Detection of Dark Matter

Despite extensive efforts, experiments like LZ, XENON-nT, and PandaX-4T have consistently failed to detect dark matter.

Key issues in detection

• Decades of experiments have yielded no definitive results, leading to a sense of resignation among the physics community.

About Dark Matter

• It is made up of particles that do not have a charge , which means they do not interact through electromagnetic interactions. 
• Characteristics: 
  • These are particles that are “dark”, namely because they do not emit light, which is an electromagnetic phenomenon and 
  • “matter” because they possess mass like normal matter and hence interact through gravity.

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Dark Energy Vs Dark Matter

• Over 95% of the universe comprises dark matter and dark energy, with visible matter making up less than 5%.

Hunt for Dark Matter

Early Discoveries

• 1930s: Fritz Zwicky observed galaxies moving too fast in the Coma Cluster, hinting at invisible mass (dark matter).
• 1970s: Vera Rubin confirmed dark matter’s presence through galaxy rotation studies.

Direct Detection Experiments

LUX-ZEPLIN (LZ) experiment: Achieved the most stringent limits on dark matter particle identity (August 2023).

• Goal: Detect dark matter particles weakly interacting with atomic nuclei deep underground.
• Challenges:
  • Neutrino Fog: It refers to the abundance of neutrinos that create background noise in dark matter detectors, masking potential dark matter signals.
    • Neutrinos, abundant ghostly particles, create background noise in detectors, making it difficult to distinguish dark matter signals.
  • Sensitivity Limits: Future detectors may struggle to differentiate dark matter from even fainter neutrino interactions.

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XENON-nT: It  is a dark matter experiment located in the Gran Sasso National Laboratory in Italy,using a large tank of liquid xenon.

• Objective: To directly detect dark matter particles by measuring their interactions with xenon atoms.
• Detection: So far, XENON-nT has not detected any definitive dark matter signals, but it has set stringent limits on the properties of certain dark matter candidates.

PandaX-4T :It is a dark matter experiment located in China. It uses a large tank of liquid xenon as its target material.

• Objective: To directly detect dark matter particles through their interactions with xenon atoms.
• Detection: Like XENON-nT, PandaX-4T has not yet detected any definitive dark matter signals. However, it has set important constraints on the properties of potential dark matter candidates.

Ways to fulfil Dark Matter Quest

• Use of Specialised Material: Detecting lighter dark matter particles with specialised materials.
• Indirect detection: Observing phenomena like gamma rays potentially produced by dark matter interactions.
• Collaborations:  It requires the collaboration of physicists, engineers, and experts across various scientific disciplines.

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