Bulletin of the American Physical Society
APS April Meeting 2023
Volume 68, Number 6
Minneapolis, Minnesota (Apr 15-18)
Virtual (Apr 24-26); Time Zone: Central Time
Session V07: DPF-DPB Prize Session |
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Sponsoring Units: DPF DPB Chair: Heidi Schellman, Oregon State University Room: MG Salon G - 3rd Floor |
Tuesday, April 18, 2023 3:45PM - 4:17PM |
V07.00001: Sakurai Dissertation Award - Cari Cesarotti: TBD Invited Speaker: Cari Cesarotti TBD |
Tuesday, April 18, 2023 4:17PM - 4:49PM |
V07.00002: Ernest Courant Outstanding Paper Recognition: Experimental demonstration of particle acceleration with normal conducting accelerating structure at cryogenic temperature Invited Speaker: Mamdouh Nasr We present an experimental demonstration of the high-gradient operation of an X-band, 11.424 GHz, 20-cells linear accelerator (linac) operating at a liquid nitrogen temperature of 77 K. The tested linac was previously processed and tested at room temperature. Low-temperature operation increases the yield strength of the accelerator material and reduces surface resistance, hence a great reduction in cyclic fatigue could be achieved resulting in a large reduction in breakdown rates compared to room- temperature operation. Furthermore, temperature reduction increases the intrinsic quality factor of the accelerating cavities, and consequently, the shunt impedance leading to increased RF-to-beam efficiency and beam loading capabilities. We verified the enhanced accelerating parameters of the tested accelerator at cryogenic temperature using different measurements including electron beam acceleration up to a gradient of 150 MV/m, corresponding to a peak surface electric field of 375 MV/m. We also measured the breakdown rates in the tested structure showing a reduction of 2 orders of magnitude compared to their values at room temperature for the same accelerating gradient. |
Tuesday, April 18, 2023 4:49PM - 5:21PM |
V07.00003: DPB Thesis Award: Chip-scale atomic beam production, collimation, and its applications Invited Speaker: Chao Li Atomic beams are a key technology for realizing navigation-grade timekeeping and inertial sensing instruments. In this thesis, we demonstrate the use of an array of silicon microchannels to create highly collimated, continuous rubidium atom beams. This allows for the customization of atomic beam pattern and the tailoring of its transverse velocity distribution, which is unachievable using conventional methods, thus enabling precise and targeted delivery of neutral atoms on-chip. Furthermore, we enhance beam brightness using blue-detuned optical molasses and characterize the transversely cooled atomic beams using a two-photon Doppler Raman spectroscopy method. Finally, we present a Monte Carlo simulation-assisted design of a fully chip-scale atomic beam system that contains an atom vapor reservoir and atomic beam drift region bridged by thin silicon microchannels for differential pumping. Additionally, we perform free-space Ramsey interferometry with a two-zone separation as short as 8 mm, which mimics the conditions and constraints for future implementation on this chip-scale platform to fully unleash its potential in inertial sensing and timekeeping. |
Tuesday, April 18, 2023 5:21PM - 5:57PM |
V07.00004: Map and Lie Methods for Accelerator Physics: A Tale of Two Symmetries Invited Speaker: Alex J Dragt Charged particle motion in E and B fields is characterized by two symmetries. First is Lorentz invariance, which is well understood. Second is the symplectic symmetry inherent in the Hamiltonian nature of the Lorentz-invariant equations that generate this motion. (The relation between initial and final conditions obtained by integration of Hamilton's equations is what is called a symplectic map. Thus the effect of any beam-line element in an accelerator is a symplectic map.) Its importance was first studied by Hamilton and Jacobi in the context of generating functions, but its full implications are still not fully appreciated or understood. Since discovery Lie algebras have been an important branch of Mathematics. Now they are also important for Physics both in Relativity and in Particle Theory. This talk aims to describe how Lie methods can also be used to exploit symplectic symmetry. A major goal of map and Lie methods is to treat linear and nonlinear behavior with equal facility. Lie tools have been developed for representing, computing, manipulating, multiplying, and applying symplectic maps. These maps can also be analyzed by normal-form methods (a nonlinear generalization of matrix diagonalization) both to determine and optimize expected accelerator performance and to motivate new designs. Additional applications include fast long-term tracking and the concept and calculation of eigen emittances. |
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