Large Size Telescope camera support structures for the Cherenkov Telescope Array

The design of the camera support structures for the Cherenkov Telescope Array (CTA) Large Size Telescopes (LSTs) is based on an elliptical arch geometry reinforced along its orthogonal projection by two symmetric sets of stabilizing ropes. The main requirements in terms of minimal camera displacement, minimal weight, minimal shadowing on the telescope mirror, maximal strength of the structures and fast dynamical stabilization have led to the application of Carbon Fibre Plastic Reinforced (CFPR) technologies. This work presents the design, static and dynamic performance of the telescope fulfilling critical specifications for the major scientific objectives of the CTA LST, e.g. Gamma Ray Burst detection.Comment: In Proceedings of the 33rd International Cosmic Ray Conference (ICRC2013), Rio de Janeiro (Brazil). All CTA contributions at arXiv:1307.223

Impact of dead zones on the response of a hadron calorimeter with projective and non-projective geometry

The aim of this study is to find an optimal mechanical design of the hadronic calorimeter for SiD detector which takes into account engineering as well as physics requirements. The study focuses on the crack effects between two modules for various barrel mechanical design on calorimeter response. The impact of different size of the supporting stringers and dead areas in an active calorimeter layer along the module boundary has been studied for single pions and muons. The emphasis has been put on the comparison of the projective and non-projective barrel geometry for SiD hadronic calorimeter.Comment: 12 pages, 8 figure

Status of the Micromegas semi-DHCAL

The activities towards the fabrication and test of a 1 m3 semi-digital hadronic calorime- ter are reviewed. The prototype sampling planes would consist of 1 m2 Micromegas chambers with 1 cm2 granularity and embedded 2 bits readout suitable for PFA calorime- try at an ILC detector. The design of the 1 m2 chamber is presented first, followed by an overview of the basic performance of small prototypes. The basic units composing the 1 m2 chamber are 32 \times 48 cm2 boards with integrated electronics and a micro-mesh. Results of character- ization tests of such boards are shown. Micromegas as a proportional detector is well suited for semi-digital hadronic calorimetry. In order to quantify the gain in perfor- mance when using one or more thresholds, simulation studies are being carried out, some of which will be reported in this contribution

Active stabilization studies at the sub-nanometer level for future linear colliders

The next collider which will be able to contribute significantly to the comprehension of matter is a high energy linear collider. The luminosity of this collider will have to be of 1035cm-2s-1, which imposes a vertical beam size of 0,7nm. The relative motion between the last two focusing magnets should not exceed a third of the beam size above 4Hz. Ground motion and acoustic noise can induce vibrations that have to be compensated with active stabilisation. In this paper, we describe the three aspects needed for such a development. We have assessed sensors capable of measuring sub-nanometre displacements, performed numerical calculations using finite element models to get the dynamic response of the structure, and developed a feedback loop for the active stabilisation. Combining the expertise into a mecatronics project made it possible to obtain a displacement RMS at 5Hz of 0.13nm at the free end of our prototype

Proposal of a new Hcal geometry avoiding cracks in the calorimeter

The classical geometry of a calorimeter consists most of the time in several modules, whose edges are pointing on the beam axis. Thus, detection discontinuities between two consecutive modules induce cracks in the calorimeter, and consequently a loss of precious information. This paper describes two new possible Hcal geometries avoiding such cracks in the detection. Then it deals with the internal layout and assembly procedure

Test in a beam of large-area Micromegas chambers for sampling calorimetry

Application of Micromegas for sampling calorimetry puts specific constraints on the design and performance of this gaseous detector. In particular, uniform and linear response, low noise and stability against high ionisation density deposits are prerequisites to achieving good energy resolution. A Micromegas-based hadronic calorimeter was proposed for an application at a future linear collider experiment and three technologically advanced prototypes of 1$\times$1 m$^{2}$ were constructed. Their merits relative to the above-mentioned criteria are discussed on the basis of measurements performed at the CERN SPS test-beam facility

Simplified transformation of ostreococcus tauri using polyethylene glycol

© 2019 by the authors. Licensee MDPI, Basel, Switzerland. Ostreococcustauri is an easily cultured representative of unicellular algae (class Mamiellophyceae) that abound in oceans worldwide. Eight complete 13–22 Mb genomes of phylogenetically divergent species within this class are available, and their DNA sequences are nearly always present in metagenomic data produced from marine samples. Here we describe a simplified and robust transformation protocol for the smallest of these algae (O. tauri). Polyethylene glycol (PEG) treatment was much more effcient than the previously described electroporation protocol. Short (2 min or less) incubation times in PEG gave >104 transformants per microgram DNA. The time of cell recovery after transformation could be reduced to a few hours, permitting the experiment to be done in a day rather than overnight as used in previous protocols. DNA was randomly inserted in the O. tauri genome. In our hands PEG was 20–40-fold more effcient than electroporation for the transformation of O. tauri, and this improvement will facilitate mutagenesis of all of the dispensable genes present in the tiny O. tauri genome

Linear Collider Final Doublet Considerations: ATF2 Vibration Measurements

Original publication available at http://www.jacow.org/International audienceAt ATF2, to allow the Shintake Monitor located at the Interaction Point to measure the beam size with only 2% of error, vertical relative motion tolerance between SM (Shintake Monitor) and final doublet magnets (FD) is of 7nm for QD0 and 20nm for QF1 above 0.1Hz. Vibration transfer function of FD and SM with their supports has been measured and show a good rigidity. Vertical relative motion between the SM and QD0 (QF1) was thus measured to be only of 5.1nm (6.5nm) with high ground motion representative of a shift period. Same measurements done in horizontal directions showed that tolerances were also respected (much less strict). Moreover, relative motion tolerances should be released due to the good motion correlation measured between FD. Thus the FD and SM supports have been validated on site at ATF2 to be within the vibration specifications

Active stabilization of a mechanical structure

This article [1] refers to a particular stage of our attempt to reach the stabilization of the linear collider final focus quadrupole. All along this final focus, an absolute displacement has to be lower than the third of nanometre above a few hertz. The presented intermediary step consists in doing active vibrations control of an elemen-tary mechanical structure in cantilever mode which is similar to the final focus. We consider mainly the active compensation and the latest results on a large prototype. Other aspects are also treated such as modelling, active isolation and instrumentation dedicated to the ground motion