The upgraded Large Hadron Collider beauty (LHCb) detector will provide data taken in Run3 at the instantaneous luminosity of proton-proton collisions increased to 2⋅1033 cm-2s-1 at energies of up to ...14 TeV. To ensure the safe operation of the experiment, a new beam and background Radiation Monitoring System (RMS-R3) was built. RMS-R3 is based on metal-foil detector technology developed at the Institute for Nuclear Research, National Academy of Sciences of Ukraine (Kyiv, Ukraine). The system comprises four detector modules with two sensors in each. Their frequency response is proportional to the flux of incident charged particles. The modules are located around the beam pipe at a distance of 2.2 m from the interaction point. The results measured during the Run3 in 2022 testify to the reliable operation of the system. Applying the asymmetry method, high-accuracy data were obtained on the localization of the interactions region and the beam and background contribution.
The upgraded LHCb detector allows the collection of data in the third physics run at instantaneous luminosity up to 2·1033 cm-2s-1 in proton-proton collisions at energy up to 14 TeV. A set of ...high-speed monitoring systems, including the RMS-R3 system, which monitors the nuclear interactions in the interaction region of the IP-8 (LHCb) experiment and the background, ensures the effective conduct of the experiment. An important functional characteristic of this system is the observation of luminosity stability over a wide dynamic range, which in its upper limit provides a linear response at ten times the nominal luminosity. This paper illustrates a new functionality feature of the RMS-R3, which is its ability to produce highly accurate data on the localization of the physical events of nuclear collisions in the interaction region of the experiment. The data measured in 2022 - 2023 allow us to observe the parameter variation impact of the nucleus-nucleus average number interactions in a single bunch crossing of the beams, the change of the state of the VELO detector and the injection of gaseous target SMOG2 by different gases.
For the feasibility studies of spatially fractionated hadron therapy prototypes of the equipment for hadron minibeams shaping and monitoring have been designed, built and tested. The collimators ...design was based on Monte Carlo simulations (Gate v.6.2). Slit and matrix collimators were used for minibeams shaping. Gafchromic films, micropixel detectors Timepix in a hybrid as well as metal mode were tested for measuring hadrons intensity distribution in minibeams. An overall beam profile was measured by the metal microstrip detector. The performance of a mini-beams shaping and monitoring equipment was characterized exploring low energy protons at the KINR Tandem generator as well as high energy carbon and oxygen ion beams at HIT (Heidelberg). The results demonstrate reliable performance of the tested equipment for shaping and imaging hadron mini-beam structures.
Double-sided silicon microstrip sensors will be used in the Silicon Tracking System of the CBM experiment. During experimental run they will be exposed to a radiation field of up to 1x1014 1 MeV neq ...cm-2. Radiation tolerance studies were made on prototypes from two different vendors. Results from these prototype detectors before and after irradiation to twice that neutron fluence are discussed.
A system for quality assessment of micropixel detectors is presented. The system includes a laser scanning microprobe and a setup for studying the response of micro detectors to minimum ionizing ...particles. The results of the validation of the developed system indicate its suitability for assessing the quality of the latest monolithic active pixel sensors (MAPS), promising elements of large-area tracking systems for future high-energy physics experiments. Comparison of MAPS with the double-sided microstrip detectors of the CBM experiment (FAIR, Darmstadt) indicates the feasibility of the upgrade of its Silicon Tracking System using MAPS.
Characterization studies of the metal micro-detector TimePix measuring dose distribution at the Minibeam Radiation Therapy setup (Bio-Medical Beamline ID17, ESRF) were performed. The results obtained ...for high intensity synchrotron radiation minibeams illustrate an excellent performance of the TimePix providing in real time 2D image of the dose distribution over many beams in a 14×14mm2 area. Peak-to-Valley–Dose–Ratios measured by TimePix and gafhromic films agree well.
Design of collimators and their effectiveness for the purposes of the fractionated mini-beam hadron radiation therapy were evaluated by Monte Carlo simulations. The calculations have been performed ...for proton, carbon and oxygen ion beams at the energies relevant for medical applications. Micropixel metal and hybrid detectors were tested for measuring charged particles intensity distribution in multi-beam structures shaped by slit or matrix collimators exploring low energy proton beam at the Tandem generator (INR NASU, Kyiv). The results obtained illustrate reliable performance of the designed collimators as well as hybrid and metal microdetectors for measuring and imaging in real time the proton intensity distribution over mini-beam structures.
Abstract
The standard model of particle physics currently provides our best description of fundamental particles and their interactions. The theory predicts that the different charged leptons, the ...electron, muon and tau, have identical electroweak interaction strengths. Previous measurements have shown that a wide range of particle decays are consistent with this principle of lepton universality. This article presents evidence for the breaking of lepton universality in beauty-quark decays, with a significance of 3.1 standard deviations, based on proton–proton collision data collected with the LHCb detector at CERN’s Large Hadron Collider. The measurements are of processes in which a beauty meson transforms into a strange meson with the emission of either an electron and a positron, or a muon and an antimuon. If confirmed by future measurements, this violation of lepton universality would imply physics beyond the standard model, such as a new fundamental interaction between quarks and leptons.
Study of the doubly charmed tetraquark Tcc Abdelmotteleb, A. S. W; Ajaltouni, Z; Andreianov, A ...
Nature communications,
12/2022, Letnik:
13, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Quantum chromodynamics, the theory of the strong force, describes interactions of coloured quarks and gluons and the formation of hadronic matter. Conventional hadronic matter consists of baryons and ...mesons made of three quarks and quark-antiquark pairs, respectively. Particles with an alternative quark content are known as exotic states. Here a study is reported of an exotic narrow state in the D0D0π+ mass spectrum just below the D*+D0 mass threshold produced in proton-proton collisions collected with the LHCb detector at the Large Hadron Collider. The state is consistent with the ground isoscalar Tcc+ tetraquark with a quark content of ccu¯d¯ and spin-parity quantum numbers JP = 1+. Study of the DD mass spectra disfavours interpretation of the resonance as the isovector state. The decay structure via intermediate off-shell D*+ mesons is consistent with the observed D0π+ mass distribution. To analyse the mass of the resonance and its coupling to the D*D system, a dedicated model is developed under the assumption of an isoscalar axial-vector Tcc+ state decaying to the D*D channel. Using this model, resonance parameters including the pole position, scattering length, effective range and compositeness are determined to reveal important information about the nature of the Tcc+ state. In addition, an unexpected dependence of the production rate on track multiplicity is observed.The existence and properties of tetraquark states with two heavy quarks and two light antiquarks have been widely debated. Here, the authors use a unitarized model to study the properties of an exotic narrow state compatible with a doubly charmed tetraquark.
A narrow pentaquark state, Pc(4312)+, decaying to J/ψp, is discovered with a statistical significance of 7.3σ in a data sample of Λb0→J/ψpK− decays, which is an order of magnitude larger than that ...previously analyzed by the LHCb Collaboration. The Pc(4450)+ pentaquark structure formerly reported by LHCb is confirmed and observed to consist of two narrow overlapping peaks, Pc(4440)+ and Pc(4457)+, where the statistical significance of this two-peak interpretation is 5.4σ. The proximity of the Σc+D¯0 and Σc+D¯*0 thresholds to the observed narrow peaks suggests that they play an important role in the dynamics of these states.