In the title compound, Na+·C14H11O2−, the di­phenyl­acetate ions have a conformation where the two phenyl rings and the carboxyl­ate group are oriented like the blades of a propeller, each ion having a well defined helicity. The crystal structure of the title compound is achiral, although non‐centrosymmetric (space group ); thus, ions with both (+) and (−) helicities are present in the crystal. Each Na+ ion is coordinated by four carboxyl­ate O atoms at distances in the range 2.207 (2)–2.467 (3) Å to form cubes of Na and O atoms which are linked via the carboxyl­ate C atoms into a columnar structure along the rotoinversion axis.

Superheated droplet detectors (SDDs) have been investigated for applications in neutron dosimetry and spectrometry. Varying the detector temperature, it is possible to change the neutron energy detection threshold of SDDs, thus allowing the use of a single detector to measure neutrons of different energy, without any change of the experimental setup. However, the neutron threshold energy versus temperature curves have to be experimentally determined. The determination of the calibration curves requires the use of monochromatic neutron beams.The neutron spectrum from a nuclear reactor covers a wide energy range, from meV to several MeV. Beams of quasi-monochromatic neutrons can be generated by filtering neutrons emerging from the core with suitable materials, such as Fe (for 24 keV neutrons) and Si (144 and 54 keV). These materials have windows in their neutron cross-sections, so that neutrons corresponding to these windows are transmitted, whereas neutrons with other energies are attenuated.We report on the MCNP simulation study of passive monochromators of Si þ S and Si þ Ti for the production of quasimonochromatic neutron beams of 54 keV ðSi þ SÞ and 144 keV ðSi þ TiÞ. The simulations allowed the purity versus intensity of the neutron beams to be optimized, within the geometrical constraints of the beam port. r