Identification of radionuclides for the spectroscopic radiation portal monitor for pedestrian screening under a low signal-to-noise ratio condition

Eungi Min, Mincheol Ko, Hakjae Lee, Yongkwon Kim, Jinhun Joung, Sung Kwan Joo, Kisung Lee

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


The spectroscopic radiation portal monitor (SPM) is widely used for homeland security. Many research groups are studying the radionuclide identification method which is one of the most important factors in the performance of the SPM using the large size of a thallium activated sodium iodide (NaI(Tl)) detector. In this study, we developed the radionuclide identification method for the SPM for pedestrian screening using a single NaI(Tl) detector that is small in size (2 in.), which is much smaller than those in the existing studies under the low signal-to-noise-ratio (SNR) condition. From the anomalous radionuclide spectrum, the noise component was effectively reduced by the wavelet decomposition and the proposed background subtraction method, and the signal component was enhanced by the principal component analysis. Finally, peak locations which have been determined by the peak search algorithm with a valley check method were compared with a pre-calibrated and constructed radionuclide database. To verify the radiation identification performance of the proposed method, experiments with various kinds of sources (137Cs, 133Ba, 22Na, and 57Co) and different SNR values (from distances of 10-150 cm and for scan times of 1-5 s) were performed. Although the high-SNR condition was explored as well, most experiments were conducted under the low-SNR condition to verify the robustness and reproducibility of the proposed algorithm. The results showed that over 98.3% of the single radionuclide detection rate was achieved regardless of which radionuclides were used, up to 50 cm under the worst SNR condition (1 s of scan time) and up to 90 cm under the best SNR condition (5 s of scan time). Furthermore we achieved accurate identification of multiple radionuclides at 40 cm with only 1 s of scan time. The results show that the proposed algorithm is competitive with the commercial method and our radionuclide identification method can be successfully applied to the SPM for pedestrian monitoring, with a small detector size and a short scan time.

Original languageEnglish
Pages (from-to)62-68
Number of pages7
JournalNuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Publication statusPublished - 2014 Sept 11


  • Detection rate
  • Pedestrian screening
  • Radionuclide identification
  • Signal-to-noise ratio
  • Spectroscopic radiation portal monitor

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Instrumentation


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