Trigger for rare kaon decays searches at the CERN NA62 experiment

The work reported in this thesis has been carried out within the Trigger and Data Acquisition (TDAQ) working group of the CERN NA62 experiment, and focused on the development of a trigger strategy for collecting rare kaon decays. The main aim of the NA62 experiment is the study of the ultra rare decay K+ -> pi+ nu nu in order to provide a stringent test of the Standard Model. The theoretical framework of the K+ -> pi+ nu nu decay, the present experimental status of the measurement of the Branching Ratio and the NA62 experimental strategy are described in chapter 1. Chapter 2 provides a description of the NA62 experimental setup. The first part of the work concerned the design, development and assessment of the common Trigger and Data Acquisition system for the majority of detectors in NA62, a high-speed integrated data acquisition and trigger generation system based on digital high resolution time measurements. The architecture of the boards, a detailed description of the developed firmwares and some results obtained during the NA62 TDAQ commissioning phase are presented in chapter 3. The second part of the work focused on Monte Carlo studies of hardware low-level (L0) trigger schemes with the purpose of selecting interesting decays. The dependence of the L0 output trigger rate and of the trigger efficiency upon the variation of several trigger parameters has been studied. The optimization of the L0 trigger scheme for the selection of K+ -> pi+ nu nu decays is described in chapter 4. In addition, a L0 trigger selection for the search for a hypothetical dark photon (U) in pi0 decays is discussed in chapter 5. After a general introduction about the searches for rare and forbidden kaon decays at NA62, the physics motivations and the experimental status are described. Finally, the NA62 expected upper limits on the Branching Ratio of the pi0->gU,U->e+e- decay are computed and compared with present limits

Studio di un trigger di molteplicita' basato su un rivelatore RICH

Il lavoro di tesi in questione e' stato svolto all'interno del gruppo dell'INFN di Pisa che partecipa all'esperimento NA62 presso i laboratori del CERN di Ginevra, in particolare nell'ambito del gruppo che si occupa del sistema di trigger e acquisizione dati (TDAQ) dell'esperimento. L'obiettivo finale ha riguardato la valutazione della possibilita' di messa a punto di un trigger, attraverso il sistema di acquisizione dati oggetto di studio, basato sul rivelatore RICH dell'esperimento NA62. Inizialmente, e' presentata un'introduzione riguardante l'esperimento NA62 con la descrizione dell'obiettivo dell'esperimento, successivamente sono esposti dei cenni alla fisica del decadimento, con le conseguenti motivazioni della misura obiettivo dell'esperimento, seguiti dalla strategia sperimentale. In secondo luogo viene descritto l'apparato sperimentale di NA62: sono presentate brevi indicazioni riguardanti la produzione del fascio di K+ e i singoli rivelatori. L'esposizione e' piu' ampia per la strumentazione direttamente coinvolta nel lavoro originale della tesi: il RICH, e il sistema di trigger e acquisizione dati, con una spiegazione abbastanza dettagliata dei componenti elettronici e delle loro modalita' di funzionamento. Nella parte principale dell'elaborato viene presentato il lavoro originale, diviso in due parti: la prima riguarda la partecipazione ai due test del prototipo RICH-400 e del sistema di acquisizione dati TELL1-TDC, la seconda focalizza l'obiettivo dello studio della realizzazione di un trigger di molteplicita' basato sul rivelatore RICH. In riferimento al primo test, viene esposta dettagliatamente l'analisi dati eseguita personalmente, e sono mostrati i risultati ottenuti riguardanti in particolare il calcolo della risoluzione temporale dei fotomoltiplicatori, e lo studio di problemi emersi quali la presenza di canali rumorosi e di hits mancanti. In merito al secondo test, viene mostrato il lavoro personalmente svolto consistente nella realizzazione di un monitor online; sono poi presentati alcuni risultati di rilievo ottenuti dal test. L'ultima parte descrive minuziosamente la ricostruzione di eventi di segnale K+ -> pi+ nu nu, generati con una simulazione Montecarlo; in particolare viene analizzato il comportamento del rivelatore RICH, studiando la possibilita' di applicazione di diverse configurazioni del sistema di readout TELL1-TDC al rivelatore stesso. L'analisi messa a punto, e i risultati presentati, mostrano la risposta del sistema all'applicazione di una soglia sul trigger di molteplicita': su eventi di segnale, in termini di efficienza al variare della soglia impostata, e su eventi corrispondenti ai principali decadimenti di fondo del K+, in termini di riduzione del rate totale sul RICH

A lithium-ion battery based on a graphene nanoflakes ink anode and a lithium iron phosphate cathode

Li-ion rechargeable batteries have enabled the wireless revolution transforming global communication. Future challenges, however, demands distributed energy supply at a level that is not feasible with the current energy-storage technology. New materials, capable of providing higher energy density are needed. Here we report a new class of lithium-ion batteries based on a graphene ink anode and a lithium iron phosphate cathode. By carefully balancing the cell composition and suppressing the initial irreversible capacity of the anode, we demonstrate an optimal battery performance in terms of specific capacity, i.e. 165 mAhg-1, estimated energy density of about 190 Whkg-1 and life, with a stable operation for over 80 charge-discharge cycles. We link these unique properties to the graphene nanoflake anode displaying crystalline order and high uptake of lithium at the edges, as well as to its structural and morphological optimization in relation to the overall battery composition. Our approach, compatible with any printing technologies, is cheap and scalable and opens up new opportunities for the development of high-capacity Li-ion batteries.Comment: 17 pages, 10 figure

Best-Estimate for System Codes (BeSYC): A New Software to Perform Best-Estimate Plus Uncertainty Analyses with Thermal-Hydraulic and Safety System Codes for Both Fusion and Fission Scenarios

The development and the validation of old and new software in relevant DEMO reactor conditions have been exploited in the latest years within the EUROfusion Consortium. The aim was to use—if possible—the software already validated for fission reactors and to fill the gaps with new ad-hoc software. As contribution to this effort, the Karlsruhe Institute of Technology (KIT) developed and tested a novel software to apply the Best-Estimate Model Calibration and Prediction through Experimental Data Assimilation methodology to the system codes RELAP5-3D, MELCOR 1.8.6, and MELCOR 2.2. This software is called Best-estimate for SYstem Codes (BeSYC), and it is developed as a MATLAB App. The application is in charge of applying the mathematical framework of the methodology, writing and executing the code runs required by the methodology, and printing the obtained results. The main goal of BeSYC is to wrap up the methodology in a software suitable to be used by any user through a simple graphical user interface. Albeit developed in the fusion research context, BeSYC can be applied to any reactor/scenario type supported by the specific system code. The goals of BeSYC, the mathematical framework, the main characteristics, and the performed verification and validation activities are described in this paper

Post-Test Numerical Analysis of a Helium-Cooled Breeding Blanket First Wall under LOFA Conditions with the MELCOR Fusion Code

The validation of numerical tools employed in the analysis of incidental transients in a fusion reactor is a topic of main concern. KIT is taking part in this task providing both experimental data and by performing numerical analysis in support of the main codes used for the safety analyses of the Helium Cooled Pebble Bed (HCPB) blanket concept. In recent years, an experimental campaign has been performed in the KIT-HELOKA facility to investigate the behavior of a First Wall Mock-Up (FWMU) under Loss Of Flow Accident (LOFA) conditions. The aim of the experimental campaign was twofold: to check the expected DEMO thermal-hydraulics conditions during normal and off-normal conditions and to provide robust data for code validation. The present work is part of these validation efforts, and it deals with the analysis of the LOFA experimental campaign with the system code MELCOR 1.8.6 for fusion. A best-estimate methodology has been used in support of this analysis to ease the distinction between user’s assumptions and code limitations. The numerical analyses are here described together with their goals, achievements, and lesson learn

The FPGA based trigger and data acquisition system for the CERN NA62 experiment

The main goal of the NA62 experiment at CERN is to measure the branching ratio of the ultra-rare K+ → π+vv decay, collecting about 100 events to test the Standard Model of Particle Physics. Readout uniformity of sub-detectors, scalability, efficient online selection and lossless high rate readout are key issues. The TDCB and TEL62 boards are the common blocks of the NA62 TDAQ system. TDCBs measure hit times from sub-detectors, TEL62s process and store them in a buffer, extracting only those requested by the trigger system following the matching of trigger primitives produced inside TEL62s themselves. During the NA62 Technical Run at the end of 2012 the TALK board has been used as prototype version of the L0 Trigger Processor

A high-resolution TDC-based board for a fully digital trigger and data acquisition system in the NA62 experiment at CERN

A Time to Digital Converter (TDC) based system, to be used for most sub-detectors in the high-flux rare-decay experiment NA62 at CERN SPS, was built as part of the NA62 fully digital Trigger and Data AcQuisition system (TDAQ), in which the TDC Board (TDCB) and a general-purpose motherboard (TEL62) will play a fundamental role. While TDCBs, housing four High Performance Time to Digital Converters (HPTDC), measure hit times from sub-detectors, the motherboard processes and stores them in a buffer, produces trigger primitives from different detectors and extracts only data related to the lowest trigger level decision, once this is taken on the basis of the trigger primitives themselves. The features of the TDCB board developed by the Pisa NA62 group are extensively discussed and performance data is presented in order to show its compliance with the experiment requirements.Comment: 6 pages, 7 figures, presented to IEEE RT 2014 Conference and I want to publish in TN

Graft-Versus-Leukemia Effect after Haplo-Identical Stem Cell Transplantation with Post-Transplant Cyclophosphamide in Patients with AML- No Association with Graft-Versus-Host Disease (GVHD): A Study on Behalf of the Acute Leukemia Working Party of EBMT.

Introduction Allogeneic stem-cell transplantation (SCT) is curative therapy in AML by providing intensive chemotherapy and enhancing a graft-versus-leukemia (GVL) effect. The GVL effect is usually closely associated with GVHD. The use of haploidentical SCT (haploSCT) is rapidly increasing due to the introduction of non-T depleted methods, in particular with post-transplant cyclophosphamide (PTCy), with similar outcomes as following other donor sources. There is no data whether GVL after haploSCT is associated with GVHD as in matched donor SCT. Methods We assessed the impact of acute and chronic GVHD on SCT outcomes following non-T depleted haploSCT with PTCy, by using a series of landmark analyses. Results The study included 605 patients with AML in CR1 (73%) or CR2 (27%) after haploSCT with PTCy, given during the years 2009-2016. The median age was 53 years (18-76). The overall rate of acute GVHD grade II-IV and III-IV was 28.4% and 8.0%, respectively. The rates of chronic GVHD all grades and extensive were 32.7% and 12.3%, respectively. The 2-year leukemia-free survival (LFS) was 59.9%. 509 patients were alive and leukemia-free 100 days after SCT; 366 had no prior acute GVHD at this landmark, 107 had acute GVHD grade II and 36 had grade III-IV. The subsequent relapse rate was 20.3%, 18.3% and 11.9%, respectively (P=0.60). The subsequent non-relapse mortality (NRM) rate was 10.3%, 19.0% and 35.7%, respectively (P Conclusions Acute and chronic GVHD of any grade were not associated with subsequent relapse. Acute GVHD grade III-IV and extensive chronic GVHD were associated with higher NRM and lower LFS. GVL is thus not closely associated with GVHD after non T-depleted haploSCT with PTCy. Future novel strategies for prevention of significant GVHD are warranted