Experimental Verification Towards Feed-Forward Ground Motion Mitigation at ATF2

International audienceWithout counter measures, ground motion effects would deteriorate the performance of future linear colliders to an unacceptable level. An envisioned new ground motion mitigation method (based on feed-forward control) has the potential to improve the performance and to reduce the system cost compared to other proposed methods. For the experimental verification of this feed-forward scheme, a dedicated measurement setup has been installed at ATF2 at KEK. In this paper, the progress on this experimental verification is described. An important part of the feed-forward scheme could be already demonstrated, namely the prediction of the orbit jitter due to ground motion measurements

The Compact Linear Collider (CLIC) - 2018 Summary Report

The Compact Linear Collider (CLIC) is a TeV-scale high-luminosity linear $e^+e^-$ collider under development at CERN. Following the CLIC conceptual design published in 2012, this report provides an overview of the CLIC project, its current status, and future developments. It presents the CLIC physics potential and reports on design, technology, and implementation aspects of the accelerator and the detector. CLIC is foreseen to be built and operated in stages, at centre-of-mass energies of 380 GeV, 1.5 TeV and 3 TeV, respectively. CLIC uses a two-beam acceleration scheme, in which 12 GHz accelerating structures are powered via a high-current drive beam. For the first stage, an alternative with X-band klystron powering is also considered. CLIC accelerator optimisation, technical developments and system tests have resulted in an increased energy efficiency (power around 170 MW) for the 380 GeV stage, together with a reduced cost estimate at the level of 6 billion CHF. The detector concept has been refined using improved software tools. Significant progress has been made on detector technology developments for the tracking and calorimetry systems. A wide range of CLIC physics studies has been conducted, both through full detector simulations and parametric studies, together providing a broad overview of the CLIC physics potential. Each of the three energy stages adds cornerstones of the full CLIC physics programme, such as Higgs width and couplings, top-quark properties, Higgs self-coupling, direct searches, and many precision electroweak measurements. The interpretation of the combined results gives crucial and accurate insight into new physics, largely complementary to LHC and HL-LHC. The construction of the first CLIC energy stage could start by 2026. First beams would be available by 2035, marking the beginning of a broad CLIC physics programme spanning 25-30 years

Równoległy system hybrydowy Voith DIWAhybrid do autobusów miejskich

W dniu 15.06.2011 r. w siedzibie niemieckiego przedsiębiorstwa komunikacji miejskiej Bogestra w Bochum miała miejsce oficjalna prezentacja nowego autobusu Solaris Urbino 18 DIWAhybrid. Zastosowano w nim równoległy układ hybrydowy marki Voith. Zastosowaniee silnika asynchronicznego o mocy 150 kW pozwoliło na zabudowanie jako jednostki spalinowej silnika Cumnis ISB6.7EV 250H, który przy 6,6 l pojemności dostarcza 181 kW i spełnia normy EEV. Zmniejszenie wymiarów silnika diesla powoduje, że system DIWAhybrid powiększa masę autobusu jedenie o 600 kg. Pasażerowie otrzymują jednocześnie ilość miejsc równoważną autobusowi z konwencjanalnym napędem

Electron Tracking Simulations in the Presence of the Beam and External Fields

The ionisation profile monitors installed in the CERN LHC and SPS make use of the ionisation of a small volume of the injected neon gas by the circulating beam. The electrons produced are guided towards the readout system using a combination of electric and magnetic fields. In the presence of the beam field their tracks are modified and the resulting profile is distorted. The Geant4 particle simulation package has been used to simulate the ionisation process, while the CERN developed PyECLOUD code has been used for tracking of the resulting ionised particles. In this paper the results of simulations are compared with observations and conclusions are presented concerning the accuracy of the reconstruction of high-intensity beam profiles

Calcite-CO₂ mixed into CO₂-free air: a new CO₂-in-air stable isotope reference material for the VPDB scale

In order to generate a reliable and long-lasting stable isotope ratio standard for CO2 in samples of clean air, CO2 is liberated from well-characterized carbonate material and mixed with CO2-free air. For this purpose a dedicated acid reaction and air mixing system (ARAMIS) was designed. In the system, CO2 is generated by a conventional acid digestion of powdered carbonate. Evolved CO2 gas is mixed and equilibrated with a prefabricated gas comprised of N-2, O-2, Ar, and N2O at close to ambient air concentrations. Distribution into glass flasks is made stepwise in a highly controlled fashion. The isotopic composition, established on automated extraction/measurement systems, varied within very small margins of error appropriate for high-precision air-CO2 work (about +/- 0.015 parts per thousand for delta(13) C and +/- 0.025 parts per thousand for delta(18)O). To establish a valid delta(18) O relation to the VPDB scale, the temperature dependence of the reaction between 25 and 47 degrees C has been determined with a high level of precision. Using identical procedures, CO2-in-air mixtures were generated from a selection of reference materials; (1) the material defining the VPDB isotope scale (NBS 19, delta(13)C = +1.95 parts per thousand and delta(18)O=-2.2 parts per thousand exactly); (2) a local calcite similar in isotopic composition to NBS 19 ('MAR-J1', delta(13)C - +1.97 parts per thousand and delta(18)O = -2.02 parts per thousand). and (3) a natural calcite with isotopic compositions closer to atmospheric values ('OMC-J1', delta(13)C = -4.24 parts per thousand and delta(18)O = -8.71 parts per thousand). To quantitatively control the extent of isotope-scale contraction in the system during mass spectrometric measurement other available international and local carbonate reference materials (L-SVEC, IAEA-CO-1, IAEA-CO-8, CAL-1 and CAL-2) were also processed. As a further control pure CO2 reference gases (Narcis I and II, NIST-RM 8563, GS19 and GS20) were mixed with CO2-free synthetic air. Independently, the pure CO2 gases were measured on the dual inlet systems of the same mass spectrometers. The isotopic record of a large number of independent batches prepared over the course of several months is presented. In addition, the relationship with other implementations of the VPDB-scale for CO2-in-air (e.g. CG-99, based on calibration of pure CO2 gas) has been carefully established. The systematic high-precision comparison of secondary carbonate and CO2 reference materials covering a wide range in isotopic composition revealed that assigned delta-values may be (slightly) in error. Measurements in this work deviate systematically from assigned values, roughly scaling with isotopic distance from NBS 19. This finding indicates that a scale contraction effect could have biased the consensus results. The observation also underlines the importance of cross-contamination errors for high-precision isotope ratio measurements. As a result of the experiments, a new standard reference material (SRM), which consists of two 5-L, glass flasks containing air at 1.6 bar and the CO2 evolved from two different carbonate materials, is available for distribution. These 'J-RAS' SRM flasks ('Jena-Reference Air Set') are designed to serve as a high-precision link to VPDB for improving inter-laboratory comparability. (a) Copyrght (c) 2005 John Wiley & Sons, Ltd. [References: 48

Localisation of beam offset jitter sources at ATF2

For the commissioning and operation of modern particle accelerators, automated error detection and diagnostics methods are becoming increasingly important. In this paper, we present two such methods, which are capable of localising sources of beam offset jitter with a combination of correlation studies and so called degree of freedom plots. The methods were applied to the ATF2 beam line at KEK, where one of the major goals is the reduction of the beam offset jitter. Results of this localisation are shown in this paper. A big advantage of the presented method is its high robustness especially to varying optics parameters. Therefore, we believe that the developed beam offset jitter localisation methods can be easily applied to other accelerators

The first experience with LHC beam gas ionization monitor

The Beam Gas Ionization Monitors (BGI) are used to measure beam emittance on LHC. This paper describes the detectors and their operation and discusses the issues met during the commissioning. It also discusses the various calibration procedures used to correct for non-uniformity of Multi-Channel plates and to correct the beam size for effects affecting the electron trajectory after ionization