• A novel method for gamma spectrum analysis of low-level and intermediate-level radioactive waste

    分类: 核科学技术 >> 辐射防护技术 提交时间: 2023-06-06

    摘要:The uncertainty of nuclide libraries in the analysis of the gamma spectra of low- and intermediate-level radioactive waste (LILW) using existing methods produces unstable results. To address this problem, a novel spectral analysis method is proposed in this study. In this method, overlapping peaks are located using a continuous wavelet transform. An improved quadratic convolution method is proposed to calculate the widths of the peaks and establish a fourth-order filter model to estimate the Compton edge baseline with the overlapping peaks. Combined with the adaptive sensitive nonlinear iterative peak, this method can effectively subtracts the background. Finally, a function describing the peak shape as a filter is used to deconvolve the energy spectrum to achieve accurate qualitative and quantitative analyses of the nuclide without the aid of a nuclide library. Gamma spectrum acquisition experiments for standard point sources of Cs-137 and Eu-152, a segmented gamma scanning experiment for a 200 L standard drum, and a Monte Carlo simulation experiment for triple overlapping peaks using the closest energy of three typical LILW nuclides (Sb-125, Sb-124, and Cs-134) are conducted. The results of the experiments indicate that (1) the novel method and gamma vision (GV) with an accurate nuclide library have the same spectral analysis capability, and the peak area calculation error is less than 4%; (2) compared with the GV, the analysis results of the novel method are more stable; (3) the novel method can be applied to the activity measurement of LILW, and the error of the activity reconstruction at the equivalent radius is 2.4%; and (4) The proposed novel method can quantitatively analyze all nuclides in LILW without a nuclide library. This novel method can improve the accuracy and precision of LILW measurements, provide key technical support for the reasonable disposal of LILW, and ensure the safety of humans and the environment.

  • Polyethylenimine as a dual functional additive for electron transporting layer in efficient solution processed planar heterojunction perovskite solar cells

    分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-08

    摘要: We report a doping method to enhance the performance of solution processed planar heterojunction perovskite solar cells. By doping a small percentage (3 wt%) of polyethylenimine (PEI) as additive into the PCBM electron transport layer of an inverted perovskite solar cell, which led to significant enhancements of power conversion efficiency from (5.9 ` 0.2) % to (10.4 ` 0.2) %. The AFM images show that the PEI doped PCBM layer can help to form a high quality, homogeneous and compact electron transporting layer on the rough CH3NH3PbI3 layer, which results in enhanced hole blocking ability and reduced leakage current at the interfaces between the CH3NH3PbI3, PCBM films and the top Al electrode. Organic field-effect transistors (OFETs) measurements reveal that the addition of 1–3 wt% PEI into PCBM layer can improve device performance without any negative effect on the electron transport property of PCBM. Steady-state PL analysis shows that the electron-rich PEI may also act as an effective interfacial modifier to passivate the trap states at the perovskite surface or crystal boundaries and to avoid the undesired charge recombination often observed in perovskite solar cells. PEI will also improve performance as a cathode interfacial modifier because the PCE of the device with PEI deposited between PCBM and Al is superior to the device without PEI. This work demonstrated that amine- containing polymer materials can be used as an efficient dual functional additive in perovskite solar cells. This study provides an efficient way of developing highly efficient CH3NH3PbI3-based perovskite solar cells.