| Paper | Title | Page |
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| WEPMF071 | Dynamic Testing and Characterization of Advanced Materials in a New Experiment at CERN HiRadMat Facility | 2534 |
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Funding: This work has received funding from the European Union's Horizon 2020 Research and Innovation programme under Grant Agreement No 730871. An innovative and comprehensive experiment (named "Multimat") was successfully carried out at CERN HiRadMat facility on 18 different materials relevant for Collimators and Beam Intercepting Devices. Material samples, tested under high intensity proton pulses of 440 GeV/c, exceeding the energy density expected in HL-LHC, ranged from very light carbon foams to tungsten heavy alloys, including novel composites as graphite/carbides and metal/diamond without and with thin-film coatings. Experimental data were acquired relying on extensive integrated instrumentation (strain gauges, temperature sensors, radiation-hard camera) and on laser Doppler vibrometer. This allows investigating relatively unexplored and fundamental phenomena as dynamic strength, internal energy dispersion, nonlinearities due to inelasticity and inhomogeneity, strength and delamination of coatings and surfaces. By benchmarking sophisticated numerical simulations against these results, it is possible to establish or update material constitutive models, which are of paramount importance for the design of devices exposed to interaction with particle beams in high energy accelerators such as the HL-LHC or FCC-hh. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF071 | |
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| WEPMF079 | Experimental Modal Analysis of Lightweight Structures used in Particle Detectors: Optical non-contact Method | 2565 |
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| CERN's specialized structures such as particle detectors are built to have high rigidity and low weight, which comes at a cost of their high fragility. Shock and vibration issues are a key element for their successful transport, handling operations around the CERN infra-structure, as well as for their operation underground. The experimental modal analysis measurement technique is performed to validate the Finite Element Analysis in the case of complex structures (with cables and substructure coupling). In the case of lightweight structures, standard contact measurements based on accelerometers are not possible due to the high mass ratio between the accelerometers and the structure itself. In such a case, the vibration of the structure can be calculated based on the Doppler shift of the laser beam reflected off the vibrating surface. This paper details the functioning and application of an advanced laser-scanning vibrometry system, which utilizes the fore-mentioned non-contact method. The results of the Experimental Modal Analysis of selected lightweight structure using this instrument is also presented and discussed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF079 | |
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| WEPMF080 | Investigation and Estimation of the LHC Magnet Vibrations Induced by HL-LHC Civil Engineering Activities | 2568 |
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| HL-LHC requires the excavation of large underground infrastructures in order to host new equipment. The tunnel shall be ready for installation for LS3 (2022) and therefore its construction shall take in place in parallel with the LHC exploitation. Effect of vibrations induced by civil engineering activities need to be evaluated in order to take required corrective actions. For this purpose, several diverse measurements and experiments have been performed in order to estimate the vibration sources and determine the vibration transfer path through the floor and the structure. The transfer functions from amplitude and phase point of view were determined through molasses rock, for both horizontal and vertical vibrations, with dedicated tools and Experimental Modal Analysis was carried out on mechanical structure. The campaign of measurements have been used to confirm the effect of the surface induced vibration on the circulating beam orbit at the resonance frequencies of the structure. This paper reviews the advanced technique of measurements, results and the conclusion about the impact of operating civil engineering machines (road header, hydraulic hammer) during beam exploitation. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF080 | |
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| WEPMF081 | Mechanical Strain Measurements Based on Fiber Bragg Grating Down to Cryogenic Temperature - R&D Study and Applications | 2572 |
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| In recent years, optical fiber sensors have been increasingly used due to their outstanding performances. Their application is preferable in case of special requirements that exclude the application of conventional electrical sensors. The scientific background of optical fiber sensors is well developed. However, the characteristic of sensors employed in rather harsh environments is often different from the one determined in laboratory conditions or prior to their installation. In order to achieve long-term stable functioning and reliable measurement under severe working environments, such as those occurring at CERN (radiation, cryogenics, high magnetic and electrical field), a statistical measurement campaign was carried out following the international standard ISO 5725. The paper describes the ongoing study to define the accuracy of optical fiber sensors based on Fiber Bragg Grating (FBG) for strain measurements, from room temperature down to 4.2 K. It also describes some of the demanding applications for which optical fiber sensors have been deployed to perform experimental strain measurements (e.g. detectors components, high-energy beam targets and dumps, superconducting magnets). | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF081 | |
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| WEPMG002 | Beam Dump Facility Target: Design Status and Beam Tests in 2018 | 2604 |
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| The Beam Dump Facility (BDF) Project, currently in its design phase, is a proposed general-purpose fixed target facility at CERN, dedicated to the Search for Hidden Particles (SHiP) experiment in its initial phase. At the core of the installation resides the target/dump assembly, whose aim is to fully absorb the high intensity 400 GeV/c SPS beam and produce charmed mesons. In addition to high thermo-mechanical loads, the most challenging aspects of the proposed installation lie in very high energy and power density deposition that are reached during operation. In order to validate the design of the BDF target, a scaled prototype is going to be tested during 2018 in the North Area at CERN, upstream the existing beryllium primary targets. The prototype testing under representative beam scenarios will allow having an insight of the material response in an unprecedented regime. Online monitoring and an extensive Post Irradiation Experimental (PIE) campaign are foreseen. The current contribution will detail the design and handling aspects of the innovative Target Complex as well as the design of the BDF target/dump core and the design and construction of the prototype target assembly. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMG002 | |
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| THPAF040 | Estimated Impact of Ground Motion on HL-LHC Beam Orbit | 3052 |
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Funding: Research supported by the HL-LHC project. The High Luminosity LHC (HL-LHC) will require unprecedented orbit stability at the low beta collision points (IP1 and IP5), and the effect of seismic noise might become a relevant source of luminosity loss. Many studies have been conducted in the past to characterise the actual ground motion in the LHC tunnel, and recently a few geo-phones have been installed to permanently monitor the ground stability at IP1 and IP5. An estimate of the impact of the main machine element vibration on orbit at the IPs and collimators is presented, together with a first look at the data collected by the installed geo-phones. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF040 | |
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