THz spectrometer calibration at FELIX

Free-electron lasers like FLASHatDESY accelerate short electron pulses with large peak currentsto generate high brightness radiation in the X-ray regime.e accelerators operation requireslongitudinal diagnostics for time scales of tenth of femtoseconds. Here coherent radiationspectroscopy is a suitable method. e absolute value of the longitudinal form factor, that isconnected to the longitudinal prole, can be retrieved by measuring the intensity spectrum of acoherent transition radiation source in the beamline. For this task the spectrometers responsefunction needs to be well known in absolute values, in order to perform accurate measurements.e free-electron laser FELIX in Nijmegen (NL) provides quasi monochromatic beams thatcan be tuned in a wide spectral range at micrometer wavelengths. A calibration campaign fortwo THz spectrometers was performed at this facility with the goal to deduce their responsefunction. is work presents the setup used at FELIX and the analysis of the data for one of thetwo spectrometers. Additionally the measured response function is applied to spectroscopicmeasurements at FLASH

Elektronenbunch-Fokussierung mit einer Plasmalinse(Electronbunch-Focusing with a Plasma Lens)

In dieser Bachelorarbeit wird ein analytisches Modell erläutert, mit dem es möglich ist, dieFokussierung von Plasmalinsen quantitativ zu beschreiben. Dazu werden zunächst Gleichungenfür die inneren Kräfte und das Propagations-Verhalten von Elektronenbunchen hergeleitet.Anschließend wird ein Plasma im Allgemeinen beschrieben und dann die Wechselwirkung vonPlasma und Elektronenbunch betrachtet. Diese Wechselwirkung wird danach analytisch mit einerDifferentialgleichung beschrieben. Die gewonnenen Gleichungen wurden in einem numerischenSkript verarbeitet. Zusätzlich wurden mehrere Particle-In-Cell-Simulationen angefertigtund diese mit den Vorhersagen des analytischen Modells verglichen. Die Übereinstimmungvon Modell und Simulation variiert dabei je nach Parameterbereich. Für dünne Linsen ist dieVorhersage sehr nahe an den Simulationsdaten. Bei Linsen, deren Dicke vergleichbar mit derBrennweite ist, wird die Vorhersage ungenau. Im Ausblick wird dann noch ein mögliches Experimentan der Testanlage Clara vorgestellt

Linac3, LEIR and PS Performance with Ions in 2021 and Prospects for 2022

CERN accelerators underwent a period of long shutdown from the end of 2018 to 2020. During this time frame, significant hardware and software upgrades have been put in place to increase the performance of both proton and ion accelerator chains in the High Luminosity LHC era. In the context of the CERN lead ion chain, 2021 has been mainly devoted to restore the injectors’ performance and to successfully prove the slip-stacking technique in SPS. In this paper we summarise the key milestones of the ion beam commissioning and the achieved beam performance for the Linac 3 (including the source), LEIR and PS accelerators, together with an outlook on 2022 operation

Achievements and Performance Prospects of the Upgraded LHC Injectors

To provide HL-LHC performance, the CERN LHC injector chain underwent a major upgrade during an almost 2-year-long shutdown. In the first half of 2021 the injectors were gradually re-started with the aim to reach at least pre-shutdown parameters for LHC as well as for fixed target beams. The strategy of the commissioning across the complex, a summary of the many challenges and finally the achievements will be presented. Several lessons were learned and have been integrated to define the strategy for the performance ramp-up over the coming years. Remaining limitations and prospects for LHC beam parameters at the exit of the LHC injector chain in the years to come will be discussed. Finally, the emerging need for improved operability of the CERN complex will be addressed, with a description of the first efforts to meet the availability and flexibility requirements of the HL-LHC era while at the same time maximizing fixed target physics output