CERN Courier October 2018 Accelerators
Discover these and more – download the Electron–ion first chapter of every title for free. iopscience.org/books collider on Expanding PhysicsTM
IOP Expanding Physics IOP Expanding Physics IOP Expanding Physics IOP Expanding Physics An Introduction to A Short Course the horizon Key Nuclear Reaction Nuclear and Experiments Elementary Particle on Relativistic Particle Physics
Discoveries and consequences Phenomenology Heavy Ion Collisions Claude Amsler Hans Paetz gen. Schieck Philip G Ratcliffe Asis Kumar Chaudhuri The National Academy of Sciences in the US finds a compelling scientific case for an advanced collider that would reveal how visible matter emerges from fundamental quarks and gluons.
IOP Expanding Physics IOP Expanding Physics IOP Expanding Physics IOP Expanding Physics Protons and neutrons, the building blocks of nuclear matter, well as being integral to the agenda of nuclear physics today. In Effective Science The Foundations of Precise Dimensions Bias in Science constitute about 99.9% of the mass of all visible matter in the addition, the development of an EIC would advance accelerator Communication Electric Circuit Theory A history of units from 1791–2018 and Communication universe. In contrast to more familiar atomic and molecular science and technology in nuclear science; it would also benefit Malcolm Cooper A field guide A practical guide to surviving N R Sree Harsha matter, nuclear matter is also inherently complex because the other fields of accelerator-based science and society, from medi- Jim Grozier Anupama Prakash as a scientist Matthew Welsh D P Kothari interactions and structures in nuclear matter are inextricably cine through materials science to elementary particle physics.” Sam Illingworth Grant Allen mixed up: its constituent quarks are bound by gluons that also From a broader perspective, the versatile EIC will, for the first bind themselves. Consequently, the observed properties of nucle- time, be able to systematically explore and map out the dynamical ons and nuclei, such as their mass and spin, emerge from a com- system that is the ordinary QCD bound state, triggering a new plex, dynamical system governed by quantum chromodynamics area of study. Just as the advent of X-ray diffraction a century ago (QCD). The quark masses, generated via the Higgs mechanism, triggered tremendous progress in visualising and understanding only account for a tiny fraction of the mass of a proton, leaving the atomic and molecular structure of matter, and as the introduc- fundamental questions about the role of gluons in nucleons and tion of large-scale terrestrial and space-based probes in the last nuclei unanswered. two to three decades led to precision observational cosmology The underlying nonlinear dynamics of the gluon’s self-interac- with noteworthy findings, the EIC is foreseen to play a similarly Concise PhysicsTM tion is key to understanding QCD and fundamental features of the strong interactions such as dynamical chiral symmetry breaking
IOP Concise Physics A Morgan & Claypool Publication IOP Concise Physics A Morgan & Claypool Publication IOP Concise Physics A Morgan & Claypool Publication IOP Concise Physics A Morgan & Claypool Publication and confinement. Despite the central role of gluons, and the many EIC’s scientific goals: in brief Introduction to Beam Quantum Field Theory Entrepreneurship Logic for Physicists successes in our understanding of QCD, the properties and dynam- An electron–ion collider would answer core questions about strongly An arcane setting for explaining the world Dynamics in High-Energy for Physicists Nicolas A Pereyra ics of gluons remain largely unexplored. interacting matter: Electron Storage Rings Roberto Iengo A practical guide to move inventions from university to market • How are the sea quarks and gluons, and their spins, distributed Andrzej Wolski Positive evaluation Davide Iannuzzi in space and momentum inside the nucleon? How do the nucleon To address these outstanding puzzles in modern nuclear phys- properties emerge from quark and gluon interactions? ics, researchers in the US have proposed a new machine called • How do colour-charged quarks and gluons, and colourless jets, the Electron Ion Collider (EIC). In July this year, a report by interact with a nuclear medium? How do confined hadronic states the National Academies of Sciences, Engineering, and Medicine emerge from quarks and gluons? How do quark–gluon interactions commissioned by the US Department of Energy (DOE) posi- create nuclear binding? tively endorsed the EIC proposal. “In summary, the committee • How does a dense nuclear environment affect quarks and finds a compelling scientific case for such a facility. The science gluons, their correlations, and their interactions? What happens questions (see “EIC’s scientific goals: in brief”) that an EIC will to the gluon density in nuclei: does it saturate at high energy, answer are central to completing an understanding of atoms as giving rise to gluonic matter with universal properties in all nuclei, even the proton? Image credit: Jefferson Lab.
31
CCOct18_EIC_v4.indd 31 21/09/2018 13:34 CERNCOURIER www. V o l u m e 5 8 N u m b e r 8 O c t o b e r 2 0 1 8 CERN Courier October 2018 CERN Courier October 2018 Accelerators Accelerators JLab BNL Nuclear femtography to delve deep into nuclear matter
The way in which a nucleon or nucleus reveals experimentally reconstruct and constrain the itself in an experiment depends on the kinematic so-called Wigner functions – the quantities that regime being probed. A dynamic structure of encode the complete tomographic information quarks and gluons is revealed when probing and constitute a QCD “genetic map” of nucleons nucleons and nuclei at higher energies, or with and nuclei. The proposed centre-of-mass higher resolutions. Here, the nucleon transforms energies of the EIC (20–100 GeV, upgradable from a few-body system with its structure to 140 GeV) are strongly linked to the scales of energy dominated by the three valence quarks to a low x transverse momentum and spatial distributions regime where it is increasingly dominated by high x to probe in nucleons and nuclei, of the order
gluons generated through gluon radiation, as The internal quark and gluon structure of the ΛQCD, and hence do not require an energy-frontier discovered at the former HERA electron–proton proton grows more complex when probed at machine such as the LHC. collider at DESY. Eventually, the gluon density increasing centre-of-mass energies. (Credit: BNL.) Investigating gluons in nuclei instead of becomes so large that the gluon radiation is protons has multiple advantages. One is that polarised electron ion collider ring electron cooler source/injector balanced by gluon recombination, leading to unique opportunity to go far beyond the present they act as an efficient amplifier of the physics linac nonlinear features of the strong interaction. one-dimensional picture of nuclei and nucleons, of high gluon densities, which enhances the interaction point From the LHC and RHIC we learned that where the composite nucleon appears as a impact of nonlinear gluon interactions and neutrons and protons bound inside nuclei already bunch of fast-moving (anti-)quarks and gluons possibly leads to gluon saturation, also known eRHIC interaction point exhibit the collective behaviour that reveals whose transverse momenta or spatial extent as the colour glass condensate. An EIC has the electron collider ring QCD substructure under extreme conditions, are not resolved. Specifically, by correlating the potential to map the transition from a linear to booster ion source as initially seen with heavy-ion collisions. This information of the quark and gluon longitudinal a nonlinear regime in QCD and characterise the detector 2 electron source has triggered widespread interest in the study momentum component with their transverse relevant parameters governing this transition. electrons of the strong force in the context of condensed momentum and spatial distribution inside the Using polarisation, an EIC can also make quark ions hall D 12 GeV CEBAF matter physics, and the understanding that the nucleon, it will enable nuclear “femtography”. and gluon femtographic maps of the deuteron in detector 1 formation and evolution of this extreme phase Such femtographic images will provide, for its dumbbell and doughnut shapes – revealing of QCD matter is dominated by the properties of the first time, insight into the QCD dynamics whether this nuclear structure impacts the ions from AGS halls A, B, C gluons at high density. inside hadrons, such as the interplay between quark–gluon polarisation or quark-flavour Fig. 1. Two US labs are bidding to host the EIC: Brookhaven National Laboratory, which would add an electron storage ring to its An electron–ion collider (EIC) will open up the sea quarks and gluons. The ultimate goal is to dependence of nucleon properties. RHIC facility (left), and Jefferson Lab, which would use its upgraded CEBAF complex as an electron injector (right).
transformative role in our understanding of the rich variety of secondary focus to even detect particles with angles and rigidi- an active detector R&D programme is ongoing, with key tech- structures at the subatomic scale. ties near the main ion beams. To quickly separate both beams nology developments including large, low-mass high-resolution Oceania 1% Africa 2% Two pre-conceptual designs for a future high-energy and high- South America 3% into their respective beam lines while providing the space and tracking detectors and compact, high-resolution calorimetry and luminosity polarised EIC have evolved in the US using exist- geometry required by the physics programme, both the BNL and particle identification. ing infrastructure and facilities (figure 1). One proposes to add Asia 18% JLab pre-conceptual designs incorporate a large crossing angle an electron storage ring to the existing Relativistic Heavy-Ion of 20–50 mrad. This achieves a hermetic acceptance and also has The path ahead Collider (RHIC) complex at Brookhaven National Laboratory the advantage of avoiding the introduction of separator dipoles A high-energy and high-luminosity electron–ion collider capable (BNL) to enable electron–ion collisions. The other pre-concep- in the detector vicinity that would generate huge amounts of of a versatile range of beam energies, polarisations and ion species tual design proposes a new electron and ion collider ring at Jef- synchrotron radiation. The detrimental effects of this crossing is the only tool to precisely image the quarks and gluons, and their ferson Laboratory (JLab), utilising the 12 GeV upgraded CEBAF angle on the luminosity and beam dynamics would be compen- interactions, and to explore the new QCD frontier of strong colour facility (CERN Courier March 2018 p19) as the electron injector. sated by a crab-crossing radio-frequency scheme, which has many fields in nuclei – to understand how matter at its most fundamental The requirement that the EIC has a high luminosity (approxi- North America 43% Europe 33% synergies with the LHC high-luminosity upgrade (CERN Courier level is made. In recognition of this, in 2015 the Nuclear Science mately 1034 cm–2 s–1) demands new ways to “cool” the hadrons, May 2018 p18). Advisory Committee (NSAC), advising the DOE, and the National beyond the capabilities of current technology. A novel, coherent Modern particle detector and readout systems will be at the Science Foundation (NSF) recommended an EIC in its long-range electron-cooling technique is under development at BNL, while heart of the EIC, driven by the demand for high precision on plan as the highest priority for new facility construction. Subse- JLab is focussing on the extension of conventional electron cool- Fig. 2. Distribution per continent of institutions that are particle detection and identification of final-state particles. A quently, a National Academy of Sciences (NAS) panel was charged ing techniques to significantly higher energy and to use bunched members of the EIC user group. multipurpose EIC detector needs excellent hadron–lepton– to review both the scientific opportunities enabled by an EIC and electron beams for the first time. The luminosity, polarisation photon separation and characterisation, full acceptance, and the benefits to other fields of science and society, leading to the and cooling requirements are coupled to the existence and fur- EIC accelerator parameters, and extreme demands on the kine- to go beyond the requirements of most particle-physics detec- report published in July. ther development of high brilliance (polarised) electron and ion matic coverage for measurements, makes it par ticularly challeng- tors when it comes to identifying pions, kaons and protons. This The NAS report strongly articulates the merit of an EIC, sources, benefitting from the existing experience at JLab, BNL ing to integrate into the interaction regions of the main detector means that different particle-identification technologies have also citing its role in maintaining US leadership in accelerator and collaborating institutions. and dedicated detectors along the beamline in order to register all to be integrated over a wide rapidity range in the detector to science. This could be the basis for what is called a Critical The EIC is foreseen to have at least two interaction regions and particles down to the smallest angles. The detectors would be fully cover particle momenta from a couple of 100 MeV to several Decision-0 or Mission Need approval for the DOE Office of thus two large detectors. The physics-driven requirements on the integrated in the accelerator over a region of about 100 m, with a tens of GeV. To address the demands on detector requirements, Science, setting in motion the process towards formal project
32 33
CCOct18_EIC_v4.indd 32 21/09/2018 13:35 CCOct18_EIC_v4.indd 33 21/09/2018 13:35 CERNCOURIER www. V o l u m e 5 8 N u m b e r 8 O c t o b e r 2 0 1 8 CERN Courier October 2018 CERN Courier October 2018 Accelerators Accelerators JLab BNL Nuclear femtography to delve deep into nuclear matter
The way in which a nucleon or nucleus reveals experimentally reconstruct and constrain the itself in an experiment depends on the kinematic so-called Wigner functions – the quantities that regime being probed. A dynamic structure of encode the complete tomographic information quarks and gluons is revealed when probing and constitute a QCD “genetic map” of nucleons nucleons and nuclei at higher energies, or with and nuclei. The proposed centre-of-mass higher resolutions. Here, the nucleon transforms energies of the EIC (20–100 GeV, upgradable from a few-body system with its structure to 140 GeV) are strongly linked to the scales of energy dominated by the three valence quarks to a low x transverse momentum and spatial distributions regime where it is increasingly dominated by high x to probe in nucleons and nuclei, of the order
gluons generated through gluon radiation, as The internal quark and gluon structure of the ΛQCD, and hence do not require an energy-frontier discovered at the former HERA electron–proton proton grows more complex when probed at machine such as the LHC. collider at DESY. Eventually, the gluon density increasing centre-of-mass energies. (Credit: BNL.) Investigating gluons in nuclei instead of becomes so large that the gluon radiation is protons has multiple advantages. One is that polarised electron ion collider ring electron cooler source/injector balanced by gluon recombination, leading to unique opportunity to go far beyond the present they act as an efficient amplifier of the physics linac nonlinear features of the strong interaction. one-dimensional picture of nuclei and nucleons, of high gluon densities, which enhances the interaction point From the LHC and RHIC we learned that where the composite nucleon appears as a impact of nonlinear gluon interactions and neutrons and protons bound inside nuclei already bunch of fast-moving (anti-)quarks and gluons possibly leads to gluon saturation, also known eRHIC interaction point exhibit the collective behaviour that reveals whose transverse momenta or spatial extent as the colour glass condensate. An EIC has the electron collider ring QCD substructure under extreme conditions, are not resolved. Specifically, by correlating the potential to map the transition from a linear to booster ion source as initially seen with heavy-ion collisions. This information of the quark and gluon longitudinal a nonlinear regime in QCD and characterise the detector 2 electron source has triggered widespread interest in the study momentum component with their transverse relevant parameters governing this transition. electrons of the strong force in the context of condensed momentum and spatial distribution inside the Using polarisation, an EIC can also make quark ions hall D 12 GeV CEBAF matter physics, and the understanding that the nucleon, it will enable nuclear “femtography”. and gluon femtographic maps of the deuteron in detector 1 formation and evolution of this extreme phase Such femtographic images will provide, for its dumbbell and doughnut shapes – revealing of QCD matter is dominated by the properties of the first time, insight into the QCD dynamics whether this nuclear structure impacts the ions from AGS halls A, B, C gluons at high density. inside hadrons, such as the interplay between quark–gluon polarisation or quark-flavour Fig. 1. Two US labs are bidding to host the EIC: Brookhaven National Laboratory, which would add an electron storage ring to its An electron–ion collider (EIC) will open up the sea quarks and gluons. The ultimate goal is to dependence of nucleon properties. RHIC facility (left), and Jefferson Lab, which would use its upgraded CEBAF complex as an electron injector (right).
transformative role in our understanding of the rich variety of secondary focus to even detect particles with angles and rigidi- an active detector R&D programme is ongoing, with key tech- structures at the subatomic scale. ties near the main ion beams. To quickly separate both beams nology developments including large, low-mass high-resolution Oceania 1% Africa 2% Two pre-conceptual designs for a future high-energy and high- South America 3% into their respective beam lines while providing the space and tracking detectors and compact, high-resolution calorimetry and luminosity polarised EIC have evolved in the US using exist- geometry required by the physics programme, both the BNL and particle identification. ing infrastructure and facilities (figure 1). One proposes to add Asia 18% JLab pre-conceptual designs incorporate a large crossing angle an electron storage ring to the existing Relativistic Heavy-Ion of 20–50 mrad. This achieves a hermetic acceptance and also has The path ahead Collider (RHIC) complex at Brookhaven National Laboratory the advantage of avoiding the introduction of separator dipoles A high-energy and high-luminosity electron–ion collider capable (BNL) to enable electron–ion collisions. The other pre-concep- in the detector vicinity that would generate huge amounts of of a versatile range of beam energies, polarisations and ion species tual design proposes a new electron and ion collider ring at Jef- synchrotron radiation. The detrimental effects of this crossing is the only tool to precisely image the quarks and gluons, and their ferson Laboratory (JLab), utilising the 12 GeV upgraded CEBAF angle on the luminosity and beam dynamics would be compen- interactions, and to explore the new QCD frontier of strong colour facility (CERN Courier March 2018 p19) as the electron injector. sated by a crab-crossing radio-frequency scheme, which has many fields in nuclei – to understand how matter at its most fundamental The requirement that the EIC has a high luminosity (approxi- North America 43% Europe 33% synergies with the LHC high-luminosity upgrade (CERN Courier level is made. In recognition of this, in 2015 the Nuclear Science mately 1034 cm–2 s–1) demands new ways to “cool” the hadrons, May 2018 p18). Advisory Committee (NSAC), advising the DOE, and the National beyond the capabilities of current technology. A novel, coherent Modern particle detector and readout systems will be at the Science Foundation (NSF) recommended an EIC in its long-range electron-cooling technique is under development at BNL, while heart of the EIC, driven by the demand for high precision on plan as the highest priority for new facility construction. Subse- JLab is focussing on the extension of conventional electron cool- Fig. 2. Distribution per continent of institutions that are particle detection and identification of final-state particles. A quently, a National Academy of Sciences (NAS) panel was charged ing techniques to significantly higher energy and to use bunched members of the EIC user group. multipurpose EIC detector needs excellent hadron–lepton– to review both the scientific opportunities enabled by an EIC and electron beams for the first time. The luminosity, polarisation photon separation and characterisation, full acceptance, and the benefits to other fields of science and society, leading to the and cooling requirements are coupled to the existence and fur- EIC accelerator parameters, and extreme demands on the kine- to go beyond the requirements of most particle-physics detec- report published in July. ther development of high brilliance (polarised) electron and ion matic coverage for measurements, makes it par ticularly challeng- tors when it comes to identifying pions, kaons and protons. This The NAS report strongly articulates the merit of an EIC, sources, benefitting from the existing experience at JLab, BNL ing to integrate into the interaction regions of the main detector means that different particle-identification technologies have also citing its role in maintaining US leadership in accelerator and collaborating institutions. and dedicated detectors along the beamline in order to register all to be integrated over a wide rapidity range in the detector to science. This could be the basis for what is called a Critical The EIC is foreseen to have at least two interaction regions and particles down to the smallest angles. The detectors would be fully cover particle momenta from a couple of 100 MeV to several Decision-0 or Mission Need approval for the DOE Office of thus two large detectors. The physics-driven requirements on the integrated in the accelerator over a region of about 100 m, with a tens of GeV. To address the demands on detector requirements, Science, setting in motion the process towards formal project
32 33
CCOct18_EIC_v4.indd 32 21/09/2018 13:35 CCOct18_EIC_v4.indd 33 21/09/2018 13:35 CERNCOURIER www. V o l u m e 5 8 N u m b e r 8 O c t o b e r 2 0 1 8 CERN Courier October 2018 CERN Courier October 2018 ccelerators Faces & Places R D, engineering and design, and construction. The DOE r i et al. ur. h s. . Office of Nuclear Physics is already supporting increased e i o et al. ur. h s. . efforts towards the most critical generic EIC-related accelerator e i et al. e . art. Nucl. ci. research and design. eu Co or io ur. h s. . C A p p o i n t m e n t But the EIC is by no means a US-only facility (fi gure 2). A large international physics community, comprising more than 800 R s m members from 150 institutions in 30 countries and six continents, Un collisionneur électron-ion se profi le à l’horizon New director for particle physics at RAL is now energised and working on the scientifi c and technical chal- D Newbold lenges of the machine. An EIC users group (www.eicug.org) was Des acad mies nationales am ricaines ont soulign le tr s grand Dave Newbold from the University of Bristol technicians working across a number of formed in late 2015 and has held meetings at the University of intérêt scientifi que qu’aurait un collisionneur électron-ion de has been appointed director of the particle areas. It currently hosts two major research California at Berkeley, Argonne National Laboratory, and Trieste, pointe capable de révéler comment la matière se forme à partir physics department for the UK’s Science facilities – the ISIS neutron and muon source Italy, with the most recent taking place at the Catholic University de quarks et de gluons. Deux pré-études de conception ont été and Technology Facilities Council (STFC), and the Central Laser Facility – and is a of America in Washington, DC in July. The EIC user group meet- proposées, l’une au Laboratoire national de Brookhaven et l’autre based at the Rutherford Appleton Laboratory Tier-1 node of the CERN–UK distributed ings in Trieste and Washington included presentations of US and au Laboratoire Jefferson. Les exigences pour un accélérateur de (RAL) in Oxfordshire. Previously head computing grid, GridPP. of particle physics at the University of Among his goals as director of the particle international funding agency perspectives, further endorsing the ce type repousseraient les frontières de la technologie actuelle. Bristol, Newbold is a member of the CMS physics department, Newbold intends to strong international interest in the EIC. Such a facility would have Tout comme la diffraction des rayons X, qui a conduit, il y a un collaboration and currently leads the UK’s focus on integrating RAL more closely capabilities beyond all previous electron-scattering machines in siècle, à des progrès considérables dans la visualisation de la CMS upgrade programme. He is also trigger with UK universities and to strengthen the US, Europe and Asia, and would be the most sophisticated structure atomique et moléculaire de la matière, un collisionneur and data-acquisition coordinator for the relations with CERN and other international and challenging accelerator currently proposed for construction électron-ion pourrait marquer un tournant dans notre international Deep Underground Neutrino laboratories. “RAL particle physics has in the US. compréhension de la QCD et des caractéristiques fondamentales Experiment based in the US. Succeeding Dave a world-class team, backed with all the de l’interaction forte. Wark of the University of Oxford, Newbold facilities of the national lab,” he says. “With took up the new position at RAL in September. Dave Newbold took up his new role at LHC upgrade construction now starting, ● F rther reading Funded and managed by the STFC, Rutherford in September. we have an intense few years of activity N io e ie o ie e E i eeri e i i e El e Caroline Aschena er Broo haven National aboratory and RAL supports the UK particle physics coming up across the UK institutes – we’ll oi Rolf Ent e erson ab programme by providing capabilities that recently marked its 60th anniversary (CERN be supporting that, and developing plans for complement and go beyond what can be done Courier March 2018 p46) and comprises a number of new projects in particle physics. in individual universities. The laboratory more than 1000 researchers, engineers and I’m looking forward to the challenge.” We are in the loop A w A r d s You know what Friedrich Wilhelm Bessel award for Higgs phenomenology you want to detect: Theorist Michael Spannowsky of the Michael Spannowsky of Durham University. Institute for Particle Physics Phenomenology at Durham University in the UK has been research project with colleagues at a - X-rays awarded a Friedrich Wilhelm Bessel German institution. Research Award in recognition of his work UniversityDurham Spannowsky’s research has contributed - Gamma-rays on Higgs-boson phenomenology. to the design of novel reconstruction and The award recognises a recipient’s analysis strategies to improve measurements - Neutrons outstanding research record and covers of the top- and bottom-quark Yukawa a number of disciplines, not just physics. couplings and the Higgs self-interaction. - Particles The Alexander von Humboldt Foundation He will use his award to collaborate with grants about 20 awards per year and winners colleagues at the University of Tübingen in receive funding to enable them to spend southwest Germany on research into dark up to a year collaborating on a long-term matter and Higgs phenomenology.
Flow Monitoring by ELETTA. D Bushmire year’s NSREC, which took place in Kona, Extreme reliability on your NSREC accolade Hawaii, on 16–20 July. cooling systems. The paper (doi:10.1109/TNS.2017. for radiation paper 2760629), which summarises the work Safety on critical applications. of a collaborative effort between CERN and the universities of Padova, Salento, Supplier for more than Federico Faccio from CERN has received Udine and Vanderbilt, marks an important the Outstanding Conference Paper Award contribution to the understanding of how 40 years at CERN and other SCIONIX Holland B.V. for the 2017 IEEE Nuclear and Space radiation influences the behaviour of particle accelerators. Tel. +31 30 6570312 Radiation Effects Conference (NSREC), modern CMOS processes. Faccio leads a Fax. +31 30 6567563 We know how to as lead author of the paper titled “Influence small team of experts at CERN studying + www.eletta.com Email. [email protected] of LDD spacers and H transport on the radiation effects in microelectronics, for [email protected] build your detectors total ionising-dose response of 65 nm instance identifying commercially available www.scionix.nl MOSFETs irradiated to ultra-high doses”. Faccio (far left) together with co-authors processes for use in the extreme radiation The prestigious award was presented at this from the other collaborating institutes. environment of the LHC detectors.
34 35
CCOct18_EIC_v4.indd 34 21/09/2018 13:36 CCOct18_Faces&Places_v3.indd 35 21/09/2018 13:43 CERNCOURIER www. V o l u m e 5 8 N u m b e r 8 O c t o b e r 2 0 1 8