Publications by Riccardo Bartolini


Double-double bend achromat cell upgrade at the Diamond Light Source: From design to commissioning

PHYSICAL REVIEW ACCELERATORS AND BEAMS 21 (2018) ARTN 050701

R Bartolini, C Abraham, M Apollonio, CP Bailey, MP Cox, A Day, RT Fielder, NP Hammond, MT Heron, R Holdsworth, J Kay, IPS Martin, S Mhaskar, A Miller, T Pulampong, G Rehm, ECM Rial, A Rose, A Shahveh, B Singh, A Thomson, RP Walker


Characterization of the double-double bend achromat lattice modification to the Diamond Light Source storage ring

PHYSICAL REVIEW ACCELERATORS AND BEAMS 21 (2018) ARTN 060701

IPS Martin, M Apollonio, RT Fielder, E Koukovini-Platia, B Singh, R Bartolini


Conceptual design of an accumulator ring for the Diamond II upgrade

Journal of Physics: Conference Series 1067 (2018)

IPS Martin, R Bartolini

© 2018 Institute of Physics Publishing. All rights reserved. Diamond Light Source is in the process of reviewing several lattice options for a potential storage ring upgrade. As part of these studies, it has become clear that a substantial reduction in emittance can be achieved by adopting an on-axis injection scheme, thereby relaxing the constraints on the dynamic aperture. In order to achieve the necessary injected bunch properties for this to be viable, a new accumulator ring would be needed. In this paper we review the requirements placed on the accumulator ring design, describe the lattice development process and analyse the performance of the initial, conceptual design.


Brilliant X-rays using a two-stage plasma insertion device

Scientific Reports Springer Nature 7 (2017) 3985

JA Holloway, P Norreys, AGR Thomas, R Bartolini, R Bingham, J Nydell, RMGM Trines, R Walker, M Wing

Particle accelerators have made an enormous impact in all fields of natural sciences, from elementary particle physics, to the imaging of proteins and the development of new pharmaceuticals. Modern light sources have advanced many fields by providing extraordinarily bright, short X-ray pulses. Here we present a novel numerical study, demonstrating that existing third generation light sources can significantly enhance the brightness and photon energy of their X-ray pulses by undulating their beams within plasma wakefields. This study shows that a three order of magnitude increase in X-ray brightness and over an order of magnitude increase in X-ray photon energy is achieved by passing a 3 GeV electron beam through a two-stage plasma insertion device. The production mechanism micro-bunches the electron beam and ensures the pulses are radially polarised on creation. We also demonstrate that the micro-bunched electron beam is itself an effective wakefield driver that can potentially accelerate a witness electron beam up to 6 GeV.


Experimental and theoretical studies of the properties of coherent Smith-Purcell radiation

Proceedings of International Particle Accelerator Conference 8-13 May 2016, Busan, Korea Joint Accelerator Conferences Website (JACoW) (2016)

F Bakkali Taheri, IV Konoplev, G Doucas, A Reichold, R Bartolini, N Delerue, J Barros, C Clarke

Recent advances in physics of particles accelerators and lasers have shifted dramatically the expectations of bunch length and capability to generate electron bunches with specific longitudinal profiles [1,2]. This has stimulated interest in analysis of spectrum of coherent radiation to enable the longitudinal bunch profile diagnostics at femtosecond-scale. Spectral analysis of coherent Smith- Purcell radiation (cSPr) is particularly relevant as it allows non-invasive and cost-effective monitoring of electron bunch profiles. In this paper, the recent results observed from the E203 experiment (FACET, SLAC) are presented. Consistency of the cSPr as diagnostic tool is discussed, as well as the properties of cSPr such as directionality and polarization.


A novel approach in one-dimensional phase retrival problem and its application to the time profile recon-struction

IPAC 2016 - Proceedings of the 7th International Particle Accelerator Conference (2016) 955-957

F Bakkali Taheri, IV Konoplev, G Doucas, R Bartolini, J Cowley, SM Hooker

Copyright © 2016 CC-BY-3.0 and by the respective authors. Phase retrieval problem occurs in a number of areas in physics and is the subject of continuing investigation [1-15]. One dimensional case, for example, an electron bunch temporal profile reconstruction, is particularly challenging. Frequently applied methods, are reliable if the Blaschke phase [10-12] contribution is negligible. This, however, is neither known a priori nor can it be assumed for an arbitrary profile. In this work we present a novel algorithm with additional constraints which gives reproducible, stable solutions for profiles, both artificial and experimental, otherwise unresolved by existing techniques.


Studies to install a multipole wiggler by removing a chromatic sextupole in diamond storage ring

IPAC 2016 - Proceedings of the 7th International Particle Accelerator Conference (2016) 3518-3521

B Singh, M Apollonio, R Bartolini, R Fielder, E Koukovini-Platia, IPS Martin, T Pulampong, RP Walker

Copyright © 2016 CC-BY-3.0 and by the respective authors. Investigations are underway for a possible use of achromat to install a multipole wiggler by removing a chromatic sextupole in cell-11 after first modification named as DDBA-1 in cell-2. The effect on emittance and energy spread is found to be small. The impact of removing a chromatic sextupole on lifetime and injection is significant if chromatcity is corrected globally. The MOGA genetic algorithm is used to optimize the lifetime and injection efficiency in this case. We used the local mirror chromatic sextupole and other chromatic sextupole family for chromaticity correction in which case the genetic algorithm found a solution that restores lifetime and injection efficiency. In this paper the results of MOGA simulations using various schemes of chromaticity correction and test results in presently operational optics will be discussed.


Concepts for a low emittance-high capacity storage ring for the Diamond Light Source

IPAC 2016 - Proceedings of the 7th International Particle Accelerator Conference (2016) 2943-2946

R Bartolini, G Cinque, G Evans, K Sawhney, J Zegenhagen

Copyright © 2016 CC-BY-3.0 and by the respective authors. The Diamond Light Source is investigating several paths for a possible machine upgrade to Diamond II. The exercise is driven by a joint assessment of the science capabilities opened by a very low emittance ring and the machine design that will underpin them. The consultation is made on a beamline-by-beamline basis and has highlighted a significant preference for lattices that combine both a low emittance and large capacity for IDs.


Online suppression of the sextupole resonance driving termsin the diamond storage ring

IPAC 2016 - Proceedings of the 7th International Particle Accelerator Conference (2016) 3381-3384

IPS Martin, M Apollonio, R Bartolini

Copyright © 2016 CC-BY-3.0 and by the respective authors. Suppression of the sextupole resonance driving terms (RDTs) is a widely used technique for optimising the theoretical on and off-momentum dynamic aperture for electron storage rings. Recently, this technique was applied online to the Diamond storage ring, with suppression of individual RDTs achieved via a sextupole family to RDT response matrix [1]. In this paper we present recent studies of the method, in which the ability to improve the lifetime and injection efficiency are investigated. An extension of the technique is explored by combining it with the Robust Conjugate Direction Search (RCDS) optimisation algorithm [2].


Injection using a nonlinear kicker located in the existing injection straight at Diamond storage ring

IPAC 2016 - Proceedings of the 7th International Particle Accelerator Conference (2016) 840-843

B Singh, A Alekou, M Apollonio, R Bartolini, I Martin, T Pulampong

Copyright © 2016 CC-BY-3.0 and by the respective authors. Injection studies using a non-linear kicker for the Diamond storage ring have been previously carried out [1]. These studies have been recently extended to investigate whether the non-linear kicker can be located in the injection straight downstream of the septum and outside the existing dipole kicker bump. If so, injection with a nonlinear kicker becomes independent of the optics used, making it suitable for use in both standard and low alpha mode. With this configuration, the existing injection scheme could also be left in place, leaving open the possibility to study both schemes in situ before potentially removing the existing dipole kickers at a later date. In order to operate with the non-linear kicker, the injected beam needs to exit the transfer line at an angle of 3mrad; this has been successfully demonstrated during machine development time. The concept and feasibility studies of this scheme are presented in this paper.


Analysis of multi-bunch instabilities at the Diamond storage ring

IPAC 2016 - Proceedings of the 7th International Particle Accelerator Conference (2016) 1685-1687

R Bartolini, R Fielder, G Rehm, V Smaluk

Copyright © 2016 CC-BY-3.0 and by the respective authors. We present the result of the analytical, numerical and experimental analysis of multi-bunch instabilities at the Diamond storage ring. This work compares the impedance estimates with CST with the analysis of the growth rates of the excited multi-bunch modes in different machine configurations. The contribution of a number of wakefield sources has been identified with very high precision thanks to high quality data provided by the existing TMBF diagnostics.


Design and optimisation strategies of nonlinear dynamics for diffraction limited synchrotron light sources

IPAC 2016 - Proceedings of the 7th International Particle Accelerator Conference (2016) 33-38

R Bartolini

Copyright © 2016 CC-BY-3.0 and by the respective authors. This paper introduces the most recent achievements in the control of nonlinear dynamics in electron synchrotron light sources, with special attention to diffraction limited storage rings. Guidelines for the design and optimization of the magnetic lattice are reviewed and discussed.


Single bunch instability studies at Diamond light source

IPAC 2016 - Proceedings of the 7th International Particle Accelerator Conference (2016) 637-640

E Koukovini-Platia, M Apollonio, R Bartolini, R Fielder, I Martin

Copyright © 2016 CC-BY-3.0 and by the respective authors. Single bunch instability thresholds, the associated coherent tune shifts and the bunch lengthening have been studied at Diamond light source for nominal optics. Measurements were taken under different settings of chromaticity, radiofrequency (RF) voltage and aperture of the insertion devices (IDs). The macro-particle code sbtrack was used to evaluate the instability thresholds and bunch lengthening where different impedance contributions are taken into account such as the resistive wall impedance, a broad-band resonator model and inductive impedance for the longitudinal plane. A comparison of simulation using the developed model impedance with measurements is shown for all cases.


Study of a Double Triple Bend Achromat (DTBA) lattice for a 3 GeV light source

IPAC 2016 - Proceedings of the 7th International Particle Accelerator Conference (2016) 2940-2942

A Alekou, R Bartolini, N Carmignani, SM Liuzzo, P Raimondi, T Pulampong, RP Walker

Copyright © 2016 CC-BY-3.0 and by the respective authors. Starting from the concepts of the Hybrid Multi Bend Achromat (HMBA) lattice developed at ESRF and of the Double-Double Bend Achromat (DDBA) lattice developed at Diamond, we present a new cell that includes all the advantages of the two designs. The resulting Double Triple Bend Achromat (DTBA) cell allows for a natural horizontal emittance of less than 100 pm with a large dynamic aperture and lifetime. It includes two straight sections, for insertion devices, five and three meters long. The lattice is consistent with the engineering design developed for the ESRF-EBS lattice and the layout and user requirements of Diamond. The characteristics of the cell are presented together with the results of the optimisation process.


THz coherent synchrotron radiation from ultra-low alpha operating mode at Diamond Light Source

IPAC 2016 - Proceedings of the 7th International Particle Accelerator Conference (2016) 1682-1684

T Chanwattana, M Atay, R Bartolini, G Cinque, M Frogley, E Koukovini-Platia, I Martin

Copyright © 2016 CC-BY-3.0 and by the respective authors. The Diamond Light Source is regularly operated in low-alpha mode to provide THz coherent synchrotron radiation (CSR) and short X-ray pulses for users. In order to maintain the wide frequency range of the coherent radiation whilst improving the signal to noise ratio, an ultra-low alpha mode has been considered to shorten the bunch length even further. In order to study this mode, the analysis of single bunch dynamics resulting from a variety of wakefield sources has been investigated using a single bunch multi-particle tracking code. These results are compared with measurements recorded using a Fourier transform infrared (FTIR) interferometer on the MIRIAM beam-line at Diamond.


Electron bunch profile reconstruction based on phase-constrained iterative algorithm

Physical Review Accelerators and Beams American Physical Society 19 (2016)

F Bakkali Taheri, I Konoplev, G Doucas, P Baddoo, R Bartolini, J Cowley, SM Hooker

The phase retrieval problem occurs in a number of areas in physics and is the subject of continuing investigation. The one-dimensional case, e.g., the reconstruction of the temporal profile of a charged particle bunch, is particularly challenging and important for particle accelerators. Accurate knowledge of the longitudinal (time) profile of the bunch is important in the context of linear colliders, wakefield accelerators and for the next generation of light sources, including x-ray SASE FELs. Frequently applied methods, e.g., minimal phase retrieval or other iterative algorithms, are reliable if the Blaschke phase contribution is negligible. This, however, is neither known a priori nor can it be assumed to apply to an arbitrary bunch profile. We present a novel approach which gives reproducible, most-probable and stable reconstructions for bunch profiles (both artificial and experimental) that would otherwise remain unresolved by the existing techniques.


On-line control of the nonlinear dynamics for synchrotrons

PHYSICAL REVIEW SPECIAL TOPICS-ACCELERATORS AND BEAMS 18 (2015) ARTN 074002

J Bengtsson, IPS Martin, JH Rowland, R Bartolini


Development of advanced fourth generation light sources for the accelerator science laboratory

6th International Particle Accelerator Conference, IPAC 2015 (2015) 1765-1767

T Chanwattana, R Bartolini, A Seryi, E Tsesmelis

Copyright © 2015 CC-BY-3.0 and by the respective authors. The John Adams Institute for Accelerator Science (JAI) has proposed the realisation of the Accelerator Science Laboratory (ASL) at the University of Oxford as a facility for the development of advanced compact light sources enabling accelerator science research and applications. The installation of a compact light source in the ASL is planned with two options for the accelerating technologies. Firstly, a conventional RF based accelerator is considered to be a driver for a short pulse THz coherent synchrotron radiation (CSR). The other option focusses on the radiation produced by a Laser Plasma Accelerator (LPA) advanced accelerator technique that will provide the possibility to shorten the length of the beamline. This paper presents results of the studies on beam dynamics for both options of compact light sources in the ASL.


Injection studies for the Diamond storage ring

6th International Particle Accelerator Conference, IPAC 2015 (2015) 1768-1771

IPS Martin, M Apollonio, R Bartolini

Copyright © 2015 CC-BY-3.0 and by the respective authors. The Diamond storage ring will be upgraded during 2016 by replacing one of the existing double bend achromat (DBA) cells with a double-DBA (DDBA) cell [1]. It is anticipated that both the on and off momentum dynamic aperture will reduce as a result of this change. In order to prepare for this eventuality, injection into the Diamond storage ring has been recently studied in detail. In particular, the oscillation amplitude, angle and energy of the injected beam have been determined, along with the position of the stored beam with respect to the septum plate. Following these studies, the injected beam energy has been matched to the storage ring, and plans have been put in place to move the injection septum 4 mm closer to the stored beam centre line.


Beam-based model of broad-band impedance of the Diamond Light Source

PHYSICAL REVIEW SPECIAL TOPICS-ACCELERATORS AND BEAMS 18 (2015) ARTN 064401

V Smaluk, I Martin, R Fielder, R Bartolini

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