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

Fiber Bragg gratings (FBGs) are point optical fiber sensors that allow the monitoring of a diversity of environmental parameters, e.g., temperature or strain. Several research groups have studied radiation effects on the grating response, as they are implemented in harsh environments: high energy physics, space, and nuclear facilities. We report here the advances made to date in studies regarding the vulnerability and hardening of this sensor under radiation. First, we introduce its principle of operation. Second, the different grating inscription techniques are briefly illustrated as well as the differences among the various types. Then, we focus on the radiation effects induced on different FBGs. Radiation induces a shift in their Bragg wavelengths, which is a property serving to measure environmental parameters. This radiation-induced Bragg wavelength shift (RI-BWS) leads to a measurement error, whose amplitude and kinetics depend on many parameters: inscription conditions, fiber type, pre- or post-treatments, and irradiation conditions (nature, dose, dose rate, and temperature). Indeed, the radiation hardness of an FBG is not directly related to that of the fiber where it has been photo-inscribed by a laser. We review the influence of all these parameters and discuss how it is possible to manufacture FBGs with limited RI-BWS, opening the way to their implementation in radiation-rich environments.

/pdf/radiation-effects-on-fiber-bragg-gratings-vulnerability-and-1xiap5fh.pdf

Radiation Effects on Fiber Bragg Gratings: Vulnerability and Hardening Studies

Longitudinal multi-bunch instability in the CERN SPS with a very low intensity threshold is a serious limitation for the future doubling of bunch intensity required by the HLLHC project. A complete and accurate impedance model is essential to understand the nature of this instability and to plan possible cures. This contribution describes the current longitudinal impedance model of the SPS. Electromagnetic simulations and bench measurements were used to build the model. The contribution from each element is described and compared to the total machine impedance. Together with relevant beam measurements and simulations, the analysis of the different sources of impedance is used to identify the source of the longitudinal instability limiting the SPS performance so that the responsible elements can be acted upon.

/pdf/an-extended-sps-longitudinal-impedance-model-4qxo41vj1s.pdf

An Extended SPS Longitudinal Impedance Model

This paper presents one of the case studies of the Gamma Factory initiative -- a proposal of a new operation scheme of ion beams in the CERN accelerator complex. Its goal is to extend the scope and precision of the LHC-based research by complementing the proton-proton collision programme with the high-luminosity nucleus-nucleus one. Its numerous physics highlights include studies of the exclusive Higgs-boson production in photon-photon collisions and precision measurements of the electroweak (EW) parameters. There are two principal ways to increase the LHC luminosity which do not require an upgrade of the CERN injectors: (1) modification of the beam-collision optics and (2) reduction of the transverse emittance of the colliding beams. The former scheme is employed by the ongoing high-luminosity (HL-LHC) project. The latter one, applicable only to ion beams, is proposed in this paper. It is based on laser cooling of bunches of partially stripped ions at the SPS flat-top energy. For isoscalar calcium beams, which fulfil the present beam-operation constrains and which are particularly attractive for the EW physics, the transverse beam emittance can be reduced by a factor of $5$ within the $8$ seconds long cooling phase. The predicted nucleon-nucleon luminosity of $L_{NN}= 4.2 \times 10^{34}\,$s$^{-1}$cm$^{-2}$ for collisions of the cooled calcium beams at the LHC top energy is comparable to the levelled luminosity for the HL-LHC proton-proton collisions, but with reduced pile-up background. The scheme proposed in this paper, if confirmed by the future Gamma Factory proof-of-principle experiment, could be implemented at CERN with minor infrastructure investments.

High-luminosity Large Hadron Collider with laser-cooled isoscalar ion beams

Fiber Optic Sensors (FOS), whose advantages have made them widely used in many applications, are up to now not so diffusely used for the monitoring of industrial processes, mainly due to two aspects: the expensiveness and complexity of the sensors monitoring systems. For these reasons, these sensor systems are usually substituted with low performance but easier to manage sensors, in agreement with industrial monitoring standards. The read-out system described in this document overcomes the limitations suffered by the commonly used FOS interrogation system and extends the fields in which FOS can be employed. The circuit handles the transduction of an optical signal to an electrical signal, going from wavelength encoding to voltage or current. Moreover, the proposed system relies on a totally analog and fully modular circuit in combination with a power fluctuation rejection circuit. The system is tested through temperature measurements highlighting it's characteristics of reliability and repeatability. The temperature variation is given by a heat plate and monitored with a calibrated sensor close to the Fiber Bragg Grating sensor under test.

Full Analog Fiber Optic Monitoring System Based on Arrayed Waveguide Grating

The i-pipe system is a peculiar structural health monitoring system, based on Fiber Bragg Grating technology, installed on the central beam pipe of the compact Muon solenoid (CMS) experiment at CERN. In this contribution, i-pipe temperature sensors, originally conceived as thermal compensator for the strain sensors, are employed to monitor central beam pipe thermal behavior in correlation with the parameters of the particle beam travelling inside, in order to directly measure possible Beam RF induced heating effect. The i-pipe system turned out to be capable of monitoring, directly and without interference, the parameters of the particle beam circulating in the LHC ring. Hence, the results presented in this work pave the way to the use of the i-pipe as monitoring system of an accelerated high energy particle beam.

Fiber Bragg Grating Sensors as Innovative Monitoring Tool for Beam Induced RF Heating on LHC Beam Pipe

TheLHCinjectionkickermagnetsexperiencedsignificant beam induced heating of the ferrite yoke, with high beam currents circulating for many hours, during operation of the LHC in 2011 and 2012. The causes of this beam induced heating were studied in depth and an improved beam screen implemented to reduce the impedance. Results of measure- ments and simulations of the new beam screen design are presented in this paper: these are used to predict power loss for operation after long shutdown 1 and for proposed HL-LHC operational parameters.

/pdf/beam-coupling-impedance-of-the-new-beam-screen-of-the-lhc-3u3zgelper.pdf

Beam Coupling Impedance of the New Beam Screen of the LHC Injection Kicker Magnets

At the beginning of 2013 an extensive measurement campaign was carried out at the SPS in order to determine the Transverse Mode Coupling Instability thresholds of LHC-type bunches in a wide range of intensities and longitudinal emittances. The measurements were performed in two different configurations of machine optics (nominal and low gamma transition) with the goal to characterize the differences in behavior and performance. The purpose of this paper is to describe in detail the measurement procedure and results, as well as the comparison of the experimental data with HEADTAIL simulations based on the latest SPS impedance model. Beside the impedances of the resistive wall, the beam position monitors (BPMs), the RF cavities, and the flanges, an advanced model of the impedance of the kicker magnets is included, which are found to play a major role in the definition of the stability region of the LHC-type bunches in the two optics configurations studied.

/pdf/tmci-thresholds-for-lhc-single-bunches-in-the-cern-sps-and-rqitt0aqqg.pdf

TMCI Thresholds for LHC Single Bunches in the CERN-SPS and Comparison with Simulations

The spectrum of long bunches injected into the ring with RF switched o has been used in the SPS in the past to probe the longitudinal coupling impedance. After a large campaign of shielding of 800 inter-magnet vacuum ports in 1999 - 2001, the microwave instability threshold was significantly increased and the high-frequency spectrum of the beam became practically flat, apart from a prominent peak at around 1.4 GHz. As corresponding high-frequency impedance could potentially lead to microwave instability of high intensity bunches observed now at high energies in the SPS, a search of the source of this impedance was launched. Using a combination of impedance simulations and measurements, vacuum flanges that are present in a large quantity in the machine have been identified as a main source of impedance at this frequency. Particle simulations based on the SPS impedance model, which includes this previously unknown impedance, are able to reproduce the characteristics of the bunch spectrum and amplitude growth rates and hence, confirm that the impedance of the vacuum flanges is responsible for the observed spectral peak.

/pdf/identification-of-high-frequency-resonant-impedance-in-the-186uf9ue64.pdf

Identification of high-frequency resonant impedance in the CERN SPS

https://cds.cern.ch/record/1749084/files/CERN-ACC-2014-0191.pdf

Theoretical Analysis of Metamaterial Insertions for Resistive-wall Beam-coupling Impedance Reduction

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Benoit Salvant

Author Tools

Chat about Author