Margarethe Mapes

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The inner surface of the ring vacuum chambers of the US Spallation Neutron Source (SNS) will be coated with ~100 nm of Titanium Nitride (TiN). This is to minimize the secondary electron yield (SEY) from the chamber wall, and thus avoid the so-called e-p instability caused by electron multipacting as observed in a few high-intensity proton storage rings.(More)
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(More)
With increasing ion beam intensity during recent RHIC operations, rapid pressure rises of several decades were observed at most warm sections and at a few cold sections. The pressure rises are associated with electron multi-pacting, electron stimulated desorption and beam ion induced desorption; and have been one of the major intensity and luminosity(More)
In polarized proton operation, the performance of the Relativistic Heavy Ion Collider (RHIC) is limited by the head-on beam–beam effect. To overcome this limitation, two electron lenses are under commissioning. We give an overview of head-on beam–beam compensation in general and in the specific design for RHIC, which is based on electron lenses. The status(More)
The Spallation Neutron Source (SNS) ring is designed to accumulate, via H injection, 1.6x10 protons per pulse at 60 Hz and 1 GeV energy [1]. At such beam intensity, electron cloud is expected to be one of the intensity-limiting mechanisms that will complicate ring operation. This paper presents the design of the ring vacuum system and the mitigation(More)
i ACKNOWELDGEMENTS I would like to thank Elyse Pineau who not only advised in this process but whose patience and encouragement has been the emotional backdrop for my time at SIU; Ross Singer for his high expectations and kind ear; Ron Pelias for his open door and willingness to mentor at the drop of a hat; Diana Woodhouse for being the best friend and most(More)
The Alternating Gradient Synchrotron (AGS) Booster is a synchrotron for the acceleration of both protons and heavy ions. To minimize the beam loss due to charge exchange of the partially stripped, low beta , very heavy ions with the residual gas molecules, a pressure of low 10/sup -11/ Torr is required for the 200 m booster ring. To achieve this,(More)
The Spallation Neutron Source (SNS) ring is designed to accumulate high intensity protons. Ultrahigh vacuum of 10-9 Torr is required in the accumulator ring to minimize beam-residual gas ionization. To reduce the secondary electron yield (SEY) and the associated electron cloud instability, the ring vacuum chambers are coated with titanium nitride (TiN).(More)
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