit statistical models, to disentangle the effects of the different predictors, including bottom trawling intensity, a prevalent industrial fishing practice which heavily impacts benthic ecosystems. Fitted models demonstrate how the geographic interplay of different environmental and anthropogenic drivers shapes the diversity, structure and potential metabolism of benthic microbial communities. Sediment properties were the primary determinants, with diversity increasing with sediment permeability but also with mud content, highlighting different underlying processes. Additionally, diversity and structure varied with total organic matter content, temperature, bottom shear stress and bottom trawling. Changes in diversity associated with bottom trawling intensity were accompanied by shifts in predicted energy metabolism. Specifically, with increasing trawling intensity, we observed a transition toward more aerobic heterotrophic and less denitrifying predicted metabolism. Our findings provide first insights into benthic microbial biogeographic patterns on a large spatial scale and illustrate how anthropogenic activity such as bottom trawling may influence the distribution and abundances of microbes and potential metabolism at macroecological scales

An Experimental Area for Short Baseline Neutrino Physics on the CERN Neutrino Beam to Gran Sasso

A new neutrino beam line from the CERN SPS to the Gran Sasso laboratory in Italy is presently under study. The new neutrino beam will allow both long baseline and short baseline neutrino oscillation experiments to be performed. This report presents a conceptual design of the short baseline experimental area to be located at a distance of 1858 m from the neutrino target

Bio-optical properties of the cyanobacterium <i>Nodularia spumigena</i>

In the last century, an increasing number of extreme weather events have been experienced across the globe. These events have also been linked to changes in water quality, especially due to heavy rains, flooding, or droughts. In terms of blue economic activities, harmful algal bloom events can pose a major threat, especially when they become widespread and last for several days. We present and discuss advanced measurements of a bloom dominated by the cyanobacterium Nodularia spumigena conducted by hyperspectral optical technologies via experiments of opportunity. Absorption coefficients, absorbance and fluorescence were measured in the laboratory, and these data are available at https://doi.org/10.4121/21610995.v1 (Wollschläger et al., 2022), https://doi.org/10.4121/21822051.v1 (Miranda et al., 2023) and https://doi.org/10.4121/21904632.v1 (Miranda and Garaba, 2023). Data used to derive the above-water reflectance are available from https://doi.org/10.4121/21814977.v1 (Garaba, 2023) and https://doi.org/10.4121/21814773.v1 (Garaba and Albinus, 2023). Additionally, hyperspectral fluorescence measurements of the dissolved compounds in the water were carried out. These hyperspectral measurements were conducted over a wide spectrum (200–2500 nm). Diagnostic optical features were determined using robust statistical techniques. Water clarity was inferred from Secchi disc measurements (https://doi.org/10.1594/PANGAEA.951239, Garaba and Albinus, 2022). Identification of the cyanobacterium was completed via visual analysis under a microscope. Full sequences of the 16S rRNA and rbcL genes were obtained, revealing a very strong match to N. spumigena; these data are available via GenBank: https://www.ncbi.nlm.nih.gov/nuccore/OP918142/ (Garaba and Bonthond, 2022b) and https://www.ncbi.nlm.nih.gov/nuccore/OP925098 (Garaba and Bonthond, 2022a). The chlorophyll-a and phycocyanin levels determined are available from https://doi.org/10.4121/21792665.v1 (Rohde et al., 2023). Our experiments of opportunity echo the importance of sustainable, simplified, coordinated and continuous water quality monitoring as a way to thrive with respect to the targets set in the United Nations Sustainable Development Goals (e.g. 6, 11, 12 and 14) or the European Union Framework Directives (e.g. the Water Framework Directive and Marine Strategy Framework Directive).</p

The 12 kV, 50 kA Pulse Generator for the SPS MKDH Horizontal Beam Dump Kicker System,equipped with Semiconductor Switches

The high current pulses for the MKDH magnets are generated with capacitor discharge type generators which, combined with a resistive free-wheel diode circuit, deliver a critically damped half-sine current with a rise-time of 25 ms. Each generator consists of two 25 kA units, connected in parallel to a magnet via low inductance transmission lines. They are equipped with a stack of four Fast High Current Thyristors, together with snubber capacitors, a voltage divider and a specially designed trigger transformer