J. Beebe-Wang

Transverse phase space painting for SNS accumulator ring injection

The results of investigation and comparison of a series of transverse phase space painting schemes for the injection of the SNS accumulator ring is reported. In this computer simulation study, the focus is on the creation of closed orbit bumps that give desired distributions at the target. Space charge effects such as tune shift, emittance growth and beam losses are considered. The results of pseudo end-to-end simulations from the injection to the target through the accumulator ring and the Ring to Target Beam Transfer (RTBT) system are presented and discussed.

Accumulator ring design for the NSNS project

The goal of the proposed National Spallation Neutron Source (NSNS) is to provide a short pulse proton beam of about 0.5 /spl mu/s with average beam power of 1 MW. To achieve such purpose, a proton storage ring operated at 60 Hz with 1/spl times/10/sup 14/ protons per pulse at 1 GeV is required. The Accumulator Ring (AR) receives 1 msec long H/sup -/ beam bunches of 28 mA from a 1 GeV linac. Scope and design performance goals of the AR are presented, other possible technological choices and design options considered, but not adopted, are also briefly reviewed.

Proton injection and RF capture in the National Spallation Neutron Source

The accelerator system for the 1 to 5 MW National Spallation Neutron Source (NSNS) consists of a linac followed by a 1 GeV proton accumulator ring. Since the ring is a very high current machine, the injection and RF capture of the protons is deeply affected by transverse and longitudinal space charge effects. Results of numerical simulation of the process are presented together with considerations on methods and results of space charge treatment in high intensity proton storage rings.

Injection carbon stripping foil issues in the SNS accumulator ring

We are reporting the results of studies on issues related to the injection stripping foil in the Spallation Neutron Source (SNS) accumulator ring. The problems related to foil heating and foil lifetime, such as current density distribution and temperature distribution in the foil, are investigated. The impact of injection errors on the beam losses at the foil is studied. The particle traversal rate and the beam losses due to scattering in the foil are summarized. Finally, SNS end-to-end simulation results of the foil-missing rate, the foil-hitting rate and the maximum foil temperature are presented.

Dynamic aperture evaluation at the current working point for RHIC polarized proton operation

With the updated multipole magnet field errors in the interaction regions (IRs), detailed dynamic aperture studies are carried out around the current RHIC polarized proton (pp) working point. The beam parameters and beta*s are similar to those proposed for the next pp run. The effects on the dynamic apertures from nonlinear corrections, such as multipole field error correction in the IRs, second order chromaticity correction and horizontal third order resonance correction are evaluated. The sextupole components in the arc dipoles and the observed tune ripples are also considered.

Effects of Halo on the AGS Injection from 1.2Gev Linac

BNL is conducting a design study of a 1.0 MW super neutrino beam facility. It requires 230 turns charge exchange injection from a 1.2 GeV superconducting linac with 28 mA current for 0.72 msec. This report studies the impact of halo distribution of the linac beam on the efficiency of injection and the final beam distribution in the AGS as functions of the injection orbit bump and the foil thickness. Another important consideration is the residual radiation generated on the accelerator components near the injection area. If necessary, radiation hardened components and local shielding have to be provided.

RHIC Polarized Proton Performance in Run‐8

During Run-8, the Relativistic Heavy Ion Collider (RHIC) provided collisions of spin-polarized proton beams at two interaction regions. Physics data were taken with vertical orientation of the beam polarization, which in the Yellow RHIC ring was significantly lower than in previous years. We present recent developments and improvements as well as the luminosity and polarization performance achieved during Run-8, and we discuss possible causes of the not as high as previously achieved polarization performance of the Yellow ring.

Realistic non-linear model and field quality analysis in RHIC interaction regions

The existence of multipole components in the dipole and quadrupole magnets is one of the factors limiting the beam stability in the RHIC operations. So, a realistic nonlinear model is crucial for understanding the beam behavior and to achieve the ultimate performance in RHIC. A procedure is developed to build a non-linear model using the available multipole component data obtained from measurements of RHIC magnets. We first discuss the measurements performed at different stages of manufacturing of the magnets in relation to their current state in RHIC. We then describe the procedure to implement these measurement data into tracking models, including the implementation of the multipole feed down effect due to the beam orbit offset from the magnet center. Finally, the field quality analysis in the RHIC interaction regions (IR) is presented.

Emittance growth due to beam-beam effect in RHIC

The beam-beam interaction has a significant impact on the beam emittance growth and the luminosity lifetime in RHIC. A simulation study of the emittance growth was performed using the LIFETRAC code. The operational conditions of RHIC 2006 100GeV polarized proton run were used in the study. In this paper, the result of this study is presented and compared to the experimental measurements.