Near detector simulation studies for CP violation discovery with ESSnuSB
(2019) FYSK02 20191Nuclear physics
Department of Physics
- Abstract
- The neutrino oscillation experiment ESSnuSB aims to measure the CP violation phase in the lepton sector with an intense neutrino beam produced at ESS. If the CP violation is discovered, then the matter-antimatter asymmetry of the Universe can be possibly explained. In order to do this, a design study of a water Cherenkov near detector was carried out, and its geometrical parameters such as the tank size and the PMT size were evaluated using a dedicated simulation software and a previously developed reconstruction algorithm. The reconstruction results show that the electrons are less likely to be misidentified than the muons, and the misidentification percentages for electrons were highly dependent on the tank size rather than the PMT size.... (More)
- The neutrino oscillation experiment ESSnuSB aims to measure the CP violation phase in the lepton sector with an intense neutrino beam produced at ESS. If the CP violation is discovered, then the matter-antimatter asymmetry of the Universe can be possibly explained. In order to do this, a design study of a water Cherenkov near detector was carried out, and its geometrical parameters such as the tank size and the PMT size were evaluated using a dedicated simulation software and a previously developed reconstruction algorithm. The reconstruction results show that the electrons are less likely to be misidentified than the muons, and the misidentification percentages for electrons were highly dependent on the tank size rather than the PMT size. On the other hand, the misidentification percentages for muons were independent of both the tank size and the PMT size. Instead, other geometrical effects played a more dominant role in particle misidentification. In order to lower the misidentification percentages, more sophisticated selection cuts are suggested. Finally, 2D mappings of the input lepton energies versus the reconstructed lepton energies, known as migration matrices, were constructed for both muons and electrons. Dedicated tunes of the modified detector geometries may address a discrepancy between the input lepton energy and the reconstructed energy, while improving the particle identification accuracy. These results provided guidance on more comprehensive design studies of the near detector. (Less)
- Popular Abstract
- Particle physics has developed dramatically over the last 40 years. However, there is a still a question left. Why can we only see matter in the universe and almost no antimatter? Scientists are saying that there were equal amounts of matter and antimatter produced during the explosion ‘Big Bang’. Matter and anti-matter have mirror image properties so that anti-matter should always be created alongside is matter created. However it seems that might some 'magic' may have occurred at certain points of the early of the Universe that made anti-particles wear an invisibility cloak. The spell of this magic is called ‘CP violation’.
We say that CP symmetry consists of two types of transformations where 'charge conjugation' transforms particles... (More) - Particle physics has developed dramatically over the last 40 years. However, there is a still a question left. Why can we only see matter in the universe and almost no antimatter? Scientists are saying that there were equal amounts of matter and antimatter produced during the explosion ‘Big Bang’. Matter and anti-matter have mirror image properties so that anti-matter should always be created alongside is matter created. However it seems that might some 'magic' may have occurred at certain points of the early of the Universe that made anti-particles wear an invisibility cloak. The spell of this magic is called ‘CP violation’.
We say that CP symmetry consists of two types of transformations where 'charge conjugation' transforms particles into antiparticles and the 'parity transformation' converts left-handed particles into the right-handed antiparticles, but these symmetries can be broken and cause the matter-antimatter asymmetry in the universe. Therefore, CP violation is one of the most important factors for our understanding of the secrets of the universe. This causes another question. How we can detect this CP violation? The answer is e.g. by measuring neutrino oscillations.
It was assumed that the neutrino is a massless particle according to the Standard Model in particle physics but, in the year 2015 the Nobel prize was awarded to two scientists who contributed to the discovery of oscillations, and proved that the neutrino is actually a massive particle. The neutrino is hard to detect because it is very unlikely to interact with other matter. Three types of neutrinos, the muon neutrino, the tau neutrino and the electron neutrino exist, and surprisingly each neutrino can be transformed into the another type. Neutrino oscillation was first detected by the Super-Kamiokande experiment in 1998, where, the number of upward-going atmospheric muon neutrinos produced in collisions between cosmic rays and nuclei in earth’s atmosphere was only half of the number of down-going neutrinos.
Although the discovery of the Higgs boson in 2012 was a great supporting evidence for the Standard Model of the elementary particles, the discovery of massive neutrinos and their oscillations into other flavors proved that the Standard Model is not complete theory . We need new theories beyond the Standard Model and additional experiments. One of the planned experiments is ESSnuSB, and a preliminary design study of its detector was carried out. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/8984059
- author
- Yeo, In-Pyo LU
- supervisor
-
- Joochun Park LU
- Joakim Cederkäll LU
- organization
- course
- FYSK02 20191
- year
- 2019
- type
- M2 - Bachelor Degree
- subject
- language
- English
- id
- 8984059
- date added to LUP
- 2019-06-25 09:25:36
- date last changed
- 2019-06-25 09:25:36
@misc{8984059,
abstract = {{The neutrino oscillation experiment ESSnuSB aims to measure the CP violation phase in the lepton sector with an intense neutrino beam produced at ESS. If the CP violation is discovered, then the matter-antimatter asymmetry of the Universe can be possibly explained. In order to do this, a design study of a water Cherenkov near detector was carried out, and its geometrical parameters such as the tank size and the PMT size were evaluated using a dedicated simulation software and a previously developed reconstruction algorithm. The reconstruction results show that the electrons are less likely to be misidentified than the muons, and the misidentification percentages for electrons were highly dependent on the tank size rather than the PMT size. On the other hand, the misidentification percentages for muons were independent of both the tank size and the PMT size. Instead, other geometrical effects played a more dominant role in particle misidentification. In order to lower the misidentification percentages, more sophisticated selection cuts are suggested. Finally, 2D mappings of the input lepton energies versus the reconstructed lepton energies, known as migration matrices, were constructed for both muons and electrons. Dedicated tunes of the modified detector geometries may address a discrepancy between the input lepton energy and the reconstructed energy, while improving the particle identification accuracy. These results provided guidance on more comprehensive design studies of the near detector.}},
author = {{Yeo, In-Pyo}},
language = {{eng}},
note = {{Student Paper}},
title = {{Near detector simulation studies for CP violation discovery with ESSnuSB}},
year = {{2019}},
}