Luigi Serio | CERN - Academia.edu (original) (raw)

Papers by Luigi Serio

… of the Nineteenth …, 2003

A major milestone in preparation of the construction, commissioning and operation of the Large Ha... more A major milestone in preparation of the construction, commissioning and operation of the Large Hadron Collider (LHC) is the assembly, commissioning and operation of a full-scale model representing a full-cell of the machine lattice, corresponding to the length of the elementary cooling ...

Proceedings of the 1999 Particle Accelerator Conference (Cat. No.99CH36366)

Proceedings of the Twentieth International Cryogenic Engineering Conference (ICEC20), 2005

Proceedings of the 30th European Safety and Reliability Conference and 15th Probabilistic Safety Assessment and Management Conference

IOP Conference Series: Materials Science and Engineering, 2017

Proceedings of the 30th European Safety and Reliability Conference and 15th Probabilistic Safety Assessment and Management Conference, 2020

IEEE Systems Journal, 2022

Functional dependencies in complex technical infras- tructures can cause unexpected cascades of f... more Functional dependencies in complex technical infras- tructures can cause unexpected cascades of failures. Given the complexity and continuous evolution in time of the infrastructure architecture, the identiﬁcation of functional dependencies using the classical methods of system decomposition and logic analysis is not feasible. Then, we consider the availability of databases of alarm messages and frame the identiﬁcation of functional dependencies in complex technical infrastructures as an optimization problem whose objective is the maximization of a metric measuring the level of dependence among alarms. A niching-based evolutionary algorithm has been developed to sequentially evolve a population of candidate solutions (group of alarms), maintaining diversity among them thanks to the use of a mechanism of population augmentation. The proposed algorithm is applied to a synthetic database of alarms generated by a complex technical infrastructure simulation model and to a real large-scale database of alarms collected from the particle accelerator of European Organization for Nuclear Re- search. The proposed algorithm is shown able to identify functional dependencies and to overperform other approaches based on the use of association rule mining algorithms, in terms of capability of extracting rare rules and computational efﬁciency.

Proceedings of the 29th European Safety and Reliability Conference (ESREL), 2019

This work proposes a methodology for identifying dependent abnormal behaviours through the extrac... more This work proposes a methodology for identifying dependent abnormal behaviours through the extraction of association rules from data. The practical case considered makes use of a database of alarms generated by different supervision systems of the CERN (European Centre for Nuclear Research) technical infrastructure. The methodology is based on the representation of the alarm database with a binary matrix and the use of the Apriori algorithm for mining association rules. An application to a large-scale database of alarms generated by various monitoring systems of the point 8 of CERN is presented.

2017 European Conference on Electrical Engineering and Computer Science (EECS), 2017

CERNs Accelerators facilities require adequate tools to operate, maintain and guide the consolida... more CERNs Accelerators facilities require adequate tools to operate, maintain and guide the consolidation of the machines, to fulfil the physics program and deliver the required luminosity for the experiments. It is therefore relevant to identify clear and easy metrics to monitor objectively the activities and guide the management to implement strategies, to improve performances, optimize costs as well as highlight key areas needing prioritization. Model-based is usually adopted to provide an early identification of failures and to reveal among several subsystems hidden dependencies. However system models are complex and require to be constantly updated to be reactive to system changes. Moreover, the availability of economic, high-efficient and smart sensors entails a growing data that, for volume and heterogeneity, are often difficult to analyse and to incorporate within the modelling process. The paper focuses on a novel approach which combines model-based and big data analytics principles. This involves machine learning techniques exploited to extract descriptive and predictive models directly from data, to foresee and react in time to the failures and reducing the downtimes of the machines which operate the largest particles accelerators complex of the world.

Flow measurement is mainly performed on the recovery at room temperature of vapour from liquid bo... more Flow measurement is mainly performed on the recovery at room temperature of vapour from liquid boil-off due to a lack of commercially available robust and precise cryogenic mass flowmeters. When high-accuracy or fast-time response is needed, or individual gas recovery at room temperature is not available, it is necessary to measure directly the fluid feed at cryogenic temperature. The results of extensive testing of industrially available and in-house developed flowmeters are presented in the paper. The characteristics and advantages of each measuring method are described.

An upgrade of the LHC injection chain, and especially the sequence of PS and SPS, up to an extrac... more An upgrade of the LHC injection chain, and especially the sequence of PS and SPS, up to an extraction energy of 1 TeV, is one of the steps considered to improve the performance of the whole LHC accelerator complex. The magnets for this upgrade require central magnetic field from 2 T (for a PS upgrade) to 4.5 T (for an SPS upgrade), and field ramp rate ranging from 1.5 to 2.5 T/s. In this paper we discuss under which conditions superconducting magnets are attractive in this range of operating field and field ramp-rate, and we list the outstanding issues to be adddressed by a dedicated R&D. MAGNET NEEDS AND R&D TARGETS

The Super FRS is a new 2 stage in flight separator to be built on the site of GSI, Darmstadt, Ger... more The Super FRS is a new 2 stage in flight separator to be built on the site of GSI, Darmstadt, Germany as part of FAIR (Facility for Anti-proton and Ion Research). It will be able to create and spatially separate rare isotopes from all elements up to Uranium. With it also very short lived nuclei will be able to be observed efficiently. The Super FRS has three branches so a wide variety of experiments can be carried out in frame of the NUSTAR collaboration. The large acceptance needed leads to large apertures of the magnets and therefore only a superconducting solution is feasible. The magnets of the Super-FRS are of so called superferric type, with superconducting coils but the field shaped by magnetic iron. In this contribution the actual status of the designs of the dipole and multipole magnets will be presented.

CERN, Accelerator Technology Department CH 1211 Geneva 23 Switzerland We analyze feasibility and ... more CERN, Accelerator Technology Department CH 1211 Geneva 23 Switzerland We analyze feasibility and cost of a superferric magnet design for the PS2. Specifically, we provide the conceptual design of dipole and quadrupoles, including considerations on cryogenics and powering. The magnets have warm iron yoke, and cryostated superconducting coils embedded in the magnet, which reduces AC loss at cryogenic temperature. The superconductor has large operating margin to endure beam loss and operating loads over a long period of time. Although conservative, and without any critical dependence on novel technology developments, this superconducting option appears to be attractive as a low-power alternative to the normal-conducting magnets that are the present baseline for the PS2 design. In addition it provides flexibility in the selection of flat-top duration at no additional cost.

IOP Conference Series: Materials Science and Engineering, 2017

Reliability Engineering & System Safety, 2021

… of the Nineteenth …, 2003

Proceedings of the 1999 Particle Accelerator Conference (Cat. No.99CH36366)

Proceedings of the Twentieth International Cryogenic Engineering Conference (ICEC20), 2005

Proceedings of the 30th European Safety and Reliability Conference and 15th Probabilistic Safety Assessment and Management Conference

IOP Conference Series: Materials Science and Engineering, 2017

Proceedings of the 30th European Safety and Reliability Conference and 15th Probabilistic Safety Assessment and Management Conference, 2020

IEEE Systems Journal, 2022

Proceedings of the 29th European Safety and Reliability Conference (ESREL), 2019

2017 European Conference on Electrical Engineering and Computer Science (EECS), 2017

IOP Conference Series: Materials Science and Engineering, 2017

Reliability Engineering & System Safety, 2021

This thesis is concerned with the design, development and testing of helium mass flowmeters based... more This thesis is concerned with the design, development and testing of helium mass flowmeters based on different technologies to be used as diagnostic tools for the cryogenic system of the Large Hadron Collider at CERN, the European laboratory for particle physics. The flowmeters were designed and the performance assessed for liquid, supercritical and superfluid helium down to 1.8 K and with pressures up to 0.3 MPa. A testing regime and equipment to enable the performance of a range of developed flowmeters to be validated at working cryogenic temperatures and pressures is described in the thesis. In particular a novel cryogenic flow test facility with 1.5 % accuracy as well as an irradiation test station designed, constructed and used as part of the evaluation work are described in the thesis. The final validation with metrological certification down to 0.5 % accuracy was performed in collaboration with the Colonnetti metrological laboratory in Italy. Devices based on the thermal exchange and transport properties of the fluid were developed and proven to be reliable and inexpensive but with accuracy poorer than 10 %. As part of this work a new empirical heat transfer correlation for supercritical helium in the piping geometry and operating conditions of the LHC was established. Industrially available Coriolis meters which had not been employed before at such low temperatures were extensively investigated. It was found that with some minor modifications in the electronics (drive system) and in the elasticity modulus (Young’s modulus) value for the flow tubes material at low temperature, accuracy down to 0.5 % could be achieved. Additional features in the mechanical and electrical design were also introduced to improve robustness and reliability at cryogenic temperatures. They mainly consisted in purging the meters secondary containment with helium to avoid gas freezing at low temperatures and increasing the internal gauge wire to improve its fatigue strength. The elasticity modulus of 316 L stainless steel below 20 K was characterised and compared to available literature data. The successful Coriolis flowmeters were validated to meter the cryogenic power distribution in the 27-km long superfluid helium system of the future collider and are now extensively and successfully used in superconducting devices test facilities at CERN and in companion laboratories.

A temperature derivative sensing and regulating device and method is described which facilitates ... more A temperature derivative sensing and regulating device and method is described which facilitates the maintainance of a very stable isothermal environment for an item, apparatus or facility or a constant rate of temperarture change. The device comprises a block of material having no internal heat sources, a thermal conductivity greater than 100 Wm1 K-1 and a specific heat capacity greater than 385 JK-1 kg-1. The block is surrounded by means for measuring the heat flow to and from the block and the device is further provided with means for generating a signal proportional to said heat flow and means for interfacing with the controller of a heating or cooling means associated with the item, apparatus or facility.

Termofluidodinamica applicata alle transizioni resistive dei magneti superconduttori ed al dimens... more Termofluidodinamica applicata alle transizioni resistive dei magneti superconduttori ed al dimensionamento e progettazione delle linee di evacuazione dell’elio