JAEA-Conf 2011-002 - 日本原子力研究開発機構

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ENDF resonance parameters are based on Mughabghab and Chrien 2 , Simpson 3 , and Fricke et al. 4 The other highabundance isotopes, 158 Gd and 160 Gd, have few resonances, and their resonance parameters are based on Mughabghab and Chrien 2 , and Rahn et al. 5 The minority isotopes are 152 Gd and 154 Gd. Its resonance parameters come from Anufriev et al. 6 and Macklin. 7 This is the first experiment to use high-purity Gd isotopes of 155 Gd, 156 Gd, 157 Gd, 158 Gd, 160 Gd. Table I lists the isotopic content of the gadolinium samples used in this experiment. A more detailed description of the present measurement and analysis is given in Ref. 8. Properties/Sample Isotopic Composition [%] TABLE I General information about elemental Gadolinium 155 Gd 156 Gd 157 Gd 158 Gd 160 Gd 152 Gd 0.04
layout of the RPI LINAC facility. JAEA-Conf 2011-002 The RPI capture detector 9 is a 30.5-cm-diam30.5-cm-high hollow cylinder that contains 16 sections of thallium activated sodium iodide NaI(Tl) scintillator crystals. The cylinder is split perpendicular to its axis into two rings, and each ring contains eight equally sized pie-shaped NaI(Tl) segments. Each NaI(Tl) segment is optically isolated and hermetically sealed within an aluminum can and mounted on an RCA 8575 photomultiplier. The samples are placed by a computer-controlled sample changer into the center of the capture detector. The sample changer is capable of holding up to eight samples. The boron carbide liner (enriched in 10 B) around the sample reduces the scattering background by absorbing the neutrons that are scattered from the sample and preventing the scattered neutrons from being detected in the NaI(Tl) crystal. The detector system discriminates against the 478-keV gamma-ray from 10 B (n;,) reactions. The efficiency of the capture detector is ~75 % for a single 2 MeV gamma-ray. The efficiency of a detecting a capture event in gadolinium is close to 100 % and varies slightly by isotope and sample thickness. Reference 10 contains a description of the detector and its signal-processing electronics. Neutron capture data-taking and data-reduction techniques at the RPI are described in Refs. 11 and 12. The large amount of data collected in each capture measurement was subject to statistical integrity checks to verify the stability of the linac, the capture detector, and associated beam monitors. Any data that failed the integrity test were eliminated. Next, the data were dead-time corrected, normalized to beam monitors, and summed. The background was determined using normalized data measured with an empty aluminum can mounted on the sample changer. This background was subtracted from the normalized and summed capture spectra. The 16 individual capture spectrums were then summed into a single total spectrum. When an incident neutron is captured in the sample, a compound nucleus in an excited state is formed. The compound nucleus then de-excites to the ground state with the subsequent emission of gamma rays. The detection of these gamma rays allows one to measure the fraction of neutrons of a given energy that are captured if the incident neutron flux is known. This fraction of captures is known as the capture yield. Thus, for a uniform thickness sample and a parallel neutron beam incident perpendicularly to this sample, the capture yield is defined as the number of detected capture gamma rays divided by the product of the detector efficiency times the number of incident neutrons. Mathematically speaking, the capture yield is defined as the number of captures per incident neutron. In time of flight measurements the capture yield, Yi in TOF channel i was calculated by Y C B i i i Ksmi where Ci= dead-time-corrected and monitor-normalized count rate of the sample measurement Bi= dead-time-corrected and monitor-normalized background counting rate K= detector efficiency and flux normalization factor smi= smoothed, background-subtracted, and monitor-normalized neutron flux shape. The incident neutron flux shape was determined with the use of a thick 10 B4C sample that is mounted on the
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JAEA-Conf 2011-002 Proceedings of t
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JAEA-Conf 2011-002 31. Preliminary
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6.2 Measurement of neutron-induced
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JAEA-Conf 2011-002 Table 1 Comparis
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JAEA-Conf 2011-002 (T1/2=8,900,000
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JAEA-Conf 2011-002 Though words too
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JENDL-3.3 showed better applicabili
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ENDF. Thus this cross section store
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Acknowledgement JAEA-Conf 2011-002
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In the MALIBU program, isotope conc
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some minor actinides. For major act
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JAEA-Conf 2011-002 code MVP-BURN an
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JAEA-Conf 2011-002 [3] Measurements
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3.1 Experimental Set up JAEA-Conf 2
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References JAEA-Conf 2011-002 [1] N
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JAEA-Conf 2011-002 was large. The a
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JAEA-Conf 2011-002 4. Results and D
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Acknowledgments Present study inclu
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Fig. 1 A conceptural picture of the
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4. Theoretical studies Theoretical
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JAEA-Conf 2011-002 Fig.9 Comparison
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Ion source JAEA-Conf 2011-002 LE
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JAEA-Conf 2011-002 3. Readiness
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JAEA-Conf 2011-002
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JAEA-Conf 2011-002 Figure 1. An exa
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JAEA-Conf 2011-002 Figure 6. Compar
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JAEA-Conf 2011-002 calculation of d
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JAEA-Conf 2011-002 equilibrium emis
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JAEA-Conf 2011-002 Cowley et al. [1
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JAEA-Conf 2011-002 radiation protec
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Ztarget, Atarget are the numbers fo
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We described our formalism for calc
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2. Model
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JAEA-Conf 2011-002 reactions. Figur
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JAEA-Conf 2011-002 Fig. 3. The angu
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analysis of integral experiments [6
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A modified SRAC library was prepare
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JAEA-Conf 2011-002 approximately 0.
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JAEA-Conf 2011-002 constructing the
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Fig.9 Spectrum of gamma-ray followi
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JAEA-Conf 2011-002 in the same way
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JAEA-Conf 2011-002 [7]. For example
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JAEA-Conf 2011-002 For
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JAEA-Conf 2011-002 (5.0-9.0MeV), a
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components, the 0.56Wt% for hydroge
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Sensitivities of curium isotope con
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decreases of (n,g) reaction rates,
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5. Conclusion JAEA-Conf 2011-002 Wi
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2. Foundation of sensitivity analys
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JAEA-Conf 2011-002 where f g and f
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Fig.1 Sensitivity coefficient of th
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An outline of core configurations o
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0.010% 0.000% -0.010% -0.020% -0.03
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To clarify what nuclides and reacti
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Calculation was performed by the MV
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among these libraries, and the diff
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JAEA-Conf 2011-002 - 日本原子力研究開発機構

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