This PDF file contains the front matter associated with SPIE Proceedings Volume 11054, including the Title Page, Copyright information, Table of Contents, Author and Conference Committee lists.

Superconductivity and Particle Accelerator (SPAS) conference is devoted to research in the domain of superconductivity and its applications in science, as well as on research in the field of particle accelerators, conducted in Polish research institutions as well as by Polish scientists working in the international laboratories. The objective of SPAS conference is to identify current and potential areas of research in superconductivity and particle accelerators, developed and possible to develop in Poland and to determine the needs in the infrastructure to support this research. The SPAS’2018 program included all main areas related to the superconductivity and accelerators, and also included a task of challenges in thermonuclear projects, which are non-accelerator project but related to the superconductivity and superconducting technology developed for accelerators. Another interesting subjects presented during conference were the Rapid Single Quantum Flux electronics which uses Josephson junctions and could be possible used in superconducting quantum computer, and lead-free materials that could substitute materials containing lead in its composition.

Large particle accelerator science and technology requires well-coordinated and equally big community efforts to lead to meaningful discoveries. The discovery class accelerator infrastructures are increasingly bigger, more complex, and power hungry, which unavoidably evokes thoughts on the realisability of these trends in the future, concerning finances, social acceptability, and possible need of change of key accelerating technologies in the future. These efforts on the largest machines are accompanied by technical research, innovations and numerous applications of accelerator infrastructures useful for industry, environment protection, safety and health. To maintain the fast pace in these multithreaded developments for the society, a number of large infrastructural and research project are funded by various institutions and organizations, the major being the EC. The largest of these infrastructures are too big to be funded by a single country not to mention a single or even a consortium of laboratories. The article concisely presents some of the major particle accelerator organizations and especially projects recently and/or currently realized in the European research laboratories supported by the efforts from numerable university groups. The aim is to try to show, however subjectively, a dynamic portrait of a vivid European particle accelerators community in their activities to pursue and develop science, discovery class research tools, technology, innovation, transfer to industry, training and education, outreach and dissemination, continuation, but first of all communication, interaction and numerous activities in favor of the society.

new giant electron-positron collider, operating at energy frontier is a natural continuation and extension of the successful research at the LHC. The four projects of such accelerators: two linear (ILC and CLIC) and two circular (FCC-ee and CEPC) are currently in various stages of development. In the next few years important decisions are to be made about the realization of such collider(s). In particular, the issue of a future electron- positron collider plays a pivotal role in the discussions about the update of European strategy for particle physics. The most important features of the proposed accelerators will be presented. The article will also discuss the physics program for new e+e- colliders.

The Polish Free Electron Laser, PolFEL was proposed more than decade ago and at that time was accepted for the Polish Roadmap for Research Infrastructures. The facility was proposed to be built in two stages, at first, with fewer accelerating sections and lower beam energy and the second one, with more accelerating sections, delivering 600 MeV electrons to VUV undulator, generating in the Self Amplified Spontaneous Emission process coherent radiation at wavelength ranged down to 27 nm and 9 nm in the first and third harmonic mode, respectively. Over past decade new experimental methods have been proposed and developed, delivering interesting results obtained with relatively low energy coherent and non-coherent photon beams, for example with IR-UV and THz radiation. In this contribution, subsystems of an updated version of the first stage PolFEL facility will be discussed. The project has recently received funds from the Smart Growth Operational Programme, Measure 4.2: Development of modern research infrastructure of the science sector, and is currently in a preparation phase of the construction, which will begin in 2019.

Continuous Wave (CW) mode is the origin of the Superconducting Radio-Frequency (SRF) accelerator technology. European XFEL project¹ was based on the Linear Collider (LC) technology (TESLA) operating in the pulsed RF power mode (10Hz / 650μs beam pulse). Many FEL user experiments will get an advantage (or become possible) with CW mode operation. European XFEL (E-XFEL) SRF accelerator recently reached its project goal of 17.5 GeV electron beam energy. Possible CW mode linac operation scenario with 17 modified injector section cryo-modules (CM) may reach ~50% of that energy with 25μA (100pC and 250kHz) CW beam in E-XFEL. A Long Pulse (LP) mode (duty factor < 100%) may provide even higher beam energies and still long enough FEL radiation pulses. Very encouraging results have been obtained at DESY on Cryo Module Test Bench (CMTB) during CW/LP tests of EXFEL prototype CMs. The possibility to run an E-XFEL accelerating module in CW/LP mode was clearly shown together with reaching higher unloaded Q-factor of the cavities in the CM⁴.

The DEMO Oriented Neutron Source (DONES; DEMO -- DEMOnstration Power Station) is part of the Early Neutron Source (ENS), one of the EUROfusion work packages. The DONES system is designed to provide an accelerator-based D-Li neutron source that produces high energy neutrons at sufficient intensity to simulate the first wall neutron spectrum of future nuclear fusion reactors. The aim of this work was to optimise the superconducting linear accelerator (SRF-L) to meet two requirements at the same time: (a) deliver sufficient energy of the beam at the end of the linac, (b) minimize energy losses. To obtain reliable results, we used two calculation codes: TraceWin and GPT (General Particle Tracer) to simulate the accelerator system. Based on technical data for a four-cryomodule system provided by CEA (French Alternative Energies and Atomic Energy Commission), we investigated 66 variants of the accelerating system. The results were not satisfactory, so the design of the accelerator was changed to add a fifth cryomodule, and subsequently we calculated 13 variants of this new system. Calculation results for beam energy losses, statistical parameters of the beam and beam density in analysed phase spaces were obtained and compared in both codes. At present, the best result obtained is a beam energy of 40.4 MeV with no losses.

In 2014 the Directory and Scientific Council accepted the development of the cryogenic infrastructure at IFJ PAN in order to support research in the field of superconductivity. Since then some key decisions have been taken and executed. This paper will present the emerging of infrastructure components such as the new experimental hall and the new helium liquefier as well as future ideas of test stands design and development.

The European DEMOnstration Fusion Power Plant (EU-DEMO) is planned to be an intermediate step between ITER experimental reactor and a commercial fusion power plant, which should demonstrate feasibility of grid electricity production at a level of several hundred MW. Design and assessment studies on the EU-DEMO superconducting magnets, have been initially focused on several concepts of the winding pack (WP) of the Toroidal Field coil, but recently also first concepts of the Central Solenoid (CS) have been proposed. The EU-DEMO CS coil will be composed of 5 modules, positioned vertically one above the other. The central CS1 module will operate under the most severe conditions. In the present work a thermal-hydraulic analysis of the most recent design of the CS1 module, proposed by the EPFL-SCP team, is performed, aimed at the assessment of the minimum temperature margin at normal operating conditions. The considered WP consists of 10 sub-coils, which are layer-wound using HTS (Re-123), React & Wind Nb₃Sn and NbTi conductors in the high, medium and low field sections, respectively. Operation of conductors designed for each sub-coil is simulated using the THEA code. The current scenario of the CS1 coil includes the premagnetization, plasma current ramp-up (PCRU), burn and dwell phases. Our analysis is focused on the fast breakdown at the beginning of the PCRU phase, which features largest heat generation due to AC losses. It is shown, that the temperature margin in all conductors is well above 1.5 K for a value of nτ = 75 ms assumed in the characterization of AC coupling losses.

The European Spallation Source (ESS) is currently under installation phase. It requires involvement of highly specialized engineering teams, working together in order to install all necessary equipment and to commission the facility. The engineering team from IFJ PAN is contributing to this common effort at Lund and team of twenty engineers and technicians are working at ESS site. The team is involved in three main tasks: installation of Radio Frequency Distribution System, Cryomodule tests and installation of Power Converters.

New superconducting transfer lines known as Superconducting Links (SC Links) are being developed at CERN for the remote powering of upgraded superconducting insertion magnets in the framework of the High Luminosity Large Hadron Collider (HL-LHC) project. The purpose of the SC Links is to transfer current from power converters located in radiation-free areas to magnets located in the vicinity of the LHC interaction points via shorter REBCO High Temperature Superconductor (HTS) current leads. HTS current leads, connecting the superconducting link to the conventional cables of the power converters, allow a very high current densities to be carried and significantly reducing the cooling power required for conventional cables. The expected length of the superconducting lines can reach 130 m, depending on the location, spanning a vertical distance of about 80 m. Each of the link containing an assembly of MgB₂ cables supplying different systems, which will transfer a total current exceeding 150 kA. In order to validate the selected technical solutions and materials as well as to confirm the design reliability and robustness of the SC Links, the construction of a fully functional 60 m long demonstrator (DEMO1) of the 18 kA circuit of the SC Link is ongoing. Since 2018, the engineering team from IFJ PAN has been contributing to the Cold Powering activity (Work Package 6a of the HL-LHC project). This contribution includes among others, preparing of assembly procedures for the system, producing components for the demonstrator, assembling the demonstrator and participating in tests.

The High Luminosity LHC (HL-LHC) Project is an upgrade program of the Large Hadron Collider (LHC) at CERN, focused on increasing the luminosity, thus significantly enhancing the potential to discover new physics from rare events. Among many activities ongoing in this framework, the implementation of novel superconducting radio frequency (SRF) cavities - especially Crab Cavities - is foreseen for compensation of the bunch crossing angle, which is a reducing factor for LHC luminosity. Two different crab cavity designs have been developed: the Double Quarter Wave (DQW) and the Radio Frequency Dipole (RFD). A prototype cryomodule, hosting two DQW cavities, has been fabricated and assembled3 for validation tests, which are currently ongoing in the Super Proton Synchrotron (SPS) at CERN. Since 2016 the engineering team from IFJ PAN has been contributing to the Crab Cavities & RF project (Work Package 4 of the HL-LHC Project). This contribution has included the following activities: mechanical, electrical and vacuum preparation of DQW crab cavities for cold tests in the vertical cryostat, as well as the assembly process of the fully-dressed DQW cavities. After successful RF cavities qualification, the assembly of the DQW cryomodule and its preparation for the tests was also performed with the participation of the IFJ PAN team.

The Double Quarter Wave (DQW) Crab Cavity was designed to rotate the colliding bunches and in consequence to increase the luminosity of the LHC machine. Prior to launching series production detailed RF validation tests, both without and with beam, were performed at CERN. For the cavity preparation and RF performance validation before installation in the cryomodule, a comprehensive programme of RF surface preparation and cavity performance evaluation in liquid helium temperatures were carried out. Due to the unusual geometry of the DQW cavity there were a number of challenges both in preparation and RF testing that had to be addressed. The results and conclusions of the preparation process and cavity performance in the vertical test cryostat are presented in this paper in the form of a short technical report.

In the paper has been theoretically analyzed the influence of the nano-sized defects created in HTc superconductors, for instance during the irradiation in the nuclear accelerators, on the current-voltage characteristics and critical current of the HTc superconducting tapes, subjected to the bending strain process. Theoretical model of these characteristics has been proposed basing on the analysis of interaction of the magnetic pancake type vortices with nano-sized defects for various initial states. The model of the change of the bending strain acting on the superconducting filament or film for the second generation composite tape, in the comparison to the applied bending strain, following from the elasticity properties of superconducting tape and geometrical factor has been presented. Current-voltage characteristics versus bending strain have been calculated, which results are in good agreement with experimental data measured on Bi-2223 tape at liquid nitrogen temperature. Model predicts too the appearance of the dynamical anomalies of the current-voltage characteristics, observed us previously.

We present a new type of a quantum detector, namely, the superconducting single-photon detector (SSPD), and demonstrate that it can be implemented in various single-photon counting applications, ranging from the visible light to near-infrared telecommunication wavelengths. We describe the physics of the photoresponse of a superconducting nanostripe to a flux of single optical photons and present the operation principle of SSPDs, stressing that, currently, they significantly outperform any competing, research or commercial devices in terms of their quantum efficiency, counting rate, jitter, and unwanted dark counts. SSPDs integrated with a cryogenic HEMT read-out circuit can provide some level of both the energy and number resolution of an unknown incident photon flux, making them uniquely suitable for various photon sensing applications.

Electromagnetic properties of the superconductors predestine them to serve as materials for the efficient and light magnetic shields. Very high attenuation factors are possible to be obtained. Superconducting elements of different geometry can be used. However, shielding effect is limited by the critical current of a superconductor. This work describes the model of an arbitrarily shaped thin superconducting plates made of BSCCO, with the focus on circular and rectangular samples. The plates are subjected to transverse magnetic fields of different strength and shape. Changes of critical current density are considered. The distribution of the shielded magnetic field and shielding current is presented. Results show that the magnetic field attenuation occurs and depend on the shape and material of a plate. It was also observed that coarse meshes can be used to obtain reliable results concerning magnetic field distribution, thus saving computational time.

The REBa₂Cu₃O_7-x (REBCO/YBCO) based high-temperature superconductors are promising materials for high magnetic field and energy applications due to their effective flux pinning abilities. The superconducting properties of these materials strongly depend on the microstructure, which could be engineered by the fabrication methods, and incorporating various dopants. Infiltration growth (IG) process is currently evolving and superior to the standard melt growth (MG) technique addressing various inherent and unwanted problems. However, the IG technique is complex as compared to conventional MG technique, and for high reproducibility, many parameters need to be optimized for every system. In this paper, we present the engineering of the final microstructure with various nanometric metal oxides to the bulk YBCO/REBCO materials aiming to improve the field dependence of the superconducting properties. The effect of introducing various RE elements in IG processed YBCO/GdBCO bulk superconductors, and the evolution of microstructures supported by thorough elemental analysis will be discussed. Emphasis will be given to the problems involved in the growth of mixed REBCO products in the IG process and to the microstructural properties at various stages of processing the bulk samples.

The performance improvement of disk- shaped bulk MgB₂ superconductor by means of a nanoscopic diamond powder have been investigated in our previous studies, using a single-step solid-state reaction process. To further improve the critical current density (J_c), we added Ag with varied compositions of 3.5, 4.0, 4.5 wt.% in the optimized composition of 0.8 wt.% of nanodiamond added MgB₂ sample and synthesized in pure Ar atmosphere. All samples were sintered at an optimized temperature of 775°C for 3 hours. X-ray diffraction patterns conformed to the main phases of MgB₂ samples with additional phases observed in the Ag-added samples. Microstructures were observed with high magnification in field emission scanning electron microscope (FE-SEM) and indicated AgMg nanoparticles are embedded in the MgB₂- nanodiamond matrix, which was correlated with XRD studies. Among, the 4.0 wt.% Ag doped sample exhibited the highest J_c of 389 kA/cm² at 20 K. The present result showed that Ag addition to MgB₂-nanodiamond is an effective pinning medium for bulk MgB₂ and might thus be attractive for a further performance improvement of the bulk MgB₂ material.

The REBa₂Cu₃O_7-δ (where RE - rare earth element, 0 < δ < 1) superconductor (also called "RE-BCO” or "1:2:3”) is produced by calcination of a mixture of copper (II) oxide (CuO), barium carbonate (BaCO₃) and yttrium (III) oxide (Y₂O₃) powders. The aim of the research was to study similarities and differences in physico-chemical properties for ceramic samples of high-temperature superconductors slightly differing in the average crystal ionic radiuses of RE³⁺. For this purpose a reference sample YBa₂Cu₃O_7-δ was prepared, for which the average crystal radius of the ion Y³⁺ is 104.0 pm and two samples with approximate to that average crystal ionic radiuses RE³⁺: HoBa₂Cu₃O_7-δ and Er_0.5Dy0.5Ba₂Cu₃O_7-δ, where the average crystal ionic radiuses are 104.1 pm. The physicochemical properties of samples were studied and the microstructure of samples was characterized. The structural and phase homogeneity analysis was carried out using Raman spectroscopy, Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) technique. Raman measurements and XRD measurements revealed the presence of a superconducting phase in all studied samples. The granulation analysis of the mixture substrates powders after first and second calcination was performed with use of the Low-Angle Laser Light Scattering (LALLS) method. The magnetic properties of the obtained samples were measured with a SQUID magnetometer. The temperature dependences of AC susceptibility were used to determine the temperature of transition to the superconducting state and the hysteretic energy dissipation due to losses at inter-grain region.

The thallium based superconductor Tl₂Ba₂Ca₂Cu₃O_y was prepared using a three-step calcination and sintering method. Afterwards, the pellet was two times oxygenated in 740^oC for 20 h. Taking the absorption part of the a.c. susceptibility measurements the critical current density turned out to be from 20 A/cm² before oxygenations, through 380 A/cm² after the first oxygenation to 1120 A/cm² after the second oxygenation. The critical temperature from the dispersion part of the a.c. susceptibility measurements was determined to be 99.7 K, 112.8 K, and 116.2 K respectively.

The samples of well-oxidized REBa₂Cu₃O_7-δ with different trivalent RE (rare earth) ions, were studied with use of EPR method at the temperature above of liquid nitrogen (77 K). The measured samples were obtained by the solid phase synthesis method. The aim of these measurements was to find and describe the relation between critical temperature, critical magnetic field, and the shape of the resonance signal. It was expected that samples possess the HTSC transition at about 90 K. For most samples, both a nonresonant absorption and emerging of HTSC state were visible in the EPR experiment. The evolution of these signals allowed determining the critical temperature, as well as the evolution of the critical magnetic fields as a function of temperature. Additionally, EPR signal of Cu (II) ions was detected and explained by insufficiently oxidized samples or the existence of contaminated phases.

Properties of two types of position-dependent electrostatic qubits: eigenenergy-based and Wannier-based, are treated with Schrodinger formalism. Their operating principles are given. The corresponding quantum universal gates for selected qubit types are described and their possible implementation is suggested. The modeling methodology of setting and reading semiconductor qubit is suggested. The interface between superconducting and semiconductor quantum computer is proposed and its implementation and operating principles are described.

The paper presents the results of measurements of a solid solution (1-x)K_0.5Bi_0.5TiO₃-xSrTiO₃ (KBT-ST) ceramics with (for) x=0.001 for two different sintering temperatures (cases of times sintering): (1) at temperature 1303K for 6 hours (KBT-ST 1) and (2) at temperature 1313K for 6 hours (KBT-ST 2). In both cases, the X-ray diffraction study demonstrated the perovskite structure with a small amount of the second phase. Microstructure research with SEM allowed to observe well-developed grains for both obtained samples. Optical studies using Raman spectroscopy showed that the obtained samples have a local structure consistent with the base material K_0.5Bi_0.5TiO₃ (KBT). Dielectric study of these solid solution ceramics were taken in the temperature range from 293K to 873K and in the frequency range from 10 kHz to 1 MHz. These measurements allowed to observe in both cases a broad maximum similar to that for the base KBT ceramics. It has been observed that if the sintering temperature increase up to 1313K it causes a double increase in the dielectric constant and (it doubles the dielectric constant value and causes) the appearance of additional anomaly on the ε(T) curve at temperature approximately T_d=521K.