The Experts below are selected from a list of 201 Experts worldwide ranked by ideXlab platform

Kengo Hashimoto - One of the best experts on this subject based on the ideXlab platform.

  • experimental study of Neutron counting in a zero power reactor driven by a Neutron source inherent in highly enriched uranium fuels
    Journal of Nuclear Science and Technology, 2019
    Co-Authors: Atsushi Sakon, Kunihiro Nakajima, Sinya Hohara, Kengo Hashimoto
    Abstract:

    ABSTRACTEven a zero-power reactor core containing highly enriched uranium has a weak Neutron source inherent in uranium 235, and consequently, a Neutron Counter placed closely to the core without external Neutron source registers a certain counting rate. The study of the counting is very important for zero-power reactor physics experiments with a high precision. In this experimental study, first, at a shutdown state of the UTR-Kinki reactor without start-up Neutron source, a pulse height distribution of output signals from a Neutron proportional Counter was measured to confirm that these signals resulted from Neutron detections. At several subcritical states of the UTR, then, the Feynman-α analysis was carried out to confirm that the Neutrons detected by the Counter must be fission Neutrons multiplied by fission chain reactions. The correlation amplitude measured in the Feynman-α analysis was much higher than that measured in a previous drive by start-up source. Further, it was also confirmed that the sub...

  • Dead-time measurement for radiation Counters by variance-to-mean method
    Journal of Nuclear Science and Technology, 1996
    Co-Authors: Kengo Hashimoto, Kei Ohya, Yoshihiro Yamane
    Abstract:

    The variance-to-mean ratios of counts accumulated during a time-gate were measured as a function of gate width for several Geiger-Mueller(GM) and Neutron proportional Counters. The measured ratios asymptotically decreased with an increase in gate width. The ratio for a GM Counter was saturated in about 400 μs of gate width, while that for a Neutron Counter was done in about 40 μs. Applying the first- and second-order formulae derived from the Muller's expression for the variance-to-mean ratio, the dead times of these Counters were inferred from these saturated ratios. In the count-rate range above 1,000cps for the GM Counter and above 12,000cps for the Neutron Counter, the dead times obtained by the first-order formula apparently depended on count rate. On the contrary, the application of the second-order formula sufficiently reduced the count-rate dependence. The dead times obtained by the second-order formula were consistent with those by the previous two-source or reactor-power variational methods.

Katsuhisa Kudo - One of the best experts on this subject based on the ideXlab platform.

  • A spherical Neutron Counter with an extended energy response for dosimetry
    Radiation Protection Dosimetry, 1997
    Co-Authors: H. Toyokawa, Akira Uritani, Chizuo Mori, N. Takeda, Katsuhisa Kudo
    Abstract:

    Neutron Counter which is applicable to spectrometry and dosimetry over a wide energy range has been developed. It gives energy spectra, integral fluences and dose equivalent of incident Neutrons with energies from thermal to 15 MeV. The Counter consists of a spherical polyethylene moderator and three slender 3 He position-sensitive proportional Counters inserted into the moderator. The position-sensitive proportional Counters give detection position profiles of Neutrons, slowed down to thermal energies in the spherical moderator, which give the above mentioned information. The responses of the Counter as a function of the Neutron energy were calculated with Monte Carlo simulations. The feasibility of the Counter for applications to Neutron spectrometry and dosimetry was examined with an unfolding method. It is shown that the Counter is applicable to the spectrometry and dosimetry of Neutrons over a wide energy range.

  • Performance of a spherical Neutron Counter for spectroscopy and dosimetry
    IEEE Transactions on Nuclear Science, 1997
    Co-Authors: H. Toyokawa, Akira Uritani, Chizuo Mori, Michio Yoshizawa, N. Takeda, Katsuhisa Kudo
    Abstract:

    A spherical Neutron Counter for spectroscopy and dosimetry has been developed. The Counter consists of a spherical polyethylene moderator and three slender /sup 3/He position-sensitive proportional Counters. Rough measurements of Neutron fluence spectra and ambient dose equivalents, H*(10), have been done in the moderated-Neutron field of JAERI. Characteristics of the Counter are examined and compared with those of a Bonner sphere Neutron spectrometer.

  • Neutron spectrometer with position-sensitive proportional Counters
    Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 1996
    Co-Authors: H. Toyokawa, Akira Uritani, Chizuo Mori, Michio Yoshizawa, N. Takeda, Katsuhisa Kudo
    Abstract:

    A spherical Neutron Counter for spectrometry and dosimetry has been developed. The Counter consists of a spherical polyethylene moderator and three slender 3He position-sensitive proportional Counters inserted into the moderator. The thermal Neutron distribution in the moderator, which is a function of the energy of the incident Neutrons is obtained with the proportional Counters. Characteristics of the Counter have been studied with experiments and Monte Carlo simulations. Also shown are energy spectra of a 252Cf Neutron source that are obtained by an unfolding method using the thermal Neutron distributions as response functions.

  • A multipurpose spherical Neutron Counter
    IEEE Transactions on Nuclear Science, 1995
    Co-Authors: H. Toyokawa, Akira Uritani, Chizuo Mori, N. Takeda, Katsuhisa Kudo
    Abstract:

    We have developed a unique Neutron Counter applicable to measurements of fluence, energy distribution and the dose equivalent of Neutrons with very wide energy range, and to estimations of incident direction of Neutron beams. This 4/spl pi/ sensitive Neutron Counter consists of a spherical polyethylene moderator and three charge-division-type position-sensitive proportional Counters (PSPCs) inserted into the moderator orthogonally with each other. The three PSPCs give thermal Neutron distributions in the spherical moderator that bring us the above information. The characteristics of this Neutron Counter have been studied with Monte Carlo simulations and with experiments using monoenergetic Neutrons. >

  • A multipurpose spherical Neutron Counter
    Proceedings of 1994 IEEE Nuclear Science Symposium - NSS'94, 1
    Co-Authors: H. Toyokawa, Akira Uritani, Chizuo Mori, N. Takeda, Katsuhisa Kudo
    Abstract:

    We have developed a unique Neutron Counter applicable to measurements of fluence, energy distribution and the dose equivalent of Neutrons with a very wide energy range, and to estimations of the incident direction of Neutron beams. This 4/spl pi/ sensitive Neutron Counter consists of a spherical polyethylene moderator and three charge-division-type position-sensitive proportional Counters (PSPCs) inserted into the moderator orthogonally with each other. The three PSPCs give thermal Neutron distributions in the spherical moderator that bring us the above information. The characteristics of this Neutron Counter have been studied with Monte Carlo simulations and with experiments using monoenergetic Neutrons. >

P.a. Russo - One of the best experts on this subject based on the ideXlab platform.

  • An approach to multiplicity counting for a versatile new sensor for plutonium assay with a very short die-away time, and independent measurements of Neutrons and gamma rays
    Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2003
    Co-Authors: Anthony P. Belian, N. Ensslin, D R Mayo, Michael C. Browne, William Clay, William H. Geist, Ha Nguyen, Kiril D. Ianakiev, Siler Panowski, P.a. Russo
    Abstract:

    Abstract A unique detector design incorporating a 6Li-based capture medium, ZnS scintillator, and wavelength shifting optical fibers is the basis of a new Neutron coincidence Counter for measurements of plutonium in highly impure residues. The sensor elements have a high efficiency for detecting Neutrons and exhibit excellent gamma-ray discrimination based on pulse-shape analysis. The short die-away time of the Counter that is based on these detector elements allows coincidence-gate settings shorter than 10 μs. This qualifies the technology for measurements of materials with high yields of uncorrelated Neutrons from 241Am(α,n) reactions. The characteristics of the new Neutron Counter will be illustrated with test data from measurements of plutonium, 252Cf, and gamma-ray sources. The integrated electronics design of the new detector also permits the simultaneous but independent measurement of both Neutrons and gamma rays. Recent test results that illustrate some unique applications of the sensor's versatility will also be presented.

  • An approach to multiplicity counting for a versatile new sensor for plutonium assay with a very short die-away time, and independent measurements of Neutrons and gamma rays
    2002
    Co-Authors: Anthony P. Belian, D R Mayo, Michael C. Browne, William H. Geist, Ha Nguyen, Kiril D. Ianakiev, Siler Panowski, W. A. Clay, P.a. Russo
    Abstract:

    A unique detector design incorporating a {sup 6}Li-based capture medium, ZnS scintillator, and wavelength shifting optical fibers is the basis of a new Neutron coincidence Counter for measurements of plutonium in highly-impure residues. The sensor elements have a high efficiency for detecting Neutrons and exhibit excellent gamma-ray discrimination based on pulse-shape analysis. The short die-away time of the Counter that is based on these detector elements allows coincidence-gate settings shorter than 10 microseconds. This qualifies the technology for measurements of materials with high yields of uncorrelated Neutrons from {sup 241}Am(alpha,n) reactions. The characteristics of the new Neutron Counter will be illustrated with test data from measurements of plutonium, {sup 252}Cf, and gamma-ray sources. The integrated electronics design of the new detector also permits the simultaneous but independent measurement of both Neutrons and gamma rays. Recent test results that illustrate some unique applications of the sensor's versatility will also be presented.

  • an evaluation of the invs model iv Neutron Counter
    1993
    Co-Authors: J.k. Sprinkle, M C Miller, Howard O Menlove, P.a. Russo
    Abstract:

    The inventory sample Counter (INVS) has been modified to allow simultaneous measurement of the plutonium isotopics during the Neutron assay. The Model IV design described in this report is suitable for in-line use with a glove-box sample-well and for off-line use with bag-out samples. The INVS Model IV can be used with a germanium detector in the bottom endplug for a simultaneous isotopics measurement or with the polyethylene and graphite endplug that was evaluated in the Model III. This report describes an evaluation with plutonium and mixed oxide samples with the polyethylene-and-graphite endplug. Half-percent uncertainties were obtained with some sample categories. A later report will describe the Neutron Counter evaluation with the germanium detector in the bottom endplug.

Yu. Penionzhkevich - One of the best experts on this subject based on the ideXlab platform.

  • Trial for the long Neutron Counter TETRA using $^{96,97}$Rb radioactive sources
    JINST, 2019
    Co-Authors: D. Testov, D. Verney, Yu. Penionzhkevich, F. Ibrahim, A. Boso, C. Delafosse, F. Didierjean, I. Deloncle, F. Le Blanc, C. Gaulard
    Abstract:

    The TETRA long Neutron Counter is operated at ALTO ISOL facility behind the PARRNe mass separator. TETRA has been proven to be a unique instrument for measurements of β-decay properties of short-lived Neutron-rich nuclei having applications for the nuclear structure and/or astrophysical r-process calculations. A proper calibration of TETRA can allow validation of the experimental procedure used for determination of β-delayed one-Neutron emission probabilities (P1n). It requires the use of a well-known β-Neutron decaying radioactive source which can be only produced and measured on-line due to its short half-life. Thus, the present paper reports on measurements of P1n and T1/2 of 96,97Rb nuclei using TETRA . The results obtained are in a good agreement with the values available in the literature. This proves that the developed techniques can be applied to unknown P1n and T1/2 of Neutron-rich species.

  • Calibration of Long Neutron Counter TETRA Using Reactions of Photo-Dissociation
    2018
    Co-Authors: D. Testov, D. Verney, V. Smirnov, M. Babo, Yu. Penionzhkevich, F. Ibrahim, E. Kuznetsova, S. Lukyanov, K. Mendibayev, Y. Sobolev
    Abstract:

    TETRA long Neutron Counter has proven to be an unique tool to identify and to measure delayed Neutron emission from photo-fission fragments produced at ALTO ISOL facility. TETRA uses robust technology based on 3He filled-Counters operating in the proportional mode. The cross-section of the reaction (n, 3He) is very larger for the thermal Neutron energy range. Thus, β-delayed Neutrons are moderated and can be detected with a high efficiency. However, due to the moderation process, information on the initial Neutron energy is typically lost. Energy of emitted Neutrons is needed for detailed description of the process of delayed (multi) Neutron emission from Neutron rich nuclei. In the present paper we discuss one of a method which can be used to recover information on the initial Neutron energy.

  • Pygmy Gamow-Teller resonance in the N=50 region: New evidence from staggering of β -delayed Neutron-emission probabilities
    Phys.Rev.C, 2017
    Co-Authors: D. Verney, D. Testov, V. Smirnov, Yu. Penionzhkevich, F. Ibrahim, F. Didierjean, B. Roussière, S. Franchoo, K. Flanagan, E. Kuznetsova
    Abstract:

    We report on the β-delayed Neutron emission probability (P1n) measurements of the Ga82,83,84 (N=51,52,53) precursors performed in one single experiment using the He3 Neutron-Counter TETRA at the ALTO facility in Orsay. Altogether our results for the three A=82,83, and 84 Ga precursors point towards a sizable P1n staggering in the N=50 region, similar to the one already observed just after the N=28 shell closure in the K isotopes chain, hinting at a similar mechanism. We will discuss the possible microscopic origin of this behavior, i.e., the existence in the light N=51 isotones of low-lying components of the so called pygmy Gamow-Teller resonance, already well established at Z=36, and persisting toward Ni79.

  • Pygmy Gamow-teller Resonance in the $N=50$ Region: new Evidence From Staggering of $\beta$-delayed Neutron-emission Probabilities Observed With Tetra
    2016
    Co-Authors: D. Verney, D. Testov, V. Smirnov, F. Ibrahim, B. Roussière, S. Franchoo, I. Matea, I. Stefan, D. Suzuki, Yu. Penionzhkevich
    Abstract:

    We report on the Pn measurements of the 82,83,84Ga (N = 51, 52, 53) precursors performed in one single experiment using the 3He Neutron-Counter TETRA at the ALTO facility in Orsay. Altogether our results for the three A = 82, 83 and 84 Ga isotopes point towards a sizable Pn staggering in the N = 50 region, similar to the one already known in the N = 28 region, hinting at a similar mechanism. We will discuss the possible microscopic origin of this behavior i.e. the existence in the N = 50 region of a low-lying component of the so called Pygmy Gamow-Teller Resonance, already well established at Z = 36, and persisting towards 78Ni.

H. Toyokawa - One of the best experts on this subject based on the ideXlab platform.

  • A spherical Neutron Counter with an extended energy response for dosimetry
    Radiation Protection Dosimetry, 1997
    Co-Authors: H. Toyokawa, Akira Uritani, Chizuo Mori, N. Takeda, Katsuhisa Kudo
    Abstract:

    Neutron Counter which is applicable to spectrometry and dosimetry over a wide energy range has been developed. It gives energy spectra, integral fluences and dose equivalent of incident Neutrons with energies from thermal to 15 MeV. The Counter consists of a spherical polyethylene moderator and three slender 3 He position-sensitive proportional Counters inserted into the moderator. The position-sensitive proportional Counters give detection position profiles of Neutrons, slowed down to thermal energies in the spherical moderator, which give the above mentioned information. The responses of the Counter as a function of the Neutron energy were calculated with Monte Carlo simulations. The feasibility of the Counter for applications to Neutron spectrometry and dosimetry was examined with an unfolding method. It is shown that the Counter is applicable to the spectrometry and dosimetry of Neutrons over a wide energy range.

  • Performance of a spherical Neutron Counter for spectroscopy and dosimetry
    IEEE Transactions on Nuclear Science, 1997
    Co-Authors: H. Toyokawa, Akira Uritani, Chizuo Mori, Michio Yoshizawa, N. Takeda, Katsuhisa Kudo
    Abstract:

    A spherical Neutron Counter for spectroscopy and dosimetry has been developed. The Counter consists of a spherical polyethylene moderator and three slender /sup 3/He position-sensitive proportional Counters. Rough measurements of Neutron fluence spectra and ambient dose equivalents, H*(10), have been done in the moderated-Neutron field of JAERI. Characteristics of the Counter are examined and compared with those of a Bonner sphere Neutron spectrometer.

  • Neutron spectrometer with position-sensitive proportional Counters
    Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 1996
    Co-Authors: H. Toyokawa, Akira Uritani, Chizuo Mori, Michio Yoshizawa, N. Takeda, Katsuhisa Kudo
    Abstract:

    A spherical Neutron Counter for spectrometry and dosimetry has been developed. The Counter consists of a spherical polyethylene moderator and three slender 3He position-sensitive proportional Counters inserted into the moderator. The thermal Neutron distribution in the moderator, which is a function of the energy of the incident Neutrons is obtained with the proportional Counters. Characteristics of the Counter have been studied with experiments and Monte Carlo simulations. Also shown are energy spectra of a 252Cf Neutron source that are obtained by an unfolding method using the thermal Neutron distributions as response functions.

  • A multipurpose spherical Neutron Counter
    IEEE Transactions on Nuclear Science, 1995
    Co-Authors: H. Toyokawa, Akira Uritani, Chizuo Mori, N. Takeda, Katsuhisa Kudo
    Abstract:

    We have developed a unique Neutron Counter applicable to measurements of fluence, energy distribution and the dose equivalent of Neutrons with very wide energy range, and to estimations of incident direction of Neutron beams. This 4/spl pi/ sensitive Neutron Counter consists of a spherical polyethylene moderator and three charge-division-type position-sensitive proportional Counters (PSPCs) inserted into the moderator orthogonally with each other. The three PSPCs give thermal Neutron distributions in the spherical moderator that bring us the above information. The characteristics of this Neutron Counter have been studied with Monte Carlo simulations and with experiments using monoenergetic Neutrons. >

  • A multipurpose spherical Neutron Counter
    Proceedings of 1994 IEEE Nuclear Science Symposium - NSS'94, 1
    Co-Authors: H. Toyokawa, Akira Uritani, Chizuo Mori, N. Takeda, Katsuhisa Kudo
    Abstract:

    We have developed a unique Neutron Counter applicable to measurements of fluence, energy distribution and the dose equivalent of Neutrons with a very wide energy range, and to estimations of the incident direction of Neutron beams. This 4/spl pi/ sensitive Neutron Counter consists of a spherical polyethylene moderator and three charge-division-type position-sensitive proportional Counters (PSPCs) inserted into the moderator orthogonally with each other. The three PSPCs give thermal Neutron distributions in the spherical moderator that bring us the above information. The characteristics of this Neutron Counter have been studied with Monte Carlo simulations and with experiments using monoenergetic Neutrons. >