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We report the test results for a 120 GeV proton beam incident on superconducting nanowire particle detectors of various wire sizes. NbN devices with the same sensitive area were fabricated with different wire widths and tested at a temperature of 2.82 K. The relative detection efficiency was extracted from bias current scans for each device. The results show that the wire width is a critical factor in determining the detection efficiency and larger wire widths than 400 nm leads to inefficiencies at low bias currents. These results are particularly relevant for novel applications at accelerator facilities, such as the Electron-Ion Collider, where cryogenic cooling is readily available. [ABSTRACT FROM AUTHOR]

The Crilin calorimeter represents a novel approach in the development of electromagnetic calorimeters for future colliders, especially for a Muon Collider. This paper details the design and performance of the innovative semi-homogeneous Crilin calorimeter, highlighting its capabilities in mitigating beam-induced backgrounds (BIB) while maintaining excellent time resolution (less than 50 ps), longitudinal segmentation, and fine granularity. These performances are achieved throughout a series of stackable and interchangeable lead fluoride (PbF 2) crystal matrices readout by surface-mount UV-extended Silicon Photo-multipliers. Simulated and experimental results demonstrate the Crilin design's potential to work as an efficient and cost-effective alternative to traditional electromagnetic calorimeters. Crilin radiation tolerance is discussed, as measured in several irradiation campaigns, as well as timing performances during a beam test at CERN-H2 with 120 GeV electrons for the latest prototype, Proto-1. Additionally, a description of the results from a recent beam test conducted at the LNF Beam Test Facility with 450 MeV electrons is provided, aiming to measure light yield losses due to irradiation. [ABSTRACT FROM AUTHOR]

An HPGe detector equipped with a transistor reset preamplifier and readout with a CAEN DT5781 fast pulse digitizer was employed in the measurement of X-rays from kaonic lead at the DA Φ NE e + e − collider at the Laboratori Nazionali di Frascati of INFN. A thin scintillator in front of a lead target was used to select kaons impinging on it and to form the trigger for the HPGe detector. We present the results of the kaonic lead feasibility measurement, where we show that the resolution of the HPGe detector in regular beam conditions remains the same as that without the beam and that a satisfactory background reduction can be achieved. This measurement serves as a test bed for future dedicated kaonic X-rays measurements for the more precise determination of the charged kaon mass. [ABSTRACT FROM AUTHOR]

Collective wakefield and beam–beam effects play an important role in accelerator design and operation. These effects can cause beam instability, emittance growth, and luminosity degradation, and warrant careful study during accelerator design. In this paper, we studied the combined wakefield and beam–beam effects in an Electron Ion Collider design using strong–strong simulations. The simulation results show that the nonlinear beam–beam effects help suppress wakefield driven instability in the nominal working tune regime. In other tune regimes, the coherent beam–beam modes interact with the wakefields and cause a beam instability. The simulation results also show the importance of maintaining nominal crab cavity voltage. If the crab cavity voltage drops significantly the beam can become unstable. [ABSTRACT FROM AUTHOR]

Over the past years the dual-readout method for calorimetry, which exploits complementary information from Scintillation and Cherenkov channels, has emerged as candidate to fulfil the requirements for precision physics at future circular lepton colliders. While the dual-readout approach has been tested experimentally quite extensively, this type of calorimeter has never been used in an experiment at a collider. In recent years dedicated studies in simulation have investigated various detector geometries based on a fibre dual-readout calorimeter. One variation of the geometry, relying on capillary tubes, promises easy assembly with excellent geometrical accuracy at a moderate cost. In these proceedings, we present the status and latest results from a full 4 π detector geometry simulation in DD4hep. The simulation is used to estimate the performance of a dual-readout calorimeter for single electromagnetic and hadronic particles. The results for the dual-readout technique show an improvement in energy resolution for both electromagnetic and hadronic showers, with respect to single channel measurements. [ABSTRACT FROM AUTHOR]

The proposed Circular Electron Positron Collider (CEPC) presents several challenges for the vertex detector, including material budget, spatial resolution, readout speed, and power consumption. To address these challenges, a Monolithic Active Pixel Sensor (MAPS) prototype called TaichuPix has been developed for the CEPC vertex detector. To evaluate the performance of the TaichuPix-3 prototype, a beam test was conducted at the DESY II TB21 facility. This work presents the analysis results of the offline beam data, including cluster size, spatial resolution, and multiple scattering studies, which indicate the intrinsic resolution of TaichuPix-3 chips is less than 5 µm and the material budget is measured to be 0. 170 ± 0. 018 %. [ABSTRACT FROM AUTHOR]

The CompleX project aims at extending the operation range of silicon detectors as 4D trackers up to 5 × 1017 n eq cm−2. The project envisions achieving this unprecedented radiation tolerance through a novel comprehension of radiation damage saturation, and an innovative design for the Low-Gain Avalanche Diodes (LGADs) gain layer with compensated implants. This innovative LGAD design, featuring a co-implantation of acceptor and donor dopants, represents a paradigm shift in radiation-resistant sensor technology. It potentially enables compensated LGADs to maintain functionality at fluences exceeding 1017 n eq cm−2, significantly extending the operational lifetime of conventional LGAD sensors under extreme fluence conditions. This advantage is further enhanced by the inherent radiation tolerance of thin substrates. This work presents simulations and measurements from the first compensated LGAD production (late 2022, FBK foundry) before and after neutrons irradiation. Numerical modeling strategies using state-of-the-art Technology-CAD tools quantify the reduction in acceptor removal rate due to carbon co-implantation and investigate the behavior of donor removal under irradiation. This comprehensive approach paves the way for the development of highly efficient tracking detectors for future collider experiments. [ABSTRACT FROM AUTHOR]

The Muon Collider (MC) is one of the most promising machines in terms of discovery potential. However, technological challenges arise from muon instability. This paper introduces a novel approach to muon track reconstruction designed to manage the high background levels. In this context, a fast-timing detector is required. This contribution presents the results of R&D efforts on the Picosec detector, a new generation of fast-timing Micro-Pattern Gaseous Detectors (MPGD). Specifically, the results from various test beam campaigns, focused on optimizing this technology for future experiments at a MC facility, are discussed. [ABSTRACT FROM AUTHOR]

Among the proposed accelerators for the post-LHC era are the Future Circular Collider (FCC) and the Circular Electron–Positron Collider (CEPC). Both projects would take advantage of the clean environment and low radiation damage of electron–positron collisions, providing the highest precision studies of electroweak and Higgs physics. The relatively high branching fraction of W, Z and Higgs bosons into hadronic jets makes the precise measurements of these objects an essential aspect on detector development for experiments at future collider facilities. One of the most promising calorimetry techniques for improved hadron energy reconstruction is the dual-readout method, which exploits signals from two different physics processes to correct for the f e m of hadron showers, therefore boosting the standalone calorimeter performance. The usage of compact photosensors (e.g. Silicon PhotoMultipliers) for the readout enables a very fine segmentation, opening to particle-flow and advanced neural networks software reconstruction of events. In this contribution, the results of testing a small-scale dual-readout calorimeter prototype, characterised by a mixed PMT and SiPM readout solution, with an electron beam at the CERN SPS facility in the energy range [10, 120] GeV are presented. It follows the description of a larger prototype of the same type, currently under construction in the context of the INFN HiDRa project, that will be large enough to fully contain hadron showers. The design, construction technique and expected performance, as estimated through a Geant4 simulation parameterised on the previous prototype, are presented. [ABSTRACT FROM AUTHOR]

The electromagnetic calorimeter (ECal) plays a critical role in high-energy particle colliders, by measuring the energy of particles that interact primarily via the electromagnetic interaction such as electrons, positrons and photons. Fudan University has undertaken part of the mass production of ECal modules for the Multi-Purpose Detector (MPD) project of the Nuclotron-based Ion Collider fAcility (NICA). Preliminary tests on the ECal modules is an essential step in detector construction. This article introduces the cosmic ray testing of the ECal modules produced by Fudan University. We tested the cosmic ray under the conditions of horizontal and vertical placement of the module, calculated the average number of generated photons, and estimated the module's energy resolution. Moreover we analyzed the time resolution performance of the device. The test results indicate that when cosmic rays vertically traverse the entire ECal, the number of photons produced can reach 834, with a potential energy resolution less than 5 % / E . The time resolution is 189ps. Based on the comprehensive test results, the production of the ECal meets the design requirements. [ABSTRACT FROM AUTHOR]

The Electron-Ion Collider (EIC) facility is envisaged for the ultimate exploration of the nucleons, the nuclear matter and the strong force, thanks to its wide range of centre-of-mass energy, its large luminosity, and the polarization of its beams. The ePIC detector, designed to cope with the EIC physics potential, involves several Cherenkov radiation-based sub-systems for Particle Identification. They need reliable and effective Single Photo-Electron (SPE) sensors. We report about the timing performance of a LAPPD prototype tested with Cherenkov light produced in a quartz radiator at a CERN PS hadron test beam. Results show a SPE time resolution of 87 ps rms. [ABSTRACT FROM AUTHOR]

We present a mixed-signal ASIC, called ALCOR (A Low-power Chip for Optical sensor Readout), designed for the readout and digitization of signals from Silicon Photomultipliers (SiPMs) in the framework of the dual-radiator RICH (dRICH) detector of the electron–Proton/Ion Collider (ePIC) experiment at the Electron–Ion Collider (EIC). ALCOR features 32 channels arranged in an 8x4 matrix. The amplifier input stage is a low impedance current conveyor based on a regulated common-gate topology. The versatile front-end is able to work with positive or negative input polarity signals and includes four gain settings and two discriminators with 6-bit DAC programmable thresholds. Each channel also incorporates quad-buffered low-power TDCs based on analogue interpolation providing precise timestamping with a 25–50 ps time bin. ALCOR is designed in a 110 nm CMOS technology and the power consumption is about 10–12 mW per channel. The ASIC has been extensively tested in the laboratory standalone and coupled to different SiPM models to assess its functionality and performance. The results have been validated in a beam test campaign with a prototype of the dRICH detector and 1280 3 × 3 mm2 SiPM sensors. [ABSTRACT FROM AUTHOR]

We study diffractive vector meson production at small- x in the collision of electrons and polarized deuterons e + d ↑. We consider the polarization dependence of the nuclear wave function of the deuteron, which results in an azimuthal angular dependence of the produced vector meson when the deuteron is transversely polarized. The Fourier coefficients extracted from the azimuthal angular dependence of the vector meson differential cross-section exhibit notable differences between longitudinally and transversely polarized deuterons. The angular dependence of the extracted effective deuteron radius provides direct insight into the structure of the polarized deuteron wave function. Furthermore, we observe slightly increased gluon saturation effects when the deuteron is longitudinally polarized compared to the transversely polarized case. The small- x observables studied in this work will be accessible at the future Electron-Ion Collider. [ABSTRACT FROM AUTHOR]

Micro-pattern gaseous detectors (MPGDs) are a promising readout technology for hadronic calorimeters (HCAL) thanks to their good spatial resolution, longevity and rate capability. We describe the development of a HCAL based on MPGDs for an experiment at the proposed Muon Collider. The design of a semi-digital MPGD-HCAL is shown and its performance is calculated with Monte Carlo simulations with high-energy pions, showing an energy resolution down to 8% for 80 GeV pions. We also present the performance of twelve MPGD prototypes with different technologies (MicroMegas, μ -RWELL and RPWELL) assembled and operated in test beam first with high-energy muons and later with pions in a hadronic calorimeter prototype of ∼ 1 λ I length; the detectors have a good response uniformity (lower than 17%) and spatial resolution and their performance in the calorimeter shows very good agreement with the Monte Carlo shower calculation. [ABSTRACT FROM AUTHOR]

The Belle II experiment at the SuperKEKB collider in Tsukuba, Japan, has collected e + e − collision data between 2019 and 2022. After reaching a record-breaking instantaneous luminosity of 4.71 × 1034 cm-2 s-1 and recording a dataset corresponding to 424 fb-1, it completed its first planned long shutdown phase in December 2023. Aside from upgrades of the collider and detector maintenance, the shutdown was used for the installation of the two-layer Pixel VerteX Detector (PXD). As the innermost sub-detector, multiple scattering effects need to be reduced. PXD utilizes the Depleted P-channel Field Effect Transistor (DEPFET) technology, allowing for a material budget of 0.21% X 0 per layer. Each of the tracker's 40 modules consists of an array of 250 × 768 pixels with a pitch ranging from 50 µm × 55 µm for the inner to 85 µm × 55 µm for the outer layer yielding high gain and high signal-to-noise ratio while retaining about 99% hit efficiency. This article discusses the experience of the 4-year operation of the previous single-layer PXD in harsh background conditions as well as commissioning and testing of the fully-populated PXD2 during Long Shutdown 1. [ABSTRACT FROM AUTHOR]

The RADiCAL Collaboration is conducting R&D on high performance electromagnetic (EM) calorimetry to address the challenges expected in future collider experiments under conditions of high luminosity and/or high irradiation (FCC-ee, FCC-hh, fixed target and forward physics environments). Under development is a sampling calorimeter approach, known as RADiCAL modules, based on scintillation, wavelength-shifting (WLS) technologies and photosensor, including SiPM or SiPM-like technology. The modules discussed herein consist of alternating layers of very dense tungsten (W) absorber and scintillating crystal Lutetium Yttrium Orthosilicate LYSO(Ce) plates, assembled to a depth of 25 X 0. The scintillation signals produced by the EM showers in the region of EM shower maximum (shower max) are transmitted to SiPM located at the upstream/downstream ends of the modules via quartz capillaries which penetrate the full length of the module. The capillaries contain DSB1 organic plastic WLS filaments positioned within the region of shower max, where the shower energy deposition is greatest, then fused with quartz rod elsewhere. The wavelength shifted light from this spatially-localized shower max region is then propagated to the photosensors. This paper presents the results of an initial measurement of the time resolution of a RADiCAL module over the energy range 25 GeV ≤ E ≤ 150 GeV using the H2 electron beam at CERN. The data indicate an energy dependence of the time resolution that follows the functional form: σ t = a / E ⊕ b , where a = 256 G e V ps and b = 17.5 ps. The time resolution measured at the highest electron beam energy for which data was currently recorded (150 GeV) was found to be σ t = 27 ps. [ABSTRACT FROM AUTHOR]

The CALICE technological RPC-based SDHCAL prototype that fulfills all the requirements of compactness, hermeticity and power budget of the future lepton accelerator experiments, has been extensively tested and has provided excellent results in terms of the energy resolution and shower separation. New phase of R&D to validate completely the SDHCAL option for the International Linear Detector (ILD) project of the ILC and also the Circular Electron Positron Collider (CEPC) has started with the conception and the realization of new prototypes. One of the new prototypes is intended to host few but large active layers of the future SDHCAL. The new active layers, made of GRPC with sizes larger than 2 m2 will be equipped with a new version of the electronic readout fulfilling the requirements of the future ILD detector. The new GRPC are conceived to improve the homogeneity with a new gas distribution scheme. Finally, the mechanical structure will use the electron beam welding. The second new prototype propose to exploit the excellent time resolution provided by RPC detectors in order to better build the hadronic showers with the aim to better separate them and also to single out the contribution of delayed neutrons. The progress realized on the two prototypes are presented. [ABSTRACT FROM AUTHOR]

In this work, the production of γ p → ϕ (2170) p is studied for the first time by using the two gluon exchange model and effective Pomeron exchange model under the assumption that ϕ (2170) is a conventional s s ¯ state. On the whole, the numerical results show that the total cross section of ϕ (2170) through γp scattering can reach more than 70 nb at a center-of-mass energy of W =7 GeV. A comparison between the outcomes of the two models reveals subtle discrepancies. Moreover, base on the cross section of ϕ (2170) photoproduction, we systematically analyzed the production of ϕ (2170) at Ultra-Peripheral Collisions (UPCs) and Electron-Ion Colliders (EICs) by using the STARlight and eSTARlight program developed by Brookhaven National Laboratory (BNL). Accordingly, the cross section, event number and rapidity distribution of ϕ (2170) through EICs and UPCs are predicted based on the accelerator experiments. These projections offer valuable theoretical insights for forthcoming experiments at EicC, EIC-US, RHIC, and LHC facilities. [ABSTRACT FROM AUTHOR]

The Belle II experiment searches for beyond-the-standard-model physics using the Belle II detector and SuperKEKB collider. The silicon vertex detector (SVD) is crucial for particle tracking. After the 1.5-year shutdown from June 2022, Run 2 began in January 2024; Run 2 operation shows stable noise levels, high signal-to-noise ratios, and hit efficiency over 99%. To manage higher beam background from increased luminosity, new techniques such as hit-time selection and cluster grouping are being developed. These methods increase the acceptable level of occupancy by distinguishing hits from triggered collisions and other sources. [ABSTRACT FROM AUTHOR]

Microwave vacuum electronics play a vital role in numerous applications, and high-power couplers are a critical component. However, coupler failure is a common problem in high-energy accelerators, especially in situations involving high continuous wave (CW) power operation, leading to costly downtime and reduced performance. This paper focuses on addressing the issue of coupler failure in high-power scenarios by studying the specific case of the Circular Electron-Positron Collider (CEPC) 650 MHz high-efficiency klystron, designed for a power of 800 kW and tested up to 700 kW. The failure was attributed to the cracking of the coupler ceramics due to asymmetric electric field distribution, a previously unnoticed issue. Consequently, this study describes the coupler testing process, analyzes the problem, and proposes corresponding solutions to achieve symmetrical electric field distribution and reduce thermal stress. After evaluating three approaches, we recommend the T-bar coupler with water cooling and forced air cooling as the most viable option. This research is significant for the future development of high-power couplers, as it offers references for overcoming technical challenges and optimizing structural designs. As a result, other high-power coupler designers may find inspiration in the suggested solutions as they strive for increased dependability and performance. • Ceramic breakage of the coupler is a common failure in microwave vacuum electronic devices. • The asymmetric electric field distribution causing high-power coupler failure is rarely discussed. • The introducing of T-bar transition and optimizing the structure can effectively suppress the issue of asymmetric field distribution. • Addressing the asymmetric field distribution problem is significant for improving coupler performance. [ABSTRACT FROM AUTHOR]

The concept of capacitive-sharing readout, described in detail in a previous study, offers the possibility for the development of high-performance three-coordinates (X–Y–U)-strip readout for Micro Pattern Gaseous Detectors (MPGDs) using simple standard PCB fabrication techniques. Capacitive-sharing (X–Y–U)-strip readout allows simultaneous measurement of the Cartesian coordinates x and y of the position of the particles together with a third coordinate u along the diagonal axis in a single readout PCB. This provides a powerful tool to address multiple-hit ambiguity and enable pattern recognition capabilities in moderate particle flux environment of collider or fixed target experiments in high energy physics HEP) and nuclear physics (NP). We present in this paper the performance of a 10 cm × 10 cm triple-GEM detector with capacitive-sharing (X–Y–U)-strip anode readout. Spatial resolutions of the order of σ x r e s = 71. 6 ± 0. 8 μ m for X-strips, σ y r e s = 56. 2 ± 0. 9 μ m for Y-strips and σ u r e s = 75. 2 ± 0. 9 μ m for U-strips have been obtained at a beam test at Thomas Jefferson National Accelerator Facility (Jefferson Lab). Modifications of the readout design of future prototypes to improve the spatial resolution and challenges in scaling to large-area MPGDs are discussed. [ABSTRACT FROM AUTHOR]

The standard gas mixture for the Resistive Plate Chambers (RPC), composed of C 2 H 2 F 4 /i- C 4 H 10 / SF 6 , allows the detector operation in avalanche mode, as required by the high-luminosity collider experiments. The C 2 H 2 F 4 and SF 6 are now considered to be non-eco-friendly gases for their high Global Warming Potential (GWP). These gases are not recommended for industrial uses anymore, thus their availability will be increasingly difficult over time and the search for an alternative gas mixture is then of absolute priority. There are several studies on going which use different approach to find an alternative gas mixture suitable for experiment which work in high-radiation environment, as those operating at the Large Hadron Collider (LHC). One approach is to replace the standard gas with HFO1234ze/ CO 2 /i- C 4 H 10 / SF 6 , being the HFO1234ze/ CO 2 the main gas component and obtaining a gas mixture with a GWP ∼ 200. The second approach, currently under study by ATLAS and CMS collaborations, is to introduce a small fraction of CO 2 in the standard gas mixture, thus reducing the emissions of C 2 H 2 F 4 . In this presentation the results on the performance achieved using a 1 mm gas gap RPC with both types of gas mixtures are reported. Moreover, the possibility to reduce the SF 6 fraction and to replace it at all with a new gas, the HFO1233zd, is also reported. The RPC performance are studied under strong photon irradiation which reproduces the gamma background of the ATLAS cavern and that expected during the High-Luminosity phase of the LHC. [ABSTRACT FROM AUTHOR]

We have studied anomalous four-photon couplings in the μ + μ − → μ + γ γ μ − scattering at a future muon collider. The collision energies of 3 TeV, 14 TeV, and 100 TeV are addressed. Both differential and total cross sections versus invariant mass of the outgoing photons are calculated. The best 95% C.L. exclusion bounds on anomalous couplings are obtained to be g 1 = 2.23 × 10 − 8 TeV−4 and g 2 = 4.22 × 10 − 8 TeV−4. They correspond to the muon collision energy of 100 TeV. The partial-wave unitary constraints on g 1 and g 2 are examined. We have demonstrated that the unitarity is not violated in a region of the anomalous couplings obtained in the present paper. [ABSTRACT FROM AUTHOR]

Novel collider experiments demand an increased performance of the silicon detectors used, such as withstanding up to 1 × 1 0 17 n eq / cm 2 in unprecedented pile-up conditions and providing time resolution around 10 ps. Currently, Low Gain Avalanche Diodes (LGADs) are the standard, achieving resolutions below 30 ps. However, their limited radiation hardness is an area of ongoing research. As an alternative to LGADs, 3D sensors are interesting due to their proven radiation hardness. In 3D sensors, where the columns are etched into the sensor from the top (junction columns) and the back (ohmic columns), the drift distances can be very short, the depletion voltage is low and the electric field can be high, resulting in fast and short signals. In this study, the time resolution of different 3D pixel and strip sensors is investigated with signals generated by electrons as well as an infra-red laser. TCT Timing measurements allow to study the position dependence of the time resolution, which is interesting for 3D sensors due to their complex electric field structure. Position-timing maps prove the direct correlation between time resolution and electric field. The time resolution of 3D sensors before and after irradiation is presented, showing that 3D sensors can reach the time resolution of standard 50 μ m LGADs, which is limited by Landau fluctuations. In addition, the results demonstrate that the radiation-induced performance degradation in 3Ds is less severe than in LGADs. Furthermore, initial results from a production run of dedicated fast 3D sensors which have recently been produced at CNM as a common RD50 project will be presented. Finally, the option of using fast 3D sensors as timing detectors in future collider experiments will be discussed. [ABSTRACT FROM AUTHOR]

An algorithm of pre-equilibrium clustering of spectator matter based on the construction of the minimum spanning tree (MST) is presented. The algorithm was implemented in the Abrasion-Ablation Monte Carlo for Colliders (AAMCC) model designed to study the characteristics of spectator matter in collisions of relativistic nuclei. Due to accounting for the pre-equilibrium clusters in modelling 208 Pb– 208 Pb collisions at the LHC, the agreement of simulation results with experimental data on the average multiplicities of spectator nucleons was improved. The results of the AAMCC-MST were compared with experimental data on the interactions of 197 Au nuclei in nuclear photoemulsion. Comparison of the yields of spectator nuclei calculated for 16 O– 16 O collisions with the yields measured in interactions of 16 O with light nuclei of photoemulsion made it possible to estimate the effect of MST-clustering in small nuclear systems. [ABSTRACT FROM AUTHOR]

We consider the production of excited electrons with spin-1/2 at future SPPC-based electron-proton colliders with center-of-mass energies of 8.4,11.6, 26.6, and 36.8 TeV. These exotic particles are predicted in the composite models. We calculate the production cross sections and concentrate on the photon decay channel of the excited electrons with the process of ep [right arrow] e*X [right arrow] e[gamma]X. The pseudo rapidity and transverse momentum distributions of the electrons and photons in the final state have been plotted to determine the kinematical cutoffs best suited for discovery of the excited electrons. By applying these cutoffs we compute 2[sigma], 3[SIGMA], and 5[SIGMA] contour plots of the statistical significance of the expected signal in the parameter space (L, m*), where L denotes the integrated luminosity of the collider and m* is the mass of the composite electrons. Key words: excited electrons, SPPC, future colliders, cross sections, excited leptons. Nous envisageons la production d'electrons excites de spin-1/2 au collisionneur electron-proton base sur le futur SPPC, avec des energies dans le centre de masse de 8,4, 11,6 et 36,8 TeV. Ces particules exotiques sont prevues dans les modeles composites. Nous calculons les sections efficaces de production et nous focalisons sur le canal de desintegration par photon de l'electron excite dans le procede ep [right arrow] e*X [right arrow] e[gamma]X. Les distributions de pseudo-rapidite et d'impulsion transverse des electrons et des protons sont tracees afin de determiner les coupures cinematiques les plus adaptees a la decouverte des electrons excites. En appliquant ces coupures, nous calculons les traces de contours a 2[SIGMA], 3[SIGMA] et 5[SIGMA] de la signification statistique du signal attendu dans l'espace des parametres (L, m*), ou L note la luminance integree du collisionneur et m* est la masse de l'electron composite. [Traduit par la Redaction] Mots-cles: electrons excites, SPPC, futurs collisionneurs, sections efficacies, leptons excites., 1. Introduction Elementary particles and electromagnetic, weak, and strong interactions among them are well described by the Standard Model (SM) in particle physics. Discovery of the Higgs boson with a [...]

Charged particle multiplicity distributions in positron-proton deep inelastic scattering at a centre-of-mass energy ps = 300 GeV, measured in the hadronic centre-of-mass frames and in different pseudorapidity windows are studied in the framework of two statistical distributions, the shifted Gompertz distribution and the Weibull distribution. Normalised moments, normalised factorial moments and the H-moments of the multiplicity distributions are determined. The phenomenon of oscillatory behaviour of the counting statistics and the Koba-Nielsen-Olesen (KNO) scaling behaviour are investigated. This is the first such analysis using these data. In addition, projections of the two distributions for the expected average charged multiplicities obtainable at the proposed future ep colliders. [ABSTRACT FROM AUTHOR]

Within the framework of the HiLumi-LHC project, CERN is currently manufacturing 11 T dipole and quadrupole accelerator magnets using state-of-the-art Nb3Sn Rutherford cables. Even higher magnetic fields are considered by the Hadron Future Circular Collider (FCC-hh) design study, which plans to develop 16 T Nb3Sn bending dipoles. In such high-field magnets, the design pre-stress can reach considerable values (150–200 MPa) and, since Nb3Sn is a brittle compound, this can constitute a technological difficult challenge. Due to the significant impact that a transverse load can have on the performances of a Nb3Sn magnet, CERN has launched a campaign of critical current measurements of reacted and impregnated Nb3Sn cables subjected to transverse pressure up to about 210 MPa. In this paper, results obtained on 18-strand 10-mm-wide cable sample based on a 1-mm-diameter powder-in-tube (PIT) wire are presented. The tests were carried out on a 2-m-long sample by using the FReSCa test station, at T = 4.3 K and background magnetic fields up to 9.6 T. For applied pressures below ≈ 130 MPa, only reversible reductions of the critical current, Ic, are observed. At higher pressures, a permanent Ic reduction occurs; such irreversible behaviour is due to the residual stresses generated by the plastic deformations of the copper stabilizer. This type of current reduction, whether reversible or not, is fully governed by the strain-induced variations of the upper critical field, Bc2. At higher pressures, estimated between 180 and 210 MPa, it is indeed plausible to believe that cracking of filaments occurs, with detrimental consequences for the Nb3Sn cable's electrical performances. The complete set of critical current data here presented, collected at different pressures and as a function of the applied magnetic field, allows for the first time to investigate the evolution of superconducting parameters such as the upper critical field Bc2 in the irreversibility region, where both the effects of Cu matrix plasticization and/or cracking of filaments may occur. The experimental approach and data interpretation have a general value and can be applied to any typology of Rutherford cable. [ABSTRACT FROM AUTHOR]

Multiple parton scattering occurs when two or more independent identified hard particle from each proton takes place in the same proton-proton collision. The multiparton scattering mechanism got a new impulse at the LHC, where the high energy provides access to a very small value at the fractional momentum. Double parton scattering (DPS) and triple parton scattering (TPS), are expected to occur frequently in the proton-proton collision at the LHC and future high-energy colliders. This can give rise to a sizeable background to certain rare single parton scattering (SPS) and an interesting signal process in their own right. In this article, we discuss the total cross sections in both double and triple parton scattering mechanism for different process. [ABSTRACT FROM AUTHOR]

Although used in the design and costing of large projects such as linear colliders and fusion tokamaks, the theory of vacuum arcs and gradient limits is not well understood. Almost 120 years after the isolation of vacuum arcs, the exact mechanisms of the arcs and the damage they produce are still being debated. We describe our simple and general model of the vacuum arc that can incorporate all active mechanisms and aims to explain all relevant data. Our four stage model, is based on experiments done at 805 MHz with a variety of cavity geometries, magnetic fields, and experimental techniques as well as data from Atom Probe Tomography and failure analysis of microelectronics. The model considers the trigger, plasma formation, plasma evolution and surface damage phases of the RF arc. This paper also examines how known mechanisms can explain the observed sharp field dependence, fast breakdown times and observed surface damage. We update the model and discuss new features while also pointing out where new data would be useful in extending the model to a wider range of frequencies. [ABSTRACT FROM AUTHOR]