BEGIN:VCALENDAR VERSION:2.0 PRODID:-//linuxsoftware.nz//NONSGML Joyous v1.4//EN BEGIN:VEVENT SUMMARY:Towards the neutrinoless double-beta decay study with SNO+: radioa ctive background characterisation with SNO+ scintillator data DTSTART:20251124T100000Z DTEND:20251124T120000Z DTSTAMP:20260925T092739Z UID:ebe2236a-a1bd-46e6-9796-46dfdc270524 SEQUENCE:2 CREATED:20251119T092139Z DESCRIPTION:0νββ is one of the most relevant processes in particle phys ics\, as it has the potential to unveil the Majorana neutrino’s nature\, and its mass generation mechanism. SNO+\, a multipurpose neutrino detecto r\, will load 130Te into its large liquid scintillator in order to search for this rare process. The aim of this thesis is to characterize all the S NO+ backgrounds that are potentially dangerous for the 0νββ signal in d ata collected before SNO+ loads Tellurium. This work included three main s teps: (T1) identification of the dataset to use\; (T2) selection of variab les to remove known backgrounds and (T3) fit of the resulting energy spect rum. (T1) was performed using a coincidence tagging technique\, which allo ws analysing an excess in 214Bi following from Rn ingress. In (T2) backgro unds like instrumentals\, muons\, externals\, coincident and pile-up event s have been rejected. The impact of these cuts was evaluated on livetime a nd efficiency. In (T3) Maximum likelihood fits were performed on data\, co llected between May 2022 and March 2023 (228.2 net livetime days). Backgro und PDFs from the 238U\, 232Th and 235U chains\, muon induced backgrounds and Solar neutrinos were used. Lastly\, the time dependence of events abov e 1.5 MeV\, was studied in intervals of 15 days\, for the three energy reg ions: [1.5\,1.8]\, [1.8\,2.2] and [2.2\,2.6] MeV to see any potential devi ation from a constant trend\, indicating a background ingress. LAST-MODIFIED:20251119T092236Z LOCATION:Online URL:http://df.vps.tecnico.ulisboa.pt/pt/eventos/towards-the-neutrinoless-d ouble-beta-decay-study-with-sno-radioactive-background-characterisation-wi th-sno-scintillator-data/ X-ALT-DESC;FMTTYPE=text/html:

0νββ is one of t he most relevant processes in particle physics\, as it has the potential t o unveil the Majorana neutrino’s nature\, and its mass generation mechan ism. SNO+\, a multipurpose neutrino detector\, will load 130Te into its la rge liquid scintillator in order to search for this rare process. The aim of this thesis is to characterize all the SNO+ backgrounds that are potent ially dangerous for the 0νββ signal in data collected before SNO+ loads Tellurium.

This work included three main steps: (T1) identifica tion of the dataset to use\; (T2) selection of variables to remove known b ackgrounds and (T3) fit of the resulting energy spectrum. (T1) was perform ed using a coincidence tagging technique\, which allows analysing an exces s in 214Bi following from Rn ingress. In (T2) backgrounds like instrumenta ls\, muons\, externals\, coincident and pile-up events have been rejected. The impact of these cuts was evaluated on livetime and efficiency.
< br/>In (T3) Maximum likelihood fits were performed on data\, collected bet ween May 2022 and March 2023 (228.2 net livetime days). Background PDFs fr om the 238U\, 232Th and 235U chains\, muon induced backgrounds and Solar n eutrinos were used. Lastly\, the time dependence of events above 1.5 MeV\, was studied in intervals of 15 days\, for the three energy regions: [1.5\ ,1.8]\, [1.8\,2.2] and [2.2\,2.6] MeV to see any potential deviation from a constant trend\, indicating a background ingress.

END:VEVENT END:VCALENDAR