Accelerator Science and Technology Seminar

Title:

"Design Strategies Towards A Lattice For BESSY III"

Abstract:

Lattice design is a bit like "looking for the needle in the haystack". We need to optimize many lattice properties, like the emittance, the momentum compaction factor, energy acceptance, dynamic aperture, lifetimes, circumference and the like, by varying many tens of magnet parameters and distances, multi-parameter optimization in a very high dimensional space. In the special case of modern Multi-bend Achromat lattices, HZB developed a deterministic approach to lattice design, that enables an understanding of the functionality of different lattice components. The successive set up of the linear lattice can help to prepare a good non-linear behavior. Different lattice options are compared and current aspects of the lattice development are discussed.

Title:

"Optimising the Non-Linear Kicker Injection using Reinforcement Learning"

Abstract: 

Synchrotron light source storage rings aim to maintain a continuous beam current without observable beam motion during injection. One element that paves the way to this target is the non-linear kicker (NLK). The field distribution it generates poses challenges for optimising the topping-up operation.

Within this study, a reinforcement learning agent was developed and trained to optimise the NLK operation parameters. We present a brief introduction to reinforcement learning, the models employed, the optimisation process, and the achieved results.

 

Title:

"Characterization of superconductors for SRF accelerators beyond the limits of niobium"

Abstract:

Superconducting radio-frequency (SRF) cavities are a key component for various state-of-the-art particle accelerators. Typically, those cavities are made from niobium for which production techniques and surface treatments have been optimized over many years, providing performances close to the material’s fundamental limits. Thin film coatings are expected to enable operation beyond these limits, i.e. at higher temperature and potentially also at higher accelerating gradients. Especially when aiming for CW applications, the management of dynamic RF losses is crucial, which is closely connected to the quality factor, determined by the cavity’s shape and the material’s surface resistance. Hence, systematic studies on alternative materials and coating processes require measurements of the surface resistance on samples.

Operating a Quadrupole Resonator (QPR), HZB has a world-wide leading role in characterizing superconducting samples at radio frequencies. The QPR enables surface resistance measurements in a wide range of temperature, RF field and frequency along with studies of penetration depth and RF quench field. Recent developments of the sample chamber boosted the measurement accuracy considerably and enabled frequency-dependent studies of the residual resistance. Complementary to that, a simplified measurement device with high sample throughput (RaSTA) is currently under development. Combining those capabilities will enable iterative optimizations of coating processes for high performance SRF thin films.

Title:

"PM-QP Magnets for BESSY III (A short story of magnet development)"

Abstract:

Permanent Hybrid Magnets are a key technology for particle accelerators to reduce the running costs and with this also the lifetime carbon footprint of new large facilities. Main part of those magnets are Permanent magnet (PM) blocks inside an iron yoke that guides the magnetic flux and defining the final magnetic field distribution. For the magnet optimization the shape, position and material parameters of PMs and yoke have to be adjusted correctly to fulfill focusing or bending parameters, as well as necessary field quality.  For this process a deterministic approach is used to minimize unwanted multipole field distributions in the magnet pole tip region and to increase the efficiency of the magnets. In a second step further parts can be used like iron and thermal shims, as well as electrical or mechanical tuners to implement higher thermal and magnetic stability in the design or to handle small magnetic variations of the real PM blocks.
In this talk, an overview of stepwise magnet optimization and PM technologies will be presented.

Title:

''The ARES linac at DESY - Past, Present and Future''

Abstract: 

The dedicated R&D linac ARES at DESY Hamburg is a ~45 meter long normal conducting electron accelerator capable of delivering ultra-short (down to sub-fs), high brightness bunches within an energy range of 20 MeV to 160 MeV at a maximum repetition rate of 50 Hz. Theses bunches, with charges between a few fC and hundreds of pC, are provided to three different experimental stations with world record energy stability.

In this talk we present past, present and future of the accelerator itself, as well as the scientific program being pursued by both DESY-internal and external users. The program includes accelerator component R&D, research on novel passive and active dielectric phase-space manipulators, medical applications, machine learning and more.

Titel of Felix Armborst's Talk:

"History of Maintenance Strategy for the SLS Operation"

Abstract:

The Swiss Light Source (SLS) at the Paul Scherrer Institute (PSI) in Villigen was the first and only 3rd generation light source in Switzerland. After being approved by the Swiss Government in September 1997, construction works for the SLS project began in 1998. The Installation of the accelerator complex began after completion of the building in June 1999. The heart of the complex was the small emittance triple-bend-achromat lattice electron storage ring with 288 m circumference and 2.4 GeV. The performance of the full energy injector complex including the 100 MeV LINAC pre-injector delivering electron bunches to the booster synchrotron installed on the inner wall of the storage ring tunnel enables reusing it for the SLS 2.0 as is or with only slight modifications, i.e., quadrupole ramps adjusted for emittance exchange before extraction. Commissioning of the SLS storage ring started in January 2000, first stored beam was achieved by Christmas 2000, and the design specifications were reached by August 2001 from whereon first user operation with 4 beamlines began. After 22 years of successful operation with over 9500 peer reviewed publications of which the top 5 alone were cited over 10’000 times, the SLS user operation came to its end in September 2023 delivering photons from 16 source points to in total 18 beamlines. The final, ceremonial beam dump was triggered by the PSI director and SLS 2.0 project leader at the end of September 2023. During the 22 years of operation the reliability of the SLS was continuously evaluated and many measures were taken to improve the reliability. In this contribution a retrospective overview of the maintenance strategy and reliability measures are presented highlighting their impact on the reliability for operation of the SLS facility.

Titel of Jonas Kallestrup's Talk:

"Fast Touschek Tracking - A Novel Approach to Momentum Acceptance Computations"

Abstract:

The Touschek lifetime is a key parameter for the performance of synchrotron light sources. Its calculation requires the computation of the local momentum acceptance everywhere in the ring, which is typically done using tracking simulations. Such simulations are particularly computationally expensive for 4th generation light sources, thereby discouraging the Touschek lifetime as a direct optimization parameter.

In this talk, we present a novel approach to the calculation of momentum acceptance based on a three-dimensional dynamic aperture under certain conditions. The new method, Fast Touschek Tracking, indicates up to two orders of magnitude faster lifetime computation for the SLS 2.0 lattice with very good accuracy.

Title:

"The Future RUEDI (Relativistic Ultrafast Electron Diffraction & Imaging) UK Facility"

Abstract: 

The UK government recently announced funding of £124.4M for the building of RUEDI - the Relativistic Ultrafast Electron Diffraction & Imaging Facility at Daresbury Laboratory. RUEDI is a future facility to directly observe and measure fundamental dynamic structural and chemical processes in materials as they happen in real time. The aim of RUEDI is to deliver MeV electron diffraction at timescales down to the sub-10 fs level, in combination with time-resolved MeV electron imaging at slower (ps-scale) timescales with nm-scale resolution. A large variety of laser pump sources and sample environments will be incorporated to enable a wide variety of science to be carried out. RUEDI is being designed to enable the following science themes: dynamics of chemical change; materials in extreme conditions; quantum materials; energy generation, storage, and conversion; and in vivo biosciences. This talk will give an overview of the RUEDI facility focusing on the current status of the accelerator design.

Titel:

 "Optimum time resolution for synchroscan streak-camera measurements" 

Abstract: 

The optical beam diagnostics at the BESSY II light source in Berlin have been improved significantly over the last few years. In particular, the streak-camera system has been extended in precision and sensitivity to allow two-dimensional imaging in time and space for equilibrated and non-equilibrated bunch patterns. In this talk, we show how we have reached a sub-ps RMS total time resolution using filtered synchrotron light. Detailed simulations, including the different physical time-dispersion mechanisms, show the influence of various band-pass and edge wavelength filters on the resolution. The limits for unfiltered near-visible synchrotron radiation (white-light) and the band-pass filter to achieve optimal time resolution are derived as well, providing a basis for more advanced beam-dynamics studies in the near future.

Title:

"Proton Driven Plasma Wakefield Acceleration and Frictional Cooling for a Muon Collider"

Abstract: 

 

Titel:

"CVD Diamond Diagnostics using Graphitic Electrodes for Synchrotron and XFEL Beamlines"

 

Abstract: 

Synchrotron scientists and users demand increasingly stable X-ray beams, where real-time X-ray beam position and beam size feedback is required. To help deliver this, thin CVD diamond diagnostics with metallised “quadrants” to detect beam position have been developed and commercialised over the past decade, and are now in widespread use.

 

This talk presents an all-carbon pixelated diamond detector that has been developed to measure the X-ray beam profile at 100 frames per second. This detector has no surface metallisation in the beam path that could absorb the beam or introduce absorption edges. It uses advances in laser processing to “write” conductive graphitic wire electrodes within the bulk diamond. This technique can be used to increase the charge collection efficiency over conventional devices with surface electrodes, and can produce more robust detectors with no surface metallisation in the beam path that could be damaged by synchrotron or XFEL radiation. 

 

This talk will provide a short summary of the laser writing technology and its application in diamond detector fabrication. An overview of new diamond instruments that this graphitic wire technique has enabled will be presented, from synchrotron diagnostics to CERN detectors. 

The talk will conclude with the X-ray beam profile results obtained at Diamond Light Source in the UK, demonstrating a novel modulation lock-in readout technique which enables the signal from all pixels to be read out simultaneously, and will show pulse-by-pulse profile measurements obtained at European XFEL in Germany.

Title:

"Assessment of the Intra-Beam Scattering and Touschek Lifetime in BESSY III"

Abstract: 

The 4th generation synchrotron light source, BESSY III, is expected to enable high-impact applications for users in life science, material science, solar cell technology, and more.
Currently in its Conceptual Design Report (CDR) phase, the feasibility of BESSY III's ambitious parameter range necessitates a thorough assessment of "collective effects". These effects are phenomena that can either compromise beam stability or degrade beam quality, potentially hindering the expected performance.
In this seminar, we present recent computations of the Intra Beam Scattering (IBS) and Touschek lifetime for the BESSY III lattice. The IBS leads to a significant increase of the final emittance of the light source, while the Touschek effect critically affects the beam lifetime. We discuss the computational methods employed, the strategies for mitigating these effects, the expected performance outcomes, and the specific challenges associated with ultralow emittance storage rings.

Title:

Digital Low-Level-RF Systems @ HZB

Abstract: