Alessandro Ratti

Operational performance of the SNS LLRF interim system

A new approach has been taken to develop and build the Low-Level RF Control System for the SNS Front End and Linear Accelerators, as reported in a separate paper in this conference. An interim version, based on the proven LBNL MEBT design, was constructed to support short-term goals and early commissioning of the Front End RFQ and DTL accelerators, while the final system is under development. Additional units of the interim system are in use at JLab and LANL for concept testing, code development, and commissioning of SNS SRF cryomodules. The conceptual design of the MEBT system had already been presented elsewhere, and this paper will address operational experiences and performance measurements with the existing interim system hardware, including commissioning results at the SNS site for the Front End and DTL Tank 3 together with operational results from the JLab test stand.

Integrating a Traveling-Wave Tube into an AECR-U Ion Source

A radio frequency system of 500 W output power from 10.75 to 12.75 GHz frequency range was designed and integrated into the Advanced Electron Cyclotron Resonance-Upgrade (AECR-U) ion source of the 88-inch cyclotron at Lawrence Berkeley National Laboratory. The AECR-U produces ion beams for the cyclotron, giving large flexibility of ion species and charge states. The broadband frequency of a traveling-wave tube (TWT) allows modifying the volume that couples and heats the plasma. The TWT system design and integration with the AECR-U ion source and results from commissioning are presented.

Use of High Resolution DAQ System to Aid Diagnosis of HD2b, a High Performance

A novel voltage monitoring system to record voltage transients in superconducting magnets is being developed at LBNL . This system has 160 monitoring channels capable of measuring differential voltages of up to 1.5 kV with 100 kHz bandwidth and 500 kS/s digitizing rate. This paper presents analysis results from data taken with a 16 channel prototype system. From that analysis we were able to diagnose a change in the current-temperature margin of the superconducting cable by analysing Flux-Jump data collected after a magnet energy extraction failure during testing of a high field Nb3Sn dipole.

{\rm Nb}_{3}{\rm Sn}

This paper describes the several phases which led, from the conceptual design, prototyping, construction and tests with beam, to the installation and operation of the BRAN (Beam RAte of Neutrals) relative luminosity monitors for the LHC. The detectors have been operating since 2009 to contribute, optimize and maintain the accelerator performance in the two high luminosity interaction regions (IR), the IR1 (ATLAS) and the IR5 (CMS). The devices are gas ionization chambers installed inside a neutral particle absorber 140 m away from the Interaction Points in IR1 and IR5 and monitor the energy deposited by electromagnetic showers produced by high-energy neutral particles from the collisions. The detectors have the capability to resolve the bunch-by-bunch luminosity at the 40 MHz bunch rate, as well as to survive the extreme level of radiation during the nominal LHC operation. The devices have operated since the early commissioning phase of the accelerator over a broad range of luminosities reaching 1.4×1034 cm−2 s−1 with a peak pileup of 45 events per bunch crossing. Even though the nominal design luminosity of the LHC has been exceeded, the BRAN is operating well. After describing how the BRAN can be used to monitor the luminosity of the collider, we discuss the technical choices that led to its construction and the different tests performed prior to the installation in two IRs of the LHC. Performance simulations are presented together with operational results obtained during p-p operations, including runs at 40 MHz bunch rate, Pb-Pb operations and p-Pb operations. (Less)

Dipole

Synchrotrons like the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory (LBNL) are an extremely bright source of X-rays. In recent years, this brightness has been coupled to large increases in detector speeds (including CMOS and sCMOS detectors) to enable microCT 3D imaging at unprecedented speeds and resolutions. The micro-CT Beamline at the ALS has been used by geologists simulating volcanic eruptions, engineers developing hierarchical materials that are tough at high temperature, and biologists studying water transport in plants experiencing drought stress. In each case, 3D processes occurring over seconds to minutes are studied with micrometer resolution-and in each case, advanced algorithms and data management have been critical in completing successful experiments. This article will describe the collaboration of the ALS with the National Energy Research Scientific Computing Center (NERSC) supercomputer to develop a super-facility, combining powerful X-rays with enormous computing power and describe the collaboration of the ALS with the Center for Applied Mathematics for Energy Research Applications (CAMERA) at LBNL to develop algorithms that can not only handle the enormous data sizes now being collected, but do so fast enough to give scientists feedback during their experiments in real-time. A major focus of CAMERA has been to apply new machine learning approaches to tomography, to improve image reconstruction, automate feature detection, and allow image search.