留言板

Lead-bismuth eutectic(LBE) is the candidate material of spallation target for China initiative Accelerator Driven System(CiADS). Long-term irradiation makes the LBE highly radioactive. Most of the spallation target radionuclide studies focused on the effects of the proton beam and ignored fission neutrons from the reactor. In this paper, both the fission neutrons and the high-energy protons have been taken into account in the radionuclide calculations of LBE and spallation target structural parts by coupling codes FLUKA and MCNP. Contributions from the fission neutron and the high-energy proton have been compared in the aspects of the activity, main radionuclides, toxicity, and the decay photon of radioactive products. The main shell, guide tube, and beam tube are significantly affected by the fission neutron activation. When the reactor tends to be critical, the fission neutron-induced LBE target activations are even greater than that induced by the proton beam. In the LBE itself, 96.66% of 210Po is induced by the fission neutrons. These results illustrate that fission neutrons are also essential for the radionuclides calculation of LBE and its structural parts. In addition, this study provides reference data for the radiation protection of CiADS and a more accurate method for the radionuclides study of the spallation target in ADS systems.

2021, (2): 1-2.

2021, 38(2): 117-122.   doi: 10.11804/NuclPhysRev.38.2020084

2021, 38(2): 123-128.   doi: 10.11804/NuclPhysRev.38.2021019

2021, 38(2): 129-135.   doi: 10.11804/NuclPhysRev.38.2021022

2021, 38(2): 136-146.   doi: 10.11804/NuclPhysRev.38.2021010

2021, 38(2): 147-152.   doi: 10.11804/NuclPhysRev.38.2021001

2021, 38(2): 153-158.   doi: 10.11804/NuclPhysRev.38.2020080

2021, 38(2): 159-165.   doi: 10.11804/NuclPhysRev.38.2020074

2021, 38(2): 166-174.   doi: 10.11804/NuclPhysRev.38.2020064

2021, 38(2): 175-181.   doi: 10.11804/NuclPhysRev.38.2020063

2021, 38(2): 182-189.   doi: 10.11804/NuclPhysRev.38.2020062

2021, 38(2): 190-195.   doi: 10.11804/NuclPhysRev.38.2020058

2021, 38(2): 196-202.   doi: 10.11804/NuclPhysRev.38.2021003

2021, 38(2): 203-209.   doi: 10.11804/NuclPhysRev.38.2020052

2021, 38(2): 210-214.   doi: 10.11804/NuclPhysRev.38.2021007

The Bohr-Lindhard (B-L) model is used to describe the classical electron-capture process. The impact-parameter dependence of the capture probability is derived by considering the impact-parameter dependence of the collision time between ion and atom. This model limits the impact parameter to be less than the capture radius. In the framework of the B-L model, although the contribution from all impact parameters may be studied through the spatial distribution function of electrons, the multiple numerical integral has to be carried out. In this work, it is proposed that the impact-parameter dependence of the electron-capture probability can be given by a simple exponential decay function based on the (B-L) model. Electron-capture cross sections for Aq+(q=2~6)-H collisions, and double-electron-capture cross sections for Aq+(q=3~6)-He collisions are calculated at low and intermediate velocities. The calculated results are in good agreement with the existing experimental data. The energy and charge-state dependences of the electron-capture process are well described. This work can also be used to calculate the cross sections of electron capture from He and H targets by other ions with different charge states.
2021, 38(2): 215-220.   doi: 10.11804/NuclPhysRev.38.2020066

In heavy-ion cancer therapy, Compton camera is a promising tool for online monitoring of the range of ions. Compton camera uses crystal detectors to determine the positions and deposited energies of the $\gamma$-rays. This will further introduce the errors and affect the actual imaging resolution of the Compton camera, due to the involved Doppler broadening effects influencing the image resolution. This work simulates the angular resolution measure originating from the Doppler broadening effects with Geant4 toolkit for 150 and 511 keV gamma, respectively, in different crystal materials. After optimizing the back-projection algorithm and improving the voxel in imaging interspace, the image resolution can be achieved better than 1.0 mm. An approximate formula is also being proposed to evaluate the image resolution based on the angular resolution measure.

2021, 38(2): 221-228.   doi: 10.11804/NuclPhysRev.38.2020075