Accelerator Science and Technology Seminar

Title:
Prospects of ultra-short bunches with low emittance from the SRF photoinjector

Abstract:
Ultrafast Electron Diffraction (UED) is a technique used to observe dynamical changes in the structure of materials. It is based on a pump-probe scheme: a laser pulse excites the target structure and a subsequent electron bunch scatters in the sample producing a diffraction pattern. The time resolution of UED experiments is governed by the electron bunch length and the time of flight jitter, while the spatial resolution is inversely proportional to the transverse emittances. Hence, high brilliance electron beams are needed in order to provide high temporal and spatial resolution at the same time. The SRF Photoinjector offers unique possibilities to perform UED experiments since the original design is flexible enough to fulfill the strict beam requirements with few changes to the beamline. Two phases are foreseen to achieve time resolved UED: the first phase is a proof of concept experiment with a static target to show that it is possible to achieve the required beam parameters, while the objective of the second phase will be to implement the time-resolved pump-probe scheme. Phase 1 is actually under development and is the main focus of this talk. In order to accomplish the high brilliance beam, the longitudinal phase space of the bunch is linearized at the target position by using three L-band booster cavities. On the other hand, the desired transverse phase space parameters are achieved by the use of an aperture and magnets. In summary, we discuss the basic requirements for such experiment, the ongoing work for the first phase and the outlook of the UED project in HZB

Title:

"Design and commissioning of a new optical diagnostics plattform at BESSY II"

Abstract: 

In sector L12, three beamlines are dedicated to bunch-selective non-destructive electron-beam diagnostics. These beamlines include transverse and longitudinal beam characterization with extremely good time and position resolution as well as the currently most effective 2-dimensional system for time vs. one of the transverse directions.

One beamline (Sector12-Dip2.1) will be placed inside the electron ring tunnel about 2 m above the ring plane. This beamline is intended exclusively for THz intensity measurements and simple spectral THz investigations of short pulses and short-time fluctuations (trigger-free analysis).

A second beamline (Sector12-Dip1.2) for transverse beam characterization is nearly completed. Since the main components are already installed, commissioning started a few weeks ago. The main application will be bunch-selective interferometry with an ultrafast intensified CCD camera system (ICCD) and the first results are promising. Later, our beam-halo monitor will be re-installed on the same optical table.

A third beamline (Sector12-Dip1.1) for longitudinal beam studies is in full operation and the main experimental instrument is an ultrafast synchroscan streak camera (as far as we know, with the highest repetition rate of
1 kHz in the world). For time-integrated acquisitions, the time resolution of this combination of optimized new beamline, trigger, and streak camera is improved by a factor of 3 to 5, and the photon yield is improved by a factor of about 3000 compared to the previous
(standard) system at BESSY II. Some examples of advanced 2D beam analysis (x vs. t or y vs. t) with this system are given during the talk.

Title:

"FLASH proton irradiation at HZB"

Abstract: 
The HZB Cyclotron provides 70 MeV protons for the radiation therapy of eye tumors in collaboration with the Charité hospital. More than 4000 patients have been treated so far with a 97% tumor control using conventional dose rates (0.25 Gy/s, 60 s). Recent studies indicate that ultra-high dose rates known as FLASH irradiation (>40 Gy/s, <0.5 s) can reduce the side effects, while shortening the treatment time. Adjustments and additions in the beamline, dosimetric studies, and the development of a fast data acquisition and control system have enabled the HZB Cyclotron to cover a wide range of the FLASH regime and accommodate in vivo and in vitro experiments, towards a future clinical application.

Title:

"Review of the Robinson Wiggler study for MLS"

Abstract: 
A Robinson wiggler was planned to be installed in the storage ring of the MLS, aiming for bunch lengthening by manipulating the damping partition numbers. As a strong focusing device in horizontal and vertical plain, the Robinson wiggler changes the linear lattice significantly. In addition, its impact on nonlinear beam dynamics is not negligible. The model of the Robinson wiggler in linear lattice is introduced in this talk. Correspondingly, the symplectic tracking methods for the Robinson wiggler are presented in detail, which are crucial in nonlinear beam dynamics simulations.

Title:

"Artificial Intelligence for the measurement based reconstruction of the complete SRF Gun module setup @ SeaLab"

Abstract: 

An SRF Gun module has several parameters to be set up and optimized for optimal beam properties during commissioning. This process is usually very time-consuming and tedious.

To overcome this, we can use knowledge extracted by already existing simulations. First, we create a surrogate model using a dataset generated using the simulation. This surrogate replaces the slow simulation. Next, we find the "offsets" – the differences of parameters and screen positioning between simulation and the real machine. The last step is to optimize the beam properties using several global optimization strategies. It turns out that the use of Reinforcement Learning is beneficial in several regards in solving this problem.

Title:

"Status of the VSR Demo project"

Abstract: 

Bunch-length manipulation in modern storage rings light sources is mandatory and CW SRF provides the required high voltage in a compact system to reach this goal. VSR Demo seeks to develop and demonstrate the required SRF technology to achieve this by means of “off-line” testing at HZB SUPRALAB facilities. The current status and achievements will be presented in this talk.

Title:

"PETRA IV - Status, Design, Challenges (tbd)"

Abstract: 

PETRA IV - Information on status, design and challenges.