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Radiative double electron capture (RDEC) observed in collisions of bare ions with atoms is a charge exchange process, during which two target electrons are captured into a bound state of the projectile and a single photon is emitted. This process could be related to the time inverse of double photoionization. For the past twenty years it has been studied, both experimentally and theoretically. However, significant discrepancies between theoretical predictions of the RDEC cross section and experimental results were noted. Here, an overview of the investigation of the RDEC process is given and various theoretical predictions are compared with experimental results.

Multielectron capture processes observed in low energy collisions of bare ions give insight into electron-electron correlations in strong fields. The main intention of this experiment is to observe radiative double electron capture (RDEC) in collisions of bare oxygen ions at energies of a few MeV/u with carbon targets. Measured results are to be compared with recent theoretical calculations.

Transmission of 3 MeV protons and 16 MeV O5+ ions through a single glass macrocapillary and a polycarbonate nanocapillary foil has been investigated. Results show that 3 MeV protons transmit through the capillary and the foils with little or no energy loss, while 16 MeV O5+ ions show transmission through the capillary and the foil with energy losses that vary with the tilt angle, and there are also changes in the charge state.

The CMS detector, including its muon system, has been operating at the CERN LHC in increasingly challenging conditions for about 15 years. The muon detector was designed to provide excellent triggering and track reconstruction for muons produced in proton–proton collisons at an instantaneous luminosity ( L ) of 1 × 10 34  cm - 2 s - 1 . During the Run 2 data-taking period (2015–2018), the LHC achieved an instantaneous luminosity of twice its design value, resulting in larger background rates and making the efficient detection of muons more difficult. While some backgrounds result from natural radioactivity, cosmic rays, and interactions of the circulating protons with residual gas in the beam pipe, the dominant source of background hits in the muon system arises from proton–proton interactions themselves. Charged hadrons leaving the calorimeters produce energy deposits in the muon chambers. In addition, high-energy particles interacting in the hadron calorimeter and forward shielding elements generate thermal neutrons, which leak out of the calorimeter and shielding structures, filling the CMS cavern. We describe the method used to measure the background rates in the various muon subsystems. These rates, in conjunction with simulations, can be used to estimate the expected backgrounds in the High-Luminosity LHC. This machine will run for at least 10 years starting in 2029 reaching an instantaneous luminosity of L = 5 × 10 34 cm -2 s -1 and increasing ultimately to L = 7.5 × 10 34 cm -2 s -1 . These background estimates have been a key ingredient for the planning and design of the muon detector upgrade.

The CMS detector, including its muon system, has been operating at the CERN LHC in increasingly challenging conditions for about 15 years. The muon detector was designed to provide excellent triggering and track reconstruction for muons produced in proton–proton collisons at an instantaneous luminosity (𝓛) of 1 x 1034 cm–2 s–1. During the Run 2 data-taking period (2015–2018), the LHC achieved an instantaneous luminosity of twice its design value, resulting in larger background rates and making the efficient detection of muons more difficult. While some backgrounds result from natural radioactivity, cosmic rays, and interactions of the circulating protons with residual gas in the beam pipe, the dominant source of background hits in the muon system arises from proton–proton interactions themselves. Charged hadrons leaving the calorimeters produce energy deposits in the muon chambers. In addition, high-energy particles interacting in the hadron calorimeter and forward shielding elements generate thermal neutrons, which leak out of the calorimeter and shielding structures, filling the CMS cavern. We describe the method used to measure the background rates in the various muon subsystems. These rates, in conjunction with simulations, can be used to estimate the expected backgrounds in the High-Luminosity LHC. This machine will run for at least 10 years starting in 2029 reaching an instantaneous luminosity of 𝓛 = 5 x 1034 cm–2 s–1 and increasing ultimately to 𝓛 = 7.5 x 1034 cm–2 s–1. These background estimates have been a key ingredient for the planning and design of the muon detector upgrade.

The CMS detector, including its muon system, has been operating at the CERN LHC in increasingly challenging conditions for about 15 years. The muon detector was designed to provide excellent triggering and track reconstruction for muons produced in proton–proton collisons at an instantaneous luminosity ($$\\mathcal {L}$$L ) of$$1 \\times 10^{34}$$1 × 10 34  cm$$^{-2}$$- 2 s$$^{-1}$$- 1 . During the Run 2 data-taking period (2015–2018), the LHC achieved an instantaneous luminosity of twice its design value, resulting in larger background rates and making the efficient detection of muons more difficult. While some backgrounds result from natural radioactivity, cosmic rays, and interactions of the circulating protons with residual gas in the beam pipe, the dominant source of background hits in the muon system arises from proton–proton interactions themselves. Charged hadrons leaving the calorimeters produce energy deposits in the muon chambers. In addition, high-energy particles interacting in the hadron calorimeter and forward shielding elements generate thermal neutrons, which leak out of the calorimeter and shielding structures, filling the CMS cavern. We describe the method used to measure the background rates in the various muon subsystems. These rates, in conjunction with simulations, can be used to estimate the expected backgrounds in the High-Luminosity LHC. This machine will run for at least 10 years starting in 2029 reaching an instantaneous luminosity of$$\\mathcal {L} = 5 \\times \\text {10}^\\text {34}\\,\\text {cm}^\\text {-2}\\,\\text {s}^\\text {-1}$$L = 5 × 10 34 cm -2 s -1 and increasing ultimately to$$\\mathcal {L} = 7.5 \\times \\text {10}^\\text {34}\\,\\text {cm}^\\text {-2}\\,\\text {s}^\\text {-1}$$L = 7.5 × 10 34 cm -2 s -1 . These background estimates have been a key ingredient for the planning and design of the muon detector upgrade.

Projectile and target K-x-ray emission associated with projectile charge changing was investigated for 12-30 MeV O super(5+) + He and Ar collisions. Negligible projectile x-ray emission was observed in coincidence with projectile electron capture or loss, while target x-ray emission correlated to projectile charge changing was seen. Differential cross sections were measured for correlated and uncorrelated x-ray emission.

X rays emitted from fluorine in single and double capture collisions with carbon have been studied. Fluorine K-x-ray emission and radiative electron capture have been observed with differences depending on the initial projectile charge state (F9+ or F8+) and whether single or double capture occurs. These origins of these differences are considered.