NEMUS—the PTB Neutron Multisphere Spectrometer: Bonner spheres and more

Wiegel, B.; Alevra, A.

doi:10.1016/s0168-9002(01)01385-7

Cited by 129 publications

(72 citation statements)

References 10 publications

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“…The analysis of the data requires several steps: the analysis of the pulse height spectrum (PHS) measured in the 3 He proportional counters of the spheres, corrections for detector dead-time, and the unfolding of the data to determine the neutron energy distribution.…”

Section: Discussionmentioning

confidence: 99%

“…The Physikalisch-Technische Bundesanstalt (PTB) operates the Bonner sphere spectrometer NEMUS [3]. This is a well characterized spectrometer which serves as the secondary standard of PTB for the dissemination of the unit of ambient dose equivalent for neutron radiation in unknown radiation fields.…”

Section: Introductionmentioning

confidence: 99%

“…We used 3 He proportional counters with pressures of either ~200 kPa or ~20 kPa. The low pressure counters are capable of handling higher count rates than the one with higher pressure, making them well suited for locations with higher fluence rates.…”

Section: Introductionmentioning

confidence: 99%

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Measurement of the energy spectrum of secondary neutrons in a proton therapy environment

Dommert

Reginatto

Zbořil

et al. 2017

Current Directions in Biomedical Engineering

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Measurement of the energy spectrum of secondary neutrons were carried out at the OncoRay Proton Therapy facility in Dresden, following an approach originating in neutron metrology which is well suited for both the characterization of secondary neutron fields at proton therapy facilities and the validation of Monte Carlo simulations. For the experiment, a brass target was placed in the proton beam and Bonner spheres measurements were made at a distance of 2 m from the target and at different angles, 15° to 120°, with respect to the incoming proton beam. The measured spectra were compared to Monte Carlo simulations.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Measurement of the energy spectrum of secondary neutrons in a proton therapy environment

Dommert

Reginatto

Zbořil

et al. 2017

Current Directions in Biomedical Engineering

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“…The BSS consists of a 3 He spherical proportional counter (CENTRONIC LTD, SP9, gas pressure: 21.3 kPa) and polyethylene (PE, 0.95 g/cm 3 ) moderators with diameters from 7.62 cm to 24.1 cm. In addition, measurements were performed using inserting metal shells made of lead (457p: 10.2-cm-diameter PE sphere + 1.27-cm thick Pb shell + 2.54-cm thick PE shell) and copper (457c: 10.2-cm-diameter PE sphere + 1.27-cm-thick Cu shell + 2.54-cm thick PE shell) [8]. The response functions of BSS were simulated with the MCNPX code [9].…”

Section: Bonner Sphere Spectrometermentioning

confidence: 99%

Measurement of neutron energy spectra behind shields for quasi-monoenergetic neutrons generated by 246-MeV and 389-MeV protons using a Bonner sphere spectrometer

Matsumoto

Masuda²,

Nishiyama³

2014

Progress in Nuclear Science and Technology

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Neutron energy spectra behind concrete and iron shields were measured for quasi-monoenergetic neutrons above 200 MeV. Quasi-monoenergetic neutrons were produced by the 7 Li(p,xn) reaction with 246-MeV and 389-MeV protons. A Bonner sphere spectrometer was used to obtain the neutron energy spectra. Shielding materials are concrete blocks with thicknesses from 25 cm to 300 cm and iron blocks with thicknesses from 10 cm to 100 cm. The neutron energy spectra behind the concrete and iron shields were obtained by the unfolding method using the MAXED code. Ambient dose equivalents were obtained as a function of a shield thickness successfully. These experimental data will be useful to perform accurate shielding design, benchmark calculation codes and evaluate neutron cross section data.

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“…It consists of a thermal neutron detector and several polyethylene moderators called Bonner spheres. It could measure neutron energy up to a few GeV with an inlet metal moderator 1) . Conventional neutron ambient dosimeters differ greatly from the conventional true value in the unknown fields.…”

Section: K0"kpvtqfwevkqp 3 "mentioning

confidence: 99%

Development of a Neutron Energy Monitoring System

Kim

Park

2012

Progress in Nuclear Science and Technology

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The neutron energy measurement is important to evaluate the neutron ambient dose-equivalent. A Bonner sphere spectrometer is a very powerful tool for the measurement of the large dynamic range of neutron energy. However, online monitoring of the neutron energy with Bonner spheres is hard to achieve because of the complex unfolding procedure. For this purpose, the neutron energy monitoring system consisted of a few 3 He proportional counters with cylindrical moderators were developed and their responses were evaluated using MCNPX transport calculations. The range of neutron energy from thermal to 5 GeV was divided into four intervals and six neutron energy spectra were studied to get the weighted average of the response. Spectral neutron fluences of 252 Cf source and D 2 O-moderated 252Cf source were measured in the neutron irradiation room at the Korea Research Institute of Standards and Science. The measured spectra were compared to those by the Bonner sphere spectrometer. The result showed that the neutron energy spectra using the weighted average response of cosmic-ray induced neutron distribution agreed with that obtained by offline analysis of the Bonner sphere spectrometer within 20 %. The system will be used to monitor the environmental neutrons in the near future. KEYWORDS: neutron energy monitoring, response matrix, diagonalization, weighted response K0"Kpvtqfwevkqp 3 "The measurement of the spectral fluence of neutrons is important for evaluating the neutron ambient dose equivalent and widely used to determine a neutron dose. Because of the large dynamic range of neutron energy from meV to a few GeV, there is no practical way to measure the full dynamic range with only a single detector. Many detectors and techniques have been developed to measure the neutron energy. Most common methods are based on the techniques with time-of-flight, multi-moderator detectors like Bonner sphere spectrometers, and threshold detectors like activation foil sets. Among them, a Bonner sphere spectrometer is a very powerful tool for the measurement of the large dynamic range of neutron energy. It consists of a thermal neutron detector and several polyethylene moderators called Bonner spheres. It could measure neutron energy up to a few GeV with an inlet metal moderator 1) . Conventional neutron ambient dosimeters differ greatly from the conventional true value in the unknown fields. Therefore, online monitoring of the neutron energy is also getting important to supplement the neutron ambient dosimeter. The Bonner sphere spectrometer could be used to monitor neutron energy. However, online monitoring of the neutron energy with Bonner spheres is hard to achieve because of the complex procedure like unfolding. The number of the spheres is usually less than 20 which is much smaller than the typical neutron energy bin size. Prior information such as an initial guess of neutron spectrum is *Corresponding Author, E-mail:jungho@kriss.re.kr © 2012 Atomic Energy Society of Japan, All Rights Reserved. required to do unfolding procedur...

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NEMUS—the PTB Neutron Multisphere Spectrometer: Bonner spheres and more

Cited by 129 publications

References 10 publications

Measurement of the energy spectrum of secondary neutrons in a proton therapy environment

Measurement of the energy spectrum of secondary neutrons in a proton therapy environment

Measurement of neutron energy spectra behind shields for quasi-monoenergetic neutrons generated by 246-MeV and 389-MeV protons using a Bonner sphere spectrometer

Development of a Neutron Energy Monitoring System

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