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Since end of the year 2020 the energy recovery linac (ERL) project bERLinPro of Helmholtz-Zentrum Berlin has been officially completed. But what is the status of this facility, the next scientific goals in the framework of accelerator physics at HZB, what are the perspectives? To reflect the continuation of this endeavor and the broadening of applications of this machine from high current SRF based energy recovery concept up to an ultrafast electron diffraction (UED) facility producing shortest electron pulses, the facility is now named Sealab, Superconducting RF Electron Accelerator Laboratory. In this contribution, an overview of lessons learned so far, the status of the machine, the coming set up and commissioning steps with an outlook to midterm and future applications will be given. In summary, Sealab will expand, including the ERL application, and become a general accelerator physics and technology test machine to employ UED as a first study case and will also be an ideal testbed to investigate new control schemes based on digital twins or machine learning methods., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

Since 2020 a detailed discussion about a BESSY~II successor is ongoing at HZB and its user community in order to define the science and layout of the new facility. Still free locations close to BESSY~II have triggered a discussion about a greenfield project, but in-house upgrade solutions have also been investigated. As an additional boundary condition, BESSY~III has to meet the requirement of the Physikalische Technische Bundesanstalt (PTB) for radiation sources for metrology applications and bending magnet sources for tender X-rays. A Conceptional Design Report is in preparation. Here, we give a status report including a first parameter space, technical specifications and a first candidate for the linear lattice., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

Following the European Strategy process in 2019, five Roadmap Panels were set up to prepare the technologies needed for future accelerators and colliders: high-field magnets, SRF, muon colliders, plasma wakefield accelerators and Energy Recovery Linacs (ERLs). The ERL Roadmap Panel, consisting of ERL experts from around the world, first developed an overview of current and future ERLs. From this it was possible to carry out a gap analysis to see what R would be needed, from which the Roadmap could be developed. The European ERL Roadmap focused on three main aspects: 1) the continuation and development of facility programs for which no additional funds are needed, S-DALINAC in Darmstadt and MESA in Mainz; 2) technology development for room-temperature HOM damping and twin-axis SRF cavities; 3) the timely upgrade of bERLinPro for 100 mA current and the construction of PERLE at Orsay as a dedicated 10 MW power multi-turn facility. The roadmap entails a vision of future energy frontier electron-positron and electron-hadron collider and describes a high quality ERL program for 4.4 K SRF technology at high Q₀. The presentation will address the ERL Roadmap process and result in detail., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

Lattice development efforts for the 2.5GeV, low emittance successor of BESSY II, are ongoing at HZB for 2 years. The basic choice of a multi-bend achromat lattice is indispensable due to the emittance goal of 100pm, required to generate diffraction limited radiation up to 1keV. Hard boundary conditions for the design are a reasonably short circumference of ~350m due to the accessible construction properties in vicinity to Bessy II and 16 super-periods to not step behind the number of existing experimental stations. Additionally, the Pysikalisch Technische Bundesanstalt, the long-term partner of HZB, requests homogeneous dipoles as a calculable and traceable source of radiation for metrology applications. The configuration of the two building blocks of MBA lattices - unit cell and dispersion suppression cell - has been thoroughly studied from basic principles. It was found that gradient free bending dipoles are the better choice for the BESSY III lattice, opposite to the concepts of comparable projects. This work summarizes and explains the findings of our investigations., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

Since the pioneering work of MAX IV *, multi-bend achromat (MBA) lattices have become the standard in lattice design for 4th generation lights sources as well as upgrades of 3rd generation storage rings. The distribution of the bending angle to many weak dipoles enables to reach unprecedented low emittance and highest brightness. In their most basic form, MBA-lattices consist of a repetitive unit cell and two identical matching cells on either end of the achromatic arc. The simplicity of both cells allows for a unique determination of the linear lattice parameters in dependence on boundary conditions defined by the design goals. Those might be the emittance, momentum compaction factor, chromaticity, as well as phase advances with respect to achieving higher-order achromatic structures. A scan of optional lattice prototypes is quickly obtained. We demonstrate this concept and apply it in the design of the first candidates for the lattice of BESSY III, a green-field 4th generation storage ring being currently planned at HZB, Berlin, Germany., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

The design philosophy for a robust prototype lattice design for BESSY III, i.e., that is insensitive to small parameter changes, e.g. engineering tolerances - based on a higher-order-achromat, a la: SLS, NSLS-II, MAX IV, and SLS 2 - is outlined presented. As usual, a well optimized design requires a clear understanding of the end-user requirements and close collaboration between the linear optics designer and nonlinear dynamics specialist for a systems approach., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

HZB operates and develops two synchrotron radiation sources at Berlin Adlershof. The larger one, BESSY II with an energy of 1.7 GeV and 240 m circumference is optimized for soft-X rays and in operation since 1999. The smaller one is the MLS (Metrology Light Source), owned by the Physikalische Technische Bundesanstalt (PTB) - Germany’s National Metrology Institute. It is designed to fulfill the special metrology needs of the PTB with an energy of 0.6 GeV and 48 m circumference, covering the spectral range from THz and IR to EUV/VUV. In 2020 a discussion process has been started to define the requirements for successors of BESSY II and MLS and to study the possibilities integrate them into a new photon science facility in Berlin Adlershof. Here, we give a status report and present a first envisaged parameter space to both machines (see also MOPAB262, MOPAB220, MOPAB048, MOPAB242)., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

BERLinPro is an Energy Recovery Linac (ERL) project currently being set up at HZB, Berlin. During the turn of the project, many adaptations of the optics to changing hardware realities were necessary. To name only one, commissioning of the recirculator will now be realized with the superconducting linac module fabricated for the Mainz ERL project MESA, as the BERLinPro linac is delayed. The Mainz linac will supply roughly 60% of the energy planned for the BERLinPro linac module and will be limited by higher order modes in the cavities to few mA of current. While the adapted optics shows similar parameters as the original 50MeV optics, studies of longitudinal space charge and coherent synchrotron radiation show that the energy leads to large emittance blow up due toμbunching. Furthermore, preparations for commissioning with gun fields much lower than the original 30MV/m in the 1.4 cell SRF gun are introduced and according optics are presented., Proceedings of the 63th ICFA Advanced Beam Dynamics Workshop on Energy Recovery Linacs, ERL2019, Berlin, Germany

The Helmholtz-Zentrum Berlin is constructing the Energy Recovery Linac Prototype BERLinPro, a SRF based demonstration facility for the science and technology of ERLs for future high power, high brilliance electron beam applications. BERLinPro was designed to accelerate a high current (100 mA, 50 MeV), high brilliance (norm. emittance below 1 mm mrad) cw electron beam. Given the recent prioritization of the BESSY II upgrade to the BESSY VSR variable pulse length storage ring, HZB is forced to reduce the project goals of BERLinPro. As a result, the project had to be rescoped with the goal to maximize its scientific impact within the present boundary conditions. We report on the last year’s progress of the building, the warm and cold infrastructure and on the time line, goals nd opportunities for the remaining project run time., Proceedings of the 63th ICFA Advanced Beam Dynamics Workshop on Energy Recovery Linacs, ERL2019, Berlin, Germany

BERLinPro is an Energy Recovery Linac (ERL) project currently being set up at HZB, Berlin. Commissioning is planned for early 2020. HZB triggered and supported the development of release 2.0 of the particle tracking code OPAL, that is now also applicable to ERLs. OPAL is set up as an open source, highly parallel tracking code for large accelerator systems and many particles. Thus, it is idially suited to serve attempts of applying machine learning approaches to beam dynamics, as demonstrated in [1]. OPAL is used to calculate hundreds of randomized machines close to the commissioning optics of BERLinPro. This data base will be used to train a neural network, to establish a surrogate model of BERLinPro, much faster than any physical model including particle tracking. First steps, like the setup of the sampler and a sensitivity analysis of the resulting data are presented. The ultimate goal of this work is to use machine learning techniques during the commissioning of BERLinPro. Future steps are outlined. [1] A. Edelen, A. Adelmann, N. Neveu, Y. Huber, M. Frey, ’Machine Learning to enable orders of magnitude speedup in multi-objective optimization of particle accelerator systems’, Proceedings of the 63th ICFA Advanced Beam Dynamics Workshop on Energy Recovery Linacs, ERL2019, Berlin, Germany

BERLinPro is an Energy Recovery Linac Project, currently being set up at the Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany. BERLinPro is a small demonstrator for ERL technology and applications. Due to the low energy of 50, resp. 32MeV, space charge plays a dominant role in the beam dynamics. Micro-bunching, due to unavoidable shot noise from the cathode in combination with space charge, is seen in the merger as well as in the recirculator. Coherent synchrotron radiation (CSR) can amplify this bunching, as well as micro-bunching can enhance CSR losses. With the release of OPAL 2.0** in May 2018, for the first time, an open source, highly parallel tracking code is available, that is capable of numerically calculating both effects, space charge and CSR, simultaneously. The calculations are compared to earlier results*, that used analytical formulas on tracked, space charge dominated bunches., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

BERLinPro is an Energy Recovery Linac (ERL) project, currently being set up at the Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany. BERLinPro is designed as - and for - experiments in accelerator physics and as a test bed for novel ERL components. MESA is an ERL project under construction at the Johannes Gutenberg-Universität, Mainz, Germany. MESA is designed as a user facility to perform experiments in dark matter physics and precision measurements of natural constants. Despite the diverse goals, the main linac, providing the larger part of the particles energy, is fairly compatible. It is planned to test and run the MESA linac module in BERLinPro, prior to its usage in MESA. The goals and benefits of this unique cooperation for both projects are outlined in this paper. The necessary adaptions in BERLinPro, including hardware aspects, the new optics, and the scope of performance are described., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

A collaboration between Cornell University and Brookhaven National Laboratory has designed and is constructing CBETA, the Cornell-BNL ERL Test Accelerator on the Cornell campus. The ERL technology that has been prototyped at Cornell for many years is being used for this new accelerator, including a DC electron source and an SRF injector Linac with world-record current and normalized brightness in a bunch train, a high-current linac cryomodule optimized for ERLs, a high-power beam stop, and several diagnostics tools for high-current and high-brightness beams. BNL has designed multi-turn ERLs for several purpose, dominantly for the electron beam of eRHIC, its Electron Ion Collider (EIC) project and for the associated fast electron cooling system. Also in JLEIC, the EIC designed at JLAB, an ERL is envisioned to be used for electron cooling. The number of transport lines in an ERL is minimized by using return arcs that are comprised of a Fixed Field Alternating-gradient (FFA) design. This technique will be tested in CBETA, which has a single return for the 4-beam energies with strongly-focusing permanent magnets of Halbach type. The high-brightness beam with 150~MeV and up to 40~mA will have applications beyond accelerator research, in industry, in nuclear physics, and in X-ray science. Low current electron beam has already been sent through the most relevant parts of CBETA, from the DC gun through both cryomodules, through one of the 8 similar separator lines, and through one of the 27 similar FFA structures. Further construction is envisioned to lead to a commissioning start for the full system early in 2019., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

The Helmholtz-Zentrum Berlin is constructing the Energy Recovery Linac Prototype BERLinPro, a demonstration facility for the science and technology of ERLs for future light source applications. BERLinPro is designed to accelerate a high current (100 mA, 50 MeV), high brilliance (norm. emittance below 1 mm mrad) cw electron beam. We report on the last year's progress, including the comissioning of the gun module as the first SRF component to be installed in BERLinPro., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

The Berlin Energy Recovery Linac project has taken shape during the past year. The magnets have been set up in the newly constructed subterraneous hall; first electrons are expected in the SRF-gun test laboratory in June 2017. Starting in February 2018 the complete gun module will be transferred to the accelerator hall for the commissioning of BERLinPro. For the first months, operation is planned without further accelerating structures (booster and linac), due to delays in their fabrication. Several modes of operation are applicable at this early stage [1]. The available hardware is displayed and the adapted optics at 2.7 MeV and at 6.5 MeV (including the booster) are presented. The trajectory distortions under the influence of the earth magnetic field are studied. The concept for trajectory correction is outlined., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

BERLinPro is an energy recovery linac project whose goal is to establish the accelerator physics knowledge and technology needed to produce 50 MeV beams with high current, low normalized emittance, and low losses. Precise measurements of beam parameters are essential for demonstrating the achievement of performance goals. In this paper we present simulations for measurements of energy, energy spread, and bunch length using the tracking code Astra., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

The Helmholtz-Zentrum Berlin is constructing the Energy Recovery Linac Prototype BERLinPro, a demonstration facility for the science and technology of ERLs for future light source applications. BERLinPro is designed to accelerate a high current (100 mA, 50 MeV), high brilliance (norm. emittance below 1 mm mrad) cw electron beam. We report on the project status. This includes the completion of the building and the installation of the first accelerator components as well as the assembly of the SRF gun and GunLab beam diagnostics, which are now ready for commissioning., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

BERLinPro is an ERL project under construction at the Helmholtz-Zentrum Berlin, with the goal to illuminate the challenges and promises of a high brightness 100 mA superconducting RF gun in combination with a 50 MeV return loop and energy recovery. Latest changes to the optics code OPAL allow for the first time to perform start-to-end tracking studies including space charge in a single run, without switching between codes. This opens the way to apply correction schemes to displaced trajectories in the complete machine and to study the effect of jitter sources, including the space charge dominated injector, on the machine performance parameters. Trajectory correction is discussed. Jitter is studied with respect to its potential impact on the recovery process and parameter changes before the dump., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

OPAL (Object Oriented Parallel Accelerator Library) is an open source, C++ based tool for charged particle tracking in large accelerator structures and beam lines including 3D space charge, particle matter interaction and FFAG capabilities. The careful parallel design makes it possible to tackle large and complex problems, in a reasonable time frame. The current code status and latest program improvements and upgrades are introduced. One of the provided flavors, OPAL-T, was, so-far, used for relatively simple lattices and was not well suited for more complicated arrangements of elements. One of the major upgrades is the possibility to place elements in 3D space, giving the user a better control in absolute element positioning. The old input format with relative positioning is still supported. We show results of the BERLinPro lattice and compare it with results obtained with elegant., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

Dark current emitted from the surface of high-field RF cavities can contribute to radiation levels and cryo budget and can cause damage to sensitive accelerator components such as the photocathode. The superconducting niobium cavities in the booster module of BERLinPro will have surface fields strong enough to produce significant dark current from field emission, so simulations were made using Astra to track the propagation of emitted electrons from the surfaces of the cavities to examine the effects of dark current in the BERLinPro injector. Results of these simulations, including optimization of the layout to reduce propagation of electrons to the cathode and an estimation of power from dark current deposited throughout the injector, are presented., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

The Helmholtz Zentrum Berlin is constructing the Energy Recovery Linac Project BERLinPro on its site in Berlin Adlershof. The project is intended to expand the required accelerator physics and technology knowledge mandatory for the design, construction and operation of future synchrotron light sources. The project goal is the generation of a high current (100 mA), high brilliance (norm. emittance below 1 mm mrad) cw electron beamat 2~ps rms bunch duration or below. The planning phase of the project is completed and the design phase of most of the components is finished. Many of them have already been ordered. After some delay the construction of the building has started in February 2015. The status of the various subprojects as well as a summary of current and future activities will be given. Major project milestones and details of the project time line will be finally introduced., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

BERLinPro is an ERL project at Helmholtz-Zentrum Berlin, with the goal to illuminate the challenges and promises of a high brightness 100 mA superconducting RF gun in combination with a 50 MeV return loop and energy recovery [1, 2]. The precision of the beam position in a single turn machine might be relaxed compared to the demands in storage rings. Still, a trajectory correction concept has to be developed and the influence of trajectory offsets on the goal parameters, its dependence on fluctuating injection parameters or effects related to the low energy of 6.5-50 MeV have to be investigated. This paper covers the initial trajectory correction studies and first tolerance scenarios of BERLinPro using the projected hardware concept., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

The Berlin Energy Recovery Linac Prototype BERLinPro is to be constructed at the Helmholtz Zentrum site in Berlin. The aim of the project is to expand the required accelerator physics and technology knowledge mandatory for the generation of a high current (100 mA), high brilliance (norm. emittance below 1 mm mrad) cw electron beam. Since the funding decision in October 2010 the project has entered a phase of detailed planning. Hardware specifications have been defined and various components have been ordered. Furthermore, extensive tests of principal superconducting accelerator components successfully demonstrated the envisaged hardware performance. A summary of the most recent activities together with the details of the project timeline for the coming years are given in this paper., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

The Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB) proposes to construct an ERL test facility. To provide different operational modes for different scientific applications is one of the advantages of these new, linac-driven radiation sources. In contrast to the linear machine layouts of FELs, new challenges arise from incorporating the linac into a circular machine. One of them is the so called merger, a magnetic chicane that threads the low energy, low emittance, but high current bunch from the gun into the recirculator. The preservation of the ambitious gun parameters, the optimal collimation of dark current and flexibility to suit all user demands are the dominant design goals. Different design criteria and possible layouts are discussed and a preliminary merger design is proposed., Proceedings of the 1st International Particle Accelerator Conference, IPAC2010, Kyoto, Japan

The Helmholtz Zentrum Berlin (HZB) is proposing to build an Energy Recovery Linac Prototype, called BERLinPro, at its site in Berlin Adlershof. A gun test stand for a superconducting RF gun is already under construction at HoBiCaT. In this paper we concentrate on the recirculator part of the ERL and discuss the ERL requirements to the magnet optics. The current design of the magnet lattice will be described and main parameters and simulation results introduced. Since BERLinPro aims to demonstrate high current operation at short pulses according optics aspects will be also discussed. The focus here will be on longitudinal phase space manipulations and lattice layout options, suppressing the BBU instability and increasing its threshold currents., Proceedings of the 1st International Particle Accelerator Conference, IPAC2010, Kyoto, Japan

The Helmholtz Zentrum Berlin is constructing the Energy Recovery Linac Prototype BERLinPro at the Berlin Adlershof site. The project is intended to expand the required accelerator physics and technology knowledge mandatory for the design, construction and operation of future synchrotron light sources. The project goal is the generation of a high current (100 mA), high brilliance (norm. emittance below 1 mm mrad) cw electron beam. We report on the project progress: since spring 2015 the building is under construction, ready for occupancy in January 2017. The planning phase for the first project stage is completed for the warm machine parts, the SRF gun and partly for the SRF booster. Most of the components have been ordered and are in fabrication with some already delivered. An update of the status of the various subprojects as well as a summary of future activities will be given. Project milestones and details of the timeline will be reviewed., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea