We examine the efficacy of Dark-mode plasmonics as a platform for enhanced magneto-optics. Dark-mode of a small particle consists of two co-existing equal-intensity and mutually opposing dipolar excitations. Each of these two opposing dipoles may even resonate at or near the dark-mode frequency , but the net dipole moment vanishes due to the mutual cancelation between the opposing dipoles. We show that application of external magnetic bias may alleviate the intense destructive interference. Furthermore, under external magnetic bias the opposing dark-resonances of a plasmonic particle shift in opposite directions and create a region of extremely sensitive Faraday rotation. We show that the magnetized dark resonance in lossless Ag-like particle may provide more than 20 degrees rotation under magnetic fields of the order of 1-2 Tesla, exhibiting magneto-plasmonic activity that is 2-3 orders of magnitude larger than that observed in conventional plasmonic particle of the same material. 1 Dark modes of an open optical structure can be described as states of excitations that incorporate mutually opposing local dipoles whose far-fields interfere destructively. The net dipolar excitation then vanishes, resulting in a significant reduction of the far-field radiation, and consequently a reduction of the associated radiation damping and bandwidth. 1-8 This, in turn, may trap optical fields in a structure that is inherently coupled to a continuum. More formally, dark modes can be viewed as manifestations of discrete eigenvalues embedded within the continuous spectrum of the associated non-compact scattering operator. Dark modes were suggested as candidates for electromagnetic energy storage, enhanced biological and chemical sensors , and nanoscale waveguides. These modes can be supported by simple structures such as nano-dimers (see, e.g. the "anti-bonding" plasmons in Ref. [ 1]), trimers, 6 clustered nano-rods 3 and spheres. 7,8 In a seemingly unrelated research endeavor, nonreciprocal magneto-optics and its implementation for one-way waveguides, optical isolators and circulators, and Faraday rotators, have been under intensive study. 9-14 Currently the major drawback of nonreciprocal magneto-optics is the requirement for strong magnetic bias B 0. Efforts to reduce B 0 for various applications (e.g. Faraday polarization rotation) in plasmonic structures can be found, e.g. in. 15-17 The work in 15 reports on an experimental evidence for a 2-3 fold enhancement of magneto-optical activity in coated nano-particles. The efforts in 16,17 are limited to graphene metasurfaces. Here we study the effect of bias magnetization on plasmonic particle dark modes, and explore its potential applications as a new platform for non-reciprocal optics. As a simple and physically transparent test-case, we consider the core-shell spherical particle shown in Fig. 1, made of two plasmonic materials with close, but not identical , plasma frequencies. The structure is excited by a linearly polarized local field E L (r) = ˆ zE L e iky. When properly d...

There are recent interests with CsI(Tl) scintillating crystals for Dark Matter experiments. The scattering signatures by neutrons on a CsI(Tl) detector were studied using a neutron beam generated by a 13 MV Tandem accelerator. The energy spectra of nuclear recoils from 7 keV to 132 keV were measured, and their quenching factors for scintillating light yield were derived. The data confirms the Optical Model predictions on neutron elastic scatterings with a direct measurement of the nuclear recoils on heavy nuclei. The pulse shape discrimination techniques to differentiate nuclear recoils from γ-background were studied. Internal consistencies were obtained among the different methods of light yield measurements. The projected capabilities for Cold Dark Matter searches with CsI(Tl) crystals are presented.PACS Codes: 25.40. Dn, 95.35.+d, 29.40.Mc.