When:
Tuesday, October 9, 2018
2:00 PM - 3:00 PM CT
Where: Technological Institute, F160, 2145 Sheridan Road, Evanston, IL 60208 map it
Audience: Faculty/Staff - Student - Public - Post Docs/Docs - Graduate Students
Contact:
Pamela Villalovoz
(847) 491-3644
Group: Physics and Astronomy High Energy Physics Seminars
Category: Academic
For dark matter (DM) particles with masses in the 0.6 - 6 GeV/c^2 range, we may set stringent constraints on the interaction cross-sections for scattering with ordinary baryonic matter. These constraints follow from the recognition that such particles can be captured by - and thermalized within - the Earth, leading to a substantial accumulation and concentration of DM that interact with baryons. I will discuss the probability that DM intercepted by the Earth will be captured, the number of DM particles thereby accumulated over Earth's lifetime, the fraction of such particles retained in the face of evaporation, and the density distribution of such particles within the Earth. This analysis provides an estimate of the DM particle density at Earth's surface, which may exceed 1.E+14 cm-3, and leads to constraints on various scattering cross-sections, which are placed by: (1) the lifetime of the relativistic proton beam at the Large Hadron Collider; (2) the orbital decay of spacecraft in low Earth orbit; (3) the vaporization rate of cryogenic liquids in well-insulated storage dewars; and (4) the thermal conductivity of Earth's crust. For the scattering cross-sections that were invoked recently in Barkana's original explanation for the anomalously deep 21 cm absorption reported by EDGES, DM particle masses in the 0.6 - 4 GeV/c^2 range are excluded. Finally, I will discuss a tabletop experiment (that we are currently conducting in my basement) to further constrain the interaction cross-sections for a variety of atomic nuclei.
Seminar Speaker: David Neufeld, Johns Hopkins University
Keywords: Physics, Astronomy, HEP