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At least 415 records · Page 23

Azimuthal correlations in diffractive scattering at the Electron-Ion Collider

We calculate azimuthal correlations between the exclusively produced vector meson and the scattered electron in Deep Inelastic Scattering processes at the future Electron-Ion Collider (EIC). We identify ``kinematical'' and ``intrinsic'' contributions to these correlations, and show that the correlations are sensitive to the non-trivial correlations in the gluon distribution of the target. Realistic predictions at the EIC kinematics are provided using two different approaches to describe the dipole-proton interaction at relatively small x.

Dumitru, Adrian↗

Radial Shift Lattice Design using BMAD toolkit

The electron-ion collider (EIC) conceptual design [1] requires that the hadron storage ring (HSR) be able to demonstrate radial shifts using a dual rigidity system. The dual rigidity system is a system in which the dipoles in the utility straight sections(USS) of the EIC lattice have a different rigidity than the arc dipoles thus affecting the beam orbit in the lattice arcs. This difference in rigidity allows the orbital offset in the arc magnets to reach approximately 18.7 mm offset, with a circumference lengthening of 73.2 mm.

43 PARTICLE ACCELERATORS↗

Effect of coherent excitation in coherent electron cooler

We consider the possibility of coherent excitation (CE) of cooled particles in the coherent electron coolers (CeC). We consider the current CeC scheme for the Electron Ion Collider (EIC) and derive the tolerances to a systematic error in longitudinal alignment of the electron and the proton bunches in the EIC cooler set by the CE effect.

43 PARTICLE ACCELERATORS↗

Instabilities driven by the fundamental crabbing mode

The Electron Ion Collider (EIC) requires crab cavities to correct for crossing angle effects. These cavities produce a time varying horizontal kick that makes the collision head on in the center of mass frame of the bunches. This results in a luminosity that is very close to the the luminosity obtained without a crossing angle. Producing the kick requires a transverse RF field. This field requires a superconducting resonator and reasonable power levels require loaded quality factors of order a million. This results is a very large transverse impedance for the crabbing mode. The horizontal beta function is large and this, coupled with the large transverse impedance of the resonator can lead to strong instabilities. In the first section of the paper a simple model is used to describe the situation without feedback. There are large ranges of tune leading to strong instabilities in both the electron and hadron storage rings of the EIC. These estimates are confirmed with simulations. In the second section, RF feedback is used to reduce the apparent impedance of the crabbing mode. Simulating the actual feedback would require both a significant rewrite of the tracking code and a significant reduction in computational speed. Instead, the apparent impedance is fitted using one pole filters, which allows use of the existing simulation code. In the third section a transverse damping system is outlined.

43 PARTICLE ACCELERATORS↗

Pathways for a compact double-quarter wave cavity with low peak surface fields and large deflecting kick

This paper describes the parameter choices necessary to obtain a compact Double Quarter Wave (DQW) cavity with low peak surface fields – electric and magnetic – and large deflecting kick. The work is motivated by the space limitations and demanding crabbing voltage required for the crabbing system of the Electron-Ion Collider (EIC) and focuses on the optimization of the 197 MHz crab cavities for the EIC’s hadron ring. For a crabbing voltage of 11.5 MV, the optimized cavity is less than one meter long, showing a maximum peak surface magnetic field of 70 mT and a maximum peak surface electric field of 45 MV/m.

43 PARTICLE ACCELERATORS↗

Understanding the Origin of the Hadron Mass within the Standard Model

Understanding the origin of the hadron mass, which constitutes 99% of our visible universe, is one of the central goals of nuclear physics. Although the Higgs mechanism provides mass for the fundamental building blocks of matter, it can only contribute less than 2% of the proton mass. The vast majority of the proton mass is believed to come from the strong force that tightly binds quarks and gluons (collectively called partons) together as described by Quantum Chromodynamics (QCD). The mass that emerges as a consequence of the strong interactions within QCD is commonly denoted as Emergent Hadronic Mass (EHM). Understanding how the nucleon mass emerges in QCD is a prerequisite to an explanation of how the Universe came into being, therefore it is of utmost importance and one of the key questions to be addressed by the future Electron-Ion Collider (EIC). When it comes to light mesons, particularly pions, the mass decomposition is drastically different. Since the pion is naturally massless in the chiral limit, the majority of its observed mass needs to come from other mechanisms within QCD. Any successful explanation for the EHM needs to be able to reconcile both the heavy proton mass and the very light pion mass (~15% of proton mass) simultaneously. The EHM theories have direct measurable implications on the description of the internal structure of the hadron, i.e., how the partons distribute inside the hadron. Precise measurement of the parton distribution functions (PDFs) will provide necessary experimental verifications and constraints of potential EHM mechanisms. We propose to carry out a comprehensive study of the poorly known pion PDFs at the AMBER experiment at CERN. The measurement will provide vital input to constrain the global analysis of the pion PDFs, which are still based on limited data obtained more than 30 years ago. The proposed pion measurement is the only direct measurement achievable within this decade, which could lead to a future major meson structure program parallel to the EIC’s proton structure measurement.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Dual Energy Storage Ring Project

The overall goals of the project were to evaluate the possibility of an electron cooler based on the novel two-energy ring idea, by designing a suitable ring, and by simulating actual ring performance characteristics with the accelerator physics and design program ELEGANT. Ring parameters were first chosen to be consistent with Jefferson Lab’s EIC design. About mid-way through the project, parameters were adjusted to be consistent with a cooler design for the new EIC project at Brookhaven National Lab.

43 PARTICLE ACCELERATORS↗

Experimental overview about LANL contributions to the Electron-Ion Collider

This report is a request from the LANL team to design and build the Forward Silicon Tracker (FST) for the Electron-Ion Collider (EIC). The report highlights past accomplishments of LANL and seeks DOE support for continued work for the EIC, including silicon detector R&D; silicon tracker construction and operation; heavy flavor physics development and data analysis.

43 PARTICLE ACCELERATORS↗

Eddy current studies for the beam screen of the Electron-Ion Collider hadron storage ring superconducting magnets

A copper-clad stainless steel beam screen will be installed in each of the Relativistic Heavy Ion Collider (RHIC) superconducting (SC) magnets used for making the Electron-Ion Collider (EIC) Hadron Storage Ring (HSR). Eddy currents are induced within conductors to oppose a changing magnetic flux. Eddy currents will appear on the EIC HSR beam screens during ramp up and ramp down, after a magnet quenches and when reversing the polarity of the γ transition jump quadrupoles during γ transition crossing. This study evaluates the magnitude of the eddy currents, the temperature increase due to Joule heating and the stress at the beam screens from the eddy-current induced force.

43 PARTICLE ACCELERATORS↗

The Electron-Ion Collider - A machine that will unlock the secrets of the strongest force in nature!

The computers and smartphones we use every day depend on what we learned about the atom in the last century. All information technology – and much of our economy today – relies on understanding the electromagnetic force between the atomic nucleus and the electrons that orbit it. The science of that force is well understood, but we still know little about the microcosm within the protons and neutrons that make up the atomic nucleus. That’s where Brookhaven National Laboratory (BNL) comes in. Brookhaven National Laboratory (located in Suffolk County, NY, about 60 miles east of midtown Manhattan) was recently chosen as the building site for an Electron-Ion Collider (EIC), a one-of-a-kind nuclear physics research facility. The EIC will be a discovery machine for unlocking the secrets of the “glue” that binds the building blocks of visible matter in the universe. The machine design will take advantage of the existing and highly optimized Relativistic Heavy Ion Collider (RHIC) that’s been operating at Brookhaven Lab since 2000. Beyond sparking scientific discoveries in a new frontier of fundamental physics, the Electron-Ion Collider will trigger technological breakthroughs that have broad-ranging impact on human health and national challenges.

43 PARTICLE ACCELERATORS↗

Design of the Electron Ion Collider Electron Storage Ring SRF cavity

The Electron Ion Collider (EIC) under construction at Brookhaven National Laboratory is a high luminosity collider as the next major research facility for the nuclear physics community. Among the numerous RF subsystems in the EIC, the electron storage ring (ESR) fundamental RF cavities system is one of the most challenging. This system will handle a high beam current of up to 2.5A and replenish up to 10MW of beam power losses from synchrotron radiation and HOM. Variable coupling is required in the cavities due to the wide range of required total RF voltage and beam current combinations. In this paper, we will present the status of the design and future plans.

Guo, J.↗

Time-domain simulation of the crab cavity/beam interaction

The Electron-Ion Collider (EIC) will employ crab cavities to maximize luminosity. A time-domain simulation is developed to study the interaction between the particle beam and the crab cavities in the EIC, including the Low-Level RF (LLRF) feedback loops. The simulation is validated through power and induced voltage estimates. We then use the simulation tool to study the beam loading effects on the crabbing voltage and thus on the beam transverse position and tilt. We also study the crabbing voltage regulation and transmitter power transients as a function of the LLRF design.

43 PARTICLE ACCELERATORS↗

Recovering the Waste Energy from the Electron-Ion Collider Cooling Water Systems

While only a fraction of the electricity required for the EIC goes into the collision itself, most of the energy ultimately ends up being rejected to the environment via the infrastructure cooling systems. The energy utilized by the RF amplifiers, power supplies, magnets, vacuum systems, and cryogenics systems is rejected to the cooling towers that ultimately dissipate the energy to the atmosphere. Current estimates indicate approximately 50 MW of heat is dissipated at a low temperature by the cooling towers. This technical note is prepared to conceptually demonstrate that feasible options exist to recover the low temperature energy from the EIC cooling water systems.

43 PARTICLE ACCELERATORS↗

Preliminary Shielding Analysis for the 1012 400 MeV Linac Building

EIC is planning to purchase a 400 MeV turnkey pre-injector linear accelerator (Linac) which will be in a new building at the end of an existing RHIC tunnel at 12 o’clock. The building will contain the Linac Tunnel and associated accelerating structures, Klystron Gallery and waveguides, laser, utility, and control rooms. This report only examines the radiation source term produced by operating the Linac and not supplemental shielding that may be required to shield the Klystrons or solid state amplifiers in the Klystron Gallery from the x rays they emit. Normal Portland concrete blocks are planned to provide shielding between the Linac vault and the occupiable portions of the building per the attached drawing. It is expected that this facility will not be routinely occupied during operations (post commissioning). The shielding design considers EIC’s draft Shielding Policy that states shielding and other controls for areas where access is controlled for radiological purposes will be designed so that an ambient dose of 100 mrem per year to a worker is not likely.

43 PARTICLE ACCELERATORS↗

A Damping Ring for the Rapid Cycling Synchrotron

The Electron-Ion Collider (EIC) electron accelerator chain consists of a 400 MeV electron Linear Accelerator (LINAC), the Rapid Cycling Synchrotron (RCS), and the Electron Storage Ring (ESR). The LINAC injects into the RCS, the RCS ramps to a top energy of 18 GeV and the electron beam is extracted to the ESR. To minimize the momentum spread of the 400 MeV injected beam and serve as a 28 nC electron accumulator ring, a damping ring is proposed. This ring may also serve as an intermediate energy booster for the RCS. The damping ring is not within the current baseline of the EIC project.

43 PARTICLE ACCELERATORS↗

TOLERANCES OF CRAB DISPERSION AT THE INTERACTION POINT IN THE HADRON STORAGE RING OF THE ELECTRON-ION COLLIDER

The Electron Ion Collider (EIC) presently under construction at Brookhaven National Laboratory will collide polarized high energy electron beams with hadron beams with luminosities up to 10^34 cm^?2 s^?1 in the center mass energy range of 20-140 GeV. Due to the detector solenoid in the interaction region, the design horizontal crabbing angle will be coupled to the vertical plane if uncompensated. In this article, we study the tolerances of crab dispersion at the interaction point in the EIC Hadron Storage Ring (HSR). Both strong-strong and weak-strong simulations are used. We found that there is a tight tolerance of vertical crabbing angle at the interaction point in the HSR.

Luo, Y.↗

Future Studies of Dihadron Production in SIDIS

Spin asymmetry and cross section measurements in semi-inclusive hadroproduction grant access to a variety of parton distribution and fragmentation functions. Such measurements of dihadron production additionally constrain Dihadron Fragmentation Functions (DiFFs), and the extra degree of freedom from the second hadron facilitates access to some of the parton distribution functions. At CLAS kinematics, subleading-twist parton distributions are accessible in dihadron beam-spin and target-spin asymmetries, and a comparison of semi-inclusive scattering off a proton and a deuteron probes their flavor dependence. The future Electron-Ion Collider (EIC) with a transversely polarized proton will access several transverse-momentum dependent distributions such as Sivers and transversity. On the fragmentation side, numerous DiFFs are accessible, and their partial wave expansion probes correlations between the angular momentum of the fragmenting parton with that of the observed dihadron. Furthermore, different hadron channels probe flavor dependence in fragmentation. Together with CLAS, the EIC as well as CLAS with the proposed 22 GeV accelerator upgrade will cover a broad range of $Q^2$ and $x$, allowing for the study of evolution effects of all of these functions. This presentation will summarize the possibilities of these measurements at CLAS and at future experimental facilities.

Dilks, Christopher↗

Design and Prototyping of the Electron Ion Collider Electron Storage Ring SRF cavity

Among the EIC?s numerous RF subsystems, the electron storage ring?s (ESR) 591 MHz fundamental RF system is one of the most challenging. Each cavity in the system will handle up to 2.5 A of beam current and supply up to 600 kW beam power under a wide range of voltage. The EIC R&D plan includes the design, fabrication and testing of such a cavity. In this paper, we will report the latest status and findings of the ongoing design and prototyping of this cavity, including the RF and mechanical/thermal design, fabrication design, and the progress of fabrication.

Guo, Jiquan↗