CERN Accelerating science

Interview with Mariana Mazzucato: Bridging Research with Innovation

Header image: Professor Mariana Mazzucato  speaks on her new book "The Value of Everything - making and taking in the global economy" as part of IIPP's lecture series on public value. Photo by Kirsten Holst. Credit: UCL IIPP

What attracted you in economics?

I was a history major in University, but after working with trade unions in the Boston area I realised that I needed to better understand how changing political, economic and social conditions affected production and work. I decided to go to do a PhD in an institution that offers heterodox as well as mainstream analysis, and was lucky to be well trained in both the Neoclassical approach as well as the Keynesian, Marxist and Classical approaches to understanding value.

Which are the key research areas of the institute for Innovation and Public Purpose (IIPP) at the University College London (UCL)?

The mission of the UCL Institute for Innovation and Public Purpose (IIPP) is to change how public value is imagined, practiced and evaluated. With this mission at its core, IIPP’s research is based around the four “pillars”:

  • rethinking value: creating a new a framework to understand and recognise where value is really created in economies, and where value is being extracted; 
  • directing finance: using patient, strategic finance for sustainable, investment-led growth; 
  • shaping innovation by steering scientific and technological advances to tackle societal challenges;
  • and transforming institutions to create entrepreneurial public institutions driven by public purpose.

Across these pillars are the key IIPP themes of: co-shaping and co-creating - markets can be shaped by purposeful policy making and by new collaborations between the state, business and civil society; missions and public purpose - mission-oriented policy focuses on problem-specific societal challenges, which many different sectors interact to solve; capabilities and governance—how can we build the capacity within the public sector to adapt to new ways of working, influenced by the research pillars? New economic thinking—it has become clear that standard economic thinking is not fit to tackle the societal challenges facing the world and therefore a new model is needed.

Why citizens should be concerned about innovation? Is innovation something concerning only few economists or high-tech companies.

If you care about better living standards that enable people to live better lives, you should be concerned about innovation. Innovation is a vital contributor to economic growth, the big challenge is to make it happen more often. At IIPP we believe that through “missions” we can direct innovation towards some of the greatest challenges society is facing today - climate change, ageing populations and rising inequality - while delivering economic growth. How to get citizens involved in setting missions is also a key question. While the moonshot was top down, the model of the Energiewende is interesting as it was the green movement that led to the legitimacy of sustainability in Germany which could be harnessed politically to create a top down mission.

The concept of missions seems to be an important part of the discussions of Horizon Europe. Could you explain what a mission is?

Missions are a way of engaging research and development to meet global complex challenges by acknowledging that innovation doesn’t just have a rate but also a direction. We have to harness innovation and give it purpose, to create new solutions to “wicked” problems - those that don’t have a simple solution. Missions, like John F Kennedy’s mission to travel to the moon, are bold and inspiration, concrete and measurable, and require interdisciplinary collaboration.

Are you concerned that by focusing too much on problem solving we may not leave enough room for blue-sky research? How important is curiosity driven research for innovation?

In the EU budget there is a separate pot for blue-sky research—that is the ERC. Indeed all missions require both basic and applied, and they also change the conversation between them. We will always need curiosity-driven research and the missions framework that we are proposing at IIPP is not a replacement for this important part of our science base. Missions are a great opportunity to apply technologies that are developed through blue-skies experimentation to broad societal applications, but we must also ensure that we don’t neglect the development of general-purpose technologies which may not have an immediate mission they fit into, like the internet or machine learning. We know that technologies can be the tools that answer big questions—missions are a way of using the tools at our disposal, but blue-sky research is a way of inventing new tools! Another key issue is how to not ignore the humanities and social sciences in missions: poets can help to make missions more inspirational! Indeed, it is Attenborough’s Blue Planet series that has led to school children to dream big about solving a major mission: getting the plastic out of the ocean!

What happens in cases where one mission can be addressed with many different approaches? For example lowering CO2 emission could be addressed from different research strands and I am wondering how this concept applies in that case.

Missions exist specifically for the situation when there is no “magic bullet” to solve a problem. Taking your example; we know the sources of ever-increasing CO2 emissions, but there is no simple solution that allows us to reduce them. There are only complex systemic solutions in which technological pathways and interactions are not clear. This is where missions give top-down direction to innovation, without being prescriptive on what the innovation required to solve the problem must be, and facilitating bottom-up innovation to achieve the goal. We need to use the full power of government instruments - from prize schemes to procurement - to crowd in the multiple bottom up solutions. Many of the UN’s Sustainable Development Goals are this type of “wicked” problem where systemic solutions that combine technologic and social change in a way that we can’t determine today.

Companies will undoubtedly play, as they always have, a role in developing and delivering missions. An entrepreneurial state doesn’t crowd out a strong private sector, and one cannot exist without the other. By setting a bold mission it can increase the expectations by business of where future investment opportunities lie - thus unlocking hoarded investment. Indeed, this is especially needed in an era with record level financialisation with many companies spending more on share buybacks (to boost share prices and hence stock options) than on R&D and human capital investments.

At IIPP we know that markets do not appear out of thin air, they are co-created by interactions between the public and private sectors. Mission-oriented policies also help create the stable environments in which business confidence for investment can be fostered, this is what we mean when we say that missions “crowd-in” investments. If a company manufacturing wind turbines knows that there will be a long-term stable market for their products created by having a government that sets a purpose to their energy policy, they are more likely to invest in new research and development, and we are more likely to profit from their innovations.

We should always remember that it’s not only about money but also organisational capacity. This is why in IIPP we are setting up an MPA that is focused on the dynamic capabilities within public institutions in order to be strategic and mission oriented, including the ability to both welcome uncertainty, and be flexible and adaptable. Similarly, in Europe we should be learning across EU countries what works and what doesn’t. Rather than focussing on cutting deficits with voodoo numbers, we should make sure that all EU countries are well equipped with proper systems of innovation. Many EU countries don’t have key institutions like the science-industry linkages that the Fraunhofer institutes (or the Catapults in the UK) provide, or public banks that provide the strategic long-term finance. It is these key lessons that should be at the heart of being in a common area. 

How investing in research can benefit Europe’s competitiveness? 

We know that we need a sense of urgency in addressing some of the wicked problems, societal challenges and sustainable development goals. Just looking at the latest IPCC reports have demonstrated the urgent need for cross-sector innovation to prevent global atmospheric warming to surpass 1.5oC. During war-time governments don’t worry about justifying spending on weapons with cost-benefit calculations, we need the same war-time sense of urgency to combat the climate crisis. Indeed, IIPP just authored a key chapter on energy innovation for the new UNEP report, which makes this case strongly: it’s not only investment but patient strategic mission oriented investment that is needed.

The financial crisis of 2008 showed that European economies are far too dependent on consumption-led, rather than investment-led, growth. We need to confront the flaws in our economic system to maintain a sustainable, inclusive economy for all. If we don’t confront this challenge Europe cannot be competitive. Mission-oriented policy fosters R&D and the economic spillovers that drive innovation-led growth. We can pursue austerity policies which impacts our future economic growth and devastates public services , or we can pursue strategic goals with societal relevance that require both private and public investments: setting the stage for future long-run growth opportunities for decades. I hope Europe chooses the latter.

Federico Carra (CERN)
A novel composite for HL-LHC collimators
12 Jul 2019

A novel composite for HL-LHC collimators

During the LS2, the LHC collimation system will be upgraded with new primary collimators for halo cleaning and in the dispersion suppression region.

Athena Papageorgiou Koufidou & Fiona J. Harden (CERN)
HiRadMat: testing materials under high radiation
7 Dec 2017

HiRadMat: testing materials under high radiation

The CERN test facility offers high irradiation testing to researchers.

Ruben Garcia Alia (CERN)
RADECS 2017: radiation resistance for electronics
7 Dec 2017

RADECS 2017: radiation resistance for electronics

Addressing radiation effects with RADECS and RADSAGA

Towards single-cycle attosecond light from accelerators

Header image (Figure 1): Technological breakthroughs in light generation and selected applications enabled by qualitatively new light source capabilities (for image sources see below*).

Methods for generating light pulses that are much shorter and brighter than currently available has been set out in a new paper by an international collaboration of accelerator scientists [1]. Figure 1 shows how throughout history the breakthroughs in light generation have revolutionized our ability to study smaller and smaller objects, from microcrystals to viruses and even to individual atoms. The discovery of X-rays at the end of the 19th century enabled diffraction imaging at the atomic scale while, with the invention of synchrotrons in the 1940’s, the photon flux became sufficient to capture the diffraction patterns of nanocrystals in the 1970’s. The time resolution at the atomic scale from these X-ray sources was, however, severely lacking.  Meanwhile, the progress in conventional laser technology, born in the 1960’s, together with the invention of chirped pulse amplification (CPA) developed in the 1980’s, now enables lasers to generate sufficient intensity to drive High-Harmonic Generation (HHG) in gases which can output attosecond duration pulses of light. However, while the femtosecond barrier was broken by laser technology and HHG, the spatial and temporal resolution potentially offered by accelerator-based X-ray sources, remains beyond their reach.

The Free-Electron Laser (FEL) is a cutting-edge, accelerator-based instrument that has the potential to provide simultaneous access to the spatial and temporal resolution of the atomic world. In a FEL, ultra-short electron bunches from an accelerator are passed through a long undulator magnet to generate coherent light. Recently, scientists from SLAC demonstrated the first generation of attosecond hard X-ray pulses, using the Linac Coherent Light Source. Now, as described in the review article by Alan Mak et al. [1], researchers are proposing developments that will make the FEL a fully coherent, single-cycle (attosecond) X-ray laser. The new concepts build upon a strong nexus between linear accelerators, FELs and quantum lasers, to produce extreme attosecond pulses with controllable waveforms.


Figure 2: The left plot in the panel (a) shows the minimum pulse duration attained over time with various demonstrated (blue) and potential (red) technologies while the right plot of the same panel depicts typical temporal waveforms. For simplicity, the period of the carrier is taken to be the same. The panel (b) presents the state-of-the-art of the pulse energy achievable by short-pulse light sources. The HHG and novel undulator concepts deliver few-cycle light pulses whereas the FEL sources shown in the figure deliver light pulses of significantly more than a few cycles. Adapted from [1].

The need for the development of a new attosecond technology is motivated by the diminishing progress in the generation of short pulses with conventional lasers, as depicted in Fig. 2a. The combination of CPA and HHG in gas allowed laser technology to break the femtosecond barrier in the 2000’s, but the initial rapid progress in pulse duration reduction has since levelled off. Another issue with conventional lasers, is that the pulse energies, critical in attosecond science, decrease rapidly as the pulses get shorter as shown in Fig. 2b. On the other hand, the attosecond regime is shown in simulations to be accessible via methods based on coherent radiation from undulators [1]. Moreover, it is seen that the pulse energy of undulator-based attosecond sources may exceed the pulse energy of the equivalent conventional laser sources by three orders of magnitude for the same pulse duration. The sub 50-attosecond, high-energy light pulse generation predicted from undulator-based technology, can therefore open up and provide access to the uncharted territory of the fastest time scales in atoms. 
 


Figure 3: Sudden radiation damage upon ionization in bio-relevant molecules and in DNA, in particular, is related to the electron-hole dynamics occurring on the sub-femtosecond scale. 

An important scientific application of such intense attosecond pulses is the study of electron flow from one region of a molecule to another, so called charge migration, which is a fundamental process in biology. As illustrated in Fig. 3, intense radiation can induce charge migration that leads to DNA and cell damage. Detailed investigations of the mechanism of charge migration are essential for understanding the processes that result in biological malfunction. Such knowledge can be obtained using the high temporal and spatial resolution offered by the proposed developments in undulator attosecond technology.

The authors of the review article have recently expanded their collaboration to form the LUSIA consortium (Towards Attosecond SIngle-cycle Undulator Light). The objectives of the consortium are to shift the paradigm of FEL pulses from long multi-cycle output, towards tailored single-cycle pulses. They aim to conduct proof-of-principle experiments leading to the development of a new enabling technology for attosecond science.


References

  • [1] Alan Mak et al “Attosecond single-cycle undulator light: a review.” Reports on Progress in Physics 82 (2019) 025901

 

* Copyright of images used in Figure 1 from left to right.

Top row:

1. Wikipedia article “Laser,” credits to David Monniaux - Kastler-Brossel Laboratory at Paris VI: Pierre et Marie Curie; 
2. Wikipedia article “Synchrotron,” credits to EPSIM 3D/JF Santarelli, Synchrotron Soleill
3. The Eurpean XFEL: https://www.xfel.eu/facility/overview/index_eng.html
4. Own artistic work
5. Own artistic work

Bottom row:

1. Google Commons.
2. Janos Hajdu “Diffraction before destruction,” talk at the Nobel Symposium on Free Electron Laser Research, 2015.
3. https://lcls.slac.stanford.edu/multimedia, “LCLS: The Linac Coherent Light Source at SLAC.”
4. N. Saito et al. "Attosecond streaking measurement of extreme ultraviolet pulses using a long-wavelength electric field." Scientific reports 6 (2016): 35594. Licensed under a Creative Commons Attribution 4.0 International License.
5. Wikipedia Commons: category “atomic orbitals.”

Panos Charitos (CERN)
Charting impact pathways of Research Infrastructures
13 Mar 2018

Charting impact pathways of Research Infrastructures

Kick-off meeting of the H2020 “RI-PATHS” project in Brussels.

Cristian Pira, Oscar Azzolini, Giorgio Keppel, Silvia Martin, Fabrizio Stivanello (INFN)
Seamless accelerating cavities
20 Mar 2019

Seamless accelerating cavities

Superconducting radiofrequency accelerating cavities are the heart of modern particle accelerators and one of the key challenges for the FCC study.

Alexandra Welsch, Samantha Colosimo, Javier Resta López (University of Liverpool)
Accelerating Learning
8 Oct 2018

Accelerating Learning

Summer events held at CERN boost knowledge and collaboration. The events were coordinated by the QUASAR Group.

ISOLDE's new solenoid spectrometer

Header Image: HIE-ISOLDE infrastructure. (Image: CERN)

New types of experiments have been recently performed at the ISOLDE facility, just before the Long Shutdown 2 (LS2), using a new spectrometer coupled to the HIE-ISOLDE superconducting LINAC. These novel experiments will open new ways of exploring the exotic nuclei, produced at ISOLDE and accelerated with the HIE-ISOLDE accelerator, which reached completion in spring 2018 with the installation of a 4th cryomodule. 

Radioactive ion beams can now be accelerated to energies close to 10 MeV per atomic mass unit (denoted MeV/u), which allows for direct ‘transfer’ reactions to probe into the structure of the exotic isotopes. Two experiments were carried out successfully, on exotic isotopes at opposite ends of the chart of the nuclides. The results will allow to study subtle features of the nuclear forces that bind atomic nuclei but moreover they tell a remarkable story of successful recycling of technology through global collaboration.

These measurements were made possible thanks to ISOLDE’s Solenoid Spectrometer (ISS) that uses a former 4-Tesla superconducting MRI magnet, re-designed for the study of exotic nuclei. The superconducting magnet from an old MRI scanner, previously located in the University of Queensland Hospital in Australia, was moved to CERN and installed at ISOLDE, thanks to a strong collaborative effort involving teams from CERN, the UK and Belgium.

At CERN it was stripped and modified to allow for installation of a particle-detector system inside a vacuum vessel, that was mounted in the large inner bore of the magnet. This particle detector was supplied by collaborators from Argonne National Laboratory, where a similar superconducting soleniod was pioneered, such that experiments could be performed before CERN’s LS2. It was installed on one of the three beam lines of the HIE-ISOLDE accelerator, where it was cooled again so it could be re-energised to function once again as a superconducting solenoid.


Figure 1. Schematic of the ISOLDE Solenoid Spectrometer. 

ISS will broadly contribute to ISOLDE’s physics programme to further our understanding of the evolution of nuclear structure and allowing studies of the changing nature of the once considered immutable shell-structure in atomic nuclei, which is now known to change in isotopes away from stability. It will also help in investigating exotic nuclear shapes – atomic nuclei can be spherical, rugby-ball shaped, or even pear shaped. Moreover, measurements with ISS will help to understand the formation of the elements of the periodic table, which have been formed in nuclear reactions in intense astrophysical environments of supernovae or neutron-star mergers and in processes such as the r-process.


Figure 2. The Superconducting Solenoid at ISOLDE.

Ian Lazarus from STFC Daresbury’s Nuclear Physics Group and Technical Coordinator for the ISOLDE-ISS project,says “For the technical team at STFC the real challenge has been ensuring firstly that the magnet was going to be fit for purpose, then that we could get the magnet back to Europe in one piece before completely reconfiguring it to make it ready for use in its new role.  After nearly 10 months of recommissioning, the solenoid was installed in the ISOLDE hall in March 2017. A third purpose-built beam line was constructed at HIE-ISOLDE to house the experiment. It is mounted on a special platform that allows precise alignment with the incoming beam. Following the installation, the team produced a detailed mapping of the magnetic field and installed the proper magnetic shielding to minimise the effect from the 4T solenoid to the neighbouring equipment and beamlines.

David Sharp, the UK-researcher, from The University of Manchester, in charge of the first experiment, explains: “The exotic beam of interest enters ISS along the magnetic field axis and is incident upon a deuterated polyethylene target that serves as a source of deuterons. The beam undergoes reactions in the target with the reaction of interest identified by detecting the particles emitted from the reaction, specifically protons in these first measurements, along with the beam like particle in it’s residual form. The emitted protons (in this case) are detected in an on-axis position-sensitive silicon-detector array and can be identified by determining the time-of-flight through the field of the solenoid relative to the beam-like particle. The energy of the proton and the distance it travelled from the target they are determined and provide information on the properties of the state populated in the exotic nucleus of interest.”


Figure 3. The position vs. energy measured in the array.

The first two measurements reported by ISOLDE were made possible due to international collaborative efforts; namely the installation of the detector system from the HELIOS experiment at Argonne National Laboratory, with the construction of the future ISS detector system underway at the University of Liverpool and Daresbury Laboratory. The intense work of the teams and the strong coordination allowed them to carry out these measurements before CERN’s LS2.

The first results concern the structure of the radioactive 29Mg nucleus and probes how the structures of nuclei in this mass region evolve away from stability. Can we explain the changes in observed behaviour in ever more exotic systems? ISS performed very well, thanks in part to the quality of the beam provided by HIE-ISOLDE (reaching 106 particles per second and 9.5 MeV/u). Preliminary analysis suggests that the results fit with theoretical predictions. The next step is to go even more exotic by adding more neutrons to the system – into a region where current nuclear models start to fail. “For this we await the end of the long shutdown, during which we will have the new advanced Liverpool detector array installed in the magnet and commissioned” says Sharp.


Figure 4. States in 29Mg measured in the first experiment.

The second measurement focused on the nucleus 207Hg, which resides one neutron outside the magic N=126 shell closure and two protons from the magic Z=82 shell closure. With this isotope, we probe completely unchartered territory – something remarkable given the long history of the field. “No other facility can make mercury beams of this mass and accelerate them to energies above the Coulomb barrier. This, coupled with the outstanding resolving power of the ISS spectrometer, has allowed us to see for the first time the spectrum of excited states in 207Hg.” notes Ben Kay from Argonne National Laboratory and spokesperson for this measurement.

The success of this campaign will enable us to anchor various calculations and models, and better estimate similar excitations in nuclei with ever fewer protons below mercury. “The measurement impacts what we can infer about the third abundance peak in the astrophysical r-process and adds to our knowledge of weak-binding in these exotic nuclear systems. In this instance, the beam was accelerated to 7.4 MeV per nucleon, giving a record total beam energy of 1.52 GeV for an ISOLDE beam. While remarkable, a few extra MeV per nucleon would have enabled even deeper insights by improving the yield for reactions populating states with high spin (angular momentum)” adds Kay. Therefore, the collaboration is looking forward to seeing the HIE-ISOLDE accelerator reach its full capacity.

Beam energies of around 10 MeV per nucleon are necessary to measure direct reactions with yields that reveal the underlying nuclear structure and probe the physics of interest. Gerda Neyens, ISOLDE’s spokesperson notes: “Currently HIE-ISOLDE is operating at 75% of its full design capabilities. Therefore, the maximum energies are only accessible for lighter nuclei, limiting the beam energies for heavy nuclei to 7.5MeV per nucleon. Once HIE-ISOLDE is operating at 100% of its capabilities access to these energies across the full range of the nuclear chart will be possible.

Two new dedicated ISS detector systems are currently under construction in the UK and in Belgium.  These complementary systems will be commissioned during (LS2). This will further boost the physics potential of HIE-ISOLDE and ISS. Moreover, it stands out as an example of collaboration and creativity that enables experimental efforts in nuclear physics, reminding us some of the core values of fundamental research.

L Marco Zanetti (INFN), Frank Zimmermann (CERN)
Discussing a future strategy for muon colliders
8 Oct 2018

Discussing a future strategy for muon colliders

Discussing status and ongoing efforts in light of the upcoming European Strategy update.

Alexandra Welsch, Samantha Colosimo, Javier Resta López (University of Liverpool)
Accelerating Learning
8 Oct 2018

Accelerating Learning

Summer events held at CERN boost knowledge and collaboration. The events were coordinated by the QUASAR Group.

Mohammed Shahzad (University of Strathclyde)
Laser-wakefield accelerators for High-energy coherent Terahertz radiation
26 Jun 2018

Laser-wakefield accelerators for High-energy coherent Terahertz radiation

Paper just published in New Journal of Physics describes a promising pathway to more efficient radiation sources

Seamless accelerating cavities

Header Image: The teamwork with the first copper seamless 400 MHz cavity. (Image: C. Pira)

Superconducting radiofrequency accelerating cavities are the heart of modern particle accelerators. One of the key challenges for FCC is the development of more efficient superconducting RF cavities. Any progress on substrate manufacturing and preparation will have an immediate impact on the final RF performance, as it was demonstrated by the seamless cavities produced for the HIE-ISOLDE project. The welded ISOLDE Quarter Wave Resonators show the typical Q-slope of thin films cavities (decrease of the Cavity Quality Factor at high accelerating fields). The issue was substantially reduced substituting the welding cavities with seamless ones.

Seamless construction helps to reduce the performance limitations arising from defects and irregularities of the welding seams and the area in their vicinity, as well to reduce possible contamination originating from them. FCC studies push in this direction, exploring the seamless cavity production by spinning and electro-hydraulic forming. The cavities will be made both in bulk niobium and in copper coated with a thin film of superconductive niobium.

Spinning is a well-known forming technique since the Middle Ages, however, the SRF community needed to wait for Enzo Palmieri who produced the first seamless elliptical cavity spun and presented it during the SRF conference of 1993 at CEBAF.

Figure 1. The aluminum seamless 400 MHz cavity prototype realized under the supervision of Enzo Palmieri. (Image: O. Azzolini)

In particular, he showed the possibility to spin a copper and niobium monocell, complete with cut-off tubes, starting from planar blanks. The technique is now mature, and it has demonstrated the feasibility to produce a 1.5 GHz nine cell elliptical resonant cavity. For its cheapness, today the spinning technique is largely used by the SRF community for the production of R&D cavities, both in niobium and copper. However, in the production of cavities for accelerators, the standard technique is still preferred. Elliptical cavities traditional fabrication methods consist in the spinning, or deep drawing, of the half-cells and a further electron beam welding on the equator. This protocol guarantees the required dimensional tolerance in a large-scale production, which is a mandatory parameter in the RF design of the accelerator. Due to the non-symmetrical nature of the seamless spinning fabrication method, to guarantee the dimensional tolerance in a large-scale production of thousands cells required from FCC is one of the challenges of this research.

Figure 2. Image featured in the Proceedings of 6th International Conference on RF Superconductivity (SRF1993). Set-up for monocell cavity spinning using a simple hand tool applied as a pry bar. (Image: E. Palmieri)

Moreover, since in FCC the 400 MHz cavities are demanded, the cell diameter increases almost 4 times compared to the standard 1.3 and 1.5 GHz produced up to now by seamless spinning methods. The seamless spinning process increases the surface, from the sheet to a final cavity shape, more or less of a factor of 1.5, independently on the cavity frequency and dimension. This means that the increment in surface during the spinning, in absolute values is 15 times higher in a 400 MHz cavity than the same increment in a 1.3 GHz cavity!

When the seamless spinning technique was proposed for the FCC cavities studies, no one knew if the large amount of cold work generated during the spinning of such a huge cavity, could allow to close the cavity without producing any cracks.

Figure 3. Image featured in the Proceedings of 8th International Workshop on RF Superconductivity (SRF1997). Development of work sone and material stress during intermediate stage of spinning. (Image: E. Palmieri)

In 2017 the aluminum prototype was realized. Aluminum cavity is the first step in seamless spinning production, since aluminum is very machinable compared to copper and niobium and the prototype is used to test the mandrel and the metrology of the cavity. For us, this piece of metal has got a special meaning: it was the last seamless cavity realized by Enzo Palmieri.

During the last year the INFN-LNL SRF group has been carrying out the R&D of the seamless 400 MHz cavities, following the road traced by Enzo, but without benefiting of his genius and his 30 year’s experience.

The first 400 MHz copper cavity spun showed deep cracks near the cell iris, but was fundamental to understand how to improve the process. For a 1.3 GHz a single intermediate annealing between the spinning of the first half cell and the second one allows a complete closure of the cavity. For the 400 MHz cavity, at least three intermediate annealings in ultra high vacuum furnace, at three different stages of spinning process, are necessary for the complete closure.

In November 2018, the first seamless 400 MHz copper cavity in the world was produced. The cavity required three months of work to be finalized, but the more difficult part starts now: to optimize the process and transform a hand-made technology into an industrialized one capable to produce the thousands of cells required by FCC.


References

  • Figure 2. V. Palmieri, R. Preciso, and S. Y. Stark, “Seamless 1.5 GHz cavities obtained by spinning a circular blank of copper or niobium,” in Proceedings of 6th International Conference on RF Superconductivity (SRF1993), CEBAF, Newport News, Virginia, USA, 1993.
  • Figure 3. V. Palmieri, “Seamless cavities: the most creative topic in RF Superconductivity,” in Proceedings of 8th International Workshop on RF Superconductivity (SRF1997), Abano Terme (Padova), Italy, 1997, vol. 3.
Cristian Pira, Oscar Azzolini, Giorgio Keppel, Silvia Martin, Fabrizio Stivanello (INFN)
Seamless accelerating cavities
20 Mar 2019

Seamless accelerating cavities

Superconducting radiofrequency accelerating cavities are the heart of modern particle accelerators and one of the key challenges for the FCC study.

Panos Charitos (CERN)
EASITrain gears up following mid-term review
12 Dec 2018

EASITrain gears up following mid-term review

The meeting offered the opportunity to young researchers to present their latest work.

Massimo Sorbi (CERN, INFN), Marco Statera (INFN) and Ezio Todesco (CERN)
A new step towards successful MgB2 superconducting coils
12 Mar 2018

A new step towards successful MgB2 superconducting coils

MgB2 coil successfully tested at LASA for the round coil superferric magnet correctors

Electron Lens Test Stand at CERN

Header Image: Electron Test Stand gun and collector magnet. (Courtesy of Giulio Stancari, Fermilab)

Due to the high stored energy in the HL-LHC beam tails (estimated to be in the order of 34 MJ above 3.5 beam σ with beam emittance of 3.5E-6 rad m [1]), it is desirable to have active halo control providing more margin during all the operational phases of HL-LHC.

Hollow Electron Lenses [2], [3], give a means of depleting the tails without using intercepting material, avoiding the risk of damage and not contributing to machine impedance. Halo particles that migrate into the electric field generated by a hollow electron column travelling concentrically around the circulating proton beam over a short distance, will be ‘kicked’ to larger oscillation amplitudes (a slow, continuous process) and be pushed towards the collimators. This leads to a cleaning of the tails.

At CERN, an option of installing Hollow Electron Lenses [4], [5] for HL-LHC is being studied; one per beam line (~ 40 m left and right from IP4). Each will provide a 5 A ‘tube’ of electrons, confined with a solenoid magnetic field, counter-propagating concentrically around the circulating high energy proton beams over 3 m of interaction length, see Figure 1. In order to accelerate halo depletion, the electron beam can be modulated On/Off at 35 kHz, with 200 ns rise-time, thereby adding a non-linear effect to the kicks given to the halo particles [6]. This way one can switch the e-beam on and off between trains, and target trains at random or a fixed number of turns.

The degree to which the electron and proton beams overlap as well as the electron beam profile will be measured with a new device being developed in collaboration between CERN and Cockcroft Institute [7], [8]. This so-called Beam Gas Curtain (BGC) monitor, is based on imaging beam induced gas fluorescence from a supersonic gas curtain.

 

Figure 1: Hollow Electron Beam around the circulated beam (left hand side) and schematics of the Collimation Scheme for HL-LHC (right hand side). (Courtesy of Stefano Redaelli, CERN)

Electron Lens for Space Charge Compensation

Space Charge Compensation of intense ion beams (in SIS18, GSI [9], [10]) by non-neutral plasma columns is being studied within the European ARIES project, a collaboration between GSI (Darmstadt), IAP (Frankfurt), RTU (Riga) and CERN. The Joint Research Activity will develop and build a gun prototype capable of providing electron beams currents of up to 20 A in an oval of 70x50, and able to be modulated with changing transverse and longitudinal profile at a bandwidth of 2 to 5 MHz.

An electron lens test stand is required at CERN for:

  • Acquiring operational experience with electron beams of high intensity and high space charge density (5A in a few mm for the Hollow Electron Lens)
  • Testing components for HL-LHC Hollow Electron Lens (HEL), in particular:
    • characterizing the electron gun current emission yield as a function of cathode temperature (800 to 1000 oC) and extraction voltage (0 to 10kV), and measuring the transverse profile of the electron beam to check uniformity and cathode material quality
    • testing the HV modulator working at 10 kV and 5A, 35 kHz repetition rate
    • testing HV power converters pulsing at 35 kHz
    • designing and testing the HEL control system
    • testing the HEL collector repellers and diagnostics
    • testing the Beam Gas Curtain diagnostics for high-density, hollow electron beams
    • testing the Beam Position Monitor response with the available e-beam modulation
  • Testing components for SIS18 SCC, in particular
    • characterizing the electron gun current emission field and transverse profile of the electron beam
    • testing the HV modulators.

The E-lens Test Stand is being constructed using a staged approach, to commission its main components separately, and validate the measurement techniques.

Stage 1 (see Figure 3) is composed of:

  • A gun solenoid of 180 mm aperture, 300 mm length, and up to 0.3T magnetic field
  • A collector solenoid of 135mm aperture, 300 mm length, and up to 0.5T magnetic field
  • A diagnostic box with a Pin Hole Faraday Cup and a YAG screen (see more details later)
  • A bake-out and pumping system to guarantee pressures of the order of 10-10 mbar
  • A collector chamber with passively cooled “Faraday Cup” with viewport.
  • A pulsing device (10 msec 10 Hz, corresponding to a duty cycle of 10-4)
  • Measurement of current with the current transformer in the cathode power converter with 200 MHz bandwidth.

Measurements that can be carried out with Stage 1 are the following:

  • Gun characterization, i.e. measurement of the current emission yield as a function of cathode temperature (typically of the order of 1000 oC) and as a function of the extraction voltage (typically 0 – 10 kV for the HEL gun and up to 25 kV for the SCC gun).
  • Measurements of the beam profile and current with varying magnetic field at the gun.
  • The transverse profile of the electron beam and its energy distribution.
  • Test of auxiliary equipment (e.g. rise time of the anode modulator).

Schematics of the hollow electron gun are shown in Figure 2. 

Figure 2. Layout of a hollow electron gun  (as scaled for the from Fermilab design – Tevatron): Left hand side: mechanical assembly (courtesy of D. Perini, CERN). Right hand side: cathode and shaping electrode (in red), control electrode (in blue) and anode (in green). (Image: CERN)

References for this type of gun and the results of similar measurements can be found in [11], [12], [13], [14].

Measurements of the beam profile as a function of the accelerating voltage (at constant extraction voltage), will require an additional power supply (upgrade A). Testing of the HEL HV modulator will need biasing of the collector to reduce the energy dissipated, adding another power supply (upgrade B).

Figure 3. Layout of the Electron Lens Test Stand, Stage 1: composed of a gun and collector solenoid plus a diagnostic box. (Image: CERN)

Figure 4. Electron Test Stand gun and collector magnet as from today’s installation. (Image: CERN)

The installation of a drift solenoid (Stage 2, shown in Figure 5) is necessary to study electron beam dynamics, develop the beam position monitor, test the BGC with different electron beam sizes, and full testing of the HV modulator performance (frequency of switching and longitudinal modulation for the ARIES application).

In the current plans, the Stage 2 drift solenoid will be a dry, superconducting solenoid, 1 m long, with a magnetic field up to 4 T. Such a solenoid will allow compression of the electron beam by up to a factor of 3 and greatly increase the span of beam dynamics studies possible.

Figure 5. Layout of the Electron Lens Test Stand. Stage 2: derived from Stage 1, adding a drift solenoid between the gun solenoid and the diagnostic box, and upgrading the collector to take more deposited power. (Image: CERN)

Diagnostic box

The Electron Lens Test Stand diagnostic box (Figure 6) hosts the instrumentation able to measure electron current and transverse profile, namely a Pinhole Faraday Cup and a YAG Screen, and possibly a Langmuir probe to measure the electron temperature, electron density, and electric potential. The diagnostic box vacuum chamber (depicted in Figure 7) has several arms for the insertion of the instrumentation, a turbo-pump and a vacuum gauge. The arms have an hippodrome-like shape to minimize the space between the gun and collector solenoid (so that the magnetic field drop at the box itself is minimal) while guaranteeing that the Pinhole Faraday Cup can be swept laterally to cover the transverse size of the electron beam, and leaving enough conductance for the turbo-pump.

Figure 6. Diagnostic box showing the actuators of the Pinhole Faraday Cup and the YAG Screen, a pump and a vacuum gauge. (Image: CERN)

Figure 7. Diagnostic box vacuum chamber. (Image: CERN)

With respect to existing test stands (for example at Fermilab, US, or IAP, Frankfurt), the CERN test stand offers the big advantage of providing diagnostics that sweep through the beam (rather than moving the beam through a fixed diagnostic set-up), a larger accelerating field and a larger drift magnetic field.

The fact of moving the diagnostics rather than the beam will give a more accurate measurement of the transverse beam profile, since the electron beam dynamics for such a non-relativistic beam also depends on the beam position relative to the vacuum chamber walls. For HEL applications, it is very important to accurately establish the shape of the electron beam and its dynamics (i.e. that it stays round along the whole interaction length) since the presence of a residual electric field in the center of the electron beam could perturb the circulating proton beam, especially if pulsed.

The CERN test stand also allows for a comparison between measurements with the Pinhole Faraday Cup, the YAG screen and an eventual beam gas curtain monitor.


References

[1] G. Valentino, presentation at the Review on the needs for a Hollow Electron Lens for the HL-LHC, CERN, 06.10.2016, https://indico.cern.ch/event/567839/contributions/2295258/attachments/1349453/2036619/Halo_MDs_operation_HEL_Review_20161006.pdf
[2] V. Shiltsev, in Proceedings of the CARE-HHH-APD Workshop (BEAM07), CERN-2008-005 (2008) https://care-hhh.web.cern.ch/CARE-HHH/BEAM07/Proceedings/Proceedings/Session%204/S14-Shiltsev-a4.pdf
[3] G. Stancari et al, Phys. Rev. Lett. 107, 084802, https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.107.084802
[4] G. Stancari et al, Conceptual design of hollow electron lenses for beam halo control in the Large Hadron Collider, FERMILAB-TM-2572-APC, CERN-ACC-2014-0248, https://arxiv.org/abs/1405.2033
[5] D. Perini and C. Zanoni, Preliminary Design Study of the Hollow Electron Lens for LHC, CERN-ACC-NOTE-2017-0004  https://cds.cern.ch/record/2242211
[6[ M. Fitterer et al., in Proceedings of IPAC2017, Copenhagen, Denmark, http://accelconf.web.cern.ch/AccelConf/ipac2017/papers/thpab041.pdf
[7] V. Tzoganis, in Proceedings of IPAC2014, Dresden, Germany
[8] H.D. Zhang, in Proceedings of IPAC2017, Copenhagen, Denmark, http://accelconf.web.cern.ch/AccelConf/ipac2017/papers/mopab139.pdf
[9] W.D. Stem at al., in Procedeengs of HB2016, Malmö, Sweden, http://accelconf.web.cern.ch/AccelConf/hb2016/papers/thpm5x01.pdf .
[10] D. Ondreka et al., in Proceedings of IPAC2017, Copenhagen, Denmark, http://accelconf.web.cern.ch/AccelConf/ipac2017/papers/tupva059.pdf
[11] A. Sharapa et al., Nucl. Instrum. Methods Phys. Research A, 406, 169 (1998), https://www.sciencedirect.com/science/article/pii/S0168900297011911?via%3Dihub .
[12] A. Ivanov and M. Tiunov, in Proceedings of the 2002 European Particle Accelerator Conference (EPAC02), Paris, France, June 2002, p. 1634, http://accelconf.web.cern.ch/AccelConf/e02/PAPERS/WEPRI050.pdf .
[13] S. Li and G. Stancari, FERMILAB-TM-2542-APC (August 2012), http://inspirehep.net/record/1181720 .
[14] V. Moens, Masters Thesis, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland, FERMILAB-MASTERS-2013-02 and CERN-THESIS-2013-126 (August 2013) http://cds.cern.ch/record/1599475 .

 

 

Alexandra Welsch, Samantha Colosimo, Javier Resta López (University of Liverpool)
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Header Image: ATLAS detector (Image: CERN)

For the HL-LHC Collider-Experiment Interface Work Package, their LS3 started last January with the manoeuvres to remove the ATLAS end cup toroid (JTT) shielding.

Why start in LS2 something planned for LS3?

Mainly because the activation of the components in the JTT shielding region will be 25 times higher during LS3 than was during LS1 and so we should try to advance any work that is feasible to reduce future doses to personnel.

The transition between the LHC tunnel and the experimental caverns is the most difficult region in terms of accessibility of the full ring. Currently, there are a number of machine components belonging to the vacuum and beam instrumentation systems located at that precise place, just behind the Target Absorber for Secondaries.  Moving them to the experimental caverns (in the IP side of the TAS) would offer a safer environment for interventions, adding the possibility to operated them remotely and so reduce the workers exposition to radiation.

However, space in the experimental caverns is rare. Every millimetre is  taken when opening of the detectors for routine maintenance tasks . After more than one year of collaborative effort and some compromises, a solution was found to relocate the VAX. In the case of ATLAS, the first of the implications foreseen to host the future VAX being compatible with detector openings was the modification of the JTT shielding.

From the 14th to the 31st January the ATLAS JTT was removed thanks to the ATLAS and CERN Engineering department teams. The transport procedure had to be completely rethink as we did not had any more a not yet completely installed experiment as was the case in 2006. A new support structure and a crab system was installed to allow the removal of the 13 Tones casted iron and boride polyethylene shielding that today is already stored in CERN ISRs waiting for its final treatment.

The new JTT units are today under construction in Pakistan. HMC3, that already contributed to the ATLAS experiment under the supervision of PAEC, should deliver them before the end of LS2. The new pieces have an innovative design compatible with the VAX.

Always having in mind personnel safety, the ATLAS forward shielding blocks will be machined during LS2. This operation requires handling of close to 100T pieces.

From the CMS side work is also frenetic. The new support for the VAX will be already installed during LS2 allowing the relocation of other vacuum equipment, while the forward shielding will also be modified in prevision of the new VAX modules.

The new VAX for ATLAS and CMS is nowadays in its prototyping phase. A new vacuum chamber handling and support compatible with remote operations and the new layout is under construction, and will be thoroughly tested with the collaboration of different CERN groups: Experimental Areas, Vacuum, Transport, Survey and Mechatronics.

Constantinos Astreos (University of Liverpool)
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Accelerating News Readers Survey

With this survey we are trying to learn more about our audience and how we can improve in the future. It should take less than 5 minutes to complete. Thank you !