J. W. Glenn

Resonant extraction parameters for the AGS Booster

Brookhavens AGS Booster is the injector for the AGS. It is being modified to send resonant extracted heavy ions to a new beam line, the Booster Applications Facility (BAF). The design of the resonant extraction system for BAF was described previously. This note will give a more detailed description of the system and describe the predicted resonant beam time structure. We will describe tune space manipulations necessary to extract the resonant beam at the maximum Booster rigidity, schemes for performing resonant extraction, and describe the modifications required to perform bunched beam extraction to the BAF facility.

Operations and Performance of RHIC as a Cu-Cu Collider

The 5thyear of RHIC operations, started in November 2004 and expected to last till June 2005, consists of a physics run with Cu-Cu collisions at 100 GeV/u followed by one with polarized protons (pp) at 100 GeV [1]. We will address here the overall performance of the RHIC complex used for the first time as a Cu-Cu collider, and compare it with previous operational experience with Au, PP and asymmetric d-Au collisions. We will also discuss operational improvements, such as a squeeze to 85cm in the high luminosity interaction regions from the design value of 1m, system improvements, machine performance and limitations, and address reliability and uptime issues.

Spill structure in intense beams

Fixed target studies of small branching ratio decay processes require intense beams and smooth spills. Longitudinal structure arises through collective effects, well below the coasting beam stability threshold. These structures have been observed at the Brookhaven AGS and dependence on intensity and momentum spread measured. Measurements and amelioration techniques have been developed and will be described.

High intensity proton operations at Brookhaven

In 1995 the AGS upgrade met its design goal of 60 TP (1 TP=10/sup 12/ protons) per pulse, made possible by significant improvements in the AGS Booster and AGS. We summarize these improvements and outline strategies for future upgrades.

Polarized Proton Acceleration in the AGS with Two Helical Partial Snakes

Acceleration of polarized protons in the energy range of 5 to 25 GeV is particularly difficult: the depolarizing resonances are strong enough to cause significant depolarization but full Siberian snakes cause intolerably large orbit excursions and are not feasible in the AGS since straight sections are too short. Recently, two helical partial snakes have been built and installed in the AGS. With careful setup of optics at injection and along the ramp, this combination can eliminate the intrinsic and imperfection depolarizing resonances encountered during acceleration. This paper presents the accelerator setup and preliminary results.

Spin dynamics in AGS and RHIC

A fundamental aspect of particle physics is the spin of the particles. With polarized beams, the internal structure of the proton may be probed in ways that are unattainable with unpolarized beams. The Relativistic Heavy Ion Collider (RHIC) has the unique capability of colliding protons with both transverse and longitudinal polarization at center-of-mass energies up to 500 GeV. In this paper we examine the methods used to accelerate and manipulate polarized proton beams in RHIC and its injectors. Special techniques include the use of a partial Siberian snake and an ac dipole in the AGS. In RHIC we use four superconducting helical Siberian snakes (two per ring) for acceleration, and eight superconducting helical rotators for independent control of polarization directions at two interaction regions.

First beam tests of the muon collider target test beam line at the AGS

In this report we will describe the muon collider target test beam line which operates off one branch of the AGS switchyard. The muon collider target test facility is designed to allow a prototype muon collider target system to be developed and studied. The beam requirements for the facility are ambitious but feasible. The system is designed to accept bunched beams of intensities up to 1.6/spl times/10/sup 13/ 24 GeV protons in a single bunch. The target specifications require beam spot sizes on the order of 1 mm, 1 sigma rms at the maximum intensity. We will describe the optics design, the instrumentation, and the shielding design. Results from the commissioning of the beam line will be shown.

Micro-bunching the AGS slow external beam

Measurements and modeling are presented on BNLs AGS operation of the slow External Beam with sub-nanosecond beam bunching for the full two second spill.

High intensity proton acceleration at the Brookhaven AGS-an update

The AGS accelerator complex is into its third year of 60+/spl times/10/sup 12/ (teraproton=Tp) per cycle operation. The hardware making up the complex as configured in 1997 is briefly mentioned. The present level of accelerator performance is discussed. This includes beam transfer efficiencies at each step in the acceleration process, i.e. losses; which are a serious issue at this intensity level. Progress made in understanding beam behavior at the Linac-to-Booster (LtB) injection, at the Booster-to-AGS (BtA) transfer as well as across the 450 ms AGS accumulation porch is presented. The state of transition crossing, with the gamma-tr jump is described. Coherent effects including those driven by space charge are important at all of these steps.

Increased Intensity Performance of the Brookhaven AGS

With the advent of H- injection into the Brookhaven AGS, circulating beams of up to 3 × 1013 protons at 200 MeV have been obtained. Rf capture of 2.2 × 1013 and acceleration of 1.73 × 1013 up to the transition energy (¿ 8 GeV) and 1.64 × 1013 to full energy (¿ 29 GeV) has been achieved. This represents a 50% increase over the best performance obtained with H+ injection. The increase in circulation beam current is obtained without filling the horizontal aperture. This allows the rf capture process to utilize a larger longitudinal phase space area (¿ 1 eV sec/bunch vs ¿ 0.6 eV sec with H+ operation). The resulting reduction in relative longitudinal density partially offsets the increase in space charge effects at higher currents. In order to make the capture process independent of injected beam current, a dynamic beam loading compensation loop was installed on the AGS rf system. This is the only addition to the synchrotron itself that was required to reach the new intensity records. A discussion of injection, the rf capture process, and space charge effects is presented.