WorldWideScience

Sample records for mixed field neutrons

  1. Neutron and photon spectrometry in mixed radiation fields

    International Nuclear Information System (INIS)

    Jancar, A.; Kopecky, Z.; Veskrna, M.

    2014-01-01

    Spectrometric measurements of the mixed fields of neutron and photon radiation in the workplaces with the L-R-0 research reactor located in the UJV Rez and with the Van de Graaff accelerator, located in the UTEF laboratories Prague, are presented in this paper. The experimental spectrometric measurements were performed using a newly developed digital measuring system, based on the technology of analog-digital converters with a very high sampling frequency (up to 2 GHz), in connection with organic scintillation detector, type BC-501A, and stilbene detector. The results of experimental measurements show high quality of spectrometry mixed fields of neutron and photon radiation across the wide dynamic range of measured energy. (authors)

  2. Response of six neutron survey meters in mixed fields of fast and thermal neutrons.

    Science.gov (United States)

    Kim, S I; Kim, B H; Chang, I; Lee, J I; Kim, J L; Pradhan, A S

    2013-10-01

    Calibration neutron fields have been developed at KAERI (Korea Atomic Energy Research Institute) to study the responses of commonly used neutron survey meters in the presence of fast neutrons of energy around 10 MeV. The neutron fields were produced by using neutrons from the (241)Am-Be sources held in a graphite pile and a DT neutron generator. The spectral details and the ambient dose equivalent rates of the calibration fields were established, and the responses of six neutron survey meters were evaluated. Four single-moderator-based survey meters exhibited an under-responses ranging from ∼9 to 55 %. DINEUTRUN, commonly used in fields around nuclear reactors, exhibited an over-response by a factor of three in the thermal neutron field and an under-response of ∼85 % in the mixed fields. REM-500 (tissue-equivalent proportional counter) exhibited a response close to 1.0 in the fast neutron fields and an under-response of ∼50 % in the thermal neutron field.

  3. EVIDOS: Individual dosimetry in mixed neutron and photon radiation fields

    International Nuclear Information System (INIS)

    Vanhavere, F.

    2006-01-01

    The EVIDOS project (partly funded by the European Commission RTD Programme: Nuclear Energy, Euratom Framework Programme V, 1998-2002, Contract No FIKR-CT-2001-00175) aimed at improving individual monitoring in mixed neutron-photon radiation fields by evaluating the performance of routine and novel personal dosimeters for mixed radiation, and by giving guidelines for deriving sufficiently accurate values of personal dose equivalent from the readings of area survey instruments and dosimeters. The main objective of EVIDOS was to evaluate different methods for individual dosimetry in mixed neutron-photon work-places in nuclear industry. This implied a determination of the capabilities and limitations of personal dosimeters and the establishment of methods to enable sufficiently accurate values of personal dose equivalent from spectrometers, area survey instruments and routine personal dosimeters. Also novel electronic personal dosimeters were investigated. To this end spectrometric and dosimetric investigations in selected representative workplaces in nuclear industry where workers can receive significant neutron doses were performed. As part of this project, a number of tasks were executed, in particular: (1) the determination of the energy and direction distribution of the neutron fluence; (2) the derivation of the (conventionally true) values of radiation protection quantities; (3) the determination of the readings of routine and innovative personal dosimeters and of area monitors; and (4) the comparison between dosimeter readings and values of the radiation protection quantities

  4. Biological dosimetry for mixed gamma-neutron field

    International Nuclear Information System (INIS)

    Brandao, J.O.C.; Santos, J.A.L.; Souza, P.L.G.; Lima, F.F.; Vilela, E.C.; Calixto, M.S.; Santos, N.

    2011-01-01

    There is increasing concern about airline crew members (about one million worldwide) exposed to measurable neutrons doses. Historically, cytogenetic biodosimetry assays have been based on quantifying asymmetrical chromosome alterations (dicentrics, centric rings and acentric fragments) in mitogen-stimulated T-lymphocytes in their first mitosis after radiation exposure. Increased levels of chromosome damage in peripheral blood lymphocytes are a sensitive indicator of radiation exposure and they are routinely exploited for assessing radiation absorbed dose after accidental or occupational exposure. Since radiological accidents are not common, not all nations feel that it is economically justified to maintain biodosimetry competence. However, dependable access to biological dosimetry capabilities is completely critical in event of an accident. In this paper the dose-response curve was measured for the induction of chromosomal alterations in peripheral blood lymphocytes after chronic exposure in vitro to mixed gamma-neutron field. Blood was obtained from one healthy donor and exposed to two mixed gamma-neutron field from sources 241 AmBe (20 Ci) at the Neutron Calibration Laboratory (NCL - CRCN/NE - PE - Brazil). The evaluated absorbed doses were 0.2 Gy; 1.0 Gy and 2.5 Gy. The dicentric chromosomes were observed at metaphase, following colcemide accumulation and 1000 well-spread metaphases were analyzed for the presence of dicentrics by two experts after painted by giemsa 5%. The preliminary results showed a linear dependence between radiations absorbed dose and dicentric chromosomes frequencies. Dose-response curve described in this paper will contribute to the construction of calibration curve that will be used in our laboratory for biological dosimetry. (author)

  5. Feasibility study on using imaging plates to estimate thermal neutron fluence in neutron-gamma mixed fields

    International Nuclear Information System (INIS)

    Fujibuchi, T.; Tanabe, Y.; Sakae, T.; Terunuma, T.; Isobe, T.; Kawamura, H.; Yasuoka, K.; Matsumoto, T.; Harano, H.; Nishiyama, J.; Masuda, A.; Nohtomi, A.

    2011-01-01

    In current radiotherapy, neutrons are produced in a photonuclear reaction when incident photon energy is higher than the threshold. In the present study, a method of discriminating the neutron component was investigated using an imaging plate (IP) in the neutron-gamma-ray mixed field. Two types of IP were used: a conventional IP for beta- and gamma rays, and an IP doped with Gd for detecting neutrons. IPs were irradiated in the mixed field, and the photo-stimulated luminescence (PSL) intensity of the thermal neutron component was discriminated using an expression proposed herein. The PSL intensity of the thermal neutron component was proportional to thermal neutron fluence. When additional irradiation of photons was added to constant neutron irradiation, the PSL intensity of the thermal neutron component was not affected. The uncertainty of PSL intensities was approximately 11.4 %. This method provides a simple and effective means of discriminating the neutron component in a mixed field. (authors)

  6. Study on the dose distribution of the mixed field with thermal and epi-thermal neutrons for neutron capture therapy

    International Nuclear Information System (INIS)

    Kobayashi, Tooru; Sakurai, Yoshinori; Kanda, Keiji

    1994-01-01

    Simulation calculations using DOT 3.5 were carried out in order to confirm the characteristics of depth-dependent dose distribution in water phantom dependent on incident neutron energy. The epithermal neutrons mixed to thermal neutron field is effective improving the thermal neutron depth-dose distribution for neutron capture therapy. A feasibility study on the neutron energy spectrum shifter was performed using ANISN-JR for the KUR Heavy Water Facility. The design of the neutron spectrum shifter is feasible, without reducing the performance as a thermal neutron irradiation field. (author)

  7. EPR dosimetry in a mixed neutron and gamma radiation field.

    Science.gov (United States)

    Trompier, F; Fattibene, P; Tikunov, D; Bartolotta, A; Carosi, A; Doca, M C

    2004-01-01

    Suitability of Electron Paramagnetic Resonance (EPR) spectroscopy for criticality dosimetry was evaluated for tooth enamel, mannose and alanine pellets during the 'international intercomparison of criticality dosimetry techniques' at the SILENE reactor held in Valduc in June 2002, France. These three materials were irradiated in neutron and gamma-ray fields of various relative intensities and spectral distributions in order to evaluate their neutron sensitivity. The neutron response was found to be around 10% for tooth enamel, 45% for mannose and between 40 and 90% for alanine pellets according their type. According to the IAEA recommendations on the early estimate of criticality accident absorbed dose, analyzed results show the EPR potentiality and complementarity with regular criticality techniques.

  8. Analysis of unstable chromosome alterations frequency induced by neutron-gamma mixed field radiation

    International Nuclear Information System (INIS)

    Souza, Priscilla L.G.; Brandao, Jose Odinilson de C.; Vale, Carlos H.F.P.; Santos, Joelan A.L.; Vilela, Eudice C.; Lima, Fabiana F.; Calixto, Merilane S.; Santos, Neide

    2009-01-01

    Nowadays monitoring chromosome alterations in peripheral blood lymphocytes have been used to access the radiation absorbed dose in individuals exposed accidental or occupationally to gamma radiation. However there are not many studies based on the effects of mixed field neutron-gamma. The radiobiology of neutrons has great importance because in nuclear factories worldwide there are several hundred thousand individuals monitored as potentially receiving doses of neutron. In this paper it was observed the frequencies of unstable chromosome alterations induced by a gamma-neutron mixed field. Blood was obtained from one healthy donor and exposed to mixed field neutron-gamma sources 241 AmBe (20 Ci) at the Neutron Calibration Laboratory (NCL-CRCN/NE-PE-Brazil). The chromosomes were observed at metaphase, following colcemid accumulation and 1000 well-spread metaphases were analyzed for the presence of chromosome alterations by two experienced scorers. The results suggest that there is the possibility of a directly proportional relationship between absorbed dose of neutron-gamma mixed field radiation and the frequency of unstable chromosome alterations analyzed in this paper. (author)

  9. Analysis of unstable chromosome alterations frequency induced by neutron-gamma mixed field radiation

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Priscilla L.G.; Brandao, Jose Odinilson de C.; Vale, Carlos H.F.P.; Santos, Joelan A.L.; Vilela, Eudice C.; Lima, Fabiana F. [Centro Regional de Ciencias Nucleares (CRCN-NE/CNEN-PE), Recife, PE (Brazil)], e-mail: psouza@cnen.gov.br, e-mail: jodinilson@cnen.gov.br; Calixto, Merilane S.; Santos, Neide [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Genetica

    2009-07-01

    Nowadays monitoring chromosome alterations in peripheral blood lymphocytes have been used to access the radiation absorbed dose in individuals exposed accidental or occupationally to gamma radiation. However there are not many studies based on the effects of mixed field neutron-gamma. The radiobiology of neutrons has great importance because in nuclear factories worldwide there are several hundred thousand individuals monitored as potentially receiving doses of neutron. In this paper it was observed the frequencies of unstable chromosome alterations induced by a gamma-neutron mixed field. Blood was obtained from one healthy donor and exposed to mixed field neutron-gamma sources {sup 241}AmBe (20 Ci) at the Neutron Calibration Laboratory (NCL-CRCN/NE-PE-Brazil). The chromosomes were observed at metaphase, following colcemid accumulation and 1000 well-spread metaphases were analyzed for the presence of chromosome alterations by two experienced scorers. The results suggest that there is the possibility of a directly proportional relationship between absorbed dose of neutron-gamma mixed field radiation and the frequency of unstable chromosome alterations analyzed in this paper. (author)

  10. Reproducibility of TL measurements in a mixed field of thermal neutrons and photons

    International Nuclear Information System (INIS)

    Fernandes, A.C.; Goncalves, I.C.; Ferro Carvalho, A.; Santos, J.; Cardoso, J.; Santos, L.; Osvay, M.

    2002-01-01

    The reproducibility of measurements performed with GR-100 (LiF:Mg,Ti) from the Solid Dosimetric Detector and Method Laboratory (DML) China, GR-107 ( 7 LiF:Mg,Ti, DML), TLD-700H ( 7 LiF:Mg,Cu,P, Harshaw) and Al 2 O 3 :Mg,Y (Hungary) in photon and mixed photon-neutron fields was investigated. Mixed-field irradiations were performed in a thermal neutron field generated at a nuclear reactor. GR-100 sensitivity decreased after mixed-field irradiations, while no significant change was found for the other materials. Using GR-100 for the dosimetry of mixed and high-intensity fields requires careful procedures. (author)

  11. Radiation hygiene aspects of mixed neutron-gamma field dosimetry

    International Nuclear Information System (INIS)

    Nikodemova, O.; Hrabovcova, A.

    1982-01-01

    Various possibilities are analyzed of determining the dose equivalent of neutrons, as is the reliability of the techniques and the correct interpretation for the purposes of radiation hygiene. (author)

  12. Simulation of the spherical experimental assemblies for the mixed neutron-gamma reference fields implementation

    International Nuclear Information System (INIS)

    Kluson, J.; Jansky, B.

    2009-01-01

    Reference mixed neutron-gamma fields are used for test and calibration of dosimetric and spectrometric systems, intercomparison measurements, and benchmark tests and represent experimental base for reactor studies. Set of the spherical experimental assemblies for the mixed neutron-gamma reference fields implementation was build in the NRI Rez. Extended sets of measurements and simulation calculations were done to describe the reference mixed field dosimetry and spectral characteristics with best achievable precision. The Monte Carlo technique was used for different experimental setups models description, comparison and verification and field characteristics simulation. Effects (hardly distinguishable experimentally) were also studied ( contributions from individual parts of experimental setup, field individual components and next effects as shadow shield cones transparency, etc.). Some results and main conclusions of these studies and calculations are presented and discussed. (authors)

  13. Simulation of the spherical experimental assemblies for the mixed neutron-gamma reference fields implementation

    International Nuclear Information System (INIS)

    Kluson, J.; Jansky, B.

    2008-01-01

    Reference mixed neutron-gamma fields are used for test and calibration of dosimetric and spectrometric systems, intercomparison measurements, and benchmark tests and represent experimental base for reactor studies. Set of the spherical experimental assemblies for the mixed neutron-gamma reference fields implementation was build in the NRI Rez. Extended sets of measurements and simulation calculations were done to describe the reference mixed field dosimetry and spectral characteristics with best achievable precision. The Monte Carlo technique was used for different experimental setups models description, comparison and verification and field characteristics simulation. Effects (hardly distinguishable experimentally) were also studied ( contributions from individual parts of experimental setup, field individual components and next effects as shadow shield cones transparency, etc.). Some results and main conclusions of these studies and calculations are presented and discussed. (authors)

  14. Dose Determination using alanine detectors in a Mixed Neutron and Gamma Field for Boron Neutron Capture Therapy of Liver Malignancies

    DEFF Research Database (Denmark)

    Schmitz, T.; Blaickner, M.; Ziegner, M.

    2011-01-01

    Introduction Boron Neutron Capture Therapy for liver malignancies is being investigated at the University of Mainz. One important aim is the set-up of a reliable dosimetry system. Alanine dosimeters have previously been applied for dosimetry of mixed radiation fields in antiproton therapy, and ma...

  15. Investigation of dose distribution in mixed neutron-gamma field of boron neutron capture therapy using N isopropylacrylamide gel

    Energy Technology Data Exchange (ETDEWEB)

    Bavarmegin, Elham; Sadremomtaz, Alireza [Nuclear Science and Technology Research Institute (NSTRI), Tehran (Iran, Islamic Republic of); Khalafi, Hossein; Kasesaz, Yaser [Dept. of Physics, University of Guilan, Rasht (Iran, Islamic Republic of); Khajeali, Azim [Medical Education Research Center, Tabriz (Iran, Islamic Republic of)

    2017-02-15

    Gel dosimeters have unique advantages in comparison with other dosimeters. Until now, these gels have been used in different radiotherapy techniques as a reliable dosimetric tool. Because dose distribution measurement is an important factor for appropriate treatment planning in different radiotherapy techniques, in this study, we evaluated the ability of the N-isopropylacrylamide (NIPAM) polymer gel to record the dose distribution resulting from the mixed neutron-gamma field of boron neutron capture therapy (BNCT). In this regard, a head phantom containing NIPAM gel was irradiated using the Tehran Research Reactor BNCT beam line, and then by a magnetic resonance scanner. Eventually, the R2 maps were obtained in different slices of the phantom by analyzing T2-weighted images. The results show that NIPAM gel has a suitable potential for recording three-dimensional dose distribution in mixed neutron-gamma field dosimetry.

  16. A coaxial double cylindrical TEPC for the microdosimetry of selected neutron energy bands in mixed fields of fast neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Saion, E.B.; Watt, D.E. (Saint Andrews Univ. (UK). Dept. of Physics); East, B.W. (Scottish Universities Research and Reactor Centre, Glasgow (UK)); Colautti, P. (Istituto Nazionale di Fisica Nucleare, Padua (Italy))

    1990-01-01

    A new low pressure tissue-equivalent proportional counter (TEPC) in a coaxial double cylindrical form has been developed to measure separately the microdose spectrum from any desired energy band of neutrons in the presence of mixed fields of faster neutrons, by selecting the thickness of the common TE dividing wall to be equivalent to the corresponding maximum proton ranges and by appropriate use of coincidence/anti-coincidence pulse arrangements. This thickness ensures charged particle equilibrium for the relevant neutron energy. Event spectra due to recoils generated by faster neutrons which interact with both the counters are removed completely by anti-coincidence techniques, thereby optimising the sensitivity of the inner microdosemeter to the event spectra of interest. The ability of this counter to discriminate in favour of events due to neutrons of energy <850 keV was achieved in microdosimetric measurements from mixed fields of a nuclear reactor. Mean values of lineal energy and quality factor for neutrons of energy <850 keV from a nuclear reactor were determined from the anti-coincidence spectrum. Good discrimination against {gamma} ray induced events is also achieved for the spectrum recorded in the anti-coincidence mode. This is an advantageous feature for other applications and requires further investigation. (author).

  17. A coaxial double cylindrical TEPC for the microdosimetry of selected neutron energy bands in mixed fields of fast neutrons

    International Nuclear Information System (INIS)

    Saion, E.B.; Watt, D.E.; Colautti, P.

    1990-01-01

    A new low pressure tissue-equivalent proportional counter (TEPC) in a coaxial double cylindrical form has been developed to measure separately the microdose spectrum from any desired energy band of neutrons in the presence of mixed fields of faster neutrons, by selecting the thickness of the common TE dividing wall to be equivalent to the corresponding maximum proton ranges and by appropriate use of coincidence/anti-coincidence pulse arrangements. This thickness ensures charged particle equilibrium for the relevant neutron energy. Event spectra due to recoils generated by faster neutrons which interact with both the counters are removed completely by anti-coincidence techniques, thereby optimising the sensitivity of the inner microdosemeter to the event spectra of interest. The ability of this counter to discriminate in favour of events due to neutrons of energy <850 keV was achieved in microdosimetric measurements from mixed fields of a nuclear reactor. Mean values of lineal energy and quality factor for neutrons of energy <850 keV from a nuclear reactor were determined from the anti-coincidence spectrum. Good discrimination against γ ray induced events is also achieved for the spectrum recorded in the anti-coincidence mode. This is an advantageous feature for other applications and requires further investigation. (author)

  18. Dosimetry of the Embalse nuclear power plant neutron/gamma mixed fields

    International Nuclear Information System (INIS)

    Salas, C.A.

    1990-01-01

    The aim of this work is to describe the method used at the Embalse nuclear power plant for carrying out personal dosimetry of the agents affected to the tasks on the Embalse nuclear power plant neutron-gamma mixed fields. (Author) [es

  19. Unilateral irradiation of pigs in a mixed neutrons+gamma field. Early results

    International Nuclear Information System (INIS)

    Lemaitre, Guy; Maas, Jean.

    1982-08-01

    Pigs (16-20kg) were irradiated with 60 Co gamma or in a mixed field (neutron + gamma from the pulsed reactor SILENE). Pigs were unilaterally exposed by the left side. Each experimental group was composed of twelve animals and one control. Within the dose range explored (reference dose is mid-line tissue dose): 4-9.8 Gy of gamma rays only; 4.6 - 5.7 Gy of neutrons and gamma rays, pigs presented the haematopioetic form of the acute radiation sickness. At 5 Gy mixed field was more harmful than gamma rays only. Therefore the numerical value of neutron RBE (lethality 50 p cent within 30 days) is more than one. Experiments will be carried out in order to determine RBE values more accurately. Bone marrow dose will also be determined [fr

  20. Optimization of electret ionization chambers for dosimetry in mixed neutron-gamma fields

    International Nuclear Information System (INIS)

    Doerschel, B.; Pretzsch, G.

    1984-01-01

    The properties of combination dosemeters consisting of two air-filled electret ionization chambers in mixed neutron-gamma fields have been investigated. The first chamber, polyethylene-walled, is sensitive to neutrons and gamma rays, the second, having walls of teflon, is sensitive to gamma rays only. The properties of the dosemeters are determined by the resulting errors and the measuring range. As both properties depend on the dimensions of the electret ionization chambers they have been taken into account in optimizing the dimensions. The results show that with the use of the dosemeters the effective dose equivalent in mixed neutron-gamma fields can be determined nearly independently of the spectra. The lower detection limit is less than 1 mSv and the maximum uncertainty of dose measurements about 12%. (author)

  1. Method for measuring and evaluation dose equivalent rate from fast neutrons in mixed gamma-neutron fields around particles accelerators

    International Nuclear Information System (INIS)

    Cruceru, I.; Sandu, M.; Cruceru, M.

    1994-01-01

    A method for measuring and evaluation of doses and dose equivalent rate in mixed gamma- neutron fields is discussed in this paper. The method is basedon a double detector system consist of an ionization chamber with components made from a plastic scintillator, coupled to on photomultiplier. Generally the radiation fields around accelerators are complex, often consisting of many different ionizing radiations extending over a broad range of energies. This method solve two major difficulties: determination of response functions of radiation detectors; interpretation of measurement and determination of accuracy. The discrimination gamma-fast neutrons is assured directly without a pulse shape discrimination circuit. The method is applied to mixed fields in which particle energies are situated in the energy range under 20 MeV and an izotropic emision (Φ=10 4 -10 11 n.s -1 ). The dose equivalent rates explored is 0.01mSV--0.1SV

  2. Determination of dose components in mixed gamma neutron fields by use of high pressure ionization chambers

    International Nuclear Information System (INIS)

    Golnik, N.; Pliszczynski, T.; Wysocka, A.; Zielczynski, M.

    1985-01-01

    The two ionization chamber method for determination of dose components in mixed γ-neutron field has been improved by increasing gas pressure in the chambers up to some milions pascals. Advantages of high pressure gas filling are the followings: 1) significant reduction of the ratio of neutron-to gamma sensitivity for the hydrogen-free chamber, 2) possibility of sensitivity correction for both chambers by application of appropriate voltage, 3) high sensitivity for small detectors. High-pressure, pen-like ionization chambers have been examined in fields of different neutron sources: a TE-chamber, filled with 0.2 MPa of quasi-TE-gas and a conductive PTFE chamber, filled with 3.1 MPa of CO 2 . The ratio of neutron-to-gamma sensitivity for the PTFE chamber, operated at electrical field strength below 100 V/cm, has not exceeded 0.01 for neutrons with energy below 8 MeV. Formula is presented for calculation of this ratio for any high-pressure, CO 2 -filled ionization chamber. Contribution of gamma component to total tissue dose in the field of typical neutron sources has been found to be 3 to 70%

  3. Performance of neutron and gamma personnel dosimetry in mixed radiation fields

    International Nuclear Information System (INIS)

    Swaja, R.E.; Sims, C.S.

    1981-01-01

    From 1974 to 1980, six personnel dosimetry intercomparison studies (PDIS) were conducted at the Oak Ridge National Laboratory (ORNL) to evaluate the performance of personnel dosimeters in a variety of neutron and gamma fields produced by operating the Health Physics Research Reactor (HPRR) in the steady state mode with and without spectral modifying shields. A total of 58 different organizations participated in these studies which produced approximately 2000 measurements of neutron and gamma dose equivalents on anthropomorphic phantoms for five different reactor spectra. Based on these data, the relative performance of three basic types of neutron dosimeters [nuclear emulsion film, thermoluminescent (TLD), and track-etch] and two basic types of gamma dosimeters (film and TLD) in mixed radiation fields was assessed

  4. Measurement of neutron and gamma absorbed doses in phantoms exposed to mixed fields

    International Nuclear Information System (INIS)

    Beraud-Sudreau, E.; Lemaire, G.; Maas, J.

    1985-01-01

    In order to study the dosimetric characteristics of PIN junctions, the absorbed doses measured by junctions and FLi7 in air and water phantoms were compared with the doses measured by classical neutron dosimetry in mixed fields. The validity of the experimental responses of PIN junctions being thus checked and established, neutron and gamma dose distributions in tissue equivalent plastic phantoms (plastinaut) and mammals (piglets) were evaluated as well as the absorbed dose distributions in the pig bone-marrow producing areas. By using correlatively a Monte-Carlo calculation method and applying some simplifying assumptions, the absorbed doses were derived from the spectrum of SILENE's neutrons at various depths inside a cubic water phantom and the results were compared with some from the literature [fr

  5. Intercomparison of personnel dosimetry for thermal neutron dose equivalent in neutron and gamma-ray mixed fields

    International Nuclear Information System (INIS)

    Ogawa, Yoshihiro

    1985-01-01

    In order to consider the problems concerned with personnel dosimetry using film badges and TLDs, an intercomparison of personnel dosimetry, especially dose equivalent responses of personnel dosimeters to thermal neutron, was carried out in five different neutron and gamma-ray mixed fields at KUR and UTR-KINKI from the practical point of view. For the estimation of thermal neutron dose equivalent, it may be concluded that each personnel dosimeter has good performances in the precision, that is, the standard deviations in the measured values by individual dosimeter were within 24 %, and the dose equivalent responses to thermal neutron were almost independent on cadmium ratio and gamma-ray contamination. However, the relative thermal neutron dose equivalent of individual dosimeter normalized to the ICRP recommended value varied considerably and a difference of about 4 times was observed among the dosimeters. From the results obtained, it is suggested that the standardization of calibration factors and procedures is required from the practical point of radiation protection and safety. (author)

  6. Workplace monitoring of mixed neutron-photon radiation fields and its contribution to external dosimetry

    International Nuclear Information System (INIS)

    Schuhmacher, H.

    2011-01-01

    Workplace monitoring is a common procedure for determining measures for routine radiation protection in a particular working environment. For mixed radiation fields consisting of neutrons and photons, it is of increased importance because it contributes to the improved accuracy of individual monitoring. An example is the determination of field-specific correction factors, which can be applied to the readings of personal dosemeters. This paper explains the general problems associated with individual dosimetry of neutron radiation, and describes the various options for workplace monitoring. These options cover a range from the elaborate field characterisation using transport calculations or spectrometers to the simpler approach using area monitors. Examples are given for workplaces in nuclear industry, at particle accelerators and at flight altitudes. (authors)

  7. The response of the BTI bubble detectors in mixed gamma-neutron workplace fields

    International Nuclear Information System (INIS)

    Vanhavere, F.; Coeck, M.; Lievens, B.; Reginatto, M.

    2005-01-01

    Full text: Bubble detectors have become a mature technology and are used as neutron dosemeters in a wide range of applications. At the SCK-CEN and Belgonucleaire they are used as official personal neutron dosemeter for the personnel. Two types are commercially available from Bubble Technology Industries: the BD-PND, which has a neutron energy threshold of around 100 keV, and the BDT, which is mainly sensitive to thermal neutrons. At Belgonucleaire only the BD-PND is worn, and the results are corrected with a site specific factor. At the SCK-CEN both the BD-PND and BDT are worn and a combination of both results is applied for the dose records. In the EC project EVIDOS (Evaluation of Individual Dosimetry in Mixed Neutron and Photon Radiation Fields), a whole range of neutron dosemeters were irradiated in workplace fields in nuclear installations in Europe, including both types of bubble detectors. The bubble detectors were exposed on a phantom with different angles towards the reference directions in the workplace fields. We will report the bubble detectors' results in the simulated workplace fields at Cadarache (CANEL and Sigma), in the workplaces at Kruemmel (boiling water reactor, transport cask), at Mol (Venus research reactor SCK-CEN, MOX-fuel facility Belgonucleaire) and Ringhals (pressurized water reactor, transport cask). The responses of the bubble detectors and the combination of both will be compared to the reference values determined with Bonner Spheres and a novel directional spectrometer. The dosemeter readings were checked for consistency by folding the dosemeter response functions with the corresponding workplace fluence spectra in the same workplace. (author)

  8. Development and testing of a thermoluminescent dosemeter for mixed neutron-photon-beta radiation fields

    International Nuclear Information System (INIS)

    Zummo, J.J.; Liu, J.C.

    1998-08-01

    A new four-element thermoluminescent (TL) dosemeter and dose evaluation algorithm have been developed and tested to better characterize personnel exposure in mixed neutron-photon-beta radiation fields. The prototype dosemeter is based on a commercially available TL card (with three LiF-7 chips and one LiF-6 chip) and modified filtration elements. The new algorithm takes advantage of the high temperature peak characteristics of the LiF-6 element to better quantify the neutron dose component. The dosemeter was tested in various radiation fields, consisting of mixtures of two radiation types typically used for dosemeter performance testing, as well as mixtures of three radiation types to simulate possible exposure conditions. The new dosemeter gave superior performance, based on the tolerance levels, when using the new algorithm as compared to a conventional algorithm that did not use the high temperature peak methodology. The limitations and further improvements are discussed

  9. Monte Carlo simulation of mixed neutron-gamma radiation fields and dosimetry devices

    International Nuclear Information System (INIS)

    Zhang, Guoqing

    2011-01-01

    Monte Carlo methods based on random sampling are widely used in different fields for the capability of solving problems with a large number of coupled degrees of freedom. In this work, Monte Carlos methods are successfully applied for the simulation of the mixed neutron-gamma field in an interim storage facility and neutron dosimeters of different types. Details are discussed in two parts: In the first part, the method of simulating an interim storage facility loaded with CASTORs is presented. The size of a CASTOR is rather large (several meters) and the CASTOR wall is very thick (tens of centimeters). Obtaining the results of dose rates outside a CASTOR with reasonable errors costs usually hours or even days. For the simulation of a large amount of CASTORs in an interim storage facility, it needs weeks or even months to finish a calculation. Variance reduction techniques were used to reduce the calculation time and to achieve reasonable relative errors. Source clones were applied to avoid unnecessary repeated calculations. In addition, the simulations were performed on a cluster system. With the calculation techniques discussed above, the efficiencies of calculations can be improved evidently. In the second part, the methods of simulating the response of neutron dosimeters are presented. An Alnor albedo dosimeter was modelled in MCNP, and it has been simulated in the facility to calculate the calibration factor to get the evaluated response to a Cf-252 source. The angular response of Makrofol detectors to fast neutrons has also been investigated. As a kind of SSNTD, Makrofol can detect fast neutrons by recording the neutron induced heavy charged recoils. To obtain the information of charged recoils, general-purpose Monte Carlo codes were used for transporting incident neutrons. The response of Makrofol to fast neutrons is dependent on several factors. Based on the parameters which affect the track revealing, the formation of visible tracks was determined. For

  10. Monte Carlo simulation of mixed neutron-gamma radiation fields and dosimetry devices

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Guoqing

    2011-12-22

    Monte Carlo methods based on random sampling are widely used in different fields for the capability of solving problems with a large number of coupled degrees of freedom. In this work, Monte Carlos methods are successfully applied for the simulation of the mixed neutron-gamma field in an interim storage facility and neutron dosimeters of different types. Details are discussed in two parts: In the first part, the method of simulating an interim storage facility loaded with CASTORs is presented. The size of a CASTOR is rather large (several meters) and the CASTOR wall is very thick (tens of centimeters). Obtaining the results of dose rates outside a CASTOR with reasonable errors costs usually hours or even days. For the simulation of a large amount of CASTORs in an interim storage facility, it needs weeks or even months to finish a calculation. Variance reduction techniques were used to reduce the calculation time and to achieve reasonable relative errors. Source clones were applied to avoid unnecessary repeated calculations. In addition, the simulations were performed on a cluster system. With the calculation techniques discussed above, the efficiencies of calculations can be improved evidently. In the second part, the methods of simulating the response of neutron dosimeters are presented. An Alnor albedo dosimeter was modelled in MCNP, and it has been simulated in the facility to calculate the calibration factor to get the evaluated response to a Cf-252 source. The angular response of Makrofol detectors to fast neutrons has also been investigated. As a kind of SSNTD, Makrofol can detect fast neutrons by recording the neutron induced heavy charged recoils. To obtain the information of charged recoils, general-purpose Monte Carlo codes were used for transporting incident neutrons. The response of Makrofol to fast neutrons is dependent on several factors. Based on the parameters which affect the track revealing, the formation of visible tracks was determined. For

  11. Differences in TLD 600 and TLD 700 glow curves derived from distict mixed gamma/neutron field irradiations

    International Nuclear Information System (INIS)

    Cavalieri, Tassio A.; Castro, Vinicius A.; Siqueira, Paulo T.D.

    2013-01-01

    In Neutron Capture Therapy, a thermal neutron beam shall impinge on a specific nuclide, such as 10 B, to promote a nuclear reaction which releases the useful therapeutic energy. A nuclear reactor is usually used as the neutron source, and therefore field contaminants such as gamma and high energy neutrons are also present in the field. However, mixed field dosimetry still stands as a challenge in some cases, due to the difficulty to experimentally discriminate the dose from each field component. For the mixed field dosimetry, the International Commission on Radiation end Units (ICRU) recommends the use of detector pairs with different responses for each beam component. The TLD 600/700 pair meets this need, because these LiF detectors have different Li isotopes concentration, with distinct thermal neutron responses because 6 Li presents a much higher neutron capture cross section than does 7 Li for low energy neutrons. TLD 600 is 6 Li enriched while TLD 700 is 7 Li enriched. However, depending on the neutron spectrum presented in the mixed field, TLD 700 response to thermal neutrons cannot be disregarded. This work aims to study the difference in TLD 600 and TLD 700 glow curves when these TLDs are submitted to mixed fields of different energy spectra and components balance. The TLDs were irradiated in a pure gamma source, and in mixed fields from an AmBe sealed source and from the IPEN/MB-01 reactor. These TLDs were read and had their two main dosimetric regions analyzed to observe the differences in the glow curves of these TLDs in each irradiation. Field components discrimination was achieved through Monte Carlo simulations run with MCNP radiation transport code. (author)

  12. Personal dosimetry in a mixed field of high energy muons and neutrons

    International Nuclear Information System (INIS)

    Cossairt, J.D.; Elwyn, A.J.

    1986-11-01

    High energy accelerators quite often emit muons. These particles behave in matter as would heavy electrons and are thus difficult to attenuate with shielding in many situations. Hence, these muons can be a source of radiation exposure to personnel and suitable methods of measuring the absorbed dose received to these people is obviously required. In practical situations, such muon radiation fields are often mixed with neutrons, well-known to be an even more troublesome particle species with respect to dosimetry. In this paper, we report on fluence measurements made in such a mixed radiation field and a comparison of dosimeter responses. We conclude that commercial self-reading dosimeters and film badges provided an adequate measure of the absorbed dose due to muons

  13. Evidos: optimisation of individual monitoring in mixed neutron/photon fields at workplaces of the nuclear fuel cycle

    International Nuclear Information System (INIS)

    Luszik-Bhadra, M.; Reginatto, M.; Schuhmacher, H.; Lacoste, V.; Muller, M.; Boschung, M.; Fiechtner, A.; Coeck, M.; Vanhavere, F.; Curzio, G.; D'errico, F.; Kyllonen, J.E.; Lindborg, L.; Molinos, C.; Tanner, R.; Derdau, D.; Lahaye, Th.

    2005-01-01

    Within its 5. Framework Programme, the EC is funding the project EVIDOS ('Evaluation of Individual Dosimetry in Mixed Neutron and Photon Radiation Fields'). The aim of this project is the optimisation of individual monitoring at workplaces of the nuclear fuel cycle with special regard to neutrons. Various dosemeters for mixed field application - passive and new electronic devices - are tested in selected workplace fields in nuclear installations in Europe. The fields are characterised using a series of spectrometers that provide the energy distribution of neutron fluence (Bonner spheres) and newly developed devices that provide the energy and directional distribution of the neutron fluence. Results from the first measurement campaign, carried out in simulated workplace fields (IRSN, Cadarache. France), and those of a second measurement campaign, carried out at workplaces at a boiling water reactor and at a storage cask with used fuel elements (Kernkraftwerk Kriimmel, Germany), are described. (authors)

  14. Simulated workplace neutron fields

    International Nuclear Information System (INIS)

    Lacoste, V.; Taylor, G.; Rottger, S.

    2011-01-01

    The use of simulated workplace neutron fields, which aim at replicating radiation fields at practical workplaces, is an alternative solution for the calibration of neutron dosemeters. They offer more appropriate calibration coefficients when the mean fluence-to-dose equivalent conversion coefficients of the simulated and practical fields are comparable. Intensive Monte Carlo modelling work has become quite indispensable for the design and/or the characterization of the produced mixed neutron/photon fields, and the use of Bonner sphere systems and proton recoil spectrometers is also mandatory for a reliable experimental determination of the neutron fluence energy distribution over the whole energy range. The establishment of a calibration capability with a simulated workplace neutron field is not an easy task; to date only few facilities are available as standard calibration fields. (authors)

  15. Portable instrument for measuring neutron energy spectra and neutron dose in a mixed n-γ field

    International Nuclear Information System (INIS)

    Daniels, C. J.; Silberberg, J. L.

    1980-01-01

    A portable high-speed neutron spectrometer consists of an organic scintillator, a true zero-crossing pulse shape discriminator, a 1 MHZ conversion-rate multichannel analyzer, an 8-bit microcomputer, and appropriate displays. The device can be used to measure neutron energy spectra and kerma rate in intense n- gamma radiation fields in which the neutron energy is from 5 to 15 MEV

  16. Neutron and photon spectrometry with liquid scintillation detectors in mixed fields

    CERN Document Server

    Klein, H

    2002-01-01

    Liquid scintillation detectors of type NE213 or BC501A are well suited and routinely used for spectrometry in mixed n-gamma-fields. Neutron- and photon-induced pulse height spectra may be simultaneously recorded making use of the n/gamma-discrimination capability based on pulse shape analysis. The light output functions for the detected secondary charged particles, i.e. electrons, positrons, protons and other charged reaction products, and the pulse height resolution function must carefully be determined. This can be done experimentally, in part via an iterative procedure by comparison with calculations. The response functions can then be reliably calculated by Monte Carlo simulations. Photon response functions calculated with the PHRESP code, which was developed on the basis of the EGS4+PRESTA program package, are in very good agreement with calibrations up to 17 MeV, both in shape and absolute scale. Similarly, neutron response functions calculated with the NRESP7 code well describe the pulse height spectra...

  17. Campbell's MSV method the neutron-gamma discrimination in mixed field of nuclear reactor

    International Nuclear Information System (INIS)

    Stankovic, S. J.; Loncar, B.; Avramovic, I.; Osmokrovic, P.

    2003-10-01

    In this paper it is carried out the analysis some capabilities of Campbell's MSV (Mean Square Value) measuring chain on base the principles derived by Campbell's theorem. Nevertheless, measurements have performed with digitized MSV method and results have compared related to they attained with classic measuring chain, when the mean value of signal from detector output has measured. In our case, detector element was uncompensated ionization chamber for mixed n-gamma fields. Thermal neutron flux, absorbed dose rate, equivalent dose rate and exposure rate in surrounding the reactor vessel of system HERBE, at nuclear reactor RB in 'VINCA' Institute, are determined. The examination of discrimination for gamma relate to neutron component in signal of detector output is performed whereby experimental work and the calculation according to linear theoretical model. The dependencies of changes for variance and mean value output detector signal versus four-decade change of fission reactor power, in range from 10 mW to 22W, are obtained. The advantage of MSV method is confirmed and concluded that the order n-gamma discrimination in MSV signal processing is around fifty times larger than classical measuring method. (author)

  18. 6LiF sandwich type detectors for low dose individual monitoring in mixed neutron-photon fields

    International Nuclear Information System (INIS)

    Olko, P.; Budzanowski, M.; Bilski, P.; Burgkhardt, B.; Piesch, E.

    1994-01-01

    ICRP Publication 60 recommends the reduction of the annual dose limit for occupational exposure from 50 to 20 mSv and a doubling of the quality factor for medium energy neutrons. If occupational doses are evaluated every month (which is obligatory e.g. in Germany and in Poland), the individual neutron dosemeter will have to measure neutron doses in the range of 100 μSv. No commercially available, automatic individual dosimetry monitoring system exists that fulfils this requirement. Some of the parameters which influence the evaluation of the neutron dose from readings of TL dosemeters have been studied in order to decrease the variance of the measured neutron signal. In mixed neutron-photon fields, clear separation of the neutron component from the total reading depends also on the uncertainty of the gamma dose measurements. While the thermal albedo neutrons are absorbed mostly at the surface of the 6 LiF detector, the reduction of the detector thickness results in a decrease of its photon sensitivity, while its neutron sensitivity is almost principally maintained. As a consequence, the uncertainty of gamma dose contributes with lower weight to the variance of the evaluated neutron signal. First tests of an optimised 200 μm thick sandwich detector and 0.9 mm thick standard LiF chips were made at low neutron and photon dose ranges using different readers, in order to determine the uncertainty versus dose for different neutron-photon combinations. The conditions under which the new sandwich type detectors may improve albedo neutron dosimetry are demonstrated. (Author)

  19. SPECTRUM WEIGHTED RESPONSES OF SEVERAL DETECTORS IN MIXED FIELDS OF FAST AND THERMAL NEUTRONS

    Directory of Open Access Journals (Sweden)

    SANG IN KIM

    2014-04-01

    Full Text Available The spectrum weighted responses of various detectors were calculated to provide guidance on the proper selection and use of survey instruments on the basis of their energy response characteristics on the neutron fields. To yield the spectrum weighted response, the detector response functions of 17 neutron-measuring devices were numerically folded with each of the produced calibration neutron spectra through the in-house developed software ‘K-SWR’. The detectors’ response functions were taken from the IAEA Technical Reports Series No. 403 (TRS-403. The reference neutron fields of 21 kinds with 2 spectra groups with different proportions of thermal and fast neutrons have been produced using neutrons from the 241Am-Be sources held in a graphite pile, a bare 241Am-Be source, and a DT neutron generator. Fluence-average energy (Eave varied from 3.8 MeV to 16.9 MeV, and the ambient-dose-equivalent rate [H*(10/h] varied from 0.99 to 16.5 mSv/h.

  20. Neutron spectrometry in mixed fields: characterisation of the Ra-1- reactor workplace

    International Nuclear Information System (INIS)

    Gregori, B.; Carelli, J.; Cruzate, J.; Papadopulos, S.

    2006-01-01

    The characterisation of the neutron spectrum of a workplace is an essential dosimetric tool for improving the assessment of the personal equivalent dose of the workers. In addition, if the operational conditions of the facility are well defined, the set of field spectra obtained may be used as a reference for comparing the performance of different type of neutron detectors. Recently, using a neutron spectrometric system based on a set of moderated spheres with 3 He detector, the characterisation of the neutron spectra in workplaces of the Argentine Reactor No. 1 (R.A. -1) has been carried out. The spectrometric system consists of 12 spheres made of the high density polyethylene d mean δ =0.95 g cm 3 , with diameters between 3'' and 12'' and a proportional counter of 3 He, 4 atm of nominal pressure, Centronic trade mark, located in the centre of the spheres. The neutron response matrix was calculated using the M.C.N.P. -I.V.B. code and E.N.D.F./B-VI library in the energy range between thermal neutron and 100 MeV. The neutron spectrum was unfolded using the M.A.X.E.D. unfolding code. The validation of the spectrometric system was performed at Cea-Cadarache (France) with of 252 Cf, Am Be, and 252 Cf + D 2 O sources. Therefore, in this work, the spectral fluence of the field in the selected points of the facility (R.A.-1) has been presented and the ambient dose equivalent, H *(10), and the personal dose equivalent, Hp(10), have been derived from the neutron fluence, applying ICRP-74 recommended fluence to dose conversion factors. The quantities evaluated have uncertainties less than 15%, which is considered good enough for radiation protection requirements. (authors)

  1. Preliminary study about frequencies of unstable chromosome alterations induced by gamma beam and neutron-gamma mixed field

    International Nuclear Information System (INIS)

    Mendes, Mariana E.; Souza, Priscilla L.G.; Brandao, Jose Odinilson de C.; Santos, Joelan A.L.; Vilela, Eudice C.; Lima, Fabiana F.; Calixto, Merilane S.; Santos, Neide

    2011-01-01

    The estimate on approximate dose in exposed individual can be made through conventional cytogenetic analysis of dicentric, this technique has been used to support physical dosimetry. It is important to estimate the absorbed dose in case of accidents with the aim of developing an appropriate treatment and biological dosimetry can be very useful in case where the dosimetry is unavailable. Exposure to gamma and neutron radiation leads to the same biological effects such as chromosomal alterations and cancer. However, neutrons cause more genetic damage, such as mutation or more structural damage, such as chromosome alterations. The aim of research is to compare frequencies of unstable chromosome alterations induced by a gamma beam with those from neutron-gamma mixed field. Two blood samples were obtained from one healthy donor and irradiated at different sources. The first sample was exposed to mixed field neutron-gamma sources 241 AmBe at the Neutron Calibration Laboratory (NCL - CRCN/NE - PE - Brazil) and the second one was exposed to 137 Cs gamma rays at 137 Cs Laboratory (CRCN/NE - PE - Brazil), both exposures resulting in an absorbed dose of 0.66Gy. Mitotic metaphase cells were obtained by lymphocyte culture for chromosomal analysis and slides were stained with Giemsa 5%. These preliminary results showed a similarity in associated dicentrics frequency per cell (0.041 and 0.048) after 137 Cs and 241 AmBe sources irradiations, respectively. However, it was not observed centric rings frequency per cell (0.0 and 0.027). This study will be continue to verify the frequencies of unstable chromosome alterations induced by only gamma beam and neutron-gamma mixed field. (author)

  2. Preliminary study about frequencies of unstable chromosome alterations induced by gamma beam and neutron-gamma mixed field

    Energy Technology Data Exchange (ETDEWEB)

    Mendes, Mariana E.; Souza, Priscilla L.G.; Brandao, Jose Odinilson de C.; Santos, Joelan A.L.; Vilela, Eudice C.; Lima, Fabiana F. [Centro Regional de Ciencias Nucleares (CRCN-NE/CNEN-PE), Recife, PE (Brazil); Calixto, Merilane S.; Santos, Neide [Universidade Federal de Pernanmbuco (CCB/UFPE), Recife, PE (Brazil). Centro de Ciencias Biologicas. Dept. de Genetica

    2011-07-01

    The estimate on approximate dose in exposed individual can be made through conventional cytogenetic analysis of dicentric, this technique has been used to support physical dosimetry. It is important to estimate the absorbed dose in case of accidents with the aim of developing an appropriate treatment and biological dosimetry can be very useful in case where the dosimetry is unavailable. Exposure to gamma and neutron radiation leads to the same biological effects such as chromosomal alterations and cancer. However, neutrons cause more genetic damage, such as mutation or more structural damage, such as chromosome alterations. The aim of research is to compare frequencies of unstable chromosome alterations induced by a gamma beam with those from neutron-gamma mixed field. Two blood samples were obtained from one healthy donor and irradiated at different sources. The first sample was exposed to mixed field neutron-gamma sources {sup 241}AmBe at the Neutron Calibration Laboratory (NCL - CRCN/NE - PE - Brazil) and the second one was exposed to {sup 137}Cs gamma rays at {sup 137}Cs Laboratory (CRCN/NE - PE - Brazil), both exposures resulting in an absorbed dose of 0.66Gy. Mitotic metaphase cells were obtained by lymphocyte culture for chromosomal analysis and slides were stained with Giemsa 5%. These preliminary results showed a similarity in associated dicentrics frequency per cell (0.041 and 0.048) after {sup 137}Cs and {sup 241}AmBe sources irradiations, respectively. However, it was not observed centric rings frequency per cell (0.0 and 0.027). This study will be continue to verify the frequencies of unstable chromosome alterations induced by only gamma beam and neutron-gamma mixed field. (author)

  3. Quinolone and glycopeptide therapy for infection in mouse following exposure to mixed-field neutron-γ-photon radiation

    International Nuclear Information System (INIS)

    Brook, I.; Tom, S.P.; Ledney, G.D.

    1993-01-01

    The effects of increased doses of mixed-field neutron-γ-photon irradiation on bacterial translocation and subsequent sepsis, and the influence of antimicrobial therapy on these events, were studied in the C3H/HeN mouse. The results demonstrate a relationship between the doses of mixed-field radiation and the rates of infection due to Enterobacteriaceae. While L-ofloxacin therapy reduces the infection rate, prolongs survival and prevents mortality, the addition of a glycopeptide can enhance systemic infection by resistant bacteria in the irradiated host. (author)

  4. Quinolone and glycopeptide therapy for infection in mouse following exposure to mixed-field neutron-[gamma]-photon radiation

    Energy Technology Data Exchange (ETDEWEB)

    Brook, I. (Naval Medical Research Inst., Bethesda, MD (United States) Armed Forces Radiobiology Research Inst., Bethesda, MD (United States)); Tom, S.P.; Ledney, G.D. (Armed Forces Radiobiology Research Inst., Bethesda, MD (United States))

    1993-12-01

    The effects of increased doses of mixed-field neutron-[gamma]-photon irradiation on bacterial translocation and subsequent sepsis, and the influence of antimicrobial therapy on these events, were studied in the C3H/HeN mouse. The results demonstrate a relationship between the doses of mixed-field radiation and the rates of infection due to Enterobacteriaceae. While L-ofloxacin therapy reduces the infection rate, prolongs survival and prevents mortality, the addition of a glycopeptide can enhance systemic infection by resistant bacteria in the irradiated host. (author).

  5. Distributions of neutron and gamma doses in phantom under a mixed field

    International Nuclear Information System (INIS)

    Beraud-Sudreau, E.

    1982-06-01

    A calculation program, based on Monte Carlo method, allowed to estimate the absorbed doses relatives to the reactor primary radiation, in a water cubic phantom and in cylindrical phantoms modelized from tissue compositions. This calculation is a theoretical approach of gamma and neutron dose gradient study in an animal phantom. PIN junction dosimetric characteristics have been studied experimentally. Air and water phantom radiation doses measured by PIN junction and lithium 7 fluoride, in reactor field have been compared to doses given by dosimetry classical techniques as tissue equivalent plastic and aluminium ionization chambers. Dosimeter responses have been employed to evaluate neutron and gamma doses in plastinaut (tissue equivalent plastic) and animal (piglet). Dose repartition in the piglet bone medulla has been also determined. This work has been completed by comparisons with Doerschell, Dousset and Brown results and by neutron dose calculations; the dose distribution related to lineic energy transfer in Auxier phantom has been also calculated [fr

  6. Characterisation of mixed neutron-photon workplace fields at nuclear facilities by spectrometry (energy and direction) within the EVIDOS project

    International Nuclear Information System (INIS)

    Luszik-Bhadra, M.; Bartlett, D.; Bolognese-Milsztajn, T.; Boschung, M.; Coeck, M.; Curzio, G.; D'Errico, F.; Fiechtner, A.; Lacoste, V.; Lindborg, L.; Reginatto, M.; Schuhmacher, H.; Tanner, R.; Vanhavere, F.

    2007-01-01

    Within the EC project EVIDOS, 17 different mixed neutron-photon workplace fields at nuclear facilities (boiling water reactor, pressurised water reactor, research reactor, fuel processing, storage of spent fuel) were characterised using conventional Bonner sphere spectrometry and newly developed direction spectrometers. The results of the analysis, using Bayesian parameter estimation methods and different unfolding codes, some of them especially adapted to simultaneously unfold energy and direction distributions of the neutron fluence, showed that neutron spectra differed strongly at the different places, both in energy and direction distribution. The implication of the results for the determination of reference values for radiation protection quantities (ambient dose equivalent, personal dose equivalent and effective dose) and the related uncertainties are discussed. (authors)

  7. Dosimetry of an accident in mixed field (neutrons, photons) using the spectrometry by electronic paramagnetic resonance(EPR)

    International Nuclear Information System (INIS)

    Herve, M.L.

    2006-03-01

    In a radiological accident, the assessment of the dose received by the victim is relevant information for the therapeutic strategy. Two complementary dosimetric techniques based on physical means are used in routine practice in the laboratory: EPR spectroscopy performed on materials removed from the victim or gathered from the vicinity of the victim and Monte Carlo calculations. EPR dosimetry, has been used successfully several times in cases of photon or electron overexposures. Accidental exposure may also occur with a neutron component. The aim of this work is to investigate the potentiality of EPR dosimetry for mixed photon and neutron field exposure with different organic materials (ascorbic acid, sorbitol, glucose, galactose, fructose, mannose, lactose and sucrose). The influence of irradiation parameters (dose, dose rate, photon energy) and of environmental parameters (temperature of heating, light exposure) on the EPR signal amplitude was studied. To assess the neutron sensitivity, the materials were exposed to a mixed radiation field of experimental reactors with different neutron to photon ratios. The relative neutron sensitivity was found to range from 10% to 43% according to the materials. Prior knowledge of the ratio between the dose in samples measured by EPR spectrometry and organ or whole body dose obtained by calculations previously performed for these different configurations, makes it possible to give a first estimation of the dose received by the victim in a short delay. The second aim of this work is to provide data relevant for a quick assessment of the dose distribution in case of accidental overexposure based on EPR measurements performed on one or several points of the body. The study consists in determining by calculation the relation between the dose to the organs and whole body and the dose to specific points of the body, like teeth, bones or samples located in the pockets of victim clothes, for different external exposures corresponding

  8. Radiation resistance of elastomeric O-rings in mixed neutron and gamma fields: Testing methodology and experimental results

    Science.gov (United States)

    Zenoni, A.; Bignotti, F.; Donzella, A.; Donzella, G.; Ferrari, M.; Pandini, S.; Andrighetto, A.; Ballan, M.; Corradetti, S.; Manzolaro, M.; Monetti, A.; Rossignoli, M.; Scarpa, D.; Alloni, D.; Prata, M.; Salvini, A.; Zelaschi, F.

    2017-11-01

    Materials and components employed in the presence of intense neutron and gamma fields are expected to absorb high dose levels that may induce deep modifications of their physical and mechanical properties, possibly causing loss of their function. A protocol for irradiating elastomeric materials in reactor mixed neutron and gamma fields and for testing the evolution of their main mechanical and physical properties with absorbed dose has been developed. Four elastomeric compounds used for vacuum O-rings, one fluoroelastomer polymer (FPM) based and three ethylene propylene diene monomer rubber (EPDM) based, presently available on the market have been selected for the test. One EPDM is rated as radiation resistant in gamma fields, while the other elastomers are general purpose products. Particular care has been devoted to dosimetry calculations, since absorbed dose in neutron fields, unlike pure gamma fields, is strongly dependent on the material composition and, in particular, on the hydrogen content. The products have been tested up to about 2 MGy absorbed dose. The FPM based elastomer, in spite of its lower dose absorption in fast neutron fields, features the largest variations of properties, with a dramatic increase in stiffness and brittleness. Out of the three EPDM based compounds, one shows large and rapid changes in the main mechanical properties, whereas the other two feature more stable behaviors. The performance of the EPDM rated as radiation resistant in pure gamma fields does not appear significantly better than that of the standard product. The predictive capability of the accelerated irradiation tests performed as well as the applicable concepts of threshold of radiation damage is discussed in view of the use of the examined products in the selective production of exotic species facility, now under construction at the Legnaro National Laboratories of the Italian Istituto Nazionale di Fisica Nucleare. It results that a careful account of dose rate effects

  9. Responses of conventional and extended-range neutron detectors in mixed radiation fields around a 150-MeV electron LINAC

    International Nuclear Information System (INIS)

    Lin, Yu-Chi; Sheu, Rong-Jiun; Chen, Ang-Yu

    2015-01-01

    This study analyzed the responses of two types of neutron detector in mixed gamma-ray and neutron radiation fields around a 150-MeV electron linear accelerator (LINAC). The detectors were self-assembled, high efficiency, and designed in two configurations: (1) a conventional moderated-type neutron detector based on a large cylindrical He-3 proportional counter; and (2) an extended-range version with an embedded layer of lead in the moderator to increase the detector’s sensitivity to high-energy neutrons. Two sets of the detectors were used to measure neutrons at the downstream and lateral locations simultaneously, where the radiation fields differed considerably in intensities and spectra of gamma rays and neutrons. Analyzing the detector responses through a comparison between calculations and measurements indicated that not only neutrons but also high-energy gamma rays (>5 MeV) triggered the detectors because of photoneutrons produced in the detector materials. In the lateral direction, the contribution of photoneutrons to both detectors was negligible. Downstream of the LINAC, where high-energy photons were abundant, photoneutrons contributed approximately 6% of the response of the conventional neutron detector; however, almost 50% of the registered counts of the extended-range neutron detector were from photoneutrons because of the presence of the detector rather than the effect of the neutron field. Dose readings delivered by extended-range neutron detectors should be interpreted cautiously when used in radiation fields containing a mixture of neutrons and high-energy gamma rays

  10. Dose-response curve for blood exposed to gamma-neutron mixed field by conventional cytogenetic method

    International Nuclear Information System (INIS)

    Brandao, Jose Odinilson de C.; Souza, Priscilla L.G.; Santos, Joelan A.L.; Vilela, Eudice C.; Lima, Fabiana F.; Calixto, Merilane S.; Santos, Neide

    2009-01-01

    There is increasing concern about airline crew members (about one million worldwide) are exposed to measurable neutrons doses. Historically, cytogenetic biodosimetry assays have been based on quantifying asymmetrical chromosome alterations (dicentrics, centric rings and acentric fragments) in mytogen-stimulated T-lymphocytes in their first mitosis after radiation exposure. Increased levels of chromosome damage in peripheral blood lymphocytes are a sensitive indicator of radiation exposure and they are routinely exploited for assessing radiation absorbed dose after accidental or occupational exposure. Since radiological accidents are not common, not all nations feel that it is economically justified to maintain biodosimetry competence. However, dependable access to biological dosimetry capabilities is completely critical in event of an accident. In this paper the dose-response curve was measured for the induction of chromosomal alterations in peripheral blood lymphocytes after chronic exposure in vitro to neutron-gamma mixes field. Blood was obtained from one healthy donor and exposed to two neutron-gamma mixed field from sources 241 AmBe (20 Ci) at the Neutron Calibration Laboratory (NCL-CRCN/NE-PE-Brazil). The evaluated absorbed doses were 0.2 Gy; 1.0 Gy and 2.5 Gy. The dicentric chromosomes were observed at metaphase, following colcemid accumulation and 1000 well-spread metaphase figures were analyzed for the presence of dicentrics by two experienced scorers after painted by giemsa 5%. Our preliminary results showed a linear dependence between radiations absorbed dose and dicentric chromosomes frequencies. Dose-response curve described in this paper will contribute to the construction of calibration curve that will be used in our laboratory for biological dosimetry. (author)

  11. Dose-response curve for blood exposed to gamma-neutron mixed field by conventional cytogenetic method

    Energy Technology Data Exchange (ETDEWEB)

    Brandao, Jose Odinilson de C.; Souza, Priscilla L.G.; Santos, Joelan A.L.; Vilela, Eudice C.; Lima, Fabiana F., E-mail: jodinilson@cnen.gov.b, E-mail: fflima@cnen.gov.b, E-mail: jasantos@cnen.gov.b [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil); Calixto, Merilane S.; Santos, Neide, E-mail: santos_neide@yahoo.com.b [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Genetica

    2009-07-01

    There is increasing concern about airline crew members (about one million worldwide) are exposed to measurable neutrons doses. Historically, cytogenetic biodosimetry assays have been based on quantifying asymmetrical chromosome alterations (dicentrics, centric rings and acentric fragments) in mytogen-stimulated T-lymphocytes in their first mitosis after radiation exposure. Increased levels of chromosome damage in peripheral blood lymphocytes are a sensitive indicator of radiation exposure and they are routinely exploited for assessing radiation absorbed dose after accidental or occupational exposure. Since radiological accidents are not common, not all nations feel that it is economically justified to maintain biodosimetry competence. However, dependable access to biological dosimetry capabilities is completely critical in event of an accident. In this paper the dose-response curve was measured for the induction of chromosomal alterations in peripheral blood lymphocytes after chronic exposure in vitro to neutron-gamma mixes field. Blood was obtained from one healthy donor and exposed to two neutron-gamma mixed field from sources {sup 241}AmBe (20 Ci) at the Neutron Calibration Laboratory (NCL-CRCN/NE-PE-Brazil). The evaluated absorbed doses were 0.2 Gy; 1.0 Gy and 2.5 Gy. The dicentric chromosomes were observed at metaphase, following colcemid accumulation and 1000 well-spread metaphase figures were analyzed for the presence of dicentrics by two experienced scorers after painted by giemsa 5%. Our preliminary results showed a linear dependence between radiations absorbed dose and dicentric chromosomes frequencies. Dose-response curve described in this paper will contribute to the construction of calibration curve that will be used in our laboratory for biological dosimetry. (author)

  12. The equidosemeter ED-02 as a device for dose equivalent measurements in mixed neutron and photon radiation fields

    International Nuclear Information System (INIS)

    Abrosimov, A.I.; Alekseev, A.G.; Antipov, V.A.; Golovachik, V.T.

    1985-01-01

    The equidosemeter ED-02 is to be used for simultaneous measurements of the dose equivalent, absorbed dose, and mean quality factor of mixed radiations. The detector is a tissue equivalent spherical low-pressure proportional counter tube the signal of which is simultaneously recorded in two channels - a current channel and a pulse one. The current channel is linear and its response proportional to the absorbed dose. The pulse channel includes a nonlinear pulse amplitude converter the characteristic of which, taking into account the required dependence of the mean quality factor on linear energy transfer, has been chosen in such a way that in final counting the pulse channel response is proportional to the difference between dose equivalent and absorbed dose. On the basis of calculations of event spectra in the sensitive volume of the detector, the energy dependence of the dosemeter sensitivity is analysed for neutron energies up to 20 MeV. The characteristic of the nonlinear converter has been calculated on the basis of the construction parameters of the detector and optimized with respect to a representative sample of neutron spectra beyond the shields of nuclear plants. The heterogeneity of the detector, i.e. the difference between the atomic composition of wall and filling and the composition of soft biological tissue as well as the effect of the conducting coating of the case cathode, has been taken into consideration. Moreover, the test results of the device in mixed neutron-photon fields of 60 Co, 239 Pu-α-Be and 252 Cf radioisotope sources are presented. The main measuring error of dose characteristics is shown to be less than 20% in the dose range 1 x 10 -3 to 4 x 10 -3 Sv/h. (author)

  13. Evaluation of individual dosimetry in mixed neutron and photon radiation fields (EVIDOS). Part II: conclusions and recommendations

    International Nuclear Information System (INIS)

    Schuhmacher, H.; Luszik-Bhadra, M.; Reginatto, M.; Bartlett, D.; Tanner, R.; Bolognese-Milsztajn, T.; Lacoste, V.; Boschung, M.; Fiechtner, A.; Coeck, M.; Vanhavere, F.; Curzio, G.; Errico d', F.; Kylloenen, J.-E.; Lindborg, L.

    2005-01-01

    Full text: The EVIDOS project, supported by the European Commission within the 5th Framework Programme, aims at evaluating state of the art dosimetry techniques in representative work-places of the nuclear industry. Seven European institutes with recognized expertise in radiation protection instruments and methods joined efforts with end users at nuclear power plants, at fuel processing and reprocessing plants, and at transport and storage facilities. A particular task of the project was to develop methods to characterize the neutron component of mixed radiation fields at workplaces and to derive reference values of radiation protection quantities from energy and direction distributions of the neutron fluence. While other presentations at this workshop describe the methods developed and the instruments used, this presentation will summarize the main results, draw conclusions and discuss recommendations relevant to routine monitoring. The final results from the project include a catalogue with spectra and dosimetric data for 14 different workplace fields (boiling water reactor, pressurized water reactor, research reactor, fuel processing, storage of spent fuel), instruments and procedures to derive reference values for personal dose equivalent and other radiation protection quantities, and novel personal dosemeters for mixed radiation and results on their dosimetric and technical performance. A number of questions will be addressed in the presentation, including: which methods allow to determine H*(10) and H p (10) in complex mixed n/γ radiation fields with acceptable uncertainty?; what is the influence of the energy and direction distributions of neutrons on the ratios between H*(10), H p (10) and E?; how much do the readings of area monitors deviate from H*(10) and do they give conservative estimates of H p (10) and E?; how much do the readings of personal dosemeters deviate from H p (10) and do they give conservative estimates of E?; do new active (electronic

  14. Measurement and assessment of mixed neutron-gamma radiation fields around the reconstructed HWRR

    International Nuclear Information System (INIS)

    Chen Changmao; Xie Jianlun; Chun Yuqing; Lin Nairong; Liu Jinhua; Su Jingling; Wei Zemin

    1987-01-01

    The neutron spectra around the HWRR (Heavy Water Research Reactor) of the Institute of Atomic Energy of China were measured. For the neutron spectra at different measuring points, the mean neutron energies ranged from 11 to 201 keV, the maximum energies were below 5 MeV, the effective quality factors were between 2.5 and 5, and the fast neutron dose equivalents mostly contributed the large fraction. During normal operation of the reactor, the n-γ dose equivalent rates in working areas were measured as well. In the experimental hall and the basement of the reactor, the mean values of the n/γ dose equivalent ratios were 15% and 31%, respectively; the γ dose equivalents were predominant. The annual dose equivalents to the persons working in the areas mentioned above possibly exceed the dose equivalent limit

  15. Study of the response to neutrons of a personal dosemeter in mixed fields (n, γ) in function of Hp(10)

    International Nuclear Information System (INIS)

    Cruzate, J.; Gregori, B.; Carelli, J.; Aguerre, L.; Discacciatti, A.

    2006-01-01

    In this work it is presented the theoretical study and their experimental validation of the answer of the personal dosimetro in terms of the component of neutrons of the personal equivalent dose Hpn(10) in function of the energy, in presence of fields of neutrons and range. The personal dosimetro, based on detecting termoluminiscentes (TLD), it consists of two detectors 7LiF and two 6LiF, located low filters of plastic and cadmium starting from whose information is evaluated the component range and of neutrons of the dose. Additionally it consists of a detecting CaF2, used basically to discriminate against the energy of the component range and to make the corresponding corrections on the evaluation of the dose range obtained with the 7LiF. The answer to neutrons in function of the energy, defined as the quotient among the one I number of reactions 6Li(n, a)4He taken place in each TLD and the Hpn(10), it was calculated using the code MCNPX and the library ENDF/B-VI. You model the dosimetro under the irradiation conditions proposed by the ISO8529-3. Faces monoenergeticos were simulated in the range of energy understood between 70 keV and 5 MeV. The dispersion in each one of the results of the simulation is smaller than 3%. You I study the existent relationship among the answer te6rica, reactions (n,a)/Hpn(10) and the experimental one, nC/Hpn(10), for a given thermal treatment. The factor of resulting conversion is constant in the energy and similar to 1,71 104 reacciones(n, a)/nC, with a smaller standard deviation to 10%. The experimental answer was obtained starting from the irradiations carried out in the mark of the International Intercomparacion of Dosimetria in Mixed Campos (n,) 2004 organized by the OIEA next to the PTB (Germany) and the IRSN (France). The extension of these calculations to other spectra of neutrons of fields real they will allow to obtain group of factors of application conversion in routine and accidental situations. (Author)

  16. Neutron-photon mixed field dosimetry by TLD-700 glow curve analysis and its implementation in dose monitoring for Boron Neutron Capture Therapy (BNCT) treatments

    Energy Technology Data Exchange (ETDEWEB)

    Boggio, E. F.; Longhino, J. M. [Centro Atomico Bariloche, Departamento de Fisica de Reactores y Radiaciones / CNEA, Av. E. Bustillo Km 9.5, R8402AGP San Carlos de Bariloche (Argentina); Andres, P. A., E-mail: efboggio@cab.cnea.gov.ar [Centro Atomico Bariloche, Division Proteccion Radiologica / CNEA, Av. E. Bustillo Km 9.5, R8402AGP San Carlos de Bariloche (Argentina)

    2015-10-15

    BNCT is a cancerous cells selective, non-conventional radiotherapy modality to treat malignant tumors such as glioblastoma, melanoma and recurrent head and neck cancer. It consists of a two-step procedure: first, the patient is injected with a tumor localizing drug containing a non-radioactive isotope (Boron-10) with high slow neutron capture cross-section. In a second step, the patient is irradiated with neutrons, which are absorbed by the Boron-10 agent with the subsequently nuclear reaction B- 10(n,a)Li-7, thereby resulting in dose at cellular level due to the high-Let particles. The neutron fields suitable for BNCT are characterized by high neutron fluxes and low gamma dose. Determination of each component is not an easy task, especially when the volume of measurement is quite small or inaccessible for a miniature ionization chamber, for example. A method of measuring the photon and slow neutron dose(mainly by N-14 and B-10) from the glow curve (GC) analysis of a single {sup 7}LiF thermoluminescence detector is evaluated. This method was suggested by the group headed by Dr. Grazia Gambarini. The dosemeters used were TLD-600 ({sup 6}LiF:Mg,Ti with 95.6% {sup 6}Li) and TLD-700 ({sup 7}LiF:Mg,Ti with 99.9% {sup 7}LiF) from Harshaw. Photon dose measurement using the GC analysis method with TLD-700 in mixed fields requires the relation of the two main peaks of a TLD-600 GC shape obtained from an exposition to the same neutron field, and a photon calibrated GC with TLD-700. The requirements for slow neutron dose measurements are similar. In order to properly apply the GC analysis method at the Ra-6 Research Reactor BNCT facility, measurements were carried out in a standard water phantom, fully characterized on the BNCT beam by conventional techniques (activation detectors and paired ionization chambers technique). Next, the method was implemented in whole body dose monitoring of a patient undergoing a BNCT treatment, using a Bo MAb (Bottle Manikin Absorption) phantom

  17. Spectroscopy of heavy nuclei by configuration mixing of symmetry restored mean-field states: shape coexistence in neutron-deficient Pb isotopes

    International Nuclear Information System (INIS)

    Bender, M.; Heenen, P.H.; Bonche, P.; Duguet, T.

    2003-01-01

    We study shape coexistence and low-energy excitation spectra in neutron-deficient Pb isotopes using configuration mixing of angular-momentum and particle-number projected self-consistent mean-field states. The same Skyrme interaction SLy6 is used everywhere in connection with a density-dependent zero-range pairing force. (orig.)

  18. Establishing personal dosimetry procedure using optically stimulated luminescence dosimeters in photon and mixed photon-neutron radiation fields

    International Nuclear Information System (INIS)

    Le Ngoc Thiem; Bui Duc Ky; Trinh Van Giap; Nguyen Huu Quyet; Ho Quang Tuan; Vu Manh Khoi; Chu Vu Long

    2017-01-01

    According to Vietnamese Law on Atomic Energy, personal dosimetry (PD) for radiation workers is required periodically in order to fulfil the national legal requirements on occupational radiation dose management. Since the radiation applications have become popular in Vietnamese society, the thermal luminescence dosimeters (TLDs) have been used as passive dosimeters for occupational monitoring in the nation. Together with the quick increase in radiation applications and the number of personnel working in radiation fields, the Optically Stimulated Luminescence Dosimeters (OSLDs) have been first introduced since 2015. This work presents the establishment of PD measuring procedure using OSLDs which are used for measuring photons and betas known as Inlight model 2 OSL (OSLDs-p,e) and for measuring mixed radiations of neutrons, photons and betas known as Inlight LDR model 2 (OSLDs-n,p,e). Such following features of OSLDs are investigated: detection limit, energy response, linearity, reproducibility, angular dependency and fading with both types of OSLDs-p,e and OSLDs-n,p,e. The result of an intercomparison in PD using OSLDs is also presented in the work. The research work also indicates that OSL dosimetry can be an alternative method applied in PD and possibly become one of the most popular personal dosimetry method in the future. (author)

  19. Hyperon-mixed neutron stars

    International Nuclear Information System (INIS)

    Takatsuka, Tatsuyuki

    2004-01-01

    Hyperon mixing in neutron star matter is investigated by the G-matrix-based effective interaction approach under the attention to use the YN and the YY potentials compatible with hypernuclear data and is shown to occur at densities relevant to neutron star cores, together with discussions to clarify the mechanism of hyperon contamination. It is remarked that developed Y-mixed phase causes a dramatic softening of the neutron star equation of state and leads to the serious problem that the resulting maximum mass M max for neutron star model contradicts the observed neutron star mass (M max obs = 1.44 M Θ ), suggesting the necessity of some extra repulsion'' in hypernuclear system. It is shown that the introduction of three-body repulsion similar to that in nuclear system can resolve the serious situation and under the consistency with observation (M max > M obs ) the threshold densities for Λ and Σ - are pushed to higher density side, from 2ρ 0 to ∼ 4ρ 0 (ρ 0 being the nuclear density). On the basis of a realistic Y-mixed neutron star model, occurrence of Y-superfluidity essential for ''hyperon cooling'' scenario is studied and both of Λ- and Σ - -superfluids are shown to be realized with their critical temperatures 10 8-9 K, meaning that the hyperon cooling'' is a promising candidate for a fast non-standard cooling demanded for some neutron stars with low surface temperature. A comment is given as to the consequence of less attractive ΛΛ interaction suggested by the ''NAGARA event'' ΛΛ 6 He. (author)

  20. Therapy of infections in mice irradiated in mixed neutron/photon fields and inflicted with wound trauma: a review of current work.

    Science.gov (United States)

    Ledney, G D; Madonna, G S; Elliott, T B; Moore, M M; Jackson, W E

    1991-10-01

    When host antimicrobial defenses are severely compromised by radiation or trauma in conjunction with radiation, death from sepsis results. To evaluate therapies for sepsis in radiation casualties, we developed models of acquired and induced bacterial infections in irradiated and irradiated-wounded mice. Animals were exposed to either a mixed radiation field of equal proportions of neutrons and gamma rays (n/gamma = 1) from a TRIGA reactor or pure gamma rays from 60[Co sources. Skin wounds (15% of total body surface area) were inflicted under methoxyflurane anesthesia 1 h after irradiation. In all mice, wounding after irradiation decreased resistance to infection. Treatments with the immunomodulator synthetic trehalose dicorynomycolate (S-TDCM) before or after mixed neutron-gamma irradiation or gamma irradiation increased survival. Therapy with S-TDCM for mice irradiated with either a mixed field or gamma rays increased resistance to Klebsiella pneumoniae-induced infections. Combined therapy with S-TDCM and ceftriaxone for K. pneumoniae infections in mice exposed to a mixed radiation field or to gamma rays was more effective than single-agent therapy. In all irradiated-wounded mice, single therapy of acquired infections with an antibiotic or S-TDCM did not increase survival. Survival of irradiated-wounded mice after topical application of gentamicin sulfate cream suggested that bacteria colonizing the wound disseminated systemically in untreated irradiated mice, resulting in death from sepsis. In lethal models of acquired infections in irradiated-wounded mice, significant increases in survival were achieved when systemic treatments with S-TDCM or gentamicin were combined with topical treatments of gentamicin cream. Therapies for sepsis in all mice exposed to a mixed field were less effective than in mice exposed to gamma rays. Nonetheless, the data show a principle by which successful therapy may be provided to individuals receiving tissue trauma in conjunction with

  1. Mixed field dosimetry with paired ionization chambers

    International Nuclear Information System (INIS)

    Coppola, M.; Porro, F.

    1977-01-01

    This report describes the results of neutron and gamma mixed-field dosimetry obtained by the Ispra Group in the framework of the European Neutron Dosimetry intercomparison Project (ENDIP). The experimental method and the formulation employed for the derivation of Kerma results are also present

  2. Dose calculation in biological samples in a mixed neutron-gamma field at the TRIGA reactor of the University of Mainz

    DEFF Research Database (Denmark)

    Schmitz, T.; Blaickner, M.; Schütz, C.

    2010-01-01

    and pin-diodes. Material and methods. When L-α-alanine is irradiated with ionizing radiation, it forms a stable radical which can be detected by electron spin resonance (ESR) spectroscopy. The value of the ESR signal correlates to the amount of absorbed dose. The dose for each pellet is calculated using......To establish Boron Neutron Capture Therapy (BNCT) for non-resectable liver metastases and for in vitro experiments at the TRIGA Mark II reactor at the University of Mainz, Germany, it is necessary to have a reliable dose monitoring system. The in vitro experiments are used to determine the relative......-calculations for mixed radiation fields and the Hansen & Olsen alanine detector response model. With the acquired data about the background dose and charged particle spectrum, and with the acquired information of the neutron flux, we are capable of calculating the dose to the tissue. Conclusion. Monte Carlo simulation...

  3. Mixed field dose equivalent measuring instruments

    International Nuclear Information System (INIS)

    Brackenbush, L.W.; McDonald, J.C.; Endres, G.W.R.; Quam, W.

    1985-01-01

    In the past, separate instruments have been used to monitor dose equivalent from neutrons and gamma rays. It has been demonstrated that it is now possible to measure simultaneously neutron and gamma dose with a single instrument, the tissue equivalent proportional counter (TEPC). With appropriate algorithms dose equivalent can also be determined from the TEPC. A simple ''pocket rem meter'' for measuring neutron dose equivalent has already been developed. Improved algorithms for determining dose equivalent for mixed fields are presented. (author)

  4. Dosimetry of an accident in mixed field (neutrons, photons) using the spectrometry by electronic paramagnetic resonance(EPR); Dosimetrie d'accident en champ mixte (neutrons, photons) utilisant la spectrometrie par resonance paramagnetique electronique (RPE)

    Energy Technology Data Exchange (ETDEWEB)

    Herve, M.L

    2006-03-15

    In a radiological accident, the assessment of the dose received by the victim is relevant information for the therapeutic strategy. Two complementary dosimetric techniques based on physical means are used in routine practice in the laboratory: EPR spectroscopy performed on materials removed from the victim or gathered from the vicinity of the victim and Monte Carlo calculations. EPR dosimetry, has been used successfully several times in cases of photon or electron overexposures. Accidental exposure may also occur with a neutron component. The aim of this work is to investigate the potentiality of EPR dosimetry for mixed photon and neutron field exposure with different organic materials (ascorbic acid, sorbitol, glucose, galactose, fructose, mannose, lactose and sucrose). The influence of irradiation parameters (dose, dose rate, photon energy) and of environmental parameters (temperature of heating, light exposure) on the EPR signal amplitude was studied. To assess the neutron sensitivity, the materials were exposed to a mixed radiation field of experimental reactors with different neutron to photon ratios. The relative neutron sensitivity was found to range from 10% to 43% according to the materials. Prior knowledge of the ratio between the dose in samples measured by EPR spectrometry and organ or whole body dose obtained by calculations previously performed for these different configurations, makes it possible to give a first estimation of the dose received by the victim in a short delay. The second aim of this work is to provide data relevant for a quick assessment of the dose distribution in case of accidental overexposure based on EPR measurements performed on one or several points of the body. The study consists in determining by calculation the relation between the dose to the organs and whole body and the dose to specific points of the body, like teeth, bones or samples located in the pockets of victim clothes, for different external exposures corresponding

  5. Criteria for personal dosimetry in mixed radiation fields in space. [analyzing trapped protons, tissue disintegration stars, and neutrons

    Science.gov (United States)

    Schaefer, H. J.

    1974-01-01

    The complexity of direct reading and passive dosimeters for monitoring radiation is studied to strike the right balance of compromise to simplify the monitoring procedure. Trapped protons, tissue disintegration stars, and neutrons are analyzed.

  6. Microdosimetry of intermediate energy neutrons in fast neutron fields

    International Nuclear Information System (INIS)

    Saion, E.B.; Watt, D.E.

    1988-01-01

    A coaxial double cylindrical proportional counter has been constructed for microdosimetry of intermediate energy neutrons in mixed fields. Details are given of the measured gas gain and resolution characteristics of the counter for a wide range of anode voltages. Event spectra due to intermediate neutrons in any desired energy band is achieved by an appropriate choice of thickness of the common dividing wall in the counter and by appropriate use of the coincidence, anticoincidence pulse counting arrangements. Calculated estimates indicate that the dose contribution by fast neutrons to the energy deposition events in the intermediate neutron range may be as large as 25%. Empirical procedures being investigated aim to determine the necessary corrections to be applied to the microdose distributions, with a precision of 10%. (author)

  7. Using multi spherical spectrometry for determination of dosimetric characteristics of mixed neutron and gamma radiation fields of fission sources

    International Nuclear Information System (INIS)

    Fyulep, M.; Nikodemova, D.; Grabovtsova, A.; Galan, P.; Trousil, J.

    1977-01-01

    Possibilities of the application of multispherical spectrometry in personnel dosimetry of neutrons (n) and gamma radiation (γ) are considered. Studies were made to elucidate a possibility of using albedo dosemeters to increase the sensitivity of personnel dosemeters. Determined were the dose due to the (n,γ) reaction in a human body, absorbed dose and dose equivalent. The effect of (n,γ) dose on the reading of personnel gamma dosemeter was considered. It is shown that the above effect on the dosemeter readings for frontal irradiation by a broad neutron beam in everyday personnel dosimetry near 252 Cf sources may be neglected. Only in the case of strongly slowed-down fission spectrum the effect of the (n,γ) reaction is considerable. The application of albedo dosemeter is expedient to take into account the corrections of personnel dosemeter readings [ru

  8. Configuration mixing of mean-field states

    International Nuclear Information System (INIS)

    Bender, M; Heenen, P-H

    2005-01-01

    Starting from self-consistent mean-field models, we discuss how to include correlations from fluctuations in collective degrees of freedom through symmetry restoration and configuration mixing, which give access to ground-state correlations and collective excitations. As an example for the method, we discuss the spectroscopy of neutron-deficient Pb isotopes

  9. Study of the response to neutrons of a personal dosemeter in mixed fields (n, {gamma}) in function of Hp(10); Estudio de la respuesta a neutrones de un dosimetro personal en campos mixtos (n, {gamma}) en funcion de Hp(10)

    Energy Technology Data Exchange (ETDEWEB)

    Cruzate, J.; Gregori, B.; Carelli, J.; Aguerre, L.; Discacciatti, A. [Autoridad REgulatoria Nuclear, Av. del Libertador 8250 (1429), Buenos Aires (Argentina)]. e-mail: cruzate@cae.arn.gov.ar

    2006-07-01

    In this work it is presented the theoretical study and their experimental validation of the answer of the personal dosimetro in terms of the component of neutrons of the personal equivalent dose Hpn(10) in function of the energy, in presence of fields of neutrons and range. The personal dosimetro, based on detecting termoluminiscentes (TLD), it consists of two detectors 7LiF and two 6LiF, located low filters of plastic and cadmium starting from whose information is evaluated the component range and of neutrons of the dose. Additionally it consists of a detecting CaF2, used basically to discriminate against the energy of the component range and to make the corresponding corrections on the evaluation of the dose range obtained with the 7LiF. The answer to neutrons in function of the energy, defined as the quotient among the one I number of reactions 6Li(n, a)4He taken place in each TLD and the Hpn(10), it was calculated using the code MCNPX and the library ENDF/B-VI. You model the dosimetro under the irradiation conditions proposed by the ISO8529-3. Faces monoenergeticos were simulated in the range of energy understood between 70 keV and 5 MeV. The dispersion in each one of the results of the simulation is smaller than 3%. You I study the existent relationship among the answer te6rica, reactions (n,a)/Hpn(10) and the experimental one, nC/Hpn(10), for a given thermal treatment. The factor of resulting conversion is constant in the energy and similar to 1,71 104 reacciones(n, a)/nC, with a smaller standard deviation to 10%. The experimental answer was obtained starting from the irradiations carried out in the mark of the International Intercomparacion of Dosimetria in Mixed Campos (n,) 2004 organized by the OIEA next to the PTB (Germany) and the IRSN (France). The extension of these calculations to other spectra of neutrons of fields real they will allow to obtain group of factors of application conversion in routine and accidental situations. (Author)

  10. Individual neutron monitoring in workplaces with mixed neutron/proton radiation

    International Nuclear Information System (INIS)

    Bolognese-Milsztajn, T.; Bartlett, D.; Boschung, M.; Coeck, M.; Curzio, G.; D'Errico, F.; Fiechtner, A.; Giusti, V.; Gressier, V.; Kylloenen, J.; Lacoste, V.; Lindborg, L.; Luszik-Bhadra, M.; Molinos, C.; Pelcot, G.; Reginatto, M.; Schuhmacher, H.; Tanner, R.; Vanhavere, F.; Derdau, D.

    2004-01-01

    EVIDOS ('evaluation of individual dosimetry in mixed neutron and photon radiation fields') is an European Commission (EC)-sponsored project that aims at a significant improvement of radiation protection dosimetry in mixed neutron/photon fields via spectrometric and dosimetric investigations in representative workplaces of the nuclear industry. In particular, new spectrometry methods are developed that provide the energy and direction distribution of the neutron fluence from which the reference dosimetric quantities are derived and compared to the readings of dosemeters. The final results of the project will be a comprehensive set of spectrometric and dosimetric data for the workplaces and an analysis of the performance of dosemeters, including novel electronic dosemeters. This paper gives an overview of the project and focuses on the results from measurements performed in calibration fields with broad energy distributions (simulated workplace fields) and on the first results from workplaces in the nuclear industry, inside a boiling water reactor and around a spent fuel transport cask. (authors)

  11. Neutron optics using transverse field neutron spin echo method

    International Nuclear Information System (INIS)

    Achiwa, Norio; Hino, Masahiro; Yamauchi, Yoshihiro; Takakura, Hiroyuki; Tasaki, Seiji; Akiyoshi, Tsunekazu; Ebisawa, Toru.

    1993-01-01

    A neutron spin echo (NSE) spectrometer with perpendicular magnetic field to the neutron scattering plane, using an iron yoke type electro-magnet has been developed. A combination of cold neutron guider, supermirror neutron polarizer of double reflection type and supermirror neutron analyser was adopted for the spectrometer. The first application of the NSE spectrometer to neutron optics by passing Larmor precessing neutrons through gas, solid and liquid materials of several different lengths which are inserted in one of the precession field have been examined. Preliminary NSE spectra of this sample geometry are discussed. (author)

  12. Hyperon-mixed neutron star matter and neutron stars

    International Nuclear Information System (INIS)

    Nishizaki, Shigeru; Takatsuka, Tatsuyuki; Yamamoto, Yasuo

    2002-01-01

    Effective Σ - n and Σ - Σ - interactions are derived from the G-matrix calculations for {n+Σ - } matter and employed in the investigation of hyperon mixing in neutron star matter. The threshold densities ρ t (Y) at which hyperons start to appear are between 2ρ 0 and 3ρ 0 (where ρ 0 is the normal nuclear density) for both Λ and Σ - , and their fractions increase rapidly with baryon density, reaching 10% already for ρ≅ρ t + ρ 0 . The mechanism of hyperon mixing and single-particle properties, such as the effective mass and the potential depth, are analyzed taking into account the roles of YN and NN interactions. The resulting equation of state is found to be too soft to sustain the observed neutron star mass M obs =1.44(solar mass). We discuss the reason for this and stress the necessity of the ''extra repulsion'' for YN and YY interactions to resolve this crucial problem. It is remarked that ρ t (Y) would be as large as 4ρ 0 for neutron stars compatible with M obs . A comment is given regarding the effects on the Y-mixing problem from a less attractive ΛΛ interaction, newly suggested by the NAGARA event. (author)

  13. Do neutrons feel electric fields?

    International Nuclear Information System (INIS)

    Klein, Tony; Werner, Sam

    1991-01-01

    An accounts is given of the results of a co-operative research carried out at the University of Melbourne in Australia and the University of Missouri, Columbia in the United States on the physics of neutrons and their interactions as a test of fundamental principles in quantum mechanics and electrodynamics. In particular it comments on the verification of the Aharonov-Casher effect in electric as well as magnetic fields in the case of neutral particles. It was demonstrated that neutrons have a magnetic moment which precess and acquire phase shifts when exposed to magnetic fields. The sign of the measured phase shift agreed with the theoretical prediction and the magnitude was within one and a half standard deviations of it. 12 refs., 4 figs

  14. Neutron Dark-Field Imaging

    Science.gov (United States)

    Mullins, David

    2017-09-01

    Neutron imaging is typically used to image and reconstruct objects that are difficult to image using X-Ray imaging techniques. X-Ray absorption is primarily determined by the electron density of the material. This makes it difficult to image objects within materials that have high densities such as metal. However, the neutron scattering cross section primarily depends on the strong nuclear force, which varies somewhat randomly across the periodic table. In this project, an imaging technique known as dark field imaging using a far-field interferometer has been used to study a sample of granite. With this technique, interferometric phase images are generated. The dispersion of the microstructure of the sample dephases the beam, reducing the visibility. Collecting tomographic projections at different autocorrelation lengths (from 100 nanometers to 1.74 micrometers) essentially creates a 3D small angle scattering pattern, enabling mapping of how the microstructure is distributed throughout the sample.

  15. Study of neutron fields around an intense neutron generator.

    Science.gov (United States)

    Kicka, L; Machrafi, R; Miller, A

    2017-12-01

    Neutron fields in the vicinity of the newly built neutron facility, at the University of Ontario Institute of Technology (UOIT), have been investigated in a series of Monte Carlo simulations and measurements. The facility hosts a P-385 neutron generator based on a deuterium-deuterium fusion reaction. The neutron fluence at different locations around the neutron generator facility has been simulated using MCNPX 2.7E Monte Carlo particle transport program. To characterize neutron fields, three neutron sources were modeled with distributions corresponding to different incident deuteron energies of 90kV, 110kV, and 130kV. Measurements have been carried out to determine the dose rate at locations adjacent to the generator using bubble detectors (BDs). The neutron intensity was evaluated and the total dose rates corresponding to different applied acceleration potentials were estimated at various locations. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Magnetic Fields of Neutron Stars

    Indian Academy of Sciences (India)

    Sushan Konar

    2017-09-12

    Sep 12, 2017 ... the material properties of the region where currents supporting the .... 1The evolution of magnetic field in neutron stars, in particular, the question of .... −10, 10. −9, 10. −8. M⊙/yr respec- tively. See Konar & Bhattacharya (1997) for details. Peq ≃ 1.9 ms ..... ported by a grant (SR/WOS-A/PM-1038/2014) from.

  17. Hyperon-mixed neutron star matter and neutron stars

    CERN Document Server

    Nishizaki, S; Yamamoto, Y

    2002-01-01

    Effective SIGMA sup - n and SIGMA sup -SIGMA sup - interactions are derived from the G-matrix calculations for left brace n+SIGMA sup -right brace matter and employed in the investigation of hyperon mixing in neutron star matter. The threshold densities rho sub t (Y) at which hyperons start to appear are between 2 rho sub 0 and 3 rho sub 0 (where rho sub 0 is the normal nuclear density) for both LAMBDA and SIGMA sup - , and their fractions increase rapidly with baryon density, reaching 10% already for rho approx = rho sub t + rho sub 0. The mechanism of hyperon mixing and single-particle properties, such as the effective mass and the potential depth, are analyzed taking into account the roles of YN and NN interactions. The resulting equation of state is found to be too soft to sustain the observed neutron star mass M sub o sub b sub s =1.44(solar mass). We discuss the reason for this and stress the necessity of the ''extra repulsion'' for YN and YY interactions to resolve this crucial problem. It is remarked ...

  18. Superfluidity of hyperon-mixed neutron stars

    International Nuclear Information System (INIS)

    Takatsuka, Tatsuyuki; Nishizaki, Shigeru; Yamamoto, Yasuo; Tamagaki, Ryozo

    2002-01-01

    Superfluidity of hyperons (Y) admixed in neutron star cores is investigated by a realistic approach. It is found that hyperons such as Λ and Σ - are likely to be superfluid due mainly to their large effective masses in the medium, in addition to their 1 S 0 -pairing attraction not so different from that of nucleons. Also the existence of nucleon superfluidity at high-density is investigated under a developed Y-contamination. It is found that the density change of nucleon components due to the Y-mixing does not work for the realization of n-superfluid and makes the existence of p-superfluid more unlikely, as compared to the normal case without the Y-mixing. (author)

  19. Polarized neutron reflectometry in high magnetic fields

    International Nuclear Information System (INIS)

    Fritzsche, H.

    2005-01-01

    A simple method is described to maintain the polarization of a neutron beam on its way through the large magnetic stray fields produced by a vertical field of a cryomagnet with a split-coil geometry. The two key issues are the proper shielding of the neutron spin flippers and an additional radial field component in order to guide the neutron spin through the region of the null point (i.e., point of reversal for the vertical field component). Calculations of the neutron's spin rotation as well as polarized neutron reflectometry experiments on an ErFe 2 /DyFe 2 multilayer show the perfect performance of the used setup. The recently commissioned cryomagnet M5 with a maximum vertical field of up to 7.2 T in asymmetric mode for polarized neutrons and 9 T in symmetric mode for unpolarized neutrons was used on the C5 spectrometer in reflectometry mode, at the NRU reactor in Chalk River, Canada

  20. Hyper-thermal neutron irradiation field for neutron capture therapy

    International Nuclear Information System (INIS)

    Sakurai, Yoshinori; Kobayashi, Tooru; Kanda, Keiji

    1994-01-01

    The utilization of hyper-thermal neutrons, which have an energy spectrum of a Maxwell distribution higher than the room temperature of 300 K, has been studied in order to improve the thermal neutron flux distribution in a living body for a deep-seated tumor in neutron capture therapy (NCT). Simulation calculations using MCNP-V3 were carried out in order to investigate the characteristics of the hyper-thermal neutron irradiation field. From the results of simulation calculations, the following were confirmed: (i) The irradiation field of the hyper-thermal neutrons is feasible by using some scattering materials with high temperature, such as Be, BeO, C, SiC and ZrH 1.7 . Especially, ZrH 1.7 is thought to be the best material because of good characteristics of up-scattering for thermal neutrons. (ii) The ZrH 1.7 of 1200 K yields the hyper-thermal neutrons of a Maxwell-like distribution at about 2000 K and the treatable depth is about 1.5 cm larger comparing with the irradiation of the thermal neutrons of 300 K. (iii) The contamination by the secondary gamma-rays from the scattering materials can be sufficiently eliminated to the tolerance level for NCT through the bismuth layer, without the larger change of the energy spectrum of hyper-thermal neutrons. ((orig.))

  1. A Neutron Radiography System for Field Use

    Science.gov (United States)

    1989-06-01

    provoked a major renewal of interest in neutron radiography because it promises to bring neutron radiography to the workplace , a convenience provided...II I~F I C II i IiH i ii MTL TR 89-52 I-AD A NEUTRON RADIOGRAPHY SYSTEM N FOR FIELD USE e~m JOHN J. ANTAL and ALFRED S. MAROTTA, and LOUIS J. FARESE...COVERED A NEUTRON RADIOGRAPHY SYSTEM FOR FIELD USE Final Report 6. PERFORMING OR1. REPORT NUMBER 7. AUTHOR(s) S. CONTRACT OR GRANT NUMBER(s) John J

  2. Neutron stars velocities and magnetic fields

    Science.gov (United States)

    Paret, Daryel Manreza; Martinez, A. Perez; Ayala, Alejandro.; Piccinelli, G.; Sanchez, A.

    2018-01-01

    We study a model that explain neutron stars velocities due to the anisotropic emission of neutrinos. Strong magnetic fields present in neutron stars are the source of the anisotropy in the system. To compute the velocity of the neutron star we model its core as composed by strange quark matter and analice the properties of a magnetized quark gas at finite temperature and density. Specifically we have obtained the electron polarization and the specific heat of magnetized fermions as a functions of the temperature, chemical potential and magnetic field which allow us to study the velocity of the neutron star as a function of these parameters.

  3. Evolution of Neutron Star Magnetic Fields

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    in nuclei. The neutrons are expected to form a 3P superfluid and the protons a 1S ... crust are expected to form a lattice; the electrons are free and highly degenerate, .... the reduced magnetic fields in neutron stars processed in binaries,.

  4. An effective field theory for the neutron electric dipole moment

    International Nuclear Information System (INIS)

    Chang, D.; Kephart, T.W.; Keung, W.Y.; Yuan, T.C.

    1992-01-01

    We derive a CP-odd effective field theory involving the field strengths of the gluon and the photon and their duals as a result of integrating out a heavy quark which carries both the chromo-electric dipole moment and electric dipole moment. The coefficients of the induced gluonic, photonic, and mixed gluon-photon operators with dimension ≤ 8 are determined. Implications of some of these operators on the neutron electric dipole moment are also discussed. (orig.)

  5. Development of neutron calibration field using accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Baba, Mamoru [Tohoku Univ., Cyclotron and Radioisotope Center, Sendai, Miyagi (Japan)

    2003-03-01

    A brief summary is given on the fast neutron calibration fields for 1) 8 keV to 15 MeV range, and 2) 30-80 MeV range. The field for 8 keV to 15 MeV range was developed at the Fast Neutron Laboratory (FNL) at Tohoku University using a 4.5 MV pulsed Dynamitron accelerator and neutron production reactions, {sup 45}Sc(p, n), {sup 7}Li(p, n), {sup 3}H(p, n), D(d, n) and T(d, n). The latter 30-80 MeV fields are setup at TIARA of Takasaki Establishment of Japan Atomic Energy Research Institute, and at Cyclotron Radio Isotope Center (CYRIC) of Tohoku University using a 90 MeV AVF cyclotron and the {sup 7}Li(p, n) reaction. These fields have been applied for various calibration of neutron spectrometers and dosimeters, and for irradiation purposes. (author)

  6. Neutron stars, magnetic fields, and gravitational waves

    International Nuclear Information System (INIS)

    Lamb, F.K.

    2001-01-01

    The r-modes of rapidly spinning young neutron stars have recently attracted attention as a promising source of detectable gravitational radiation. These neutron stars are expected to have magnetic fields ∼ 10 12 G. The r-mode velocity perturbation causes differential motion of the fluid in the star; this is a kinematic effect. In addition, the radiation-reaction associated with emission of gravitational radiation by r-waves drives additional differential fluid motions; this is a dynamic effect. These differential fluid motions distort the magnetic fields of neutron stars and may therefore play an important role in determining the structure of neutron star magnetic fields. If the stellar field is ∼ 10 16 (Ω/Ω B ) G or stronger, the usual r-modes are no longer normal modes of the star; here Ω and Ω B are the angular velocities of the star and at which mass shedding occurs. Much weaker magnetic fields can prevent gravitational radiation from amplifying the r-modes or damp existing r-mode oscillations on a relatively short timescale by extracting energy from the modes faster than gravitational wave emission can pump energy into them. The onset of proton superconductivity in the cores of newly formed magnetic neutron stars typically increases the effect on the r-modes of the magnetic field in the core by many orders of magnitude. Once the core has become superconducting, magnetic fields of the order of 10 12 G or greater are usually sufficient to damp r-modes that have been excited by emission of gravitational radiation and to suppress any further emission. A rapid drop in the strength of r-mode gravitational radiation from young neutron stars may therefore signal the onset of superconductivity in the core and provide a lower bound on the strength of the magnetic field there. Hence, measurements of r-mode gravitational waves from newly formed neutron stars may provide valuable diagnostic information about magnetic field strengths, cooling processes, and the

  7. Study of ceramic mixed boron element as a neutron shielding

    International Nuclear Information System (INIS)

    Ismail Mustapha; Mohd Reusmaazran Yusof; Md Fakarudin Ab Rahman; Nor Paiza Mohamad Hasan; Samihah Mustaffha; Yusof Abdullah; Mohamad Rabaie Shari; Airwan Affandi Mahmood; Nurliyana Abdullah; Hearie Hassan

    2012-01-01

    Shielding upon radiation should not be underestimated as it can causes hazard to health. Precautions on the released of radioactive materials should be well concerned and considered. Therefore, the combination of ceramic and boron make them very useful for shielding purpose in areas of low and intermediate neutron. A six grades of ceramic tile have been produced namely IMN05 - 5 % boron, IMN06 - 6 % boron, IMN07 - 7 % boron, IMN08 - 8 % boron, IMN09 - 9 % boron, IMN10 - 10 % boron from mixing, press and sintered process. Boron is a material that capable of absorbing and capturing neutron, so that neutron and gamma test were conducted to analyze the effectiveness of boron material in combination with ceramic as shielding. From the finding, percent reduction number of count per minute shows the ceramic tiles are capable to capture neutron. Apart from all the percentage of boron used, 10 % is the most effective shields since the percent reduction indicating greater neutron captured increased. (author)

  8. Mixed field dosimetry with the twin chamber technique

    International Nuclear Information System (INIS)

    Burger, G.; Maier, E.

    1974-04-01

    For the separate dosimetry of the neutron- and gamma-component in a mixed beam it is principally possible to use two ionization chambers with different ratios of neutron- to gamma sensitivity. Several authors proposed for this purpose the use of a homogenious TE-chamber filled with the TE-gas and of a carbon-chamber filled with CO 2 -gas. This chamber combination is also commercially available in several countries. The chambers are normally equipped with a continuous gas-flow provision and with a waterproof-housing for the use within liquid phantoms. The application of such chambers for mixed field dosimetry in the intercomparison project of the ICRU at the RARAF-facility in Brookhaven (International Neutron Dosimetry Intercomparison - INDI) is described. (orig./HP) [de

  9. Neutron Scattering and High Magnetic Fields

    Energy Technology Data Exchange (ETDEWEB)

    Winn, Barry L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Stone, Matthew B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2014-11-01

    The workshop “Neutron Scattering and High Magnetic Fields” was held September 4-5, 2014 at the Oak Ridge National Laboratory (ORNL). The workshop was held in response to a recent report by the National Research Council of the National Academy of Sciences entitled “High Magnetic Field Science and Its Application in the United States: Current Status and Future Directions.”1 This report highlights the fact that neutron scattering measurements carried out in high magnetic fields provide important opportunities for new science. The workshop explored the range of the scientific discoveries that could be enabled with neutron scattering measurements at high fields (25 Tesla or larger), the various technologies that might be utilized to build specialized instruments and sample environment equipment to enable this research at ORNL, and possible routes to funding and constructing these facilities and portable high field sample environments.

  10. Effective delayed neutron fraction and prompt neutron lifetime of Tehran research reactor mixed-core

    International Nuclear Information System (INIS)

    Lashkari, A.; Khalafi, H.; Kazeminejad, H.

    2013-01-01

    Highlights: ► Kinetic parameters of Tehran research reactor mixed-core have been calculated. ► Burn-up effect on TRR kinetics parameters has been studied. ► Replacement of LEU-CFE with HEU-CFE in the TRR core has been investigated. ► Results of each mixed core were compared to the reference core. ► Calculation of kinetic parameters are necessary for reactivity and power excursion transient analysis. - Abstract: In this work, kinetic parameters of Tehran research reactor (TRR) mixed cores have been calculated. The mixed core configurations are made by replacement of the low enriched uranium control fuel elements with highly enriched uranium control fuel elements in the reference core. The MTR P C package, a nuclear reactor analysis tool, is used to perform the analysis. Simulations were carried out to compute effective delayed neutron fraction and prompt neutron lifetime. Calculation of kinetic parameters is necessary for reactivity and power excursion transient analysis. The results of this research show that effective delayed neutron fraction decreases and prompt neutron lifetime increases with the fuels burn-up. Also, by increasing the number of highly enriched uranium control fuel elements in the reference core, the prompt neutron lifetime increases, but effective delayed neutron fraction does not show any considerable change

  11. Proton mixing in -condensed phase of neutron star matter

    Energy Technology Data Exchange (ETDEWEB)

    Takatsuka, Tatsuyuki

    1984-08-01

    The mixing of protons in neutron star matter under the occurrence of condensation is studied in the framework of the ALS (Alternating Layer Spin) model and with the effective interaction approach. It is found that protons are likely to mix under the situation and cause a remarkable energy gain from neutron matter as the density increases. The extent of proton mixing becomes larger by about a factor (1.5-2.5) according to the density rho asymptotically equals (2-5)rho0, rho0 being the nuclear density, as compared with that for the case without pion condensation. The reason can be attributed to the two-dimensional nature of the Fermi gas state characteristic of the nucleon system under condensation.

  12. Neutron oscillations and the primordial magnetic field

    International Nuclear Information System (INIS)

    Sarkar, S.

    1988-01-01

    It has been claimed that a primordial magnetic field must exist in order to suppress possible oscillations of neutrons into antineutrons which would otherwise affect the cosmological synthesis of helium. We demonstrate that such oscillations, even if they do occur, have a negligible effect on primordial nucleosynthesis, thus refuting the above claim. Hence the possible existence of a primordial magnetic field, relevant to current speculations concerning superconducting 'cosmic strings', remains an open question. (author)

  13. Neutron field features in a calibration hall

    International Nuclear Information System (INIS)

    Vega C, H.R.; Gallego, E.; Lorente, A.

    2004-01-01

    A new source facility ( 241 Am-Be) has been installed in a large size bunker-type room. To characterize the neutron fields in the facility, detailed calculations have been made with MCNP-4C, showing the different components of the neutron radiation reaching the reference points (direct, in scattered, backscattered). The contribution from neutrons scattered in the walls to the total ambient dose equivalent remains reasonably low ( 6 LiI(Eu) scintillator (0.4 cm 0 x 0.4 cm), UTA4 response matrix and BUNKIUT unfolding code. The calculated and experimentally obtained spectra are compared, with small differences found in the epithermal and thermal region, attributable to the concrete composition used in the calculations. The H*(10) rate has been determined from the spectra, and then compared to the reading of an active dosemeter (LB 6411), with differences found lower than 8%. (Author)

  14. Photon iso-effective dose for cancer treatment with mixed field radiation based on dose-response assessment from human and an animal model: clinical application to boron neutron capture therapy for head and neck cancer.

    Science.gov (United States)

    González, S J; Pozzi, E C C; Monti Hughes, A; Provenzano, L; Koivunoro, H; Carando, D G; Thorp, S I; Casal, M R; Bortolussi, S; Trivillin, V A; Garabalino, M A; Curotto, P; Heber, E M; Santa Cruz, G A; Kankaanranta, L; Joensuu, H; Schwint, A E

    2017-10-03

    Boron neutron capture therapy (BNCT) is a treatment modality that combines different radiation qualities. Since the severity of biological damage following irradiation depends on the radiation type, a quantity different from absorbed dose is required to explain the effects observed in the clinical BNCT in terms of outcome compared with conventional photon radiation therapy. A new approach for calculating photon iso-effective doses in BNCT was introduced previously. The present work extends this model to include information from dose-response assessments in animal models and humans. Parameters of the model were determined for tumour and precancerous tissue using dose-response curves obtained from BNCT and photon studies performed in the hamster cheek pouch in vivo models of oral cancer and/or pre-cancer, and from head and neck cancer radiotherapy data with photons. To this end, suitable expressions of the dose-limiting Normal Tissue Complication and Tumour Control Probabilities for the reference radiation and for the mixed field BNCT radiation were developed. Pearson's correlation coefficients and p-values showed that TCP and NTCP models agreed with experimental data (with r  >  0.87 and p-values  >0.57). The photon iso-effective dose model was applied retrospectively to evaluate the dosimetry in tumours and mucosa for head and neck cancer patients treated with BNCT in Finland. Photon iso-effective doses in tumour were lower than those obtained with the standard RBE-weighted model (between 10% to 45%). The results also suggested that the probabilities of tumour control derived from photon iso-effective doses are more adequate to explain the clinical responses than those obtained with the RBE-weighted values. The dosimetry in the mucosa revealed that the photon iso-effective doses were about 30% to 50% higher than the corresponding RBE-weighted values. While the RBE-weighted doses are unable to predict mucosa toxicity, predictions based on the proposed

  15. Photon iso-effective dose for cancer treatment with mixed field radiation based on dose-response assessment from human and an animal model: clinical application to boron neutron capture therapy for head and neck cancer

    Science.gov (United States)

    González, S. J.; Pozzi, E. C. C.; Monti Hughes, A.; Provenzano, L.; Koivunoro, H.; Carando, D. G.; Thorp, S. I.; Casal, M. R.; Bortolussi, S.; Trivillin, V. A.; Garabalino, M. A.; Curotto, P.; Heber, E. M.; Santa Cruz, G. A.; Kankaanranta, L.; Joensuu, H.; Schwint, A. E.

    2017-10-01

    Boron neutron capture therapy (BNCT) is a treatment modality that combines different radiation qualities. Since the severity of biological damage following irradiation depends on the radiation type, a quantity different from absorbed dose is required to explain the effects observed in the clinical BNCT in terms of outcome compared with conventional photon radiation therapy. A new approach for calculating photon iso-effective doses in BNCT was introduced previously. The present work extends this model to include information from dose-response assessments in animal models and humans. Parameters of the model were determined for tumour and precancerous tissue using dose-response curves obtained from BNCT and photon studies performed in the hamster cheek pouch in vivo models of oral cancer and/or pre-cancer, and from head and neck cancer radiotherapy data with photons. To this end, suitable expressions of the dose-limiting Normal Tissue Complication and Tumour Control Probabilities for the reference radiation and for the mixed field BNCT radiation were developed. Pearson’s correlation coefficients and p-values showed that TCP and NTCP models agreed with experimental data (with r  >  0.87 and p-values  >0.57). The photon iso-effective dose model was applied retrospectively to evaluate the dosimetry in tumours and mucosa for head and neck cancer patients treated with BNCT in Finland. Photon iso-effective doses in tumour were lower than those obtained with the standard RBE-weighted model (between 10% to 45%). The results also suggested that the probabilities of tumour control derived from photon iso-effective doses are more adequate to explain the clinical responses than those obtained with the RBE-weighted values. The dosimetry in the mucosa revealed that the photon iso-effective doses were about 30% to 50% higher than the corresponding RBE-weighted values. While the RBE-weighted doses are unable to predict mucosa toxicity, predictions based on the proposed

  16. Neutron matter, neutron pairing, and neutron drops based on chiral effective field theory interactions

    Energy Technology Data Exchange (ETDEWEB)

    Krueger, Thomas

    2016-10-19

    The physics of neutron-rich systems is of great interest in nuclear and astrophysics. Precise knowledge of the properties of neutron-rich nuclei is crucial for understanding the synthesis of heavy elements. Infinite neutron matter determines properties of neutron stars, a final stage of heavy stars after a core-collapse supernova. It also provides a unique theoretical laboratory for nuclear forces. Strong interactions are determined by quantum chromodynamics (QCD). However, QCD is non-perturbative at low energies and one presently cannot directly calculate nuclear forces from it. Chiral effective field theory circumvents these problems and connects the symmetries of QCD to nuclear interactions. It naturally and systematically includes many-nucleon forces and gives access to uncertainty estimates. We use chiral interactions throughout all calculation in this thesis. Neutron stars are very extreme objects. The densities in their interior greatly exceed those in nuclei. The exact composition and properties of neutron stars is still unclear but they consist mainly of neutrons. One can explore neutron stars theoretically with calculations of neutron matter. In the inner core of neutron stars exist very high densities and thus maybe exotic phases of matter. To investigate whether there exists a phase transition to such phases even at moderate densities we study the chiral condensate in neutron matter, the order parameter of chiral symmetry breaking, and find no evidence for a phase transition at nuclear densities. We also calculate the more extreme system of spin-polarised neutron matter. With this we address the question whether there exists such a polarised phase in neutron stars and also provide a benchmark system for lattice QCD. We find spin-polarised neutron matter to be an almost non-interacting Fermi gas. To understand the cooling of neutron stars neutron pairing is of great importance. Due to the high densities especially triplet pairing is of interest. We

  17. Observation of nonadditive mixed-state phases with polarized neutrons.

    Science.gov (United States)

    Klepp, Jürgen; Sponar, Stephan; Filipp, Stefan; Lettner, Matthias; Badurek, Gerald; Hasegawa, Yuji

    2008-10-10

    In a neutron polarimetry experiment the mixed-state relative phases between spin eigenstates are determined from the maxima and minima of measured intensity oscillations. We consider evolutions leading to purely geometric, purely dynamical, and combined phases. It is experimentally demonstrated that the sum of the individually determined geometric and dynamical phases is not equal to the associated total phase which is obtained from a single measurement, unless the system is in a pure state.

  18. Neutronics of a mixed-flow gas-core reactor

    International Nuclear Information System (INIS)

    Soran, P.D.; Hansen, G.E.

    1977-11-01

    The study was made to investigate the neutronic feasibility of a mixed-flow gas-core reactor. Three reactor concepts were studied: four- and seven-cell radial reactors and a seven-cell scallop reactor. The reactors were fueled with UF 6 (either U-233 or U-235) and various parameters were varied. A four-cell reactor is not practical nor is the U-235 fueled seven-cell radial reactor; however, the 7-cell U-233 radial and scallop reactors can satisfy all design criteria. The mixed flow gas core reactor is a very attractive reactor concept and warrants further investigation

  19. Compilation of neutron flux density spectra and reaction rates in different neutron fields

    International Nuclear Information System (INIS)

    Ertek, C.

    1979-07-01

    Upon the recommendation of International Working Group of Reactor Radiation Measurements (IWGRRM), the compilation of neutron flux density spectra and the reaction rates obtained by activation and fission foils in different neutron fields is presented. The neutron fields considered are as follows: 1/E; iron block; LWR core and pressure vessel; LMFBR core and blanket; CTR first wall and blanket; fission spectrum

  20. Neutron stars. [quantum mechanical processes associated with magnetic fields

    Science.gov (United States)

    Canuto, V.

    1978-01-01

    Quantum-mechanical processes associated with the presence of high magnetic fields and the effect of such fields on the evolution of neutron stars are reviewed. A technical description of the interior of a neutron star is presented. The neutron star-pulsar relation is reviewed and consideration is given to supernovae explosions, flux conservation in neutron stars, gauge-invariant derivation of the equation of state for a strongly magnetized gas, neutron beta-decay, and the stability condition for a neutron star.

  1. Compilation of neutron flux density spectra and reaction rates in different neutron fields. V.3

    International Nuclear Information System (INIS)

    Ertek, C.

    1980-04-01

    Upon the recommendation of the International Working Group of Reactor Radiation Measurements (IWGRRM) a compilation of documents containing neutron flux density spectra and the reaction rates obtained by activiation and fission foils in different neutron fields is presented

  2. ESR-dosimetry in thermal and epithermal neutron fields for application in boron neutron capture therapy

    Energy Technology Data Exchange (ETDEWEB)

    Schmitz, Tobias

    2016-01-22

    Dosimetry is essential for every form of radiotherapy. In Boron Neutron Capture Therapy (BNCT) mixed neutron and gamma fields have to be considered. Dose is deposited in different neutron interactions with elements in the penetrated tissue and by gamma particles, which are always part of a neutron field. The therapeutic dose in BNCT is deposited by densely ionising particles, originating from the fragmentation of the isotope boron-10 after capture of a thermal neutron. Despite being investigated for decades, dosimetry in neutron beams or fields for BNCT remains complex, due to the variety in type and energy of the secondary particles. Today usually ionisation chambers combined with metal foils are used. The applied techniques require extensive effort and are time consuming, while the resulting uncertainties remain high. Consequently, the investigation of more effective techniques or alternative dosimeters is an important field of research. In this work the possibilities of ESR-dosimeters in those fields have been investigated. Certain materials, such as alanine, generate stable radicals upon irradiation. Using Electron Spin Resonance (ESR) spectrometry the amount of radicals, which is proportional to absorbed dose, can be quantified. Different ESR detector materials have been irradiated in the thermal neutron field of the research reactor TRIGA research reactor in Mainz, Germany, with five setups, generating different secondary particle spectra. Further irradiations have been conducted in two epithermal neutron beams. The detector response, however, strongly depends on the dose depositing particle type and energy. It is hence necessary to accompany measurements by computational modelling and simulation. In this work the Monte Carlo code FLUKA was used to calculate absorbed doses and dose components. The relative effectiveness (RE), linking absorbed dose and detector response, has been calculated using amorphous track models. For the simulation, detailed models of

  3. Biomedical and biophysical research and calibration projects: radiobiology. Chromosomal aberrations in human lymphocytes - response to mixed neutron/photon exposures

    International Nuclear Information System (INIS)

    Slabbert, J.P.; Hough, J.H.; Jansen, S.

    1991-01-01

    Whether synergistic interaction damage is realized when lymphocytes are exposed to mixed high/low LET radiation fields, and if so, how well these effects can be predicted, was investigated. Whole-blood samples were exposed, at 37 degrees C, to neutrons, 60 Co gamma-rays and a mixture of 25% neutrons and 75% photons. The mixture was delivered both sequentially and simultaneously. A significant difference between the sequential and simultaneous irradiations was evident. Both mixed-field exposures yield aberration frequencies in excess of the sum predicted for individual irradiations. 5 refs., 2 figs., 1 tab

  4. Performance of a PADC personal neutron dosemeter at simulated and real workplace fields of the nuclear industry

    International Nuclear Information System (INIS)

    Fiechtner, A.; Boschung, M.; Wernli, C.

    2007-01-01

    In the framework of the EVIDOS (Evaluation of Individual Dosimetry in Mixed Neutron and Photon Radiation Fields) project, funded by the EC, measurements with PADC personal neutron dosemeters were carried out at several workplace fields of the nuclear industry and at simulated workplace fields. The measured personal neutron dose equivalents of the PADC personal neutron dosemeter are compared with values that were assessed within the EVIDOS project by other partners. The detection limits for different spectra types are given. In cases were the neutron dose was too low to be measured by the PADC personal neutron dosemeter, the response is estimated by convoluting the responses to monoenergetic neutrons with the dose energy distribution measured within EVIDOS. The advantages and limitations of the PADC personal neutron dosemeter are discussed. (authors)

  5. Characteristics of thermal neutron calibration fields using a graphite pile

    International Nuclear Information System (INIS)

    Uchita, Yoshiaki; Saegusa, Jun; Kajimoto, Yoichi; Tanimura, Yoshihiko; Shimizu, Shigeru; Yoshizawa, Michio

    2005-03-01

    The Facility of Radiation Standards of Japan Atomic Energy Research Institute is equipped with thermal neutron fields for calibrating area and personal neutron dosemeters. The fields use moderated neutrons leaked from a graphite pile in which radionuclide sources are placed. In January 2003, we have renewed the pile with some modifications in its size. In accordance with the renewal, we measured and calculated thermal neutron fluence rates, neutron energy distributions and angular distributions of the fields. The thermal neutron fluence rates of the ''inside-pile fields'' and the outside-pile fields'' were determined by the gold foil activation method. The neutron energy distributions of the outside-pile fields were also measured with the Bonner multi-sphere spectrometer system. The contributions of epithermal and fast neutrons to the total dose-equivalents were 9% in the southern outside-pile field and 12% in the western outside-pile field. The personal dose-equivalents, H p,slab (10, α), in the outside-pile fields are evaluated by considering the calculated angular distributions of incoming neutrons. The H p,slab (10, α) was found to be about 40% higher than the value in assuming the unidirectional neutron between the pile and the test point. (author)

  6. Neutron dosemeter responses in workplace fields and the implications of using realistic neutron calibration fields

    International Nuclear Information System (INIS)

    Thomas, D.J.; Horwood, N.; Taylor, G.C.

    1999-01-01

    The use of realistic neutron calibration fields to overcome some of the problems associated with the response functions of presently available dosemeters, both area survey instruments and personal dosemeters, has been investigated. Realistic calibration fields have spectra which, compared to conventional radionuclide source based calibration fields, more closely match those of the workplace fields in which dosemeters are used. Monte Carlo simulations were performed to identify laboratory systems which would produce appropriate workplace-like calibration fields. A detailed analysis was then undertaken of the predicted under- and over-responses of dosemeters in a wide selection of measured workplace field spectra assuming calibration in a selection of calibration fields. These included both conventional radionuclide source calibration fields, and also several proposed realistic calibration fields. The present state of the art for dosemeter performance, and the possibilities of improving accuracy by using realistic calibration fields are both presented. (author)

  7. Neutrons in the field of metallurgy

    International Nuclear Information System (INIS)

    Novion, C. de

    1989-01-01

    Beams of thermal neutrons are now widely used for the study of material structure. Following a summary of the characteristics of the neutron-material interaction, and an outlook on the major uses of neutrons in metallurgy, we present some examples of application. The comparative advantages and drawbacks of neutrons and X-rays are discussed. 14 refs [fr

  8. Experimental investigations of the neutron contamination in high-energy photon fields at medical linear accelerators

    International Nuclear Information System (INIS)

    Brunckhorst, Elin

    2009-01-01

    The scope of this thesis was to develop a device for the detection of the photoneutron dose inside the high-energy photon field. The photoneutron contamination of a Siemens PRIMUS linear accelerator was investigated in detail in its 15 MV photon mode. The experimental examinations were performed with three ionisation chambers (a tissue equivalent chamber, a magnesium chamber and a 10 B-coated magnesium chamber) and two types of thermoluminescence detectors (enriched with 6 Li and 7 Li, respectively). The detectors have different sensitivities to photons and neutrons and their combination allows the dose separation in a mixed neutron/photon field. The application of the ionisation chamber system, as well as the present TLD system for photoneutron detection in high-energy photon beams is a new approach. The TLD neutron sensitivity was found to be too low for a measurement inside the open photon field and the further investigation focused on the ionisation chambers. The three ionisation chambers were calibrated at different photon and neutron sources and a the borated magnesium chamber showed a very high response to thermal neutrons. For a cross check of the calibration, the three chambers were also used for dose separation of a boron neutron capture therapy beam where the exact determination of the thermal neutron dose is essential. Very accurate results were achieved for the thermal neutron dose component. At the linear accelerator the chamber system was reduced to a paired chamber system utilising the two magnesium chambers, since the fast neutron component was to small to be separated. The neutron calibration of the three chambers could not be applied, instead a conversion of measured thermal neutron signal by the borated chamber to Monte Carlo simulated total neutron dose was performed. Measurements for open fields in solid water and liquid water were performed with the paired chamber system. In larger depths the neutron dose could be determined with an

  9. Experimental investigations of the neutron contamination in high-energy photon fields at medical linear accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Brunckhorst, Elin

    2009-02-26

    The scope of this thesis was to develop a device for the detection of the photoneutron dose inside the high-energy photon field. The photoneutron contamination of a Siemens PRIMUS linear accelerator was investigated in detail in its 15 MV photon mode. The experimental examinations were performed with three ionisation chambers (a tissue equivalent chamber, a magnesium chamber and a {sup 10}B-coated magnesium chamber) and two types of thermoluminescence detectors (enriched with {sup 6}Li and {sup 7}Li, respectively). The detectors have different sensitivities to photons and neutrons and their combination allows the dose separation in a mixed neutron/photon field. The application of the ionisation chamber system, as well as the present TLD system for photoneutron detection in high-energy photon beams is a new approach. The TLD neutron sensitivity was found to be too low for a measurement inside the open photon field and the further investigation focused on the ionisation chambers. The three ionisation chambers were calibrated at different photon and neutron sources and a the borated magnesium chamber showed a very high response to thermal neutrons. For a cross check of the calibration, the three chambers were also used for dose separation of a boron neutron capture therapy beam where the exact determination of the thermal neutron dose is essential. Very accurate results were achieved for the thermal neutron dose component. At the linear accelerator the chamber system was reduced to a paired chamber system utilising the two magnesium chambers, since the fast neutron component was to small to be separated. The neutron calibration of the three chambers could not be applied, instead a conversion of measured thermal neutron signal by the borated chamber to Monte Carlo simulated total neutron dose was performed. Measurements for open fields in solid water and liquid water were performed with the paired chamber system. In larger depths the neutron dose could be determined

  10. Monoenergetic neutron fields for the calibration of neutron dosemeters at the accelerator facility of the PTB

    International Nuclear Information System (INIS)

    Lesiecki, H.; Cosack, M.; Schoelermann, H.

    1987-01-01

    The present state in the realization of monoenergetic standard neutron fields and the possibility of calibrating neutron dose- and doserate meters at the accelerator facility of the PTB are described. There are excellent conditions for the performance of irradiations in the neutron energy range of 1 keV to 14.8 MeV. (orig.) [de

  11. Intermediate and fast neutron absorbed doses in fast neutron field at the RB reactor

    International Nuclear Information System (INIS)

    Sokcic-Kostic, M.; Pesic, M.; Antic, D.

    1987-10-01

    The experimental fuel channel EFC is created as one of the fast neutron fields at the RB reactor. The intermediate and fast neutron spectra in EFC are measured by activation technique. The intermediate and fast neutron absorbed doses are computed on the basis of these experimental results. At the end the obtained doses are compared. (author)

  12. Development of advanced radiation monitors for pulsed neutron fields

    CERN Document Server

    AUTHOR|(CDS)2081895

    The need of radiation detectors capable of efficiently measuring in pulsed neutron fields is attracting widespread interest since the 60s. The efforts of the scientific community substantially increased in the last decade due to the increasing number of applications in which this radiation field is encountered. This is a major issue especially at particle accelerator facilities, where pulsed neutron fields are present because of beam losses at targets, collimators and beam dumps, and where the correct assessment of the intensity of the neutron fields is fundamental for radiation protection monitoring. LUPIN is a neutron detector that combines an innovative acquisition electronics based on logarithmic amplification of the collected current signal and a special technique used to derive the total number of detected neutron interactions, which has been specifically conceived to work in pulsed neutron fields. Due to its special working principle, it is capable of overcoming the typical saturation issues encountere...

  13. Magnetic field devices for neutron spin transport and manipulation in precise neutron spin rotation measurements

    Energy Technology Data Exchange (ETDEWEB)

    Maldonado-Velázquez, M. [Posgrado en Ciencias Físicas, Universidad Nacional Autónoma de México, 04510 (Mexico); Barrón-Palos, L., E-mail: libertad@fisica.unam.mx [Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20-364, 01000 (Mexico); Crawford, C. [University of Kentucky, Lexington, KY 40506 (United States); Snow, W.M. [Indiana University, Bloomington, IN 47405 (United States)

    2017-05-11

    The neutron spin is a critical degree of freedom for many precision measurements using low-energy neutrons. Fundamental symmetries and interactions can be studied using polarized neutrons. Parity-violation (PV) in the hadronic weak interaction and the search for exotic forces that depend on the relative spin and velocity, are two questions of fundamental physics that can be studied via the neutron spin rotations that arise from the interaction of polarized cold neutrons and unpolarized matter. The Neutron Spin Rotation (NSR) collaboration developed a neutron polarimeter, capable of determining neutron spin rotations of the order of 10{sup −7} rad per meter of traversed material. This paper describes two key components of the NSR apparatus, responsible for the transport and manipulation of the spin of the neutrons before and after the target region, which is surrounded by magnetic shielding and where residual magnetic fields need to be below 100 μG. These magnetic field devices, called input and output coils, provide the magnetic field for adiabatic transport of the neutron spin in the regions outside the magnetic shielding while producing a sharp nonadiabatic transition of the neutron spin when entering/exiting the low-magnetic-field region. In addition, the coils are self contained, forcing the return magnetic flux into a compact region of space to minimize fringe fields outside. The design of the input and output coils is based on the magnetic scalar potential method.

  14. Neutron induced degradation in nitrided pyrogenic field oxide MOS capacitors

    CERN Document Server

    Vaidya, S J; Shaikh, A M; Chandorkar, A N

    2002-01-01

    Neutron induced oxide charge trapping and generation of interface states in MOS capacitors with pyrogenic and nitrided pyrogenic field oxides have been studied. In order to assess the damage due to neutrons alone, it is necessary to account for the damage produced by the accompanying gamma rays from neutron radiation. This is done by measuring the intensity of gamma radiation accompanying neutrons at different neutron fluences at the irradiation position. MOS capacitor structures were subjected to neutron radiation in a swimming pool type of reactor. Other samples from the same batch were then subjected to an equivalent dose of gamma radiation from a Co sup 6 sup 0 source. The difference in the damage observed was used to characterize the damage caused by neutrons. It is observed that neutrons, though uncharged, are capable of causing ionization damage. This damage is found to be significant when the radiation is performed under biased conditions. Nitridation in different ambients is found to improve the radi...

  15. The design, build and test of a digital analyzer for mixed radiation fields

    International Nuclear Information System (INIS)

    Joyce, M. J.; Aspinall, M. D.; Georgopoulos, K.; Cave, F. D.; Jarrah, Z.

    2009-01-01

    The design, build and test of a digital analyzer for mixed radiation fields is described. This instrument has been developed to provide portable, real-time discrimination of hard mixed fields comprising both neutrons and γ rays with energies typically above 0.5 MeV. The instrument in its standard form comprises a sensor head and a system unit, and affords the flexibility to provide processed data in the form of the traditional scatter-plot representation separating neutron and γ-ray components, or the full, sampled pulse data itself. The instrument has been tested with an americium-beryllium source in three different shielding arrangements to replicate the case in which there are only neutrons, only γ rays and where both neutrons and γ-rays are present. The instrument is observed to return consistent results. (authors)

  16. Dosimeter incorporating radiophotoluminescent detectors for thermal neutrons and γ-rays in n-γ fields

    Energy Technology Data Exchange (ETDEWEB)

    Salem, Y.O. [Groupe RaMsEs, Institut Pluridisciplinaire Hubert Curien (IPHC), UMR 7178 CNRS/IN2P3, 23 rue du Loess, BP 28, F-67037 Strasbourg Cedex 2 (France); Nachab, A., E-mail: a.nachab@uca.ma [Département de physique, Faculté Poly-disciplinaire, Université Cadi Ayyad, Route Sidi Bouzid BP 4162, 46000 Safi (Morocco); Roy, C.; Nourreddine, A. [Groupe RaMsEs, Institut Pluridisciplinaire Hubert Curien (IPHC), UMR 7178 CNRS/IN2P3, 23 rue du Loess, BP 28, F-67037 Strasbourg Cedex 2 (France)

    2016-10-15

    We have developed a dosimeter associating different neutron converters with two radiophotoluminescent detectors to measure thermal neutrons and γ-rays in a mixed n-γ field. Tests show that the H{sup ∗}(10) and H{sub p}(10) responses to thermal neutrons and γ-rays are linear with detection limits lower than 0.4 mSv. The angular dependence of the dosimeter response is satisfactory and the influence of a phantom on the results is examined.

  17. Finite field dependent mixed BRST transformation

    International Nuclear Information System (INIS)

    Upadhyay, Sudhaker; Mandal, Bhabani Prasad

    2013-01-01

    Joglekar and Mandal have generalized the usual Bechhi-Rouet-Stora-Tyutin (BRST) transformation by allowing infinitesimal BRST parameter finite and field dependent. Such a generalized BRST transformation (so-called FFBRST transformation) is also the symmetry of the effective action but not of the generating functional of the theory. We generalize the mixed BRST (sum of totally anti-commuting BRST and anti-BRST) symmetry transformation in same manner. We show that such a generalized mixed BRST transformation is the symmetry of the effective action as well as of the generating functional. We show our result by considering several explicit examples. (author)

  18. Interaction of neutrons with the matter in the laser field

    International Nuclear Information System (INIS)

    Zaretskij, D.F.; Lomonosov, V.V.

    1980-01-01

    The interactions of neutrons with the molecules, atoms and nuclei in the presence of the coherent electromagnetic radiation are considered. There are two effects which are discussed in detail: 1) the ''acceleration'' of thermal neutrons passed through the excited by the resonance laser wave molecular gas; 2) the induced by the laser field the slow neutron capture accompanied by the compound nucleus level excitation. The given effects, if they are experimentally detected, give the possibility to control the neutron flux (spectrum change, polarization, spatial modulation and etc.) and change the interaction cross sections of thermal and resonance neutrons with nuclei due to excitation of p levels of the compound nucleus [ru

  19. The neutron imaging system fielded at the National Ignition Facility

    Directory of Open Access Journals (Sweden)

    Fittinghoff D.N.

    2013-11-01

    Full Text Available We have fielded a neutron imaging system at the National Ignition Facility to collect images of fusion neutrons produced in the implosion of inertial confinement fusion experiments and scattered neutrons from (n, n′ reactions of the source neutrons in the surrounding dense material. A description of the neutron imaging system is presented, including the pinhole array aperture, the line-of-sight collimation, the scintillator-based detection system and the alignment systems and methods. Discussion of the alignment and resolution of the system is presented. We also discuss future improvements to the system hardware.

  20. Evaluation of mixed energy neutron doses using TLD NG-67 type

    International Nuclear Information System (INIS)

    Akhadi, Mukhlis; Thoyib Thamrin, M; Usmiyati Dewi, K.

    2000-01-01

    A research has been carried out to develop dose evaluation method of mixed neutron source with its neutron doses can be classified to two groups, I.e neutron doses with energy ≥ 0.5 eV and thermal neutron doses with energy less than 0.5 e V consist of epithermal and fast neutron, but in this research they were classified as fast neutron. Development of this dose evaluation method was carried out by sensitivity (S) intercomparison of TLD-600 to fast neutron, mixed energy neutron of nuclear rectors, and thermal neutron. From the experiment it was obtained that the value of Sfast : Sreactor : Sthermal = 0.005 : 0.010 : 1. Calibration factor (CF) of TLD is defined as 1/S. from the sensitivity data it can be obtained that the value of Cffast : Cfreactor : Cfthermal = 200 :100 : 1. The value of Cfreactor can be applied for mixed energy neutron doses evaluation of TLD-600. Key word : dosemeter, neutron dose, calibration factor, fast neutron, thermal neutron, nuclear reactor

  1. Neutron scattering studies of mixed-valence semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Mignot, J M [Laboratoire Leon Brillouin (LLB) - Centre d` Etudes de Saclay, 91 - Gif-sur-Yvette (France); Alekseev, P A [Kurchatov Institute, Moscow (Russian Federation)

    1994-12-31

    Neutron scattering experiments on the mixed-valence (MV) compounds SmB{sub 6} are reported. The inelastic magnetic response of SmB{sub 6} at T = 2 K, measured on a double-isotope single crystal,displays a strongly damped peak at 35 meV corresponding to the inter multiplet transition of Sm{sup 2+}. At lower energies ( h.{omega} {approx_equal} 14 meV), a narrow magnetic excitation is observed, with remarkable scattering-vector and temperature dependences of its intensity. This novel feature is discussed in terms of recent theoretical works describing the formation of an anisotropic local bound state in semiconducting MV materials. If the average samarium valence is decreased by substituting La for Sm, a peak is found to appear at high energies. The elastic magnetic form factor of SmB{sub 6} was determined using polarised neutrons and no significant difference is observed in its Q-dependence with respect to that of pure divalent samarium. This surprising behaviour is constant with previous measurements on the gold (high-pressure) phase of SmS. The above results are compared to those already reported for other MV materials. In particular existing information for TmSe is supplemented by recent inelastic scattering measurements carried out on a large stoichiometric single crystal. (author). 44 refs., 7 figs.

  2. Discussions in symposium 'neutron dosimetry in neutron fields - from detection techniques to medical applications'

    International Nuclear Information System (INIS)

    Tanimura, Y.; Sato, T.; Kumada, H.; Terunuma, T.; Sakae, T.; Harano, H.; Matsumoto, T.; Suzuki, T.; Matsufuji, N.

    2008-01-01

    Recently the traceability system (JCSS) of neutron standard based on the Japanese law 'Measurement Act' has been instituted. In addition, importance of the neutron dose evaluation has been increasing in not only the neutron capture medical treatment but also the proton or heavy particle therapy. Against such a background, a symposium 'Neutron dosimetry in neutron fields - From detection techniques to medical applications-' was held on March 29, 2008 and recent topics on the measuring instruments and their calibration, the traceability system, the simulation technique and the medical applications were introduced. This article summarizes the key points in the discussion at the symposium. (author)

  3. Least squares analysis of fission neutron standard fields

    International Nuclear Information System (INIS)

    Griffin, P.J.; Williams, J.G.

    1997-01-01

    A least squares analysis of fission neutron standard fields has been performed using the latest dosimetry cross sections. Discrepant nuclear data are identified and adjusted spectra for 252 Cf spontaneous fission and 235 U thermal fission fields are presented

  4. Neutron field characterization in the installation for BNCT study in the IEA-R1 reactor

    International Nuclear Information System (INIS)

    Carneiro Junior, Valdeci

    2008-01-01

    This work aims to characterize the mixed neutron and gamma field, in the sample irradiation position, in a research installation for Boron Neutron Capture Therapy (BNCT), in the IPEN IEA-R1 reactor. The BNCT technique has been studied as a safe and selective option in the treatment of resistant cancerigenous tumors or considered non-curable by the conventional techniques, for example, the Glioblastoma Multiform - a brain cancerigenous tumor. Neutron flux measurements were carried out: thermal, resonance and fast, as well as neutron and gamma rays doses, in the sample position, using activation foils detectors and thermoluminescent dosimeters. For the determination of the neutron spectrum and intensity, a set of different threshold activation foils and gold foils covered and uncovered with cadmium irradiated in the installation was used, analyzed by a high Pure Germanium semiconductor detector, coupled to an electronic system suitable for gamma spectrometry. The results were processed with the SAND-BP code. The doses due to gamma and neutron rays were determined using thermoluminescent dosimeters TLD 400 and TLD 700 sensitive to gamma and TLD 600, sensitive to neutrons. The TLDs were selected and used for obtaining the calibration curves - dosimeter answer versus dose - from each of the TLD three types, which were necessary to calculate the doses due to neutron and gamma, in the sample position. The radiation field, in the sample irradiation position, was characterized flux for thermal neutrons of 1.39.10 8 ± 0,12.10 8 n/cm 2 s the doses due to thermal neutrons are three times higher than those due to gamma radiation and confirm the reproducibility and consistency of the experimental findings obtained. Considering these results, the neutron field and gamma radiation showed to be appropriated for research in BNCT. (author)

  5. Investigation of Response of Several Neutron Surveymeters by a DT Neutron Generator

    International Nuclear Information System (INIS)

    Kim, Sang In; Jang, In Su; Kim, Jang Lyul; Lee, Jung IL; Kim, Bong Hwan

    2012-01-01

    Several neutron measuring devices were tested under the neutron fields characterized with two distinct kinds of thermal and fast neutron spectrum. These neutron fields were constructed by the mixing of both thermal neutron fields and fast neutron fields. The thermal neutron field was constructed using by a graphite pile with eight AmBe neutron sources. The fast neutron field of 14 MeV was made by a DT neutron generator. In order to change the fraction of fast neutron fluence rate in each neutron fields, a neutron generator was placed in the thermal neutron field at 50 cm and 150 cm from the reference position. The polyethylene neutron collimator was used to make moderated 14 MeV neutron field. These neutron spectra were measured by using a Bonner sphere system with an LiI scintillator, and dosimetric quantities delivered to neutron surveymeters were determined from these measurement results.

  6. Selective data analysis for diamond detectors in neutron fields

    Directory of Open Access Journals (Sweden)

    Weiss Christina

    2017-01-01

    Full Text Available Detectors based on synthetic chemical vapor deposition diamond gain importance in various neutron applications. The superior thermal robustness and the excellent radiation hardness of diamond as well as its excellent electronic properties make this material uniquely suited for rough environments, such as nuclear fission and fusion reactors. The intrinsic electronic properties of single-crystal diamond sensors allow distinguishing various interactions in the detector. This can be used to successfully suppress background of γ-rays and charged particles in different neutron experiments, such as neutron flux measurements in thermal nuclear reactors or cross-section measurements in fast neutron fields. A novel technique of distinguishing background reactions in neutron experiments with diamond detectors will be presented. A proof of principle will be given on the basis of experimental results in thermal and fast neutron fields.

  7. Personnel neutron dose assessment upgrade: Volume 2, Field neutron spectrometer for health physics applications

    International Nuclear Information System (INIS)

    Brackenbush, L.W.; Reece, W.D.; Miller, S.D.

    1988-07-01

    Both the (ICRP) and the (NCPR) have recommended an increase in neutron quality factors and the adoption of effective dose equivalent methods. The series of reports entitled Personnel Neutron Dose Assessment Upgrade (PNL-6620) addresses these changes. Volume 1 in this series of reports (Personnel Neutron Dosimetry Assessment) provided guidance on the characteristics, use, and calibration of personnel neutron dosimeters in order to meet the new recommendations. This report, Volume 2: Field Neutron Spectrometer for Health Physics Applications describes the development of a portable field spectrometer which can be set up for use in a few minutes by a single person. The field spectrometer described herein represents a significant advance in improving the accuracy of neutron dose assessment. It permits an immediate analysis of the energy spectral distribution associated with the radiation from which neutron quality factor can be determined. It is now possible to depart from the use of maximum Q by determining and realistically applying a lower Q based on spectral data. The field spectrometer is made up of two modules: a detector module with built-in electronics and an analysis module with a IBM PC/reg sign/-compatible computer to control the data acquisition and analysis of data in the field. The unit is simple enough to allow the operator to perform spectral measurements with minimal training. The instrument is intended for use in steady-state radiation fields with neutrons energies covering the fission spectrum range. The prototype field spectrometer has been field tested in plutonium processing facilities, and has been proven to operate satisfactorily. The prototype field spectrometer uses a 3 He proportional counter to measure the neutron energy spectrum between 50 keV and 5 MeV and a tissue equivalent proportional counter (TEPC) to measure absorbed neutron dose

  8. Simulation analysis of radiation fields inside phantoms for neutron irradiation

    International Nuclear Information System (INIS)

    Satoh, Daiki; Takahashi, Fumiaki; Endo, Akira; Ohmachi, Y.; Miyahara, N.

    2007-01-01

    Radiation fields inside phantoms have been calculated for neutron irradiation. Particle and heavy-ion transport code system PHITS was employed for the calculation. Energy and size dependences of neutron dose were analyzed using tissue equivalent spheres of different size. A voxel phantom of mouse was developed based on CT images of an 8-week-old male C3H/HeNs mouse. Deposition energy inside the mouse was calculated for 2- and 10-MeV neutron irradiation. (author)

  9. Ionization signals from diamond detectors in fast-neutron fields

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, C. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); CIVIDEC Instrumentation, Wien (Austria); Frais-Koelbl, H. [University of Applied Sciences, Wiener Neustadt (Austria); Griesmayer, E.; Kavrigin, P. [CIVIDEC Instrumentation, Wien (Austria); Vienna University of Technology, Wien (Austria)

    2016-09-15

    In this paper we introduce a novel analysis technique for measurements with single-crystal chemical vapor deposition (sCVD) diamond detectors in fast-neutron fields. This method exploits the unique electronic property of sCVD diamond sensors that the signal shape of the detector current is directly proportional to the initial ionization profile. In fast-neutron fields the diamond sensor acts simultaneously as target and sensor. The interaction of neutrons with the stable isotopes {sup 12}C and {sup 13}C is of interest for fast-neutron diagnostics. The measured signal shapes of detector current pulses are used to identify individual types of interactions in the diamond with the goal to select neutron-induced reactions in the diamond and to suppress neutron-induced background reactions as well as γ-background. The method is verified with experimental data from a measurement in a 14.3 MeV neutron beam at JRC-IRMM, Geel/Belgium, where the {sup 13}C(n, α){sup 10}Be reaction was successfully extracted from the dominating background of recoil protons and γ-rays and the energy resolution of the {sup 12}C(n, α){sup 9}Be reaction was substantially improved. The presented analysis technique is especially relevant for diagnostics in harsh radiation environments, like fission and fusion reactors. It allows to extract the neutron spectrum from the background, and is particularly applicable to neutron flux monitoring and neutron spectroscopy. (orig.)

  10. Neutrino emissivity in the quark-hadron mixed phase of neutron stars

    Energy Technology Data Exchange (ETDEWEB)

    Spinella, William M. [Computational Science Research Center San Diego State University, San Diego, CA (United States); San Diego State University, Department of Physics, San Diego, CA (United States); Weber, Fridolin [San Diego State University, Department of Physics, San Diego, CA (United States); University of California San Diego, Center for Astrophysics and Space Sciences, La Jolla, CA (United States); Contrera, Gustavo A. [CONICET, Buenos Aires (Argentina); CONICET - Dept. de Fisica, UNLP, IFLP, La Plata (Argentina); Universidad Nacional de La Plata, Grupo de Gravitacion, Astrofisica y Cosmologia, Facultad de Ciencias Astronomicas y Geofisicas, La Plata (Argentina); Orsaria, Milva G. [CONICET, Buenos Aires (Argentina); Universidad Nacional de La Plata, Grupo de Gravitacion, Astrofisica y Cosmologia, Facultad de Ciencias Astronomicas y Geofisicas, La Plata (Argentina)

    2016-03-15

    Numerous theoretical studies using various equation of state models have shown that quark matter may exist at the extreme densities in the cores of high-mass neutron stars. It has also been shown that a phase transition from hadronic matter to quark matter would result in an extended mixed phase region that would segregate phases by net charge to minimize the total energy of the phase, leading to the formation of a crystalline lattice. The existence of quark matter in the core of a neutron star may have significant consequences for its thermal evolution, which for thousands of years is facilitated primarily by neutrino emission. In this work we investigate the effect a crystalline quark-hadron mixed phase can have on the neutrino emissivity from the core. To this end we calculate the equation of state using the relativistic mean-field approximation to model hadronic matter and a nonlocal extension of the three-flavor Nambu-Jona-Lasinio model for quark matter. Next we determine the extent of the quark-hadron mixed phase and its crystalline structure using the Glendenning construction, allowing for the formation of spherical blob, rod, and slab rare phase geometries. Finally we calculate the neutrino emissivity due to electron-lattice interactions utilizing the formalism developed for the analogous process in neutron star crusts. We find that the contribution to the neutrino emissivity due to the presence of a crystalline quark-hadron mixed phase is substantial compared to other mechanisms at fairly low temperatures (

  11. Electromagnetic multipole fields of neutron stars

    International Nuclear Information System (INIS)

    Roberts, W.J.

    1979-01-01

    There is now indisputable evidence that some pulsars possess space velocities so high that internal asymmetries in the dynamics of their formation are strongly implied. We develop in this paper a complete formalism for the calculation of the only such mechanism that has yet been subjected to quantitative analysis: electromagnetic recoil radiation. To make the general problem tractable without doing violence to the physics, we have made the following simplifying assumptions: (1) the magnetic induction B in athin shell enclosing the surface can be satisfactorily approximated by a sum of vacuum multipole fields; (2) the star is spherical, and all parts are in good electrical contact; (3) vertical-bar Ω X r vertical-barvery-much-less-thanc everywhere within the star; and (4) the star is surrounded by a vacuum. Our qualitative conclusions hold even if these assumptions are violated, but corrections to our quantitative results required by a relaxation of our assumptions are not easily computed.Given this simple electrodynamic model of a neutron star, we solve the following problems: (1) What electric multipoles are induced by each magnetic multipole. (2) What is the general formula for the recoil produced by the projection on the rotational axis of a net linear momentum flux produced by the rotation of any two magnetic multipoles. (3) What is the set of centered multipoles that represents the field of an arbitrary off-centered multipole. We use these general results go perform a detailed analysis of the linear momentum radiated by an off-centered dipole. We find a force larger by a factor 6 than that obtained for the special case treated in the best previous calculation. In spite of this considerable increase in the computed strengrh of the effect, we still believe it to be too weak to produce the large space velocities observed for pulsars. For the mechanism to be effective, the pulsar must be born rotating near the breakup velocity

  12. Transmutation of Minor Actinide in well thermalized neutron field and application of advanced neutron source (ANS)

    International Nuclear Information System (INIS)

    Iwasaki, Tomohiko; Hirakawa, Naohiro

    1995-01-01

    Transmutation of Minor Actinide (MA) in a well thermalized neutron field was studied. Since MA nuclides have large effective cross sections in the well thermalized neutron field, the transmutation in the well thermalized neutron field has an advantage of high transmutation rate. However, the transmutation rate largely decreases by accumulation of 246 Cm when MA is transmuted only in the well thermalized neutron field for a long period. An acceleration method of burn-up of 246 Cm was studied. High transmutation rate can be obtained by providing a neutron field with high flux in the energy region between 1 and 100 eV. Two stage transmutation using the well thermalized neutron field and this field can transmute MA rapidly. The applicability of the Advanced Neutron Source (ANS) to the transmutation of MA was examined for a typical MA with the composition in the high-level waste generated in the conventional PWR. If the ANS is applied without changing the fuel inventory, the amount of MA which corresponds to that produced by a conventional 1,175 MWe PWR in one year can be transmuted by the ANS in one year. Furthermore, the amount of the residual can be reduced to about 1g (10 -5 of the initial MA weight) by continuing the transmutation for 5 years owing to the two stage transmutation. (author)

  13. Band mixing effects in mean field theories

    International Nuclear Information System (INIS)

    Kuyucak, S.; Morrison, I.

    1989-01-01

    The 1/N expansion method, which is an angular momentum projected mean field theory, is used to investigate the nature of electromagnetic transitions in the interacting boson model (IBM). Conversely, comparison with the exact IBM results sheds light on the range of validity of the mean field theory. It is shown that the projected mean field results for the E2 transitions among the ground, β and γ bands are incomplete for the spin dependent terms and it is essential to include band mixing effect for a correct (Mikhailov) analysis of E2 data. The algebraic expressions derived are general and will be useful in the analysis of experimental data in terms of both the sd and sdg boson models. 17 refs., 7 figs., 8 tabs

  14. Matter and Radiation in Strong Magnetic Fields of Neutron Stars

    International Nuclear Information System (INIS)

    Lai, D

    2006-01-01

    Neutron stars are found to possess magnetic fields ranging from 10 8 G to 10 15 G, much larger than achievable in terrestrial laboratories. Understanding the properties of matter and radiative transfer in strong magnetic fields is essential for the proper interpretation of various observations of magnetic neutron stars, including radio pulsars and magnetars. This paper reviews the atomic/molecular physics and condensed matter physics in strong magnetic fields, as well as recent works on modeling radiation from magnetized neutron star atmospheres/surface layers

  15. Alabama warm mix asphalt field study : final report.

    Science.gov (United States)

    2010-05-01

    The Alabama Department of Transportation hosted a warm mix asphalt field demonstration in August 2007. The warm mix asphalt technology demonstrated was Evotherm Dispersed Asphalt Technology. The WMA and hot mix asphalt produced for the demonstration ...

  16. Thermal neutron standard fields with the KUR heavy water facility

    International Nuclear Information System (INIS)

    Kanda, K.; Kobayashi, K.; Shibata, T.

    1978-01-01

    A heavy water facility attached to the KUR (Kyoto University Reactor, swimming pool type, 5 MW) yields pure thermal neutrons in the Maxwellian distribution. The facility is faced to the core of KUR and it contains about 2 tons of heavy water. The thickness of the layer is about 140 cm. The neutron spectrum was measured with the time of flight technique using a fast chopper. The measured spectrum was in good agreement with the Maxwellian distribution in all energy region for thermal neutrons. The neutron temperature was slightly higher than the heavy water temperature. The contamination of epithermal and fast neutrons caused by photo-neutrons of the γ-n reaction of heavy water was very small. The maximum intensity of thermal neutrons is 3x10 11 n/cm 2 sec. When the bismuth scatterer is attached, the gamma rays contamination is eliminated by the ratio of 0.05 of gamma rays to neutrons in rem. This standard neutron field has been used for such experiments as thermal neutron cross section measurement, detector calibration, activation analysis, biomedical purposes etc. (author)

  17. Neutron induced degradation in nitrided pyrogenic field oxide MOS capacitors

    Science.gov (United States)

    Vaidya, S. J.; Sharma, D. K.; Shaikh, A. M.; Chandorkar, A. N.

    2002-09-01

    Neutron induced oxide charge trapping and generation of interface states in MOS capacitors with pyrogenic and nitrided pyrogenic field oxides have been studied. In order to assess the damage due to neutrons alone, it is necessary to account for the damage produced by the accompanying gamma rays from neutron radiation. This is done by measuring the intensity of gamma radiation accompanying neutrons at different neutron fluences at the irradiation position. MOS capacitor structures were subjected to neutron radiation in a swimming pool type of reactor. Other samples from the same batch were then subjected to an equivalent dose of gamma radiation from a Co 60 source. The difference in the damage observed was used to characterize the damage caused by neutrons. It is observed that neutrons, though uncharged, are capable of causing ionization damage. This damage is found to be significant when the radiation is performed under biased conditions. Nitridation in different ambients is found to improve the radiation performance of pyrogenic field oxides with respect to positive charge build up as well as interface state generation. Pyrogenic oxide nitrided in N 2O is found to be the best oxynitride as damage due to neutrons is the least.

  18. Neutron field inside a PET Cyclotron vault room

    International Nuclear Information System (INIS)

    Vega C, H.R.; Mendez, R.; Iniguez, M.P.; Climent, J.M.; Penuelas, I.; Barquero, R.

    2006-01-01

    The neutron field around a Positron Emission Tomography cyclotron was investigated during 18 F radioisotope production with an 18 MeV proton beam. In this study the Ion Beam Application cyclotron, model Cyclone 18/9, was utilized. Measurements were carried out with a Bonner sphere neutron spectrometer with pairs of thermoluminescent dosemeters (TLD600 and TLD700) as thermal neutron detector. The TLDs readouts were utilized to unfold the neutron spectra at three different positions inside the cyclotron's vault room. With the spectra the Ambient dose equivalent was calculated. Neutron spectra unfolding were performed with the BUNKIUT code and the UTA4 response matrix. Neutron spectra were also determined by Monte Carlo calculations using a detailed model of cyclotron and vault room. (Author)

  19. A crystalline quark-hadron mixed phase in neutron stars

    International Nuclear Information System (INIS)

    Glendenning, N.K.

    1994-01-01

    The mixed phase of a substance undergoing a first order phase transition has entirely different behavior according as the substance has more than one conserved charge or only one, as in the text book examples. In the latter case the pressure and nature of the phases are constants throughout the coexistence phase. For systems with more than one conserved charge (or independent component) we prove two theorems: (1) The pressure and the nature of the phases in equilibrium change continuously as the proportion of the phases varies from one pure phase to the other. (2) If one of the conserved charges is the Coulomb force, an intermediate-range order will be created by the competition between Coulomb and surface interface energy. Their sum is minimized when the coexistence phase assumes a Coulomb lattice of one phase immersed in the other. The geometry will vary continuously as the proportion of phases. We illustrate the theorems for a simple description of the hadron to quark phase transition in neutron stars and find a crystalline phase many kilometers thick. However the theorems are general and pertain to chemical mixtures, nuclear systems, either static as in stars or dynamic as in collisions, and have possible application to phase transitions in the early universe

  20. Effects of hyperon mixing on neutron star properties

    International Nuclear Information System (INIS)

    Takatsuka, Tatsuyuki

    2008-01-01

    From a serious inconsistency between theory and observations for the mass of hyperon-mixed neutron stars (NSs), it is stressed that some "extra repulsion" is missing in hypernuclear systems and three-body force repulsion is tested for the cases with phenomenological Illinoi's type, 2π-exchange via Δ-excitation type (2πΔ) and string-junction quark model(SJM). It is remarked that the "extra repulsion" should have a nature to act universally, i.e., independent of baryon species. The SJM three-body repulsion can meet the condition because of flavor-independence and {2πΔ+SJM} scheme is shown to be a promising candidate for the "extra repulsion". Occurence of Λ and Σ - superfluidities are shown also by a realistic approach, which importantly supports the idea of nonstandard fast "hyperon cooling" scenario to explain colder class NSs. However, less attractive ΛΛ interaction suggested by the "NAGARA event" ( ΛΛ 6 He) leads to the disappearance of Λ superfluidity and the breaking down of the scenario. In this connection, the revival of "Λ superfluidity" due to ΛΣ - pairing instead of ΛΛ one is discussed in a new scheme of "bubble shell" hypothesis where the matching of two different Fermi surfaces is forced. (author)

  1. Transmission of neutrons in serpentine mixed and ordinary concrete a comparative study

    International Nuclear Information System (INIS)

    Ravishankar, R.; Bhattacharyya, Sarmishtha; Bandyopadhyay, Tapas; Sarkar, P.K.

    2002-01-01

    Full text: In particle accelerator facilities, for radiation shielding, concrete is commonly used for its effectiveness in attenuating neutrons in addition to its good structural and mechanical properties. Neutron attenuation depends largely on the water content in the concrete. Serpentine mixed concrete is reported to retain better water content than ordinary concrete. Experiments have been carried out to compare neutron attenuation properties of Serpentine mixed concrete slabs and ordinary concrete slabs of different thickness. Transmission of neutrons from a 185 GBq Pu-Be neutron source has been studied using NE-213 liquid scintillator detector, along with the associated electronics to discriminate neutron from gamma using pulse shape discrimination techniques. The energy differential neutron spectra transmitted through the concrete slabs and the corresponding dose have been obtained by unfolding the pulse height spectra using the FERDOR-U computer code and proper response matrix data of the NE-213 detector. The neutron transmission factors through both Serpentine and Ordinary concrete slabs have been studied. The results show serpentine mixed concrete slabs can attenuate more neutrons of varying energies compared to ordinary concrete slabs of equal dimensions. From the trend, it has been found out, with the increase in slab thickness, the gain in neutron attenuation increases. This is due to increase in quantity of serpentine with the increase in thickness of, concrete. A Monte Carlo simulation carried out, for theoretical analysis of the results, has been found to be in order

  2. Transmission of neutrons in serpentine mixed and ordinary concrete- a comparative study

    International Nuclear Information System (INIS)

    Ravishankar, R.; Bhattacharyya, Sarmishtha; Bandyopadhyay, Tapas; Sarkar, P. K.

    2002-01-01

    In particle accelerator facilities, for radiation shielding, concrete is commonly used for its effectiveness in attenuating neutrons in addition to its good structural and mechanical properties. Neutron attenuation depends largely on the water content in the concrete. Serpentine mixed concrete is reported to retain better water content than ordinary concrete. Experiments have been carried out to compare neutron attenuation properties of Serpentine mixed concrete slabs and ordinary concrete slabs of different thickness. Transmission of neutrons from a 185 GBq Pu-Be neutron source has been studied using NE-213 liquid scintillator detector, along with the associated electronics to discriminate neutron from gamma using pulse shape discrimination techniques. The energy differential neutron spectra transmitted through the concrete slabs and the corresponding dose have been obtained by unfolding the pulse height spectra using the FERDOR-U computer code and proper response matrix data of the NE-213 detector. The neutron transmission factors through both Serpentine and Ordinary concrete slabs have been studied. The results show serpentine mixed concrete slabs can attenuate more neutrons of varying energies compared to ordinary concrete slabs of equal dimensions. From the trend, it has been found out, with the increase in slab thickness, the gain in neutron attenuation increases. This is due to increase in quantity of serpentine with the increase in thickness of concrete. A Monte Carlo simulation carried out, for theoretical analysis of the results, has been found to be in order

  3. Magnetization of dense neutron matter in a strong magnetic field

    International Nuclear Information System (INIS)

    Isaev, A.A.; Yang, J.

    2010-01-01

    Spin polarized states in neutron matter at a strong magnetic field up to 1018 G are considered in the model with the Skyrme effective interaction. Analyzing the self consistent equations at zero temperature, it is shown that a thermodynamically stable branch of solutions for the spin polarization parameter as a function of the density corresponds to the negative spin polarization when the majority of neutron spins are oriented oppositely to the direction of the magnetic field. In addition, beginning from some threshold density dependent on the magnetic field strength, the self-consistent equations have also two other branches of solutions for the spin polarization parameter with the positive spin polarization. The free energy corresponding to one of these branches turns out to be very close to the free energy corresponding to the thermodynamically preferable branch with the negative spin polarization. As a consequence, at a strong magnetic field, the state with the positive spin polarization can be realized as a metastable state at the high density region in neutron matter which changes into a thermodynamically stable state with the negative spin polarization with decrease in the density at some threshold value. The calculations of the neutron spin polarization parameter, energy per neutron, and chemical potentials of spin-up and spin-down neutrons as functions of the magnetic field strength show that the influence of the magnetic field remains small at the field strengths up to 1017 G.

  4. Evaluation of room-scattered neutrons at the JNC Tokai neutron reference field

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Tadayoshi; Tsujimura, Norio [Japan Nuclear Cycle Development Inst., Tokai, Ibaraki (Japan). Tokai Works; Oyanagi, Katsumi [Japan Radiation Engineering Co., Ltd., Hitachi, Ibaraki (Japan)

    2002-09-01

    Neutron reference fields for calibrating neutron-measuring devices in JNC Tokai Works are produced by using radionuclide neutron sources, {sup 241}Am-Be and {sup 252}Cf sources. The reference field for calibration includes scattered neutrons from the material surrounding sources, wall, floor and ceiling of the irradiation room. It is, therefore, necessary to evaluate the scattered neutrons contribution and their energy spectra at reference points. Spectral measurements were performed with a set of Bonner multi-sphere spectrometers and the reference fields were characterized in terms of spectral composition and the fractions of room-scattered neutrons. In addition, two techniques stated in ISO 10647, the shadow-cone method and the polynomial fit method, for correcting the contributions from the room-scattered neutrons to the readings of neutron survey instruments were compared. It was found that the two methods gave an equivalent result within a deviation of 3.3% at a source-to-detector distance from 50cm to 500cm. (author)

  5. Evaluation of room-scattered neutrons at the JNC Tokai neutron reference field

    International Nuclear Information System (INIS)

    Yoshida, Tadayoshi; Tsujimura, Norio

    2002-01-01

    Neutron reference fields for calibrating neutron-measuring devices in JNC Tokai Works are produced by using radionuclide neutron sources, 241 Am-Be and 252 Cf sources. The reference field for calibration includes scattered neutrons from the material surrounding sources, wall, floor and ceiling of the irradiation room. It is, therefore, necessary to evaluate the scattered neutrons contribution and their energy spectra at reference points. Spectral measurements were performed with a set of Bonner multi-sphere spectrometers and the reference fields were characterized in terms of spectral composition and the fractions of room-scattered neutrons. In addition, two techniques stated in ISO 10647, the shadow-cone method and the polynomial fit method, for correcting the contributions from the room-scattered neutrons to the readings of neutron survey instruments were compared. It was found that the two methods gave an equivalent result within a deviation of 3.3% at a source-to-detector distance from 50cm to 500cm. (author)

  6. The neutron field perturbation effect in the Dalat Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Huy, Ngo Quang [Centre for Nuclear Technique Application, Ho Chi Minh City (Viet Nam); Thong, Ha Van; Long, Vu Hai; Khang, Ngo Phu; Binh, Nguyen Duc; Tuan, Nguyen Minh; Vinh, Le Vinh [Nuclear Research Inst., Da Lat (Viet Nam)

    1994-10-01

    The perturbation effect of the thermal neutron field of the Dalat reactor is investigated when a fuel element is replaced by a water column or a plexiglass rod. In consequence, it is possible to replace the measurement of the relative distribution of the thermal neutron field on the surface of fuel element by that in the water column or in the plexiglass rod. (author). 5 refs. 4 figs. 4 tabs.

  7. Neutron spectrum determination by activation method in fast neutron fields at the RB reactor

    International Nuclear Information System (INIS)

    Sokcic-Kostic, M.; Pesic, M.; Antic, D.

    1994-01-01

    The fast neutron fields of the RB reactor are presented in this paper. The activation method for spectrum determination is described and explained. The obtained results for intermediate and fast spectrum are given and discussed. (author)

  8. Neutron spectrum determination by activation method in fast neutron fields at the RB reactors

    International Nuclear Information System (INIS)

    Sokcic-Kostic, M.S.; Pesic, M.P.; Antic, D.P.

    1994-01-01

    The fast neutron fields of the RB reactor are presented in this paper. The activation method for spectrum determination is described and explained. The obtained results for intermediate and fast spectrum are given and discussed. (authors). 7 refs., 3 tabs

  9. Local-field refinement of neutron scattering lengths

    Energy Technology Data Exchange (ETDEWEB)

    Sears, V F

    1985-06-01

    We examine the way in which local field effects in the neutron refractive index affect the values of coherent scattering lengths determined by various kinds of neutron optical measurements. We find that under typical experimental conditions these effects are negligible for interferometry measurements but that they are significant for gravity refractometry measurements, producing changes in the effective scattering length of as much as two or three standard deviations in some cases. Refined values of the scattering length are obtained for the thirteen elements for which data are presently available. The special role of local field effects in neutron transmission is also discussed.

  10. Local-field refinement of neutron scattering lengths

    International Nuclear Information System (INIS)

    Sears, V.F.

    1985-01-01

    We examine the way in which local field effects in the neutron refractive index affect the values of coherent scattering lengths determined by various kinds of neutron optical measurements. We find that under typical experimental conditions these effects are negligible for interferometry measurements but that they are significant for gravity refractometry measurements, producing changes in the effective scattering length of as much as two or three standard deviations in some cases. Refined values of the scattering length are obtained for the thirteen elements for which data are presently available. The special role of local field effects in neutron transmission is also discussed. (orig.)

  11. Irradiation test of HAFM and tag gas samples at the standard neutron field of 'YAYOI'

    International Nuclear Information System (INIS)

    Iguchi, Tetsuo

    1997-03-01

    To check the accuracy of helium accumulation neutron fluence monitors (HAFM) as new technique for fast reactor neutron dosimetry and the applicability of tag gas activation analysis to fast reactor failed fuel detection, their samples were irradiated at the standard neutron field of the fast neutron source reactor 'YAYOI' (Nuclear Engineering Research Laboratory, University of Tokyo). Since October in 1996, the HAFM samples such as 93% enriched boron (B) powders of 1 mg and natural B powders of 10 mg contained in vanadium (V) capsule were intermittently irradiated at the reactor core center (Glory hole: Gy) and/or under the leakage neutron field from the reactor core (Fast column: FC). In addition, new V capsules filled with enriched B of 40 mg and Be of 100 mg, respectively, were put into an experimental hole through the blanket surrounding the core. These neutron fields were monitored by the activation foils consisting of Fe, Co, Ni, Au, 235 U, 237 Np etc., mainly to confirm the results obtained from 1995's preliminary works. In particular, neutron flux distributions in the vicinity of irradiated samples were measured in more detail. At the end of March in 1997, the irradiated neutron fluence have reached the goal necessary to produce the detectable number of He atoms more than ∼10 13 in each HAFM sample. Six kinds of tag gas samples, which are the mixed gases of isotopically adjusted Xe and Kr contained in SUS capsules, were separately irradiated three times at Gy under the neutron fluence of ∼10 16 n/cm 2 in average. After irradiation, γ-ray spectra were measured for each sample. Depending on the composition of tag gas mixtures, the different patterns of γ-ray peak spectra from 79 Kr, 125 Xe, etc. produced through tag gas activation were able to be clearly identified. These experimental data will be very useful for the benchmark test of tag gas activation calculation applied to the fast reactor failed fuel detection. (author)

  12. Hematologic status of mice submitted to sublethal total body irradiation with mixed neutron-gamma radiation

    International Nuclear Information System (INIS)

    Herodin, F.; Court, L.

    1989-01-01

    The hematologic status of mice exposed to sublethal whole body irradiation with mixed neutron-gamma radiation (mainly neutrons) is studied. A slight decrease of the blood cell count is still observed below 1 Gy. The recovery of bone marrow granulocyte-macrophage progenitors seems to require more time than after pure gamma irradiation [fr

  13. Neutron radiation shielding properties of polymer incorporated self compacting concrete mixes.

    Science.gov (United States)

    Malkapur, Santhosh M; Divakar, L; Narasimhan, Mattur C; Karkera, Narayana B; Goverdhan, P; Sathian, V; Prasad, N K

    2017-07-01

    In this work, the neutron radiation shielding characteristics of a class of novel polymer-incorporated self-compacting concrete (PISCC) mixes are evaluated. Pulverized high density polyethylene (HDPE) material was used, at three different reference volumes, as a partial replacement to river sand in conventional concrete mixes. By such partial replacement of sand with polymer, additional hydrogen contents are incorporated in these concrete mixes and their effect on the neutron radiation shielding properties are studied. It has been observed from the initial set of experiments that there is a definite trend of reductions in the neutron flux and dose transmission factor values in these PISCC mixes vis-à-vis ordinary concrete mix. Also, the fact that quite similar enhanced shielding results are recorded even when reprocessed HDPE material is used in lieu of the virgin HDPE attracts further attention. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Relativistic mean field calculations in neutron-rich nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Gangopadhyay, G.; Bhattacharya, Madhubrata [Department of Physics, University of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata 700 009 (India); Roy, Subinit [Saha Institute of Nuclear Physics, Block AF, Sector 1, Kolkata- 700 064 (India)

    2014-08-14

    Relativistic mean field calculations have been employed to study neutron rich nuclei. The Lagrange's equations have been solved in the co-ordinate space. The effect of the continuum has been effectively taken into account through the method of resonant continuum. It is found that BCS approximation performs as well as a more involved Relativistic Continuum Hartree Bogoliubov approach. Calculations reveal the possibility of modification of magic numbers in neutron rich nuclei. Calculation for low energy proton scattering cross sections shows that the present approach reproduces the density in very light neutron rich nuclei.

  15. Intercomparison of radiation protection instrumentation in a pulsed neutron field

    Energy Technology Data Exchange (ETDEWEB)

    Caresana, M., E-mail: marco.caresana@polimi.it [Politecnico di Milano, CESNEF, Dipartimento di Energia, via Ponzio 34/3, 20133 Milano (Italy); Denker, A. [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, D-14109 Berlin (Germany); Esposito, A. [IFNF-LNF, FISMEL, via E. Fermi 40, 00044 Frascati (Italy); Ferrarini, M. [CNAO, Via Privata Campeggi, 27100 Pavia (Italy); Golnik, N. [Institute of Metrology and Biomedical Engineering, Warsaw University of Technology, Sw. A. Boboli 8, 02-525 Warsaw (Poland); Hohmann, E. [Paul Scherrer Institut (PSI), Radiation Metrology Section, CH-5232 Villigen PSI (Switzerland); Leuschner, A. [Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22603 Hamburg (Germany); Luszik-Bhadra, M. [Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig (Germany); Manessi, G. [CERN, 1211 Geneva 23 (Switzerland); University of Liverpool, Department of Physics, L69 7ZE Liverpool (United Kingdom); Mayer, S. [Paul Scherrer Institut (PSI), Radiation Metrology Section, CH-5232 Villigen PSI (Switzerland); Ott, K. [Helmholtz-Zentrum Berlin, BESSYII, Albert-Einstein-Str.15, 12489 Berlin (Germany); Röhrich, J. [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, D-14109 Berlin (Germany); Silari, M. [CERN, 1211 Geneva 23 (Switzerland); Trompier, F. [Institute for Radiological Protection and Nuclear Safety, F-92262 Fontenay aux Roses (France); Volnhals, M.; Wielunski, M. [Helmholtz Zentrum München, Ingolstädter Landstr. 1, D-85764 Neuherberg (Germany)

    2014-02-11

    In the framework of the EURADOS working group 11, an intercomparison of active neutron survey meters was performed in a pulsed neutron field (PNF). The aim of the exercise was to evaluate the performances of various neutron instruments, including commercially available rem-counters, personal dosemeters and instrument prototypes. The measurements took place at the cyclotron of the Helmholtz-Zentrum Berlin für Materialien und Energie GmbH. The cyclotron is routinely used for proton therapy of ocular tumours, but an experimental area is also available. For the therapy the machine accelerates protons to 68 MeV. The interaction of the proton beam with a thick tungsten target produces a neutron field with energy up to about 60 MeV. One interesting feature of the cyclotron is that the beam can be delivered in bursts, with the possibility to modify in a simple and flexible way the burst length and the ion current. Through this possibility one can obtain radiation bursts of variable duration and intensity. All instruments were placed in a reference position and irradiated with neutrons delivered in bursts of different intensity. The analysis of the instrument response as a function of the burst charge (the total electric charge of the protons in the burst shot onto the tungsten target) permitted to assess for each device the dose underestimation due to the time structure of the radiation field. The personal neutron dosemeters were exposed on a standard PMMA slab phantom and the response linearity was evaluated.

  16. Reaction-in-flight neutrons as a signature for shell mixing in National Ignition Facility capsules

    International Nuclear Information System (INIS)

    Hayes, A. C.; Bradley, P. A.; Grim, G. P.; Jungman, Gerard; Wilhelmy, J. B.

    2010-01-01

    Analytic calculations and results from computational simulations are presented that suggest that reaction-in-flight (RIF) neutrons can be used to diagnose mixing of the ablator shell material into the fuel in deuterium-tritium (DT) capsules designed for the National Ignition Facility (NIF) [J. A. Paisner, J. D. Boyes, S. A. Kumpan, W. H. Lowdermilk, and M. S. Sorem, Laser Focus World 30, 75 (1994)]. Such mixing processes in NIF capsules are of fundamental physical interest and can have important effects on capsule performance, quenching the total thermonuclear yield. The sensitivity of RIF neutrons to hydrodynamical mixing arises through the dependence of RIF production on charged-particle stopping lengths in the mixture of DT fuel and ablator material. Since the stopping power in the plasma is a sensitive function of the electron temperature and density, it is also sensitive to mix. RIF production scales approximately inversely with the degree of mixing taking place, and the ratio of RIF to down-scattered neutrons provides a measure of the mix fraction and/or the mixing length. For sufficiently high-yield capsules, where spatially resolved RIF images may be possible, neutron imaging could be used to map RIF images into detailed mix images.

  17. Calibration of a special neutron dosemeter based on solid-state track detectors and fission radiators in various neutron fields

    International Nuclear Information System (INIS)

    Doerschel, B.; Krusche, M.; Schuricht, V.

    1980-01-01

    The calibration of a personnel neutron dosemeter in different neutron fields is described. The badge-like dosemeter contains 5 detectors: polycarbonate foil (10 μm, Makrofol KG), 232 Th, natural uranium, natural uranium with boron, and natural uranium with cadmium. Detector sensitivity and calibration factors have been calculated and measured in radiation fields of 252 Cf fission neutrons, WWR-S reactor neutrons with and without Cd and Fe shielding, 3-MeV (d,t) generator neutrons, and 238 PuBe neutrons. Measurement range and achievable accuracy are discussed from the point of view of applying the dosemeter in routine and emergency uses

  18. Neutron Reference Benchmark Field Specification: ACRR Free-Field Environment (ACRR-FF-CC-32-CL).

    Energy Technology Data Exchange (ETDEWEB)

    Vega, Richard Manuel [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Parma, Edward J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Griffin, Patrick J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Vehar, David W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-07-01

    This report was put together to support the International Atomic Energy Agency (IAEA) REAL- 2016 activity to validate the dosimetry community’s ability to use a consistent set of activation data and to derive consistent spectral characterizations. The report captures details of integral measurements taken in the Annular Core Research Reactor (ACRR) central cavity free-field reference neutron benchmark field. The field is described and an “a priori” calculated neutron spectrum is reported, based on MCNP6 calculations, and a subject matter expert (SME) based covariance matrix is given for this “a priori” spectrum. The results of 31 integral dosimetry measurements in the neutron field are reported.

  19. An active pixels spectrometers for neutronic fields metrology

    International Nuclear Information System (INIS)

    Taforeau, Julien

    2013-01-01

    The fundamental metrology is responsible for the sustainability of the measurement systems and handles to supply the reference standards. Concerning the metrology of ionizing radiations and, in particular the neutron metrology, detectors standards are used to characterize reference fields, in terms of energy and fluence. The dosimeters or particle detectors are calibrated on these reference fields. This thesis presents the development of a neutron spectrometer neutron candidate to the status of primary standard for the characterization of neutron fields in the range from 5 to 20 MeV. The spectrometer uses the recoil proton telescope as detection principle; the CMOS technology, through three sensor positions, is taking advantage to realize the tracking of protons. A Si(Li) detector handles the measure of the residual proton energy. The device simulations, realized under MCNPX, allow to estimate its performances and to validate the neutron energy reconstruction. An essential step of characterization of the telescope elements and in particular of CMOS sensors is also proposed to guarantee the validity of posterior experimental measurements. The tests realized as well in mono-energy fields as in radionuclide source show the very good performances of the system. The quantification of uncertainties indicates an energy estimation with 1.5 % accuracy and a resolution of less than 6 %. The fluence measurement is performed with an uncertainty about 4 to 6%. (author)

  20. A design study on hyper-thermal neutron irradiation field for neutron capture therapy at Kyoto University Reactor

    International Nuclear Information System (INIS)

    Sakurai, Y.; Kobayashi, T.

    2000-01-01

    A study about the installation of a hyper-thermal neutron converter to a clinical collimator was performed, as a series of the design study on a hyper-thermal neutron irradiation field at the Heavy Water Neutron Irradiation Facility of Kyoto University Reactor. From the parametric-surveys by Monte Carlo calculation, it was confirmed that the practical irradiation field of hyper-thermal neutrons would be feasible by the modifications of the clinical collimator and the bismuth-layer structure. (author)

  1. Mixed field dosimetry in the FRN exposure-room

    International Nuclear Information System (INIS)

    Jentzsch, U.

    1976-01-01

    The twin ionization chamber technique, chemical dosimeter systems and silicon diodes have been used to determine the neutron and gamma components of the reactor field in the FRN exposure-room. The knowledge of these components are of fundamental importance for irradiation experiments in the biological research program started at the FRN. The chemical systems and silicon diodes have the advantage of low cost and simple handling. Furthermore, silicon diodes have negligible gamma response and the shift of neutron response with variation of neutron energy spectrum is small. The results of measurements with the different methods have been compared and discussed. (author)

  2. Determination of two- and three-dimensional radiation fields for neutron radiotherapy planning

    International Nuclear Information System (INIS)

    Boehm, J.K.

    1986-01-01

    The thesis deals with the computerized investigations for fast neutron radiotherapy planning, explaining the calculation and modelling of local dose distributions in patients as a result of mixed neutron and gamma radiation fields. For a computed irradiation program (elaborated for instance by the COMRAD program system), dose distribution functions are required for the simulation of multi-field or moving beam irradiations, the functions being derived semi-empirically by non-linear regression. The necessary data on stationary field doses are derived by measurements or by computed simulation with specific transport programs from the nuclear engineering sector. Transport calculations show the effects of inhomogeneities in the patient's body on the dose distribution. The determined, strong inhomogneity effects (lungs, head) have to be taken into account as precisely as possible in order to achieve optimum irradiation planning. (orig./HP) [de

  3. The Covariance and Bicovariance of the Stochastic Neutron Field

    International Nuclear Information System (INIS)

    Perez, R.B.; Mattingly, J.K.; Valentine, T.E.; Mihalczo, J.T.

    2000-01-01

    On the basis of the general stochastic neutron field theory developed by Munoz-Cobo et al, results on the covariance and bicovariance of the neutron field have been presented. These two statistical quantities are obtained from the counts observed in detectors operating during a period of time (gate length), Δ qc . A classical example is the so called Feynmann Y-function that is defined as the variance to mean ratio of the neutron field. Upon taking the limit of the covariance and bicovariance function for Δ qc r a rrow O , one obtains the two and three detector cross correlation functions respectively. The mathematical structure of the results so obtained have a transparent physical interpretation in terms of the space and delay time overlap between the field-of-view of the detectors. For the first time, an expression has been obtained for the bispectrum function of the stochastic neutron field and for the appropriate weight functions to be used as space-energy-angle correction factors for the one-point kinetics approximation

  4. A neutron spin echo spectrometer with two optimal field shape coils for neutron spin precession

    International Nuclear Information System (INIS)

    Takeda, T.; Ebisawa, T.; Tasaki, S.; Ito, Y.; Takahashi, S.; Yoshizawa, H.

    1995-01-01

    We have designed and have been constructing at the C 2-2 cold neutron guide port of JRR-3M, JAERI, a neutron spin echo spectrometer (NSE) which is equipped with two optimal field shape (OFS) coils for neutron spin precession with the maximum field integral of 0.22 T m, an assembly of position sensitive detectors (PSD), a converging polarizer and a wide area analyzer. The dynamic range of scattering vector Q covers from 0.005 A -1 to 0.2 A -1 and that of energy hω from 10 neV to 30 μeV. Performance tests of the OFS coils show that the inhomogeneity of the magnetic field integral in the OFS coils with the spiral coils is so small that the NSE signal amplitude decreases little even for the neutron cross section of 30 mm diameter as the Fourier time t increases up to 25 ns, though the precession coils are close to iron covers of the neighboring neutron guide. This verifies that the OFS precession coils are appropriate for this NSE spectrometer. Another test experiment shows that the homogeneity condition of the precession magnet is loosened by use of PSD. (orig.)

  5. Field calibration of a TLD albedo dosemeter in the high-energy neutron field of CERF

    International Nuclear Information System (INIS)

    Haninger, T.; Kleinau, P.; Haninger, S.

    2017-01-01

    The new albedo dosemeter-type AWST-TL-GD 04 has been calibrated in the CERF neutron field (CERN-EU high-energy Reference Field). This type of albedo dosemeter is based on thermoluminescent detectors (TLDs) and used by the individual monitoring service of the Helmholtz Zentrum Muenchen (AWST) since 2015 for monitoring persons, who are exposed occupationally against photon and neutron radiation. The motivation for this experiment was to gain a field specific neutron correction factor N n for workplaces at high-energy particle accelerators. N n is a dimensionless factor relative to a basic detector calibration with 137 Cs and is used to calculate the personal neutron dose in terms of H p (10) from the neutron albedo signal. The results show that the sensitivity of the albedo dosemeter for this specific neutron field is not significantly lower as for fast neutrons of a radionuclide source like 252 Cf. The neutron correction factor varies between 0.73 and 1.16 with a midrange value of 0.94. The albedo dosemeter is therefore appropriate to monitor persons, which are exposed at high-energy particle accelerators. (authors)

  6. Field neutron spectrometer using 3He, TEPC, and multisphere detectors

    International Nuclear Information System (INIS)

    Brackenbush, L.W.

    1991-01-01

    Since the last DOE Neutron Dosimetry Workshop, there have been a number of changes in radiation protection standards proposed by national and international advisory bodies. These changes include: increasing quality factors for neutrons by a factor of two, defining quality factors as a function of lineal energy rather than linear energy transfer (see ACCRUE-40; Joint Task Group 1986), and adoption of effective dose equivalent methodologies. In order to determine the effects of these proposed changes, it is necessary to know the neutron energy spectrum in the work place. In response to the possible adoption of these proposals, the Department of Energy (DOE) initiated a program to develop practical neutron spectrometry systems for use by health physicists. One part of this program was the development of a truly portable, battery operated liquid scintillator spectrometer using proprietary electronics developed at Lawrence Livermore National Laboratory (LLNL); this instrument will be described in the following paper. The second part was the development at PNL of a simple transportable spectrometer based on commercially available electronics. This open-quotes field neutron spectrometerclose quotes described in this paper is intended to be used over a range of neutron energies extending from thermal to 20 MeV

  7. Average cross sections calculated in various neutron fields

    International Nuclear Information System (INIS)

    Shibata, Keiichi

    2002-01-01

    Average cross sections have been calculated for the reactions contained in the dosimetry files, JENDL/D-99, IRDF-90V2, and RRDF-98 in order to select the best data for the new library IRDF-2002. The neutron spectra used in the calculations are as follows: 1) 252 Cf spontaneous fission spectrum (NBS evaluation), 2) 235 U thermal fission spectrum (NBS evaluation), 3) Intermediate-energy Standard Neutron Field (ISNF), 4) Coupled Fast Reactivity Measurement Facility (CFRMF), 5) Coupled thermal/fast uranium and boron carbide spherical assembly (ΣΣ), 6) Fast neutron source reactor (YAYOI), 7) Experimental fast reactor (JOYO), 8) Japan Material Testing Reactor (JMTR), 9) d-Li neutron spectrum with a 2-MeV deuteron beam. The items 3)-7) represent fast neutron spectra, while JMTR is a light water reactor. The Q-value for the d-Li reaction mentioned above is 15.02 MeV. Therefore, neutrons with energies up to 17 MeV can be produced in the d-Li reaction. The calculated average cross sections were compared with the measurements. Figures 1-9 show the ratios of the calculations to the experimental data which are given. It is found from these figures that the 58 Fe(n, γ) cross section in JENDL/D-99 reproduces the measurements in the thermal and fast reactor spectra better than that in IRDF-90V2. (author)

  8. Small angle neutron scattering studies of mixed micelles of sodium

    Indian Academy of Sciences (India)

    The aqueous solutions of sodium cumene sulphonate (NaCS) and its mixtures with each of cetyl trimethylammonium bromide (CTAB) and sodium dodecyl sulphate (SDS) are characterized by small angle neutron scattering (SANS). NaCS when added to CTAB solution leads to the formation of long rod-shaped micelles with ...

  9. A compact neutron generator using a field ionization source.

    Science.gov (United States)

    Persaud, Arun; Waldmann, Ole; Kapadia, Rehan; Takei, Kuniharu; Javey, Ali; Schenkel, Thomas

    2012-02-01

    Field ionization as a means to create ions for compact and rugged neutron sources is pursued. Arrays of carbon nano-fibers promise the high field-enhancement factors required for efficient field ionization. We report on the fabrication of arrays of field emitters with a density up to 10(6) tips∕cm(2) and measure their performance characteristics using electron field emission. The critical issue of uniformity is discussed, as are efforts towards coating the nano-fibers to enhance their lifetime and surface properties.

  10. Inelastic neutron scattering on a mixed-valence dodecanuclear polyoxovanadate cluster

    CERN Document Server

    Basler, R; Andrés, H; Güdel, H U; Koegerler, P; Krickemeier, E; Bögge, H; Müller, A; Mutka, H

    2002-01-01

    The magnetic exchange interactions in the mixed-valence dodecanuclear polyoxovanadate cluster compound (NHEt sub 3) sub 4 [V sub 1 sub 2 As sub 8 O sub 4 sub 0 (H sub 2 O)] x H sub 2 O were investigated by a detailed inelastic neutron scattering study using cold neutrons. The data show clear evidence for the presence of a magnetic anisotropy within the cluster. Exchange parameters are accurately determined. (orig.)

  11. Shape coexistence in the neutron-deficient Pt isotopes in a configuration mixing IBM

    International Nuclear Information System (INIS)

    Morales, Irving O.; Vargas, Carlos E.; Frank, Alejandro

    2004-01-01

    The recently proposed matrix-coherent state approach for configuration mixing IBM is used to describe the evolving geometry of the neutron deficient Pt isotopes. It is found that the Potential Energy Surface (PES) of the Platinum isotopes evolves, when the number of neutrons decreases, from spherical to oblate and then to prolate shapes, in agreement with experimental measurements. Oblate-Prolate shape coexistence is observed in 194,192Pt isotopes

  12. Three Dimensional Polarimetric Neutron Tomography of Magnetic Fields

    DEFF Research Database (Denmark)

    Sales, Morten; Strobl, Markus; Shinohara, Takenao

    2018-01-01

    Through the use of Time-of-Flight Three Dimensional Polarimetric Neutron Tomography (ToF 3DPNT) we have for the first time successfully demonstrated a technique capable of measuring and reconstructing three dimensional magnetic field strengths and directions unobtrusively and non-destructively wi......Through the use of Time-of-Flight Three Dimensional Polarimetric Neutron Tomography (ToF 3DPNT) we have for the first time successfully demonstrated a technique capable of measuring and reconstructing three dimensional magnetic field strengths and directions unobtrusively and non...... and reconstructed, thereby providing the proof-of-principle of a technique able to reveal hitherto unobtainable information on the magnetic fields in the bulk of materials and devices, due to a high degree of penetration into many materials, including metals, and the sensitivity of neutron polarisation to magnetic...... fields. The technique puts the potential of the ToF time structure of pulsed neutron sources to full use in order to optimise the recorded information quality and reduce measurement time....

  13. Quantum States of Neutron in Earth's Gravitational Field

    Indian Academy of Sciences (India)

    Keywords. Neutron; gravitational field; Bohr-Sommerfeld-Wilson quantization; projectile motion; elastic collision; Olympiad. Author Affiliations. Vijay A Singh1 Praveen Pathak1 K Krishna Chaitanya2. Homi Bhabha Centre For Science Education (TIFR), V N Purav Marg, Mankhurd Mumbai 400088, India. Physics Department ...

  14. A device for quantitative plutonium testing in mixed fuel by its neutron emission

    International Nuclear Information System (INIS)

    Gadzhiev, G.I.; Gorobets, A.K.; Golushko, V.V.; Dunaev, E.S.; Leshchenko, Yu.I.

    1987-01-01

    A device for quantitative plutonium testing in mixed fuel by its neutron emission is described. The method of ''assigned dead time'' for isolation of neutrons of spontaneous fission is used in the device. The main characteristics of the registrating equipment specifying the regime of measuring and affecting testing errors are presented. The results of spontaneous fission neutrons detection in the range up to 100 g of plutonium linearly depend on 240 Pu. Sensitivity of testing makes up about 28 pul./s per 1 g of 240 Pu

  15. Assessment of the neutron component in a neutron-gamma field of a californium-252 source

    International Nuclear Information System (INIS)

    Tetteh, G.K.

    1978-12-01

    Experiments have been performed to determine the percentages of the different components in the radiation field of californium-252 which has now some clinical applications. Using Rossi Chambers in conjunction with absorption investigations involving lead and aluminium thimbles, it is observed that the dose rates due to the different components are: neutrons 54%; gammas 30%; betas 16%

  16. Synergistic effect of mixed neutron and gamma irradiation in bipolar operational amplifier OP07

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Liu, E-mail: liuyan@nint.ac.cn [State Key Laboratory of Intense Pulsed Irradiation Simulation and Effect, Northwest Institute of Nuclear Technology, P.O.Box 69-10, Xi’an 710024 (China); School of Nuclear Science and Technology, Xi’an Jiaotong University, Xi’an 710049 (China); Wei, Chen; Shanchao, Yang; Xiaoming, Jin [State Key Laboratory of Intense Pulsed Irradiation Simulation and Effect, Northwest Institute of Nuclear Technology, P.O.Box 69-10, Xi’an 710024 (China); Chaohui, He [School of Nuclear Science and Technology, Xi’an Jiaotong University, Xi’an 710049 (China)

    2016-09-21

    This paper presents the synergistic effects in bipolar operational amplifier OP07. The radiation effects are studied by neutron beam, gamma ray, and mixed neutron/gamma ray environments. The characterateristics of the synergistic effects are studied through comparison of different experiment results. The results show that the bipolar operational amplifier OP07 exhibited significant synergistic effects in the mixed neutron and gamma irradiation. The bipolar transistor is identified as the most radiation sensitive unit of the operational amplifier. In this paper, a series of simulations are performed on bipolar transistors in different radiation environments. In the theoretical simulation, the geometric model and calculations based on the Medici toolkit are built to study the radiation effects in bipolar components. The effect of mixed neutron and gamma irradiation is simulated based on the understanding of the underlying mechanisms of radiation effects in bipolar transistors. The simulated results agree well with the experimental data. The results of the experiments and simulation indicate that the radiation effects in the bipolar devices subjected to mixed neutron and gamma environments is not a simple combination of total ionizing dose (TID) effects and displacement damage. The data suggests that the TID effect could enhance the displacement damage. The synergistic effect should not be neglected in complex radiation environments.

  17. A technique for determining fast and thermal neutron flux densities in intense high-energy (8-30 MeV) photon fields

    International Nuclear Information System (INIS)

    Price, K.W.; Holeman, G.R.; Nath, R.

    1978-01-01

    A technique for measuring fast and thermal neutron fluxes in intense high-energy photon fields has been developed. Samples of phorphorous pentoxide are exposed to a mixed photon-neutron field. The irradiated samples are then dissolved in distilled water and their activation products are counted in a liquid scintillation spectrometer at 95-97% efficiency. The radioactive decay characteristics of the samples are then analyzed to determine fast and thermal neutron fluxes. Sensitivity of this neutron detector to high energy photons has been measured and found to be small. (author)

  18. Magnetic field effects on the crust structure of neutron stars

    Science.gov (United States)

    Franzon, B.; Negreiros, R.; Schramm, S.

    2017-12-01

    We study the effects of high magnetic fields on the structure and on the geometry of the crust in neutron stars. We find that the crust geometry is substantially modified by the magnetic field inside the star. We build stationary and axis-symmetric magnetized stellar models by using well-known equations of state to describe the neutron star crust, namely, the Skyrme model for the inner crust and the Baym-Pethick-Sutherland equation of state for the outer crust. We show that the magnetic field has a dual role, contributing to the crust deformation via the electromagnetic interaction (manifested in this case as the Lorentz force) and by contributing to curvature due to the energy stored in it. We also study a direct consequence of the crust deformation due to the magnetic field: the thermal relaxation time. This quantity, which is of great importance to the thermal evolution of neutron stars, is sensitive to the crust properties, and, as such, we show that it may be strongly affected by the magnetic field.

  19. The theory of neutron scattering from mixed harmonic solids

    International Nuclear Information System (INIS)

    Warner, M.; Lovesey, S.W.; Smith, J.

    1982-12-01

    The dynamic structure factor for incoherent neutron scattering from light mass particles substituted in a solid is calculated for two model systems. One model is appropriate for a dilute concentration of light particles in a matrix, and the second is a binary system with various masses and force constants. The exact calculations are used to assess the value of approximation schemes for the dynamic structure factor which exploit the separation of time scales in the motions of the light and the heavier lattice particles. (author)

  20. The effect of mixed fractionation with X rays and neutrons on tumour growth delay and skin reactions in mice

    International Nuclear Information System (INIS)

    Carl, U.M.

    1987-01-01

    The authors have compared the effects of mixed fractionation schedules with X rays and neutrons on growth delay of a murine tumour and skin reactions in mice. The schedules were five daily fractions of X rays, neutrons or mixtures (NNXXX, XXXNN or NXXXN). For clamped tumours or skin all three mixed schedules had the same effect. In contrast, for unclamped tumours giving the neutrons first (NNXXX) was more effective than the other two mixed schedules. This represented a true therapeutic gain and implies that if neutrons are used clinically as only part of a course of fractionated radiotherapy, they should be given at the beginning rather than at the end of treatment. (author)

  1. Design of hyper-thermal neutron irradiation fields for neutron capture therapy in KUR-heavy water neutron irradiation facility. Mounting of hyper-thermal neutron converter in therapeutic collimator

    International Nuclear Information System (INIS)

    Sakurai, Y.; Kobayashi, T.

    2001-01-01

    Neutron capture therapy (NCP) using thermal neutron needs to improve of depth dose distribution in a living body. Epi-thermal neutron following moderation of fast neutron is usually used for improving of the depth dose distribution. The moderation method of fast neutron, however, gets mixed some of high energy neutron which give some of serious effects to a living body, and involves the difficulty for collimation of thermal neutron to the diseased part. Hyper-thermal neutrons, which are in an energy range of 0.1-3 eV at high temperature side of thermal neutron, are under consideration for application to the NCP. The hyper-thermal neutrons can be produced by up-scattering of thermal neutron in a high temperature material. Fast neutron components in collimator for the NCP reduce on application of the up-scattering method. Graphite at high temperature (>1000k) is used as a hyper-thermal neutron converter. The hyper-thermal neutron converter is planted to mount on therapeutic collimator which is located at the nearest side of patient for the NCP. Total neutron flux, ratio of hyper-thermal neutron to total neutron, and ratio of gamma-ray dose to neutron flux are calculated as a function of thickness of the graphite converter using monte carlo code MCNP-V4B. (M. Suetake)

  2. Characterisation of neutron fields: challenges in assessing the directional distribution

    International Nuclear Information System (INIS)

    Cauwels, Vanessa; Vanhavere, Filip; Reginatto, Marcel

    2014-01-01

    The SCK.CEN has carried out neutron field characterisation campaigns at several nuclear reactors. The main goal of these measurement campaigns was to evaluate the performance of different neutron personal dosemeters. To be able to evaluate the performance of neutron personal dosemeters in terms of H p (10), knowledge of the directional distribution is indispensable. This distribution was estimated by placing several personal dosemeters on all six sides of a slab phantom. The interpretation and conversion of this information into a reliable value for H p (10) requires great care. The data were analysed using three methods. In the first approach, a linear interpolation was performed on three perpendicular axes. In the other two approaches, an icosahedron was used to model the angle of incidence of the neutrons and a linear interpolation or a Bayesian analysis was performed. This study describes the limitations and advantages of each of these methods and provides recommendations for their use to estimate the personal dose equivalent H p (10) for neutron dosimetry. Neutron personal dosimetry is complicated by the fact that the neutron dose quantity H p (10) is strongly energy and angular dependent. Instead of simply assuming that the fluence is unidirectional or that the fluence is isotropic, an attempt was made to estimate the directional distribution of the neutron field using a relatively simple measurement procedure. A number of active and passive personal dosemeters were placed on the six faces of a slab phantom and the results were analysed via different algorithms to obtain partial fluences in several directions of incidence. The results from all calculations in this study show the importance of introducing information about the directional distribution of the neutron fluence for the estimation of the personal dose equivalent H p (10). The difference between H p (10) dose estimates carried out using a unidirectional or an isotropic distribution can be of up

  3. The PTB thermal neutron reference field at GeNF

    International Nuclear Information System (INIS)

    Boettger, R.; Friedrich, H.; Janssen, H.

    2004-01-01

    The experimental setup and procedure for the characterization of the thermal neutron reference field established at the Geesthacht neutron facility (GeNF) of the GKSS is described. The neutron beam, free in air, with a maximum flux of 10 6 s -1 , can easily be reduced to less than 10 4 s -1 by using a diaphragm variable in size and without changing the beam divergence. Also, the spectral distribution with a mean energy of 45 meV, measured by time-of-flight over a 6.6 m long flight path, is independent of the beam current chosen. In the 2002/2003 experiments reported here, a 6 Li glass detector was employed to determine the absolute beam current and to calibrate the 3 He transmission beam monitor. In addition, activation measurements of gold foils were carried out at a reduced beam divergence. The results agree within ±2%. Furthermore, the beam is characterized by a low gamma background intensity and a negligible fraction of epithermal neutrons. Irradiations in combination with a scanner device to achieve a homogeneously illuminated scan field have shown that the thermal beam is well suited for dosemeter development and for the calibration of radiation protection instruments. (orig.)

  4. Intercomparison of radiation protection instrumentation in a pulsed neutron field

    CERN Document Server

    Caresana, M; Esposito, A; Ferrarini, M; Golnik, N; Hohmann, E; Leuschner, A; Luszik-Bhadra, M; Manessi, G; Mayer, S; Ott, K; Röhrich, J; Silari, M; Trompier, F; Volnhals, M; Wielunski, M

    2014-01-01

    In the framework of the EURADOS working group 11, an intercomparison of active neutron survey meters was performed in a pulsed neutron field (PNF). The aim of the exercise was to evaluate the performances of various neutron instruments, including commercially available rem-counters, personal dosemeters and instrument prototypes. The measurements took place at the cyclotron of the Helmholtz-Zentrum Berlin für Materialien und Energie GmbH. The cyclotron is routinely used for proton therapy of ocular tumours, but an experimental area is also available. For the therapy the machine accelerates protons to 68 MeV. The interaction of the proton beam with a thick tungsten target produces a neutron field with energy up to about 60 MeV. One interesting feature of the cyclotron is that the beam can be delivered in bursts, with the possibility to modify in a simple and flexible way the burst length and the ion current. Through this possibility one can obtain radiation bursts of variable duration and intensity. All instru...

  5. The PTB thermal neutron reference field at GeNF

    Energy Technology Data Exchange (ETDEWEB)

    Boettger, R.; Friedrich, H.; Janssen, H.

    2004-07-01

    The experimental setup and procedure for the characterization of the thermal neutron reference field established at the Geesthacht neutron facility (GeNF) of the GKSS is described. The neutron beam, free in air, with a maximum flux of 10{sup 6} s{sup -1}, can easily be reduced to less than 10{sup 4} s{sup -1} by using a diaphragm variable in size and without changing the beam divergence. Also, the spectral distribution with a mean energy of 45 meV, measured by time-of-flight over a 6.6 m long flight path, is independent of the beam current chosen. In the 2002/2003 experiments reported here, a {sup 6}Li glass detector was employed to determine the absolute beam current and to calibrate the {sup 3}He transmission beam monitor. In addition, activation measurements of gold foils were carried out at a reduced beam divergence. The results agree within {+-}2%. Furthermore, the beam is characterized by a low gamma background intensity and a negligible fraction of epithermal neutrons. Irradiations in combination with a scanner device to achieve a homogeneously illuminated scan field have shown that the thermal beam is well suited for dosemeter development and for the calibration of radiation protection instruments. (orig.)

  6. Review of microscopic integral cross section data in fundamental reactor dosimetry benchmark neutron fields

    International Nuclear Information System (INIS)

    Fabry, A.; McElroy, W.N.; Kellogg, L.S.; Lippincott, E.P.; Grundl, J.A.; Gilliam, D.M.; Hansen, G.E.

    1976-01-01

    This paper is intended to review and critically discuss microscopic integral cross section measurement and calculation data for fundamental reactor dosimetry benchmark neutron fields. Specifically the review covers the following fundamental benchmarks: the spontaneous californium-252 fission neutron spectrum standard field; the thermal-neutron induced uranium-235 fission neutron spectrum standard field; the (secondary) intermediate-energy standard neutron field at the center of the Mol-ΣΣ, NISUS, and ITN-ΣΣ facilities; the reference neutron field at the center of the Coupled Fast Reactor Measurement Facility; the reference neutron field at the center of the 10% enriched uranium metal, cylindrical, fast critical; the (primary) Intermediate-Energy Standard Neutron Field

  7. Review of microscopic integral cross section data in fundamental reactor dosimetry benchmark neutron fields

    International Nuclear Information System (INIS)

    Fabry, A.; McElroy, W.N.; Kellogg, L.S.; Lippincott, E.P.; Grundl, J.A.; Gilliam, D.M.; Hansen, G.E.

    1976-10-01

    The paper is intended to review and critically discuss microscopic integral cross section measurement and calculation data for fundamental reactor dosimetry benchmark neutron fields. Specifically the review covers the following fundamental benchmarks: (1) the spontaneous californium-252 fission neutron spectrum standard field; (2) the thermal-neutron induced uranium-235 fission neutron spectrum standard field; (3) the (secondary) intermediate-energy standard neutron field at the center of the Mol-ΣΣ, NISUS, and ITN--ΣΣ facilities; (4) the reference neutron field at the center of the Coupled Fast Reactor Measurement Facility (CFRMF); (5) the reference neutron field at the center of the 10 percent enriched uranium metal, cylindrical, fast critical; and (6) the (primary) Intermediate-Energy Standard Neutron Field

  8. Crystalline structure in the confined-deconfined mixed phase: Neutron stars as an example

    International Nuclear Information System (INIS)

    Glendenning, N.K.

    1996-01-01

    We review the differences in first order phase transition of single and multi-component systems, and then discuss the crystalline structure expected to exist in the mixed confined deconfined phase of hadronic matter. The particular context of neutron stars is chosen for illustration. The qualitative results are general and apply for example to the vapor-liquid transition in subsaturated asymmetric nuclear matter

  9. Shape coexistence in the neutron-deficient Pt isotopes in the configuration-mixed IBM

    International Nuclear Information System (INIS)

    Vargas, Carlos E.; Campuzano, Cuauhtemoc; Morales, Irving O.; Frank, Alejandro; Van Isacker, Piet

    2008-01-01

    The matrix-coherent state approach in the IBM with configuration mixing is used to describe the geometry of neutron-deficient Pt isotopes. Employing a parameter set for all isotopes determined previously, it is found that the lowest minimum goes from spherical to oblate and finally acquires a prolate shape when approaching the mid-shell Pt isotopes

  10. Long distance propagation of a polarized neutron beam in zero magnetic field

    International Nuclear Information System (INIS)

    Schmidt, U.; Bitter, T.; El-Muzeini, P.

    1992-01-01

    A beam of fully polarized cold neutrons was transported through a zero magnetic field region of 70 m length without loss of polarization. The purpose of this exercise was twofold: Firstly, to demonstrate that the new zero-field neutron spin-echo method will work also for very long neutron flight paths; secondly, to prove in the most direct way that the neutron free-flight region of the ILL neutron-antineutron oscillation experiment was indeed sufficiently field-free ('quasifree condition') by using the neutrons themselves as a magnetometer. To this purpose the residual magnetic field integrals in the long 'zero-field' region were measured with a conventional neutron spin-echo method. The overall spin precession angle of the neutrons during their flight through the long zero-field region was found to be less than 2 0 . (orig.)

  11. Naturalness in an Effective Field Theory for Neutron Star Matter

    International Nuclear Information System (INIS)

    Razeira, Moises; Vasconcellos, Cesar A.Z.; Bodmann, Bardo E.J.; Coelho, Helio T.; Dillig, Manfred

    2004-01-01

    High density hadronic matter is studied in a generalized relativistic multi-baryon lagrangian density. By comparing the predictions of our model with estimates obtained within a phenomenological naive dimensional analysis based on the naturalness of the coefficients of the theory, we show that naturalness plays a major role in effective field theory and, in combination with experiment, could represent a relevant criterium to select a model among others in the description of global static properties of neutron stars

  12. Performance degradation of ferrofluidic feedthroughs in a mixed irradiation field

    Science.gov (United States)

    Simos, Nikolaos; Fernandes, S.; Mittig, Wolfgang; Pellemoine, Frederique; Avilov, M.; Kostin, M.; Mausner, L.; Ronningen, R.; Schein, M.; Bollen, G.

    2017-01-01

    Ferrofluidic feedthrough (FF) rotary seals containing either NdFeB or SmCo-type permanent magnets have been considered for use in the target and beam dump systems of the Facility for Rare Isotope Beams (FRIB). To evaluate their performance under irradiation three FF seals were irradiated in a mixed field consisting of fast neutrons, protons and γ-rays to an average absorbed dose of 0.2, 2.0, and 20.0 MGy at the Brookhaven Linac Isotope Producer facility (BLIP). The radiation types and energy profiles mimic those expected at the FRIB facility. Degradation of the operational performance of these devices due to irradiation is expected to be the result of the de-magnetization of the permanent magnets contained within the seal and the changes in the ferrofluid properties. Post-irradiation performance was evaluated by determining the ferrofluidic seal vacuum tightness and torque under static and dynamic conditions. The study revealed that the ferrofluidic feedthrough seal irradiated to a dose of 0.2 MGy maintained its vacuum tightness under both static and rotational condition while the one irradiated to a dose of 2.0 MGy exhibited signs of ferrofluid damage but no overall performance loss. At 20 MGy dose the effects of irradiation on the ferrofluid properties (viscosity and particle agglomeration) were shown to be severe. Furthermore, limited de-magnetization of the annular shaped Nd2Fe14B and Sm2Co17 magnets located within the irradiated FFs was observed for doses of 0.2 MGy and 20 MGy respectively.

  13. Mixed-symmetry fields in AdS(5), conformal fields, and AdS/CFT

    Energy Technology Data Exchange (ETDEWEB)

    Metsaev, R.R. [Department of Theoretical Physics, P.N. Lebedev Physical Institute,Leninsky prospect 53, Moscow 119991 (Russian Federation)

    2015-01-15

    Mixed-symmetry arbitrary spin massive, massless, and self-dual massive fields in AdS(5) are studied. Light-cone gauge actions for such fields leading to decoupled equations of motion are constructed. Light-cone gauge formulation of mixed-symmetry anomalous conformal currents and shadows in 4d flat space is also developed. AdS/CFT correspondence for normalizable and non-normalizable modes of mixed-symmetry AdS fields and the respective boundary mixed-symmetry anomalous conformal currents and shadows is studied. We demonstrate that the light-cone gauge action for massive mixed-symmetry AdS field evaluated on solution of the Dirichlet problem amounts to the light-cone gauge 2-point vertex of mixed-symmetry anomalous shadow. Also we show that UV divergence of the action for mixed-symmetry massive AdS field with some particular value of mass parameter evaluated on the Dirichlet problem amounts to the action of long mixed-symmetry conformal field, while UV divergence of the action for mixed-symmetry massless AdS field evaluated on the Dirichlet problem amounts to the action of short mixed-symmetry conformal field. We speculate on string theory interpretation of a model which involves short low-spin conformal fields and long higher-spin conformal fields.

  14. First steps of ion beam mixing: study by X-ray reflectometry and neutron diffraction

    International Nuclear Information System (INIS)

    Le Boite, M.G.

    1987-12-01

    There are several processes involved in ion beam mixing: ballistic processes, chemical driving forces and radiation enhanced diffusion. Experiments usually performed on bilayers irradiated with heavy elements and characterized by Rutherford backscattering (R.B.S.), have shown that the measured mixing rate is always higher than the calculated one, taking into account ballistic effects only. Besides classical R.B.S. experiments on NiAu and NiPt bilayers irradiated with Xe, we have used another technique of characterization: X-ray reflectometry and neutron diffraction, performed on multilayers irradiated with He. The systems are NiAu, NiPt, NiPd and NiAg, which behave similarly from the ballistic point of view, but have very different heats of mixing. In these experiments, the range of deposited energy density is very low, in contrast to heavy ions irradiation: this has allowed us to reach very low diffusion coefficient, never observed before. The dependence of the diffusion coefficient on the heat of mixing is in agreement with the one theoretically calculated. For the NiAg system, which has a positive heat of mixing, the measured diffusion coefficient is smaller than the ballistic one: a decrease of the ballistic mixing rate is seen for the first time. In this work, we have shown the interest of the reflectometry techniques (X-ray and neutrons); we have used a simple model to analyze the ion beam mixing, when elementary processes are involved

  15. Development of moderated neutron calibration fields simulating workplaces of MOX fuel facilities

    International Nuclear Information System (INIS)

    Tsujimura, Norio; Yoshida, Tadayoshi; Takada, Chie

    2005-01-01

    It is important for the MOX fuel facilities to control neutrons produced by the spontaneous fission of plutonium isotopes and those from (α,n) reactions between 18 O and α particles emitted by 238 Pu. Neutron dose meters should be calibrated for measuring these neutrons. We have developed moderated-neutron calibration fields employing a 252 Cf neutron source and moderators mainly for the characteristics evaluation and the calibration of neutron detectors used in MOX fuel facilities. Neutron energy spectrum can be adjusted by changing the position of the 252 Cf neutron source and combining different moderators to simulate the neutron field of the MOX fuel facility. This performance is realized owing to using an existing neutron irradiation room. (K. Yoshida)

  16. Determination of low-field critical parameters of superconducting niobium by small-angle neutron diffraction

    International Nuclear Information System (INIS)

    Christen, D.K.; Spooner, S.; Thorel, P.; Kerchner, H.R.

    1977-01-01

    The perfect double-crystal small-angle diffraction technique enables measurement of scattering angles to within 0.3 arc sec. accuracy. At a wavelength of 2.55 A, this provides a resolution of 3 x 10 -6 A -1 in the scattering vector. This technique has been used to study the anisotropic behavior of the critical parameters B 0 and H/sub c1/, characteristic of the first-order magnetic phase transition which occurs in low-kappa type-II superconductors. Magnetic fields were applied parallel to several crystal axes of a large single-crystal sphere of pure niobium, resulting in well-defined flux-line lattices (FLL). Measurement of the FLL cell area in the intermediate mixed state field region gives the equilibrium flux density B 0 , which results from an attractive interaction between fluxoids. In addition, field variation of the scattered neutron intensity allows measurement of the transition field between the mixed state and intermediate mixed state. This transition field is related to the lower critical field H/sub c1/ and enables its determination to a precision 0.2%. Data at T = 4.3 K display a small anisotropic effect of about 2% in B 0 and 1% in H/sub c1/. Although orientation effects of this magnitude are difficult to resolve by bulk measurements, the neutron data are in accord with magnetization data. Observations regarding the temperature dependence of these parameters also will be presented, and comparisons made with current theoretical models

  17. On the neutron diffraction in a crystal in the field of a standing laser wave

    International Nuclear Information System (INIS)

    Grigoryan, K.K.; Hayrapetyan, A.G.; Petrosyan, R.G.

    2010-01-01

    The possibility of high-energy neutron diffraction in a crystal is shown by applying the solution of time-dependent Schroedinger equation for a neutron in the field of a standing laser wave. The scattering picture is examined within the framework of non-stationary S-matrix theory, where the neutron-laser field interaction is considered exactly and the neutron-crystal interaction is considered as a perturbation described by Fermi pseudopotential (Farri representation). The neutron-crystal interaction is elastic, and the neutron-laser field interaction has both inelastic and elastic behaviors which results in the observation of an analogous to the Kapitza-Dirac effect for neutrons. The neutron scattering probability is calculated and the analysis of the results are adduced. Both inelastic and elastic diffraction conditions are obtained and the formation of a 'sublattice' is illustrated in the process of neutron-photon-phonon elastic interaction.

  18. Moduli/inflaton mixing with supersymmetry breaking field

    Energy Technology Data Exchange (ETDEWEB)

    Endo, M.; Takahashi, F. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)]|[Tokyo Univ. (Japan). Inst. for Cosmic Ray Research; Hamaguchi, K. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)]|[Tokyo Univ. (Japan). Dept. of Physics

    2006-05-15

    A heavy scalar field such as moduli or an inflaton generally mixes with a field responsible for the supersymmetry breaking. We study the scalar decay into the standard model particles and their superpartners, gravitinos, and the supersymmetry breaking sector, particularly paying attention to decay modes that proceed via the mixing between the scalar and the supersymmetry breaking field. The impacts of the new decay processes on cosmological scenarios are also discussed; the modulus field generically produces too much gravitinos, and most of the inflation models tend to result in too high reheating temperature and/or gravitino overproduction. (Orig.)

  19. Reference radiation fields - Simulated workplace neutron fields - Part 2: Calibration fundamentals related to the basic quantities

    International Nuclear Information System (INIS)

    2008-01-01

    ISO 8529-1, ISO 8529-2 and ISO 8529-3, deal with the production, characterization and use of neutron fields for the calibration of personal dosimeters and area survey meters. These International Standards describe reference radiations with neutron energy spectra that are well defined and well suited for use in the calibration laboratory. However, the neutron spectra commonly encountered in routine radiation protection situations are, in many cases, quite different from those produced by the sources specified in the International Standards. Since personal neutron dosimeters, and to a lesser extent survey meters, are generally quite energy dependent in their dose equivalent response, it might not be possible to achieve an appropriate calibration for a device that is used in a workplace where the neutron energy spectrum and angular distribution differ significantly from those of the reference radiation used for calibration. ISO 8529-1 describes four radionuclide based neutron reference radiations in detail. This part of ISO 12789 includes the specification of neutron reference radiations that were developed to closely resemble radiation that is encountered in practice

  20. Monte Carlo calculations for intermediate-energy standard neutron field

    International Nuclear Information System (INIS)

    Joneja, O.P.; Subbukutty, K.; Iyengar, S.B.D.; Navalkar, M.P.

    Intermediate-Energy Standard Neutron Field (ISNF) which produces a well characterised spectrum in the energy range of interest for fast reactors including breeders, has been set up at NBS using thin enriched 235 U fission sources. A proposal has been made for setting up a similar facility at BARC using however, easily available natural U instead of enriched U sources, to start with. In order to simulate the neutronics of such a facility Monte Carlo method of calculations has been adopted and developed. The results of these calculations have been compared with those of NBS and it is found that there may be a maximum difference of 10% in spectrum characteristics for the two cases of using thick and thin fission sources. (K.B.)

  1. Development of the neutron reference calibration field using a {sup 252}Cf standard source surrounded with PMMA moderators

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, T.; Kanai, K.; Tsujimura, N. [Japan Nuclear Cycle Development Institute, Ibaraki-ken (Japan)

    2002-07-01

    The authors developed the neutron reference calibration fields using a {sup 252} Cf standard source surrounded with PMMA moderators at the Japan Nuclear Cycle Development (JNC), Tokai Works. The moderators are co-axial, hollow cylinders made of lead-contained PMMA with a thickness of 13.5, 35.0, 59.5 and 77.0mm, and the {sup 252} Cf source is guided to the geometric center of moderators by the pneumatic system. These fields can provide the moderated neutron spectra very similar to those encountered around the globe-boxes of the fabrication process of MOX (PuO{sub 2}-UO{sub 2} mixed oxide) fuel. The neutron energy spectrum at the reference calibration point was evaluated from the calculations by MCNP4B and the measurements by the INS-type Bonner multi-sphere spectrometer and the hydrogen-filled proportional counters. The calculated neutron spectra were in good agreements with the measured ones. These fields were characterized in terms of the neutron fluence rate, spectral composition and ambient dose equivalent rate, and have served for the response-characterization of various neutron survey instruments.

  2. Development of the neutron reference calibration field using a 252Cf standard source surrounded with PMMA moderators

    International Nuclear Information System (INIS)

    Yoshida, T.; Kanai, K.; Tsujimura, N.

    2002-01-01

    The authors developed the neutron reference calibration fields using a 252 Cf standard source surrounded with PMMA moderators at the Japan Nuclear Cycle Development (JNC), Tokai Works. The moderators are co-axial, hollow cylinders made of lead-contained PMMA with a thickness of 13.5, 35.0, 59.5 and 77.0mm, and the 252 Cf source is guided to the geometric center of moderators by the pneumatic system. These fields can provide the moderated neutron spectra very similar to those encountered around the globe-boxes of the fabrication process of MOX (PuO 2 -UO 2 mixed oxide) fuel. The neutron energy spectrum at the reference calibration point was evaluated from the calculations by MCNP4B and the measurements by the INS-type Bonner multi-sphere spectrometer and the hydrogen-filled proportional counters. The calculated neutron spectra were in good agreements with the measured ones. These fields were characterized in terms of the neutron fluence rate, spectral composition and ambient dose equivalent rate, and have served for the response-characterization of various neutron survey instruments

  3. Characterization of Monoenergetic Low Energy Neutron Fields with the {mu}TPC Detector

    Energy Technology Data Exchange (ETDEWEB)

    Golabek, C.; Lebreton, L.; Petit, M. [Laboratoire de Metrologie et de Dosimetrie des Neutrons, IRSN Cadarache, 13115 Saint-Paul-Lez-Durance (France); Billard, J.; Grignon, C.; Bosson, G.; Bourrion, O.; Guillaudin, O.; Mayet, F.; Richer, J.-P.; Santos, D. [Laboratoire de Physique Subatomique et de Cosmologie, Universite Joseph (France)

    2011-12-13

    The AMANDE facility produces monoenergetic neutron fields from 2 keV to 20 MeV for metrological purposes. To be considered as a reference facility, fluence and energy distributions of neutron fields have to be determined by primary measurement standards. For this purpose, a micro Time Projection Chamber is being developed to be dedicated to measure neutron fields with energy ranging from 2 keV up to 1 MeV. We present simulations showing that such a detector, which allows the measurement of the ionization energy and the 3D reconstruction of the recoil nucleus, provides the determination of neutron energy and fluence of such low energy neutron fields.

  4. LUPIN, a new instrument for pulsed neutron fields

    Energy Technology Data Exchange (ETDEWEB)

    Caresana, M. [Politecnico di Milano, Department of Energy, Via Ponzio 34/3, 20133 Milan (Italy); Ferrarini, M. [Politecnico di Milano, Department of Energy, Via Ponzio 34/3, 20133 Milan (Italy); CNAO, Via Privata Campeggi, 27100 Pavia (Italy); Manessi, G.P., E-mail: giacomo.paolo.manessi@cern.ch [CERN, 1211 Geneva 23 (Switzerland); University of Liverpool, Department of Physics, L69 7ZE Liverpool (United Kingdom); Silari, M. [CERN, 1211 Geneva 23 (Switzerland); Varoli, V. [Politecnico di Milano, Department of Energy, Via Ponzio 34/3, 20133 Milan (Italy)

    2013-06-01

    A number of studies focused in the last decades on the development of survey meters to be used in pulsed radiation fields. This is a topic attracting widespread interest for applications such as radiation protection and beam diagnostics in accelerators. This paper describes a new instrument specifically conceived for applications in pulsed neutron fields (PNF). The detector, called LUPIN, is a rem counter type instrument consisting of a {sup 3}He proportional counter placed inside a spherical moderator. It works in current mode with a front-end electronics consisting of a current–voltage logarithmic amplifier, whose output signal is acquired with an ADC and processed on a PC. This alternative signal processing allows the instrument to be used in PNF without being affected by saturation effects. Moreover, it has a measurement capability ranging over many orders of burst intensity. Despite the fact that it works in current mode, it can measure a single neutron interaction. The LUPIN was first calibrated in CERN's calibration laboratory with a PuBe source. Measurements were carried out under various experimental conditions at the Helmholtz-Zentrum in Berlin, in the stray field at various locations of the CERN Proton Synchrotron complex and around a radiotherapy linear accelerator at the S. Raffaele hospital in Milan. The detector can withstand single bursts with values of H⁎(10) up to 16 nSv/burst without showing any saturation effect. It efficiently works in pulsed stray fields, where a conventional rem-counter underestimates by a factor of 2. It is also able to reject the very intense and pulsed photon contribution that often accompanies the neutron field with good reliability. -- Highlights: ► LUPIN is a new detector specifically conceived to work in neutron pulsed fields. ► The detector is a rem counter type instrument working in current mode. ► The performances of the detectors were studied under various experimental conditions. ► The detector

  5. Neutrons field in the neutronic measurements room of the Polytechnic University of Madrid

    International Nuclear Information System (INIS)

    Vega C, H. R.; Gallego, E.; Lorente, A.; Rubio O, I. P.

    2010-09-01

    Through of measurements and calculations of a Monte Carlo series has been characterized the neutronic field of the neutronic measurements room of Nuclear Engineering Department of the Polytechnic University of Madrid. The measurements were realized with the Bonner Spheres Spectrometer that allowed establish the spectra on the new stainless steel panel and at different distances measured regarding the source. The values of the speed of environmental equivalent dose were measured with an area monitor Bert hold Lb 6411. Through of Monte Carlo methods was built a detailed model of the room with the panel and the spectra were calculated and, with these the values of the environmental equivalent dose were obtained using the conversion coefficients of the ICRP 74 and the Bert hold Lb 6411 response. The calculated values were compared with those measured and was consistency among the results. (Author)

  6. Possible dark energy imprints in the gravitational wave spectrum of mixed neutron-dark-energy stars

    Energy Technology Data Exchange (ETDEWEB)

    Yazadjiev, Stoytcho S. [Department of Theoretical Physics, Faculty of Physics, St. Kliment Ohridski University of Sofia, James Bourchier Blvd. 5, 1164 Sofia (Bulgaria); Doneva, Daniela D., E-mail: yazad@phys.uni-sofia.bg, E-mail: daniela.doneva@uni-tuebingen.de [Theoretical Astrophysics, IAAT, Eberhard-Karls University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen (Germany)

    2012-03-01

    In the present paper we study the oscillation spectrum of neutron stars containing both ordinary matter and dark energy in different proportions. Within the model we consider, the equilibrium configurations are numerically constructed and the results show that the properties of the mixed neuron-dark-energy star can differ significantly when the amount of dark energy in the stars is varied. The oscillations of the mixed neuron-dark-energy stars are studied in the Cowling approximation. As a result we find that the frequencies of the fundamental mode and the higher overtones are strongly affected by the dark energy content. This can be used in the future to detect the presence of dark energy in the neutron stars and to constrain the dark-energy models.

  7. Responses of commercially available neutron electronic personal dosemeters in neutron fields simulating workplaces at MOX fuel fabrication facilities

    International Nuclear Information System (INIS)

    Tsujimura, N.; Yoshida, T.; Takada, C.

    2011-01-01

    The authors investigated the performance of three commercially available electronic personal dosemeters (EPDs) in evaluating neutron dose equivalents and discussed their suitability to work environments in MOX fuel fabrication facilities. The EPDs selected for this study were NRY21 (Fuji Electric Systems), PDM-313 (Aloka) and DMC 2000 GN (MGP Instruments). All tests were conducted in moderated 252 Cf neutron fields with neutron spectral and dosimetric characteristics similar to those found in MOX fuel facilities. The test results revealed trends and the magnitude of response variations in relation to neutron spectral changes expected in work environments.

  8. Evaluation of area monitor response for neutrons in radiation field generated by a 15 MV clinic accelerator

    International Nuclear Information System (INIS)

    Salgado, Ana Paula

    2011-01-01

    The clinical importance and usage of linear accelerators in cancer treatment increased significantly in the last years. Coupled with this growth came the concern about the use of accelerators with energies over to 10 MeV which produce therapeutic beam contaminated with neutrons generated when high-energy photons interact with high-atomic-number materials such as tungsten and lead present in the accelerator itself. At these facilities, measurements of the ambient dose equivalent for neutrons present difficulties owing to the existence of a mixed radiation field and possible electromagnetic interference near the accelerator. The Neutron Laboratory of the IRD - Brazilian Institute for Radioprotection and Dosimetry, aiming to evaluate the survey meters performance at these facilities, initiated studies of instrumentation response in the presence of different neutron spectra. Neutrons sources with average energies ranging from 0.55 to 4.2 MeV, four different survey meters and one ionization chamber to obtain the ratio between the dose due to neutrons and gamma radiation were used in this work. The evaluation of these measurements, performed in a 15 MV linear accelerator room is presented. This work presents results that demonstrate the complexity and care needed to make neutrons measurements in radiotherapy treatment rooms containing high energy clinical accelerators. (author)

  9. Instrument intercomparison in the high-energy mixed field at the CERN-EU reference field (CERF) facility

    CERN Document Server

    Caresana, Marco; Manessi, Giacomo; Ott, Klaus; Scherpelz, Robert; Silari, Marco

    2014-01-01

    This paper discusses an intercomparison campaign performed in the mixed radiation field at the CERN-EU (CERF) reference field facility. Various instruments were employed: conventional and extended-range rem counters including a novel instrument called LUPIN, a bubble detector using an active counting system (ABC 1260) and two tissue-equivalent proportional counters (TEPCs). The results show that the extended range instruments agree well within their uncertainties and within 1σ with the H*(10) FLUKA value. The conventional rem counters are in good agreement within their uncertainties and underestimate H*(10) as measured by the extended range instruments and as predicted by FLUKA. The TEPCs slightly overestimate the FLUKA value but they are anyhow consistent with it when taking the comparatively large total uncertainties into account, and indicate that the non-neutron part of the stray field accounts for ∼30 % of the total H*(10).

  10. Heterogeneous analysis of non-uniform neutron field formation

    International Nuclear Information System (INIS)

    Zagrebaev, A.M.; Fedosov, A.M.

    1979-01-01

    Investigated are the specific features of spatial-energy neutron distribution formation in the transient zone between regions, operating at different levels of energy release with accounting for the real structure of fuel element lattice and control elements in the channel reactors of high power. Presented are the calculation results, obtained by heterogeneous method in the two-group monopole approximation by means of the HETLAT code. The analysis, based on the homogeneous model shows, that the efficiency of the transient zone in forming neutron flux qradient can be increased by introducing an additional interlayer of moderator between the layers with extreme multiplying properties. It is stressed, that the most favourable from the point of view of energy release uniformity in zones and width of the transient zone is the variant in which neutron flux gradient is carried out by moving the control elements on the boundaries of regions while the internal rows of control elements create the conditions for flattening the energy release in the zones. The result obtained corresponds to the recommendation on optimal control, coming from the Pontryagin maximum principle. The analysis of neutron field formation using heterogeneous models mainly proves the conclusions following from homogeneous calculations using the maximum principle. At the same time quantitative results for the zones of small dimensions (less than 10 migration lengths) with a vividly expressed heterogeneous structure essentially differ from the forecast, obtained on the basis of the simplified homogeneous one-group model. The heterogeneous analysis shows possibilities for further optimization of the transient zone structure with account of the control element location

  11. Investigation of the response characteristics of OSL albedo neutron dosimeters in a 241AmBe reference neutron field

    Science.gov (United States)

    Liamsuwan, T.; Wonglee, S.; Channuie, J.; Esoa, J.; Monthonwattana, S.

    2017-06-01

    The objective of this work was to systematically investigate the response characteristics of optically stimulated luminescence Albedo neutron (OSLN) dosimeters to ensure reliable personal dosimetry service provided by Thailand Institute of Nuclear Technology (TINT). Several batches of InLight® OSLN dosimeters were irradiated in a reference neutron field generated by the in-house 241AmBe neutron irradiator. The OSL signals were typically measured 24 hours after irradiation using the InLight® Auto 200 Reader. Based on known values of delivered neutron dose equivalent, the reading correction factor to be used by the reader was evaluated. Subsequently, batch homogeneity, dose linearity, lower limit of detection and fading of the OSLN dosimeters were examined. Batch homogeneity was evaluated to be 0.12 ± 0.05. The neutron dose response exhibited a linear relationship (R2=0.9974) within the detectable neutron dose equivalent range under test (0.4-3 mSv). For this neutron field, the lower limit of detection was between 0.2 and 0.4 mSv. Over different post-irradiation storage times of up to 180 days, the readings fluctuated within ±5%. Personal dosimetry based on the investigated OSLN dosimeter is considered to be reliable under similar neutron exposure conditions, i.e. similar neutron energy spectra and dose equivalent values.

  12. The measurement of gamma ray induced heating in a mixed neutron and gamma ray environment

    International Nuclear Information System (INIS)

    Chiu, H.K.

    1991-10-01

    The problem of measuring the gamma heating in a mixed DT neutron and gamma ray environment was explored. A new detector technique was developed to make this measurement. Gamma heating measurements were made in a low-Z assembly irradiated with 14-Mev neutrons and (n, n') gammas produced by a Texas Nuclear Model 9400 neutron generator. Heating measurements were made in the mid-line of the lattice using a proportional counter operating in the Continuously-varied Bias-voltage Acquisition mode. The neutron-induced signal was separated from the gamma-induced signal by exploiting the signal rise-time differences inherent to radiations of different linear energy transfer coefficient, which are observable in a proportional counter. The operating limits of this measurement technique were explored by varying the counter position in the low-Z lattice, hence changing the irradiation spectrum observed. The experiment was modelled numerically to help interpret the measured results. The transport of neutrons and gamma rays in the assembly was modelled using the one- dimensional radiation transport code ANISN/PC. The cross-section set used for these calculations was derived from the ENDF/B-V library using the code MC 2 -2 for the case of DT neutrons slowing down in a low-Z material. The calculated neutron and gamma spectra in the slab and the relevant mass-stopping powers were used to construct weighting factors which relate the energy deposition in the counter fill-gas to that in the counter wall and in the surrounding material. The gamma energy deposition at various positions in the lattice is estimated by applying these weighting factors to the measured gamma energy deposition in the counter at those locations

  13. Mixed global anomalies and boundary conformal field theories

    OpenAIRE

    Numasawa, Tokiro; Yamaguchi, Satoshi

    2017-01-01

    We consider the relation of mixed global gauge gravitational anomalies and boundary conformal field theory in WZW models for simple Lie groups. The discrete symmetries of consideration are the centers of the simple Lie groups. These mixed anomalies prevent to gauge them i.e, take the orbifold by the center. The absence of anomalies impose conditions on the levels of WZW models. Next, we study the conformal boundary conditions for the original theories. We consider the existence of a conformal...

  14. Measurements and Monte Carlo calculations with the extended-range Bonner sphere spectrometer at high-energy mixed fields

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00406842; Bay, Aurelio; Silari, Marco; Aroua, Abbas

    The use of spectrometry to provide information for neutron radiation protection has become an increasingly important activity over recent years. The need for spectral data arises because neither area survey instruments nor personal dosimeters give the correct dose equivalent results at all neutron energies. It is important therefore to know the spectra of the fields in which these devices are used. One of the systems most commonly employed in neutron spectrometry and dosimetry is the Bonner Sphere Spectrometers (BSS). The extended- range BSS that was used for this work, consists of 7 spheres with an overall response to neutrons up to 2 GeV. A 3He detector is used as a thermal counter in the centre of each sphere. In the context of this thesis the BSS was calibrated in monoenergetic neutron fields at low and intermediate energies. It was also used for measurements in several high energy mixed fields. These measurements have led to the calculation of neutron yields and spectral fluences from unshielded targets....

  15. Experimental possibilities and fast neutron dose map of the fast neutron fields at the RB reactor facility

    International Nuclear Information System (INIS)

    Sokcic-Kostic, M.; Pesic, M.; Antic, D.; Ninkovic, M.

    1993-01-01

    The RB is an unshielded, zero power nuclear facility with natural and enriched uranium fuel (2% and 80%) and D 2 O as moderator. It is possible to create different configurations of non-reflected and partially reflected critical systems and to make experiments in the fields of thermal neutrons. The fields of fast neutrons with 'softened' fission spectrum are made by modifying the system: modified experimental fuel channel EFC, coupled fast-thermal system in two configurations CFTS-1 and CFTS-2, coupled fast-thermal core HERBE. The intermediate and fast neutron absorbed doses in fast neutron fields are given. In first configuration of RB reactor it was almost impossible to perform dosimetric and other experiments. By creating these fields, with in our circumstances available fuel elements, the possibilities for different experiments are greatly improved. Now we can irradiate food samples, soil samples, electronic devices, study material properties, perform various dosimetry experiments, etc. (1 tab.)

  16. A new mixed self-consistent field procedure

    Science.gov (United States)

    Alvarez-Ibarra, A.; Köster, A. M.

    2015-10-01

    A new approach for the calculation of three-centre electronic repulsion integrals (ERIs) is developed, implemented and benchmarked in the framework of auxiliary density functional theory (ADFT). The so-called mixed self-consistent field (mixed SCF) divides the computationally costly ERIs in two sets: far-field and near-field. Far-field ERIs are calculated using the newly developed double asymptotic expansion as in the direct SCF scheme. Near-field ERIs are calculated only once prior to the SCF procedure and stored in memory, as in the conventional SCF scheme. Hence the name, mixed SCF. The implementation is particularly powerful when used in parallel architectures, since all RAM available are used for near-field ERI storage. In addition, the efficient distribution algorithm performs minimal intercommunication operations between processors, avoiding a potential bottleneck. One-, two- and three-dimensional systems are used for benchmarking, showing substantial time reduction in the ERI calculation for all of them. A Born-Oppenheimer molecular dynamics calculation for the Na+55 cluster is also shown in order to demonstrate the speed-up for small systems achievable with the mixed SCF. Dedicated to Sourav Pal on the occasion of his 60th birthday.

  17. Continuous spin fields of mixed-symmetry type

    Science.gov (United States)

    Alkalaev, Konstantin; Grigoriev, Maxim

    2018-03-01

    We propose a description of continuous spin massless fields of mixed-symmetry type in Minkowski space at the level of equations of motion. It is based on the appropriately modified version of the constrained system originally used to describe massless bosonic fields of mixed-symmetry type. The description is shown to produce generalized versions of triplet, metric-like, and light-cone formulations. In particular, for scalar continuous spin fields we reproduce the Bekaert-Mourad formulation and the Schuster-Toro formulation. Because a continuous spin system inevitably involves infinite number of fields, specification of the allowed class of field configurations becomes a part of its definition. We show that the naive choice leads to an empty system and propose a suitable class resulting in the correct degrees of freedom. We also demonstrate that the gauge symmetries present in the formulation are all Stueckelberg-like so that the continuous spin system is not a genuine gauge theory.

  18. Mixing of alcohol and water molecules studied by neutron probe. Structure and dynamics

    International Nuclear Information System (INIS)

    Yoshida, Koji

    2001-01-01

    Structure of water/alcohol mixing solution was studied by three methods such as an isotope-exchanged neutron scattering method, RISM (Reference Interaction Site Model) integral equation and a neutron spin echo method. The principle of methods, experiments and results were reported. The results of experiments of water/tert-butyl alcohol (TBA) solution by the isotope-exchange neutron scattering method showed TBA molecule associated with each other through end methyl group. Especially this effect was the largest at x TBA = 0.06 and decreased with increasing the concentration of TBA. However, hydrogen bonding of TBA was very rare at x TBA = 0.06. By the partial radial distribution function obtained from RISM integral equation, it indicated that the structure of pure TBA became chain structure by hydrogen bond but changed to the structure contacted directly each hydrophobic group with increasing the concentration of water. Water/2-butoxyethanol (BE) mixing solution was measured by a neutron spin echo method. The activation energy of the diffusion coefficients obtained agreed to the energy of hydrogen bonding. The temperature response of diffusion coefficients showed the inverse of the experimental results obtained by the dynamic light scattering method. The difference between two measurement methods was different time scale and space scale. Namely, the object of the neutron scattering method is nano meter and nano second, but one of light scattering method many times over. It was proved from the above results that there was the cluster consisted of the same kind of molecule in the homogeneous two components solution, but the cluster was not stable and constantly exchanged with molecule, where the production and decay of the cluster is repeated at about nano sec. (S.Y.)

  19. Geiger-Mueller counter for mixed neutron-gamma beam dosimetry

    International Nuclear Information System (INIS)

    McDonald, J.C.; Ma, I.-C.

    1978-01-01

    A Geiger-Mueller (G-M) dosimeter has been constructed and employed to measure the gamma-ray component of absorbed dose in a cyclotron produced fast neutron field. This instrument is waterproof for measurements in a liquid medium, and read-out is accompanied with any standard scaler. (Auth.)

  20. To the problem of spatial focusing of ultracold neutrons by nonuniform magnetic field. Eikonal approximation

    CERN Document Server

    Chen, T

    2002-01-01

    Motion of the ultracold neutrons in the nonuniform magnetic field with a square nonuniformity by two coordinates is considered. The Schroedinger equation is solved with application of the quasi-classical (eikonal) approach. The theoretical possibility of the neutrons spatial focusing with formation of the point focus and also the neutrons bunches is shown

  1. Neutron Field Characterization of Irradiation Locations Applied to the Slovenian TRIGA Reactor

    International Nuclear Information System (INIS)

    Barbot, Loic; Domergue, Christophe; Breaud, Stephane; Destouches, Christophe; Villard, Jean-Francois; Snoj, Luka; Stancar, Ziga; Radulovic, Vladimir; Trkov, Andrej

    2013-06-01

    This work deals with several neutron flux measurement instruments and particle transport calculations combined in a method to assess the neutron field in experimental locations in nuclear reactor core or reflector. First test of this method in the TRIGA Mark II of Slovenia led to the assessment of three energy groups neutron fluxes in central irradiation locations within reactor core. (authors)

  2. A study of the cosmic-ray neutron field near interfaces

    CERN Document Server

    Sheu, R J; Jiang, S H

    2002-01-01

    This study investigated the characteristics of the cosmic-ray neutron field near air/ground and air/water interfaces with an emphasis on the angular distribution. Two sets of high-efficiency neutron detecting systems were used. The first one, called the Bonner Cylinders, was used for measurements of the energy information. The other one, referred to as the eight-channel neutron detector (8CND), was used to characterize the angular information of the neutron field. The measured results were used to normalize and confirm one-dimensional transport calculations for cosmic-ray neutrons below 20 MeV in the air/ground and air/water media. Annual sea level cosmic-ray neutron doses were then determined based on the obtained characteristics of low-energy cosmic-ray neutrons near interfaces and estimated contribution from high-energy neutrons.

  3. Domain decomposition methods for the mixed dual formulation of the critical neutron diffusion problem

    International Nuclear Information System (INIS)

    Guerin, P.

    2007-12-01

    The neutronic simulation of a nuclear reactor core is performed using the neutron transport equation, and leads to an eigenvalue problem in the steady-state case. Among the deterministic resolution methods, diffusion approximation is often used. For this problem, the MINOS solver based on a mixed dual finite element method has shown his efficiency. In order to take advantage of parallel computers, and to reduce the computing time and the local memory requirement, we propose in this dissertation two domain decomposition methods for the resolution of the mixed dual form of the eigenvalue neutron diffusion problem. The first approach is a component mode synthesis method on overlapping sub-domains. Several Eigenmodes solutions of a local problem solved by MINOS on each sub-domain are taken as basis functions used for the resolution of the global problem on the whole domain. The second approach is a modified iterative Schwarz algorithm based on non-overlapping domain decomposition with Robin interface conditions. At each iteration, the problem is solved on each sub domain by MINOS with the interface conditions deduced from the solutions on the adjacent sub-domains at the previous iteration. The iterations allow the simultaneous convergence of the domain decomposition and the eigenvalue problem. We demonstrate the accuracy and the efficiency in parallel of these two methods with numerical results for the diffusion model on realistic 2- and 3-dimensional cores. (author)

  4. Using the Δ3 statistic to test for missed levels in mixed sequence neutron resonance data

    International Nuclear Information System (INIS)

    Mulhall, Declan

    2009-01-01

    The Δ 3 (L) statistic is studied as a tool to detect missing levels in the neutron resonance data where two sequences are present. These systems are problematic because there is no level repulsion, and the resonances can be too close to resolve. Δ 3 (L) is a measure of the fluctuations in the number of levels in an interval of length L on the energy axis. The method used is tested on ensembles of mixed Gaussian orthogonal ensemble spectra, with a known fraction of levels (x%) randomly depleted, and can accurately return x. The accuracy of the method as a function of spectrum size is established. The method is used on neutron resonance data for 11 isotopes with either s-wave neutrons on odd-A isotopes, or p-wave neutrons on even-A isotopes. The method compares favorably with a maximum likelihood method applied to the level spacing distribution. Nuclear data ensembles were made from 20 isotopes in total, and their Δ 3 (L) statistics are discussed in the context of random matrix theory.

  5. Radiation effect on silicon transistors in mixed neutrons-gamma environment

    Science.gov (United States)

    Assaf, J.; Shweikani, R.; Ghazi, N.

    2014-10-01

    The effects of gamma and neutron irradiations on two different types of transistors, Junction Field Effect Transistor (JFET) and Bipolar Junction Transistor (BJT), were investigated. Irradiation was performed using a Syrian research reactor (RR) (Miniature Neutron Source Reactor (MNSR)) and a gamma source (Co-60 cell). For RR irradiation, MCNP code was used to calculate the absorbed dose received by the transistors. The experimental results showed an overall decrease in the gain factors of the transistors after irradiation, and the JFETs were more resistant to the effects of radiation than BJTs. The effect of RR irradiation was also greater than that of gamma source for the same dose, which could be because neutrons could cause more damage than gamma irradiation.

  6. Performance of silicon pad detectors after mixed irradiations with neutrons and fast charged hadrons

    Energy Technology Data Exchange (ETDEWEB)

    Kramberger, G. [Jozef Stefan Institute, Department of Physics, University of Ljubljana, Jamova 39, SI-1000 Ljubljana (Slovenia)], E-mail: Gregor.Kramberger@ijs.si; Cindro, V.; Dolenc, I.; Mandic, I.; Mikuz, M.; Zavrtanik, M. [Jozef Stefan Institute, Department of Physics, University of Ljubljana, Jamova 39, SI-1000 Ljubljana (Slovenia)

    2009-10-11

    A large set of silicon pad detectors produced on MCz and FZ wafer of p- and n-type was irradiated in two steps, first by fast charged hadrons followed by reactor neutrons. In this way the irradiations resemble the real irradiation fields at LHC. After irradiations controlled annealing started in steps during which the evolution of full depletion voltage, leakage current and charge collection efficiency was monitored. The damage introduced by different irradiation particles was found to be additive. The most striking consequence of that is a decrease of the full depletion voltage for n-type MCz detectors after additional neutron irradiation. This confirms that effective donors introduced by charged hadron irradiation are compensated by acceptors from neutron irradiation.

  7. Performance of silicon pad detectors after mixed irradiations with neutrons and fast charged hadrons

    International Nuclear Information System (INIS)

    Kramberger, G.; Cindro, V.; Dolenc, I.; Mandic, I.; Mikuz, M.; Zavrtanik, M.

    2009-01-01

    A large set of silicon pad detectors produced on MCz and FZ wafer of p- and n-type was irradiated in two steps, first by fast charged hadrons followed by reactor neutrons. In this way the irradiations resemble the real irradiation fields at LHC. After irradiations controlled annealing started in steps during which the evolution of full depletion voltage, leakage current and charge collection efficiency was monitored. The damage introduced by different irradiation particles was found to be additive. The most striking consequence of that is a decrease of the full depletion voltage for n-type MCz detectors after additional neutron irradiation. This confirms that effective donors introduced by charged hadron irradiation are compensated by acceptors from neutron irradiation.

  8. Gauge field governing parallel transport along mixed states

    International Nuclear Information System (INIS)

    Uhlmann, A.

    1990-01-01

    At first a short account is given of some basic notations and results on parallel transport along mixed states. A new connection form (gauge field) is introduced to give a geometric meaning to the concept of parallelity in the theory of density operators. (Author) 11 refs

  9. Fast neutron dosimeter with wide base silicon diode

    International Nuclear Information System (INIS)

    Ma Lu

    1986-01-01

    This paper briefly introduces a wide base silicon diode fast neutron dosimeter with wide measuring range and good energy response to fast neutron. It is suitable to be used to detect fast neutrons in the mixed field of γ-ray, thermal neutrons and fast neutrons

  10. Pulsed mixed n, γ radiation fields for electronic testing

    International Nuclear Information System (INIS)

    Nurdin, G.; Becret, C.; Jaureguy, J.C.; Vie, M.; Baboulet, J.P.; Lapeyre, P.; Ramisse, D.

    1994-01-01

    For combined n, γ TREE testing we have modified the CALIBAN Fast Burst Reactor Field with CdO/Epoxy converters to cover the range [10 11 -10 12 ] n.cm -2 (1 MeV Si), [10 7 - 10 8 ] cGy(Si).s -1 . Activation and fission σ φvector, 1 MeV(Si) fluences, neutron spectra, total exposures and dose rates were predicted with good agreement by n, γ photon transport codes. (author). 12 refs., 2 figs., 1 tab

  11. Neutron field characterization in the installation for BNCT study in the IEA-R1 reactor; Caracterizacao do campo de neutrons na instalacao para estudo em BNCT no reator IEA-R1

    Energy Technology Data Exchange (ETDEWEB)

    Carneiro Junior, Valdeci

    2008-07-01

    This work aims to characterize the mixed neutron and gamma field, in the sample irradiation position, in a research installation for Boron Neutron Capture Therapy (BNCT), in the IPEN IEA-R1 reactor. The BNCT technique has been studied as a safe and selective option in the treatment of resistant cancerigenous tumors or considered non-curable by the conventional techniques, for example, the Glioblastoma Multiform - a brain cancerigenous tumor. Neutron flux measurements were carried out: thermal, resonance and fast, as well as neutron and gamma rays doses, in the sample position, using activation foils detectors and thermoluminescent dosimeters. For the determination of the neutron spectrum and intensity, a set of different threshold activation foils and gold foils covered and uncovered with cadmium irradiated in the installation was used, analyzed by a high Pure Germanium semiconductor detector, coupled to an electronic system suitable for gamma spectrometry. The results were processed with the SAND-BP code. The doses due to gamma and neutron rays were determined using thermoluminescent dosimeters TLD 400 and TLD 700 sensitive to gamma and TLD 600, sensitive to neutrons. The TLDs were selected and used for obtaining the calibration curves - dosimeter answer versus dose - from each of the TLD three types, which were necessary to calculate the doses due to neutron and gamma, in the sample position. The radiation field, in the sample irradiation position, was characterized flux for thermal neutrons of 1.39.10{sup 8} {+-} 0,12.10{sup 8} n/cm{sup 2}s the doses due to thermal neutrons are three times higher than those due to gamma radiation and confirm the reproducibility and consistency of the experimental findings obtained. Considering these results, the neutron field and gamma radiation showed to be appropriated for research in BNCT. (author)

  12. Microstructural evolution of pure tungsten neutron irradiated with a mixed energy spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Koyanagi, Takaaki, E-mail: koyanagit@ornl.gov [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Kumar, N.A.P. Kiran [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Hwang, Taehyun [Tohoku University, Sendai, 980-8579 (Japan); Garrison, Lauren M.; Hu, Xunxiang [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Snead, Lance L. [Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Katoh, Yutai [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2017-07-15

    Microstructures of single-crystal bulk tungsten (W) and polycrystalline W foil with a strong grain texture were investigated using transmission electron microscopy following neutron irradiation at ∼90–800 °C to 0.03–4.6 displacements per atom (dpa) in the High Flux Isotope Reactor with a mixed energy spectrum. The dominant irradiation defects were dislocation loops and small clusters at ∼90 °C. Additional voids were formed in W irradiated at above 460 °C. Voids and precipitates involving transmutation rhenium and osmium were the dominant defects at more than ∼1 dpa. We found a new phenomenon of microstructural evolution in irradiated polycrystalline W: Re- and Os-rich precipitation along grain boundaries. Comparison of results between this study and previous studies using different irradiation facilities revealed that the microstructural evolution of pure W is highly dependent on the neutron energy spectrum in addition to the irradiation temperature and dose.

  13. Chameleon-photon mixing in a primordial magnetic field

    International Nuclear Information System (INIS)

    Schelpe, Camilla A. O.

    2010-01-01

    The existence of a sizable, O(10 -10 -10 -9 G), cosmological magnetic field in the early Universe has been postulated as a necessary step in certain formation scenarios for the large-scale O(μG) magnetic fields found in galaxies and galaxy clusters. If this field exists then it may induce significant mixing between photons and axion-like particles (ALPs) in the early Universe. The resonant conversion of photons into ALPs in a primordial magnetic field has been studied elsewhere by Mirizzi, Redondo and Sigl (2009). Here we consider the nonresonant mixing between photons and scalar ALPs with masses much less than the plasma frequency along the path, with specific reference to the chameleon scalar field model. The mixing would alter the intensity and polarization state of the cosmic microwave background (CMB) radiation. We find that the average modification to the CMB polarization modes is negligible. However the average modification to the CMB intensity spectrum is more significant and we compare this to high-precision measurements of the CMB monopole made by the far infrared absolute spectrophotometer on board the COBE satellite. The resulting 95% confidence limit on the scalar-photon conversion probability in the primordial field (at 100 GHz) is P γ↔φ -2 . This corresponds to a degenerate constraint on the photon-scalar coupling strength, g eff , and the magnitude of the primordial magnetic field. Taking the upper bound on the strength of the primordial magnetic field derived from the CMB power spectra, B λ ≤5.0x10 -9 G, this would imply an upper bound on the photon-scalar coupling strength in the range g eff -13 GeV -1 to g eff -14 GeV -1 , depending on the power spectrum of the primordial magnetic field.

  14. Cosmic-ray neutron transport at a forest field site

    DEFF Research Database (Denmark)

    Andreasen, Mie; Jensen, Karsten Høgh; Desilets, Darin

    2017-01-01

    -ray neutron intensity is essential (e.g., the effect of vegetation, litter layer and soil type). In this study the environmental effect is examined by performing a sensitivity analysis using neutron transport modeling. We use a neutron transport model with various representations of the forest and different...

  15. Fast neutron fields at the RB reactor; Polja brzih neutron na reacktoru RB

    Energy Technology Data Exchange (ETDEWEB)

    Strugar, P; Pesic, M; Dasic, N [Institut za nuklearne nauke Boris Kidric Vinca, Beograd (Yugoslavia)

    1984-07-01

    Paper deals with the reasons and methods of realization of the RB neutron converters. The methods and results of neutron flux intensities and spectra measurements as well as gamma dose determination are presented. (author)

  16. Bubble detectors as a tool of the dosimetry and microdosimetry in neutron fields

    International Nuclear Information System (INIS)

    Spurny, F.; Vlcek, B.; Rannou, A.

    1998-01-01

    Two types of bubble detector were studied: the Bubble Damage Neutron Detector (BDND) and the Superheated Drop Detector (SDD). The detectors were tested in neutron beams and fields. The relative response of the detectors varied with the average neutron energy. The response of SDD 100 started to decrease at higher energies than for BDND's, at 100 keV it was only about 1/4 of the response to AmBe neutrons. The responses of SDD 1000 and SDD 6000 decreased with the average neutron energy in a rather similar way. Starting from the AmLi source they represented less than 0.1 of the response to AmBe neutrons. Their response to high energy neutrons was practically the same as to AmBe neutrons. This is important for individual air crew dosimetry on board aircraft. (M.D.)

  17. On the Pressure of a Neutron Gas Interacting with the Non-Uniform Magnetic Field of a Neutron Star

    Science.gov (United States)

    Skobelev, V. V.

    2018-04-01

    On the basis of simple arguments, practically not going beyond the scope of an undergraduate course in general physics, we estimate the additional pressure (at zero temperature) of degenerate neutron matter due to its interaction with the non-uniform magnetic field of a neutron star. This work has methodological and possibly scientific value as an intuitive application of the content of such a course to a solution of topical problems of astrophysics.

  18. Neutron scattering studies of crude oil viscosity reduction with electric field

    Science.gov (United States)

    Du, Enpeng

    topic. Dr. Tao with his group at Temple University, using his electro or magnetic rheological viscosity theory has developed a new technology, which utilizes electric or magnetic fields to change the rheology of complex fluids to reduce the viscosity, while keeping the temperature unchanged. After we successfully reduced the viscosity of crude oil with field and investigated the microstructure changing in various crude oil samples with SANS, we have continued to reduce the viscosity of heavy crude oil, bunker diesel, ultra low sulfur diesel, bio-diesel and crude oil and ultra low temperature with electric field treatment. Our research group developed the viscosity electrorheology theory and investigated flow rate with laboratory and field pipeline. But we never visualize this aggregation. The small angle neutron scattering experiment has confirmed the theoretical prediction that a strong electric field induces the suspended nano-particles inside crude oil to aggregate into short chains along the field direction. This aggregation breaks the symmetry, making the viscosity anisotropic: along the field direction, the viscosity is significantly reduced. The experiment enables us to determine the induced chain size and shape, verifies that the electric field works for all kinds of crude oils, paraffin-based, asphalt-based, and mix-based. The basic physics of such field induced viscosity reduction is applicable to all kinds of suspensions.

  19. Characterisation of ionisation chambers for a mixed radiation field and investigation of their suitability as radiation monitors for the LHC.

    Science.gov (United States)

    Theis, C; Forkel-Wirth, D; Perrin, D; Roesler, S; Vincke, H

    2005-01-01

    Monitoring of the radiation environment is one of the key tasks in operating a high-energy accelerator such as the Large Hadron Collider (LHC). The radiation fields consist of neutrons, charged hadrons as well as photons and electrons with energy spectra extending from those of thermal neutrons up to several hundreds of GeV. The requirements for measuring the dose equivalent in such a field are different from standard uses and it is thus necessary to investigate the response of monitoring devices thoroughly before the implementation of a monitoring system can be conducted. For the LHC, it is currently foreseen to install argon- and hydrogen-filled high-pressure ionisation chambers as radiation monitors of mixed fields. So far their response to these fields was poorly understood and, therefore, further investigation was necessary to prove that they can serve their function well enough. In this study, ionisation chambers of type IG5 (Centronic Ltd) were characterised by simulating their response functions by means of detailed FLUKA calculations as well as by calibration measurements for photons and neutrons at fixed energies. The latter results were used to obtain a better understanding and validation of the FLUKA simulations. Tests were also conducted at the CERF facility at CERN in order to compare the results with simulations of the response in a mixed radiation field. It is demonstrated that these detectors can be characterised sufficiently enough to serve their function as radiation monitors for the LHC.

  20. Neutronic feasibility of PWR core with mixed oxide fuels in the Republic of Korea

    International Nuclear Information System (INIS)

    Kim, Y.J.; Joo, H.K.; Jung, H.G.; Sohn, D.S.

    1997-01-01

    Neutronic feasibility of a PWR core with mixed oxide (MOX) fuels has been investigated as part of the feasibility study for recycling spent fuels in Korea. A typical 3-loop PWR with 900 MWe capacity is selected as reference plant to develop equilibrium core designs with low-leakage fuel management scheme, while incorporating various MOX loading. The fuel management analyses and limited safety analyses show that, safely stated, MOX recycling with 1/3 reload fraction can be accommodated for both annual and 18 month fuel cycle schemes in Korean PWRs, without major design modifications on the reactor systems. (author). 12 refs, 4 figs, 3 tabs

  1. Measurement and modeling of polarized specular neutron reflectivity in large magnetic fields.

    Science.gov (United States)

    Maranville, Brian B; Kirby, Brian J; Grutter, Alexander J; Kienzle, Paul A; Majkrzak, Charles F; Liu, Yaohua; Dennis, Cindi L

    2016-08-01

    The presence of a large applied magnetic field removes the degeneracy of the vacuum energy states for spin-up and spin-down neutrons. For polarized neutron reflectometry, this must be included in the reference potential energy of the Schrödinger equation that is used to calculate the expected scattering from a magnetic layered structure. For samples with magnetization that is purely parallel or antiparallel to the applied field which defines the quantization axis, there is no mixing of the spin states (no spin-flip scattering) and so this additional potential is constant throughout the scattering region. When there is non-collinear magnetization in the sample, however, there will be significant scattering from one spin state into the other, and the reference potentials will differ between the incoming and outgoing wavefunctions, changing the angle and intensities of the scattering. The theory of the scattering and recommended experimental practices for this type of measurement are presented, as well as an example measurement.

  2. The effect of the scalar-isovector meson field on hyperon-rich neutron star matter

    International Nuclear Information System (INIS)

    Mi, Aijun; Zuo, Wei; Li, Ang

    2008-01-01

    We investigate the effect of the scalar-isovector δ-meson field on the equation of state (EOS) and composition of hyperonic neutron star matter, and the properties of hyperonic neutron stars within the framework of the relativistic mean field theory. The influence of the δ-field turns out to be quite different and generally weaker for hyperonic neutron star matter as compared to that for npeμ neutron star matter. We find that inclusion of the δ-field enhances the strangeness content slightly and consequently moderately softens the EOS of neutron star matter in its hyperonic phase. As for the composition of hyperonic star matter, the effect of the δ-field is shown to shift the onset of the negatively-charged (positively-charged) hyperons to slightly lower (higher) densities and to enhance (reduce) their abundances. The influence of the δ-field on the maximum mass of hyperonic neutron stars is found to be fairly weak, whereas inclusion of the δ-field turns out to enhance sizably both the radii and the moments of inertia of neutron stars with given masses. It is also shown that the effects of the δ-field on the properties of hyperonic neutron stars remain similar in the case of switching off the Σ hyperons. (author)

  3. Standardization of radiation protection measurements in mixed fields of an extended energy range

    International Nuclear Information System (INIS)

    Hoefert, M.; Stevenson, G.R.

    1977-01-01

    The improved ICRU concept of dose equivalent index aims at standardizing both area and personnel dose measurements so that the results on the dosimetry of external irradiations in radiation protection become compatible. It seems that for photon and neutron energies up to 3 and 20 MeV respectively the realization of dose-equivalent index is straightforward, but the inclusion of higher energies and/or other types of radiation will lead both to conceptual and practical difficulties. It will be shown that practical measurements in mixed radiation fields of an extended energy range for protection purposes will overestimate the standardized quantity. While area measurements can be performed to represent a good approximation, greater uncertainties have to be accepted in personnel dosimetry for stray radiation fields around GeV proton accelerators

  4. SEL Hardness Assurance in a Mixed Radiation Field

    CERN Document Server

    Garcia Alia, Ruben; Danzeca, Salvatore; Ferlet-Cavrois, Veronique; Frost, Christopher; Gaillard, Remi; Mekki, Julien; Saigné, Frédéric; Thornton, Adam; Uznanski, Slawosz; Worbel, Frédéric; CERN. Geneva. ATS Department

    2015-01-01

    This paper explores the relationship between monoenergetic and mixed-field Single Event Latchup (SEL) cross sections, concluding for components with a very strong energy dependence and highly-energetic environments, test results from monoenergetic or soft mixed-field spectra can significantly underestimate the operational failure rate. We introduce a semi-empirical approach that can be used to evaluate the SEL rate for such environments based on monoenergetic measurements and information or assumptions on the respective sensitive volume and materials surrounding it. We show that the presence of high-Z materials such as tungsten is particularly important in determining the hadron cross section energy dependence for components with relatively large LET thresholds.

  5. Activation product analysis in a mixed sample containing both fission and neutron activation products

    Energy Technology Data Exchange (ETDEWEB)

    Morrison, Samuel S.; Clark, Sue B.; Eggemeyer, Tere A.; Finn, Erin C.; Hines, C. Corey; King, Mathew D.; Metz, Lori A.; Morley, Shannon M.; Snow, Mathew S.; Wall, Donald E.; Seiner, Brienne N.

    2017-11-02

    Activation analysis of gold (Au) is used to estimate neutron fluence resulting from a criticality event; however, such analyses are complicated by simultaneous production of other gamma-emitting fission products. Confidence in neutron fluence estimates can be increased by quantifying additional activation products such as platinum (Pt), tantalum (Ta), and tungsten (W). This work describes a radiochemical separation procedure for the determination of these activation products. Anion exchange chromatography is used to separate anionic forms of these metals in a nitric acid matrix; thiourea is used to isolate the Au and Pt fraction, followed by removal of the Ta fraction using hydrogen peroxide. W, which is not retained on the first anion exchange column, is transposed to an HCl/HF matrix to enhance retention on a second anion exchange column and finally eluted using HNO3/HF. Chemical separations result in a reduction in the minimum detectable activity by a factor of 287, 207, 141, and 471 for 182Ta, 187W, 197Pt, and 198Au respectively, with greater than 90% recovery for all elements. These results represent the highest recoveries and lowest minimum detectable activities for 182Ta, 187W, 197Pt, and 198Au from mixed fission-activation product samples to date, enabling considerable refinement in the measurement uncertainties for neutron fluences in highly complex sample matrices.

  6. A Survey on Mixed Spin P-Fields

    Institute of Scientific and Technical Information of China (English)

    Huai-Liang CHANG; Jun LI; Wei-Ping LI; Chiu-Chu Melissa LIU

    2017-01-01

    The mixed spin P-fields (MSP for short) theory sets up a geometric platform to relate Gromov-Witten invariants of the quintic three-fold and Fan-Jarvis-Ruan-Witten invariants of the quintic polynomial in five variables.It starts with Wittens vision and the P-fields treatment of GW invariants and FJRW invariants.Then it briefly discusses the master space technique and its application to the set-up of the MSP moduli.Some key results in MSP theory are explained and some examples are provided.

  7. Investigation of Fe3O4 Colloid Behaviour in a Magnetic Field by Polarized Neutron Transmission

    International Nuclear Information System (INIS)

    Dokukin, E.B.; Kozhevnikov, S.V.; Nikitenko, Yu.V.; Petrenko, A.V.

    1994-01-01

    Experiments were conducted to measure the dependence of neutron polarization following their transmission through a magnetic colloid on the concentration of magnetic particles, magnetic field strength and wavelength of neutrons. In a magnetic field up to 500 Oe the precession of the neutron polarization is seen. Comparison of the experimental data and theory is made and colloid magnetization is determined. The measurement was carried out with the SPN-1 polarized neutron spectrometer at the high-flux pulsed reactor IBR-2 in Dubna. 7 refs., 2 figs

  8. Polarized X-Ray Emission from Magnetized Neutron Stars: Signature of Strong-Field Vacuum Polarization

    Science.gov (United States)

    Lai, Dong; Ho, Wynn C.

    2003-08-01

    In the atmospheric plasma of a strongly magnetized neutron star, vacuum polarization can induce a Mikheyev-Smirnov-Wolfenstein type resonance across which an x-ray photon may (depending on its energy) convert from one mode into the other, with significant changes in opacities and polarizations. We show that this vacuum resonance effect gives rise to a unique energy-dependent polarization signature in the surface emission from neutron stars. The detection of polarized x rays from neutron stars can provide a direct probe of strong-field quantum electrodynamics and constrain the neutron star magnetic field and geometry.

  9. Polarized x-ray emission from magnetized neutron stars: signature of strong-field vacuum polarization.

    Science.gov (United States)

    Lai, Dong; Ho, Wynn C G

    2003-08-15

    In the atmospheric plasma of a strongly magnetized neutron star, vacuum polarization can induce a Mikheyev-Smirnov-Wolfenstein type resonance across which an x-ray photon may (depending on its energy) convert from one mode into the other, with significant changes in opacities and polarizations. We show that this vacuum resonance effect gives rise to a unique energy-dependent polarization signature in the surface emission from neutron stars. The detection of polarized x rays from neutron stars can provide a direct probe of strong-field quantum electrodynamics and constrain the neutron star magnetic field and geometry.

  10. Degenerate four-wave mixing with the phase diffusion field

    International Nuclear Information System (INIS)

    Anderson, M.H.; Chen, CE.; Elliott, D.S.; Cooper, J.; Smith, S.J.

    1993-01-01

    We report measurements of the effect of laser fluctuations on a strong-field degenerate four-wave mixing interaction, carried out in a nearly Doppler-free, two-level system using a single laser with statistically well-defined phase fluctuations. The counterpropagating pump beams and the probe beam, each split from this phase-noise-modulated source, were fully correlated. The nonlinear medium was an optically-pumped diffuse beam of atomic sodium. By time-delaying the probe with respect to the pump beams, the composite field becomes non-Markovian. Four-wave mixing results in the generation of a phase-conjugate beam anti-parallel to the probe beam. With the laser field spectrum nearly Lorentzian in shape, and with a field linewidth greater (and, for comparison, much narrower) than the natural linewidth of the sodium, we measured the intensity of the phase-conjugate beam as the pump and probe beams were tuned through the D2 resonance, as a function of intensity of die pump beam (up to intensities several times the saturation intensity), and for varying delay between the pump and probe fields. This experiment provides a cleaner measurement of this interaction than any previously available

  11. Comparison of Out-Of-Field Neutron Equivalent Doses in Scanning Carbon and Proton Therapies for Cranial Fields

    DEFF Research Database (Denmark)

    Athar, B.; Henker, K.; Jäkel, O.

    2010-01-01

    Purpose: The purpose of this analysis is to compare the secondary neutron lateral doses from scanning carbon and proton beam therapies. Method and Materials: We simulated secondary neutron doses for out-of-field organs in an 11-year old male patient. Scanned carbon and proton beams were simulated...

  12. Characterization of thermal neutron fields for calibration of neutron monitors in accordance with great equivalent dose environment H⁎(10)

    International Nuclear Information System (INIS)

    Silva, Larissa P. S. da; Silva, Felipe S.; Fonseca, Evaldo S.; Patrao, Karla C.S.; Pereira, Walsan W.

    2017-01-01

    The Laboratório Brasileiro de Nêutrons do Instituto de Radioproteção e Dosimetria (IRD/CNEN) has developed and built a thermal neutron flux facility to provide neutron fluence for dosimeters (Astuto, 2014). This fluency is obtained by four 16 Ci sources 241 AmBe (α, n) positioned around the channel positioned in the center of the Thermal Flow Unit (UFT). The UFT was built with blocks of paraffin with graphite addition and graphite blocks of high purity to obtain a central field with a homogeneous thermal neutron fluence for calibration purposes with the following measurements: 1.2 x 1.2 x 1.2 m 3 . The objective of this work is to characterize several points, in the thermal energy range, in terms of the equivalent ambient dose quantity H⁎(10) for calibration and irradiation of monitors neutrons

  13. Neutron radiography experiments for verification of soluble boron mixing and transport modeling under natural circulation conditions

    International Nuclear Information System (INIS)

    Morlang, M.M.; Feltus, M.A.

    1996-01-01

    The use of neutron radiography for visualization of fluid flow through flow visualization modules has been very successful. Current experiments at the Penn State Breazeale Reactor serve to verify the mixing and transport of soluble boron under natural flow conditions as would be experienced in a pressurized water reactor. Different flow geometries have been modeled including holes, slots, and baffles. Flow modules are constructed of aluminum box material 1 1/2 inches by 4 inches in varying lengths. An experimental flow system was built which pumps fluid to a head tank and natural circulation flow occurs from the head tank through the flow visualization module to be radio-graphed. The entire flow system is mounted on a portable assembly to allow placement of the flow visualization module in front of the neutron beam port. A neutron-transparent fluor-inert fluid is used to simulate water at different densities. Boron is modeled by gadolinium oxide powder as a tracer element, which is placed in a mixing assembly and injected into the system a remotely operated electric valve, once the reactor is at power. The entire sequence is recorded on real-time video. Still photographs are made frame-by-frame from the video tape. Computers are used to digitally enhance the video and still photographs. The data obtained from the enhancement will be used for verification of simple geometry predictions using the TRAC and RELAP thermal-hydraulic codes. A detailed model of a reactor vessel inlet plenum, downcomer region, flow distribution area and core inlet is being constructed to model the APGOO plenum. Successive radiography experiments of each section of the model under identical conditions will provide a complete vessel / core model for comparison with the thermal-hydraulic codes

  14. Neutron radiography experiments for verification of soluble boron mixing and transport modeling under natural circulation conditions

    International Nuclear Information System (INIS)

    Feltus, M.A.; Morlang, G.M.

    1996-01-01

    The use of neutron radiography for visualization of fluid flow through flow visualization modules has been very successful. Current experiments at the Penn State Breazeale Reactor serve to verify the mixing and transport of soluble boron under natural flow conditions as would be experienced in a pressurized water reactor. Different flow geometries have been modeled including holes, slots, and baffles. Flow modules are constructed of aluminum box material 1 1/2 inches by 4 inches in varying lengths. An experimental flow system was built which pumps fluid to a head tank and natural circulation flow occurs from the head tank through the flow visualization module to be radiographed. The entire flow system is mounted on a portable assembly to allow placement of the flow visualization module in front of the neutron beam port. A neutron-transparent fluorinert fluid is used to simulate water at different densities. Boron is modeled by gadolinium oxide powder as a tracer element, which is placed in a mixing assembly and injected into the system by remote operated electric valve, once the reactor is at power. The entire sequence is recorded on real-time video. Still photographs are made frame-by-frame from the video tape. Computers are used to digitally enhance the video and still photographs. The data obtained from the enhancement will be used for verification of simple geometry predictions using the TRAC and RELAP thermal-hydraulic codes. A detailed model of a reactor vessel inlet plenum, downcomer region, flow distribution area and core inlet is being constructed to model the AP600 plenum. Successive radiography experiments of each section of the model under identical conditions will provide a complete vessel/core model for comparison with the thermal-hydraulic codes

  15. A {mu}TPC detector for the characterization of low energy neutron fields

    Energy Technology Data Exchange (ETDEWEB)

    Golabek, C., E-mail: cedric.golabek@irsn.fr [Laboratoire de Metrologie et de Dosimetrie des Neutrons, IRSN Cadarache, 13115 Saint-Paul-Lez-Durance (France); Billard, J. [Laboratoire de Physique Subatomique et de Cosmologie, Universite Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut Polytechnique de Grenoble, 53 rue des Martyrs, 38026 Grenoble (France); Allaoua, A. [Laboratoire de Metrologie et de Dosimetrie des Neutrons, IRSN Cadarache, 13115 Saint-Paul-Lez-Durance (France); Bosson, G.; Bourrion, O.; Grignon, C.; Guillaudin, O. [Laboratoire de Physique Subatomique et de Cosmologie, Universite Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut Polytechnique de Grenoble, 53 rue des Martyrs, 38026 Grenoble (France); Lebreton, L., E-mail: lena.lebreton@irsn.fr [Laboratoire de Metrologie et de Dosimetrie des Neutrons, IRSN Cadarache, 13115 Saint-Paul-Lez-Durance (France); Mayet, F. [Laboratoire de Physique Subatomique et de Cosmologie, Universite Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut Polytechnique de Grenoble, 53 rue des Martyrs, 38026 Grenoble (France); Petit, M. [Laboratoire de Metrologie et de Dosimetrie des Neutrons, IRSN Cadarache, 13115 Saint-Paul-Lez-Durance (France); Richer, J.-P.; Santos, D. [Laboratoire de Physique Subatomique et de Cosmologie, Universite Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut Polytechnique de Grenoble, 53 rue des Martyrs, 38026 Grenoble (France)

    2012-06-21

    The AMANDE facility produces monoenergetic neutron fields from 2 keV to 20 MeV for metrological purposes. To be considered as a reference facility, fluence and energy distributions of neutron fields have to be determined by primary measurement standards. For this purpose, a micro Time Projection Chamber is being developed to be dedicated to measure neutron fields with energy ranging from 8 keV up to 1 MeV. In this work we present simulations showing that such a detector, which allows the measurement of the ionization energy and the 3D reconstruction of the recoil nucleus, provides the determination of neutron energy and fluence of these neutron fields.

  16. Dosimetry Characterization of the Neutron Fields of the Intermediate Temporary Storage of the Trillo Nuclear Power Plant

    International Nuclear Information System (INIS)

    Campo Blanco, X.

    2015-01-01

    The Neutron Standards Laboratory of CIEMAT, in collaboration with the Trillo Nuclear Power Plant, has conducted a detailed dosimetric and spectrometric characterization of the neutron fields at the Intermediate Temporary Storage of the Trillo Nuclear Power Plant, as well as the neutron fields of ENSA-DPT spent fuel casks. For neutron measurements, neutron monitors and a Bonner spheres spectrometry system have been used. In addition, a Monte Carlo model of the installation and the cask has been developed and validated.

  17. Asymmetry of neutrino emission from neutron beta-decay in superdense matter and strong magnetic field

    International Nuclear Information System (INIS)

    Kauts, V.L.; Savochkin, A.M.; Studenikin, A.I.

    2006-01-01

    Exact solution of Dirac equation for charged particles in homogenous magnetic field for computation of probability in presence of degenerate magnetized Fermi-gas consisting of protons, neutrons, and electrons has been used. Angular distribution of antineutrino momenta is investigated. Values of main parameters of medium is realistic for physics of neutron stars. This investigation may be applied for consideration of cooling of neutron stars [ru

  18. Spin-polarized neutron matter at different orders of chiral effective field theory

    OpenAIRE

    Sammarruca, F.; Machleidt, R.; Kaiser, N.

    2015-01-01

    Spin-polarized neutron matter is studied using chiral two- and three-body forces. We focus, in particular, on predictions of the energy per particle in ferromagnetic neutron matter at different orders of chiral effective field theory and for different choices of the resolution scale. We discuss the convergence pattern of the predictions and their cutoff dependence. We explore to which extent fully polarized neutron matter behaves (nearly) like a free Fermi gas. We also consider the more gener...

  19. Ten year's activity in the field of neutron scattering workshop

    International Nuclear Information System (INIS)

    Hamaguchi, Yoshikazu

    2003-01-01

    'Neutron scattering' is in the frame of the 'Utilization of Research Reactor's of the FNCA (Forum for Nuclear Cooperation in Asia) project, which held the workshops from FY 1992. This report is a summary of the results and activities of neutron scattering workshops and sub-workshops since the start in FY 1992. (author)

  20. Applications of Bonner sphere detectors in neutron field dosimetry

    International Nuclear Information System (INIS)

    Awschalom, M.; Sanna, R.S.

    1983-09-01

    The theory of neutron moderation and spectroscopy are briefly reviewed, and moderators that are useful for Bonner sphere spectrometers are discussed. The choice of the neutron detector for a Bonner sphere spectrometer is examined. Spectral deconvolution methods are briefly reviewed, including derivative, parametric, quadrature, and Monte Carlo methods. Calibration is then discussed

  1. Position sensitive detection of neutrons in high radiation background field.

    Science.gov (United States)

    Vavrik, D; Jakubek, J; Pospisil, S; Vacik, J

    2014-01-01

    We present the development of a high-resolution position sensitive device for detection of slow neutrons in the environment of extremely high γ and e(-) radiation background. We make use of a planar silicon pixelated (pixel size: 55 × 55 μm(2)) spectroscopic Timepix detector adapted for neutron detection utilizing very thin (10)B converter placed onto detector surface. We demonstrate that electromagnetic radiation background can be discriminated from the neutron signal utilizing the fact that each particle type produces characteristic ionization tracks in the pixelated detector. Particular tracks can be distinguished by their 2D shape (in the detector plane) and spectroscopic response using single event analysis. A Cd sheet served as thermal neutron stopper as well as intensive source of gamma rays and energetic electrons. Highly efficient discrimination was successful even at very low neutron to electromagnetic background ratio about 10(-4).

  2. Determining of the intermediate neutron spectrum in fast neutron field at the RB reactor

    International Nuclear Information System (INIS)

    Sokcic-Kostic, M.; Pesic, M.; Antic, D.

    1987-01-01

    The activation method for intermediate neutron spectrum determination is given in this paper. The intermediate neutron spectrum in experimental fuel channel (EFC) at the RB reactor is determined om the basis of this method. The results of measurements are treated with PRAG code and will be treated with KRIFIT and TENET codes that are also developed. (author)

  3. Strongly coupled chameleon fields: Possible test with a neutron Lloyd's mirror interferometer

    International Nuclear Information System (INIS)

    Pokotilovski, Yu.N.

    2013-01-01

    The consideration of possible neutron Lloyd's mirror interferometer experiment to search for strongly coupled chameleon fields is presented. The chameleon scalar fields were proposed to explain the acceleration of expansion of the Universe. The presence of a chameleon field results in a change of a particle's potential energy in vicinity of a massive body. This interaction causes a phase shift of neutron waves in the interferometer. The sensitivity of the method is estimated

  4. Strongly coupled chameleon fields: Possible test with a neutron Lloyd's mirror interferometer

    Energy Technology Data Exchange (ETDEWEB)

    Pokotilovski, Yu.N., E-mail: pokot@nf.jinr.ru [Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region (Russian Federation)

    2013-02-26

    The consideration of possible neutron Lloyd's mirror interferometer experiment to search for strongly coupled chameleon fields is presented. The chameleon scalar fields were proposed to explain the acceleration of expansion of the Universe. The presence of a chameleon field results in a change of a particle's potential energy in vicinity of a massive body. This interaction causes a phase shift of neutron waves in the interferometer. The sensitivity of the method is estimated.

  5. New experimental research stand SVICKA neutron field analysis using neutron activation detector technique

    Science.gov (United States)

    Varmuza, Jan; Katovsky, Karel; Zeman, Miroslav; Stastny, Ondrej; Haysak, Ivan; Holomb, Robert

    2018-04-01

    Knowledge of neutron energy spectra is very important because neutrons with various energies have a different material impact or a biological tissue impact. This paper presents basic results of the neutron flux distribution inside the new experimental research stand SVICKA which is located at Brno University of Technology in Brno, Czech Republic. The experiment also focused on the investigation of the sandwich biological shielding quality that protects staff against radiation effects. The set of indium activation detectors was used to the investigation of neutron flux distribution. The results of the measurement provide basic information about the neutron flux distribution inside all irradiation channels and no damage or cracks are present in the experimental research stand biological shielding.

  6. Compact deuterium-tritium neutron generator using a novel field ionization source

    Energy Technology Data Exchange (ETDEWEB)

    Ellsworth, J. L., E-mail: ellsworth7@llnl.gov; Falabella, S.; Sanchez, J.; Tang, V. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States); Wang, H. [Department of Computer Science, Stanford University, Stanford, California 94305 (United States)

    2014-11-21

    Active interrogation using neutrons is an effective method for detecting shielded nuclear material. A lightweight, lunch-box-sized, battery-operated neutron source would enable new concepts of operation in the field. We have developed at-scale components for a highly portable, completely self-contained, pulsed Deuterium-Tritium (DT) neutron source producing 14 MeV neutrons with average yields of 10{sup 7} n/s. A gated, field ionization ion source using etched electrodes has been developed that produces pulsed ion currents up to 500 nA. A compact Cockcroft-Walton high voltage source is used to accelerate deuterons into a metal hydride target for neutron production. The results of full scale DT tests using the field ionization source are presented.

  7. Effect of neutrons scattered from boundary of neutron field on shielding experiment

    International Nuclear Information System (INIS)

    Ogawa, Tatsuhiko; Abe, Takuya; Kosako, Toshiso; Iimoto, Takeshi

    2009-01-01

    Neutron shielding experiment with 49 cm-thick ordinary concrete was carried out at the reactor 'Yayoi' The University of Tokyo. System of this experiment is enclosed by heavy concrete where neutrons backscattered from heavy concrete likely affected neutron flux on the back surface of shielding concrete. Reaction rate of 197 Au(n, γ), cadmium covered 197 Au(n, γ) and 115 In(n, n') in the shielding concrete was measured using foil activation method. Neutron transport calculation was carried out in order to simulate reaction rate by calculating neutron spectra and convoluting with neutron capture cross-section in neutron shielding concrete. Comparison was made between calculated reaction rate and experimental one, and almost satisfactory agreement was found except for the back surface of shielding. To compose adequate simulation model, description of heavy concrete behind the shielding was thought to be of importance. For example, disregarding neutrons backscattered from heavy concrete, calculation underestimated reaction rate by the factor of 10. In another example, assuming that chemical composition of heavy concrete is equal to the composition adopted from a literature, the reaction rate was overestimated by factor of 5. By making the composition of heavy concrete equal to that based on facility design, overestimation was found to be the factor of 2. Therefore, adequate description of chemical composition of heavy concrete is found to be of importance in order to simulate neutron induced reaction rate on the back surface of neutron shielding concrete in shielding experiment performed in a system enclosed by heavy concrete. (author)

  8. INVESTIGATION OF SECONDARY MIXED RADIATION FIELD AROUND A MEDICAL LINEAR ACCELERATOR.

    Science.gov (United States)

    Tulik, Piotr; Tulik, Monika; Maciak, Maciej; Golnik, Natalia; Kabat, Damian; Byrski, Tomasz; Lesiak, Jan

    2017-09-29

    The aim of this study is to investigate secondary mixed radiation field around linac, as the first part of an overall assessment of out-of-field contribution of neutron dose for new advanced radiation dose delivery techniques. All measurements were performed around Varian Clinic 2300 C/D accelerator at Maria Sklodowska-Curie Memorial, Cancer Center and Institute of Oncology, Krakow Branch. Recombination chambers REM-2 and GW2 were used for recombination index of radiation quality Q4 determination (as an estimate of quality factor Q), measurement of total tissue dose Dt and calculation of gamma and neutron components to Dt. Estimation of Dt and Q4 allowed for the ambient dose equivalent H*(10) per monitor unit (MU) calculations. Measurements around linac were performed on the height of the middle of the linac's head (three positions) and on the height of the linac's isocentre (five positions). Estimation of secondary radiation level was carried out for seven different configurations of upper and lower jaws position and multileaf collimator set open or closed in each position. Study includes the use of two photon beam modes: 6 and 18 MV. Spatial distribution of ambient dose equivalent H*(10) per MU on the height of the linac's head and on the standard couch height for patients during the routine treatment, as well as relative contribution of gamma and neutron secondary radiation inside treatment room were evaluated. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  9. Axial distribution of absorbed doses in fast neutron field at the RB reactor

    International Nuclear Information System (INIS)

    Sokcic-Kostic, M.; Pesic, M.; Antic, D.; Ninkovic, M.

    1988-11-01

    The coupled fast thermal system CFTS at the RB reactor is created for obtaining fast neutron fields. The axial distribution of fast neutron flux density in its second configuration (CFTS-2) is measured. The axial distribution of absorbed doses is computed on the basis of mentioned experimental results. At the end these experimental and computed results are given. (Author)

  10. Gamma ray bursts from comet neutron star magnetosphere interaction, field twisting and Eparallel formation

    International Nuclear Information System (INIS)

    Colgate, S.A.

    1990-01-01

    Consider the problem of a comet in a collision trajectory with a magnetized neutron star. The question addressed in this paper is whether the comet interacts strongly enough with a magnetic field such as to capture at a large radius or whether in general the comet will escape a magnetized neutron star. 6 refs., 4 figs

  11. Designing research of fast neutron radiation field based on the reactor

    International Nuclear Information System (INIS)

    Zhang Wenzhong; Zhang Xiaomin

    2009-01-01

    Based on the Tsinghua University experimental nuclear reactor neutron source, this research designed moderate theory technical scheme, and the thickness of materials in the scheme were selected by means of Monte Carlo simulating method. An fast neutron radiation field was gained. (authors)

  12. Program system for calculating streaming neutron radiation field in reactor cavity

    International Nuclear Information System (INIS)

    He Zhongliang; Zhao Shu.

    1986-01-01

    The A23 neutron albedo data base based on Monte Carlo method well agrees with SAIL albedo data base. RSCAM program system, using Monte Carlo method with albedo approach, is used to calculate streaming neutron radiation field in reactor cavity and containment operating hall. The dose rate distributions calculated with RSCAM in square concrete duct well agree with experiments

  13. Deficiency in Monte Carlo simulations of coupled neutron-gamma-ray fields

    NARCIS (Netherlands)

    Maleka, Peane P.; Maucec, Marko; de Meijer, Robert J.

    2011-01-01

    The deficiency in Monte Carlo simulations of coupled neutron-gamma-ray field was investigated by benchmarking two simulation codes with experimental data. Simulations showed better correspondence with the experimental data for gamma-ray transport only. In simulations, the neutron interactions with

  14. Assessment of radiation fields from neutron irradiated structural components of the 40 MW research reactor CIRUS

    International Nuclear Information System (INIS)

    Sankaranarayanan, S.; Sharma, S.K.

    1993-01-01

    The paper summarizes the results of an assessment of the radiation fields from the long-lived neutron activation products (including the decay chain products) in the various structural components of the CIRUS reactor. Special attention is given for the analysis of neutron activation of impurity elements present in the materials of the structure. 16 refs, 4 figs, 4 tabs

  15. Cold neutron interaction with a classical electric field: Some basic theoretical and experimental considerations

    International Nuclear Information System (INIS)

    Bruce, S.; Diaz-Valdes, J.; Bennun, L.; Minning, P.C.

    2008-01-01

    We explore the feasibility of performing an experiment to measure the interaction of cold neutrons with a given classical electric field. Bound and scattering states could be detected by means of an approximate Aharonov-Casher configuration. The theoretical background is presented and then some primary elements for building a neutron detector of this nature are proposed

  16. Neutron Star Structure in the Presence of Conformally Coupled Scalar Fields

    Science.gov (United States)

    Sultana, Joseph; Bose, Benjamin; Kazanas, Demosthenes

    2014-01-01

    Neutron star models are studied in the context of scalar-tensor theories of gravity in the presence of a conformally coupled scalar field, using two different numerical equations of state (EoS) representing different degrees of stiffness. In both cases we obtain a complete solution by matching the interior numerical solution of the coupled Einstein-scalar field hydrostatic equations, with an exact metric on the surface of the star. These are then used to find the effect of the scalar field and its coupling to geometry, on the neutron star structure, particularly the maximum neutron star mass and radius. We show that in the presence of a conformally coupled scalar field, neutron stars are less dense and have smaller masses and radii than their counterparts in the minimally coupled case, and the effect increases with the magnitude of the scalar field at the center of the star.

  17. Neutron scattering study of magnetic and crystalline electirc field interactions in RCrO3

    International Nuclear Information System (INIS)

    Shamir, N.

    1978-05-01

    Magnetic and crystalline electric field interactions in the compounds RCrO 3 (R-rare earth) , were studied by neutron scattering. Elastic neutron scattering was utilized in the study of the temperature dependence of the Cr 3+ and Ho 3+ magnetic reflections in Lu CrO 3 and HoCrO 3 , respectively. Analysis of this temperature dependence yielde constant canting angles for the Cr 3+ and Ho 3+ magnetic moments. Molecular magnetic field constants and crystalline electric field splitting were also calculated from the temperature dependence of the Ho 3+ magnetic reflection. These parameters were obtained directly by inelastic neutron scattering measurement. Inelastic neutron scattering measurements of crystlline electric field transitions of R 3+ (R=Pr, Nd, Tb, Ho, Er, Tm, Yb) in RCrO 3 , formed the basis for the calculation of the common crystalline electirc field parameters of the heavy R 3+ ions. (author)

  18. Mixed Field Modification of Thermally Cured Castor Oil Based Polyurethanes

    International Nuclear Information System (INIS)

    Mortley, A.

    2006-01-01

    Thermally cured polyurethanes were prepared from castor oil and hexamethylene diisocyanatee (HMDI). Due to the long aliphatic chain of the castor oil component of polyurethane, thermal curing of castor oil based polyurethane (COPU) is limited by increasing polymer viscosity. To enhance further crosslinking, COPUs were subjected to a range of accumulated doses (0.0-3.0 MGy) produced by the mixed ionizing field of the SLOWPOKE-2 research reactor. The physico-mechanical properties of COPU, unirradiated and irradiated, were characterized by mechanical tests. Increased bond formation resulting from radiation-induced crosslinking was confirmed by favorable increases in mechanical properties and by solid-state 13 C -NMR and FTIR spectra

  19. Characterization of TL dosimeters for determination of the gamma component in a mixed n+γ radiation field

    International Nuclear Information System (INIS)

    Ranogajec-Komor, M.; Miljanic, S.; Ferek, S.; Dvornik, I.; Osvay, M.

    1996-01-01

    In the International Intercomparison of the Criticality Accident Dosimetry Systems organized by the Commission of European Communities at SILENE Reactor in Valduc, France, 1993, the Ruder Boskovic Institute (RBI) measured the total neutron and gamma tissue absorbed dose (D n+γ ) at the body surface irrespective of neutron and gamma energy spectra variations using the chemical dosimeters DL-M4. For deriving the neutron dose i.e recoil dose, D n , from the differences D n = D n+γ - D t , the total gamma dose (D tγ ) has to be measured with highest accuracy. The determination of the gamma dose in a mixed field is complicated because TL dosimeters are sensitive both to neutrons and gammas. Besides, the radiation doses and energy spectra vary because of scattering and absorption in the body or phantom. Therefore dosimeters with different sensitivities, energy dependences and encapsulations have to be used. In this paper only the study of some characteristics of various TL detectors, such as sensitivity, linearity, supralinearity and fading, for measurement of the gamma component are described. These investigations were carried out in RBI before and after the Valduc intercomparison experiments. The encapsulations, TL response corrections for thermal and fast neutron effects as well as the discussion of Valduc results will be published later

  20. Study of the neutron field in the vicinity of an unshielded PET cyclotron

    International Nuclear Information System (INIS)

    Mendez, R; Iniguez, M P; MartI-Climent, J M; Penuelas, I; Vega-Carrillo, H R; Barquero, R

    2005-01-01

    The neutron field in the proximity of an unshielded PET cyclotron was investigated during 18 F radioisotope production with an 18 MeV proton beam. Thermoluminescent detector (TLD) models TLD600 and TLD700 as well as Bonner moderating spheres were irradiated at different positions inside the vault room where the cyclotron is located to determine the thermal neutron flux, neutron spectrum and dose equivalent. Furthermore, from a combination of measurements and Monte Carlo simulations the neutron source intensity at the target was estimated. The resulting intensity is in good agreement with the IAEA recommendations. Neutron doses derived from the measured spectra were found to vary between 7 and 320 mSv per 1 μA h of proton-integrated current. Finally, gamma doses were determined from TLD700 readings and amounted to around 10% of the neutron doses

  1. Study of the neutron field in the vicinity of an unshielded PET cyclotron

    Energy Technology Data Exchange (ETDEWEB)

    Mendez, R [Dpto. Fisica Teorica, Atomica y Optica, Universidad de Valladolid (Spain); Iniguez, M P [Dpto. Fisica Teorica, Atomica y Optica, Universidad de Valladolid (Spain); MartI-Climent, J M [Servicio de Medicina Nuclear, ClInica Universitaria de Navarra (Spain); Penuelas, I [Servicio de Medicina Nuclear, ClInica Universitaria de Navarra (Spain); Vega-Carrillo, H R [Dpto. Estudios Nucleares, IngenierIa Electrica, Matematicas, Universidad Autonoma de Zacatecas (Mexico); Barquero, R [Hospital Universitario RIo Hortega, Valladolid (Spain)

    2005-11-07

    The neutron field in the proximity of an unshielded PET cyclotron was investigated during {sup 18}F radioisotope production with an 18 MeV proton beam. Thermoluminescent detector (TLD) models TLD600 and TLD700 as well as Bonner moderating spheres were irradiated at different positions inside the vault room where the cyclotron is located to determine the thermal neutron flux, neutron spectrum and dose equivalent. Furthermore, from a combination of measurements and Monte Carlo simulations the neutron source intensity at the target was estimated. The resulting intensity is in good agreement with the IAEA recommendations. Neutron doses derived from the measured spectra were found to vary between 7 and 320 mSv per 1 {mu}A h of proton-integrated current. Finally, gamma doses were determined from TLD700 readings and amounted to around 10% of the neutron doses.

  2. Coulomb Excitation of a Neutron-Rich $^{88}$Kr Beam Search for Mixed Symmetry States

    CERN Multimedia

    Andreoiu, C; Napiorkowski, P J; Iwanicki, J S

    2002-01-01

    We propose to use the ISOLDE/REX/MINIBALL/CD set-up to perform a Coulomb Excitation experiment with a $^{88}$Kr radioactive beam. The motivation includes a search for $Mixed$ $Symmetry$ states predicted by the IBM-2 model, gathering more spectroscopy data about the $^{88}$Kr nucleus and extending shape coexistence studies (performed previously by the proposers for neutron-deficient Kr isotopes) to the neutron-rich side. The proposed experiment will provide data complementary to the Coulomb Excitation of a relativistic $^{88}$Kr beam proposed by D. Tonev et al. for a RISING experiment. A total of 12 days of beam time is necessary for the experiment, equally divided into two runs. One run with a 2.2 MeV/A beam energy on a $^{48}$Ti target and a second run with the maximum available REX energy of 3.1 MeV/A on a $^{208}$Pb target are requested. Using either a UC$_{x}$ or ThC$_{x}$ fissioning primary target coupled with a plasma source by a cooled transfer line seems to be the best choice for the proposed experime...

  3. Kinetic studies of methane-ethane mixed gas hydrates by neutron diffraction and Raman spectroscopy.

    Science.gov (United States)

    Murshed, M Mangir; Kuhs, Werner F

    2009-04-16

    In situ formations of CH(4)-C(2)H(6) mixed gas hydrates were made using high flux neutron diffraction at 270 K and 5 MPa. For this purpose, a feed gas composition of CH(4) and C(2)H(6) (95 mol% CH(4)) was employed. The rates of transformation of spherical grains of deuterated ice Ih into hydrates were measured by time-resolved neutron powder diffraction on D20 at ILL, Grenoble. Phase fractions of the crystalline constituents were obtained from Rietveld refinements. A concomitant formation of structure type I (sI) and structure type II (sII) hydrates were observed soon after the gas pressure was applied. The initial fast formation of sII hydrate reached its maximum volume and started declining very slowly. The formation of sI hydrate followed a sigmoid growth kinetics that slowed down due to diffusion limitation. This observation has been interpreted in terms of a kinetically favored nucleation of the sII hydrate along with a slow transformation into sI. Both powder diffraction and Raman spectroscopic results suggest that a C(2)H(6)-rich sII hydrate was formed at the early part of the clathration, which slowly decreased to approximately 3% after a reaction of 158 days as confirmed by synchrotron XRD. The final persistence of a small portion of sII hydrate points to a miscibility gap between CH(4)-rich sI and C(2)H(6)-rich sII hydrates.

  4. Revisiting Field Burial by Accretion onto Neutron Stars

    Indian Academy of Sciences (India)

    Dipanjan Mukherjee

    2017-09-12

    Sep 12, 2017 ... review the recent work on magnetic confinement of accreted matter on neutron stars poles. We present ..... hours to days, see Brown & Bildsten 1998) where the ...... Radhakrishnan, V., Srinivasan, G. 1984, in: Second Asian-.

  5. Neutronic analysis concerning the utilization of mixed U N-Pu N nitride fuel for fast reactors

    International Nuclear Information System (INIS)

    Renke, C.A.C.; Batista, J.L.; Waintraub, M.; Santos Bastos, W. dos; Brito Aghina, L.O. de.

    1991-08-01

    Neutronic behavior of mixed UN-PuN nitride fuel in substitution of the mixed oxide U O 2 - Pu O 2 for fast reactors is discussed with focus on Super Phenix I. Characteristics parameters of both cores are calculated and compared and the results presented show a great advantage for the nitride fuel, pointing out a larger performance of fuel elements in the core and an effective reduction of reactivity loss during the cycle. (author)

  6. Evaluation of area monitor response for neutrons in radiation field generated by a 15 MV clinic accelerator; Avaliacao da resposta dos monitores de area para neutrons em campo de radiacao gerado por um acelerador clinico de 15 MV

    Energy Technology Data Exchange (ETDEWEB)

    Salgado, Ana Paula

    2011-07-01

    The clinical importance and usage of linear accelerators in cancer treatment increased significantly in the last years. Coupled with this growth came the concern about the use of accelerators with energies over to 10 MeV which produce therapeutic beam contaminated with neutrons generated when high-energy photons interact with high-atomic-number materials such as tungsten and lead present in the accelerator itself. At these facilities, measurements of the ambient dose equivalent for neutrons present difficulties owing to the existence of a mixed radiation field and possible electromagnetic interference near the accelerator. The Neutron Laboratory of the IRD - Brazilian Institute for Radioprotection and Dosimetry, aiming to evaluate the survey meters performance at these facilities, initiated studies of instrumentation response in the presence of different neutron spectra. Neutrons sources with average energies ranging from 0.55 to 4.2 MeV, four different survey meters and one ionization chamber to obtain the ratio between the dose due to neutrons and gamma radiation were used in this work. The evaluation of these measurements, performed in a 15 MV linear accelerator room is presented. This work presents results that demonstrate the complexity and care needed to make neutrons measurements in radiotherapy treatment rooms containing high energy clinical accelerators. (author)

  7. Instrument intercomparison in the high-energy mixed field at the CERN-EU reference field (CERF) facility.

    Science.gov (United States)

    Caresana, Marco; Helmecke, Manuela; Kubancak, Jan; Manessi, Giacomo Paolo; Ott, Klaus; Scherpelz, Robert; Silari, Marco

    2014-10-01

    This paper discusses an intercomparison campaign performed in the mixed radiation field at the CERN-EU (CERF) reference field facility. Various instruments were employed: conventional and extended-range rem counters including a novel instrument called LUPIN, a bubble detector using an active counting system (ABC 1260) and two tissue-equivalent proportional counters (TEPCs). The results show that the extended range instruments agree well within their uncertainties and within 1σ with the H*(10) FLUKA value. The conventional rem counters are in good agreement within their uncertainties and underestimate H*(10) as measured by the extended range instruments and as predicted by FLUKA. The TEPCs slightly overestimate the FLUKA value but they are anyhow consistent with it when taking the comparatively large total uncertainties into account, and indicate that the non-neutron part of the stray field accounts for ∼30 % of the total H*(10). © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  8. Time-Dependent Neutron and Photon Dose-Field Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Wooten, Hasani Omar [Georgia Inst. of Technology, Atlanta, GA (United States)

    2005-08-01

    A unique tool is developed that allows the user to model physical representations of complicated glovebox facilities in two dimensions and determine neutral-particle flux and ambient dose-equivalent fields throughout that geometry. The Pandemonium code, originally designed to determine flux and dose-rates only, is improved to include realistic glovebox geometries, time-dependent source and detector positions, time-dependent shielding thickness calculations, time-integrated doses, a representative criticality accident scenario based on time-dependent reactor kinetics, and more rigorous photon treatment. A primary benefit of this work has been an extensive analysis and improvement of the photon model that is not limited to the application described in this thesis. The photon model has been extended in energy range to 10 MeV to include photons from fission and new photon buildup factors have been included that account for the effects of photon buildup at slant-path thicknesses as a function of angle, where the mean free path thickness has been preserved. The overall system of codes is user-friendly and it is directly applicable to facilities such as the plutonium facility at Los Alamos National Laboratory, where high-intensity neutron and photon emitters are regularly used. The codes may be used to determine a priori doses for given work scenarios in an effort to supply dose information to process models which will in turn assist decision makers on ensuring as low as reasonably achievable (ALARA) compliance. In addition, coupling the computational results of these tools with the process model visualization tools will help to increase worker safety and radiological safety awareness.

  9. Measurement of Neutron Field Characteristics at Nuclear-Physics Instalations for Personal Radiation Monitoring

    CERN Document Server

    Alekseev, A G; Britvich, G I; Kosyanenko, E V; Pikalov, V A; Gomonov, I P

    2003-01-01

    n this work the observed data of neutron spectra on Rostov NEP, Kursk NEP and Smolensk NEP and on the reactor IRT MIPHI are submitted. For measurement of neutron spectra two types of spectrometer were used: SHANS (IHEP design ) and SDN-MS01 (FEI design). The comparison of the data measurements per-formed by those spectrometers above one-type cells on the reactor RBMK is submitted. On the basis of the 1-st horizontal experimental channel HEC-1 of the IRT reactor 4 reference fields of neutrons are investigated. It is shown, that spectra of neutrons of reference fields can be used for imitation of neutron spectra for conditions of NEP with VVER and RBMK type reactors.

  10. A high-field adiabatic fast passage ultracold neutron spin flipper for the UCNA experiment

    Energy Technology Data Exchange (ETDEWEB)

    Holley, A. T.; Pattie, R. W.; Young, A. R. [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695 (United States); Broussard, L. J. [Department of Physics, Duke University, Durham, North Carolina 27708 (United States); Davis, J. L.; Ito, T. M.; Lyles, J. T. M.; Makela, M.; Morris, C. L.; Mortensen, R.; Saunders, A. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Hickerson, K.; Mendenhall, M. P. [W. K. Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125 (United States); Liu, C.-Y. [Department of Physics, Indiana University, Bloomington, Indiana 47405 (United States); Mammei, R. R. [Department of Physics, Virginia Tech, Blacksburg, Virginia 24061 (United States); Rios, R. [Department of Physics, Idaho State University, Pocatello, Idaho 83209 (United States)

    2012-07-15

    The UCNA collaboration is making a precision measurement of the {beta} asymmetry (A) in free neutron decay using polarized ultracold neutrons (UCN). A critical component of this experiment is an adiabatic fast passage neutron spin flipper capable of efficient operation in ambient magnetic fields on the order of 1 T. The requirement that it operate in a high field necessitated the construction of a free neutron spin flipper based, for the first time, on a birdcage resonator. The design, construction, and initial testing of this spin flipper prior to its use in the first measurement of A with UCN during the 2007 run cycle of the Los Alamos Neutron Science Center's 800 MeV proton accelerator is detailed. These studies determined the flipping efficiency of the device, averaged over the UCN spectrum present at the location of the spin flipper, to be {epsilon}=0.9985(4).

  11. Absorbed dose conversion coefficients for embryo and foetus in neutron fields

    International Nuclear Information System (INIS)

    Chen, J.

    2007-01-01

    The Monte Carlo code MCNPX has been used to determine mean absorbed doses to the embryo and foetus when the mother is exposed to neutron fields. There are situations, such as on-board aircraft, where high-energy neutrons are often peaked in top down (TOP) direction. In addition to previous publications for standard irradiation geometries, this study provides absorbed dose conversion coefficients for the embryo of 8 weeks and the foetus of 3, 6 or 9 months at TOP irradiation geometry. The conversion coefficients are compared with the coefficients in isotropic irradiation (ISO). With increasing neutron energies, the conversion coefficients in TOP irradiation become dominant. A set of conversion coefficients is constructed from the higher value in either ISO or TOP irradiation at a given neutron energy. In cases where the irradiation geometry is not adequately known, this set of conversion coefficients can be used in a conservative dose assessment for embryo and foetus in neutron fields. (authors)

  12. Topological currents in neutron stars: kicks, precession, toroidal fields, and magnetic helicity

    International Nuclear Information System (INIS)

    Charbonneau, James; Zhitnitsky, Ariel

    2010-01-01

    The effects of anomalies in high density QCD are striking. We consider a direct application of one of these effects, namely topological currents, on the physics of neutron stars. All the elements required for topological currents are present in neutron stars: degenerate matter, large magnetic fields, and parity violating processes. These conditions lead to the creation of vector currents capable of carrying momentum and inducing magnetic fields. We estimate the size of these currents for many representative states of dense matter in the neutron star and argue that they could be responsible for the large proper motion of neutron stars (kicks), the toroidal magnetic field and finite magnetic helicity needed for stability of the poloidal field, and the resolution of the conflict between type-II superconductivity and precession. Though these observational effects appear unrelated, they likely originate from the same physics — they are all P-odd phenomena that stem from a topological current generated by parity violation

  13. Intraoperative boron neutron capture therapy for malignant gliomas. First clinical results of Tsukuba phase I/II trial using JAERI mixed thermal-epithermal beam

    International Nuclear Information System (INIS)

    Matsumura, A.; Yamamoto, T.; Shibata, Y.

    2000-01-01

    Since October 1999, a clinical trial of intraoperative boron neutron capture therapy (IOBNCT) is in progress at JRR-4 (Japan Research Reactor-4) in Japan Atomic Energy Research Institute (JAERI) using mixed thermal-epithermal beam (thermal neutron beam I: TNB-I). Compared to pure thermal beam (thermal neutron beam II: TNB-II), TNB-I has an improved neutron delivery into the deep region than TNB-II. The clinical protocol and the preliminary results will be discussed. (author)

  14. Magnetic fields driven by tidal mixing in radiative stars

    Science.gov (United States)

    Vidal, Jérémie; Cébron, David; Schaeffer, Nathanaël; Hollerbach, Rainer

    2018-04-01

    Stellar magnetism plays an important role in stellar evolution theory. Approximatively 10 per cent of observed main sequence (MS) and pre-main-sequence (PMS) radiative stars exhibit surface magnetic fields above the detection limit, raising the question of their origin. These stars host outer radiative envelopes, which are stably stratified. Therefore, they are assumed to be motionless in standard models of stellar structure and evolution. We focus on rapidly rotating, radiative stars which may be prone to the tidal instability, due to an orbital companion. Using direct numerical simulations in a sphere, we study the interplay between a stable stratification and the tidal instability, and assess its dynamo capability. We show that the tidal instability is triggered regardless of the strength of the stratification (Brunt-Väisälä frequency). Furthermore, the tidal instability can lead to both mixing and self-induced magnetic fields in stably stratified layers (provided that the Brunt-Väisälä frequency does not exceed the stellar spin rate in the simulations too much). The application to stars suggests that the resulting magnetic fields could be observable at the stellar surfaces. Indeed, we expect magnetic field strengths up to several Gauss. Consequently, tidally driven dynamos should be considered as a (complementary) dynamo mechanism, possibly operating in radiative MS and PMS stars hosting orbital companions. In particular, tidally driven dynamos may explain the observed magnetism of tidally deformed and rapidly rotating Vega-like stars.

  15. Intercomparison of radiation protection devices in a high-energy stray neutron field. Part III: Instrument response

    CERN Document Server

    Silari, M; Beck, P; Bedogni, R; Cale, E; Caresana, M; Domingo, C; Donadille, L; Dubourg, N; Esposito, A; Fehrenbacher, G; Fernández, F; Ferrarini, M; Fiechtner, A; Fuchs, A; García, M J; Golnik, N; Gutermuth, F; Khurana, S; Klages, Th; Latocha, M; Mares, V; Mayer, S; Radon, T; Reithmeier, H; Rollet, S; Roos, H; Rühm, W; Sandri, S; Schardt, D; Simmer, G; Spurný, F; Trompier, F; Villa-Grasa, C; Weitzenegger, E; Wiegel, B; Wielunski, M; Wissmann, F; Zechner, A; Zielczyński, M

    2009-01-01

    The European Commission has funded within its 6th Framework Programme a three-year project (2005–2007) called CONRAD, COordinated Network for RAdiation Dosimetry. The organizational framework for this project was provided by the European radiation Dosimetry Group EURADOS. Work Package 6 of CONRAD dealt with “complex mixed radiation fields at workplaces” and in this context it organised a benchmark exercise, which included both measurements and calculations, in a stray radiation field at a high-energy particle accelerator at GSI, Germany. The aim was to intercompare the response of several types of active detectors and passive dosemeters in a well-characterised workplace field. The Monte Carlo simulations of the radiation field and the experimental determination of the neutron spectra with various Bonner Sphere Spectrometers are discussed in Rollet et al. (2008) and in Wiegel et al. (2008). This paper focuses on the intercomparison of the response of the dosemeters in terms of ambient dose equivalent. Th...

  16. TRIPOLI calculation of the neutron field in the hall of the SILENE reactor

    International Nuclear Information System (INIS)

    Bourdet, L.

    1986-05-01

    This study concerns the utilization of the experimental reactor SILENE as radiation source. Its aim is to get a theoretical estimation of the neutron field characteristics in different points of the irradiation hall (spectra, fluences, equivalents of biological doses and reaction yields). These estimations are compared to results obtained by several experimental techniques; they allow to know better this neutron field with or without lead shield [fr

  17. Periodic magnetic field as a polarized and focusing thermal neutron spectrometer and monochromator

    Energy Technology Data Exchange (ETDEWEB)

    Cremer, J. T.; Williams, D. L.; Fuller, M. J.; Gary, C. K.; Piestrup, M. A. [Adelphi Technology, Inc., 2003 East Bayshore Rd., Redwood City, California 94063 (United States); Pantell, R. H.; Feinstein, J. [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Flocchini, R. G.; Boussoufi, M.; Egbert, H. P.; Kloh, M. D.; Walker, R. B. [Davis McClellan Nuclear Radiation Center, University of California, McClellan, California 95652 (United States)

    2010-01-15

    A novel periodic magnetic field (PMF) optic is shown to act as a prism, lens, and polarizer for neutrons and particles with a magnetic dipole moment. The PMF has a two-dimensional field in the axial direction of neutron propagation. The PMF alternating magnetic field polarity provides strong gradients that cause separation of neutrons by wavelength axially and by spin state transversely. The spin-up neutrons exit the PMF with their magnetic spins aligned parallel to the PMF magnetic field, and are deflected upward and line focus at a fixed vertical height, proportional to the PMF period, at a downstream focal distance that increases with neutron energy. The PMF has no attenuation by absorption or scatter, as with material prisms or crystal monochromators. Embodiments of the PMF include neutron spectrometer or monochromator, and applications include neutron small angle scattering, crystallography, residual stress analysis, cross section measurements, and reflectometry. Presented are theory, experimental results, computer simulation, applications of the PMF, and comparison of its performance to Stern-Gerlach gradient devices and compound material and magnetic refractive prisms.

  18. Periodic magnetic field as a polarized and focusing thermal neutron spectrometer and monochromator.

    Science.gov (United States)

    Cremer, J T; Williams, D L; Fuller, M J; Gary, C K; Piestrup, M A; Pantell, R H; Feinstein, J; Flocchini, R G; Boussoufi, M; Egbert, H P; Kloh, M D; Walker, R B

    2010-01-01

    A novel periodic magnetic field (PMF) optic is shown to act as a prism, lens, and polarizer for neutrons and particles with a magnetic dipole moment. The PMF has a two-dimensional field in the axial direction of neutron propagation. The PMF alternating magnetic field polarity provides strong gradients that cause separation of neutrons by wavelength axially and by spin state transversely. The spin-up neutrons exit the PMF with their magnetic spins aligned parallel to the PMF magnetic field, and are deflected upward and line focus at a fixed vertical height, proportional to the PMF period, at a downstream focal distance that increases with neutron energy. The PMF has no attenuation by absorption or scatter, as with material prisms or crystal monochromators. Embodiments of the PMF include neutron spectrometer or monochromator, and applications include neutron small angle scattering, crystallography, residual stress analysis, cross section measurements, and reflectometry. Presented are theory, experimental results, computer simulation, applications of the PMF, and comparison of its performance to Stern-Gerlach gradient devices and compound material and magnetic refractive prisms.

  19. Comparison of neutron scattering, gravimetric and tensiometric methods for measuring soil water content in the field

    International Nuclear Information System (INIS)

    Jat, R.L.; Das, D.K.; Naskar, G.C.

    1975-01-01

    Water content of a sandy clay loam soil was measured by neutron scattering, gravimetric and tensiometric methods. Tensiometric measurement based on laboratory moisture retention curve gave comparatively higher moisture content than those obtained by other methods. No significant differences were observed among neutron meter, gravimetric and tensiometric measurement based on field calibration curve. Though for irrigation purposes all the methods can be used equally, use of tensiometric method with field calibration curve is suggested for easy and more accurate soil water content measurement where neutron meter is not available. (author)

  20. Fast-neutron detecting system with n, γ discrimination

    International Nuclear Information System (INIS)

    Ouyang Xiaoping; Huang Bao; Cao Jinyun

    1997-11-01

    In the present work, a new type neutron detecting system is reported, which can absolutely measure neutron parameters in n + γ mixed fields and has a long continuance of static high vacuum of 10 -4 Pa. The detecting system, with middle neutron-detecting sensitivity, short time response and big linear current output, has applied successfully in pulsed neutron beam measurement

  1. Calibration of a spectrometry multisphere system for neutron fields

    International Nuclear Information System (INIS)

    Carelli, Jorge L.; Cruzate, Juan A.; Papadopulos, Susana B.; Gregori, Beatriz N.; Ciocci Brazzano, Ligia

    2005-01-01

    In this work it is presented the calibration of the neutrons spectrometric system of the Nuclear Regulatory Authority (ARN) in the Institut de Protection et Sure te Nucleaires (Ipn), Labourite dadaist et de Recherche s en Dosimetric Extern e, Cadarache, France. The multisphere system is composed of 9 polyethylene spheres of high density, with a gaseous detector of 3 He and associate electronics. The matrix of energy response to the system neutrons was obtained applying the MCNPX code for the range of energies between thermal and 100 MeV with cross sections taken from library ENDF/B-VI. The neutron spectra of the multisphere system were obtained applying the deconvolution code LOUHI82. The relationship between the theoretical responses and the experiences obtained with the AmBe and 252 Cf sources are also presented in this work [es

  2. The influence of hyperons and strong magnetic field in neutron star properties

    International Nuclear Information System (INIS)

    Lopes, L.L.; Menezes, D.P.

    2012-01-01

    Neutron stars are among the most exotic objects in the universe and constitute a unique laboratory to study nuclear matter above the nuclear saturation density. In this work, we study the equation of state (EoS) of the nuclear matter within a relativistic model subject to a strong magnetic field. We then apply this EoS to study and describe some of the physical characteristics of neutron stars, especially the massradius relation and chemical compositions. To study the influence of the magnetic field and the hyperons in the stellar interior, we consider altogether four solutions: two different magnetic fields to obtain a weak and a strong influence; and two configurations: a family of neutron stars formed only by protons, electrons, and neutrons and a family formed by protons, electrons, neutrons, muons, and hyperons. The limit and the validity of the results found are discussed with some care. In all cases, the particles that constitute the neutron star are in ,B equilibrium and zero total net charge. Our work indicates that the effect of a strong magnetic field has to be taken into account in the description of magnetars, mainly if we believe that there are hyperons in their interior, in which case the influence of the magnetic field can increase the mass by more than 10 %. We have also seen that although a magnetar can reach 2.48 M0, a natural explanation of why we do not know pulsars with masses above 2.0 Mo arises. We also discuss how the magnetic field affects the strangeness fraction in some standard neutron star masses, and to conclude our paper, we revisit the direct Urca process related to the cooling of the neutron stars and show how it is affected by the hyperons and the magnetic field. (author)

  3. Neutronic design of mixed oxide-silicide cores for the core conversion of rsg-gas reactor

    International Nuclear Information System (INIS)

    Sembiring, Tagor Malem; Tukiran; Pinem surian; Febrianto

    2001-01-01

    The core conversion of rsg-gas reactor from an all-oxide (U 3 O 8 -Al) core, through a series of mixed oxide-silicide core, to an all-silicide (U 3 Si 2 -Al) core for the same meat density of 2.96 g U/cc is in progress. The conversion is first step of the step-wise conversion and will be followed by the second step that is the core conversion from low meat density of silicide core, through a series of mixed lower-higher density of silicide core, to an all-higher meat density of 3.55 g/cc core. Therefore, the objectives of this work is to design the mixed cores on the neutronic performance to achieve safety a first full-silicide core for the reactor with the low uranium meat density of 2.96gU/cc. The neutronic design of the mixed cores was performed by means of Batan-EQUIL-2D and Batan-3DIFF computer codes for 2 and 3 dimension diffusion calculation, respectively. The result shows that all mixed oxide-silicide cores will be feasible to achieve safety a fist full-silicide core. The core performs the same neutronic core parameters as those of the equilibrium silicide core. Therefore, the reactor availability and utilization during the core conversion is not changed

  4. Mixed field radiation modification of polyurethanes based on castor oil

    International Nuclear Information System (INIS)

    Mortley, A.; Bonin, H.W.; Bui, V.T.

    2006-01-01

    Polyurethane is among the polymers and polymer-based composite materials being investigated at the Royal Military College of Canada for the fabrication of leak-tight containers for the long-term disposal of radioactive waste. Due to the long aliphatic chain of the castor oil component of polyurethane, thermal curing of castor oil based polyurethane (COPU) is limited by increasing polymer viscosity. To enhance further crosslinking, COPUs were subjected to a range of doses (0.0 - 3.0 MGy) produced by the mixed ionizing radiation field of a SLOWPOKE-2 research nuclear reactor. The tensile mechanical properties of castor oil based polyurethanes (COPU), unirradiated and irradiated, were characterized by mechanical tensile tests. Increases in mechanical strength due to radiation-induced crosslinking and limitations of thermal curing were confirmed by tensile tests and changing 13 C-NMR and FTIR spectra. (author)

  5. Mixed field radiation modification of polyurethanes based on castor oil

    Energy Technology Data Exchange (ETDEWEB)

    Mortley, A.; Bonin, H.W.; Bui, V.T. [Royal Military College of Canada, Dept. of Chemistry and Chemical Engineering, Kingston, Ontario (Canada)]. E-mail: aba.mortley@rmc.ca

    2006-07-01

    Polyurethane is among the polymers and polymer-based composite materials being investigated at the Royal Military College of Canada for the fabrication of leak-tight containers for the long-term disposal of radioactive waste. Due to the long aliphatic chain of the castor oil component of polyurethane, thermal curing of castor oil based polyurethane (COPU) is limited by increasing polymer viscosity. To enhance further crosslinking, COPUs were subjected to a range of doses (0.0 - 3.0 MGy) produced by the mixed ionizing radiation field of a SLOWPOKE-2 research nuclear reactor. The tensile mechanical properties of castor oil based polyurethanes (COPU), unirradiated and irradiated, were characterized by mechanical tensile tests. Increases in mechanical strength due to radiation-induced crosslinking and limitations of thermal curing were confirmed by tensile tests and changing {sup 13}C-NMR and FTIR spectra. (author)

  6. Entanglement in Quantum Field Theory: particle mixing and oscillations

    International Nuclear Information System (INIS)

    Blasone, M; Dell'Anno, F; De Siena, S; Illuminati, F

    2013-01-01

    The phenomena of particle mixing and flavor oscillations in elementary particle physics are associated with multi-mode entanglement of single-particle states. We show that, in the framework of quantum field theory, these phenomena exhibit a fine structure of quantum correlations, as multi-mode multi-particle entanglement appears. Indeed, the presence of anti-particles adds further degrees of freedom, thus providing nontrivial contributions both to flavor entanglement and, more generally, to multi-partite entanglement. By using the global entanglement measure, based on the linear entropies associated with all the possible bipartitions, we analyze the entanglement in the multiparticle states of two-flavor neutrinos and anti-neutrinos. A direct comparison with the instance of the quantum mechanical Pontecorvo single-particle states is also performed.

  7. Workplace characterization using spectrometry for reliable neutron dose assessment in mixed neutron photon fields

    International Nuclear Information System (INIS)

    Bolognese-Milsztajn, T.; Asselineau, B.; Itie, C.; Lahaye, T.; Muller, H.

    2002-01-01

    Radiation protection for practices should be based on justification of exposure, optimization of protection and dose limitations. The 96/29 European Union directive clearly requires that operational protection of exposed workers shall be based on prior evaluation to identify the nature and magnitude of the radiological risk to exposed workers and implementation of optimization of radiation protection in all working conditions. Operational protection of exposed workers requires the implementation of measures at workplaces. The ICRP60 publication (1991) defines and recommends the use of the effective dose E for radiological protections purposes. This quantity can not be directly measured; the operational quantities ambient dose equivalent: H and personal dose equivalent: Hp as defined in the ICRU 51 report (1993) are recommended to estimate the effective dose E. These operational quantities are related, through calculated conversion coefficients h Φ , to the measurable function fluence Φ by: H = ∫ h Φ (E) Φ E dE (1a); Hp = ∫ hp Φ (E, Ω) Φ E , Ω dE dΩ (1b). Φ E (Φ E ,Ω) is the distribution of the fluence with respect to energy (energy E and direction Ω); h Φ or hp Φ are the fluence to operational quantity conversion coefficients as defined by the ICRU 57 report (1998)

  8. Radial oscillations of neutron stars in strong magnetic fields

    Indian Academy of Sciences (India)

    The eigen frequencies of radial pulsations of neutron stars are calculated in a strong magnetic field. At low densities we use the magnetic BPS equation of state (EOS) similar to that obtained by Lai and Shapiro while at high densities the EOS obtained from the relativistic nuclear mean field theory is taken and extended to ...

  9. Neutron generators and their uses in research and applied fields. Vol. 1

    Energy Technology Data Exchange (ETDEWEB)

    Asfour, F I [Division of Basic Nuclear Sciences, Nuclear Research Center, Atomic Energy Authority, Cairo (Egypt)

    1996-03-01

    The development of the low voltage neutron generators (NGS) has contributed considerably to the scope of nuclear research and the economical application of nuclear methods. Such simple instruments are used to produce 14 MeV and 3 MeV neutrons via the 3{sup H}(d,n)4{sup H}e and 2{sup H}(d,n)3{sup H}e reactions,respectively. The neutrons are very widely used and are inexpensive, easy to install and operate, therefore, in addition to nuclear physicists, there are a number of groups of scientists who use low voltage accelerators as tools for pure and applied research, service and education. The aim of this work is to review shortly those problems and methods of science and technology where the neutrons produced in the D-T and D-D reactions play the main role. A wide range of experiments with the detection of neutrons and charged particles is available including the study of shielding and the generator technology itself. N.G. are recently widely used for the determination of neutron data needed for fast reactor and thermonuclear devices. The principles and techniques of the possible uses of neutron generators in technology and research are summarized. The review is devoted to:- Give a short review of the most important operational characteristics of the neutron generators and the necessary instruments needed for application. Outline the main applications of the neutron generators in neutron activation and prompt radiation analysis in various fields(metallurgy, chemistry, biology, meteoritic and lunar studies, geology and mining, etc...) fast neutron therapy, and radiation effects. 2 figs.

  10. Mixed Methods Research Prevalence Studies: Field-Specific Studies on the State of the Art of Mixed Methods Research

    OpenAIRE

    Molina-Azorín, José F.; Fetters, Michael D.

    2016-01-01

    The Journal of Mixed Methods Research (JMMR) has always welcomed two main kinds of manuscripts: original empirical articles and methodological/theoretical articles (Creswell & Tashakkori, 2007; Fetters & Freshwater, 2015a; Mertens, 2011). Both types of articles must clearly state methodological aims, review mixed methods literature relative to the methodological aim, and advance the field of mixed methods—empirical articles must address integration (Fetters & Freshwater, 2015b). In this edito...

  11. The calibration method for personal dosimetry system in photon and neutron radiation fields

    Energy Technology Data Exchange (ETDEWEB)

    Trousil, J; Plichta, J [CSOD, Prague (Czech Republic); Nikodemova, D [SOD, Bratislava (Slovakia)

    1996-12-31

    The type testing of dosimetry system was performed with standard photon radiation fields within the energy range 15 keV to 1.25 MeV and electron radiation fields within the range 0.2 MeV to 3 MeV. For type testing of neutron dosimeters {sup 252}Cf and {sup 241}Am-Be radionuclide neutron sources was used, as well as a 14 MeV neutron generator. The neutron sources moderated by various moderating and absorbing materials was also used. The routine calibration of individual photon dosemeters was carried out using a {sup 137}Cs calibration source in the air kerma quality in the dose range 0.2 mGy to 6 Gy. The type testing of neutron dosemeters was performed in collaboration with Nueherberg laboratory on neutron generator with neutron energies -.57; 1.0;; 5.3 and 15.1 MeV. The fading and angular dependence testing was also included in the tests of both dosemeter systems. (J.K.).

  12. Neutron calibration field of bare {sup 252}Cf source in Vietnam

    Energy Technology Data Exchange (ETDEWEB)

    Le, Ngoc Thiem; Tran, Hoai Nam; Nguyen, Khai Tuan [Institute for Nuclear Science and Technology, Hanoi (Viet Nam); Trinh, Glap Van [Institute of Research and Development, Duy Tan University, Da Nang (Viet Nam)

    2017-02-15

    This paper presents the establishment and characterization of a neutron calibration field using a bare {sup 252}Cf source of low neutron source strength in Vietnam. The characterization of the field in terms of neutron flux spectra and neutron ambient dose equivalent rates were performed by Monte Carlo simulations using the MCNP5 code. The anisotropy effect of the source was also investigated. The neutron ambient dose equivalent rates at three reference distances of 75, 125, and 150 cm from the source were calculated and compared with the measurements using the Aloka TPS-451C neutron survey meters. The discrepancy between the calculated and measured values is found to be about 10%. To separate the scattered and the direct components from the total neutron flux spectra, an in-house shadow cone of 10% borated polyethylene was used. The shielding efficiency of the shadow cone was estimated using the MCNP5 code. The results confirmed that the shielding efficiency of the shadow cone is acceptable.

  13. A method to describe inelastic gamma field distribution in neutron gamma density logging.

    Science.gov (United States)

    Zhang, Feng; Zhang, Quanying; Liu, Juntao; Wang, Xinguang; Wu, He; Jia, Wenbao; Ti, Yongzhou; Qiu, Fei; Zhang, Xiaoyang

    2017-11-01

    Pulsed neutron gamma density logging (NGD) is of great significance for radioprotection and density measurement in LWD, however, the current methods have difficulty in quantitative calculation and single factor analysis for the inelastic gamma field distribution. In order to clarify the NGD mechanism, a new method is developed to describe the inelastic gamma field distribution. Based on the fast-neutron scattering and gamma attenuation, the inelastic gamma field distribution is characterized by the inelastic scattering cross section, fast-neutron scattering free path, formation density and other parameters. And the contribution of formation parameters on the field distribution is quantitatively analyzed. The results shows the contribution of density attenuation is opposite to that of inelastic scattering cross section and fast-neutron scattering free path. And as the detector-spacing increases, the density attenuation gradually plays a dominant role in the gamma field distribution, which means large detector-spacing is more favorable for the density measurement. Besides, the relationship of density sensitivity and detector spacing was studied according to this gamma field distribution, therefore, the spacing of near and far gamma ray detector is determined. The research provides theoretical guidance for the tool parameter design and density determination of pulsed neutron gamma density logging technique. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Measurements of Integral Cross Section Ratios in Two Dosimetry Benchmark Neutron Fields

    International Nuclear Information System (INIS)

    Fabry, A.; Czock, K.H.

    1974-12-01

    In the frame of a current interlaboratory effort devoted to the standardization of fuels and materials neutron dosimetry, the 103 Rh(n,n') 103m Rh and 58 Ni(n,p) 58 Co integral cross sections have been accurately measured relatively to the 115 In(n,n') 115m In cross section in the 235 U thermal dission neutron spectrum and in the MOLΣΣ Intermediate-Energy Standard Neutron field. In this last neutron field, the data are related also to the 235 U(n,f) cross section. The measurements are extensively documented and the results briefly compared to literature. Most noticeably, decisive support is provided for the selection of a specific 103 Rh(n,n') 103m Rh differential-energy cross section among the existing, conflicting data. (author)

  15. Measurements of integral cross section ratios in two dosimetry benchmark neutron fields

    International Nuclear Information System (INIS)

    Fabry, A.; Czock, K.H.

    1974-12-01

    In the frame of a current interlaboratory effort devoted to the standardization of fuels and materials neutron dosimetry, the 103 Rh(n,n') 103m Rh and 58 Ni(n,p) 58 Co integral cross sections have been accurately measured relatively to the 115 In(n,n') 115m In cross section in the 235 U thermal fission neutron spectrum and in the MOL-ΣΣ intermediate-energy standard neutron field. In this last neutron field, the data are related also to the 235 U(n,f) cross section. The measurements are extensively documented and the results briefly compared to literature. Most noticeably, decisive support is provided for the selection of a specific 103 Rh(n,n') 103m Rh differential-energy cross section among the existing, conflicting data. (author)

  16. Measurements of integral cross section ratios in two dosimetry benchmark neutron fields

    Energy Technology Data Exchange (ETDEWEB)

    Fabry, A [CEN-SCK, Mol (Belgium); Czock, K H [International Atomic Energy Agency, Laboratory Seibersdorf, Vienna (Austria)

    1974-12-01

    In the frame of a current interlaboratory effort devoted to the standardization of fuels and materials neutron dosimetry, the {sup 103}Rh(n,n'){sup 103m}Rh and {sup 58}Ni(n,p){sup 58}Co integral cross sections have been accurately measured relatively to the {sup 115}In(n,n'){sup 115m} In cross section in the {sup 235}U thermal fission neutron spectrum and in the MOL-{sigma}{sigma} intermediate-energy standard neutron field. In this last neutron field, the data are related also to the {sup 235}U(n,f) cross section. The measurements are extensively documented and the results briefly compared to literature. Most noticeably, decisive support is provided for the selection of a specific {sup 103}Rh(n,n'){sup 103m}Rh differential-energy cross section among the existing, conflicting data. (author)

  17. Measurements of Integral Cross Section Ratios in Two Dosimetry Benchmark Neutron Fields

    Energy Technology Data Exchange (ETDEWEB)

    Fabry, A. [CEN-SCK, Mol (Belgium); Czock, K. H. [International Atomic Energy Agency, Vienna (Austria)

    1974-12-15

    In the frame of a current interlaboratory effort devoted to the standardization of fuels and materials neutron dosimetry, the {sup 103}Rh(n,n'){sup 103m}Rh and {sup 58}Ni(n,p){sup 58}Co integral cross sections have been accurately measured relatively to the {sup 115}In(n,n'){sup 115m}In cross section in the {sup 235}U thermal dission neutron spectrum and in the MOL{Sigma}{Sigma} Intermediate-Energy Standard Neutron field. In this last neutron field, the data are related also to the {sup 235}U(n,f) cross section. The measurements are extensively documented and the results briefly compared to literature. Most noticeably, decisive support is provided for the selection of a specific {sup 103}Rh(n,n'){sup 103m}Rh differential-energy cross section among the existing, conflicting data. (author)

  18. The Response of Alanine Dosimeters in Thermal Neutron Fields

    DEFF Research Database (Denmark)

    Schmitz, T.; Bassler, Niels; Sharpe, P.

    response of all pellets could be reproduced by calculations within a uncertainty of 5 %. For all experiments three dose components have been separated. A proton dose is generated in the 14N(n,p)14C reaction. Secondary gammas are generated by various (n,γ) reactions, dominated by the 2.2 MeV photon from...... experiments the dosimeters will be exposed to higher neutron energies, which are more typical for BNCT treatments. References: [1] Barth, R.F; 2009: Boron neutron capture therapy at the crossroads: Challenges and opportunities. Applied Radiation and Isotopes 67, 3-6. [2] Rogus, R.D.; Harling, O.K.; Yanch, J.C...... for treatment of liver metastases. Applied Radiation and Isotopes 67, 238-241. [4] Sharpe, P.; Sephtan, J.; 2000: An automated system for the measurement of alanine/EPR dosimeters. Applied Radiation and Isotopes 52, 1185-1188....

  19. Study of an integrated electronic monitor for neutron fields

    Energy Technology Data Exchange (ETDEWEB)

    Barelaud, B.; Nexon-Mokhtari, F.; Barrau, C.; Decossas, J.L.; Vareille, J.C. [Limoges Univ., 87 (France); Sarrabayrouse, G.J. [CNRS, 31 - Toulouse (France)

    1995-12-31

    The majority of the individual neutron monitors measure incorrectly in a certain energy range (10 keV-500 keV). For electronic devices, this problem is due to their high {gamma} sensitivity. To solve this problem a microelectronic detector design for neutron spectrometry is now being studied at LEPOFI. It is based on the measurement of the total energy which is deposited by {sup 6}Li (n, {alpha}) {sup 3}H or {sup 10}B (n {alpha}) {sup 7}Li reactions in silicon detectors. A new electronic sensor - for example a boron or lithium sandwich device -has been developed in collaboration with LAAS. Specific techniques for silicon sensor coating with boron have been developed and are briefly presented. The response of the detector has been computed using a model and a code developed at LEPOFI. Several parameters have been taken into account in the calculations: the type of layer, its thickness, the characteristics of the detector. The results of these simulations are discussed and calculated pulse height distributions for various designs are presented. The present status of the investigation only concerns thermal neutrons. (author).

  20. ENEA TRIGA RC-1 reactor activities in the fields of nuclear medicine and neutron radiography

    International Nuclear Information System (INIS)

    Chiesa, Gianni; Festinesi, Armando; Palomba, Mario; Rosa, Roberto; Rossi, Gabriela; Sangiovanni, Gino; Santoro, Emilio; Sedda, Antioco Franco; Storelli, Lucio

    2008-01-01

    In the last three years, TRIGA RC-1 plant staff is involved in collaborations with some roman hospitals for the production of particular radioisotopes for the diagnosis and therapy in the field of human cancer. Further, the thermal column of TRIGA reactor has been prepared for neutron radiography and tomography. For another channel, instruments and equipment above neutron radiography and tomography are in preparation phase. This paper includes an overview of the experimental equipment properly developed by TRIGA staff. (authors)

  1. The alanine detector in BNCT dosimetry: dose response in thermal and epithermal neutron fields.

    Science.gov (United States)

    Schmitz, T; Bassler, N; Blaickner, M; Ziegner, M; Hsiao, M C; Liu, Y H; Koivunoro, H; Auterinen, I; Serén, T; Kotiluoto, P; Palmans, H; Sharpe, P; Langguth, P; Hampel, G

    2015-01-01

    The response of alanine solid state dosimeters to ionizing radiation strongly depends on particle type and energy. Due to nuclear interactions, neutron fields usually also consist of secondary particles such as photons and protons of diverse energies. Various experiments have been carried out in three different neutron beams to explore the alanine dose response behavior and to validate model predictions. Additionally, application in medical neutron fields for boron neutron capture therapy is discussed. Alanine detectors have been irradiated in the thermal neutron field of the research reactor TRIGA Mainz, Germany, in five experimental conditions, generating different secondary particle spectra. Further irradiations have been made in the epithermal neutron beams at the research reactors FiR 1 in Helsinki, Finland, and Tsing Hua open pool reactor in HsinChu, Taiwan ROC. Readout has been performed with electron spin resonance spectrometry with reference to an absorbed dose standard in a (60)Co gamma ray beam. Absorbed doses and dose components have been calculated using the Monte Carlo codes fluka and mcnp. The relative effectiveness (RE), linking absorbed dose and detector response, has been calculated using the Hansen & Olsen alanine response model. The measured dose response of the alanine detector in the different experiments has been evaluated and compared to model predictions. Therefore, a relative effectiveness has been calculated for each dose component, accounting for its dependence on particle type and energy. Agreement within 5% between model and measurement has been achieved for most irradiated detectors. Significant differences have been observed in response behavior between thermal and epithermal neutron fields, especially regarding dose composition and depth dose curves. The calculated dose components could be verified with the experimental results in the different primary and secondary particle fields. The alanine detector can be used without

  2. Spin ordered phase transitions in neutron matter under the presence of a strong magnetic field

    International Nuclear Information System (INIS)

    Isayev, A.A.; Yang, J.

    2011-01-01

    In dense neutron matter under the presence of a strong magnetic field, considered in the model with the Skyrme effective interaction, there are possible two types of spin ordered states. In one of them the majority of neutron spins are aligned opposite to magnetic field (thermodynamically preferable state), and in other one the majority of spins are aligned along the field (metastable state). The equation of state, incompressibility modulus and velocity of sound are determined in each case with the aim to find the peculiarities allowing to distinguish between two spin ordered phases.

  3. Cytogenetic effect of reactor beams of mixed neutrons and gamma rays on spermatocytes

    International Nuclear Information System (INIS)

    Roushdy, H.M.; El-Dawy, H.A.; Hassan, N.H.A; Khattab, F.I.

    1997-01-01

    Spermatocytes metaphase- 1 - chromosomes of young adult male mice irradiated at 42.5 r of mixed neutrons and gamma rays were investigated at the intervals of 1,2,3 and 4 weeks post-irradiation. The induced chromosomal aberrations were: ring-four (RIV), chain-four (CIV), chain three plus one univalent (CIII+1), chain hexavalent (CVI), autosomal univalent X-Y univalent and polyploidy. The percentage of abnormal spermatocytes with respect to the time intervals between treatment and sacrifice were studied in both subgroups irradiated at 42.5 R. and 58.5 R. The frequencies of abnormal spermatocytes reached 10.7%, 16%, 20% and 18.7 at the intervals of 1,2,3 and 4 weeks post - irradiation for the dose 42.5 R. respectively. In the subgroups exposed to 58.5 R the percentage of abnormal spermatocytes was 17.3%, 24.7%, 30.7% and 22.0% after the 1st, 2nd, 3rd, and 4th weeks, respectively

  4. Development of a filtered neutron field in KUR. In behalf of biological irradiation experiments

    International Nuclear Information System (INIS)

    Sato, Takashi; Utsuro, Masahiko; Utsumi, Hiroshi

    1995-07-01

    Very little direct measurements have been made of the biological effects of neutrons below 100keV. Recently, an iron-filtered 24keV neutron beam of Harwell Materials Testing Reactor, PLUTO, was reported to be highly efficient in inducing chromosome aberrations; the efficiency being comparable to that of fission neutrons. This results could have serious repercussions for radiation protection standards as the ICRP assume a decrease in neutron RBE below 100keV. The investigations reported here have as their primary purpose the production of neutron beams at the 24keV iron window energy, using the B-1 experimental facility of the Kyoto University Research Reactor (KUR) at the Research Reactor Institute, Kyoto University (KURRI). The filtered neutron filed for biomedical applications is designed to maximized the contributions of neutrons with other energies and gamma-rays. The characteristics of the radiation field were obtained by the simple transmission calculations for Fe(45cm) and Al(35cm) filters, by using the Monte Carlo code MCN P, and by the measurement of nuclear heating for Fe and Al filter pieces. The 24keV neutron flux and gamma-ray dose rate were measured using a proton recoil counter and TLDs, respectively. The measured findings are as follows: The 24keV neutron flux at the irradiation field was approximately 1x10 6 n/cm 2 /s, and the gamma-ray dose rate was 1.0Gy/h at the surface of the B-1 plug. Nuclear heating of the filter materials was 5.2mW/g for Fe and 4mW/g for Al, in maximum. (author)

  5. Field Monitoring of Experimental Hot Mix Asphalt Projects Placed in Massachusetts

    Science.gov (United States)

    2017-06-30

    Since 2000, Massachusetts has been involved with numerous field trials of experimental hot mix asphalt mixtures. These experimental mixtures included several pilot projects using the Superpave mixture design methodology, utilization of warm mix aspha...

  6. Dosimetry with tissue-equivalent ionisation chambers in fast neutron fields for biomedical applications

    International Nuclear Information System (INIS)

    Zoetelief, J.; Broerse, J.J.

    1983-01-01

    The use of calibrated tissue-equivalent (TE) ionisation chambers is commonly considered to be the most practical method for total absorbed dose determinations in mixed neutron-photon fields for biomedical applications. The total absorbed dose can be derived from the charge produced within the cavity of an ionisation chamber employing a number of physical parameters. To arrive at the charge produced in the cavity several correction factors have to be introduced which are related to the operational characteristics of the chambers. Information on the operational characteristics of four TE ionisation chambers is presented in relation to ion collection, density and composition of gas in the cavity, wall thickness and effective point of measurement. In addition, some recent results from an ionisation chamber operated at high gas pressures are presented. The total absorbed doses derived from TE ionisation chambers show agreement within the uncertainty limits with results from other independent dosimetry methods, i.e., differential fluence measurements and a TE calorimeter. Conscientious experimentation and a common data base can provide dosimetry results with TE ionisation chambers with variations of less than +-2%. (author)

  7. Intercomparison of radiation protection devices in a high-energy stray neutron field, Part II: Bonner sphere spectrometry

    International Nuclear Information System (INIS)

    Wiegel, B.; Agosteo, S.; Bedogni, R.; Caresana, M.; Esposito, A.; Fehrenbacher, G.; Ferrarini, M.; Hohmann, E.; Hranitzky, C.; Kasper, A.; Khurana, S.; Mares, V.; Reginatto, M.; Rollet, S.; Ruehm, W.; Schardt, D.; Silari, M.; Simmer, G.; Weitzenegger, E.

    2009-01-01

    The European Commission has funded within its 6th Framework Programme a three-year project (2005-2007) called CONRAD, COordinated Network for RAdiation Dosimetry. A major task of the CONRAD Work Package 'complex mixed radiation fields at workplaces' was to organise a benchmark exercise in a workplace field at a high-energy particle accelerator where neutrons are the dominant radiation component. The CONRAD benchmark exercise took place at the Gesellschaft fuer Schwerionenforschung mbH (GSI) in Darmstadt, Germany in July 2006. In this paper, the results of the spectrometry using four extended -range Bonner sphere spectrometers of four different institutes are reported. Outside Cave A the neutron spectra were measured with three spectrometers at six selected positions and ambient dose equivalent values were derived for use in the intercomparison with other area monitors and dosemeters. At a common position all three spectrometers were used to allow a direct comparison of their results which acts as an internal quality assurance. The comparison of the neutron spectra measured by the different groups shows very good agreement. A detailed analysis presents some differences between the shapes of the spectra and possible sources of these differences are discussed. However, the ability of Bonner sphere spectrometers to provide reliable integral quantities like fluence and ambient dose equivalent is well demonstrated in this exercise. The fluence and dose results derived by the three groups agree very well within the given uncertainties, not only with respect to the total energy region present in this environment but also for selected energy regions which contribute in certain strength to the total values. In addition to the positions outside Cave A one spectrometer was used to measure the neutron spectrum at one position in the entry maze of Cave A. In this case a comparison was possible to earlier measurements.

  8. SU-E-T-594: Out-Of-Field Neutron and Gamma Dose Estimated Using TLD-600/700 Pairs in the Wobbling Proton Therapy System

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y [College of Medicine, Chang Gung University, Linkou, Taoyuan, Taiwan (China); Lin, Y [College of Medicine, Chang Gung University, Linkou, Taoyuan, Taiwan (China); Medical Physics Research Center, Institute for Radiological Research, Chang Gung University / Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan (China); Chen, H [College of Medicine, Chang Gung University, Linkou, Taoyuan, Taiwan (China); Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan (China); Tsai, H [College of Medicine, Chang Gung University, Linkou, Taoyuan, Taiwan (China); Medical Physics Research Center, Institute for Radiological Research, Chang Gung University / Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan (China); Healthy Aging Research Center, Chang Gung University, Linkou, Taoyuan, Taiwan (China)

    2015-06-15

    Purpose: Secondary fast neutrons and gamma rays are mainly produced due to the interaction of the primary proton beam with the beam delivery nozzle. These secondary radiation dose to patients and radiation workers are unwanted. The purpose of this study is to estimate the neutron and gamma dose equivalent out of the treatment volume during the wobbling proton therapy system. Methods: Two types of thermoluminescent (TL) dosimeters, TLD-600 ({sup 6}LiF: Mg, Ti) and TLD-700 ({sup 7}LiF: Mg, Ti) were used in this study. They were calibrated in the standard neutron and gamma sources at National Standards Laboratory. Annealing procedure is 400°C for 1 hour, 100°C for 2 hours and spontaneously cooling down to the room temperature in a programmable oven. Two-peak method (a kind of glow curve analysis technique) was used to evaluate the TL response corresponding to the neutron and gamma dose. The TLD pairs were placed outside the treatment field at the neutron-gamma mixed field with 190-MeV proton beam produced by the wobbling system through the polyethylene plate phantom. The results of TLD measurement were compared to the Monte Carlo simulation. Results: The initial experiment results of calculated dose equivalents are 0.63, 0.38, 0.21 and 0.13 mSv per Gy outside the field at the distance of 50, 100, 150 and 200 cm. Conclusion: The TLD-600 and TLD-700 pairs are convenient to estimate neutron and gamma dosimetry during proton therapy. However, an accurate and suitable glow curve analysis technique is necessary. During the wobbling system proton therapy, our results showed that the neutron and gamma doses outside the treatment field are noticeable. This study was supported by the grants from the Chang Gung Memorial Hospital (CMRPD1C0682)

  9. SU-E-T-594: Out-Of-Field Neutron and Gamma Dose Estimated Using TLD-600/700 Pairs in the Wobbling Proton Therapy System

    International Nuclear Information System (INIS)

    Chen, Y; Lin, Y; Chen, H; Tsai, H

    2015-01-01

    Purpose: Secondary fast neutrons and gamma rays are mainly produced due to the interaction of the primary proton beam with the beam delivery nozzle. These secondary radiation dose to patients and radiation workers are unwanted. The purpose of this study is to estimate the neutron and gamma dose equivalent out of the treatment volume during the wobbling proton therapy system. Methods: Two types of thermoluminescent (TL) dosimeters, TLD-600 ( 6 LiF: Mg, Ti) and TLD-700 ( 7 LiF: Mg, Ti) were used in this study. They were calibrated in the standard neutron and gamma sources at National Standards Laboratory. Annealing procedure is 400°C for 1 hour, 100°C for 2 hours and spontaneously cooling down to the room temperature in a programmable oven. Two-peak method (a kind of glow curve analysis technique) was used to evaluate the TL response corresponding to the neutron and gamma dose. The TLD pairs were placed outside the treatment field at the neutron-gamma mixed field with 190-MeV proton beam produced by the wobbling system through the polyethylene plate phantom. The results of TLD measurement were compared to the Monte Carlo simulation. Results: The initial experiment results of calculated dose equivalents are 0.63, 0.38, 0.21 and 0.13 mSv per Gy outside the field at the distance of 50, 100, 150 and 200 cm. Conclusion: The TLD-600 and TLD-700 pairs are convenient to estimate neutron and gamma dosimetry during proton therapy. However, an accurate and suitable glow curve analysis technique is necessary. During the wobbling system proton therapy, our results showed that the neutron and gamma doses outside the treatment field are noticeable. This study was supported by the grants from the Chang Gung Memorial Hospital (CMRPD1C0682)

  10. Nondestructive characterization of mixed oxide pellets in welded nuclear fuel pins by neutron radiography and gamma-autoradiography

    International Nuclear Information System (INIS)

    Panakkal, J.P.; Ghosh, J.K.; Roy, P.R.

    1989-01-01

    Nondestructive evaluation of nuclear fuel pellets after the welding of fuel pins plays a vital role in assuring a safe and reliable operation of reactors. Some of the important characteristics to be monitored in low plutonium enriched mixed oxide fuel pellets are plutonium enrichment, size of plutonium dioxide agglomerates, incorrect loading and geometric shape. Experiments were carried out at Bhabha Atomic Research Centre, Bombay on experimental fuel pins containing mixed oxide pellets of different geometry (solid and annular), of different plutonium enrichment (0-6 w% of plutonium dioxide) and containing PuO 2 agglomerates of size 125-2000 microns to evaluate these characteristics nondestructively. Neutron radiography of these fuel pins was carried out using a swimming pool type reactor 'APSARA'. Results of quantitative evaluation of the neutron radiographs and a simple model correlating neutron interaction probability and the optical density are presented. Gamma autoradiography of these fuel pins showed that these parameters could be evaluated with a few limitations. This paper presents the experimental details, quantitative analysis of the radiographs by microdensitometry and merits and demerits of neutron radiography and gamma autoradiography for nondestructive charcterisation of nuclear fuel pellets. (orig.)

  11. Effect of mixed γ-plus neutron-radiation on permeability to taurine of peripheral blood leukocyte membranes

    International Nuclear Information System (INIS)

    Dokshina, G.A.; Naumenko, L.A.

    1980-01-01

    A study was made of permeability to taurine of cellular membranes of peripheral blood leukocytes in vitro under normal conditions and 24 k following mixed γ-plus neutron-irradiation in a dose of 3.5 Gy. It was established that radiation increases the taurine content of cells. The protein content of leukocytes also increases probably due to a better sorption of serum proteins of blood

  12. Fallback accretion onto magnetized neutron stars and the hidden magnetic field model

    International Nuclear Information System (INIS)

    Torres, A; Cerdá-Durán, P; Font, J A

    2015-01-01

    The observation of several neutron stars with relatively low values of the surface magnetic field found in supernova remnants has led in recent years to controversial interpretations. A possible explanation is the slow rotation of the proto-neutron star at birth which is unable to amplify its magnetic field to typical pulsar levels. An alternative possibility, the hidden magnetic field scenario, seems to be favoured over the previous one due to the observation of three low magnetic field magnetars. This scenario considers the accretion of the fallback of the supernova debris onto the neutron star as the responsible for the observed low magnetic field. In this work, we have studied under which conditions the magnetic field of a neutron star can be buried into the crust due to an accreting fluid. We have considered a simplified toy model in general relativity to estimate the balance between the incoming accretion flow an the magnetosphere. We conclude that the burial is possible for values of the surface magnetic field below 10 13 G. The preliminary results reported in this paper for simplified polytropic models should be confirmed using a more realistic thermodynamical setup. (paper)

  13. The importance of using the mixed neutron flux in activation analysis of D-3He fueled reactors

    International Nuclear Information System (INIS)

    Khater, H.Y.; Sawan, M.E.

    1992-01-01

    This paper reports on the D-D and D-T secondary reactions in D- 3 He reactors which provide the neutron source term for most of the radioactivity produced in the structure of the reactor. radionuclides are produced as a result of neutron interactions with their parent nuclides. The amount of activity produced by any radionuclide depends on the number of its parent atoms present at any given time. One approach to account for the activity induced by both neutron sources in any activation analysis is to add their individual contributions. Performing two separate calculations for the D-D and D-T neutron flux components and adding their contributions yields conservative results due to underestimating the destruction of the parent atoms. The overestimation is more pronounced for short and intermediate lived nuclides, long operation time, large neutron flux and large destruction cross section for the parent atoms. In the steel first wall of a typical d- 3 He reactor, adding the individual contributions of the tow neutron sources results in overestimating the activities produced by most of the radioactive isotopes of Ag, Lu, Ta, W and Re. After 30 years of reactor operation, the activity of 187 W, which is a major source of safety concern in case of an accident, is more than an order of magnitude higher than its value if the mixed neutron flux is used. The activity of 188 Re, which is an important source of offsite does in case of accidental release, is overestimated by more than a factor of two

  14. Neutron stars in relativistic mean field theory with isovector scalar meson

    Energy Technology Data Exchange (ETDEWEB)

    Kubis, S.; Kutschera, M.; Stachniewicz, S. [H. Niewodniczanski Institute of Nuclear Physics, Cracow (Poland)

    1998-03-01

    We study the equation of state (EOS) of {beta}-stable dense matter and models of neutron stars in the relativistic mean field (RMF) theory with the isovector scalar mean field corresponding to the {delta}-meson (a{sub 0}(980)). A range of values of the {delta}-meson coupling compatible with the Bonn potentials is explored. Parameters of the model in the isovector sector are constrained to fit the nuclear symmetry energy, E{sub s}{approx}30 MeV. We find that the quantity most sensitive to the {delta}-meson coupling is the proton fraction of neutron star matter. It increases significantly in the presence of the {delta}-field. The energy per baryon also increases but the effect is smaller. The EOS becomes slightly stiffer and the maximum neutron star mass increases for stronger {delta}-meson coupling. (author) 8 refs, 6 figs, 2 tabs

  15. Neutron stars in relativistic mean field theory with isovector scalar meson

    International Nuclear Information System (INIS)

    Kubis, S.; Kutschera, M.; Stachniewicz, S.

    1996-12-01

    We study the equation of state (EOS) of neutron star matter in a relativistic mean field (RMF) theory with the isovector scalar mean field corresponding to the δ-meson [a 0 (980)]. A range of values of the δ-meson coupling compatible with the Bonn potentials is explored. Parameters of the model in the isovector sector are constrained to fit the nuclear symmetry energy, E s ∼ 30 MeV. We find that proton fraction of neutron star matter is higher in the presence of the δ-field whereas the energy per particle is lower. The EOS becomes slightly stiffer and the maximum mass of the neutron star increased with increasing δmeson coupling. The effect is stronger for soft EOS. (author). 7 refs, 6 figs, 1 tab

  16. Neutron stars in relativistic mean field theory with isovector scalar meson

    International Nuclear Information System (INIS)

    Kubis, S.; Kutschera, M.; Stachniewicz, S.

    1998-01-01

    We study the equation of state (EOS) of β-stable dense matter and models of neutron stars in the relativistic mean field (RMF) theory with the isovector scalar mean field corresponding to the δ-meson (a 0 (980)). A range of values of the δ-meson coupling compatible with the Bonn potentials is explored. Parameters of the model in the isovector sector are constrained to fit the nuclear symmetry energy, E s ∼30 MeV. We find that the quantity most sensitive to the δ-meson coupling is the proton fraction of neutron star matter. It increases significantly in the presence of the δ-field. The energy per baryon also increases but the effect is smaller. The EOS becomes slightly stiffer and the maximum neutron star mass increases for stronger δ-meson coupling. (author)

  17. Neutron stars in relativistic mean field theory with isovector scalar meson

    Energy Technology Data Exchange (ETDEWEB)

    Kubis, S.; Kutschera, M.; Stachniewicz, S. [Institute of Nuclear Physics, Cracow (Poland)

    1996-12-01

    We study the equation of state (EOS) of neutron star matter in a relativistic mean field (RMF) theory with the isovector scalar mean field corresponding to the {delta}-meson [a{sub 0}(980)]. A range of values of the {delta}-meson coupling compatible with the Bonn potentials is explored. Parameters of the model in the isovector sector are constrained to fit the nuclear symmetry energy, E{sub s} {approx} 30 MeV. We find that proton fraction of neutron star matter is higher in the presence of the {delta}-field whereas the energy per particle is lower. The EOS becomes slightly stiffer and the maximum mass of the neutron star increased with increasing {delta}meson coupling. The effect is stronger for soft EOS. (author). 7 refs, 6 figs, 1 tab.

  18. Recent developments in the specification and achievement of realistic neutron calibration fields

    International Nuclear Information System (INIS)

    Chartier, J.L.; Kluges, H.; Wiegel, B.; Schraube, H.

    1997-01-01

    In order to calibrate more accurately the neutron dosemeters involved in radiation protection, the concept of 'Realistic Neutron Calibration Fields' is considered as an appropriate alternative solution, making necessary new irradiation facilities which generate well-characterised neutron fields with energy and angular distribution replicating more closely practical workplace conditions. Several experienced laboratories have collaborated on a European project and proposed various approaches which are reviewed in this paper. A short description of the facilities currently in operation is given as well as a few characteristics of the available radiation fields. This description of the state of art is followed by a discussion of the problems to be solved for using such facilities for calibration purposes according to well-specified calibration procedures. (author)

  19. Miniature neutron sources: Thermal neutron sources and their users in the academic field

    International Nuclear Information System (INIS)

    Egelstaff, P.A.

    1992-01-01

    The three levels of thermal neutron sources are introduced - University laboratory sources infrastructure sources and world-class sources - and the needs for each kind and their inter-dependence will be emphasized. A description of the possibilities for University sources based on α-Be reactions or spontaneous fission emission is given, and current experience with them is described. A new generation of infrastructure sources is needed to continue the regional programs based on small reactors. Some possibilities for accelerator sources that could meet this need are considered

  20. Are neutron stars crushed? Gravitomagnetic tidal fields as a mechanism for binary-induced collapse

    International Nuclear Information System (INIS)

    Favata, Marc

    2006-01-01

    Numerical simulations of binary neutron stars by Wilson, Mathews, and Marronetti indicated that neutron stars that are stable in isolation can be made to collapse to black holes when placed in a binary. This claim was surprising as it ran counter to the Newtonian expectation that a neutron star in a binary should be more stable, not less. After correcting an error found by Flanagan, Wilson and Mathews found that the compression of the neutron stars was significantly reduced but not eliminated. This has motivated us to ask the following general question: Under what circumstances can general-relativistic tidal interactions cause an otherwise stable neutron star to be compressed? We have found that if a nonrotating neutron star possesses a current-quadrupole moment, interactions with a gravitomagnetic tidal field can lead to a compressive force on the star. If this current quadrupole is induced by the gravitomagnetic tidal field, it is related to the tidal field by an equation-of-state-dependent constant called the gravitomagnetic Love number. This is analogous to the Newtonian Love number that relates the strength of a Newtonian tidal field to the induced mass quadrupole moment of a star. The compressive force is almost never larger than the Newtonian tidal interaction that stabilizes the neutron star against collapse. In the case in which a current quadrupole is already present in the star (perhaps as an artifact of a numerical simulation), the compressive force can exceed the stabilizing one, leading to a net increase in the central density of the star. This increase is small (< or approx. 1%) but could, in principle, cause gravitational collapse in a star that is close to its maximum mass. This paper also reviews the history of the Wilson-Mathews-Marronetti controversy and, in an appendix, extends the discussion of tidally induced changes in the central density to rotating stars

  1. Bubbles, Bow Shocks and B Fields: The Interplay Between Neutron Stars and Their Environments

    Science.gov (United States)

    Gaensler, Bryan M.

    2006-12-01

    Young neutron stars embody Nature's extremes: they spin incredibly rapidly, move through space at enormous velocities, and are imbued with unimaginably strong magnetic fields. Since their progenitor stars do not have any of these characteristics, these properties are presumably all imparted to a neutron star during or shortly after the supernova explosion in which it is formed. This raises two fundamental questions: how do neutron stars attain these extreme parameters, and how are their vast reservoirs of energy then dissipated? I will explain how multi-wavelength observations of the environments of neutron stars not only provide vital forensic evidence on the physics of supernova core collapse, but also spectacularly reveal the winds, jets, shocks and outflows through which these remarkable objects couple to their surroundings.

  2. Spontaneous scalarization with an extremely massive field and heavy neutron stars

    Science.gov (United States)

    Morisaki, Soichiro; Suyama, Teruaki

    2017-10-01

    We investigate the internal structure and the mass-radius relation of neutron stars in a recently proposed scalar-tensor theory dubbed asymmetron in which a massive scalar field undergoes spontaneous scalarization inside neutron stars. We focus on the case where the Compton wavelength is shorter than 10 km, which has not been investigated in the literature. By solving the modified Einstein equations, either purely numerically or by partially using a semianalytic method, we find that not only the weakening of gravity by spontaneous scalarization but also the scalar force affect the internal structure significantly in the massive case. We also find that the maximum mass of neutron stars is larger for certain parameter sets than that in general relativity and reaches 2 M⊙ even if the effect of strange hadrons is taken into account. There is even a range of parameters where the maximum mass of neutron stars largely exceeds the threshold that violates the causality bound in general relativity.

  3. Testing Moderating Detection Systems with 252Cf-Based Reference Neutron Fields

    International Nuclear Information System (INIS)

    Hertel, Nolan E.; Sweezy, Jeremy; Sauber, Jeremiah S.; Vaughn, David; Cook, Andrew; Tays, Jeff; Ro, Tae-Ik

    2001-01-01

    Calibration measurements were carried out on a probe designed to measure ambient dose equivalent in accordance with ICRP Pub 60 recommendations. It consists of a cylindrical 3 He proportional counter surrounded by a 25-cm-diameter spherical polyethylene moderator. Its neutron response is optimized for dose rate measurements of neutrons between thermal energies and 20 MeV. The instrument was used to measure the dose rate in four separate neutron fields: unmoderated 252 Cf, D 2 O-moderated 252 Cf, polyethylene-moderated 252 Cf, and WEP neutron howitzer with 252 Cf at its center. Dose equivalent measurements were performed at source-detector centerline distances from 50 to 200 cm. The ratio of air-scatter- and room-return-corrected ambient dose equivalent rates to ambient dose equivalent rates calculated with the code MCNP are tabulated

  4. Characterization of the neutron field of the 241AmBe in a calibration room

    International Nuclear Information System (INIS)

    Vega C, H.R.; Gallego, E.; Lorente, A.

    2003-01-01

    The field of neutrons produced by an isotopic source of neutrons of 241 Am Be had been characterized. The characterization was carried out modeling those relevant details of the calibration room and simulating the neutron transport at different distances of the source. The calculated spectra were used to determine the equivalent environmental dose rate. A series of experiments were carried out with the Bonner sphere spectrometric system to measure the spectra in the same points where the calculations were carried out and with these spectra the rates of environmental dose were calculated. By means of a one sphere dosemeter type Berthold the rates of environmental dose were measured. To the one to compare the calculated spectra and measured its were found small differences in the group of the thermal neutrons due to the elementary composition used during the simulation. When comparing the derived rates starting from the calculated spectra with those measured it was found a maxim difference smaller to 13%. (Author)

  5. Measurements of H*(10) in reference neutron fields using Bonner sphere spectrometry and LET spectrometry

    CERN Document Server

    Golnik, N; Králik, M

    2002-01-01

    A Bonner sphere spectrometer and the REM-2 recombination chamber were used for inter-comparison measurements of the neutron component of ambient dose equivalent, H sub n *(10) in reference neutron fields. The sup 2 sup 4 sup 1 Am-Be and sup 2 sup 5 sup 2 Cf neutron sources were exposed either free-in-air or placed in iron or paraffin filters. The REM-2 recombination chamber was used as a LET spectrometer. The agreement of H sub n *(10) values measured with both the methods was within experimental uncertainties of few percent. The determined neutron spectra were used for calculations of the REM-2 chamber response to H*(10).

  6. Estimate of the neutron fields in ATLAS based on ATLAS-MPX detectors data

    Energy Technology Data Exchange (ETDEWEB)

    Bouchami, J; Dallaire, F; Gutierrez, A; Idarraga, J; Leroy, C; Picard, S; Scallon, O [Universite de Montreal, Montreal, Quebec H3C 3J7 (Canada); Kral, V; PospIsil, S; Solc, J; Suk, M; Turecek, D; Vykydal, Z; Zemlieka, J, E-mail: scallon@lps.umontreal.ca [Institute of Experimental and Applied Physics of the CTU in Prague, Horska 3a/22, CZ-12800 Praha2 - Albertov (Czech Republic)

    2011-01-15

    The ATLAS-MPX detectors are based on Medipix2 silicon devices designed by CERN for the detection of different types of radiation. These detectors are covered with converting layers of {sup 6}LiF and polyethylene (PE) to increase their sensitivity to thermal and fast neutrons, respectively. These devices allow the measurement of the composition and spectroscopic characteristics of the radiation field in ATLAS, particularly of neutrons. These detectors can operate in low or high preset energy threshold mode. The signature of particles interacting in a ATLAS-MPX detector at low threshold are clusters of adjacent pixels with different size and form depending on their type, energy and incidence angle. The classification of particles into different categories can be done using the geometrical parameters of these clusters. The Medipix analysis framework (MAFalda) - based on the ROOT application - allows the recognition of particle tracks left in ATLAS-MPX devices located at various positions in the ATLAS detector and cavern. The pattern recognition obtained from the application of MAFalda was configured to distinguish the response of neutrons from other radiation. The neutron response at low threshold is characterized by clusters of adjoining pixels (heavy tracks and heavy blobs) left by protons and heavy ions resulting from neutron interactions in the converting layers of the ATLAS-MPX devices. The neutron detection efficiency of ATLAS-MPX devices has been determined by the exposure of two detectors of reference to radionuclide sources of neutrons ({sup 252}Cf and {sup 241}AmBe). With these results, an estimate of the neutrons fields produced at the devices locations during ATLAS operation was done.

  7. Estimate of the neutron fields in ATLAS based on ATLAS-MPX detectors data

    International Nuclear Information System (INIS)

    Bouchami, J; Dallaire, F; Gutierrez, A; Idarraga, J; Leroy, C; Picard, S; Scallon, O; Kral, V; PospIsil, S; Solc, J; Suk, M; Turecek, D; Vykydal, Z; Zemlieka, J

    2011-01-01

    The ATLAS-MPX detectors are based on Medipix2 silicon devices designed by CERN for the detection of different types of radiation. These detectors are covered with converting layers of 6 LiF and polyethylene (PE) to increase their sensitivity to thermal and fast neutrons, respectively. These devices allow the measurement of the composition and spectroscopic characteristics of the radiation field in ATLAS, particularly of neutrons. These detectors can operate in low or high preset energy threshold mode. The signature of particles interacting in a ATLAS-MPX detector at low threshold are clusters of adjacent pixels with different size and form depending on their type, energy and incidence angle. The classification of particles into different categories can be done using the geometrical parameters of these clusters. The Medipix analysis framework (MAFalda) - based on the ROOT application - allows the recognition of particle tracks left in ATLAS-MPX devices located at various positions in the ATLAS detector and cavern. The pattern recognition obtained from the application of MAFalda was configured to distinguish the response of neutrons from other radiation. The neutron response at low threshold is characterized by clusters of adjoining pixels (heavy tracks and heavy blobs) left by protons and heavy ions resulting from neutron interactions in the converting layers of the ATLAS-MPX devices. The neutron detection efficiency of ATLAS-MPX devices has been determined by the exposure of two detectors of reference to radionuclide sources of neutrons ( 252 Cf and 241 AmBe). With these results, an estimate of the neutrons fields produced at the devices locations during ATLAS operation was done.

  8. Estimate of the neutron fields in ATLAS based on ATLAS-MPX detectors data

    Science.gov (United States)

    Bouchami, J.; Dallaire, F.; Gutiérrez, A.; Idarraga, J.; Král, V.; Leroy, C.; Picard, S.; Pospíšil, S.; Scallon, O.; Solc, J.; Suk, M.; Turecek, D.; Vykydal, Z.; Žemlièka, J.

    2011-01-01

    The ATLAS-MPX detectors are based on Medipix2 silicon devices designed by CERN for the detection of different types of radiation. These detectors are covered with converting layers of 6LiF and polyethylene (PE) to increase their sensitivity to thermal and fast neutrons, respectively. These devices allow the measurement of the composition and spectroscopic characteristics of the radiation field in ATLAS, particularly of neutrons. These detectors can operate in low or high preset energy threshold mode. The signature of particles interacting in a ATLAS-MPX detector at low threshold are clusters of adjacent pixels with different size and form depending on their type, energy and incidence angle. The classification of particles into different categories can be done using the geometrical parameters of these clusters. The Medipix analysis framework (MAFalda) — based on the ROOT application — allows the recognition of particle tracks left in ATLAS-MPX devices located at various positions in the ATLAS detector and cavern. The pattern recognition obtained from the application of MAFalda was configured to distinguish the response of neutrons from other radiation. The neutron response at low threshold is characterized by clusters of adjoining pixels (heavy tracks and heavy blobs) left by protons and heavy ions resulting from neutron interactions in the converting layers of the ATLAS-MPX devices. The neutron detection efficiency of ATLAS-MPX devices has been determined by the exposure of two detectors of reference to radionuclide sources of neutrons (252Cf and 241AmBe). With these results, an estimate of the neutrons fields produced at the devices locations during ATLAS operation was done.

  9. The measurement of internal stress fields in weldments and around cracks using high resolution neutron diffraction

    International Nuclear Information System (INIS)

    Allen, A.J.; Hutchings, M.T.; Windsor, C.G.

    1987-01-01

    The paper describes and illustrates the capability of neutron diffraction to measure the complete internal lattice macrostrain field, and hence the stress field, within steel components and weldments arising from their fabrication. A brief outline is given of the theory of the neutron method. The experimental considerations are discussed. The method is illustrated by its application to the measurement of the stress distribution in a:- uniaxially stressed mild steel rod, a double - V test weld, a tube-plate weld, and a cracked fatigue test specimen. (U.K.)

  10. Neutron fraction and neutrino mean free path predictions in relativistic mean field models

    International Nuclear Information System (INIS)

    Hutauruk, P.T.P.; Williams, C.K.; Sulaksono, A.; Mart, T.

    2004-01-01

    The equation of state (EOS) of dense matter and neutrino mean free path (NMFP) in a neutron star have been studied by using relativistic mean field models motivated by effective field theory. It is found that the models predict too large proton fractions, although one of the models (G2) predicts an acceptable EOS. This is caused by the isovector terms. Except G2, the other two models predict anomalous NMFP's. In order to minimize the anomaly, besides an acceptable EOS, a large M* is favorable. A model with large M* retains the regularity in the NMFP even for a small neutron fraction

  11. Neutron Crystal-Field Spectroscopy and Susceptibility in ErcY1-cA1

    DEFF Research Database (Denmark)

    Heer, H.; Furrer, A.; Walker, E.

    1974-01-01

    Inelastic neutron scattering experiments and susceptibility measurements have been carried out on polycrystalline ErcY1-cAl2. A least-squares fitting procedure has been applied to the neutron data which favours four sets of crystal-field parameters. The results are compared with the measured...... susceptibility and other bulk magnetic properties. From this it is concluded that the crystal-field parameters x=-0.54 and W=-0.018 meV are the most probable ones....

  12. The influence of the energy distribution of workplace fields on neutron personal dosemeter reading

    International Nuclear Information System (INIS)

    Tanner, R.J.; Thomas, D.J.; Bartlett, D.T.; Hager, L.G.; Horwood, N.A.

    2002-01-01

    Variations in the energy dependence of response of neutron personal dosemeters cause systematic errors in the readings obtained in workplace fields. The magnitude of these errors has been determined theoretically by folding measured and calculated workplace energy distributions with dosemeter response functions, to determine the response of a given personal dosemeter in that field. These results have been analysed with consideration of the dosemeter response to various calibration spectra, and with reference to different workplaces. The dosemeters in the study are discussed in terms of the workplaces for which they can be suitably calibrated. Deficiencies in the published neutron energy distributions are identified

  13. Neutrons field in the neutronic measurements room of the Polytechnic University of Madrid; Campo de neutrones en la sala de medidas neutronicas de la Universidad Politecnica de Madrid

    Energy Technology Data Exchange (ETDEWEB)

    Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Calle Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Gallego, E.; Lorente, A.; Rubio O, I. P., E-mail: hrvegacarrillo@yahoo.com.m [Universidad Politecnica de Madrid, Departamento de Ingenieria Nuclear, C/Jose Gutierrez Abascal No. 2, 28006 Madrid (Spain)

    2010-09-15

    Through of measurements and calculations of a Monte Carlo series has been characterized the neutronic field of the neutronic measurements room of Nuclear Engineering Department of the Polytechnic University of Madrid. The measurements were realized with the Bonner Spheres Spectrometer that allowed establish the spectra on the new stainless steel panel and at different distances measured regarding the source. The values of the speed of environmental equivalent dose were measured with an area monitor Bert hold Lb 6411. Through of Monte Carlo methods was built a detailed model of the room with the panel and the spectra were calculated and, with these the values of the environmental equivalent dose were obtained using the conversion coefficients of the ICRP 74 and the Bert hold Lb 6411 response. The calculated values were compared with those measured and was consistency among the results. (Author)

  14. Signatures of field induced spin polarization of neutron star matter in seismic vibrations of paramagnetic neutron star

    International Nuclear Information System (INIS)

    Bastrukov, S I; Yang, J; Podgainy, D V; Weber, F

    2003-01-01

    A macroscopic model of the dissipative magneto-elastic dynamics of viscous spin polarized nuclear matter is discussed in the context of seismic activity of a paramagnetic neutron star. The source of the magnetic field of such a star is attributed to Pauli paramagnetism of baryon matter promoted by a seed magnetic field frozen into the star in the process of gravitational collapse of a massive progenitor. Particular attention is given to the effect of shear viscosity of incompressible stellar material on the timing of non-radial torsional magneto-elastic pulsations of the star triggered by starquakes. By accentuating the fact that this kind of vibration is unique to the seismology of a paramagnetic neutron star we show that the high-frequency modes decay faster than the low-frequency modes. The obtained analytic expressions for the period and relaxation time of this mode, in which the magnetic susceptibility and viscosity enter as input parameters, are then quantified by numerical estimates for these parameters taken from early and current works on transport coefficients of dense matter. It is found that the effect of viscosity is crucial for the lifetime of magneto-torsion vibrations but it does not appreciably affect the periods of this seismic mode which fall in the realm of periods of pulsed emission of soft gamma-ray repeaters and anomalous x-ray pulsars - young super-magnetized neutron stars, radiating, according to the magnetar model, at the expense of the magnetic energy release. Finally, we present arguments that the long periodic pulsed emission of these stars in a quiescent regime of radiation can be interpreted as a manifestation of weakly damped seismic magneto-torsion vibrations exhibiting the field induced spin polarization of baryon matter

  15. Testing of ENDF/B cross section data in the Californium-252 neutron benchmark field

    International Nuclear Information System (INIS)

    Mannhart, W.

    1979-01-01

    The fission neutron field of 252 Cf presently represents one of the most well-known neutron benchmark fields. For 13 neutron reactions which are of importance in reactor metrology, measurements of spectrum-averaged cross sections, [sigma], performed in this neutron field were compared with calculated average cross sections. This comparison allows one to draw conclusions as to the quality of different sigma(E) data taken from ENDF/B-IV, from ENDF/B-V, and from recent experiments and used in the calculation of average cross sections. The comparison includes an uncertainty analysis regarding the different uncertainty contributions of [sigma], of sigma(E), and of the spectral distribution of 252 Cf fission neutrons. Additionally, in a few examples, sensitivity studies were carried out. The sensitivity of the spectrum-averaged cross sections to individual characteristics of the sigma(E) data, such as normalization factors or shifts in the energy scale, was investigated. Similarly, the sensitivity of [sigma] to the spectral distribution of 252 Cf was determined. 4 figures, 2 tables

  16. Multipolar electromagnetic fields around neutron stars: general-relativistic vacuum solutions

    Science.gov (United States)

    Pétri, J.

    2017-12-01

    Magnetic fields inside and around neutron stars are at the heart of pulsar magnetospheric activity. Strong magnetic fields are responsible for quantum effects, an essential ingredient to produce leptonic pairs and the subsequent broad-band radiation. The variety of electromagnetic field topologies could lead to the observed diversity of neutron star classes. Thus, it is important to include multipolar components to a presumably dominant dipolar magnetic field. Exact analytical solutions for these multipoles in Newtonian gravity have been computed in recent literature. However, flat space-time is not adequate to describe physics in the immediate surroundings of neutron stars. We generalize the multipole expressions to the strong gravity regime by using a slowly rotating metric approximation such as the one expected around neutron stars. Approximate formulae for the electromagnetic field including frame dragging are computed from which we estimate the Poynting flux and the braking index. Corrections to leading order in compactness and spin parameter are presented. As far as spin-down luminosity is concerned, it is shown that frame dragging remains irrelevant. For high-order multipoles starting from the quadrupole, the electric part can radiate more efficiently than the magnetic part. Both analytical and numerical tools are employed.

  17. The Equation of State of Neutron Star Matter in Strong Magnetic Fields

    International Nuclear Information System (INIS)

    Broderick, A.; Prakash, M.; Lattimer, J. M.

    2000-01-01

    We study the effects of very strong magnetic fields on the equation of state (EOS) in multicomponent, interacting matter by developing a covariant description for the inclusion of the anomalous magnetic moments of nucleons. For the description of neutron star matter, we employ a field-theoretical approach, which permits the study of several models that differ in their behavior at high density. Effects of Landau quantization in ultrastrong magnetic fields (B>10 14 G) lead to a reduction in the electron chemical potential and a substantial increase in the proton fraction. We find the generic result for B>10 18 G that the softening of the EOS caused by Landau quantization is overwhelmed by stiffening due to the incorporation of the anomalous magnetic moments of the nucleons. In addition, the neutrons become completely spin polarized. The inclusion of ultrastrong magnetic fields leads to a dramatic increase in the proton fraction, with consequences for the direct Urca process and neutron star cooling. The magnetization of the matter never appears to become very large, as the value of |H/B| never deviates from unity by more than a few percent. Our findings have implications for the structure of neutron stars in the presence of large frozen-in magnetic fields. (c) 2000 The American Astronomical Society

  18. The Equation of State of Neutron Star Matter in Strong Magnetic Fields

    Energy Technology Data Exchange (ETDEWEB)

    Broderick, A; Prakash, M; Lattimer, J M

    2000-07-01

    We study the effects of very strong magnetic fields on the equation of state (EOS) in multicomponent, interacting matter by developing a covariant description for the inclusion of the anomalous magnetic moments of nucleons. For the description of neutron star matter, we employ a field-theoretical approach, which permits the study of several models that differ in their behavior at high density. Effects of Landau quantization in ultrastrong magnetic fields (B>10{sup 14} G) lead to a reduction in the electron chemical potential and a substantial increase in the proton fraction. We find the generic result for B>10{sup 18} G that the softening of the EOS caused by Landau quantization is overwhelmed by stiffening due to the incorporation of the anomalous magnetic moments of the nucleons. In addition, the neutrons become completely spin polarized. The inclusion of ultrastrong magnetic fields leads to a dramatic increase in the proton fraction, with consequences for the direct Urca process and neutron star cooling. The magnetization of the matter never appears to become very large, as the value of |H/B| never deviates from unity by more than a few percent. Our findings have implications for the structure of neutron stars in the presence of large frozen-in magnetic fields. (c) 2000 The American Astronomical Society.

  19. Design of a graphite-moderated {sup 241}Am-Li neutron field to simulate reactor spectra

    Energy Technology Data Exchange (ETDEWEB)

    Tsujimura, N., E-mail: tsujimura.norio@jaea.go.j [Nuclear Fuel Cycle Engineering Laboratories, Japan Atomic Energy Agency, 4-33, Tokai-mura, Ibaraki-ken, 319-1194 (Japan); Yoshida, T. [Nuclear Fuel Cycle Engineering Laboratories, Japan Atomic Energy Agency, 4-33, Tokai-mura, Ibaraki-ken, 319-1194 (Japan)

    2010-12-15

    A neutron calibration field using {sup 241}Am-Li sources and a moderator was designed to simulate the neutron fields found outside a reactor. The moderating assembly selected for the design calculation consists of a cube of graphite blocks with dimensions of 50 cm by 50 cm by 50 cm, in which the {sup 241}Am-Li sources are placed. Monte Carlo calculations revealed the optimal depth of the source to be 15 cm. This moderated neutron source can be used to provide a test field that has a large number of intermediate energy neutrons with a small portion of MeV component.

  20. Development of a hand-held fast neutron survey meter

    International Nuclear Information System (INIS)

    Yoshida, T.; Tsujimura, N.; Yamano, T.

    2011-01-01

    A neutron survey meter with a ZnS(Ag) scintillator to measure recoil protons was built. The detection probe weighs ∼2 kg, therefore providing us with true portability. Performance tests exhibited satisfactory neutron dosimetry characteristics in unmoderated or lightly moderated fission neutron fields and in particular work environments at a mixed oxide fuel facility. This new survey meter will augment a routine of neutron monitoring that is inconveniently being carried out by moderator-based neutron survey meters. (authors)

  1. Fast neutron and gamma-ray transmission technique in mixed samples. MCNP calculations

    International Nuclear Information System (INIS)

    Perez, N.; Padron, I.

    2001-01-01

    In this paper the moisture in sand and also the sulfur content in toluene have been described by using the simultaneous fast neutron/gamma transmission technique (FNGT). Monte Carlo calculations show that it is possible to apply this technique with accelerator-based and isotopic neutron sources in the on-line analysis to perform the product quality control, specifically in the building materials industry and the petroleum one. It has been used particles from a 14MeV neutron generator and also from an Am-Be neutron source. The estimation of optimal system parameters like the efficiency, detection time, hazards and costs were performed in order to compare both neutron sources

  2. Ultra-High Field Magnets for X-Ray and Neutron Scattering using High Temperature Superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Winn, Barry L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Broholm, C. [Johns Hopkins Univ., Baltimore, MD (United States); Bird, M. [Florida State Univ., Tallahassee, FL (United States). National High Magnetic Field Lab. (MagLab); Breneman, Bruce C. [General Atomics, San Diego, CA (United States); Coffey, Michael [Cryomagnetics, Oak Ridge, TN (United States); Cutler, Roy I. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Duckworth, Robert C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Erwin, R. [National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States); Hahn, Seungyong [Florida State Univ., Tallahassee, FL (United States). National High Magnetic Field Lab. (MagLab); Hernandez, Yamali [National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States); Herwig, Kenneth W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Holland, Leo D. [General Atomics, San Diego, CA (United States); Lonergan, Kevin M. [Oxford Instruments, Abingdon (United Kingdom); Melhem, Ziad [Oxford Instruments, Abingdon (United Kingdom); Minter, Stephen J. [Cryomagnetics, Oak Ridge, TN (United States); Nelson, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Paranthaman, M. Parans [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Pierce, Josh [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ruff, Jacob [Cornell Univ., Ithaca, NY (United States); Shen, Tengming [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sherline, Todd E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Smeibidl, Peter G. [Helmholtz-Zentrum Berlin (HZB), (Germany); Tennant, David [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); van der Laan, Danko [Advanced Conductor Technologies, LLC, Boulder, CO (United States); Wahle, Robert J. [Helmholtz-Zentrum Berlin (HZB), (Germany); Zhang, Yifei [SuperPower, Inc., Schenectady, NY (United States)

    2017-01-01

    X-ray and neutron scattering techniques are capable of acquiring information about the structure and dynamics of quantum matter. However, the high-field magnet systems currently available at x-ray and neutron scattering facilities in the United States are limited to fields of 16 tesla (T) at maximum, which precludes applications that require and/or study ultra-high field states of matter. This gap in capability—and the need to address it—is a central conclusion of the 2005 National Academy of Sciences report by the Committee on Opportunities in High Magnetic Field Science. To address this gap, we propose a magnet development program that would more than double the field range accessible to scattering experiments. With the development and use of new ultra-high field–magnets, the program would bring into view new worlds of quantum matter with profound impacts on our understanding of advanced electronic materials.

  3. μ-TPC: a future standard instrument for low energy neutron field characterization

    International Nuclear Information System (INIS)

    Maire, D.; Lebreton, L.; Petit, M.; Billard, J.; Bourrion, O.; Bosson, G.; Guillaudin, O.; Lamblin, J.; Mayet, F.; Medard, J.; Muraz, J.F.; Richer, J.P.; Riffard, Q.; Santos, D.

    2013-06-01

    In order to measure energy of neutron fields, with energy ranging from 8 keV to 1 MeV, a new primary standard is being developed at the IRSN (Institute for Radioprotection and Nuclear Safety). This project, μ-TPC (Micro Time Projection Chamber), carried out in collaboration with the LPSC (Laboratoire de Physique Subatomique et de Cosmologie), is based on the nucleus recoil detector principle. The instrument will be presented with the associated method to measure the neutron energy. This article will emphasize the proton energy calibration procedure and energy measurements of a neutron field produced at 127 keV on the IRSN facility AMANDE. Finally the COMIMAC device, dedicated to the calibration, will be described. This original device, developed at the LPSC, is able to produce proton and electron beams with an accurate energy ranging from 1 keV to 50 keV. (authors)

  4. Relativistic field theory of neutron stars and their hyperon populations

    International Nuclear Information System (INIS)

    Glendenning, N.K.

    1986-01-01

    The nuclear many-body problem is examined by means of the formulation of an effective relativistic field theory of interacting hadrons. A relativistic field theory of hadronic matter is especially appropriate for the description of hot or dense matter, because of the appearance of antiparticles and higher baryon resonances and because it automatically respects causality. 8 refs., 7 figs., 1 tab

  5. Mixed-field GCR Simulations for Radiobiological Research using Ground Based Accelerators

    Science.gov (United States)

    Kim, Myung-Hee Y.; Rusek, Adam; Cucinotta, Francis

    Space radiation is comprised of a large number of particle types and energies, which have differential ionization power from high energy protons to high charge and energy (HZE) particles and secondary neutrons produced by galactic cosmic rays (GCR). Ground based accelerators such as the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory (BNL) are used to simulate space radiation for radiobiology research and dosimetry, electronics parts, and shielding testing using mono-energetic beams for single ion species. As a tool to support research on new risk assessment models, we have developed a stochastic model of heavy ion beams and space radiation effects, the GCR Event-based Risk Model computer code (GERMcode). For radiobiological research on mixed-field space radiation, a new GCR simulator at NSRL is proposed. The NSRL-GCR simulator, which implements the rapid switching mode and the higher energy beam extraction to 1.5 GeV/u, can integrate multiple ions into a single simulation to create GCR Z-spectrum in major energy bins. After considering the GCR environment and energy limitations of NSRL, a GCR reference field is proposed after extensive simulation studies using the GERMcode. The GCR reference field is shown to reproduce the Z and LET spectra of GCR behind shielding within 20 percents accuracy compared to simulated full GCR environments behind shielding. A major challenge for space radiobiology research is to consider chronic GCR exposure of up to 3-years in relation to simulations with cell and animal models of human risks. We discuss possible approaches to map important biological time scales in experimental models using ground-based simulation with extended exposure of up to a few weeks and fractionation approaches at a GCR simulator.

  6. Investigation of Workplace-like Calibration Fields via a Deuterium-Tritium (D-T) Neutron Generator.

    Science.gov (United States)

    Mozhayev, Andrey V; Piper, Roman K; Rathbone, Bruce A; McDonald, Joseph C

    2017-04-01

    Radiation survey meters and personal dosimeters are typically calibrated in reference neutron fields based on conventional radionuclide sources, such as americium-beryllium (Am-Be) or californium-252 (Cf), either unmodified or heavy-water moderated. However, these calibration neutron fields differ significantly from the workplace fields in which most of these survey meters and dosimeters are being used. Although some detectors are designed to yield an approximately dose-equivalent response over a particular neutron energy range, the response of other detectors is highly dependent upon neutron energy. This, in turn, can result in significant over- or underestimation of the intensity of neutron radiation and/or personal dose equivalent determined in the work environment. The use of simulated workplace neutron calibration fields that more closely match those present at the workplace could improve the accuracy of worker, and workplace, neutron dose assessment. This work provides an overview of the neutron fields found around nuclear power reactors and interim spent fuel storage installations based on available data. The feasibility of producing workplace-like calibration fields in an existing calibration facility has been investigated via Monte Carlo simulations. Several moderating assembly configurations, paired with a neutron generator using the deuterium tritium (D-T) fusion reaction, were explored.

  7. Improvement of neutron irradiation field of research reactors for BNCT

    International Nuclear Information System (INIS)

    Aizawa, Otohiko

    1992-01-01

    The modification of research reactors for an improvement of the irradiation field for BNCT has been investigated in comparison with the field characteristics of the 'old' configuration at the Musashi reactor. The new point of this study is that the evaluation has been done by using an arrangement including both the facility structure and a whole-body phantom, and also by considering the whole-body absorbed dose. (author)

  8. Characterisation of neutron fields around high-energy x-ray radiotherapy machines

    Czech Academy of Sciences Publication Activity Database

    Králík, M.; Turek, Karel

    2004-01-01

    Roč. 110, 1-4 (2004), s. 503-507 ISSN 0144-8420 Institutional research plan: CEZ:AV0Z1048901 Keywords : radiotherapy machines * neutron fields * high-energy Subject RIV: DN - Health Impact of the Environment Quality Impact factor: 0.617, year: 2003

  9. Doublet channel neutron-deuteron scattering in leading order effective field theory

    OpenAIRE

    B. BlankleiderFlinders U.; J. Gegelia(INFN)

    2015-01-01

    The doublet channel neutron-deuteron scattering amplitude is calculated in leading order effective field theory (EFT). It is shown that this amplitude does not depend on a constant contact interaction three-body force. Satisfactory agreement with available data is obtained when only two-body forces are included.

  10. Zero Sound in Neutron Stars with Dense Quark Matter under Strong Magnetic Fields

    DEFF Research Database (Denmark)

    Kouvaris, Christoforos

    2009-01-01

    We study a neutron star with a quark matter core under extremely strong magnetic fields. We investigate the possibility of an Urca process as a mechanism for the cooling of such a star. We found that apart from very particular cases, the Urca process cannot occur. We also study the stability...

  11. Extension of the VITESS polarized neutron suite towards the use of imported magnetic field distributions

    International Nuclear Information System (INIS)

    Manoshin, S; Rubtsov, A; Bodnarchuk, V; Mattauch, S; Ioffe, A

    2014-01-01

    Latest developments of the polarized neutron suite in the VITESS simulation package allowed for simulations of time-dependent spin handling devices (e.g. radio-frequency (RF) flippers, adiabatic gradient RF-flippers) and the instrumentation built upon them (NRSE, SESANS, MIEZE, etc.). However, till now the magnetic field distribution in such devices have been considered as 'ideal' (sinusoidal, triangular or rectangular), when the main practical interest is in the use of arbitrary magnetic field distributions (either obtained by the field mapping or by FEM calculations) that may significantly influence the performance of real polarized neutron instruments and is the key issue in the practical use of the simulation packages. Here we describe modified VITESS modules opening the possibility to load the magnetic field 3-dimensional space map from an external source (file). Such a map can be either obtained by direct measurements or calculated by dedicated FEM programs (such as ANSYS, MagNet, Maxwell or similar). The successful use of these new modules is demonstrated by a very good agreement of neutron polarimetric experiments with performance of the spin turner with rotating magnetic field and an adiabatic gradient RF-flipper simulated by VITESS using calculated 3-dimensional field maps (using MagNet) and magnetic field mapping, respectively.

  12. Mixed species flocking of tits (Parus spp.): a field experiment.

    Science.gov (United States)

    Székely, T; Szép, T; Juhász, T

    1989-03-01

    We tested two general models of flocking behaviour, namely the antipredation model and foraging efficiency model on mixed-species tit flocks (Parus spp.). After food addition the size of mixed-species flocks was significantly less than in the control samples. In the presence of extra food significantly more birds were observed either in monospecific flocks or solitary, than during the control observations. In the presence of a living predator the birds foraged in larger mixed-specifies flocks than during the control observations. In addition, the social behaviour of Great Spotted Woodpecker, Middle Spotted Woodpecker and Nuthatch shifted to mixed-specific flocking. The size of monospecific flocks was independent of both treatments. The density of birds increased significantly after food addition, while in the predator presence the birds tended to leave the forest. These results support the view that both the antipredation model and foraging efficiency model seem to be valid for mixed-species flocking. However, in the case of monospecific flocks, the territory maintenance could be the most important factor.

  13. A sensitive search for dark energy through chameleon scalar fields using neutron interferometry

    International Nuclear Information System (INIS)

    Snow, W M; Li, K; Skavysh, V; Arif, M; Huber, M; Heacock, B; Young, A R; Pushin, D

    2015-01-01

    The physical origin of the dark energy, which is postulated to cause the accelerated expansion rate of the universe, is one of the major open questions of cosmology. A large subset of theories postulate the existence of a scalar field with a nonlinear coupling to matter chosen so that the effective range and/or strength of the field is greatly suppressed unless the source is placed in vacuum. We describe a measurement using neutron interferometry which can place a stringent upper bound on chameleon fields proposed as a solution to the problem of the origin of dark energy of the universe in the regime with a strongly-nolinear coupling term. In combination with other experiments searching for exotic short-range forces and laser-based measurements, slow neutron experiments are capable of eliminating this and many similar types of scalar-field-based dark energy models by laboratory experiments

  14. An automated analysis workflow for optimization of force-field parameters using neutron scattering data

    Energy Technology Data Exchange (ETDEWEB)

    Lynch, Vickie E.; Borreguero, Jose M. [Neutron Data Analysis & Visualization Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831 (United States); Bhowmik, Debsindhu [Computational Sciences & Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831 (United States); Ganesh, Panchapakesan; Sumpter, Bobby G. [Center for Nanophase Material Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831 (United States); Computational Sciences & Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831 (United States); Proffen, Thomas E. [Neutron Data Analysis & Visualization Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831 (United States); Goswami, Monojoy, E-mail: goswamim@ornl.gov [Center for Nanophase Material Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831 (United States); Computational Sciences & Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831 (United States)

    2017-07-01

    Graphical abstract: - Highlights: • An automated workflow to optimize force-field parameters. • Used the workflow to optimize force-field parameter for a system containing nanodiamond and tRNA. • The mechanism relies on molecular dynamics simulation and neutron scattering experimental data. • The workflow can be generalized to any other experimental and simulation techniques. - Abstract: Large-scale simulations and data analysis are often required to explain neutron scattering experiments to establish a connection between the fundamental physics at the nanoscale and data probed by neutrons. However, to perform simulations at experimental conditions it is critical to use correct force-field (FF) parameters which are unfortunately not available for most complex experimental systems. In this work, we have developed a workflow optimization technique to provide optimized FF parameters by comparing molecular dynamics (MD) to neutron scattering data. We describe the workflow in detail by using an example system consisting of tRNA and hydrophilic nanodiamonds in a deuterated water (D{sub 2}O) environment. Quasi-elastic neutron scattering (QENS) data show a faster motion of the tRNA in the presence of nanodiamond than without the ND. To compare the QENS and MD results quantitatively, a proper choice of FF parameters is necessary. We use an efficient workflow to optimize the FF parameters between the hydrophilic nanodiamond and water by comparing to the QENS data. Our results show that we can obtain accurate FF parameters by using this technique. The workflow can be generalized to other types of neutron data for FF optimization, such as vibrational spectroscopy and spin echo.

  15. Characterization of ophiolites from northern Havana-Matanzas petroleum fields using instrumental neutron activation analysis

    Energy Technology Data Exchange (ETDEWEB)

    Montero Cabrera, M.E. E-mail: montero@yakko.cimav.edu.mx; Ortueta Milan, M.; Herrera Peraza, E.F.; Herrera Hernandez, H.; Rodriguez Martinez, N.; Olivares Rieumont, S.; Lopez Reyes, M.C

    2001-01-15

    Concentrations of 16 elements from 14 serpentinitic samples from Basilio and Cantel petroleum fields were obtained by instrumental neutron activation analysis (INAA): Cr, Co, Ni, La, Nd, Sm, Eu, Gd, Tb, Ce Yb, Lu, Rb, Cs, Hf and Th. Relative INAA was performed using certified reference materials and laboratory standards. Average elemental concentrations showed that the ophiolites have a basic character, suggesting the use of a well-logging method designed for volcano-sedimentary petroleum fields.

  16. Direct URCA-processes in neutron star quark core with strong magnetic field.

    Directory of Open Access Journals (Sweden)

    Belyaev Vasily

    2017-01-01

    In evaluations, the strength of magnetic field corresponds to the case, where the quarks of medium occupy a lot of Landau levels, while the electrons are in ground Landau level. The analytical dependence of neutrino emissivity on chemical potentials of quarks and electrons, temperature and magnetic field strength is obtained and briefly discussed. The result could be important in application to a massive strongly magnetized neutron star with quark core.

  17. Characterization of ophiolites from northern Havana-Matanzas petroleum fields using instrumental neutron activation analysis

    International Nuclear Information System (INIS)

    Montero Cabrera, M.E.; Ortueta Milan, M.; Herrera Peraza, E.F.; Herrera Hernandez, H.; Rodriguez Martinez, N.; Olivares Rieumont, S.; Lopez Reyes, M.C.

    2001-01-01

    Concentrations of 16 elements from 14 serpentinitic samples from Basilio and Cantel petroleum fields were obtained by instrumental neutron activation analysis (INAA): Cr, Co, Ni, La, Nd, Sm, Eu, Gd, Tb, Ce Yb, Lu, Rb, Cs, Hf and Th. Relative INAA was performed using certified reference materials and laboratory standards. Average elemental concentrations showed that the ophiolites have a basic character, suggesting the use of a well-logging method designed for volcano-sedimentary petroleum fields

  18. A new nonlinear mean-field model of neutron star matter

    CERN Document Server

    Miyazaki, K

    2005-01-01

    A new relativistic mean-field model of neutron star matter is developed. It is a generalization of the Zimanyi-Moszkowski (ZM) model based on the constituent quark picture of baryons. The renormalized meson-hyperon coupling constants in medium are uniquely determined in contrast to the naive extention of ZM model and so the application of the model to high-density neutron star (NS) matter is possible. Our results of the particle composition and the mass-radius relation of NSs agree well with those obtained from the phenomenologically-determined realistic equation-of-state.

  19. The reversed-field-pinch (RFP) fusion neutron source: A conceptual design

    International Nuclear Information System (INIS)

    Bathke, C.G.; Krakowski, R.A.; Miller, R.L.; Werley, K.A.

    1989-01-01

    The conceptual design of an ohmically heated, reversed-field pinch (RFP) operating at ∼5-MW/m 2 steady-state DT fusion neutron wall loading and ∼124-MW total fusion power is presented. These results are useful in projecting the development of a cost effective, low input power (∼206 MW) source of DT neutrons for large-volume (∼10 m 3 ), high-fluence (3.4 MW yr/m 2 ) fusion nuclear materials and technology testing. 19 refs., 15 figs., 9 tabs

  20. Neutron reflectivity studies of electric field driven structural transformations of surfactants

    CERN Document Server

    Majewski, J; Burgess, I; Zamlynny, V; Szymanski, G; Lipkowski, J; Satija, S

    2002-01-01

    We employed electrochemical methods together with in situ neutron reflectometry to describe the aggregation of organic surfactant molecules at a solid-liquid interface. The neutron reflectometry allowed us to determine the surface coverage, thickness, roughness and the relative positions of the aggregates. We found that the applied electric field may be used to reversibly manipulate the architecture of the organic molecules: from uniform monolayers to adsorbed hemi-micelles. These studies are expected to provide a new insight into the roles played by entropic and electrostatic forces in complex fluids or biomaterials. (orig.)

  1. Neutron Star masses from the Field Correlator Method Equation of State

    Directory of Open Access Journals (Sweden)

    Zappalà D.

    2014-04-01

    Full Text Available We analyse the hadron-quark phase transition in neutron stars by confronting the hadronic Equation of State (EoS obtained according to the microscopic Brueckner-Hartree-Fock many body theory, with the quark matter EoS derived within the Field Correlator Method. In particular, the latter EoS is only parametrized in terms of the gluon condensate and the large distance quark-antiquark potential, so that the comparison of the results of this analysis with the most recent measurements of heavy neutron star masses provides some physical constraints on these two parameters.

  2. The impact of ICRP 60 recommendations on the dose equivalent in low- and high energy neutron fields

    Energy Technology Data Exchange (ETDEWEB)

    Jakes, J; Schraube, H [GSF-Forschungszentrum Neuberg, D-85758 Oberschleissheim (Germany). Inst. fuer Strahlenschutz

    1996-12-31

    The objectives of this study was to determine the impact of the increased risk factors for neutrons after ICRP 60 on the operational dose equivalent quantities at a few neutron fields selected with the respect to cover the broad variety of neutron spectra: (1) Cadarache calibration assembly, with average neutron energy around 0.6 MeV, designed to simulate realistic neutron spectra at workplaces. This assembly is basically composed of an almost spherical {sup 238}U converter irradiated by 14.6 MeV neutrons from an accelerator target, placed at its center, and a scattering chamber consisting of a cylindrical polyethylene duct and a series of additional shieldings; (2) Neutron spectra at exposed workplaces in nuclear power plants; (3) Moderated spectra of {sup 252}Cf fission source; (4) Neutron spectra behind a shielding made of the iron (the average energy 5.,89 MeV) and concrete (the average energy 46.51 MeV), respectively; (5) Cosmic rays induced neutron spectra measured on the top of the Zugspitze (2968 m) where there is the average neutron energy around 40 MeV. From the derived neutron spectra, the mean quality factors and conversion factors h after ICRP 21 and ICRP 60, respectively, were calculated. The dose equivalent conversion factors were taken for the region below 20 MeV, and the energy region above 20 MeV. The results show that the operational quantities were affected predominately in the low energy fields, where the changes are given by a factor of 1,3 for the neutron fields given above. As has been expected, the impact of the new recommendations depends on the shape of the neutron spectra. Therefore, this factor can be much higher in the fields where the intermediate energy region is dominant, which is the case of moderated and scattered spectra at some places in the nuclear power plant and around containers with the spent fuel elements. (J.K.) 9 refs.

  3. Neutron spin filter based on optically polarized sup 3 He in a near-zero magnetic field

    CERN Document Server

    Skoy, V R; Sorokin, V N; Kolachevsky, N N; Sobelman, I I; Sermyagin, A V

    2003-01-01

    A test of polarization of sup 3 He nuclei via spin-exchange collisions with optically pumped rubidium atoms in an extremely low applied magnetic field was carried out. Permalloy magnetic shields were used to prevent a fast relaxation of sup 3 He polarization owing to the inhomogeneity of a surrounding magnetic field. The whole installation was placed at the neutron beam line of the IBR-30 facility, and used as a neutron spin filter. Thus, a prototype of new design of neutron polarizer was introduced. We intend to apply this experience for the full-scale KaTRIn facility to test the time reversal violation in neutron-nuclear reactions.

  4. Helium-burning flashes on accreting neutron stars: effects of stellar mass, radius, and magnetic field

    International Nuclear Information System (INIS)

    Joss, P.C.; Li, F.K.

    1980-01-01

    We have computed the evolution of the helium-burning shell in an accreting neutron star for various values of the stellar mass (M), radius (R), and surface magnetic fields strength (B). As shown in previous work, the helium-burning shell is often unstable and undergoes thermonuclear flashes that result in the emission of X-ray bursts from the neutron-star surface. The dependence of the properties of these bursts upon the values of M and R can be described by simple scaling relations. A strong magnetic field decreases the radiative and conductive opacities and inhibits convection in the neutron-star surface layers. For B 12 gauss, these effects are unimportant; for B> or approx. =10 13 gauss, the enhancement of the electron thermal conductivity is sufficiently large to stabilize the helium-burning shell against thermonuclear flashes. For intermediate values of B, the reduced opacities increase the recurrence intervals between bursts and the energy released per burst, while the inhibition of convection increases the burst rise times to about a few seconds. If the magnetic field funnels the accreting matter onto the magnetic polar caps, the instability of the helium-burning shell will be very strongly suppressed. These results suggest that it may eventually be possible to extract information on the macroscopic properties of neutron stars from the observed features of X-ray burst sources

  5. Cryogen free high magnetic field and low temperature sample environments for neutron scattering - latest developments

    International Nuclear Information System (INIS)

    Burgoyne, John

    2016-01-01

    Continuous progress has been made over many years now in the provision of low- and ultra-low temperature sample environments, together with new high-field superconducting magnets and increased convenience for both the user and the neutron research facility via new cooling technologies. Within Oxford Instrument's experience, this has been achieved in many cases through close collaboration with neutron scientists, and with the neutron facilities' sample environment leaders in particular. Superconducting magnet designs ranging from compact Small Angle (SANS) systems up to custom-engineered wide-angle scattering systems have been continuously developed. Recondensing, or 'zero boil-off' (ZBO), systems are well established for situations in which a high field magnet is not conducive to totally cryogen free cooling solutions, and offer a reliable route with the best trade-offs of maximum system capability versus running costs and user convenience. Fully cryogen free solutions for cryostats, dilution refrigerators, and medium-field magnets are readily available. Here we will present the latest technology developments in these options, describing the state-of-the art, the relative advantages of each, and the opportunities they offer to the neutron science community. (author)

  6. Crystalline Electric Field Levels in the Neodymium Monopnictides Determined by Neutron Spectroscopy

    DEFF Research Database (Denmark)

    Furrer, A.; Kjems, Jørgen; Vogt, O.

    1972-01-01

    Neutron inelastic scattering experiments have been carried out to determine the energies and widths of the crystalline electric field levels in the neodymium monopnictides NdP, NdAs, and NdSb. The energy level sequence is derived from the observed crystal field transition peak intensities, which...... are in good agreement with calculations based on elementary crystal field theory. The energy level widths are qualitatively discussed. It is found that the point-charge model cannot reproduce the crystal field levels satisfactorily....

  7. Field and laboratory investigation of warm mix asphalt in Texas.

    Science.gov (United States)

    2010-07-01

    During the first half of this research study, TxDOT had only placed 1000 tons of warm mix asphalt : (WMA) as part of a demonstration project. By the end of this three year study, TxDOT had placed more : than 1,000,000 tons of WMA and allowed its use ...

  8. A Search for Black Holes and Neutron Stars in the Kepler Field

    Science.gov (United States)

    Orosz, Jerome; Short, Donald; Welsh, William; Windmiller, Gur; Dabney, David

    2018-01-01

    Black holes and neutron stars represent the final evolutionary stages of the most massive stars. In addition to their use as probes into the evolution of massive stars, black holes and neutron stars are ideal laboratories to test General Relativity in the strong field limit. The number of neutron stars and black holes in the Milky Way is not precisely known, but there are an estimated one billion neutron stars in the galaxy based on the observed numbers of radio pulsars. The number of black holes is about 100 million, based on the behavior of the Initial Mass Function at high stellar masses.All of the known steller-mass black holes (and a fair number of neutron stars) are in ``X-ray binaries'' that were discovered because of their luminous X-ray emission. The requirement to be in an X-ray-emitting binary places a strong observational bias on the discovery of stellar-mass black holes. Thus the 21 known black hole binaries represent only the very uppermost tip of the population iceberg.We have conducted an optical survey using Kepler data designed to uncover black holes and neutron stars in both ``quiescent'' X-ray binaries and ``pre-contact'' X-ray binaries. We discuss how the search was conducted, including how potentially interesting light curves were classified and the how variability types were identified. Although we did not find any convincing candidate neutron star or black hole systems, we did find a few noteworthy binary systems, including two binaries that contain low-mass stars with unusually low albedos.

  9. Inelastic neutron scattering study of crystal field levels in PrOs4As12

    International Nuclear Information System (INIS)

    Chi, Songxue; Dai, Pengcheng; Barnes, T.F.E.; Kang, H. J.; Lynn, J. W.; Ye, Feng; Maple, M. B.

    2008-01-01

    We use neutron scattering to study the Pr 3+ crystalline electric field (CEF) excitations in the filled skutterudite PrOs 4 As 12 . By comparing the observed levels and their strengths under neutron excitation with the theoretical spectrum and neutron excitation intensities, we identify the Pr 3+ CEF levels, and show that the ground state is a magnetic Γ 4 (2) triplet, and the excited states Γ 1 , Γ 4 (1) and Γ 23 are at 0.4, 13 and 23 meV, respectively. A comparison of the observed CEF levels in PrOs 4 As 12 with the heavy fermion superconductor PrOs 4 Sb 12 reveals the microscopic origin of the differences in the ground states of these two filled skutterudites

  10. Neutronics and radiation field studies for the RIA fragmentation target area

    Energy Technology Data Exchange (ETDEWEB)

    Reyes, Susana [Lawrence Livermore National Laboratory, P.O. Box 808, L-446, Livermore, CA 94550 (United States)]. E-mail: reyes20@llnl.gov; Boles, Jason L. [Lawrence Livermore National Laboratory, P.O. Box 808, L-446, Livermore, CA 94550 (United States); Ahle, Larry E. [Lawrence Livermore National Laboratory, P.O. Box 808, L-446, Livermore, CA 94550 (United States); Stein, Werner [Lawrence Livermore National Laboratory, P.O. Box 808, L-446, Livermore, CA 94550 (United States)

    2006-06-23

    Neutronics simulations and activation evaluations are currently in progress as part of the pre-conceptual research and development effort for the Rare Isotope Accelerator (RIA). The RIA project involves generating heavy element ion beams with powers up to 400 kw for use in a fragmentation target line to produce selected ion beams for physics research experiments. Designing a fragmentation beam dump for RIA is one of the most critical challenges for such a facility. Here, we present the results from neutronics and radiation field assessments for various beam dump concepts that can meet requirements for the RIA fragmentation line. Preliminary results from heavy ion transport including radiation damage evaluations for the RIA fragmentation beam dump are also presented. Initial neutronics and activation studies will be incorporated with other target area considerations to identify important challenges and explore possible solutions.

  11. Neutronics and radiation field studies for the RIA fragmentation target area

    Science.gov (United States)

    Reyes, Susana; Boles, Jason L.; Ahle, Larry E.; Stein, Werner

    2006-06-01

    Neutronics simulations and activation evaluations are currently in progress as part of the pre-conceptual research and development effort for the Rare Isotope Accelerator (RIA). The RIA project involves generating heavy element ion beams with powers up to 400 kW for use in a fragmentation target line to produce selected ion beams for physics research experiments. Designing a fragmentation beam dump for RIA is one of the most critical challenges for such a facility. Here, we present the results from neutronics and radiation field assessments for various beam dump concepts that can meet requirements for the RIA fragmentation line. Preliminary results from heavy ion transport including radiation damage evaluations for the RIA fragmentation beam dump are also presented. Initial neutronics and activation studies will be incorporated with other target area considerations to identify important challenges and explore possible solutions.

  12. Neutron measurements in the stray field produced by 158 GeV/c lead ion beams

    International Nuclear Information System (INIS)

    Agosteo, S.; Birattari, C.; Foglio Para, A.; Nava, E.; Silari, M.; Ulrici, L.

    1997-01-01

    This paper discusses measurements carried out at CERN in the stray radiation field produced by 158 GeV/c 208 Pb 82+ ions. The purpose was to test and intercompare the response of several detectors, mainly neutron measuring devices, and to determine the neutron spectral fluence as well as the microdosimetric (absorbed dose and dose equivalent) distributions in different locations around the shielding. Both active instruments and passive dosimeters were employed, including different types of Andersson-Braun rem counters, a tissue equivalent proportional counter, a set of superheated drop detectors, a Bonner sphere system and different types of ion chambers. Activation measurements with 12 C plastic scintillators and with 32 S pellets were also performed to assess the neutron yield of high energy lead ions interacting with a thin gold target. The results are compared with previous measurements and with measurements made during proton runs. (author)

  13. Energy and direction distribution of neutrons in workplace fields: Implication of the results from the EVIDOS project for the set-up of simulated workplace fields

    International Nuclear Information System (INIS)

    Luszik-Bhadra, M.; Lacoste, V.; Reginatto, M.; Zimbal, A.

    2007-01-01

    Workplace neutron spectra from nuclear facilities obtained within the European project EVIDOS are compared with those of the simulated workplace fields CANEL and SIGMA and fields set-up with radionuclide sources at the PTB. Contributions of neutrons to ambient dose equivalent and personal dose equivalent are given in three energy intervals (for thermal, intermediate and fast neutrons) together with the corresponding direction distribution, characterised by three different types of distributions (isotropic, weakly directed and directed). The comparison shows that none of the simulated workplace fields investigated here can model all the characteristics of the fields observed at power reactors. (authors)

  14. Using Cosmic-Ray Neutron Probes to Monitor Landscape Scale Soil Water Content in Mixed Land Use Agricultural Systems

    International Nuclear Information System (INIS)

    Franz, Trenton E.; Wahbi, Ammar; Weltin, Georg; Heng, Lee; Dercon, Gerd; Vreugdenhi, Mariette; Oismueller, Markus; Strauss, Peter; Desilets, Darin

    2016-01-01

    With an ever-increasing demand for natural resources and the societal need to understand and predict natural disasters such as flood, soil water content (SWC) observations remain a critical variable to monitor in order to optimally allocate resources, establish early warning systems, and improve weather forecasts. However, routine agricultural production practices of soil cultivation, planting, and harvest make the operation and maintenance of direct contact point sensors for long-term monitoring a challenging task. In this work, we used Cosmic-Ray Neutron Probe (CRNP) to monitor landscape average SWC in a mixed agricultural land use system in northeast Austria since December 2013.

  15. Calibration of PADC-based neutron area dosemeters in the neutron field produced in the treatment room of a medical LINAC

    International Nuclear Information System (INIS)

    Bedogni, R.; Domingo, C.; Esposito, A.; Gentile, A.; García-Fusté, M.J.; San-Pedro, M. de; Tana, L.; D’Errico, F.; Ciolini, R.; Di Fulvio, A.

    2013-01-01

    PADC-based nuclear track detectors have been widely used as convenient ambient dosemeters in many working places. However, due to the large energy dependence of their response in terms of ambient dose equivalent (H ∗ (10)) and to the diversity of workplace fields in terms of energy distribution, the appropriate calibration of these dosemeters is a delicate task. These are among the reasons why ISO has introduced the 12789 Series of Standards, where the simulated workplace neutron fields are introduced and their use to calibrate neutron dosemeters is recommended. This approach was applied in the present work to the UAB PADC-based nuclear track detectors. As a suitable workplace, the treatment room of a 15 MV Varian CLINAC DHX medical accelerator, located in the Ospedale S. Chiara (Pisa), was chosen. Here the neutron spectra in two points of tests (1.5 m and 2 m from the isocenter) were determined with the INFN-LNF Bonner Sphere Spectrometer equipped with Dysprosium activation foils (Dy-BSS), and the values of H ∗ (10) were derived on this basis. The PADC dosemeters were exposed in these points. Their workplace specific H*(10) responses were determined and compared with those previously obtained in different simulated workplace or reference (ISO 8529) neutron fields. - Highlights: ► The neutron field of a medical LINAC was used to calibrate PADC neutron dosemeters. ► The neutron spectra were derived with a Dy-foil based Bonner Sphere Spectrometer. ► Workplace specific calibration factor were derived for the PADC dosemeters. ► These factors were compared with those obtained in reference neutron fields

  16. Relativistic mean field model for entrainment in general relativistic superfluid neutron stars

    International Nuclear Information System (INIS)

    Comer, G.L.; Joynt, R.

    2003-01-01

    General relativistic superfluid neutron stars have a significantly more intricate dynamics than their ordinary fluid counterparts. Superfluidity allows different superfluid (and superconducting) species of particles to have independent fluid flows, a consequence of which is that the fluid equations of motion contain as many fluid element velocities as superfluid species. Whenever the particles of one superfluid interact with those of another, the momentum of each superfluid will be a linear combination of both superfluid velocities. This leads to the so-called entrainment effect whereby the motion of one superfluid will induce a momentum in the other superfluid. We have constructed a fully relativistic model for entrainment between superfluid neutrons and superconducting protons using a relativistic σ-ω mean field model for the nucleons and their interactions. In this context there are two notions of 'relativistic': relativistic motion of the individual nucleons with respect to a local region of the star (i.e. a fluid element containing, say, an Avogadro's number of particles), and the motion of fluid elements with respect to the rest of the star. While it is the case that the fluid elements will typically maintain average speeds at a fraction of that of light, the supranuclear densities in the core of a neutron star can make the nucleons themselves have quite high average speeds within each fluid element. The formalism is applied to the problem of slowly rotating superfluid neutron star configurations, a distinguishing characteristic being that the neutrons can rotate at a rate different from that of the protons

  17. Time dependet behaviour of the neutron field in in two interacting cylindrical disks

    International Nuclear Information System (INIS)

    Hedlund, T.

    1979-01-01

    The influence of a void on the neutron flux in a moderating system has been studied mainly by the Monte Carlo method. The calculations simulate the decay of the neutron field in a pulsed neutron source measurement. The neutron flux was studied as a function of space, angle, energy and time for a system of two flat cylindrical polyethylene disks. The slab thickness was varied between 1.1 and 4.4 cm and the radius was 9.0 cm. The gap between the slabs was varied from zero to 18 cm. Some calculations have also been made for absorbers in the gap. The purpose of these absorbers was to eliminate the time delay effect for the low velocity neutrons accumulating in the gap. The calculations showed the usefulness of the absorber method. From the results in the time dependent cases the interaction parameter for the two slabs in the corresponding stationary cases has been calculated. The agreement with measurements made by Grosshoeg is good. In the one velocity cases some other methods have also been used to predict the decay rates. For small gap widths the best agreement with the Monte Carlo results was obtained with the variational method. (author)

  18. 40-Tesla pulsed-field cryomagnet for single crystal neutron diffraction

    Science.gov (United States)

    Duc, F.; Tonon, X.; Billette, J.; Rollet, B.; Knafo, W.; Bourdarot, F.; Béard, J.; Mantegazza, F.; Longuet, B.; Lorenzo, J. E.; Lelièvre-Berna, E.; Frings, P.; Regnault, L.-P.

    2018-05-01

    We present the first long-duration and high duty cycle 40-T pulsed-field cryomagnet addressed to single crystal neutron diffraction experiments at temperatures down to 2 K. The magnet produces a horizontal field in a bi-conical geometry, ±15° and ±30° upstream and downstream of the sample, respectively. Using a 1.15 MJ mobile generator, magnetic field pulses of 100 ms length are generated in the magnet, with a rise time of 23 ms and a repetition rate of 6-7 pulses per hour at 40 T. The setup was validated for neutron diffraction on the CEA-CRG three-axis spectrometer IN22 at the Institut Laue Langevin.

  19. Magnetic field strength of a neutron-star-powered ultraluminous X-ray source

    Science.gov (United States)

    Brightman, M.; Harrison, F. A.; Fürst, F.; Middleton, M. J.; Walton, D. J.; Stern, D.; Fabian, A. C.; Heida, M.; Barret, D.; Bachetti, M.

    2018-04-01

    Ultraluminous X-ray sources (ULXs) are bright X-ray sources in nearby galaxies not associated with the central supermassive black hole. Their luminosities imply they are powered by either an extreme accretion rate onto a compact stellar remnant, or an intermediate mass ( 100-105M⊙) black hole1. Recently detected coherent pulsations coming from three bright ULXs2-5 demonstrate that some of these sources are powered by accretion onto a neutron star, implying accretion rates significantly in excess of the Eddington limit, a high degree of geometric beaming, or both. The physical challenges associated with the high implied accretion rates can be mitigated if the neutron star surface field is very high (1014 G)6, since this suppresses the electron scattering cross-section, reducing the radiation pressure that chokes off accretion for high luminosities. Surface magnetic field strengths can be determined through cyclotron resonance scattering features7,8 produced by the transition of charged particles between quantized Landau levels. Here, we present the detection at a significance of 3.8σ of an absorption line at 4.5 keV in the Chandra spectrum of a ULX in M51. This feature is likely to be a cyclotron resonance scattering feature produced by the strong magnetic field of a neutron star. Assuming scattering off electrons, the magnetic field strength is implied to be 1011 G, while protons would imply a magnetic field of B 1015 G.

  20. Digital marketing mix specific to the IT Field

    Directory of Open Access Journals (Sweden)

    Loredana PATRUTIU BALTES

    2016-07-01

    Full Text Available In a world in which digitalization seems to monopolize more and more the business environment, IT companies are the ones which have initiated and felt the most its impact. If, for many companies, digitalization of the marketing strategy is a very attractive option, for IT companies it becomes a “sine qua non” condition. In this context, the traditional marketing mix has undergone extensive transformations and the marketing strategy of the companies has been rethought for the digital environment. Without this adjustment, any marketing strategy will fail in the future. This article presents the 4 basic policies (product, price, placement, promotion policies of the marketing mix adapted to the digitalization context, which can be valid for any company that wants to explore the benefits of the digital market, and especially for IT companies.

  1. Digital marketing mix specific to the IT Field

    OpenAIRE

    Loredana PATRUTIU BALTES

    2016-01-01

    In a world in which digitalization seems to monopolize more and more the business environment, IT companies are the ones which have initiated and felt the most its impact. If, for many companies, digitalization of the marketing strategy is a very attractive option, for IT companies it becomes a “sine qua non” condition. In this context, the traditional marketing mix has undergone extensive transformations and the marketing strategy of the companies has been rethought for the di...

  2. Characterization of the neutron field at the ISIS-VESUVIO facility by means of a bonner sphere spectrometer

    International Nuclear Information System (INIS)

    Bedogni, Roberto; Esposito, Adolfo; Andreani, Carla; Senesi, Roberto; De Pascale, Maria Pia; Picozza, Piergiorgio; Pietropaolo, Antonino; Gorini, Giuseppe; Frost, Christopher D.; Ansell, Stewart

    2009-01-01

    One of the more actual and promising fields of applied neutron physics is the investigation of the malfunctions induced by high-energy neutrons naturally present in the atmosphere in electronic devices, called single event effects (SEE). These studies are of primary importance for the design of devices that have to fulfill high reliability requirements and those that are likely to be exposed to enhanced levels of cosmic rays background, e.g. in aerospace and avionic applications. Particle accelerators-driven neutron sources constitute valuable irradiation facilities for these purposes as they provide an opportunity for accelerated testing of the effects of these naturally occurring neutrons, provided the neutron spectrum is comparable with the atmospheric one and the neutron fields are known with high accuracy. The latter can be achieved through the use of appropriate radiation transport codes and neutron spectrometry techniques. In view of the design and construction of CHIPIR, a dedicated beam line for SEE studies at the ISIS pulsed neutron source second target station (UK) ((http://ts-2.isis.rl.ac.uk/instruments/phase2/index.htm)), a spectrometric characterization was performed on the VESUVIO beamline (Senesi et al.,2000). The spectrometric technique was the bonner sphere spectrometer (BSS), widely used to determine neutron spectra and dose quantities around high-energy accelerators. The experimental campaign provided a complete spectrometric investigation of the VESUVIO neutron beam, allowing the integral quantities (total fluence rate, fraction of fluence in given energy intervals) to be estimated with uncertainties lower than 10%.

  3. Characterization of the neutron field at the ISIS-VESUVIO facility by means of a bonner sphere spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Bedogni, Roberto; Esposito, Adolfo [INFN-LNF Via E. Fermi n. 40-00044 Frascati (RM) (Italy); Andreani, Carla [Universita degli Studi di Roma Tor Vergata, Dipartimento di Fisica e Centro NAST, Via R. Scientifica 1, 00133 Roma (Italy); Senesi, Roberto, E-mail: roberto.senesi@roma2.infn.i [Universita degli Studi di Roma Tor Vergata, Dipartimento di Fisica e Centro NAST, Via R. Scientifica 1, 00133 Roma (Italy); De Pascale, Maria Pia; Picozza, Piergiorgio [Universita degli Studi di Roma Tor Vergata, Dipartimento di Fisica e Centro NAST, Via R. Scientifica 1, 00133 Roma (Italy); Pietropaolo, Antonino; Gorini, Giuseppe [CNISM and Universita degli Studi di Milano Bicocca, Dipartimento di Fisica ' G. Occhialini' , Piazza della Scienza 3, 20126 Milano (Italy); Frost, Christopher D. [INFN-LNF Via E. Fermi n. 40-00044 Frascati (RM) (Italy); Universita degli Studi di Roma Tor Vergata, Dipartimento di Fisica e Centro NAST, Via R. Scientifica 1, 00133 Roma (Italy); CNISM and Universita degli Studi di Milano Bicocca, Dipartimento di Fisica ' G. Occhialini' , Piazza della Scienza 3, 20126 Milano (Italy); STFC Rutherford Appleton Laboratory, ISIS Facility, Harwell Science and Innovation Campus, Didcot, Oxon, OX11 0QX (United Kingdom); Ansell, Stewart [STFC Rutherford Appleton Laboratory, ISIS Facility, Harwell Science and Innovation Campus, Didcot, Oxon, OX11 0QX (United Kingdom)

    2009-12-21

    One of the more actual and promising fields of applied neutron physics is the investigation of the malfunctions induced by high-energy neutrons naturally present in the atmosphere in electronic devices, called single event effects (SEE). These studies are of primary importance for the design of devices that have to fulfill high reliability requirements and those that are likely to be exposed to enhanced levels of cosmic rays background, e.g. in aerospace and avionic applications. Particle accelerators-driven neutron sources constitute valuable irradiation facilities for these purposes as they provide an opportunity for accelerated testing of the effects of these naturally occurring neutrons, provided the neutron spectrum is comparable with the atmospheric one and the neutron fields are known with high accuracy. The latter can be achieved through the use of appropriate radiation transport codes and neutron spectrometry techniques. In view of the design and construction of CHIPIR, a dedicated beam line for SEE studies at the ISIS pulsed neutron source second target station (UK) ((http://ts-2.isis.rl.ac.uk/instruments/phase2/index.htm)), a spectrometric characterization was performed on the VESUVIO beamline (Senesi et al.,2000). The spectrometric technique was the bonner sphere spectrometer (BSS), widely used to determine neutron spectra and dose quantities around high-energy accelerators. The experimental campaign provided a complete spectrometric investigation of the VESUVIO neutron beam, allowing the integral quantities (total fluence rate, fraction of fluence in given energy intervals) to be estimated with uncertainties lower than 10%.

  4. Thermal annealing and recoil reactions of 128I atoms in thermal neutron activated iodate-nitrate mixed crystals

    International Nuclear Information System (INIS)

    Mishra, S.P.; Sharma, R.B.

    1983-01-01

    Recoil reaction of 128 I atoms in neutron irradiated mixed crystals (iodate-nitrate) have been studied by thermal annealing methods. The retention of 128 I (i.e. radioactivity of 128 I retained in the parent chemi cal form) decreases sharply in the beginning and then attains saturation value with the increase in concentration of nitrate. The annealing followed the usual characteristic pattern, viz., a steep rise in retention within the first few minutes and then a saturation value thereafter but these saturation values in case of mixed crystals are lower in comparison to those of pure iodate targets. The process obeys simple first order kinetics and the activation energy obtained are of lower order than those obtained in case of pure targets. The results are discussed in the light of present ideas and the role of nitrate ion and its radiolytic products have also been invoked. (author)

  5. DOSIMETRIC response of a REM-500 in low energy neutron fields typical of nuclear power plants.

    Science.gov (United States)

    Aslam; Matysiak, W; Atanackovic, J; Waker, A J

    2012-06-01

    This study investigates the response of a REM-500 to assess neutron quality factor and dose equivalent in low energy neutron fields, which are commonly encountered in the workplace environment of nuclear power stations. The McMaster University 3 MV Van de Graaff accelerator facility was used to measure the response of the instrument in monoenergetic neutron fields in the energy range 51 to 727 keV by bombarding a thin LiF target with 1.93-2.50 MeV protons. The energy distribution of the neutron fields produced in the facility was measured by a (3)He filled gas ionization chamber. The MCA mode of the REM-500 instrument was used to collect lineal energy distributions at varying neutron energies and to calculate the frequency and dose-mean lineal energies. The effective quality factor, Q-, was also calculated using the values of Q(y)listed in the REM-500 operation manual and compared with those of ICRP 60. The authors observed a continuously increasing trend in y - F, y-D, and Q-with an increase in neutron energy. It is interesting to note that standard tissue equivalent proportional counters (TEPCs) filled with tissue equivalent(TE) gas give rise to a similar trend for these microdosimetric quantities of interest in the same energy range; however, the averages calculated in this study are larger by about 15%compared to a TEPC filled with propane-based TE gas probably because of the larger stopping power of protons in propane compared to TE gas. These somewhat larger event sizes did not result in any significant increase in the Q-compared to those obtained from a TEPC filled with TE gas and were found to be in good agreement with other measurements reported earlier at corresponding neutron energies. The instrument quality factor response, R(Q), defined as the ratio of measured quality factor to the calculated quality factor in an ICRU tissue sphere,was found to vary with neutron energy. The instrument response,R(Q), was ~0.6 at 727 keV, which deteriorates further to

  6. Mixed Far-Field and Near-Field Source Localization Algorithm via Sparse Subarrays

    Directory of Open Access Journals (Sweden)

    Jiaqi Song

    2018-01-01

    Full Text Available Based on a dual-size shift invariance sparse linear array, this paper presents a novel algorithm for the localization of mixed far-field and near-field sources. First, by constructing a cumulant matrix with only direction-of-arrival (DOA information, the proposed algorithm decouples the DOA estimation from the range estimation. The cumulant-domain quarter-wavelength invariance yields unambiguous estimates of DOAs, which are then used as coarse references to disambiguate the phase ambiguities in fine estimates induced from the larger spatial invariance. Then, based on the estimated DOAs, another cumulant matrix is derived and decoupled to generate unambiguous and cyclically ambiguous estimates of range parameter. According to the coarse range estimation, the types of sources can be identified and the unambiguous fine range estimates of NF sources are obtained after disambiguation. Compared with some existing algorithms, the proposed algorithm enjoys extended array aperture and higher estimation accuracy. Simulation results are given to validate the performance of the proposed algorithm.

  7. Intercomparison of radiation protection devices in a high-energy stray neutron field. Part III: Instrument response

    International Nuclear Information System (INIS)

    Silari, M.; Agosteo, S.; Beck, P.; Bedogni, R.; Cale, E.; Caresana, M.; Domingo, C.; Donadille, L.; Dubourg, N.; Esposito, A.; Fehrenbacher, G.; Fernandez, F.; Ferrarini, M.; Fiechtner, A.; Fuchs, A.; Garcia, M.J.; Golnik, N.; Gutermuth, F.; Khurana, S.; Klages, Th.

    2009-01-01

    The European Commission has funded within its 6th Framework Programme a three-year project (2005-2007) called CONRAD, COordinated Network for RAdiation Dosimetry. The organizational framework for this project was provided by the European radiation Dosimetry Group EURADOS. Work Package 6 of CONRAD dealt with 'complex mixed radiation fields at workplaces' and in this context it organised a benchmark exercise, which included both measurements and calculations, in a stray radiation field at a high-energy particle accelerator at GSI, Germany. The aim was to intercompare the response of several types of active detectors and passive dosemeters in a well-characterised workplace field. The Monte Carlo simulations of the radiation field and the experimental determination of the neutron spectra with various Bonner Sphere Spectrometers are discussed in Rollet et al. (2008) and in Wiegel et al. (2008). This paper focuses on the intercomparison of the response of the dosemeters in terms of ambient dose equivalent. The paper describes in detail the detectors employed in the experiment, followed by a discussion of the results. A comparison is also made with the H*(10) values predicted by the Monte Carlo simulations and those measured by the BSS systems.

  8. Study of the neutronic performances of cores with mixed nitride fuel [(U,Pu)N] for fast neutron reactors

    International Nuclear Information System (INIS)

    Merzouk, Hamid

    1992-01-01

    This paper proposes a core design of fast reactor using mixed nitride fuel [(U,Pu)N], having small loss of reactivity and reaching a maximum thermal burn-up rate from 150 GWd/t, while being managed in single batch (renewal of the fuel in only one time for all the subassemblies of the core). This work was completed with aid of the studies of sensibilities of the fast reactors cores to principal parameters: general design of the core, volumetric percentages of the various mixture of materials composing the core, initial enrichments of the fuel. A detailed optimization study on the selected core was conducted complying with safety criteria taking into consideration of consequences of nitride material presence on fuel assembly design rules. (author) [fr

  9. Field calibration of PADC track etch detectors for local neutron dosimetry in man using different radiation qualities

    Energy Technology Data Exchange (ETDEWEB)

    Haelg, Roger A., E-mail: rhaelg@phys.ethz.ch [Institute for Radiotherapy, Radiotherapie Hirslanden AG, Hirslanden Medical Center, Rain 34, CH-5000 Aarau (Switzerland); Besserer, Juergen [Institute for Radiotherapy, Radiotherapie Hirslanden AG, Hirslanden Medical Center, Rain 34, CH-5000 Aarau (Switzerland); Boschung, Markus; Mayer, Sabine [Division for Radiation Safety and Security, Paul Scherrer Institut, CH-5232 Villigen (Switzerland); Clasie, Benjamin [Department of Radiation Oncology, Massachusetts General Hospital, 30 Fruit Street, Boston, MA 02114 (United States); Kry, Stephen F. [Department of Radiation Physics, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030 (United States); Schneider, Uwe [Institute for Radiotherapy, Radiotherapie Hirslanden AG, Hirslanden Medical Center, Rain 34, CH-5000 Aarau (Switzerland); Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 204, CH-8057 Zurich (Switzerland)

    2012-12-01

    In order to quantify the dose from neutrons to a patient for contemporary radiation treatment techniques, measurements inside phantoms, representing the patient, are necessary. Published reports on neutron dose measurements cover measurements performed free in air or on the surface of phantoms and the doses are expressed in terms of personal dose equivalent or ambient dose equivalent. This study focuses on measurements of local neutron doses inside a radiotherapy phantom and presents a field calibration procedure for PADC track etch detectors. An initial absolute calibration factor in terms of H{sub p}(10) for personal dosimetry is converted into neutron dose equivalent and additional calibration factors are derived to account for the spectral changes in the neutron fluence for different radiation therapy beam qualities and depths in the phantom. The neutron spectra used for the calculation of the calibration factors are determined in different depths by Monte Carlo simulations for the investigated radiation qualities. These spectra are used together with the energy dependent response function of the PADC detectors to account for the spectral changes in the neutron fluence. The resulting total calibration factors are 0.76 for a photon beam (in- and out-of-field), 1.00 (in-field) and 0.84 (out-of-field) for an active proton beam and 1.05 (in-field) and 0.91 (out-of-field) for a passive proton beam, respectively. The uncertainty for neutron dose measurements using this field calibration method is less than 40%. The extended calibration procedure presented in this work showed that it is possible to use PADC track etch detectors for measurements of local neutron dose equivalent inside anthropomorphic phantoms by accounting for spectral changes in the neutron fluence.

  10. Naturalness of Nonlinear Scalar Self-Couplings in a Relativistic Mean Field Theory for Neutron Stars

    International Nuclear Information System (INIS)

    Maekawa, Claudio; Razeira, Moises; Vasconcellos, Cesar A. Z.; Dillig, Manfred; Bodmann, Bardo E. J.

    2004-01-01

    We investigate the role of naturalness in effective field theory. We focus on dense hadronic matter using a generalized relativistic multi-baryon lagrangian density mean field approach which contains nonlinear self-couplings of the σ, δ meson fields and the fundamental baryon octet. We adjust the model parameters to describe bulk static properties of ordinary nuclear matter. Then, we show that our approach represents a natural modelling of nuclear matter under the extreme conditions of density as the ones found in the interior of neutron stars

  11. Spin-polarized states in neutron matter in a strong magnetic field

    International Nuclear Information System (INIS)

    Isayev, A. A.; Yang, J.

    2009-01-01

    Spin-polarized states in neutron matter in strong magnetic fields up to 10 18 G are considered in the model with the Skyrme effective interaction. By analyzing the self-consistent equations at zero temperature, it is shown that a thermodynamically stable branch of solutions for the spin-polarization parameter as a function of density corresponds to the negative spin polarization when the majority of neutron spins are oriented opposite to the direction of the magnetic field. Besides, beginning from some threshold density dependent on magnetic field strength, the self-consistent equations also have two other branches of solutions for the spin-polarization parameter with the positive spin polarization. The free energy corresponding to one of these branches turns out to be very close to that of the thermodynamically preferable branch. As a consequence, in a strong magnetic field, the state with the positive spin polarization can be realized as a metastable state in the high-density region in neutron matter, which, under decreasing density, at some threshold density changes to a thermodynamically stable state with the negative spin polarization.

  12. International key comparison of neutron fluence measurements in mono-energetic neutron fields: C.C.R.I.(3)-K10

    Energy Technology Data Exchange (ETDEWEB)

    Chen, J.; Wang, Z.; Rong, C. [China Institute of Atomic Energy (CIAE), Beijing, People' s Republic of China (China); Lovestam, G.; Plompen, A.; Puglisi, N. [EC-JRC-Institute for Reference Materials and Measurements (IRMM), Geel (Belgium); Gilliam, D.M.; Eisenhauer, C.M.; Nico, J.S.; Dewey, M.S. [National Institute of Standards and Technology (NIST), Gaithersburg (United States); Kudo, K.; Uritani, A.; Harano, H.; Takeda, N. [National Metrology Institute of Japan (NMIJ), Tsukuba (Japan); Thomas, D.J.; Roberts, N.J.; Bennett, A.; Kolkowski, P. [National Physical Laboratory (NPL), Teddington (United Kingdom); Moisseev, N.N.; Kharitonov, I.A. [Mendeleyev Institute for Metrology (VNIIM), St Petersburg (Russian Federation); Guldbakke, S.; Klein, H.; Nolte, R.; Schlegel, D. [Physikalisch-Technische Bundesanstalt (PTB), Braunschweig (Germany)

    2007-12-15

    C.C.R.I. Section III (neutron measurements) conducted a unique key comparison of neutron fluence measurements in mono-energetic neutron fields. In contrast to former comparisons, here the fluence measurements were performed with the participants' instruments in the same neutron fields at the P.T.B. accelerator facility. Seven laboratories- the C.I.A.E. (China), I.R.M.M. (E.C.), N.M.I.J. (Japan), N.I.S.T. (USA), N.P.L. (UK), P.T.B. (Germany) and the V.N.I.I.M. (Russia)-employed their primary standard reference methods or transfer instruments carefully calibrated against their primary standards, to determine the fluence of 0.144 MeV, 1.2 MeV, 5.0 MeV and 14.8 MeV neutrons and reported calibration coefficients for a selected neutron monitor and each neutron energy with a detailed uncertainty budget for the measurements. The key comparison reference values (K.C.R.V.) were finally evaluated as the weighted mean values of the neutron fluence at 1 m distance from the target in vacuum per neutron monitor count. The uncertainties of each K.C.R.V. amounted to about 1%. The degree of equivalence (D.o.E.), defined as the deviation of the result reported by the laboratories for each energy from the corresponding K.C.R.V., and the associated expanded uncertainty are also reported. The deviations between the results of two laboratories each with the corresponding expanded uncertainties complete the documentation of the degrees of equivalence. (authors)

  13. Neutron inelastic scattering experiments on the mixed-valent compound YbCuAl

    International Nuclear Information System (INIS)

    Mattens, W.C.M.; de Boer, F.R.; Murani, A.P.; Lander, G.H.

    1979-01-01

    The dynamical susceptibility of YbCuAl has been established by means of time of flight neutron scattering experiments. Non-Korringa behavior of the quasi-elastic line-width has been found and comparison with NMR data will be given

  14. Description of a neutron field perturbed by a probe using coupled Monte Carlo and discrete ordinates radiation transport calculations

    International Nuclear Information System (INIS)

    Zazula, J.M.

    1984-01-01

    This work concerns calculation of a neutron response, caused by a neutron field perturbed by materials surrounding the source or the detector. Solution of a problem is obtained using coupling of the Monte Carlo radiation transport computation for the perturbed region and the discrete ordinates transport computation for the unperturbed system. (author). 62 refs

  15. Studies in the Crystalline Electric Field in Pr2 Al and Pr Al by the Inelastic Neutron Scattering Method

    International Nuclear Information System (INIS)

    Slisenko, V.I.; Ivanitskij, P.G.; Vasil'kevich, A.A.; Krotenko, V.T.; Majstrenko, A.N.

    1993-01-01

    Results of inelastic neutron scattering in polycrystalline Pr 2 Al and Pr Al are reported. The parameters of the crystal field Hamiltonian for the orthorhombic point symmetry of the Pr 3+ ions in Pr 2 Al and Pr Al are derived from neutron spectra. Using These parameters the magnetic contribution to the specific heat is calculated

  16. Neutron-skin thickness of finite nuclei in relativistic mean-field models with chiral limits

    International Nuclear Information System (INIS)

    Jiang Weizhou; Li Baoan; Chen Liewen

    2007-01-01

    We study several structure properties of finite nuclei using relativistic mean-field Lagrangians constructed according to the Brown-Rho scaling due to the chiral symmetry restoration at high densities. The models are consistent with current experimental constraints for the equations of state of symmetric matter at both normal and supranormal densities and of asymmetric matter at subsaturation densities. It is shown that these models can successfully describe the binding energies and charge radii of finite nuclei. Compared to calculations with usual relativistic mean-field models, these models give a reduced thickness of neutron skin in 208 Pb between 0.17 fm and 0.21 fm. The reduction of the predicted neutron skin thickness is found to be due to not only the softening of the symmetry energy but also the scaling property of ρ meson required by the partial restoration of chiral symmetry

  17. Antikaon condensation in neutron stars by a new nonlinear mean-field model

    CERN Document Server

    Miyazaki, K

    2005-01-01

    We have investigated both the K^- and \\bar{K}^0 condensations in beta-equilibrated neutron star (NS) matter using the relativistic mean-field model with the renormalized meson-baryon coupling constants. Adopting the antikaon optical potential of -120MeV, our model predicts the K^- condensation as the second-order phase transition inside the neutron star of maximum mass, while the deeper potential than -160MeV is ruled out. This is in contrast to the result of the density-dependent hadron field theory. Our model also predicts remarkable softening of the equation of state by the \\bar{K}^0 condensation at high densities. Although this is contrasted with the result of the nonlinear Walecka model, only the K^- condensation can be formed in NSs.

  18. Magnetic Field Monitoring in the SNS and LANL Neutron EDM Experiments

    Science.gov (United States)

    Aleksandrova, Alina; SNS nEDM Collaboration; LANL nEDM Collaboration

    2017-09-01

    The SNS neutron EDM experiment requires the ability to precisely control and monitor the magnetic field inside of the fiducial volume. However, it is not always practical (or even possible) to measure the field within the region of interest directly. To remedy this issue, we have designed a field monitoring system that will allow us to reconstruct the field inside of the fiducial volume using noninvasive measurements of the field components at discrete locations external to this volume. A prototype probe array (consisting of 12 single-axis fluxgate magnetometer sensors) was used to monitor the magnetic field within the fiducial volume of an in-house magnetic testing apparatus. In this talk, the design and results of this test will be presented, and the possible implementation of this field monitoring method may have in the room temperature LANL neutron EDM experiment will be discussed. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under Award Number DE-SC-0014622.

  19. Test and evaluation of semiconductor components in mixed field radiation monitoring

    International Nuclear Information System (INIS)

    Cardenas, Jose Patricio N.; Madi Filho, Tufic; Rodrigues, Leticia L.C.

    2009-01-01

    Silicon components have found extensive use in nuclear spectroscopy and counting, as described in many articles in the last three decades. These devices have found utility in radiation dosimetry because a diode, for instance, produces a current approximately 18000 times higher than any ionization chamber of equal sensitive volume. This reduces stringent requirements from the electronics used to amplify or integrate the current and / or allows approaching the ideal detector point for the mapping of radiation fields. For better performance, in the case of diodes, they are normally used with high inverse polarity to obtain a deeper barrier, less noise and shorter transit time. The aim of this work was the evaluation of these semiconductor components for application in ionizing radiation fields monitoring, in nuclear research reactors and radiotherapy facilities, for radiation protection and health physics purposes. Experimental configurations to analyze the performance of commercial semiconductors, such as silicon PIN Photodiodes and Silicon Surface Barrier Detectors, were developed and the performance of three different configurations of charge preamplifier with silicon components was also studied. Components were evaluated for application as neutron detectors, using some types of radiators (converters). The radiation response of these silicon components to neutron fields from nuclear research reactors IEA-R1 and IPEN-MB1 (thermal, epithermal and fast neutrons), from beam holes, experimental halls and AmBe neutron sources in laboratory was investigated. (author)

  20. Neutron matter at next-to-next-to-next-to-leading order in chiral effective field theory.

    Science.gov (United States)

    Tews, I; Krüger, T; Hebeler, K; Schwenk, A

    2013-01-18

    Neutron matter presents a unique system for chiral effective field theory because all many-body forces among neutrons are predicted to next-to-next-to-next-to-leading order (N(3)LO). We present the first complete N(3)LO calculation of the neutron matter energy. This includes the subleading three-nucleon forces for the first time and all leading four-nucleon forces. We find relatively large contributions from N(3)LO three-nucleon forces. Our results provide constraints for neutron-rich matter in astrophysics with controlled theoretical uncertainties.

  1. Status report on dosimetry benchmark neutron field development, characterization, and application

    International Nuclear Information System (INIS)

    Fabry, A.; Grundl, J.A.; McElroy, W.N.; Lippincott, E.P.; Farrar, H. IV.

    1977-01-01

    The report attempts to present a brief, but comprehensive review of the status and future directions of benchmark neutron field development, characterization and application in perspective with two major objectives of reactor dosimetry: (1) fuel fission rate and burn-up passive monitoring, and (2) correlation of materials irradiation damage effects and projection to commercial power plants. The report focuses on the Light Water Reactor and Fast Breeder Reactor program needs

  2. Plunging neutron stars as origin of organised magnetic field in galactic nuclei

    Czech Academy of Sciences Publication Activity Database

    Karas, Vladimír; Kopáček, Ondřej; Kunneriath, D.; Zajaček, M.; Araudo, Anabella; Eckart, A.; Kovář, J.

    2017-01-01

    Roč. 47, č. 2 (2017), s. 124-132 ISSN 1335-1842 R&D Projects: GA ČR GA17-16287S; GA MŠk LD15061 Grant - others:COST(XE) MP1304 Institutional support: RVO:67985815 Keywords : magnetic fields * neutron stars * galactic centre Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics OBOR OECD: Astronomy (including astrophysics,space science) Impact factor: 0.336, year: 2016

  3. Cosmic Rays and Clouds, 1. Formation of Lead Mesoatoms In Neutron Monitor By Soft Negative Muons and Expected Atmospheric Electric Field Effect In The Cosmic Ray Neutron Component

    Science.gov (United States)

    Dorman, L. I.; Dorman, I. V.

    We extend our model (Dorman and Dorman, 1995) of cosmic ray atmospheric electric field effect on the case of neutron monitor. We take into account that about 0.07 of neu- tron monitor counting rate caused by negative soft muons captured by lead nucleons and formed mesoatoms with generation of several MeV energy neutrons from lead. In this case the neutron monitor or neutron supermonitor works as analyzer which de- tects muons of only one, negative sign. It is very important because the atmospheric electric field effect have opposite signs for positive and negative muons that main part of this effect in the muon telescope or in ionization chamber is compensated and we can observe only small part of total effect of one sign muons. On the basis of our gen- eral theory of cosmic ray meteorological effects with taking into account of negative soft muon acceleration and deceleration in the Earth atmosphere (in dependence of di- rection and intensity of electric field) we discuss the possibility of existing this effect in cosmic ray neutron component and made some rough estimations. REFERENCES: Dorman L.I. and Dorman I.V., 1995. "Cosmic-ray atmospheric electric field effects". Canadian J. of Physics, Vol. 73, pp. 440-443.

  4. On the mixed discretization of the time domain magnetic field integral equation

    KAUST Repository

    Ulku, Huseyin Arda; Bogaert, Ignace; Cools, Kristof; Andriulli, Francesco P.; Bagci, Hakan

    2012-01-01

    Time domain magnetic field integral equation (MFIE) is discretized using divergence-conforming Rao-Wilton-Glisson (RWG) and curl-conforming Buffa-Christiansen (BC) functions as spatial basis and testing functions, respectively. The resulting mixed

  5. Effects of neutrino emissivity on the cooling of neutron stars in the presence of a strong magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Coelho, Eduardo Lenho, E-mail: eduardo.coelho@uva.br [Universidade Veiga de Almeida, 108 Ibituruna St., 20271-020, Rio de Janeiro (Brazil); Chiapparini, Marcelo [Instituto de Física, Universidade do Estado do Rio de Janeiro, 524 São Francisco Xavier St., 20271-020, Rio de Janeiro (Brazil); Negreiros, Rodrigo Picanço [Instituto de Física, Universidade Federal Fluminense, Gal. Milton Tavares de Souza Ave., 24210-346, Rio de Janeiro (Brazil)

    2015-12-17

    One of the most interesting kind of neutron stars are the pulsars, which are highly magnetized neutron stars with fields up to 10{sup 14} G at the surface. The strength of magnetic field in the center of a neutron star remains unknown. According to the scalar virial theorem, magnetic field in the core could be as large as 10{sup 18} G. In this work we study the influence of strong magnetic fields on the cooling of neutron stars coming from direct Urca process. Direct Urca process is an extremely efficient mechanism for cooling a neutron star after its formation. The matter is described using a relativistic mean-field model at zero temperature with eight baryons (baryon octet), electrons and muons. We obtain the relative population of each species of particles as function of baryon density for different magnetic fields. We calculate numerically the cooling of neutron stars for a parametrized magnetic field and compare the results for the case without a magnetic field.

  6. About the possibility of using the field of the portable neutron generator for treatment of oncological diseases

    International Nuclear Information System (INIS)

    Stoyanov, A.Ph.; Dovbnya, A.N.; Tsymbal, V.A.

    2017-01-01

    The possibility of using a portable neutron generator (PNG) for the treatment of oncological diseases is being considered. It has been shown that when using PNG as a neutron source, it is possible to ensure sufficient therapeutic impact on sick cells, with minimal damage to healthy cells. It's about applying PNG in a brachytherapy tumor. It is important to note that the presence of a narrow ion- pipe- needle allows a neutron source to be placed close to the tumor, and thus to increase therapeutic influence. Numerical estimates of the density of neutrons and the consumed dose when using PNG for brachytherapy performed, it is shown that, for a short period of time (approx 1 minute), sufficient dose of radiation for therapy is absorbed. The calculations of the neutron field and absorbed dose are accomplished through a computer program developed by the authors based on the Monte Carlo method, designed to simulate the generation, movement, braking and absorption of neutrons.

  7. The cross-section data from neutron activation experiments on niobium in the NPI p-7Li quasi-monoenergetic neutron field

    Directory of Open Access Journals (Sweden)

    Simakov S.P.

    2010-10-01

    Full Text Available The reaction of protons on 7Li target produces the high-energy quasi- monoenergetic neutron spectrum with the tail to lower energies. Proton energies of 19.8, 25.1, 27.6, 30.1, 32.6, 35.0 and 37.4 MeV were used to obtain quasi-monoenergetic neutrons with energies of 18, 21.6, 24.8, 27.6, 30.3, 32.9 and 35.6 MeV, respectively. Nb cross-section data for neutron energies higher than 22.5 MeV do not exist in the literature. Nb is the important material for fusion applications (IFMIF as well. The variable-energy proton beam of NPI cyclotron is utilized for the production of neutron field using thin lithium target. The carbon backing serves as the beam stopper. The system permits to produce neutron flux density about 109  n/cm2/s in peak at 30 MeV neutron energy. The niobium foils of 15 mm in diameter and approx. 0.75 g weight were activated. The nuclear spectroscopy methods with HPGe detector technique were used to obtain the activities of produced isotopes. The large set of neutron energies used in the experiment allows us to make the complex study of the cross-section values. The reactions (n,2n, (n,3n, (n,4n, (n,He3, (n,α and (n,2nα are studied. The cross-sections data of the (n,4n and (n,2nα are obtained for the first time. The cross-sections of (n,2n and (n,α reactions for higher neutron energies are strongly influenced by low energy tail of neutron spectra. This effect is discussed. The results are compared with the EAF-2007 library.

  8. Measurements and Monte Carlo calculations with the extended-range Bonner sphere spectrometer at high-energy mixed fields

    OpenAIRE

    Dimovasili, Evangelia; Valley, Jean-Francois; Bay, Aurelio; Silari, Marco; Aroua, Abbas

    2016-01-01

    The use of spectrometry to provide information for neutron radiation protection has become an increasingly important activity over recent years. The need for spectral data arises because neither area survey instruments nor personal dosimeters give the correct dose equivalent results at all neutron energies. It is important therefore to know the spectra of the fields in which these devices are used. One of the systems most commonly employed in neutron spectrometry and dosimetry is the Bonner S...

  9. Molecular Dynamics and Neutron Scattering Studies of Mixed Solutions of Caffeine and Pyridine in Water.

    Science.gov (United States)

    Tavagnacco, Letizia; Mason, Philip E; Neilson, George W; Saboungi, Marie-Louise; Cesàro, Attilio; Brady, John W

    2018-05-31

    Insight into the molecular interactions of homotactic and heterotactic association of caffeine and pyridine in aqueous solution is given on the basis of both experimental and simulation studies. Caffeine is about 5 times more soluble in a 3 m aqueous pyridine solution than it is in pure water (an increase from ∼0.1 m to 0.5 m). At this elevated concentration the system becomes suitable for neutron scattering study. Caffeine-pyridine interactions were studied by neutron scattering and molecular dynamics simulations, allowing a detailed characterization of the spatial and orientational structure of the solution. It was found that while pyridine-caffeine interactions are not as strong as caffeine-caffeine interactions, the pyridine-caffeine interactions still significantly disrupted caffeine-caffeine stacking. The alteration of the caffeine-caffeine stacking, occasioned by the presence of pyridine molecules in solution and the consequent formation of heterotactic interactions, leads to the experimentally detected increase in caffeine solubility.

  10. Modelling Field Bus Communications in Mixed-Signal Embedded Systems

    Directory of Open Access Journals (Sweden)

    Alassir Mohamad

    2008-01-01

    Full Text Available Abstract We present a modelling platform using the SystemC-AMS language to simulate field bus communications for embedded systems. Our platform includes the model of an I/O controller IP (in this specific case an C controller that interfaces a master microprocessor with its peripherals on the field bus. Our platform shows the execution of the embedded software and its analog response on the lines of the bus. Moreover, it also takes into account the influence of the circuits's I/O by including their IBIS models in the SystemC-AMS description, as well as the bus lines imperfections. Finally, we present simulation results to validate our platform and measure the overhead introduced by SystemC-AMS over a pure digital SystemC simulation.

  11. Modelling Field Bus Communications in Mixed-Signal Embedded Systems

    Directory of Open Access Journals (Sweden)

    Patrick Garda

    2008-08-01

    Full Text Available We present a modelling platform using the SystemC-AMS language to simulate field bus communications for embedded systems. Our platform includes the model of an I/O controller IP (in this specific case an I2C controller that interfaces a master microprocessor with its peripherals on the field bus. Our platform shows the execution of the embedded software and its analog response on the lines of the bus. Moreover, it also takes into account the influence of the circuits's I/O by including their IBIS models in the SystemC-AMS description, as well as the bus lines imperfections. Finally, we present simulation results to validate our platform and measure the overhead introduced by SystemC-AMS over a pure digital SystemC simulation.

  12. Crystal structure and dynamics of K2-x(NH4)xSeO4 mixed crystals studied by x-ray and neutron scattering

    International Nuclear Information System (INIS)

    Smirnov, L.S.; Natkaniec, I.; Loose, A.

    2006-01-01

    The K 2-x (NH 4 ) x SeO 4 mixed crystals have been studied by powder X-ray and neutron diffraction and inelastic incoherent neutron scattering in a wide temperature range from 300 to 16 K. No phase transition is observed in (NH 4 ) 2 SeO 4 in the range from room temperature to 20 K. The reorientation potential barriers of ammonium ions in the K 2-x (NH 4 ) x SeO 4 mixed crystals increase with the increasing concentration of ammonium ions

  13. Correlation of the neutron yield from the plasma focus upon variations in the magnetic field energy of the discharge circuit

    Science.gov (United States)

    Ablesimov, V. E.; Dolin, Yu. N.; Kalinychev, A. E.; Tsibikov, Z. S.

    2017-10-01

    The relation between neutron yield Y and magnetic field energy variations Δ W in the discharge circuit has been studied for a Mather-type plasma-focus camera. The activation technique (activation of silver isotopes) has been used to measure the integral yield of DD neutrons from the source. The time dependence of the neutron yield has been recorded by scintillation detectors. For the device used in the investigations, the neutron yield exhibits a linear dependence on variations in the magnetic field energy Δ W in the discharge circuit at the instant of neutron generation. It is also found that this dependence is related to the initial deuteron pressure in the discharge chamber.

  14. Determination of technetium-99 in mixed fission products by neutron activation analysis

    International Nuclear Information System (INIS)

    Bate, L.C.

    1980-01-01

    A method has been developed for analysis of 99 Tc in fission product mixtures. The analysis consists of a chemical separation of 99 Tc, neutron irradiation of the isolated 99 Tc, and gamma-ray spectrometric determination of the induced 100 Tc radioactivity. Technetium-99 is chemically separated from most fission products by a cyclohexanone extraction from basic carbonate solution. Technetium-99 is stripped into water by addition of carbon tetrachloride to the cyclohexanone phase. A final step in the separation procedure is adsorption of 99 Tc on an anion exchange column which provides additional decontamination and places the 99 Tc in a concentrated form for neutron activation analysis. Neutron irradiations of the isolated 99 Tc were made in the pneumatic tube facility at the High Flux Isotope Reactor at a flux of 5 x 10 14 n/cm 2 /sec for 11 seconds. Induced 100 Tc radioactivity was determined immediately after irradiation using gamma-ray spectrometry to measure the 540 and 591 keV lines. Sensitivity of the analysis under these conditions is approximately 5 ng, and samples of up to about 100 ml volume can be easily processed. The method has been successfully applied to reactor fuel solutions and off-gas traps containing 6.5 x 10 -4 to 240 μg 99 Tc/ml

  15. Deformation and mixing of co-existing shapes in the neutron-deficient polonium isotopes

    CERN Document Server

    AUTHOR|(CDS)2078559; Huyse, Mark

    The neutron-deficient polonium isotopes, with only 2 protons outside the Z = 82 shell closure, are situated in an interesting region of the nuclear chart. In the neighboring lead (Z = 82) and mercury (Z = 80) isotopes, experimental and theoretical efforts identified evidence of shape coexistence. Shape coexistence is the remarkable phenomenon in which two or more distinct types of deformation occur in states of the same angular momentum and similar excitation energy in a nucleus. The neutron-deficient polonium isotopes have also been studied intensively, experimentally as well as theoretically. The closed neutron-shell nucleus 210Po (N = 126) manifests itself as a two-particle nucleus where most of the excited states can be explained by considering the degrees of freedom of the two valence protons outside of 208Pb. The near-constant behavior of the yrast 2+1 and 4+1 states in the isotopes with mass 200 ≤ A ≤ 208 can be explained by coupling the two valence protons to a vibrating lead core. 200Po seems to ...

  16. Constraints on Non-Newtonian Gravity From the Experiment on Neutron Quantum States in the Earth's Gravitational Field.

    Science.gov (United States)

    Nesvizhevsky, V V; Protasov, K V

    2005-01-01

    An upper limit to non-Newtonian attractive forces is obtained from the measurement of quantum states of neutrons in the Earth's gravitational field. This limit improves the existing constraints in the nanometer range.

  17. Characterization of Black Carbon Mixing State Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Sedlacek, A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Davidovits, P. [Boston College, Chestnut Hill, MA (United States); Lewis, E. R. [Brookhaven National Lab. (BNL), Upton, NY (United States); Onasch, T. B. [Aerodyne Research, Billerica, MA (United States)

    2016-04-01

    Interpreting the temporal relationship between the scattering and incandescence signals recorded by the Single Particle Soot Photometer (SP2), Sedlacek et al. (2012) reported that 60% of the refractory black carbon containing particles in a plume containing biomass burning tracers exhibited non-core-shell structure. Because the relationship between the rBC (refractory black carbon) incandescence and the scattering signals had not been reported in the peer-reviewed literature, and to further evaluate the initial interpretation by Sedlacek et al., a series of experiments was undertaken to investigate black carbon-containing particles of known morphology using Regal black (RB), a proxy for collapsed soot, as the light-absorbing substance to characterize this signal relationship. Particles were formed by coagulation of RB with either a solid substance (sodium chloride or ammonium sulfate) or a liquid substance (dioctyl sebacate), and by condensation with dioctyl sebacate, the latter experiment forming particles in a core-shell configuration. Each particle type experienced fragmentation (observed as negative lagtimes), and each yielded similar lagtime responses in some instances, confounding attempts to differentiate particle morphology using current SP2 lagtime analysis. SP2 operating conditions, specifically laser power and sample flow rate, which in turn affect the particle heating and dissipation rates, play an important role in the behavior of particles in the SP2, including probability of fragmentation. This behavior also depended on the morphology of the particles and on the thermochemical properties of the non-RB substance. Although these influences cannot currently be unambiguously separated, the SP2 analysis may still provide useful information on particle mixing states and black carbon particle sources. This work was communicated in a 2015 publication (Sedlacek et al. 2015)

  18. Evaluation of two personal dosemeters in polyenergetic mono- and multi-directional neutron fields

    International Nuclear Information System (INIS)

    Nunes, J. C.; Surette, R. A.

    2005-01-01

    The neutron dose-equivalent response of two commercially available electronic personal neutron dosemeters was studied in several laboratory-produced broad-spectrum neutron fields. Fluence-weighted mean energies ranged from 200 keV to 4 MeV; personal dose-equivalent rates ranged from 75 to 10 mSv h -1 ; and angles of incidence were multidirectional, 0 deg., 30 deg. and 60 deg.. Three of these fields have been shown previously to resemble ones found in CANDU (Canadian Deuterium Uranium is a registered trademark of the Atomic Energy of Canada Limited) power plant workplaces. Both dosemeters were found to perform reasonably well across the range of energy spectra and angles of incidence. One type of dosemeter displayed values of the personal dose equivalent that were, at worst, within a factor of ∼2 of the reference values and, at best, within a few per cent of the reference values. The other type displayed values of the personal dose equivalent that were consistently within unity and 20% of the reference values. Although the radiological performance of one was found to be more accurate, this device was also found to be the less rugged of the two. Some of the data acquired in this work were compared with results previously published by others. There was consistency between these sets of data. (authors)

  19. Finite temperature effects on anisotropic pressure and equation of state of dense neutron matter in an ultrastrong magnetic field

    International Nuclear Information System (INIS)

    Isayev, A. A.; Yang, J.

    2011-01-01

    Spin-polarized states in dense neutron matter with the recently developed Skyrme effective interaction (BSk20 parametrization) are considered in the magnetic fields H up to 10 20 G at finite temperature. In a strong magnetic field, the total pressure in neutron matter is anisotropic, and the difference between the pressures parallel and perpendicular to the field direction becomes significant at H>H th ∼10 18 G. The longitudinal pressure decreases with the magnetic field and vanishes in the critical field 10 18 c 19 G, resulting in the longitudinal instability of neutron matter. With increasing temperature, the threshold H th and critical H c magnetic fields also increase. The appearance of the longitudinal instability prevents the formation of a fully spin-polarized state in neutron matter and only the states with moderate spin polarization are accessible. The anisotropic equation of state is determined at densities and temperatures relevant to the interiors of magnetars. The entropy of strongly magnetized neutron matter turns out to be larger than the entropy of nonpolarized matter. This is caused by some specific details in the dependence of the entropy on the effective masses of neutrons with spin up and spin down in a polarized state.

  20. Experimental study of the field-of-view of neutron detectors towards thermohydraulic perturbances

    International Nuclear Information System (INIS)

    Kozma, R.

    1988-05-01

    The aim of the present study was to identify different stages of boiling during the HOR experiments at the 2 MW reactor of IRI (Interfaculty Reactor Inst.), Delft, Netherlands. The electrical heating power was increased while the flow rate was constant, thus inducing a single-phase flow, and afterwards subcooled boiling and finally developed volume boiling of the coolant in the experimental assembly. Subcooled boiling and the onset of boiling could not be detected using neutron detectors. This behaviour shows that the field of view of the NDs is very limited. The neutron noise signals remained unchanged, though at a distance of 3-10 cm developed volume boiling arose. Only the steam-packets in the slug-type flow during measurement III caused changes in the neutro noise. (author) 12 refs.; 20 figs

  1. Disordered nuclear pasta, magnetic field decay, and crust cooling in neutron stars

    Science.gov (United States)

    Horowitz, C. J.; Berry, D. K.; Briggs, C. M.; Caplan, M. E.; Cumming, A.; Schneider, A. S.

    2015-04-01

    Nuclear pasta, with non-spherical shapes, is expected near the base of the crust in neutron stars. Large scale molecular dynamics simulations of pasta show long lived topological defects that could increase electron scattering and reduce both the thermal and electrical conductivities. We model a possible low conductivity pasta layer by increasing an impurity parameter Qimp. Predictions of light curves for the low mass X-ray binary MXB 1659-29, assuming a large Qimp, find continued late time cooling that is consistent with Chandra observations. The electrical and thermal conductivities are likely related. Therefore observations of late time crust cooling can provide insight on the electrical conductivity and the possible decay of neutron star magnetic fields (assuming these are supported by currents in the crust). This research was supported in part by DOE Grants DE-FG02-87ER40365 (Indiana University) and DE-SC0008808 (NUCLEI SciDAC Collaboration).

  2. A new Recoil Proton Telescope for energy and fluence measurement of fast neutron fields

    Energy Technology Data Exchange (ETDEWEB)

    Lebreton, Lena; Bachaalany, Mario [IRSN / LMDN (Institut de Radioprotection et de Surete nucleaire / Laboratoire de Metrologie et de dosimetrie des neutrons), Cadarache Bat.159, 13115 Saint Paul-lez-Durance, (France); Husson, Daniel; Higueret, Stephane [IPHC / RaMsEs (Institut Pluridisciplinaire Hubert Curien / Radioprotection et Mesures Environnementales), 23 rue du loess - BP28, 67037 Strasbourg cedex 2, (France)

    2015-07-01

    The spectrometer ATHENA (Accurate Telescope for High Energy Neutron metrology Applications), is being developed at the IRSN / LMDN (Institut de Radioprotection et de Surete nucleaire / Laboratoire de Metrologie et de dosimetrie des neutrons) and aims at characterizing energy and fluence of fast neutron fields. The detector is a Recoil Proton Telescope and measures neutron fields in the range of 5 to 20 MeV. This telescope is intended to become a primary standard for both energy and fluence measurements. The neutron detection is achieved by a polyethylene radiator for n-p conversion, three 50{sub m} thick silicon sensors that use CMOS technology for the proton tracking and a 3 mm thick silicon diode to measure the residual proton energy. This first prototype used CMOS sensors called MIMOSTAR, initially developed for heavy ion physics. The use of CMOS sensors and silicon diode increases the intrinsic efficiency of the detector by a factor of ten compared with conventional designs. The first prototype has already been done and was a successful study giving the results it offered in terms of energy and fluence measurements. For mono energetic beams going from 5 to 19 MeV, the telescope offered an energy resolution between 5 and 11% and fluence difference going from 5 to 7% compared to other home standards. A second and final prototype of the detector is being designed. It will hold upgraded CMOS sensors called FastPixN. These CMOS sensors are supposed to run 400 times faster than the older version and therefore give the telescope the ability to support neutron flux in the order of 107 to 108cm{sup 2}:s{sup 1}. The first prototypes results showed that a 50 m pixel size is enough for a precise scattering angle reconstruction. Simulations using MCNPX and GEANT4 are already in place for further improvements. A DeltaE diode will replace the third CMOS sensor and will be installed right before the silicon diode for a better recoil proton selection. The final prototype with

  3. Applications of a lead pile coupled with fast reactor core of Yayoi as an intermediate energy neutron standard field

    International Nuclear Information System (INIS)

    Kosako, Toshiso; Nakazawa, Masaharu; Sekiguchi, Akira; Wakabayashi, Hiroaki.

    1976-10-01

    Intermediate neutron column of YAYOI reactor is here evaluated as an intermediate energy neutron standard field which provides a base of the measurements of various reaction rates in that energy region, including detector calibration and Doppler coefficient determination. The experiments were performed using YAYOI's core as a fast neutron source by coupling with the large lead pile, which is a 160 ton's octagon of 2.5 m high and with a thickness of about 2.5 m face to face distance. Spatial variation of the neutron flux in the lead pile was estimated by gold activation foils, and the neutron spectrum by sandwich foils, a helium-3 proportional counter and a proton recoil counter. The calculated results were obtained using one and two- dimensional discrete ordinate code, ANISN and TWOTRAN II. Through comparison of experiment with calculation, it became clear that the neutron field at the central block has simple energy spectrum and stable spatial distribution of the neutron flux, the absolute of which was 5.0 x 10 4 (n/cm 2 /sec/Watt) at the representative energy of 1 KeV. The energy spectrum of the position and the spatial dependent neutron flux in the lead pile are both represented by the semiempirical formula, which must be useful both for evaluation of experimental data and for future applications. (auth.)

  4. Exclusive vector meson production with leading neutrons in a saturation model for the dipole amplitude in mixed space

    Science.gov (United States)

    Amaral, J. T.; Becker, V. M.

    2018-05-01

    We investigate ρ vector meson production in e p collisions at HERA with leading neutrons in the dipole formalism. The interaction of the dipole and the pion is described in a mixed-space approach, in which the dipole-pion scattering amplitude is given by the Marquet-Peschanski-Soyez saturation model, which is based on the traveling wave solutions of the nonlinear Balitsky-Kovchegov equation. We estimate the magnitude of the absorption effects and compare our results with a previous analysis of the same process in full coordinate space. In contrast with this approach, the present study leads to absorption K factors in the range of those predicted by previous theoretical studies on semi-inclusive processes.

  5. Interfacial mixing in as-deposited Si/Ni/Si layers analyzed by x-ray and polarized neutron reflectometry

    Science.gov (United States)

    Bhattacharya, Debarati; Basu, Saibal; Singh, Surendra; Roy, Sumalay; Dev, Bhupendra Nath

    2012-12-01

    Interdiffusion occurring across the interfaces in a Si/Ni/Si layered system during deposition at room temperature was probed using x-ray reflectivity (XRR) and polarized neutron reflectivity (PNR). Exploiting the complementarity of these techniques, both structural and magnetic characterization with nanometer depth resolution could be achieved. Suitable model fitting of the reflectivity profiles identified the formation of Ni-Si mixed alloy layers at the Si/Ni and Ni/Si interfaces. The physical parameters of the layered structure, including quantitative assessment of the stoichiometry of interfacial alloys, were obtained from the analyses of XRR and PNR patterns. In addition, PNR provided magnetic moment density profile as a function of depth in the stratified medium.

  6. Determination of rare earth elements, hafnium and cadmium in sintered pellets of mixed thorium and uranium oxides by neutron activation

    International Nuclear Information System (INIS)

    Cardoso, S.N.M.

    1987-01-01

    This work shows the development of a method for determination of the rare-earth elements (Eu, Sm, Dy and Gd), Hf and Cd contents in sinterized U and Th mixed oxides by neutron activation analysis. The sample is dissolved in nitric/fluoridric (0,1% HF) medium, to dryness and redissolved in 6N HCl solution. The Hf is extracted into organic phase (0,5 M TTA/benzene), irradiated and analysed through 181 Hf isotope energy peak. The aqueous phase is treated with NH 4 OH for the precipitation of hidroxides. Then, these are dissolved in 6N HNO 3 solution. The extraction of U and Th is made in two steps, one with TBP/CCl 4 and another with 0,5 M TTA/C 6 H 6 . Then the rare-earth elements and Cd are irradiated and determined by gamma spectrometry. (author) [pt

  7. Interfacial mixing in as-deposited Si/Ni/Si layers analyzed by x-ray and polarized neutron reflectometry

    International Nuclear Information System (INIS)

    Bhattacharya, Debarati; Basu, Saibal; Singh, Surendra; Roy, Sumalay; Dev, Bhupendra Nath

    2012-01-01

    Highlights: ► Room temperature diffusion in Si/Ni/Si trilayer detected through complementary x-ray and polarized neutron reflectometry. ► Analyses of XPNR data generated the construction of the layered structure in terms of physical parameters along with alloy layers created by diffusion. ► Scattering length density information from XPNR provided quantitative assessment of the stoichiometry of alloys formed at the Si/Ni and Ni/Si interfaces. - Abstract: Interdiffusion occurring across the interfaces in a Si/Ni/Si layered system during deposition at room temperature was probed using x-ray reflectivity (XRR) and polarized neutron reflectivity (PNR). Exploiting the complementarity of these techniques, both structural and magnetic characterization with nanometer depth resolution could be achieved. Suitable model fitting of the reflectivity profiles identified the formation of Ni–Si mixed alloy layers at the Si/Ni and Ni/Si interfaces. The physical parameters of the layered structure, including quantitative assessment of the stoichiometry of interfacial alloys, were obtained from the analyses of XRR and PNR patterns. In addition, PNR provided magnetic moment density profile as a function of depth in the stratified medium.

  8. Interfacial mixing in as-deposited Si/Ni/Si layers analyzed by x-ray and polarized neutron reflectometry

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharya, Debarati, E-mail: debarati@barc.gov.in [Solid State Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Basu, Saibal; Singh, Surendra [Solid State Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Roy, Sumalay; Dev, Bhupendra Nath [Department of Materials Science, Indian Association for the Cultivation of Science, 2A and 2B Raja S.C. Mullick Road, Jadavpur, Kolkata 700032 (India)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer Room temperature diffusion in Si/Ni/Si trilayer detected through complementary x-ray and polarized neutron reflectometry. Black-Right-Pointing-Pointer Analyses of XPNR data generated the construction of the layered structure in terms of physical parameters along with alloy layers created by diffusion. Black-Right-Pointing-Pointer Scattering length density information from XPNR provided quantitative assessment of the stoichiometry of alloys formed at the Si/Ni and Ni/Si interfaces. - Abstract: Interdiffusion occurring across the interfaces in a Si/Ni/Si layered system during deposition at room temperature was probed using x-ray reflectivity (XRR) and polarized neutron reflectivity (PNR). Exploiting the complementarity of these techniques, both structural and magnetic characterization with nanometer depth resolution could be achieved. Suitable model fitting of the reflectivity profiles identified the formation of Ni-Si mixed alloy layers at the Si/Ni and Ni/Si interfaces. The physical parameters of the layered structure, including quantitative assessment of the stoichiometry of interfacial alloys, were obtained from the analyses of XRR and PNR patterns. In addition, PNR provided magnetic moment density profile as a function of depth in the stratified medium.

  9. Parotid gland pathophysiology after mixed gamma and neutron irradiation of cancer patients

    International Nuclear Information System (INIS)

    Anderson, M.W.; Izutsu, K.T.; Rice, J.C.

    1981-01-01

    Electrolyte and protein concentrations were measured in parotid saliva samples obtained from patients receiving localized, fractionated, neutron and gamma irradiation for the treatment of cancer. Salivary sodium chloride concentration increased transiently but then usually decreased to preirradiation values after 2 weeks of therapy. There were concurrent decreases in salivary flow rate, pH, and bicarbonate concentration. The decreases in sodium chloride concentration and flow rate are inconsistent with a previously suggested, irradiation-induced ductal sodium resorption defect. The findings contribute toward understanding how salivary gland physiology is altered in irradiation injury

  10. Dosimetry of mixed gamma - neutron fluxes in the active zone of working reactor and gamma-flux after quenching

    International Nuclear Information System (INIS)

    Mussaeva, M.A.; Zinov'ev, V.; Ibragimova, E.M.; Muminov, M.I.

    2006-01-01

    Full text: For carrying out experiments in the channels of nuclear reactor, it is necessary to know the distribution of neutron flux and the intensity of accompanying gamma-radiation both in the working and quenched regimes. Dosimetric parameter of transparent dielectrics is based on the effect of monotonous changing of optical absorption or luminescence under neutrons and/or gamma-radiation. While the radioactivity induced in an element monitor is proportional only to a neutron fluence beginning from a threshold energy. Therefore the aim of this work was to determine the values of neutron and gamma-component fluxes separately and evaluate the contribution of each into the defect production in dielectrics. We used very pure quartz glass of KU-1 type, produced in Russian State Optical Institute by fusion from SiCl 4 in the mixed flow of O 2 +H 2 (impurities of Cl and OH up to 10 -2 % and the rest - below 10 -4 %), SiO 2 glasses with 30 % Ba, and also pure Ni wire. Since under irradiation in the working reactor samples were undergone mixed neutron and gamma fluxes, we suggested determination of intensity of gamma-radiation from radio-nuclides (products of uranium fission) after quenching the reactor by the current of ionization chamber and glass dosimeters. Samples of SiO 2 -BaO together with Ni monitors were irradiated for 1 hour in 18 channels of the active zone of the working reactor both in the sealed ampoules and in the contact with water of the 1-st cooling circuit at 40 deg C. The linear dependence of the induced optical density on the absorbed dose of n 0 + γ-radiation was obtained. Ni -monitors not sensitive to γ-radiation gained the induced radioactivity proportional to the absorbed energy of neutron flux above 1 MeV. Neutron fluxes in the 18 channels varied from 9.53·10 11 to 1.21·10 13 cm -2 s -1 corresponding to fluences from 3.43·10 15 to 4.3·10 16 cm -2 . Optical density of band 215 nm ascertained to E ' - center, which is ≡ Si * near oxygen

  11. Measurements of Electric Field in a Nanosecond Pulse Discharge by 4-WAVE Mixing

    Science.gov (United States)

    Baratte, Edmond; Adamovich, Igor V.; Simeni Simeni, Marien; Frederickson, Kraig

    2017-06-01

    Picosecond four-wave mixing is used to measure temporally and Picosecond four-wave mixing is used to measure temporally and spatially resolved electric field in a nanosecond pulse dielectric discharge sustained in room air and in an atmospheric pressure hydrogen diffusion flame. Measurements of the electric field, and more precisely the reduced electric field (E/N) in the plasma is critical for determination rate coefficients of electron impact processes in the plasma, as well as for quantifying energy partition in the electric discharge among different molecular energy modes. The four-wave mixing measurements are performed using a collinear phase matching geometry, with nitrogen used as the probe species, at temporal resolution of about 2 ns . Absolute calibration is performed by measurement of a known electrostatic electric field. In the present experiments, the discharge is sustained between two stainless steel plate electrodes, each placed in a quartz sleeve, which greatly improves plasma uniformity. Our previous measurements of electric field in a nanosecond pulse dielectric barrier discharge by picosecond 4-wave mixing have been done in air at room temperature, in a discharge sustained between a razor edge high-voltage electrode and a plane grounded electrode (a quartz plate or a layer of distilled water). Electric field measurements in a flame, which is a high-temperature environment, are more challenging because the four-wave mixing signal is proportional to the to square root of the difference betwen the populations of N2 ground vibrational level (v=0) and first excited vibrational level (v=1). At high temperatures, the total number density is reduced, thus reducing absolute vibrational level populations of N2. Also, the signal is reduced further due to a wider distribution of N2 molecules over multiple rotational levels at higher temperatures, while the present four-wave mixing diagnostics is using spectrally narrow output of a ps laser and a high

  12. The recovery of bone marrow derived GM-CFU in baboons unilaterally exposed to a total body LD50/30d mixed neutron-gamma irradiation

    International Nuclear Information System (INIS)

    Herodin, F.; Orfeuvre, H.; Janodet, D.; Mestries, J.C.; Fatome, M.

    1990-01-01

    The unilateral exposure of baboons to a total body LD 50/30d mixed neutron/gamma irradiation was characterized to be non uniform in dose distribution. The pattern of recovery of granulocyte-macrophage progenitors in bone marrow samples collected from entrance and exit sides respectively is consistent with this observed heterogeneity [fr

  13. A multidimensional multigroup diffusion model for the determination of the frequency-dependent field of view of a neutron detector

    International Nuclear Information System (INIS)

    van der Hagen, T.H.J.J.; Hoogenboom, J.E.; van Dam, H.

    1992-01-01

    This paper reports on the sensitivity of a neutron detector to parametric fluctuations in the core of a reactor which depends on the position and the frequency of the perturbation. The basic neutron diffusion model for the calculation of this so-called field of view (FOV) of the detector is extended with respect to the dimensionality of the problem and the number of energy groups involved. The physical meaning of the FOV concept is illustrated by means of some simple examples, which can be handled analytically. The possibility of calculating the FOV by a conventional neutron diffusion code is demonstrated. In that case, the calculation in n neutron energy groups leads to 2n modified neutron diffusion equations

  14. Construction of monoenergetic neutron calibration fields using 45Sc(p, n)45Ti reaction at JAEA.

    Science.gov (United States)

    Tanimura, Y; Saegusa, J; Shikaze, Y; Tsutsumi, M; Shimizu, S; Yoshizawa, M

    2007-01-01

    The 8 and 27 keV monoenergetic neutron calibration fields have been developed by using (45)Sc(p, n)(45)Ti reaction. Protons from a 4-MV Pelletron accelerator are used to bombard a thin scandium target evaporated onto a platinum disc. The proton energies are finely adjusted to the resonance to generate the 8 and 27 keV neutrons by applying a high voltage to the target assemblies. The neutron energies were measured using the time-of-flight method with a lithium glass scintillation detector. The neutron fluences at a calibration point located at 50 cm from the target were evaluated using Bonner spheres. A long counter was placed at 2.2 m from the target and at 60 degrees to the direction of the proton beam in order to monitor the fluence at the calibration point. Fluence and dose equivalent rates at the calibration point are sufficient to calibrate many types of the neutron survey metres.

  15. Pilot study for the implantation of a high-energy neutrons field

    International Nuclear Information System (INIS)

    Pinto, Jose Julio de O.; Mendes, Adriane C.; Federico, Claudio A.; Passaro, Angelo; Gaspar, Felipe de B.; Pazianotto, Mauricio T.

    2013-01-01

    In this work a theoretical study is presented for the implementation of a high-energy neutron field (14.1 MeV) produced by a neutron generator type DT (deuterium-tritium), to be installed in the premises of the Laboratorio de Radiacoes Ionizantes (LRI) of the Instituto de Estudos Avancados (IEAv). This evaluation was performed by means of computer simulation by Monte Carlo method, using the computer code MCNP5 (Monte Carlo N-Particle). The neutron spectra were simulated computationally for pre-selected points of the installation, allowing to estimate the beam quality in the positions provided for use of the direct beam. These simulations also allow assist the basement of a project to install the consistent D-T generator with the guidelines for radiation protection and radiation safety standards determined by the Comissao Nacional de Energia Nuclear (CNEN), by estimating the dose rates provided in accessible points to Individuals Occupationally Exposed (IOE) in the facility. The computational determination of spectra, fluxes and doses produced in different positions previously selected within and outside the laboratory, will serve as guidance from previous studies for the future installation of this generator in the physical facilities of the LRI

  16. Bubble detector's evaluation for neutron field measurement in a very known source

    Energy Technology Data Exchange (ETDEWEB)

    Ramalho, Eduardo; Silva, Ademir X. da, E-mail: ademir@nuclear.ufrj.b, E-mail: jdantas@con.ufrj.b [Coordenacao dos Programas de Pos-Graduacao de Engenharia (PEN/COPPE/UFRJ), RJ (Brazil). Programa de Engenharia Nuclear; Reina, Luiz, E-mail: reina@ien.gov.b [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Facure, Alessandro, E-mail: facure@cnen.gov.b [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil)

    2011-07-01

    Measurements on neutron fields, mainly for dosimetric purposes, have been a major concern for ionizing radiation workers, because of the radiation protection issues. The present work aims to study the using of bubble detectors in neutron dosimetry and the Bubble Detector Spectrometer (BDS) was chosen for this task. Several experiments were performed in order to obtain spectra from such devices and their respective analysis and then they were compared to those which were obtained by other ways. An Am-Be calibration neutron source from Instituto de Radioprotecao e Dosimetria/Comissao Nacional de Energia Nuclear (IRD/CNEN) was used and its spectrum was compared to the one obtained by BDS. The possibility of the use of such devices as ambient dosimeters was also evaluated. Despite the uncertainties, especially in the lowest energy thresholds, the spectrum from BDS is in good agreement with the known ones and the use of BDS as a dosimeter demands a more detailed study due to some characteristics of the Am-Be source that produce high uncertainties in low energy thresholds. (author)

  17. Equation of state of neutron-rich nuclear matter from chiral effective field theory

    Energy Technology Data Exchange (ETDEWEB)

    Kaiser, Norbert; Strohmeier, Susanne [Technische Universitaet Muenchen (Germany)

    2016-07-01

    Based on chiral effective field theory, the equation of state of neutron-rich nuclear matter is investigated systematically. The contributing diagrams include one- and two-pion exchange together with three-body terms arising from virtual Δ(1232)-isobar excitations. The proper expansion of the energy per particle, anti E(k{sub f},δ) = anti E{sub n}(k{sub f}) + δB{sub 1}(k{sub f}) + δ{sup 5/3}B{sub 5/3}(k{sub f}) + δ{sup 2}B{sub 2}(k{sub f}) +.., for the system with neutron density ρ{sub n} = k{sub f}{sup 3}(1-δ)/3π{sup 2} and proton density ρ{sub p} = k{sub f}{sup 3}δ/3π{sup 2} is performed analytically for the various interaction contributions. One observes essential structural differences to the commonly used quadratic approximation. The density dependent coefficient B{sub 1}(k{sub f}) turns out to be unrelated to the isospin-asymmetry of nuclear matter. The coefficient B{sub 5/3}(k{sub f}) of the non-analytical δ{sup 5/3}-term receives contributions from the proton kinetic energy and from the one- and two-pion exchange interactions. The physical consequences for neutron star matter are studied.

  18. Neutron spectrometry using LNL bonner spheres and FLUKA

    Energy Technology Data Exchange (ETDEWEB)

    Sarchiapone, L.; Zafiropoulos, D. [INFN, Laboratori Nazionali di Legnaro (Italy)

    2013-07-18

    The characterization of neutron fields has been made with a system based on a scintillation detector and multiple moderating spheres. The system, together with the unfolding procedure, have been tested in quasi-monochromatic neutron energy fields and in complex, mixed, cyclotron based environments. FLUKA simulations have been used to produce response functions and reference energy spectra.

  19. Characterization of the neutron field at the ISIS-VESUVIO facility by means of a bonner sphere spectrometer

    Science.gov (United States)

    Bedogni, Roberto; Esposito, Adolfo; Andreani, Carla; Senesi, Roberto; De Pascale, Maria Pia; Picozza, Piergiorgio; Pietropaolo, Antonino; Gorini, Giuseppe; Frost, Christopher D.; Ansell, Stewart

    2009-12-01

    One of the more actual and promising fields of applied neutron physics is the investigation of the malfunctions induced by high-energy neutrons naturally present in the atmosphere in electronic devices, called single event effects (SEE). These studies are of primary importance for the design of devices that have to fulfill high reliability requirements and those that are likely to be exposed to enhanced levels of cosmic rays background, e.g. in aerospace and avionic applications. Particle accelerators-driven neutron sources constitute valuable irradiation facilities for these purposes as they provide an opportunity for accelerated testing of the effects of these naturally occurring neutrons, provided the neutron spectrum is comparable with the atmospheric one and the neutron fields are known with high accuracy. The latter can be achieved through the use of appropriate radiation transport codes and neutron spectrometry techniques. In view of the design and construction of CHIPIR, a dedicated beam line for SEE studies at the ISIS pulsed neutron source second target station (UK) [1] ( http://ts-2.isis.rl.ac.uk/instruments/phase2/index.htm), a spectrometric characterization was performed on the VESUVIO beamline [2] (Senesi et al.,2000). The spectrometric technique was the bonner sphere spectrometer (BSS), widely used to determine neutron spectra and dose quantities around high-energy accelerators. The experimental campaign provided a complete spectrometric investigation of the VESUVIO neutron beam, allowing the integral quantities (total fluence rate, fraction of fluence in given energy intervals) to be estimated with uncertainties lower than 10%.

  20. Neutron field characterization and dosimetry at the TRIUMF proton therapy facility

    International Nuclear Information System (INIS)

    Mukherjee, B.

    2002-01-01

    Full text: In 1972 the 500 MeV H' Cyclotron of the TRIUMF (Tri University Meson Factory) located in Vancouver, Canada became operational. Beside Meson Physics, high-energy protons of various energy and beam current levels from the TRIUMF Cyclotron are used for scientific research and biomedical applications. Recently, a 500 MeV proton beam from the cyclotron was used as the booster beam for the radioactive ion beam facility, ISAC (Isotope Separator Accelerator) and a second beam as primary irradiation source for the Proton Irradiation Facility (PIF). The major commercial applications of the PIF are the provision of high-energy proton beams for radiation hardness testing of electronic components used in space applications (NASA) and proton therapy of ocular tumors (British Columbia Proton Therapy Facility). The PIF vault was constructed within the main accelerator hall of the TRIUMF using stacks of large concrete blocks. An intense field of fast neutrons is produced during the interaction of high-energy proton beam with target materials, such as, beam stops, collimators and beam energy degraders. The leakage of such neutrons due to insufficient radiological shielding or through the shielding discontinuities may constitute a major share of the personnel radiation exposure of the radiation workers. The neutron energy distribution and dose equivalent near a lead beam stopper bombarded with 116 MeV and 65 MeV collimated proton beams at the Ocular Tumor irradiation facility were evaluated using a Bonner-Sphere Spectrometer and a REM counter respectively. The results were utilized to investigate efficacy of the existing radiological shielding of the PIF. This paper highlights experimental methods to analyze the high-energy accelerator produced neutron beam and basic guideline for the radiological shielding designs of irradiation vault of Proton Therapy facilities

  1. Integral test of JENDL dosimetry file using fast neutron field in the Experimental Fast Reactor JOYO

    International Nuclear Information System (INIS)

    Aoyama, Takafumi; Sekine, Takashi

    1999-09-01

    In order to evaluate the applicability of the JENDL dosimetry file, an integral test using a fast neutron spectrum field in the Experimental Fast Reactor JOYO Mark-II core was performed. The dosimeter set consisting of eight reactions of 46 Ti(n,p) 46 Sc, 54 Fe(n,p) 54 Mn, 58 Fe(n,γ) 59 Fe, 58 Ni(n,p) 58 Co, 59 Co(n,γ) 60 Co, 63 Cu(n,α) 60 Co, 238 U fission and 237 Np fission was irradiated for approximately 30 days near the core center of the JOYO Mk-II. Neutron flux at the dosimeter position was calculated using the two dimensional discrete ordinate transport code 'DORT'. The core configuration was modeled in XY geometry, and the 100 group cross section set of JSD-J2 / JFT-J2, which was processed from JENDL-2, was utilized. The absolute value of neutron flux was normalized so that the 235 U fission rate using the calculated neutron spectrum agreed with the measured reaction rate. The 103 group cross section data were processed by 'NJOY' code for nuclides to be used in the JOYO dosimetry. As the results of integral test for JENDL/D-99 (new file) and JENDL/D-91 (previous file), calculated values by JENDL/D-99 agreed well with the experimental values, and the C/E ratios ranged from 0.95 to 1.22. By comparing the results between JENDL/D-99 and JENDL/D-91, small differences exist, except for 58 Fe(n, γ) 59 Fe reaction, which was improved significantly in JENDL/D-99. (author)

  2. Depression of DNA synthesis rate following hyperthermia, gamma irradiation, cyclotron neutrons and mixed modalities

    International Nuclear Information System (INIS)

    Weber, H.J.; Muehlensiepen, H.; Porschen, W.; Feinendegen, L.E.; Dietzel, F.

    1978-01-01

    The incorporation of the thymidine analogue I-UdR is proportional to the activity of DNA synthesis. The maximum depression of 125-I-UdR incorporation occurs approximately 4 hours after all kinds of treatment. The increase which follow reflects cell processes like reoxygeneration, recovery, recycling and recruitment (although a direct relation is not yet demonstrable). The degree of depression 4 hours after treatment and the time required needs to reach control level is dependent on dose and radiation quaility but no such dependence could be clearly seen for the times of hyperthermia treatment we used. Neutron irradiation and the combination gamma irradiation + hyperthermia show a higher depression and a slower return to normal than gamma irradiation at the same dose. (orig.) [de

  3. Integral test on activation cross section of tag gas nuclides using fast neutron spectrum fields

    Energy Technology Data Exchange (ETDEWEB)

    Aoyama, Takafumi; Suzuki, Soju [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center

    1997-03-01

    Activation cross sections of tag gas nuclides, which will be used for the failed fuel detection and location in FBR plants, were evaluated by the irradiation tests in the fast neutron spectrum fields in JOYO and YAYOI. The comparison of their measured radioactivities and the calculated values using the JENDL-3.2 cross section set showed that the C/E values ranged from 0.8 to 2.8 for the calibration tests in YAYOI and that the present accuracies of these cross sections were confirmed. (author)

  4. Study of combinations of TL/OSL single dosimeters for mixed high/low ionization density radiation fields

    International Nuclear Information System (INIS)

    Oster, L.; Druzhyna, S.; Orion, I.; Horowitz, Y.S.

    2013-01-01

    In this paper we discuss and compare the potential application of combined OSL/TL measurements using 6 LiF:Mg,Ti (TLD-600 is enriched of isotope 6 Li which has a high cross-section for the reaction with slow neutrons) or 7 LiF:Mg,Ti ( TLD-700 is enriched of 7 Li isotope) and TLD-100 (natural isotopic composition) detectors. The OSL/TL duel readout of LiF:Mg,Ti as an ionization density discriminator avoids some of the difficulties inherent to the various types of discrimination mixed-field passive dosimeters, and in addition has several advantages. The preferential excitation of OSL compared to TL following high ionization density (HID) alpha irradiation, naturally explained via the identification of OSL with the “two-hit” F 2 or F 3 center, whereas the major component of composite TL glow peak 5 is believed to arise from a ''one-hit'' complex defect. This evidence allows near-total discrimination between HID radiation and low-ionization density (LID) radiation. Beta and alpha particle irradiations were carried out with 90 Sr/ 90 Y (∼500 keV average energy) and 241 Am sources (4.7 MeV) respectively and neutron irradiations were carried out at the PTB (Germany) (E n = 5 MeV) and RARAF (Columbia University, USA) (E n = 6 MeV) accelerator facilities. The highest values of the FOM obtained was ∼30 for neutron/gamma discrimination and ∼110 for alpha/gamma discrimination using OSL/TL – peak 5 measurements in TLD-700. -- Highlights: ► The increased response of OSL compared to TL following HID irradiation is observed. ► This evidence is explained via the identification of OSL with the ''two-hit'' F2 centers. ► The potential application of combined OSL/TL in discrimination dosimetry is discussed. ► The values of FOM were 110 for alpha/gamma and 30 for neutron/gamma discrimination

  5. THE HIDDEN MAGNETIC FIELD OF THE YOUNG NEUTRON STAR IN KESTEVEN 79

    International Nuclear Information System (INIS)

    Shabaltas, Natalia; Lai Dong

    2012-01-01

    Recent observations of the central compact object in the Kesteven 79 supernova remnant show that this neutron star (NS) has a weak dipole magnetic field (a few × 10 10 G) but an anomalously large (∼64%) pulse fraction in its surface X-ray emission. We explore the idea that a substantial sub-surface magnetic field exists in the NS crust, which produces diffuse hot spots on the stellar surface due to anisotropic heat conduction, and gives rise to the observed X-ray pulsation. We develop a general-purpose method, termed 'Temperature Template with Full Transport' (TTFT), that computes the synthetic pulse profile of surface X-ray emission from NSs with arbitrary magnetic field and surface temperature distributions, taking into account magnetic atmosphere opacities, beam pattern, vacuum polarization, and gravitational light bending. We show that a crustal toroidal magnetic field of order a few × 10 14 G or higher, varying smoothly across the crust, can produce sufficiently distinct surface hot spots to generate the observed pulse fraction in the Kes 79 NS. This result suggests that substantial sub-surface magnetic fields, much stronger than the 'visible' dipole fields, may be buried in the crusts of some young NSs, and such hidden magnetic fields can play an important role in their observational manifestations. The general TTFT tool we have developed can also be used for studying radiation from other magnetic NSs.

  6. Investigation of the neutron diffraction anomaly and electrical behaviour of α-LiIO3 single crystal under AC field

    International Nuclear Information System (INIS)

    Wang Guang; Yang Zhen

    1990-01-01

    A systematic study of the unique neutron diffraction and electric behaviour of α-LiIO 3 single crystal under AC field is reported. A frequency dependent rectification effect was observed and can be explained as the relaxation process in the ionic conduction. Theoretical treatment using Boltzmann equation gives satisfactory agreement with experimental results. The neutron diffraction anomaly can be attributed to the effect of the rectified DC current in the sample

  7. Calcium ions in aqueous solutions: Accurate force field description aided by ab initio molecular dynamics and neutron scattering

    Science.gov (United States)

    Martinek, Tomas; Duboué-Dijon, Elise; Timr, Štěpán; Mason, Philip E.; Baxová, Katarina; Fischer, Henry E.; Schmidt, Burkhard; Pluhařová, Eva; Jungwirth, Pavel

    2018-06-01

    We present a combination of force field and ab initio molecular dynamics simulations together with neutron scattering experiments with isotopic substitution that aim at characterizing ion hydration and pairing in aqueous calcium chloride and formate/acetate solutions. Benchmarking against neutron scattering data on concentrated solutions together with ion pairing free energy profiles from ab initio molecular dynamics allows us to develop an accurate calcium force field which accounts in a mean-field way for electronic polarization effects via charge rescaling. This refined calcium parameterization is directly usable for standard molecular dynamics simulations of processes involving this key biological signaling ion.

  8. Characterisation of the IRSN CANEL/T400 facility producing realistic neutron fields for calibration and test purposes

    International Nuclear Information System (INIS)

    Gressier, V.; Lacoste, V.; Lebreton, L.; Muller, H.; Pelcot, G.; Bakali, M.; Fernandez, F.; Tomas, M.; Roberts, N. J.; Thomas, D. J.; Reginatto, M.; Wiegel, B.; Wittstock, J.

    2004-01-01

    The new CANEL/T400 facility has been set-up at the Inst. for Radiological Protection and Nuclear Safety (IRSN) to produce a realistic neutron field. The accurate characterisation of this neutron field is mandatory since this facility will be used as a reference neutron source. For this reason an international measuring campaign, involving four laboratories with extensive expertise in neutron metrology and spectrometry, was organised through a concerted EUROMET project. Measurements were performed with Bonner sphere (BS) systems to determine the energy distribution of the emitted neutrons over the whole energy range (from thermal energy up to a few MeV). Additional measurements were performed with proton recoil detectors to provide detailed information in the energy region above 90 keV. The results obtained by the four laboratories are in agreement with each other and are compared with a calculation performed with the MCNP4C Monte-Carlo code. As a conclusion of this exercise, a reliable characterisation of the CANEL/T400 neutron field is obtained. (authors)

  9. ATLAS-TPX: a two-layer pixel detector setup for neutron detection and radiation field characterization

    International Nuclear Information System (INIS)

    Bergmann, B.; Caicedo, I.; Pospisil, S.; Vykydal, Z.; Leroy, C.

    2016-01-01

    A two-layer pixel detector setup (ATLAS-TPX), designed for thermal and fast neutron detection and radiation field characterization is presented. It consists of two segmented silicon detectors (256 × 256 pixels, pixel pitch 55 μm, thicknesses 300 μm and 500 μm) facing each other. To enhance the neutron detection efficiency a set of converter layers is inserted in between these detectors. The pixelation and the two-layer design allow a discrimination of neutrons against γs by pattern recognition and against charged particles by using the coincidence and anticoincidence information. The neutron conversion and detection efficiencies are measured in a thermal neutron field and fast neutron fields with energies up to 600 MeV. A Geant4 simulation model is presented, which is validated against the measured detector responses. The reliability of the coincidence and anticoincidence technique is demonstrated and possible applications of the detector setup are briefly outlined.

  10. Unparticle-Higgs field mixing: Mikheyev-Smirnov-Wolfenstein resonances, seesaw mechanism, and spinodal instabilities

    International Nuclear Information System (INIS)

    Boyanovsky, D.; Holman, R.; Hutasoit, Jimmy A.

    2009-01-01

    Motivated by slow-roll inflationary cosmology we study a scalar unparticle weakly coupled to a Higgs field in the broken symmetry phase. The mixing between the unparticle and the Higgs field results in a seesaw type matrix and the mixing angles feature a Mikheyev-Smirnov-Wolfenstein (MSW) effect as a consequence of the unparticle field being noncanonical. We find two (MSW) resonances for small and large spacelike momenta. The unparticlelike mode features a nearly flat potential with spinodal instabilities and a large expectation value. An effective potential for the unparticlelike field is generated from the Higgs potential, but with couplings suppressed by a large power of the small seesaw ratio. The dispersion relation for the Higgs-like mode features an imaginary part even at ''tree level'' as a consequence of the fact that the unparticle field describes a multiparticle continuum. Mixed unparticle-Higgs propagators reveal the possibility of oscillations, albeit with short coherence lengths. The results are generalized to the case in which the unparticle features a mass gap, in which case a low energy MSW resonance may occur for lightlike momenta depending on the scales. Unparticle-Higgs mixing leads to an effective unparticle potential of the new-inflation form. Slow-roll variables are suppressed by seesaw ratios and the anomalous dimensions and favor a red spectrum of scalar perturbations consistent with cosmic microwave background data.

  11. Unparticle-Higgs field mixing: Mikheyev-Smirnov-Wolfenstein resonances, seesaw mechanism, and spinodal instabilities

    Science.gov (United States)

    Boyanovsky, D.; Holman, R.; Hutasoit, Jimmy A.

    2009-04-01

    Motivated by slow-roll inflationary cosmology we study a scalar unparticle weakly coupled to a Higgs field in the broken symmetry phase. The mixing between the unparticle and the Higgs field results in a seesaw type matrix and the mixing angles feature a Mikheyev-Smirnov-Wolfenstein (MSW) effect as a consequence of the unparticle field being noncanonical. We find two (MSW) resonances for small and large spacelike momenta. The unparticlelike mode features a nearly flat potential with spinodal instabilities and a large expectation value. An effective potential for the unparticlelike field is generated from the Higgs potential, but with couplings suppressed by a large power of the small seesaw ratio. The dispersion relation for the Higgs-like mode features an imaginary part even at “tree level” as a consequence of the fact that the unparticle field describes a multiparticle continuum. Mixed unparticle-Higgs propagators reveal the possibility of oscillations, albeit with short coherence lengths. The results are generalized to the case in which the unparticle features a mass gap, in which case a low energy MSW resonance may occur for lightlike momenta depending on the scales. Unparticle-Higgs mixing leads to an effective unparticle potential of the new-inflation form. Slow-roll variables are suppressed by seesaw ratios and the anomalous dimensions and favor a red spectrum of scalar perturbations consistent with cosmic microwave background data.

  12. Rapid Mergers in a Mixed System of Black Holes and Neutron Stars

    Science.gov (United States)

    Tagawa, Hiromichi; Umemura, Masayuki

    Recently, it has been argued that r-process elements in galaxies primarily originate from the mergers of double neutron stars (NSs) and black hole (BH)-NS. However, there is a momentous problem that the merger timescale is estimated to be much longer than the production timescale of r-process elements inferred from metal poor stars in the Galactic halo. To solve this problem, we propose the rapid merger processes in gas-rich first-generation objects in a high redshift epoch. In such an era, it is expected that the dynamical friction by dense gas effectively promotes the merger of compact objects. To explore the possibility of mergers in a system composed of multiple NSs as well as BHs, we perform post Newtonian N-body simulations, incorporating the gas dynamical friction, the gas accretion, and the gravitational wave emission including the recoil kick. As a result, we find that NS-NS or NS-BH can merge within 10 Myr in first-generation objects. Furthermore, to satisfy the condition of the mass ejection of r-process elements, the gas accretion rate need to be lower than 0.1 Hoyle-Lyttleton accretion rate. These results imply that the mergers in early cosmic epochs may reconcile the conflict on the timescale of NS mergers.

  13. Bound-state β decay of a neutron in a strong magnetic field

    International Nuclear Information System (INIS)

    Kouzakov, Konstantin A.; Studenikin, Alexander I.

    2005-01-01

    The β decay of a neutron into a bound (pe - ) state and an antineutrino in the presence of a strong uniform magnetic field (B > or approx. 10 13 G) is considered. The β decay process is treated within the framework of the standard model of weak interactions. A Bethe-Salpeter formalism is employed for description of the bound (pe - ) system in a strong magnetic field. For the field strengths 10 13 18 G the estimate for the ratio of the bound-state decay rate w b and the usual (continuum-state) decay rate w c is derived. It is found that in such strong magnetic fields w b /w c ∼0.1-0.4. This is in contrast to the field-free case, where w b /w c ≅4.2x10 -6 [J. N. Bahcall, Phys. Rev. 124, 495 (1961); L. L. Nemenov, Sov. J. Nucl. Phys. 15, 582 (1972); X. Song, J. Phys. G: Nucl. Phys. 13, 1023 (1987)]. The dependence of the ratio w b /w c on the magnetic field strength B exhibits a logarithmiclike behavior. The obtained results can be important for applications in astrophysics and cosmology

  14. Study on the manganese distribution in the soil of an agricultural field using neutron activation analysis method

    International Nuclear Information System (INIS)

    Souza, Marcos P. de; Armelin, Maria J.A.; Cruvinel, Paulo E.

    1997-01-01

    Manganese distribution in the soil of an agricultural field was evaluated by neutron activation analysis. The accuracy and precision of the method were verified by the analysis of two Standard Reference Materials with different manganese concentration in the experimental field, through one schematic diagram. (author). 7 refs., 1 fig., 2 tabs

  15. Neutronic analysis of the PBMR-400 full core using thorium fuel mixed with plutonium or minor actinides

    International Nuclear Information System (INIS)

    Acır, Adem; Coşkun, Hasan

    2012-01-01

    Highlights: ► Neutronic calculations for PBMR 400 were conducted with the computer codes MCNP and MONTEBURNS 2.0. ► The criticality and burnup were investigated for reactor grade plutonium and minor actinides. ► We found that the use of these new fuels in PBMRs would reduce the nuclear waste repository significantly. -- Abstract: Time evolution of criticality and burnup grades of the PBMR were investigated for reactor grade plutonium and minor actinides in the spent fuel of light water reactors (LWRs) mixed with thoria. The calculations were performed by employing the computer codes MCNP and MONTEBURNS 2.0 and using the ENDF/B-V nuclear data library. Firstly, the plutonium–thorium and minor actinides–thorium ratio was determined by using the initial k eff value of the original uranium fuel design. After the selection of the plutonium/minor actinides–thorium mixture ratio, the time-dependent neutronic behavior of the reactor grade plutonium and minor actinides and original fuels in a PBMR-400 reactor was calculated by using the MCNP code. Finally, k eff , burnup and operation time values of the fuels were compared. The core effective multiplication factor (k eff ) for the original fuel which has 9.6 wt.% enriched uranium was computed as 1.2395. Corresponding to this k eff value the reactor grade plutonium/thorium and minor actinide/thorium oxide mixtures were found to be 30%/70% and 50%/50%, respectively. The core lives for the original, the reactor grade plutonium/thorium and the minor actinide/thorium fuels were calculated as ∼3.2, ∼6.5 and ∼5.5 years, whereas, the corresponding burnups came out to be 99,000, ∼190,000 and ∼166,000 MWD/T, respectively, for an end of life k eff set equal to 1.02.

  16. Mixed

    Directory of Open Access Journals (Sweden)

    Pau Baya

    2011-05-01

    Full Text Available Remenat (Catalan (Mixed, "revoltillo" (Scrambled in Spanish, is a dish which, in Catalunya, consists of a beaten egg cooked with vegetables or other ingredients, normally prawns or asparagus. It is delicious. Scrambled refers to the action of mixing the beaten egg with other ingredients in a pan, normally using a wooden spoon Thought is frequently an amalgam of past ideas put through a spinner and rhythmically shaken around like a cocktail until a uniform and dense paste is made. This malleable product, rather like a cake mixture can be deformed pulling it out, rolling it around, adapting its shape to the commands of one’s hands or the tool which is being used on it. In the piece Mixed, the contortion of the wood seeks to reproduce the plasticity of this slow heavy movement. Each piece lays itself on the next piece consecutively like a tongue of incandescent lava slowly advancing but with unstoppable inertia.

  17. The representation of neutron polarization

    International Nuclear Information System (INIS)

    Byrne, J.

    1979-01-01

    Neutron beam polarization representation is discussed under the headings; transfer matrices, coherent parity violation for neutrons, neutron spin rotation in helical magnetic fields, polarization and interference. (UK)

  18. Structure of neutron star crusts from new Skyrme effective interactions constrained by chiral effective field theory

    Science.gov (United States)

    Lim, Yeunhwan; Holt, Jeremy W.

    2017-06-01

    We investigate the structure of neutron star crusts, including the crust-core boundary, based on new Skyrme mean field models constrained by the bulk-matter equation of state from chiral effective field theory and the ground-state energies of doubly-magic nuclei. Nuclear pasta phases are studied using both the liquid drop model as well as the Thomas-Fermi approximation. We compare the energy per nucleon for each geometry (spherical nuclei, cylindrical nuclei, nuclear slabs, cylindrical holes, and spherical holes) to obtain the ground state phase as a function of density. We find that the size of the Wigner-Seitz cell depends strongly on the model parameters, especially the coefficients of the density gradient interaction terms. We employ also the thermodynamic instability method to check the validity of the numerical solutions based on energy comparisons.

  19. Validation of IRDFF in 252Cf Standard and IRDF-2002 Reference Neutron Fields

    Directory of Open Access Journals (Sweden)

    Simakov Stanislav

    2016-01-01

    Full Text Available The results of validation of the latest release of International Reactor Dosimetry and Fusion File, IRDFF-1.03, in the standard 252Cf(s.f. and reference 235U(nth,f neutron benchmark fields are presented. The spectrum-averaged cross sections were shown to confirm IRDFF-1.03 in the 252Cf standard spontaneous fission spectrum; that was not the case for the current recommended spectra for 235U(nth,f. IRDFF was also validated in the spectra of the research reactor facilities ISNF, Sigma-Sigma and YAYOI, which are available in the IRDF-2002 collection. The ISNF facility was re-simulated to remove unphysical oscillations in the spectrum. IRDFF-1.03 was shown to reproduce reasonably well the spectrum-averaged data measured in these fields except for the case of YAYOI.

  20. Out‐of‐field doses and neutron dose equivalents for electron beams from modern Varian and Elekta linear accelerators

    Science.gov (United States)

    Cardenas, Carlos E.; Nitsch, Paige L.; Kudchadker, Rajat J.; Howell, Rebecca M.

    2016-01-01

    Out‐of‐field doses from radiotherapy can cause harmful side effects or eventually lead to secondary cancers. Scattered doses outside the applicator field, neutron source strength values, and neutron dose equivalents have not been broadly investigated for high‐energy electron beams. To better understand the extent of these exposures, we measured out‐of‐field dose characteristics of electron applicators for high‐energy electron beams on two Varian 21iXs, a Varian TrueBeam, and an Elekta Versa HD operating at various energy levels. Out‐of‐field dose profiles and percent depth‐dose curves were measured in a Wellhofer water phantom using a Farmer ion chamber. Neutron dose was assessed using a combination of moderator buckets and gold activation foils placed on the treatment couch at various locations in the patient plane on both the Varian 21iX and Elekta Versa HD linear accelerators. Our findings showed that out‐of‐field electron doses were highest for the highest electron energies. These doses typically decreased with increasing distance from the field edge but showed substantial increases over some distance ranges. The Elekta linear accelerator had higher electron out‐of‐field doses than the Varian units examined, and the Elekta dose profiles exhibited a second dose peak about 20 to 30 cm from central‐axis, which was found to be higher than typical out‐of‐field doses from photon beams. Electron doses decreased sharply with depth before becoming nearly constant; the dose was found to decrease to a depth of approximately E(MeV)/4 in cm. With respect to neutron dosimetry, Q values and neutron dose equivalents increased with electron beam energy. Neutron contamination from electron beams was found to be much lower than that from photon beams. Even though the neutron dose equivalent for electron beams represented a small portion of neutron doses observed under photon beams, neutron doses from electron beams may need to be considered for

  1. Out-of-field doses and neutron dose equivalents for electron beams from modern Varian and Elekta linear accelerators.

    Science.gov (United States)

    Cardenas, Carlos E; Nitsch, Paige L; Kudchadker, Rajat J; Howell, Rebecca M; Kry, Stephen F

    2016-07-08

    Out-of-field doses from radiotherapy can cause harmful side effects or eventually lead to secondary cancers. Scattered doses outside the applicator field, neutron source strength values, and neutron dose equivalents have not been broadly investigated for high-energy electron beams. To better understand the extent of these exposures, we measured out-of-field dose characteristics of electron applicators for high-energy electron beams on two Varian 21iXs, a Varian TrueBeam, and an Elekta Versa HD operating at various energy levels. Out-of-field dose profiles and percent depth-dose curves were measured in a Wellhofer water phantom using a Farmer ion chamber. Neutron dose was assessed using a combination of moderator buckets and gold activation foils placed on the treatment couch at various locations in the patient plane on both the Varian 21iX and Elekta Versa HD linear accelerators. Our findings showed that out-of-field electron doses were highest for the highest electron energies. These doses typically decreased with increasing distance from the field edge but showed substantial increases over some distance ranges. The Elekta linear accelerator had higher electron out-of-field doses than the Varian units examined, and the Elekta dose profiles exhibited a second dose peak about 20 to 30 cm from central-axis, which was found to be higher than typical out-of-field doses from photon beams. Electron doses decreased sharply with depth before becoming nearly constant; the dose was found to decrease to a depth of approximately E(MeV)/4 in cm. With respect to neutron dosimetry, Q values and neutron dose equivalents increased with electron beam energy. Neutron contamination from electron beams was found to be much lower than that from photon beams. Even though the neutron dose equivalent for electron beams represented a small portion of neutron doses observed under photon beams, neutron doses from electron beams may need to be considered for special cases.

  2. ANALYSIS ON THE DYNAMICS OF SPATIAL DISTRIBUTION PATTERN OF MIXED SPIDER POPULATION IN RICE FIELD

    Institute of Scientific and Technical Information of China (English)

    ZhiWang; Zhe-mingYuan; Da-xiangSong; Ming-shengZhu

    2004-01-01

    The results make it clear that there are total 11 families, 29 genera and 43 species of spiders in the rice field of Dong Fang Hong Farm. Among them, there are 8 families, 19 genera and 28 species in the early rice field, and 10 families, 27 genera and 36 species in the late rice field. The spatial distribution pattern of mixed spider populations in rice fields was different during different development stages of rice plant. During the prophase, metaphase and anaphase of early rice plant development, the spatial distribution pattern of mixed spider populations was aggregative, random and aggregative respectively. During the prophase, metaphase and anaphase of late rice plant development, the spatial distribution pattern was uniform, aggregative and uniform respectively.

  3. Ground Albedo Neutron Sensing (GANS) method for measurements of soil moisture in cropped fields

    Science.gov (United States)

    Andres Rivera Villarreyes, Carlos; Baroni, Gabriele; Oswald, Sascha E.

    2013-04-01

    Measurement of soil moisture at the plot or hill-slope scale is an important link between local vadose zone hydrology and catchment hydrology. However, so far only few methods are on the way to close this gap between point measurements and remote sensing. This study evaluates the applicability of the Ground Albedo Neutron Sensing (GANS) for integral quantification of seasonal soil moisture in the root zone at the scale of a field or small watershed, making use of the crucial role of hydrogen as neutron moderator relative to other landscape materials. GANS measurements were performed at two locations in Germany under different vegetative situations and seasonal conditions. Ground albedo neutrons were measured at (i) a lowland Bornim farmland (Brandenburg) cropped with sunflower in 2011 and winter rye in 2012, and (ii) a mountainous farmland catchment (Schaefertal, Harz Mountains) since middle 2011. At both sites depth profiles of soil moisture were measured at several locations in parallel by frequency domain reflectometry (FDR) for comparison and calibration. Initially, calibration parameters derived from a previous study with corn cover were tested under sunflower and winter rye periods at the same farmland. GANS soil moisture based on these parameters showed a large discrepancy compared to classical soil moisture measurements. Therefore, two new calibration approaches and four different ways of integration the soil moisture profile to an integral value for GANS were evaluated in this study. This included different sets of calibration parameters based on different growing periods of sunflower. New calibration parameters showed a good agreement with FDR network during sunflower period (RMSE = 0.023 m3 m-3), but they underestimated soil moisture in the winter rye period. The GANS approach resulted to be highly affected by temporal changes of biomass and crop types which suggest the need of neutron corrections for long-term observations with crop rotation. Finally

  4. Residual stress characterization of steel TIG welds by neutron diffraction and by residual magnetic stray field mappings

    Energy Technology Data Exchange (ETDEWEB)

    Stegemann, Robert, E-mail: Robert.Stegemann@bam.de [Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, 12200 Berlin (Germany); Cabeza, Sandra; Lyamkin, Viktor; Bruno, Giovanni; Pittner, Andreas [Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, 12200 Berlin (Germany); Wimpory, Robert; Boin, Mirko [HZB Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Kreutzbruck, Marc [Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, 12200 Berlin (Germany); IKT, University of Stuttgart, Pfaffenwaldring 32, 70569 Stuttgart (Germany)

    2017-03-15

    The residual stress distribution of tungsten inert gas welded S235JRC+C plates was determined by means of neutron diffraction (ND). Large longitudinal residual stresses with maxima around 600 MPa were found. With these results as reference, the evaluation of residual stress with high spatial resolution GMR (giant magneto resistance) sensors was discussed. The experiments performed indicate a correlation between changes in residual stresses (ND) and the normal component of local residual magnetic stray fields (GMR). Spatial variations in the magnetic field strength perpendicular to the welds are in the order of the magnetic field of the earth. - Highlights: • Comparison of magnetic microstructure with neutron diffraction stress analysis. • High spatial resolution magnetic stray field images of hypereutectoid TIG welds. • Spatial variations of the stray fields are below the magnetic field of the earth. • GMR spin valve gradiometer arrays adapted for the evaluation of magnetic microstructures. • Magnetic stray fields are closely linked to microstructure of the material.

  5. Characterization of the neutronic fields obtained by means of neutron traps inside the nuclear reactor core IPEN/MB-01

    International Nuclear Information System (INIS)

    Mura, Luiz Ernesto Credidio

    2011-01-01

    This paper presents the results of the neutron flux values obtained from the deployment of a Flux Trap of neutrons in the reactor core IPEN/MB-01. We analyzed several configurations of Flux Traps deployed in the reactor core IPEN/MB-01 in order to get elected to Flux Trap configuration more efficient. To characterize the neutron spectrum were irradiated in the center of the Flux Trap activation detectors of different materials (Au, Sc, In, Ti, Ni). The respective gamma spectroscopy of these elements after irradiation with and without cadmium cover, provided the experimental values of the nuclear reaction rates (saturation activity) by the target nuclei and their uncertainties used as input to the code SANDBP who calculated the energy spectrum of neutrons in the center of the 'Flux-Trap' in 50 energy groups, using the input spectra calculated at the irradiation position (center of the 'Flux Trap') by codes for Reactor Physics. The results found an increase in the thermal neutron flux in the center of the Flux Trap configuration 203 for the standard configuration (default) of about 350% without having the need to increase the reactor power. We also made comparisons between the spectra obtained by SANDBP deployed, compared to those calculated by MCNP-4C code and XSDRNPM. The spatial characterization of the thermal neutron flux is made with activation foils in the form of an infinitely dilute bulk alloy of 1% Au and 99% Al in some internal points of the configuration 203 (axially to Flux Trap a nd adjacent radial) and the results showed a significant increase in the magnitude of their values when compared to standard rectangular configuration. (author)

  6. Crystal field in ErGa3 - a neutron spectroscopy study

    International Nuclear Information System (INIS)

    Murasik, A.; Czopnik, A.; Clementyev, E.; Schefer, J.

    2000-01-01

    The splitting of the J = 15/2 multiplet of Er in a cubic crystal field has been determined by inelastic scattering from a polycrystalline sample of ErGa 3 . On the base of observed intensities and their temperature variation we have been able to determine two crystal electric fields (CEF) parameters required for cubic symmetry. Least-squares fits of calculated crystal field transitions of the observed neutron inelastic scattering spectra taken at 12, 24, 32, 40, 50 and 80 K, gave the crystal field parameters: B 4 (7.15±0.05) x 10 -5 and B 6 = (1.28±0.05) x 1- -6 MeV yielding the Γ 7 doublet as a ground level with the overall splitting of 10.92 MeV. The results are used to calculate the temperature-depended zero field magnetization and the Schottky anomaly of the heat capacity of the ErGa 3 which yield reasonable agreement with experimental data obtained earlier. (author)

  7. Neutron Reference Benchmark Field Specifications: ACRR Polyethylene-Lead-Graphite (PLG) Bucket Environment (ACRR-PLG-CC-32-CL).

    Energy Technology Data Exchange (ETDEWEB)

    Vega, Richard Manuel [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Parm, Edward J. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Griffin, Patrick J. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Vehar, David W. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-07-01

    This report was put together to support the International Atomic Energy Agency (IAEA) REAL- 2016 activity to validate the dosimetry community’s ability to use a consistent set of activation data and to derive consistent spectral characterizations. The report captures details of integral measurements taken in the Annular Core Research Reactor (ACRR) central cavity with the Polyethylene-Lead-Graphite (PLG) bucket, reference neutron benchmark field. The field is described and an “a priori” calculated neutron spectrum is reported, based on MCNP6 calculations, and a subject matter expert (SME) based covariance matrix is given for this “a priori” spectrum. The results of 37 integral dosimetry measurements in the neutron field are reported.

  8. Construction of 144, 565 keV and 5.0 MeV monoenergetic neutron calibration fields at JAERI.

    Science.gov (United States)

    Tanimura, Y; Yoshizawa, M; Saegusa, J; Fujii, K; Shimizu, S; Yoshida, M; Shibata, Y; Uritani, A; Kudo, K

    2004-01-01

    Monoenergetic neutron calibration fields of 144, 565 keV and 5.0 MeV have been developed at the Facility of Radiation Standards of JAERI using a 4 MV Pelletron accelerator. The 7Li(p,n)7Be and 2H(d,n)3He reactions are employed for neutron production. The neutron energy was measured by the time-of-flight method with a liquid scintillation detector and calculated with the MCNP-ANT code. A long counter is employed as a neutron monitor because of the flat response. The monitor is set up where the influence of inscattered neutrons from devices and their supporting materials at a calibration point is as small as possible. The calibration coefficients from the monitor counts to the neutron fluence at a calibration point were obtained from the reference fluence measured with the transfer instrument of the primary standard laboratory (AIST), a 24.13 cm phi Bonner sphere counter. The traceability of the fields to AIST was established through the calibration.

  9. Computational Model Prediction and Biological Validation Using Simplified Mixed Field Exposures for the Development of a GCR Reference Field

    Science.gov (United States)

    Hada, M.; Rhone, J.; Beitman, A.; Saganti, P.; Plante, I.; Ponomarev, A.; Slaba, T.; Patel, Z.

    2018-01-01

    The yield of chromosomal aberrations has been shown to increase in the lymphocytes of astronauts after long-duration missions of several months in space. Chromosome exchanges, especially translocations, are positively correlated with many cancers and are therefore a potential biomarker of cancer risk associated with radiation exposure. Although extensive studies have been carried out on the induction of chromosomal aberrations by low- and high-LET radiation in human lymphocytes, fibroblasts, and epithelial cells exposed in vitro, there is a lack of data on chromosome aberrations induced by low dose-rate chronic exposure and mixed field beams such as those expected in space. Chromosome aberration studies at NSRL will provide the biological validation needed to extend the computational models over a broader range of experimental conditions (more complicated mixed fields leading up to the galactic cosmic rays (GCR) simulator), helping to reduce uncertainties in radiation quality effects and dose-rate dependence in cancer risk models. These models can then be used to answer some of the open questions regarding requirements for a full GCR reference field, including particle type and number, energy, dose rate, and delivery order. In this study, we designed a simplified mixed field beam with a combination of proton, helium, oxygen, and iron ions with shielding or proton, helium, oxygen, and titanium without shielding. Human fibroblasts cells were irradiated with these mixed field beam as well as each single beam with acute and chronic dose rate, and chromosome aberrations (CA) were measured with 3-color fluorescent in situ hybridization (FISH) chromosome painting methods. Frequency and type of CA induced with acute dose rate and chronic dose rates with single and mixed field beam will be discussed. A computational chromosome and radiation-induced DNA damage model, BDSTRACKS (Biological Damage by Stochastic Tracks), was updated to simulate various types of CA induced by

  10. Pulsed neutron generator

    International Nuclear Information System (INIS)

    Bespalov, D.F.; Bykovskii, Yu.A.; Vergun, I.I.; Kozlovskii, K.I.; Kozyrev, Yu.P.; Leonov, R.K.; Simagin, B.I.; Tsybin, A.S.; Shikanov, A.Ie.

    1986-03-01

    The paper describes a new device for generating pulsed neutron fields, utilized in nuclear geophysics for carrying out pulsed neutron logging and activation analysis under field conditions. The invention employs a sealed-off neutron tube with a laser ion source which increases neutron yield to the level of 10 neutrons per second or higher. 2 refs., 1 fig

  11. Research in the field of neutronics and nuclear data for fusion

    International Nuclear Information System (INIS)

    Batistoni, P.

    2001-01-01

    A reliable and validated nuclear database is required for the design of a fusion reactor. Neutrons produced by the fusion reactions between deuterium and tritium have a very peaked energy spectrum at 14 MeV, requiring a substantial extrapolation with respect to the database made available from fission studies. The correct evaluation of shielding properties, damage, nuclear heating and of tritium breeding performance in the blanket surrounding the reaction chamber is crucial to the correct reactor design. Moreover, the attractiveness of fusion relies in the low activation of the reactor components and in the minimal production of long-term radioactive waste that is pursued with development of low activation materials. Beside the materials development, Europe is carrying out a co-ordinated program for the development of adequate nuclear database and numerical tools, directed to evaluations, processing, application, and benchmarking of cross sections including uncertainty information. Experimental validation of data and of the relative uncertainties is also pursued, both on material samples and on more design-oriented experiments. A general view of the research work in the field of neutronics and nuclear data for fusion will be given in the presentation, with emphasis to the experimental validation activity.(author)

  12. Magnetic neutron scattering resonance of high-¤Tc¤ superconductors in external magnetic fields: An SO(5) study

    DEFF Research Database (Denmark)

    Mortensen, Asger; Rønnow, Henrik Moodysson; Bruus, Henrik

    2000-01-01

    The magnetic resonance at 41 meV observed in neutron scattering studies of YBa2Cu3O7 holds a key position in the understanding of high-T-c, superconductivity. Within the SO(5) model for superconductivity and antiferromagnetism, we have calculated the effect of an applied magnetic field on the neu......The magnetic resonance at 41 meV observed in neutron scattering studies of YBa2Cu3O7 holds a key position in the understanding of high-T-c, superconductivity. Within the SO(5) model for superconductivity and antiferromagnetism, we have calculated the effect of an applied magnetic field...

  13. DNA damage induced by radiation plasmodial mixed + gamma thermal neutrons in the presence and absence of free radical scavenger

    International Nuclear Information System (INIS)

    Rodriguez Gual, Maritza; Mas Milian, Felix; Gouveia, Andreia; Deppman, Airton

    2010-01-01

    In this work is quantified the damage in DNA plasmid induced by mixed radiation (thermal neutron and gamma rays) for first time. For the study was used the pBs KS+ plasmid of 2961 bp in aqueous solution of the 88 ng/μL with 0, 2 and 20 mmol/L of glycerol which acts as a free radicals scavenger. This plasmid changes its form of supercoiled to circular when a simple strand break is produced, and passes to a linear form when a double strand break is produced in the chain. Quantifying the fractions that exist in each of these forms is possible to estimate the effect of radiation on DNA. The irradiations were carried out in the radial channel 3 at IEA-R1 research reactor of the Instituto de Pesquisas Energeticas y Nucleares in Sao Paulo, Brazil. DNA forms were separated by agarose gel electrophoresis. For quantification the program GelAnalis was used. The values of the fractions of DNA in various forms were plotted as a function of dose and fitted to exponential and linear functions to obtaining the probabilities of simple and double strand breaks normalized by dose and molecular mass. The results showed the protective action of free radical scavenger against damage induced for radiation which corroborates the previous results found with other ionizing radiations. Yields of SSB and DSB will be of interest for the validation of the different models that attempt to reproduce the experimental results

  14. Effects of mixed neutron-γ total-body irradiation on physical activity performance of rhesus monkeys

    International Nuclear Information System (INIS)

    Franz, C.G.

    1985-01-01

    Behavioral incapacitation for a physical activity task and its relationship to emesis and survival time following exposure to ionizing radiation were evaluated in 39 male rhesus monkeys (Macaca mulatta). Subjects were trained to perform a shock avoidance activity task for 6 hr on a 10-min work/5-min rest schedule in a nonmotorized physical activity wheel. Following stabilization of performance, each subject received a single, pulsed dose of mixed neutron-γ, whole-body radiation (n/γ = 3.0) ranging between 1274 and 4862 rad. Performance testing was started 45 sec after exposure. A dose-response function for early transient incapacitation (ETI) during the first 2 hr after irradiation was fitted, and the median effective dose (ED 50 ) was calculated to be 1982 rad. Analysis done on the relationship of dose to ETI, emesis, and survival time found (a) a significant relationship between the radiation dose and the number and duration of ETIs; (b) no correlation between emesis and dose, survival time, or ETI; (c) no relation between survival time and ETI at any dose; and (d) no significant difference in survival time for dose groups between 1766 +/- 9 (SEM) and 2308 +/- 23 rad

  15. Analysis of mixed oxide fuel critical experiments with neutronics analysis codes for boiling water reactors

    International Nuclear Information System (INIS)

    Tamitani, Masashi; Maruyama, Hiromi; Ishii, Kazuya; Izutsu, Sadayuki; Yamaguchi, Masao

    2000-01-01

    Critical experiments of UO 2 and full mixed oxide (MOX) fuel cores conducted at the Tank-type Critical Assembly (TCA) were analyzed using BWR design-purpose codes HINES and CERES with ENDF/B files and Monte Carlo fine analysis codes VMONT and MVP with the JENDL-3.2 library. The averaged values of the multiplication factors calculated with HINES/CERES, VMONT and MVP agreed with those of experiments within 0.3%Δk. The values by the design-purpose codes showed a small difference of 0.1%Δk between UO 2 and MOX cores. Monte Carlo code results showed that the JENDL-3.2 library had a tendency to overestimate the multiplication factors of UO 2 cores by about 0.3%Δk compared with those values of MOX cores. The root mean square errors of calculated power distributions were less than 1% for HINES/CERES and VMONT. These results showed that (1) the accuracy of these codes when applied to full MOX cores was almost the same as their accuracy for UO 2 cores, which confirmed the accuracy of present core design codes for full MOX cores; and (2) the accuracy of the 190-energy-group Monte Carlo calculation code VMONT was almost the same as that of the continuous-energy Monte Carlo calculation code MVP. (author)

  16. Development of Real-Time Measurement of Effective Dose for High Dose Rate Neutron Fields

    International Nuclear Information System (INIS)

    Braby, L. A.; Reece, W. D.; Hsu, W. H.

    2003-01-01

    Studies of the effects of low doses of ionizing radiation require sources of radiation which are well characterized in terms of the dose and the quality of the radiation. One of the best measures of the quality of neutron irradiation is the dose mean lineal energy. At very low dose rates this can be determined by measuring individual energy deposition events, and calculating the dose mean of the event size. However, at the dose rates that are normally required for biology experiments, the individual events can not be separated by radiation detectors. However, the total energy deposited in a specified time interval can be measured. This total energy has a random variation which depends on the size of the individual events, so the dose mean lineal energy can be calculated from the variance of repeated measurements of the energy deposited in a fixed time. We have developed a specialized charge integration circuit for the measurement of the charge produced in a small ion chamber in typical neutron irradiation experiments. We have also developed 4.3 mm diameter ion chambers with both tissue equivalent and carbon walls for the purpose of measuring dose mean lineal energy due to all radiations and due to all radiations except neutrons, respectively. By adjusting the gas pressure in the ion chamber, it can be made to simulate tissue volumes from a few nanometers to a few millimeters in diameter. The charge is integrated for 0.1 seconds, and the resulting pulse height is recorded by a multi channel analyzer. The system has been used in a variety of photon and neutron radiation fields, and measured values of dose and dose mean lineal energy are consistent with values extrapolated from measurements made by other techniques at much lower dose rates. It is expected that this technique will prove to be much more reliable than extrapolations from measurements made at low dose rates because these low dose rate exposures generally do not accurately reproduce the attenuation and

  17. Magnetic field dependence of static correlations and spin dynamics of reentrant spin glasses studied by neutron scattering

    International Nuclear Information System (INIS)

    Hennion, M.; Hennion, B.; Mirebeau, I.; Lequien, S.; Hippert, F.

    1988-01-01

    We report small angle (SANS) and inelastic neutron scattering in zero and applied field for a-FeMn, NiMn and AuFe at composition where both ferromagnetic and frustration characters occur. We discuss the field evolution of the transverse correlations which arise below T c . A study of the field sensitivity of the spin wave anomalies in a-FeMn is reported

  18. Neutron scattering techniques for betaine calcium chloride dihydrate under applied external field (temperature, electric field and hydrostatic pressure)

    International Nuclear Information System (INIS)

    Hernandez, O.

    1997-01-01

    We have studied with neutron scattering techniques betaine calcium chloride dihydrate (BCCD), a dielectric aperiodic crystal which displays a Devil's staircase type phase diagram made up of several incommensurate and commensurate phases, having a range of stability very sensitive to temperature, electric field and hydrostatic pressure. We have measured a global hysteresis of δ(T) of about 2-3 K in the two incommensurate phases. A structural study of the modulated commensurate phases 1/4 and 1/5 allows us to evidence that the atomic modulation functions are anharmonic. The relevance of the modelization of the modulated structure by polar Ising pseudo-spins is then directly established. On the basis of group theory calculation in the four dimensional super-space, we interpret this anharmonic modulation as a soliton regime with respect to the lowest-temperature non modulated ferroelectric phase. The continuous character of the transition to the lowest-temperature non modulated phase and the diffuse scattering observed in this phase are accounted for the presence of ferroelectric domains separated by discommensurations. Furthermore, we have shown that X-rays induce in BCCD a strong variation with time of irradiation of the intensity of satellite peaks, and more specifically for third order ones. This is why the 'X-rays' structural model is found more harmonic than the 'neutron' one. Under electric field applied along the vector b axis, we confirm that commensurate phases with δ = even/odd are favoured and hence are polar along this direction. We have evidenced at 10 kV / cm two new higher order commensurate phases in the phase INC2, corroborating the idea of a 'complete' Devil's air-case phase diagram. A phenomenon of generalized coexistence of phases occurs above 5 kV / cm. We have characterized at high field phase transitions between 'coexisting' phases, which are distinguishable from classical lock-in transitions. Under hydrostatic pressure, our results contradict

  19. On the mixed discretization of the time domain magnetic field integral equation

    KAUST Repository

    Ulku, Huseyin Arda

    2012-09-01

    Time domain magnetic field integral equation (MFIE) is discretized using divergence-conforming Rao-Wilton-Glisson (RWG) and curl-conforming Buffa-Christiansen (BC) functions as spatial basis and testing functions, respectively. The resulting mixed discretization scheme, unlike the classical scheme which uses RWG functions as both basis and testing functions, is proper: Testing functions belong to dual space of the basis functions. Numerical results demonstrate that the marching on-in-time (MOT) solution of the mixed discretized MFIE yields more accurate results than that of classically discretized MFIE. © 2012 IEEE.

  20. Test of the rem-counter WENDI-II from Eberline in different energy-dispersed neutron fields

    International Nuclear Information System (INIS)

    Gutermuth, F.; Radon, T.; Fehrenbacher, G.; Siekmann, R.

    2004-03-01

    The neutron rem-counter WENDI-II from Eberline was tested in high-energy particle accelerator produced neutron fields. A radioactive 241 Am-Be(αn) source was used as a reference. The experimentally determined responses are compared to Monte-Carlo simulations of the response function done by R. H. Olsher et al. (2000). The energy spectra of the accelerator produced neutron fields were determined employing Monte-Carlo simulations, too. According to the simulations done by C. Birattari et al. (1998) and in this work these neutron fields exhibit large contributions to the ambient dose equivalent resulting from neutrons with kinetic energy of more than 20 MeV up to a few 100 MeV. The WENDI-II detector proved to show a response of approximately 3.10 9 pulses per Sievert ambient dose equivalent. Considering the experimental and statistical uncertainties the results are consistent with the assumption that the dose response of the WENDI-II reproduces quite accurately the function for the ambient dose equivalent of the ICRP 74