accelerating-news-arc.web.cern.ch - issue 5

“TLEP” - Circular Higgs Factory and a Long-Term Perspective for High Energy Physics

Sabrina El Yacoubi — Fri, 28 Nov 2014 08:24:49 +0000

“TLEP” - Circular Higgs Factory and a Long-Term Perspective for High Energy Physics
by Frank Zimmermann (CERN)

A long term strategy for particle physics. The succession of TLEP & VHE-LHC could provide more than 50 years of e+e-, pp, AA, ep/A physics at highest conceivable energies. The sequence LEP3 & HE-LHC represents a less ambitious, but lower-energy alternative.s. Image credit: TLEP.

Following the first EuCARD “LEP3 Day” on 18 June 2012 (see article ‘Circulating ideas about a new Higgs factory’ inAccelerating News issue 3), which revealed a great interest in a circular-collider “Higgs factory”, EuCARD Work Package 4,AccNet, has been organizing several workshops discussing the key ingredients, the physics potential, experimental detector concepts, and synergies with other projects of such a facility.

Emphasis has shifted from LEP3, a machine installed in the 27-km LHC tunnel originally proposed, to TLEP, an electron-positron collider in a new 80 or 100-km long ring tunnel. Advantages are manifold: TLEP construction would be fully decoupled from LHC/HL-LHC operation. TLEP could achieve up to 5 times higher luminosity than LEP3, promising a precision for Higgs coupling measurements much better than any other planned or proposed machine. Such precision is needed to discover physics beyond the standard model at energies above 1 TeV. In addition, TLEP could possibly provide the infrastructure (tunnel, cryogenics, injector-ring magnets, detectors) for a future 100-TeV proton-proton collider in the same tunnel – the “Very High Energy LHC” or “VHE-LHC” –, paving a path towards extremely high hadron collision energies, while also allowing for highest-energy electron-proton collisions.

Presently a TLEP conceptual design study is being set up aiming at delivering a design report by 2014/2015.

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TLEP

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EuCARD

issue 5

Diagnostics based on Higher order mode port signals

Sabrina El Yacoubi — Fri, 28 Nov 2014 08:16:23 +0000

Diagnostics based on Higher order mode port signals
by Ursula van Rienen, Thomas Flisgen, Tomasz Galek (Universität Rostock)

"Parasitical" use of HOM couplers. Image credit: Universitat Rostock

Higher order mode (HOM) couplers are a crucial part of many superconducting cavities since unwanted modes, which are excited by the beam, need to be damped effectively. EuCARD WP10 task 5 is predominantly dealing with studies on diagnostics based on HOM port signals. This task is carried out jointly with the teams around Roger Jones (University of Manchester, speaker) and Nicoleta Baboi (DESY).

Monitoring the HOM port signals as a by-product of the HOM damping offers the possibility to determine the transversal offset, the total charge of the bunch, etc. with little additional hardware.

One major concern of the ongoing studies is to predict the theoretical accuracy of the diagnostic system in the context of uncertainties such as perturbations of the cavity from the design shape. The entire investigation is based on three pillars: First, experiments at the FLASH facility at DESY in Hamburg are undertaken with the focus on the third harmonic module ACC39. Second, numerical simulations are performed using existing commercial programs such as CST MICROWAVE STUDIO® and in-house codes. Third, new computational methods are developed and implemented. In this context, a method to determine wake fields in large structures by means of decomposition techniques is constructed. Moreover, a generalized perturbation theory is in development which determines a set of eigenmodes of the perturbed geometry based on a set of eigenmodes of the unperturbed shape. Overall, the research efforts are aiming for a sophisticated understanding of diagnostics based on HOM port signals. The long term goal is the equipment of current and future machines with diagnostics based on HOMs.

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superconducting cavities

wake fields

issue 5

Targeting the Energy Frontier for next Accelerators

Sabrina El Yacoubi — Fri, 28 Nov 2014 08:09:00 +0000

Targeting the Energy Frontier for next Accelerators
by Frank Zimmermann (CERN)

Layout of SAPPHiRE g-g collider Higgs factory delivering 10k Higgs per year.

Recently two EuCARD-AccNet events explored options for the next accelerators at the energy frontier. The EuCARD “SAPPHiRE Day” on 19 February focused on the key components of a proposed g-g collider Higgs factory, based on a recirculating SC linac. The “Joint Snowmass-EuCARD/AccNet-HiLumiLHC meeting on Frontier Capabilities for Hadron Colliders 2013” on 21-22 February investigated the next generations of hadron colliders up to the 100 TeV scale. Both workshops attracted about 50 experts from around the world.

The proposed SAPPHIRE layout is a moderately expensive step towards a higher-energy linear collider, demonstrating the handling of 20-nm spot sizes while delivering first-rate physics results. The emphasis of the SAPPHiRE Day was on the laser system, optical cavity, interaction region design, and FEL approaches.

The joint workshop on frontier capabilities explored the parameters and 20-T magnets for a 33-TeV c.m. pp collider in the existing LHC tunnel and for a 100-TeV c.m. collider in a new 80-km tunnel. The workshop reviewed the high-field magnet development status and plans at CERN and LBNL.

Introducing CRISP Accelerator Topic for Synergies in Physics

Sabrina El Yacoubi — Fri, 28 Nov 2014 08:02:22 +0000

Introducing CRISP Accelerator Topic for Synergies in Physics
by Hans Weise (DESY) with Agnes Szeberenyi (CERN)

Group photo taken at the 2nd CRISP Annual meeting, 18-20 March 2013, PSI, Switzerland. Image credit: CRISP

The EU funded CRISP project (The Cluster of Research Infrastructures for Synergies in Physics) started on 1st October 2011 and runs for 3 years. CRISP is a cooperative project, creating synergies and developing common solutions via knowledge and technology transfer from academia and industry for research infrastructures (RIs), initially bringing together 11 RIs in the field of Physics, Astronomy, and Analytical Facilities from the ESFRI roadmap across Europe. The work is organized around 4 main topics; accelerators, detectors, instruments and experiments, information technology and data management.

In the Accelerator Topic, the CRISP developments support the delivery of beams with superior intensity, the operation of accelerators with high reliability, particle beam characteristics which will allow opening new perspectives and opportunities for the next generation of nuclear and high energy physics projects and of experiments in photon, neutron and ion beam science.

A total of five work packages were defined within the topic to the benefit of several accelerator projects funded by CRISP. Improved ion sources will allow for better operation of Spiral 2 at GANIL. Bunch Shape Monitors are under development at GANIL as well as at GSI for FAIR. Superconducting accelerator technology will be further improved at DESY for the European XFEL, at CERN in collaboration with ESS for future projects including the European Spallation Source, and at GSI in order to address the challenges of fast cycled superconducting magnets for FAIR. Novel compact particle sources, electrons as well as protons, are also discussed and Radio Frequency Solid State Amplifiers using Cavity Combiners are under development at ESRF.

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High Temperature Superconductors in the LHC

Sabrina El Yacoubi — Thu, 27 Nov 2014 14:37:07 +0000

High Temperature Superconductors in the LHC
by Amalia Ballarino (CERN)

Maquette of High Temperature Superconducting Link of the type needed at LHC Point 7. Image credits: CERN

Superconducting links in accelerator systems enable powering of the cryo-magnets from remote power converters. The development carried out within Task 5 of the EuCARD Work Package7 aims at providing such technology for the remote powering of LHC magnets.

The use of High Temperature Superconductors (HTS) in Superconducting Links has the great benefit of enabling the development of a powering system where superconductors can be operated with a generous temperature margin. To enable the use of superconductors with tape geometry, a novel concept of cable optimized for DC electrical transmission (Twisted-Pair Cable) has been developed and demonstrated [1], [2]. A cabling machine enabling the controlled assembly of km-long Twisted Pair cables - made from superconductors with different mechanical characteristics - has been conceived, assembled and commissioned at CERN. A full-scale 5 m long prototype link has been made at CERN and successfully tested in nominal conditions at the University of Southampton [3]. A 20 m-long full scale link is being assembled at CERN, where it will be tested in nominal and transient conditions.

The main outcomes of this activity are: (1) the development of a novel concept of superconducting cable for electrical transmission that can be made from any of the HTS tape-conductors today available (BSCCO 2223, YBCO or MgB2); (2) the development of a new cabling machine for the controlled assembly of the cable; (3) the development of a full superconducting link system that could be used at LHC Point 7 for the powering of the superconducting magnets. The developed technology could be applied for feeding any superconducting system requiring currents in the 1 kA range at any temperature from liquid nitrogen to liquid helium.

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A growing market for accelerator personnel in Europe

Sabrina El Yacoubi — Thu, 27 Nov 2014 14:31:37 +0000

A growing market for accelerator personnel in Europe
by Philip Burrows (JAI, University of Oxford)

Reported skills shortages (number of institutes) vs. area of expertise. Click to enlarge. Image credit: TIARA.

The findings are revealing: an overall growth of 18% in personnel is projected over the next 5 years, driven largely by the construction of new facilities on this timescale. However a majority of respondents report difficulties in hiring suitable personnel, most notably engineers, and skills shortages are reported in a number of critical areas.

In 2011 the members of TIARA Work Package 5 “Education & Training” (WP5) conducted a survey of provision of accelerator science training across Europe which revealed some interesting facts (see Accelerating News issue 2). In our follow-on survey we have attempted to gauge the market needs for accelerator-related personnel by surveying major customers: laboratories, universities, companies and medical facilities that design, build or operate accelerators. We assessed the types, numbers, and qualification levels of required personnel, as well as issues of recruitment and skills shortages. The response was outstanding: 70 research institutes and 44 companies from Denmark, Finland, France, Germany, Italy, Norway, Poland, Spain, Sweden, Switzerland and the United Kingdom completed the survey, accounting for more than 4500 personnel engaged in accelerator-related activities. The findings are described in full in the Needs for Accelerator Scientists report released recently.

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A first layout for the High Luminosity Upgrade

Sabrina El Yacoubi — Thu, 27 Nov 2014 14:26:50 +0000

A first layout for the High Luminosity Upgrade
by Ezio Todesco, Stephane Fartoukh (CERN)

The tentative layout for the insertion: sequence of magnets versus distance to the interaction point in ATLAS or CMS (0 m is the centre of the experiment). The flags indicate a possible origin of the in-kind contribution.
Image credit: HiLumi LHC

A first baseline for the layout of the High Luminosity inner triplet and associated magnets has recently been defined. This is the second major milestone, after the choice of a 150 mm aperture for the quadrupoles in July 2012.

A layout is the selection of the sequence of magnets, their strength, their length, and the associated technology: therefore, it requires inputs both from the optics and from the magnet teams. Its definition is a delicate equilibrium between the search for maximum performance and the need of minimizing complexity and associated risks. Nb3Sn technology had been already selected for the triplet quadrupoles – these magnets are planned to be built with a CERN-US collaboration, heavily relying on the work carried out by LARP in the past 10 years.

After the triplet, a separation dipole of 5.5 T, in Nb-Ti, is being studied by the Japanese team in KEK. The layout is complemented by the challenging orbit correctors, also based on Nb-Ti technology, with nested coils both providing horizontal and vertical field of up to 2 T. A package of higher order correctors relying on superferric technology is also available, in order to correct for the inevitable field imperfections of the inner triplet at the 10-4 level. The triplet corrector package is based on the design developed in Spain by CIEMAT.

As a result, the energy deposition team can start simulations to have a precise estimate of the radiation damage and heat loads coming from the collision debris. It is a heavy shower and magnets will need thick shielding to avoid falling in pieces before reaching the project ambitious goal of 3000 fb-1. The layout has been presented at CERN and will be extensively discussed at theHiLumi/LARP collaboration meeting, 8-10 April 2013, Napa Valley.

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Development and Testing of Crab Cavities for High Intensity Colliders

Sabrina El Yacoubi — Thu, 27 Nov 2014 14:21:39 +0000

Development and Testing of Crab Cavities for High Intensity Colliders
by Peter McIntosh (STFC)

Fig 1: CLIC ‘Undamped’ Crab Cavity Fabricated.Image credit: Shakespeare Engineering Ltd (UK)

Fig 2: LHC 4-rod Crab Cavity Fabricated. Image credit: Niowave Inc (USA)

The development of innovative crab cavity solutions for high intensity particle colliders is part of both the FP7 EUCARD and HiLumi framework programmes.

The activity has been led by Lancaster University and STFC in the UK, in direct collaboration with CERN. For LHC, a compact Superconducting RF (SRF) solution at 400 MHz, capable of fitting into the confined space available at the LHC interaction regions is proposed. A compact TEM type deflecting structure has been manufactured at Niowave from bulk Niobium, which has been tested in SM18 at CERN, reaching a surface magnetic field of 33 mT (limited by a serious LHe leak). This represents the world's first high field test of a compact SRF deflector and the cavity is currently undergoing additional BCP processing in order to reach the LHC design gradient of 6 MV/m (Bpk~70 mT).

For CLIC, a high gradient 12 GHz, normal-conducting travelling-wave structure, with a high group-velocity to minimise the effects of beam loading, has been developed. Two ‘undamped’ structures have been fabricated, one in the UK by Shakespeare Engineering Ltd and the other at CERN. Systematic high gradient tests are planned at SLAC and CERN, to study breakdown differences between deflecting and accelerating structures. A third ‘damped’ cavity is currently being developed to allow verification of the operational performance. A high phase stability control system, which will keep the phase from a klystron stable over long distances, is also in development to meet the stringent CLIC phase stability tolerances.

From the editors

Sabrina El Yacoubi — Thu, 27 Nov 2014 14:16:10 +0000

From the editors
by Agnes Szeberenyi (CERN), Celine Tanguy (CEA)

Fig 1: Amongst the upcoming events we highlight the EuCARD'13 event combined with a workshop on "Visions for the future of Particle Accelerators" on 10-14 June 2013. Image credit: CERN
Fig 2: The ACFA / IPAC’13 Accelerator Prizes will be presented during the IPAC'13 event from 13 to 17 May, 2013, in Sanghai, China. Image credit: IPAC'13

In this spring issue, we look at developments towards higher luminosity and higher energy colliders. We report on the technology developed for the remote powering of the LHC magnets and studies of diagnostics based on higher order mode port signals. We also inform you about the main outcome of the TIARA survey on market needs for accelerator scientists.

Expanding further the scope of the newsletter beyond EuCARD, HiLumi and TIARA projects, we are introducing the Accelerator Topic activities of the CRISP (Cluster of Research Infrastructures for Synergies in Physics) European project and featuring the long term perspective for High Energy Physics via TLEP.

In the headlines, we learn about a new insulating compound for superconducting magnets, US-CERN partnership to accelerate neutrino research, recent results about the particle that we can now name a Higgs boson. We update you concerning the strategy for European particle physics and situation on linear colliders. Finally, we’ve found stories on how superconductivity leads the way to high luminosity and the huge impact of accelerators on semiconductor industry.

We hope you enjoy this issue. Please contact us with any news or events that you would like added to future issues.

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