Nb3Sn Targets Synthesis via Liquid Tin Diffusion for Thin Films Depositions

The deposition of superconducting Nb3 Sn on copper accelerating cavities is interesting for the higher thermal conductivity of copper compared to common Nb substrates. The better heat exchange would allow the use of cryocoolers reducing cryogenic costs and the risk of thermal quench [1]. The magnetron sputtering technology allows the deposition of Nb 3 Sn on substrates different than Nb, however the coating of substrates with complex geometry (such as elliptical cavities) may require target with non-planar shape, which are difficult to realize with classic powder sintering techniques. In this work, the possibility of using the Liquid Tin Diffusion (LTD) technique to produce sputtering targets is explored. The LTD technique is a wire fabrication technology, already developed in the past at LNL for superconducting radio frequency (SRF) applications [2], that allows the deposition of very thick and uniform coating on Nb substrates even with complex geometries [3]. Improvements in LTD process, proof of concept of a single use LTD target production, and characterization of the Nb 3 Sn film coated by DC magnetron sputtering with these innovative targets are reported in this work

Nb3Sn Targets Synthesis via Liquid Tin Diffusion for Thin Films Depositions

The deposition of superconducting Nb3 Sn on copper accelerating cavities is interesting for the higher thermal conductivity of copper compared to common Nb substrates. The better heat exchange would allow the use of cryocoolers reducing cryogenic costs and the risk of thermal quench [1]. The magnetron sputtering technology allows the deposition of Nb 3 Sn on substrates different than Nb, however the coating of substrates with complex geometry (such as elliptical cavities) may require target with non-planar shape, which are difficult to realize with classic powder sintering techniques. In this work, the possibility of using the Liquid Tin Diffusion (LTD) technique to produce sputtering targets is explored. The LTD technique is a wire fabrication technology, already developed in the past at LNL for superconducting radio frequency (SRF) applications [2], that allows the deposition of very thick and uniform coating on Nb substrates even with complex geometries [3]. Improvements in LTD process, proof of concept of a single use LTD target production, and characterization of the Nb 3 Sn film coated by DC magnetron sputtering with these innovative targets are reported in this work

Nb3Sn Targets Synthesis via Liquid Tin Diffusion for Thin Films Depositions

The deposition of superconducting Nb3 Sn on copper accelerating cavities is interesting for the higher thermal conductivity of copper compared to common Nb substrates. The better heat exchange would allow the use of cryocoolers reducing cryogenic costs and the risk of thermal quench [1]. The magnetron sputtering technology allows the deposition of Nb 3 Sn on substrates different than Nb, however the coating of substrates with complex geometry (such as elliptical cavities) may require target with non-planar shape, which are difficult to realize with classic powder sintering techniques. In this work, the possibility of using the Liquid Tin Diffusion (LTD) technique to produce sputtering targets is explored. The LTD technique is a wire fabrication technology, already developed in the past at LNL for superconducting radio frequency (SRF) applications [2], that allows the deposition of very thick and uniform coating on Nb substrates even with complex geometries [3]. Improvements in LTD process, proof of concept of a single use LTD target production, and characterization of the Nb 3 Sn film coated by DC magnetron sputtering with these innovative targets are reported in this work

Thick Film Morphology and SC Characterizations of 6 GHz Nb/Cu Cavities

Thick films deposited in long pulse DCMS mode onto 6 GHz copper cavities have demonstrated the mitigation of the Q-slope at low accelerating fields. The Nb thick films (~40 microns) show the possibility to reproduce the bulk niobium superconducting properties and morpholo-gy characterizations exhibited dense and void-free films that are encouraging for the scaling of the process to 1.3 GHz cavities. In this work a full characterization of thick films by DC magnetometry, computer tomography, SEM and RF characterizations are presented

Main highlights of ARIES WP15 collaboration

International audienceAn international collaboration of research teams from CEA (France), CERN (Switzerland), INFN/LNL (Italy), HZB and USI (Germany), IEE (Slovakia), RTU (Latvia) and STFC/DL (UK), are working together on better understanding of how to improve the properties of superconducting thin films (ScTF) for RF cavities. The collaboration has been formed as WP15 in the H2020 ARIES project funded by EC. The systematic study of ScTF covers: Cu substrate polishing with different techniques (EP, SUBU, EP+SUBU, tumbling, laser), Nb, NbN, Nb₃Sn and SIS film deposition and characterisation, Laser post deposition treatments, DC magnetisation characterisation, application of all obtained knowledge on polishing, deposition and characterisation, Laser post deposition treatments, DC magnetisation characterisation, application to the QPR samples for testing the films at RF conditions. The preparation, deposition and characterisation of each sample involves 3-5 partners enhancing the capability of each other and resulting in a more complete analysis of each film. The talk will give an overview of the collaborative research and will be an introduction to the detailed talks given by the team members

Progress in European Thin Film Activities

International audienceThin-film cavities with higher Tc superconductors (SC) than Nb promise to move the operating temperature from 2 to 4.5 K with savings 3 orders of magnitude in cryogenic power consumption. Several European labs are coordinating their efforts to obtain a first 1.3 GHz cavity prototype through the I.FAST collaboration and other informal collaborations with CERN and DESY. R&D covers the entire production chain. In particular, new production techniques of seamless Copper and Niobium elliptical cavities via additive manufacturing are studied and evaluated. New acid-free polishing techniques to reduce surface roughness in a more sustainable way such as plasma electropolishing and metallographic polishing have been tested. Optimization of coating parameters of higher Tc SC than Nb (Nb₃Sn, V₃Si, NbTiN) via PVD and multilayer via ALD are on the way. Finally, rapid heat treatments such as Flash Lamp Annealing and Laser Annealing are used to avoid or reduce Cu diffusion in the SC film. The development and characterization of SC coatings is done on planar samples, 6 GHz cavities, choke cavities, QPR and 1.3 GHz cavities. This work presents the progress status of these coordinated efforts

Indicatori ambientali nello studio EpiAir2: I dati di qualit\ue0 dell'aria per la sorveglianza epidemiologica

OBIETTIVO: costruzione di indicatori ambientali di inquinamento aerodiffuso per finalit\ue0 di sorveglianza epidemiologica in 25 citt\ue0 italiane per il progetto EpiAir2 (2006-2010) e presentazione dei dati di dieci anni di sorveglianza in 10 citt\ue0 italiane (2001-2010). DISEGNO: sono stati raccolti dati di particolato (nelle frazioni PM10 e PM2.5 ), biossido di azoto (NO2 ) e ozono (O3 ), considerati fattori di rischio per la salute. I datimeteorologici considerati come confondenti nell\u2019analisi dell\u2019effetto degli inquinanti sono stati: temperatura, umidit\ue0 relativa (e la variabile derivata \u201ctemperatura apparente\u201d) e pressione barometrica. I criteri per la selezione delle stazioni dimonitoraggio e imetodi di calcolo per la costruzione di indicatori ambientali a partire dalle serie giornaliere disponibili sono stati scelti in continuit\ue0 con la precedente edizione di EpiAir. Per tutte le citt\ue0, \ue8 stata verificata l\u2019omogeneit\ue0 dei dati selezionati nel rappresentare l\u2019esposizione delle popolazioni. SETTING E PARTECIPANTI: il progetto EpiAir2 coinvolge per gli anni 2006-2010 le citt\ue0 diMilano,Mestre-Venezia,Torino, Bologna, Firenze, Pisa, Roma,Taranto,Cagliari e Palermo, gi\ue0 presenti nello studio EpiAir. A questo elenco vanno aggiunte le citt\ue0 di Treviso, Trieste, Padova, Rovigo, Piacenza, Parma, Ferrara, Reggio Emilia, Modena, Genova, Rimini, Ancona, Bari, Napoli e Brindisi. RISULTATI: nel periodo considerato \ue8 stato osservato un decremento delle concentrazioni di particolato nella maggior parte delle citt\ue0 in analisi, mentre non si pu\uf2 giungere a conclusioni cos\uec nette per NO2 e ozono. L\u2019analisi dell\u2019andamento temporale degli indicatori ha evidenziato valori medi annuali di PM10 superiori ai 40 \u3bcg/m3 in alcune citt\ue0 della Pianura Padana, e valori medi annuali di NO2 costantemente superiori ai 40 \u3bcg/m3 nelle citt\ue0 di Trieste, Milano, Padova, Torino, Modena, Bologna, Roma e Napoli. CONCLUSIONE: l\u2019ampliamento del progetto EpiAir, con l\u2019inclusione di ulteriori 13 citt\ue0, ha permesso di evidenziare peculiarit\ue0 legate alle differenti aree geografiche in studio e numerose situazioni di criticit\ue0 con superamenti dei valori di concentrazione limite fissati dalla legislazione corrente. I risultati dello studio EpiAir2 confermano la necessit\ue0 di un sistema di sorveglianza dell\u2019inquinamento aerodiffuso nei centri urbani e industriali al fine di ottenere stime affidabili dell\u2019esposizione della popolazione residente e di monitorarne l\u2019andamento nel tempo

Impatto a breve termine dell'inquinamento dell'aria nelle citt\ue0 coperte dalla sorveglianza epidemiologica EpiAir2

OBIETTIVO: stimare l\u2019impatto a breve termine dell\u2019inquinamento atmosferico sulla popolazione adulta di 23 citt\ue0 italiane nel periodo 2006-2009 nell\u2019ambito del progetto EpiAir2. DISEGNO, MATERIALI E METODI: per ogni citt\ue0 inclusa nello studio \ue8 stato calcolato l\u2019impatto dell\u2019effetto a breve termine dell\u2019inquinamento atmosferico sulla mortalit\ue0. In particolare, sono stati calcolati i decessi attribuibili a concentrazioni delle polveri (PM10 e PM2.5) superiori a soglie differenti definite dalla legislazione europea o nell\u2019ambito delle linee guida dell\u2019Organizzazione mondiale della sanit\ue0 (per il PM10: 20 e 40 \u3bcg/m3, riduzione del 20% ad arrivare a 20 \u3bcg/m3 e superamento del limite di 35 giorni con concentrazioni medie di 50 \u3bcg/m3; per il PM2.5: 10, 18 e 25 \u3bcg/m3, riduzione del 20% ad arrivare a 18 \u3bcg/m3). La stima di impatto \ue8 stata ottenuta combinando la stima di effetto delle polveri, il livello di mortalit\ue0 osservato e i livelli di concentrazione degli inquinanti misurati dalle reti di monitoraggio urbane. Per quanto riguarda le stime di effetto, sono state utilizzate le distribuzioni a posteriori specifiche per citt\ue0 risultanti da una metanalisi bayesiana. L\u2019incertezza sulle stime di impatto \ue8 stata calcolata con metodi Monte Carlo. RISULTATI: nell\u2019insieme delle 23 citt\ue0 valutate nel presente studio il numero di decessi attribuibili agli effetti a breve termine delle concentrazioni di PM10 superiori a 20 \u3bcg/m3 e di PM2.5 superiori a 10 \u3bcg/m3 nel periodo 2006-2009 \ue8 risultato rispettivamente pari allo 0,9% (assumendo indipendenza tra citt\ue0 l\u2019intervallo di credibilit\ue0 all\u201980% \ue8 0,4-1,4) e allo 0,8% (ICr80% 0,2-1,3) della mortalit\ue0 naturale. L\u2019impatto delle concentrazioni di polveri PM10 e PM2.5 \ue8 risultato concentrato nelle citt\ue0 della Pianura Padana, della Piana fiorentina, e nelle grandi realt\ue0 metropolitane di Roma, Napoli e Palermo: per il PM10 la percentuale sui decessi \ue8 risultata 1,0% (ICr80% 0,4-1,5) contro 0,4% (ICr80% 0,2-0,7) nelle altre citt\ue0 analizzate. Se i livelli di concentrazione delle polveri fossero stati inferiori del 20%, complessivamente l\u2019impatto si sarebbe ridotto del 42% per il PM10 e del 51% per il PM2.5. CONCLUSIONI: i livelli di inquinamento osservati nel periodo in studio sono stati responsabili di un numero importante di decessi nelle citt\ue0 analizzate. Politiche di contenimento basate sulla diminuzione percentuale delle concentrazioni annuali di polveri interesserebbero tutte le citt\ue0 coperte dallo studio e potrebbero ridurre in modo importante l\u2019impatto dell\u2019inquinamento sulla salute