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Introduction - Trains and Pulses

This overview focuses on information that is needed to understand the structure of the data produced at European XFEL, and how to analyse it. For a more general overview see the 'Facility' page on the European XFEL website .

Trains and Pulses

European XFEL generates a pulse train of up to 2700 individual X-ray pulses, at a rate of 10 trains per second (10Hz). Within a train, pulses arrive with a maximum frequency of 4.5 MHz (220 ns between pulses).

EuXFEL Pulse Structure

The structure of trains and pulses at European XFEL

Each train receives a unique integer macro number, the so-called trainId.

This trainId is utilized in the data files for indexing. Hence, the DAQ writes data per trainId to disk. If more data per train is required, it is related to the pulse numbers.

Information about the pulses generated in each SASE can be recorded with a BUNCH_DECODER device. This is a subset of the raw ‘bunch pattern’ data available through a TIMESERVER device.

Chapter Overview

The following sections describe in detail, the EuXFEL data acquistion system:

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