Total Cross Sections for Neutron Nucleus Scattering

S. V. Suryanarayana,H. Naik,S. Ganesan,S. Kailas,R. K. Choudhury,김귀년 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

Ramsauer model is well known and widely applied to understand systematics of neutron nucleus total cross sections. In this work, we examined the role of nuclear effective radius parameter (r_0) on Ramsauer model fits of neutron total cross sections. We examined the Ramsauer model global analysis of the experimental neutron total cross sections reported by W. P. Abfalterer, F. B. Bateman, et. al., from 20 MeV to 550 MeV for nuclei ranging from Be to U. The global fits predict within ±8% deviation to data.It has been observed that a finer adjustment of r_0 parameter alone can give very good Ramsauer model description of neutron total scattering data within ±4% deviation. The required r_0 values for Ramsauer model fits are provided as a function of nuclear mass number. In optical model study, we have modified the real part of Koning-Deleroche potentials to fit the neutron total cross sections using SCAT2 code. The modified potentials have a different energy dependence beyond 200 MeV of neutron energy and fit the neutron total cross sections from C to Bi.

Mono-energetic Neutron Source Using the 7Li(p,n)7Be Reaction

G. D. Kim,H. J. Woo,W. Hong,Y. K. Kim 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.4

The facilities for the production and the measurement of neutrons with energies below 1000 keV were completed in 2008. The facilities are based on the 7Li(p,n)7Be reaction and a neutron timeof- flight (TOF) system. Neutrons with an energy width of 300 keV were obtained by controlling the thickness of Li. The energy spectrum, which was measured by using TOF, was established by the resonance states of Al below energies of about 1000 keV. This width is in good agreement, within about 2%, with the attenuation energy of incident protons, which was calculated by using the Stopping and Range of Ions in Matter (SRIM) code. Neutron total cross-sections on Al and W were measured by using these neutrons and were compared with the data in the Evaluated Nuclear Data File-6 (ENDF-6). The facilities for the production and the measurement of neutrons with energies below 1000 keV were completed in 2008. The facilities are based on the 7Li(p,n)7Be reaction and a neutron timeof- flight (TOF) system. Neutrons with an energy width of 300 keV were obtained by controlling the thickness of Li. The energy spectrum, which was measured by using TOF, was established by the resonance states of Al below energies of about 1000 keV. This width is in good agreement, within about 2%, with the attenuation energy of incident protons, which was calculated by using the Stopping and Range of Ions in Matter (SRIM) code. Neutron total cross-sections on Al and W were measured by using these neutrons and were compared with the data in the Evaluated Nuclear Data File-6 (ENDF-6).

Improved Neutron Capture Cross Section Measurements with the n_TOF Total Absorption Calorimeter

E. Mendoza,V. Becares,A. Casado,D. Cano-Ott,M. Fernandez-Ordonez,E. Gonzalez-Romero,C. Guerrero,T. Martinez,J. J. Vidriales,J. Andrzejewski,J. Marganiec,J. Perkowski,L. Audouin,B. Berthier,L. Tassan-G 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

The n_TOF collaboration operates a Total Absorption Calorimeter (TAC) [1] for measuring neutron capture cross-sections of low-mass and/or radioactive samples. The results obtained with the TAC have led to a substantial improvement of the capture cross sections of ^(237)Np and ^(240)Pu [2].The experience acquired during the first measurements has allowed us to optimize the performance of the TAC and to improve the capture signal to background ratio, thus opening the way to more complex and demanding measurements on rare radioactive materials. The new design has been reached by a series of detailed Monte Carlo simulations of complete experiments and dedicated test measurements. The new capture setup will be presented and the main achievements highlighted. KEYWORDS: ND2010, nuclear data, n\textunderscore TOF, background, Monte Carlo, neutron, time of flight, cross section, calorimeter, shielding, simulation, total absorption, gamma ray, neutron capture.

Measurements of Neutron Total Cross-Section of Natural Silver in the Energy Region from 0.01 to 10 eV

신성균,조무현,김귀년,이만우 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.72 No.1

We measured the neutron total cross-section of natural Ag in the energy region from 0.01 eV to 10 eV by the neutron time-of-flight method with a data acquisition system based on the flash analog to digital converter. The experiment was performed at Pohang Neutron Facility, which consists of a 100 MeV electron linac, a water-cooled Ta-target with a water moderator and a 6Li-ZnS(Ag) scintillator located at 11 m long time-of-flight path. The background level has been determined by using notch filters, which consist of Co, In, Dy and Cd plates. The present averaged neutron total cross-sections in the thermal neutron energy region are compared to those from the previous measurements and the evaluated data. The differences between the present and the evaluated averaged cross-sections were less than 2%.

Neutron Total Cross-section Measurements with the 6Li-ZnS(Ag) Scintillator (BC702) Employing a Neutron and Noise Separation Technique

신성균,계용욱,조무현,Won Namkung,김귀년,이만우,강영록 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.64 No.9

The neutron total cross-section of natural Dy has been measured in the energy region from 0.01to 100 eV by using the neutron time-of-flight method at Pohang Neutron Facility, which consistsof an electron linear accelerator, a water-cooled Ta target with a water moderator, and a timeof-flight path with an 11-m length. A 6Li-ZnS(Ag) scintillator with a diameter of 12.5 cm and athickness of 1.5 cm has been used as a neutron detector, and a metallic Dy plate has been used forthe neutron transmission measurement. The background level has been determined by using notchfilters of Co, Ta, and Cd sheets. In order to reduce the gamma rays from bremsstrahlung and fromneutron capture, we have employed a neutron-gamma separation system based on their differentpulse shapes.

Neutron Capture Measuremetns on Minor Actinides at the n_TOF Facility at CERN: Past, Present and Future

D. Cano-Ott,F. Alvarez-Velarde,E. Gonzalez-Romero,C. Guerrero,T. Martinez,E. Mendoza,D. Villamarin,M. C. Vicente,U. Abbondanno,N. Colonna,M. H. Meaze,S. Marrone,G. Tagliente,R. Terlizzi,F. Belloni,K. 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

The successful development of advanced nuclear systems for sustainable energy production and nuclear waste management depends on high quality nuclear data libraries. Recent sensitivity studies and reports [1][2][3] have identified the need for substantially improving the accuracy of neutron cross-section data for minor actinides. The n_TOF collaboration has initiated an ambitious experimental program for the measurement of neutron capture cross sections of minor actinides. Two experimental setups have been constructed for this purpose: a Total Absorption Calorimeter (TAC) [4] for measuring neutron capture cross-sections of low-mass and/or radioactive samples and a set of two low neutron sensitivity C_6D_6 detectors for the less radioactive materials.

Measurement of Fast Neutron Total Cross Sections on natO, natSi, and natSiO2

김기동,최한우,우형주,홍완 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.3

Neutron total cross sections on natSi and natSiO2 were measured in the energy range from 0.7 MeV to 2.0 MeV by using a time-of-flight (TOF) system and a 1.7-MV tandem-type accelerator at the Korea Institute of Geoscience and Mineral Resources (KIGAM). Fast neutron sources were obtained by the 7Li(p,n)7Be reaction and the 3H(p,n)3He reaction. The TOF system with a flight length of 4.3 m consists of a time pick-up module and a plastic scintillator with a diameter of 7.54 cm and a length of 1 cm. The samples used for measuring the neutron total cross sections on natSi and natSiO2 were cylindrical Si ingot and cylindrical quartz, respectively. A correction in the calculation of neutron total cross section due to the singly-scattered neutrons for the samples was performed by using diffraction theory based on a continuum model. The total cross section on natO was obtained by extracting that on natSi from that on natSiO2. The neutron total cross sections on natO and natSi were compared with those of the evaluated nuclear data files (ENDF).

Measurement of Fast Neutron Total Cross Sections on ^(nat)Ta and ^(nat)Bi at MeV Energy Range

김기동,우형주,양태근,이삼열,이영욱 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.3

The reported values of the fast neutron total cross section on ^(nat)Ta of JEFF (nuclear data in Europe) at energies below the MeV ranges are different from those of JENDL (nuclear data in Japan). Those on ^(nat)Ta and ^(nat)Bi were measured in the energy range from 0.7 MeV to 2.0 MeV by the using a time-of-flight (TOF) system and a 1.7-MV tandem-type accelerator at the Korea Institute of Geoscience and Mineral Resources (KIGAM). Fast neutrons were obtained by using the ^7Li(p,n)^7Be reaction and the ^3H(p,n)^3He reaction. The TOF system with a flight length of 4.3m consists of a time pick-up module and a plastic scintillator with a diameter of 7.54 cm and a length of 1 cm. The samples of ^(nat)Ta and natBi that were used for measuring the neutron total cross sections were cylinders with diameters of 3 cm and lengths of 1.2 cm.. A collection in the calculation of the neutron total cross section due to singly-scattered neutrons was performed by using diffraction theory based on a continuum model. The neutron total cross sections on ^(nat)Ta and ^(nat)Bi were compared with those of the evaluated nuclear data files (ENDF).

Nuclear Data Production Facilty of KIGAM

G. D. Kim,H. J. Woo,H. W. Choi,J. K. Kim,Y. O. Lee 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

Nuclear data production project as one of the nation-wide nuclear R&D programs was launched by the Korea Atomic Energy Research Institute (KAERI) in 2000. We wanted to construct an infrastructure for nuclear data production with a high reliability. So KIGAM designed and fabricated a proton beam pulsing and bunching system to remove the signal of the delayed gamma-ray electronically and to allow the neutron energy to be defined. A TOF system was also constructed to measure neutron cross section on a natural sample of Y at the energy range from 0.7 MeV to 1.2 MeV. The repetition time and the beam width of the proton pulsed beam were obtained to be 125ns and about 2 ns, respectively. The neutron total cross section of ^(89)Y which was measured by this facility was compared with that of ENDF. In this report, an overview of the facility with its current status and prospects for the future will be presented.

Time of Flight System for MeV Neutron

G. D. Kim,H. W. Choi,H. J. Woo,김용균 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.4

The fast neutron facility with a prototype detecting system at the Korea Institute of Geoscience and Mineral Resources (KIGAM) was constructed in 2007. The detecting system was upgraded by changing the detecting sensor and its size and by changing the distance from the detector to the neutron target. The reaction with a Ti- target was used to estimate the time resolution of the upgraded system. The time resolution of the system was observed to be 36 keV (1.79 ns) at 2.077 MeV by analyzing the absorption width of the neutron energy spectrum for . The main factor for the time resolution of the system is thought to be a variation in the repetition time of the bunching beam. The width of the neutron energy spectrum was 150 keV, which corresponded to the proton energy loss caused by a Ti thickness of 2 mg/2 (4.44 ) on the Ti- target. The neutron total cross sections for and were measured by using the upgraded detecting system and the results are compared with the data for Evaluated Nuclear Data File-VI (ENDF-VI).