0000000000286979
AUTHOR
F. Qi
Feasibility and physics potential of detecting $^8$B solar neutrinos at JUNO
The Jiangmen Underground Neutrino Observatory (JUNO) features a 20 kt multi-purpose underground liquid scintillator sphere as its main detector. Some of JUNO's features make it an excellent location for 8B solar neutrino measurements, such as its low-energy threshold, high energy resolution compared with water Cherenkov detectors, and much larger target mass compared with previous liquid scintillator detectors. In this paper, we present a comprehensive assessment of JUNO's potential for detecting 8B solar neutrinos via the neutrino-electron elastic scattering process. A reduced 2 MeV threshold for the recoil electron energy is found to be achievable, assuming that the intrinsic radioactive …
Slow and fast methyl group rotations in fragile glass-formers studied by NMR
Abstract The spin-lattice relaxation times of the selectively ring deuterated, fragile glass-formers propylene carbonate and toluene were compared with those measured for species which were specifically labeled at the methyl groups. It was found that the dynamics of the CD 3 group is strongly decoupled from that associated with the primary response of toluene, while for propylene carbonate the degree of decoupling is relatively weak. The experimental results could be described successfully using a model which takes into account the ring dynamics as well as those of the methyl group.
Stimulated 7^Li echo NMR spectroscopy of slow ionic motions in a solid electrolyte
Abstract Lithium spin-alignment spectroscopy is presented as an NMR technique for studying slow translational motions in solid and solid-like ionic conductors. We employ phase cycling that allows to measure two-time translational correlation functions via the generation of a pure quadrupolar ordered state. Correlation functions of the crystalline electrolyte Li 3 Sc 2 (PO 4 ) 3 were recorded for times ranging from about 0.1 ms to more than 10 s, implying that translational diffusion coefficients smaller than 10 −20 m 2 /s become accessible.
Simple modeling of dipolar coupled 7Li spins and stimulated-echo spectroscopy of single-crystalline β-eucryptite
Abstract Stimulated-echo spectroscopy has recently been applied to study the ultra-slow dynamics of nuclear spin-3/2 probes such as 7 Li and 9 Be in solids. Apart from the dominant first-order quadrupolar interaction in the present article also the impact of the homonuclear dipolar interactions is considered in a simple way: the time evolution of a dipole coupled pair of spins with I =3/2 is calculated in an approximation, which takes into account that the satellite transitions usually do not overlap. Explicit analytical expressions describing various aspects of a coupled quadrupolar pair subjected to a Jeener–Broekaert pulse sequence are derived. Extensions to larger spin systems are also …
Stimulated-echo NMR spectroscopy of 9Be and 7Li in solids: method and application to ion conductors.
The generation of pure quadrupolar stimulated-echo spectra is successfully demonstrated for the spin-3/2 probe 9Be in a single crystal of triglycine fluoberyllate. This solid exhibits a paraelectric-to-ferroelectric phase transition. From experiments carried out for various mixing times no indications for a slow soft mode could be detected in this crystal. Then ion conducting lithium metal phosphates were studied using 7Li, another spin-3/2 probe which allows for a non-selective excitation of the entire NMR spectrum. In the indium and the scandium phosphates ultra-slow Li hopping processes could be detected directly via the stimulated-echo technique in a time range of up to four orders of m…