BEAM-INDUCED BACKGROUND AND DETECTOR CONFIGURATION

MuCol Consortium, 2025 Grant Agreement 101094300 PUBLIC 1 / 23 Grant Agreement No: 101094300 MuCoL A Design Study for a Muon Collider complex at 10 TeV centre of mass Horizon Europe Framework Programme DELIVERABLE REPORT BEAM-INDUCED BACKGROUND AND DETECTOR CONFIGURATION DELIVERABLE: D2.1 Document identifier: MuCol_D2.1_final.pdf DOI: 10.5281/zenodo.17494967 Due date of milestone: 31/10/2025 (End of Month) Justification for delay: N/A Work package: WP2: Physics and Detectors Requirements Lead beneficiary: WP2 Report release date: 31/10/2025 Document version: 0.1 Document status: Final BEAM-INDUCED BACKGROUND AND DETECTOR CONFIGURATION Deliverable: D2.1 Date: 31/10/2025 Grant Agreement 101094300 PUBLIC 2 / 23 Abstract: This document provides a description of the background data samples prepared for a 10 TeV Muon Collider within the framework of the International Muon Collider Collaboration. The data files are available in the same Zenodo document as this report. The simulations, performed with the FLUKA.CERN Monte Carlo code, include the main background sources arising from muon decays and incoherent electron–positron pair production. The implemented model comprises the interaction region optics, final-focus magnets, detector solenoid, and forward shielding. The document defines the structure, normalization, and intended use of the produced datasets to support subsequent detector simulation and performance studies. Two detector concepts specifically designed for muon collisions at a center-of-mass energy of 10 TeV, MUSIC and MAIA, are presented with a description of their individual components. In addition, the associated software repositories are made available, including instructions for installation and use. A parametric model of the MUSIC detector is also provided in the form of a DELPHES card, allowing users to reproduce the detector’s expected response. MuCol Consortium, 2025 For more information on MuCol, its partners and contributors please see https://mucol.web.cern.ch/ Funded by the European Union (EU). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the EU or European Research Executive Agency (REA). Neither the EU nor the REA can be held responsible for them. Delivery Slip Name Partner Date Authored by D. Calzolari, M. Casarsa, A. Lechner, D. Lucchesi, F. Meloni, M. Vanwelde CERN, UNIPD, DESY 20/10/25 Edited by A. Lechner, D. Lucchesi CERN, UNIPD 22/10/25 Reviewed by D. Schulte, R. Losito CERN 30/10/25 Approved by MuCol Management Committee 30/10/25 BEAM-INDUCED BACKGROUND AND DETECTOR CONFIGURATION Deliverable: D2.1 Date: 31/10/2025 Grant Agreement 101094300 PUBLIC 3 / 23 TABLE OF CONTENTS 1. INTRODUCTION.......................................................................................................................................... 4 2. DETECTOR CONFIGURATION ............................................................................................................... 6 2.1 THE MUSIC DETECTOR CONCEPT ............................................................................................................................. 6 2.1.1. The tracking system .................................................................................................................................... 6 2.1.2. Calorimeters ............................................................................................................................................... 7 2.1.3. Muon system ............................................................................................................................................... 7 2.2. THE MAIA DETECTOR CONCEPT ..................................................................................................................... 7 2.2.1. The tracking system .................................................................................................................................... 8 2.2.2. Calorimeters ............................................................................................................................................... 8 2.2.3. Muon system ............................................................................................................................................... 9 2.3. DETECTOR SIMULATION AND RECONSTRUCTION SOFTWARE .................................................................................... 9 2.3.1. Parametric simulation ................................................................................................................................ 9 3. INTERACTION REGION LAYOUT AND OPTICS .............................................................................. 10 4. NOZZLE DESCRIPTION .......................................................................................................................... 12 5. DECAY INDUCED BACKGROUND ........................................................................................................ 14 5.1. GENERATION OF MUON DECAYS ............................................................................................................................ 14 5.2. RESULTS ................................................................................................................................................................ 15 6. INCOHERENT PAIR PRODUCTION BACKGROUND ....................................................................... 18 7. APPENDIX: USEFUL CODE .................................................................................................................... 19 8. CONCLUSION ............................................................................................................................................ 21 9. REFERENCES ............................................................................................................................................. 22 ANNEX: GLOSSARY ......................................................................................................................................... 23 BEAM-INDUCED BACKGROUND AND DETECTOR CONFIGURATION Deliverable: D2.1 Date: 31/10/2025 Grant Agreement 101094300 PUBLIC 4 / 23 Executive summary This document summarizes the detector configuration as well as the machine-induced background datasets for a 10 TeV centre-of-mass Muon Collider, prepared within the International Muon Collider Collaboration under the Horizon Europe MuCol project (WP2 — Physics and Detector Requirements). The study is based on the latest interaction region optics (lattice version 0.8) including the final-focus triplet, dipole chicane, detector solenoid, and tungsten–polyethylene nozzle shielding. The main background sources considered are muon decays and incoherent electron–positron pair production, simulated with the FLUKA.CERN and GUINEA-PIG codes, respectively. The resulting datasets provide normalized particle lists for detector simulation and performance studies. The results confirm that photons, neutrons, electrons and positrons dominate the background, with time and spatial distributions validating the shielding and optics design. These samples serve as a common reference for future optimisation of the machine–detector interface and detector layouts in the MuCol framework. 1. INTRODUCTION This document describes the detector configuration as well as the background data samples for a √s = 10 TeV Muon Collider with two counter-rotating muon bunches (1.8×10¹² μ/bunch) of opposite charge. The background studies were carried out by the International Muon Collider Collaboration within the scope of the ESPPU process 2026. The document presents two of the main background sources (muon decay and incoherent electron–positron pair production). The background was simulated with the FLUKA.CERN Monte Carlo code [1, 2], using code version 4.4.1. The simulation model, including final focus magnets, shielding, detector, and solenoid, is illustrated in Figure 1. The incoherent pairs were generated with an external event generator (GuineaPig) and were then tracked within the FLUKA model. This document summarizes the underlying interaction region (IR) optics and geometry model, in particular the nozzle-like shielding in the forward region, and provides a brief description of the background datasets. In particular, the data format of the data samples and the normalization constants are described such that the data can be used for detector simulations. BEAM-INDUCED BACKGROUND AND DETECTOR CONFIGURATION Deliverable: D2.1 Date: 31/10/2025 Grant Agreement 101094300 PUBLIC 5 / 23 Figure 1: Model of the Muon Collider Machine-Detector Interface and Interaction Region. Figure 2: y-z view of the MUSIC detector. BEAM-INDUCED BACKGROUND AND DETECTOR CONFIGURATION Deliverable: D2.1 Date: 31/10/2025 Grant Agreement 101094300 PUBLIC 6 / 23 2. DETECTOR CONFIGURATION Two detector configurations are proposed to collect data and study 10 TeV center-of-mass collisions: MUSIC (MUon System for Interesting Collisions) and MAIA (Muon Accelerator Instrumented Apparatus). Both detector designs have been optimised to minimise the impact of the machineinduced backgrounds while at the same time maintaining high efficiency and accuracy for physics measurements exploiting both lowand high-momentum reconstructed objects. They share a similar structure, conventional of multipurpose collider experiments, with a cylindrical layout consisting of an innermost tracking system, a set of electromagnetic and hadron calorimeters, a muon system and a solenoidal magnet. Both detector concepts assume a magnetic field of 5 T. The field intensity was chosen to minimise the effects of the incoherent e+e− pair production on the tracking system. A right-handed reference system is used with the origin at the center of the detectors, the nominal collision point: the z-axis is aligned with the direction of the clockwise-circulating μ+ beam, the y axis points upward, and the x axis lies on the plane of the collider ring. 2.1 THE MUSIC DETECTOR CONCEPT The MUSIC detector concept, illustrated in Figure 2, has a length of 11.4 m and a diameter of 12.8 m. Beginning with the innermost region, the detector features an all-silicon tracking system, followed by a calorimetric system composed of electromagnetic and hadronic subdetectors, and finally a muon detection system. A superconducting solenoid is placed between the electromagnetic and the hadronic calorimeters. 2.1.1. The tracking system The tracking system’s configuration and geometry have been optimized to maximize acceptance and provide redundant measurements that help to minimize background effects. The tracking system consists of three sub-detectors: Vertex Detector: It is the innermost system, consisting of five cylindrical barrel layers, each 26 cm long, positioned at radii ranging from 2.9 cm to 10.1 cm from the beam axis. The forward and backward regions feature four endcap disks, oriented transverse to the beamline and located at distances of |z| = 18 to 36.6 cm from the interaction point. A layout of 25 × 25 μm2 pixels is assumed with a hit spatial resolution of 5 μm × 5 μm and a hit time resolution of 30 ps. Inner Tracker: It consists of 50 μm × 1 mm macropixel modules arranged in three barrel layers, at radii from 16.4 to 55.4 cm, and seven disks on either side at |z| from 60.4 to 219 cm. The first two barrel layers are 96.32 cm long, while the third measures 138.46 cm. Hit spatial and time resolutions of 7 μm × 90 μm and 60 ps are assumed, respectively. Outer Tracker: It has three 252.8-cm long barrel layers at radii between 81.9 and 148.6 cm and four endcap disks at |z| from 141 to 219 cm. It features 50 μm × 1 mm macropixel with a hit spatial resolution of 7 μm × 90 μm and a hit time resolution of 60 ps. BEAM-INDUCED BACKGROUND AND DETECTOR CONFIGURATION Deliverable: D2.1 Date: 31/10/2025 Grant Agreement 101094300 PUBLIC 7 / 23 2.1.2. Calorimeters The MUSIC detector comprises an electromagnetic calorimeter and a hadronic calorimeter. The electromagnetic calorimeter is specifically designed for muon collisions, while the hadronic calorimeter is adapted from the CLIC Collaboration detector at √s = 3 TeV [3]. Electromagnetic calorimeter (ECAL): The ECAL is a semi-homogeneous electromagnetic crystal calorimeter with longitudinal segmentation (CRILIN). It consists of 1 × 1 × 4-cm3 lead-fluorite crystals arranged in six layers for a total of 26.5 radiation lengths. The cylindrical barrel section has an inner radius of 169 cm and is 442 cm long. The endcaps, shaped as disks, have inner and outer radii of 31 cm and 196 cm, respectively, and are positioned at |z| = 230.7 cm. Hadronic calorimeter (HCAL): The HCAL is an iron-scintillator sampling calorimeter composed of 70 layers of 2-cm iron absorbers and 3 × 3 cm2 scintillator pads, totaling approximately seven nuclear interaction lengths. It consists of a central cylindrical part measuring 501.8 cm in length and 290.2 cm in radius, along with two endcaps positioned at |z| = 257.9 cm. The endcaps have inner and outer radii of 32 cm and 475.6 cm, respectively. Positioned outside the superconducting solenoid, the HCAL iron absorber also functions as a return yoke for the magnetic field flux. 2.1.3. Muon system The final technology for the muon detectors has not yet been selected. The current detector is modeled on the resistive-plate chambers (RPC) employed in the CLIC detector [3]. It features seven-barrel layers, each measuring 888.8 cm in length, with radii ranging from 480.6 cm to 680 cm, and six endcap layers at |z| positions between 444.4 cm and 590 cm, with inner and outer radii of 49.3 cm and 680 cm, respectively. The RPCs are segmented into 3 × 3 cm2 cells and a hit time resolution of 100 ps is assumed. 2.2. THE MAIA DETECTOR CONCEPT The MAIA detector concept, illustrated in Figure 3, was conceived for the highest possible hermiticity given the constraints of the shielding nozzles described above. It has an overall length of 12 m and a diameter of 14 m. The detector is designed to be approximately azimuthally symmetric with varying n-fold symmetries across the subdetectors. Full azimuthal coverage is assumed. The detector features an all-silicon tracking system, a silicon-tungsten electromagnetic sampling calorimeter, an ironplastic scintillator hadronic sampling calorimeter, and an RPC-based muon detection system. A thin superconducting solenoid is placed between the tracking system and the electromagnetic calorimeter. BEAM-INDUCED BACKGROUND AND DETECTOR CONFIGURATION Deliverable: D2.1 Date: 31/10/2025 Grant Agreement 101094300 PUBLIC 8 / 23 Figure 3: 3D model of the MAIA detector concept. 2.2.1. The tracking system The occupancy and time structure of beam-induced background (BIB) particles motivate a high granularity detector with precision timing in every layer. The conceptual tracker design comprises two silicon subdetectors: the vertex detector, a high-resolution pixel detector closest to the collision point and the inner tracker, a macro-pixel detector. Vertex Detector: It consists of four cylindrical barrel layers, each 13 cm long, positioned at radii ranging from 3.0 cm to 10.4 cm from the beam axis. The first layer is equipped with sensitive detectors on its two sides, making it a “double layer”. The forward and backward regions feature four double-layer endcap disks, oriented transverse to the beamline and located at distances of |z| = 8 to 28.2 cm from the interaction point. Pixel detectors with 25 × 25 μm2 granularity and a hit time resolution of 30 ps are required to achieve a desired occupancy of 1%. Inner Tracker: It consists of 50 μm × 1 mm macropixel modules arranged in six barrel layers, at radii from 12.7 to 143.0 cm, and eleven disks on either side at |z| from 48.2 to 219 cm. The first two barrel layers are 96.32 cm long, the third measures 138.46 cm, while the subsequent layers have a length of 252.8 cm. Hit spatial and time resolutions of 7 μm × 90 μm and 60 ps are assumed, respectively. 2.2.2. Calorimeters The MAIA detector concept makes use of a silicon-tungsten electromagnetic calorimeter and an ironscintillator hadronic calorimeter. Both systems are based on the CLIC calorimeter design [3], which was also the starting point for earlier iterations of a muon collider detector optimized for √s = 3 TeV. Compared to the calorimeters optimized for lower energy, this detector concept has more layers, and each layer has a slightly thicker absorber. The cells have also been slightly scaled up in size. The presence of the solenoid material in front of the electromagnetic calorimeter reduces the incoming BIB particle flux. The solenoid adds approximately 4 X0 and 1 λ for a particle crossing the material in the transverse direction, and reduces the incoming BIB flux by a factor of 10. BEAM-INDUCED BACKGROUND AND DETECTOR CONFIGURATION Deliverable: D2.1 Date: 31/10/2025 Grant Agreement 101094300 PUBLIC 9 / 23 Electromagnetic calorimeter: It consists of a dodecagonal barrel and two endcap systems. The technical specifications of the ECAL’s silicon are similar to that of the CMS high granularity calorimeter, currently under construction for the High-Luminosity LHC upgrade. It is composed of 50 layers of Tungsten as absorber material 2.2 mm thick intertwined with Si sensors as active material with 5 × 5 mm2 silicon detector cells. It is located outside of the superconducting solenoid, at a radius of 185.7 cm. Hadron calorimeter: It consists of an iron-scintillator sampling calorimeter composed of 75 layers of 2 cm-thick iron absorbers and 3 × 3 cm2 scintillator pads. The MAIA HCAL is similar in design to the ATLAS Tile Calorimeter, albeit with smaller cells by roughly a factor of 10 in each direction, and a timing resolution is roughly 1 ns. It consists of a central barrel section measuring 515 cm in length and 257.5 cm in radius, along with two endcaps positioned at |z| = 257.5 cm. The iron absorber serves as a return yoke for the magnetic field flux. 2.2.3. Muon system The lack of a magnetic field relegates the muon system to the role of particle identification. The layout and baseline technology of the muon system are kept the same as used in the 3 TeV detector, although with increased dimensions to fit the volume of the other subsystems. The detector employs resistive-plate chambers. It features four barrel layers, with radii ranging from 415.6 cm to 715 cm, and six endcap layers at |z| positions between 456.5 cm and 602.5 cm, with inner and outer radii of 44.6 cm and 715 cm, respectively. The RPCs are segmented into 3 × 3 cm2 cells and a hit time resolution of 100 ps is assumed. 2.3. DETECTOR SIMULATION AND RECONSTRUCTION SOFTWARE Both detector concepts are fully integrated in the key4hep software stack. Compact dd4hep detector models, for simulation with the GEANT4 program are available on github at https://github.com/key4hep/k4geo. The software used for the digitisation of the detector response, as well as for the reconstruction of the collision events is also part of the key4hep software stack, with muon collider-specific additions made publicly available under the https://github.com/MuonColliderSoft organisation. Software releases are routinely built and distributed via docker registries (https://github.com/orgs/MuonColliderSoft/packages?repo_name=mucoll-spack) and via the CERN cvmfs distributed file system. Information on the software releases and tutorials on the MuonColliderSoft framework are available at: https://mcd-wiki.web.cern.ch 2.3.1. Parametric simulation A DELPHES card for the MUSIC detector is publicly available at: https://github.com/MuonColliderSoft/Delphes/tree/main/cardswitrh with usage instructions hosted on Zenodo, at this link https://zenodo.org/records/14001529. The present release models tracks, BEAM-INDUCED BACKGROUND AND DETECTOR CONFIGURATION Deliverable: D2.1 Date: 31/10/2025 Grant Agreement 101094300 PUBLIC 16 / 23 As described in the previous section, the decay simulations have been subdivided into N₍cycles₎, each one simulating 200 decays. For each cycle, a separate file containing the background particle list is produced. The naming pattern of the files is: summary***_DET_IP.dat, where the *** contains the cycle number. All the following results will refer to the μ⁺ beam going from left to right, corresponding to a movement from negative to positive z coordinates. The decay background from the negative muon beam will have a specular contribution with the same characteristics because the electromagnetic showers exhibit a similar behaviour, regardless of whether the initiating particle is an electron or a positron. Particle type Particles entering detector Threshold Photons 1.0 × 10⁸ 100 keV Neutrons 1.1 × 10⁸ 0.01 meV Electrons/positrons 1.2 × 10⁶ 100 keV Muons 1.1 × 10⁴ 100 keV Charged hadrons 4.0 × 10⁴ 100 keV Table 6: Particle types and thresholds for decay-induced background particles entering the detector. The total background particle multiplicity per bunch crossing at nominal intensity is reported in Table 6. Photons and neutrons represent the predominant particle species in the dataset. The background particle multiplicity as a function of the position of the muon decay is reported in Figure 7. The drop in the background contribution for decays outside of the interval [–55, 6] m from the interaction point proves that the spatial extent of the simulation model is appropriate. Figure 7: Number of decay-induced background particles as a function of the longitudinal decay position in the machine. The boxes on top indicate the positions of dipoles (blue) and final focus quadrupoles (red). The results correspond to the µ+ beam, while the ones for the µare exactly specular. The origin corresponds to the interaction point. The dashed line represents the particle component arriving between -5 and 15 ns with respect to the bunch crossing. The energy spectrum of background particles is reported in Figure 8. The most abundant contributions come from the photon and the neutron components. In the neutron spectrum, the absence of the thermal peak is noticeable due to the presence of boron in the cladding. BEAM-INDUCED BACKGROUND AND DETECTOR CONFIGURATION Deliverable: D2.1 Date: 31/10/2025 Grant Agreement 101094300 PUBLIC 17 / 23 The time of arrival is reported in Figure 9. The electromagnetic shower component is concentrated at times near zero, arriving together with the bunch crossing. On the other hand, neutrons are delayed in time, and their time distribution is more uniform compared to the other particles. For these reasons, applying a simple time-based cut could reduce the overall event count by more than a factor of two. The assumed time window ranges from –5 ns to 15 ns relative to the bunch crossing, reflecting the delayed arrival of certain secondary particles (particularly neutrons) with respect to the bunch crossing. Conversely, the presence of electrons and positrons, albeit less abundant, presents a challenge in mitigation due to their timely arrival characteristics. Figure 8: Kinetic energy spectra of background particles from muon decay. Figure 9: Time of arrival distribution of the decay induced background. Finally, the position of crossing in the detector volume as a function of the longitudinal coordinate is shown in Figure 10. The neutrons peak around +1 m and –1 m from the IP, since the boron cladding stops there. On the contrary, for the photon and electron distributions, the peak is closer to the IP, arriving at the nozzle tip. BEAM-INDUCED BACKGROUND AND DETECTOR CONFIGURATION Deliverable: D2.1 Date: 31/10/2025 Grant Agreement 101094300 PUBLIC 18 / 23 Figure 10: Decay induced background position of crossing. 6. INCOHERENT PAIR PRODUCTION BACKGROUND In addition to the decay-induced background originating from secondary particles produced by muon decays, a relevant source of background arises from incoherent pair production. This process consists of the creation of electron–positron pairs in the intense electromagnetic field of the oncoming bunch. Although its overall rate is smaller than that of the muon-decay background, it can lead to a non-negligible flux of charged particles in the detector acceptance, particularly at small polar angles. In this study, the simulation considers the original MAP nozzle material (i.e., pure tungsten for the nozzle instead of the tungsten alloy considered for the decay background studies). The generation of the incoherent pairs was performed using the GUINEA-PIG code [9], a Monte Carlo event generator developed to simulate beam–beam interactions in lepton colliders. The GUINEA-PIG program calculates the full electromagnetic interaction between the two bunches, producing a list of incoherent e⁺e⁻ pairs at the interaction point. Each entry in the generated dataset corresponds to a single particle (electron or positron) characterized by its energy, direction, and emission angle with respect to the beam axis. The settings used for GUINEA-PIG correspond to the nominal muon collider parameters for a 10 TeV centre-of-mass configuration. The complete configuration file is provided in the supplementary material as acc.dat, and its parameters fully define the bunch charge, transverse and longitudinal sizes, and energy spread of the colliding beams. ID ID ₘ E [GeV] x [cm] y [cm] z [cm] c ₓ cᵧ c_z t [s] int (int32) double (float64) Table 7: Data format for incoherent e⁺e⁻ pairs. The generated pairs are subsequently injected into the FLUKA simulation as primary particles. The FLUKA run corresponds to a full bunch crossing at nominal beam intensity. The data are stored in the incoherent_pair_production_data_fluka.csv file. The data produced follow the same structure BEAM-INDUCED BACKGROUND AND DETECTOR CONFIGURATION Deliverable: D2.1 Date: 31/10/2025 Grant Agreement 101094300 PUBLIC 19 / 23 as the decay background dataset, with the format summarised in Table 7. Each record represents one particle entering the detector region. The resulting dataset allows one to reconstruct both the spatial and angular distributions of the incoherent pairs. The energy spectrum of these particles typically peaks below a few GeV (see Figure 11a), with a long tail extending up to tens of GeV due to the hard photon component from the beam– beam interactions. The directional cosines (Cₓ, Cᵧ, Cz) indicate that most of the pairs are produced with very small polar angles, confirming their highly forward-peaked nature (see Figure 11b). (a): Electron energy spectrum simulated in GUINEA-PIG. (b): Transverse momentum of electrons and positrons after the FLUKA simulation. Figure 11: Comparison between the energy spectrum of incoherent pairs generated by GUINEA-PIG and their transverse momentum after transport in FLUKA. The temporal distribution of the incoherent pairs shows a sharp peak around t = 0, indicating that these particles arrive almost simultaneously with the bunch crossing. This characteristic distinguishes them from the secondary background produced by muon decays, where delayed components (e.g., neutrons) dominate the late-time tails. Consequently, the incoherent pairs represent a challenging background for the inner detector layers, where timing-based background rejection is less effective. 7. APPENDIX: USEFUL CODE The FLUKA numbering system is different from the canonical PDG one. This is due to historical and practical reasons. Information on the particle numbering is provided in the FLUKA manual and FLUKA_PIDS = { -6: 1000020040, -5: 1000020030, -4: 1000010030, -3: 1000010020, 1: 2212, 2: -2212, 3: 11, 4: -11, 5: 12, 6: -12, 7: 22, 8: 2112, 9: -2112, 10: -13, 11: 13, 12: 130, 13: 211, 14: -211, 15: 321, 16: -321, 17: 3122, 18: -3122, 19: 310, 20: 3112, 21: 3222, 22: 3212, 23: 111, 24: 311, 25: - 311, 27: 14, 28: -14, 31: -3222, 32: -3212, 33: -3112, 34: 3322, 35: -3322, 36: 3312, 37: -3312, 38: 3334, 39: -3334, 41: -15, 42: 15, 43: 16, 44: -16, 45: 411, 46: -411, 47: 421, 48: -421, 49: 431, 50: -431, 51: 4122, 52: 4232, 53: 4112, 54: 4322, 55: 4312, 56: 4332, 57: -4122, 58: -4232, 59: - 4132, 60: -4322, 61: -4312, 62: -4332 } BEAM-INDUCED BACKGROUND AND DETECTOR CONFIGURATION Deliverable: D2.1 Date: 31/10/2025 Grant Agreement 101094300 PUBLIC 20 / 23 printed at the end of each FLUKA simulation in the output file [10]. Here, a snippet of Python code allows one to easily transform the FLUKA ID numbering system into the PDG one. The snippet in Listing 1 provides a dictionary that facilitates conversion from FLUKA to PDG particle IDs. It is worth noting that FLUKA may contain ID codes not included in this dictionary. These do not correspond to any known physical particles; they might be reserved identifiers or represent optical photons or ray-tracing objects. Therefore, in the context of the BIB (Beam-Induced Background) simulation output, such unlisted FLUKA ID codes should not appear. BEAM-INDUCED BACKGROUND AND DETECTOR CONFIGURATION Deliverable: D2.1 Date: 31/10/2025 Grant Agreement 101094300 PUBLIC 21 / 23 8. CONCLUSION This deliverable summarizes the production of background data samples for the 10 TeV Muon Collider, generated with the FLUKA.CERN Monte Carlo code within the International Muon Collider Collaboration. The datasets include the main beam-induced background sources: the muon decays and the incoherent electron–positron pair production. The decay induced background was simulated using the latest interaction region layout (lattice version 0.8) with detailed modelling of magnets, shielding, and detector geometry. These samples provide a common reference for detector simulation and performance studies, supporting the design and optimization of the machine–detector interface and the development of effective background mitigation strategies for future muon collider experiments. BEAM-INDUCED BACKGROUND AND DETECTOR CONFIGURATION Deliverable: D2.1 Date: 31/10/2025 Grant Agreement 101094300 PUBLIC 22 / 23 9. REFERENCES [1] Ahdida, C., Bozzato, D., et al. (2022), New capabilities of the FLUKA multi-purpose code, Frontiers in Physics, 9 [2] Battistoni, G., Boehlen, T., et al. (2015), Overview of the FLUKA code, Annals of Nuclear Energy, 82, pp. 10–18 [3] Arominski, D., others (2018), A detector for CLIC: main parameters and performance [4] Skoufaris, K., Carli, C., et al. (2022), 10 TeV Center of Mass Energy Muon Collider, JACoW IPAC, 2022, pp. 515–518 [5] Calzolari, D., Vanwelde, M., et al. (2024), Tentative design of the interaction region, . Available at: https://doi.org/10.5281/zenodo.14000854 [6] Calzolari, D., Skoufaris, K., et al. (2022), Machine-detector interface studies for a multi-TeV muon collider, PoS, EPS-HEP2023 [7] Accettura, C., Adams, D., et al. (2023), Towards a muon collider, The European Physical Journal C, 83 (9) [8] Alexahin, Y.I., Gianfelice-Wendt, E., et al. (2011), Muon collider interaction region design, Physical Review Special Topics - Accelerators and Beams, 14 (6) [9] Schulte, D. (1997), Study of Electromagnetic and Hadronic Background in the Interaction Region of the TESLA Collider, PhD Thesis, Hamburg U. [10] FLUKA collaboration, Fluka manual: particle id codes, https://flukafiles.web.cern.ch/manual/chapters/particle_and_material_codes/particles_codes.ht ml BEAM-INDUCED BACKGROUND AND DETECTOR CONFIGURATION Deliverable: D2.1 Date: 31/10/2025 Grant Agreement 101094300 PUBLIC 23 / 23 ANNEX: GLOSSARY Acronym Definition BIB Beam-Induced Background MDI Machine-Detector Interface IP Interaction Point IR Interaction Region MAP Muon Accelerator Program (U.S. initiative) PDG Particle Data Group