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The 2019 edition of the “Electron-Ion Collider User Group Meeting” will take place from 22 to 26 of July at the National School of Chemistry in Paris, and will be organized jointly between the Institut de Physique Nucleaire d’Orsay (CNRS/IN2P3) and the CEA-Saclay Nuclear Physics Department.
The meeting will feature topical sessions on new advances in the physics as well as accelerator and detector R&D related to the Electron-Ion Collider. Discussions on the next steps for the realization of the project will also be part of the agenda.
The Electron-Ion Collider User Group (EICUG) consists of more than 800 physicists from over 170 laboratories and universities from around the world who are working together to realize a powerful new facility in the United States with the aim of studying the particles, gluons, which bind all the observable matter in the world around us. This new facility, known as the Electron-Ion Collider (EIC), would collide intense beams of spin-polarized electrons with intense beams of both polarized nucleons and unpolarized nuclei from deuterium to uranium. Detector concepts are now being developed to detect the high-energy scattered particles as well as the low-energy debris as a means to definitively understand how the matter we are all made of is bound together.
Excellent particle identification (PID) is an essential requirement for a future Electron-Ion Collider (EIC) detector. Identification of the hadrons in the final state is critical to study how different quark flavors contribute to nucleon properties. A detector based on the Detection of Internally Reflected Cherenkov light (DIRC) principle, with a radial size of only a few cm, is a great solution for those requirements. The R&D process performed by the EIC PID consortium (eRD14) is focused on designing a High-Performance DIRC that would extend the momentum coverage well beyond the state-of-the-art. A key component to reach such a performance is a special 3-layer compound lens. The status of the High-Performance DIRC R&D for the EIC detector will be presented, with a focus on the detailed Monte Carlo simulation results and performance tests of two 3-layer lens prototypes.
The Electron-Ion Collider (EIC) will cover a broad range in pseudorapidity,−4.5 ≤ η ≤ 4.5. To reconstruct particle tracks and momenta at all η values, gas tracking detectors with good momentum resolution will be needed in the forward (η > 1.0), backward (η < −1.0), and central (|η| ≤ 1.0) regions. The EIC handbook recommends tracking detectors capable of achieving momentum resolutions from σ p /p ∼ (0.05%) p + 1.0% in the central region, to σ p /p ∼ (0.1%) p + 2.0% for the forward/backward regions. Additionally, gas based tracking detectors can also be used for particle ID. Presented in this poster is a brief summary of selected tracking detectors which are being investigated for use at an EIC in the central and forward/backward η regions that are based on micro-pattern gas detector technologies.
The 2015 Nuclear Science Advisory Committee Long Rang Plan identified the need for an electron-ion collider (EIC) facility as a gluon microscope with capabilities beyond those of any existing accelerator complex. To reach the required high energy, high luminosity, and high polarization, the eRHIC design, based on the existing heavy ion and polarized proton collider RHIC, adopts a very small beam sizes at the interaction points, a high collision repetition rate, and a novel hadron cooling scheme. A full crossing angle of 25 mrad and crab cavities for both electron and proton rings are required. In this poster, we will review the beam-beam interaction related eRHIC design parameters, and compare them with the previous and existing colliders. Then we present our numeric simulation results for eRHIC beam-beam interaction. In the end we present the simulation challenges for eRHIC beam-beam interaction study, and our methods to address them.
A polarized beam dynamics software tool is developed at BNL, which is routinely used for on-going polarization studies regarding the EIC, at both BNL and Jefferson Lab. These developments are being supported and tightly benchmarked over the years in the general R/D context of RHIC collider spin physics program. They further lean on tight collaborations with others, in the frame FOA and SBIR DOE programs, and NY State programs. As part of the EIC R/D dynamics, these activities aim at responding to the DOE recommendations in the matter of software tools: "EIC will be one of the most complex collider accelerators ever to be built. [...] Technical Challenges for EIC [include] Beam and spin dynamics and benchmarking of simulation tools [...]. State of the Art Accelerator Technology for EIC [must address] Simulation Codes: Benchmarking of realist EIC simulation tools against available data needs to be aggressively pursued."[1]. The present contribution to eicug2019 is based on recent detailed publications in journals, conferences, workshops, and as lab notes, regarding : RHIC and injectors; eRHIC and JLEIC; rapid-cycling synchrotron methods; BNL-Cornell's CBETA and ERLs.
[1] Manouchehr Farkhondeh, "DOE Support to EIC Accelerator R&D and FOA Landscape", slides 9, 10; EIC Accelerator Collaboration Meeting 2018, Thomas Jefferson Lab, Oct. 29, 2018. https://www.jlab.org/indico/event/281/session/5/contribution/15
The sPHENIX Collaboration at RHIC is upgrading the PHENIX detector in a way that will enable a comprehensive measurement of jets in relativistic heavy ion collisions. The upgrade will give the experiment full azimuthal coverage within a pseudorapidity range of $-1.1 < \eta < 1.1$. Parts of the apparatus might one day be the basis of an EIC experiment at BNL.
We have made significant progress with the readout of our calorimeters, which work with a "classic" triggered-event paradigm. At the same time, we have developed the prototype readout electronics for the Time Projection Chamber, which will operate in streaming, or trigger-less, readout mode. The entire tracking system, which consists of 3 detectors, will eventually be read out in a streaming mode.
We will present an overview of the DAQ system and the choices and current status of the readout electronics, firmware, and software components, especially with the detectors read out in a streaming mode, and discuss potential paths forward for the readout at the EIC.
Along with the development of Deep Inelastic Scattering experiments, there has been a growing interest to fully understand the nucleons structure. In particular, there is nowadays a great interest in the decomposition of its total angular momentum into orbital angular momentum (OAM) and intrinsic spin, as well as identifying contributions from valence quarks, sea quarks and gluons.
The most common decompositions of OAM are the Jaffe-Manohar (canonical) and Ji (kinetic) decompositions, which differ in the way contributions are attributed to either quarks or gluons. Using perturbation theory, explicit one-loop calculations have found that the difference between such decompositions vanishes in QED. We show within the scalar diquark model in QED that the discrepancy appears at two-loop level, supporting the interpretation of such inequality as originating from the torque exerted by the spectator system on the struck quark.
The early-time evolution of the system generated in ultra-relativistic heavy ion collisions is dominated by the presence of strong color fields known as Glasma fields. These can be described following the classical approach embodied in the Color Glass Condensate effective theory, which approximates QCD in the high gluon density regime. In this framework we perform an analytical first-principles calculation of the two-point correlator of the divergence of the Chern-Simons current at proper time $\tau=0^+$, which characterizes the early fluctuations of axial charge density in the plane transverse to the collision axis. This object plays a crucial role in the description of anomalous transport phenomena such as the Chiral Magnetic Effect. We compare our results to those obtained under the Glasma Graph approximation, which assumes gluon field correlators to obey Gaussian statistics. While this approach proves to be equivalent to the exact calculation in the limit of short transverse separations, important differences arise at larger distances, where our expression displays a remarkably slower fall-off than the Glasma Graph result ($1/r^4$ vs.\ $1/r^8$ power-law decay). This discrepancy emerges from the non-linear dynamics mapping the Gaussianly-distributed color source densities onto the Glasma fields, encoded in the classical Yang-Mills equations. Our results support the conclusions reached in a previous work, where we found indications that the color screening of correlations in the transverse plane occurs at relatively large distances.
In 2018, an EIC Detector Design Study Group was formed to start considering in detail how an EIC detector could be built around the sPHENIX solenoid, formerly used by the BaBar experiment. A series of studies examining the design and physics performance for select options of calorimetry, tracking, and particle identification covering -4 to +4 in pseudorapidity has already been performed, and further studies are ongoing. The design ideas that have been explored so far will be presented, and the many opportunities for further contributions will be described.
The discovery of the relation between the quantum energy-momentum tensor (EMT) and General Parton Distributions [1, 2] provides a unique way to study the EMT of the nucleon [3,4].
It was shown that the expectation value of the EMT for an unpolarized proton target in the Breit frame has the same structure as that of an anisotropic perfect fluid density [5,6]. Thus, in this case one can identify terms related to the internal energy and transverse/radial pressure inside a proton. We illustrate these results using current phenomenological knowledge of the EMT form factors.
References
[1] X.-D. Ji; Phys.Rev. D55 (1997) 7114-7125.
[2] X.-D. Ji; Phys.Rev.Lett. 78 (1997) 610-613.
[3] M.V. Polyakov; Phys.Lett. B555 (2003) 57-62.
[4] M. Burkardt; Int.J.Mod.Phys. A18 (2003) 173-208.
[5] M.V. Polyakov, P. Schweitze; Int.J.Mod.Phys. A33 (2018) 1830025
[6] C. Lorcé, H. Moutarde, A.P. Trawiński; Eur.Phys.J. C79 (2019) 89
Hard processes in proton–nucleus or electron-nucleus collisions are powerful tools to investigate cold nuclear matter effects. Among various QCD processes, the Drell-Yan (DY) mechanism in proton-nucleus collisions and the production of hadrons in semi-inclusive DIS (SIDIS) allow for probing parton distribution functions in nuclei as well as parton energy loss effects.
In this talk, we investigate the production of Drell-Yan and quarkonium production in proton-nucleus collisions, from SPS to LHC collision energies. The rapidity dependence of DY lepton pair production at low collision energies highlights the role of parton energy loss processes and would eventually allow for the precise extraction of the transport coefficient of nuclear matter. This, however, would only be possible once nuclear parton densities are better constrained from DY production at LHC energies and from measurements in an electron-ion collider. Constraints on the transport coefficient from the transverse momentum broadening of various probes, either DY or quarkonium production in hadron-nucleus collisions or from hadron production in SIDIS, will also be discussed.
While Compton Polarimetry has been successfully used for electron polarimetry at several facilities already, some parameters need to be carefully taken into account to be able to handle the large beam current available at an EIC.
I will present a preliminary design for the Compton Polarimeter currently focusing on detecting the scattered electron in the case of the JLEIC machine.
In this talk I will discuss the constraints imposed by Poincaré symmetry on the gravitational form factors appearing in the Lorentz decomposition of the energy-momentum tensor matrix elements. By adopting a distributional approach, one can prove non-perturbatively that the zero momentum transfer limits of the leading two form factors are completely independent of the spin of the states in the matrix elements. Expressing these form factors in terms of generalised parton distributions, this implies that the corresponding linear and angular momentum sum rules are in fact spin-universal.
Gravitational form factors (GFFs) characterize the distribution of energy, angular momentum, and forces within a hadron, analogous to the charge and magnetization distributions encoded by electromagnetic form factors. GFFs can experimentally be extracted from generalized parton distributions (GPDs), which are themselves measured in hard exclusive reactions such as deeply virtual Compton scattering (DVCS). We present a Poincare-covariant calculation of GPDs and GFFs for light mesons and the proton in the Nambu-Jona-Lasinio (NJL) model of quantum chromodynamics (QCD), and comment on the physical interpretation of the GFFs.
With the design of an EIC, advancements in theory and further development of phenomenological tools, we are now preparing for the next step in subnuclear tomographic imaging. The collider's large range of center-of-mass energy, in combination with very high luminosity and polarization of both the lepton and the hadron beams, will open a unique opportunity for very high precision measurements of both cross sections and spin-asymmetries. This will allow us for a detailed investigation of the partonic substructure of hadrons in multi-dimensions, as well as addressing the role of orbital angular momentum with respect to the nucleon spin.
Generalized parton distributions (GPDs) describe the multi-dimensional partonic structure of a nucleon in coordinate space, providing new information about the internal dynamics of quarks and gluons. Extraction of GPDs from hard exclusive processes and all related probes, is a pillar of the EIC science program.
We will highlighting key measurements, experimental challenges and present the current status and near-future plans to assess the EIC's expected impact over the current knowledge of GPDs.
A future electron-ion collider (EIC) with forward detectors would allow for measurements of coherent production of two vector mesons on proton and deuteron targets. In kinematics where the two vector mesons are separated by a large rapidity gap, one vector meson is produced at large transverse momenta and the other is transversily polarized, this process can probe the transversity generalized parton distributions of the respective targets. We show estimates for cross sections of the $\gamma^* N \rightarrow \rho \rho N'$, $\gamma^* d \rightarrow \rho \omega N$ and $\gamma^* D \rightarrow \rho \phi N$ processes at EIC kinematics, illustrating the feasibility of these measurements.
Generalised Parton Distributions (GPDs) are a key point of the EIC physics case as they encode the 3D structure of hadrons. Contrary to the usual Parton Distribution Functions (PDFs) they have to obey a certain number of theoretical properties coming from first principle considerations. Both extraction and modelling of GPDs must therefore fulfil these criteria, especially at a time when experimental uncertainties are expected to de significantly reduced. We will present in this talk a approach based on Lightfront wave functions which allows one to fulfil a priori all the theoretical constraints required to get GPDs (models or extractions) consistent with all known theoretical constraints.
We will consider quarkonium production in proton-proton and lepton-proton collisions, within a TMD approach. We will discuss the relative role of the NRQCD color-singlet and color-octet production mechanisms both in the unpolarized cross section and in the transverse single-spin asymmetries. Focus will be put on linearly polarized gluons in unpolarized and transversely polarized targets as well as on the gluon Sivers function. Their process dependence will be also addressed.
Most states in QCD decay strongly to multi-hadron scattering states. In this talk I will review recent progress in determining the spectrum of hadrons using lattice QCD, where the resonant nature of the states is implemented exactly. Emphasis will be placed in low-lying resonances in the light mesonic sector. Lastly, I will discuss how we may be able to study structural information of these states as well as their baryonic counterparts.
The Dyson-Schwinger/Bethe-Salpeter approach provides insight into many connected problems in QCD, proving to be especially powerful in describing processes that are dominated by chiral symmetry and its dynamical breaking. Being formulated in the continuum it avoids some of the difficulties encountered on the Lattice (e.g. chiral quarks etc) at the cost of having to introduce truncations.
I will discuss some of these truncations and how their extension leads to an improved understanding of the (spectrum of) hadrons, not only as concerns mesons and baryons but also exotic states such as tetraquarks.
Furthermore, I will report on recent progress in the generalization of these studies to finite temperature.
A striking feature of the strong interaction is its emergent 1-GeV mass-scale, as exhibited in the masses of protons and neutrons and numerous other hadronic bound states. In sharp contrast, the energy needed to hold the gluons and quarks within the Nambu-Goldstone Bosons, such as the pion and kaon, is not so readily apparent. Even if both quarks and gluons acquire mass dynamically, in all hadrons, the pion ends up near-massless, and the kaon ends up acquiring just half the 1-GeV mass scale. A coherent effort in QCD phenomenology and continuum calculations, in exa-scale computing as provided by Lattice QCD, and in experiments are required to make progress in understanding the origins of these disparate masses and the distribution of that mass within them. We compare the unique capabilities foreseen at an EIC with those of HERA, and describe a few key experimental measurements at an EIC that can be expected to deliver far-reaching insights into the dynamical generation of mass leading to apparently mysterious differences between pion, kaon and proton masses.
Nuclear dynamics at short distances among nucleons is one of the most outstanding phenomena in nuclear physics, where understanding the role of QCD in generating nuclear forces is important for uncovering the underlying physics of Short-Range Correlations (SRCs). In recent years, SRCs has been observed from light to heavy nuclei using fixed target experiments at Jefferson lab via high energy electron-nucleus scattering. In this talk, I will talk about opportunities and challenges of studying SRCs using light and heavy nuclei at high energy collider experiments, e.g., the current Relativistic-Heavy-Ion-Collider (RHIC) facility at Brookhaven National Lab and a future US based facility of Electron-Ion Collider (EIC). Based on the STAR experiment at RHIC and its upcoming forward upgrades, the ultra-peripheral collisions from nucleus-nucleus to proton- (deuteron-) nucleus can provide new insights into the short-range dynamics in nuclei and further constrains to the nuclear Parton Distribution Functions. Furthermore, the designs of the interaction region and the forward detectors R&D at an EIC would greatly benefit from these accessible studies.
Recently studies of the form factors of the energy-momentum tensor attracted significant interest in theory and experiment. The recent developments are reviewed and perspectives for the EIC are discussed.
The capability of accelerating a high-intensity polarized $^{3}$He ion beam would provide an effective polarized neutron beam for the study of new high-energy QCD studies of nucleon structure. This development is essential for the future Electron Ion Collider, which could use a polarized $^{3}$He ion beam to probe the spin structure of the neutron. The proposed polarized $^{3}$He ion source is based on the Electron Beam Ion Source (EBIS) currently in operation at Brookhaven National Laboratory. $^{3}$He gas would be polarized within the 5 T field of the EBIS solenoid via Metastability Exchange Optical Pumping (MEOP) and then pulsed into the EBIS vacuum and drift tube system where the $^{3}$He will be ionized by the 10 Amp electron beam. The goal of the polarized $^{3}$He ion source is to achieve $2.5 \times 10^{11}$ $^{3}$He$^{++}$/pulse at 70% polarization. An upgrade of the EBIS is currently underway. An absolute polarimeter and spin-rotator is being developed to measure the $^{3}$He ion polarization at 6 MeV after initial acceleration out of the EBIS. The source is being developed through collaboration between BNL and MIT.
The EIC physics goals require high luminosity and a full-acceptance detector. In order to meet these goals, the interaction region design needs to address large asymmetries between the ion and electron beams, and the presence of collision products traveling near the ion beam downstream from the IP. Since it is still not possible to separate all the collision products of interest prior to the ion beam focusing elements, large aperture quadrupoles are required allowing detection and momentum analysis further downstream. The resulting IR layout needs to integrate accelerator and detector elements over a much longer distance from the IP than is typical of other colliders. In addition, two separate beamlines are required to independently adjust the electron and ion energies. Since the crossing angle is limited by the complexity of the associated crab cavity system, the ion beam quadrupoles need to be radially compact and contain or correct the fringe field on the path of the electron beam to minimize the synchrotron radiation background in the detector. Finally, large functions make the beam very sensitive to magnet misalignments and multipole components. This should also be addressed by the quadrupole design to minimize the space allocated to correction elements in a tightly packed IR. This presentation will discuss the current status of the IR magnet technologies and designs under consideration for eRHIC and JLEIC to address the physics requirements while meeting space and background radiation constraints.
The Jefferson Lab Electron Ion Collider (JLEIC) is a proposed new nuclear physics facility designed to deliver high luminosity and high polarization electron-ion collisions. JLEIC employs high repetition rate collisions of short low emittance bunches to achieve the electron ion luminosity goal of 10^{33}-10^{34}cm^{-2}s^{-1} over a wide range of center-of-mass energy. With a growing physics interest, a positron-ion collision scheme is under study for JLEIC. The JLEIC positron-ion scheme will use CEBAF as the positron injector with minimal modification, so the Polarized Electrons for Polarized Positrons (PEPPo) based positron generation scheme is chosen. The major challenge of this scheme is to generate the polarized positron bunch trains with the time structure and peak beam current required for the injection/top-off of the electron collider ring. In this talk, we will address the details of this scheme, with the focus on the positron beam formation, as well as the preliminary collider parameters optimized for positron-ion luminosity.
We present the progress and approach of the eRHIC RCS electron injector development. The RCS is designed to deliver 5, 10 and 18 GeV polarized electrons to the eRHIC storage ring. The approach involves using a special symmetry to avoid polarization losses due to intrinsic spin resonances during the acceleration cycle and a robust spin imperfection correction scheme to correct residual imperfection spin resonances. The design approach involves using newly developed spin-orbit fitting tools to quickly optimize the lattice, followed by direct spin-orbit tracking to verify the performance. The base design has matured to a level which accounts for the all the existing and future obstructions in the tunnel and should fit comfortably in the future eRHIC accelerator complex.
The radio frequency (RF) systems in an EIC performs a wide range of functions from increase particle energy, bunch splitting or lengthening, to beam rotation, and maintain beam stability, etc. In this talk, an overview of the RF systems for both eRHIC and JLEIC designs is introduced. The subsystems and their necessity to the design luminosity will be presented.
The high luminosity LHC (HL-LHC) will use transverse deflecting superconducting cavities (aka crab cavities) to achieve head-on collisions at the interaction points (IP1 and IP5). Crab cavities will recover the geometric luminosity loss due to the finite crossing angle at the IPs without which the peak luminosity loss can be up to 70 %. The the development of the superconducting crab cavities which were tested for the first time with proton beam in the Super Proton Synchrotron (SPS) is discussed. The main highlights from the beams tests are outlined.
The prospective future Electron-Ion Collider (EIC) would offer a unique opportunity to understand the role of gluons in strongly interacting nuclear matter. An essential requirement of the EIC calorimeters is to provide adequate energy resolution, which translates into momentum resolution and reconstruction, over a wide kinematic range, as well as particle identification in the forward and backward directions. This sets the EIC calorimeters apart from many others. Progress is being made to get reliable PbWO4 crystals that would be compatible with EIC requirements at small angles in the forward and backward regions. At larger angles, where resolution requirements are less stringent, glass scintillators provide an attractive and cost effective option. Some of the most promising materials investigated are cerium doped hafnate glasses and doped and undoped silicate glasses and nanocomposite scintillators. All of these have various shortcomings that include, lack of uniformity and, macro defects, as well as limitations in radiation length, density, radiation resistance, and timing. One of the most recent efforts is DSB:Ce, which is a cerium-doped glass. Small samples of this material have been shown to be in many aspects competitive with PbWO4. However, the issue of macro defects, which can become increasing acute on scale-up remain. A future EIC glass-based calorimeter can benefit from many aspects of this very promising R&D, but also presents its own unique set of challenges. In this talk we will report on the status of the EIC homogeneous crystal/glass-based calorimeter project R&D project and plans for the future.
The JETSCAPE collaboration recently released the first public version
of an innovative modular event generator and simulation framework with
a unified interface and a comprehensive suite of model implementations
for all stages of ultra-relativistic heavy ion collisions.
The framework's modularity and agnosticism regarding the underlying
physics assumptions make it a promising platform for developing Monte
Carlo models of electron-ion collisions specifically because it allows
to concentrate on one aspect at a time, such as medium interaction or
hadronization, while leaving other modules unchanged. An overview of
necessary modifications and baseline performance for electron+proton
collisions will be presented, as well as a first look at possible jet
modification observables in e+nucleus collisions.
Over the past several years, there has been growing interest, both experimental and theoretical, in the prospects of jet physics at the future Electron Ion Collider (EIC). Jets have several properties which make them attractive probes for both the electron-hadron and electron-nucleus EIC physics programs, including their ability to act as surrogates of scattered partons as well as the fact that the energy distribution within a jet can be rigorously defined and studied systematically. A number of recent studies have been made which leverage these advantages to explore a diverse set of physics topics. This contribution will summarize these studies and discuss possible future avenues of research.
TOPSiDE is a concept of a general purpose detector for the Electron-Ion Collider.
It features advanced technologies, such as imaging calorimetry with ultra-fast
silicon detectors. The detector is conceived such that each particle can be identified
and measured individually, similar to the output of Monte Carlo simulations at the
hadron level.
We will review the status of the concept, its GEANT4 implementation, and event
reconstruction. The latter includes an attempt at using Machine Learning
technologies for track finding and to implement Particle Flow Algorithms.
The analysis of fully simulated and reconstructed exclusive J/psi
and Upsilon events will be presented.
The EIC at the highest luminosities will have competitive sensitivity to search for new physics beyond the Standard Model via the observation of charged lepton flavor violation, specifically electron-tau lepton transitions as would result from the existence for instance of leptoquarks. We investigate the identification of tau leptons in the detector with high efficiency using tracking with the vertex detector, energetic lepton and pion identification, and jet observables, while rejecting background. We will present preliminary studies to determine whether such a search could be carried out for a high integrated luminosity data set while maintaining close to perfect background rejection.
The production of a hard dijet with small transverse momentum imbalance in semi-inclusive DIS probes the conventional and linearly polarized Weizsäcker-Williams (WW) transverse momentum dependent (TMD) gluon distributions. The latter, in particular, gives rise to an azimuthal dependence of the dijet cross section. In this talk, I will discuss the feasibility of measurement of these TMDs through dijet production in DIS on a nucleus at an electron-ion collider using a Monte Carlo generator to sample quark-antiquark dijet configurations based on leading-order parton level cross sections. The WW gluon distributions are obtained as a solution of the nonlinear small-x QCD evolution equations. The quark-antiquark dijet configurations are then fragmented to hadrons using PYTHIA, and final-state jets are subsequently reconstructed. I will report on background studies and on the effect of kinematic cuts introduced to remove beam jet remnants. The estimates on required luminosity to measure the distribution of linearly polarized gluons with a statistical accuracy of 5% will be provided.
The Electron Ion Collider optimizes electron and ion beams for high luminosity collisions. For electron/proton collisions, both beams are to be polarized. The accelerator physics challenges are therefore focused on obtaining and maintaining (A) high luminosity and (B) a high degree of polarization. High luminosity provides challenges for (A1) beam currents and for (A2) collision parameters, while polarization has challenges with regard to (B1) high-current polarized sources, and (B2) polarization transport and storage. The collision parameters provide challenges associated with (A2a) small emittances and with (A2b) the construction of high-luminosity interaction regions. Small emittnaces for the ion beams can be maintained by (A2ai) electron cooling, which provides its own set of challenges. This multitude of challenges will be addressed and approches for meeting these challenges will be discussed.
Storing electron bunches with a high degree of polarization will be a key aspect of eRHIC operation.
This talk will introduce the basic concepts of electron beam polarization and summarize known optimization strategies. Special emphasis will be put on the eRHIC project.
The electron-ion collider as the next generation nuclear physics research facility has great demand for the luminosity of colliding beams. Meanwhile, the effects due to the electromagnetic interactions of the colliding beams, i.e. beam-beam effects, put strong limit on the achievable luminosity. In this talk, we will discuss about the numerical simulations of the beam-beam effects with crab cavities. We will present application examples in the HL-LHC study and in the preliminary electron-ion-collider design study.
Dynamic aperture, defined as a stable region in the six dimensional phase space, is always a challenging design issue in circular accelerators. In hadron rings, it is largely determinants by the magnetic errors in the superconducting magnets in arcs at injection and in the final focusing quadupoles at the collision. In electron machines, it is dominated by the sextupoles that are introduced for chromatic compensations. In this paper, we will review methods of optimization of dynamic aperture and their applications to the electron ion colliders.
This talk will review the main hadron beam heating mechanisms for the existing EIC concepts and will establish the requirements for hadron beam cooling. It will then review the conventional and advanced hadron beam cooling techniques and their present state of the art. An R&D path and associated milestones for various cooling techniques will be also discussed.
Designs of two proposed electron-ion colliders, eRHIC at BNL and JLEIC at JLab, are driven by achieving unprecedentedly high performances in collider luminosity, beam polarization and particle detection. To realize such design goals, an arrow of advanced concepts and new accelerator technologies have been integrated into the two collider designs, and several key machine parameters have been pushed beyond the present state-of-art. In this presentation, I give an overview of the advanced accelerator R&D for the two electron-ion colliders and also highlight recent progresses in some areas of the accelerator R&D.
EIC Experiments require excellent hadron identification, over a broad momentum range, in harsh conditions. A RICH capable to fulfill the PID requirements of the EIC could use MPGD-based Photon Detectors (PDs) with solid photocathodes. This technology allows covering large surfaces at affordable cost, provides good efficiency, high resolution and compatibility with magnetic field.
PDs based on the coupling of THGEMs and Micromegas have been successfully operated at the RICH-1 detector of the COMPASS Experiment at CERN since 2016. A similar technology could be used for a RICH at the EIC, provided a large improvement in the photon position resolution is achieved. An R&D effort in this direction is ongoing at INFN Trieste.
Prototypes with small pixel size (down to 3 mm x 3 mm) have been built and tested in the laboratory, using X-Ray and UV light sources.
A modular mini-pad PD with 100 mm x 100 mm active area has been tested at the CERN SPS H4 beam-line in October-November 2018. Cherenkov photons were produced in a fused silica radiator in front of the detector and converted by a CsI-coated THGEM. A second THGEM and a Micromegas acted as further electron amplifiers. Signals were registered via an APV-25 based front-end by a Scalable Readout System (SRS) DAQ with a dedicated software.
The characteristics of the prototype are described and the main results of the laboratory and beam tests are presented.
CsI is the most widely used photo-cathode for gaseous detectors of single photons, but it is hygroscopic and delicate. A search for a novel photo-cathode material with similar sensitivity in the far ultraviolet region and increased robustness against aging and exposure to air is ongoing.
Layers of hydrogenated diamond nano-grains have recently been proposed as an alternative photo-cathode material and shown to have promising characteristics. The performance of nano-diamond photo-cathodes when coupled to THGEM-based detectors are the objects of a dedicated R&D program. Preliminary results on these studies are reported.
The perspectives of these R&D programs are discussed.
We propose to develop a concept for forward and backward tracking detectors near the collision vertex at pseudo-rapidity 1<|eta|<3.5 using small strip Thin Gap Chamber (sTGC) technology. This represents an attractive option for building a tracking device as they have minimum material budget, are easy to construct, and most-importantly, are cost effective. We aim on the detection of all charged hadrons and will study performance parameters such as tracking efficiency and momentum resolution. As part of our proposal, a prototype sTGC was constructed at Shandong University in China. The prototype sTGC detector will be installed at the Solenoidal Tracker at RHIC (STAR) experiment, and tested in the 2019 and 2020 runs. In this talk, I will report the prototype performances from cosmic ray test. The implications of the sTGC detector for tracking at the EIC will be discussed.
At the University of Birmingham, work on the EIC research and development is focused on the silicon vertex tracker, which is the detector closest to the interaction point. Simulations are carried out in an effort to determine the performance of different silicon vertex tracker layouts, and tests are made on individual sensors to find the optimal technology to use, utilising the Birmingham Instrumentation Laboratory for Particle physics and Applications (BILPA).
Currently, depleted monolithic active pixel sensors (DMAPS) are the primary path of investigation. The performance of different settings and pixel sizes and layouts are investigated, primarily using prototype test chips from TowerJazz. The goal is to use the information gathered from experiments on the test chips to develop a new sensor for the EIC, with improved spatial and timing resolution compared to current state-of-the-art silicon vertex tracker detectors.
The presentation will give an overview of the work carried out at the University of Birmingham relating to the EIC R&D, presenting results and conclusions so far. The experiments carried out on the test chips will be discussed in more detail, and results presented and interpreted.
With the advent of cheap, highly integrated and fast converter
electronics, the old and limiting paradigm of a hardware-triggered read
out solution can be replaced with a fully streaming readout system, in
which data selection is moved into the software domain. In the talk, the
advantages of such a system and its implications in the context of EIC
will be discussed.
Modern tracking gaseous detectors based on micro pattern readout, or MPGDs, are becoming the standard in high energy physics experiments. This is thanks to their great time (better than 10ns) and spatial (up to 50µm) resolutions, low energy budget (down to 0.4% of a X0), high rate capabilities (several kHz/mm2), high tolerance to radiation, and relatively low cost per area. In addition to these performances, MPGDs can be used in very different forms and shapes for different applications. For example: cylindrical Micromegas with low material budget for low momentum proton reconstruction at Jefferson Lab for the CLAS12 experiment to the very large muon tracker for the ATLAS experiment at CERN on the LHC with highly controlled geometry.
We propose to report on what we have learned from building these detectors at CEA Saclay from the COMPASS experiment to the LHC upgrade. Then, for those which have been talking physics data, we will report on the operation of these detectors in experimental condition and the performances that they have reached. Later we will present our newest advance in tracking detectors with MPGDs for an EIC.
The most common formulae for both inclusive and exclusive lepton scattering on nuclei frequently assume fixed-target or head-on collider kinematics. Using light-cone vectors defined by the incident beam four-momenta, I will present a universal basis of longitudinal and transverse four-vectors. This permits direct generation of particle four-momenta in the detector frame of a non-collinear collider, as well as direct adaptation to any specific theory formula or Monte Carlo generator that might be hard-wired to a particular frame. In particular, this approach provides a Lorentz-covariant definition of the azimuthal angles, which are not invariant with respect to arbitrary boosts.
In recent years it has become clear that inclusive Deep Inelastic Scattering does not allow to answer a few fundamental questions about the nuclear partonic structure, such the EMC effect. These difficulties will be overcome going beyond inclusive processes, in a new generation of experiments at high energy and high luminosity [1]. Deeply Virtual Compton Scattering (DVCS) is a very promising direction and the first experimental data have become available recently at Jlab, using the $^4$He target, separating the coherent and incoherent channels of the process [2]. We studied the handbag contribution to coherent DVCS off the 4He nucleus in impulse approximation [3]. Within this scenario, a convolution formula for the only leading twist Generalized Parton Distribution (GPD) describing the $^4$He partonic structure is derived in terms of the non-diagonal nuclear spectral function of $^4$He and on the GPD of the struck nucleon. A model for the off-diagonal spectral function, based on the momentum distribution corresponding to the Argonne 18 nucleon-nucleon interaction, is used in the actual calculation together with a well known model as far as it concerns the nucleonic GPD [4]. Then, the numerical results of this approach are compared with the experimental data recently published by the EG6 experiment at the Jefferson Laboratory (Jlab) [2], showing an overall good agreement. On the light of this comparison, one can conclude that the description of the present data does not require exotic arguments, such as dynamical off-shellness or non-nucleonic degrees of freedom. More refined nuclear calculations, necessary for the expected improved accuracy of the next generation of experiments at the Jefferson Laboratory, with the 12 GeV electron beam and high luminosity, and at the future electron-ion collider, both in the coherent and incoherent channels, will be addressed.
[1] R. Dupré and S. Scopetta, Eur. Phys. J. A 52, 159 (2016).
[2] M. Hattawy, et al., CLAS collaboration, Phys. Rev. Lett. 119, 202004 (2017).
[3] S. Fucini, S. Scopetta, and M. Viviani, Phys. Rev. C. 98, 015203 (2018).
[4] S. V. Goloskokov and P. Kroll, Eur. Phys. J. C 53, 367 (2008).
Generalized Parton Distributions (GPDs) have emerged during the 1990s as a powerful concept and tool to study nucleon structure. They provide nucleon tomography from the correlation between transverse position and longitudinal momentum of partons. The Double Deeply Virtual Compton Scattering (DDVCS) process corresponds to the scattering from the nucleon of a virtual photon that finally generates a lepton pair. The virtuality of this photon can be measured and varied, thus providing the necessary lever arm to measure independently the dependences of the GPDs on the initial and transferred momentum[1,2].
Since the cross section of the DDVCS process is very small, any experimental investigation requires high luminosity. The current technology of polarized targets does not allow to operate them in fixed target experiment at such a luminosity. The Electron-Ion Collider (EIC) provides another opportunity for measuring longitudinally and transversely polarized nucleon observables to access GPDs. This presentation will discuss model-predicted DDVCS experimental observables in the kinematical regime of EIC and will address the impact of potential measurements.
[1] M. Guidal and M. Vanderhaeghen, Phys. Rev. Lett. 90 (2003) 012001.
[2] A. V. Belitsky and D. M¨uller, Phys. Rev. Lett. 90 (2003) 022001.
High-energy scatterings allow one to extract information about the distribution of partons inside hadrons. In particular, they constrain the hadronic matrix elements of the energy-momentum tensor which encode the mechanical properties of the system like energy, linear and angular momentum, moment of inertia, pressure forces, ... We present in this talk a selection of recent developments.
I will discuss the theoretical aspects of NLO computations for exclusive diffractive electron-ion processes at small x
General-purpose Monte Carlo event generators are essential tools for any high-energy collider experiments by acting as a link between first-principle calculations and complicated final states measured in the detectors. Large amount of data from different LHC experiments have lead to many recent improvements in perturbative treatment and phenomenological models describing the non-perturbative physics in the modern event generators. In this talk I will give an overview on the current status of Pythia, Herwig and Sherpa event generators for processes relevant to an electron-ion collider. In particular I will discuss about single- and multi-jet production in deep inelastic scattering and compare results from different event generators to data from HERA experiments. In addition, I will present recent developments in photoproduction regime. Here the modelling of the non-perturbative physics becomes more relevant as the (quasi-)real photons may fluctuate into a hadronic state enabling different soft QCD processes, such as diffraction, and multiparton interactions. Also the abilities to generate events with nuclear targets will be commented.
Machine Learning has become a field of great interest lately with newly established software and hardware technologies providing numerous applications. HEP experiments have already begun implementing ML in areas of triggering systems, data quality monitoring, and data analysis. There are several areas were an EIC could potentially exploit ML technology in similar and perhaps unique ways. Some existing ML applications will be presented along with how these might benefit an EIC.
We would like to report a series of studies and prototyping for data acquisition for EIC experiments. The EIC data rate is estimated based on full detector Geant4 simulations, which define the strategy in the DAQ design. The DAQ architecture is based on a high-performance FPGA-based PCI-express DAQ interface, which bridges custom front-end and commodity computing. This series of interface cards have been developed for the FELIX DAQ in the ATLAS Phase-I upgrade and beyond, and it has already been adopted by many high-rate experiments in the 2020s. Prototype timing and flow control are used to synchronize all front-ends. The DAQ package, "RCDAQ", is already used by numerous EIC detector prototyping and beam tests. This work is closely connected with the on-going sPHENIX upgrade which supports both triggered and streaming readout at a higher signal data rate than that of the EIC. We welcome discussion, feedback, and collaboration on adopting this DAQ as part of the EIC detector R&D efforts.
A generic software suite for simulation and reconstruction has been developed to facilitate EIC prototype detector R&D, physics studies and full detector designs. At its core, it is based on Fun4All, a compact and versatile software framework. It has been used in the PHENIX experiment to process tens of petabytes of data each year at BNL, and has been continually developed by the sPHENIX collaboration and adopted by the Fermilab E1039 collaboration. Many packages are integrated into this framework, including event generators, the Geant4 toolkit, detector models, reconstruction and analysis packages. It also provides a simple interface to integrate new simulation and reconstruction modules. It is fully open source and supported with daily build and validations. A standalone container is available for download at https://github.com/sPHENIX-Collaboration/singularity. In this talk, we will discuss this software suite and share its user experience, from learning simulation to large scale computing.
I will discuss the recent developments and near future plans for the Sartre event generator for the EIC. Sartre simulates exclusive vector meson and DVCS production at small x for electron-ion/hadron collisions. It contains models for both saturated and non-saturated QCD. We have added the UPC processes for exclusive vector mesons to the generator, which enable us to test our model against LHC and RHIC measurements. We have also added the Upsilon wave-overlap. There is an ongoing effort for including inclusive diffraction to the framework, which is implemented in parallel with extensions of the dipole model, and new fits to HERA data. We are also adding Deuterium processes to the generator.
The Electron-Ion Collider, with its physics goals of studying in detail perturbative and non-perturbative QCD, requires a complete acceptance detector with high precision tracking, good vertex resolution, and excellent particle identification. The Timing Optimized PID Silicon Detector for the EIC (TOPSiDE) is a proposed concept of such a detector. In the barrel region, it is mainly divided into three parts, a silicon pixel vertex detector, a silicon strip tracker, and an imaging calorimeter concentrically assembled inside the superconducting solenoid. In the forward (backward) region it is supplemented by a Ring Imaging Cherenkov detector (High-resolution Crystal calorimeter). TOPSiDE provides five-dimensional information (energy, position, and time) using the tracker and calorimeter for particle identification by measuring the time-of-flight of charged particles. To cover the entire momentum range (up to 10 GeV/$c$) for most of the solid angle requires a time resolution of around 10ps.
To achieve this time resolution, TOPSiDE uses so-called Ultra-Fast Silicon Detectors (UFSD) based on the Low-Gain Avalanche Detector (LGAD) technology. To date time resolutions of 18 ps have been achieved. To further improve the timing measurement, we plan to integrate the sensor and electronics on the same wafer using the HVCMOS technology. We will present our progress in this respect, i.e., the results from the simulation of LGAD silicon sensor using Silvaco TCAD tools, the design of a PCB based readout electronic system, and the characterization and testing of LGAD silicon sensors both on the bench and in particle beams.
Extraction of the strange quark PDF is a long standing puzzle. We use
nCTEQ nPDFs with uncertainties to examine W/Z production at the LHC
and try to study both the nuclear corrections and the flavor
differentiation. This complements the information from neutrino-DIS
data. Additionally, we look ahead to future facilities such as EIC,
LHeC, and LHC upgrades and use a new tool, PDFSense, to estimate the
impact
Probing the high-x partonic structure of nuclei opens a window in
investigation of several outstanding issues of nuclear dynamics such as
dynamics of the quark/hadron transition, medium modification of
partonic distributions, and ultimately mechanism of the nuclear
repulsive core.
Several inclusive and semi-inclusive deep-inelastic processes will be
discussed relevant to EIC kinematics with evaluation of the sensitivity
to the above discussed nuclear phenomena. We also will discuss how the possible
high-x program at EIC can advance the research on the physics of cold dense
nuclear matter relevant to nuclear astrophysics.
With its high luminosity and wide kinematic coverage, the electron-ion collider (EIC) will be principally dedicated to unraveling vexing issues in QCD. In particular, these include a thorough tomographic mapping of the nucleon's internal structure as well as investigations of the quark-hadron transition, searches for the appearance and dynamics of gluon saturation, and studies of the nuclear environment. At the same time, this wealth of information will not be relegated purely to hadronic or nuclear physics, but will be accompanied by serious advances relevant for high-energy programs at the LHC and beyond. In this talk, I will provide an overview of the physics motivation for the EIC and its importance for future efforts along the energy frontier.
We present a first determination of the nuclear parton distribution functions (nPDF) based on the NNPDF methodology: nNNPDF1.0.
This analysis is based on neutral-current deep-inelastic structure function data and is performed up to NNLO in QCD calculations with heavy quark mass effects.
For the first time in the NNPDF fits, the $\chi^2$ minimization is achieved using stochastic gradient descent with reverse-mode automatic differentiation (backpropagation).
We validate the robustness of the fitting methodology through closure tests, assess the perturbative stability of the resulting nPDFs, and compare them with other recent analyses.
The nNNPDF1.0 distributions satisfy the boundary condition whereby the NNPDF3.1 proton PDF central values and uncertainties are reproduced at $A=1$, which introduces important constraints particularly for low-$A$ nuclei.
We also investigate the information that would be provided by an Electron-Ion Collider (EIC), finding that EIC measurements would significantly constrain the nPDFs down to $x\simeq 5\times 10^{-4}$.
Our results represent the first-ever nPDF determination obtained using a Monte Carlo methodology consistent with that of state-of-the-art proton PDF fits, and provide the foundation for a subsequent global nPDF analyses including also proton-nucleus data.
Perturbative evolution of QCD cross sections is governed by the DGLAP evolution of parton distribution and fragmentation functions. This formalism breaks down at small Bjorken x (high energy) due to high gluon
density (gluon saturation) effects. The Color Glass Condensate (CGC)
formalism is an effective action approach to QCD at
small Bjorken x which includes gluon saturation. The CGC
formalism nevertheless breaks down at intermediate/large Bjorken x. Here we describe the first steps taken towards the
derivation of a new approach, with the ultimate goal of having a
unified formalism for calculation of QCD cross sections at both large and small Bjorken x. Application of the new approach to calculation of observables in EIC will be discussed.
The structure of Goldstone bosons is intimately tied to key questions in QCD, such as, the origin of hadron masses and color confinement. This talk will present recent results on the partonic structure of the pion and kaon obtained using the Dyson-Schwinger equations. Particular focus will be given to the properties of the pion and kaon as expressed by aspects of their light-front wave functions, and the connection of these properties to DCSB, examples include, parton distribution amplitudes and functions, form factors, TMDs and GPDs. Opportunities to measure aspects of this partonic structure at a future electron-ion collider will be discussed.