Development of Cryogenic Dark Matter Diamond Detector

There is an increasing sense of ‘crisis’ in the DM particle community, which arises from the absence of evidence for the various candidates for dark-matter particles despite the enormous decades-long effort that has gone into searching for these particles. A lack of evidence for a high-mass dark matter particle in direct detection experiments and at the Large Hadron Collider has stimulated alternative theories that predict dark matter particle masses less than the mass of the proton (‘sub-GeV’). The challenging aspect of searching for these lighter DM particles, however, is that the scattering kinematics result in a very small momentum transfer, and thus require much more sensitive detectors with experimental thresholds as low as a few tens of eV, a performance that can be attained by cryogenic solid state detectors. The current state-of-the-art technology uses high-purity germanium or silicon cryogenic detectors with simultaneous measurements of phonon and ionization signal. To reach a higher sensitivity new material with excellent isotopic purity, lighter nuclei, and better long-lived phonon modes are required. Euclid Beamlabs LLC in collaboration with the Ohio State University propose a novel technology for detecting light sub-GeV DM particles that will allow to push the sensitivity down to two orders of magnitude for particles with masses less than 400 Mev/c2. Our approach proposes to develop Diamond as the active material in a Cryogenic Diamond-based detector. The technology will combine superior material, thermal, and electronic properties of diamond with superconducting Transition Edge Sensor (TES) technology and semiconductor ionization detector technology, which will allow to discriminate a vast majority of radioactive backgrounds. With the goal of achieving macroscopic detectors of mass 0.1-30 g, our program will primarily consider polycrystalline CVD (pCVD) diamond as it is readily available commercially, has lower cost and larger wafer sizes than single crystal (sc) diamond substrates. Under Phase 1 of the project, the room temperature electronic and thermal performance of diamond substrates will be used for initial material assessment, comparison and selection using simple Cr/Au contacts. We will also characterize isotopic purity and defect properties of the substrates. Once the devices are characterized, we will strip the contacts of the best devices and reuse the same material to create devices with W and or Ti/W contacts. For these devices we will assess the temperature-dependent phonon physics performance down to cryogenic temperatures. The final stage of the project will be to use the data we have accumulated as input parameters for simulation and modeling simple TES and ionization detector structures at low temperatures for the material’s sensitivity assessment of for low mass DM particles search. The disruptive cryogenic diamond-based detector approach we propose will achieve unprecedent (at least two orders of magnitude) sensitivity for sub-100 MeV Dark Matter particles direct search. The invention has high commercialization potential on current and future HEP experiments around the world. The same technology could be used in various fields outside the low mass dark Matter search and the accelerator avenue including quantum computation and communication, homeland security, and medical applications.