Introduction of the Reactor Source Spectrometers and Recent Research Progress in China Academy of Engineering Physics

Gong Jian (Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics)

The China Mianyang Research Reactor (CMRR) with the power of 20 MW is located in Mianyang City, Sichuan Province. It was limited open to users officially from 2012, including the thermal and cold neutron halls. The liquid hydrogen cold neutron source began to work from September 2013. The measured thermal and cold fluxes for neutron scattering experiments are 2.4×10¹⁴ n/cm²·s and 10⁹ n/cm²·s, respectively.

CMRR is devoted to both fundamental and applied neutron research. In the first phase, eight neuron scattering instruments have been installed and started operation from 2014. Four thermal neutron instruments installed in the reactor hall are: a high resolution neutron diffractometer (HRND), a residual stress neutron diffractometer (RSND), a thermal neutron radiography station (TNR) and a high pressure neutron diffractometer (HPDC). Four cold neutron instruments in the guide hall are: a small-angle neutron spectrometer (SANS), a time-of-flight and polarized neutron reflectometer (TPNR), a cold-neutron triple-axis spectrometer (CTAS) and a cold neutron radiography station (CNR). The HRPD has an optimum resolution of Δλ/λ=0.2 % with a wavelength of 1.88 Å. For the RSND, the maxiumu integral neutron flux at the sample position is 4.7×10⁶ n/cm²/s. Moreover, the wavelength can be tuned from 1.2 to 2.8 Å, and its resolution is Δd/d ≤ 0.25 %. Recently, texture measurement was realized on the RSND by utilizing the Kappa goniometer. The HPDC is equipped with a He-3 array detector containing 70 detection units. A sample temperature environment in a range of 10~1200 K and a high pressure loading system with a maximum pressure of 20 GPa are also installed on the PDC. The length of the reflection room of the SANS is 13 meters, and the range of reflection vector is 1×10^-2~5.0 nm^-1. The characteristics of the TPNR are the time-of-flight and polarization modes. Relative resolution of momentum transfer of the TPNR is Δq/q=(0.5~5)% for q=(0.05~3.0) nm^-1. The CTAS has an energy resolution of ΔE/E ≤ 2 % with a range of energy transformation of 0~10 meV.

Since the neutron scattering instruments at CMRR came into service, a number of neutron experiments have successfully been performed not only by our own research scientists but also by users from outside academic institutions such as Peking University, Chinese Academy of Science, et al. and some results have been published. For example, in situ neutron diffraction measurements on zircaloy-4 alloy and NiTi alloy have been performed using the RSND. Many materials have been studied by the diffraction measurements using the PDC, such as magnetic material Mn₅₄Al₄₆ (provided by Peking University), neutron irradiated Al1.0wt%B, permanent magnet material TbFeMn, superconducting material FeSe_0.2Te_0.8, etc. Analysis of the l temperature and humidity effects on the microstructure of Estane and the measurements of the precipitates in zironium alloys are performed using SANS. Moreover, some film sample tests, such as NiFe/NiFe, Ac/Estane et al, have been done using TPNR. The detailed analysis will be presented on the conference.

The second phase for neutron scattering instruments development at CMRR has recently been approved. In situ loading systems will be equipped for the present spectrometers, such as high/low temperature environments, high pressure loading systems, magnetic field loading systems, chemical loading devices (hydrogen/deuterium gas environment), et al. Furthermore, three new instruments, polarized thermal-neutron triple axis spectrometer (TTAS), ultra small angle neutron spectrometer (USANS), and neutron standard test beam-line (NSTB) will be built during the next several years. Details of the outlook progress will also be presented.

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Last modified 09-March-2015 by website owner: NCNR (attn: )