Izvestiya vuzov. Yadernaya Energetika

The peer-reviewed scientific and technology journal. ISSN: 0204-3327

Measurement of Neutron Source Field Characteristics by the Developed Bonner Spectrometer

12/10/2025 2025 - #04 Application of nuclear tech

Kugavda V.A. Denisenko A.P. Ryabeva E.V.

DOI: https://doi.org/10.26583/npe.2025.4.16

UDC: 539.1.074.85

This paper presents the developed Bonner spectrometer, experimental and model measurements, reduced spectra of isotopic neutron sources and their spectrometric and dosimetric characteristics. The Bonner spectrometer consists of a silver-based activation detection unit, an interface unit and a set of polyethylene retarding spheres with diameters of 3, 5, 7, 10 and 15 inches. It is enough for the spectrometer to drop the voltage of 12 V; the current consumption is not more than 400 mA. In the same geometry of the experiment, measurements were made, as well as the neutron spectra of “pure” 241AmBe and delayed neutrons of the same source were restored according to the readings of the integral number of pulses by various methods: iterative (GRAVEL and MAXED), parametric (ATOMTEX, CASCADE) and machine learning (Random Forest - machine learning algorithm based on an ensemble of decisive trees). The quality of spectrum recovery was assessed: average neutron energy in the recovered spectrum; absolute deviation of the energy value corresponding to the position of the peak of neutrons with an energy of ~ 4.87 MeV; including comparison with known spectra, by integral dose characteristic, average dose conversion factor from neutron fluence to ambient dose equivalent (AED) for various energy ranges. It has been shown that the highest quality restoration of the spectrum of isotope sources in the entire energy range is achieved (thermal, intermediate and fast neutrons) if spectra restored according to the readings of a scintillation spectrometer based on stilbene in the high-energy region (more than 1 MeV) are used as a priori information.

References

  1. Li Chongwei, Zhou Hongzhao, Liu Haixia, Sun Tao, Fan Haijun, Yang Jun, Xiao Wuyun. Neutron spectrometry of D2O-moderated 252Cf with Bonner sphere spectrometer Applied Radiation and Isotopes. 2023;197:1–6. DOI: https://doi.org/10.1016/j.apradiso.2023.110824
  2. Hu Qingdong, Ma Hao, Zeng Zhi, Cheng Jianping, Chen Yunhua, He Shengming, Li Junli, Shen Manbin, Wu Shiyong, Yue Qian, Yue Jianfeng, Zhang Hui. Neutron background measurements at China Jinping underground laboratory with a Bonner multi-sphere spectrometer. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 2017;859:37–40. DOI: https://doi.org/10.1016/j.nima.2017.03.048
  3. Savin D.I., Urupa I.V., Lupar E.E., Ibragimov R.F., Ryabeva E.V. Stilbene-Based Spectrometer for Unfolding the Energy Distribution of Fast Neutron Sources. Atomic Energy. 2022;133(2):109–114 https://doi.org/10.1007/s10512-023-00981-w
  4. DBN-A03D. NPP DOZA. URL: www.doza.ru/catalog/continuous_monitoring/detection_bloks/DBN-A03D/ (accessed May 12, 2025) (in Russian).
  5. DownloadGeant4-10.7.2. Geant4. URL: geant4.web.cern.ch/download/10.7.2.html (accessed May 12, 2025).
  6. Jun Chen B.Sc. Geant4 simulations and experimental tests of a silicon CD detector. China, 2006, 80 p.
  7. Wiegel B., Alevra A.V. NEMUS – the PTB Neutron Multisphere Spectrometer: Bonner spheres and more. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 2002;476:36–41. DOI: https://doi.org/10.1016/S0168-9002(01)01385-7
  8. ISO 8529-1, Neutron reference radiations fields – Part 1: Characteristics and methods of production.
  9. Kanj A., Lynde C., Carrel F., Frangville C., Thiam C., Ben Mosbah M., Venara J. Performance of deconvolution codes (MAXED, GRAVEL, MLEM) for neutron spectrometry of radioactive source using plastic scintillator simulated data. Radiation Measurements. 2024;176:107206. DOI: https://doi.org/10.1016/j.radmeas.2024.107206
  10. Pyshkina M.D., Vasilyev A.V., Nazarov E.I., Ekidin A.A. Characteristics of neutron fields around biological shielding of research nuclear reactors in Russia. Radiation Measurements. 2025;180:107325. DOI: https://doi.org/10.1016/j.radmeas.2024.107325
  11. Sevast’yanov V.D., Koshelev A.S., Maslov G.N. Standard neutron field at the center of the active zone of a BIR-2 reactor. Atomic Energy. 1994;76(1):49–55. DOI: https://doi.org/10.1007/BF02407866
  12. RandomForestClassifier. Scikit learn. URL: scikit-learn.org/stable/modules/generated/sklearn.ensemble.RandomForestClassifier.html (accessed Apr. 10, 2025).

neutron spectrometry Bonner spheres MAXED GRAVEL ATOMTEX CASCADE Random Forest ambient dose equivalent of neutrons average energy

Link for citing the article: Kugavda V.A., Denisenko A.P., Ryabeva E.V. Measurement of Neutron Source Field Characteristics by the Developed Bonner Spectrometer. Izvestiya vuzov. Yadernaya Energetika. 2025, no. 4, pp. 207-221; DOI: https://doi.org/10.26583/npe.2025.4.16 (in Russian).

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