Molecular excitations: a new way to detect Dark Matter

Abstract

We believe that the Dark Matter (DM) search should be expanded into the domain of detectors sensitive to molecular excitations, and so that we should create detectors which are more sensitive to collisions with very light WIMPs. In this paper we investigate in detail di-atomic molecules, such as Fused Silica material with large OH-molecule content, and water molecules. Presently, we do not have suitable low cost IR detectors to observe single photons, however some OH-molecular excitations extend to visible and UV wavelengths, and can be measured by Bialkali photocathodes. There are many other chemical substances with di-atomic molecules, or more complex oil molecules, which could be investigated also. This idea invites searches in experiments having large target volumes of such materials coupled to a large array of single-photon detectors with Bialkali or infrared-sensitive photocathodes.

Search for a nonrelativistic component in the spectrum of cosmic rays at Earth

“…A neutron this slow, even when transferring all of its energy to a proton recoil in a single scatter, has a small probability of generating scintillation in LS. While this same limitation would apply to an equally slow 1 GeV SIMP predominantly interacting via proton recoils, dark matter particles are potentially able to display other mechanisms of interaction [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38], not partaken by neutrons. Most importantly, values of | ∆t| smaller than ∼ 1 µs are not possible for dark matter particles, due to their characteristic halo velocity distribution, which is bound from above by the galactic escape velocity at the position of the Earth (v esc 550 km/s).…”

“…Perhaps as a reaction to this, the last few years have witnessed a surge of phenomenological interest in dark matter alternatives to a "vanilla" mediummass (10-1000 GeV) WIMP interacting through nuclear recoils. Two themes, oftentimes overlapping, can be discerned in this flurry of activity: candidates with lighter masses m χ few GeV [9][10][11][12][13][14][15][16][17][18][19][20][21][22], incapable or limited in their ability to produce signals above the energy threshold of present devices, and an examination of interaction mechanisms other than nuclear recoils [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38]. Unfortunately, the heavy investment of the experimental community into the next and possibly final generation of WIMP detectors has resulted in a certain inertia, with few (as of yet) searches being performed in response to this phenomenological prod.…”

A new possible way to explain the DAMA results

“…One could attempt to detect diatomic molecular vibration, excited by gentle WIMP-proton scattering, and hence further reduce the threshold on the WIMP mass [25]. To excite such vibrations, a very small energy deposit at a level of 1.8-4.3 eV is needed.…”

Detection of sub-GeV dark matter and solar neutrinos via chemical-bond breaking

“…New detection methods involving chemical-bond breaking could significantly improve upon current detection capabilities, may allow for the detection of cosmic and solar axions, and may ultimately also be able to probe the lowest energy part of the solar neutrino spectrum. For other recent proposals see [29][30][31][32].…”