An innovative monochromator shielding is designed and implemented for the cold neutron spectrometers XINGZHI and BOYA operated by Renmin University of China at China Advanced Research Reactor.Via Monte Carlo simulatio...An innovative monochromator shielding is designed and implemented for the cold neutron spectrometers XINGZHI and BOYA operated by Renmin University of China at China Advanced Research Reactor.Via Monte Carlo simulations and careful mechanical designs,a shielding configuration has been successfully developed to satisfy safety requirements of below 3μSv/h dose rate at its exterior,meanwhile fulfilling space,floor load and nonmagnetic requirements.Composite materials are utilized to form the sandwich-type shielding walls:the inner layer of boron carbide rubber,the middle layer of steel-encased lead and the outer layer of borated polyethylene.Special-shaped liftable shielding blocks are incorporated to facilitate a continuous adjustment of the neutron energy while preventing radiation leakage.Our work has demonstrated that by utilizing composite shielding materials,along with the sandwich structure and liftable shielding blocks,a compact and lightweight shielding solution can be achieved.This enables the realization of advanced neutron scattering instruments that provide expanded space of measurement,larger energy and momentum coverage,and higher flux on the sample.This shielding represents the first of its kind in neutron scattering instruments in China.Following its successful operation,it has been subsequently employed by other neutron instruments across the country.展开更多
We report an investigation on the single crystal growth,magnetic and transport properties of Eu In_(2)(As_(1-x)P_(x))_(2(0≤x≤1).The physical properties of axion insulator candidate Eu In;As;can be effectively tuned ...We report an investigation on the single crystal growth,magnetic and transport properties of Eu In_(2)(As_(1-x)P_(x))_(2(0≤x≤1).The physical properties of axion insulator candidate Eu In;As;can be effectively tuned by P-doping.With increasing x,the c-axis lattice parameter decreases linearly,the magnetic transition temperature gradually increases and ferromagnetic interactions are enhanced.This is similar to the previously reported high pressure effect on Eu In_(2)As_(2).For x=0.40,a spin glass state at T_(g)=10 K emerges together with the observations of a butter-fly shaped magnetic hysteresis and slow magnetic behavior.Besides,magnetic transition has great influence on the charge carriers in this system and negative colossal magnetoresistance is observed for all P-doped samples.Our findings suggest that Eu In_(2)(As_(1-x)P_(x))_(2) is a promising material playground for exploring novel topological states.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12004426,U2030106,and 12304185)the National Key Scientific Instrument and Equipment Development Project of NSFC(Grant No.11227906)the National Key R&D Program of China(Grant No.2023YFA1406500)。
文摘An innovative monochromator shielding is designed and implemented for the cold neutron spectrometers XINGZHI and BOYA operated by Renmin University of China at China Advanced Research Reactor.Via Monte Carlo simulations and careful mechanical designs,a shielding configuration has been successfully developed to satisfy safety requirements of below 3μSv/h dose rate at its exterior,meanwhile fulfilling space,floor load and nonmagnetic requirements.Composite materials are utilized to form the sandwich-type shielding walls:the inner layer of boron carbide rubber,the middle layer of steel-encased lead and the outer layer of borated polyethylene.Special-shaped liftable shielding blocks are incorporated to facilitate a continuous adjustment of the neutron energy while preventing radiation leakage.Our work has demonstrated that by utilizing composite shielding materials,along with the sandwich structure and liftable shielding blocks,a compact and lightweight shielding solution can be achieved.This enables the realization of advanced neutron scattering instruments that provide expanded space of measurement,larger energy and momentum coverage,and higher flux on the sample.This shielding represents the first of its kind in neutron scattering instruments in China.Following its successful operation,it has been subsequently employed by other neutron instruments across the country.
基金supported by the National Natural Science Foundation of China(Grant Nos.12074426,11227906and U2030106)the Fundamental Research Funds for the Central Universities,the Research Funds of Renmin University of China(Grant No.20XNLG19)。
文摘We report an investigation on the single crystal growth,magnetic and transport properties of Eu In_(2)(As_(1-x)P_(x))_(2(0≤x≤1).The physical properties of axion insulator candidate Eu In;As;can be effectively tuned by P-doping.With increasing x,the c-axis lattice parameter decreases linearly,the magnetic transition temperature gradually increases and ferromagnetic interactions are enhanced.This is similar to the previously reported high pressure effect on Eu In_(2)As_(2).For x=0.40,a spin glass state at T_(g)=10 K emerges together with the observations of a butter-fly shaped magnetic hysteresis and slow magnetic behavior.Besides,magnetic transition has great influence on the charge carriers in this system and negative colossal magnetoresistance is observed for all P-doped samples.Our findings suggest that Eu In_(2)(As_(1-x)P_(x))_(2) is a promising material playground for exploring novel topological states.
