Development of the Neutron Calibration Fields using Accelerators at FRS and TIARA of JAEA

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Development of three calibration fields for 45, 60 and 75 MeV neutrons has been in progress at Takasaki Ion Accelerators for Advanced Radiation Application (TIARA) of JAEA-Takasaki. Achievement of the neutron calibration fields requires establishment of both measurement of neutron fluence and its monitoring technique. In order to measure the neutron fluence of main energy peak especially at a reference point on low fluence condition, a proton recoil counter telescope with high efficiency has been developed. The design of relatively large telescope components brought a high detection efficiency at the reference point with wide irradiation area at a long distance. Effective and precise measurement of the neutron fluence could be performed with uncertainties less than 6.5 % (standard deviation). For detecting neutrons without scattering near the target, a transmission type neutron fluence monitor has been newly developed to measure the neutron fluence directly at the collimator exit. Its performance such as counting rates was tested for various beam intensities.

Section: Introduction *mentioning

confidence: 99%

Section: Introduction *mentioning

confidence: 99%

Development of the Quasi-monoenergetic Neutron Calibration Fields of Several Tens of MeV at TIARA

Shikaze

Tanimura

Saegusa

et al. 2011

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“…The energy response of the neutron counters was measured using the neutron reference field (FRS) at the Japan Atomic Energy Agency (JAEA) 2,3,4) . Figure 5 shows the experimental setup.…”

Section: Energy Responsementioning

confidence: 99%

Development of a Current-Readout Type Neutron Monitor for Burst Neutron Fields

Iijima

Sanami

Hagiwara

et al. 2011

We report on the development of a current-readout type neutron monitor for the measurement of the dose rate of burst neutrons generated by beam loss in an accelerator that occurs within a short time span. This neutron monitor consists of a commercially available neutron proportional counter, a 6.5-cm thick polyethylene moderator, and a newly developed charge-integration circuit. The monitor was tested under mono-energetic neutron standard fields (En = 8 keV to 15 MeV) and was compared with a conventional pulse-readout type monitor. The energy response of the current-readout monitor is identical to that of the pulse-readout monitor. The current-readout monitor is able to measure neutron doses up to 4.5 mSv/h without count loss, whereas the pulse-readout monitor fails due to count loss.

“…The 1.2 and 2.5 MeV neutrons, which are the two of 12 energies specified in ISO 8529-1 [4], are produced by the 3 H(p,n) 3 He reaction. For the calibration of neutron dosemeters, the reference neutron dose equivalent is the most important parameter.…”

mentioning

confidence: 99%

“…Mono-energetic neutron calibration fields were developed between 8 keV and 19 MeV at the Facility of Radiation Standards (FRS) in the Japan Atomic Energy Agency (JAEA) using a 4MV Pelletron accelerator [1][2][3]. The 1.2 and 2.5 MeV neutrons, which are the two of 12 energies specified in ISO 8529-1 [4], are produced by the 3 H(p,n) 3 He reaction.…”

mentioning

confidence: 99%

Determination of neutron fluence in 1.2 and 2.5 MeV mono-energetic neutron calibration fields at FRS / JAEA

Tanimura

Tsutsumi

Yoshizawa

2014

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A highly efficient silicon semiconductor detector with a polyethylene convertor (CH 2 -SSD) was developed and the neutron fluences were precisely evaluated with it at 1.2 and 2.5 MeV mono-energetic neutron calibration fields at the Facility of Radiation Standard (FRS) in the Japan Atomic Energy Agency (JAEA) using an accelerator. The CH 2 -SSD was designed to have a higher detection efficiency than that of the conventional one in order to measure the neutron fluencies at the calibration point of more than 100 cm from the target. The NRESP-ANT and PHITS codes were used to calculate the efficiency of the CH 2 -SSD and its uncertainties. The maximum neutron fluence rates at 100 cm from the target were evaluated to be 1.0×10 3 and 2.0×10 3 cm -2 s -1 in the 1.2 and 2.5 MeV fields, respectively. They are high enough to calibrate dosemeters used for radiation protection purpose.