IMP, TU Darmstadt, Darmstadt, Germany
THM, Friedberg, Germany
The Zero-Bias Schottky Diode (ZBSD) and field effect transistor (TeraFET) based Terahertz (THz) detectors be- come more and more important for beam diagnosis and alignment at THz generating accelerator facilities. The roll- off factor of the detectors at higher THz frequencies requires wide-band amplifiers to enhance the IF signal from a few µW to nW well above the noise floor of the following post detection electronics. Connecting external amplifiers to the detectors via rf cables would enhance the signal losses even further and degrade the signal to noise ratio (SNR). In order to maximize the SNR, it is necessary to have on-chip amplifier integrated in the intermediate frequency (IF) circuit of the detector in the same housing. In this work, we present the design and parametric analysis of components for transition to an IF circuit, which will be integrated in the ZBSD and TeraFET on chip with amplifier in the same housing. The design analysis has been done to find the optimal parameters. The broader IF circuit will enhance the detector resolution to capture pulses in the picosecond range with the help of fast post detection electronics.
[*] R. Yadav et al., doi:10.3390/s23073469
[**] S. Preu et al., doi:10.1109/TTHZ.2015.2482943
[***] A. Penirschke et al., doi:10.1109/IRMMW-THz.2014.6956027
THM, Friedberg, Germany
TEMF, TU Darmstadt, Darmstadt, Germany
GSI, Darmstadt, Germany
GHz transition radiation monitors (GTRs) can be used to measure longitudinal beam profiles even for low ß beams. In comparison to traditional methods e.g., Fast Faraday Cups (FFCs) and Feschenko monitors, GTRs are a non-destructive measurement method and are able to resolve bunch-by-bunch longitudinal profiles at the same time. In our case, we plan to measure the transition radiation outside the beam line through an RF-window with an 8 GHz broad band antenna. At the border of the RF-window the transition radiation is partially reflected propagating in the beam line backwards. In this contribution, we show a study of different geometries to suppress reflections generated at the transition to the RF-window. For higher permittivity the strength of these reflections becomes stronger, simultaneously reducing the measurable signal strength at the antenna. Secondly the RF-window material must be UHV usable and should be durable like Alumina or Peek.
THM, Friedberg, Germany
TEMF, TU Darmstadt, Darmstadt, Germany
DESY, Hamburg, Germany
HZDR, Dresden, Germany
A vacuum sealed prototype of an electro-optical bunch-arrival-time monitor has been commissioned in 2023. It comprises of a pickup-structure and a low-pi-voltage ultra-wideband traveling wave electro-optical modulator. The stainless-steel body of the pickup structure is partially produced by additive manufacturing and comprises four pickups as well as an integrated combination network on a printed circuit board. This novel design aims to enable single-shot bunch-arrival-time measurements for electron beams in free-electron lasers with single-digit fs precision for low bunch charges down to 1 pC. The theoretical jitter charge product has been estimated by simulation and modeling to be in the order of 9 fs pC. The new prototype is tailored for validation experiments at the ELBE accelerator beamline. In this contribution first measurement results are presented.
IMP, TU Darmstadt, Darmstadt, Germany
HZDR, Dresden, Germany
THM, Friedberg, Germany
Semiconductor-based broadband room-temperature Terahertz (THz) detectors are well suitable for beam diagnosis and alignment at accelerator facilities due to easy handling, compact size, no requirement of cooling, direct detection and robustness. Zero-Bias Schottky Diode (ZBSD) based THz detectors are highly sensitive and extremely fast, enabling the detection of picosecond scale THz pulses. This contribution gives an overview of direct THz detector technologies and applications. The ZBSD detector developed by our group has undergone several tests with table-top THz sources and also characterized with the free-electron laser (FEL) at HZDR Dresden, Germany up to 5.56 THz. In order to understand the rectification mechanism at higher THz frequencies, detector modelling and optimization is essential for a given application. We show parametric analysis of a antenna-coupled ZBSD detector by using 3D electromagnetic field simulation software (CST). The results will be used for optimization and fabrication of next generation ZBSD detectors, which are planned to be commissioned at THz generating FEL accelerator facilities in near future.
[1] R. Yadav et al., doi:10.3390/s23073469
[2] M. Hoefleet al., doi:10.1109/IRMMW-THz.2013.6665893
[3] R. Yadav et al., doi:10.18429/JACoW-IPAC2022-MOPOPT013
