18856410
Test of the end-ladder prototype board of the ALICE SDD experiment
The paper presents an end-ladder card prototype of the data acquisition chain of the ALICE SDD experim ent. The prototype includes most of the electronics devices that will be applied to ALICE SDD experiment. The card interface s with the front-end electronics and with the counting roo m detector data link via the interface card named CARLOS_rx. T he end_ladder PCB has been fully tested by providing c ontrol signals and input vectors via a pattern generator a nd by collecting output data via the detector data link.
46500747
Implementation of a bidimensional compressor for a high-energy physics experiment
CARLOSv3 is the third version of a chip that plays a significant role in the data acquisition chain of the A Large Ion Collider Experiment (ALICE) silicon drift detector (SDD). ALICE is one of the foremost high-energy physics experiments (HEPE) conducted within the Large Hadron Collider at CERN, the European Organization for Nuclear Research in Geneva. CARLOSv3 was principally designed and built for the on-line compression of the input dataset originating from a physical bidimensional silicon sensor. To compress a bidimensional dataset, a bidimensional data compressor was required. The compressor was designed for the ALICE SDD Experiment but could be applied to all experiments in which an incoming stream dataset originates from a bidimensional sensor.
123625473
Architecture of a general purpose embedded Slow-Control Adapter ASIC for future high-energy physics experiments
Abstract This work is aimed at defining the architecture of a new digital ASIC, namely Slow-Control Adapter (SCA), which will be designed in a commercial 130-nm CMOS technology. This chip will be embedded within a high-speed data acquisition optical link (GBT) to control and monitor the front-end electronics in future high-energy physics experiments. The GBT link provides a transparent transport layer between the SCA and control electronics in the counting room. The proposed SCA supports a variety of common bus protocols to interface with end-user general-purpose electronics. Between the GBT and the SCA a standard 100 Mb/s IEEE-802.3 compatible protocol will be implemented. This standard protocol allows off-line tests of the prototypes using commercial components that support the same standard. The project is justified because embedded applications in modern large HEP experiments require particular care to assure the lowest possible power consumption, still offering the highest reliability demanded by very large particle detectors.
109308730
Heavy-Ions induced SEE effects measurements for the STRURED ASIC
With the aim of developing a radiation-tolerant circuit, a digital test microelectronic device has been designed and fabricated by using a standard-cell library of a 130-nm CMOS technology, including three different architectures to correct circuit malfunctions induced by the occurrence of Single-Event Effects (SEEʼs). SEEʼs are one of the main reasons of failures affecting electronic circuits operating in harsh radiation environments, such as in experiments performed at High Energy Physics (HEP) colliders or in apparatus to be operated in Space. On the same digital circuit specifically designed, three redundant architectures added to a basic scheme have been implemented in order to evaluate their effectiveness to prevent SEE. This may give an indication on their usage in future digital circuits specifically designed for the above mentioned applications. We present the results of SEE cross section measurements performed on a test digital device exposed to a high energy heavy ion beam at the SIRAD irradiation facility of the INFN National Laboratories of Legnaro (Padova Italy).
56367755
Design of an integrated particle detector-cell based on latchup effect
The paper describes an innovative idea for a silicon pixel detector. The principle is based on latchup effect that is common in to-date CMOS technologies working in a radiation environment. A prototype was constructed in the past with commercial components and here is described in detail an integrated version of the design. In principle the detector has low triggering and dead time, can operate at room temperature, does not require a high voltage power supply and is intrinsically tolerant to radiation. As a latchup-based detector can be constructed using state-of-the-art CMOS technologies, here it is presented a design of a prototype that will be implemented on a commercial 0.35 μm Bi-CMOS technology and tested at Electronics Department of Torino Politecnico.
109494522
Design, realization and test of a rad-hard 2D-compressor and packing chip for high energy physics experiments
CARLOSv3 is a third version of a chip that plays a significant role in the data acquisition chain of the A Large Ion Collider Experiment Inner Tracking System experiment. It has been designed and realized with a 0.25 μm CMOS 3-metal rad-hard digital library. The chip elaborates and compresses, by means of a bi-dimensional compressor, data belonging to a so-called event. The compressor looks for cross-shaped clusters within the whole data set coming from the silicon detector. To test the chip a specific PCB has been designed; it contains the connectors for probing the ASIC with a pattern generator and a logic state analyzer. The chip is inserted on the PCB using a ZIF socket. This allows to test the 35 packaged samples out of the total amount of bare chips we have from the foundry. The test phase has shown that 32 out of 35 chips under test work well. It is planned to redesign a new version of the chip by adding extra features and to submit the final version of CARLOS upon the final DAQ chain will be totally tested both in Bologna and at CERN.
14466810
Basic properties of galaxy clustering in the light of recent results from the Sloan Digital Sky Survey
We discuss some of the basic implications of recent results on galaxy correlations published by the SDSS collaboration. In particular we focus on the evidence which has been recently presented for the scale and nature of the transition to homogeneity in the galaxy distribution, and results which describe the dependence of clustering on luminosity. The two questions are in fact strictly entangled, as the stability of the measure of the amplitude of the correlation function depends on the scale at which the mean density becomes well defined. We note that the recent results which indicate the convergence to well defined homogeneity in a volume equivalent to that of a sphere of radius 70 Mpc/h, place in doubt previous detections of luminosity bias from measures of the amplitude of the correlation function. We emphasize that the way to resolve these issues is to first use, in volume limited samples corresponding to different ranges of luminosity, the unnormalized two point statistics to establish the scale (and value) at which the mean density becomes well defined. We note also that the recent SDSS results for these statistics are in good agreement with those obtained by us through analyses of many previous samples, confirming in particular that the galaxy distribution is well described by a fractal dimension D 2 up to a scale of at least 20 Mpc/h. We discuss critically the agreement of this new data with current theoretical models.
33686678
Force distribution in a randomly perturbed lattice of identical particles with 1/r2 pair interaction.
We study the statistics of the force felt by a particle in the class of a spatially correlated distribution of identical pointlike particles, interacting via a 1/r2 pair force (i.e., gravitational or Coulomb), and obtained by randomly perturbing an infinite perfect lattice. We specify the conditions under which the force on a particle is a well-defined stochastic quantity. We then study the small displacements approximation, giving both the limitations of its validity and, when it is valid, an expression for the force variance. The method introduced by Chandrasekhar to find the force probability density function for the homogeneous Poisson particle distribution is extended to shuffled lattices of particles. In this way, we can derive an approximate expression for the probability distribution of the force over the full range of perturbations of the lattice, i.e., from very small (compared to the lattice spacing) to very large where the Poisson limit is recovered. We show in particular the qualitative change in the large-force tail of the force distribution between these two limits. Excellent accuracy of our analytic results is found on detailed comparison with results from numerical simulations. These results provide basic statistical information about the fluctuations of the interactions (i) of the masses in self-gravitating systems like those encountered in the context of cosmological N -body simulations, and (ii) of the charges in the ordered phase of the one-component plasma, the so-called Coulomb or Wigner crystal.
58911681
Peaks in the CMBR power spectrum. I. Mathematical analysis of the associated real space features
The purpose of our study is to understand the mathematical origin in real space of modulated and damped sinusoidal peaks observed in cosmic microwave background radiation anisotropies. We use the theory of the Fourier transform to connect localized features of the two-point correlation function in real space to oscillations in the power spectrum. We also illustrate analytically and by means of Monte Carlo simulations the angular correlation function for distributions of filled disks with fixed or variable radii capable of generating oscillations in the power spectrum. While the power spectrum shows repeated information in the form of multiple peaks and oscillations, the angular correlation function offers a more compact presentation that condenses all the information of the multiple peaks into a localized real space feature. We have seen that oscillations in the power spectrum arise when there is a discontinuity in a given derivative of the angular correlation function at a given angular distance. These kinds of discontinuities do not need to be abrupt in an infinitesimal range of angular distances but may also be smooth, and can be generated by simply distributing excesses of antenna temperature in filled disks of fixed or variable radii on the sky, provided that there is a non-null minimum radius and/or the maximum radius is constrained.
1069360
Fluctuations in galaxy counts: A new test for homogeneity vs. fractality
Fractal properties are usually characterized by means of various statistical tools which deal with spatial average quantities. Here we focus on the determination of fluctuations around the average counts and we develop a test for the study of galaxy distribution both in redshift and magnitude space. Fluctuations in the counts of galaxies, in a fractal distribution, are of the same order of the average number at all scales as a function of redshift and magnitude. We point out that the study of these kinds of fluctuations can be a powerful test to understand the nature of galaxy clustering at very large scales.
15853720
Galaxy number counts and fractal correlations
We report the correlation analysis of various redshift surveys which shows that the available data are consistent with each other and manifest fractal correlations (with dimension D 2) up to the present observational limits ( ≈ 150 h−1Mpc) without any tendency towards homogenization. This result points to a new interpretation of the number counts that represents the main subject of this letter. We show that an analysis of the small-scale fluctuations allows us to reconcile the correlation analysis and the number counts in a new perspective which has a number of important implications.