Systematic Study on KeV-Neutron Capture Reaction of Se Isotopes

M. Igashira,S. Kamada,T. Katabuchi,M. Mizumoto 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

Systematic measurements and calculations of neutron capture cross sections and capture gamma-ray spectra of all stable Se isotopes ^(74, 76, 77, 78, 80, 82)Se were performed in a neutron energy region from 10 to 600 keV, using a pulsed neutron source by the ^7Li(p,n)^7Be reaction. Highly isotopically enriched Se samples and standard Au samples were used. The capture gamma rays from each sample were detected with an anti-Compton NaI(Tl) spectrometer by means of a time-of-flight method. The capture cross sections were derived by using a pulse-height weighting technique and the standard capture cross sections of ^(197)Au. The capture gamma-ray spectra were obtained by unfolding the observed capture gamma-ray pulse-height spectra. In the calculations, a computer code, POD, was utilized. The calculated results were compared with the experimental results. The present experimental and calculated results were compared with previous measurements and evaluated values.

Evaluation of Neutron Capture Gamma-ray Spectra for ⁸⁹Y, ⁹³Nb, ¹²⁷I, ¹³³Cs, ¹⁴¹Pr, ¹⁹⁷Au, ^natTl, and ²⁰⁹Bi

KIM, Hyeong Il,YI, Mi Ja,LEE, Young-Ouk Atomic Energy Society of Japan 2007 Journal of nuclear science and technology Vol.44 No.8

<P>The neutron capture gamma-ray spectra for 8 nuclides, <SUP>89</SUP>Y, <SUP>93</SUP>Nb, <SUP>127</SUP>I, <SUP>133</SUP>Cs, <SUP>141</SUP>Pr, <SUP>197</SUP>Au, <SUP>nat</SUP>Tl, and <SUP>209</SUP>Bi, were calculated by using the Hauser-Feshbach statistical model, and their results were compared with the available experimental data. Two dominant ingredients to perform the statistical calculation were the level densities described by the Gilbert-Cameron approach with an improved systematics, and the gamma-ray transmission coefficients described by gamma-ray strength functions. Although various gamma-ray strength functions with a Lorentzian formula have been developed by using the photonuclear data or a microscopic analysis, they have failed to reproduce the occasional anomalous bumps observed near or below a neutron binding. In this work, we could reproduce the bumps well by adding a Lorentzian with an energy-temperature dependent width into a giant electric dipole resonance with an enhanced generalized Lorentzian. In addition, we introduced a correction function so as to compensate for the shortcomings due to missing levels or level-cuts.</P>

Measurement of Neutron Capture Gamma-ray Spectrum of Natural Gold in the keV Energy Region

Jae Hong Lee,Samyol Lee,Sangbock Lee,Junhaeng Lee,Gyehwan Jin 한국방사선학회 2007 한국방사선학회 논문지 Vol.1 No.1

keV-neutron capture gamma-ray spectrum of 197Au(natural gold) sample have been measured in neutron energy range from 10 to 90 keV using the 3-MV pelletron accelerator of the Research Laboratory for Nuclear Reactors at the Tokyo Institute of Technology. Pulsed keV neutrons were produced from the 7Li(p,n)7Be reaction by bombarding on the 7Li target with the 1.5-ns bunched proton beam. The incident neutron spectrum on the Au sample was measured by a 6Li-glass scintillation detector and TOF method. Capture gamma-rays from Au sample were measured by anti-Compton NaI(TI) spectrometer. Five average neutron energy regions were selected to obtain the neutron capture spectrum. Several gamma-ray peaks in the spectrum were found in the present experiment. 동경공업대학교의 3MV 펠레트론가속기를 사용하여 10에서 90keV 영역에 대하여 197 Au의 중성자포획 스펙트럼을 측정하였다. 중성자 펄스빔은 7Li(p,n)7 Be반응을 통하여 발생되었다. 사용되어진 양성자 빔 의 폭은 1.5-ns였다. 금 시료에 입사된 중성자의 에너지 스펙트럼은 6 Li-glass 섬광검출기의 중성자 비행 시간법을 사용하여 측정하였다. 금 시료의 중성자포획에 의해서 발생된 감마선은 anti-Compton NaI(TI) 검출장비를 사용하여 측정되었다. 본 연구에서는 5개의 중성자 에너지 역영을 선택했고, 각각의 에너지 영역에서 얻어진 감마선파고스펙트럼을 표시하였다. 본 연구에서 얻어진 스펙트럼은 처음으로 얻어진 결과이며, 중성자 결합에너지부근에 몇 개의 천이 피크가 보인다.

Measurement of Neutron Capture Gamma-ray Spectrum of Natural Gold in the keV Energy Region

Lee, Jae-Hong,Lee, Sam-Yol,Lee, Sang-Bock,Lee, Jun-Haeng,Jin, Gye-Hwan The Korean Society of Radiology 2007 한국방사선학회 논문지 Vol.1 No.1

keV-neutron capture gamma-ray spectrum of $^{197}Au$(natural gold) sample have been measured in neutron energy range from 10 to 90 keV using the 3-MV pelletron accelerator of the Research Laboratory for Nuclear Reactors at the Tokyo Institute of Technology. Pulsed keV neutrons were produced from the $^7Li(p,n)^7Be$ reaction by bombarding on the $^7Li$ target with the 1.5-ns bunched proton beam. The incident neutron spectrum on the Au sample was measured by a $^6Li$-glass scintillation detector and TOF method. Capture gamma-rays from Au sample were measured by anti-Compton NaI(TI) spectrometer. Five average neutron energy regions were selected to obtain the neutron capture spectrum. Several gamma-ray peaks in the spectrum were found in the present experiment. 동경공업대학교의 3MV 펠레트론가속기를 사용하여 10에서 90keV 영역에 대하여 $^{197}Au$의 중성자포획 스펙트럼을 측정하였다. 중성자 펄스빔은 $^7Li(p,n)^7Be$반응을 통하여 발생되었다. 사용되어진 양성자 빔의 폭은 1.5-ns였다. 금 시료에 입사된 중성자의 에너지 스펙트럼은 $^6Li$-glass 섬광검출기의 중성자 비행시간법을 사용하여 측정하였다. 금 시료의 중성자포획에 의해서 발생된 감마선은 anti-Compton NaI(TI) 검출장비를 사용하여 측정되었다. 본 연구에서는 5개의 중성자 에너지 역영을 선택했고, 각각의 에너지영역에서 얻어진 감마선파고스펙트럼을 표시하였다. 본 연구에서 얻어진 스펙트럼은 처음으로 얻어진 결과이며, 중성자 결합에너지부근에 몇 개의 천이 피크가 보인다.

Simulation of Gamma-ray/Neutron Detectors in Neutron-induced Gamma-ray Spectroscopy Sonde

Jihye Jeon,Chang Je Park,Geehyun Kim 대한방사선방어학회 2017 대한방사선방어학회 학술발표회 논문요약집 Vol.2017 No.11

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.

What Do s- and p-wave Neutron Average Radiative Widths Reveal?

S. F. Mughabghab 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

A first observation of two resonance-like structures at mass numbers 92 and 112 in the average capture widths of the p-wave neutron resonances relative to the s-wave component is interpreted in terms of a spin-orbit splitting of the 3p single-particle state into p_(3/2) and p_(1/2) components at the neutron separation energy. A third structure at about A = 124, which is not correlated with the 3p-wave neutron strength function, is possibly due to the Pygmy Dipole Resonance. Five significant results emerge from this investigation: (i) The strength of the spin-orbit potential of the optical-model is determined as 5.7 ± 0.5 MeV, (ii) Non-statistical effects dominate the p-wave neutron-capture in the mass region A = 85 - 130, (iii) The background magnitude of the p-wave average capture-width relative to that of the s-wave is determined as 0.50 ± 0.05, which is accounted for quantitatively in terms of the generalized Fermi liquid model of Mughabghab and Dunford,(iv) The p-wave resonances are partially decoupled from the giant-dipole resonance (GDR), and (v) Gamma-ray transitions, enhanced over the predictions of the GDR, are observed in the ^(90)Zr - ^(98)Mo and Sn-Ba regions.

Measurement of (γ,n) Cross Sections of Se Isotopes Using Laser-Compton Scattering γ-rays

F. Kitatani,S. Goko,H. Harada,H. Utsunomiya,H. Akimune,H. Toyokawa,K. Yamada 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

The photo-nuclear cross sections of Se isotopes (^(80)Se, ^(78)Se, ^(77)Se, ^(76)Se) were measured with laser-Compton scattering (LCS) γ-rays to supply fundamental data for the estimation of the inverse reaction cross sections, i.e., the ^(79)Se(n,γ)^(80)Se cross section. Enriched Se isotope samples were irradiated with LCS γ-rays whose maximum energy was varied from each near neutron separation energy to each threshold energy (γ, 2n) of reaction. The energy distributions of LCS γ-rays were precisely determined using a high-resolution high-energy photon spectrometer (HHS). Emitted neutrons were detected by a high efficiency 4π - ^3He detector. The excitation functions of the photo-nuclear cross section of Se isotopes were determined. The energy point corresponding to each cross section was deduced using the accurately determined energydistribution of LCS γ-rays.