Search

The Forward Physics Facility (FPF) is a proposed new facility to house several new experiments at the CERN High Luminosity LHC (HL-LHC). The FPF is located such that the experiments can be aligned with the collision axis line of sight (LOS), a location which allows many interesting physics measurements and searches for new physics to be carried out. The status of technical studies related to the FPF, as well as the physics potential were documented in Ref. [1] which was released in March 2022. This note documents updates to the FPF technical studies completed since that time.

In the framework of the Physics Beyond Colliders (PBC) study, a future high intensity facility at the existing ECN3 experimental hall of the North Area (NA) complex is under study. A task force is investigating ECN3 intensity upgrade scenarios concerning beam delivery and related infrastructure, considering solutions compatible with consolidation plans and post-LS3 experimental scenarios. As input to this study group, the sharing scenarios for the amount of protons on target (PoT) delivered to such a future high intensity fixed-target facility and the existing North Area experiments are presented in this report. Based on demonstrated Super Proton Synchrotron (SPS) performance for CERN Neutrinos to Gran Sasso (CNGS) and the recent SPS performance for fixed target beams following the successful completion of the LHC Injectors Upgrade (LIU) project, the expected proton sharing between the TCC2 targets and ECN3 is estimated. AWAKE and HiRadMat are taken into account in the future supercycle composition while the maximum possible power dissipation of the SPS magnets is respected. In the note it is also assumed that measures will be taken to address beam loss and activation at extraction and transfer compatibly with the transmission efficiency presented here. Finally, also considerations on power consumption are made for the different operational scenarios.

Acknowledgments We thank the participants of the FPF meetings and the Snowmass working groups for discussions that have contributed both directly and indirectly to this study. We gratefully acknowledge the invaluable support of the CERN Physics Beyond Colliders study group and the work of CERN technical teams related to civil engineering studies (SCE-DOD), safety discussions (HSE-OHS, HSE-RP, EP-DI-SO), integration (EN-ACE), and discussions on services (EN-CV, EN-EL, EN-AA) and simulations (SY-STI). The work by J Alameddine, W Rhode, T Ruhe, and A Sandrock has been supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation), Collaborative Research Center SFB 876 and SFB 1491. L A Anchordoqui is supported by the US National Science Foundation (NSF) Grant PHY-2112527. T Araki is supported by JP18H01210. A Ariga is supported by JSPS KAKENHI Grant JP20K23373 and the European Research Council (ERC) under the European Union's Horizon 2020 Research and Innovation Programme (Grant 101002690). T Ariga acknowledges support from JSPS KAKENHI Grant JP19H01909. K Asai is supported by JSPS KAKENHI Grant JP19J13812 and JP21K20365. A Bacchetta and F G Celiberto acknowledge support from the INFN/NINPHA project. P Bakhti and M Rajaee are supported by the National Research Foundation of Korea (NRF-2020R1I1A3072747). B Barman received funding from the Patrimonio Autónomo—Fondo Nacional de Financiamiento para la Ciencia, la Tecnología y la Innovación Francisco José de Caldas (MinCiencias—Colombia) Grant 80740-465-2020 and the European Union's Horizon 2020 Research and Innovation Programme under the Marie Sklodowska-Curie Grant Agreement No. 860881-HIDDeN. The work of B Batell is supported by the US Department of Energy (DOE) Grant DE–SC0007914. The work of A Berlin, T J Hobbs, S Hoeche, and J G Morfín was supported by the Fermi National Accelerator Laboratory (Fermilab), a US DOE, Office of Science, HEP User Facility. Fermilab is managed by Fermi Research Alliance, LLC (FRA), acting under Contract DE-AC02-07CH11359. M Becker, E Copello and J Harz acknowledge support from the DFG Emmy Noether Grant HA 8555/1-1. E Copello acknowledges also support from the DFG Collaborative Research Centre 'Neutrinos and Dark Matter in Astro- and Particle Physics' (SFB 1258). E Bertuzzo acknowledges financial support from FAPESP Contracts 2015/25884-4 and 2019/15149-6 and is indebted to the Theoretical Particle Physics and Cosmology group at King's College London for hospitality. The work of J Bian and W Wu is supported in part by US DOE Grant DE-SC0009920 and Heising-Simons Foundation Grant 2022-3319. The work of A Boyarsky and M Ovchynnikov is supported by the ERC under the European Union's Horizon 2020 Research and Innovation Programme (GA 694896). A Carmona acknowledges funding from the European Union's Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie Grant Agreement No. 754446 and UGR Research and Knowledge Transfer Found—Athenea3i. A Carmona also acknowledges partial support by the Ministry of Science and Innovation and SRA (10.13039/501100011033) Grant PID2019-106087GB-C22 and by the Junta de Andalucía Grant A-FQM-472-UGR20. F G Celiberto thanks the Università degli Studi di Pavia for the warm hospitality. The work of G Chachamis was supported by the Fundação para a Ciência e a Tecnologia (Portugal) under Project CERN/FIS-PAR/0024/2019 and Contract 'Investigador auxiliar FCT—Individual Call/03216/2017'. The work of M Citron and D Stuart is supported by US DOE Grant DE-SC0011702. The work of L Darme is supported by the European Union's Horizon 2020 Research and Innovation Programme under the Marie Sklodowska-Curie Grant Agreement 101028626. P B Denton acknowledges support from the US DOE Grant Contract DE-SC0012704. The work of P S Bhupal Dev was supported in part by the US DOE Grant DE-SC0017987. The research activities of K R Dienes were supported in part by the US DOE Grant DE-FG02-13ER41976/DE-SC0009913 and also by the US NSF through its employee IR/D program. M V Diwan acknowledges support from the US DOE Grant Contract DE-SC0012704. Y Du and J H Yu are supported in part by National Key Research and Development Program of China Grant 2020YFC2201501, and the National Science Foundation of China (NSFC) under Grants 12022514, 11875003 and 12047503, and CAS Project for Young Scientists in Basic Research YSBR-006, and the Key Research Program of the CAS Grant XDPB15. The work of B Dutta and S Ghosh are supported in part by the US DOE Grant DE-SC0010813. The work of S Ghosh is also supported in part by National Research Foundation of Korea (NRF)'s Grants, Grant 6N021413. Y Farzan has received financial support from Saramadan Contract ISEF/M/400279 as well as from the European Union's Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie Grant Agreement 860881-HIDDeN. The work of J L Feng is supported in part by US NSF Grants PHY-1915005 and PHY-2111427, Simons Investigator Award #376204, Simons Foundation Grant 623683, and Heising-Simons Foundation Grants 2019-1179 and 2020-1840. M Fieg is supported in part by US NSF Grant PHY-1915005 and by NSF Graduate Research Fellowship Award DGE-1839285. A L Foguel is supported by FAPESP Contract 2020/00174-2. The work of P Foldenauer is supported by the UKRI Future Leaders Fellowship DARKMAP. The work of S Foroughi-Abari and A Ritz is supported in part by NSERC, Canada. The work of J-F Fortin is supported in part by NSERC, Canada. A Friedland is supported by the US DOE Grant DE-AC02-76SF00515. E Fuchs acknowledges support by the DFG Germany's Excellence Strategy—EXC-2123 'QuantumFrontiers'—390837967. M Fucilla, M M A Mohammed, and A Papa acknowledge support from the INFN/QFT@COLLIDERS project. A Garcia acknowledges support from the European Union's H2020-MSCA Grant Agreement 101025085. C A García Canal and S J Sciutto acknowledge support from CONICET and ANPCyT M V Garzelli acknowledges support the from German BMBF Contract 05H21GUCCA. V P Goncalves was partially financed by the Brazilian funding agencies CNPq, CAPES, FAPERGS and INCT-FNA (Process Number 464898/2014-5). S Goswami acknowledges the J C Bose Fellowship (JCB/2020/000011) of Science and Engineering Research Board of Department of Science and Technology, Government of India. The work of M Guzzi is supported by US NSF Grant PHY-2112025. L Harland-Lang thanks the Science and Technology Facilities Council (STFC) for support via Grant Award ST/L000377/1. The work of S P Harris is supported by the US DOE Grant DE-FG02-00ER41132 as well as the US NSF Grant PHY-1430152 (JINA Center for the Evolution of the Elements). J C Helo acknowledge support from Grant ANID FONDECYT-Chile 1201673 and ANID—Millennium Science Initiative Program ICN2019-044. The work of M Hirsch is supported by the Spanish Grants PID2020-113775GB-I00 (AEI/10.13039/501100011033) and PROMETEO/2018/165 (Generalitat Valenciana). The work of A Hryczuk and M Laletin is supported by the National Science Centre, Poland, research Grant 2018/31/D/ST2/00813. The research activities of F Huang are supported by the International Postdoctoral Exchange Fellowship Program and in part by US NSF Grant PHY-1915005. A Ismail is supported by NSERC (Reference Number 557763) and by US NSF Grant PHY-2014071. Y S Jeong acknowledges support from the National Research Foundation of Korea (NRF) grant funded by the Korea government through Ministry of Science and ICT Grant 2021R1A2C1009296. K Jodlowski and L Roszkowski are supported by the National Science Centre, Poland, research Grant 2015/18/A/ST2/00748. S R Klein is supported in part by the US NSF Grant PHY-1307472 and the US DOE Contract DE-AC-76SF00098. F Kling and P Quílez are supported by the DFG under Germany's Excellence Strategy—EXC 2121 Quantum Universe—390833306. P Ko is supported in part by KIAS Individual Grant PG021403 and by National Research Foundation of Korea (NRF) Grant NRF-2019R1A2C3005009. S Kulkarni is supported by the Austrian Science Fund Elise-Richter Grant V592-N27. The work of J Kumar is supported in part by US DOE Grant DE-SC0010504. J-L Kuo is supported by US NSF Theoretical Physics Program, Grant PHY-1915005. The work of C Le Roux and K Zapp is part of a project that has received funding from the ERC under the European Union's Horizon 2020 Research and Innovation Programme (Grant Agreement 803183, collectiveQCD). The work of H-S Lee was supported in part by the National Research Foundation of Korea (NRF-2021R1A2C2009718). S J Lee was supported by the Samsung Science and Technology Foundation. Ji Li is supported by the National Natural Science Foundation of China Grant 11905149. K-F Lyu and Z Liu are supported in part by the US DOE Grant DE-SC0022345. The work of R Maciula and A Szczurek was partially supported by the Polish National Science Centre under Grant 2018/31/B/ST2/03537. R Mammen Abraham and A Ismail acknowledge support from the US DOE Grant DE-SC0016013. M R Masouminia is supported by the UK Science and Technology Facilities Council (Grant ST/P001246/1). The work of J McFayden was supported by the Royal Society Fellowship Grant URF R1 201519. The work of O Mikulenko is supported by the NWO Physics Vrij Programme 'The Hidden Universe of Weakly Inter-acting Particles' with Project Number 680.92.18.03 (NWO Vrije Programma), which is (partly) financed by the Dutch Research Council (NWO). P Nadolsky and F Olness acknowledge support through US DOE Grant DE-SC0010129. E R Nocera thanks the STFC for support by the Grant Awards ST/P000630/1and ST/T000600/1. The work of N Okada is supported by the US DOE Grant DE-SC0012447. V Pandey acknowledges the support from US DOE Grant DE-SC0009824. The work of D Raut is supported by the US DOE Grant DE-SC0013880. P Reimitz acknowledges financial support from FAPESP Contract 2020/10004-7. M H Reno is supported in part by US DOE Grant DE-SC-0010113. The work of J Rojo is partly supported by the Dutch Research Council (NWO). L Roszkowski and S Trojanowski are supported by the grant 'AstroCeNT: Particle Astrophysics Science and Technology Centre' carried out within the International Research Agendas programme of the Foundation for Polish Science financed by the European Union under the European Regional Development Fund. S Trojanowski is also supported in part by the Polish Ministry of Science and Higher Education through its scholarship for young and outstanding scientists (Decision No. 1190/E-78/STYP/14/2019). S Trojanowski is also supported in part from the European Union's Horizon 2020 Research and Innovation Programme under Grant Agreement No. 952480 (DarkWave 24 project). I Sarcevic is supported by US DOE Grant DOE DE-SC-0009913. The work of L Shchutska is supported by the ERC under the European Union's Horizon 2020 Research and Innovation Programme (GA 758316). The work of T Shimomura is supported by JSPS KAKENHI Grants JP18H01210, JP18K03651, and MEXT KAKENHI Grant JP18H05543. The work of K Sinha is supported in part by US DOE Grant DE-SC0009956. The work of T Sjöstrand is supported by the Swedish Research Council, Contract 2016-05996. J T Sobczyk acknowledges support from NCN Grant UMO-2021/41/B/ST2/02778. D Soldin acknowledges support from the US NSF Grant PHY-1913607. H Song is supported by the International Postdoctoral Exchange Fellowship Program. Y Soreq is supported by grants from the NSF-BSF, BSF, the ISF and by the Azrieli foundation. A Stasto acknowledges support from US DOE Grant DE-SC-0002145. S Su is supported by the US DOE Grant DE-FG02-13ER41976/DE-SC0009913. W Su is supported by a KIAS Individual Grant (PG084201) at Korea Institute for Advanced Study. Y Takubo is supported by JP20K04004. M Taoso acknowledges support from the INFN Grant 'LINDARK', the research grant 'The Dark Universe: A Synergic Multimessenger Approach 2017X7X85' funded by MIUR, and the project 'Theoretical Astroparticle Physics (TAsP)' funded by the INFN. The research activities of B Thomas are supported in part by US NSF Grant PHY-2014104. The work of Y-D Tsai is supported in part by US NSF Grant PHY-1915005. The work of A Sabio Vera has been supported by the Spanish Research Agency (Agencia Estatal de Investigación) through the Grant IFT Centro de Excelencia Severo Ochoa SEV-2016-0597, by the Spanish Government Grant FPA2016-78022-P and from the European Union's Horizon 2020 Research and Innovation Programme under Grant Agreement 824093. The work of Yongchao Zhang is supported by the National Natural Science Foundation of China Grant 12175039, the 2021 Jiangsu Shuangchuang (Mass Innovation and Entrepreneurship) Talent Program JSSCBS20210144, and the 'Fundamental Research Funds for the Central Universities'. Yue Zhang is supported by the Arthur B McDonald Canadian Astroparticle Physics Research Institute. R Zukanovich Funchal is partially supported by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) and Conselho Nacional de Ciência e Tecnologia (CNPq). The opinions and conclusions expressed herein are those of the authors and do not represent any funding agencies., High energy collisions at the High-Luminosity Large Hadron Collider (LHC) produce a large number of particles along the beam collision axis, outside of the acceptance of existing LHC experiments. The proposed Forward Physics Facility (FPF), to be located several hundred meters from the ATLAS interaction point and shielded by concrete and rock, will host a suite of experiments to probe standard model (SM) processes and search for physics beyond the standard model (BSM). In this report, we review the status of the civil engineering plans and the experiments to explore the diverse physics signals that can be uniquely probed in the forward region. FPF experiments will be sensitive to a broad range of BSM physics through searches for new particle scattering or decay signatures and deviations from SM expectations in high statistics analyses with TeV neutrinos in this low-background environment. High statistics neutrino detection will also provide valuable data for fundamental topics in perturbative and non-perturbative QCD and in weak interactions. Experiments at the FPF will enable synergies between forward particle production at the LHC and astroparticle physics to be exploited. We report here on these physics topics, on infrastructure, detector, and simulation studies, and on future directions to realize the FPF's physics potential., German Research Foundation (DFG) SFB 876 SFB 1491, National Science Foundation (NSF) PHY2112527, Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research (KAKENHI) JP18H01210 JSPS KAKENHI JP20K23373 JP19H01909 JSPS KAKENHI JP19J13812 JP21K20365 JSPS KAKENHI JP18K03651, European Research Council (ERC) 101002690, National Research Foundation of Korea NRF-2020R1I1A3072747, Patrimonio Autónomo-Fondo Nacional de Financiamiento para la Ciencia Tecnología y la Innovación Francisco José de Caldas (MinCiencias-Colombia) 80740-465-2020, European Commission Joint Research Centre 860881-HIDDeN European Union's Horizon 2020 Research and Innovation Programme under the Marie Sklodowska-Curie Grant 754446, United States Department of Energy (DOE) DE-SC0007914, Fermi National Accelerator Laboratory (Fermilab), a US DOE, Office of Science, HEP User Facility, Fermi Research Alliance, LLC (FRA) DE-AC02-07CH11359, German Research Foundation (DFG) HA 8555/1-1, DFG Collaborative Research Centre 'Neutrinos and Dark Matter in Astro-and Particle Physics' SFB 1258, Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) 2015/25884-4 2019/15149-6, United States Department of Energy (DOE) DE-SC0009920, Heising-Simons Foundation 2022-3319 2019-1179 2020-1840, ERC under the European Union's Horizon 2020 Research and Innovation Programme 694896 803183, UGR Research and Knowledge Transfer Found-Athenea3i, Ministry of Science and Innovation, Spain (MICINN) Spanish Government, SRA Grant PID2019-106087GB-C22, Junta de Andalucía A-FQM-472-UGR20, Fundacao para a Ciencia e a Tecnologia (FCT) CERN/FIS-PAR/0024/2019 03216/2017, United States Department of Energy (DOE) DE-SC0011702 DE-SC0017987 DE-FG02-13ER41976/DE-SC0009913 DE-SC0012704 DE-SC0010813 DE-AC02-76SF00515 DE-FG02-00ER41132 DE-AC-76SF00098 DE-SC0010504 DE-SC0022345 DE-SC0010129, US NSF through its employee IR/D program, National Key Research and Development Program of China 2020YFC2201501, National Natural Science Foundation of China (NSFC) 12022514 11875003 12047503, CAS Project for Young Scientists in Basic Research YSBR-006, Key Research Program of the CAS XDPB15, National Research Foundation of Korea (NRF)'s Grants 6N021413, Saramadan Contract ISEF/M/400279, National Science Foundation (NSF) PHY-1915005 PHY-2111427 PHY1430152 PHY-2014071 PHY-1307472 PHY-2014104, Simons Investigator Award 376204, Simons Foundation 623683, National Science Foundation (NSF) DGE-1839285, FAPESP Contract 2020/00174-2, UKRI Future Leaders Fellowship DARKMAP, Natural Sciences and Engineering Research Council of Canada (NSERC), German Research Foundation (DFG) EXC-2123 390837967, INFN/QFT@COLLIDERS project, European Union's H2020-MSCA Grant Agreement 101025085, Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), ANPCyT, Federal Ministry of Education & Research (BMBF) 05H21GUCCA, Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPQ), Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES), Fundacao de Amparo a Ciencia e Tecnologia do Estado do Rio Grande do Sul (FAPERGS), INCT-FNA 464898/2014-5, J C Bose Fellowship of Science and Engineering Research Board of Department of Science and Technology, Government of India JCB/2020/000011, National Science Foundation (NSF) PHY-2112025, UK Research & Innovation (UKRI) Science & Technology Facilities Council (STFC) Science and Technology Development Fund (STDF) ST/L000377/1, Grant ANID FONDECYT-Chile 1201673, ANID-Millennium Science Initiative Program ICN2019-044, Spanish Grant (AEI) PID2020-113775GBI00, Center for Forestry Research & Experimentation (CIEF) PROMETEO/2018/165, National Science Centre, Poland 2018/31/D/ST2/00813, International Postdoctoral Exchange Fellowship Program, KIAS Individual Grant PG021403, National Research Foundation of Korea NRF-2019R1A2C3005009, Austrian Science Fund Elise-Richter Grant V592-N27, US NSF Theoretical Physics Program PHY-1915005, Samsung, National Natural Science Foundation of China (NSFC) 11905149, Polish National Science Centre 2018/31/B/ST2/03537, UK Research & Innovation (UKRI) Science & Technology Facilities Council (STFC) ST/P001246/1, Royal Society of London URF R1 201519, Netherlands Organization for Scientific Research (NWO) 680.92.18.03 Physics Vrij Programme .The Hidden Universe of Weakly Inter-acting Particles' - Dutch Research Council (NWO), UK Research & Innovation (UKRI) Science & Technology Facilities Council (STFC) ST/T000600/1 ST/P000630/1, Netherlands Organization for Scientific Research (NWO), European Union under the European Regional Development Fund, Polish Ministry of Science and Higher Education through its scholarship for young and outstanding scientists 1190/E-78/STYP/14/2019, European Commission 952480, ERC under the European Union 758316, Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research (KAKENHI) JP18H05543 MEXT KAKENHI, Swedish Research Council 2016-05996, NCN UMO-2021/41/B/ST2/02778, NSF-BSF, US-Israel Binational Science Foundation, Israel Science Foundation, Azrieli foundation, KIAS Individual Grant at Korea Institute for Advanced Study PG084201, Istituto Nazionale di Fisica Nucleare (INFN), Ministry of Education, Universities and Research (MIUR) 2017X7X85', Spanish Government SEV-2016-0597 Spanish Research Agency (Agencia Estatal de Investigacion) through the Grant IFT Centro de Excelencia Severo Ochoa FPA2016-78022-P, European Union's Horizon 2020 Research and Innovation Programme 824093, National Natural Science Foundation of China (NSFC) 12175039, 2021 Jiangsu Shuangchuang (Mass Innovation and Entrepreneurship) Talent Program JSSCBS20210144, Fundamental Research Funds for the Central Universities, Arthur B McDonald Canadian Astroparticle Physics Research Institute, Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP), United States Department of Energy (DOE) DE-SC0012447 DE-SC0009824 DE-SC0013880 :The US DOE DE-SC-0010113 DOE DE-SC-0009913 US DOE DE-SC0009956 DE-FG02-13ER41976/DESC0009913 US DOE JP20K04004

Following new findings in beam dynamics and the latest HL-LHC project decisions, an operational scenario has been developed for the first HL-LHC run, Run 4. This new scenario is presented in this document along with the motivations for the proposed changes and performance estimates.

A new scenario for the first operational run of the HL-LHC era (Run 4) has been recently developed to accommodate a period of performance ramp-up to achieve an annual integrated luminosity close to the nominal HL-LHC design. The operational scenario in terms of beam parameters and machine settings, as well as the different phases, are described here along with the impact of potential delays on key hardware components., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

After its second successful run period, the Large Hadron Collider (LHC) shut down for three years with the plan of being recommissioned in 2022 for a three-year physics production period, the Run 3. The future restart of the machine coincides with the completion of the LHC Injectors Upgrade (LIU) project, offering to the LHC the opportunity and the challenge to operate with up to two times higher beam brightness, pending the complete installation of the High-Luminosity LHC (HL-LHC), which should take place in Long Shutdown 3 (LS3). In this context, Run 3 is clearly a transition between the LHC and the HL-LHC, with key ingredients which will be made available, either gradually (LIU beam) or immediately (ATS optics). Run 3 shall therefore be exploited not only for performance, but also as a full scale demonstrator of the HL-LHC in terms of beams, optics and beam manipulation (e.g. β∗ levelling over a very large dynamic range). To this aim, the so-called LHC configuration, namely the optics, needs to be adapted in order to cope or mitigate constraints of different nature, from beam brightness limitations due to the machine impedance, to specific desiderata of some LHC experiments. After reviewing these constraints, including the intensity limitations coming from the existing hardware, the beam parameters targeted for the LHC in Run 3 are given. A possible solution for the machine configuration will then be described, and analyzed from various perspectives, which should not limit the machine performance over the full Run 3, and should enable to double the integrated luminosity delivered so far to the two high luminosity insertions of the LHC.

The main aspects linked to Landau damping of head-tail instabilities at top energy in the HL-LHC are discussed, in particular the interplay between the arc octupoles and long-range, offset or head-on beam-beam interactions as well as lattice imperfections. When possible, the models are compared with the operational experience of Runs 1 and 2 of the LHC. Based on these considerations, various operational scenarios are discussed identifying their strengths and limitations.

This MD allowed confirming that the solenoid installed in 16L2 during Technical Stop 2 (TS22017) could be held responsible for the performance improvement observed after TS2. The MD was performed on 30th November 2017 in parallel with MD#2889 and the procedure was adjusted for both MDs to profit as much as possible of the available time.

Electron cloud (e-cloud) effects are among the main performance limitations for the operation of the Large Hadron Collider (LHC) with 25 ns bunch spacing. A large number of electrons impacting on the beam-screens of the superconducting magnets induces significant heat load, reaching values close to the full cooling capacity available from the cryogenic system. A number of Machine Development (MD) sessions in 2018 was dedicated to characterizing the heat load as a function of beam and machine parameters, investigating in particular its distribution along the ring and its dependence on the filling pattern, bunch population and bunch length. The main results of these measurements have been compared against simulations performed with the PyECLOUD code in order to validate the underlying model.

Since the beginning of the LHC commissioning, harmonics of 50 Hz have been observed in the beam spectrum. Several observations during the 2018 proton run show that these harmonics are the result of a real beam excitation, rather than an artifact of the instrumentation system. As many of these components reside in the vicinity of the betatron tune, their presence can complicate the tune measurement and tracking during operation and potentially lead to beam losses and emittance growth. This note summarizes the program of the first LHC Machine Development (MD) (Fills 7342 and 7343) dedicated to the investigation of this effect. The aim of this study is to reproduce some of the observations acquired during End-of-Fill experiments and parasitic observations, as well as to simulate the impact of dipolar noise on the beam with controlled ADT excitations.

The Beams Department hosts the Groups responsible for the beam generation, acceleration, diagnostics, controls and performance optimization for the whole CERN accelerator complex. This Report describes the 2018 highlights for the BE Department.

his note summarizes the program of the LHC Machine Development to assess the potential and limits of the long-range beam-beam compensators held in 2017 (MD2202). Two compensator prototypes were installed in the machine during the EYETS16-17 and the first evidence of compensation were observed during the MD block 1 (FILLS 5898 and 5900, 9 h assigned on 1st July 2017).This study was also scheduled for the MD block 3 but could not be performed due to the machine unavailability (9 h assigned, 2 h available but unfortunately not exploitable for measurements). In MD block 4 an additional slot was scheduled (FILLS 6434 and 6435, 10 h on 29th November 2017)

Since the publication of the document providing the specifications of the new circuits of the HL-LHC (see CERN-ACC-2017-0101), using criteria based on beam dynamics considerations, more accurate performance expectations of the power converter technology have been made available. Moreover, cost optimisation and technological considerations on the initially-proposed choices made it necessary a review of the previous document together with some clarifications of some details of the previous analysis. The impact on beam parameters of the newly-proposed solutions and new power converter specifications is carried out in this document, and a summary of the new choices is presented.

This report discusses the feasibility and limitations for operating the LHC and HL-LHC at the ultimate beam energy of 7.5 TeV, corresponding to a main dipole magnetic field of 8.93 T and an operating current of 12748 A.

At the CERN accelerator complex, it seems that only the highest energy machine in the sequence, the LHC, with space charge (SC) parameter close to one, sees the predicted beneficial effect of SC on transverse coherent instabilities. In the other circular machines of the LHC injector chain (PSB, PS and SPS), where the SC parameter is much bigger than one, SC does not seem to play a major (stabilising) role, and it is maybe the opposite in the SPS. All the measurements and simulations performed so far in both the SPS and LHC will be reviewed and analysed in detail., Proceedings of the 13th Int. Computational Accelerator Physics Conf., ICAP2018, Key West, FL, USA

The Beams Department hosts the Groups responsible for the beam generation, acceleration, diagnostics, controls and performance optimization for the whole CERN accelerator complex. This Report describes the 2017 highlights for the BE Department.

The Search for Hidden Particles (SHiP) experiment aims at acquiring a total of 4e19 protons on target (PoT) per year. Based on demonstrated Super Proton Synchrotron (SPS) performance for CERN Neutrinos to Gran Sasso (CNGS), the 2018 SPS performance and recent high-intensity test results, the expected proton sharing between the TCC2 targets and SHiP is estimated. AWAKE and HiRadMat are taken into account in the future supercycle composition while the maximum possible power dissipation is respected. Limitations from activation of the SPS extraction channel are also addressed. Furthermore, future operational scenarios with long spills to the TCC2 targets are discussed.

Transverse feedback systems are one of the crucial and fundamental devices needed in high brightness proton synchrotrons to ensure a reliable and stable operation. They are used to lock the beam to the reference orbit during injection transient, and also while it is circulating, and thus secure the maintenance of a high beam quality. In particular, the latter use has been important for many of the machines at CERN to prevent single and coupled bunch instabilities from being triggered by impedances or electron clouds. Present systems at CERN are bandwidth limited to 20 MHz at max and are therefore unsuited to be used against the full spectrum of instabilities encountered at the CERN synchrotrons. This report will discuss the ongoing efforts in the R&D of a new class of transverse feedback systems with a widely enlarged bandwidth that should be able to cope with all types of instabilities up to frequencies of several GHz.

Alternative scenarios for using different configurations of RF frequencies exist and are under study for the HL-LHC. One particular scenario considers the use of a 200 MHz fundamental system which may have advantages over the standard 400 MHz used in the LHC today. In particular, in terms of heat load generated by electron clouds, this approach appears to provide significant advantages with relaxed requirements on the necessary cooling capacity. One of the main concerns with this scenario, on the other hand, is the lowering of the transverse mode coupling instability (TMCI) which puts a hard limit on the reachable intensity. In this note we focus on the evaluation of the TMCI thresholds for the different scenarios and give some guidelines on what configurations are tolerable from a transverse stability point of view. We also briefly address the impact of an idealized transverse damper on the TMCI thresholds.

Presently, the LHCb experiment at IP8 operates at reduced luminosity (~4.0 1032 cm-2 s-1) compared to ATLAS and CMS experiments. The LHCb collaboration is proposing an Upgrade II during HL-LHC operation, where the beams at IP8 will collide at high-luminosity (~1-2 1034 cm-2 s-1), comparable to the present high-luminosity regions IP1&IP5. The LHCb experiment aims to collect more than 300 fb-1 by the end of the HL-LHC operation. A feasibility study of operating IP8 at high-luminosity whilst preserving the performance at IP1 and IP5 and on the impact to the LHC machine and experimental cavern was done. Optics studies shows that solutions allowing to reach an integrated luminosity of 40 to 50 fb-1 per year to LHCb/IP8 at the cost of a reduction of about 5% in the integrated luminosity of the main experiments ATLAS and CMS, under the assumption that there are no lifetime limitations besides burn-off, are feasible. Energy deposition in the machine elements of the IR straight section 8 and LHC infrastructure and possible mitigation options were evaluated, revealing the challenges involved but also showing possible mitigation solutions. This is a first study with preliminary findings on the key aspects of operating LHCb at high-luminosity. In addition, aspects like beam-beam effects that could have an impact on the beam lifetime and on the overall estimates of the integrated luminosities for LHCb and ATLAS and CMS need to be further studied.

Recurrent beam dumps significantly perturbed the operation of the CERN LHC in the summer months of 2017, especially in August. These unexpected beam dumps were triggered by fast beam losses that built up in the cryogenic beam vacuum at the half-cell 16 left of LHC-IP2 and were detected either at that location but mainly in the collimation insertions. This contribution details the experimental observables (beam losses, coherent instabilities, heat load to cryogenic system, vacuum signals), the extent of the understanding of the beam loss and instability mechanisms and the mitigation steps and new settings that allowed recovering the luminosity performance of the LHC for the rest of the Run., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

PERLE (Powerful ERL for Experiments) is a novel ERL test facility, initially proposed to validate choices for a 60 GeV ERL foreseen in the design of the LHeC and the FCC-eh. Its main thrust is to probe high current, CW, multi-pass operation with superconducting cavities at 802 MHz (and perhaps testing other frequencies of interest). With very high virtual beam power (~ 10 MW), PERLE offers an opportunity for controllable study of every beam dynamic effect of interest in the next generation of ERL design; becoming a ‘stepping stone' between present state-of-art 1 MW ERLs and future 100 MW scale applications. PERLE design features Flexible Momentum Compaction lattice architecture for six vertically stacked return arcs and a high-current, 6 MeV, photo-injector. With only one pair of 4 cavity cryomodules, 400 MeV beam energy can be reached in 3 re-circulation passes, with beam currents in excess of 15 mA. The beam is decelerated in 3 consecutive passes back to the injection energy, transferring virtually stored energy back to the RF. This unique facility will serve as a test-bed for high current ERL technologies, as well as a user facility in low energy electron and photon physics., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

The High-Luminosity LHC (HL-LHC) experiments will operate at unprecedented level of event pile-up from proton-proton collisions at 14TeV center-of-mass energy. In this paper we study the performance of the baseline and a series of alternative scenarios in terms of the delivered integrated luminosity and its quality (pile-up density). A new figure-of-merit is introduced, the effective pile-up density, a concept that reflects the expected detector efficiency in the reconstruction of event vertices for a given operational scenario, acting as a link between the machine and experimental slides. Alternative scenarios have been proposed either to improve the baseline performance, or tot provide operational schemes in the case of particular limitations. Simulations of the evolution of optimum fills with the latest set of parameters of the HL-LHC are performed with β* - levelling, and results are discussed in terms of both the integrated luminosity and the effective pile-up density. The crab kissing scheme, a proposed scenario for pile-up density control, in re-evaluated under this new perspective, with updated beam and optics parameters. Estimations on the impact of crab cavity noise, full crab crossing, or reduced cross section section for burn-off, on the expected integrated luminosity are also presented.

The main aim of this document is to have a clearly identified set of beam and machine parameters to be used for numerical simulations and performance assessment. Two scenarios (referring only to the operation at the nominal beam energy of 7 TeV) are discussed: i) Nominal scenario (levelling at a luminosity of 5E34 cm-2s-1) ii) Ultimate scenario (levelling at a luminosity of 7.5E34 cm-2s-1)

The LHC machine is envisioned to operate eventually at an ultimate beam energy of 7.5 TeV at the end of LHC Run 4, i.e. after commissioning of the HL-LHC systems, a stage falling into the High Luminosity LHC (HL-LHC) era. In this paper we review the latest baseline parameters and performance, and study the potential reach of the HL-LHC with pushed optics at the ultimate beam energy. Results in terms of integrated luminosity and effective pile-up density of both the nominal (5.0×10³⁴ cm⁻² s^{−1}) and ultimate (7.5×10³⁴ cm⁻² s^{−1}) levelling operations are discussed, Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

The operation during the summer months of the 2017 Run of the CERN LHC was plagued with fast beam losses that repeatedly occurred in the 16th arc half-cell at the left of IP2 as well as in the collimation insertion, leading to unwanted beam dumps. Transverse coherent oscillations were observed during this fast process. We detail here the experimental observations of coherent motion that al-lowed shedding light upon parts of the mechanism and identify the potential mitigations that were successfully implemented in the second half of the Run., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

The Beams Department hosts the Groups responsible for the beam generation, acceleration, diagnostics, controls and performance optimization for the whole CERN accelerator complex. This Report describes the 2016 highlights for the BE Department.

A certain number of LHC magnets and relative electrical circuits will be replaced for the HL-LHC upgrade. The performance of the new circuits will need to be compatible with the current installation, and to provide the necessary improvements to meet the tight requirements of the new operational scenario. This document summarises the present knowledge of the performance and use of the LHC circuits and, based on this and on the new optics requirements, provides the necessary specifications for the new HL-LHC electrical circuits.

This is the first report of a three volume study on the full energy exploitation of the LHC. The report summaries the necessary preparations and consolidation work and the potential performance reach for operating the LHC at its nominal beam energy of 7TeV.

In this note the half-day internal review of LHC performance limitations (linked to transverse collective effects) during run II (2015-2016), which took place at CERN on 29/11/2016 (https://indico.cern.ch/event/589625/), is summarised and the next steps are discussed.

The proposed SPS beam dump facility (BDF) is a fixed-target facility foreseen to be situated at the North Area of the SPS. Beam dump in this context implies a target aimed at absorbing the majority of incident protons and containing most of the cascade generated by the primary beam interaction. The aim is a general purpose fixed target facility, which in the initial phase is aimed at the Search for Hidden Particles (SHiP) experiment. Feasibility studies are ongoing at CERN to address the key challenges of the facility. These challenges include: slow resonant extraction from the SPS; a target that has the two-fold objective of producing charged mesons as well as stopping the primary proton beam; and radiation protection considerations related to primary proton beam with a power of around 355 kW. The aim of the project is to complete the key technical feasibility studies in time for the European Strategy for Particle Physics (ESPP) update foreseen in 2020. This is in conjunction with the recommendation by the CERN Research Board to the SHiP experiment to prepare a comprehensive design study as input to the ESPP., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

A local Crab Cavity (CC) scheme will recover head-on collisions at the Interaction Points (IPs) of the High Luminosity LHC (HL-LHC), which aims to increase the LHC luminosity by a factor of 3-10. The first time that CC will ever be tested with proton beams will be in 2018 in the SPS machine. The available dedicated Machine Development (MD) time after the installation of the cavities will be limited and therefore good preparation is essential in order to ensure that the MDs are as efficient as possible. This paper presents the simulations and experimental studies performed in preparation for the future MDs and discusses the next steps., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

Studies on luminous region and pile-up density are of great interest for the experiments at the future High Luminosity LHC (HL-LHC) in order to optimize the detector performance. The evolution of these parameters at the two main interaction points of the HL-LHC along optimum physics fills is studied for the baseline and alternative operational scenarios with the latest set of parameters, including a refined description of the longitudinal bunch profile. Results are discussed in terms of a new figure-of-merit, the effective pile-up density., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

The Beams Department hosts the Groups responsible for the beam generation, acceleration, diagnostics, controls and performance optimization for the whole CERN accelerator complex. This Report describes the 2015 highlights for the BE Department.

Since the first transverse instability observed in 2010, many studies have been performed on both measurement and simulation sides and several lessons have been learned. In a machine like the LHC, not only all the mechanisms have to be understood separately, but the possible interplays between the different phenomena need to be analyzed in detail, including the beam-coupling impedance (with in particular all the necessary collimators to protect the machine but also new equipment such as crab cavities for HL-LHC), linear and nonlinear chromaticity, Landau octupoles (and other intrinsic nonlinearities), transverse damper, space charge, beam-beam (long-range and head-on), electron cloud, linear coupling strength, tune separation between the transverse planes, tune split between the two beams, transverse beam separation between the two beams, etc. This paper reviews all the transverse beam instabilities observed and simulated so far, the mitigation measures which have been put in place, the remaining questions and challenges and some recommendations for the future., Proceedings of the 57th ICFA Advanced Beam Dynamics Workshop on High-Intensity and High-Brightness Hadron Beams, HB2016, Malmö, Sweden

High luminosity LHC upgrade will improve the luminosity of the current LHC operation by an order of magnitude. Crab cavity as a critical component for compensating luminosity loss from large crossing angle collision and also providing luminosity leveling for the LHC upgrade is being actively pursued. In this paper, we will report on the study of potential effects of the frequence-dependent crab cavity noise on the beam luminosity lifetime using strong-strong beam-beam simulations., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea