S. Mastroianni

The Trigger System of the ARGO-YBJ detector

Astrophysical radiation with ground-based observatory at YangBaJing (ARGO-YBJ) is a ground-based cosmic ray detector presently under construction at the Yangbajing High Altitude Cosmic Ray Laboratory (4300 m a.s.l.), Lhasa, Tibet. The apparatus has been designed to detect air showers with an energy threshold of a few hundred GeV and it has a total active area of 6400 m/sup 2/. The full-coverage central carpet of 5772 m/sup 2/ is equipped with an array of resistive plate counters. This array is surrounded by a partially instrumented guard ring to improve the reconstruction of showers with the core falling outside the carpet. The ARGO trigger logic implements simple yet robust algorithms, based on the timing distribution of the hits and their multiplicity on the central carpet. In this paper, we describe the hardware architecture and the main features of the trigger system.

Integration of the Analog Readout in the ARGO-YBJ DAQ System

The ARGO-YBJ experiment has been in stable data taking since November 2007 at the YangBaJing Cosmic Ray Lab oratory (Tibet, China, 4300 m a.s.l.). Its main fields of research are γ-astronomy with an energy threshold of a few hundred GeV and cosmic ray physics in the 1 ÷ 1000 TeV energy range. The ARGO-YBJ detector consists of a single layer of RPCs operated in streamer mode, housed in a large building of about 11000 m2). Signals from each RPC are picked up with 80 readout strips 61.8 cm wide and 6.75 cm long (23 strips/m2) that allow the shower front reconstruction with a high space-time resolution. In order to fully investigate the PeV region, where the previous (digital) readout saturates, an analog one has been implemented by instrumenting each RPC with two large size electrodes of dimension 1.39 × 1.23 m2. The 130 Clusters of the central carpet have been instrumented with the charge readout hardware and software since November 2009. In this paper we describe the hardware solution that implements the real-time charge readout in the ARGO-YBJ experiment, paying a special attention to the synchronization with the central data acquisition system, which is also described.

INFN Camera demonstrator for the Cherenkov Telescope Array

The Cherenkov Telescope Array is a world-wide project for a new generation of ground-based Cherenkov telescopes of the Imaging class with the aim of exploring the highest energy region of the electromagnetic spectrum. With two planned arrays, one for each hemisphere, it will guarantee a good sky coverage in the energy range from a few tens of GeV to hundreds of TeV, with improved angular resolution and a sensitivity in the TeV energy region better by one order of magnitude than the currently operating arrays. In order to cover this wide energy range, three different telescope types are envisaged, with different mirror sizes and focal plane features. In particular, for the highest energies a possible design is a dual-mirror Schwarzschild-Couder optical scheme, with a compact focal plane. A silicon photomultiplier (SiPM) based camera is being proposed as a solution to match the dimensions of the pixel (angular size of ~ 0.17 degrees). INFN is developing a camera demonstrator made by 9 Photo Sensor Modules (PSMs, 64 pixels each, with total coverage 1/4 of the focal plane) equipped with FBK (Fondazione Bruno Kessler, Italy) Near UltraViolet High Fill factor SiPMs and Front-End Electronics (FEE) based on a Target 7 ASIC, a 16 channels fast sampler (up to 2GS/s) with deep buffer, self-trigger and on-demand digitization capabilities specifically developed for this purpose. The pixel dimensions of

The trigger supervisor of the ARGO-YBJ detector

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A time-to-digital converter based on a digitally controlled oscillator

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The Argo YBJ Daq System and the GRID Based Data Transfer

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A general estimator of the primary cosmic ray energy with the ARGO-YBJ experiment

lead to a very compact design with challenging problems of thermal dissipation. A modular structure, made by copper frames hosting one PSM and the corresponding FEE, has been conceived, with a water cooling system to keep the required working temperature. The actual design, the adopted technical solutions and the achieved results for this demonstrator are presented and discussed.

Layout and performance of RPCs used in the Argo-YBJ experiment

ARGO-YBJ is a full coverage air shower detector under construction at the Yangbajing Laboratory (4300 m a.s.l., Tibet, People Republic of China). Its main fields of research are gamma ray astronomy and cosmic ray studies. The detector covers ~5800 m2 with single layer resistive plate counters (RPCs), surrounded by a partially instrumented guard ring. This paper describes in detail the ARGO-YBJ trigger supervisor, which provides the interface between the data acquisition and the trigger system. It is a simple and robust control instrument that monitors continuously the dead time at different levels of the DAQ architectures. We present in this paper the results of the first pilot runs at the Yangbajing laboratory

Proton-air cross section measurement with the ARGO-YBJ cosmic ray experiment

Time measurements play a crucial role in trigger and data acquisition systems of high-energy physics experiments, where synchronization between system elements, signal calibration, and phase-measurement accuracy is often required. In this paper, we present a fully digital time-to-digital converter (TDC) architecture and its application, based on a synthesizable digitally controlled oscillator (DCO), where the TDC is used to measure the phase relationship between a timing signal and a 40-MHz reference clock. The DCO design is technology independent; it is described by means of a hardware description language and it can be placed and routed with automatic tools. The TDC will be used in the new readout chip that is under development for the muon detector electronic upgrade in Large Hadron Collider beauty experiment at CERN. The TDC presented in this paper has the fundamental task of measuring, with a resolution of about 1.5 ns, the phase difference between the 40-MHz LHC machine clock and a digital signal coming from the muon detector.

Local Station: the data read-out basic unit for the ARGO-YBJ experiment

The Argo-YBJ experiment has now reached its final design configuration. The detector system consists of a full coverage array (about 5800 square meters) of resistive plate chambers (RPCs). The throughput depends on the trigger rate and threshold. The DAQ system must be able to sustain a maximum transfer rate of the order of 15 MB/s and a high peak data flow. Data are read out using a typical front-end acquisition chain built around a custom bus. Specialized electronics have been designed and dedicated software has been written to perform this task. Data are sent to the online farm through a switch exploiting a gigabit ethernet protocol. A solution to transfer data from the YBJ laboratory to the laboratories belonging to the Argo-YBJ collaboration exploiting the GRID middleware has also been implemented. In this paper we describe the daq and the data mover main characteristics and performance.