A time-resolved luminescence spectroscopy study of self-trapped excitons in KH2PO4 crystals

A complex investigation of the dynamics of electronic excitations in potassium dihydrophosphate (KDP) crystals is performed by the low-temperature time-resolved vacuum ultraviolet optical luminescence spectroscopy with subnanosecond time resolution and with selective photoexcitation by synchrotron radiation. For KDP crystals, data on the kinetics of the photoluminescence (PL) decay, time-resolved PL spectra (2–$\text{6.2}\text{eV}$), and time-resolved excitation PL spectra (4–$\text{24}\text{eV}$) at $\text{10}\text{K}$ were obtained for the first time. The intrinsic character of the PL of KDP in the vicinity of $\text{5.2}\text{eV}$, which is caused by the radiative annihilation of self-trapped excitons (STEs), is ascertained; σ and π bands in the luminescence spectra of the STEs, which are due to singlet and triplet radiative transitions, are resolved; and the shift of the σ band with respect to the π band in the spectra of the STEs is explained.     

Environmental gamma radiation measurements in Bangladeshi houses

Indoor gamma dose rate in air measured using TLDs in the Dhaka district is not wide ranging and follows a normal distribution with an arithmetic mean of $\text{1.54±0.26}\text{mGy}\text{y}{}^{\mathrm{-1}}$. The result has been compared with those found by other investigators for different locations of the world. Measurements were made on a monthly basis for a year period, and a sinusoidal variation of monthly indoor gamma radiation of the type: $\text{d=160+65}\text{cos}\text{π/6}\text{(m−1)}$, where d is the indoor dose rate $\text{(}\text{nGy}\text{h}{}^{\mathrm{-1}}\text{)}$ and m the month. This might be due to the seasonally varied air exchange rates of the houses. The average annual effective dose and the collective dose equivalent for the residents were estimated to be $\text{0.86}\text{mSv}$ and $\text{172.20}\text{man}$-Sv, respectively, based on the indoor gamma exposure.     

Superfluidity with dressed nucleons

The gap equation with dressed propagators is solved in symmetric nuclear matter. Nucleon self-energies are obtained within the self-consistent in medium T matrix approximation. The off-shell gap equation is compared to an effective quasiparticle gap equation with reduced interaction. At normal density, we find a reduction of the superfluid gap from $\text{6.5}\text{MeV}$ to $\text{0.45}\text{MeV}$ when self-energy effects are included.