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A Neutrino Detector Design

Burgman, Alexander LU (2015) FYSM60 20151
Department of Physics
Abstract
Abstract

Today, the neutrino oscillation is very well established by experiment. It is described by a theoretical framework similar to that of quark mixing. Here is included a CP violating phase, delta_CP, which is the only known possible source of CP violation in the lepton sector. So far, delta_CP is completely unconstrained by experiment, and the determination of the value of delta_CP could further the search for an explanation of the matter-antimatter asymmetry observed in the Universe today.
Therefore, many next generation experiments are in development to measure delta_CP. One of the experiments under evaluation is the ESSnuSB; a proposed high intensity neutrino beam produced at the European Spallation Source (the ESS).
The ESS... (More)
Abstract

Today, the neutrino oscillation is very well established by experiment. It is described by a theoretical framework similar to that of quark mixing. Here is included a CP violating phase, delta_CP, which is the only known possible source of CP violation in the lepton sector. So far, delta_CP is completely unconstrained by experiment, and the determination of the value of delta_CP could further the search for an explanation of the matter-antimatter asymmetry observed in the Universe today.
Therefore, many next generation experiments are in development to measure delta_CP. One of the experiments under evaluation is the ESSnuSB; a proposed high intensity neutrino beam produced at the European Spallation Source (the ESS).
The ESS facility, now under construction in Lund, Sweden, would need to be upgraded in order to produce the high intensity neutrino beam. Neutrino oscillations in the nu_mu to nu_e channel could then be studied by the use of a megaton water Cherenkov detector separated from the beam source by some hundred kilometres. The phase delta_CP would thereby be determined by measuring the asymmetry between the oscillation probabilities of neutrinos and antineutrinos.
The precision of this experiment would be improved by characterising the beam close to the production point. This would be achieved by the use of a kiloton water Cherenkov detector, denoted as the Near Detector (ND), which is studied in this thesis. Firstly, concrete design recommendations for the near detector of the ESSnuSB should be found through simulations. Secondly, a set of algorithms should be developed that reconstructs the properties of a neutrino event vertex from the simulated detector response. It is essential that a muon neutrino event can be separated from an electron neutrino event, as the purpose of the ESSnuSB is to detect the transition from one flavour to the other.
The near detector is foreseen to be cylindrical in shape, with radius R_ND and length L_ND, and located at a distance z_ND from the neutrino beam production point. It will be filled with water and have photon detectors placed on the inner surface. In this project, several limits have been put on the design parameters of the ESSnuSB ND.
• The radius of the near detector: 2*R_ND > 2 m, R_ND < z_ND/50.
• The length of the near detector: L_ND > 3 m.
• The distance between the neutrino beam production and the near detector: zND > 200 m.
• The detector must have a spatial resolution smaller than 10 cm.
• The detector must have a time resolution shorter than 100 ps.
Additionally, a set of reconstruction algorithms was developed for a simplified detector environment, and the flavour identification algorithm was found to have a misidentification rate of 0.3%. (Less)
Popular Abstract (Swedish)
Att Detektera en Neutrino

I dagens Universum är allting vi kan se; alla varelser, alla planeter och alla stjärnor, uppbyggda av materia. Trots detta tror man att det i Big Bang skapades lika mycket antimateria som materia, men att all denna antimateria på något sätt har försvunnit. Ett steg på vägen att förklara detta kan vara att undersöka vissa skillnader mellan neutriner och antineutriner, vilket är de minsta och mest svårdetekterade partiklarna man idag känner till. Denna skillnad kan återfinnas i hur fort neutrinerna och antineutrinerna oscillerar, alltså hur fort de skiftar mellan att vara en av tre olika sorter (elektron-neutrino, myon-neutrino och tauon-neutrino).
Ett av de projekt som är föreslagna för att undersöka detta är... (More)
Att Detektera en Neutrino

I dagens Universum är allting vi kan se; alla varelser, alla planeter och alla stjärnor, uppbyggda av materia. Trots detta tror man att det i Big Bang skapades lika mycket antimateria som materia, men att all denna antimateria på något sätt har försvunnit. Ett steg på vägen att förklara detta kan vara att undersöka vissa skillnader mellan neutriner och antineutriner, vilket är de minsta och mest svårdetekterade partiklarna man idag känner till. Denna skillnad kan återfinnas i hur fort neutrinerna och antineutrinerna oscillerar, alltså hur fort de skiftar mellan att vara en av tre olika sorter (elektron-neutrino, myon-neutrino och tauon-neutrino).
Ett av de projekt som är föreslagna för att undersöka detta är forskningsanläggningen ESSnuSB, vilket skulle vara ett tillägg till ESS-anläggningen i Lund. Vid ESSnuSB skulle man då generera en stråle av neutriner som sedan skulle passera genom jorden till en gruva i Mellansverige, ca 500 km ifrån punkten där de genererats. I gruvan ska då en så kallad fjärrdetektor placeras, en enorm vattentank med ljusmätare på insidan, i syfte att detektera de neutriner som når den.
Utöver fjärrdetektorn behöver man även ha placerat en så kallad närdetektor i nära anslutning till punkten där neutrinerna produceras. Närdetektorn kommer att vara en vattenfylld cylinderformad tank med ljusmätare på insidan, och ligga i samma riktning som neutrinostrålen. Den kommer att vara placerad någonstans mellan 50 och 500 m ifrån neutrinernas produktionspunkt, och kommer på insidan vara klädd med en stor mängd ljusdetektorer. Med hjälp av närdetektorn kan man kontrollera att neutrinostrålen har de egenskaper som man tror strax efter dess produktion.
Syftet med det examensarbete som utförts var tudelat. För det första ska konkreta rekommendationer tas fram för hur närdetektorn ska utformas, d.v.s. begränsningar i bl.a. dess storlek och placering. För det andra ska en algorithm utvecklas som kan avgöra vilken sort en neutrino har när den registreras i detektorn. Detta är mycket viktigt, då man vill finna övergången, eller oscillationen, från en sort till en annan. Dessa två mål nås genom att simulera hur detektorn beter sig när den registrerar en neutrino.
Examensarbetet har visat att närdetektorn måste uppfylla följande villkor för att kunna detektera neutriner på ett tillfredsställande sätt:
• Närdetektorn bör ha en diameter betydligt större än 2 m, exempelvis 8 m.
• Närdetektorn bör vara betydligt längre än 3 m, exempelvis 10 m.
• Närdetektorn bör vara placerad längre ifrån neutrinernas produktionspunkt än 200 m.
• Närdetektorn bör dessutom vara placerad längre ifrån produktionspunkten än 25 gånger dess diameter, på grund av strålens spridning.
• Ljusdetektorerna på insidan av närdetektorn bör kunna upplösa avstånd på minst 10 cm.
• Ljusdetektorerna på insidan av närdetektorn bör kunna upplösa tidsskillnader på minst 100 ps.
Utöver detta har en algoritm utvecklats som kan identifiera vilken sort av neutrino som detekteras. Denna algorithm ger en felidentifikation för endast 0.3% av detektionerna.
Detta examensarbete utgör därmed den första studien som gjorts på utformningen av närdetektorn för ESSnuSB, och lägger således grunden för vidare utveckling av denna detektor. (Less)
Please use this url to cite or link to this publication:
author
Burgman, Alexander LU
supervisor
organization
alternative title
A Simulation Study on the Design of the Cherenkov Near Detector of the Proposed ESSnuSB
course
FYSM60 20151
year
type
H2 - Master's Degree (Two Years)
subject
keywords
neutrino, neutrinos, oscillation, CP violation, muon, electron, ESSnuSB, ESS, Cherenkov, detector, near detector, simulation, reconstruction, identification, particle, partikelfysik, thesis, master's, master, Burgman, Alexander
language
English
id
5466261
date added to LUP
2015-06-07 13:19:36
date last changed
2015-06-07 13:19:36
@misc{5466261,
  abstract     = {Abstract

Today, the neutrino oscillation is very well established by experiment. It is described by a theoretical framework similar to that of quark mixing. Here is included a CP violating phase, delta_CP, which is the only known possible source of CP violation in the lepton sector. So far, delta_CP is completely unconstrained by experiment, and the determination of the value of delta_CP could further the search for an explanation of the matter-antimatter asymmetry observed in the Universe today.
Therefore, many next generation experiments are in development to measure delta_CP. One of the experiments under evaluation is the ESSnuSB; a proposed high intensity neutrino beam produced at the European Spallation Source (the ESS).
The ESS facility, now under construction in Lund, Sweden, would need to be upgraded in order to produce the high intensity neutrino beam. Neutrino oscillations in the nu_mu to nu_e channel could then be studied by the use of a megaton water Cherenkov detector separated from the beam source by some hundred kilometres. The phase delta_CP would thereby be determined by measuring the asymmetry between the oscillation probabilities of neutrinos and antineutrinos.
The precision of this experiment would be improved by characterising the beam close to the production point. This would be achieved by the use of a kiloton water Cherenkov detector, denoted as the Near Detector (ND), which is studied in this thesis. Firstly, concrete design recommendations for the near detector of the ESSnuSB should be found through simulations. Secondly, a set of algorithms should be developed that reconstructs the properties of a neutrino event vertex from the simulated detector response. It is essential that a muon neutrino event can be separated from an electron neutrino event, as the purpose of the ESSnuSB is to detect the transition from one flavour to the other.
The near detector is foreseen to be cylindrical in shape, with radius R_ND and length L_ND, and located at a distance z_ND from the neutrino beam production point. It will be filled with water and have photon detectors placed on the inner surface. In this project, several limits have been put on the design parameters of the ESSnuSB ND.
• The radius of the near detector: 2*R_ND > 2 m, R_ND < z_ND/50.
• The length of the near detector: L_ND > 3 m.
• The distance between the neutrino beam production and the near detector: zND > 200 m.
• The detector must have a spatial resolution smaller than 10 cm.
• The detector must have a time resolution shorter than 100 ps.
Additionally, a set of reconstruction algorithms was developed for a simplified detector environment, and the flavour identification algorithm was found to have a misidentification rate of 0.3%.},
  author       = {Burgman, Alexander},
  keyword      = {neutrino,neutrinos,oscillation,CP violation,muon,electron,ESSnuSB,ESS,Cherenkov,detector,near detector,simulation,reconstruction,identification,particle,partikelfysik,thesis,master's,master,Burgman,Alexander},
  language     = {eng},
  note         = {Student Paper},
  title        = {A Neutrino Detector Design},
  year         = {2015},
}