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ARIADNE is a 1-ton (330 kg fiducial mass) dual-phase liquid argon (LAr) time projection chamber (TPC) featuring a novel optical readout. Four electron-multiplying charge-coupled device (EMCCD) cameras are mounted externally, and these capture the secondary scintillation light produced in the holes of a thick electron gas multiplier (THGEM). Track reconstruction using this novel readout approach is demonstrated. Optical readout has the potential to be a cost effective alternative to charge readout in future LArTPCs. In this paper, the technical design of the detector is detailed. Results of mixed particle detection using a secondary beam from the CERN PS (representing the first ever optical images of argon interactions in a dual-phase LArTPC at a beamline) and cosmic muon detection at the University of Liverpool are also presented., 58 pages, 40 figures. Changes from previous version based on pre-publication review: improved quality of various figures, improved clarity of some definitions and reduced longer sentences for better readability, fixed typos and formatting errors

ARIADNE is a research project for the development of innovative two-phase optical LAr TPC readouts. Optical readout presents several considerable advantages when compared to traditional segmented THGEM (THick Gaseous Electron Multiplier) charge readout technologies, such as ease of scalability, upgrade, installation and maintenance, cost effectiveness and simplicity. This paper presents the first demonstration of 3D particle tracking in a TPC using purely optical readout. By combining an optically sensitive Timepix3 (TPX3) sensor with an image intensifier a single photon sensitive camera has been developed. TPX3, operated in data driven mode, provides both arrival time (ToA) information and charge deposit information (ToT) together with the coordinates of the active pixel when light is received. Since charge produced in a TPC is drifted over time it is possible to perform full 3D reconstruction by combining the (x,y) pixel information with ToA information. ToT information provides a measure of intensity in each pixel and enables calorimetry. Both an Americium-241 alpha source and cosmic rays have been imaged in 100mbar CF4.

The ARIADNE Experiment, utilising a 1-ton dual-phase Liquid Argon Time Projection Chamber (LArTPC), aims to develop and mature optical readout technology for large scale LAr detectors. This paper describes the characterisation, using cosmic muons, of a Timepix3-based camera mounted on the ARIADNE detector. The raw data from the camera are natively 3D and zero suppressed, allowing for straightforward event reconstruction, and a gallery of reconstructed LAr interaction events is presented. Taking advantage of the 1.6 ns time resolution of the readout, the drift velocity of the ionised electrons in LAr was determined to be 1.608 &plusmn, 0.005 mm/&mu, s at 0.54 kV/cm. Energy calibration and resolution were determined using through-going muons. The energy resolution was found to be approximately 11% for the presented dataset. A preliminary study of the energy deposition (dEdX) as a function of distance has also been performed for two stopping muon events, and comparison to GEANT4 simulation shows good agreement. The results presented demonstrate the capabilities of this technology, and its application is discussed in the context of the future kiloton-scale dual-phase LAr detectors that will be used in the DUNE programme.

The PRINTS database, now in its 21st year, houses a collection of diagnostic protein family ‘fingerprints’. Fingerprints are groups of conserved motifs, evident in multiple sequence alignments, whose unique inter-relationships provide distinctive signatures for particular protein families and structural/functional domains. As such, they may be used to assign uncharacterized sequences to known families, and hence to infer tentative functional, structural and/or evolutionary relationships. The February 2012 release (version 42.0) includes 2156 fingerprints, encoding 12 444 individual motifs, covering a range of globular and membrane proteins, modular polypeptides and so on. Here, we report the current status of the database, and introduce a number of recent developments that help both to render a variety of our annotation and analysis tools easier to use and to make them more widely available. Database URL: www.bioinf.manchester.ac.uk/dbbrowser/PRINTS/

© Copyright owned by the author(s). There is a significant R&D effort ongoing in the liquid argon (LAr) time projection chamber (TPC) community. Due to the scintillation and ionisation properties of LAr, coupled with its low cost, it is possible to construct detectors with immense fiducial volume at a modest cost. It is for this reason that LAr TPCs are fast becoming the detector of choice for long baseline neutrino physics experiments. Using LAr TPCs it is possible to provide the large targets required to make direct observation of neutrino interactions a statistically reasonable prospect. Experiments such as the deep underground neutrino experiment (DUNE) are proposing the use of 68,000 tons of liquid argon as the target material of choice shared between four colossal LAr TPCs. In a two-phase TPC the charge amplification process is performed in the gas phase. By performing charge amplification in the gas phase it is possible to achieve much higher gains and hence improved signal-to-noise ratios. ARIADNE is a novel and innovative two-phase LAr TPC pioneering the direct imaging of secondary scintillation light produced during the charge amplification process using a THGEM in the gas phase. Optical readout presents many advantages over current readout technologies such as massive reductions in the number of readout channels, ease of scalability, upgrade, installation and maintenance as well as cost effectiveness.