accelerating-news-arc.web.cern.ch - FCC

Accelerator reliability training help for experts

Jennifer Toes — Mon, 16 Oct 2017 14:58:07 +0000

Accelerator reliability training help for experts
by Panos Charitos

Attendees of the previous ARA course (Image: Athina Papageorgiou-Koufidou)

The goal of the four-day ARA training is to give a common foundation and identify the best practices in reliability engineering for CERN system experts. The biannual course is organized in collaboration with University of Stuttgart, Tampere University of Technology and Ramentor Oy.

Organizer Jussi-Pekka Penttinen describes importance of this type of course: "We all have some idea about reliability from our everyday life. One dictionary definition is that: a reliable vehicle, piece of equipment, or system always works well. Such vague definitions are not suitable in engineering projects. No system is totally free of failure and people working in large organizations have different backgrounds, and therefore their expectations for reliability vary. The training builds a common foundation and understanding of reliability terms and methods which are required to avoid misunderstandings."

The course will consist of three days of theoretical training and one hands on day with ELMAS software that is used in Future Circular Collider study. The topics to be covered include the mathematical treatment of reliability and availability, along with common reliability engineering methods, such as Failure Mode and Effects Analysis, Fault Trees and Reliability Block Diagrams.

The course also demonstrates that theoretical training does not need to be boring. In previous sessions, the participants were asked to bend paper clips. After a while the clip breaks due to metal fatigue. But all clips don’t break at the same time. The exercise demonstrates probabilistic nature of reliability as the number of cycles clips survive form a distribution.

Industry uses this same principle for accelerated life testing and so the exercise gives CERN experts an insight on how CERN suppliers might test their product reliability.

Previous participants have responded positively feedback to the thoroughness of the theory presented on the course, including their understanding of the ELMAS tool. Combining theory and hands-on elements are useful for fostering a deeper understanding of topics presented.

The original motivation for the course was born from the Future Circular Collider study, where the increasing size and stored energy of the collider can be a challenge for system designers.

High system reliability is the key to availability. In colliders, availability directly influences the number of collisions, which can have further knock-on effects on researcher’s ability to find adequate evidence of new physics, as well as reach statistical significance to confirm findings.

The ARA course ultimately aims to increase the number and experience of experts so they are ready to design reliable systems for future colliders.

The Autumn 2017 session of the Reliability Engineering Training will take place at CERN from Tuesday, November 14th to Friday, November 17th. The course is open to all CERN personnel, as well as collaboration partners with discretion.

For more information contact: FCC-RAMS@cern.ch

The author would like to thank Arto Niemi for his invaluable comments and fruitful feedback in writing this article.

Related reading:

Accelerator availability modeling / Integrated Luminosity: https://doi.org/10.1103/PhysRevAccelBeams.19.121003
FCC Innovation Awards: https://fcc.web.cern.ch/Pages/news/FCC-Innovation-Awards.aspx
A scalable and open platform for complex system behavior assessment: https://indico.cern.ch/event/556692/contributions/2592536/

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Accelerator Reliability training

ARA

FCC

RAMS

SuShi: a Superconducting Shield Septum

Sabrina El Yacoubi — Mon, 03 Jul 2017 13:32:10 +0000

SuShi: a Superconducting Shield Septum
by Panos Charitos (CERN)

High-energy colliders have time and again proven their potential for making breakthrough discoveries and exploring some of the biggest questions in physics, the most prominent example being the discovery of the Higgs boson at the LHC in 2013. Given that the time-span from design to construction of an accelerator of this complexity is about 25 years, and to ensure the continuity of CERN's diverse scientific programme, the Future Circular Collider (FCC) Study was launched in 2014 to explore scenarios for post-LHC circular colliders. The unprecedented parameters of this future machine create exciting technological challenges, as it requires novel concepts for many of its key subsystems including the beam injection and extraction.

Given the extremely destructive energy stored in the circulating beams (8.4 GJ, corresponding to the kinetic energy of 24 TGV trains at a speed of 150 km/h), the extraction system is crucial for machine protection, as the beam must be safely disposed in case of any failure, or at the end of an experimental cycle. The extracted beam is first deflected by a fast-pulsed kicker magnet, and then it runs into the high magnetic field region of the static septum magnet, which provides the final, and significant, deflection towards an external beam dump. At the same time this magnet must realize a very low field at the position of the circulating beam. The transition between the two regions must be as thin as possible to reduce the required strength of the upstream kicker system.

A passive superconducting shield can create a zero-field region inside a strong external magnetic field by inducing persistent eddy currents on its surface, automatically arranged in a way to fully cancel the field in its interior (Figure 1).

Figure 1: The SuShi septum principle where the black arrows indicate the shielding currents in the superconductor and the red arrows indicate the magnetic field in the midplane of the device (Image: SuShi/ CERN)

A collaboration between CERN and Wigner Institute for Physics (Budapest, Hungary) was established under the framework of the FCC Study to evaluate the feasibility of this concept in a high-energy accelerator and propose realistic materials and technologies.

Three possible candidates have been selected for the first tests: a bulk MgB₂ tube (Figure 2a), a multilayer helically wrapped GdBCO tape on a copper tube (Figure 2b), and a multilayer NbTi/Nb/Cu sheet. The first prototype was successfully tested in February 2017 at CERN's SM18 facility, and could shield 2.6 T at its surface with a wall thickness of 8.5 mm. This is already a factor of about 2.5 improvement over the Lambertson septa of the LHC.

Tests for the two other prototypes are foreseen for later this year. Once the performance of all three prototypes has been evaluated, the best candidate technology will be chosen for more sophisticated tests and further prototyping.

For more information, visit the project website.

Figure 2a: The MgB₂ prototype (Image: SuShi/ CERN)

Figure 2b: The HTS prototype (Image: SuShi/ CERN)

Figure 3: The SuShi team during the test of the MgB₂ prototype (Image credit: Daniel Barna)

The research group is grateful for the support of the SM18 and the Magnetic Measurements teams, the CERN TE-ABT group and the FCC Study Coordination group.

The research leading to these results has received funding from the European Commission under the FP7 Research Infrastructures project EUCARD-2, grant agreement no. 312453, and the FCC Study group.

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FCC paves the way for future superconductors

Panagiotis Charitos — Mon, 03 Jul 2017 12:03:38 +0000

FCC paves the way for future superconductors
by Panos Charitos (CERN)

Nb3Sn Rutherford cable for high-field magnets to be used in HL-LHC as well as for future colliders covered by the FCC study (Image: CERN)

The FCC Week 2017 offered a unique opportunity to discuss the program and the on-going activities, for the development of Nb3Sn superconductor for the FCC 16T magnets. In a number of dedicated sessions, scientists and industry representatives came together to discuss targets and work on conductor launched for enabling design of compact and cost-efficient magnet design.

In her opening talk, Amalia Ballarino, Head of CERN’s Superconductors & Superconducting devices section, reported on the challenges associated with the development of a Nb3Sn wire that should have performance exceeding that of present state-of-the-art materials. She also reported on the status and progress of the collaboration agreements (Japan, Korea, Russia) launched by CERN and carried-out in the past year. Specific strategic R&D programs have been launched, in parallel with the on-going production for HL-LHC (Europe and USA). Indeed, both performance and quantity of conductor needed for a potential future FCC machine require a world-wide effort. Three talks from Japan, Korea and Russia followed her presentation and reported on the status of the on-going work. Encouraging results were already presented and discussed. Performance increase is one of the key targets of the 16 T conductor development programme. Ballarino emphasized the importance of developing higher critical current density (J_c) at the target field, i.e. the amount of current that goes through the superconducting part of the wire that represents about 50% of the total cross section.

Ballarino emphasized that the focus at this stage is on the development of Nb3Sn multi-filamentary wires meeting the target performance of 1,500 Amperes/mm² at 16 Tesla and a temperature of 4.2 Kelvin (-268.95 °C). She reported that the cost of the process adopted for the R&D work shall also enable large scale production and achievement of the final target (≤ 5 Euro/kA m) – together with an increased J_c. Presently, the conductor procured from HL-LHC has an average of 1,000 A/mm2, with some samples reaching about 1200 A/mm², and a fundamental development R&D effort has to be done in order reach the goal for FCC.

Another key aspect for the success of the programme is to involve industrial partners from an early stage. From the current experience from LHC and HL-LHC we know that the performance requirements for Nb3Sn conductor for future circular collider are challenging. A large industrial effort is needed to engage the community on performance and feasibility of a potential very large-scale production (thousands of tons of conductor).

Researches from various laboratories come close with tindustry to study new materials and ways to achieve the required goal. Examples of academic activities include the characterization of materials that take place in laboratories and institutes all progressing in a global fashion.

Finally, Ballarino reported that the conductor programme explores also the potential of other still novel superconductors MgB2 and iron based superconductors are part of the study. Though these materials are not mature today for magnet development, they both show some potential and are therefore worth investigating for future applications. Understanding of present limits of MgB2 at high field and potentials of iron based are being carried out via collaborations launched by CERN with SPIN and Columbus. Marina Putti from University of Genova/SPIN discussed the collaboration agreement with CERN concerning the development and characterization of MgB2, Bi-2212 and iron based superconductors. Moreover, Columbus Superconductors studies the production of MgB2 wire optimized for high fields.

Cost reduction is one of the key challenges that was clearly set from the beginning of this program and lies at the centre of the study for a future circular collider. Further work is needed to understand how this goal can be achieved. Clearly, increase of Jc, large billets size, the optimization of the processcost along with the optimization of raw materials that arekey elements for cost optimization.

In addition to increased performance and reduced costs, the feasibility of large production is a main target for the future. As Ballarino mentioned, the FCC-hh baseline scenario would require about 7000-9000 tons while a High Energy LHC would require about 2500 tons. This poses a significant challenge compared to present project where Nb3Sn production is also important like ITER (about 500 tons) and the amount for the foreseen HL-LHC upgrade (25 tons).

In parallel with the development of the conductor, the procurement of about 290 km of Nb3Sn wire is foreseen, to cover the needs of the magnet program from 2018 to 2019. The program will also require an additional 6 tons from 2020 to 2030. For this wires, the target J_c (4. 2K, 16T) is 1200 A/mm²and a minimum J_c (4.2 K, 16T) equal to 1000 A/mm².

FCC Conductor development paves the way for the future. Synergies between magnet designers, superconductor experts, material scientists and industry are required to make the next step. The meeting pointed to that direction by bringing together industrial partners and external laboratories and by encouraging collaborations amongst them.

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Laser technology take the LHC to the next level

Livia Lapadatescu — Wed, 01 Mar 2017 16:05:54 +0000

Laser technology to help take the LHC to the next level
by Panos Charitos (CERN)

Jointly developed by researchers from the University of Dundee and the Science and Technology Facilities Council (STFC), the technology – which is known as LESS (Laser Engineered Surface Structures) – could increase the range of experiments possible on the LHC by helping to clear the so-called “electron cloud”: a cloud of negative particles which can degrade the performance of the primary proton beams that circulate in the accelerator.

Laser-engineered surface structures (Image credit: STFC Daresbury Laboratory)

Removing this electron cloud will expand the range of experiments that the LHC, the world’s largest particle collider, can carry out. Professor Amin Abdolvand, chair of functional materials and photonics at Dundee University said: “Large particle accelerators such as the Large Hadron Collider suffer from a fundamental limitation known as the ‘electron cloud’.

“This cloud of negative particles under certain conditions may degrade the performance of the primary proton beams that circulate in the accelerator, which is central to its core experiments.

“Current efforts to limit these effects involve applying composite metal or amorphous carbon coatings to the inner surfaces of the LHC vacuum chambers. These are expensive and time consuming processes that are implemented under vacuum.”

Tests have shown that it is possible to reformulate the surface of the metals in the LHC vacuum chambers to a design that under a microscope resembles the type of sound padding seen in music studios. The surface can trap electrons, keeping the chambers clear of the cloud.

The image shows the metal before the laser treatment (top) and afterwards (bottom) where one can see the characteristic pattern that resembles the type of sound padding (Image credit: Dundee University)

Future upgrades of the LHC that will double the intensity of the beams – thus resulting in a denser electron cloud – and studies for future circular high-intensity and high-energy colliders, could profit from this technique. The LESS method, which uses lasers to manipulate the surface of metals, could effectively reduce the electron cloud allowing for more powerful beams.

Professor Lucio Rossi, project leader of the High Luminosity LHC, said: “If successful, this method will allow us to remove fundamental limitations of the LHC and reach the parameters which are needed for the high luminosity upgrade in an easier and less expensive way. “This will boost the experimental program by increasing the number of collisions in the LHC by a factor over the present machine configuration.”

Michael Benedikt, head of the Future Circular Collider Study at CERN, said: “The LESS solution could be easily integrated in the design of future high-intensity proton accelerators; the method is scalable from small samples to kilometre-long beam lines.”

(*Front page image credit: Joshua Valcarel)

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Designing an elevator system for FCC

Panagiotis Charitos — Mon, 05 Dec 2016 16:45:20 +0000

Designing an elevator system for FCC
by Panos Charitos (CERN)

Designing an elevator system for a 300 underground tunnel that could host a future circular collider (Image: CERN - FCC Collaboration)

CERN has come a long way since its foundation in 1954 in advancing our knowledge about the basic components of the Universe. This was made possible due to the advancements in technologies and the building of more complex accelerators and detectors that significantly push the limit of our knowledge. This complexity calls for long-term planning of any future development.

Building a larger and more powerful accelerator sets a number of challenges related to physics and accelerator parameters but also to civil engineering and day-to-day operations. A future collider like those explored under the FCC study will not merely be a scaled-up version of the LHC but a totally new machine. Scientists and engineers are working to develop new technologies and concepts for building and running such a large-scale research infrastructure.

Designing a 100 km tunnel, lying in an average depth of 300 meters that could host a future collider and the experimental detectors is not a trivial task.

First of all, one needs to face open issues related to the installation of the different accelerator parts, including the high-field magnets, the commissioning of the detectors and the need to transfer equipment between the tunnel and surface facilities. There are many more questions when designing such a system like: "How many people will move within such a large underground facility? How often they will need to access the tunnel and from which points? How quickly will the tunnel be evacuated to ensure safety for the personnel?

Volker Mertens, who is in charge of the Infrastructure and Operation studies for the FCC study, notes: "answering these questions becomes more challenging as the answers depend on the available state-of-the-art technologies and a possible project on how they could evolve within the next 20 years."

A key aspect of the construction and operation phase linked to the above questions is the elevator system that will be installed. Engineers are working to design a number of elevators that will efficiently connect the tunnel with the surface giving access to the engineers and technicians that will work in this project. Damien Lafarge, section leader at CERN responsible for lift operation explains: "lifts that give access to underground part are one of the most vital parts in designing a post-LHC collider. They must be operational all time, with an availability rate of 99.6% as any failure can be very costly in the operation of such a large-scale infrastructure".

An overview of the cavern and the elevator system (Image: CERN - FCC Collaboration)

At this early stage engineers are looking nominally at 12 deep access shafts, where approximately 24 lifts could be located at significant locations intervals along the collider ring. Volker notes that: "to ensure quick and successful intervention in the tunnel, the number of shafts around the tunnel, the number of lifts in each shaft and their capacity are key elements". Presently at the LHC sixteen elevators are used to connect the surface to the LHC and its experiments. The one-stop ride between the surface and the tunnel last about one minute while the cabins of these lifts can carry loads from 1 to 3 tons up to a speed of 2.5 m/s.

For FCC a slightly higher speed of 4-6 m/s to keep the duration of the ride to two minutes and a similar load of 3 tons are discussed as baseline parameters. However the greater depth of the tunnel means that one needs larger cables and thus the total weight of the cables becomes a critical issue. In fact, it turns out that the cables weigh much more than the actual cabin load as Lafarge explains. To address this issue we discuss with our industrial partners different scenarios; from using different materials to a more clever design for the elevator system.

The LHC lifts have made nearly 9'140'000 races ranging from 45.35 to 143.54m, over the LEP and LHC run 1 operation periods. You can multiply this by a factor of 2 or 3 based on the depth and number of components of a future collider (3 times bigger than the LHC) to get a rough idea of the wear and tear that the elevator system will be exposed to. That's why a key idea is now to get a redundancy with 2 lifts per shaft in order to reduce constraints on each lift, therefore maintenance costs, and increase the reliability of the function "access to the underground" at the same time!

Ingo Ruehl, an expert in CERN's Handling Engineering (HE) Group comments: "the earliest stages of any construction project offer the most opportunity for maximising quality and reducing total project costs. With this in mind, we are working in partnership with world leading engineering consultancies to utilise the latest methods and technology to ensure the best possible outcome from the first stages of design."

Thinking and designing the next generation of elevators that will be used for FCC, reliability and availability are realized to be key factors in future large and high-performance colliders as they can guarantee an efficient operation. CERN is working closely with its industrial partners to explore the latest generation of monitoring system for elevators, allowing to anticipate failures, an essential element to ensure the reliability of our facilities.

In the next years, a detailed presentation of the available technical options for the elevator system of the FCC will be prepared. This will be included in the FCC conceptual design report that will cover every aspect of building and operating such a future large-scale infrastructure. FCC offers a unique opportunity for experts in elevator engineering to think of novel solutions in order to address the unprecedented challenges posed by such a large underground facility.

Designing an efficient elevator is important to guarantee the safety for the people installing, maintaining and operating a future more powerful collider and running new experiments that will allow to go deeper in our understanding of our Universe!

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FCC

elevator system

issue 19

Accelerator Fault Tracking at CERN

Panagiotis Charitos — Mon, 05 Dec 2016 13:41:15 +0000

Accelerator Fault Tracking at CERN
by Chris Roderick (CERN)

During Run 2 the LHC achieved an outstanding performance (Image: CERN CDS)

CERN’s Accelerator Fault Tracking (AFT) system aims to facilitate answering questions like: “Why are we not doing Physics when we should be?” and “What can we do to increase machine availability?”

People have tracked faults for many years, using numerous diverse, distributed and un-related systems. As a result, and despite a lot of effort, it has been difficult to get a clear and consistent overview of what is going on, where the problems are, how long they last for, and what is the impact. This is particularly true for the LHC, where faults may induce long recovery times after being fixed.

The AFT project was launched in February 2014 as collaboration between the Controls and Operations groups with stakeholders from the LHC Availability Working Group (AWG).

The project was initially divided into 3 phases, with the 1st phase completed on time, ahead of the LHC restart (post Long Shutdown 1: 2013-2014) and delivering the means to achieve consistent and coherent data capture for LHC, from an operational perspective. Phase 2 of the project has been in progress during 2015-16 working on detailed fault classification and analysis for equipment groups. Phase 3 (pending) foresees extended integration with other systems e.g. asset management tracking to be able to make predictive failure analysis and plan preventive maintenance operations.

AFT helps various teams from around CERN, and output from the Web application regularly features in various machine coordination and operations meetings. Furthermore the AWG and various equipment group representatives are using AFT data and statistics to analyse the performance of their systems and target areas for improvement – as presented at various conferences and workshops [1] [2], and summarized in regular AWG reports [3] [4] [5].

If a picture is worth a 1000 words, then take a look at the AFT Cardiogram (Figure 1) that displays LHC faults occurring in 2016 between Technical Stops 1 and 2, together with the machine activity data.

Figure 1 LHC Faults between 2016 Technical Stops 1 and 2

AFT allows representing relationships between faults such as child faults (represented in pink on the Cardiogram) and faults blocking the resolution of another fault. With such data it is possible to analyse availability from different perspectives such as raw system downtime, impact on machine availability (accounting for faults occurring in the shadow of on-going faults) and root cause analysis (assigning child fault downtime to parent faults). Figure 2 shows an example of such a comparison, for a specific sub-domain of systems displayed in the AFT Web application.

Figure 2 Comparison of Fault Time from different perspectives for LHC Technical Services

Other functionality includes: fault searching and data export with a workflow for fault follow-up by different experts. Like most data-centric systems, the value of the infrastructure and tools is always governed by the quality of the data, and so the role of the AWG – who regularly meet to ensure the completeness and correctness of the AFT data – shouldn’t be underestimated.

The technologies involved are a database to persist fault data, a Java server with ReST APIs for data exchange with the Operation team’s E-logbooks (and potentially other systems), and a dedicated Web application for data editing / visualization and analysis (shown in above screenshots).

The AFT system has been designed to be non-LHC specific, and therefore is able to cater for fault tracking for other accelerators if so desired. Due to the success of AFT for LHC during 2015, in 2016 the CERN Machine Advisory Committee proposed that AFT be used for CERN’s Injector Complex. As such, work has started in late 2016 to prepare for AFT usage in the Injector Complex from the start of 2017 operation at the end of March.

References

[1] 7th Evian Workshop, 2016, https://indico.cern.ch/event/578001

[2] LHC Performance Workshop (Chamonix 2017), https://indico.cern.ch/event/580313/

[3] LHC Availability 2016: Restart to Technical Stop 1, CERN-ACC-NOTE-2016-0047, http://cds.cern.ch/record/2195706?ln=en

[4] LHC Availability 2016: Technical Stop 1 to Technical Stop 2, CERN-ACC-NOTE-2016-0066, http://cds.cern.ch/record/2235082?ln=en

[5] LHC Availability 2016: Technical Stop 2 to Technical Stop 3, CERN-ACC-NOTE-2016-0065, http://cds.cern.ch/record/2235079?ln=en

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Superconducting magnet test facilities workshop

Panagiotis Charitos — Thu, 15 Sep 2016 12:19:13 +0000

First international superconducting magnet test facilities workshop

by Marta Bajko (CERN) and Panos Charitos (CERN)

Overview of CERN's Large Magnet Hall (Image Credit@CERN)

Within the HL-LHC project about 100 superconducting magnets will be produced in the next years up to 2024. Magnets of different type and size will use NbTi or Nb3Sn technology. The design of the superconducting magnets is well advanced at CERN, and other collaborating institutes and for most of them plan to build a model and a prototype magnet during the period 2016-2018. From13-14th of June CERN hosted the 1st International Workshop on Superconducting Magnet Test Facilities where the status of different facilities was presented along with the needed steps to meet the needs and the rising interest on superconductors.

For the design of new high-field magnets for HL-LHC and for the scenarios explored under the FCC study, there are several institutes together with CERN. working on the testing of the models, prototypes and even the series magnets. Some institutes are equipped with adequate infrastructure while others are completing their installations during the next coming years.

The test of a superconducting magnets is part of the QA process to assess the soundness of the construction and the suitability for machine operation. In addition, tests are important also during construction/building of magnets, as an integral part of the construction chain. One has to get timely feedback to take corrective actions during the construction process. In that sense test is a key milestone for triggering acceptance and passage of responsibility between firms and institutes (in case of industrial orders) or among institutes (in the case of in-kind contribution). For the readiness of the test stands and for achieving a a good coherence between the facilities and planned test, it is essential to coordinate the activities with the magnet production managed by WP3, WP6 and WP11 of HL LHC (MSC group at CERN and collaborating Institutes).

The SMTS Workshop contributes to the above mentioned coordination and assessment of the needs and readiness. The main goal of the SMTS workshop is to verify that all test stand will be ready in time and able to perform measurements that will meet the HL-LHC standards. Through regular meetings we to create an active network between the test stands allowing them to exchange methods, techniques, and experience on equipment, data and finally expertise when and where needed. Presently test stations for the HL-LHC magnets exist in the following laboratories: FNAL (USA), BNL (USA), CERN (Switzerland), KEK (Japan), KEK (Japan), CEA Saclary (France), Freia (Sweded), INFN (Milano), LBNL (USA) and Nafassy (Italy)

Most of the test stands for superconducting magnets are in collaboration with CERN for the HL-LHC project but we would like to welcome those working in this area as well independently if they will or not test magnets for HL-LHC or future collider projects. Therefore the above mentioned list has been extended and now also includes GSI (Germany), PSI (Switzerland), JINR (Russia).

This workshop provided a forum for potential users of the Trans National Accesses (TNA) supported by FP7 Eucard2 project and Aries (presently under evaluation). More than 60 participants were registered for the one and a half days of presentations followed by an interactive visit to CERN test facility in SM18. OnAt that occasion 20 experts, mainly from CERN, were sharing their knowledge with the workshop participants during 2 h.

Further events will cover subjects linked to specified areas of measurements as magnetic or mechanical measurements while protection and detection systems will also be treated in detail. The connection to the final IT STRING test will be covered, too. The safety and the interlock systems used by the different test stands will be presented with the goal to optimise the stands and improve where possible the safety of the personnel and the equipment.

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Academia Meets Industry in the European Cryogenics Days at CERN

Panagiotis Charitos — Tue, 21 Jun 2016 16:18:56 +0000

Academia Meets Industry in the European Cryogenics Days at CERN

By Eleonora Getsova (HEPTech)

Cryogenics has widely contributed to the recent major successes of High-Energy Physics (HEP). And conversely, HEP has pushed cryogenic engineering developments to a high level of technical excellence. The third European Cryogenics days, hosted by CERN on 9^th and 10^th June 2016, were focused on the latest developments in Cryogenics and laid grounds for further cooperation between academia and industry in this field.

Organizer of the event that brought together 176 participants, mostly from Europe, was the Cryogenics Society of Europe together with the High-Energy Physics Technology Transfer Network (HEPTech) and CERN, in partnership with the Enterprise Europe Network.

The forum explored topics relating to large cryogenic systems for HEP accelerators and detectors, instrumentation for cryogenic systems, research in the cryogenic field revealing examples of fundamental and applied projects, and future of cryogenics – covering developments in HEP, cryotherapy and space applications.

The talks dedicated to cryogenics for accelerators and detectors gave an overview of the structure of and experience with the cryogenic systems of the Large Hadron Collider (CERN), Wendelstein-7X stellarator (Max Planck Institute of Plasma Physics), the European X-ray Free Electron Laser (DESY, Germany) and the U.S. ITER central solenoid module, and highlighted problems and solutions relating to their installation, commissioning and operation. Lessons learnt from ATLAS and CMS – the two detectors of the LHC machine that use dedicated cryogenic equipment – addressed the most noticeable shortfalls, including oil contamination, experienced with each of them as well as the remedy modifications realized. Cryogenics of the European Spallation Source (ESS) target was explored and it was pointed out that the integrated moderator/hydrogen/helium system is currently being implemented.

Industry introduced novel membrane cryostats for large volume neutrino detectors to be used by CERN to detect interactions between neutrinos and argon atoms.

What makes cryogenic helium so beneficial in turbulence studies and what is the price to pay on the instrumentation side? These issues were the essence of a presentation on the GreC experiment showing preliminary results obtained. The experiment is hosted in SM I8, the CERN main cryogenic test facility, and is probing ultra high-intensity turbulence.

Both academia and industry presented latest developments in the cryogenic instrumentation, such as usage of superconducting devices for metrology and general instrumentation, optical fiber sensors for cryogenic applications, Coulomb Blockade Thermometer as a primary device for sub-kelvin measurements, specifics of the cryogenic instrumentation at CERN depending on the availability of radiation, and application of the Pressure Equipment Directive (PED) on the design codes for cryogenic equipment.

An overview of the research in the cryogenic field covered current research topics at the CERN’s Cryolab in the field of He II, such as heat transport studies in confined superconducting Rutherford cable geometries, options to localize a Quench spot at superconducting radio-frequency cavity surfaces as well as visualized effects of He II heat transfer mechanisms. Different material property test stands and cryocooler based zero boil off cryostat solutions were also discussed. Results of studies of the heat transfer at a sapphire – indium interface in the 30 mK – 300 mK temperature range were presented as well as examples of extreme conditions sample environment used in ISIS neutron scattering experiments at the Rutherford Appleton Laboratory (STFC), including ultra-low temperatures, high magnetic fields, high pressure and cryogenic environment for soft matter samples. Current experimental and theoretical work on cryogenic safety was also explored.

Future cryogenic applications addressing both needs of the fundamental research and applied science were discussed in the second day of the event. HEP research efforts will be concentrated on the development of dedicated cryogenic systems for the High-Luminosity LHC, under construction at CERN, and the Future Circular Collider (FCC), under study. It is clear already that the FCC cryogenic system will require cryoplants far beyond the present state-of-the-art with unit capacities of 100 kW at 4.5 K equivalent including 12 kW at 1.9 K.

Exposition of parts of the human body or the whole human body to cryogenic temperatures and the implying effects are in the core of the advanced cryogenic applications for medical purposes, health and well-being. Identification and development of enabling technologies for re-ignitable cryogenic upper-stages of future rocket launchers will be a breakthrough in usage of cryogenics for space applications at the European Space Agency.

Participants enjoyed the visits of the cryogenic systems at LHC point 1.8, the upper 18 kW cold-box and its corresponding compressor station as well as two 125 m3 liquid helium storage tanks, the CERN Large Magnet Facility, and the Central Cryogenic Laboratory where they had a look at normal helium in a glass cryostat being brought to its superfluid state and explored the Superconducting Cable Test Facility.

The event was accompanied with an industrial exhibition and bilateral brokerage meetings to enable the contacts and future cooperation between the representatives of academia and industry who valued the forum as a major step forward to strengthening of the European cryogenic community. The brokerage event was organized by Enterprise Europe Network, and is part of every European Cryogenics days.

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New furnace for the heat treatment of superconducting coils

Panagiotis Charitos — Tue, 21 Jun 2016 11:44:46 +0000

New furnace for the heat treatment of superconducting coils for HL-LHC and future circular colliders

by Panos Charitos (CERN)

A new furnace for the heat-treatment of superconducting coils is currently commissioned at CERN’s Large Magnet Facility. It is the last large equipment that will allow the production of superconducting coils needed for the HL-LHC upgrade and future colliders explored under the FCC study.

HL-LHC targets to increase the integrated luminosity by a factor of 10, resulting in an integrated luminosity of 3000 fb⁻¹. The higher luminosities will allow higher-precision measurements and enable scientists to collect data at a much faster rate. HL-LHC calls for the development of new 11 Tesla dipole magnets with a total length of 11 meters to replace some of the existing 8 Tesla LHC dipole magnets. The development of these magnets was launched at the end of 2010 in the framework of a collaboration between the magnet groups of CERN and the US laboratory FNAL. Another major improvement for HL-LHC is the reduction of the beam size near the collision points. This requires the development of 150 mm single aperture quadrupoles to be installed in the interaction regions around the ATLAS and CMS experiments. The new quadrupoles, to be operated at a peak field of nearly 12 Tesla, are developed in a joint collaboration between CERN and the US-LHC Accelerator Research Program (LARP).

The FCC study has launched an R&D programme for the development of 16 Tesla magnets. In order to keep the protons on a circular track at the record-breaking energies of 100 TeV foreseen for a future hadron circular collider, scientists have to design and demonstrate very powerful magnets accelerator. The FCC relies on the use of magnets with a nominal field of 16 Tesla, almost double compared to the nominal 8.3 Tesla of the superconducting magnets used in the LHC.

To attain the goals posed by the HL-LHC and the FCC study, the use of new superconducting materials is needed. The niobium-titanium alloy that is currently used for the LHC superconducting magnets doesn’t allow to go higher than 9 T at 1.9 Kelvin in accelerator magnets. A new superconductor, based on the metallic compound niobium-three-tin (Nb₃Sn) is at present the only practical option to reach such a high magnetic fields. Nb₃Sn coils can sustain the required current densities to create magnetic fields of up to 16 T. Therefore it could fulfil the requirements of the HL-LHC upgrade as well as allow to realize a future circular hadron collider like the one explored by the FCC study.

In order to use Nb₃Sn for new magnets one should understand in depth its properties and have the manufacturing processes at hand at a reasonable cost. Nb₃Sn is much more complicated to work with compared to niobium titanium. A high temperature heat treatment (HTHT) is needed to form Nb₃Sn superconductor via a solid state reaction of the primary components. This is a long process that lasts about two weeks. During the HTHT, the coils reach different temperature plateaus up to 665 ^oC.

After this process the material becomes brittle as ceramic. This poses a challenge for the manufacturing processes of the Nb₃Sn superconducting coils. “Nb₃Sn has been chosen for the next generation of superconducting magnets. The field achieved with this material can reach up to 16T. The production of such coils is complex as we must first wind the coils and then perform the heat treatment - a technique called "wind and react" - that will allow the formation of Nb₃Sn” explains Friedrich Lackner, the project engineer who supervises the long quadropule coil production for HL-LHC. He continues: "Submitting an entire coil of many meters length, with its content of insulators and residuals of organics, to a high temperature treatment is a complicated process. Therefore, the oven to accommodate the heat treatment of Nb₃Sn coils requires latest technology to achieve temperature uniformity and process stability."

Friedrich Lackner, project engineer who supervises the long quadropule coil production for HL-LHC, explains the special features of the new furnace.

In 2010 CERN launched the procurement of industrial furnaces to perform the in-house thermal treatment of the new coils. Before the construction of the long coils for future high-field dipole and quadrupole magnets, experts study and develop the process based on a short-model programme based on 2.5 meter magnets. This is a necessary step before starting the construction of the 5.5 m coils for the dipole magnets (that will be installed in the LHC tunnel during the Long Shutdown 2 in 2018) and the 8 meter long coils needed for new quadrupoles.

CERN’s Large Magnet Test facility has been equipped with different furnaces for treating the new superconducting materials forming a full production chain for the new coils. The first piece of this chain is the so-called HB160 high-temperature furnace arrived at CERN in 2011 soon followed by the installation of GLO750.

In 2014, the installation of GLO2000 in the Large Magnet Test hall allowed the treatment of 6.5 m long coils. The first 5.5 m long coils were wound in the CERN Large Magnet to build the HL-LHC 11 Tesla dipole magnets successfully tested this year. The results fulfilled the requirements that were specified for the furnace proving an excellent collaboration between CERN, the US laboratories in developing Nb₃Sn coils that can meet the requirements of the HL-LHC project.

On May, the last missing piece of this chain arrived at CERN. The new furnace, called GL010000, will allow the heat treatment of coils with length of up to 11 meters while it can reach temperatures up to 900 ^oC providing a sufficient margin for future challenges. The new furnace will allow CERN to lead a rich R&D effort in the production of superconducting coils and the development of high-field magnets. Moreover, what makes the new oven unique is the high temperature homogeneity that can be achieved with a tolerance of ⁺/_- 3 ^oC for up to two weeks in an Argon atmosphere. The whole gas guiding system is optimized to achieve the nominal temperature as fast as possible and to achieve the best possible uniformity during the heat treatment.

GL010000 will be mainly used for treating Nb₃Sn quadrupole coils magnets for the HL-LHC while it can also be used for prototyping the 16 Tesla magnets for FCC. The first copper practice coil for the quadrupole magnets (MQXF) will be wounded in early 2016 and a full RHT based on this coil will be performed in summer 2016.

“The completion of this project that started as an initiative for HL-LHC but will be also useful for the new magnets needed for FCC, puts CERN and the global HEP community in a unique position in the development of new powerful accelerator magnets” says Lucio Rossi, leader of the HL-LHC project.

The installation of the new furnace at CERN’s Large Magnet Facility (LMF) will help scientists researching and developing the new materials needed for future colliders to understand the superconductor development based on this Nb₃Sn alloy, and allow CERN to lead the production of superconducting coils and the development of high-field magnets.

The successful test of 11 Tesla magnets for the HL-LHC upgrade and the developments for the 16 Tesla magnets programme of the FCC study proves that the future is bright for developing high-field accelerator magnets. The realization of more powerful magnets will allow extending the luminosity and energy frontiers and pave the way to answer some of the fundamental questions that lie open after the Higgs discovery.

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FCC

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issue17

Highlights from FCC Week 2016

Panagiotis Charitos — Tue, 21 Jun 2016 10:51:00 +0000

Highlights from FCC Week 2016

by Panos Charitos (CERN)

From 11 to 15 April, more than 450 participants from all over the world met in Rome during the 2016 Future Circular Collider (FCC) Week.
The future of high-energy physics on the timescale of the 21st century hinges on designing and building future colliders that could take us at least one order of magnitude beyond the present energy and intensity frontiers. Reaching this goal in an efficient way calls for a large circular collider. The FCC study explores different options for a post-LHC research infrastructure.

The discovery of the Higgs boson, a particle profoundly different from all other elementary particles, calls for further studies of its properties. Moreover, a number “known unknowns” like the observed asymmetry between matter and antimatter, the dark matter content of our Universe and the non-zero neutrino masses are only a few of the indicators that point to physics that possibly lies beyond the Standard Model. There are several questions related to physics at the TeV scale, exacerbated by the lack of evidence (so far) of new physics whose answer is critical for our understanding of the Universe.

The next results from the LHC may shatter some of our previous theories while they could call for a profound change of scientific paradigm signalling an exciting state for modern physics. Whether marked by a major discovery or not they are probably going to question our present understanding of fundamental theories. Gian Guidice, Head of CERN’s TH department in his talk “the FCC and the present physics landscape” concluded: “We live in one of the most fruitful periods in physics facing a number of challenges and new opportunities”.

With the LHC programme underway, the global particle physics community works to prepare a common vision for the future. The full exploitation of the LHC including its high-luminosity phase (HL-LHC) sets a timescale of 20 years. Given the long lead times in the field of high-energy physics, the FCC study is exploring possible options for the post-LHC era. "As one of the high-priority items on CERN's agenda, the FCC design study is exploring a potential post-LHC accelerator project that will ensure the continuation of the world’s particle physics programme” noted Frédérick Bordry, CERN Director for Accelerators and Technology. "The post-LHC accelerator calls for breakthrough technologies to afford the beam energy, intensity and brightness which are required for a future 'discovery machine'." he affirms. This timescale along with the complexity of the FCC project and the desire to profit from other international studies for future accelerators make the FCC study a timely effort.

The physics potential for each of the FCC-study scenarios (proton-proton, electron-positron or electron-proton) was reviewed during the meeting. Each of the scenarios has its specific virtues though there is also a strong complementarity while they set certain challenges for the design of the machine and the experiments. Detector-design concepts for all three scenarios were also presented while areas where further theoretical or experimental input is needed were identified. The FCC physics programme shows that this research infrastructure is not a mere follow up of past machines but could open new horizons in our quest to understand nature.

Among the main R&D programs launched as part of the FCC study are those investigating new superconducting magnets and cryogenic systems, new superconducting RF cavities, innovative vacuum systems as well as innovation in detector technologies to meet the physics challenges. The latest results in these fronts were discussed during the FCC Week 16 and the next steps in R&D activities defined.

Substantial progress has been made on infrastructure and operation studies. Civil engineering studies for a 90-100 km tunnel in the Geneva area were presented. In addition, operational aspects become crucial for FCC; controls and machine protection, as well as energy-consumption, reliability and safety were some of the topics covered during the meeting.

Finally, the FCC week also featured the work of younger researchers. More than 100 of them presented their latest research in the poster sessions. Three of them received the FCC Innovation award that distinguishes early stage researchers or engineers for outstanding work carried out in the scope of the study.

The efforts presented during the 2016 FCC week will culminate into a Conceptual Design Report by 2019. This will serve as a decision aid for a future particle research infrastructure. Michael Benedikt, FCC study leader, concluded: “We have a high responsibility to keep the present momentum and attract more collaborators in our efforts to design future circular machines that will serve the global scientific community”. Following the hard efforts of the last two years: “we must now focus on the established parameters and use them as basis for further optimization that can be done for the machines, detectors, and technologies required to realize such a large-scale research infrastructure.”

The next FCC Week will take place in Berlin from 27 May to 02 June, 2017. This meeting will mark a major review of the study and will be an important step in the launch of the preparation of the FCC Conceptual Design Report.

You can find more information about FCC and the FCC Week 2016 and read more stories in the FCC storify channel.

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FCC

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issue 17