Felix Based Readout of The Single-Phase Protodune Detector

The liquid argon Time Projection Chamber technique has matured and is now in use by several short-baseline neutrino experiments. This technology will be used in the long-baseline DUNE experiment; however, this experiment represents a large increase in scale, for which the technology needs to be validated explicitly. To this end, both the single-phase and dual-phase implementations of the technology are being tested at CERN in two full-scale (10 × 10 × 10 m3) ProtoDUNE setups. Besides the detector technology, these setups also allow for extensive tests of readout strategies. The Front-End LInk eXchange (FELIX) system was initially developed within the ATLAS collaboration and is based on custom FPGA-based PCIe I/O cards in combination with commodity servers. FELIX will be used in the single-phase ProtoDUNE setup to read the data coming from 2560 anode wires organized in a single Anode Plane Assembly structure. With a sampling rate of 2 MHz, the system must buffer and process an input rate of 74 Gb/s. Event building requests will arrive at a target rate of 25 Hz, and loss-less compression must reduce the data within the requested time windows before it is sent to the experiment’s event building farm. This paper discusses the design of the system as well as first operational experiences.

Theoretical Analysis of the Electroforming Process

A theoretical model is developed for electroforming with a shaped, soluble anode-electrode. Cases are considered for which the electrode is either flat or conforms initially to the shape of the cathode-mandrel. The model is first analysed by a perturbation procedure for a case where the amplitude and slope of the surfaces of sinusoidally-shaped electrodes are small compared with the inter-electrode gap width. The analysis shows that for d.c. electroforming, when the soluble anode is initially flat, the upper surface of the electroformed metal can become fiat at some stage. After that stage has been passed, the amplitude of the metal layer increases indefinitely with time of electroforming. A uniform thickness for the electroformed metal layer cannot, therefore, be achieved, unlike the case for insoluble plane anodes. When a soluble anode which conforms initially to the cathode-mandrel is used, a fiat upper surface for the metal layer can be obtained. When periodic reversal of polarity is used with soluble anodes, a uniform thickness for the electroformed layer cannot be achieved. A numerical method of analysis of electroforming is proposed which removes the restrictions on the size of shape treated by the perturbation method. The latter method is then applied to the practical case of electroforming of a mould for a rubber ‘O’ ring. Conditions are investigated where the anode is (i) plane and insoluble, (ii) plane and soluble, (iii) and (iv) conforming initially to the mandrel-shape and either insoluble or soluble. The numerical method has revealed that a variation in the metal layer thickness occurs for all these types of anode, and that little marked improvement arises if the simplest type of anode—plane and insoluble—is replaced by any one of the others.