Search

The High Intensity Muon Beams (HIMB) project at the Paul Scherrer Institute (PSI) will deliver muon beams with unprecedented intensities of up to 10 10 muons / s for next-generation particle physics and material science experiments. This represents a hundredfold increase over the current state-of-the-art muon intensities, also provided by PSI. We performed beam dynamics optimisations and studies for the design of the HIMB beamlines MUH2 and MUH3 using Graphics Transport, Graphics Turtle, and G4beamline, the latter incorporating PSI's own measured π + cross-sections and variance reduction. We initially performed large-scale beamline optimisations using asynchronous Bayesian optimisation with DeepHyper. We are now developing an island-based evolutionary optimisation code glyfada based on the Paradiseo framework, where we implemented Message Passing Interface (MPI) islands with OpenMP parallelisation within each island. Furthermore, we implemented an island model that is also suitable for high-throughput computing (HTC) environments with asynchronous communication via a Redis database. The code interfaces with the codes COSY INFINITY and G4beamline. The code glyfada will provide heterogeneous island model optimisation using evolutionary optimisation and local search methods, as well as part-wise optimisation of the beamline with automatic advancement through stages. We will use the glyfada for a future large-scale optimisation of the HIMB beamlines. [ABSTRACT FROM AUTHOR]

The High Intensity Muon Beams (HIMB) project at the Paul Scherrer Institute (PSI) will deliver muon beams with unprecedented intensities of up to 1010muons/s for next-generation particle physics and material science experiments. This represents a hundredfold increase over the current state-of-the-art muon intensities, also provided by PSI. We performed beam dynamics optimisations and studies for the design of the HIMB beamlines MUH2 and MUH3 using Graphics Transport, Graphics Turtle, and G4beamline, the latter incorporating PSI’s own measured π+ cross-sections and variance reduction. We initially performed large-scale beamline optimisations using asynchronous Bayesian optimisation with DeepHyper. We are now developing an island-based evolutionary optimisation code glyfada based on the Paradiseo framework, where we implemented Message Passing Interface (MPI) islands with OpenMP parallelisation within each island. Furthermore, we implemented an island model that is also suitable for high-throughput computing (HTC) environments with asynchronous communication via a Redis database. The code interfaces with the codes COSY INFINITY and G4beamline. The code glyfada will provide heterogeneous island model optimisation using evolutionary optimisation and local search methods, as well as part-wise optimisation of the beamline with automatic advancement through stages. We will use the glyfada for a future large-scale optimisation of the HIMB beamlines.

The mass mμ− of the negative muon is one of the parameters of the elementary particle Standard Model and it allows us to verify the CPT (charge–parity–time) symmetry theorem by comparing mμ− value with the mass mμ+ of the positive muon. However, the experimental determination precision of mμ− is 3.1ppm, which is an order of magnitude lower than the determination precision of mμ+ at 120ppb. The authors aim to determine mμ− and the magnetic moment μμ− with a precision of O(10ppb) through spectroscopy of the hyperfine structure (HFS) of muonic helium-4 atom (4Heμ−e−) under high magnetic fields. He4μ−e− is an exotic atom where one of the two electrons of the He4 atom is replaced by a negative muon. To achieve the goal, it is necessary to determine the HFS of He4μ−e− with a precision of O(1ppb). This paper describes the determination procedure of the HFS of He4μ−e− in weak magnetic fields reported recently, and the work towards achieving the goal of higher precision measurement.

A novel nondestructive light element analysis method for bulk materials using muon beams was demonstrated. This method is based on the lifetime measurement of muons in a material and performed by measuring muon-decay electrons and identifying elements using the atomic number based on muon lifetimes. Muon irradiation on pure iron and two steel samples with known carbon contents was conducted to prepare a calibration curve for the quantitative analysis. We also performed a muon lifetime measurement for a Japanese sword and successfully determined its carbon content as 0.51 wt% using the calibration curve, without sample destruction. [ABSTRACT FROM AUTHOR]

The mass  m μ −  of the negative muon is one of the parameters of the elementary particle Standard Model and it allows us to verify the CPT (charge–parity–time) symmetry theorem by comparing  m μ −  value with the mass  m μ +  of the positive muon. However, the experimental determination precision of  m μ −  is  3.1 ppm , which is an order of magnitude lower than the determination precision of  m μ +  at  120 ppb . The authors aim to determine  m μ −  and the magnetic moment  μ μ −  with a precision of  O (10 ppb)  through spectroscopy of the hyperfine structure (HFS) of muonic helium-4 atom  (4 He μ − e −)  under high magnetic fields.  He 4 μ − e −  is an exotic atom where one of the two electrons of the  He 4  atom is replaced by a negative muon. To achieve the goal, it is necessary to determine the HFS of  He 4 μ − e −  with a precision of  O (1 ppb) . This paper describes the determination procedure of the HFS of  He 4 μ − e −  in weak magnetic fields reported recently, and the work towards achieving the goal of higher precision measurement. [ABSTRACT FROM AUTHOR]

Elemental analysis with muonic x-rays is one of the analytical methods to identify elements non-destructively. Since the energy of the muonic x-rays is almost 200 times higher than one of the fluorescent x-rays, light elements such as lithium can be identified. We have applied this technique to detection of metallic lithium deposition in a Li-ion battery, which prevents from promoting the recovery and reuse of used batteries. Since the capture ratio of muon by lithium in metallic lithium is enormously higher than one in anode, it is possible to detect metallic lithium with high sensitivity by the technique. This technique is being developed to be also used in factories and yards during the industrial processes with portable accelerators for muons, which will promote the recovery and reuse of Li-ion batteries in the future. [ABSTRACT FROM AUTHOR]

In recent years, the use of high-penetrate cosmic-ray muons has been used in many applications to investigate the internal structure and composition of large material. The muon attenuation is based on multiple Coulomb scattering. This study was aimed to investigate the effect of massive shielding material composition in muon tomography. Muon with various energies between 1 MeV to 100 MeV was used as a source located directly above the shielding material with different density and composition. The output of scattered muon was scored in 2 and 5 km after the material. The simulation was performed using particle and heavy ion transport system (PHITS) software developed by Japan Atomic Energy Agency. The attenuation and scattering of the muon depends predominantly on the shielding material density. The muon energy and flux was decreased with increasing depth of the muon detector. This muon tomography can be applied in investigating the structure and internal composition of unknown materials such as volcanic structures in Indonesia.

Cosmic ray air showers are a phenomenon that can be observed on Earth when high-energy particles from outer space collide with the Earth’s atmosphere. These energetic particles in space are called primary cosmic rays and consist mainly of protons (about 89%), along with nuclei of helium (10%) and heavier nuclei (1%). Particles resulting from interactions in the atmosphere are called secondary cosmic rays. The composition of air showers in the atmosphere can include several high-energy particles such as mesons, electrons, muons, photons, and others, depending on the energy and type of the primary cosmic ray. Other than air, primary cosmic rays can also produce showers of particles when they interact with any type of matter; for instance, particle showers are also produced within the soil of planets without an atmosphere. In the same way, secondary cosmic particles can start showers of tertiary particles in any substance. In the 1930s, Bruno Rossi conducted an experiment to measure the energy loss of secondary cosmic rays passing through thin metal sheets. Surprisingly, he observed that as the thickness of the metal sheets increased, the number of particles emerging from the metal also increased. However, by adding more metal sheets, the number of particles eventually decreased. This was consistent with the expectation that cosmic rays were interacting with the atoms in the metals and losing energy to produce multiple secondary particles. In this paper, we describe a new–old approach for measuring particle showers in water using a cosmic ray telescope and Rossi’s method. Our instrument consists of four Geiger–Müller tubes (GMT) arranged to detect muons and particle showers. GMT sensors are highly sensitive devices capable of detecting electrons and gamma rays with energies ranging from a few tens of keV up to several tens of MeV. Since Rossi studied the effects caused by cosmic rays as they pass through metals, we wondered if the same process could also happen in water. We present results from a series of experiments conducted with this instrument, demonstrating its ability to detect and measure particle showers produced by the interaction of cosmic rays in water with good confidence. To the best of our knowledge, this experiment has never been conducted before. Our approach offers a low-cost and easy-to-use alternative to more sophisticated cosmic ray detectors, making it accessible to a wider range of researchers and students.

Secondary particles will always be generated in particle-to-matter interactions. The interaction of muons with matter produces various secondary particles. In this study, secondary particles produced by the interaction between muons with energies of 5, 50, 100, 200 and 500 MeV with water were analyzed using the PHITS Monte Carlo package. The muon source is placed on the surface of water that has a thickness of 1 km. The muography technique was applied by placed a detector at a depth of 1 km from the source. This detector records the secondary particles produced by the interaction. The results obtained show that this interaction produces secondary particles in the form of photons and neutrons in the detector. The number and energy of these photons and neutrons are strongly influenced by the initial energy of the muon. Muons with the lowest energy of 5 MeV produce more secondary particles than any other energy by a factor of 10. Low-energy muons travel slowly, allowing more interactions to occur and increasing the number of secondary particles in the detector. The energies of neutrons and photons in the detector are at most 3.76 MeV and 5.3 MeV, respectively.

We propose a new method to detect sub-GeV dark matter, through their scatterings from free leptons and the resulting kinematic shifts. Especially, such an experiment can detect dark matter interacting solely with muons. The experiment proposed here is for directly probing the muonphilic dark matter in a model-independent way. Its complementarity with the muon on the target proposal is similar to e.g. XENON/PandaX and ATLAS/CMS on the dark matter searches. Moreover, our proposal can work better for relatively heavy dark matter such as those in the sub-GeV region. We start with a small device of a size around 0.1–1 m, using atmospheric muons to set up a prototype. Within only one year of operation, the sensitivity on the cross-section of dark matter scattering with muons can already reach σ D ∼ 1 0 − 1 9 (− 2 0 , − 1 8) cm 2 for the dark matter mass M D = 1 0 0 (10, 1000) MeV. We can then interface the device with a high-intensity muon beam of 1 0 1 2 /bunch. Within one year, the sensitivity can reach σ D ∼ 1 0 − 2 7 (− 2 8 , − 2 6) cm 2 for M D = 1 0 0 (10, 1000) MeV. [ABSTRACT FROM AUTHOR]

This article is a brief biography and account of the scientific achievements of an inspiring Indian woman scientist, Dr Bibha Chowdhuri. Her story is one of courage, determination, and perseverance as she carved her path in a male dominated profession during a time when women faced severe obstacles even accessing basic education, let alone pursuing higher education and a career in science. [ABSTRACT FROM AUTHOR]

Cosmic ray air showers are a phenomenon that can be observed on Earth when high-energy particles from outer space collide with the Earth's atmosphere. These energetic particles in space are called primary cosmic rays and consist mainly of protons (about 89%), along with nuclei of helium (10%) and heavier nuclei (1%). Particles resulting from interactions in the atmosphere are called secondary cosmic rays. The composition of air showers in the atmosphere can include several high-energy particles such as mesons, electrons, muons, photons, and others, depending on the energy and type of the primary cosmic ray. Other than air, primary cosmic rays can also produce showers of particles when they interact with any type of matter; for instance, particle showers are also produced within the soil of planets without an atmosphere. In the same way, secondary cosmic particles can start showers of tertiary particles in any substance. In the 1930s, Bruno Rossi conducted an experiment to measure the energy loss of secondary cosmic rays passing through thin metal sheets. Surprisingly, he observed that as the thickness of the metal sheets increased, the number of particles emerging from the metal also increased. However, by adding more metal sheets, the number of particles eventually decreased. This was consistent with the expectation that cosmic rays were interacting with the atoms in the metals and losing energy to produce multiple secondary particles. In this paper, we describe a new–old approach for measuring particle showers in water using a cosmic ray telescope and Rossi's method. Our instrument consists of four Geiger–Müller tubes (GMT) arranged to detect muons and particle showers. GMT sensors are highly sensitive devices capable of detecting electrons and gamma rays with energies ranging from a few tens of keV up to several tens of MeV. Since Rossi studied the effects caused by cosmic rays as they pass through metals, we wondered if the same process could also happen in water. We present results from a series of experiments conducted with this instrument, demonstrating its ability to detect and measure particle showers produced by the interaction of cosmic rays in water with good confidence. To the best of our knowledge, this experiment has never been conducted before. Our approach offers a low-cost and easy-to-use alternative to more sophisticated cosmic ray detectors, making it accessible to a wider range of researchers and students. [ABSTRACT FROM AUTHOR]

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The recent headline-grabbing announcement of the long awaited results of the Muon g−2 experiment at the Fermi National Accelerator Laboratory (FNAL) has raised eyebrows. The international collaboration of scientists at the Fermilab claims that the measured "wobble" of the magnetic moment of the muon in the presence of a strong magnetic field defies the prediction of the Standard Model (SM). The anomalous behaviour of muons hints at physics beyond the Standard Model. A brief account of the momentous g−2 experiment and its possible implications on our understanding of the machinations of nature is presented here. [ABSTRACT FROM AUTHOR]

A search is performed for neutral non-standard-model Higgs bosons decaying to two muons in the context of the minimal supersymmetric standard model (MSSM). Proton-proton collision data recorded by the CMS experiment at the CERN Large Hadron Collider at a center-of-mass energy of 13TeVwere used, corresponding to an integrated luminosity of 35.9fb-1. The search is sensitive to neutral Higgs bosons produced via the gluon fusion process or in association with a bbquark pair. No significant deviations from the standard model expectation are observed. Upper limits at 95% confidence level are set in the context of the mmod+hand phenomenological MSSM scenarios on the parameter tanβas a function of the mass of the pseudoscalar Aboson, in the range from 130 to 600GeV. The results are also used to set a model-independent limit on the product of the branching fraction for the decay into a muon pair and the cross section for the production of a scalar neutral boson, either via gluon fusion, or in association with bquarks, in the mass range from 130 to 1000GeV.

A search is performed for neutral non-standard-model Higgs bosons decaying to two muons in the context of the minimal supersymmetric standard model (MSSM). Proton-proton collision data recorded by the CMS experiment at the CERN Large Hadron Collider at a center-of-mass energy of 13TeVwere used, corresponding to an integrated luminosity of 35.9fb-1. The search is sensitive to neutral Higgs bosons produced via the gluon fusion process or in association with a bbquark pair. No significant deviations from the standard model expectation are observed. Upper limits at 95% confidence level are set in the context of the mmod+hand phenomenological MSSM scenarios on the parameter tanβas a function of the mass of the pseudoscalar Aboson, in the range from 130 to 600GeV. The results are also used to set a model-independent limit on the product of the branching fraction for the decay into a muon pair and the cross section for the production of a scalar neutral boson, either via gluon fusion, or in association with bquarks, in the mass range from 130 to 1000GeV.

The SeaQuest spectrometer at Fermilab was designed to detect oppositely-charged pairs of muons (dimuons) produced by interactions between a 120 GeV proton beam and liquid hydrogen, liquid deuterium and solid nuclear targets. The primary physics program uses the Drell–Yan process to probe antiquark distributions in the target nucleon. The spectrometer consists of a target system, two dipole magnets and four detector stations. The upstream magnet is a closed-aperture solid iron magnet which also serves as the beam dump, while the second magnet is an open aperture magnet. Each of the detector stations consists of scintillator hodoscopes and a high-resolution tracking device. The FPGA-based trigger compares the hodoscope signals to a set of pre-programmed roads to determine if the event contains oppositely-signed, high-mass muon pairs.

Muons are usually among the most common secondary cosmic ray particles on Earth's surface. Muon research has confirmed their occurrence in a variety of locales. It has been claimed that cosmic radiation in general, and muons in particular, have disastrous consequences on biological things and electrical components on Earth and in space. According to medical sources, cosmic rays have been linked to many ailments affecting people and other creatures. Because of these issues, cosmic ray shielding has become a crucial component of this and comparative studies. Muons emitted by cosmic rays were detected using a muon telescope made of coaxial Geiger-Muller (GM) tubes. This experiment was carried out within the muon lab of Universiti Kebangsaan Malaysia (UKM) in Malaysia to examine how the cosmic ray muon count fluctuates with the shielding of metals (Copper (Cu) and Aluminium (Al)) and polyethylene. The measured muon count for each metal sample was statistically analysed. Using both metals as shielding in this experiment revealed that adding additional Cu and Al sheets reduced the muon count. Generally, the numbers drop as the thickness increases. The results suggest that Cu outperforms Al in shielding efficacy (19% vs 16%). Because Cu has a more significant density than Al, the correlation coefficient R2 for Cu = 0.9372 is greater than R2 for Al = 0.6593, indicating that the trend for Cu is better than the trend for Al in this experiment. To study the shielding capabilities of the two composites, Al/PE and Cu/PE, ten sheets of Polyethylene (PE) were gradually put individually between the Al and Cu sheets. The results showed that PE sheets slightly increased cosmic ray shielding. [ABSTRACT FROM AUTHOR]

We propose a neutrino lepton collider where the neutrino beam is generated from TeV scale muon decays. Such a device would allow for a precise measurement of the W mass based on single W production ν l → W (∗) . Although it is challenging to achieve high instantaneous luminosity with such a collider, we find that a total luminosity of 0.1 fb − 1  can already yield competitive physics results. In addition to a W mass measurement, a rich variety of physics goals could be achieved with such a collider, including W boson precision measurements, heavy leptophilic gauge boson searches and anomalous Z ν ν coupling searches. A neutrino lepton collider is both a novel idea in itself, and may also be a useful intermediate step, with less muon cooling required, towards the muon–muon collider already being pursued by the energy frontier community. A neutrino neutrino or neutrino proton collider may also be interesting future options for the high energy frontier. [ABSTRACT FROM AUTHOR]

Muons, which were discovered in the 1930s and first generated using an accelerator half a century after their discovery, are now widely used in several scientific fields such as particle physics and material science. Recent advancements in cooling techniques have reduced the phase-space volume of muon beams and driven the effort to realize muon acceleration, which has now been demonstrated for the first time. This paper reviews the current state of muon cooling and acceleration technologies. [ABSTRACT FROM AUTHOR]

Abstract Muons, which were discovered in the 1930s and first generated using an accelerator half a century after their discovery, are now widely used in several scientific fields such as particle physics and material science. Recent advancements in cooling techniques have reduced the phase-space volume of muon beams and driven the effort to realize muon acceleration, which has now been demonstrated for the first time. This paper reviews the current state of muon cooling and acceleration technologies.

The Muon g-2 Experiment at Fermilab aims to measure the muon anomalous magnetic moment with a precision of 140 parts per billion (ppb). The collaboration has published the latest measurement based on the first three Runs (collected from 2018 to 2020) in August 2023 with a precision of 200 ppb. The experiment accumulated three more years of data, from 2020 to 2023, which are currently being analyzed. This additional statistic is sufficient to achieve and possibly exceed the goal of 100 ppb of final statistical uncertainty. As the statistical error reduces, increasing attention is dedicated to studying systematic uncertainties. Among them, one source is a magnetic transient generated by the fast kickers. To center the muon orbit into its final position in the storage ring, three kickers emit a 120 ns magnetic pulse of ∼ 240 G, right after injection. This, however, induces eddy currents in the kicker aluminum structure that last for several microseconds. To measure the 10 mG magnetic perturbations generated by the eddy currents, the INFN team developed a laser magnetometer based on the Faraday effect. This article describes the technical principles, operations, and data analysis of this very sensitive device. [ABSTRACT FROM AUTHOR]

BackgroundIn the realm of cosmological ray studies employing plastic scintillation fibers, it is essential to conduct quantitative analyses of the photon number from the fiber's output pulse for the successful design of readout electronics.PurposeGiven the absence of a weak cursor setting device such as a single photon source. This study aims to quantitatively analyze the number of photons generated by photon incidents within the fiber calibrating without a weak photon source such as a single photon source.MethodsFirstly, photon numbers within weak optical pulses induced by muons in optical fibers with diameters of 1 mm and 2 mm were determinated by the calibration method that making use of inherent non-photogenerated carrier characteristics of the silicon photomultiplier tube (SiPM). Then, the Geant4 software was employed to simulate the theoretical photon yield of muons in these optical fibers, and the simulation results were compared with experimental data for validation.ResultsThe verification results indicate that the anticipated photon count in the optical pulses within fibers with diameters of the 1 mm and 2 mm fibers are 44 and 85, respectively. The deviation from the simulation results is 4.55% and 10.59%, respectively.ConclusionsThe results validate the efficiency of the low photon number measurement method, demonstrating its ability to accurately measure the photon count generated by the incident fiber without the need for additional calibration equipment. This method may extend to other scenarios that require the measurement of photon numbers in weak light pulse situations.

The positive muon (μ+) can be regarded as a light isotope of proton and has been an important tool to study radical reactions of organic compounds. Recently, muons have been applied to produce short‐lived paramagnetic species from the heavier unsaturated organic molecules including the p‐block elements. This article overviews recent muon spin rotation/resonance (μSR) studies on the phosphorus analogs of alkenes, anthracenes, and cyclobutane‐1,3‐diyls together with the fundamentals of μSR. The acyclic phosphaalkene of P=C and phosphasilenes of P=Si can accept muonium (Mu=[μ+e−]) at the heavier double bonds, and the corresponding radicals have been characterized. The phosphorus atom in 9‐phosphaanthracene, whose P=C double bond is stabilized by the peri‐substituted CF3 groups, predominantly captures muonium to provide the corresponding paramagnetic fused heterocyclic system. The peri‐trifluoromethyl groups are functional to promote the unprecedented light isotope effect of muon providing the planar three‐cyclic molecular structure to consume the increased zero‐point energy. The formally open‐shell singlet 1,3‐diphosphacyclobutane‐2,4‐diyl unit can accept muonium at the (ylidic) phosphorus or the skeletal radicalic carbon, and the corresponding paramagnetic phosphorus heterocycles can be characterized by μSR. The findings on these muoniation processes to the unsaturated phosphorus‐containing compounds will contribute not only to development of novel paramagnetic functional species but also to progress on muon science. [ABSTRACT FROM AUTHOR]

In order to study the bio-samples (aqueous solutions) using muon spin rotation and relaxation (mSR) method, the optimization of momentum of incident muon beam and selection of material for window of sample cell towards muon side are the initial steps for the mSR measurement. Rather than several experimental trials, we used to perform simulation study to optimize the momentum of muon beam and thickness of window of the sample cell. Monte Carlo simulation for optimization of momentum of monoenergetic surface muon beam in different material/thickness of window of the sample cell indicates that the Al or Kapton window of thickness less than 0.3 mm is suitable to maximize the intensity of the stopped muons (momentum between 25.8 MeV/c to 29.8 MeV/c) within 1 mm of water (bio-samples). This simulation will help to design the sample cell for the study of application of muon in life science. BIBECHANA 19(2022)160-164

We lay out a comprehensive physics case for a future high-energy muon collider, exploring a range of collision energies (from 1 to 100 TeV) and luminosities. We highlight the advantages of such a collider over proposed alternatives. We show how one can leverage both the point-like nature of the muons themselves as well as the cloud of electroweak radiation that surrounds the beam to blur the dichotomy between energy and precision in the search for new physics. The physics case is buttressed by a range of studies with applications to electroweak symmetry breaking, dark matter, and the naturalness of the weak scale. Furthermore, we make sharp connections with complementary experiments that are probing new physics effects using electric dipole moments, flavor violation, and gravitational waves. An extensive appendix provides cross section predictions as a function of the center-of-mass energy for many canonical simplified models. [ABSTRACT FROM AUTHOR]

Recently, the 'Muon g-2' experiment at Fermilab announced a new measurement of the muon's anomalous magnetic moment with better than one-in-a-million accuracy. While confirming the earlier measurement at the Brookhaven National Lab, it has also strengthened the discrepancy with the theoretical calculations, which have also been performed with the same level of accuracy. We shall discuss the physics behind the anomalous magnetic moment of the muon and some theoretical and experimental aspects of its determination. We shall also touch upon what this discrepancy, if confirmed, would mean for our knowledge of particle physics. [ABSTRACT FROM AUTHOR]

Neutrino masses are evidence of lepton flavor violation, but no violation in the interactions among the charged leptons has been observed yet. Many models of Physics Beyond the Standard Model (BSM) predict Charged Lepton Flavor Violation (CLFV) in a wide spectrum of processes with rates in reach of upcoming experiments. The experimental searches that provide the current best limits on the CLFV searches are reviewed, with a particular emphasis on the muon-based experiments that give the most stringent constraints on the BSM parameter space. The next generation of muon-based experiments (MEG-II, Mu2e, COMET, Mu3e) aims to reach improvements by many orders of magnitude with respect to the current best limits, thanks to several technological advancements. We review popular heavy BSM theories, and we present the calculations of the predicted CLFV branching ratios, focusing on the more sensitive μ → e sector. [ABSTRACT FROM AUTHOR]

COMET is an experiment at J-PARC that searches for the charged lepton flavor violating process of neutrino-less muon-to-electron conversion (μ → e conversion) in a muonic atom. The COMET Phase-I experiment, which represents the first stage of its staged approach, utilizes the cylindrical drift chamber (CDC) as the main detector to measure the momentum of electrons emitted from μ → e conversion in a 1 T magnetic field. The CDC is designed for optimal performance to achieve the best momentum resolution and effectively separate the μ → e conversion electron signal from background signals. This design entails adapting He:i-C 4 H 10 (90:10) as its chamber gas and employing an all-stereo wire configuration. This document provides a comprehensive overview of the CDC detector, encompassing design considerations, mechanical structure, construction methodologies, and results of performance evaluations conducted using cosmic-rays. [ABSTRACT FROM AUTHOR]

The CHNet-MAXI experiment (Muonic Atom X-ray and prompt gamma spectroscopy for Isotopic analysis for cultural heritage) is an INFN Cultural Heritage program funded by Scientific Commission V, aiming at selecting the best figures of merit in the isotopic analysis of lead by means of muonic atom emission. The experiment will be deployed at RIKEN-RAL facility ISIS-STFC (UK), providing a pulsed muon beams with momenta between 15 and 90 MeV/c. The CHNet-MAXI apparatus will be mainly based on a 9 HPGe detectors array and innovative scintillator detectors read-out by SiPMs for the detection of the characteristic X and gamma rays emitted by isotopically enriched targets of Pb 204, 206, 207 and 208, after negative muon irradiation at the RIKEN-RAL beamlines. A muon beam hodoscope will be used as a beam x/y profiler and as a beam intensity monitor. This detector has been designed to provide a few mm spacial resolution, and it is based on 3 mm thick scintillating fibers, each read-out by a single SiPM at one edge. The setup is meant to be portable thanks to desktop HV and innovative open-FPGA DAQ modules. All the phases of the design, assembly, and testing of the CHNet-MAXI hodoscope are illustrated. Finally, first operation tests of this new beam monitor are shown. [ABSTRACT FROM AUTHOR]

• The phenomenon of ball lightning anomalous penetration through thick metalic absorbing filters and appearance of a dark ball lightning has been investigated. • At the interaction of ball lightning with a dense medium a process of energy conversion of its own magnetic field into the kinetic energy of its charged particles occurs. • The phenomenon of anomalous passing of the ball lightning may be explained only by cascading generation of particles due to interaction of high-energy protons with absorbing filter, which causes the appearance of either negative muons and muon antineutrino or positive muons and muon neutrino. • The phenomenon of muons generation can be used to successfuly solve the problem of nuclear fusion. The phenomenon of ball lightning anomalous penetration through thick metalic absorbing filters and appearance of a dark ball lightning has been investigated. The ball lightning represents an extreme state of ionized matter in Nature. At the interaction of ball lightning with a dense medium a process of energy conversion of its own poloidal magnetic field into the kinetic energy of its charged particles occurs. The phenomenon of anomalous passage of a ball lightning within the standard model can be explained only by cascading generation of particles due to interaction of high-energy protons with an absorbing filter. The decay of pions leads either to the appearance of negative muons and muon antineutrino or positive muons and muon neutrino. This fact is confirmed by the absence of any particle imprints on the surface of this filter and the presence of a high potential of variable polarity in the region above the absorber after passing a ball lightning through it. This phenomenon of muons generation can be used to solve the problem of nuclear fusion. [ABSTRACT FROM AUTHOR]

Lepton-flavor violation (LFV) has been discovered in the neutrino sector by neutrino oscillation experiments. The minimal extension of the Standard Model (SM) to include neutrino masses allows LFV in the charged sector (CLFV) at the loop level, but at rates that are too small to be experimentally observed. Lepton-number violation (LNV) is explicitly forbidden even in the minimally extended SM, so the observation of an LNV process would be unambiguous evidence of physics beyond the SM. The search for the LNV and CLFV process μ − + N (A , Z) → e + + N ′ (A , Z − 2) (referred to as μ − → e + ) complements 0 ν β β decay searches, and is sensitive to potential flavor effects in the neutrino mass-generation mechanism. A theoretical motivation for μ − → e + is presented along with a review of the status of past μ − → e + experiments and future prospects. Special attention is paid to an uncertain and potentially dominant background for these searches, namely, radiative muon capture (RMC). The RMC high energy photon spectrum is theoretically understudied and existing measurements insufficiently constrain this portion of the spectrum, leading to potentially significant impacts on current and future μ − → e + work. [ABSTRACT FROM AUTHOR]

Short history and modern status of muon puzzle in cosmic rays of very high energies are described. Possible reasons of muon puzzle appearance are discussed. Some experimental ways of muon puzzle solution are considered. One of them is the measurement of energy characteristics of muons, which give the contribution to the observed excess of muon bundles at very high energies. Preliminary results of measurements of muon bundle energy deposit at large zenith angles are analysed. [ABSTRACT FROM AUTHOR]