JAEA-Conf 2011-002 - 日本原子力研究開発機構

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eports of data of carbon-ion incident neutron-production double-differential cross sections (DDX) on biological elements are very few [4, 5]. The experimental cross sections of neutron-production are required to be simulated with high accuracy. Especially, the accurate data around neutron energy of several MeV is required because such an energy neutron has a large relative biological effectiveness (RBE). Therfore, we measured the neutron-production double-differential cross sections for 290 MeV/u oxygen ions incidence on a carbon target of natural isotopic composition. Because of diffculty in preparation of a oxygen target, we performed the natC( 16O, xn) DDX measurement to conduct inverse reaction analysis. The experimental data are compared with calculated results by the PHITS2 code [6]. 2. Experimental procedure NE213 (φ12.7 cm×12.7 cm) NE102A (2 mm thick) 60° 2.9 m 2.6 m 75° 90° 2.4 m 45° 3.5 m JAEA-Conf 2011-002 Concrete Shield 30° 4.0 m Carbon Target (2.12 cm thick) Beam Pick Up (0.5 mm thick) 15° 4.0 m 7.0 m Iron Shield Al Plate Beam Dump HIMAC PH2 Beam Line 290 MeV/u Oxygen Ion Incidence Fig. 1: Illustration of experimental setup The experiment was carried out at the PH2 beam line at the heavy ion accelerator facility HIMAC of the National Institute of Radiological Sciences, Chiba, Japan. A schematic view of the experimental arrangement is illustrated in Fig. 1. The 290 MeV/u oxygen ions were employed as incident particles and a carbon plate of natural isotopic composition was chosen as an irradiation target. The beam emerged from a vacuum duct through a 100 μm thick aluminum window. Before impinging on the target, the beam traversed a beam pick up detector, which was an NE102A plastic scintillator in front of the target. The beam pick up detector provided the signal for the time-of-flight (TOF) measurement and the number of incident particles. The detector was 3 cm in diameter and was 0.5 mm thick so as to reduce the energy loss of incident beam inside it. The beam irradiated the carbon target, having the dimension of 5 × 5 × 1.5 cm3 . A carbon plate was placed at an angle of 45◦ to the beam line as a target. The beam traveled in
the air and stopped at a beam dump placed 7 m downstream from the target. Emitted neutrons were detected with NE213 liquid organic scintillators, which dimension was 12.7 cm in diameter and 12.7 cm thick. The NE213 detectors were placed to measure angular distributions at 15 ◦ ,30 ◦ ,45 ◦ ,60 ◦ ,75 ◦ and 90 ◦ . Scintillation lights from the NE213 liquid organic scintillators are originated from as well as γ-rays and charged particles. Since the synchrotron was operated in a pulse mode (0.3 Hz repetition cycle) and incident oxygen beam intensity was very weak in level of 104∼105 particles/3.3 s, the number of incident oxygens can be individually counted. A veto detector, 150 × 150 × 2mm3 , made of NE102A plastic scintillator, was set in front of each NE213 scintillator to eliminate charged particle events. In order to reduce neutrons from the beam dump, a couple of an iron of 63 cm thick and a concrete of 50 cm thick shields was placed between the detectors and beam dump. For measurement of background neutrons, the measurement with an iron shadow bar of 110 cm thick set between a target and detector were carried out. 3. Data analysis In this measurement, the beam pick up detecter detects not only the single incident oxygen events but also the plural incident oxygen events. As clearly shown in Fig. 2, when two or three projectiles pass through the beam pick up detecter coincidentally, the pulse heights appear twice or three times higher than that of single projectile. The ratio of events obtained by single projectile to the all events was employed to correct the number of projectiles. Count [-] 3 10 2 10 10 Single Incident Particle Events 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 ADC [ch] JAEA-Conf 2011-002 Fig. 2: spectrum of the beam pick up detector Count [-] 3 10 2 10 10 1 Foreground Background (Shadow Bar) Flash γ-Ray 500 1000 1500 2000 2500 3000 TDC [ch] Fig. 3: An example of TOF spectra Typical measured TOF spectra are shown in Fig. 3. Both foreground and background spectra contain neutron and γ-ray events. The flash γ-rays were generated from the target
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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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4. Conclusions We have compared nuc
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of MeV region with highest cosmic-r
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JAEA-Conf 2011-002 events can be id
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JAEA-Conf 2011-002 models and its p
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JAEA-Conf 2011-002
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JAEA-Conf 2011-002 xx
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JAEA-Conf 2011-002 1. The recent ac
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JAEA-Conf 2011-002 4. Conceptual de
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The Institute's staff of about 280
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3. Nuclear Theory Laboratory JAEA-C
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JAEA-Conf 2011-002 References [1] P
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JAEA-Conf 2011-002 reaction 6 Li +
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Using the approximated distribution
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momentum of the constituents of P.
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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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