لخّصلي

ALBA Synchrotron Heading Towards Its Upgrade C. BisCari, E. aignEr, K. attEnKofEr, J. C asas, s. fErrEr, o. M atilla, J. niColas, r. P asCual , f. P erEz, M. P ont, and a. sanChEz ALBA Synchrotron, Barcelona, Spain 1.It is motivated by the needs of three focus areas; life sci- ence, including structural molecular and integrative biology; energy, especially catalysis for carbon neutral economies and batteries for short term storage and electro-mobility; and information technology enabling the digital transformation, which mainly focuses on emerging technolo- gies and materials but extends to state-of-the-art device structures with increasing microscopy capabilities.By substantially contributing to ALBA II construction, the Span- ish and European research instrumentation industry is provided with opportunities to develop products and train their personnel in ac- celerator and X-ray technologies, competitively entering a global growth market characterized by the struggle of satisfying the in- creased requests caused by many simultaneous synchrotron upgrade projects worldwide.37, No. 1, 2024, Synchrotron radiation newS Technical RepoRT Environmental sustainability is incorporated in the ALBA II design and construction at different levels, starting with the definition of build- ings and services, continuing with specific requirements on call for ten- ders or detailed specifications of the constructive design.The injection scheme is based on a single fast pulsed multipole kicker magnet, the Double Di- pole Kicker (DDK), a 400 mm long in air kicker, composed of 8 con- ductor rods fixed on a ceramic vacuum chamber, titanium coated on the inner surface.ALBA II, with its boost of microscopy and imaging capabilities in combination with the extended energy range, reduced beam size, and improved data pipe- lines, will allow investigation into broader, more complex sample sets with a strong focus on applied science and industrial needs.Round beam operation is be- ing analyzed for a substantial improvement of the lifetime and it is also preferred for many experimental techniques since the photon beam co- herence lengths in the vertical and horizontal directions are equal.XBPMs will also be located in each front- end and the possibility of using them into the FOFB will be studied for those BLs that need it. Corrector magnets will be implemented as stand- alone devices in the straight sections and as extra winding in sextupoles inside the cells, keeping the system very compact.Introduction The ALBA Synchrotron light source [1] provides extended research capabilities and a wide range of state-of-the-art instrumentation to aca- demic and industrial users of the Spanish and European Research Area.ALBA delivers the Spanish research community another gate to the larger European research network and infrastructures, especially through the participation in LEAPS, the League of European Accelerator-based Photon Sources [2] and is one of the players of the recently published European Strategy for Accelerator-based Photon Sources (ESAPS 2022 [3]).ALBA II long BLs will extend to the nearby plots (see Figure 1), where there is opportunity to combine the corresponding experimental hall with new scientific and technological institutes.ALBA industrial users, of which 37% are small and medium enterprises (SME), belong mainly to the pharmaceutical, nanotechnology, advanced materials and chemistry sectors.The high magnetic field density requirements for the magnets im- plies very small vacuum chambers radius and the use of the new NEG coating technology with state-of-the-art functionalities.Thanks to its large circumference, the existing ALBA booster deliv- ers a small-emittance beam suitable for the injection into the upgraded storage ring, and does not need an upgrade.Building on operational excellence, this strategy pivots around multimodal characterization, in-situ and operando capabilities, fast, accessible high throughput capabilities, and the participation of the big-data world.org/licenses/by-nc-nd/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited, and is not altered, transformed, or built upon in any way.The 3 GeV electron energy will be maintained, while the nominal current will be increased from the present 250 to 300 mA. The ALBA II lattice, fitting into a 270 m long circumference, will be very compact.Four straight sections have high-betas, one for the injection, two for RF cavities, and one is available for one ID. Dynamic aperture optimization is being carried out with the applica- tion of genetic algorithms.The ALBA 500 MHz RF system is maintained, with the addition of a 3rd harmonic system to increase the bunch length and lifetime and to decrease the Intra Beam Scattering effect.Beam stability better than 10% of the beam size will be guaranteed by a Fast Orbit Feedback (FOFB) system, which will use the 10 kHz data stream from hundreds of Beam Position Moni- tors (BPM) around the ring.The combination of a large research infrastructure and a science and technology park, situated near the Barcelona universities and research centers, along with the proximity of the Autonomous University of Barcelona [4], will foster research, innovation, and economic growth.In collaboration with the user community, ALBA has developed a holistic approach focusing on the big scientific, economic, and ecologi- cal challenges our society faces.A new one, the Interdisciplinary and MultiModal Section [6] covers JEMCA (Joint Electron Microscopy Center at ALBA), a recently inaugurated ad- vanced microscopy center in partnership with other institutions.ALBA is ready to leap from the 3rd to the 4th generation and give birth to ALBA II by combining the upgrade of the storage ring with that of the existing instrumentation and the addition of new cutting-edge beamlines (BLs).The ALBA-II project has the following objectives for day-one:

• Renovation of the accelerator structure and adaptation of the cor- responding infrastructures.The design is based on MultiBend achromat cells configuration [7] (see Figure 3), reducing the horizontal natural emittance to about 200 pmrad, a factor of 20 lower than ALBA's.37, No. 1, 2024 19 Technical RepoRT Three sections cover the three strategic areas: Life Science, Chemical and Materials Sciences, and Magnetic and Electronic Structure.Dedicated and advanced proprietary services have strengthened the industrial community supporting its technological innovation.ALBA will maintain its relevance in the future research infrastruc- ture landscape by upgrading to a 4th generation light source, ALBA II, which is planned to become fully operational in 2031.- Development of further capabilities for automatization, simula- tion, prototyping, nanotechnology and advanced optics.ALBA II is giving way to modern resource and energy consumption schemes re- sulting in more efficiency and less environmental impact.ALBA II accelerator, sources, and beamlines 3.1 Accelerator The upgrade will transform the ALBA storage ring into a high coherence light source.High stability diagnostics adapted to the small beam size, and com- pact accelerator will be distributed along the ring using all the available space between magnets.ALBA evolution from 3rd to 4th generation ALBA is a Synchrotron Light Facility managed by the Consortium for the Construction, Equipment and Exploitation of a Synchrotron Light Laboratory (CELLS) in operation since 2012.It is a member of the Spanish Map of Infraestructuras Cientifico Tecnicas Singulares (ICTS) [5], and it is a non-profit public entity supported by the Spanish and Catalan governments.This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License (http://creativecommons.ALBA is developing its new services and infrastructures, ensuring the fast and easy role out of new services to the broad existing user community.The terms on which this article has been published allow the posting of the Accepted Manuscript in a repository by the author(s) or with their consent.Published with license by Taylor & Francis Group, LLC Synchrotron radiation newS, Vol.- Renovation of existing BLs, including instrumentation, data stor- age and analysis system.All current BLs will be overhauled to adapt them for fully exploiting the high brilliance of the new pho- ton source.The BL which will enter in operation in 2026 is already optimized for ALBA II characteris- tics.It will be a cost and time effective process, prof- iting at maximum from all existing infrastructure, in particular the building, which is now hosting the facility.The injector, the accelerator tunnel, and the Insertion Devices (IDs) will be maintained.The overall ring symmetry is preserved: the lattice is composed of 16 cells organized in four quadrants.ALBA is a 3rd generation, 3 GeV synchrotron light source, with 11 BLs in operation.Two additional BLs, now in commissioning, will start operation in 2024 and another one, currently in the procurement phase, will start in 2026 (see Figure 2).The great level of collaboration between visiting scientists and expert staff is a key element of the evolution of the com- munity.An adjacent land plot has been acquired to allow the extension of the infrastructure and to allow the construction of up to three long beam- lines, as shown in Figure 1.Their experimental stations can also be the seed for new research centers in collaboration with other institutions.Their design, construction and installation are carried out while operating ALBA; commissioning is postponed until the new source is available.20 Vol.2.3.

ALBA Synchrotron Heading Towards Its Upgrade
C. BisCari, E. aignEr, K. attEnKofEr, J. C asas, s. fErrEr, o. M atilla, J. niColas, r. P asCual ,
f. P érEz, M. P ont, and a. sánChEz
ALBA Synchrotron, Barcelona, Spain

1. Introduction
   The ALBA Synchrotron light source [1] provides extended research
   capabilities and a wide range of state-of-the-art instrumentation to aca-
   demic and industrial users of the Spanish and European Research Area.
   ALBA delivers the Spanish research community another gate to the
   larger European research network and infrastructures, especially
   through the participation in LEAPS, the League of European
   Accelerator-based Photon Sources [2] and is one of the players of the
   recently published European Strategy for Accelerator-based Photon
   Sources (ESAPS 2022 [3]).
   ALBA is ready to leap from the 3rd to the 4th generation and give
   birth to ALBA II by combining the upgrade of the storage ring with that
   of the existing instrumentation and the addition of new cutting-edge
   beamlines (BLs).
   ALBA II long BLs will extend to the nearby plots (see Figure 1),
   where there is opportunity to combine the corresponding experimental
   hall with new scientific and technological institutes. The combination
   of a large research infrastructure and a science and technology park,
   situated near the Barcelona universities and research centers, along
   with the proximity of the Autonomous University of Barcelona [4], will
   foster research, innovation, and economic growth. This initiative will
   also provide Spain with a unique high-tech company incubator.


2. ALBA evolution from 3rd to 4th generation
   ALBA is a Synchrotron Light Facility managed by the Consortium
   for the Construction, Equipment and Exploitation of a Synchrotron
   Light Laboratory (CELLS) in operation since 2012. It is a member of
   the Spanish Map of Infraestructuras Científico Técnicas Singulares
   (ICTS) [5], and it is a non-profit public entity supported by the Spanish
   and Catalan governments.
   ALBA is a 3rd generation, 3 GeV synchrotron light source, with 11
   BLs in operation. Two additional BLs, now in commissioning, will start
   operation in 2024 and another one, currently in the procurement phase,
   will start in 2026 (see Figure 2). ALBA operates 24 hours per day in 4
   to 5 week runs all year long, accumulating almost 6000 hours per year
   of operation. The operation of the accelerator systems is highly reliable
   and reaches an average availability above 98%.
   In collaboration with the user community, ALBA has developed a
   holistic approach focusing on the big scientific, economic, and ecologi-
   cal challenges our society faces. Building on operational excellence,
   this strategy pivots around multimodal characterization, in-situ and
   operando capabilities, fast, accessible high throughput capabilities, and
   the participation of the big-data world.
   ALBA is developing its new services and infrastructures, ensuring
   the fast and easy role out of new services to the broad existing user
   community. It is motivated by the needs of three focus areas; life sci-
   ence, including structural molecular and integrative biology; energy,
   especially catalysis for carbon neutral economies and batteries for short
   term storage and electro-mobility; and information technology enabling
   the digital transformation, which mainly focuses on emerging technolo-
   gies and materials but extends to state-of-the-art device structures with
   increasing microscopy capabilities.
   Figure 1: ALBA and future ALBA II new experimental hall extension.
   This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License (http://creativecommons.
   org/licenses/by-nc-nd/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited, and is
   not altered, transformed, or built upon in any way. The terms on which this article has been published allow the posting of the Accepted Manuscript in a repository by
   the author(s) or with their consent.
   © 2024 C.E.E. LAB LUZ SINCROTRON (ALBA-CELLS). Published with license by Taylor & Francis Group, LLC
   Synchrotron radiation newS, Vol. 37, No. 1, 2024 19
   Technical RepoRT
   Three sections cover the three strategic areas: Life Science, Chemical
   and Materials Sciences, and Magnetic and Electronic Structure. A new
   one, the Interdisciplinary and MultiModal Section [6] covers JEMCA
   (Joint Electron Microscopy Center at ALBA), a recently inaugurated ad-
   vanced microscopy center in partnership with other institutions.
   All BLs are oversubscribed, with an average overbooking factor of


3. The community of users served by ALBA has grown ten times from
   the start of operations, having reached more than 7500 national and in-
   ternational users. The great level of collaboration between visiting
   scientists and expert staff is a key element of the evolution of the com-
   munity. The result of that intense activity is a total of more than 2900
   scientific publications, with a high average impact factor (>9 in the last
   two years).
   Dedicated and advanced proprietary services have strengthened the
   industrial community supporting its technological innovation. ALBA
   industrial users, of which 37% are small and medium enterprises
   (SME), belong mainly to the pharmaceutical, nanotechnology, advanced
   materials and chemistry sectors.
   ALBA will maintain its relevance in the future research infrastruc-
   ture landscape by upgrading to a 4th generation light source, ALBA II,
   which is planned to become fully operational in 2031. ALBA II, with its
   boost of microscopy and imaging capabilities in combination with the
   extended energy range, reduced beam size, and improved data pipe-
   lines, will allow investigation into broader, more complex sample sets
   with a strong focus on applied science and industrial needs.
   The design, construction and part of the installation will be carried
   out over the next years, while ALBA continues operating. The dark
   period, in the years 2030 and 2031, will be dedicated to the installation
   and commissioning of the new light source.
   An adjacent land plot has been acquired to allow the extension of the
   infrastructure and to allow the construction of up to three long beam-
   lines, as shown in Figure 1. Their experimental stations can also be the
   seed for new research centers in collaboration with other institutions.
   The ALBA-II project has the following objectives for day-one:
   – Renovation of the accelerator structure and adaptation of the cor-
   responding infrastructures.
   – Construction of three new BLs, two of them with long paths.
   Their design, construction and installation are carried out while
   operating ALBA; commissioning is postponed until the new
   source is available.
   – Renovation of existing BLs, including instrumentation, data stor-
   age and analysis system. All current BLs will be overhauled to
   adapt them for fully exploiting the high brilliance of the new pho-
   ton source. Some of them will also need refurbishment since they
   have been in operation for one decade. The BL which will enter in
   operation in 2026 is already optimized for ALBA II characteris-
   tics.
   – Development of further capabilities for automatization, simula-
   tion, prototyping, nanotechnology and advanced optics.
   Few other light ports are still available, two of them with the possi-
   bility of building other two long BLs. This opens the possibility to con-
   solidate collaborations with other institutions interested in developing
   joint projects.
   By substantially contributing to ALBA II construction, the Span-
   ish and European research instrumentation industry is provided with
   opportunities to develop products and train their personnel in ac-
   celerator and X-ray technologies, competitively entering a global
   growth market characterized by the struggle of satisfying the in-
   creased requests caused by many simultaneous synchrotron upgrade
   projects worldwide.
   Figure 2: Layout of ALBA with its present beamlines.
   20 Vol. 37, No. 1, 2024, Synchrotron radiation newS
   Technical RepoRT
   Environmental sustainability is incorporated in the ALBA II design
   and construction at different levels, starting with the definition of build-
   ings and services, continuing with specific requirements on call for ten-
   ders or detailed specifications of the constructive design. ALBA II is
   giving way to modern resource and energy consumption schemes re-
   sulting in more efficiency and less environmental impact.


4. ALBA II accelerator, sources, and beamlines
   3.1 Accelerator
   The upgrade will transform the ALBA storage ring into a high
   coherence light source. It will be a cost and time effective process, prof-
   iting at maximum from all existing infrastructure, in particular the
   building, which is now hosting the facility. The injector, the accelerator
   tunnel, and the Insertion Devices (IDs) will be maintained. The 3 GeV
   electron energy will be maintained, while the nominal current will be
   increased from the present 250 to 300 mA.
   The ALBA II lattice, fitting into a 270 m long circumference, will be
   very compact. The design is based on MultiBend achromat cells
   configuration [7] (see Figure 3), reducing the horizontal natural
   emittance to about 200 pmrad, a factor of 20 lower than ALBA’s. The
   overall ring symmetry is preserved: the lattice is composed of 16 cells
   organized in four quadrants. Four straight sections have high-betas, one
   for the injection, two for RF cavities, and one is available for one ID.
   Dynamic aperture optimization is being carried out with the applica-
   tion of genetic algorithms.
   The high magnetic field density requirements for the magnets im-
   plies very small vacuum chambers radius and the use of the new NEG
   coating technology with state-of-the-art functionalities. The smallest
   magnet aperture is 20 mm, with an effective vacuum chamber of about
   16 mm in diameter. The detailed design of the different sections is now
   ongoing.
   The ALBA 500 MHz RF system is maintained, with the addition of
   a 3rd harmonic system to increase the bunch length and lifetime and to
   decrease the Intra Beam Scattering effect. Round beam operation is be-
   ing analyzed for a substantial improvement of the lifetime and it is also
   preferred for many experimental techniques since the photon beam co-
   herence lengths in the vertical and horizontal directions are equal.
   High stability diagnostics adapted to the small beam size, and com-
   pact accelerator will be distributed along the ring using all the available
   space between magnets. Beam stability better than 10% of the beam
   size will be guaranteed by a Fast Orbit Feedback (FOFB) system, which
   will use the 10 kHz data stream from hundreds of Beam Position Moni-
   tors (BPM) around the ring. XBPMs will also be located in each front-
   end and the possibility of using them into the FOFB will be studied for
   those BLs that need it. Corrector magnets will be implemented as stand-
   alone devices in the straight sections and as extra winding in sextupoles
   inside the cells, keeping the system very compact.
   Thanks to its large circumference, the existing ALBA booster deliv-
   ers a small-emittance beam suitable for the injection into the upgraded
   storage ring, and does not need an upgrade. The injection scheme is
   based on a single fast pulsed multipole kicker magnet, the Double Di-
   pole Kicker (DDK), a 400 mm long in air kicker, composed of 8 con-
   ductor rods fixed on a ceramic vacuum chamber, titanium coated on the
   inner surface. A prototype is being built and will be installed and tested
   in the existing ALBA ring.
   The development and verification of the magnet designs is taking
   place by means of adequate prototypes during the period 2022–25
   within the framework of a project entitled “Enabling technologies for
   ALBA II.”
   Nine different types of magnet are used in the lattice, for a total of
   almost 600 individual magnets, more than doubling those of the current
   storage ring. Conventional electro-magnet technology is adopted to de-
   fine a baseline design for all magnets, even if the possibility of using
   permanent magnets (PM) or hybrid designs for some particular types of
   magnets is being explored, mainly aiming at lowering the power con-
   sumption.
   Figure 3: ALBA II arc example (pink: antibend and quadrupole; yellow: sextupole and corrector; red: dipole and quadrupole; blue: quadrupole, green:
   corrector).
   Synchrotron radiation newS, Vol. 37, No. 1, 2024 21
   Technical RepoRT
   3.2 Photon sources
   A total portfolio of 26 BL ports will be available at ALBA II.
   Even if the layout of the new storage ring differs from the present
   one, only the BLs with dipoles as photon sources will need to be
   displaced.
   The photon flux and coherence of the existing undulator sources
   will strongly benefit from the foreseen 20-fold decrease of the electron
   beam emittance. Figure 4 left shows a comparison between the spectral
   brilliance calculated for the undulators in ALBA and ALBA II. The
   expected brilliance increase will depend on the photon beam energy:
   from a factor 6 at 100 eV up to a factor 20 at 10 keV. For the wigglers
   and dipole sources there is a smaller gain in brilliance mostly given by
   the smaller source size. Figure 4 right shows the increase of the hori-
   zontal coherent fraction, which measures how close the source is to the
   diffraction limit, and which is at higher photon energies. In addition, the
   availability of long BLs will allow exploiting transverse coherence,
   also at higher photon energies.
   The reduction of the horizontal beam size will allow for round vac-
   uum chambers in the straight sections, opening the door to IDs with
   magnetic material surrounding the electron beam, as Delta-type [8] or
   APPLE-X [9] undulators. It is also foreseen to explore the development
   of superconducting and cryogenic undulators increasing the available
   photon energy.
   ALBA II will have ports for thirteen bending magnet BLs, including
   the four already in use. Some of these will be able to reach high photon
   energies by using a superbend magnet based on the PM design
   developed by SIRIUS [10], with a peak magnetic field up to 3 T.
   3.3 Beamlines
   The total number of BLs in ALBA II on day-one will be 17 (see
   Figure 5). The 14 existing BLs will be upgraded in different aspects, in
   order to benefit from the features of the new source. For instance, most
   optical elements currently installed have surface errors that would limit
   the spot size and the photon flux density achievable on sample, and
   Figure 4: Left: Comparison of the spectral brilliance for undulators operating in the present (ALBA, 1% coupling, dashed lines) and the upgraded (ALBA
   II, 100% coupling, solid lines) storage ring, for the same electron beam current (250 mA). Right: Evolution of horizontal coherent fraction with ALBA
   upgrade. Dashed lines correspond to present storage ring (ALBA, 1% coupling) and solid lines to the upgraded one (ALBA II, 100% coupling). Results
   obtained using SPECTRA within Gaussian approximation.
   Figure 5: Layout of Day-One ALBA II.
   22 Vol. 37, No. 1, 2024, Synchrotron radiation newS
   Technical RepoRT
   would introduce significant structures and inhomogeneities in the pho-
   ton beam. BLs and experimental stations will require more accurate and
   stable positioning systems, as well as faster scanning systems. Refur-
   bishment of aged systems when needed is also part of the upgrade.
   The increased flux on sample of ALBA-II (see Figure 6) will
   allow collecting data with sufficient statistics using shorter acquisi -
   tion times, improving the sensitivity limit of many experimental sta-
   tions. The BLs, including mechanics, detector, and control systems,
   must be prepared to run the experiment at the required speed. In
   addition, the reduced dimensions of the beam will lead to tighter
   stability requirements, not just on scanning components, but on ev-
   ery component interacting with the beam. Finally, the higher acqui-
   sition rate at the experimental station will require the BL to be free
   of mechanical resonances in a wider range of frequencies than for
   ALBA.
   Increased demands on speed, accuracy, and stability will be faced
   with improvements on components. From a mechanical design per-
   spective, systems will be more compact, with simpler kinematic
   chains, and working in a closed loop using feedback from encoders
   and interferometers. Continuous scans at high speed and synchroniz-
   ing multiple axes during the experiment will be the routine mode of
   operation.
   At ALBA II, the amount of data generated in the BLs will increase
   by several orders of magnitude with respect to the present thanks to the
   higher X-ray flux, combined with the hundreds of kHz frame rates
   attained by the newest detectors. Guaranteeing scientific success will
   require providing users with external access to the data and to the High-
   Performance Computing clusters needed for processing it, and, just as
   necessary, adequate software applications to exploit these types of in-
   frastructures.
   Proper metadata ingestion for future reuse and completeness of the
   information plus data pipelines will also be provided.
   3.4 First two long beamlines
   On day one, ALBA II will have two long BLs, CoDI and CORUS,
   with nanometers focusing at the positions of the samples located at
   230–270 m from the photon sources.
   CoDI will be a hard X-ray (10–30 keV) coherent diffraction imag-
   ing BL for in situ and operando research of a large variety of scientific
   cases such as semiconductors, electrocatalysis, quantum materials,
   earth science, and geochemistry. The main techniques based on a nano-
   focused beam will include X-ray fluorescence, diffraction, ptychogra-
   phy, holo-tomography (phase contrast microscopy) and coherent
   diffraction imaging. A preliminary beamline layout is schematically
   shown in Figure 7. The focused beam dimensions have been calculated
   to be in the range of 30–50 nm at 20 keV. The sample stage in the end-
   station will include a rotary stage, a hexapode, and a piezo stage for
   high resolution positioning.
   CORUS will be a hard X-ray cryogenic nanoprobe BL to investigate
   sensitive biological samples at the nanoscale to understand their struc-
   ture and interactions. The beamline will have two end-stations. The first
   one, NanoImag, will be devoted to 3D cryo-nano fluorescence (XRF)
   and 3D cryo or room temperature (RT) phase contrast imaging (PCI)
   based on the propagation-based technique, enabling 2D and 3D imaging
   and quantification of trace endo- and exogenous elements at very high
   sensitivity (parts per million level) in whole prokaryotic and eukaryotic
   cells in near-to-native conditions or tissue sections. The second station,
   NanoSpec, will be one of the few instruments in Europe to allow cryo
   spectromicroscopy 2D/3D XRF maps varying the photon energy and
   acquiring single point nano-XANES spectra, while it will be the only
   one with 3D capabilities. Cryogenic temperatures will allow probing
   chemical states at the cellular level in close-to-native conditions and will
   enable understanding the mode of action of drugs and their toxicity,
   biomineralization among others. The beamline optics are rather similar
   to that in Figure 7. The expected beam dimensions at the sample posi-
   Figure 6: Simulation of the flux density emitted by IVU21 (XALOC BL).