Difference between revisions of "Master student Projects"
Jump to navigation
Jump to search
| Line 203: | Line 203: | ||
''' Research description: ''' | ''' Research description: ''' | ||
During the R&D phase for the LHCb VELO Upgrade detector a few sensor prototypes were irradiated to the extreme fluence expected to be achieved during the detector lifetime. These samples were tested using high energy particles at the SPS facility at CERN with their trajectories reconstructed by the Timepix3 telescope. A preliminary analysis revealed that at the highest irradiation levels the amount of signal observed is higher than expected, and even larger than the signal obtained at lower doses. At the Device Under Test (DUT) position inside the telescope, the spatial resolution attained by this system is below 2 um. This means that a detailed analysis can be performed in order to study where and how this signal amplification happens within the 55x55 um^2 pixel cell. This project involves analysing the telescope and DUT data to investigate the charge multiplication mechanism at the microscopic level. | During the R&D phase for the LHCb VELO Upgrade detector a few sensor prototypes were irradiated to the extreme fluence expected to be achieved during the detector lifetime. These samples were tested using high energy particles at the SPS facility at CERN with their trajectories reconstructed by the Timepix3 telescope. A preliminary analysis revealed that at the highest irradiation levels the amount of signal observed is higher than expected, and even larger than the signal obtained at lower doses. At the Device Under Test (DUT) position inside the telescope, the spatial resolution attained by this system is below 2 um. This means that a detailed analysis can be performed in order to study where and how this signal amplification happens within the 55x55 um^2 pixel cell. This project involves analysing the telescope and DUT data to investigate the charge multiplication mechanism at the microscopic level. | ||
| + | |||
| + | |||
| + | {| border="1" cellpadding="2" cellspacing="0" | ||
| + | |- | ||
| + | ! style="background:#3399ff;" | <font color=#ffffff> 11) Searching for lepton-universality violation with ?b ? ?l+l? decays </font> | ||
| + | |} | ||
| + | |||
| + | '''Supervisor''' : Niels Tuning (staff), Lex Greeven (PhD), Mick Mulder (postdoc@CERN) | ||
| + | |||
| + | '''Research Description:''' | ||
| + | A current �hot topic� in the field of particle physics is the potential violation of lepton-universality. At the LHCb experiment, lepton-universality tests are performed by looking at the ratio of decays | ||
| + | into muons and into electrons/taus. Recent measurements in meson modes show hints (2 ? 3?) of lepton non-universality. Baryonic modes, however, have been less studied and provide an independent test of lepton-universality. At Nikhef, we study the decay ?b ? ?l+l- , where l can be an electron or a muon. There are two possible project topics: | ||
| + | |||
| + | 1. Identifying novel analysis techniques in the high di-lepton invariant mass region. Electrons in this region undergo more Bremsstrahlung, and therefore have a worse momentum resolution, | ||
| + | meaning background from the resonant ? (2s) mode can leak into our signal. Since we expect most of our signal in this region, it is important to improve this, most likely using machine learning techniques. | ||
| + | |||
| + | 2. Identifying, simulating, and setting up a rejection for partially reconstructed ?0b ? ?*l+l? backgrounds. By not fully reconstructing the excited ?0, we can mis-reconstruct it as a signal | ||
| + | candidate. Machine learning techniques could be explored. | ||
| + | |||
| + | |||
| + | ''' Relevant information: ''' | ||
| + | |||
| + | [1] [https://arxiv.org/abs/1903.09252 arXiv:1903.09252] LHCb coll., Search for lepton-universality violation in B+?K+l+l?decays | ||
| + | |||
| + | [2] [https://arxiv.org/abs/1705.05802 arXiv:1903.09252] LHCb coll., Test of lepton universality with B0?K*0l+l? decays | ||
| + | |||
| + | [3] [https://arxiv.org/abs/1912.08139 arXiv:1912.08139] LHCb coll., Test of lepton universality with ?b?pKl+l? decays | ||
| + | |||
| + | [4] [https://arxiv.org/abs/1602.01399 arXiv:1602.01399] W. Detmold and S. Meinel, ?b??l+l? form factors, differential branching fraction, and angular observables from lattice QCD with relativistic b-quarks | ||
| + | |||