Robert Lambiase

The Brookhaven National Laboratory electron beam ion source for RHIC

As part of a new heavy ion preinjector that will supply beams for the Relativistic Heavy Ion Collider and the National Aeronautics and Space Administration Space Radiation Laboratory, construction of a new electron beam ion source (EBIS) is now being completed. This source, based on the successful prototype Brookhaven National Laboratory Test EBIS, is designed to produce milliampere level currents of all ion species, with q/m=(1/6)-(1/2). Among the major components of this source are a 5 T, 2-m-long, 204 mm diameter warm bore superconducting solenoid, an electron gun designed to operate at a nominal current of 10 A, and an electron collector designed to dissipate approximately 300 kW of peak power. Careful attention has been paid to the design of the vacuum system, since a pressure of 10(-10) Torr is required in the trap region. The source includes several differential pumping stages, the trap can be baked to 400 C, and there are non-evaporable getter strips in the trap region. Power supplies include a 15 A, 15 kV electron collector power supply, and fast switchable power supplies for most of the 16 electrodes used for varying the trap potential distribution for ion injection, confinement, and extraction. The EBIS source and all EBIS power supplies sit on an isolated platform, which is pulsed up to a maximum of 100 kV during ion extraction. The EBIS is now fully assembled, and operation will be beginning following final vacuum and power supply tests. Details of the EBIS components are presented.

RHIC EBIS: basics of design and status of commissioning

RHIC EBIS will be used for producing multicharged ions from helium to uranium using primary ions from various external ion sources. The EBIS is followed by an RFQ and short linac, forming the new preinjector which will produce beams used for physics at RHIC and the NASA Space Radiation Laboratory, The design of RHIC EBIS is based on the BNL Test EBIS, which was a successful 10A electron current prototype. Improvements have been made in the RHIC EBIS design to increase the capacity of the ion trap, repetition frequency of operation, electron current, acceptance for injected ions, and improve vacuum conditions in the ionization region. RHIC EBIS has been assembled and installed in its final position. Commissioning is now underway to reach its project parameters. The results of this commissioning stage are presented.

Conceptual design of a Polarized Electron Ion Collider at Brookhaven National Laboratory

To facilitate the SAC 2015 Long Range Plan for Nuclear Science: a high-energy high-luminosity polarized Electron-Ion Collider (EIC) as the highest priority for new facility construction following the completion of FRIB. Brookhaven National Laboratory (BNL) is proposing to build a high luminosity electron-hadron collider called e-RHIC which incorporates a new electron synchrotron with the existing Relativistic Heavy Ion Collider (RHIC). A low risk conventional technology based design is being adopted for the majority of the accelerator components. The e-RHIC electron source will produce a highly polarized beam current of up to 50 mA with > 80% polarization at an energy of up to 18 GeV with a luminosity > 1034 cm-2s-1. The prototype e-RHIC beam source is currently under development at BNL and Stony Brook University. This paper presents a conceptual design of the e-RHIC machine, how polarized beam will enhance the physics program and plans to address the remaining challenges associated with the construction of e-RHIC. In order to construct a future electron ion collider with high luminosity, a high average current and high bunch charge polarized electron source is under development at Brookhaven National Laboratory. We present the R&D plan for achieving the required charge and current in the polarized eRHIC gun.. The plan involves developing a large single cathode gun to generate 5.3 nC and 6 mA polarized electrons beam. We report the progress of large cathode prototype gun development, the beam line design and plan for measuring gun charge lifetime for high bunch charge, high current operation.

Record Performance of SRF Gun with CsK2Sb Photocathode

High-gradient CW photo-injectors operating at high accelerating gradients promise to revolutionize many sciences and applications. They can establish the basis for super-bright monochromatic X-ray and gamma-ray sources, high luminosity hadron colliders, nuclearwaste transmutation or a new generation of microchip production. In this paper we report on our operation of a superconducting RF electron gun with a record-high accelerating gradient at the CsK2Sb photocathode (i.e. ~ 20 MV/m) generating a record-high bunch charge (i.e., 2 nC). We briefly describe the system and then detail our experimental results. INTRODUCTION The coherent electron cooling experiment (CeC PoP) [1, 2] is expected to demonstrate cooling of a single hadron bunch in RHIC. A superconducting RF gun operating at 112 MHz frequencies generates the electron beam. 500MHz normal conducting cavities provide energy chirp for ballistic compression of the beam. 704-MHz superconducting cavity will accelerate beam to the final energy. The electron beam merges with the hadron beam and after cooling process is steered to a dump. The FEL-like structure enhances the electron-hadron interaction. The electron beam parameters are shown in the Table 1. Table 1: Parameters of the Electron Beam

Control of Laser Ablation Plasma by Pulsed Magnetic Field for Heavy Ion Beam Production

To improve the total charge and quality of a beam pulse from the laser ion source (LIS) operated at Brookhaven National Laboratory (BNL), we attempt to modify the beam current profile to be flatter by applying a pulsed magnetic field to the plasma. For this purpose, we investigated the suitable magnetic field experimentally with a quasi-steady field. We found that a magnetic field decreasing from 90 G to 60 G within 10 μs is expected to create a flat current profile. To drive such a current, we designed a coil and a modified LC discharge circuit. The coil will be installed into LIS at BNL and the effect will be tested.

Circular beam scanning power system for isotope production upgrade

To increase the production of medical isotopes, an upgrade to the Brookhaven Linac Isotope Producer (BLIP) facility is now being designed and constructed. Currently, the ion beam strikes the isotope producing target in a single spot. With this upgrade, the ion beam will be directed to hit the target in circular patterns, distributing the heat of collision over a bigger area on the target. The power system to create the circular patterns requires orthogonal dipole magnets with sinusoidal currents which are ninety degrees apart from each other. This paper describes the design concept for powering the magnets and the control system that produces the correct waveforms despite component variations.