Statistical error estimation of the Feynman-α method using the bootstrap method

Applicability of the bootstrap method is investigated to estimate the statistical error of the Feynman-α method, which is one of the subcritical measurement techniques on the basis of reactor noise analysis. In the Feynman-α method, the statistical error can be simply estimated from multiple measurements of reactor noise, however it requires additional measurement time to repeat the multiple times of measurements. Using a resampling technique called “bootstrap method,” standard deviation and confidence interval of measurement results obtained by the Feynman-α method can be estimated as the statistical error, using only a single measurement of reactor noise. In order to validate our proposed technique, we carried out a passive measurement of reactor noise without any external source, i.e. with only inherent neutron source by spontaneous fission and (α,n) reactions in nuclear fuels at the Kyoto University Criticality Assembly. Through the actual measurement, it is confirmed that the bootstrap method is applicable to approximately estimate the statistical error of measurement results obtained by the Feynman-α method.     

An applied limit of the bunching method for the Feynman-α analysis

Feynman-α method is used as the representative method in reactor noise analysis for the criticality monitoring. Feynman-α analysis needs a large amount of measurement time in its original process, though many researchers use the bunching method and its derived methods for the experimental data processing to shorten the measurement time. However, the detailed characteristics and the application limit of the bunching method have not been researched and discussed enough. This paper shows a possibility that the Bunching method is a method to reduce the probability fluctuation with the Y value only in the appearance. Moreover, the criteria for determining that the Y value is not an accidental product are also provided in this paper.     

A Generalized Analysis of Rossi-α Experiment

A generalized theory of the Rossi-α method is shown and is applied to the analysis of an experiment made with a remotely subcritical system.

Starting from the neutron transport equation, a general expression for the probability of detecting correlated neutrons is given, which is a function of the positions and sensitivities of the neutron detectors used in the experiment.

Some numerical examples for this expression are also given under the one-group diffusion approximation for comparison with the experiment. The agreement between them is satisfactory.     

Analysis of the Rossi-α Experiment through Pál-Bell's Equation

Pál -Bell's equation for the probability generating function of neutron counts has been analytically solved in the case of three time states, using two-forked approximation. From this solution it is found that all experimental data on neutron fluctuation consist individually of only three basic parameters. The average counting rate C, the decay constant α and the chain register rate C_r are in this instance chosen for the three fundamental measures of correlation. The original observation is presented that C_r can be obtained precisely by determining the waiting time distribution for the triggering of the time analyzer.

The correlated and uncorrelated parts of the Rossi-α data in a thermal system have been analyzed by this three-parameter scheme, and a consistent explanation is given of the results obtained.     

Fusion Core Imaging Experiment Based on the Shenguang II Facility

A laser fusion experiment was performed based on the Shenguang II facility. An image of thermonuclear burning region was obtained with a Fresnel zone plate-coded imaging technique, where the laser-driven target was served as an a-particle source, and the coded image obtained in the experiment was reconstructed by a numerical way.     

Fusion Core Imaging Experiment Based on the Shenguang Ⅱ Facility

A laser fusion experiment was performed based on the Shenguang Ⅱ Facility ,An image of thermonuclear burning region was obtained with a Fresnel zone plate-coded imaging technique,where the laser-driver target was served as an α-particle soure ,and the coded image obtained in the experiment was reconstructed by a numerical way.     

The Effect of the Decay Data on Activation Cross Section

The effect of the decay data on evaluation of activation cross section is investigated. Present work shows that these effects must be considered carefully when activation cross section is evaluated. Sometime they are main reason for causing the discrepancies among the experimental data.     

A System for the γ-Production Data Intercomparison and the Intercomparison of γ-Production Data for Fe, Cr, Ni from Major Evaluated Data Libraries

The γ-production data are very important for the nuclear engineering, especially for radioactive shielding. There are γ-production data in the major evaluated nuclear data libraries, such as ENDF/B-6(B6), JENDL-3(J3),JEF-2(JE2), BROND-2(BR2) and CENDL-2.1(C2) for important nuclides, especially for structure and shielding materials. And meanwhile, quite lots of measured data have been compiled in EXFOR format. To intercompare the γ-production data from the major evaluated data libraries, a system has been developed and used to Fe, Cr, Ni data from C2, B6, J3, JE2 and BR2.     

Effects of the radiative recombination on the intensity and polarization of the Ly-α emission of hydrogen-like ions

The intensity ratio of the to photon emission is analyzed for hydrogen-like Fe²⁵⁺ ions if their excitation arises in a plasma not only from the electron impact but also due to the radiative recombination (RR) of initially bare Fe²⁶⁺ ions. Under such conditions, the intensity ratio and the (degree of) linear polarization of the Ly-α₁ line are explored for collisions with an electron beam over a wide range of kinetic energies up to 50 keV. Apart from the direct population of the 2p_1/2,3/2 levels via the RR of bare ions, the contributions from radiative cascades and higher multipoles are taken into account by applying a fully relativistic theory for the motion of the electrons and the electron-photon coupling. Our calculations show an overall small effect of the RR upon the degree of the Ly-α₁ polarization as well as the intensity ratio under usual plasma conditions. However, the effects from the RR of initially bare ions may become significant at electron beam energies , for plasma conditions far away from ionization equilibrium with a relatively large proportion of bare Fe ions, as it may be realized in electron-beam ion trap experiments.     

Start of the Experiment on the Absolute Calibration of Particle Energy in VÉPP-4M near the τ-Lepton Production Threshold

An experiment, using the new detector Kedr, on the precise measurement of the -lepton mass is being readied on the VÉPP-4M. The resonance depolarization method is used for absolute calibration of the particle energy. The main difficulty in using a polarized beam at the -lepton production threshold (1777 MeV) is the closeness of an integral spin resonance (1763 MeV). Experiments observing the polarization of particles in VÉPP-4M after injection of the polarized beam from the VÉPP-3 storage booster with different detunings from resonance have been performed. For comparison, the depolarization time of a beam due to quantum fluctuations in the presence of characteristic disturbances of the guiding field is calculated. The temporal stability of the energy indications is studied.     

Discharge Plasma Assisted Adsorbents for Exhaust Treatment： A Comparative Analysis on Enhancing NOx Removal

An analysis has been made on the discharge plasma coupled with an adsorbent system for NOx removal. The cascaded plasma-adsorbent system may be perceived as a better alternative for the existing adsorbent-based abatement system in the industry. In this study the exhaust is sourced from a diesel generator set. It was observed that better NO removal in a plasma reactor can be made possible by achieving higher average fields and subsequent NO2 removal can be improved using an adsorbent system connected in cascade with the plasma system. The paper describes various findings pertaining to these comparative analyses.     

Breit interaction effects on the Kα angular distribution following the dielectronic recombination of high-Z ions

The angular distribution of the Kα hypersatellite radiation has been investigated for high-Z, helium-like ions following the K − LL dielectronic recombination of initially hydrogen-like projectiles in relativistic ion-atom collisions. A particular strong effect is found for the alignment of the 2s2p_1/2J = 1 (spin-forbidden) resonance that changes sign if, in addition to the static Coulomb repulsion, the Breit interaction is taken into account for the resonant electron capture. This change in the alignment of the recombined ion also leads to a remarkable shift in the angular distribution of the subsequent 2s2p_1/2J = 1 → 1s2s J = 0 Kα₂ photons from a dominantly perpendicular emission to one that occurs in parallel with the ion beam, and vice versa for the 2s2p_1/2J = 1 → 1s2s J = 1 line.     

Evaluation of ~(235)U Fission Product Yield Data and Study of the Dependence of Fission Yield Data on Neutron Energy

The ~(235)U(n,f) fission product yield data were evaluated for some important product nuclides ~(95)Zr, ~(99)Mo, ~(144)Ce and ~(147)Nd. The dependence of fission yield data on incident neutron energy was studied.     

A Prototype of the Read-out Subsystem of the BESIII DAQ Based on PowerPC

1 Overview of the data acquisi-tion system for BES IIIAfter having run successfully for more than tenyears, the BEPC e+ e- collider will be upgradedfor higher luminosity, which will be increased to1033 cm-2 ·sec-1 [1]. Therefore, its detector BESII willbe upgraded to BESIII in order to take advantage ofthis increased luminosity, named BESIII.Trigger rate and event size define the performance re-quirements for the data acquisition (DAQ) system. Forpeak luminosity, we expect a L1 t…     

Adjustment of the Parameters in the Calculations of the γ-Production Data

Introduction The γ-production data are very important for the nuclear engineering, especially for the calculations of the radiation shielding. Because the experimental values of the γ-production data can not satisfy the needs of the nuclear engineering both in the quantity of the nuclei and in the energy region covered by them, as the supplement, the theoretical calculations of the γ-production data are indispensable. The γ-production data in the nuclear reactions induced by neutrons include the γ-production cross sections, the γ-energy spectra, the γ-multiplicities and the reaction cross sections of the (n,γ) and the (n,xγ) reactions, where the (n,xγ) reactions mean     

Progress on Study of Nuclear Data Theory and Related Fields at the Theory Group of CNDC

The theory group of CNDC has made a lot of progress in nuclear reaction theory and its application as well as many other related fields in 1995. The recent progress in those fields are presented as the following. 1 Nuclear Reaction Theory Study and Its Applications     

Nuclear Data Sheets Update for A=195

The 1989 version of Nuclear Data Sheets for A=195 has been updated mainly on the basis of the experimental results from the ~(198)Pt(α,xnγ),~(195)Bi (from ~(181)Ta(~(20)Ne,6n) and ~(185)Re(~(16)O,6n)) EC decay, ~(181)Ta(~(18)O,xnγ),