After years of working on accelerator-based experiments at Fermilab and Brookhaven, I have moved to the exciting subfield of direct searches for Dark Matter. Working with the Princeton Particle Astrophysics group (see Profs. Calaprice and Galbiati) and others, I am developing new devices to detect the very-low-energy nuclear recoils from the elastic scattering of "Weakly Interacting Massive Particles" (WIMPs), a promising model for the Dark Matter. We are focused on liquid argon as a detection medium, collecting the scintillation light and ionization created by the recoiling nuclei in a "two-phase TPC" configuration. We have built prototypes and operated them in the basement of Jadwin Hall, but actual experiments must be operated deep underground in laboratories like Gran Sasso National Laboratory (LNGS) in Italy, SNOLab in Canada, or the Sanford Laboratory in the Homestake Mine in South Dakota.
After operating a prototype TPC with an active mass of 10 kg of liquid argon, DarkSide-10, at Princeton and LNGS (see figure), we built DarkSide-50, a 50-kg detector now now running at LNGS. See the DarkSide-50 proposal here. I was in charge of the design and fabrication of the TPC, the heart of the experiment, that is deployed in a very elaborate facility to reduce backgrounds from cosmic rays and natural radioactivity in the lab and detector components. In April 2015, we started a three-year run with argon we extracted from underground sources. As expected from early samples, this argon has much less of the radioactive isotope Ar-39 than argon from the atmosphere.
We have published papers from the first 50 days of running with atmospheric argon and from the first 70 days of running with underground argon (see below).
My previous project was the Fermilab Booster Neutrino Experiment, MiniBooNE. This was an investigation of neutrino oscillations in the region of mass-difference and mixing angle where the LSND experiment had seen some evidence for oscillations. "MiniBooNE" is a 40-ft-diameter tank of mineral oil, instrumented with photomultiplier tubes and positioned 500 m from the 1-GeV neutrino source. The Princeton group led the design and construction of this detector in 2001. You can see how the construction proceeded here.
In 2007, we reported our first oscillation results (see the reference below), which saw no evidence for the LSND effect. The published analysis was the one developed by the Princeton group. In this analysis, there was an excess of electron-like events at low energies for which there is still no convincing explanation. The experiment continued running (without our active involvement) until September 2014.
- “Low radioactivity argon dark matter search results from the DarkSide-50 experiment,” P. Agnes et al., arXiv:1510.00702 (2015).
- "First results from the DarkSide-50 dark matter experiment at Laboratori Nazionali del Gran Sasso", P. Agnes et al., Phys. Lett. B 743, 456 (2015). arXiv:1410.0653.
- "Light Yield in DarkSide-10: a Prototype Two-phase Liquid Argon TPC for Dark Matter Searches", D. Akimov et al. (DarkSide Collaboration), arXiv:1204.6218 (2012).
- "A Search for Electron Neutrino Appearance at the m2 ~1 eV2 Scale", A. A. Aguilar-Arevalo et al., arXiv:0704.1500 [hep-ex], Phys. Rev. Lett. 98, 231801 (2007).
- "The MiniBooNE Detector", A.A. Aguilar-Arevalo et al., arXiv:0806.4201 [hep-ex], Nucl. Instr. Meth. A599 (2009) 28-4.