BNL, Upton, Long Island, New York, USA
Fermilab, Batavia, Illinois, USA
FRIB, East Lansing, Michigan, USA
The Electron-Ion Collider (EIC) is being envisioned as the next facility to be constructed by the DOE Nuclear Physics program. Brookhaven National Laboratory is proposing eRHIC, a facility based on the existing RHIC complex as a cost effective realization of the EIC project with a peak luminosity of 1034 cm-2 sec-1. An electron storage ring with an energy range from 5 to 18 GeV will be added in the existing RHIC tunnel. A spin-transparent rapid-cycling synchrotron (RCS) will serve as a full-energy polarized electron injector. Recent design improvements include reduction of the IR magnet strengths to avoid the necessity for Nb3Sn magnets, and a novel hadron injection scheme to maximize the integrated luminosity. We will provide an overview of this proposed project and present the current design status.
BNL, Upton, Long Island, New York, USA
PVI, Oxnard, California, USA
Although great progress was made with in-situ copper coating, by magnetron sputtering, to address the high room temperature resistivity, literature indicates that conventionally deposited thick copper films do not retain the same RF conductivity at cryogenic temperatures, since straightforward deposition tends to result in films with columnar structure and other lattice defects, which cause significant conductivity degradation at cryogenic temperatures. We utilize energetic ions for ion assisted deposition (IAD) to reduce lattice imperfections, for coating. IAD that can in-situ coat long small diameter tubes with compacted crystalline structure thick copper films has been developed. Moreover, development of techniques and devices can resurrect IAD for other applications, which have been impractical and/or not viable economically. Comparison of conductivity at cryogenic temperatures between straight magnetron physical vapor deposition and IAD will be presented.
BNL, Upton, Long Island, New York, USA
PVI, Oxnard, California, USA
A unique apparatus for measuring RF resistivity of tubes and coated tubes at cryogenic temperatures is operational at BNL, which to our knowledge is the first of its kind. A folded quarter wave resonator structure of 300 mm length accesses a wide range of frequencies. The structure is cooled in liquid He bath at 4 K. All internal resonator components (except for test samples) were fabricated out of superconducting materials. Consequently, when the resonator is cooled, the bulk of the losses are due to the copper coating. The RF resistivity is determined from Q measurements, since for a fixed geometry the quality factor of a resonant cavity is proportional to the square root of the conductivity. The RF input loop and the output signal antenna are adjustable when cold via bellows to control matching to each cavity mode. The Q values of 10 resonant modes between 180 and 2500 MHz are deduced from the bandwidth of the S21 response Network Analyzer measurements. CST MicroWave Studio is used to extract the resistivity of the samples from the Q measurements. Resistivity results of solid Cu tube, 2, 5, & 10 μm Cu coated 316LN stainless steel RHIC beam tubes will be presented.