Changchun Sun

Conceptual Design of a 260 mm Bore 5 T Superconducting Curved Dipole Magnet for a Carbon Beam Therapy Gantry

A conceptual design of curved superconducting magnet for a carbon therapy gantry has been proposed. The design can reduce the gantrys size and weight and make it more comparable with gantries used for proton therapy. In this paper we report on a combined function, 5 T, superconducting dipole magnet with a 260 mm bore diameter that is curved 90 degrees at a radius of 1269 mm. The magnet superimposes two layers of oppositely wound and skewed solenoids like windings, energized in a way that nulls the solenoid field and doubles the dipole field component. Furthermore, the combined architecture of the windings can create a selection of field terms that are off the near-pure dipole field. Combined harmonics such as a quadrupole and sextupole are needed to adjust the beam trajectory. Ways to adjust the field and beam trajectory, magnet size and assembly, structure and pre-stress are considered.

Lattice Optimization Using Jupyter Notebook on HPC Clusters

Tracy accelerator simulation library [1] was originally developed for the Advanced Light Source (ALS) design studies [2] at LBNL in the late 1980’s. It was originally written in Pascal [3], later ported to C++, and then to C# [4]. It is still actively updated and currently used by the ALS Upgrade Project (ALS-U) [5] to design and to optimize the lattice. Recently, it has been reconstructed to provide ease of use and flexibility by leveraging the quickly growing Python language. This paper describes our effort of porting it to Jupyter Notebook[6] on our institutional High-Performance Computing (HPC) clusters [7]. PERFORMANCE AND PRODUCTIVITY The most CPU-intensive part of the ALS-U design study is the optimization in the high-dimensional parameter space using the multi-objective genetic algorithm (MOGA)[8] on HPC clusters by using Tracy++ [9]. It is critical to have natively compiled code to maximize the runtime performance. But this approach may not be userfriendly enough since many scientists are not comfortable to deal with the complex tool-chain and software dependencies to compile the code. Python made this easy by providing an interactive environment and excellent scientific library support. By making C++ and Python work together properly, we can get a balance of performance and productivity. Productivity will be further increased when Tracy++ is used in the Jupyter Notebook, an interactive and computational environment which has been well recognized in scientific and engineering fields. Other advantages include the contextual readability, reproducibility, and mobility. For example, astropy [10] for astronomy is already a part of the Anaconda distribution [11]. There are also Jupyter Notebooks available for accelerator physics [12]. Our effort is to port Tracy++ API to Python in an automated environment, using Jupyter Notebook running on HPC clusters that hosts a Jupyter HUB [13]. TRACY++ FOR PYTHON We started with porting the Tracy API to Python, then migrated it to the HPC cluster.

Optimization of the ALS-U Storage Ring Lattice

The Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory is proposing the upgrade of its synchrotron light source to reach soft x-ray diffraction limits within the present ALS footprint. The storage ring lattice design and optimization of this light source is one of the challenging aspects for this proposed upgrade. The candidate upgrade lattice needs not only to fulfill the physics design requirements such as brightness, injection efficiency and beam lifetime, but also to meet engineering constraints such as space limitations, maximum magnet strength as well as beamline port locations. In this paper, we will present the approach that we applied to design and optimize a multi-bend achromat based storage ring lattice for the proposed ALS upgrade.

Physics Design Progress towards a Diffraction Limited Upgrade of the ALS

Improvements in brightness and coherent flux of more than two orders of magnitude are possible using multi bend achromat lattice designs [1]. These improvements can be implemented as upgrades of existing facilities, like the proposed upgrade of the Advanced Light Source. We will describe the progress in the physics design of this upgrade, including lattice evolution, error tolerance studies, simulations of collective effects, and intra beam scattering.

R+ D Progress Towards a Diffraction Limited Upgrade of the ALS

Author(s): Steier, C; Anders, A; Byrd, J; Chow, K; Duarte, R; Jung, J; Luo, T; Nishimura, H; Oliver, T; Osborn, J; Padmore, H; Pappas, C; Robin, D; Sannibale, F; De Santis, S; Schlueter, R; Sun, C; Swenson, C; Venturini, M; Waldron, W; Wallen, E; Wan, W; Yang, Y | Abstract: Copyright