photoproduction on complex nuclei is reexamined using a generalized vector dominance model which succesfully predicts the oberved nuclear shadowing in real photoabsorption and deep inelastic scattering. This model is shown to give a good fit to photoproduction data on both nucleons and complex nuclei, in which the disagreement between the measured ␥-coupling and the ␥-coupling required by the simple vector dominance model is eliminated. The N total cross sections required are similar to those predicted by the additive quark model, and the magnitude of the correction to simple vector dominance is consistent with that inferred from the analysis of real photoabsorption and deep inelastic scattering. ͓S0556-2813͑98͒00505-6͔
Gamma‐rays (γ‐rays), wherever present, e.g., in medicine, nuclear environment, or homeland security, due to their strong impact on biological matter, should be closely monitored. There is a need for simple, sensitive γ‐ray detectors at affordable prices. Here, it is shown that γ‐ray detectors based on crystals of methylammonium lead tribromide (MAPbBr3) ideally meet these requirements. Specifically, the γ‐rays incident on a MAPbBr3 crystal generates photocarriers with a high mobility‐lifetime product, allowing radiation detection by photocurrent measurements at room temperatures. Moreover, the MAPbBr3 crystal‐based detectors, equipped with improved carbon electrodes, can operate at low bias (≈1.0 V), hence being suitable for applications in energy‐sparse environments, including space. The γ‐ray detectors reported herein are exposed to radiation from a 60Co source at dose rates up to 2.3 Gy h−1 under ambient conditions for over 100 h, without any sign of degradation. The excellent radiation tolerance stems from the intrinsic structural plasticity of the organic–inorganic halide perovskites, which can be attributed to a defect‐healing process by fast ion migration at the nanoscale level. The sensitivity of the γ‐ray detection upon volume is tested for MAPbBr3 crystals reaching up to 1000 cm3 (3.3 kg in weight) grown by a unique crystal growth technique.
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