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The European Spallation Source (ESS) will provide long neutron pulses for experiments on a suite of different instruments. Most of these will perform neutron data acquisition in event mode, i.e. each detected neutron will be characterised by one absolute timestamp and pixel identifier pair. Slow controls metadata from EPICS, such as sample environment measurements and motor positions, will also be timestamped at their source, so that all data and metadata are streamed as a list of events instead of histograms. A flexible data aggregation and streaming system is being developed combining both open source third-party software and in-house development. This is to be used at ESS and other neutron scattering facilities like ISIS and SINQ, replacing legacy solutions by a shared software collection maintained by a cross-facility effort. The architecture of the Apache Kafka-based system, its metadata forwarding and NeXus file writing components are presented, along with test results demonstrating their integration and the scalability in terms of performance., Comment: Corrected typos; addressed revision requests: added more details about event sizes, added discussion on generic versus specific applications, added information about the Event Formation Unit's event schema, added more information on performance tests and added reference

A mini-PET style detector system is being developed for a plant imaging application with a compact array of silicon photomultipliers (SiPM) replacing position sensitive photomultipliers (PSPMT). In addition to compactness, the use of SiPMs will allow imaging setups involving high strength MRI-type magnetic fields. The latter will allow for better position resolution of the initial positron annihilations in the plant tissue. In the present work, prototype arrays are tested for the uniformity of their response as it is known that PSPMTs require significant gain compensation on the individual channels to achieve an improved uniformity in response. The initial tests indicate a high likelihood that the SiPM arrays can be used without any gain compensation., Comment: Presented at 2010 IEEE NSS/MIC Conference, Knoxville, Tennessee, USA, October 30 - November 6, 2010

The accelerated expansion of the universe has now been confirmed by several independent observations including those of high redshift type Ia supernovae, and the cosmic microwave background combined with the large scale structure of the Universe. In this work we introduce families of analytical solutions for the scale factor different from the current literature. The knowledge of the scale factor behavior might shed some light on these questions since the entire evolution of a homogeneous isotropic Universe is contained in the scale factor. We use different parameters for these solutions and with these parameters we stablish a connection with the equation of state for different dark energy scenarios., Comment: 15 pages, 5 figures. Revtex4

From the principles of quantum cosmologies we can justify the reason for an inverse-square law for the cosmological constant with no conflict with observations. Although this general expression for $\Lambda$ is well known in the literature, in this work we introduce some analytical solutions for the scale factor different from the literature. The underlying motivation to carry out these solutions is the fact that the time variation of $\Lambda$ can lead to a creation of matter and/or radiation such as to help in the investigation of the age of the Universe. The knowledge of the scale factor behavior might shed some light on these questions since the entire evolution of a homogeneous isotropic Universe is contained in the scale factor., Comment: 10 pages. RevTex