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In the framework of the ELI-NP GBS program a full pre-injector was delivered in the Magurele premises (Romania). This article develops the scenario of the re-use of the pre injector components to integrate a radioactive beams facility in the ELI site, considering the possible interest of the local nuclear physics community.

In this work, we present the RF design of a table-top Ka-Band mode launcher operating at 35.98 GHz. The structure consists of a symmetrical 4-port WR28 rectangular-TE10-to-circular-TM01 mode converter that is used to couple a peak output RF power of 5 MW (pulse length up to 50 ns and repetition rate up to 100 Hz) in Ka-Band linear accelerator able to achieve very high accelerating gradients (up to 200 MV/m). Numerical simulations have been carried out with the 3D full-wave commercial simulator Ansys HFSS in order to obtain a preliminary tuning of the accelerating field flatness at the operating frequency f0=35.98 GHz. The main RF parameters, such as reflection coefficient, transmission losses, and conversion efficiency are given together with a verification of the field azimuthal symmetry which avoids dipole and quadrupole deflecting modes. To simplify future manufacturing, reduce fabrication costs, and also reduce the probability of RF breakdown, the proposed new geometry has "open" configuration. This geometry eliminates the flow of RF currents through critical joints and allows this device to be milled from metal blocks., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

Personnel safety system for particle accelerator facility involves different devices to monitor gates, shielding doors, dosimetry stations, search and emergency buttons. In order to achieve the proper reliability, these systems are developed compliant with functional safety standards involving stable technologies like relays and, recently, PLC. This work will report benchmark of a new FPGA-based system, developed at INFN-LNF, from the design to the validation phase of the prototype currently operating inside the linac bunker of Dafne. In order to achieve the compliance with functional safety standard (IEC-61508), NCRP report 88 on "Radiation Alarms and Access Control Systems" and ANSI report 43 on "Radiation Safety for the Design and Operation of Particle Accelerator", this novel instrument has been designed capable of: devices monitoring in real-time, dual modular redundancy, fail-safe, fool-proof and multi-node architecture on optical link. The aim of this project is to illustrate the feasibility of FPGA technology in the field of personnel safety and develop a standard solution for other fields like the machine protection., Proceedings of the 17th International Conference on Accelerator and Large Experimental Physics Control Systems, ICALEPCS2019, New York, NY, USA

The HEP scientific community is, at present, exploring different scenario concerning the post LHC era. In fact, after the Higgs boson discovery, the future facility will require not only to improve the LHC and HL-LHC physics programs but also to continue the search for phenomena beyond the Standard Model into an extended energy domain. In this framework ideas and proposals, together with the results obtained in accelerator research, introduce a scenario where the feasibility of a multi-TeV muon collider should be explored. This article will describe the advantages provided by the muon collider scheme. The proposed schemes will be shortly illustrated. The very important recent results obtained in proof-of-principle experiments will be subsequently described. Finally, for each scheme, the future possible directions for proof-of-principle experiments to demonstrate the muon collider feasibility will be presented., Proceedings of the 11th International Particle Accelerator Conference, IPAC2020, Caen, France

In the framework of the Compact Light XLS project a compact third harmonic RF accelerating structure at 35.982 GHz with respect to the main Linac frequency 11.994 GHz, working with an ultra-high gradient accelerating field in order to linearize the longitudinal space phase is adopted. To this end an innovative high power Ka band klystron operating at about 35.982 GHz has to be designed for feeding the linearizer structure. In addition, we also are planning to design a Ka band klystron operating on the third harmonic of TM01 mode. The generation of a high density electron beam by using the Pierce type electron gun is also requested. The electron gun goal is to produce a converging high beam current that matches to a focusing magnetic field in such way to obtain about 100 MW beam power. This paper proposes a possible design of a electron gun to be used in millimetric waves vacuum tubes. We here report the preliminary studies of the electron gun and the related beam dynamic. Estimations have been obtained by using the numerical code CST and analytical approaches.

The Low Emittance Muon Accelerator~(LEMMA) aims at producing small emittance muons from positron annihilation with electrons in a target. Given the low cross section of the production process, a large number of positrons on the target are required, exposing it to high power deposition and the beam to large degradation because of multiple scattering and bremstrahlung. A multi-target IP, and multi-IP line has been studied to reduce the power deposition per target and the degradation of the positron beam while preserving the number of muon pairs produced. The lattice copes with the focusing and transport of three beams at two different energies, the positron beam at 45 GeV, and µ⁺+ and µ⁻ beams at 22.5~GeV. Studies on the beam dynamics, number of targets, material and thickness of the targets are reported in this paper., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

The design of a future multi-TeV muon collider needs new ideas to overcome the technological challenges related to muon production, cooling, accumulation and acceleration. The Low Emittance Muon Accelerator (LEMMA) concept *,** presents in this paper an upgraded layout of a positron driven muon source. The positron beam, stored in a ring with high energy acceptance and low emittance, is extracted and driven in a push-pull configuration to a multi-target system, to produce muon pairs at threshold on the target’s electrons. This solution alleviates the issues related to the power deposited and the integrated Peak Energy Density Deposition on the targets. Muons produced in the multi-target system will then be accumulated in many parallel rings before acceleration and injection in the collider. A special multi-target line lattice has been designed to cope with the focusing of both the positron and muon beams. Studies on the number, material and thickness of the targets have been carried out. A general layout of the overall scheme and a description is presented, as well as plans for future R, Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

Technological advancements are strongly required to fulfil demands for new accelerators devices from the compact or portable devices for radiotherapy to mo-bile cargo inspections and security, biology, energy and environmental applications, and ultimately for the next generation of colliders. In the frame of the collab-oration with INFN-LNF, SLAC (USA) we are working closely on design studies, fabrication and high-power operation of Ka-band accelerating structures. In par-ticular, new manufacturing techniques for hard-copper structures are being investigated in order to determine the maximum sustainable gradients above 150 MV/m and extremely low probability of RF breakdown. In this paper, the preliminary RF and mechanical design as well as beam dynamics estimations for a Ka-Band accelerating structure at 35 GHz are presented together with discussions on practical accelerating gradients and maximum average beam current throughput., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

Optical Transition Radiation (OTR) screen represents the most appropriate instrument to measure and verify the characteristics of a beam spot size produced by a particle accelerator. In order to measure such beam properties, OTR screens have to sustain thermal and mechanical stresses due to the energy that several bunches deposit. Owing to these requirements, it is essential to identify the more suitable material to optimize the OTR dimensions and to get reliable measures from the diagnostic system. In this paper, we describe a numerical procedure to choose the most performing material taking into account the physical requirements of a multi-bunch high brightness. The procedure is based on a dedicated ANSYS script able to evaluate the fatigue life time of the material considering a high number of thermal cycles generated by several bunches. The main characteristic of this script is the capability to simulate the real thermal and mechanical effect on the target that the hitting particle beam produces. The numerical procedure has been applied to compare the performance of three relevant materials-Aluminium, Silicon and Graphite simulating a beam hitting with well-known parameters., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

Optical Transition Radiation (OTR) screens are widely used for beam profile measurements. The radiation is emitted when a charged particle beam crosses the boundary between two media with different optical properties. The main advantages of OTR are the instantaneous emission process allowing fast single shot measurements (i.e. bunch by bunch measurements in a multi bunch machine), and the good linearity with the beam charge (if coherent effects can be neglected). Furthermore, OTR angular distribution strongly depends on beam energy. Since OTR screens are typically placed in several positions along the Linac to monitor beam envelope, one may perform a distributed energy measurement along the machine: this will be useful, for instance, during the commissioning phase of a machine. This paper deals with the studies of an algorithm to optimize the generation and the transport of the transition radiation through an optic system using the simulation tool Zemax. The algorithm, in combination with a particle tracking code (i.e. Elegant), will allow to simulate the radiation generated by a beam and, so, to take into account beam divergence and energy spread or chromatic effects in the optic system., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

Operation of modern particle accelerators require high qualitity beams and conseguently sensitive diagnostic system in order to monitories and characterize the beam during the acceleration and transport. A turn-key high level software BOLINA (Beam Orbit for Linear Accelerators) has been developed to fully characterise the 6D beam phase space in order to help operator during commissioning with an easily scalable suite for any high brightness LINAC. In this work will be presented the diagnostic toolkit is presented as designed for the ELI-NP Gamma Beam System (GBS) a radiation source based on the Compton back scattering effect able to provide tunable gamma rays in the 0.2-20 MeV range with narrow bandwidth (0.3% and a high spectral density (10⁴ photons/sec/eV) by the Compton backscattering effect. BOLINA suite is design to be machine independent, thanks to the file exchanges with the EPICS based control system. Simulation of raw data of the ELI-NP-GBS accelerator has been used to test the capabilities of the diagnostic toolkit., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

Personnel safety system for particle accelerator facility involves different devices to monitor gates, shielding doors, dosimetry stations, search and emergency buttons. In order to achieve the proper reliability, fail-safe and fail-proof capabilities, these systems are developed compliant with safety standards (like the IEC-61508 on ’Functional Safety’, ANSI N43.1 ’Radiation Safety for the design and operation of Particle Accelerator’ and NCRP report 88) involving stable technologies like electro-mechnaical relays and, recently, PLC. As part of the Singularity project at Frascati National Laboratories of INFN, this work will report benchmark of a new FPGA-based system from the design to the validation phase of the prototype currently operating as personnel safety system at the Beam Test Facility (BTF) of Dafne facility. This novel instrument is capable of: devices monitoring in real-time at 1 kHz, dual modular redundancy, fail-safe and fail-proof, multi-node distributed solution on optical link, radiation damage resistance and compliant with IEC-61508, ANSI N43.1 and NCRP report 88. The aim of this FPGA-based system is to illustrate the feasibility of FPGA technology in the field of personnel safety for particle accelerator in order to take advantage of a fully digital system integrated with facility control system, evaluate the related reliability and availability and realize a standard, scalable and flexible hardware solution also for other fields with similar requirements like machine protection systems., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

The Extreme Light Infrastructure - Nuclear Physics Gamma Beam Source (ELI-NP GBS) will be installed and commissioned starting within the next year in Magurele, Romania. It will generate gamma beam through Compton back-scattering of a recirculated laser and a multi-bunch electron beam, produced by a 720 MeV LINAC. In order to obtain bunch by bunch position measurements, four cavity beam position monitors (cBPM) near the two interaction points are foreseen. Extensive tests on the cBPM read-out electronics, recently developed by Instrumentation Technologies and acquired for ELI-NP GBS, were performed in laboratory at INFN-LNF and at FLASH in DESY, during the user operation. In the latter case, three cBPMs installed along the LINAC, with similar features as the ones of ELI-NP GBS, were used as measuring devices and signal sources for the read-out electronics under test. We present here the measurements collected and the related analysis, with a particular focus on the beam position measurement resolution., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

A high brightness electron Linac is being built in the Compton Gamma Source at the ELI Nuclear Physics facility in Romania. To achieve the design luminosity, a train of 32 bunches, 16 ns spaced, with a nominal charge of 250 pC will collide with the laser beam in the interaction point. Electron beam spot size is measured with optical transition radiation (OTR) profile monitors. Furthermore, OTR angular distribution strongly depends on beam energy. Since OTR screens are typically placed in several positions along the Linac to monitor beam envelope, one may perform a distributed energy measurement along the machine. This will be useful, for instance, during the commissioning phase of the GBS in order to verify the correct functionality of the C-Band accelerating structures, due to the fact that there are OTR screens after each accelerating module. This paper deals with the studies of different optic configurations to achieve the field of view, resolution and accuracy in order to measure the energy of the beam. Several configurations of the optical detection line will be studied with simulation tools (e.g. Zemax)., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

The Extreme Light Infrastructure ' Nuclear Physics Gamma Beam Source (ELI-NP GBS) facility will provide an high intensity laser and a very intense gamma beam for verious experiments. The gamma beam is generated through incoherent Compton back-scattering of a laser light off a high brightness electron beam provided by a 720MeV warm LINAC. The electrons are organized in compact trains with up to 32 bunches, each separated by 16ns. To optimize the laser-electron interaction and therefore the generation of the gamma rays, one big challenge is to precisely monitor the trajectory of each electron bunch. To match this requirement, at the interaction point two S-band cavity beam position monitors will be used, and the related readout system should perform bunch-by-bunch position measurements with sub-μm resolution. Using 500MS/s ADC converters and dedicated data processing, the readout system proposes an alternative measurement concept. In this paper the architecture of the system, the implemented signal processing and the results of the first laboratory tests will be presented., Proceedings of the 6th Int. Beam Instrumentation Conf., IBIC2017, Grand Rapids, MI, USA

PSPA (Platform for Simulation of Particle Accelerators) is an original web-based interactive simulation platform for designing and modelling particle accelerators created at Laboratoire de l'Accélérateur Linéaire, Orsay. It aims at eventually containing all the tools to make a start-to-end simulation of an accelerator, and make it possible to run interactively several open source simulations codes available worldwide. At the moment, the focus is on electron/positron accelerators. PSPA will optimize the work of accelerator designers by factoring once and for all the tedious, time-consuming and error prone process of translating data formats between the various codes involved in the modelling of a machine, controlling the repeated execution of these models by easily varying some parameter and managing the associated data. Moreover, as a truly innovative feature, it will provide a convenient means for testing different physical models of a given part of a machine. The status of the project is described in this paper, and examples of its application to the ThomX compact Compton backscattering source at LAL are presented., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

The correlations between vertical and longitudinal planes at the Radio Frequency Deflector (RFD) entrance can be introduced by misalignments of accelerating sections or quadrupoles upstream of the RFD. These correlations are undesired effects and they can affect the RFD based bunch length measurements in high-brightness electron LINAC. In this paper, an RFD based measurement technique for vertical and longitudinal planes is proposed. The basic idea is to obtain information about the correlations between vertical and longitudinal planes from vertical spot size measurements varying the RFD phase, because they add contributions on this quantity. In particular, considering a small RFD phase range centred in 0 or π rad, the correlations between the particle longitudinal positions and the vertical plane are constant with the deflecting voltage phase, on the contrary, the correlations between the particle energies and the vertical plane vary linearly with the deflecting voltage phase. The simulations are carried out by means of ELEctron Generation ANd Tracking (ELEGANT) code in the case of the Gamma Beam System (GBS) at the Extreme Light Infrastructure-Nuclear Physics (ELI-NP)., Proceedings of the 6th Int. Beam Instrumentation Conf., IBIC2017, Grand Rapids, MI, USA

A high brightness electron Linac is being built in the Compton Gamma Source at the ELI Nuclear Physics facility in Romania. To achieve the design luminosity, a train of 32, 16 ns spaced, bunches with a nominal charge of 250 pC will collide with the laser beam in the interaction point. Electron beam spot size is measured with an OTR (optical transition radiation) profile monitors. In order to measure the beam properties, the optical radiation detecting system must have the necessary accuracy and resolution. This paper deals with the studies of different optic configurations to achieve the magnification, resolution and accuracy desired considering design and technological constraints; we will compare several configurations of the optical detection line to justify the one chosen for the implementation in the Linac., Proceedings of the 5th Int. Beam Instrumentation Conf., IBIC2016, Barcelona, Spain

The advanced source of Gamma-ray photons will be soon built near Bucharest (Romania) by an European consortium (EurogammaS) led by INFN, as part of the ELI-NP (Extreme Light Infrastructure-Nuclear Physics). It will generate photons by Compton back-scattering in the collision between a multi-bunch electron beam, at a maximum energy of 720 MeV, and a high intensity recirculated laser pulse. An S-Band photo-injector and the following C-band Linac, which are under construction, will operate at 100Hz repetition rate with macro pulses of 32 electron bunches, separated by 16ns and with 250pC nominal charge. Stripline and cavity BPMs will be installed along the linac, in order to measure both the position and charge of the electron beam. Stripline BPM response can be considered linear within a limited area around the BPM origin. In order to use the full BPM acceptance area, without accuracy losses due to non-linearities, we plan to use correction algorithms, developed on the basis of simulations and measurements of BPMs response. In particular, suitable high-order surface polynomials will be used., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

RF Deflector (RFD) based measurements are widely used in high–brightness electron LINAC around the world in order to measure the ultra–short electron bunch length. The RFD provides a vertical kick to the particles of the electron bunch according to their longitudinal positions. In this paper, a measurement technique for the bunch length and other bunch proprieties, based on the usage of an RFD, is proposed. The basic idea is to obtain information about the bunch length, energy chirp, and energy spread from vertical spot size measurements varying the RFD phase, because they add contributions on this quantity. The case study is the Gamma Beam System (GBS), the Compton Source being built in the Extreme Light Infrastructure–Nuclear Physics (ELI–NP) facility. The ELEctron Generation ANd Tracking (ELEGANT) code is used for tracking the particles from RFD to the measurement screen., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

High gradient RF photoguns have been a key development to enable several applications of high quality electron beams. They allow the generation of beams with very high peak current and low transverse emittance, satisfying the tight demands for free-electron lasers, energy recovery Linacs, Compton/Thomson Sources and high-energy linear colliders. A new fabrication technique for this type of structures has been recently developed and implemented at the Laboratories of the National Institute of Nuclear physics in Frascati (LNF-INFN, Italy). It is based on the use of special RF-vacuum gaskets that allow avoiding brazing in the realization process. The S-band gun of the Compton-based ELI-NP gamma beam system (GBS) has been fabricated with this new technique. It operates at 100 Hz with 120 MV/m cathode peak field and long RF pulses to allow the 32 bunch generation foreseen for the GBS. High gradient tests have been performed at full power full repetition rate and have shown the extremely good performances of the structure in term of breakdown rates. In the paper we report and discuss all experimental results with details of the electromagnetic design and mechanical realization processes., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

A high brightness electron Linac is being built in the Compton Gamma Source at the ELI Nuclear Physics facility in Romania. To achieve the design luminosity, a train of 32 bunches, 16 ns spaced, with a nominal charge of 250 pC will collide with the laser beam in the interaction point. Electron beam spot size is measured with optical transition radiation (OTR) profile monitors. In order to measure the beam properties, the optical radiation detecting system must have the necessary accuracy and resolution. This paper deals with the studies of different optic configurations to achieve the magnification, resolution and accuracy in order to measure very small beam (below 30 um) or to study the angular distribution of the OTR and therefore the energy of the beam. Several configurations of the optical detection line will be studied both with simulation tools (e.g. Zemax) and experimentally. The paper will deal also with the sensibility of optic system (in terms of depth of field, magnification and resolution) to systematic errors., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

A high brightness electron Linac is being built in the Compton Gamma Source at the ELI Nuclear Physics facility in Romania. To achieve the design luminosity, a train of 32 bunches, 16 ns spaced, with a nominal charge of 250 pC will collide with the laser beam in two interaction points. Electron beam spot size is measured with optical transition radiation (OTR) profile monitors. In order to measure the beam properties, the OTR screens must sustain the thermal and mechanical stress due to the energy deposited by the bunches. This paper is an ANSYS study of the issues due to the high energy transferred to the OTR screens. Thermal multicycle analysis will be shown; each analysis will be followed by a structural analysis in order to investigate the performance of the material. The multiphysics analysis will be extended to the mechanical contact areas with the target frame in order to evaluate the order of magnitude of the phenomena in those regions., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

The new Gamma Beam System (GBS), within the ELI-NP project, under installation in Magurele (RO) by INFN, as part of EuroGammas consortium, can provide gamma rays that open new possibilities for nuclear photonics and nuclear physics. ELI-GBS gamma rays are produced by Compton back-scattering to get monochromaticity (0,1% bandwidth), high flux (10¹³ photon/s the highest in the world), tunable directions and energies up to 19 MeV. Such gamma beam is obtained when a high-intensity laser collides a high-brightness electron beam with energies up to 720 MeV with a repetition rate of 100 Hz in multi-bunch mode with trains of 32 bunches. An advanced Machine Protection System was developed in order to ensure proper operation for this challenging facility. Such system operate on different layers of the control system to be interfaced with all sub-systems of the control system. It's equipped with different beam loss monitors based on Cherenkov optical fiber, hall probes, fast current transformer together with BPM and an embedded system based on FPGA with distributed I/O over EtherCAT to monitor vacuum and RF systems which requires fast response to be interlocked within the next RF pulse., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

New generation of Compton sources are developing in different countries to take advantage of the photon energy amplification given by the Compton backscattering effect. In this framework the Eurogammas international collaboration is producing a very high brilliance gamma source for the Nuclear Pillar of the Exterme Light Infrastructure program (ELI). At present there is a lot of effort in the mass production of all the components and in the developments and tests of the different high technology devices that will operate in the gammas beam source, like the optical recirculator and the high gradient - high average current warm C band accelerating sections. In this paper we will provide a general overview of the GBS status and of the perspectives for the future integration phase., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

A high brightness electron LINAC is being built in the Compton Gamma Source at the ELI Nuclear Physics facility in Romania. To achieve the design luminosity, a train of 32 bunches, 16 ns spaced, with a nominal charge of 250 pC will collide with the laser beam in the interaction point at two electron beam energies, namely 280 MeV and 720 MeV. Electron beam spot size is measured with optical transition radiation (OTR) profile monitors. The paper deals with the possibility of using the OTR monitors to measure also beam energy along the machine; such measurements may help monitoring the accelerating sections performances, especially when the whole bunch train is being accelerated. We discuss the measurement principle, the expected accuracy and the main characteristic of the optical line to retrieve the angular distribution of the emitted radiation., Proceedings of the 6th Int. Beam Instrumentation Conf., IBIC2017, Grand Rapids, MI, USA