Group for Cooperation with CERN

Student projects

• Feasibility studies of hadron channels in deep inelastic scattering

  | project/SFG | Supervisor: Jan Matoušek |
  Our group is studying the distributions of charged hadrons in deep inelastic scattering to learn about the quarks within the nucleon (see Talks). The hadrons are mainly a mix of charged pions and kaons. This needs to be taken into account in the interpretation of the measurements. Identification of the hadrons would make the interpretation easier, allowing better quark flavour separation. One way is identifying the charged hadrons using Cherenkov effect, another way is looking at short-lived hadrons like ρ⁰, φ, π⁰, K⁰, Λ or J/ψ via their decay products. It is also desirable to understand to what extent the hadrons from these decays enter the standard charged hadrons sample and how they influence it. The aim of this study is to analyse COMPASS 2016 and 2022 data in a simplified ROOT format, checking the yields and simple distributions of the short-lived hadrons to evaluate the feasibility of their further studies.

• Monte Carlo studies of hadron production in deep inelastic scattering

  | project/SFG | bachelor thesis | Supervisor: Jan Matoušek |
  Our group is studying the distributions of charged hadrons in deep inelastic scattering to learn about the quarks within the nucleon (see Talks). However, the distributions of final state hadrons depend not only on the nucleon structure, but also on the fragmentation (hadronization) process in which the interaction between the struck quark and the spectator quarks give rise to the final state hadrons. In addition, some of the hadrons decay soon afer, so part of the hadrons reaching the detectors are secondary. These effects can be studied in Monte Carlo simulations. Recently, a first plugin for fragmentation of polarised quarks has been developed for the Pythia event generator by our Trieste colleague [StringSpinner]. As we are interested in correlations within the nucleon involving quark spins, we would like to test and start using this model to better understand our experimental observations.

• RICH detector performance studies

  | project/SFG | bachelor thesis | Supervisor: Jan Matoušek |
  RICH detector uses the Cherenkov effect to identify charged particles by determining their mass. In fact, it measures their velocity, which is then combined with the momentum measured in a magnetic spectrometer. The particle identification is important for correct interpretation of measurements of hadron production in deep inelastic scattering at COMPASS and it is vital for the measurement of antiproton production cross section at AMBER. Knowing the efficiency and purity of the particle identification as a function of relevant kinematic variables is necessary for such measurements.

• Development of software tools for detector efficiency simulation

  | project/SFG | Supervisor: Jan Matoušek |
  Detector efficiency may vary across the detector plane. There may be broken readout cards serving a group of wires or strips, less efficient photomultipliers at certain sctintillating hodoscope slabs, effects of space charge or ageing in high-occupancy central regions of wire chambers etc. These effects have impact on the experimental acceptance for particles. Therefore, 2D detector efficiencies were measured and are being used in Monte Carlo simulations for the acceptance determination at COMPASS. However, unbiased measurement of the efficiency is computationally very intensive. To take into account variation of the efficiency in time, corrections could be determined based on the so-called pseudo-efficiency, which is biased, but much less demanding to obtain. The goal of this project would be to develop a tool for the application of such corrections and in general for easy 2D efficiency comparison and manipulation.

• Trigger efficiency measurement for AMBER antiproton production

  | bachelor thesis | diploma thesis | Supervisor: Jan Matoušek, Tomáš Klásek |
  At AMBER, we are measuring the cross section for producing antiprotons in proton-He, proton-H and proton-D interactions. The trigger decides whether an event is recorded or not. Therefore, its efficiency directly impacts the measured cross section and needs to be precisely known. It can be determined analysing events recorded with another trigger system and checking, how often the physics trigger occured in events that have the desired signature.

• Elastic events contamination and re-interactions in AMBER antiproton production measurement

  | project/SFG | bachelor thesis | Supervisor: Jan Matoušek, Tomáš Klásek |
  At AMBER, we are measuring the cross section for producing antiprotons in proton-He, proton-H and proton-D interactions. A possible background from elastic scattering and re-interactions in the target is to be studied using a Monte Carlo simulation.

• Elastic and inelastic scattering demonstrator model

  | project/SFG | Supervisor: Jan Matoušek |
  The goal of this project is to develop a computer simulation that could serve as a demonstrator to explain the idea of scattering experiments, elastic and inelastic scattering and the parton model to students.

• K⁰ and Λ production in deep inelastic scattering

  | bachelor thesis | diploma thesis | Supervisor: Jan Matoušek |
  Our group is studying the distributions of charged hadrons in deep inelastic scattering to learn about the quarks within the nucleon (see Talks). The hadrons are mainly a mix of charged pions and kaons. This needs to be taken into account in the interpretation of the measurements. Identification of the hadrons would make the interpretation easier, allowing better quark flavour separation. One way is identifying the charged hadrons using Cherenkov effect, another way is looking at the so-called V0 particles K⁰ and Λ via their decay products.

• ρ⁰ and φ production in deep inelastic scattering

  | bachelor thesis | diploma thesis | Supervisor: Jan Matoušek |
  Our group is studying the distributions of charged hadrons in deep inelastic scattering to learn about the quarks within the nucleon (see Talks). The hadrons are mainly a mix of charged pions and kaons. This needs to be taken into account in the interpretation of the measurements. Identification of the hadrons would make the interpretation easier, allowing better quark flavour separation. One way is identifying the charged hadrons using Cherenkov effect, another way is looking at ρ⁰ and φ resonances via their decay products. It is also desirable to understand to what extent the hadrons from these decays enter the standard charged hadrons sample (clearly significantly in the case of ρ⁰) and how they influence it.

• π⁰ production in deep inelastic scattering

  | bachelor thesis | diploma thesis | Supervisor: Jan Matoušek |
  Our group is studying the distributions of charged hadrons in deep inelastic scattering to learn about the quarks within the nucleon (see Talks). About 70% of the hadrons are charged pions. It may be interesting to expand this studies to neutral pions, which decay into two photons immediately after being born. As COMPASS experiment is equipped with electromagnetic calorimeters, the π⁰ can be reconstructed.

• Azimuthal distributions in J/ψ leptoproduction

  | bachelor thesis | diploma thesis | Supervisor: Jan Matoušek |
  J/ψ particle is composed of charm quark and antiquark. As these quarks are virtually not present in the nucleon, one of the possible mechanisms of its creation os the photon–gluon fusion. Like the azimuthal distributions of light hadrons can tell us about the quark distributions in the nucleon, the J/ψ can allow us to reach the gluon distributions. SIS