Recently, copper­(I) halides have been gaining increased attention as highly luminescent nontoxic alternatives to lead halide perovskites for optoelectronic applications. Here, we report preparation of blue emitting, lead free, all-inorganic halides K2CuX3 (X = Cl, Br) through five synthetic methods including traditional solid-state and solution methods. The photoluminescence (PL) emission spectra of K2CuCl3 and K2CuBr3 exhibit narrow peaks centered at 392 and 388 nm with full widths at half-maximum (fwhm) values of ∼54 nm. The visible bright blue emission is corroborated by the remarkably high photoluminescence quantum yield (PLQY) values up to ∼97%. Furthermore, radioluminescence measurements on K2CuCl3 yield a bright peak at 404 nm under irradiation with X-rays at 200 kVp and 20 mA, which is optimal for use with PMTs and Si photomultipliers, suggesting a strong potential of this family for radiation detection applications. Based on our combined experimental and computational investigations, the origin of the efficient luminescence in K2CuX3 is attributed to the high stability self-trapped excitons (STE) formed in the one-dimensional anionic ∞ 1[CuX3]2– chains. Advantageously, K2CuX3 demonstrate improved air- and photostability compared to the previously reported copper­(I) halides. The discovery of highly efficient and high stability light emitters based on earth-abundant copper­(I) halides paves the way for their potential practical applications.

Abstract-The simulation of radioactive decays is a common task in Monte-Carlo systems such as Geant4. Usually, a system either uses an approach focusing on the simulations of every individual decay or an approach which simulates a large number of decays with a focus on correct overall statistics. The radioactive decay package presented in this work permits, for the first time, the use of both methods within the same simulation framework -Geant4. The accuracy of the statistical approach in our new package, RDM-extended, and that of the existing Geant4 per-decay implementation (original RDM), which has also been refactored, are verified against the ENSDF database. The new verified package is beneficial for a wide range of experimental scenarios, as it enables researchers to choose the most appropriate approach for their Geant4-based application.

No abstract

PACS 29.30.Hs, 29.40.Vj, 29.40.Wk The common methods of neutron detection are reviewed with special attention paid to the application of cryogenics and semiconductors to the problem. The authors' work with LiF-and boron-based cryogenic instruments is described as well as the use of CdTe and HgI 2 for direct detection of neutrons. 1 Introduction Advances in materials and methods have enabled the detection of radiation by means today that would have seemed, to pioneers in the field a century ago, like science fiction. Improvements in technology have resulted, for gamma ray detection, in high-purity germanium operating at 77 K and providing 0.1% energy resolution above 1 MeV, more than an order of magnitude improvement over what was (and still is) achievable by scintillators. However, operating below 1 K, cryogenic calorimeters have been used in X-ray astronomy, in the search for dark matter, and more recently in gamma ray spectroscopy, and have achieved better than 70 eV resolution at 60 keV [1], a factor of 4 to 5 improvement over what can be achieved by germanium at that energy. Meanwhile, at the other end of the temperature spectrum, the development of new, wide band-gap semiconductors has sparked research in room temperature gamma ray detectors and has held out the hope of 1 -2% resolution and freedom from cryogenics [2,3].With such results being reported from the X-and gamma ray world it is natural to examine the possibilities for neutron detection. A cryogenic neutron detector would operate by detecting the heat pulses caused by neutron capture and scattering, while a semiconducting detector would detect the nuclear reaction products from a sensitizer (for example, fission fragments detected in a 235 U-coated Si diode) or from some constituent of the semiconductor.In the following sections, the common methods of neutron detection are described and their deficiencies with respect to neutron spectroscopy at energies above thermal (0.025 eV) are outlined. Published work on neutron-detecting cryogenic calorimeters will be reviewed and work by the present authors on boron-and lithium-based instruments will be discussed. Turning to semiconductors, we review work with coated and native (uncoated) semiconductor, including Cd 1-x Zn x Te (CZT) and HgI 2 , as applied to neutron detection. Results obtained by the authors with HgI 2 will be shown.

No abstract