IHEP Beijing, Beijing
IHEP Beiing, Beijing
As a tau-charm factory like collider, the upgrade project of the Beijing Electron Positron Collider (BEPCII), has reached its first design value of luminosity. During the commissioning of its luminosity, beam optics recovery, machine parameters measurement, detector solenoid compensation, and instability cure are main problems we met. Besides commissioning the machine, beams were delivered to the users from high energy physics and synchrotron radiation. This paper summarizes the accelerator physics issues in the BEPCII luminosity commissioning.
Supported by National Natural Sciences Foundation of China (10725525)
CASA, newport news
JLAB, Newport News, Virginia
One key limiting factor to a collider luminosity is bean-beam interactions which usually can cause serious emittance growth of colliding beams and fast reduction of luminosity. Such nonlinear collective beam effect can be a very serious design challenge when the machine parameters are pushed into a new regime. In this paper, we present simulation studies of the beam-beam effect for a medium energy ring-ring electron-ion collider based on CEBAF.
Muons, Inc, Batavia
JLAB, Newport News, Virginia
The operation of the RHIC facility at BNL and the Electron Ion Colliders (EIC) under development at Jefferson Laboratory and BNL need high brightness ion beams with the highest polarization. Charge exchange injection into a storage ring or synchrotron and Siberian snakes have the potential to handle the needed polarized beam currents, but first the ion sources must create beams with the highest possible polarization to maximize collider productivity, which is proportional to a high power of the polarization. We are developing one universal H-/D- ion source design which will synthesize the most advanced developments in the field of polarized ion sources to provide high current, high brightness, ion beams with greater than 90% polarization, good lifetime, high reliability, and good power efficiency. The new source will be an advanced version of an atomic beam polarized ion source (ABPIS) with resonant charge exchange ionization by negative ions. An integrated ABPIS design will be prepared based on new materials and an optimized magnetic focusing system. Polarized atomic and ion beam formation, extraction, and transport for the new source will be computer simulated.
ORNL, Oak Ridge, Tennessee
Experience and lessons with the SNS superconducting linac over the first 5 years of commissioning and operation are reviewed. As the beam power was ramped up to 1 MW, the linac beam loss has been maintained below 1 W/m and residual activation has been held to a safe level. This can be attributed mainly to a robust accelerator design as well as to dedicated beam dynamics studies during this period. In addition to a review of both transverse and longitudinal beam phase-space measurements, we will review several hardware lessons learned with this high-power proton linac − such as nonlinear multipole components of the linac quadrupoles, beam collimators, high-order-mode couplers of the superconducting cavities, and cavity piezo tuners.
ORNL, Oak Ridge, Tennessee
A Medium Energy Beam Transport line (MEBT) is employed in the SNS linac to match the beam from an RFQ to a DTL and to perform other functions. The MEBT lattice consists of fourteen electromagnetic quadrupoles. The quads have very small aspect ratios (steel length over aperture diameter), and they are densely packed in the lattice. Significant fringe fields and magnetic interference cause difficulties in beam matching. We have performed 3D simulations of the magnets, computed their optical properties, and compared their performance with what predicted by simple hard edge models. This paper reports our findings and possible solutions to the problem.