Observation of the Migdal effect in TPC with optical readout

• Grant number: 23/10311-5
• Support Opportunities: Scholarships abroad - Research
• Start date: September 03, 2023
• End date: March 02, 2024
• Field of knowledge: Physical Sciences and Mathematics - Physics - Elementary Particle Physics and Fields
• Principal Investigator: Ernesto Kemp
• Grantee: Ernesto Kemp
• Host Investigator: Elisabetta Baracchini
• Host Institution: Instituto de Física Gleb Wataghin (IFGW). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Institution abroad: Gran Sasso Science Institute (GSSI), Italy

Abstract

This research project aims to develop an experiment based on Time Projection Chamber (TPC) with 3D optical reading to measure the Migdal effect. The Migdal effect, predicted and calculated by A. B. Migdal in 1941, has not yet been observed in nuclear collisions, but only in the nuclear decay of radioactive elements with few elements. The Migdal effect refers to the possibility of sudden excitation or ionization of a recoiling atom in elastic scattering due to a time delay between the electron cloud and the nucleus. Observing the Migdal effect is significant because it can be utilized to effectively reduce nuclear recoil (NR) detection thresholds in direct searches for Dark Matter (DM). The dominance of DM in the Universe is a well-established scientific paradigm, and identifying and studying its nature is one of the most challenging tasks in fundamental physics. The current lack of evidence for DM in indirect, direct, and collider searches has led researchers to explore DM candidates with masses less than 1 GeV, a range with solid theoretical support but largely unexplored due to the limitations of current technologies, which do not reach sub-keV energies for NR required for observing DM with small masses. Additionally, there are proposals to enhance the sensitivity of solar neutrino detectors by exploring the Migdal effect in the scattering process of coherent neutrino-nucleus interactions. Given these reasons, the experimental observation of the Migdal effect is deemed fundamental and highly relevant to current research in DM and other areas of particle physics. The proposed experimental approach for directional detection of the Migdal effect using TPCs is well-suited for this measurement. Our plan is to use a TPC with approximately 50 liters of He/Ar:CF4, combining optical reading with PMTs and a high-resolution sCMOS camera for precise 3D reconstruction. The project aims to optimize the TPC design for measuring the Migdal effect under experimental conditions with a large flux neutron beam serving as the source of incident particles. (AU)