title: Search for Dark Matter and other beyond the Standard Model physics with XENON1T and XENONnT
Creators: name: Althüser, Lutz
Publisher: name: University of Muenster, Institutional Repository MIAMI
Year: 2024
Subjects: subject: 530 Physics

description: Trotz zahlreicher Hinweise für die Existenz der Dunklen Materie, bleiben ihre Eigenschaften ein Rätsel und bildeen eines der Hauptthemen der modernen Teilchenphysik. Das XENON Dark Matter Projekt beabsichtigt den direkten Nachweis dieser hypothetischen Dunklen Materie mit immer empfindlicheren Detektoren. In dieser Arbeit wird untersucht ob der Überschuss an Elektron-Rückstößen in XENON1T auf inelastische Streuung von Dunkler Materie an Elektronen in der Xenon Detektromasse zurückzuführen ist. Frühere Analysen wurden nur mit der Energieinformation der Rückstöße durchgeführt, wobei die Zeitinformationen vernachlässigt wurden. Eine Analyse mit der Zeitinformation führt zu verschiedenen Verbesserungen gegenüber vorheriger Veröffentlichung. Die Dicke der PTFE-Detektorwand von XENONnT wurde hinsichtlich ihrer Lichtdichtigkeit und Massenreduzierung optimiert. Diese Arbeit stellt ein Modell für die Lichtdurchlässigkeit bei Xenon-Szintillationslicht und die optimale Detektorwandstärke vor.
description: Despite numerous evidence for the existence of Dark Matter, its nature remains a mystery and is one of the main topics of modern particle physics. The XENON Dark Matter project is aiming for the direct detection of the hypothetical Dark Matter particles with increasingly sensitive detectors. This work investigates the possibility that the excess of electronic recoil events in XENON1T originates from inelastic scattering of Dark Matter off electrons in the xenon target. Previous analyses were only performed by investigating the electronic recoil energy spectra, neglecting most of the time information. This work describes the re-analysis focusing on the time information leading to various improvements over the previous analyses. The thickness of the XENONnT PTFE detector wall is optimized for light tightness and mass reduction. This work presents a modell for the light transmission at xenon scintillation light wavelengths and the optimal detector wall thickness.
description: 1 Introduction ..... 1
2 Search for dark matter ..... 3
2.1 Evidence and particle candidates ..... 3
2.2 Direct detection ..... 7
2.3 Annual modulations ..... 13
3 The XENON dark matter project ..... 17
3.1 Xenon dual-phase time projection chambers ..... 18
3.2 The XENON1T experiment ..... 27
3.3 Results from the XENON1T experiment ..... 34
3.4 Upgrade to the XENONnT experiment ..... 41
4 VUV transmission of PTFE ..... 45
4.1 Münster reflectance and transmittance chamber ..... 47
4.2 Setup preparation and calibration ..... 52
4.2.1 Monochromator calibration ..... 52
4.2.2 PMT and sample holder alignment ..... 58
4.2.3 PTFE samples ..... 63
4.3 Setup systematics ..... 64
4.4 PTFE transmission measurements ..... 68
4.5 Transmission phenomena ..... 74
4.5.1 Beer-Lambert law ..... 75
4.5.2 Kubelka and Munk ..... 75
4.6 Results ..... 76
4.7 Summary and discussion ..... 79
5 Optical simulations for the XENON detectors ..... 83
5.1 Optical simulations for XENON ..... 84
5.2 XENON1T optical photon response ..... 91
5.3 Developments for the XENONnT experiment ..... 93
5.4 Summary and discussion ..... 100
6 Annual modulation of inelastic DM-electron scattering ..... 103
6.1 Inelastic DM-electron scattering ..... 105
6.2 Dark photon model and scattering process ..... 109
6.3 Modeling of the XENON experiments ..... 112
6.4 Simplified annual modulation model ..... 11
6.5 Analysis methods and results ..... 120
6.6 Summary and discussion ..... 125
7 Time stability and modulation analysis of the XENON1T electronic recoil data ..... 127
7.1 Data selection, energy calibration and fiducial volume ..... 129
7.1.1 Science data and detector livetime ..... 129
7.1.2 Detector calibration ..... 134
7.1.3 Fiducial volume definition ..... 137
7.2 Cut stability and acceptances ..... 139
7.2.1 Crosscheck with previous studies ..... 142
7.2.2 Time dependence evaluation ..... 145
7.2.3 Redefinition of the S2 pattern likelihood cut ..... 147
7.2.4 Final cut acceptances ..... 151
7.2.5 Event distributions after applying cuts ..... 159
7.3 Detector stability ..... 161
7.4 Background models ..... 174
7.4.1 Time-independent backgrounds ..... 178
7.4.2 Materials backgrounds ..... 184
7.4.3 Neutron activated backgrounds ..... 187
7.4.4 Other time-dependent backgrounds ..... 193
7.5 Statistical methods ..... 198
7.6 Background only fit ..... 206
7.7 Searches for other time signatures ..... 223
7.8 Summary and discussion ..... 232
8 WIMP and other rare event search results from the XENONnT experiment ..... 235
8.1 Search for new physics in electronic recoil data ..... 236
8.2 First dark matter search with nuclear recoils ..... 241
9 Conclusion and Outlook ..... 247
Bibliography ..... 251
List of abbreviations ..... 273
Nomenclature ..... 277
A Appendix ..... 279
A.1 Working principle of the XENONnT detector ..... 279
A.2 VUV transmission of PTFE ..... 280
A.3 Time stability and modulation analysis of the XENON1T electronic recoil data ..... 284
A.4 Detector stability ..... 306