Dark Matter Search XENON 100 Xiangyu Xie 1172022

Evidence on dark matter 1. Galaxies rotation curves 2. Cluster collision / Bullet cluster

Detecting mechanics v. Nucleus recoil • Kinetic process • Ionize Xe molecule • First

DAQ system v. Sum-up trigger • All channels contribute to the trigger v. Sampling

Event reconstruction vz coordinate • Determined by drifting time vx, y coordinates • Reconstructed

Data analysis: Fiducial cut v. The background (blue) v. The WIMP signal(red) v 22

Summary v. Features of XENON 100 • The target material is carefully chosen to

Slides: 10

Download presentation

Dark Matter Search: XENON 100 Xiangyu Xie 1/17/2022 1

Evidence on dark matter 1. Galaxies rotation curves 2. Cluster collision / Bullet cluster 3. Cosmic microwave background • Dark matter and dark energy influence the mass distribution (more overdense regions or less) • Fit model: 68% dark energy + 27% dark matter + 5% normal matter 1/17/2022 2

Glance of XENON 100 Profile 1/17/2022 Sectional Drawing 3

Detector design v Top Bot 1/17/2022 4

Detecting mechanics v. Nucleus recoil • Kinetic process • Ionize Xe molecule • First scintillating light (S 1) v. Electrons drifting • Under the E field • At constant velocity v. Electrons extracted into gas • Under a stronger E field • Second scintillating light (S 2) 1/17/2022 EM interaction would lead to more ionized electrons 5

DAQ system v. Sum-up trigger • All channels contribute to the trigger v. Sampling ADCs • Preserve the waveform v. Zero-length-encoding • Discard while the strength of waveform is lower than a given threshold • Could compress 90% data v. Online PMT-gain calibration • Use an external blue LED via optical-fiber 1/17/2022 Scheme of the DAQ system 6

Event reconstruction vz coordinate • Determined by drifting time vx, y coordinates • Reconstructed from top S 2 PMT signals using: • Support Vector Machine • χ2 • (√)Neural Network 1/17/2022 S 1: S 2: 7

Data analysis: Fiducial cut v. The background (blue) v. The WIMP signal(red) v 22 events (black spots) • After fiducialization and veto v. Assumption: S 1 resolution dominated by Poisson fluctuations 1/17/2022 8

Data analysis: Profile MLE v 1/17/2022 9

Summary v. Features of XENON 100 • The target material is carefully chosen to meet the different requirements • The ‘slow’ cosmic-ray experiments leads to a different DAQ system comparing to ATLAS • ‘Real time’ PMT calibration v. Two different analysis methods: • In high WIMP mass region, MLE is 20%-30% better due to large parameter space • MLE is easier to determine the error • Fiducial cut is still used in XENON 1 T, may due to less time for publication v. Challenge of XENON n. T • Higher voltage for larger volume leads to sparkling 1/17/2022 10