This paper is aimed at detecting the neutron spectrum of^(241)Am–Be, a widely used neutron source, with the SP9 ~3He proportional counter, which is a multi-sphere spectrometer system of eight thermal neutron detector...This paper is aimed at detecting the neutron spectrum of^(241)Am–Be, a widely used neutron source, with the SP9 ~3He proportional counter, which is a multi-sphere spectrometer system of eight thermal neutron detectors embedded in eight polyethylene(PE) spheres of varying diameters. The transport processes of a neutron in the multi-sphere spectrometer are simulated using the Geant4 code. Two sets of response functions of the PE spheres are obtained for calculating the^(241)Am–Be neutron spectrum.Response Function 1 utilizes the thermal neutron scattering model G4 Neutron HPThermal Scattering for neutron energies of ≤4 eV, and Response Function 2 has no thermal treatment. Neutron spectra of an^(241)Am–Be neutron source are measured and compared to those calculated by using the response functions. The results show that response function with thermal treatment is more accurate and closer to the real spectrum.展开更多
The extended Bonner sphere spectrometer （EBSS） at the HL-2A tokamak for the neutron spectrum is described. This device was developed on the basis of previous Bonner sphere spectrometry （BSS）, aiming to obtain a mo...The extended Bonner sphere spectrometer （EBSS） at the HL-2A tokamak for the neutron spectrum is described. This device was developed on the basis of previous Bonner sphere spectrometry （BSS）, aiming to obtain a more accurate neutron spectrum in the HL-2A tokamak hall. The previous BSS contained eight Bonner spheres （BS）. This EBSS contains 13 3He-filled detectors embedded in polyethylene spheres （PS）, pre-amplifiers, and a parallel processing data acquisition system （DAQ）. A response matrix is simulated in Geant4 taking the effect of the environment into account.展开更多
In the year 2002, Lin detected a nontrivial family in the stable homotopy groups of spheres ;π-6S which is represented by hngoγ^-3 ∈ Ext^6tA（Zp, Zp） in the Adams spectral sequence, where t = 2p^n（p- 1）＋ 6（p^2...In the year 2002, Lin detected a nontrivial family in the stable homotopy groups of spheres ;π-6S which is represented by hngoγ^-3 ∈ Ext^6tA（Zp, Zp） in the Adams spectral sequence, where t = 2p^n（p- 1）＋ 6（p^2 ＋p ＋ 1）（p- 1） and p ≥ 7 is a prime number. This article generalizes the result and proves the existence of a new nontrivial family of filtration s ＋ 6 in the stable homotopy groups of spheres πt1-8-6S which is represented by bygoγ^s＋3 ∈ Ext^s＋6＋t1Atl （Zp, Zp） in the Adams spectral sequence, where n≥ 4, 0 ≤ s 〈 p - 4, t1 = 2p^n（p- 1） ＋ 2（p- 1）（（s ＋ 3）p^2 ＋ （s ＋ 3）p ＋ （s ＋ 3）） ＋ s.展开更多
In this paper, it is proved that for p≥7 an arbitrary odd prime and 3≤s 〈 p, the homotopy elements β1λs and α1λs are nontrivial in the stable homotopy groups of spheres π＊S.
Real-time Bonner sphere spectrometry（BSS）at the HL-2A tokamak for the neutron spectrum diagnostic is described.The spectrometer consists of eight different size Bonner spheres made of polyethylene and with a ^3heliu...Real-time Bonner sphere spectrometry（BSS）at the HL-2A tokamak for the neutron spectrum diagnostic is described.The spectrometer consists of eight different size Bonner spheres made of polyethylene and with a ^3helium-filled detector in the center,pre-amplifiers,and parallelprocessing data acquisition system（DAQ）.Dynamic neutrons from plasma discharges of the HL-2A tokamak were measured and the real-time neutron spectrum was presented.展开更多
This study proves a general result on convergence of α2x ∈ ExtA^s＋2.tq＋2q＋1 （Zp, Zp） in the Adams spectral sequence and as a consequence, the study detects some new families in the stable homotopy groups of sph...This study proves a general result on convergence of α2x ∈ ExtA^s＋2.tq＋2q＋1 （Zp, Zp） in the Adams spectral sequence and as a consequence, the study detects some new families in the stable homotopy groups of spheres πtq＋2q-4S which is represented in the Adams spectral sequence by α2fn,α2fn,α2huhmhn ∈ ExtA^5,tq＋2q＋1（Zp,Zp） with tq=p^n＋1q＋2p^nq,2p^n＋1q_P^nq,p^uq＋p^mq＋p^nq,respectively, where α2∈Extα^2,2q＋1（Zp,Zp）,fn∈ExtA^3,p^n＋1q＋2p^nq（Zp,Zp）,fn∈ExtA^3,2p^n＋2q＋p^nq（Zp,Zp）,hn∈ExtA^1,p^nq（Zp,Zp）and p≥5 is a prime,q=2（p=-1）,n≥2.展开更多
中国先进研究堆(CARR)H-8水平孔道是提供中子的实验孔道,可以提供稳定的辐射场,对于不同的中子实验,其所需的中子能谱谱形不同,准确测量中子能谱具有重要意义。为测量H-8水平孔道中子能谱,研制一种以金活化片为热中子探测器的被动式单...中国先进研究堆(CARR)H-8水平孔道是提供中子的实验孔道,可以提供稳定的辐射场,对于不同的中子实验,其所需的中子能谱谱形不同,准确测量中子能谱具有重要意义。为测量H-8水平孔道中子能谱,研制一种以金活化片为热中子探测器的被动式单球中子能谱仪,使用MCNP程序对10-11~15 MeV能区的中子能量响应进行计算,并分析能量响应的合理性。在CARR堆导管大厅对单球谱仪进行测试实验,使用高纯锗探测器测量各金活化片活度,使用UGA(unfolding based on genetic algorithm)解谱程序对实验数据进行解谱计算。结果表明,导管大厅出射中子能量在10-9~10-6 MeV范围内,单球中子谱仪可以较为精确的给出中子能谱数据,适用于CARR堆H-8水平孔道中子能谱测量研究。展开更多
基金supported by ITER Plan National Major Project(No.2008GB109000)the Introduces Talents Scientific Research Project of Guizhou University(2014,No.32)
文摘This paper is aimed at detecting the neutron spectrum of^(241)Am–Be, a widely used neutron source, with the SP9 ~3He proportional counter, which is a multi-sphere spectrometer system of eight thermal neutron detectors embedded in eight polyethylene(PE) spheres of varying diameters. The transport processes of a neutron in the multi-sphere spectrometer are simulated using the Geant4 code. Two sets of response functions of the PE spheres are obtained for calculating the^(241)Am–Be neutron spectrum.Response Function 1 utilizes the thermal neutron scattering model G4 Neutron HPThermal Scattering for neutron energies of ≤4 eV, and Response Function 2 has no thermal treatment. Neutron spectra of an^(241)Am–Be neutron source are measured and compared to those calculated by using the response functions. The results show that response function with thermal treatment is more accurate and closer to the real spectrum.
基金supported by National Natural Science Foundation of China (No. 11375195, No. 11575184)the National Magnetic Confinement Fusion Energy Development Research (2013GB104003)
文摘The extended Bonner sphere spectrometer （EBSS） at the HL-2A tokamak for the neutron spectrum is described. This device was developed on the basis of previous Bonner sphere spectrometry （BSS）, aiming to obtain a more accurate neutron spectrum in the HL-2A tokamak hall. The previous BSS contained eight Bonner spheres （BS）. This EBSS contains 13 3He-filled detectors embedded in polyethylene spheres （PS）, pre-amplifiers, and a parallel processing data acquisition system （DAQ）. A response matrix is simulated in Geant4 taking the effect of the environment into account.
基金Supported by the National Natural Science Foundation of China (1051045)the Youth Project of Tianyuan Foundation of China (10426028)the China Postdoctoral,Science Foundation and Fund of the Personnel Division of Nankai University
文摘In the year 2002, Lin detected a nontrivial family in the stable homotopy groups of spheres ;π-6S which is represented by hngoγ^-3 ∈ Ext^6tA（Zp, Zp） in the Adams spectral sequence, where t = 2p^n（p- 1）＋ 6（p^2 ＋p ＋ 1）（p- 1） and p ≥ 7 is a prime number. This article generalizes the result and proves the existence of a new nontrivial family of filtration s ＋ 6 in the stable homotopy groups of spheres πt1-8-6S which is represented by bygoγ^s＋3 ∈ Ext^s＋6＋t1Atl （Zp, Zp） in the Adams spectral sequence, where n≥ 4, 0 ≤ s 〈 p - 4, t1 = 2p^n（p- 1） ＋ 2（p- 1）（（s ＋ 3）p^2 ＋ （s ＋ 3）p ＋ （s ＋ 3）） ＋ s.
文摘In this paper, it is proved that for p≥7 an arbitrary odd prime and 3≤s 〈 p, the homotopy elements β1λs and α1λs are nontrivial in the stable homotopy groups of spheres π＊S.
基金supported by National Natural Science Foundation of China(No.11375195)the National Magnetic Confinement Fusion Science Program of China(No.2013GB104003)
文摘Real-time Bonner sphere spectrometry（BSS）at the HL-2A tokamak for the neutron spectrum diagnostic is described.The spectrometer consists of eight different size Bonner spheres made of polyethylene and with a ^3helium-filled detector in the center,pre-amplifiers,and parallelprocessing data acquisition system（DAQ）.Dynamic neutrons from plasma discharges of the HL-2A tokamak were measured and the real-time neutron spectrum was presented.
文摘This study proves a general result on convergence of α2x ∈ ExtA^s＋2.tq＋2q＋1 （Zp, Zp） in the Adams spectral sequence and as a consequence, the study detects some new families in the stable homotopy groups of spheres πtq＋2q-4S which is represented in the Adams spectral sequence by α2fn,α2fn,α2huhmhn ∈ ExtA^5,tq＋2q＋1（Zp,Zp） with tq=p^n＋1q＋2p^nq,2p^n＋1q_P^nq,p^uq＋p^mq＋p^nq,respectively, where α2∈Extα^2,2q＋1（Zp,Zp）,fn∈ExtA^3,p^n＋1q＋2p^nq（Zp,Zp）,fn∈ExtA^3,2p^n＋2q＋p^nq（Zp,Zp）,hn∈ExtA^1,p^nq（Zp,Zp）and p≥5 is a prime,q=2（p=-1）,n≥2.
文摘中国先进研究堆(CARR)H-8水平孔道是提供中子的实验孔道,可以提供稳定的辐射场,对于不同的中子实验,其所需的中子能谱谱形不同,准确测量中子能谱具有重要意义。为测量H-8水平孔道中子能谱,研制一种以金活化片为热中子探测器的被动式单球中子能谱仪,使用MCNP程序对10-11~15 MeV能区的中子能量响应进行计算,并分析能量响应的合理性。在CARR堆导管大厅对单球谱仪进行测试实验,使用高纯锗探测器测量各金活化片活度,使用UGA(unfolding based on genetic algorithm)解谱程序对实验数据进行解谱计算。结果表明,导管大厅出射中子能量在10-9~10-6 MeV范围内,单球中子谱仪可以较为精确的给出中子能谱数据,适用于CARR堆H-8水平孔道中子能谱测量研究。
