LEP and SPS Evacuation Systems and Beam Imminent Warning

An evacuation system was installed in 1989 in the LEP collider. Its purpose was to make people aware of a dangerous situation and to request them to exit from the area rapidly. In 1998, a new feature was added, a final warning now being generated in the radiation-controlled areas before the injection of high-energy particle beams. This Beam Imminent Warning calls for immediate evacuation of those zones as an additional measure to the existing access control procedures. People are thus prevented from being trapped inside a running accelerator. During the next two decades, CERN's fixed-target physics will continue and the SPS will act as pre-injector for the LHC accelerator. A system similar to the one operating successfully at LEP will be implemented in the SPS as part of the current consolidation program. The LEP and SPS evacuation systems and the Beam Imminent features will be described

Evolution dans la gestion de la détection gaz

Cet article présente l'interface graphique qui a été développée pour gérer d'une façon visuelle et globale la détection des gaz inflammables utilisés dans les expériences du hall EHN1 (NA49, NA56, tests pour ATLAS, CMS, Alice, etc.). A cet effet, on utilise des détecteurs catalytiques connectés à une centrale. Afin de retransmettre les alarmes à la salle de contrôle des pompiers, cette centrale est couplée à un automate programmable connecté au réseau Ethernet du CERN. Une liaison filaire entre l'automate et le synoptique câblé des alarmes de niveau 3 assure la redondance nécessaire à ce type d'alarmes. Le logiciel de contrôle LabView a été utilisé pour développer l'interface graphique. Elle permet de visualiser sur n'importe quel PC ou X-Terminal le taux de remplissage des bouteilles de gaz, la position des électrovannes ainsi que les asservissements qui pilotent lors d'une alarme, notamment les ventilations, les panneaux de signalisation et les arrêts d'urgence

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 Diversity of Cytospora Associated With Canker and Dieback of Rosaceae in China, With 10 New Species Described

Cytospora canker is a destructive disease of numerous hosts and causes serious economic losses with a worldwide distribution. Identification of Cytospora species is difficult due to insufficient phylogenetic understanding and overlapped morphological characteristics. In this study, we provide an assessment of 23 Cytospora spp., which covered nine genera of Rosaceae, and focus on 13 species associated with symptomatic branch or twig canker and dieback disease in China. Through morphological observation and multilocus phylogeny of internal transcribed spacer (ITS), large nuclear ribosomal RNA subunit (LSU), actin (act), RNA polymerase II subunit (rpb2), translation elongation factor 1-α (tef1-α), and beta-tubulin (tub2) gene regions, the results indicate 13 distinct lineages with high branch support. These include 10 new Cytospora species, i.e., C. cinnamomea, C. cotoneastricola, C. mali-spectabilis, C. ochracea, C. olivacea, C. pruni-mume, C. rosicola, C. sorbina, C. tibetensis, and C. xinjiangensis and three known taxa including Cytospora erumpens, C. leucostoma, and C. parasitica. This study provides an initial understanding of the taxonomy of Cytospora associated with canker and dieback disease of Rosaceae in China

A tufA metabarcoding approach for Ulva and related seaweeds

Ulva-like green algae are notoriously difficult to distinguish due to their morphological variability and/or similarity. DNA barcoding approaches are therefore currently essential for their reliable identification. However, such approaches often fail when rare or inconspicuous species are to be detected in large mixed populations of Ulva species, for example, at early stages following the introduction of species into new habitats. We therefore developed a detection method based on next-generation DNA sequencing. The approach is suitable for the analysis of DNA traces in preserved water samples or in particles enriched by filtration from such samples. A new pair of primers was designed to amplify a 475 bp segment within the tufA marker gene. The primers were relatively group specific. 68.5% of all reads obtained after quality filtering represented the genus Ulva, 11.1% other Ulvophyceae, and only 20% other Chlorophyta, despite their relatively higher abundance in phytoplankton. The relatively short target amplicon still allows good differentiation of Ulvales and Ulothrichales at the species level. Using a database containing tufA sequences of 879 species - 281 of which were Ulvophyceae and 35 Ulva - we were able to detect mostly Ulvophyceae that had been previously detected in our study area in northern Germany using Sanger sequencing. However, the number of species detected at individual sites was generally higher than in previous studies, which could be due to drifting DNA: Analysis of samples collected at different distances from shore suggests that a sample collected at a given site may be influenced by Ulvophyceae within a radius of up to about 1 km in winter. In summer, this radius is reduced to less than 100 m, possibly due to the less frequent occurrence of strong wind events. Nonetheless, rare species may be detected with this new approach: At one site, an undescribed Blidingia species that was not previously known from our study area was repeatedly detected. Based on these findings, the species was searched for and found, and its identity confirmed by traditional tufA barcoding

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

DAM pilot project: Exclusion of bottom trawl fishery in marine protected areas of the German EEZ (North Sea) - DAM MPA Geo 1, Cruise No. HE588, October 24 - November 4, 2021, Bremerhaven (Germany) - Bremerhaven (Germany)

During HE588, data were collected in five research areas in the south-eastern part of the German Bight as part of the DAM Pilotmission on the exclusion of mobile bottom-contact fishing in the North Sea (www.mgf-nordsee.de). The cruise started on October 24, 2021, and had a duration of twelve days at sea. The conducted tasks consisted of seafloor mapping with hydroacoustic devices, multicoring and grab sampling from the seafloor surface, lander deployments for the study of current characteristics, and video and diving surveys of benthic fauna. Despite the unstable weather conditions, all scientific tasks could be conducted successfully within the allocated time

How do microbiota associated with an invasive seaweed vary across scales?

Communities are shaped by scale dependent processes. To study the diversity and variation of microbial communities across scales, the invasive and widespread seaweed Agarophyton vermiculophyllum presents a unique opportunity. We characterized pro‐ and eukaryotic communities associated with this holobiont across its known distribution range, which stretches over the northern hemisphere. Our data reveal that community composition and diversity in the holobiont vary at local but also larger geographic scales. While processes acting at the local scale (i.e., within population) are the main structuring drivers of associated microbial communities, changes in community composition also depend on processes acting at larger geographic scales. Interestingly, the largest analysed scale (i.e., native and non‐native ranges) explained variation in the prevalence of predicted functional groups, which could suggest a functional shift in microbiota occurred over the course of the invasion process. While high variability in microbiota at the local scale supports A. vermiculophyllum to be a generalist host, we also identified a number of core taxa. These geographically independent holobiont members imply that cointroduction of specific microbiota may have additionally promoted the invasion process

Seiridium (Sporocadaceae) : an important genus of plant pathogenic fungi

The genus Seiridium includes multiple plant pathogenic fungi well-known as causal organisms of cankers on Cupressaceae. Taxonomically, the status of several species has been a topic of debate, as the phylogeny of the genus remains unresolved and authentic ex-type cultures are mostly absent. In the present study, a large collection of Seiridium cultures and specimens from the CBS and IMI collections was investigated morphologically and phylogenetically to resolve the taxonomy of the genus. These investigations included the type material of the most important Cupressaceae pathogens, Seiridium cardinale, S. cupressi and S. unicorne. We constructed a phylogeny of Seiridium based on four loci, namely the ITS rDNA region, and partial translation elongation factor 1-alpha (TEF), β-tubulin (TUB) and RNA polymerase II core subunit (RPB2). Based on these results we were able to confirm that S. unicorne and S. cupressi represent different species. In addition, five new Seiridium species were described, S. cupressi was lectotypified and epitypes were selected for S. cupressi and S. eucalypti.http://www.persoonia.orghttp://www.ingentaconnect.com/content/nhn/pimjam2019Forestry and Agricultural Biotechnology Institute (FABI)Microbiology and Plant Patholog