Online Model Server for the Jefferson Lab accelerator

A beam physics model server (Art++) has been developed for the Jefferson Lab accelerator. This online model server is a redesign of the ARTEMIS model server. The need arose from an impedance mismatch between the current requirements and ARTEMIS capabilities. The purpose of the model server is to grant access to both static (machine lattice parameters) and dynamic (actual machine settings) data using a single programming interface. A set of useful optics calculations (R-matrix, orbit fit, etc.) has also been implemented and can be invoked by clients via the model interface. Clients may also register their own dynamic models in the server. The server interacts with clients using the CDEV protocol and data integrity is guaranteed by a relational database (Oracle8i) accessed through a persistence layer. By providing a centralized repository for both data and optics calculations, the following benefits were achieved: optimal use of network consumption, software reuse, and ease of maintenance

Izazov eksperimenata virtualnog Comptonovog raspršenja iznad 8 GeV

We discuss the experimental issues confronting measurements of the virtualCompton-scattering (VCS) reaction ep→epγ with electron beams of energy 6 – 30 GeV. We specifically address the kinematics of deeply-virtual-Comptonscattering (deep inelastic scattering, with coincident detection of the exclusive real photon nearly parallel to the virtual photon direction) and large transverse momentum VCS (high energy VCS of arbitrary Q2, and the recoil proton emitted with high-momentum transverse to the virtual photon direction). We discuss the experimental equipment necessary for these measurements. For the deeply virtual Compton scattering, we emphasize the importance of the Bethe-Heitler – Compton interference terms that can be measured with the electron-positron (beam charge) asymmetry, and the electron beam helicity asymmetryRaspravljamo teško´ce s kojima se sučeljavaju mjerenja reakcija virtualnog Comptonovog raspršenja (VCS) ep→epγ pri energijama elektrona od 6 do 30 GeV. Posebno se razmatra kinematika duboko virtualnog Comptonovog raspršenja i VCS s velikim prijenosom impulsa. Raspravljamo mjerne uređaje koji su potrebni za takva mjerenja. Za duboko virtualno Comptonovo raspršenje, naglašavamo važnost Bethe-Heitlerovih interferentnih članova koji se mogu mjeriti asimetrijom elektronpozitron (naboj snopa) i asimetrijom heliciteta elektronskog snopa

Izazov eksperimenata virtualnog Comptonovog raspršenja iznad 8 GeV

We discuss the experimental issues confronting measurements of the virtualCompton-scattering (VCS) reaction ep→epγ with electron beams of energy 6 – 30 GeV. We specifically address the kinematics of deeply-virtual-Comptonscattering (deep inelastic scattering, with coincident detection of the exclusive real photon nearly parallel to the virtual photon direction) and large transverse momentum VCS (high energy VCS of arbitrary Q2, and the recoil proton emitted with high-momentum transverse to the virtual photon direction). We discuss the experimental equipment necessary for these measurements. For the deeply virtual Compton scattering, we emphasize the importance of the Bethe-Heitler – Compton interference terms that can be measured with the electron-positron (beam charge) asymmetry, and the electron beam helicity asymmetryRaspravljamo teško´ce s kojima se sučeljavaju mjerenja reakcija virtualnog Comptonovog raspršenja (VCS) ep→epγ pri energijama elektrona od 6 do 30 GeV. Posebno se razmatra kinematika duboko virtualnog Comptonovog raspršenja i VCS s velikim prijenosom impulsa. Raspravljamo mjerne uređaje koji su potrebni za takva mjerenja. Za duboko virtualno Comptonovo raspršenje, naglašavamo važnost Bethe-Heitlerovih interferentnih članova koji se mogu mjeriti asimetrijom elektronpozitron (naboj snopa) i asimetrijom heliciteta elektronskog snopa

Electron-Ion Collider Performance Studies With Beam Synchronization via Gear-Change

Beam synchronization of the future electron-ion collider (EIC) is studied with introducing different bunch numbers in the two colliding beams. This allows non-pairwise collisions between the bunches of the two beams and is known as gear-change , whereby one bunch of the first beam collides with all other bunches of the second beam, one at a time. Here we report on the study of how the beam dynamics of the Jefferson Lab Electron Ion collider concept is affected by the gear change. For this study, we use the new GPU-based code (GHOST). It features symplectic one-turn maps for particle tracking and Bassetti-Erskine approach for beam-beam interactions

Optimization of the RF Cavity Heat Load and Trip Rates for CEBAF at 12 GeV

The Continuous Electron Beam Accelerator Facility at JLab has 200 RF cavities in the north linac and the south linac respectively after the 12 GeV upgrade. The purpose of this work is to simultaneously optimize the heat load and the trip rate for the cavities and to reconstruct the pareto-optimal front in a timely manner when some of the cavities are turned down. By choosing an efficient optimizer and strategically creating the initial gradients, the pareto-optimal front for no more than 15 cavities down can be re-established within 20 seconds

GPU-optimized Code for Long-term Simulations of Beam-beam Effects in Colliders

We report on the development of the new code for long-term simulation of beam-beam effects in particle colliders. The underlying physical model relies on a matrix-based arbitrary-order symplectic particle tracking for beam transport and the Bassetti-Erskine approximation for beam-beam interaction. The computations are accelerated through a parallel implementation on a hybrid GPU/CPU platform. With the new code, a previously computationally prohibitive long-term simulations become tractable. We use the new code to model the proposed medium-energy electron-ion collider (MEIC) at Jefferson Lab

Simulation Study on JLEIC High Energy Bunched Electron Cooling

In the JLab Electron Ion Collider (JLEIC) project the traditional electron cooling technique is used to reduce the ion beam emittance at the booster ring, and to compensate the intrabeam scattering effect and maintain the ion beam emittance during the collision at the collider ring. Different with other electron coolers using DC electron beam, the proposed electron cooler at the JLEIC ion collider ring uses high energy bunched electron beam, provided by an ERL. In this paper, we report some recent simulation study on how the electron cooling rate will be affected by the bunched electron beam properties, such as the correlation between the longitudinal position and momentum, the bunch size, and the Larmor emittance

GPU Accelerated Long-Term Simulations of Beam-Beam Effects in Colliders

We present an update on the development of the new code for long-term simulation of beam-beam effects in particle colliders. The underlying physical model relies on a matrix-based arbitrary-order particle tracking (including a symplectic option) for beam transport and the generalized Bassetti-Erskine approximation for beam-beam interaction. The computations are accelerated through a parallel implementation on a hybrid GPU/CPU platform. With the new code, previously computationally prohibitive long-term simulations become tractable. The new code will be used to model the proposed Medium-energy Electron-Ion Collider (MEIC) at Jefferson Lab