V. Judin

An ultra-fast data acquisition system for coherent synchrotron radiation with terahertz detectors

The recording of coherent synchrotron radiation requires data acquisition systems with a temporal resolution of tens of picosecond. This paper describes a new real-time and high-accuracy data acquisition system suitable for recording individual ultra-short pulses generated by a fast terahertz (THz) detector (e.g. YBCO, NbN, Zero Biased Schottky Diode). The system consists of a fast sampling board combined with a high data throughput readout. The first board is designed for sampling the fast pulse signals with a full width half maximum (FWHM) between a few tens to one hundred picoseconds with a minimum sampling time of 3 ps. The high data throughput board consists of a PCIe-Bus Master DMA architecture used for fast data transfer up to 3 GByte/s. The full readout chain with fast THz detectors and the acquisition system has been successfully tested at the synchrotron ANKA. An overview of the electronics system and preliminary results with multi-bunch filling pattern will be presented.

Real-time measurement of picosecond THz pulses by an ultra-fast YBa2Cu3O7−d detection system

The temporal evolution of picosecond THz pulses generated at ANKA, the electron storage ring of the Karlsruhe Institute of Technology, has been measured in real-time using an ultra-fast YBa2Cu3O7−δ detection system. YBa2Cu3O7−δ thin-film detectors with 30 nm thickness were patterned to microbridges (2 μm long, 4.5 μm wide) and embedded into a planar log-spiral THz antenna. The detectors were glued on a silicon lens and installed in an ultra-fast readout system with a temporal resolution of 15 ps (full width at half maximum). Detector responses as short as 17 ps were recorded showing very good agreement with the expected storage ring bunch lengths.

An ultra-fast digitizer with picosecond sampling time for Coherent Synchrotron Radiation

Since a few years Coherent Synchrotron Radiation (CSR) generated by short electron bunches is provided at the ANKA synchrotron light source. To study the THz emission characteristics over multiple revolutions superconducting YBa2Cu3O7-δ (YBCO) thin-film detectors can be used. The intrinsic response time of YBCO thin films is in the order of a few picoseconds only. For fast and continuous sampling of this individual ultra-short terahertz pulses a novel digitizer system has been developed with programmable sampling times in the range of 3 to 100 ps. The Real-time system is based on a heterogeneous FPGA and GPU architecture for on-line pulse reconstruction and evaluations of the peak amplitudes and the time between consecutive bunches. The data is transmitted to a GPU computing node by a fast data transfer link based on a bus master DMA engine connected to PCI express endpoint logic. This new DMA architecture ensures a continuous high data throughput of up to 4 GByte/s. The presented DAQ system is able to resolve the bursting behavior of single bunches even in a multi-bunch environment and to study the bunch-bunch-interactions.