The GRAAL high resolution BGO calorimeter and its energy calibration and monitoring system

We describe the electromagnetic calorimeter built for the GRAAL apparatus at the ESRF. Its monitoring system is presented in detail. Results from tests and the performance obtained during the first GRAAL experiments are given. The energy calibration accuracy and stability reached is a small fraction of the intrinsic detector resolution.Comment: 19 pages, 14 figures, submitted to Nuclear Instruments and Method

Photonic integrated reconfigurable linear processors as neural network accelerators

Reconfigurable linear optical processors can be used to perform linear transformations and are instrumental in effectively computing matrix–vector multiplications required in each neural network layer. In this paper, we characterize and compare two thermally tuned photonic integrated processors realized in silicon-on-insulator and silicon nitride platforms suited for extracting feature maps in convolutional neural networks. The reduction in bit resolution when crossing the processor is mainly due to optical losses, in the range 2.3–3.3 for the silicon-on-insulator chip and in the range 1.3–2.4 for the silicon nitride chip. However, the lower extinction ratio of Mach–Zehnder elements in the latter platform limits their expressivity (i.e., the capacity to implement any transformation) to 75%, compared to 97% of the former. Finally, the silicon-on-insulator processor outperforms the silicon nitride one in terms of footprint and energy efficiency

Photonic Combinatorial Network for Contention Management in 160 Gb/s Interconnection Networks based on All-Optical 2x2 Switching Elements

A modular photonic interconnection network based on a combination of basic 2×2 all-optical nodes including a photonic combinatorial network for the packet contention management is presented. The proposed architecture is synchronous, can handle optical time division multiplexed (OTDM) packets up to 160 Gb/s, exhibits self-routing capability, and very low switching latency. In such a scenario, OTDM has to be preferred to wavelength division multiplexing (WDM) because in the former case, the instantaneous packet power carries the information related to only one bit, making the signal processing based on instantaneous nonlinear interactions between packets and control signals more efficient. Moreover, OTDM can be used in interconnection networks without caring about the propagation impairments because of the very short length (< 100 m) of the links in these networks. For such short-range networks, the packet synchronization can be solved at the network boundary in the electronic domain without the need of complex optical synchronizers. In this paper, we focus on a photonic combinatorial network able to detect the contentions, and to optically drive the contention resolution block and the switching control block. The implementation of the photonic combinatorial network is based on semiconductor devices, which makes the solution very promising in terms of compactness, stability, and power consumption. This implementation represents the first example of complex photonic combinatorial network for ultrafast digital processing. The network performance has been investigated for bit streams at 10 Gb/s in terms of bit error rate (BER) and contrast ratio. Moreover, the suitability of the 2×2 photonic node architecture exploiting the earlier mentioned combinatorial network has been verified at a bit rate up to 160 Gb/s. In this way, the potential of photonic digital processing for the next generation broad band and flexible interconnection networks has been demonstrated

Past and future detector arrays for complete event reconstruction in heavy-ion reactions

Complex and more and more complete detector arrays have been developed in the last two decades, or are in advanced design stage, in different laboratories. Such arrays are necessary to fully characterize nuclear reactions induced by stable and exotic beams. The need for contemporary detection of charged particles, and/or γ-rays, and/or neutrons, has been stressed in many fields of nuclear structure and reaction dynamics, with particular attention to the improvement of both high angular and energy resolution. Some examples of detection systems adapted to various energy ranges is discussed. Emphasis is given to the possible update of relatively old 4π detectors with new electronics and new detection methods

Challenges and Requirements for Introducing Impairment-awareness into the Management and Control Planes of ASON/GMPLS WDM Networks

The absence of electrical regenerators in transparent WDM networks significantly contributes to reduce the overall network cost. In transparent WDM networks, a proper resource allocation requires that the presence of physical impairments in Routing and Wavelength Assignment (RWA) and lightpath provisioning be taken into account. In this article a centralized, a hybrid centralized-distributed and two distributed approaches that integrate information about most relevant physical impairments in RWA and lightpath provisioning are presented and assessed. Both centralized and hybrid approaches perform a centralized path computation at the management-plane level, utilizing physical impairment information, while the lightpath provisioning is done by the management plane or the control plane, respectively. The distributed approaches fall entirely within the scope of the ASON/GMPLS control plane. For these two approaches, we provide functional requirements, architectural functional blocks, and protocol extensions for implementing either an impairment-aware real-time RWA, or a lighpath provisioning based on impairment-aware signaling