Relativistic Heavy Ion Collider

The 26.7 MHz (harmonic # h=342) RF system will be used to capture the injected bunched beam from the AGS and accelerate it to a kinetic energy of up to 250 GeV for protons; 100 GeV/u for gold ions. All ions except protons cross transition, and are finally transferred to a storage RF system working at 196 MHz. Each RHIC ring will be provided with two single-ended capacitively loaded quarter-wave cavities; each of these can be dynamically tuned by 100 kHz to compensate for the change in speed of the beam, and can deliver at least 200 kV voltage. A 100 kW tetrode amplifier with local RF feedback is directly coupled to the cavity to minimize phase delay. Prototypes of cavity and amplifier have been built and first test results are presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Large Heavy-Ion Experiment) no Large Hadron Collider (LHC).Apesar de todos os avanços no entendimento acerca da estrutura da matéria, ainda há muitas questões em aberto

In an effort to understand the risks of operating RHIC with an additional delay of 40 ms in the abort system, all beam aborts triggered by loss monitors at store from the years 2014, 2015 and 2016 were analyzed; and particularly fast cases, selected. The results were presented at the RHIC retreat on Jul 29, 2016. All beam aborts at injection, during the ramp and at flattop but before the “ev-lumi” event were ignored since the additional delay of 40 ms is proposed for operation at store only. Many (but not all) of the 15 studied cases are of no concern. Cases with high damage potential are rare - but not rare enough. In order to make an added 40 ms during physics store conditions as safe as reasonably possible, additional permit inputs such as 10 Hz BF power supplies, RF storage cavities, power supply error states or BPMs, in addition to significantly reduced loss monitors (LM) thresholds for selected LM should be commissioned.

The on-momentum description of linear coupling between horizontal and vertical betatron motion is extended to include off-momentum particles, introducing a vector quantity called the "skew chromaticity". This vector tends to be long in large superconducting storage rings, where it restricts the available working space in the tune plane, and modifies collective effect stability criteria. Skew chromaticity measurements at the Cornell Electron Storage Ring (CESR) and at the Fermilab Tevatron are reported, as well as tracking results from the Relativistic Heavy Ion Collider (RHIC). The observation of anomalous head-tail beam losses near the tune diagonal in the Tevatron are explained in terms of the extended theory, including modified criteria for head­ tail stability. These results are confirmed in head-tail simulations. Sources of skew chromaticity are investigated.

BBAT ['bat] is a graphical package, written in C, tcl/tk and BLT, to analyze bunch and bucket properties in the longitudinal phase space for a single and double RF system (Dr. BBAT) interactively. Its usage is detailed fully.