Search

The article presents the results of studies of the characteristics of lead tungstate crystals (PbWO4). Measurements of light transmission and light output from the passage of cosmic muons were carried out. The average light transmittance of crystals in the transverse direction is 62.82, 68.38, and 75.68% at wavelengths λ = 360, 420, and 620 nm, and the light output is ~16 pe/MeV. A prototype of an electromagnetic calorimeter was designed and built from crystals arranged in a 4 × 4 matrix which has been tested by cosmic muons. The results obtained confirm the conclusions of other groups in the Electron-Ion Collider collaboration that the quality of the crystals produced by CRYTUR meets the requirements for an electromagnetic calorimeter, and that they can be the basis for its creation. [ABSTRACT FROM AUTHOR]

The questions of how the bulk of the Universe's visible mass emerges and how it is manifest in the existence and properties of hadrons are profound, and probe the heart of strongly interacting matter. Paradoxically, the lightest pseudoscalar mesons appear to be key to a further understanding of the emergent mass and structure mechanisms. These mesons, namely, the pion and kaon, are the Nambu-Goldstone boson modes of quantum chromodynamics (QCD). Unravelling their partonic structure and the interplay between emergent and Higgs-boson mass mechanisms is a common goal of three interdependent approaches - continuum QCD phenomenology, lattice-regularised QCD, and the global analysis of parton distributions - linked to experimental measurements of hadron structure. Experimentally, the anticipated electron-ion collider will enable a revolution in our ability to study pion and kaon structures, accessed by scattering from the 'meson cloud' of the proton through the Sullivan process. With the goal of enabling a suite of measurements that can address these questions, we examine key reactions that identify the critical detector-system requirements needed to map tagged pion and kaon cross-sections over a wide range of kinematics. The excellent prospects for extracting pion structural, functional, and form-factor data are outlined, and similar prospects for kaon structures are discussed in the context of a worldwide programme. The successful completion of the programme outlined herein will deliver deep, far-reaching insights into the emergence of pions and kaons, their properties, and their role as QCD's Goldstone boson modes.

Using a simple geometric framework with a realistic nuclear density distribution, we fit published HERMES data to determine fundamental properties of hadronization using the nuclear medium as a spatial analyzer. Our approach uses a fit to the transverse momentum broadening observable and the hadronic multiplicity ratio; the simultaneous fit to two different observables strongly constrains the outcome. Using the known sizes of the target nuclei, we extract the color lifetime, finding a zh-dependent range of values from 2 to 8 fm/c for these data. We also extract estimates for the qˆ transport coefficient characterizing the strength of the interaction between the quark and the cold nuclear medium, finding an average value of 0.035±0.011 GeV2/fm. With a three-parameter model we obtain satisfactory fits to the data with a goodness-of-fit parameter χ2/dof of 1.1 or less. In a secondary fit of the results from that model we independently find a value for the Lund String Model string tension of 1.00±0.05 GeV/fm. We evaluated the sensitivity for extracting quark energy loss and effective in-medium hadronic cross sections using four-parameter variants of the model, finding large uncertainties in both cases. Our results suggest that hadronic interaction of forming hadrons in the nuclear medium is the primary dynamical cause of meson attenuation in the HERMES data, with quark energy loss playing a more minor role.

Ionization scattering of electron beams with residual gas molecules causes ion trapping in electron rings, both in a collider and electron cooling system. These trapped ions may cause emittance growth, tune shift, halo formation, and coherent coupled bunch instabilities. In order to clear the ions and prevent them from accumulating turn after turn, the gaps in a temporal structure of the beam are typically used. Typically, the gap in the bunch train has a length of a few percent of the ring circumference. In those regions, the extraction electrodes with high pulsed voltages are introduced. In this paper, we present the design consideration and initial test results of the high-voltage pulsed kicker hardware that includes vacuum device and pulsed voltage driver, capable of achieving over 3 kV of deflecting voltage amplitude, rise and fall times of less than 10 ns, 100 ns flat-top duration at 1.4 MHz repetition rate.

One of the more promising observables to probe the high energy regime of the QCD dynamics in the future Electron - Ion Colliders (EIC) is the exclusive vector meson production cross section in coherent and incoherent interactions. Such processes measure the average spatial distribution of gluons in the target as well the fluctuations and correlations in the gluon density. In this paper we present a comprehensive analysis of the energy, photon virtuality, atomic number and momentum transfer dependencies of the coherent and incoherent cross sections considering two different models for the nuclear profile function. In particular, we present the predictions of the hot - spot model, which assumes the presence of subnucleonic degrees of freedom and an energy-dependent profile. Our results indicate that the analysis of the ratio between the incoherent and coherent cross sections and the momentum transfer distributions in the future EIC can be useful to constrain the description of the hadronic structure at high energies. [ABSTRACT FROM AUTHOR]

The motivation of this paper is to explore the parameters that affect the performance of Microchannel Plate Photomultiplier Tubes (MCP-PMTs) in magnetic fields with the goal to guide their design to achieve a high magnetic field tolerance. MCP-PMTs based on two different designs were tested. The magnetic field tolerance of MCP-PMT based on a design providing independently biased voltages showed a significant improvement (up to 0.7 T) compared to the one utilizing an internal resistor chain design (up to 0.1 T), indicating the importance of individually adjustable voltages. The effects of the rotation angle of the MCP-PMT relative to the magnetic field direction and of the bias voltage between the photocathode and the top MCP were extensively investigated using the MCP-PMT based on the independently biased voltage design. It was found that the signal amplitude of the MCP-PMT exhibits an enhanced performance at a tilt angle of ± 8°, due to the 8°bias angle of the MCP pores. The maximum signal amplitude was observed at different bias voltages depending on the magnetic field strength. [ABSTRACT FROM AUTHOR]

The evaluation of the measurement of double-spin asymmetries for charge-separated pions and kaons produced in deep-inelastic scattering from the proton using the ECCE detector design concept is presented, for the combinations of lepton and hadron beam energies of 5 × 41 GeV 2 and 18 × 275 GeV 2. The study uses unpolarised simulated data that are processed through a full GEANT simulation of the detector. These data are then reweighted at the parton level with DSSV helicity distributions and DSS fragmentation functions, in order to generate the relevant asymmetries, and subsequently analysed. The performed analysis shows that the ECCE detector concept provides the resolution and acceptance, with a broad coverage in kinematic phase space, needed for a robust extraction of asymmetries. This, in turn, allows for a precise extraction of sea-quark helicity distributions. [ABSTRACT FROM AUTHOR]

An Electron-Ion Collider (EIC) has been proposed to further explore the strong force and QCD, focusing on the structure and the interaction of gluon-dominated matter. A generic detector R&D program (EIC PID consortium) for the particle identification in EIC experiments was formed to explore technologically advanced solutions in this scope. In this context two Ring Imaging Cherenkov (RICH) counters have been proposed: a modular RICH detector which consists of an aerogel radiator, a Fresnel lens, a mirrored box, and pixelated photon sensor; a dual-radiator RICH, consisting of an aerogel radiator and C 2 F 6 gas in a mirror-focused configuration. We present the simulations of the two detectors and their estimated performance. [ABSTRACT FROM AUTHOR]

In this proceeding, I review what we have learned, and what we will be able to learn, about low- x physics from proton-nucleus ( pA ) collisions at RHIC and the LHC, and how this complements future Electron-Ion Collider (EIC) measurements. EIC not only will provide us essential and complementary information about the gluon saturation to the knowledge that we have learned from pA collisions at RHIC and the LHC, it will also allow us to visualize the internal structure of protons and nuclei in a multi-dimensional fashion with unprecedented precision. [ABSTRACT FROM AUTHOR]

The aims of building electron-ion colliders (EICs) are to reach high collision luminosity and polarization, to search on the structure and the interactions of gluon-matter, to investigate the spin structure of matter, to probe the behavior of parton densities in the nuclear medium, and to study and to test quantum chromodynamics (QCD). In this work, we have calculated the cross-sections of the ion beam loss mechanism at EICs via bound-free pair production (BFPP) mechanism. The BFPP is important for the detector design because of its large cross-sections that will give rise to decrease the luminosity of the accelerators. We have done the cross-section calculations for BFPP in the framework of quantum electrodynamics (QED) by using the lowest-order perturbation theory for three different EICs that are mentioned below. [ABSTRACT FROM AUTHOR]

This article presents a collection of simulation studies using the ECCE detector concept in the context of the EIC's exclusive, diffractive, and tagging physics program, which aims to further explore the rich quark–gluon structure of nucleons and nuclei. To successfully execute the program, ECCE proposed to utilize the detector system close to the beamline to ensure exclusivity and tag ion beam/fragments for a particular reaction of interest. Preliminary studies confirm the proposed technology and design satisfy the requirements. The projected physics impact results are based on the projected detector performance from the simulation at 10 or 100 fb−1 of integrated luminosity. Additionally, insights related to a potential second EIC detector are documented, which could serve as a guidepost for future development. [ABSTRACT FROM AUTHOR]

Particle IDentification (PID) is a central requirement of the experiments at the future EIC. Hadron PID at high momenta by RICH techniques requires the use of low density gaseous radiators, where the challenge is the limited length of the radiator region available at a collider experiment. By selecting a photon wavelength range in the far UV domain, around 120 nm, the number of detectable photons can be increased. Ideal sensors are gaseous Photon Detectors (PD) with CsI photocathode, where the status of the art is represented by the MPGD-based PDs at COMPASS RICH. Detector optimization is required for the application at EIC. Here we report about a dedicated prototype where the sensor pad-size has been reduced to preserve the angular resolution. A new DAQ system based on the SRS readout electronics has been developed for the laboratory and test beam studies of the prototype. [ABSTRACT FROM AUTHOR]

The proposed new Electron–Ion Collider poses a technical and intellectual challenge for the detector design to accommodate the long-term diverse physics goals envisaged by the program. This requires a 4 π detector system capable of reconstructing the energy and momentum of final state particles with high precision. The Electron-Ion Collider also requires identification of particles of different masses over a wide momentum range. A diverse spectrum of Particle IDentification detectors has been proposed. Of the four types of detectors for hadron identification, three are based on Ring Imaging Cherenkov Counter technologies, and one is realized by the Time of Flight method. The quest for a novel photocathode, sensitive in the far vacuum ultraviolet wavelength range and more robust than cesium iodide, motivated an R&D programme to explore nano-diamond (ND) based photocathodes, started by a collaboration between INFN and CNR Bari and INFN Trieste. Systematic measurements of the photoemission in different Ar:CH 4 and Ar:CO 2 gas mixtures with various types of ND powders and Hydrogenated ND (H-ND) powders are reported. A first study of the response of THGEMs coated with different photocathode materials is presented. The progress of this R&D programme and the results obtained so far by these exploratory studies are described. [ABSTRACT FROM AUTHOR]

The Electron–Ion Collider's (EIC's) ability to collide high-energy electron beams with high-energy ion beams will provide access to those regions in the nucleon and nuclei where their structure is dominated by gluons. Moreover, polarized beams in the EIC will give unique access to the spatial and spin structure of gluons and sea-quarks in the proton and light nuclei. The EIC will be an unprecedented collider with luminosities 2–3 orders of magnitude higher than previous e + p colliders over a very wide range of center-of-mass energies, from 20 to 140 GeV, while accommodating highly polarized electron and nucleon beams. Equally demanding are the requirements for the detector(s) that will be needed to carry out the physics program: hermetic coverage in tracking, calorimetry and particle ID within a wide pseudorapidity range, substantial angular and momentum acceptance in the hadron-going direction, as well as high quality hadronic calorimetry among others. This paper gives a brief overview of the detector requirements, current general-purpose detector concepts, and the ongoing EIC detector R&D efforts. [ABSTRACT FROM AUTHOR]

Our understanding of the structure of nucleons is described by the properties and dynamics of quarks and gluons in the theory of quantum chromodynamics (QCD). With advancements in theory and the development of phenomenological tools we are preparing for the next step in subnuclear tomographic imaging at a future electron–ion collider. High center-of-mass energies (up to 150 GeV) in combination with extremely high luminosities (up to 10 34 s − 1 cm − 2 ) will provide the precision and a kinematic reach well into the gluon dominated regime of very low parton momenta where a saturation of the gluon density is expected, in particular in collisions of electrons with heavy nuclei. In addition, highly polarized nucleon and electron beams (70% polarization) can probe the parton polarizations in previously unexplored kinematic regions and with unprecedented accuracy, as well as address the role of orbital angular momentum with respect to the nucleon spin. [ABSTRACT FROM AUTHOR]

Despite the successes of the HERA collider, where much information was gained on the structure of the nucleon, data on the structure of the nucleus at moderate-to-small x remains elusive, as only fixed-target high- x data currently exist. The small- x region, however, is of great interest. The nucleon structure in this region is dominated by gluons which show a rapid rise with decreasing x . At low- x , this growth must be tamed and the gluon distribution will be saturated. This saturation phenomena is expected to be universal, appearing in both nucleons and nuclei. A knowledge of this regime is of vital importance to understanding the underlying physics which governs the initial conditions of heavy-ion collisions at both the LHC and RHIC, where particle production is dominated by gluons from this unknown region. However, only tantalising hints of this have been observed so far. Therefore, the construction of an Electron–Ion Collider (EIC), colliding polarised electrons with polarised protons and also a wide variety of nuclei, will allow an exploration of the region of small- x in great detail (with luminosities 100 x that of HERA), answering questions on both the spatial and momentum distributions of gluons and sea quarks in nuclei. In particular, the saturation region is more accessible in nuclei due to the amplification of the saturation scale with nuclear size ( Q S ∝ A 1 / 3 ). In this paper I present the current status of measuring the gluon distribution in nuclei in e + A collisions at an EIC. [ABSTRACT FROM AUTHOR]

Abstract: We examine the possibility that one could measure partonic charge symmetry violation (CSV) by comparing neutrino or antineutrino production through charged-current reactions induced by electrons or positrons at a possible electron collider at the LHC. We calculate the magnitude of CSV that might be expected at such a facility. We show that this is likely to be a several percent effect, substantially larger than the typical CSV effects expected for partonic reactions. [Copyright &y& Elsevier]

Abstract: To maximize luminosity in a collider, low- quadrupoles need to be installed as close as possible to the interaction point (IP), where beams are focussed to small spot sizes. In an asymmetric collider such as an asymmetric B-factory [An Asymmetric B Factory Based on PEP: Conceptual Design Report, SLAC-0372 ; KEKB B-Factory Design Report, KEK Report 95-7 ] or an electron–ion collider [Hera—A Proposal for a Large Electron Proton Colliding Beam Facility at DESY, DESY HERA 81-10 ; M. Farkhondeh, V. Ptitsyn (Eds.), eRHIC Zeroth Order Design Report, BNL Note C-A/AP/142; L. Merminga, Y. Derbenev, ELIC: an electron-light ion collider at CEBAF, ICFA Beam Dynamics Newsletter No. 30, 2003, p. 22; J.B. Dainton, M. Klein, P. Newman, E. Perez, F. Willeke, Deep Inelastic Electron–Nucleon Scattering at the LHC, DESY 06-006, and Cockcroft-06-04], beams of different energy are brought into collision at the IP. The energy difference requires separate focusing systems for the two beams. Placing regular separator dipoles between the IP and the focussing system either reduces the available space for the detector and therefore the detector acceptance or forces the low- quads to be placed further away from the IP, resulting in reduced luminosity. Combining the separation and focusing functions of the innermost elements by using off-center quadrupoles and/or additional dipole coils on superconducting low- quadrupoles ameliorates the problem somewhat. However, even in this case the separation occurs rather far away from the interaction point, leading to a large width of the synchrotron radiation fan generated by the deflection of the lower-energy electron or positron beam. To overcome these limitations in the eRHIC design, we have proposed integration of dipole coils in the (superconducting) detector solenoid [C. Montag, et al., Interaction region design for the electron–ion collider eRHIC, in: Proceedings of the PAC 2005, 2005], a concept that had originally been proposed for the Linear Collider detector solenoid [B. Parker, A. Seryi, Phys. Rev. ST Accel. Beams 8 (2005) 041001]. This results in a curved trajectory of the lower-energy electron beam across the interaction point, and therefore in a considerable transverse offset of the head and tail of the long ion bunches with respect to the (short) electron bunches. This paper examines beam dynamics issues arising from the collision of a long high-energy ion beam with a lower-energy electron beam on a trajectory curved by the detector-integrated dipole. [Copyright &y& Elsevier]

Abstract: To achieve luminosities ranging from to , future electron–ion colliders require very small beam sizes, together with a large number of bunches. The strong focusing necessary to achieve -functions as low as can only be achieved by placing low- quadrupoles as close as possible to the interaction point (IP). With the beam energies of the ion and electron beam differing by more than an order of magnitude, beams need to be separated before encountering the first ion low- quadrupole, which would otherwise greatly defocus the lower-energy electron beam. This beam separation can be achieved by either deflecting the electron beam away from the ion beam by means of magnetic dipole fields, or by introduction of a crossing angle large enough as to provide sufficient separation at the first ion beam quadrupole. While the former scheme results in large amounts of synchrotron radiation generated near or even inside the detector volume, the latter significantly reduces the luminosity due to the relatively large ion bunch length. This luminosity reduction can be overcome by application of a crab crossing scheme, thus re-instating head-on collisions. However, due to the high ion beam energy, crab cavity RF voltages in the range of tens of megavolts are required, scaling linearly with the RF wavelength. It is therefore desirable to choose the crab cavity RF frequency as high as possible, thus reducing the required voltage. This paper examines the effect of the finite crab cavity RF wavelength on beam dynamics in the proposed electron–ion colliders eRHIC , ELIC , and LHeC . [Copyright &y& Elsevier]

We review predictions of the theory of leading twist nuclear shadowing for inclusive unpolarized and polarized deuteron structure functions $F_2^D$, $g_1^D$ and $b_1^D$ and for the tagged deuteron structure function $F_2^D(x,Q^2,{\bf p})$. We analyze the possibility to extract the neutron structure function $F_2^n$ from electron–deuteron data and demonstrate that an account of leading twist nuclear shadowing leads to large corrections for the extraction of $F_2^n$ from the future deuteron collider data both in the inclusive and in the tagged structure function modes. We suggest several strategies to address the extraction of $F_2^n$ and to measure at the same time the effect of nuclear shadowing via the measurement of the distortion of the proton spectator spectrum in the semi-inclusive eD → e′NX process. We address the issue of the final state interactions in the eD → e′NX process and examine how they affect the extraction of $F_2^n$. [ABSTRACT FROM AUTHOR]

Ionization scattering of electron beams with residual gas molecules causes ion trapping in electron rings, both in a collider and electron cooling system. These trapped ions may cause emittance growth, tune shift, halo formation, and coherent coupled bunch instabilities. In order to clear the ions and prevent them from accumulating turn after turn, the gaps in a temporal structure of the beam are typically used. Typically, the gap in the bunch train has a length of a few percent of the ring circumference. In those regions, the extraction electrodes with high pulsed voltages are introduced. In this paper, we present the design consideration and initial test results of the high-voltage pulsed kicker hardware that includes vacuum device and pulsed voltage driver, capable of achieving over 3 kV of deflecting voltage amplitude, rise and fall times of less than 10 ns, 100 ns flat-top duration at 1.4 MHz repetition rate. [ABSTRACT FROM AUTHOR]

We study the semi-inclusive production of real, high- p T , isolated photons in unpolarized and polarized lepton-proton collisions, ℓ p → ℓ γ X. In particular we analyze the transverse nucleon single-spin asymmetry within the collinear twist-3 formalism in perturbative QCD to leading order (LO) accuracy. We find that this spin asymmetry is generated by twist-3 dynamical quark-gluon-quark (qgq) correlations in the nucleon through the so-called soft-fermion and hard pole contributions. Hence, this process unprecedentedly allows for a point-by-point scan of the support of the dynamical qgq twist-3 matrix elements F F T (x , x ′) and G F T (x , x ′) in lepton-nucleon scattering experiments. [ABSTRACT FROM AUTHOR]

We investigate saturation effects in ep scattering as well as in ultraperipheral p A and AA collisions at small x with four variants of the impact parameter dependent color dipole model: with and without gluon saturation and with and without a novel mechanism that suppresses unphysical dipole radii above the confinement scale, a problem not addressed by most implementations. We show that ep scattering at HERA can be very well described by any of the four variants. When going from ep to e A scattering, saturation effects are expected to increase as ∼A1/3. In lieu of an electron-ion collider, we confront the different versions of the dipole model with data recorded in ultraperipheral collisions at the LHC in order to estimate the sensitivity of the data to gluon saturation in the target nuclei. We find that ultraperipheral PbPb collisions indicate strong saturation effects while p Pb collisions turn out to not have any discriminating power to distinguish saturation from non-saturation scenarios. [ABSTRACT FROM AUTHOR]

This paper discusses the quality and performance of currently available PbWO 4 crystals of relevance to high-resolution electromagnetic calorimetry, e.g. detectors for the Neutral Particle Spectrometer at Jefferson Lab or those planned for the Electron–Ion Collider. Since the construction of the Compact Muon Solenoid (CMS) at the Large Hadron Collider (LHC) and early PANDA (The antiProton ANnihilations at DArmstadt) electromagnetic calorimeter (ECAL) the worldwide availability of high quality PbWO 4 production has changed dramatically. We report on our studies of crystal samples from SICCAS/China and CRYTUR/Czech Republic that were produced between 2014 and 2019. [ABSTRACT FROM AUTHOR]

Polarized electron-deuteron deep-inelastic scattering (DIS) with detection of the spectator proton ("tagged DIS") enables measurements of neutron spin structure with maximal control of nuclear effects. We calculate the longitudinal spin asymmetries in polarized tagged DIS using methods of light-front nuclear structure and study their dependence on the measured proton momentum. Asymmetries can be formed with all three deuteron spin states (± 1 , 0) or the two maximum-spin states only (±1, involving tensor polarization). The proton momentum dependence can be used to select pure S-wave configurations in the deuteron and eliminate D-wave depolarization (transverse momenta p p T ≲ 100 MeV). Free neutron spin structure can be extracted model-independently through pole extrapolation of the tagged asymmetries. Such measurements could be performed at a future electron-ion collider (EIC) with polarized deuteron beams and forward proton detectors. [ABSTRACT FROM AUTHOR]