Figure 8
x distribution: data are shown by the dots, the continuous histogram corresponds to the result of the simulation. Both data and simulation are normalized to unit area.
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... better accuracy is reached on the x (µ) and x (e + ) measurements. The x distribution measured in data is shown in Fig. 8 together with the corresponding simulation result. A fair agreement is found. The drop around x = 0, well visible both in data and simulations, is due to the fact that a fraction of the events have small values of x for both muon tracks. A small x value corresponds to a small slope. Hence these tracks, produced at the same vertex, will ...
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... The Low EMittance Muon Accelerator (LEMMA) is an alternative scheme to produce a muon beam with a very small emittance [124,125]. An injector complex produces a high-current positron beam [126]. The positrons impact a target with an energy of 45 GeV, sufficient to produce muon pairs by annihilating with the electrons of the target. ...
A muon collider would enable the big jump ahead in energy reach that is needed for a fruitful exploration of fundamental interactions. The challenges of producing muon collisions at high luminosity and 10~TeV centre of mass energy are being investigated by the recently-formed International Muon Collider Collaboration. This Review summarises the status and the recent advances on muon colliders design, physics and detector studies. The aim is to provide a global perspective of the field and to outline directions for future work.
... The DTs used in this work were built at the Legnaro National INFN Laboratories (LNL) and inspired by those used in the CMS experiment [1], with which they share the same underlying design and configuration. These detectors (referred here as mini-DTs) are designed to provide small-footprint, roughly 70 × 70 cm 2 , muon tracking detectors, and be deployed in a number of different configurations, as for instance in the case of the test-beam of the LEMMA collaboration [2]. Each mini-DT chamber consists of 4 layers of 16 cells, totaling 64 cells per chamber. ...
The online reconstruction of muon tracks in High Energy Physics experiments is a highly demanding task, typically performed on reconfigurable digital circuits, such as FPGAs. Complex analytical algorithms are executed in a quasi-real-time environment to identify, select, and reconstruct local tracks in often noise-rich environments. A novel approach to the generation of local triggers based on a hybrid combination of Artificial Neural Networks and analytical methods is proposed, targeting the muon reconstruction for drift tube detectors. The proposed algorithm exploits Neural Networks to solve otherwise computationally expensive analytical tasks for the unique identification of coherent signals and the removal of geometrical ambiguities. The proposed approach is deployed on state-of-the-art FPGA and its performances are evaluated on simulation and on data collected from cosmic rays.
... For all these future accelerators, however, luminosity is the key factor to reach the desired precision. For lepton colliders e + e − and μ + μ − with muons produced by positrons [3][4][5][6] -the availability of intense and small emittance electron and positron beams is a crucial element to reach the required luminosity. In particular, a positron source represents a major challenge [7]. ...
An intense positron sources is a demanding element in the design of future lepton colliders. A crystal-based hybrid positron source could be an alternative to a more conventional scheme based on the electron conversion into positron in a thick amorphous target. The conceptual idea of the hybrid source is to have two separate objects, a photon radiator and a photon-to-positron converter target. In such a scheme an electron beam crosses a thin axially oriented crystal with the emission of a channeling radiation, characterized by a considerably larger amount of photons if compared to Bremsstrahlung. The net result is an increase in the number of produced positrons at the converter target. In this paper we present the results of a beam test conducted at the DESY TB 21 with 5.6 GeV electron beam and a crystalline tungsten radiator. Experimental data clearly highlight an increased production of photons and they are critically compared with the outcomes of novel method to simulate the number of radiated photons, showing a very good agreement. Strong of this, the developed simulation tool has been exploited to design a simple scheme for a positron source based on oriented crystal, demonstrating the advantages in terms of reduction of both deposited energy and the peak energy deposition density if compared to conventional sources. The presented work opens the way for a realistic and detailed design of a hybrid crystal-based positron source for future lepton colliders.
... For all these future accelerators, however, luminosity is the key factor to reach the desired precision. For lepton colliderse + e − and µ + µ − with muons produced by positrons [3][4][5][6] -the availability of intense and small emittance electron and positron beams is a crucial element to reach the required luminosity. In particular, a positron source represents a major challenge. ...
An intense positron sources is a demanding element in the design of future lepton colliders. A crystal-based hybrid positron source could be an alternative to a more conventional scheme based on the electron conversion into positron in a thick amorphous target. The conceptual idea of the hybrid source is to have two separate objects, a photon radiator and a photon-to-positron converter target. In such a scheme an electron beam crosses a thin axially oriented crystal with the emission of a channeling radiation, characterized by a considerably larger amount of photons if compared to Bremsstrahlung. The net result is an increase in the number of produced positrons at the converter target. In this paper we present the results of a beam test conducted at the DESY TB 21 with 5.6 GeV electron beam and a crystalline tungsten radiator. Experimental data clearly highlight an increased production of photons and they are critically compared with the outcomes of novel method to simulate the number of radiated photons, showing a very good agreement. Strong of this, the developed simulation tool has been exploited to design a simple scheme for a positron source based on oriented crystal, demonstrating the advantages in terms of reduction of both deposited energy and the peak energy deposition density if compared to conventional sources. The presented work opens the way for a realistic and detailed design of a hybrid crystal-based positron source for future lepton colliders.
... Indeed, observing and studying dimuonium would be a significant advance, not only as a chance to understand the fundamental mysteries of leptons, but also as a challenge to experimental physicists to develop new discovery tools. Studying muon pair production in electron-positron annihilation at the threshold energy will also be useful for estimating the limiting luminosity attainable in a muon collider [19]. ...
In this article, we present MuMuPy, a computational library and cloud-based tool for calculating cross sections for the interaction of dimuonium (true muonium) with matter. MuMuPy calculates corresponding form factors and allows one to find the probabilities of dimuonium transitions in the electric field of the nucleus. MuMuPy was developed in the context of the $\mu\mu$-tron facility, the project of a low-energy electron-positron collider for production and experimental study of dimuonium, proposed in our home institute, Budker Institute of Nuclear Physics. The reliability of MuMuPy was verified by three independent methods, one of which was developed by the authors earlier.
... In a range close to the threshold value for √ s the maximum of + − is about 1 µb. A campaign of measurements to study the features of this production scheme has been recently performed at CERN, by means of positron beams of energies between 45 and 49 GeV colliding on a Beryllium (Be) or Carbon (C) target [9,10]. Further investigations are planned to precisely measure the production cross section and the emittance of the produced muon beams. ...
A future multi-TeV muon collider requires new ideas to tackle the problems of muon production, accumulation and acceleration. In the Low EMittance Muon Accelerator concept a 45 GeV positron beam, stored in an accumulation ring with high energy acceptance and low angular divergence, is extracted and driven to a target system in order to produce muon pairs near the kinematic threshold. However, this scheme requires an intensity of the impinging positron beam so high that the energy dissipation and the target maintenance are crucial aspects to be investigated. Both peak temperature rises and thermomechanical shocks are related to the beam spot size at the target for a given material: these aspects are setting a lower bound on the beam spot size itself. The purpose of this paper is to provide a fully theoretical approach to predict the temperature increase, the thermal gradients, and the induced thermomechanical stress on targets, generated by a sequence of 45 GeV positron bunches. A case study is here presented for Beryllium and Graphite targets. We first discuss the Monte Carlo simulations to evaluate the heat deposited on the targets after a single bunch of 3 × 10¹¹ positrons for different beam sizes. Then a theoretical model is developed to simulate the temperature increase of the targets subjected to very fast sequences of positron pulses, over different timescales, from ps regime to hundreds of seconds. Finally a simple approach is provided to estimate the induced thermomechanical stresses in the target, together with simple criteria to be fulfilled (i.e., Christensen safety factor) to prevent the crack formation mechanism.
... A set of gaseous detectors is used in the testbed experimental setup. The detectors are based on the design of the Drift Tubes (DT) of the Compact Muon Solenoid (CMS) experiment [4], and have been employed to perform tracking and particle identification of muons during the 2019 test-beam campaigns of the LEMMA project [8]. Each detector, referred to as chamber, is composed by 4 layers of 16 tubes (cells), each with a transverse size of 42 × 13 mm 2 . ...
As the vast majority of high energy physics experiments rely on data acquisition and trigger systems performing a number of stringent selections before storing data for offline analysis, the reach of their physics programs is thus limited by the fraction of data collected, and by the bias induced by the online filters. Alternative data acquisition solutions, based on the continuous processing of the stream of data are therefore foreseeable. Such implementations, to be deployed as a parallel solution to an experimental trigger architecture, or as a fully integrated data acquisition system for smaller scale experiments, might extend the physics reach by accessing a more and less filtered data. In this document, an end-to-end implementation of a fully trigger-less data acquisition and online data processing system is discussed. An easily scalabe and deployable implementation of such architecture is proposed, based on open-source solutions, to allow for a flexible deployment depending on the computing infrastructure and resources available. A muon telescope setup is used as experimental testbed as the source of the data stream, and a fully integrated online processing pipeline, deployed on cloud computing resources is implemented and described.
... While the leading-order Quantum ElectroDynamics (QED) e + e − → µ + µ − cross-section calculations are well established, at threshold higher order radiative effects, due to Coulomb interaction, might be important to predict the muons production rate and their angular distribution [6]. A dedicated experimental effort has been put in place to study muon production by 45 GeV positrons impinging in beryllium or carbon targets [7]. ...
The investigation of the energy frontier in physics requires novel concept forfuture colliders. The idea of a muon collider is very appealing since it would aim to study particle collisions up to tens of TeV energy while offering a cleaner experimental environment with respect to hadronic colliders. One key elementin the muon collider design is muon production with small emittance. Recently,the Low EMittance Muon Accelerator (LEMMA) collaboration has explored the close-to-threshold muon production by 45 GeV positron annihilating in a low Z material target. Muons are emerging with a natural small emittance. In this paper we describe the performance of a system of segmented absorbers with alternating active layers realized with fast Cherenkov detectors and a muon identification technique based on it. Passive layers were made of tungsten. Muons and electron beams data were collected in September 2018 at the H2 linein the North Area of the Conseil Europ\'een pour la Recherche Nucl\'eaire (CERN).
... The use of crystals for high-energy beam manipulations include also beam focusing and mirroring [41][42][43][44], with potential applications for collimation, cooling, and steering of secondary particle beams [45,46]. Proposals for production and acceleration of future muon beams are under study [7,47,48]. At lower beam energies, interesting developments are ongoing for the use of crystals as ondulators for the next generation of intensive γ -ray light sources by means of channeling of electrons and positrons [49][50][51][52][53][54][55]. ...
Beam collimation in high-energy colliders is customarily carried out by means of massive amorphous absorbers surrounding the circulating beam. Several studies were performed in the last decades to establish an innovative collimation technique that relies on particle deflection by means of channeling between crystalline planes of a bent crystal. We report the operational use of crystal collimation in the Large Hadron Collider that was achieved during a special high-β∗ physics run with low-intensity beams, representing a milestone for both accelerator and high-energy physics that could pave the way for new synergies in the near future. The deployment of this scheme was steered and motivated by machine-simulation studies, which were then confirmed experimentally using data provided by the experiments thanks to a sensitivity not accessible with the ring instrumentation. The evidence of beam-related experimental background reduction, improved data quality, and faster halo removal with respect to amorphous collimators is obtained using bent crystals as the primary collimation stage. A detailed description of preparatory studies and operational performance is reported, together with a comparison between experimental results and theoretical expectations.
... The former process can be used for the precise measurement of the CMS energy and its spread at the µµ-tron collider [4]. Several accelerator technologies studies, like the development of a muon collider, could also benefit from these measurements [5]. ...
A fast leading-order Monte Carlo generator for the process $e^+ e^- \to \mu^+\mu^- \gamma$ is described. Matrix elements are calculated using the helicity amplitude method. Monte Carlo algorithm uses the acceptance-rejection method with an appropriately chosen simplified distribution that can be generated using an efficient algorithm. We provide a detailed pedagogical exposition of both the helicity amplitude method and the Monte Carlo technique, which we hope will be useful for high energy physics students.
