Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

The Large Hadron Collider (LHC), now close to completion at CERN will provide proton–proton collisions with unprecedented luminosity and energy. It will allow the Standard Model of physics to be explored in an energy range where new phenomena can be studied. This includes the validity of the Higgs mechanism, supersymmetry and CP violation. The machine presents a number of novel features discussed in detail below.

https://iopscience.iop.org/article/10.1088/1367-2630/9/9/335/pdf

The Large Hadron Collider

Free-electron laser (FEL) is an all-electric, high-power, high beam-quality source of coherent radiation, tunable – unlike other laser sources – at any wavelength within wide spectral region from hard X-rays to far-IR and beyond. After the initial push in the framework of the “Star Wars” program, the FEL technology benefited from decades of R&D and scientific applications. Currently, there are clear signs that the FEL technology reached maturity, enabling real-world applications. E.g., successful and unexpectedly smooth commissioning of the world-first X-ray FEL in 2010 increased in one blow by more than an order of magnitude (40×) wavelength region available by FEL technology and thus demonstrated that the theoretical predictions just keep true in real machines. Experience of ordering turn-key electron beamlines from commercial companies is a further demonstration of the FEL technology maturity. Moreover, successful commissioning of the world-first multi-turn energy-recovery linac demonstrated feasibility of reducing FEL size, cost and power consumption by probably an order of magnitude in respect to previous configurations, opening way to applications, previously considered as non-feasible. This review takes engineer-oriented approach to discuss the FEL technology issues, keeping in mind applications in the fields of military and aerospace, next generation semiconductor lithography, photo-chemistry and isotope separation.

/pdf/high-power-free-electron-lasers-technology-and-future-3aspk5vvwo.pdf

High-power free-electron lasers–technology and future applications

Nano-Motion Control of Heavy Quadrupoles for Future Particle Colliders: An Experimental Validation

Ambitious projects such as the design of the future Compact Linear Collider (CLIC) require challenging parameters and technologies. Stabilization of the CLIC particle beam is one of these challenges. Ground motion (GM) is the main source of beam misalignment. Beam dynamics controls are however efficient only at low frequency (<4Hz), due to the sampling of the beam at 50 Hz. Hence, ground motion mitigation techniques such as active stabilization are required. This paper shows a dedicated prototype able to manage vibration at a sub-nanometer scale. The use of cutting edge sensor technology is however very challenging for control applications as they are usually used for measurement purposes. Limiting factors such as sensor dynamics and noise lead to a performance optimization problem. The current state of the art in GM measurement and GM mitigation techniques is pointed out and shows limits of the technologies. The proposed active device is then described and a realistic model of the process has been established. A dedicated controller design combining feedforward and feedback techniques is presented and theoretical results in terms of Power Spectral Density (PSD) of displacement are compared to real time experimental results obtained with a rapid control prototyping tool.

/pdf/sub-nanometer-active-seismic-isolator-control-2jkvlfei7w.pdf

Sub-nanometer active seismic isolator control

The conceptual design of the active stabilization and nano-positioning of the CLIC main beam quadrupoles was validated in models and experimentally demonstrated on test benches. Although the mechanical vibrations were re- duced to within the specification of 1.5 nm at 1 Hz, ad- ditional input for the stabilization system control was re- ceived from integrated luminosity simulations that included the measured stabilization transfer functions. Studies are ongoing to obtain a transfer function which is more com- patible with beam based orbit feedback; it concerns the controller layout, new sensors and their combination. In addition, the gain margin must be increased in order to reach the requirements from a higher vibration background. For this purpose, the mechanical support is adapted to raise the frequency of some resonances in the system and the im- plementation of force sensors is considered. Furthermore, this will increase the speed of repositioning the magnets be- tween beam pulses. This paper describes the improvements and their implementation from a controls perspective.

/pdf/system-control-for-the-clic-main-beam-quadrupole-fdpnaish42.pdf

System control for the clic main beam quadrupole stabilization and nano-positioning ∗

The Compact Linear Collider (CLIC) accelerator has strong stability requirements on the position of the beam. In particular, the beam position will be sensitive to ground motion (GM). A number of mitigation techniques are proposed — quadrupole stabilisation and positioning, final doublet stabilisation as well as beam-based orbit and interaction point (IP) feedback. Integrated studies of the impact of the GM on the CLIC Main Linac (ML) and Beam Delivery System (BDS) have been performed, which model the hardware and beam performance in detail. Based on the results, future improvements of the mitigation techniques are suggested and simulated. It is shown that with the current design the tight luminosity budget for GM effects is fulfilled and accordingly, an essential feasibility issue of CLIC has been addressed.

/pdf/status-of-ground-motion-mitigation-techniques-for-clic-4d30k7olq3.pdf

Status of Ground Motion Mitigation Techniques for CLIC

The trajectory feedback of the Compact Linear Collider (CLIC) is an essential mitigation method for ground motion effects at CLIC. In this paper significant improvements of the design of this feedback are presented. The new controller is based on a singular value decomposition (SVD) of the orbit response matrix to decouple the in- and outputs of the accelerator. For each decoupled channel one independent controller is designed by utilising ground motion and noise models. This new design allows a relaxation of the required resolution of the beam position monitor from 10 to 50 nm. At the same time the suppression of ground motion effects is improved. As a consequence, the tight tolerances for the allowable luminosity loss due to ground motion effects in CLIC can be met. The presented methods can be easily adapted to other accelerators in order to loosen sensor tolerances and to efficiently suppress ground motion effects.

/pdf/svd-based-filter-design-for-the-trajectory-feedback-of-clic-1y5kku7rl1.pdf

SVD-based filter design for the trajectory feedback of CLIC

The additional heat load onto the LHC beam screens of the cold magnets in the bending sections ({approx}21 km) is still considered as one of the main possible limitations of the LHC performances. Since more than three years, the characteristics of the electron cloud are being studied in the SPS at ambient (RT) and cryogenic temperatures in both dipole and field free conditions. The results obtained in the SPS in 2003 showed a vacuum cleaning (or vacuum scrubbing) on both ambient and cryogenic surfaces. On the contrary, the heat load and the electron intensity (current collected at the detector) under both dipole and field free conditions at 4.5 or 30 K had shown only a limited decrease after 12 A.h of beam i.e. beam conditioning. Water contamination coming from the unbaked upstream and downstream parts of the SPS (non-baked machine) was suspected to be responsible for this behavior. The upgrade of the existing detectors as well as the design and results obtained with the new strip detector installed in a quadrupole are presented. Preliminary results on the electron cloud build up in the quadrupole will also be presented and compared to the predictions of the simulations. The effects of themore » gases physisorbed at cryogenic temperature in the SPS and in the laboratory are shown and the applicability to the LHC will be discussed.« less

LHC and SPS Electron Cloud Studies

The international CLIC collaboration is carrying out an extensive R&D programme to prepare a multi-TeV electron-positron collider. This year the collaboration will produce a conceptual design report (CDR) to establish the feasibility of the technology. The CLIC concept will be introduced and the status of key studies of critical issues will be discussed, with a focus on the CLIC Test Facility 3 (CTF3), which is a small scale facility to produce and use a high current drive beam.

/pdf/clic-conceptual-design-and-ctf3-results-4agn4hhhy7.pdf

Clic conceptual design and ctf3 results

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