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Sample records for magnetically shielded room

  1. Improvement of open-type magnetically shielded room composed of magnetic square cylinders by controlling flux path

    International Nuclear Information System (INIS)

    Hirosato, S.; Yamazaki, K.; Tsuruta, T.; Haraguchi, Y.; Kosaka, M.; Gao, Y.; Muramatsu, K.; Kobayashi, K.

    2011-01-01

    We have developed an open-type magnetically shielded room composed of magnetic square cylinders that has been used for an actual MRI in a hospital. To improve shielding performance, we propose here a method to control the path of the magnetic flux in the wall composed of the magnetic square cylinders by changing the magnetic permeability in each direction of the square cylinders spatially. First, we discuss a method to control the magnetic permeability in each direction of the square cylinders independently by inserting slits without changing the outside dimensions of the square cylinders, by using 3-D magnetic field analysis. Then, the effectiveness of the design of controlling the flux pass was shown by magnetic field analysis and experiments. (author)

  2. Simple Design Method for Magnetic Shield Room(The 20th MAGDA Conference in Pacific Asia (MAGDA2011))

    OpenAIRE

    Keisuke, FUJISAKI; Masahiro, FUJIKURA; Jirou, MINO; Nippon Steel Corporation:Toyota Technological Institute; Nippon Steel Corporation; Nippon Steel Engineering Co., Ltd

    2012-01-01

    As a primary evaluation of the magnetic shield room design, a simple design method is proposed here. The steel sheet number of the magnetic shield room is designed so as to make the distributed magnetic flux density from the exciting coil catch the magnetic shield body. The proposed method is applied to a full-scale magnetic shield room and the leakage magnetic flux density is evaluated by numerical calculation. Though it introduces a large steel number of the magnetic shield body, the leakag...

  3. Hybrid Magnetic Shielding

    Science.gov (United States)

    Royal, Kevin; Crawford, Christopher; Mullins, Andrew; Porter, Greg; Blanton, Hunter; Johnstone, Connor; Kistler, Ben; Olivera, Daniela

    2017-09-01

    The search for the electric dipole moment of the neutron requires the ambient magnetic field to be on the pT scale which is accomplished with large magnetic shielding rooms. These rooms are fitted with large mu-metal sheets to allow for passive cancellation of background magnetic fields. Active shielding technology cannot uniformly cancel background magnetic fields. These issues can be remedied by combining the methods into a hybrid system. The design used is composed of panels that have an active layer of cancellation between two sheets of mu-metal. The panels form a cube and draw in magnetic fields perpendicular to the surface which can then be reduced using active shielding. This work is supported by the Department of Energy under Contract DE-SC0008107.

  4. Shielded room measurements, Final report

    Energy Technology Data Exchange (ETDEWEB)

    Stanton, J.S.

    1949-02-22

    The attenuation of electro-statically and electro-magnetically shielded rooms in the ``E,`` ``R,`` ``I,`` and ``T`` Buildings was measured so that corrective measure could be taken if the attenuation was found to be low. If remedial measures could not be taken, the shortcomings of the rooms would be known. Also, the men making the measurements should oversee construction and correct errors at the time. The work was performed by measuring the attenuation at spot frequencies over the range of from 150 kilocycles to 1280 megacycles with suitable equipment mounted in small rubber-tried trucks. The attenuation was determined by ``before and after`` shielding and/or ``door open and door closed`` measurements after installation of copper shielding. In general, attenuation in the frequency range of approximately 10 to 150 mc. was good and was of the order expected. At frequencies in the range of 150 mc. to 1280 mc., the attenuation curve was more erratic; that is, at certain frequencies a severe loss of attenuation was noted, while at others, the attenuation was very good. This was mainly due to poor or faulty seals around doors and pass windows. These poor seals existed in the ``T,`` ``E,`` and ``I`` Buildings because the doors were fitted improperly and somewhat inferior material was used. By experience from these difficulties, both causes were corrected in the ``R`` Building, which resulted in the improvement of the very high frequency (v.h.f.) range in this building. In some specific cases, however, the results were about the same. For the range of frequencies below approximately 10 mc., the attenuation, in almost all cases, gradually decreased as the frequency decreased and reached a minimum at .3 to 1.0 mc. This loss of attenuation was attributed to multiple grounding caused by moisture in the insulating timbers and will gradually decrease as the wood dries out.

  5. Dynamical cancellation of pulse-induced transients in a metallic shielded room for ultra-low-field magnetic resonance imaging

    International Nuclear Information System (INIS)

    Zevenhoven, Koos C. J.; Ilmoniemi, Risto J.; Dong, Hui; Clarke, John

    2015-01-01

    Pulse-induced transients such as eddy currents can cause problems in measurement techniques where a signal is acquired after an applied preparatory pulse. In ultra-low-field magnetic resonance imaging, performed in magnetic fields typically of the order of 100 μT, the signal-to-noise ratio is enhanced in part by prepolarizing the proton spins with a pulse of much larger magnetic field and in part by detecting the signal with a Superconducting QUantum Interference Device (SQUID). The pulse turn-off, however, can induce large eddy currents in the shielded room, producing an inhomogeneous magnetic-field transient that both seriously distorts the spin dynamics and exceeds the range of the SQUID readout. It is essential to reduce this transient substantially before image acquisition. We introduce dynamical cancellation (DynaCan), a technique in which a precisely designed current waveform is applied to a separate coil during the later part and turn off of the polarizing pulse. This waveform, which bears no resemblance to the polarizing pulse, is designed to drive the eddy currents to zero at the precise moment that the polarizing field becomes zero. We present the theory used to optimize the waveform using a detailed computational model with corrections from measured magnetic-field transients. SQUID-based measurements with DynaCan demonstrate a cancellation of 99%. Dynamical cancellation has the great advantage that, for a given system, the cancellation accuracy can be optimized in software. This technique can be applied to both metal and high-permeability alloy shielded rooms, and even to transients other than eddy currents

  6. Magnetic shielding for superconducting RF cavities

    Science.gov (United States)

    Masuzawa, M.; Terashima, A.; Tsuchiya, K.; Ueki, R.

    2017-03-01

    Magnetic shielding is a key technology for superconducting radio frequency (RF) cavities. There are basically two approaches for shielding: (1) surround the cavity of interest with high permeability material and divert magnetic flux around it (passive shielding); and (2) create a magnetic field using coils that cancels the ambient magnetic field in the area of interest (active shielding). The choice of approach depends on the magnitude of the ambient magnetic field, residual magnetic field tolerance, shape of the magnetic shield, usage, cost, etc. However, passive shielding is more commonly used for superconducting RF cavities. The issue with passive shielding is that as the volume to be shielded increases, the size of the shielding material increases, thereby leading to cost increase. A recent trend is to place a magnetic shield in a cryogenic environment inside a cryostat, very close to the cavities, reducing the size and volume of the magnetic shield. In this case, the shielding effectiveness at cryogenic temperatures becomes important. We measured the permeabilities of various shielding materials at both room temperature and cryogenic temperature (4 K) and studied shielding degradation at that cryogenic temperature.

  7. Surface magnetic field measurement with magnetic shielding

    Czech Academy of Sciences Publication Activity Database

    Perevertov, Oleksiy

    2010-01-01

    Roč. 61, č. 7 (2010), 66-68 ISSN 1335-3632 Grant - others:AVČR(CZ) M100100906 Institutional research plan: CEZ:AV0Z10100520 Keywords : magnetic hysteresis * magnetic field measurement * magnetic shielding * extrapolation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.270, year: 2010

  8. Magnetic shielding for MRI superconducting magnets

    International Nuclear Information System (INIS)

    Ishiyama, A.; Hirooka, H.

    1991-01-01

    This paper describes an optimal design of a highly homogeneous superconducting coil system with magnetic shielding for Magnetic Resonance Imaging (MRI). The presented optimal design method; which is originally proposed in our earlier papers, is a combination of the hybrid finite element and boundary element method for analysis of an axially symmetric nonlinear open boundary magnetic field problem, and the mathematical programming method for solving the corresponding optimization problem. In this paper, the multi-objective goal programming method and the nonlinear least squares method have been adopted. The optimal design results of 1.5- and 4.7-Tesla-magnet systems with different types of magnetic shielding for whole-body imaging are compared and the advantages of a combination of active and yoke shields are shown

  9. Magnetic shield effect simulation of superconducting film shield covering directly coupled HTS dc-SQUID magnetometer

    International Nuclear Information System (INIS)

    Terauchi, N.; Noguchi, S.; Igarashi, H.

    2011-01-01

    A superconducting film shield over a SQUID ring improves the robustness of the SQUID with respect to magnetic noise. Supercurrent in the SQUID magnetometer and the superconducting film shield were simulated. The superconducting film shield reduces the influence of the external magnetic field on the SQUID ring. An HTS SQUID is a high sensitive magnetic sensor. In recent years, the HTS SQUID is widely used in various applications. In some applications, high robustness with respect to magnetic noise is required to realize stable operation at outside of a magnetic shielding room. The target of this paper is a directly coupled HTS dc-SQUID magnetometer. To enhance the robustness of the SQUID magnetometer, use of a superconducting thin film shield has been proposed. The magnetic field directly penetrating the SQUID ring causes the change of the critical current of Josephson junction, and then the SQUID magnetometer transitions into inoperative state. In order to confirm the magnetic shield effect of the superconducting film shield, electromagnetic field simulation with 3D edge finite element method was performed. To simulate the high temperature superconductor, E-J characteristics and c-axis anisotropy are considered. To evaluate the effect of the superconducting film shield, an external magnetic field which is supposed to be a magnetic noise is applied. From the simulation results, the time transition of the magnetic flux penetrating the SQUID ring is investigated and the effect of the superconducting film shield is confirmed. The amplitude of the magnetic flux penetrating the SQUID ring can be reduced to about one-sixth since the superconducting film shield prevents the magnetic noise from directly penetrating the SQUID ring.

  10. Magnetic shielding of a limiter

    International Nuclear Information System (INIS)

    Brevnov, N.N.; Stepanov, S.B.; Khimchenko, L.N.; Matthews, G.F.; Goodal, D.H.J.

    1991-01-01

    Localization of plasma interaction with material surfaces in a separate chamber, from where the escape of impurities is hardly realized, i.e. application of magnetic divertors or pump limiters, is the main technique for reduction of the impurity content in a plasma. In this case, the production of a divertor configuration requires a considerable power consumption and results in a less effective utilization of the magnetic field volume. Utilization of a pump limiter, for example the ICL-type, under tokamak-reactor conditions would result in the extremely high and forbidden local heat loadings onto the limiter surface. Moreover, the magnetically-shielded pump limiter (MSL) was proposed to combine positive properties of the divertor and the pump limiter. The idea of magnetic shielding is to locate the winding with current inside the limiter head so that the field lines of the resultant magnetic field do not intercept the limiter surface. In this case the plasma flows around the limiter leading edges and penetrates into the space under the limiter. The shielding magnetic field can be directed either counter the toroidal field or counter the poloidal one of a tokamak, dependent on the concrete diagram of the device. Such a limiter has a number of advantages: -opportunity to control over the particle and impurity recycling without practical influence upon the plasma column geometry, - perturbation of a plasma column magnetic configuration from the side of such a limiter is less than that from the side of the divertor coils. The main deficiency is the necessity to locate active windings inside the discharge chamber. (author) 5 refs., 3 figs

  11. Superconducting magnetic shields production. Realisation d'ecrans magnetiques supraconducteurs

    Energy Technology Data Exchange (ETDEWEB)

    Lainee, F; Kormann, R [Thomson-CSF, Domaine de Corbeville, 91 - Orsay (FR); Lainee, F [Ecole des Mines de Paris, 91 - Evry (FR)

    1992-02-01

    Low fields and low frequency shielding properties of YBCO magnetic shields are measured at 77 K. They compare favourably with shielding properties of mumetal shields. Therefore high-T{sub c} superconducting magnetic shields can already be used to shield small volumes. The case of magnetic shields for large volumes is also discussed. 3 refs; 6 figs; 4 tabs.

  12. A study of an active magnetic shielding method for the superconductive Maglev vehicle

    International Nuclear Information System (INIS)

    Nemoto, K.; Komori, M.

    2010-01-01

    Various methods of magnetic shielding have been studied so far to reduce magnetic field strength inside the passenger room of the superconductive Maglev vehicle. Magnetic shielding methods with ferromagnetic materials are very useful, but they tend to be heavier for large space. Though some passive magnetic shielding methods using induced currents in superconducting bulks or superconducting coils have also been studied, the induced current is relatively small and it is difficult to get satisfactory magnetic shielding performance for the passenger room of the Maglev vehicle. Thus, we have proposed an active magnetic shielding method with some superconducting coils of the same length as propulsion-levitation-guidance superconducting coils of the Maglev vehicle. They are arranged under the passenger room of the Maglev vehicle. Then, we studied the shielding effect by canceling magnetic flux density in the passenger room by way of adjusting magnetomotive-forces of the magnetic shielding coils. As a result, it is found that a simple arrangement of two magnetic shielding coils for one propulsion-levitation-guidance superconducting coil on the vehicle shows an effective magnetic shielding.

  13. A study of an active magnetic shielding method for the superconductive Maglev vehicle

    Energy Technology Data Exchange (ETDEWEB)

    Nemoto, K., E-mail: nemoto@kamakuranet.ne.j [Kyushu Institute of Technology, Dept. of Applied Science for Integrated System Engineering, 1-1 Sensui, Tobata, Kitakyushu, Fukuoka 804-8550 (Japan); Komori, M. [Kyushu Institute of Technology, Dept. of Applied Science for Integrated System Engineering, 1-1 Sensui, Tobata, Kitakyushu, Fukuoka 804-8550 (Japan)

    2010-11-01

    Various methods of magnetic shielding have been studied so far to reduce magnetic field strength inside the passenger room of the superconductive Maglev vehicle. Magnetic shielding methods with ferromagnetic materials are very useful, but they tend to be heavier for large space. Though some passive magnetic shielding methods using induced currents in superconducting bulks or superconducting coils have also been studied, the induced current is relatively small and it is difficult to get satisfactory magnetic shielding performance for the passenger room of the Maglev vehicle. Thus, we have proposed an active magnetic shielding method with some superconducting coils of the same length as propulsion-levitation-guidance superconducting coils of the Maglev vehicle. They are arranged under the passenger room of the Maglev vehicle. Then, we studied the shielding effect by canceling magnetic flux density in the passenger room by way of adjusting magnetomotive-forces of the magnetic shielding coils. As a result, it is found that a simple arrangement of two magnetic shielding coils for one propulsion-levitation-guidance superconducting coil on the vehicle shows an effective magnetic shielding.

  14. Magnetic shielding for coreless linear permanent magnet motors

    NARCIS (Netherlands)

    Pluk, K.J.W.; Jansen, J.W.; Lomonova, E.

    2013-01-01

    This paper concerns the local reduction of the magnetic flux density by means of magnetic shielding. Using a spatial frequency description, a 2-D semi-analytical periodic model is obtained for a coreless single-sided linear permanent magnet motor. The magnetic shield is included in the modeling

  15. Shielding calculation for treatment rooms of high energy linear accelerator

    International Nuclear Information System (INIS)

    Elleithy, M.A.

    2006-01-01

    A review of German Institute of Standardization (DIN) scheme of the shielding calculation and the essential data required has been done for X-rays and electron beam in the energy range from 1 MeV to 50 MeV. Shielding calculation was done for primary and secondary radiations generated during X-ray operation of Linac. In addition, shielding was done against X-rays generated (Bremsstrahlung) by useful electron beams. The calculations also covered the neutrons generated from the interactions of useful X-rays (at energies above 8 MeV) with the surrounding. The present application involved the computation of shielding against the double scattered components of X-rays and neutrons in the maze area and the thickness of the paraffin wax of the room door. A new developed computer program was designed to assist shielding thickness calculations for a new Linac installation or in replacing an existing machine. The program used a combination of published tables and figures in computing the shielding thickness at different locations for all possible radiation situations. The DIN published data of 40 MeV accelerator room was compared with the program calculations. It was found that there is good agreement between both calculations. The developed program improved the accuracy and speed of calculation

  16. Computer code for shielding calculations of x-rays rooms

    International Nuclear Information System (INIS)

    Affonso, R.R.W.; Borges, D. da S.; Lava, D.D.; Moreira, M. de L.; Guimarães, A.C.F.

    2015-01-01

    The building an effective barrier against ionizing radiation present in radiographic rooms requires consideration of many variables. The methodology used for thickness specification of primary and secondary, barrier of a traditional radiographic room, considers the following factors: Use Factor, Occupational Factor, distance between the source and the wall, Workload, Kerma in the air and distance between the patient and the source. With these data it was possible to develop a computer code, which aims to identify and use variables in functions obtained through graphics regressions provided by NCRP-147 (Structural Shielding Design for Medical X-Ray Imaging Facilities) report, for shielding calculation of room walls, and the walls of the dark room and adjacent areas. With the implemented methodology, it was made a code validation by comparison of results with a study case provided by the report. The obtained values for thickness comprise different materials such as concrete, lead and glass. After validation it was made a case study of an arbitrary radiographic room.The development of the code resulted in a user-friendly tool for planning radiographic rooms to comply with the limits established by CNEN-NN-3:01 published in september/2011. (authors)

  17. Shield design of concrete wall between decay tank room and primary pump room in TRIGA facility

    International Nuclear Information System (INIS)

    Khan, M. J. H.; Rahman, M.; Haque, A.; Zulquarnain, A.; Ahmed, F. U.; Bhuiyan, S. I.

    2007-01-01

    The objective of this study is to recommend the radiation protection design parameters from the shielding point of view for concrete wall between the decay tank room and the primary pump room in TRIGA Mark-II research reactor facility. The shield design for this concrete wall has been performed with the help of Point-kernel Shielding Code Micro-Shield 5.05 and this design was also validated based on the measured dose rate values with Radiation Survey Meter (G-M Counter) considering the ICRP-60 (1990) recommendations for occupational dose rate limit (10 μSv/hr). The recommended shield design parameters are: (i) thickness of 114.3 cm Ilmenite-Magnetite Concrete (IMC) or 129.54 cm Ordinary Reinforced Concrete (ORC) for concrete wall A (ii) thickness of 66.04 cm Ilmenite-Magnetite Concrete (IMC) or 78.74 cm Ordinary Reinforced Concrete (ORC) for concrete wall B and (iii) door thickness of 3.175 cm Mild Steel (MS) on the entrance of decay tank room. In shielding efficiency analysis, the use of I-M concrete in the design of this concrete wall shows that it reduced the dose rate by a factor of at least 3.52 times approximately compared to ordinary reinforced concrete

  18. Evaluation of the shielding of a room for radiodiagnostic

    International Nuclear Information System (INIS)

    Padilla R, Z. P.; Acuna D, E.; Escareno J, E.; Vega C, H. R.

    2011-10-01

    The X-ray discovery by Roentgen in 1895 and its application in diagnosis was a breakthrough in medicine. Worldwide, X-ray technique is one of the most widely used procedures in medical diagnosis. At the Mental Health Hospital of Calera Zacatecas a room has been designed as radiology room, however there is not a record of shielding characteristics. In order to determine the features of X-ray equipment that the room can host, in this work a series of calculations were carried out. Calculations were based upon the NCRP 151 recommendations and fulfilling the requirements given in the Mexican standard NOM-229-SSA1-2002. From the actual room conditions this can host a X-ray equipment without fluoroscopy, with a workload of 80 ma-min/week, with 125 k Vp as maximum operating voltage. From the actual conditions a set of recommendations, for better protection of radiation workers and public are also given. (Author)

  19. Magnetic leakage shield of septum magnet for SPring-8 synchrotron

    International Nuclear Information System (INIS)

    Abe, Hiroshi; Aoki, Tsuyoshi; Fukami, Kenji

    1997-01-01

    This paper describes magnetic field measurements of the prototype septum magnet and countermeasure for reducing the leakage magnetic fields in the incidence and the extraction parts of the SPring-8 synchrotron. We studied and developed 'leakage magnetic shield' on the basis of the tests data got in these measurements. Consequentially, it succeeded in reducing effects of the leakage field to about 50% by installing the shield board in the magnet main body. Then, it was possible to manufacture the magnet which sufficiently held the effect of the leakage field for the electron and positron beam. In this examination, we confirmed the reproduction with the magnetic field distribution of the magnet measured in the manufacturer. We developed and produced of the septum magnets which were carried out determination of the shapes of the magnetic shielding. (author)

  20. Superconductor shields test chamber from ambient magnetic fields

    Science.gov (United States)

    Hildebrandt, A. F.

    1965-01-01

    Shielding a test chamber for magnetic components enables it to maintain a constant, low magnetic field. The chamber is shielded from ambient magnetic fields by a lead foil cylinder maintained in a superconducting state by liquid helium.

  1. Measurement accuracy in shielded magnetic fields

    International Nuclear Information System (INIS)

    Bottauscio, Oriano; Chiampi, Mario; Crotti, Gabriella; Zucca, Mauro

    2005-01-01

    The measurement error due to both the probe size averaging effect and the coil arrangement is investigated when magnetic field measurements are performed in close proximity to different planar shields. The analysis is carried on through a hybrid FEM/BEM model which employs the 'thin shield' technique. Ferromagnetic, pure conductive and multilayer screens are taken into consideration and an estimation of the errors for concentric and non-concentric coil probes is given. The numerical results are validated by experiments

  2. DEVELOPMENT OF EXTREMELY LOW FREQUENCY PASSIVE SHIELDING APPLICATION USING MAGNETIC AQUEOUS SUBSTRATE

    Directory of Open Access Journals (Sweden)

    NOOR ASHIKIN MOHD RASHID

    2016-04-01

    Full Text Available Public concerns on Extremely Low Frequency (ELF Electromagnetic Field (EMF exposure have been elongated since the last few decades. Electrical substations and high tension rooms in commercial buildings were among the contributing factors emanating ELF magnetic fields. This paper discussed various shielding methods conventionally used in mitigating the ELF exposure. Nevertheless, the standard methods were found to be impractical and incapable of meeting currents shielding demands. In response to that, remarkable researches were conducted in effort to invent novel methods which is more convenient and efficient such as magnetic aqueous shielding or paint, textiles and papers shielding. A magnetic aqueous substrate, Manganese Zinc Ferrite was used as shielding material. The magnetic field and flux distribution inside the aqueous magnetic material are evaluated to optimize shielding against ELFEMF exposure, as to mitigate its exposure.

  3. Superconducting magnetic shielding apparatus and method

    Science.gov (United States)

    Clem, John R.; Clem, John R.

    1983-01-01

    Disclosed is a method and apparatus for providing magnetic shielding around a working volume. The apparatus includes a hollow elongated superconducting shell or cylinder having an elongated low magnetic pinning central portion, and two high magnetic pinning end regions. Transition portions of varying magnetic pinning properties are interposed between the central and end portions. The apparatus further includes a solenoid substantially coextensive with and overlying the superconducting cylinder, so as to be magnetically coupled therewith. The method includes the steps passing a longitudinally directed current through the superconducting cylinder so as to depin magnetic reservoirs trapped in the cylinder. Next, a circumferentially directed current is passed through the cylinder, while a longitudinally directed current is maintained. Depinned magnetic reservoirs are moved to the end portions of the cylinder, where they are trapped.

  4. Superconducting magnetic shielding apparatus and method

    Science.gov (United States)

    Clem, J.R.

    1982-07-09

    Disclosed is a method and apparatus for providing magnetic shielding around a working volume. The apparatus includes a hollow elongated superconducting shell or cylinder having an elongated low magnetic pinning central portion, and two high magnetic pinning end regions. Transition portions of varying magnetic pinning properties are interposed between the central and end portions. The apparatus further includes a solenoid substantially coextensive with and overlying the superconducting cylinder, so as to be magnetically coupled therewith. The method includes the steps passing a longitudinally directed current through the superconducting cylinder so as to depin magnetic reservoirs trapped in the cylinder. Next, a circumferentially directed current is passed through the cylinder, while a longitudinally directed current is maintained. Depinned magnetic reservoirs are moved to the end portions of the cylinder, where they are trapped.

  5. Superconducting magnetic shields for neutral beam injectors. Final report

    International Nuclear Information System (INIS)

    1985-04-01

    Large high energy deuterium neutral beams which must be made from negative ions require extensive magnetic shielding against the intense fringe fields surrounding a magnetic fusion power plant. The feasibility of shielding by multilayer sheets of copper-superconducting laminated material was investigated. It was found that, if necessary fabrication techniques are developed, intrinsically stable type II superconductors will be able to shield against the magnetic fields of the fusion reactors. Among the immediate benefits of this research is better magnetic shields for neutral beam injectors in support of DOE's fusion program. Another application may be in the space vehicles, where difficulties in transporting heavy μ-metal sections may make a comparatively light superconducting shield attractive. Also, as high-field superconducting magnets find widespread applications, the need for high-intensity magnetic shielding will increase. As a result, the commercial market for the magnetic shields should expand along with the market for superconducting magnets

  6. Passive magnetic shielding in MRI-Linac systems

    Science.gov (United States)

    Whelan, Brendan; Kolling, Stefan; Oborn, Brad M.; Keall, Paul

    2018-04-01

    Passive magnetic shielding refers to the use of ferromagnetic materials to redirect magnetic field lines away from vulnerable regions. An application of particular interest to the medical physics community is shielding in MRI systems, especially integrated MRI-linear accelerator (MRI-Linac) systems. In these systems, the goal is not only to minimize the magnetic field in some volume, but also to minimize the impact of the shield on the magnetic fields within the imaging volume of the MRI scanner. In this work, finite element modelling was used to assess the shielding of a side coupled 6 MV linac and resultant heterogeneity induced within the 30 cm diameter of spherical volume (DSV) of a novel 1 Tesla split bore MRI magnet. A number of different shield parameters were investigated; distance between shield and magnet, shield shape, shield thickness, shield length, openings in the shield, number of concentric layers, spacing between each layer, and shield material. Both the in-line and perpendicular MRI-Linac configurations were studied. By modifying the shield shape around the linac from the starting design of an open ended cylinder, the shielding effect was boosted by approximately 70% whilst the impact on the magnet was simultaneously reduced by approximately 10%. Openings in the shield for the RF port and beam exit were substantial sources of field leakage; however it was demonstrated that shielding could be added around these openings to compensate for this leakage. Layering multiple concentric shield shells was highly effective in the perpendicular configuration, but less so for the in-line configuration. Cautious use of high permeability materials such as Mu-metal can greatly increase the shielding performance in some scenarios. In the perpendicular configuration, magnetic shielding was more effective and the impact on the magnet lower compared with the in-line configuration.

  7. Evaluation of the room shielding thickness of Hi-Art tomotherapy system

    International Nuclear Information System (INIS)

    Liu Haikuan; Wu Jinhai; Gu Naigu; Gao Yiming; Wang Li; Huang Weiqin; Wang Fengxian

    2010-01-01

    In this paper, we calculate and evaluate the room shielding thickness of a Hi-Art tomotherapy system, which is a new type of radiotherapy facility. Due to the self-shielding of the accelerator,only scattered beam and beam leakage were considered in calculating the room shielding thickness. The radiation field of the tomotherapy system was used as the basic data to calculate the shielding thickness of every 15 degree solid angle. The maximum shielding thickness required of each shielding wall was at the position with the angle of 15 degree, and the calculated shielding thickness were 1023, 975, 917, 1460, 1147 and 1189 mm for the east wall,south wall,west wall, north wall, the roof and the floor,respectively. According to the calculation results, all shielding walls, ceiling and floor could meet the requirement of the radiation protection, but the north wall thickness of 1200 mm was a little thinner. (authors)

  8. Magnetic shielding structure optimization design for wireless power transmission coil

    Science.gov (United States)

    Dai, Zhongyu; Wang, Junhua; Long, Mengjiao; Huang, Hong; Sun, Mingui

    2017-09-01

    In order to improve the performance of the wireless power transmission (WPT) system, a novel design scheme with magnetic shielding structure on the WPT coil is presented in this paper. This new type of shielding structure has great advantages on magnetic flux leakage reduction and magnetic field concentration. On the basis of theoretical calculation of coil magnetic flux linkage and characteristic analysis as well as practical application feasibility consideration, a complete magnetic shielding structure was designed and the whole design procedure was represented in detail. The simulation results show that the coil with the designed shielding structure has the maximum energy transmission efficiency. Compared with the traditional shielding structure, the weight of the new design is significantly decreased by about 41%. Finally, according to the designed shielding structure, the corresponding experiment platform is built to verify the correctness and superiority of the proposed scheme.

  9. Structural analysis of the Passive Magnetic Shield for the ITER Heating Neutral Beam Injector system

    Energy Technology Data Exchange (ETDEWEB)

    Cabrera, Santiago, E-mail: santiago.cabrera@ciemat.es [CIEMAT Laboratorio Nacional de Fusión, Avda. Complutense 40, 28040 Madrid (Spain); Rincón, Esther; Ahedo, Begoña; Alonso, Javier; Barrera, Germán; Ramos, Francisco; Ríos, Luis [CIEMAT Laboratorio Nacional de Fusión, Avda. Complutense 40, 28040 Madrid (Spain); El-Ouazzani, Anass; García, Pablo [ITER Organization, Route de Vinon-sur-Verdon – CS 90 046, 13067 St Paul Lez Durance Cedex (France); Agarici, Gilbert [Fusion for Energy, Josep Pla 2, Torres Diagonal Litoral B3 – 07/08, 08019 Barcelona (Spain)

    2015-10-15

    The ITER Passive Magnetic Shield (PMS) main function is to protect the Neutral Beam Injector (NBI) from the external magnetic field coming from the tokamak, and to shield the NB cell from the radiation coming from all activated components. The shielding from the external magnetic field is performed in association with the Active Compensation Cooled Correction Coils (ACCC). The Bushing and Transmission Line (TL) PMS also provides structural support for HV bushing, allowing its maintenance and providing air sealing function between NBI cell and High Voltage deck room. The paper summarizes the structural analyses performed in order to evaluate the mechanical behaviour of the HNB PMS under operation combined with seismic event. The RCC-MR Code is used to validate the design, assuming creep is negligible, since the structure is expected to be at room temperature. P-type damage is assessed.

  10. Structural shielding of medical X-ray rooms for diagnostic installations

    International Nuclear Information System (INIS)

    Rabitsch, H.

    1979-06-01

    In Part I (RIG 8), the various design procedures for shielding against X-rays are discussed and compared. In particular, this comparison is carried out between the shielding obtained conforming to the Austrian Regulations for Radiation Protection and that obtained from the DIN-standard DIN 6812; this latter includes the various operating conditions of diagnostic installations up to 150 kV. Several examples for particular structural shielding components in medical radiation rooms are given. (author)

  11. Shielding design for the target room of the proton accelerator research center

    International Nuclear Information System (INIS)

    Min, Y. S.; Lee, C. W.; Mun, K. J.; Nam, J.; Kim, J. Y.

    2010-01-01

    The Proton Engineering Frontier Project (PEFP) has been developing a 100-MeV proton linear accelerator. Also, PEFP has been designing the Proton Accelerator Research Center (PARC). In the Accelerator Tunnel and Beam Experiment Hall in PARC, 10 target rooms for the 20- and 100-MeV beamline facilities exist in the Beam Experiment Hall. For the 100-MeV target rooms during 100-MeV proton beam extraction, a number of high energy neutrons, ranging up to 100-MeV, are produced. Because of the high beam current and space limitations of each target room, the shielding design of each target room should be considered seriously. For the shielding design of the 100-MeV target rooms of the PEFP, a permanent and removable local shield structure was adopted. To optimize shielding performance, we evaluated four different shield materials (concrete, HDPE, lead, iron). From the shielding calculation results, we confirmed that the proposed shielding design made it possible to keep the dose rate below the 'as low as reasonably achievable (ALARA)' objective.

  12. Magnetic Materials Characterization and Modeling for the Enhanced Design of Magnetic Shielding of Cryomodules in Particle Accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Sah, Sanjay [Virginia Commonwealth Univ., Richmond, VA (United States)

    2016-05-31

    Particle accelerators produce beams of high-energy particles, which are used for both fundamental and applied scientific research and are critical to the development of accelerator driven sub-critical reactor systems. An effective magnetic shield is very important to achieve higher quality factor (Qo) of the cryomodule of a particle accelerator. The allowed value of field inside the cavity due to all external fields (particularly the Earth’s magnetic field) is ~15 mG or less. The goal of this PhD dissertation is to comprehensively study the magnetic properties of commonly used magnetic shielding materials at both cryogenic and room temperatures. This knowledge can be used for the enhanced design of magnetic shields of cryomodes (CM) in particle accelerators. To this end, we first studied the temperature dependent magnetization behavior (M-H curves) of Amumetal and A4K under different annealing and deformation conditions. This characterized the effect of stress or deformation induced during the manufacturing processes and subsequent restoration of high permeability with appropriate heat treatment. Next, an energy based stochastic model for temperature dependent anhysteretic magnetization behavior of ferromagnetic materials was proposed and benchmarked against experimental data. We show that this model is able to simulate and explain the magnetic behavior of as rolled, deformed and annealed amumetal and A4K over a large range of temperatures. The experimental results for permeability are then used in a finite element model (FEM) in COMSOL to evaluate the shielding effectiveness of multiple shield designs at room temperature as well as cryogenic temperature. This work could serve as a guideline for future design, development and fabrication of magnetic shields of CMs.

  13. Pre-installation empirical testing of room shielding for high dose rate remote afterloaders

    International Nuclear Information System (INIS)

    Klein, E.E.; Grigsby, P.W.; Williamson, J.F.; Meigooni, A.S.

    1993-01-01

    PURPOSE: Many facilities are acquiring high dose rate remote afterloading units. It is economical that these units be placed in existing shielded teletherapy rooms. Scatter-radiation barriers marginally protect uncontrolled areas from a high dose rate source especially in a room that houses a non-dynamic Cobalt-60 unit. In addition the exact thickness and material composition of the barriers are unknown and therefore, a calculation technique may give misleading results. Also, it would be impossible to evaluate an entire wall barrier by taking isolated core samples in order to assist in the calculations. A quick and inexpensive measurement of dose equivalent using a rented high activity 192Ir source evaluates the barriers and locates shielding deficiencies. METHODS AND MATERIALS: We performed transmission calculations for primary and scattered radiation based on National Council on Radiation Protection and Measurements Reports 49 and 51, respectively. We then rented a high activity 21.7 Ci (8.03 x 10(11) Bq) Ir-192 source to assess our existing teletherapy room shielding for adequacy and voids. This source was placed at the proposed location for clinical high dose rate treatment and measurements were performed. RESULTS: No deficiencies were found in controlled areas surrounding the room, but large differences were found between the calculated and measured values. Our survey located a region in the uncontrolled area above the room requiring augmented shielding which was not predicted by the calculations. A canopy shield was designed to potentially augment the shielding in the ceiling direction. CONCLUSION: Pre-installation testing by measurement is an invaluable method for locating shielding deficiencies and avoiding unnecessary enhancement of shielding particularly when there is lack of information of the inherent shielding

  14. A versatile program for the calculation of linear accelerator room shielding.

    Science.gov (United States)

    Hassan, Zeinab El-Taher; Farag, Nehad M; Elshemey, Wael M

    2018-03-22

    This work aims at designing a computer program to calculate the necessary amount of shielding for a given or proposed linear accelerator room design in radiotherapy. The program (Shield Calculation in Radiotherapy, SCR) has been developed using Microsoft Visual Basic. It applies the treatment room shielding calculations of NCRP report no. 151 to calculate proper shielding thicknesses for a given linear accelerator treatment room design. The program is composed of six main user-friendly interfaces. The first enables the user to upload their choice of treatment room design and to measure the distances required for shielding calculations. The second interface enables the user to calculate the primary barrier thickness in case of three-dimensional conventional radiotherapy (3D-CRT), intensity modulated radiotherapy (IMRT) and total body irradiation (TBI). The third interface calculates the required secondary barrier thickness due to both scattered and leakage radiation. The fourth and fifth interfaces provide a means to calculate the photon dose equivalent for low and high energy radiation, respectively, in door and maze areas. The sixth interface enables the user to calculate the skyshine radiation for photons and neutrons. The SCR program has been successfully validated, precisely reproducing all of the calculated examples presented in NCRP report no. 151 in a simple and fast manner. Moreover, it easily performed the same calculations for a test design that was also calculated manually, and produced the same results. The program includes a new and important feature that is the ability to calculate required treatment room thickness in case of IMRT and TBI. It is characterised by simplicity, precision, data saving, printing and retrieval, in addition to providing a means for uploading and testing any proposed treatment room shielding design. The SCR program provides comprehensive, simple, fast and accurate room shielding calculations in radiotherapy.

  15. Evaluation of shielding capability of controlled area for CT examination room

    International Nuclear Information System (INIS)

    Suzuki, Shoichi; Asada, Yasuki; Nakai, Takayo; Takeuchi, Kichito; Kinoshita, Kazuo; Watanabe, Nobuyuki; Koga, Sukehiko

    2002-01-01

    With the revision of the law in April, 2001, the effective dose at the boundary of the controlled area was set at 1.3 mSv/3M. Whether the shielding capability of the CT room satisfied the provisions of the law or not was confirmed by actual measurements. Both thermo luminescence dosemeter (TLD) and electronic dosemeter were used to measure the radiation doses. The shielding capability of the gantry was studied both inside and outside the room for a week as a basic experiment. On the basis of the data thus obtained doses accumulated in 3 months were estimated. According to the results of 3 month-measurement, the doses outside the wall of the CT room were about 200μ Sv. This numerical value was comparable to the background level of the evaluation point. The results above assured that the shielding capability of the CT room satisfied the provisions of the law well. (author)

  16. Magnetic field shielding effect for CFETR TF coil-case

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Weiwei; Liu, Xufeng, E-mail: Lxf@ipp.ac.cn; Du, Shuangsong; Zheng, Jinxing

    2017-05-15

    Highlights: • The eddy current of CFETR vacuum vessel can be calculated by using a series of ideal current loops. • The shielding effect with different eddy current is studied by decomposing the exciting magnetic field as two orthogonal components. • The shielding effect can be determined from the rate of eddy current magnetic field to the external magnetic field. - Abstract: The operation of superconducting magnet for fusion device is under the complex magnetic field condition, which affect the stabilization of superconductor. The coil-case of TF coil can shield the magnetic field to some extent. The shielding effect is related to the eddy current of coil-case. The shielding effect with different eddy current is studied by decomposing the exciting magnetic field as two orthogonal components, respectively. The results indicate that the shielding effect of CFETR TF coil-case has obvious different with the different directional magnetic field, and it’s larger for tangential magnetic compared with that for normal field.

  17. Effect of Anode Magnetic Shield on Magnetic Field and Ion Beam in Cylindrical Hall Thruster

    International Nuclear Information System (INIS)

    Zhao Jie; Wang Shiqing; Liu Jian; Xu Li; Tang Deli; Geng Shaofei

    2010-01-01

    Numerical simulation of the effect of the anode magnetic shielding on the magnetic field and ion beam in a cylindrical Hall thruster is presented. The results show that after the anode is shielded by the magnetic shield, the magnetic field lines near the anode surface are obviously convex curved, the ratio of the magnetic mirror is enhanced, the width of the positive magnetic field gradient becomes larger than that without the anode magnetic shielding, the radial magnetic field component is enhanced, and the discharge plasma turbulence is reduced as a result of keeping the original saddle field profile and the important role the other two saddle field profiles play in restricting electrons. The results of the particle in cell (PIC) numerical simulation show that both the ion number and the energy of the ion beam increase after the anode is shielded by the magnetic shield. In other words, the specific impulse of the cylindrical Hall thruster is enhanced.

  18. Helical tomotherapy shielding calculation for an existing LINAC treatment room: sample calculation and cautions

    International Nuclear Information System (INIS)

    Wu Chuan; Guo Fanqing; Purdy, James A

    2006-01-01

    This paper reports a step-by-step shielding calculation recipe for a helical tomotherapy unit (TomoTherapy Inc., Madison, WI, USA), recently installed in an existing Varian 600C treatment room. Both primary and secondary radiations (leakage and scatter) are explicitly considered. A typical patient load is assumed. Use factor is calculated based on an analytical formula derived from the tomotherapy rotational beam delivery geometry. Leakage and scatter are included in the calculation based on corresponding measurement data as documented by TomoTherapy Inc. Our calculation result shows that, except for a small area by the therapists' console, most of the existing Varian 600C shielding is sufficient for the new tomotherapy unit. This work cautions other institutions facing the similar situation, where an HT unit is considered for an existing LINAC treatment room, more secondary shielding might be considered at some locations, due to the significantly increased secondary shielding requirement by HT. (note)

  19. Solvent effects on the magnetic shielding of tertiary butyl alcohol

    African Journals Online (AJOL)

    )4 and tetramethyl ammonium cation N(CH3)4(+) have also been presented. KEY WORDS: Solvent effects, Magnetic shielding, Tertiary butyl alcohol, Tertiary butyl amine, Continuum solvation calculations, Chemical shift estimation methods

  20. Magnetic shielding tests for MFTF-B neutral beamlines

    International Nuclear Information System (INIS)

    Kerns, J.; Fabyan, J.; Wood, R.; Koger, P.

    1983-01-01

    A test program to determine the effectiveness of various magnetic shielding designs for MFTF-B beamlines was established at Lawrence Livermore National Laboratory (LLNL). The proposed one-tenth-scale shielding-design models were tested in a uniform field produced by a Helmholtz coil pair. A similar technique was used for the MFTF source-injector assemblies, and the model test results were confirmed during the Technology Demonstration in 1982. The results of these tests on shielding designs for MFTF-B had an impact on the beamline design for MFTF-B. The iron-core magnet and finger assembly originally proposed were replaced by a simple, air-core, race-track-coil, bending magnet. Only the source injector needs to be magnetically shielded from the fields of approximately 400 gauss

  1. Spectroscopic Study of Radiation around the Leksell Gamma Knife for Room Shielding Applications

    OpenAIRE

    Hubert, Alexis

    2017-01-01

    Any center planning to install a Gamma Knife radiosurgery unit has to provide for an efficient shielding of the treatment room, to protect the patient, the staff and the public, against undesired radiation. The shielding barrier design is controlled by national and international recommendations; the reference documents for gamma ray radiotherapy facilities are the National Council on Radiation Protection and Measurements (NCRP) reports 49 and 151. However, some facts highlighted in this thesi...

  2. Materials for room temperature magnetic refrigeration

    Energy Technology Data Exchange (ETDEWEB)

    Rosendahl Hansen, B.

    2010-07-15

    Magnetic refrigeration is a cooling method, which holds the promise of being cleaner and more efficient than conventional vapor-compression cooling. Much research has been done during the last two decades on various magnetic materials for this purpose and today a number of materials are considered candidates as they fulfill many of the requirements for a magnetic refrigerant. However, no one material stands out and the field is still active with improving the known materials and in the search for a better one. Magnetic cooling is based on the magnetocaloric effect, which causes a magnetic material to change its temperature when a magnetic field is applied or removed. For room temperature cooling, one utilizes that the magnetocaloric effect peaks near magnetic phase transitions and so the materials of interest all have a critical temperature within the range of 250 - 310 K. A magnetic refrigerant should fulfill a number of criteria, among these a large magnetic entropy change, a large adiabatic temperature change, preferably little to no thermal or magnetic hysteresis and the material should have the stability required for long term use. As the temperature range required for room temperature cooling is some 40 - 50 K, the magnetic refrigerant should also be able to cover this temperature span either by exhibiting a very broad peak in magnetocaloric effect or by providing the opportunity for creating a materials series with varying transition temperatures. (Author)

  3. Materials for Room Temperature Magnetic Refrigeration

    DEFF Research Database (Denmark)

    Hansen, Britt Rosendahl

    Magnetic refrigeration is a cooling method, which holds the promise of being cleaner and more efficient than conventional vapor-compression cooling. Much research has been done during the last two decades on various magnetic materials for this purpose and today a number of materials are considered...... candidates as they fulfill many of the requirements for a magnetic refrigerant. However, no one material stands out and the field is still active with improving the known materials and in the search for a better one. Magnetic cooling is based on the magnetocaloric effect, which causes a magnetic material...... to change its temperature when a magnetic field is applied or removed. For room temperature cooling, one utilizes that the magnetocaloric effect peaks near magnetic phase transitions and so the materials of interest all have a critical temperature within the range of 250 – 310 K. A magnetic refrigerant...

  4. Upgrade of the LHC magnet interconnections thermal shielding

    Science.gov (United States)

    Musso, Andrea; Barlow, Graeme; Bastard, Alain; Charrondiere, Maryline; Chrul, Anna; Damianoglou, Dimitrios; Deferne, Guy; Dib, Gaëlle; Duret, Max; Guinchard, Michael; Prin, Hervé; Strychalski, Michał; Craen, Arnaud Vande; Villiger, Gilles; Wright, Loren

    2014-01-01

    The about 1700 interconnections (ICs) between the Large Hadron Collider (LHC) superconducting magnets include thermal shielding at 50-75 K, providing continuity to the thermal shielding of the magnet cryostats to reduce the overall radiation heat loads to the 1.9 K helium bath of the magnets. The IC shield, made of aluminum, is conduction-cooled via a welded bridge to the thermal shield of the adjacent magnets which is actively cooled. TIG welding of these bridges made in the LHC tunnel at installation of the magnets induced a considerable risk of fire hazard due to the proximity of the multi-layer insulation of the magnet shields. A fire incident occurred in one of the machine sectors during machine installation, but fortunately with limited consequences thanks to prompt intervention of the operators. LHC is now undergoing a 2 years technical stop during which all magnet's ICs will have to be opened to consolidate the magnet electrical connections. The IC thermal shields will therefore have to be removed and re-installed after the work is completed. In order to eliminate the risk of fire hazard when re-welding, it has been decided to review the design of the IC shields, by replacing the welded bridges with a mechanical clamping which also preserves its thermal function. An additional advantage of this new solution is the ease in dismantling for maintenance, and eliminating weld-grinding operations at removal needing radioprotection measures because of material activation after long-term operation of the LHC. This paper describes the new design of the IC shields and in particular the theoretical and experimental validation of its thermal performance. Furthermore a status report of the on-going upgrade work in the LHC is given.

  5. Upgrade of the LHC magnet interconnections thermal shielding

    Energy Technology Data Exchange (ETDEWEB)

    Musso, Andrea; Barlow, Graeme; Bastard, Alain; Charrondiere, Maryline; Deferne, Guy; Dib, Gaëlle; Duret, Max; Guinchard, Michael; Prin, Hervé; Craen, Arnaud Vande; Villiger, Gilles [CERN European Organization for Nuclear Research, Meyrin 1211, Geneva 23, CH (Switzerland); Chrul, Anna [The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, ul.Radzikowskiego 152, 31-324 Krakow (Poland); Damianoglou, Dimitrios [NTUA National Technical University of Athens, Heeron Polytechniou 9, 15780 Zografou (Greece); Strychalski, Michał [Wroclaw University of Technology, Faculty of Mechanical and Power Engineering, Wyb. Wyspianskiego 27, Wroclaw, 50-370 (Poland); Wright, Loren [Lancaster University, Bailrigg, Lancaster, LA1 4YW (United Kingdom)

    2014-01-29

    The about 1700 interconnections (ICs) between the Large Hadron Collider (LHC) superconducting magnets include thermal shielding at 50-75 K, providing continuity to the thermal shielding of the magnet cryostats to reduce the overall radiation heat loads to the 1.9 K helium bath of the magnets. The IC shield, made of aluminum, is conduction-cooled via a welded bridge to the thermal shield of the adjacent magnets which is actively cooled. TIG welding of these bridges made in the LHC tunnel at installation of the magnets induced a considerable risk of fire hazard due to the proximity of the multi-layer insulation of the magnet shields. A fire incident occurred in one of the machine sectors during machine installation, but fortunately with limited consequences thanks to prompt intervention of the operators. LHC is now undergoing a 2 years technical stop during which all magnet's ICs will have to be opened to consolidate the magnet electrical connections. The IC thermal shields will therefore have to be removed and re-installed after the work is completed. In order to eliminate the risk of fire hazard when re-welding, it has been decided to review the design of the IC shields, by replacing the welded bridges with a mechanical clamping which also preserves its thermal function. An additional advantage of this new solution is the ease in dismantling for maintenance, and eliminating weld-grinding operations at removal needing radioprotection measures because of material activation after long-term operation of the LHC. This paper describes the new design of the IC shields and in particular the theoretical and experimental validation of its thermal performance. Furthermore a status report of the on-going upgrade work in the LHC is given.

  6. Shielding design for testing room of large container scanner

    International Nuclear Information System (INIS)

    Liu Yisi; Miao Qitian; Zhou Liye

    1997-01-01

    Testing facility for large container scanner is a most advanced anti-smuggle tool. The X-ray scanning principle is adopted in this system. The X-ray was collimated a ted as a fan-shape beam. The accelerator only supplies the ray beam when the container is scanned. The irradiation time is less than one minute per test. The X-ray burst irradiation and highly collimated a ted scanning beam of this system is different from the common industrial irradiation accelerator. The shielding design of the 1:1 large container scanner introduced has better collimation level because of tri-collimation. The irradiation dose is less than 150 μGy per test, which is obviously lower than importations

  7. A history of radiation shielding of x-ray therapy rooms

    International Nuclear Information System (INIS)

    McGinley, P.H.; Miner, M.S.

    1996-01-01

    In this report the history of shielding for radiation treatment rooms is traced from the time of the discovery of x rays to the present. During the early part of the twentieth century the hazards from ionizing radiation were recognized and the use of lead and other materials became common place for shielding against x rays. Techniques for the calculation of the shield thickness needed for x ray protection were developed in the 1920's, and shielding materials were characterized in terms of the half value layer or simple exponential factors. At the same time, better knowledge of the interaction between radiation and matter was acquired. With the development of high energy medical accelerators after 1940, new and more complex shielding problems had to be addressed. Recently, shielding requirements have become more stringent as standards for exposure of personnel and the general public have been reduced. The art of shielding of radiation treatment facilities is still being developed, and the need for a revision of the reports on shielding of medical accelerators from the National Council on Radiation Protection and Measurements is emphasized in this article. (author). 61 Refs., 3 Tabs

  8. Finite perturbation studies of magnetic susceptibility and shielding with GIAO

    International Nuclear Information System (INIS)

    Zaucer, M.; Pumpernik, D.; Hladnik, M.; Azman, A.

    1977-01-01

    The magnetic susceptibility tensor and proton and fluorine magnetic shielding tensors are calculated for F 2 and (FHF) - using an ab initio finite perturbation method with gauge-invariant atomic orbitals (GIAO). The discussion of the basis set deficiency shows that the calculated values for the susceptibilities are reliable. Simple additivity (Pascal rule) for the susceptibility is confirmed. (orig.) [de

  9. Method for calculating required shielding in medical x-ray rooms

    International Nuclear Information System (INIS)

    Karppinen, J.

    1997-10-01

    The new annual radiation dose limits - 20 mSv (previously 50 mSv) for radiation workers and 1 mSv (previously 5 mSv) for other persons - implies that the adequacy of existing radiation shielding must be re-evaluated. In principle, one could assume that the thicknesses of old radiation shields should be increased by about one or two half-value layers in order to comply with the new dose limits. However, the assumptions made in the earlier shielding calculations are highly conservative; the required shielding was often determined by applying the maximum high-voltage of the x-ray tube for the whole workload. A more realistic calculation shows that increased shielding is typically not necessary if more practical x-ray tube voltages are used in the evaluation. We have developed a PC-based calculation method for calculating the x-ray shielding which is more realistic than the highly conservative method formerly used. The method may be used to evaluate an existing shield for compliance with new regulations. As examples of these calculations, typical x-ray rooms are considered. The lead and concrete thickness requirements as a function of x-ray tube voltage and workload are also given in tables. (author)

  10. Comparative study between NCRP-49 and NCRP-147 methodologies for shielding calculus to fluoroscopy rooms

    International Nuclear Information System (INIS)

    Ferreira, Christiano Eduardo Martins

    2011-01-01

    The walls of a fluoroscopy room must be shielded to prevent unnecessary exposures to technicians and public individuals. Thus this dissertation aims to describe the methodologies contained in two documents which are references for the calculation of shielding those rooms. They are the National Council on Radiation Protection and Measurements Report No. 49 (NCRP Report No. 49) and No. 147 (NCRP Report No. 147), the latter being more recent publication. And based on such description was made a comparative study between the two methodologies, using for this, as a benchmark, spreadsheets computer program developed by Wolfram Mathematica 6. With that we could reach the final thickness of the barriers to a Standard Plan for a fluoroscopy room (provided by Siemens) and noted that the NCRP-49 presents a methodology with results more conservative. (author)

  11. A Designed Room Temperature Multilayered Magnetic Semiconductor

    Science.gov (United States)

    Bouma, Dinah Simone; Charilaou, Michalis; Bordel, Catherine; Duchin, Ryan; Barriga, Alexander; Farmer, Adam; Hellman, Frances; Materials Science Division, Lawrence Berkeley National Lab Team

    2015-03-01

    A room temperature magnetic semiconductor has been designed and fabricated by using an epitaxial antiferromagnet (NiO) grown in the (111) orientation, which gives surface uncompensated magnetism for an odd number of planes, layered with the lightly doped semiconductor Al-doped ZnO (AZO). Magnetization and Hall effect measurements of multilayers of NiO and AZO are presented for varying thickness of each. The magnetic properties vary as a function of the number of Ni planes in each NiO layer; an odd number of Ni planes yields on each NiO layer an uncompensated moment which is RKKY-coupled to the moments on adjacent NiO layers via the carriers in the AZO. This RKKY coupling oscillates with the AZO layer thickness, and it disappears entirely in samples where the AZO is replaced with undoped ZnO. The anomalous Hall effect data indicate that the carriers in the AZO are spin-polarized according to the direction of the applied field at both low temperature and room temperature. NiO/AZO multilayers are therefore a promising candidate for spintronic applications demanding a room-temperature semiconductor.

  12. Fe-based bulk metallic glasses used for magnetic shielding

    Energy Technology Data Exchange (ETDEWEB)

    Serban, Va; Codrean, C; UTu, D [Politehnica University of Timisoara, Depart for Materials Science and Welding, 1, M. Viteazu Bvd., 300222, Timisoara (Romania); ErcuTa, A, E-mail: serban@mec.upt.r [West University of Timisoara, Faculty of Physics, 4, Vasile Parvan Bdv., Timisoara 300223 (Romania)

    2009-01-01

    The casting in complex shapes (tubular) and the main magnetic properties of bulk metallic glasses (BMG) alloys from the ferromagnetic Fe-Cr-Ni-Ga-P-Si-C system, with a small addition of Ni (3%) were studied. Samples as rods and sockets having the thickness up to 1 mm were obtained from master alloys by melt injection by low cooling rates into a Cu mold and annealed in order to ensure adequate magnetic requirements. The structure was examined by X-ray diffraction (XRD) and the basic magnetic properties (coercivity, magnetic remanence, initial susceptibility, etc.) were determined by conventional low frequency induction method. The experimental investigations on producing of BMG ferromagnetic alloys with 3% Ni show the possibility to obtain magnetic shields of complex shape with satisfactory magnetic properties. The presence of Ni does not affect the glass forming ability, but reduce the shielding capacity.

  13. Radiation shielding design of BNCT treatment room for D-T neutron source.

    Science.gov (United States)

    Pouryavi, Mehdi; Farhad Masoudi, S; Rahmani, Faezeh

    2015-05-01

    Recent studies have shown that D-T neutron generator can be used as a proper neutron source for Boron Neutron Capture Therapy (BNCT) of deep-seated brain tumors. In this paper, radiation shielding calculations have been conducted based on the computational method for designing a BNCT treatment room for a recent proposed D-T neutron source. By using the MCNP-4C code, the geometry of the treatment room has been designed and optimized in such a way that the equivalent dose rate out of the treatment room to be less than 0.5μSv/h for uncontrolled areas. The treatment room contains walls, monitoring window, maze and entrance door. According to the radiation protection viewpoint, dose rate results of out of the proposed room showed that using D-T neutron source for BNCT is safe. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Superconducting and hybrid systems for magnetic field shielding

    International Nuclear Information System (INIS)

    Gozzelino, L; Gerbaldo, R; Ghigo, G; Laviano, F; Truccato, M; Agostino, A

    2016-01-01

    In this paper we investigate and compare the shielding properties of superconducting and hybrid superconducting/ferromagnetic systems, consisting of cylindrical cups with an aspect ratio of height/radius close to unity. First, we reproduced, by finite-element calculations, the induction magnetic field values measured along the symmetry axis in a superconducting (MgB 2 ) and in a hybrid configuration (MgB 2 /Fe) as a function of the applied magnetic field and of the position. The calculations are carried out using the vector potential formalism, taking into account simultaneously the non-linear properties of both the superconducting and the ferromagnetic material. On the basis of the good agreement between the experimental and the computed data we apply the same model to study the influence of the geometric parameters of the ferromagnetic cup as well as of the thickness of the lateral gap between the two cups on the shielding properties of the superconducting cup. The results show that in the considered non-ideal geometry, where the edge effect in the flux penetration cannot be disregarded, the superconducting shield is always the most efficient solution at low magnetic fields. However, a partial recovery of the shielding capability of the hybrid configuration occurs if a mismatch in the open edges of the two cups is considered. In contrast, at high magnetic fields the hybrid configurations are always the most effective. In particular, the highest shielding factor was found for solutions with the ferromagnetic cup protruding over the superconducting one. (paper)

  15. New possibility of magnetic ripple shielding for specific heat measurements in hybrid magnets

    NARCIS (Netherlands)

    Tarnawski, Z.; Meulen, der, H. van; Franse, J.J.M.; Kadowaki, K.; Veenhuizen, P.A.; Klaasse, J.

    1988-01-01

    A test of the new high Tc superconducting materials for magnetic ripple shielding has been carried out. It was found that magnetic ripples of 0.0009 T (peak-to-peak) in the frequency range below 20 kHz can be completely shielded in high static fields by a 2 mm thick Y-Ba-Cu-O screen.

  16. Active Magnetic Shielding with magneto-impedance sensor

    International Nuclear Information System (INIS)

    Okazaki, Yasuo; Yanase, Shunji; Sugimoto, Noriko

    2002-01-01

    Active shielding effect was examined in a negative feedback circuit system consisting of a magneto-impedance effective sensor, an amplifier and a canceling coil to compensate external magnetic field noise. The phase difference between the input and output sensor signals in a loop was less than 90 degree up to 20,000 Hz. An excellent frequency characteristic of active shielding effectiveness, 48 dB was obtained for the external magnetic field at the frequency of 0 - 2,000 Hz. (Author)

  17. Dynamic shielding of the magnetic fields

    Directory of Open Access Journals (Sweden)

    RAU, M.

    2010-11-01

    Full Text Available The paper presents a comparative study of the methods used to control and compensate the direct and alternative magnetic fields. Two frequently used methods in the electromagnetic compatibility of the complex biomagnetism installations were analyzed. The two methods refer to the use of inductive magnetic field sensors (only for alternative fields and of fluxgate magnetometers as active transducers which measures both the direct and alternative components of the magnetic field. The applications of the dynamic control of the magnetic field are: control of the magnetic field of the military ships, control of parasite magnetic field produced by power transformers and the electrical networks, protection of the mass spectrometers, electronic microscopes, SQUID and optical pumping magnetometers for applications in biomagnetism.

  18. Magnetic heat pumping near room temperature

    Science.gov (United States)

    Brown, G. V.

    1976-01-01

    It is shown that magnetic heat pumping can be made practical at room temperature by using a ferromagnetic material with a Curie point at or near operating temperature and an appropriate regenerative thermodynamic cycle. Measurements are performed which show that gadolinium is a resonable working material and it is found that the application of a 7-T magnetic field to gadolinium at the Curie point (293 K) causes a heat release of 4 kJ/kg under isothermal conditions or a temperature rise of 14 K under adiabatic conditions. A regeneration technique can be used to lift the load of the lattice and electronic heat capacities off the magnetic system in order to span a reasonable temperature difference and to pump as much entropy per cycle as possible

  19. Quality control, mean glandular dose estimate and room shielding calculation in mammography

    International Nuclear Information System (INIS)

    Rakotomalala, H.M.

    2014-01-01

    This study focuses in the importance of Radiation Protection in mammography. A good control of the radiological risk depends on the dose optimization, room shielding calculation and the quality of equipment. The work was carried out in the three private medical centers called A, B, and C. Dosimetry estimates were made on the equipment of the three centers. Values has been compared with the Diagnostic Reference Levels established by the International Atomic Energy Agency (IAEA). Conformity control of the radiological devices has also been done with the Mammographic Quality Control Kit of the INSTN-Madagascar. Verifications of shields of the room containing the mammography equipment were done by theoretical calculations using the method provided by NCRP 147. [fr

  20. Some folded issues related to over-shielded and unplanned rooms for medical linear accelerators - A case study

    Science.gov (United States)

    Muhammad, Wazir; Ullah, Asad; Hussain, Amjad; Ali, Nawab; Alam, Khan; Khan, Gulzar; Matiullah; Maeng, Seongjin; Lee, Sang Hoon

    2015-08-01

    A medical linear accelerator (LINAC) room must be properly shielded to limit the outside radiation exposure to an acceptable safe level defined by individual state and international regulations. However, along with this prime objective, some additional issues are also important. The current case-study was designed to unfold the issues related to over-shielded and unplanned treatment rooms for LINACs. In this connection, an apparently unplanned and over-shielded treatment room of 610 × 610 cm2 in size was compared with a properly designed treatment room of 762 × 762 cm2 in size ( i.e., by following the procedures and recommendations of the IAEA Safety Reports Series No. 47 and NCRP 151). Evaluation of the unplanned room indicated that it was over-shielded and that its size was not suitable for total body irradiation (TBI), although the license for such a treatment facility had been acquired for the installed machine. An overall 14.96% reduction in the total shielding volume ( i.e., concrete) for an optimally planned room as compared to a non-planned room was estimated. Furthermore, the inner room's dimensions were increased by 25%, in order to accommodate TBI patients. These results show that planning and design of the treatment rooms are imperative to avoid extra financial burden to the hospitals and to provide enough space for easy and safe handling of the patients. A spacious room is ideal for storing treatment accessories and facilitates TBI treatment.

  1. Shield requirement estimation for pin storage room in fuel fabrication plant

    International Nuclear Information System (INIS)

    Shanthi, M.M.; Keshavamurthy, R.S.; Sivashankaran, G.

    2012-01-01

    Fast Reactor Fuel Cycle Facility (FRFCF) is an upcoming project in Kalpakkam. It has the facility to recycle the fuel from PFBR. It is an integrated facility, consists of fuel reprocessing plant, fuel fabrication plant (FFP), core subassembly plant, Reprocessed Uranium plant (RUP) and waste management plant. The spent fuel from PFBR would be reprocessed in fuel reprocessing plant. The reprocessed fuel material would be sent to fuel fabrication plant. The main activity of fuel fabrication plant is the production of MOX fuel pins. The fuel fabrication plant has a fuel pin storage room. The shield requirement for the pin storage room has been estimated by Monte Carlo method. (author)

  2. Practical high-density shielding materials for medical linear accelerator rooms

    International Nuclear Information System (INIS)

    Barish, R.J.

    1990-01-01

    High-energy linear accelerators are replacing lower energy units in radiation therapy centers. Radiation protection requirements necessitate expensive reconstruction of existing treatment rooms to accommodate these new machines. We describe two shielding materials: one made by embedding small pieces of scrap steel in cement, and the other made with cast iron in cement. Both materials produce high-density barriers at low cost using standard construction methods

  3. Force measurements on a shielded coreless linear permanent magnet motor

    NARCIS (Netherlands)

    Pluk, K.J.W.; Jansen, J.W.; Lomonova, E.A.

    2014-01-01

    This paper compares force measurements on a shielded coreless linear permanent magnet motor with 2-D models. A 2-D semianalytical modeling method is applied, which is based on Fourier modeling and includes force calculations. The semianalytical modeling correctly predicts the behavior found in the

  4. Passive magnetic cylindrical shielding at gauss-range static fields

    International Nuclear Information System (INIS)

    Calvo, E.; Cerrada, M.; Gil-Botella, I.; Palomares, C.; Rodriguez, I.; Toral, F.; Verdugo, A.

    2009-01-01

    A study has been performed in order to find the optimal solution for the magnetic shielding of the 10 in. photomultipliers which will be used in the Double Chooz neutrino experiment under a very low magnetic field (less than 2 G). The results obtained with analytical and numerical calculations are compared with measurements made using test prototypes of several magnetic materials, with different dimensions and from different manufacturers. An exhaustive analysis of the magnetic materials was needed to understand the observed disagreement between calculations and test results obtained at low field values.

  5. Comparison between steel and lead shieldings for radiotherapy rooms regarding neutron doses to patients

    Energy Technology Data Exchange (ETDEWEB)

    Silva, M.G.; Rebello, W.F.; Andrade, E.R.; Medeiros, M.P.C.; Mendes, R.M.S.; Braga, K.L.; Gomes, R.G., E-mail: eng.cavaliere@gmail.com, E-mail: ggrprojetos@gmail.com [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil). Secao de Engenharia Nuclear; Silva, A.X., E-mail: ademir@con.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil)

    2015-07-01

    The NCRP Report No. 151, Structural Shielding Design and Evaluation for Megavoltage X- and Gamma-Ray Radiotherapy Facilities, considers, in shielding calculations for radiotherapy rooms, the use of lead and/or steel to be applied on bunker walls. The NCRP Report calculations were performed foreseeing a better protection of people outside the radiotherapy room. However, contribution of lead and steel to patient dose should be taken into account for radioprotection purposes. This work presents calculations performed by MCNPX code in analyzing the Ambient Dose Equivalent due to neutron, H *(10){sub n}, within a radiotherapy room, in the patients area, considering the use of additional shielding of 1 TVL of lead or 1 TVL of steel, positioned at the inner faces of walls and ceiling of a bunker. The head of the linear accelerator Varian 2100/2300 C/D was modeled working at 18MeV, with 5 x 5 cm{sup 2}, 10 x 10 cm{sup 2}, 20 x 20 cm{sup 2}, 30 x 30 cm{sup 2} and 40 x 40 cm{sup 2} openings for jaws and MLC and operating in eight gantry's angles. This study shows that the use of lead generates an average value of H *(10){sub n} at patients area, 8.02% higher than the expected when using steel. Further studies should be performed based on experimental data for comparison with those from MCNPX simulation. (author)

  6. Comparison between steel and lead shieldings for radiotherapy rooms regarding neutron doses to patients

    International Nuclear Information System (INIS)

    Silva, M.G.; Rebello, W.F.; Andrade, E.R.; Medeiros, M.P.C.; Mendes, R.M.S.; Braga, K.L.; Gomes, R.G.

    2015-01-01

    The NCRP Report No. 151, Structural Shielding Design and Evaluation for Megavoltage X- and Gamma-Ray Radiotherapy Facilities, considers, in shielding calculations for radiotherapy rooms, the use of lead and/or steel to be applied on bunker walls. The NCRP Report calculations were performed foreseeing a better protection of people outside the radiotherapy room. However, contribution of lead and steel to patient dose should be taken into account for radioprotection purposes. This work presents calculations performed by MCNPX code in analyzing the Ambient Dose Equivalent due to neutron, H *(10) n , within a radiotherapy room, in the patients area, considering the use of additional shielding of 1 TVL of lead or 1 TVL of steel, positioned at the inner faces of walls and ceiling of a bunker. The head of the linear accelerator Varian 2100/2300 C/D was modeled working at 18MeV, with 5 x 5 cm 2 , 10 x 10 cm 2 , 20 x 20 cm 2 , 30 x 30 cm 2 and 40 x 40 cm 2 openings for jaws and MLC and operating in eight gantry's angles. This study shows that the use of lead generates an average value of H *(10) n at patients area, 8.02% higher than the expected when using steel. Further studies should be performed based on experimental data for comparison with those from MCNPX simulation. (author)

  7. QED Theory of the Nuclear Magnetic Shielding in Hydrogenlike Ions

    International Nuclear Information System (INIS)

    Yerokhin, V. A.; Pachucki, K.; Harman, Z.; Keitel, C. H.

    2011-01-01

    The shielding of the nuclear magnetic moment by the bound electron in hydrogenlike ions is calculated ab initio with inclusion of relativistic, nuclear, and quantum electrodynamics (QED) effects. The QED correction is evaluated to all orders in the nuclear binding strength parameter and, independently, to the first order in the expansion in this parameter. The results obtained lay the basis for the high-precision determination of nuclear magnetic dipole moments from measurements of the g factor of hydrogenlike ions.

  8. Proposal of Magnetic Circuit using Magnetic Shielding with Bulk-Type High Tc Superconductors

    Science.gov (United States)

    Fukuoka, Katsuhiro; Hashimoto, Mitsuo; Tomita, Masaru; Murakami, Masato

    Recently, bulk-type high Tc superconductors having a characteristic of critical current density over 104 A/cm2 in liquid nitrogen temperature (77K) on 1T, can be produced. They are promising for many practical applications such as a magnetic bearing, a magnetic levitation, a flywheel, a magnetic shielding and others. In this research, we propose a magnetic circuit that is able to use for the magnetic shield of plural superconductors as an application of bulk-type high Tc superconductors. It is a closed magnetic circuit by means of a toroidal core. Characteristics of the magnetic circuit surrounded with superconductors are evaluated and the possibility is examined. As the magnetic circuit of the ferrite core is surrounded with superconductors, the magnetic flux is shielded even if it leaked from the ferrite core.

  9. Re-Shielding of Cobalt-60 Teletherapy Rooms for Tomotherapy and Conventional Linear Accelerators using Monte Carlo Simulations

    Science.gov (United States)

    Çeçen, Yiğit; Yazgan, Çağrı

    2017-09-01

    Purpose. Nearly all Cobalt-60 teletherapy machines were removed around the world during the last two decades. The remaining ones are being used for experimental purposes. However, the rooms of these teletherapy machines are valuable because of lack of space in radiotherapy clinics. In order to place a new technology treatment machine in one of these rooms, one should re-shield the room since it was designed only for 1.25 MeV gamma beams on average. Mostly, the vendor of the new machine constructs the new shielding of the room using their experience. However, every radiotherapy room has different surrounding work areas and it would be wise to shield the room considering these special conditions. Also, the shield design goal of the clinic may be much lower than the International Atomic Energy Agency (IAEA) or the local association accepts. The study shows re-shielding of a Cobalt-60 room, specific to the clinic, using Monte Carlo simulations. Materials & Methods: First, a 6 MV Tomotherapy machine, then a 10 MV conventional linear accelerator (LINAC) was placed inside the Cobalt-60 teletherapy room. The photon flux outside the room was simulated using Monte Carlo N-Particle (MCNP6.1) code before and after re-shielding. For the Tomotherapy simulation, flux distributions around the machine were obtained from the vendor and implemented as the source of the model. The LINAC model was more generic with the 10 MeV electron source, the tungsten target, first and secondary collimators. The aim of the model was to obtain the maximum (40x40 cm2) open field at the isocenter. Two different simulations were carried out for gantry angles 90o and 270o. The LINAC was placed in the room such that the primary walls were A' (Gantry 270o) and C' (Gantry 90o) (figure 1). The second part of the study was to model the re-shielding of the room for Tomotherapy and for the conventional LINAC, separately. The aim was to investigate the recommended shielding by the vendors. Left side of the room

  10. Shielding Design and Leaking Measurement for the High Energy Radiation Room

    International Nuclear Information System (INIS)

    Chu, Sung Sil

    1979-01-01

    An optimum shielding design and the computation of protective barriers for high energy radiation therapy room, Toshiba 13 MeV , are presented. We obtained following results by comparison between the p recalculating values and actual survey after complete installation of radio generating units. 1. The precalculating values of protective barrier are 5 times more protective than that of actual measurement. 2. The dose rate during exposure are 2-10 mR /hr at out of the door and the control room. 3. The exposure doses for occupationally persons are relatively low levels, the average values of exposure dose is 10-50 mR per month. 4. The foul smelling and ozone gas production from long exposure of cancer patients cannot be eliminated when the room is ill ventilated

  11. Magnetic shield of PMT used in DAMPE electromagnetic calorimeter

    CERN Document Server

    Wang, Peilong; Wang, Xiaolian; Xu, Zizong

    2014-01-01

    The magnetic characteristics of photomultiplier tube R5610A-01 are studied in this paper. The experimental data shows that the gain of R5610A-01 loses about 53% when the magnetic field is 3G along its +X axis. A cylinder of one-layer permalloy strip is able to reduce the effect of 3G magnetic field on the PMT's gain to less than 1%. A cylinder of two-layer permalloy is finally used to shield the PMT from the outside field.

  12. Protective shielding parameters of diagnostic x-ray rooms in some hospitals in Benue State

    International Nuclear Information System (INIS)

    Agba, E.H.; Gemanam, S.; Sombo, T.

    2011-01-01

    Protective shielding parameters of diagnostic x-ray units at Federal Medical Centre, Makurdi, Baki Hospital, Gboko and Mkar Christian Hospital, Gboko have been determined using a radiation meter, (Inspector, Exp.S.E). The parameters determined include: Operating potential, Workload and Use factors of each diagnostic x-ray room. These parameters were used to estimate the primary and secondary protective barriers for the hospitals. The primary and secondary protective barrier values at Mkar Christian Hospital, Baki Hospital, Gboko and Federal Medical Centre, Makurdi are found to be: 11.0±0.11 x10 -1 mm and 9.0±9x10 -2 mm; 6.0±6.0x10 -1 mm and 6.0±6.0x10 -2 mm; and 7.0±7.0x10 -1 mm and 6.0±6.0x10 -2 mm respectively. The wall thicknesses around the x-ray rooms of the respective hospitals are 300±3.0x1 0 -1 mm for Mkar Christian Hospital and Federal Medical Centre, Makurdi, while that of Baki Hospital, Gboko is 270±2.7x10 -1 mm. The measured wall thicknesses are seen to be adequate protective structural shields on the basis of International NCRP Standards on Structural Shielding.

  13. Analytical solution for shielding in teletherapy rooms with Co60 according to semiempirical equation of attenuation

    International Nuclear Information System (INIS)

    Saez, D.G.; Borroto, M.

    1996-01-01

    The paper presents the parameters for a semiempirical equation of an exponential-polynomial type for the description of the transmission data of the different qualities of the Co-60 radiation in finite means of concrete (2350 kg m -3 ) and lead. This equation and the expression obtained for the relationship of scatter-to-incident exposure, help in the development of a computerized analytical solution of the Simpkin's method for shielding calculations in Co-60 teletherapy rooms. The results were compared with the values offered in the NCRP-49 for the same conditions, obtaining an acceptable correlation. (authors). 8 refs., 2 tabs

  14. Test of magnetic shielding cases for a 3'' phototube attached to a lead glass counter

    International Nuclear Information System (INIS)

    Ogawa, K.; Sumiyoshi, T.; Takasaki, F.

    1985-09-01

    Effect of a magnetic shielding for a phototube of 3'' diameter attached to a lead glass counter has been studied using permalloy shielding cases with two kinds of shapes. Both cases show sufficient shielding effect with magnetic field up to around 30 gauss. (author)

  15. Evaluation of neutron doses beyond of primary shielding of rooms housing clinical linear accelerators

    International Nuclear Information System (INIS)

    Rezende, Gabriel Fonseca da Silva

    2011-01-01

    The growing need to build radiotherapy rooms in places with lack of available space leads to the necessity of unconventional solutions for the shielding projects. In most cases, adding metals to the primary barriers is the best way to shield the rooms properly. However, when photons with energies equal to or great than 10 MeV interact with nuclei of materials with high atomic number, neutrons are ejected and can result in a problem of radioprotection both inside and outside the room. Currently, the only empirical formula existing in the literature to assess the dose equivalent due to neutrons beyond the laminated barriers works only under very specific conditions, and a validation of this formula had not yet been done. In this work, the Monte Carlo code MCNPX was used to verify the validity of the above formula for cases of primary barriers containing lead or iron sheets in rooms that house linear accelerators with 10, 15 and 18 MV. Moreover, such a code was used to evaluate the coefficient of neutron production and tenth-value layer for neutrons in concrete, both parameters that directly influence the equation studied. The study results showed that over 90% of the values compared between the formula and the simulations present discrepancies above 100%, which led to conclude that the formula from the literature produces values that do not match the reality. In addition, there were inconsistencies in the parameters that make up the formula, leading to a need to review this formula in order to build a new model that will better represent the real case. (author)

  16. Reassessment of shielding calculations for a room housing a Cesium-137 irradiator

    International Nuclear Information System (INIS)

    Oliveira, Leticia S.; Barbosa, Rugles C.; Rezende, Ana C.B.

    2017-01-01

    This aim of this work is to reassess the shielding calculations for a room that houses an irradiator with cesium-137 ( 137 Cs) source with activity of 444GBq (12Ci). Shielding or barriers have the function of reducing the intensity of the radiation emitted by a radioactive source, are constituted by materials of high atomic number and guarantee the radiological protection in areas occupied by occupationally exposed individuals or by individuals of the public. The barriers located in the direction of the direct beam of radiation are called primary barriers and are thicker. Already the barriers that attenuate the radiation scattered by the radiated surface are called secondary barriers. In the new calculations, the thickness of the primary barrier was determined by model of the point nucleus model and for the secondary barriers, the differential albedo dose model was used. The results obtained show that all secondary barriers were constructed with overestimated thicknesses and that the radiological protection of individuals from the public and occupationally exposed individuals in the areas outside these barriers is guaranteed. The primary barrier was constructed with a thickness 8% smaller than the thickness obtained in the new calculations. In addition to shielding calculations, classification and signaling of adjacent areas were performed, including necessary emergency procedures. The necessary instrumentation for monitoring these areas was also determined. (author)

  17. Reassessment of shielding calculations for a room housing a Cesium-137 irradiator

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Leticia S.; Barbosa, Rugles C., E-mail: leticia.fmufg@gmail.com, E-mail: rbarbosa@cnen.gov.br [Centro Regional de Ciências Nucleares do Centro Oeste (CRCN-CO/CNEN-GO), Abadia de Goiás, GO (Brazil); Rezende, Ana C.B., E-mail: anacbrz@gmail.com [Universidade Federal de Goiás (UFG), Goiânia, GO (Brazil). Escola de Engenharia

    2017-07-01

    This aim of this work is to reassess the shielding calculations for a room that houses an irradiator with cesium-137 ({sup 137}Cs) source with activity of 444GBq (12Ci). Shielding or barriers have the function of reducing the intensity of the radiation emitted by a radioactive source, are constituted by materials of high atomic number and guarantee the radiological protection in areas occupied by occupationally exposed individuals or by individuals of the public. The barriers located in the direction of the direct beam of radiation are called primary barriers and are thicker. Already the barriers that attenuate the radiation scattered by the radiated surface are called secondary barriers. In the new calculations, the thickness of the primary barrier was determined by model of the point nucleus model and for the secondary barriers, the differential albedo dose model was used. The results obtained show that all secondary barriers were constructed with overestimated thicknesses and that the radiological protection of individuals from the public and occupationally exposed individuals in the areas outside these barriers is guaranteed. The primary barrier was constructed with a thickness 8% smaller than the thickness obtained in the new calculations. In addition to shielding calculations, classification and signaling of adjacent areas were performed, including necessary emergency procedures. The necessary instrumentation for monitoring these areas was also determined. (author)

  18. Structural considerations for the practical development of primary shielding of X-ray rooms of megavoltage

    International Nuclear Information System (INIS)

    Lava, Deise D.; Borges, Diogo da S.; Affonso, Renato R.W.; Moreira, Maria de L.; Guimaraes, Antonio C.F.

    2014-01-01

    Due to the necessity of the use of accelerators with voltages above 10 MV in medical facilities, becomes necessary to evaluate the efficiency of the thickness of shielding materials used in rooms that contain these devices. This work presents the development of an algorithm able to provide data in a practical way, regarding the thickness of materials that can be used for an effective shielding against primary beams from these equipment. The use of the computer language C ++ allowed developing a practical tool for determining the thickness of materials required to protect the public and Individuals Occupationally Exposed (IOEs) against major powers beams. Furthermore, it was considered by calculations Intensity Modulated Radiotherapy Technique (IMRT). The construction of this tool was based to ensure the dose limits established in the CNEN-NN-3.01. The dose limiting is done through the use of loops able to validate the efficiency of thickness determined by the algorithm itself, and ensure if the radiation dose exceeds the limits set by the standard, it will be the inclusion of sufficient Half-Reducer Layers in so that the dose is within the parameters established by the Brazilian National Nuclear Energy Commission (CNEN). The code validation is performed by comparing results obtained in the examples p recalculated in the NCRP Report-151 (Structural Shielding Design and Evaluation for megavoltage X and Gamma-Ray Radiotherapy Facilities) with the results generated by the code. The results are satisfactory and consistent with that report

  19. Magnetic shielding of an inhomogeneous magnetic field source by a bulk superconducting tube

    International Nuclear Information System (INIS)

    Hogan, K; Fagnard, J-F; Wéra, L; Vanderheyden, B; Vanderbemden, P

    2015-01-01

    Bulk type-II irreversible superconductors can act as excellent passive magnetic shields, with a strong attenuation of low frequency magnetic fields. Up to now, the performances of superconducting magnetic shields have mainly been studied in a homogenous magnetic field, considering only immunity problems, i.e. when the field is applied outside the tube and the inner field should ideally be zero. In this paper, we aim to investigate experimentally and numerically the magnetic response of a high-T c bulk superconducting hollow cylinder at 77 K in an emission problem, i.e. when subjected to the non-uniform magnetic field generated by a source coil placed inside the tube. A bespoke 3D mapping system coupled with a three-axis Hall probe is used to measure the magnetic flux density distribution outside the superconducting magnetic shield. A finite element model is developed to understand how the magnetic field penetrates into the superconductor and how the induced superconducting shielding currents flow inside the shield in the case where the emitting coil is placed coaxially inside the tube. The finite element modelling is found to be in excellent agreement with the experimental data. Results show that a concentration of the magnetic flux lines occurs between the emitting coil and the superconducting screen. This effect is observed both with the modelling and the experiment. In the case of a long tube, we show that the main features of the field penetration in the superconducting walls can be reproduced with a simple analytical 1D model. This model is used to estimate the maximum flux density of the emitting coil that can be shielded by the superconductor. (paper)

  20. Production of a datolite-based heavy concrete for shielding nuclear reactors and megavoltage radiotherapy rooms

    International Nuclear Information System (INIS)

    Mortazavi, S. M. J.; Mosleh-Shirazi, M.A.; Baradaran-Ghahfarokhi, M.; Siavashpour, Z.; Farshadi, A.; Ghafoori, M.; Shahvar, A.

    2010-01-01

    Biological shielding of nuclear reactors has always been a great concern and decreasing the complexity and expense of these installations is of great interest. In this study, we used datolite and galena minerals for production of a high performance heavy concrete. Materials and Methods: Datolite and galena minerals which can be found in many parts of Iran were used in the concrete mix design. To measure the gamma radiation attenuation of the Datolite and galena concrete samples, they were exposed to both narrow and wide beams of gamma rays emitted from a cobalt-60 radiotherapy unit. An Am-Be neutron source was used for assessing the shielding properties of the samples against neutrons. To test the compression strengths, both types of concrete mixes (Datolite and galena and ordinary concrete) were investigated. Results: The concrete samples had a density of 4420-4650 kg/m 3 compared to that of ordinary concrete (2300-2500 kg/m 3 ) or barite high density concrete (up to 3500 kg/m 3 ). The measured half value layer thickness of the Datolite and galena concrete samples for cobalt-60 gamma rays was much less than that of ordinary concrete (2.56 cm compared to 6.0 cm). Furthermore, the galena concrete samples had a significantly higher compressive strength as well as 20% more neutron absorption. Conclusion: The Datolite and galena concrete samples showed good shielding/engineering properties in comparison with other reported samples made, using high-density materials other than depleted uranium. It is also more economic than the high-density concretes. Datolite and galena concrete may be a suitable option for shielding nuclear reactors and megavoltage radiotherapy rooms.

  1. Anisotropic Pressure, Transport, and Shielding of Magnetic Perturbations

    International Nuclear Information System (INIS)

    Mynick, H.E.; Boozer, A.H.

    2008-01-01

    We compute the effect on a tokamak of applying a nonaxisymmetric magnetic perturbation (delta)B. An equilibrium with scalar pressure p yields zero net radial current, and therefore zero torque. Thus, the usual approach, which assumes scalar pressure, is not self-consistent, and masks the close connection which exists between that radial current and the in-surface currents, which provide shielding or amplification of (delta)B. Here, we analytically compute the pressure anisotropy, anisotropy, p # parallel#, p # perpendicular# and ≠ p, and from this, both the radial and in-surface currents. The surface-average of the radial current recovers earlier expressions for ripple transport, while the in-surface currents provide an expression for the amount of self-consistent shielding the plasma provides.

  2. Expression of the axial magnetic attenuation for a circularly cylindrical magnetic shield with partial openings

    CERN Document Server

    Chang, L H; Luo, G H; Lin, M C

    2002-01-01

    This paper presents a novel empirical formula for evaluating the axial magnetic attenuation of a circularly cylindrical shield with partial openings at both ends, which is derived under the assumption of scaling law with help of the 3-D magnetostatic code TOSCA for computing the magnetic attenuation of some canonical models. Our formula allows a quick evaluation of the magnetic shielding for design application to a superconducting radio-frequency cavity with less than 10% discrepancy in comparison with that obtained from pure numerical simulations.

  3. Method and Apparatus of Implementing a Magnetic Shield Flux Sweeper

    Science.gov (United States)

    Sadleir, John E. (Inventor)

    2018-01-01

    The present invention relates to a method and apparatus of protecting magnetically sensitive devices with a shield, including: a non-superconducting metal or lower transition temperature (T.sub.c) material compared to a higher transition temperature material, disposed in a magnetic field; means for creating a spatially varying order parameter's |.PSI.(r,T)|.sup.2 in a non-superconducting metal or a lower transition temperature material; wherein a spatially varying order parameter is created by a proximity effect, such that the non-superconducting metal or the lower transition temperature material becomes superconductive as a temperature is lowered, creating a flux-free Meissner state at a center thereof, in order to sweep magnetic flux lines to the periphery.

  4. On the Magnetic Shield for a Vlasov-Poisson Plasma

    Science.gov (United States)

    Caprino, Silvia; Cavallaro, Guido; Marchioro, Carlo

    2017-12-01

    We study the screening of a bounded body Γ against the effect of a wind of charged particles, by means of a shield produced by a magnetic field which becomes infinite on the border of Γ . The charged wind is modeled by a Vlasov-Poisson plasma, the bounded body by a torus, and the external magnetic field is taken close to the border of Γ . We study two models: a plasma composed by different species with positive or negative charges, and finite total mass of each species, and another made of many species of the same sign, each having infinite mass. We investigate the time evolution of both systems, showing in particular that the plasma particles cannot reach the body. Finally we discuss possible extensions to more general initial data. We show also that when the magnetic lines are straight lines, (that imposes an unbounded body), the previous results can be improved.

  5. Evaluation of the shield calculation adequacy of radiotherapy rooms through Monte Carlo Method and experimental measures

    International Nuclear Information System (INIS)

    Meireles, Ramiro Conceicao

    2016-01-01

    The shielding calculation methodology for radiotherapy services adopted in Brazil and in several countries is that described in publication 151 of the National Council on Radiation Protection and Measurements (NCRP 151). This methodology however, markedly employs several approaches that can impact both in the construction cost and in the radiological safety of the facility. Although this methodology is currently well established by the high level of use, some parameters employed in the calculation methodology did not undergo to a detailed assessment to evaluate the impact of the various approaches considered. In this work the MCNP5 Monte Carlo code was used with the purpose of evaluating the above mentioned approaches. TVLs values were obtained for photons in conventional concrete (2.35g / cm 3 ), considering the energies of 6, 10 and 25 MeV, respectively, first considering an isotropic radiation source impinging perpendicular to the barriers, and subsequently a lead head shielding emitting a shaped beam, in the format of a pyramid trunk. Primary barriers safety margins, taking in account the head shielding emitting photon beam pyramid-shaped in the energies of 6, 10, 15 and 18 MeV were assessed. A study was conducted considering the attenuation provided by the patient's body in the energies of 6,10, 15 and 18 MeV, leading to new attenuation factors. Experimental measurements were performed in a real radiotherapy room, in order to map the leakage radiation emitted by the accelerator head shielding and the results obtained were employed in the Monte Carlo simulation, as well as to validate the entire study. The study results indicate that the TVLs values provided by (NCRP, 2005) show discrepancies in comparison with the values obtained by simulation and that there may be some barriers that are calculated with insufficient thickness. Furthermore, the simulation results show that the additional safety margins considered when calculating the width of the primary

  6. Design and analysis of magnetic shield for 650 MHz SCRF cavity

    International Nuclear Information System (INIS)

    Thakur, Vanshree; Jain, Vikas; Das, S.; Shinde, R.S.; Joshi, S.C.

    2015-01-01

    Five-cell, 650 MHz Superconducting RF (SCRF) cavity is being developed at RRCAT for the Injector Linac of proposed ISNS project. The SCRF cavity needs to be shielded effectively from earth magnetic field. The external magnetic field can cause magnetic field trapping that limits the performance of SCRF cavity. The allowable limit of earth magnetic field in the cavity surface is < 10 mG. The magnetic shielding analysis carried out for 650 MHz dressed SCRF cavity is presented in this paper. For axial magnetic field shielding analysis, 2-D code PANDIRA has been used. A 2-D axisymmetric geometry (cylinder of Cryoperm10 sheet with 460 mm diameter of various thickness and 1100 mm length) has been modelled and analyzed in the presence of 240 mG external axial magnetic field. The influence of partial opening of 120 mm diameter at both ends of the cylinder on magnetic field pattern inside the shielded region has been evaluated. The transverse magnetic shielding analysis in the presence of 500 mG transverse external field has been carried out using OPERA 3D code. The flux leakage through the major openings for cavity supports, ports on the shield is investigated and accordingly the openings are designed to minimize the leakage. Inference of material thickness on the magnetic shielding for reducing magnetic field below specified limit has been investigated. Details of design and analysis of magnetic shield for SCRF cavity will be discussed in this paper. (author)

  7. Production of an economic high-density concrete for shielding megavoltage radiotherapy rooms and nuclear reactors

    International Nuclear Information System (INIS)

    Mortazavi, S. M. J.; Mosleh-Shirazi, M. A.; Maheri, M. R.; Haji-pour, A.; Yousefnia, H.; Zolghadri, S.

    2007-01-01

    In megavoltage radiotherapy rooms, ordinary concrete is usually used due to its low construction costs, although higher density concrete are sometimes used, as well. The use of high-density concrete decreases the required thickness of the concrete barrier; hence, its disadvantage is its high cost. In a nuclear reactor, neutron radiation is the most difficult to shield. A method for production of economic high-density concrete witt, appropriate engineering properties would be very useful. Materials and Methods: Galena (Pb S) mineral was used to produce of a high-density concrete. Galena can be found in many parts of Iran. Two types of concrete mixes were produced. The water-to-concrete (w/c) ratios of the reference and galena concrete mixes were 0.53 and 0.25, respectively. To measure the gamma radiation attenuation of Galena concrete samples, they were exposed to a narrow beam of gamma rays emitted from a cobalt-60 therapy unit. Results: The Galena mineral used in this study had a density of 7400 kg/m 3 . The concrete samples had a density of 4800 kg/m 3 . The measured half value layer thickness of the Galena concrete samples for cobalt 60 gamma rays was much less than that of ordinary concrete (2.6 cm compared to 6.0 cm). Furthermore, the galena concrete samples had significantly higher compressive strength (500 kg/cm 2 compared to 300 kg/cm 2 ). Conclusion: The Galena concrete samples made in our laboratories had showed good shielding/engineering properties in comparison with all samples made by using high-density materials other than depleted uranium. Based on the preliminary results, Galena concrete is maybe a suitable option where high-density concrete is required in megavoltage radiotherapy rooms as well as nuclear reactors

  8. Nuclear magnetic shielding tensors of 207Pb2+ in Pb(NO3)2

    International Nuclear Information System (INIS)

    Lutz, O.; Nolle, A.

    1980-01-01

    The NMR signals of 207 Pb were observed in a single crystal of Pb(NO 3 ) 2 and could be assigned to the four different Pb 2+ sites by the dependence of the linewidths on the orientation. Four different nuclear magnetic shielding tensors with equal principal values but with different characteristic vectors could be determined. The symmetry of the shielding tensors is in agreement with the symmetry at the Pb 2+ sites. It is shown, that intermolecular contributions can not account for the anisotropy of the nuclear magnetic shielding, which is 3 0 / 00 of the isotropic absolute magnetic shielding. (orig.)

  9. An optimizing design method for a compact iron shielded superconducting magnet for use in MRI

    International Nuclear Information System (INIS)

    Tang Xin; Zu Donglin; Wang Tao; Han Baohui

    2010-01-01

    A method is developed for designing a special iron shielded superconducting magnet for MRI in this paper. The shield is designed as an integral part of the cryostat and high permeability and high saturated magnetization iron material is adopted. This scheme will result in a compact iron shielded magnet. In the presented design, the finite element (FE) method is adopted to calculate the magnetic field produced by superconducting coils and nonlinear iron material. The FE method is incorporated into the simulated annealing method which is employed for corresponding optimization. Therefore, geometrical configurations of both coils and iron shield can be optimized together. This method can deal with discrete design variables which are defined to describe the cable arrangements of coil cross sections. A detailed algorithm of the present design is described and an example for designing a 1.5 T clinical iron shielded magnet for MRI is shown.

  10. Beam loss reduction by magnetic shielding using beam pipes and bellows of soft magnetic materials

    Science.gov (United States)

    Kamiya, J.; Ogiwara, N.; Hotchi, H.; Hayashi, N.; Kinsho, M.

    2014-11-01

    One of the main sources of beam loss in high power accelerators is unwanted stray magnetic fields from magnets near the beam line, which can distort the beam orbit. The most effective way to shield such magnetic fields is to perfectly surround the beam region without any gaps with a soft magnetic high permeability material. This leads to the manufacture of vacuum chambers (beam pipes and bellows) with soft magnetic materials. A Ni-Fe alloy (permalloy) was selected for the material of the pipe parts and outer bellows parts, while a ferritic stainless steel was selected for the flanges. An austenitic stainless steel, which is non-magnetic material, was used for the inner bellows for vacuum tightness. To achieve good magnetic shielding and vacuum performances, a heat treatment under high vacuum was applied during the manufacturing process of the vacuum chambers. Using this heat treatment, the ratio of the integrated magnetic flux density along the beam orbit between the inside and outside of the beam pipe and bellows became small enough to suppress beam orbit distortion. The outgassing rate of the materials with this heat treatment was reduced by one order magnitude compared to that without heat treatment. By installing the beam pipes and bellows of soft magnetic materials as part of the Japan Proton Accelerator Research Complex 3 GeV rapid cycling synchrotron beam line, the closed orbit distortion (COD) was reduced by more than 80%. In addition, a 95.5% beam survival ratio was achieved by this COD improvement.

  11. LOW-FREQUENCY MAGNETIC FIELD SHIELDING BY A CIRCULAR PASSIVE LOOP AND CLOSED SHELLS

    Directory of Open Access Journals (Sweden)

    V.S. Grinchenko

    2016-05-01

    Full Text Available Purpose. To analyze the shielding factors for a circular passive loop and conductive closed shells placed in a homogeneous low-frequency magnetic field. Methodology. We have obtained simplified expressions for the shielding factors for a circular passive loop and a thin spherical shell. In addition, we have developed the numerical model of a thin cubical shell in a magnetic field, which allows exploring its shielding characteristics. Results. We have obtained dependences of the shielding factors for passive loops and shells on the frequency of the external field. Analytically determined frequency of the external magnetic field, below which field shielding of a passive loop is expedient to use, above which it is advisable to use a shielding shell.

  12. If additional shielding required for the linear accelerator room when modern treatment techniques are intensively used

    International Nuclear Information System (INIS)

    Miller, Albert V.; Atkocius, Vydmantas; Aleknavicius, Eduardas

    2001-01-01

    Full text: Introduction - When the new linear accelerator is to be installed in radiotherapy department the responsible personnel should perform necessary estimations and calculations of the protective barriers for the accelerator treatment room. These methods are described in details in literature. However, if modern treatment techniques are planned to be intensively used on this machine, additional concern rises regarding adequacy of these calculations. The new Saturne-43 linear accelerator with three photon energies of 8, 15 and 25 MV recently installed at our department was, planned to be used for conventional treatment techniques as well as for conformal and total body treatments. The method of conformal therapy generally employs more small fields per one treated patient than conventional techniques. It leads to the use of more linear accelerator monitor units for the average treatment. It was estimated that 'beam on' time of an accelerator to deliver the same dose to the tumor is up to 3 times more than for conventional methods. The total body technique contribute to the extra time on of an accelerator because of extended distance to the dose prescription point. Altogether intensive clinical use of these modern techniques will noticeably increase 'beam on' time of an accelerator and rise question regarding validity of the traditionally calculated shielding of the treatment room. Materials and methods - IAEA-TECDOC-1040 and NCRP Report No 49 suggest considering three main components incident on the protective barriers: direct radiation, scatter radiation and leakage radiation. The formulas for these components are similar and dose equivalent limits are proportional to the workload. For the conventional treatments workloads of direct, scattered and leakage radiation are equal and calculated by the division of total prescribed dose (for all treated per week patients) to the machine isocenter to average tissue maximum ratio. These workloads for conformal and TBI

  13. A survey of Alberta physicians' use of and attitudes toward face masks and face shields in the operating room setting.

    Science.gov (United States)

    Davis, Philip J; Spady, Donald; Forgie, Sarah E D

    2007-09-01

    There is little evidence that surgical mask use by physicians in the operating room (OR) reduces surgical site infections (SSIs), but masks do protect the wearer from potentially infectious splashes. Face shields offer even more protection because they cover the eyes, but they may be perceived as offering less protection to the patient than do masks. The objectives of this study were to ascertain if there were predictors to determine which OR physicians are continuing to use masks and what their reasons are for doing so, and which OR physicians would accept face shields and their reasons for doing so. We surveyed the province of Alberta's surgeons, general practice (GP) surgeons, anesthesiologists, and GP anesthetists to determine how many physicians in the OR wear surgical masks, their reasons for wearing surgical masks (ethical, legal, protection of the patient, protection of the wearer), and if they believe that face shields offer more protection to the patient or to the wearer. We also sought to examine which demographic factors affected their responses. The data were examined with chi(2) analysis to assess the relationships of age and practitioner type, and for various outcome variables. A significance level of P masks; masks are worn to prevent the spread of disease, not because it is tradition to do so; masks protect the wearer more than do face shields; and wearing face shields alone will subject the patient to higher rates of SSIs. Surgeons are more likely than are anesthesiologists to wear surgical masks in the OR and wear a surgical mask and a face shield if the patient has risk factors for a blood borne infection. According to our survey, age and profession were the most important variables that affected the potential use of surgical masks and face shields. Younger OR physicians likely would be amenable to using face shields in addition to masks in the OR to protect themselves from exposure to blood or bodily fluids.

  14. Magnetic Shielding Design for Coupler of Wireless Electric Vehicle Charging Using Finite Element Analysis

    Science.gov (United States)

    Zhao, W. N.; Yang, X. J.; Yao, C.; Ma, D. G.; Tang, H. J.

    2017-10-01

    Inductive power transfer (IPT) is a practical and preferable method for wireless electric vehicle (EV) charging which proved to be safe, convenient and reliable. Due to the air gap between the magnetic coupler, the magnetic field coupling decreases and the magnetic leakage increases significantly compared to traditional transformer, and this may lead to the magnetic flux density around the coupler more than the safety limit for human. So magnetic shielding should be adding to the winding made from litz wire to enhance the magnetic field coupling effect in the working area and reduce magnetic field strength in non-working area. Magnetic shielding can be achieved by adding high-permeability material or high-conductivity material. For high-permeability material its magnetic reluctance is much lower than the surrounding air medium so most of the magnetic line goes through the high-permeability material rather than surrounding air. For high-conductivity material the eddy current in the material can produce reverse magnetic field to achieve magnetic shielding. This paper studies the effect of the two types of shielding material on coupler for wireless EV charging and designs combination shielding made from high-permeability material and high-conductivity material. The investigation of the paper is done with the help of finite element analysis.

  15. Feasibility of a superconducting FED with 50 cm of magnet shielding

    International Nuclear Information System (INIS)

    Schultz, J.H.; Montgomery, D.B.

    1981-01-01

    The feasibility of the suggestion that the cost of a Fusion Energy Device (FED) could be substantially reduced by operating with a reduced duty factor and only 50 cm of magnet shielding is evaluated here. This report examines the effect of light shielding on insulation life, matrix- and superconductor properties, refrigerator cost and steady-state heat removal. With very careful design, it appears feasible to build a device with only 50 cm of shielding

  16. Evaluation of the shielding of a room for radiodiagnostic; Evaluacion del blindaje de una sala para radiodiagnostico

    Energy Technology Data Exchange (ETDEWEB)

    Padilla R, Z. P. [Servicios de Salud de Zacatecas, Hospital de Especialidades en Salud Mental, Prolongacion 5 de mayo 1702-Sur, Parque Industrial, 98500 Calera de Victor Rosales, Zacatecas (Mexico); Acuna D, E.; Escareno J, E.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Calle Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)

    2011-10-15

    The X-ray discovery by Roentgen in 1895 and its application in diagnosis was a breakthrough in medicine. Worldwide, X-ray technique is one of the most widely used procedures in medical diagnosis. At the Mental Health Hospital of Calera Zacatecas a room has been designed as radiology room, however there is not a record of shielding characteristics. In order to determine the features of X-ray equipment that the room can host, in this work a series of calculations were carried out. Calculations were based upon the NCRP 151 recommendations and fulfilling the requirements given in the Mexican standard NOM-229-SSA1-2002. From the actual room conditions this can host a X-ray equipment without fluoroscopy, with a workload of 80 ma-min/week, with 125 k Vp as maximum operating voltage. From the actual conditions a set of recommendations, for better protection of radiation workers and public are also given. (Author)

  17. Cryogenic magnetic coil and superconducting magnetic shield for neutron electric dipole moment searches

    Science.gov (United States)

    Slutsky, S.; Swank, C. M.; Biswas, A.; Carr, R.; Escribano, J.; Filippone, B. W.; Griffith, W. C.; Mendenhall, M.; Nouri, N.; Osthelder, C.; Pérez Galván, A.; Picker, R.; Plaster, B.

    2017-08-01

    A magnetic coil operated at cryogenic temperatures is used to produce spatial, relative field gradients below 6 ppm/cm, stable for several hours. The apparatus is a prototype of the magnetic components for a neutron electric dipole moment (nEDM) search, which will take place at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory using ultra-cold neutrons (UCN). That search requires a uniform magnetic field to mitigate systematic effects and obtain long polarization lifetimes for neutron spin precession measurements. This paper details upgrades to a previously described apparatus [1], particularly the introduction of super-conducting magnetic shielding and the associated cryogenic apparatus. The magnetic gradients observed are sufficiently low for the nEDM search at SNS.

  18. Structural Design and Thermal Analysis for Thermal Shields of the MICE Coupling Magnets

    International Nuclear Information System (INIS)

    Green, Michael A.; Pan, Heng; Liu, X.K.; Wang, Li; Wu, Hong; Chen, A.B.; Guo, X.L.

    2009-01-01

    A superconducting coupling magnet made from copper matrix NbTi conductors operating at 4 K will be used in the Muon Ionization Cooling Experiment (MICE) to produce up to 2.6 T on the magnet centerline to keep the muon beam within the thin RF cavity indows. The coupling magnet is to be cooled by two cryocoolers with a total cooling capacity of 3 W at 4.2 K. In order to keep a certain operating temperature margin, the most important is to reduce the heat leakage imposed on cold surfaces of coil cold mass assembly. An ntermediate temperature shield system placed between the coupling coil and warm vacuum chamber is adopted. The shield system consists of upper neck shield, main shields, flexible connections and eight supports, which is to be cooled by the first stage cold heads of two ryocoolers with cooling capacity of 55 W at 60 K each. The maximum temperature difference on the shields should be less than 20 K, so the thermal analyses for the shields with different thicknesses, materials, flexible connections for shields' cooling and structure design for heir supports were carried out. 1100 Al is finally adopted and the maximum temperature difference is around 15 K with 4 mm shield thickness. The paper is to present detailed analyses on the shield system design.

  19. SHIELDING OF A UNIFORM ALTERNATING MAGNETIC FIELD USING A CIRCULAR PASSIVE LOOP

    Directory of Open Access Journals (Sweden)

    V. S. Grinchenko

    2015-04-01

    Full Text Available The magnetic and electromagnetic shields are used to reduce the magnetic field in local spaces. Usually these shields are implemented in the form of a box or a cylinder. At the same time the magnetic field reduction in local spaces by means of passive loops is not considered in detail yet. So, the present study considers shielding capabilities of a circular passive loop. The authors have performed an analytical and numerical modeling of a process of a uniform harmonic magnetic field shielding. The simulated results permit to find out the spatial distribution of the shielded magnetic field. Dependencies of shielding effectiveness on the passive loop radius and cross-section are determined. Moreover, the non-monotonic behavior of the loop radius dependence is shown. We have substantiated that the shielded volume of a circular passive loop is advisable to limit by the sphere with a half loop radius. Presented results give parameters of the circular passive loop that reduces the rms value of the magnetic flux density by 30 %.

  20. The use of steel and lead shieldings in radiotherapy rooms and its comparison with respect to neutrons doses at patients

    International Nuclear Information System (INIS)

    Silva, M.G.; Rebello, W.F.; Andrade, E.R.; Medeiros, M.P.C.; Mendes, R.M.S.; Braga, K.L.; Gomes, R.G.; Santos, R.F.G.

    2015-01-01

    The NCRP Report No. 151, Structural Shielding Design and Evaluation for Megavoltage X- and Gamma-Ray Radiotherapy Facilities, considers, in shielding calculations for radiotherapy rooms, the use of lead and/or steel to be applied on bunker walls. The NCRP Report calculations were performed foreseeing a better protection of people outside the radiotherapy room. However, contribution of lead and steel to patient dose should be taken into account for radioprotection purposes. This work presents calculations performed by MCNPX code in analyzing the Ambient Dose Equivalent due to neutron, H*(10) n , within a radiotherapy room, in the patients area, considering the use of additional shielding of 1 TVL of lead or 1 TVL of steel, positioned at the inner faces of walls and ceiling of a bunker. The head of the linear accelerator Varian 2100/2300 C/D was modeled working at 18MeV, with 5x5cm 2 , 10x10cm 2 , 20x20cm 2 , 30x30cm 2 and 40x40cm 2 openings for jaws and MLC and operating in eight gantry's angles. This study shows that the use of lead generates an average value of H*(10) n at patients area, 8.02% higher than the expected when using steel. Further studies should be performed based on experimental data for comparison with those from MCNPX simulation.

  1. MAGNETIC SHIELDING OF EXOMOONS BEYOND THE CIRCUMPLANETARY HABITABLE EDGE

    Energy Technology Data Exchange (ETDEWEB)

    Heller, René [McMaster University, Department of Physics and Astronomy, Hamilton, ON L8S 4M1 (Canada); Zuluaga, Jorge I., E-mail: rheller@physics.mcmaster.ca, E-mail: jzuluaga@fisica.udea.edu.co [FACom - Instituto de Física - FCEN, Universidad de Antioquia, Calle 70 No. 52-21, Medellín (Colombia)

    2013-10-20

    With most planets and planetary candidates detected in the stellar habitable zone (HZ) being super-Earths and gas giants rather than Earth-like planets, we naturally wonder if their moons could be habitable. The first detection of such an exomoon has now become feasible, and due to observational biases it will be at least twice as massive as Mars. However, formation models predict that moons can hardly be as massive as Earth. Hence, a giant planet's magnetosphere could be the only possibility for such a moon to be shielded from cosmic and stellar high-energy radiation. Yet, the planetary radiation belt could also have detrimental effects on exomoon habitability. Here we synthesize models for the evolution of the magnetic environment of giant planets with thresholds from the runaway greenhouse (RG) effect to assess the habitability of exomoons. For modest eccentricities, we find that satellites around Neptune-sized planets in the center of the HZ around K dwarf stars will either be in an RG state and not be habitable, or they will be in wide orbits where they will not be affected by the planetary magnetosphere. Saturn-like planets have stronger fields, and Jupiter-like planets could coat close-in habitable moons soon after formation. Moons at distances between about 5 and 20 planetary radii from a giant planet can be habitable from an illumination and tidal heating point of view, but still the planetary magnetosphere would critically influence their habitability.

  2. MAGNETIC SHIELDING OF EXOMOONS BEYOND THE CIRCUMPLANETARY HABITABLE EDGE

    International Nuclear Information System (INIS)

    Heller, René; Zuluaga, Jorge I.

    2013-01-01

    With most planets and planetary candidates detected in the stellar habitable zone (HZ) being super-Earths and gas giants rather than Earth-like planets, we naturally wonder if their moons could be habitable. The first detection of such an exomoon has now become feasible, and due to observational biases it will be at least twice as massive as Mars. However, formation models predict that moons can hardly be as massive as Earth. Hence, a giant planet's magnetosphere could be the only possibility for such a moon to be shielded from cosmic and stellar high-energy radiation. Yet, the planetary radiation belt could also have detrimental effects on exomoon habitability. Here we synthesize models for the evolution of the magnetic environment of giant planets with thresholds from the runaway greenhouse (RG) effect to assess the habitability of exomoons. For modest eccentricities, we find that satellites around Neptune-sized planets in the center of the HZ around K dwarf stars will either be in an RG state and not be habitable, or they will be in wide orbits where they will not be affected by the planetary magnetosphere. Saturn-like planets have stronger fields, and Jupiter-like planets could coat close-in habitable moons soon after formation. Moons at distances between about 5 and 20 planetary radii from a giant planet can be habitable from an illumination and tidal heating point of view, but still the planetary magnetosphere would critically influence their habitability

  3. Concurrent transition of ferroelectric and magnetic ordering near room temperature.

    Science.gov (United States)

    Ko, Kyung-Tae; Jung, Min Hwa; He, Qing; Lee, Jin Hong; Woo, Chang Su; Chu, Kanghyun; Seidel, Jan; Jeon, Byung-Gu; Oh, Yoon Seok; Kim, Kee Hoon; Liang, Wen-I; Chen, Hsiang-Jung; Chu, Ying-Hao; Jeong, Yoon Hee; Ramesh, Ramamoorthy; Park, Jae-Hoon; Yang, Chan-Ho

    2011-11-29

    Strong spin-lattice coupling in condensed matter gives rise to intriguing physical phenomena such as colossal magnetoresistance and giant magnetoelectric effects. The phenomenological hallmark of such a strong spin-lattice coupling is the manifestation of a large anomaly in the crystal structure at the magnetic transition temperature. Here we report that the magnetic Néel temperature of the multiferroic compound BiFeO(3) is suppressed to around room temperature by heteroepitaxial misfit strain. Remarkably, the ferroelectric state undergoes a first-order transition to another ferroelectric state simultaneously with the magnetic transition temperature. Our findings provide a unique example of a concurrent magnetic and ferroelectric transition at the same temperature among proper ferroelectrics, taking a step toward room temperature magnetoelectric applications.

  4. Evaluation of a method to shield a welding electron beam from magnetic interference

    Science.gov (United States)

    Wall, W. A.

    1976-01-01

    It is known that electron beams are easily deflected by magnetic and electrostatic fields. Therefore, to prevent weld defects, stray electromagnetic fields are avoided in electron beam welding chambers if at all possible. The successful results of tests conducted at MSFC to evaluate a simple magnetic shield made from steel tubing are reported. Tests indicate that this shield was up to 85 percent effective in reducing magnetic effects on the electron beam of a welding machine. In addition, residual magnetic fields within the shield were so nearly uniform that the net effect on the beam alignment was negligible. It is concluded that the shield, with the addition of a tungsten liner, could be used in production welding.

  5. Classical anomalous absorption in strongly magnetized plasmas and effective shielding length

    International Nuclear Information System (INIS)

    Matsuda, K.

    1981-01-01

    The high-frequency conductivity tensor of a plasma in a magnetic field has been evaluated. An anomalous perpendicular conductivity is obtained for a strongly magnetized plasma. Contrarily to the previous prediction, the effective shielding length is found to be the Debye length even when the Debye length is larger than the electron gyroradius. The effective shielding length is further discussed by presenting the generalized Balescu-Lenard equation

  6. Magnetic refrigeration--towards room-temperature applications

    International Nuclear Information System (INIS)

    Brueck, E.; Tegus, O.; Li, X.W.; Boer, F.R. de; Buschow, K.H.J.

    2003-01-01

    Modern society relies very much on readily available cooling. Magnetic refrigeration based on the magneto-caloric effect (MCE) has become a promising competitive technology for the conventional gas-compression/expansion technique in use today. Recently, there have been two breakthroughs in magnetic-refrigeration research: one is that American scientists demonstrated the world's first room-temperature, permanent-magnet, magnetic refrigerator; the other one is that we discovered a new class of magnetic refrigerant materials for room-temperature applications. The new materials are manganese-iron-phosphorus-arsenic (MnFe(P,As)) compounds. This new material has important advantages over existing magnetic coolants: it exhibits a huge MCE, which is larger than that of Gd metal; and its operating temperature can be tuned from about 150 to about 335 K by adjusting the P/As ratio. Here we report on further improvement of the materials by increasing the Mn content. The large entropy change is attributed to a field-induced first-order phase transition enhancing the effect of the applied magnetic field. Addition of Mn reduces the thermal hysteresis, which is intrinsic to the first-order transition. This implies that already moderate applied magnetic fields of below 2 T may suffice

  7. Optimisation of structural shielding of accelerator control room for compliance with ALARA principle under Indian conditions

    International Nuclear Information System (INIS)

    Ahmad, Masood; Singh, Brijesh

    1999-01-01

    The case of a 20 MV x-ray accelerator has been considered in this paper for optimisation. An internationally recommended value of α = US$ 1000 per person-sievert has been assumed. Cost of concrete has been assumed as US$ 82.7/m 3 . It is seen that, extra shielding is needed to satisfy the ALARA principle. Further, the amount of requisite shielding increases with the degree of occupancy and, also, if the local construction materials or the labour are cheaper than considered in this paper. Accordingly 1.5 to 4.75 HVLs may be needed as extra shielding in different situations. Therefore, a site specific and installation specific optimisation of shielding is necessary

  8. Considerations on scattering and leak radiation for effective determination of secondary shielding in X-rays rooms of megavoltage

    International Nuclear Information System (INIS)

    Borges, Diogo da S.; Lava, Deise D.; Affonso, Renato R.W.; Moreira, Maria de L.; Guimaraes, Antonio C.F.

    2014-01-01

    This paper addresses the development of a algorithm capable of analyzing the thickness of the secondary shielding due to the production of secondary beams. The production of this beam requires consideration of scattering angle, as well as factors normally used for screening of medical facilities using radiographic techniques. Besides the beam emanated from scattering radiation, is is necessary to evaluate the contribution of leakage radiation, originating from equipment used for the production of the primary beam. A view of the mutual contribution of these radiation to the formation of the secondary beam has shown the need of using shieldings in adjacent walls of the room. The code was validated by comparison with an example case provided by NCRP-151 Report. In this report calculations for determining the secondary barrier for small angles are presented, that deserves greater attention for shielding and statements related to radiotherapy procedures of Modulated intensity. The results are consistent with those provided in the report, which makes the code can be used as a practical tool for the determination of effective shielding beams of megavoltage X-rays

  9. The magnetic shield design and simulation of an X-ray spectrometer for Chang'E mission

    International Nuclear Information System (INIS)

    Zhang Jiayu; Wang Huanyu; Zhang Chengmo; Yang Jiawei; Liang Xiaohua; Wang Jinzhou; Cao Xuelei; Gao Min; Cui Xingzhu; Peng Wenxi

    2008-01-01

    Basic design methods about the magnetic shield of an X-ray spectrometer for Chang'E Mission were introduced in this paper. The real magnetic field distribution was obtained through the measure experiment, and according to the measure results, the simulation to evaluate the magnetic shield effect was carded on. The results showed that the collimator can play a good role in magnetic shield to the electron. (authors)

  10. Observation of Various and Spontaneous Magnetic Skyrmionic Bubbles at Room Temperature in a Frustrated Kagome Magnet with Uniaxial Magnetic Anisotropy

    KAUST Repository

    Hou, Zhipeng; Ren, Weijun; Ding, Bei; Xu, Guizhou; Wang, Yue; Yang, Bing; Zhang, Qiang; Zhang, Ying; Liu, Enke; Xu, Feng; Wang, Wenhong; Wu, Guangheng; Zhang, Xixiang; Shen, Baogen; Zhang, Zhidong

    2017-01-01

    to various external stimuli acting as information carriers in spintronic devices. Here, the first observation of skyrmionic magnetic bubbles with variable topological spin textures formed at room temperature in a frustrated kagome Fe3 Sn2 magnet with uniaxial

  11. Thermal investigations of a room temperature magnetic refrigerator

    Energy Technology Data Exchange (ETDEWEB)

    Smaili, Arezki; Chiba, Younes [Ecole Nationale Polytechnique d' Alger (Algeria)], email: arezki.smaili@enp.edu.dz

    2011-07-01

    Magnetic refrigeration is a concept based on the magnetocaloric effect that some materials exhibit when the external magnetic field changes. The aim of this paper is to assess the performance of a numerical model in predicting parameters of an active magnetic regenerator refrigerator. Numerical simulations were conducted to perform a thermal analysis on an active magnetic regenerator refrigerator operating near room temperature with and without applied cooling load. Curves of temperature span, cooling capacity and thermal efficiency as functions of the operating conditions were drawn and are presented in this paper. Results showed that at fixed frequency Ql versus mf has an optimum and COP was increased with cycle frequency values. This study demonstrated that the proposed numerical model could be used to predict parameters of an active magnetic regenerator refrigerator as it provides consistent results.

  12. An analytical solution to the shielding of Co 60 teletherapy rooms based on a semiempirical equation of photon attenuation

    International Nuclear Information System (INIS)

    Saez, D.G.; Hernandez, L.; Borroto, M.; Figueredo, M.

    1996-01-01

    A semiempirical equation of polynomial-exponential type is presented to describe the transmission data of Co-60 gamma radiation in finite materials of concrete and lead. This equation and the expression obtained for the relationship of scatter-to-incident exposure made easy the developing in computer of an analytical solution for shielding calculations of Co 60 teletherapy rooms, based on the procedures of the NCRP 49 and Simpkin's method. The standard error in the estimation of parameters is less than 1.7 % except for the attenuation of 150 'o' scattered radiation in concrete that resulted in 6.3 % for one of them. The shielding calculations were compared with the data in NCRP 49 for the same conditions with a correlation better than 99 %

  13. Shielding of Sensitive Electronic Devices in Magnetic Nanoparticle Hyperthermia Using Arrays of Coils

    International Nuclear Information System (INIS)

    Spirou, S V; Tsialios, P; Loudos, G

    2015-01-01

    In Magnetic Nanoparticle Hyperthermia (MNH) an externally applied electromagnetic field transfers energy to the magnetic nanoparticles in the body, which in turn convert this energy into heat, thus locally heating the tissue they are located in. This external electromagnetic field is sufficiently strong so as to cause interference and affect sensitive electronic equipment. Standard shielding of magnetic fields involves Faraday cages or coating with high-permeability shielding alloys; however, these techniques cannot be used with optically sensitive devices, such as those employed in Optical Coherence Tomography or radionuclide imaging. In this work we present a method to achieve magnetic shielding using an array of coils. The magnetic field generated by a single coil was calculated using the COMSOL physics simulation toolkit. Software was written in C/C++ to import the single-coil data, and then calculate the positions, number of turns and currents in the shielding coils in order to minimize the magnetic field strength at the desired location. Simulations and calculations have shown that just two shielding coils can reduce the magnetic field by 2-3 orders of magnitude. (paper)

  14. Shielding of Sensitive Electronic Devices in Magnetic Nanoparticle Hyperthermia Using Arrays of Coils

    Science.gov (United States)

    Spirou, S. V.; Tsialios, P.; Loudos, G.

    2015-09-01

    In Magnetic Nanoparticle Hyperthermia (MNH) an externally applied electromagnetic field transfers energy to the magnetic nanoparticles in the body, which in turn convert this energy into heat, thus locally heating the tissue they are located in. This external electromagnetic field is sufficiently strong so as to cause interference and affect sensitive electronic equipment. Standard shielding of magnetic fields involves Faraday cages or coating with high-permeability shielding alloys; however, these techniques cannot be used with optically sensitive devices, such as those employed in Optical Coherence Tomography or radionuclide imaging. In this work we present a method to achieve magnetic shielding using an array of coils. The magnetic field generated by a single coil was calculated using the COMSOL physics simulation toolkit. Software was written in C/C++ to import the single-coil data, and then calculate the positions, number of turns and currents in the shielding coils in order to minimize the magnetic field strength at the desired location. Simulations and calculations have shown that just two shielding coils can reduce the magnetic field by 2-3 orders of magnitude.

  15. Shielding design of a treatment room for an accelerator-based epithermal neutron irradiation facility for BNCT

    International Nuclear Information System (INIS)

    Evans, J.F.; Blue, T.E.

    1996-01-01

    Protecting the facility personnel and the general public from radiation exposure is a primary safety concern of an accelerator-based epithermal neutron irradiation facility. This work makes an attempt at answering the questions open-quotes How much?close quotes and open-quotes What kind?close quotes of shielding will meet the occupational limits of such a facility. Shielding effectiveness is compared for ordinary and barytes concretes in combination with and without borated polyethylene. A calculational model was developed of a treatment room, patient open-quotes scatterer,close quotes and the epithermal neutron beam. The Monte Carlo code, MCNP, was used to compute the total effective dose equivalent rates at specific points of interest outside of the treatment room. A conservative occupational effective dose rate limit of 0.01 mSv h -1 was the guideline for this study. Conservative Monte Carlo calculations show that constructing the treatment room walls with 1.5 m of ordinary concrete, 1.2 m of barytes concrete, 1.0 m of ordinary concrete preceded by 10 cm of 5% boron-polyethylene, or 0.8 m of barytes concrete preceded by 10 cm of 5% boron-polyethylene will adequately protect facility personnel. 20 refs., 8 figs., 2 tabs

  16. Optimal Magnetic Field Shielding Method by Metallic Sheets in Wireless Power Transfer System

    Directory of Open Access Journals (Sweden)

    Feng Wen

    2016-09-01

    Full Text Available To meet the regulations established to limit human exposure to time-varying electromagnetic fields (EMFs such as the International Committee on Non-Ionizing Radiation Protection (ICNIRP guidelines, thin metallic sheets are often used to shield magnetic field leakage in high power applications of wireless power transfer (WPT systems based on magnetic field coupling. However, the metals in the vicinity of the WPT coils cause the decrease of self and mutual inductances and increase of effective series resistance; as such, the electric performance including transmission power and the efficiency of the system is affected. With the research objective of further investigating excellent shielding effectiveness associated with system performance, the utilization of the optimal magnetic field shielding method by metallic sheets in magnetic field coupling WPT is carried out in this paper. The circuit and 3D Finite Element Analysis (FEA models are combined to predict the magnetic field distribution and electrical performance. Simulation and experiment results show that the method is very effective by obtaining the largest possible coupling coefficient of the WPT coils within the allowable range and then reducing the value nearest to and no smaller than the critical coupling coefficient via geometric unbroken metallic sheets. The optimal magnetic field shielding method which considers the system efficiency, transmission power, transmission distance, and system size is also achieved using the analytic hierarchy process (AHP. The results can benefit WPT by helping to achieve efficient energy transfer and safe use in metal shielded equipment.

  17. Technical and economic considerations of using actively shielded superconducting magnets for MR imaging

    International Nuclear Information System (INIS)

    McDougall, L.; Hawksworth, D.

    1986-01-01

    Air-cored superconducting magnets provide uniform fields for MR imaging over large volumes at the lowest cost per gauss of available technologies. Traditional solenoidal designs have an air flux return path and contaminate the clinical environment. Actively shielded magnets comprising one magnet inside another provide the maximum possible fringe field reduction per unit cost. The use of iron to reduce fringe field is more costly than active shielding and much less flexible. Solutions to providing fringe field cancellation are possible using industry standard cryostat dimensions. Costs of materials are minimized by designing with coil optimization routines that include stress parameters

  18. Design and demonstration of adiabatic quantum-flux-parametron logic circuits with superconductor magnetic shields

    International Nuclear Information System (INIS)

    Inoue, Kenta; Narama, Tatsuya; Yamanashi, Yuki; Yoshikawa, Nobuyuki; Takeuchi, Naoki

    2015-01-01

    Adiabatic quantum-flux-parametron (AQFP) logic is an energy-efficient superconductor logic with zero static power and very small dynamic power due to adiabatic switching operations. In order to build large-scale digital circuits, we built AQFP logic cells using superconductor magnetic shields, which are necessary in order to avoid unwanted magnetic couplings between the cells and excitation currents. In preliminary experimental tests, we confirmed that the unwanted coupling became negligibly small thanks to the superconductor shields. As a demonstration, we designed a four-to-one multiplexor and a 16-junction full adder using the shielded logic cells. In both circuits, we confirmed correct logic operations with wide operation margins of excitation currents. These results indicate that large-scale AQFP digital circuits can be realized using the shielded logic cells. (paper)

  19. Frequency dependence of magnetic shielding performance of HTS plates in mixed states

    Energy Technology Data Exchange (ETDEWEB)

    Kamitani, Atsushi; Yokono, Takafumi [Yamagata Univ., Yonezawa (Japan). Faculty of Engineering; Yokono, Takafumi [Tsukuba Univ., Ibaraki (Japan). Inst. of Information Sciences and Electronics

    2000-06-01

    The magnetic shielding performance of the high-Tc superconducting (HTS) plate is investigated numerically. The behavior of the shielding current density in the HTS plate is expressed as the integral-differential equation with a normal component of the current vector potential as a dependent variable. The numerical code for solving the equation has been developed by using the combination of the Newton-Raphson method and the successive substitution method and, by use of the code, damping coefficients and shielding factors are evaluated for the various values of the frequency {omega}. The results of computations show that the HTS plate has a possibility of shielding the high-frequency magnetic field with {omega} > or approx. 1 kHz. (author)

  20. Frequency dependence of magnetic shielding performance of HTS plates in mixed states

    International Nuclear Information System (INIS)

    Kamitani, Atsushi; Yokono, Takafumi; Yokono, Takafumi

    2000-01-01

    The magnetic shielding performance of the high-Tc superconducting (HTS) plate is investigated numerically. The behavior of the shielding current density in the HTS plate is expressed as the integral-differential equation with a normal component of the current vector potential as a dependent variable. The numerical code for solving the equation has been developed by using the combination of the Newton-Raphson method and the successive substitution method and, by use of the code, damping coefficients and shielding factors are evaluated for the various values of the frequency ω. The results of computations show that the HTS plate has a possibility of shielding the high-frequency magnetic field with ω > or approx. 1 kHz. (author)

  1. A study on optimization of photoneutron shielding in a medical accelerator room by using Monte Carlo simulation

    International Nuclear Information System (INIS)

    Kim, Yong Nam; Jeong, Kyoungkeun; Kim, Joo Young; Lee, Chang Geol; Seong, Jinsil; Choi, Sang Hyun; Kim, Chan Hyeong

    2008-01-01

    Medical linear accelerators operating above 10 MV require door shielding for neutrons in addition to photons. A criterion for choice of optimal configuration of lamination of BPE (Borated Polyethylene) and lead is not clear. Moreover, optimal configuration cannot be determined by the conventional method using an analytical formula and simple measurement. This study performs Monte Carlo simulation of radiation field in a commercial LINAC room with 15 MV X-ray sources. Considering two configuration of lamination such as 'lead-BPE' and 'lead-BPE-lead', dose equivalents are calculated by using the MCNPX code and comparative analyses are performed with each other. The obtained results show that there is no significant difference in neuron shielding between both configurations, whereas lead-BPE-lead is more effective for photon shielding. It is also noted that the absolute values of neutron doses are much greater than that of photon doses outside as well as inside the door, by three orders of magnitude. As a conclusion, the laminating of lead-BPE is suggested as the optimal configuration from the viewpoint of simplicity in fabrication and handling, even though it has no significant difference from lead-BPE-lead in terms of total dose equivalent. (author)

  2. Manufacture and testing of the CTB&SBB thermal shield for the ITER magnet feeder system

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Kun; Liu, Chen; Song, Yuntao; Feng, Hansheng; Ding, Kaizhong, E-mail: kzding@ipp.ac.cn; Wang, Tanbin; Ji, Hui

    2015-10-15

    The system of International Thermonuclear Experimental Reactor (ITER) feeders is responsible for the power, helium cooling, and instrumentation of the magnets of the coil terminal box and S-bend box (CTB&SBB) thermal shield outside the cryostat. An 80-K rectangular Al thermal shield is hung inside the CTB&SBB to reduce the thermal radiation heat loads of 4.5-K helium. The American Society of Interventional Pain Physicians (ASIPP) will supply all the 31 sets of feeders for ITER. A manufactured prototype of CTB&SBB thermal shield is first quality-tested before the commencement of the series production. First, a detailed configuration of the rectangular Al thermal shield is presented in this article. The paper also presents more information on the manufacturing process of the thermal shield, especially the welding process, the procedure for ensuring good weld quality, and the use of a specially designed tool to ensure <5-mm deformation on such a 7.3-m-long thermal shield during welding. In addition, the cold test and results, including the cooling process with 13-bar and 17.5-g/s 80-K He gas, and the temperature distribution on different panels of the thermal shield are presented. The whole process of manufacture and testing lays a good foundation for the series production of the thermal shield.

  3. Survey of shielding calculation parameters in radiotherapy rooms used in the country and its impact in the existing calculation methodologies

    International Nuclear Information System (INIS)

    Japiassu, Fernando Parois

    2013-01-01

    When designing radiotherapy treatment rooms, the dimensions of barriers are established on the basis of American calculation methodologies specifically; NCRP Report N° 49, NCRP Report N° 51, and more recently, NCRP Report N° 151. Such barrier calculations are based on parameters reflecting predictions of treatments to be performed within the room; which, in tum, reftect a specific reality found in a country. There exists, however, a variety of modern radiotherapy techniques, such as Intensity Modulated Radiation Therapy (IMRT); Total Body Irradiation (TBl) and radiosurgery (SRS); where patierits are treated in a much different way than during more conventional treatrnents, which are not taken into account the traditional shielding calculation methodology. This may lead to a faulty design of treattnent rooms. In order to establish a comparison between the methodology used to calculate shielding design and the reality of treatments performed in Brazil, two radiotherapy facilitie were selected, both of them offering traditional and modern treatment techniqued as described above. Data in relation with reatments perfotmed over a period of six (6)months of operations in both institutions were collected. Based on tlis informaton, a new set of realistic parameters required for shielding design was estãblished, whicb in turn allowed for a nwe caculation of barrier thickness for both facilities. The barrier thickness resultaing from this calculation was then compared with the barrier thickness propose as part of the original shielding design, approved by the regulatory authority. First, concerning the public facility, the thickness of all primary barriers proposed in the shielding design was actually larger than the thickness resulting from calculations based on realistic parameters. Second, concerning the private facility, the new data show that the thickness of three out of the four primary barriers described in the project is larger than the thickness oresulting from

  4. A 2-Tesla active shield magnet for whole body imaging and spectroscopy

    International Nuclear Information System (INIS)

    Davies, F.J.; Elliott, R.T.; Hawksworth, D.G.

    1991-01-01

    This paper reports on the development and testing of a 2T superconducting Active Shield magnet, with a 0.99m diameter warm bore for whole-body Magnetic Resonance Imaging (MRI) and spectroscopy. The magnet and cryostat were designed to meet the same performance standards as existing MRI magnets, but with the volume of the stray field region reduced to less than 4% of that for an unshielded magnet. The 0.5 mT stray field contour is within 5m axially and 3m radially of the magnet center. The system weight is only 14 tonnes

  5. Magnet Architectures and Active Radiation Shielding Study - SR2S Workshop

    Science.gov (United States)

    Westover, Shane; Meinke, Rainer; Burger, William; Ilin, Andrew; Nerolich, Shaun; Washburn, Scott

    2014-01-01

    Analyze new coil configurations with maturing superconductor technology -Develop vehicle-level concept solutions and identify engineering challenges and risks -Shielding performance analysis Recent advances in superconducting magnet technology and manufacturing have opened the door for re-evaluating active shielding solutions as an alternative to mass prohibitive passive shielding.Publications on static magnetic field environments and its bio-effects were reviewed. Short-term exposure information is available suggesting long term exposure may be okay. Further research likely needed. center dotMagnetic field safety requirements exist for controlled work environments. The following effects have been noted with little noted adverse effects -Magnetohydrodynamic (MHD) effects on ionized fluids (e.g. blood) creating an aortic voltage change -MHD interaction elevates blood pressure (BP) center dot5 Tesla equates to 5% BP elevation -Prosthetic devises and pacemakers are an issue (access limit of 5 gauss).

  6. A three-layer magnetic shielding for the MAIUS-1 mission on a sounding rocket

    International Nuclear Information System (INIS)

    Kubelka-Lange, André; Herrmann, Sven; Grosse, Jens; Lämmerzahl, Claus; Rasel, Ernst M.; Braxmaier, Claus

    2016-01-01

    Bose-Einstein-Condensates (BECs) can be used as a very sensitive tool for experiments on fundamental questions in physics like testing the equivalence principle using matter wave interferometry. Since the sensitivity of these experiments in ground-based environments is limited by the available free fall time, the QUANTUS project started to perform BEC interferometry experiments in micro-gravity. After successful campaigns in the drop tower, the next step is a space-borne experiment. The MAIUS-mission will be an atom-optical experiment that will show the feasibility of experiments with ultra-cold quantum gases in microgravity in a sounding rocket. The experiment will create a BEC of 10"5 "8"7Rb-atoms in less than 5 s and will demonstrate application of basic atom interferometer techniques over a flight time of 6 min. The hardware is specifically designed to match the requirements of a sounding rocket mission. Special attention is thereby spent on the appropriate magnetic shielding from varying magnetic fields during the rocket flight, since the experiment procedures are very sensitive to external magnetic fields. A three-layer magnetic shielding provides a high shielding effectiveness factor of at least 1000 for an undisturbed operation of the experiment. The design of this magnetic shielding, the magnetic properties, simulations, and tests of its suitability for a sounding rocket flight are presented in this article.

  7. A three-layer magnetic shielding for the MAIUS-1 mission on a sounding rocket

    Energy Technology Data Exchange (ETDEWEB)

    Kubelka-Lange, André, E-mail: andre.kubelka@zarm.uni-bremen.de; Herrmann, Sven; Grosse, Jens; Lämmerzahl, Claus [Center of Applied Space Technology and Microgravity (ZARM), University of Bremen, Am Fallturm, 28359 Bremen (Germany); Rasel, Ernst M. [Institut für Quantenoptik, Leibniz Universität Hannover, Welfengarten 1, 30167 Hannover (Germany); Braxmaier, Claus [Center of Applied Space Technology and Microgravity (ZARM), University of Bremen, Am Fallturm, 28359 Bremen (Germany); DLR Institute for Space Systems, Robert-Hooke-Str. 7, 28359 Bremen (Germany)

    2016-06-15

    Bose-Einstein-Condensates (BECs) can be used as a very sensitive tool for experiments on fundamental questions in physics like testing the equivalence principle using matter wave interferometry. Since the sensitivity of these experiments in ground-based environments is limited by the available free fall time, the QUANTUS project started to perform BEC interferometry experiments in micro-gravity. After successful campaigns in the drop tower, the next step is a space-borne experiment. The MAIUS-mission will be an atom-optical experiment that will show the feasibility of experiments with ultra-cold quantum gases in microgravity in a sounding rocket. The experiment will create a BEC of 10{sup 5} {sup 87}Rb-atoms in less than 5 s and will demonstrate application of basic atom interferometer techniques over a flight time of 6 min. The hardware is specifically designed to match the requirements of a sounding rocket mission. Special attention is thereby spent on the appropriate magnetic shielding from varying magnetic fields during the rocket flight, since the experiment procedures are very sensitive to external magnetic fields. A three-layer magnetic shielding provides a high shielding effectiveness factor of at least 1000 for an undisturbed operation of the experiment. The design of this magnetic shielding, the magnetic properties, simulations, and tests of its suitability for a sounding rocket flight are presented in this article.

  8. Use of a radio frequency shield during 1.5 and 3.0 Tesla magnetic resonance imaging: experimental evaluation.

    Science.gov (United States)

    Favazza, Christopher P; King, Deirdre M; Edmonson, Heidi A; Felmlee, Joel P; Rossman, Phillip J; Hangiandreou, Nicholas J; Watson, Robert E; Gorny, Krzysztof R

    2014-01-01

    Radiofrequency (RF) shields have been recently developed for the purpose of shielding portions of the patient's body during magnetic resonance imaging (MRI) examinations. We present an experimental evaluation of a commercially available RF shield in the MRI environment. All tests were performed on 1.5 T and 3.0 T clinical MRI scanners. The tests were repeated with and without the RF shield present in the bore, for comparison. Effects of the shield, placed within the scanner bore, on the RF fields generated by the scanner were measured directly using tuned pick-up coils. Attenuation, by as much as 35 dB, of RF field power was found inside the RF shield. These results were supported by temperature measurements of metallic leads placed inside the shield, in which no measurable RF heating was found. In addition, there was a small, simultaneous detectable increase (∼1 dB) of RF power just outside the edges of the shield. For these particular scanners, the autocalibrated RF power levels were reduced for scan locations prescribed just outside the edges of the shield, which corresponded with estimations based on the pick-up coil measurements. Additionally, no significant heating during MRI scanning was observed on the shield surface. The impact of the RF shield on the RF fields inside the magnet bore is likely to be dependent on the particular model of the RF shield or the MRI scanner. These results suggest that the RF shield could be a valuable tool for clinical MRI practices.

  9. Magnetic field shielding system in a tokamak experimental power reactor (EPR): concept and calculations

    International Nuclear Information System (INIS)

    Peng, Y.K.M.; Marcus, F.B.; Dory, R.A.; Moore, J.R.

    1975-01-01

    A poloidal magnetic field shielding system is proposed for a tokamak EPR. This coil system minimizes the pulsed poloidal field that intersects the TF (toroidal field) coils and hence reduces the risk of superconductor quenching and structural failure of the coils. Based on an idealized shielding model, we have determined the configurations for the OH (ohmic heating), the S-VF (shield-vertical field), and the T-VF (trimming-vertical field) coils in a typical tokamak EPR. It is found that the pulsed poloidal field strength is greatly reduced in the TF coil region. The overall requirement in stored plasma and vertical field energy is also substantially reduced when compared with conventional EPR designs. Use of this field shielding system is expected to enhance reliability of the superconducting TF coils in a tokamak EPR

  10. Simulation of a conductive shield plate for the focalization of transcranial magnetic stimulation in the rat.

    Science.gov (United States)

    Gasca, Fernando; Richter, Lars; Schweikard, Achim

    2010-01-01

    Transcranial Magnetic Stimulation (TMS) in the rat is a powerful tool for investigating brain function. However, the state-of-the-art experiments are considerably limited because the stimulation usually affects undesired anatomical structures. A simulation of a conductive shield plate placed between the coil stimulator and the rat brain during TMS is presented. The Finite Element (FE) method is used to obtain the 3D electric field distribution on a four-layer rat head model. The simulations show that the shield plate with a circular window can improve the focalization of stimulation, as quantitatively seen by computing the three-dimensional half power region (HPR). Focalization with the shield plate showed a clear compromise with the attenuation of the induced field. The results suggest that the shield plate can work as a helpful tool for conducting TMS rat experiments on specific targets.

  11. High field septum magnet using a superconducting shield for the Future Circular Collider

    Directory of Open Access Journals (Sweden)

    Dániel Barna

    2017-04-01

    Full Text Available A zero-field cooled superconducting shield is proposed to realize a high-field (3–4 T septum magnet for the Future Circular Collider hadron-hadron (FCC-hh ring. Three planned prototypes using different materials and technical solutions are presented, which will be used to evaluate the feasibility of this idea as a part of the FCC study. The numerical simulation methods are described to calculate the field patterns around such a shield. A specific excitation current configuration is presented that maintains a fairly homogeneous field outside of a rectangular shield in a wide range of field levels from 0 to 3 Tesla. It is shown that a massless septum configuration (with an opening in the shield is also possible and gives satisfactory field quality with realistic superconducting material properties.

  12. High field septum magnet using a superconducting shield for the Future Circular Collider

    CERN Document Server

    AUTHOR|(CDS)2069375

    2017-01-01

    A zero-field cooled superconducting shield is proposed to realize a high-field (3–4 T) septum magnet for the Future Circular Collider hadron-hadron (FCC-hh) ring. Three planned prototypes using different materials and technical solutions are presented, which will be used to evaluate the feasibility of this idea as a part of the FCC study. The numerical simulation methods are described to calculate the field patterns around such a shield. A specific excitation current configuration is presented that maintains a fairly homogeneous field outside of a rectangular shield in a wide range of field levels from 0 to 3 Tesla. It is shown that a massless septum configuration (with an opening in the shield) is also possible and gives satisfactory field quality with realistic superconducting material properties.

  13. Poster - 28: Shielding of X-ray Rooms in Ontario in the Absence of Best Practice

    Energy Technology Data Exchange (ETDEWEB)

    Frimeth, Jeff; Richer, Jeff; Nesbitt, James [Xspect Inc., Windsor Regional Hospital, XRCT Ltd. (Canada)

    2016-08-15

    This poster will be strictly based on the Healing Arts Radiation Protection (HARP) Act, Regulation 543 under this Act (X-ray Safety Code), and personal communication the presenting author has had. In Ontario, the process of approval of an X-ray machine installation by the Director of the X-ray Inspection Service (XRIS) follows a certain protocol. Initially, the applicant submits a series of forms, including recommended shielding amounts, in order to satisfy the law. This documentation is then transferred to a third-party vendor (i.e. a professional engineer – P.Eng.) outsourced by the Ministry of Health and Long-term Care (MOHLTC). The P.Eng. then evaluates the submitted documentation for appropriate fulfillment of the HARP Act and Reg. 543 requirements. If the P.Eng.’s evaluation of the documentation is to their satisfaction, the XRIS is then notified. Finally, the Director will then issue a letter of approval to install the equipment at the facility. The methodology required to be used by the P.Eng. in order to determine the required amounts of protective barriers, and recommended to be used by the applicant, is contained within Safety Code 20A. However, Safety Code 35 has replaced the obsolete Safety Code 20A document and employs best practices in shielding design. This talk will focus further on specific intentions and limitations of Safety Code 20A. Furthermore, this talk will discuss the definition of the “practice of professional engineering” in Ontario. COMP members who are involved in shielding design are strongly encouraged to attend.

  14. Poster - 28: Shielding of X-ray Rooms in Ontario in the Absence of Best Practice

    International Nuclear Information System (INIS)

    Frimeth, Jeff; Richer, Jeff; Nesbitt, James

    2016-01-01

    This poster will be strictly based on the Healing Arts Radiation Protection (HARP) Act, Regulation 543 under this Act (X-ray Safety Code), and personal communication the presenting author has had. In Ontario, the process of approval of an X-ray machine installation by the Director of the X-ray Inspection Service (XRIS) follows a certain protocol. Initially, the applicant submits a series of forms, including recommended shielding amounts, in order to satisfy the law. This documentation is then transferred to a third-party vendor (i.e. a professional engineer – P.Eng.) outsourced by the Ministry of Health and Long-term Care (MOHLTC). The P.Eng. then evaluates the submitted documentation for appropriate fulfillment of the HARP Act and Reg. 543 requirements. If the P.Eng.’s evaluation of the documentation is to their satisfaction, the XRIS is then notified. Finally, the Director will then issue a letter of approval to install the equipment at the facility. The methodology required to be used by the P.Eng. in order to determine the required amounts of protective barriers, and recommended to be used by the applicant, is contained within Safety Code 20A. However, Safety Code 35 has replaced the obsolete Safety Code 20A document and employs best practices in shielding design. This talk will focus further on specific intentions and limitations of Safety Code 20A. Furthermore, this talk will discuss the definition of the “practice of professional engineering” in Ontario. COMP members who are involved in shielding design are strongly encouraged to attend.

  15. Magnetic shielding for FEL microwave electric field diagnostic in MTX tokamak

    International Nuclear Information System (INIS)

    Yamada, Shinichi; Odajima, Kazuo; Ishida, Hiroyasu

    1991-07-01

    A diagnostic system for measurement of microwave electric field from free electron laser (FEL) is in preparation at JAERI under JAERI-DOE collaborative program in the Microwave Tokamak Experiment (MTX) being held at Lawrence Livermore National Laboratory in U.S.A.. That is called LAPPS (Laser Aided Particle Probe Spectroscopy). This is consist of helium neutral beam source, a dye laser and viewing optics. It is required that 1000 gauss of the magnetic field must be shielded to less than 1 gauss in order to operate these LAPPS components. New high performance soft ferrous magnetic material 'FERROPERM' and PERMALLOY are used on this purpose. This paper proposes a new method to estimate a required thickness of the magnetic shielding in a saturated region of B-H curve, that is, 'magnetic shielding calculation by Virtual Divided Layers Method (VDLM)', where the shielding layer is virtually divided in many layers in the calculation. The results are compared with a computer simulation using 'three dimensional static magnetic field code' and with experimental results in a uniform static field. (author)

  16. Passive shielding effect on space profile of magnetic field emissions for wireless power transfer to vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Batra, T., E-mail: tba@et.aau.dk; Schaltz, E. [Department of Energy Technology, Aalborg University, Aalborg 9220 (Denmark)

    2015-05-07

    Magnetic fields emitted by wireless power transfer systems are of high importance with respect to human safety and health. Aluminum and ferrite are used in the system to reduce the fields and are termed as passive shielding. In this paper, the influence of these materials on the space profile has been investigated with the help of simulations on Comsol for the four possible geometries—no shielding, ferrite, aluminum, and full shielding. As the reflected impedance varies for the four geometries, the primary current is varied accordingly to maintain constant power transfer to the secondary side. Surrounding magnetic field plots in the vertical direction show that maxima's of the two coils for the no shielding geometry are centered at the respective coils and for the remaining three are displaced closer to each other. This closeness would lead to more effective addition of the two coil fields and an increase in the resultant field from space point of view. This closeness varies with distance in the horizontal direction and vertical gap between the coils and is explained in the paper. This paper provides a better understanding of effect of the passive shielding materials on the space nature of magnetic fields for wireless power transfer for vehicle applications.

  17. Passive shielding effect on space profile of magnetic field emissions for wireless power transfer to vehicles

    International Nuclear Information System (INIS)

    Batra, T.; Schaltz, E.

    2015-01-01

    Magnetic fields emitted by wireless power transfer systems are of high importance with respect to human safety and health. Aluminum and ferrite are used in the system to reduce the fields and are termed as passive shielding. In this paper, the influence of these materials on the space profile has been investigated with the help of simulations on Comsol for the four possible geometries—no shielding, ferrite, aluminum, and full shielding. As the reflected impedance varies for the four geometries, the primary current is varied accordingly to maintain constant power transfer to the secondary side. Surrounding magnetic field plots in the vertical direction show that maxima's of the two coils for the no shielding geometry are centered at the respective coils and for the remaining three are displaced closer to each other. This closeness would lead to more effective addition of the two coil fields and an increase in the resultant field from space point of view. This closeness varies with distance in the horizontal direction and vertical gap between the coils and is explained in the paper. This paper provides a better understanding of effect of the passive shielding materials on the space nature of magnetic fields for wireless power transfer for vehicle applications

  18. Radiation Shielding Utilizing A High Temperature Superconducting Magnet

    Data.gov (United States)

    National Aeronautics and Space Administration — Project objective is to evaluate human radiation protection and architecture utilizing existing superconducting magnet technology while attempting to significantly...

  19. Analytical model for relativistic corrections to the nuclear magnetic shielding constant in atoms

    Energy Technology Data Exchange (ETDEWEB)

    Romero, Rodolfo H. [Facultad de Ciencias Exactas, Universidad Nacional del Nordeste, Avenida Libertad 5500 (3400), Corrientes (Argentina)]. E-mail: rhromero@exa.unne.edu.ar; Gomez, Sergio S. [Facultad de Ciencias Exactas, Universidad Nacional del Nordeste, Avenida Libertad 5500 (3400), Corrientes (Argentina)

    2006-04-24

    We present a simple analytical model for calculating and rationalizing the main relativistic corrections to the nuclear magnetic shielding constant in atoms. It provides good estimates for those corrections and their trends, in reasonable agreement with accurate four-component calculations and perturbation methods. The origin of the effects in deep core atomic orbitals is manifestly shown.

  20. Passive Shielding Effect on Space Profile of Magnetic Field Emissions for Wireless Power Transfer to Vehicles

    DEFF Research Database (Denmark)

    Batra, Tushar; Schaltz, Erik

    2015-01-01

    Magnetic fields emitted by wireless power transfer systems are of high importance with respect to human safety and health. Aluminum and ferrite are used in the system to reduce the fields and are termed as passive shielding. In this paper, the influence of these materials on the space profile has...... fields for wireless power transfer for vehicle applications....

  1. Analytical model for relativistic corrections to the nuclear magnetic shielding constant in atoms

    International Nuclear Information System (INIS)

    Romero, Rodolfo H.; Gomez, Sergio S.

    2006-01-01

    We present a simple analytical model for calculating and rationalizing the main relativistic corrections to the nuclear magnetic shielding constant in atoms. It provides good estimates for those corrections and their trends, in reasonable agreement with accurate four-component calculations and perturbation methods. The origin of the effects in deep core atomic orbitals is manifestly shown

  2. Design of the magnetized muon shield for the prompt-neutrino facility

    International Nuclear Information System (INIS)

    Baltay, C.; Bosek, N.; Couch, J.

    1982-01-01

    The main technical challenge in the design of the prompt neutrino beam is the magnetized muon shield. Two satisfactory alternate designs have been developed for such a shield during this past year and the background muon fluxes have been calculated by three independent programs at Columbia, Fermilab, and MIT. The background muon fluxes have been calculated to be satisfactory in all of the detectors that might use the beam. In Section III of this report we describe in detail the three Monte Carlo programs used in these calculations. In Section IV we give the details of the flux calculations for the E-613 shield and the comparisons with the observed fluxes with various configurations of that shield. In Section V we describe the designs that have been developed for the neutrino area shield. In Section VI we discuss the problem of proton beam transport losses and the associated muon fluxes. Finally, in Section VII a comparison of the two solutions is made which covers cost, effectiveness, schedule and responsiveness to future unknowns. We conclude that there are not overwhelming reasons for the choice of one design over the other. However, for a variety of secondary reasons the superconducting design offers advantages. We therefore propose the construction of the prompt neutrino facility with the superconducting magnet design

  3. Use of a radio frequency shield during 1.5 and 3.0 Tesla magnetic resonance imaging: experimental evaluation

    Directory of Open Access Journals (Sweden)

    Favazza CP

    2014-10-01

    Full Text Available Christopher P Favazza, Deirdre M King, Heidi A Edmonson, Joel P Felmlee, Phillip J Rossman, Nicholas J Hangiandreou, Robert E Watson, Krzysztof R Gorny Department of Radiology, Mayo Clinic, Rochester, MN, USA Abstract: Radiofrequency (RF shields have been recently developed for the purpose of shielding portions of the patient's body during magnetic resonance imaging (MRI examinations. We present an experimental evaluation of a commercially available RF shield in the MRI environment. All tests were performed on 1.5 T and 3.0 T clinical MRI scanners. The tests were repeated with and without the RF shield present in the bore, for comparison. Effects of the shield, placed within the scanner bore, on the RF fields generated by the scanner were measured directly using tuned pick-up coils. Attenuation, by as much as 35 dB, of RF field power was found inside the RF shield. These results were supported by temperature measurements of metallic leads placed inside the shield, in which no measurable RF heating was found. In addition, there was a small, simultaneous detectable increase (~1 dB of RF power just outside the edges of the shield. For these particular scanners, the autocalibrated RF power levels were reduced for scan locations prescribed just outside the edges of the shield, which corresponded with estimations based on the pick-up coil measurements. Additionally, no significant heating during MRI scanning was observed on the shield surface. The impact of the RF shield on the RF fields inside the magnet bore is likely to be dependent on the particular model of the RF shield or the MRI scanner. These results suggest that the RF shield could be a valuable tool for clinical MRI practices. Keywords: radiofrequency shield, magnetic resonance imaging, radiofrequency attenuation

  4. Magnetic shielding for a transversely polarized target in the longitudinal field of the PANDA solenoid

    Energy Technology Data Exchange (ETDEWEB)

    Froehlich, Bertold; Ahmed, Samer; Dbeyssi, Alaa; Mora Espi, Maria Carmen; Gerz, Kathrin; Lin, Dexu; Maas, Frank; Martinez, Ana Penuelas; Morales, Cristina; Wang, Yadi [Helmholtz Institut Mainz (Germany); Aguar Bartolome, Patricia [Institut fuer Kernphysik, Johannes Gutenberg-Universitaet Mainz (Germany)

    2016-07-01

    A transversely polarized target in PANDA would allow for the first time access to the imaginary part of the time like electromagnetic proton form factors, namely the phase angle in the imaginary plane between electric and magnetic form factors. Moreover it would allow for a number of other target single spin asymmetries revealing nucleon structure observables connected with the transverse spin structure of the proton. As a first step for achieving a transverse target polarization, the target region has to be shielded against the 2 T longitudinal magnetic flux from the solenoid of the PANDA spectrometer. We present experimental results on intense magnetic flux shielding using a BSCCO-2212 high temperature superconducting hollow cylinder at liquid helium temperature.

  5. Estimated residual Magnetic Field acting on the Circulating Beam in the LHC Septum Magnets MSI and MSD - Shielding Efficiency

    CERN Document Server

    Gyr, Marcel

    2000-01-01

    Computation of the residual field inside the shielded vacuum chambers of the circulating beams that pass through the septum holes of the MSI and MSD magnets is very impractical because of the disproportionate effort involved in obtaining meaningful results. Therefore, a short model has been built to measure the order of magnitude of the residual field inside the LHC vacuum chambers. It is found, that a 0.9 mm thick µ-metal (or Permalloy$^{TM}$) shielding is sufficient to reduce the field, which is experienced by the circulating beam, below the level of the earth's field.

  6. Shielding of the NBI boxes against W7-X magnetic stray fields

    Energy Technology Data Exchange (ETDEWEB)

    Kick, Manfred [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstr. 2, D-85748 Garching (Germany)], E-mail: Kick@arcor.de; Sielanko, Juliusz [Maria Curie Sklodowska University, Pl. M. C. Sklodowskie 1, 20-031 Lublin (Poland); Heinemann, Bernd; Riedl, Rudolf; Speth, Eckehart; Staebler, Albrecht [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstr. 2, D-85748 Garching (Germany)

    2009-06-15

    Neutral Beam Injection (NBI), besides ECRH, is foreseen as one of the main heating devices at the W7-X stellarator currently under construction at IPP Greifswald, Germany. In a final stage 20 MW of NBI heating power will be installed generated by two NBI boxes of the ASDEX Upgrade (AUG) type. Since magnetic fields generally affect the trajectories of charged particles, essentially all the NBI boxes - including ion sources, acceleration sections, neutralisers and deflection magnets - must be shielded against the stray fields of W7-X. In the magnetic stray fields of W7-X there exist significant radial and toroidal components whereas at tokamaks the vertical components are dominant. The power loads on the ion dump and the protecting structures of the deflecting magnets and the beam lines caused by residual beam ions, therefore, will be strongly different. Thus the shielding concept of AUG cannot simply be taken over, but must be carefully redesigned in order to remain below the critical power limits. New modelling calculations of the magnetic shielding, the ion trajectories and the resulting power loads have been carried out for the 'high iota' and 'low shear' experimental scenarios of W7-X. The fields taken for these calculations are modelled by averaging the calculated W7-X stray fields on the one hand, and by fields generated by two-hypothetical-planar coils perpendicular to the x-y plane, on the other hand. The shielding concept for W7-X mainly consist of iron plates in the outer side regions of the boxes and as little magnetic material as possible inside the boxes.

  7. Double-layer rotor magnetic shield performance analysis in high temperature superconducting synchronous generators under short circuit fault conditions

    Science.gov (United States)

    Hekmati, Arsalan; Aliahmadi, Mehdi

    2016-12-01

    High temperature superconducting, HTS, synchronous machines benefit from a rotor magnetic shield in order to protect superconducting coils against asynchronous magnetic fields. This magnetic shield, however, suffers from exerted Lorentz forces generated in light of induced eddy currents during transient conditions, e.g. stator windings short-circuit fault. In addition, to the exerted electromagnetic forces, eddy current losses and the associated effects on the cryogenic system are the other consequences of shielding HTS coils. This study aims at investigating the Rotor Magnetic Shield, RMS, performance in HTS synchronous generators under stator winding short-circuit fault conditions. The induced eddy currents in different circumferential positions of the rotor magnetic shield along with associated Joule heating losses would be studied using 2-D time-stepping Finite Element Analysis, FEA. The investigation of Lorentz forces exerted on the magnetic shield during transient conditions has also been performed in this paper. The obtained results show that double line-to-ground fault is of the most importance among different types of short-circuit faults. It was revealed that when it comes to the design of the rotor magnetic shields, in addition to the eddy current distribution and the associated ohmic losses, two phase-to-ground fault should be taken into account since the produced electromagnetic forces in the time of fault conditions are more severe during double line-to-ground fault.

  8. Fusion energy in an inertial electrostatic confinement device using a magnetically shielded grid

    Energy Technology Data Exchange (ETDEWEB)

    Hedditch, John, E-mail: john.hedditch@sydney.edu.au; Bowden-Reid, Richard, E-mail: rbow3948@physics.usyd.edu.au; Khachan, Joe, E-mail: joe.khachan@sydney.edu.au [School of Physics, The University of Sydney, Sydney, New South Whales 2006 (Australia)

    2015-10-15

    Theory for a gridded inertial electrostatic confinement (IEC) fusion system is presented, which shows a net energy gain is possible if the grid is magnetically shielded from ion impact. A simplified grid geometry is studied, consisting of two negatively biased coaxial current-carrying rings, oriented such that their opposing magnetic fields produce a spindle cusp. Our analysis indicates that better than break-even performance is possible even in a deuterium-deuterium system at bench-top scales. The proposed device has the unusual property that it can avoid both the cusp losses of traditional magnetic fusion systems and the grid losses of traditional IEC configurations.

  9. Study of the radiation scattered and produced by concrete shielding of radiotherapy rooms and its effects on equivalent doses in patients' organs

    International Nuclear Information System (INIS)

    Braga, K.L.; Rebello, W.F.; Andrade, E.R.; Gavazza, S.; Medeiros, M.P.C.; Mendes, R.M.S.; Gomes, R.G.; Silva, M.G.; Thalhofer, J.L.; Silva, A.X.; Santos, R.F.G.

    2015-01-01

    Within a radiotherapy room, in addition to the primary beam, there is also secondary radiation due to the leakage of the accelerator head and the radiation scattering from room objects, patient and even the room's shielding itself, which is projected to protect external individuals disregarding its effects on the patient. This work aims to study the effect of concrete shielding wall over the patient, taking into account its contribution on equivalent doses. The MCNPX code was used to model the linear accelerator Varian 2100/2300 C/D operating at 18MeV, with MAX phantom representing the patient undergoing radiotherapy treatment for prostate cancer following Brazilian Institute of Cancer four-fields radiation application protocol (0°, 90°, 180° and 270°). Firstly, the treatment was patterned within a standard radiotherapy room, calculating the equivalent doses on patient's organs individually. In a second step, this treatment was modeled withdrawing the walls, floor and ceiling from the radiotherapy room, and then the equivalent doses calculated again. Comparing these results, it was found that the concrete has an average shielding contribution of around 20% in the equivalent dose on the patient's organs. (author)

  10. Observation of Various and Spontaneous Magnetic Skyrmionic Bubbles at Room Temperature in a Frustrated Kagome Magnet with Uniaxial Magnetic Anisotropy

    KAUST Repository

    Hou, Zhipeng

    2017-06-07

    The quest for materials hosting topologically protected skyrmionic spin textures continues to be fueled by the promise of novel devices. Although many materials have demonstrated the existence of such spin textures, major challenges remain to be addressed before devices based on magnetic skyrmions can be realized. For example, being able to create and manipulate skyrmionic spin textures at room temperature is of great importance for further technological applications because they can adapt to various external stimuli acting as information carriers in spintronic devices. Here, the first observation of skyrmionic magnetic bubbles with variable topological spin textures formed at room temperature in a frustrated kagome Fe3 Sn2 magnet with uniaxial magnetic anisotropy is reported. The magnetization dynamics are investigated using in situ Lorentz transmission electron microscopy, revealing that the transformation between different magnetic bubbles and domains is via the motion of Bloch lines driven by an applied external magnetic field. These results demonstrate that Fe3 Sn2 facilitates a unique magnetic control of topological spin textures at room temperature, making it a promising candidate for further skyrmion-based spintronic devices.

  11. Atom interferometry in space: Thermal management and magnetic shielding

    Energy Technology Data Exchange (ETDEWEB)

    Milke, Alexander; Kubelka-Lange, André; Gürlebeck, Norman, E-mail: norman.guerlebeck@zarm.uni-bremen.de; Rievers, Benny; Herrmann, Sven [Center of Applied Space Technology and Microgravity (ZARM), University Bremen, Am Fallturm, 28359 Bremen (Germany); Schuldt, Thilo [DLR Institute for Space Systems, Robert-Hooke-Str. 7, 28359 Bremen (Germany); Braxmaier, Claus [Center of Applied Space Technology and Microgravity (ZARM), University Bremen, Am Fallturm, 28359 Bremen (Germany); DLR Institute for Space Systems, Robert-Hooke-Str. 7, 28359 Bremen (Germany)

    2014-08-15

    Atom interferometry is an exciting tool to probe fundamental physics. It is considered especially apt to test the universality of free fall by using two different sorts of atoms. The increasing sensitivity required for this kind of experiment sets severe requirements on its environments, instrument control, and systematic effects. This can partially be mitigated by going to space as was proposed, for example, in the Spacetime Explorer and Quantum Equivalence Principle Space Test (STE-QUEST) mission. However, the requirements on the instrument are still very challenging. For example, the specifications of the STE-QUEST mission imply that the Feshbach coils of the atom interferometer are allowed to change their radius only by about 260 nm or 2.6 × 10{sup −4} % due to thermal expansion although they consume an average power of 22 W. Also Earth's magnetic field has to be suppressed by a factor of 10{sup 5}. We show in this article that with the right design such thermal and magnetic requirements can indeed be met and that these are not an impediment for the exciting physics possible with atom interferometers in space.

  12. Characterization of Magnetic Field Immersed Photomultipliers from Double Chooz Experiment. Design and Construction of their Magnetic Shields

    International Nuclear Information System (INIS)

    Valdivia Valero, F. J.

    2007-01-01

    Flavour oscillations of neutrinos are a quantum-mechanical effect widely demonstrated. It is explained through interferences of their mass eigenstates, therefore, belonging to the physical area beyond the Standard Model. This work deals with the CIEMAT collaboration in the neutrino experiment Double Chooz. Such an experiment aims to measure the mixture angle θ 1 3, one of the PMNS leptonic mixture matrix, with a un reached-before sensibility by decrease of systematic errors. For this, two identical scintillator detectors, equipped with PMT's, will be sited at different distances from two reactors located in the nuclear power plant CHOOZ B (France). The electronic neutrino flux from these reactors will be compared, explaining its deficit by flavour oscillations of these particles. The identity of both detectors will be diminished by the magnetic field effects on the PMT's response. Therefore, this study serves as for quantifying such an effects as for fitting the magnetic shields design that minimize them. Shielding measurements and final design of magnetic shields as much as the effect these ones cause in the PMT's response immersed in a monitored magnetic field are presented. (Author) 85 refs

  13. Ion-collecting sphere in a stationary, weakly magnetized plasma with finite shielding length

    International Nuclear Information System (INIS)

    Patacchini, Leonardo; Hutchinson, Ian H

    2007-01-01

    Collisionless ion collection by a negatively biased stationary spherical probe in a finite shielding length plasma is investigated using the Particle in Cell code SCEPTIC, in the presence of a weak magnetic field B. The overall effect of the magnetic field is to reduce the ion current, linearly in |B| for weak enough fields, with a slope steepness increasing with the electron Debye length. The angular current distribution and space-charge buildup strongly depend on the focusing properties of the probe, hence on its potential and the plasma shielding length. In particular, it is found that the concavity of the ion collection flux distribution can reverse sign when the electron Debye length is comparable to or larger than the probe radius (λ De ∼> r p ), provided the ion temperature is much lower than the probe bias (T i p )

  14. Thermal and flow considerations for the 80 K shield of the SSC magnet cryostats

    International Nuclear Information System (INIS)

    Abramovich, S.; Yuecel, A.; Demko, J.; Thirumaleshwar, M.

    1994-01-01

    The nominal temperatures in the SSC magnets range between 4.2 K in the superconducting coils and 300 K on the cryostat outer wall. To minimize the 4 K heat load, one thermal shield cooled by liquid and vapor nitrogen flows at 84 K, and another cooled by helium flow at 20 K are incorporated in the cryostat. Tubes attached to the shields serve as conduits for the cryogens. The liquid nitrogen tube in the cryostat is used for shield refrigeration and also for liquid distribution around the SSC rings. The second nitrogen line is used to return the vapor to the helium refrigerators for helium precooling. The nominal LN2 flow from a 4.3 km long cryogenic string (4 sections) to the surface is 64 g/s. The total liquid nitrogen consumption of approximately 5000 g/s will be supplied at one, two or more locations on the surface. The total heat load of the 80 K shield is estimated as 3.2 W/m: about 50% is composed of infrared radiation; the remaining 50% is by heat conduction through supports, vacuum barriers and other thermal connections between the shield and the 300 K outer wall. The required LN2 flow rate depends on the distribution and circulation schemes. The LN2 temperature will in turn vary depending on the flow rate and on the recooling method used. For example, with a massflow of 400 g/s of LN2 the temperature rises from 82 K to 86 K between two compact recoolers 1 km apart. This temperature is higher than desired. The temperature can be reduced by increasing the flow rate of the liquid or by using the continuous recooling scheme. This paper discusses some thermal problems caused by certain mechanical designs of the 80 K shield and the possible improvement by using continuous recooling. The authors present results of the 80 K shield temperature distribution analysis, the 20 K shield heat load augmentation resulting from the increased 80 K shield temperatures, the continuous nitrogen recooling scheme and some flow timing related analysis

  15. Electromagnetic shielding mechanisms using soft magnetic stainless steel fiber enabled polyester textiles

    Science.gov (United States)

    Shyr, Tien-Wei; Shie, Jing-Wen

    2012-11-01

    This work studied the effects of conductivity, magnetic loss, and complex permittivity when using blended textiles (SSF/PET) of polyester fibers (PET) with stainless steel fibers (SSF) on electromagnetic wave shielding mechanisms at electromagnetic wave frequencies ranging from 30 MHz to 1500 MHz. The 316L stainless steel fiber used in this study had 38 vol% γ austenite and 62 vol% α' martensite crystalline phases, which was characterized by an x-ray diffractometer. Due to the magnetic and dielectric loss of soft metallic magnetic stainless steel fiber enabled polyester textiles, the relationship between the reflection/absorption/transmission behaviors of the electromagnetic wave and the electrical/magnetic/dielectric properties of the SSF and SSF/PET fabrics was analyzed. Our results showed that the electromagnetic interference shielding of the SSF/PET textiles show an absorption-dominant mechanism, which attributed to the dielectric loss and the magnetic loss at a lower frequency and attributed to the magnetic loss at a higher frequency, respectively.

  16. Gauge origin independent calculations of nuclear magnetic shieldings in relativistic four-component theory

    DEFF Research Database (Denmark)

    Ilias, Miroslav; Saue, Trond; Enevoldsen, Thomas

    2009-01-01

    The use of perturbation-dependent London atomic orbitals, also called gauge including atomic orbitals, has proven efficient for calculations of NMR shielding constants and other magnetic properties in the nonrelativistic framework. In this paper, the theory of London atomic orbitals for NMR...... calculates the diamagnetic contribution as an expectation value, leads to significant errors and is not recommended. (C) 2009 American Institute of Physics. [doi:10.1063/1.3240198]...

  17. Low Frequency Plasma Oscillations in a 6-kW Magnetically Shielded Hall Thruster

    Science.gov (United States)

    Jorns, Benjamin A.; Hofery, Richard R.

    2013-01-01

    The oscillations from 0-100 kHz in a 6-kW magnetically shielded thruster are experimen- tally characterized. Changes in plasma parameters that result from the magnetic shielding of Hall thrusters have the potential to significantly alter thruster transients. A detailed investigation of the resulting oscillations is necessary both for the purpose of determin- ing the underlying physical processes governing time-dependent behavior in magnetically shielded thrusters as well as for improving thruster models. In this investigation, a high speed camera and a translating ion saturation probe are employed to examine the spatial extent and nature of oscillations from 0-100 kHz in the H6MS thruster. Two modes are identified at 8 kHz and 75-90 kHz. The low frequency mode is azimuthally uniform across the thruster face while the high frequency oscillation is concentrated close to the thruster centerline with an m = 1 azimuthal dependence. These experimental results are discussed in the context of wave theory as well as published observations from an unshielded variant of the H6MS thruster.

  18. Finalized configuration of magnetic shielding for LEReC cooling section

    Energy Technology Data Exchange (ETDEWEB)

    Seletskiy, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); De Monte, V. [Brookhaven National Lab. (BNL), Upton, NY (United States); Di Lieto, A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Fedotov, A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Mahler, G. [Brookhaven National Lab. (BNL), Upton, NY (United States); McIntyre, G. [Brookhaven National Lab. (BNL), Upton, NY (United States); Tuozzolo, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Weiss, D. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2017-11-20

    In the LEReC Cooling Section (CS) the RHIC ions are traveling together with and getting cooled by the LEReC electrons. The required cooling rate sets the limit of 150 urad on tolerable angles of the electrons in the CS. One of the components of overall electron angle is the angle of the e-beam trajectory with respect to the ion beam trajectory. We set the limit for electron trajectory angle to 100 urad. It is critical for preserving small trajectory angle to keep the transverse magnetic field inside the CS drifts within +/- 2.3 mG. The drifts in the CS must be shielded from the ambient magnetic fields of the RHIC tunnel, which can be as high as 0.5 G, to minimize the transverse field inside the CS vacuum chamber. In this paper we present the final design of the magnetic shielding of the LEReC CS and discuss the results of tests dedicated to studies of the shielding effectiveness.

  19. Characterisation of superconducting capillaries for magnetic shielding of twisted-wire pairs in a neutron electric dipole moment experiment

    Energy Technology Data Exchange (ETDEWEB)

    Henry, S., E-mail: s.henry@physics.ox.ac.uk; Pipe, M.; Cottle, A.; Clarke, C.; Divakar, U.; Lynch, A.

    2014-11-01

    The cryoEDM neutron electric dipole moment experiment requires a SQUID magnetometry system with pick-up loops inside a magnetically shielded volume connected to SQUID sensors by long (up to 2 m) twisted-wire pairs (TWPs). These wires run outside the main shield, and therefore must run through superconducting capillaries to screen unwanted magnetic pick-up. We show that the average measured transverse magnetic pick-up of a set of lengths of TWPs is equivalent to a loop area of 5.0×10{sup −6} m{sup 2}/m, or 14 twists per metre. From this we set the requirement that the magnetic shielding factor of the superconducting capillaries used in the cryoEDM system must be greater than 8.0×10{sup 4}. The shielding factor—the ratio of the signal picked-up by an unshielded TWP to that induced in a shielded TWP—was measured for a selection of superconducting capillaries made from solder wire. We conclude the transverse shielding factor of a uniform capillary is greater than 10{sup 7}. The measured pick-up was equal to, or less than that due to direct coupling to the SQUID sensor (measured without any TWP attached). We show that discontinuities in the capillaries substantially impair the magnetic shielding, yet if suitably repaired, this can be restored to the shielding factor of an unbroken capillary. We have constructed shielding assemblies for cryoEDM made from lengths of single core and triple core solder capillaries, joined by a shielded Pb cylinder, incorporating a heater to heat the wires above the superconducting transition as required.

  20. Evaluation of Superconducting Magnet Shield Configurations for Long Duration Manned Space Missions.

    Science.gov (United States)

    Ambroglini, Filippo; Battiston, Roberto; Burger, William J

    2016-01-01

    A manned mission to Mars would present an important long-term health risk to the crew members due to the prolonged exposure to the ionizing radiation of galactic cosmic-rays. The radiation levels would largely exceed those encountered in the Apollo missions. An increase in the passive shielding provided by the spacecraft implies a significant increase of the mass. The advent of superconducting magnets in the early 1960s was considered an attractive alternative. The technology allows to generate magnetic fields capable to deflect the cosmic-rays in a manner analogous to the reduction of the particle fluxes in the upper atmosphere due to the Earth's dipole magnetic field. A series of the three studies have been conducted over the last 5 years, funded successively by European Space Agency (ESA), the NASA Innovative Advanced Concepts (NIAC) program, and the Union European's Seventh Framework Programme (FP7). The shielding configurations studied are based on high-temperature superconductors, which eliminate the need to operate with liquid helium. The mass estimates of the coils and supporting structure of the engineering designs are based on the current and expected near-future performance of the superconducting materials. In each case, the shield performance, in terms of dose reduction, is provided by a 3-dimensional Monte Carlo simulation, which treats in detail the electromagnetic and hadronic interactions of the galactic-cosmic rays, and the secondary particles they produce in the materials of the shield and spacecraft. A summary of the results of the studies, representing one of the most detailed and comprehensive efforts made in the field, is presented.

  1. Helium leak testing of superconducting magnets, thermal shields and cryogenic lines of SST -1

    International Nuclear Information System (INIS)

    Thankey, P.L.; Joshi, K.S.; Semwal, P.; Pathan, F.S.; Raval, D.C.; Khan, Z.; Patel, R.J.; Pathak, H.A.

    2005-01-01

    Tokamak SST - 1 is under commissioning at Institute for Plasma Research. It comprises of a toroidal doughnut shaped plasma chamber, surrounded by liquid helium cooled superconducting magnets, housed in a cryostat chamber. The cryostat has two cooling circuits, (1) liquid nitrogen cooling circuit operating at 80 K to minimize the radiation heat load on the magnets, and (2) liquid helium cooling circuit to cool magnets and cold mass support structure to 4.5 K. In this paper we describe (a) the leak testing of copper - SS joints, brazing joints, interconnecting joints of the superconducting magnets, and (b) the leak testing of the liquid nitrogen cooling circuit, comprising of the main supply header, the thermal shields, interconnecting pipes, main return header and electrical isolators. All these tests were carried out using both vacuum and sniffer methods. (author)

  2. Additive manufacturing of magnetic shielding and ultra-high vacuum flange for cold atom sensors.

    Science.gov (United States)

    Vovrosh, Jamie; Voulazeris, Georgios; Petrov, Plamen G; Zou, Ji; Gaber, Youssef; Benn, Laura; Woolger, David; Attallah, Moataz M; Boyer, Vincent; Bongs, Kai; Holynski, Michael

    2018-01-31

    Recent advances in the understanding and control of quantum technologies, such as those based on cold atoms, have resulted in devices with extraordinary metrological performance. To realise this potential outside of a lab environment the size, weight and power consumption need to be reduced. Here we demonstrate the use of laser powder bed fusion, an additive manufacturing technique, as a production technique relevant to the manufacture of quantum sensors. As a demonstration we have constructed two key components using additive manufacturing, namely magnetic shielding and vacuum chambers. The initial prototypes for magnetic shields show shielding factors within a factor of 3 of conventional approaches. The vacuum demonstrator device shows that 3D-printed titanium structures are suitable for use as vacuum chambers, with the test system reaching base pressures of 5 ± 0.5 × 10 -10 mbar. These demonstrations show considerable promise for the use of additive manufacturing for cold atom based quantum technologies, in future enabling improved integrated structures, allowing for the reduction in size, weight and assembly complexity.

  3. Selective electrochemical extraction of REEs from NdFeB magnet waste at room temperature

    NARCIS (Netherlands)

    Venkatesan, P.; Vander Hoogerstraete, Tom; Hennebel, Tom; Binnemans, Koen; Sietsma, J.; Yang, Y.

    2018-01-01

    NdFeB magnet waste is one of the important secondary resources from which rare-earth elements (REEs) can be recovered. Herein we present an electrochemical route to selectively extract REEs from the magnet waste at room temperature. First, the magnet waste was partially leached with HCl. The

  4. Decontamination of the activation product based on a legal revision of the cyclotron vault room on the non-self-shield compact medical cyclotron

    International Nuclear Information System (INIS)

    Komiya, Isao; Umezu, Yoshiyuki; Fujibuchi, Toshiou; Nakamura, Kazumasa; Baba, Shingo; Honda, Hiroshi

    2016-01-01

    The non-self-shield compact medical cyclotron and the cyclotron vault room were in operation for 27 years. They have now been decommissioned. We efficiently implemented a technique to identify an activation product in the cyclotron vault room. Firstly, the distribution of radioactive concentrations in the concrete of the cyclotron vault room was estimated by calculation from the record of the cyclotron operation. Secondly, the comparison of calculated results with an actual measurement was performed using a NaI scintillation survey meter and a high-purity germanium detector. The calculated values were overestimated as compared to the values measured using the Nal scintillation survey meter and the high-purity germanium detector. However, it could limit the decontamination area. By simulating the activation range, we were able to minimize the concrete core sampling. Finally, the appropriate range of radioactivated area in the cyclotron vault room was decontaminated based on the results of the calculation. After decontamination, the radioactive concentration was below the detection limit value in all areas inside the cyclotron vault room. By these procedures, the decommissioning process of the cyclotron vault room was more efficiently performed. (author)

  5. Synthesis, characterization and magnetic properties of room-temperature nanofluid ferromagnetic graphite

    OpenAIRE

    Souza, N. S.; Sergeenkov, S.; Speglich, C.; Rivera, V. A. G.; Cardoso, C. A.; Pardo, H.; Mombru, A. W.; Rodrigues, A. D.; de Lima, O. F.; Araujo-Moreira, F. M.

    2009-01-01

    We report the chemical synthesis route, structural characterization, and physical properties of nanofluid magnetic graphite (NFMG) obtained from the previously synthesized bulk organic magnetic graphite (MG) by stabilizing the aqueous ferrofluid suspension with an addition of active cationic surfactant. The measured magnetization-field hysteresis curves along with the temperature dependence of magnetization confirmed room-temperature ferromagnetism in both MG and NFMG samples. (C) 2009 Americ...

  6. The magnetic vapour shield effect at divertor plates during plasma disruptions

    International Nuclear Information System (INIS)

    Piazza, G.; Goel, B.; Hoebel, W.; Wuerz, H.; Landman, I.

    1995-01-01

    Hard disruptions in a TOKAMAK cause a large thermal load on the divertor plates with an instantaneous ablation of a part of the heated material. The produced vapour cloud screens the plasma facing component from the direct interaction with the disrupting plasma (vapour shield effect). In order to quantify the damage to the divertor the magneto-hydrodynamic behaviour of the expanding vapour cloud has been investigated using an extended version of the 1-dimensional Lagrangian hydrodynamic code KATACO. Modelling of the magnetic field effects on the expanding plasma takes into account that the magnetic field is oblique to the divertor (1 1/2 dimensional model). The ''Radiation Heat Conduction Approximation'' has been used for describing the radiative energy transport. In this paper results are presented assuming graphite as divertor material, irradiated with a proton beam of an energy density of 12MJ/m 2 and a duration of 100μs. (orig.)

  7. Assembly and gap management strategy for the ITER NBI vessel passive magnetic shield

    Energy Technology Data Exchange (ETDEWEB)

    Ríos, Luis, E-mail: luis.rios@ciemat.es [CIEMAT Laboratorio Nacional de Fusión, Avda. Complutense 22, 28040 Madrid (Spain); Ahedo, Begoña; Alonso, Javier; Barrera, Germán; Cabrera, Santiago; Rincón, Esther; Ramos, Francisco [CIEMAT Laboratorio Nacional de Fusión, Avda. Complutense 22, 28040 Madrid (Spain); El-Ouazzani, Anass; Graceffa, Joseph; Urbani, Marc; Shah, Darshan [ITER Organization, Route de Vinon-sur-Verdon – CS 90 046, 13067 St Paul Lez Durance Cedex (France); Agarici, Gilbert [Fusion for Energy, Josep Pla 2, Torres Diagonal Litoral B3 – 07/08, 08019 Barcelona (Spain)

    2015-10-15

    The neutral beam system for ITER consists of two heating and current drive neutral ion beam injectors (HNB) and a diagnostic neutral beam (DNB) injector. The proposed physical plant layout allows a possible third HNB injector to be installed later. The HNB Passive Magnetic Shield (PMS) works in conjunction with the active compensation/correction coils to limit the magnetic field inside the Beam Line Vessel (BLV), Beam Source Vessel (BSV), High Voltage Bushing (HVB) and Transmission Line (TL) elbow to acceptable levels that do not interfere with the operation of the HNB components. This paper describes the current design of the PMS, having had only minor modifications since the preliminary design review (PDR) held in IO in April 2013, and the assembly strategy for the vessel PMS.

  8. Shielding of External Magnetic Perturbations By Torque In Rotating Tokamak Plasmas

    International Nuclear Information System (INIS)

    Park, Jong-Kyu; Boozer, Allen H.; Menard, Jonathan E.; Gerhardt, Stefan P.; Sabbagh, Steve A.

    2009-01-01

    The imposition of a nonaxisymmetric magnetic perturbation on a rotating tokamak plasma requires energy and toroidal torque. Fundamental electrodynamics implies that the torque is essentially limited and must be consistent with the external response of a plasma equilibrium (rvec f) = (rvec j) x (rvec B). Here magnetic measurements on National Spherical Torus eXperiment (NSTX) device are used to derive the energy and the torque, and these empirical evaluations are compared with theoretical calculations based on perturbed scalar pressure equilibria (rvec f) = (rvec (del))p coupled with the theory of nonambipolar transport. The measurement and the theory are consistent within acceptable uncertainties, but can be largely inconsistent when the torque is comparable to the energy. This is expected since the currents associated with the torque are ignored in scalar pressure equilibria, but these currents tend to shield the perturbation.

  9. Placed in a steady magnetic field, the flux density inside a permalloy-shielded volume decreases over hours and days

    Science.gov (United States)

    Feinberg, Benedict; Gould, Harvey

    2018-03-01

    Following the application of an external magnetic field to a thin-walled demagnetized Permalloy cylinder, the magnetic flux density at the center of the shielded volume decreases by roughly 20% over periods of hours to days. We measured this effect for applied magnetic fields from 0.48 A/m to 16 A/m, the latter being comparable to the Earths magnetic field at its weakest point. Delayed changes in magnetic flux density are also observed following alternating current demagnetization. We attribute these effects to delayed changes in magnetization, which have previously been observed in thin Permalloy films and small bulk samples of ferromagnetic materials. Phenomenological models of thermal activation are discussed. Some possible effects on experiments that rely on static shielding are noted.

  10. Hybrid Active-Passive Radiation Shielding System

    Data.gov (United States)

    National Aeronautics and Space Administration — A radiation shielding system is proposed that integrates active magnetic fields with passive shielding materials. The objective is to increase the shielding...

  11. Characterization of large-area photomultipliers under low magnetic fields: Design and performance of the magnetic shielding for the Double Chooz neutrino experiment

    International Nuclear Information System (INIS)

    Calvo, E.; Cerrada, M.; Fernandez-Bedoya, C.; Gil-Botella, I.; Palomares, C.; Rodriguez, I.; Toral, F.; Verdugo, A.

    2010-01-01

    A precise quantitative measurement of the effect of low magnetic fields in Hamamatsu R7081 photomultipliers has been performed. These large-area photomultipliers will be used in the Double Chooz neutrino experiment. A magnetic shielding has been developed for these photomultipliers. Its design and performance is also reported in this paper.

  12. A novel magnetic valve using room temperature magnetocaloric materials

    DEFF Research Database (Denmark)

    Eriksen, Dan; Bahl, Christian; Pryds, Nini

    2012-01-01

    changes. This is made possible by the strong temperature dependence of the magnetization close to the Curie temperature of the magnetocaloric materials. Different compositions of both La0.67(Ca,Sr)0.33MnO3 and La(Fe,Co,Si)13 have been considered for use in prototype valves. Based on measured magnetization...

  13. Measured surface magnetic field attenuation of shielded windows and wire mesh over an electrically small enclosure

    International Nuclear Information System (INIS)

    Hoeft, L.O.; Hofstra, J.S.; Karaskiewicz, R.J.; Wiser, G.

    1984-01-01

    The surface magnetic field attenuation of five types of shielded transparency (window) material was measured over the frequency range 10 kHz to 100 MHz by installing them on an .61 m x .61 m x .2 m enclosure, placing the enclosure on the wall of a TEM cell and measuring the surface and interior magnetic fields using a computer-controlled network analyzer system. The samples included two thicknesses of conductive grids on acrylic, hardware, cloth with 1/8 and 1/4-inch mesh, and a fine mesh laminated optical display window. These measurements are indicative of an enclosure with aperture coupling; namely, they become frequency-independent at high frequencies. Coarse mesh samples (1/8-1/4-inch mesh) were able to provide 50 to 60 dB of magnetic field reduction at tens of MHz, whereas the finer mesh did slightly better. This behavior is consistent with magnetic polarizability theory. Material thickness did not have an appreciable effect for frequencies above a MHz

  14. Re-evaluation of the shielding adequacy of the brachytherapy treatment room at Korle-Bu teaching hospital, Ghana

    International Nuclear Information System (INIS)

    Arwui, C. C.

    2009-06-01

    Staff and the general public's safety during the operation of the 137 Cs brachytherapy unit at the Korle Bu teaching hospital depends on the adequacy of the shielding of the facility. Shielding design of the brachytherapy unit at the hospital was based on postulated workload and postulated occupancy factors to critical locations at the facility where the public and staff may occupy. This facility has been in existence for the past twelve (12) years and has accumulated operational workload data which differs from the postulated one. A study was carried out to re-evaluate the integrity of the biological shielding of the 137 Cs brachytherapy unit. This study analyzed the accumulated workload data and used the information to perform shielding calculations to verify the adequacy of the biological shielding thicknesses to provide sufficient protection of staff and the public. Dose rate calculations were verified by measurements with calibrated dose rate meters. This provided the basis for determining the current state of protection and safety for staff and the general public. The results show that despite the variation in actual and postulated workloads, the dose rates were below the reference values of 0.5μSv/h for public areas and 7.5μSv/h for controlled areas. It was confirmed that the present shielding thickness of 535 mm can accommodate a high dose rate (HDR) 192 Ir source with activity in the range 370 - 570 GBq with an operational workload of 30 patients per week and an average treatment time of 10 minutes.

  15. Use of fusion-welding techniques in fabrication of a superconducting-magnet thermal-shield system

    International Nuclear Information System (INIS)

    Dalder, E.N.C.; Berkey, J.H.; Chang, Y.; Johnson, G.L.; Lathrop, G.H.; Podesta, D.L.; Van Sant, J.H.

    1983-01-01

    Success of the thermal shield system was demonstrated by the results of acceptance tests performed with the magnet and all its ancillary equipment. During these tests the thermal shield system was: (1) thermally cycled several times from 300 0 K to 77 0 K; (2) pressure cycled several times from 0 to 5 atmospheres; (3) operated for more than 500 hours at 77 0 K and in a vacuum environment of less than 10 - 5 torr; (4) operated in a magnetic field up to 6.0 Telsa; (5) exposed to a rapidly collapsing magnetic field of more than 250 gauss per second; (6) drained of all LN 2 in a few minutes, without any weld failures. The successful (and relatively problem free) operation of the magnet system validates the choice of the welding processes used, as well as their execution in both shop and field environments

  16. Modifications of the Fourier approach for magnetic field calculations to include axial shields in superconducting magnets

    International Nuclear Information System (INIS)

    Caldwell, J.

    1984-01-01

    Martinelli and Morini have used an analytical method for calculating values and distribution of the magnetic field in superconducting magnets. Using Fourier series the magnetic field is determined by carrying out a series expansion of the current density distribution of the system of coils. This Fourier method can be modified to include axial iron to a far greater accuracy (for finite permeability) by incorporating the image series approach of Caldwell and Zisserman. Also an exact solution can be obtained for the case of infinite permeability. A comparison of the results derived from the expansion of Martinelli and Morini with the exact solution of Caldwell and Zisserman shows excellent agreement for the iron-free case but the accuracy deteriorates as the permeability μ/sub z/ increases. The exact solution should be used for infinite permeability and also gives satisfactory results for permeability μ/sub z/ >100. A symmetric geometry is used throughout the communication for simplicity of presentation

  17. Structural setting and magnetic properties of pseudotachylyte in a deep crustal shear zone, western Canadian shield

    Science.gov (United States)

    Orlandini, O. F.; Mahan, K. H.; Brown, L. L.; Regan, S.; Williams, M. L.

    2012-12-01

    Seismic slip commonly produces pseudotachylytes, a glassy vein-filling substance that is typically interpreted as either a frictional melt or an ultra-triturated cataclasite. In either form, pseudotachylytes are commonly magnetite enriched, even in magnetite-free host rocks, and therefore are potentially useful as high fidelity recorders of natural magnetic fields at the time of slip in a wide array of lithologies. Pseudotachylytes generally have high magnetic susceptibility and thus should preserve the dominant field present as the material passes the Curie temperatures of magnetic minerals, primarily magnetite. Two potential sources have been proposed for the dominant magnetic field recorded: the earth's magnetic field at the time of slip or the temporary and orders of magnitude more intense field created by the presence of coseismic currents along the failure plane. Pseudotachylytes of the Cora Lake shear zone (CLsz) in the Athabasca Granulite Terrain, western Canadian shield, are consistently hosted in high strain ultramylonitic orthogneiss. Sinistral and extensional oblique-slip in the CLsz occurred at high-pressure granulite-grade conditions of ~1.0 GPa and >800°C and may have persisted to somewhat lower P-T conditions (~0.8 GPa, 700 °C) during ductile deformation. Pseudotachylyte-bearing slip surfaces have sinistral offset, matching the larger shear zone, and clasts of wall rock in the more brecciated veins display field evidence for ductile shear along the same plane prior to brittle failure. The presence of undeformed pseudotachylyte in kinematically compatible fracture arrays localized in ultramylonite indicates that brittle failure may have occurred in the waning stages of shear zone activity and at similar deep crustal conditions. Field-documented occurrences of pseudotachylyte include 2 cm-thick veins that run subparallel to mylonitic foliation and contain small flow-aligned clasts and large, heavily brecciated foliation-crosscutting zones up to

  18. Direct writing of room temperature and zero field skyrmion lattices by a scanning local magnetic field

    KAUST Repository

    Zhang, Senfu; Zhang, Junwei; Zhang, Qiang; Barton, Craig; Neu, Volker; Zhao, Yuelei; Hou, Zhipeng; Wen, Yan; Gong, Chen; Kazakova, Olga; Wang, Wenhong; Peng, Yong; Garanin, Dmitry A.; Chudnovsky, Eugene M.; Zhang, Xixiang

    2018-01-01

    Magnetic skyrmions are topologically protected nanoscale spin textures exhibiting fascinating physical behaviors. Recent observations of room temperature skyrmions in sputtered multilayer films are an important step towards their use in ultra-low power devices. Such practical applications prefer skyrmions to be stable at zero magnetic fields and room temperature. Here, we report the creation of skyrmion lattices in Pt/Co/Ta multilayers by a scanning local field using magnetic force microscopy tips. We also show that those newly created skyrmion lattices are stable at both room temperature and zero fields. Lorentz transmission electron microscopy measurements reveal that the skyrmions in our films are of Néel-type. To gain a deeper understanding of the mechanism behind the creation of a skyrmion lattice by the scanning of local fields, we perform micromagnetic simulations and find the experimental results to be in agreement with our simulation data. This study opens another avenue for the creation of skyrmion lattices in thin films.

  19. Direct writing of room temperature and zero field skyrmion lattices by a scanning local magnetic field

    Science.gov (United States)

    Zhang, Senfu; Zhang, Junwei; Zhang, Qiang; Barton, Craig; Neu, Volker; Zhao, Yuelei; Hou, Zhipeng; Wen, Yan; Gong, Chen; Kazakova, Olga; Wang, Wenhong; Peng, Yong; Garanin, Dmitry A.; Chudnovsky, Eugene M.; Zhang, Xixiang

    2018-03-01

    Magnetic skyrmions are topologically protected nanoscale spin textures exhibiting fascinating physical behaviors. Recent observations of room temperature skyrmions in sputtered multilayer films are an important step towards their use in ultra-low power devices. Such practical applications prefer skyrmions to be stable at zero magnetic fields and room temperature. Here, we report the creation of skyrmion lattices in Pt/Co/Ta multilayers by a scanning local field using magnetic force microscopy tips. We also show that those newly created skyrmion lattices are stable at both room temperature and zero fields. Lorentz transmission electron microscopy measurements reveal that the skyrmions in our films are of Néel-type. To gain a deeper understanding of the mechanism behind the creation of a skyrmion lattice by the scanning of local fields, we perform micromagnetic simulations and find the experimental results to be in agreement with our simulation data. This study opens another avenue for the creation of skyrmion lattices in thin films.

  20. Direct writing of room temperature and zero field skyrmion lattices by a scanning local magnetic field

    KAUST Repository

    Zhang, Senfu

    2018-03-29

    Magnetic skyrmions are topologically protected nanoscale spin textures exhibiting fascinating physical behaviors. Recent observations of room temperature skyrmions in sputtered multilayer films are an important step towards their use in ultra-low power devices. Such practical applications prefer skyrmions to be stable at zero magnetic fields and room temperature. Here, we report the creation of skyrmion lattices in Pt/Co/Ta multilayers by a scanning local field using magnetic force microscopy tips. We also show that those newly created skyrmion lattices are stable at both room temperature and zero fields. Lorentz transmission electron microscopy measurements reveal that the skyrmions in our films are of Néel-type. To gain a deeper understanding of the mechanism behind the creation of a skyrmion lattice by the scanning of local fields, we perform micromagnetic simulations and find the experimental results to be in agreement with our simulation data. This study opens another avenue for the creation of skyrmion lattices in thin films.

  1. Does apartment's distance to an in-built transformer room predict magnetic field exposure levels?

    Science.gov (United States)

    Huss, Anke; Goris, Kelly; Vermeulen, Roel; Kromhout, Hans

    2013-01-01

    It has been shown that magnetic field exposure in apartments located directly on top or adjacent to transformer rooms is higher compared with exposure in apartments located further away from the transformer rooms. It is unclear whether this also translates into exposure contrast among individuals living in these apartments. We performed spot measurements of magnetic fields in 35 apartments in 14 apartment buildings with an in-built transformer and additionally performed 24-h personal measurements in a subsample of 24 individuals. Apartments placed directly on top of or adjacent to a transformer room had on average exposures of 0.42 μT, apartments on the second floor on top of a transformer room, or sharing a corner or edge with the transformer room had 0.11 μT, and apartments located further away from the transformer room had levels of 0.06 μT. Personal exposure levels were approximately a factor 2 lower compared with apartment averages, but still showed exposure contrasts, but only for those individuals who live in the apartments directly on top or adjacent to a transformer room compared with those living further away, with 0.23 versus 0.06 μT for personal exposure when indoors, respectively. A classification of individuals into 'high' and 'low' exposed based on the location of their apartment within a building with an in-built transformer is possible and could be applied in future epidemiological studies.

  2. In-situ measurement of magnetic field gradient in a magnetic shield by a spin-exchange relaxation-free magnetometer

    International Nuclear Information System (INIS)

    Fang Jian-Cheng; Wang Tao; Li Yang; Cai Hong-Wei; Zhang Hong

    2015-01-01

    A method of measuring in-situ magnetic field gradient is proposed in this paper. The magnetic shield is widely used in the atomic magnetometer. However, there is magnetic field gradient in the magnetic shield, which would lead to additional gradient broadening. It is impossible to use an ex-situ magnetometer to measure magnetic field gradient in the region of a cell, whose length of side is several centimeters. The method demonstrated in this paper can realize the in-situ measurement of the magnetic field gradient inside the cell, which is significant for the spin relaxation study. The magnetic field gradients along the longitudinal axis of the magnetic shield are measured by a spin-exchange relaxation-free (SERF) magnetometer by adding a magnetic field modulation in the probe beam’s direction. The transmissivity of the cell for the probe beam is always inhomogeneous along the pump beam direction, and the method proposed in this paper is independent of the intensity of the probe beam, which means that the method is independent of the cell’s transmissivity. This feature makes the method more practical experimentally. Moreover, the AC-Stark shift can seriously degrade and affect the precision of the magnetic field gradient measurement. The AC-Stark shift is suppressed by locking the pump beam to the resonance of potassium’s D1 line. Furthermore, the residual magnetic fields are measured with σ + - and σ – -polarized pump beams, which can further suppress the effect of the AC-Stark shift. The method of measuring in-situ magnetic field gradient has achieved a magnetic field gradient precision of better than 30 pT/mm. (paper)

  3. Electrical detection of single magnetic skyrmion at room temperature

    Directory of Open Access Journals (Sweden)

    Riccardo Tomasello

    2017-05-01

    Full Text Available This paper proposes a protocol for the electrical detection of a magnetic skyrmion via the change of the tunneling magnetoresistive (TMR signal in a three-terminal device. This approach combines alternating spin-transfer torque from both spin-filtering (due to a perpendicular polarizer and spin-Hall effect with the TMR signal. Micromagnetic simulations, used to test and verify such working principle, show that there exists a frequency region particularly suitable for this achievement. This result can be at the basis of the design of a TMR based read-out for skyrmion detection, overcoming the difficulties introduced by the thermal drift of the skyrmion once nucleated.

  4. Determination of the exposure speed of radiation emitted by the linear accelerator, using the code MCNP5 to evaluate the radiotherapy room shields of ABC Hospital

    International Nuclear Information System (INIS)

    Corral B, J. R.

    2015-01-01

    Humans should avoid exposure to radiation, because the consequences are harmful to health. Although there are different emission sources of radiation, generated by medical devices they are usually of great interest, since people who attend hospitals are exposed in one way or another to ionizing radiation. Therefore, is important to conduct studies on radioactive levels that are generated in hospitals, as a result of the use of medical equipment. To determine levels of exposure speed of a radioactive facility there are different methods, including the radiation detector and computational method. This thesis uses the computational method. With the program MCNP5 was determined the speed of the radiation exposure in the radiotherapy room of Cancer Center of ABC Hospital in Mexico City. In the application of computational method, first the thicknesses of the shields were calculated, using variables as: 1) distance from the shield to the source; 2) desired weekly equivalent dose; 3) weekly total dose equivalent emitted by the equipment; 4) occupation and use factors. Once obtained thicknesses, we proceeded to model the bunker using the mentioned program. The program uses the Monte Carlo code to probabilistic ally determine the phenomena of interaction of radiation with the shield, which will be held during the X-ray emission from the linear accelerator. The results of computational analysis were compared with those obtained experimentally with the detection method, for which was required the use of a Geiger-Muller counter and the linear accelerator was programmed with an energy of 19 MV with 500 units monitor positioning the detector in the corresponding boundary. (Author)

  5. Improvement of the Magnetic Shielding Effects by the Superposition of a Multi-Layered Ferromagnetic Cylinder over an HTS Cylinder: Relationship Between the Shielding Effects and the Layer Number of the Ferromagnetic Cylinder

    International Nuclear Information System (INIS)

    Yasui, K; Tarui, Y; Itoh, M

    2006-01-01

    The idealized magnetic shielded vessel can be realized by making use of a high-critical temperature superconductor (HTS). It is difficult for practical applications, however, to fabricate a shielding vessel that has a high value of the maximum shielded magnetic flux density B s0 . The present authors have improved the value of B s0 for the Bi-Pb-Sr-Ca-Cu-O (BPSCCO) cylinder used as the shielding vessel, by the superposition of a four-layered softiron cylinder over the BPSCCO cylinder, termed the four-layered superimposed cylinder. The B s4 value of 610 x 10 -4 T for the four-layered superimposed cylinder, is found to be about 4 times larger than that of a single-BPSCCO cylinder, and is theoretically analyzed by use of a new analysis method. The experimental values of the maximum shielded magnetic flux density B sn of n-layered superimposed cylinders are found to agree well with those of the theoretical analysis. Experimental results revealed several characteristics of the magnetic shielding within the n-layered superimposed cylinders. Also discussed is the new analysis method for the relationship between the n and B sn

  6. Review on numerical modeling of active magnetic regenerators for room temperature applications

    DEFF Research Database (Denmark)

    Nielsen, Kaspar Kirstein; Tusek, Jaka; Engelbrecht, Kurt

    2011-01-01

    The active magnetic regenerator (AMR) is an alternative refrigeration cycle with a potential gain of energy efficiency compared to conventional refrigeration techniques. The AMR poses a complex problem of heat transfer, fluid dynamics and magnetic fields, which requires detailed and robust modeling....... This paper reviews the existing numerical modeling of room temperature AMR to date. The governing equations, implementation of the magnetocaloric effect (MCE), fluid flow and magnetic field profiles, thermal conduction etc. are discussed in detail as is their impact on the AMR cycle. Flow channeling effects...

  7. Hafnium Films and Magnetic Shielding for TIME, A mm-Wavelength Spectrometer Array

    Science.gov (United States)

    Hunacek, J.; Bock, J.; Bradford, C. M.; Butler, V.; Chang, T.-C.; Cheng, Y.-T.; Cooray, A.; Crites, A.; Frez, C.; Hailey-Dunsheath, S.; Hoscheit, B.; Kim, D. W.; Li, C.-T.; Marrone, D.; Moncelsi, L.; Shirokoff, E.; Steinbach, B.; Sun, G.; Trumper, I.; Turner, A.; Uzgil, B.; Weber, A.; Zemcov, M.

    2018-04-01

    TIME is a mm-wavelength grating spectrometer array that will map fluctuations of the 157.7-μm emission line of singly ionized carbon ([CII]) during the epoch of reionization (redshift z ˜ 5-9). Sixty transition-edge sensor (TES) bolometers populate the output arc of each of the 32 spectrometers, for a total of 1920 detectors. Each bolometer consists of gold absorber on a ˜ 3 × 3 mm silicon nitride micro-mesh suspended near the corners by 1 × 1 × 500 μm silicon nitride legs targeting a photon-noise-dominated NEP ˜ 1 × 10^{-17} W/√{Hz} . Hafnium films are explored as a lower-T_c alternative to Ti (500 mK) for TIME TESs, allowing thicker support legs for improved yield. Hf T_c is shown to vary between 250 and 450 mK when varying the resident Ar pressure during deposition. Magnetic shielding designs and simulations are presented for the TIME first-stage SQUIDs. Total axial field suppression is predicted to be 5 × 10^7.

  8. Calculations of atomic magnetic nuclear shielding constants based on the two-component normalized elimination of the small component method

    Science.gov (United States)

    Yoshizawa, Terutaka; Zou, Wenli; Cremer, Dieter

    2017-04-01

    A new method for calculating nuclear magnetic resonance shielding constants of relativistic atoms based on the two-component (2c), spin-orbit coupling including Dirac-exact NESC (Normalized Elimination of the Small Component) approach is developed where each term of the diamagnetic and paramagnetic contribution to the isotropic shielding constant σi s o is expressed in terms of analytical energy derivatives with regard to the magnetic field B and the nuclear magnetic moment 𝝁 . The picture change caused by renormalization of the wave function is correctly described. 2c-NESC/HF (Hartree-Fock) results for the σiso values of 13 atoms with a closed shell ground state reveal a deviation from 4c-DHF (Dirac-HF) values by 0.01%-0.76%. Since the 2-electron part is effectively calculated using a modified screened nuclear shielding approach, the calculation is efficient and based on a series of matrix manipulations scaling with (2M)3 (M: number of basis functions).

  9. Development of a highly sensitive current and position monitor with HTS squids and an HTS magnetic shield

    International Nuclear Information System (INIS)

    Watanabe, T.; Ikeda, T.; Kase, M.; Yano, Y.; Watanabe, S.; Sasaki, Y.; Kawaguchi, T.

    2005-01-01

    A highly sensitive current and position monitor with HTS (High-Temperature Superconducting) SQUIDs (Superconducting QUantum Interference Device) and an HTS magnetic shield for the measurement of the intensity of faint beams, such as a radioisotope beam, has been developed for the RIKEN RI beam factory project. The HTS magnetic shield and the HTS current sensor including the HTS SQUID are cooled by a low-vibration pulse-tube refrigerator. Both the HTS magnetic shield and the HTS current sensor were fabricated by dip-coating a thin Bi 2 -Sr 2 -Ca 2 -Cu 3 -O x (Bi-2223) layer on 99.9% MgO ceramic substrates. The HTS technology enables us to develop a system equipped with a downsized and highly sensitive current monitor. Recently, a prototype system was completed and installed in the beam transport line of the RIKEN Ring Cyclotron to measure the DC-current of high-energy heavy-ion beams. As a result, we succeeded in measuring the intensity of the 600 nA 40 Ar 17+ beam (95 MeV/u). We describe the present status of the monitor system and the results of the beam measurements. (author)

  10. The Active Muon Shield

    CERN Document Server

    Bezshyiko, Iaroslava

    2016-01-01

    In the SHiP beam-dump of the order of 1011 muons will be produced per second. An active muon-shield is used to magnetically deflect these muons out of the acceptance of the spectrom- eter. This note describes how this shield is modelled and optimized. The SHiP spectrometer is being re-optimized using a conical decay-vessel, and utilizing the possibility to magnetize part of the beam-dump shielding iron. A shield adapted to these new conditions is presented which is significantly shorter and lighter than the shield used in the Technical Proposal (TP), while showing a similar performance.

  11. Material shielding of power frequency magnetic fields: Research and testing results from the EPRI Power Delivery Center-Lenox. Final report

    International Nuclear Information System (INIS)

    Anderson, C.B.

    1998-06-01

    Extensive investigations of a variety of material shielding methods have been performed at the EPRI Power Delivery Center--Lenox, Massachusetts. This work is part of a larger shielding investigation being done for EPRI by Electric Research and Management, Inc. (ERM) as part of the Magnetic Field Management Target in the EPRI Environment Group. Part of this work, involving cylinders of material, is to be included in a shielding handbook being prepared by ERM. Material shielding tests, not included in the handbook, as well as additional material shielding research, including testing, analyses, and computer simulations performed at the EPRI Power Delivery Center--Lenox are documented here. One of the major complications of using materials to shield magnetic fields is the mathematical complexity of the phenomenon involved. The result is that analytical solutions exist only for a very small number of simple geometries such as spheres, infinitely long cylinders, and infinite sheets. In practice, the materials typically come in the form of sheets. At present, there are no analytical methods for directly determining the shielding effectiveness of finite sheets of material, however, EPRI is sponsoring work in this area. There are some methods based on conformal mapping which can provide a solution for simple two-dimensional sheets. While such methods are useful in gaining insight into the mechanisms of shielding, they are not realistic enough to provide accurate shielding estimates. Empirical techniques are still required to determine the shielding effectiveness of material sheets. The material shielding tests and computer simulations are described in the report. The results of these tests and simulations have been used to develop a number of material shielding design rules for use in practical applications

  12. Radiation shielding lead shield

    International Nuclear Information System (INIS)

    Dei, Shoichi.

    1991-01-01

    The present invention concerns lead shields for radiation shielding. Shield boxes are disposed so as to surround a pipeline through which radioactive liquids, mists or like other objects are passed. Flanges are formed to each of the end edges of the shield boxes and the shield boxes are connected to each other by the flanges. Upon installation, empty shield boxes not charged with lead particles and iron plate shields are secured at first at the periphery of the pipeline. Then, lead particles are charged into the shield boxes. This attains a state as if lead plate corresponding to the depth of the box is disposed. Accordingly, operations for installation, dismantling and restoration can be conducted in an empty state with reduced weight to facilitate the operations. (I.S.)

  13. WE-G-17A-09: Novel Magnetic Shielding Design for Inline and Perpendicular Integrated 6 MV Linac and 1.0 T MRI Systems

    Energy Technology Data Exchange (ETDEWEB)

    Li, X; Ma, B; Kuang, Y [University of Nevada, Las Vegas, Las Vegas, NV (United States); Diao, X [Shenzhen University, Shenzhen, Guangdong (China)

    2014-06-15

    Purpose: The influence of fringe magnetic fields delivered by magnetic resonance imaging (MRI) on the beam generation and transportation in Linac is still a major challenge for the integration of linear accelerator and MRI (Linac-MRI). In this study, we investigated an optimal magnetic shielding design for Linac-MRI and further characterized the beam trajectory in electron gun. Methods: Both inline and perpendicular configurations were analyzed in this study. The configurations, comprising a Linac-MRI with a 100cm SAD and an open 1.0 T superconductive magnet, were simulated by the 3D finite element method (FEM). The steel shielding around the Linac was included in the 3D model, the thickness of which was varied from 1mm to 20mm, and magnetic field maps were acquired with and without additional shielding. The treatment beam trajectory in electron gun was evaluated using OPERA 3d SCALA with and without shielding cases. Results: When Linac was not shielded, the uniformity of diameter sphere volume (DSV) (30cm) was about 5 parts per million (ppm) and the fringe magnetic fields in electron gun were more than 0.3 T. With shielding, the magnetic fields in electron gun were reduced to less than 0.01 T. For the inline configuration, the radial magnetic fields in the Linac were about 0.02T. A cylinder steel shield used (5mm thick) altered the uniformity of DSV to 1000 ppm. For the perpendicular configuration, the Linac transverse magnetic fields were more than 0.3T, which altered the beam trajectory significantly. A 8mm-thick cylinder steel shield surrounding the Linac was used to compensate the output losses of Linac, which shifted the magnetic fields' uniformity of DSV to 400 ppm. Conclusion: For both configurations, the Linac shielding was used to ensure normal operation of the Linac. The effect of magnetic fields on the uniformity of DSV could be modulated by the shimming technique of the MRI magnet. NIH/NIGMS grant U54 GM104944, Lincy Endowed Assistant

  14. WE-G-17A-09: Novel Magnetic Shielding Design for Inline and Perpendicular Integrated 6 MV Linac and 1.0 T MRI Systems

    International Nuclear Information System (INIS)

    Li, X; Ma, B; Kuang, Y; Diao, X

    2014-01-01

    Purpose: The influence of fringe magnetic fields delivered by magnetic resonance imaging (MRI) on the beam generation and transportation in Linac is still a major challenge for the integration of linear accelerator and MRI (Linac-MRI). In this study, we investigated an optimal magnetic shielding design for Linac-MRI and further characterized the beam trajectory in electron gun. Methods: Both inline and perpendicular configurations were analyzed in this study. The configurations, comprising a Linac-MRI with a 100cm SAD and an open 1.0 T superconductive magnet, were simulated by the 3D finite element method (FEM). The steel shielding around the Linac was included in the 3D model, the thickness of which was varied from 1mm to 20mm, and magnetic field maps were acquired with and without additional shielding. The treatment beam trajectory in electron gun was evaluated using OPERA 3d SCALA with and without shielding cases. Results: When Linac was not shielded, the uniformity of diameter sphere volume (DSV) (30cm) was about 5 parts per million (ppm) and the fringe magnetic fields in electron gun were more than 0.3 T. With shielding, the magnetic fields in electron gun were reduced to less than 0.01 T. For the inline configuration, the radial magnetic fields in the Linac were about 0.02T. A cylinder steel shield used (5mm thick) altered the uniformity of DSV to 1000 ppm. For the perpendicular configuration, the Linac transverse magnetic fields were more than 0.3T, which altered the beam trajectory significantly. A 8mm-thick cylinder steel shield surrounding the Linac was used to compensate the output losses of Linac, which shifted the magnetic fields' uniformity of DSV to 400 ppm. Conclusion: For both configurations, the Linac shielding was used to ensure normal operation of the Linac. The effect of magnetic fields on the uniformity of DSV could be modulated by the shimming technique of the MRI magnet. NIH/NIGMS grant U54 GM104944, Lincy Endowed Assistant

  15. Study of geometries of active magnetic regenerators for room temperature magnetocaloric refrigeration

    DEFF Research Database (Denmark)

    Lei, Tian; Engelbrecht, Kurt; Nielsen, Kaspar Kirstein

    2017-01-01

    Room temperature magnetic refrigeration has attracted substantial attention during the past decades and continuing to increase the performance of active magnetic regenerators (AMR) is of great interest. Optimizing the regenerator geometry and related operating parameters is a practical and effect......Room temperature magnetic refrigeration has attracted substantial attention during the past decades and continuing to increase the performance of active magnetic regenerators (AMR) is of great interest. Optimizing the regenerator geometry and related operating parameters is a practical...... and effective way to obtain the desired cooling performance. To investigate how to choose and optimize the AMR geometry, a quantitative study is presented by simulations based on a one-dimensional (1D) numerical model. Correlations for calculating the friction factor and heat transfer coefficient are reviewed...... and chosen for modeling different geometries. Moreover, the simulated impacts of various parameters on the regenerator efficiency with a constant specific cooling capacity are presented. An analysis based on entropy production minimization reveals how those parameters affect the main losses occurring inside...

  16. Magnetic refrigeration at room temperature - from magnetocaloric materials to a prototype

    DEFF Research Database (Denmark)

    Kuhn, Luise Theil; Pryds, Nini; Bahl, Christian Robert Haffenden

    2011-01-01

    Based on the magnetocaloric effect, magnetic refrigeration at room temperature has for the past decade been a promising, environmentally friendly new energy technology predicted to have a significantly higher efficiency than the present conventional methods. However, so far only a few prototype...... refrigeration machines have been presented worldwide and there are still many scientific and technological challenges to be overcome. We report here on the MagCool project, which spans all the way from basic materials studies to the construction of a prototype. Emphasis has been on ceramic magnetocaloric...... materials, their shaping and graded composition for technological use. Modelling the performance of a permanent magnet with optimum use of the flux and relatively low weight, and designing and constructing a prototype continuous magnetic refrigeration device have also been major tasks in the project...

  17. Magnetic refrigeration at room temperature - from magnetocaloric materials to a prototype

    International Nuclear Information System (INIS)

    Kuhn, L Theil; Pryds, N; Bahl, C R H; Smith, A

    2011-01-01

    Based on the magnetocaloric effect, magnetic refrigeration at room temperature has for the past decade been a promising, environmentally friendly new energy technology predicted to have a significantly higher efficiency than the present conventional methods. However, so far only a few prototype refrigeration machines have been presented worldwide and there are still many scientific and technological challenges to be overcome. We report here on the MagCool project, which spans all the way from basic materials studies to the construction of a prototype. Emphasis has been on ceramic magnetocaloric materials, their shaping and graded composition for technological use. Modelling the performance of a permanent magnet with optimum use of the flux and relatively low weight, and designing and constructing a prototype continuous magnetic refrigeration device have also been major tasks in the project.

  18. Recuperation of ISR Dipole Magnet Yokes for Use as Shielding for the LHC Beam Dumps TDE

    CERN Document Server

    Ross, M

    1999-01-01

    The quantity of iron shielding required for two LHC dumps was estimated at about 1500 tons. Possible sources of slightly irradiated iron shielding were considered, in particular, the ISR dipole yokes, which were stocked in the I2. Of rectangular form and weighing 22 tons each, they were well suited to the LHC dump geometry. Furthermore, they were to all intents and purposes non-radioactive. The preferred solution was to cut off four lifting pads and three support plates using arc/air equipment, seal temporarily each end with shutters, fit two lifting "anchor" pins, and fill with concrete.

  19. Room Temperature Magnetic Determination of the Current Center Line for the ITER TF Coils

    CERN Document Server

    Lerch, Philippe; Buzio, Marco; Negrazus, Marco; Baynham, Elwyn; Sanfilippo, Stephane; Foussat, Arnaud

    2014-01-01

    The ITER tokamak includes 18 superconducting D-shaped toroidal field (IT) coils. Unavoidable shape deformations as well as assembly errors will lead to field errors, which can be modeled with the knowledge of the current center line (CCL). Accurate survey during the entire manufacturing and assembly process, including transfer of survey points, is complex. In order to increase the level of confidence, a room temperature magnetic measurement of the CCL on assembled and closed winding packs is foreseen, prior to insertion into their cold case. In this contribution, we discuss the principle of the CCL determination and present a low frequency ac measurement system under development at PSI, within an ITER framework contract. The largest current allowed to flow in the TF coil at room temperature and the precision requirements for the determination of the CCL loci of the coil are hard boundaries. Eddy currents in the radial plates, the winding pack enclosures, and possibly from iron in the reinforced concrete floor...

  20. Magnetic properties of CoP alloys electrodeposited at room temperature

    International Nuclear Information System (INIS)

    Lucas, I.; Perez, L.; Aroca, C.; Sanchez, P.; Lopez, E.; Sanchez, M.C.

    2005-01-01

    CoP alloys have been electrodeposited at room temperature from electrolytes with different pH values and their magnetic properties have been studied. Cracks and fractures appear when using stiff substrates, showing that high internal stresses, due to hydrogen evolution, are involved in the electrodeposition process. Samples electrodeposited onto flexible substrates do not show cracks on the surface. We also report an increment in the coercivity of the alloys when the pH of the electrolyte decreases, and therefore, the hydrogen evolution and the internal stresses increase

  1. Investigation of shape, position, and permeability of shielding material in quadruple butterfly coil for focused transcranial magnetic stimulation

    Science.gov (United States)

    Rastogi, Priyam; Zhang, Bowen; Tang, Yalun; Lee, Erik G.; Hadimani, Ravi L.; Jiles, David C.

    2018-05-01

    Transcranial magnetic stimulation has been gaining popularity in the therapy for several neurological disorders. A time-varying magnetic field is used to generate electric field in the brain. As the development of TMS methods takes place, emphasis on the coil design increases in order to improve focal stimulation. Ideally reduction of stimulation of neighboring regions of the target area is desired. This study, focused on the improvement of the focality of the Quadruple Butterfly Coil (QBC) with supplemental use of different passive shields. Parameters such as shape, position and permeability of the shields have been explored to improve the focus of stimulation. Results have been obtained with the help of computer modelling of a MRI derived heterogeneous head model over the vertex position and the dorsolateral prefrontal cortex position using a finite element tool. Variables such as maximum electric field induced on the grey matter and scalp, volume and area of stimulation above half of the maximum value of electric field on the grey matter, and ratio of the maximum electric field in the brain versus the scalp have been investigated.

  2. Numerical modelling and analysis of a room temperature magnetic refrigeration system

    DEFF Research Database (Denmark)

    Petersen, Thomas Frank

    This thesis presents a two-dimensional mathematical model of an Active Magnetic Regenerator (AMR) system which is used for magnetic refrigeration at room temperature. The purpose of the model is to simulate a laboratory-scale AMR constructed at Risø National Laboratory. The AMR model geometry....... The AMR performs a cyclic process, and to simulate the AMR refrigeration cycle the model starts from an initial temperature distribution in the regenerator and fluid channel and takes time steps forward in time until the cyclical steady-state is obtained. The model can therefore be used to study both...... transient and steady-state phenomena. The AMR performance can be evaluated in terms of the no-load temperature span as well as the refrigeration capacity and the COP. The AMR model was verified extensively and it was concluded that the model has energy conservation and that the solution is independent...

  3. Lateral spin transfer torque induced magnetic switching at room temperature demonstrated by x-ray microscopy

    Science.gov (United States)

    Buhl, M.; Erbe, A.; Grebing, J.; Wintz, S.; Raabe, J.; Fassbender, J.

    2013-10-01

    Changing and detecting the orientation of nanomagnetic structures, which can be used for durable information storage, needs to be developed towards true nanoscale dimensions for keeping up the miniaturization speed of modern nanoelectronic components. Therefore, new concepts for controlling the state of nanomagnets are currently in the focus of research in the field of nanoelectronics. Here, we demonstrate reproducible switching of a purely metallic nanopillar placed on a lead that conducts a spin-polarized current at room temperature. Spin diffusion across the metal-metal (Cu to CoFe) interface between the pillar and the lead causes spin accumulation in the pillar, which may then be used to set the magnetic orientation of the pillar. In our experiments, the detection of the magnetic state of the nanopillar is performed by direct imaging via scanning transmission x-ray microscopy (STXM).

  4. On the room temperature multiferroic BiFeO3: magnetic, dielectric and thermal properties

    Science.gov (United States)

    Lu, J.; Günther, A.; Schrettle, F.; Mayr, F.; Krohns, S.; Lunkenheimer, P.; Pimenov, A.; Travkin, V. D.; Mukhin, A. A.; Loidl, A.

    2010-06-01

    Magnetic dc susceptibility between 1.5 and 800 K, ac susceptibility and magnetization, thermodynamic properties, temperature dependence of radio and audio-wave dielectric constants and conductivity, contact-free dielectric constants at mm-wavelengths, as well as ferroelectric polarization are reported for single crystalline BiFeO3. A well developed anomaly in the magnetic susceptibility signals the onset of antiferromagnetic order close to 635 K. Beside this anomaly no further indications of phase or glass transitions are indicated in the magnetic dc and ac susceptibilities down to the lowest temperatures. The heat capacity has been measured from 2 K up to room temperature and significant contributions from magnon excitations have been detected. From the low-temperature heat capacity an anisotropy gap of the magnon modes of the order of 6 meV has been determined. The dielectric constants measured in standard two-point configuration are dominated by Maxwell-Wagner like effects for temperatures T > 300 K and frequencies below 1 MHz. At lower temperatures the temperature dependence of the dielectric constant and loss reveals no anomalies outside the experimental errors, indicating neither phase transitions nor strong spin phonon coupling. The temperature dependence of the dielectric constant was measured contact free at microwave frequencies. At room temperature the dielectric constant has an intrinsic value of 53. The loss is substantial and strongly frequency dependent indicating the predominance of hopping conductivity. Finally, in small thin samples we were able to measure the ferroelectric polarization between 10 and 200 K. The saturation polarization is of the order of 40 μC/cm2, comparable to reports in literature.

  5. Design of a Laboratory Hall Thruster with Magnetically Shielded Channel Walls, Phase III: Comparison of Theory with Experiment

    Science.gov (United States)

    Mikellides, Ioannis G.; Katz, Ira; Hofer, Richard R.; Goebel, Dan M.

    2012-01-01

    A proof-of-principle effort to demonstrate a technique by which erosion of the acceleration channel in Hall thrusters of the magnetic-layer type can be eliminated has been completed. The first principles of the technique, now known as "magnetic shielding," were derived based on the findings of numerical simulations in 2-D axisymmetric geometry. The simulations, in turn, guided the modification of an existing 6-kW laboratory Hall thruster. This magnetically shielded (MS) thruster was then built and tested. Because neither theory nor experiment alone can validate fully the first principles of the technique, the objective of the 2-yr effort was twofold: (1) to demonstrate in the laboratory that the erosion rates can be reduced by >order of magnitude, and (2) to demonstrate that the near-wall plasma properties can be altered according to the theoretical predictions. This paper concludes the demonstration of magnetic shielding by reporting on a wide range of comparisons between results from numerical simulations and laboratory diagnostics. Collectively, we find that the comparisons validate the theory. Near the walls of the MS thruster, theory and experiment agree: (1) the plasma potential has been sustained at values near the discharge voltage, and (2) the electron temperature has been lowered by at least 2.5-3 times compared to the unshielded (US) thruster. Also, based on carbon deposition measurements, the erosion rates at the inner and outer walls of the MS thruster are found to be lower by at least 2300 and 1875 times, respectively. Erosion was so low along these walls that the rates were below the resolution of the profilometer. Using a sputtering yield model with an energy threshold of 25 V, the simulations predict a reduction of 600 at the MS inner wall. At the outer wall ion energies are computed to be below 25 V, for which case we set the erosion to zero in the simulations. When a 50-V threshold is used the computed ion energies are below the threshold at both

  6. Theoretical Study of H/D Isotope Effects on Nuclear Magnetic Shieldings Using an ab initio Multi-Component Molecular Orbital Method

    Directory of Open Access Journals (Sweden)

    Masanori Tachikawa

    2013-05-01

    Full Text Available We have theoretically analyzed the nuclear quantum effect on the nuclear magnetic shieldings for the intramolecular hydrogen-bonded systems of σ-hydroxy acyl aromatic species using the gauge-including atomic orbital technique combined with our multi-component density functional theory. The effect of H/D quantum nature for geometry and nuclear magnetic shielding changes are analyzed. Our study clearly demonstrated that the geometrical changes of hydrogen-bonds induced by H/D isotope effect (called geometrical isotope effect: GIE is the dominant factor of deuterium isotope effect on 13C chemical shift.

  7. Influence of particle size on the magnetic spectrum of NiCuZn ferrites for electromagnetic shielding applications

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Xiaohan; Yan, Shuoqing; Liu, Weihu [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, Hubei (China); Feng, Zekun, E-mail: fengzekun@mail.hust.edu.cn [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, Hubei (China); Chen, Yajie; Harris, Vincent G. [Center for Microwave Magnetic Materials and Integrated Circuits, and Department of Electrical and Computer Engineering, Northeastern University, Boston, MA 02115 (United States)

    2016-03-01

    The effect of ferrite particle size on the magnetic spectra (1 MHz to 1 GHz) of NiCuZn polycrystalline ferrites doped with Co{sub 2}O{sub 3} and Bi{sub 2}O{sub 3} were systematically investigated. The experiments indicate that the ferrite particle size tailored by grinding time and corresponding sintering temperatures is crucial to achieving high permeability, high Q-factor and low magnetic loss, at 13.56 MHz for electromagnetic shielding applications especially in the near field communication (NFC) field. It is evident that high-performance NiZnCu ferrite materials are strongly tailored by morphology and microstructure. It is conclusive that fine ferrite particles and relatively low sintering temperatures are favorable to lowering magnetic loss and enhancing permeability. This work has built a foundation for improvement of the ferrite slurry used for fabrication of large area tape-casting ferrite sheets. - Highlights: • Fine particles are favorable to lowering magnetic loss and enhancing permeability.

  8. Calculation of binary magnetic properties and potential energy curve in xenon dimer: second virial coefficient of (129)Xe nuclear shielding.

    Science.gov (United States)

    Hanni, Matti; Lantto, Perttu; Runeberg, Nino; Jokisaari, Jukka; Vaara, Juha

    2004-09-22

    Quantum chemical calculations of the nuclear shielding tensor, the nuclear quadrupole coupling tensor, and the spin-rotation tensor are reported for the Xe dimer using ab initio quantum chemical methods. The binary chemical shift delta, the anisotropy of the shielding tensor Delta sigma, the nuclear quadrupole coupling tensor component along the internuclear axis chi( parallel ), and the spin-rotation constant C( perpendicular ) are presented as a function of internuclear distance. The basis set superposition error is approximately corrected for by using the counterpoise correction (CP) method. Electron correlation effects are systematically studied via the Hartree-Fock, complete active space self-consistent field, second-order Møller-Plesset many-body perturbation, and coupled-cluster singles and doubles (CCSD) theories, the last one without and with noniterative triples, at the nonrelativistic all-electron level. We also report a high-quality theoretical interatomic potential for the Xe dimer, gained using the relativistic effective potential/core polarization potential scheme. These calculations used valence basis set of cc-pVQZ quality supplemented with a set of midbond functions. The second virial coefficient of Xe nuclear shielding, which is probably the experimentally best-characterized intermolecular interaction effect in nuclear magnetic resonance spectroscopy, is computed as a function of temperature, and compared to experiment and earlier theoretical results. The best results for the second virial coefficient, obtained using the CCSD(CP) binary chemical shift curve and either our best theoretical potential or the empirical potentials from the literature, are in good agreement with experiment. Zero-point vibrational corrections of delta, Delta sigma, chi (parallel), and C (perpendicular) in the nu=0, J=0 rovibrational ground state of the xenon dimer are also reported.

  9. Performance and Facility Background Pressure Characterization Tests of NASAs 12.5-kW Hall Effect Rocket with Magnetic Shielding Thruster

    Science.gov (United States)

    Kamhawi, Hani; Huang, Wensheng; Haag, Thomas; Shastry, Rohit; Thomas, Robert; Yim, John; Herman, Daniel; Williams, George; Myers, James; Hofer, Richard; hide

    2015-01-01

    NASA's Space Technology Mission Directorate (STMD) Solar Electric Propulsion Technology Demonstration Mission (SEP/TDM) project is funding the development of a 12.5-kW Hall thruster system to support future NASA missions. The thruster designated Hall Effect Rocket with Magnetic Shielding (HERMeS) is a 12.5-kW Hall thruster with magnetic shielding incorporating a centrally mounted cathode. HERMeS was designed and modeled by a NASA GRC and JPL team and was fabricated and tested in vacuum facility 5 (VF5) at NASA GRC. Tests at NASA GRC were performed with the Technology Development Unit 1 (TDU1) thruster. TDU1's magnetic shielding topology was confirmed by measurement of anode potential and low electron temperature along the discharge chamber walls. Thermal characterization tests indicated that during full power thruster operation at peak magnetic field strength, the various thruster component temperatures were below prescribed maximum allowable limits. Performance characterization tests demonstrated the thruster's wide throttling range and found that the thruster can achieve a peak thruster efficiency of 63% at 12.5 kW 500 V and can attain a specific impulse of 3,000 s at 12.5 kW and a discharge voltage of 800 V. Facility background pressure variation tests revealed that the performance, operational characteristics, and magnetic shielding effectiveness of the TDU1 design were mostly insensitive to increases in background pressure.

  10. Electric control of magnon frequencies and magnetic moment of bismuth ferrite thin films at room temperature.

    Science.gov (United States)

    Kumar, Ashok; Scott, J F; Katiyar, R S

    2011-08-08

    Here, we report the tuning of room-temperature magnon frequencies from 473 GHz to 402 GHz (14%) and magnetic moment from 4 to 18 emu∕cm(3) at 100 Oe under the application of external electric fields (E) across interdigital electrodes in BiFeO(3) (BFO) thin films. A decrease in magnon frequencies and increase in phonon frequencies were observed with Magnon and phonon Raman intensities are asymmetric with polarity, decreasing with positive E (+E) and increasing with negative E (-E) where polarity is with respect to in-plane polarization P. The magnetoelectric coupling (α) is proved to be linear and a rather isotropic α = 8.5 × 10(-12) sm(-1).

  11. MAGNET

    CERN Multimedia

    B. Curé

    MAGNET During the winter shutdown, the magnet subsystems went through a full maintenance. The magnet was successfully warmed up to room temperature beginning of December 2008. The vacuum was broken later on by injecting nitrogen at a pressure just above one atmosphere inside the vacuum tank. This was necessary both to prevent any accidental humidity ingress, and to allow for a modification of the vacuum gauges on the vacuum tank and maintenance of the diffusion pumps. The vacuum gauges had to be changed, because of erratic variations on the measurements, causing spurious alarms. The new type of vacuum gauges has been used in similar conditions on the other LHC experiments and without problems. They are shielded against the stray field. The lubricants of the primary and diffusion pumps have been changed. Several minor modifications were also carried out on the equipment in the service cavern, with the aim to ease the maintenance and to allow possible intervention during operation. Spare sensors have been bough...

  12. Nuclear Magnetic Shielding of Monoboranes: Calculation and Assessment of B-11 NMR Chemical Shifts in Planar BX3 and in Tetrahedral [BX4](-) Systems

    Czech Academy of Sciences Publication Activity Database

    Macháček, Jan; Bühl, M.; Fanfrlík, Jindřich; Hnyk, Drahomír

    2017-01-01

    Roč. 121, č. 50 (2017), s. 9631-9637 ISSN 1089-5639 R&D Projects: GA ČR(CZ) GA17-08045S Institutional support: RVO:61388980 ; RVO:61388963 Keywords : Electrostatic potentials * Nonrelativistic * Nuclear magnetic shieldings Subject RIV: CA - Inorganic Chemistry OBOR OECD: Inorganic and nuclear chemistry Impact factor: 2.847, year: 2016

  13. Development of a nano-tesla magnetic field shielded chamber and highly precise AC-susceptibility measurement coil at μK temperatures

    Science.gov (United States)

    Kumar, Anil; Prakash, Om; Ramakrishanan, S.

    2014-04-01

    A special sample measurement chamber has been developed to perform experiments at ultralow temperatures and ultralow magnetic field. A high permeability material known as cryoperm 10 and Pb is used to shield the measurement space consisting of the signal detecting set-up and the sample. The detecting setup consists of a very sensitive susceptibility coil wound on OFHC Cu bobbin.

  14. Magnetic Properties of Fe-49Co-2V Alloy and Pure Fe at Room and Elevated Temperatures

    Science.gov (United States)

    De Groh, Henry C., III; Geng, Steven M.; Niedra, Janis M.; Hofer, Richard R.

    2018-01-01

    The National Aeronautics and Space Administration (NASA) has a need for soft magnetic materials for fission power and ion propulsion systems. In this work the magnetic properties of the soft magnetic materials Hiperco 50 (Fe-49wt%Cr-2V) and CMI-C (commercially pure magnetic iron) were examined at various temperatures up to 600 C. Toroidal Hiperco 50 samples were made from stacks of 0.35 mm thick sheet, toroidal CMI-C specimens were machined out of solid bar stock, and both were heat treated prior to testing. The magnetic properties of a Hiperco 50 sample were measured at various temperatures up to 600 C and then again after returning to room temperature; the magnetic properties of CMI-C were tested at temperatures up to 400 C. For Hiperco 50 coercivity decreased as temperature increased, and remained low upon returning to room temperature; maximum permeability improved (increased) with increasing temperature and was dramatically improved upon returning to room temperature; remanence was not significantly affected by temperature; flux density at H = 0.1 kA/m increased slightly with increasing temperature, and was about 20% higher upon returning to room temperature; flux density at H = 0.5 kA/m was insensitive to temperature. It appears that the properties of Hiperco 50 improved with increasing temperature due to grain growth. There was no significant magnetic property difference between annealed and aged CMI-C iron material; permeability tended to decrease with increasing temperature; the approximate decline in the permeability at 400 C compared to room temperature was 30%; saturation flux density, B(sub S), was approximately equal for all temperatures below 400 C; B(sub S) was lower at 400 C.

  15. The ITER thermal shields for the magnet system: Design evolution and analysis

    International Nuclear Information System (INIS)

    Bykov, V.; Krasikov, Yu.; Grigoriev, S.; Komarov, V.; Krylov, V.; Labusov, A.; Pyrjaev, V.; Chiocchio, S.; Smirnov, V.; Sorin, V.; Tanchuk, V.

    2005-01-01

    The thermal shield (TS) system provides the required reduction of thermal loads to the cold structures operating at 4.5 K. This paper presents the rationale for the TS design evolution, details of the recent modifications that affect the TS cooling panels, the central TS ports and support system, interface labyrinths and TS structural joints. The modern results of thermal-hydraulic, thermal, seismic, static and dynamic structural analyses, that involve sub-modeling and sub-structuring finite element analysis techniques, are also reported. The modifications result in considerable reduction of TS mass, surface area and heat loads to/from the TS, simplification of TS assembly procedure and in-cryostat maintenance

  16. Shielded 3T HTS ADR Magnet Operating at 30-40 K, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Topic S1.10 of NASA 2015 SBIR solicitation calls for "Low current superconducting magnets (3-4 Tesla at temperatures > 15K". This proposal is a response to the...

  17. Spiral MRI on a 9.4T Vertical-bore Superconducting Magnet Using Unshielded and Self-shielded Gradient Coils

    Science.gov (United States)

    Kodama, Nao; Setoi, Ayana; Kose, Katsumi

    2018-01-01

    Spiral MRI sequences were developed for a 9.4T vertical standard bore (54 mm) superconducting magnet using unshielded and self-shielded gradient coils. Clear spiral images with 64-shot scan were obtained with the self-shielded gradient coil, but severe shading artifacts were observed for the spiral-scan images acquired with the unshielded gradient coil. This shading artifact was successfully corrected with a phase-correction technique using reference scans that we developed based on eddy current field measurements. We therefore concluded that spiral imaging sequences can be installed even for unshielded gradient coils if phase corrections are performed using the reference scans. PMID:28367906

  18. Spiral MRI on a 9.4T Vertical-bore Superconducting Magnet Using Unshielded and Self-shielded Gradient Coils.

    Science.gov (United States)

    Kodama, Nao; Setoi, Ayana; Kose, Katsumi

    2018-04-10

    Spiral MRI sequences were developed for a 9.4T vertical standard bore (54 mm) superconducting magnet using unshielded and self-shielded gradient coils. Clear spiral images with 64-shot scan were obtained with the self-shielded gradient coil, but severe shading artifacts were observed for the spiral-scan images acquired with the unshielded gradient coil. This shading artifact was successfully corrected with a phase-correction technique using reference scans that we developed based on eddy current field measurements. We therefore concluded that spiral imaging sequences can be installed even for unshielded gradient coils if phase corrections are performed using the reference scans.

  19. Optimization of a partially non-magnetic primary radiation shielding for the triple-axis spectrometer PANDA at the Munich high-flux reactor FRM-II

    CERN Document Server

    Pyka, N M; Rogov, A

    2002-01-01

    Monte Carlo simulations have been used to optimize the monochromator shielding of the polarized cold-neutron triple-axis spectrometer PANDA at the Munich high-flux reactor FRM-II. By using the Monte Carlo program MCNP-4B, the density of the total spectrum of incoming neutrons and gamma radiation from the beam tube SR-2 has been determined during the three-dimensional diffusion process in different types of heavy concrete and other absorbing material. Special attention has been paid to build a compact and highly efficient shielding, partially non-magnetic, with a total biological radiation dose of less than 10 mu Sv/h at its outsides. Especially considered was the construction of an albedo reducer, which serves to reduce the background in the experiment outside the shielding. (orig.)

  20. MAGNET

    CERN Multimedia

    B. Curé

    During the winter shutdown, the magnet subsystems went through a full maintenance. The magnet was successfully warmed up to room temperature beginning of December 2008. The vacuum was broken later on by injecting nitrogen at a pressure just above one atmosphere inside the vacuum tank. This was necessary both to prevent any accidental humidity ingress, and to allow for a modification of the vacuum gauges on the vacuum tank and maintenance of the diffusion pumps. The vacuum gauges had to be changed, because of erratic variations on the measurements, causing spurious alarms. The new type of vacuum gauges has been used in similar conditions on the other LHC experiments and without problems. They are shielded against the stray field. The lubricants of the primary and diffusion pumps have been changed. Several minor modifications were also carried out on the equipment in the service cavern, with the aim to ease the maintenance and to allow possible intervention during operation. Spare sensors have been bought. Th...

  1. Super magnets for interaction regions

    International Nuclear Information System (INIS)

    Biallas, G.; Fowler, W.; Diebold, R.

    1977-01-01

    The feasibility of using superconducting magnets in the beam interaction regions of particle accelerators is discussed. These higher field magnets can be shorter, leaving more room for detectors, but also must have a large aperture and magnetic shielding. The ''kissing geometry'' was investigated, and design and scaling considerations are given. A rough estimate of the cost of such superconducting magnets is given as an aid to the selection of interaction geometry

  2. Environmental optimization and shielding for NMR experiments and imaging in the earth's magnetic field.

    Science.gov (United States)

    Favre, B; Bonche, J P; Meheir, H; Peyrin, J O

    1990-02-01

    For many years, a number of laboratories have been working on the applications of very low field NMR. In 1985, our laboratory presented the first NMR images using the earth's magnetic field. However, the use of this technique was limited by the weakness of the signal and the disturbing effects of the environment on the signal-to-noise ratio and on the homogeneity of the static magnetic field. Therefore experiments has to be performed in places with low environmental disturbances, such as open country or large parks. In 1986, we installed a new station in Lyon, in the town's hostile environment. Good NMR signals can now be obtained (with a signal-to-noise ratio better than 200 and a time constant T2 better than 3s for 200-mnl water samples and at a temperature of about 40 degrees C). We report the terrace roof of our faculty building. Gradient coils were used to correct the local inhomogeneities of the earth's magnetic field. We show FIDs and MR images of water-filled tubes made with or without these improvements.

  3. Adjoint acceleration of Monte Carlo simulations using TORT/MCNP coupling approach: A case study on the shielding improvement for the cyclotron room of the Buddhist Tzu Chi General Hospital

    International Nuclear Information System (INIS)

    Sheu, R. J.; Sheu, R. D.; Jiang, S. H.; Kao, C. H.

    2005-01-01

    Full-scale Monte Carlo simulations of the cyclotron room of the Buddhist Tzu Chi General Hospital were carried out to improve the original inadequate maze design. Variance reduction techniques are indispensable in this study to facilitate the simulations for testing a variety of configurations of shielding modification. The TORT/MCNP manual coupling approach based on the Consistent Adjoint Driven Importance Sampling (CADIS) methodology has been used throughout this study. The CADIS utilises the source and transport biasing in a consistent manner. With this method, the computational efficiency was increased significantly by more than two orders of magnitude and the statistical convergence was also improved compared to the unbiased Monte Carlo run. This paper describes the shielding problem encountered, the procedure for coupling the TORT and MCNP codes to accelerate the calculations and the calculation results for the original and improved shielding designs. In order to verify the calculation results and seek additional accelerations, sensitivity studies on the space-dependent and energy-dependent parameters were also conducted. (authors)

  4. Mechanically Robust Magnetic Carbon Nanotube Papers Prepared with CoFe2O4 Nanoparticles for Electromagnetic Interference Shielding and Magnetomechanical Actuation.

    Science.gov (United States)

    Lim, Guh-Hwan; Woo, Seongwon; Lee, Hoyoung; Moon, Kyoung-Seok; Sohn, Hiesang; Lee, Sang-Eui; Lim, Byungkwon

    2017-11-22

    The introduction of inorganic nanoparticles into carbon nanotube (CNT) papers can provide a versatile route to the fabrication of CNT papers with diverse functionalities, but it may lead to a reduction in their mechanical properties. Here, we describe a simple and effective strategy for the fabrication of mechanically robust magnetic CNT papers for electromagnetic interference (EMI) shielding and magnetomechanical actuation applications. The magnetic CNT papers were produced by vacuum filtration of an aqueous suspension of CNTs, CoFe 2 O 4 nanoparticles, and poly(vinyl alcohol) (PVA). PVA plays a critical role in enhancing the mechanical strength of CNT papers. The magnetic CNT papers containing 73 wt % of CoFe 2 O 4 nanoparticles exhibited high mechanical properties with Young's modulus of 3.2 GPa and tensile strength of 30.0 MPa. This magnetic CNT paper was successfully demonstrated as EMI shielding paper with shielding effectiveness of ∼30 dB (99.9%) in 0.5-1.0 GHz, and also as a magnetomechanical actuator in an audible frequency range from 200 to 20 000 Hz.

  5. Analysis of the Magnetic Measurements at Room Temperature of the LHC Main Quadrupole Prototypes

    CERN Document Server

    Peyrot, M; Remondino, Vittorio; Rifflet, J M; Scandale, Walter; Simon, F; Todesco, Ezio; Tortschanoff, Theodor

    2000-01-01

    The room temperature magnetic measurements of the first series-design prototypes of the LHC main quadrupoles are analysed. Field shape harmonics for the nominal design are worked out using numerical simulations. Data relative to six apertures (three quadrupoles) are considered. The averages of the multipoles are interpreted as the systematic components. The agreement with the nominal design is verified, and possible explanations for discrepancies are worked out. An offset in b6 of around 2.4 units is observed, and can be justified in terms of a coil azimuthal length larger than the nominal value by about 0.1 mm. Standard deviations of the multipoles are interpreted as the random components. We show that the latter can be in-terpreted in terms of random movements of around 25-35 µm r.m.s. of the coil blocks, because of components and assembly tolerances. A good correlation between measurements made on collared coil and the assembled cold mass is found. Comparison with target values for beam dynamics is given.

  6. Shielding practice

    International Nuclear Information System (INIS)

    Sauermann, P.F.

    1985-08-01

    The basis of shielding practice against external irradiation is shown in a simple way. For most sources of radiation (point sources) occurring in shielding practice, the basic data are given, mainly in the form of tables, which are required to solve the shielding problems. The application of these data is explained and discussed using practical examples. Thickness of shielding panes of glove boxes for α and β radiation; shielding of sealed γ-radiography sources; shielding of a Co-60 radiation source, and of the manipulator panels for hot cells; damping factors for γ radiation and neutrons; shielding of fast and thermal neutrons, and of bremsstrahlung (X-ray tubes, Kr-85 pressure gas cylinders, 42 MeV betatrons, 20 MeV linacs); two-fold shielding (lead glass windows for hot cells, 14 MeV neutron generators); shielding against scattered radiation. (orig./HP) [de

  7. Direct Observation of Room-Temperature Stable Magnetism in LaAlO3/SrTiO3 Heterostructures.

    Science.gov (United States)

    Yang, Ming; Ariando; Zhou, Jun; Asmara, Teguh Citra; Krüger, Peter; Yu, Xiao Jiang; Wang, Xiao; Sanchez-Hanke, Cecilia; Feng, Yuan Ping; Venkatesan, T; Rusydi, Andrivo

    2018-03-21

    Along with an unexpected conducting interface between nonmagnetic insulating perovskites LaAlO 3 and SrTiO 3 (LaAlO 3 /SrTiO 3 ), striking interfacial magnetisms have been observed in LaAlO 3 /SrTiO 3 heterostructures. Interestingly, the strength of the interfacial magnetic moment is found to be dependent on oxygen partial pressures during the growth process. This raises an important, fundamental question on the origin of these remarkable interfacial magnetic orderings. Here, we report a direct evidence of room-temperature stable magnetism in a LaAlO 3 /SrTiO 3 heterostructure prepared at high oxygen partial pressure by using element-specific soft X-ray magnetic circular dichroism at both Ti L 3,2 and O K edges. By combining X-ray absorption spectroscopy at both Ti L 3,2 and O K edges and first-principles calculations, we qualitatively ascribe that this strong magnetic ordering with dominant interfacial Ti 3+ character is due to the coexistence of LaAlO 3 surface oxygen vacancies and interfacial (Ti Al -Al Ti ) antisite defects. On the basis of this new understanding, we revisit the origin of the weak magnetism in LaAlO 3 /SrTiO 3 heterostructures prepared at low oxygen partial pressures. Our calculations show that LaAlO 3 surface oxygen vacancies are responsible for the weak magnetism at the interface. Our result provides direct evidence on the presence of room-temperature stable magnetism and a novel perspective to understand magnetic and electronic reconstructions at such strategic oxide interfaces.

  8. HPGe detector shielding adjustment

    International Nuclear Information System (INIS)

    Trnkova, L.; Rulik, P.

    2008-01-01

    Low-level background shielding of HPGe detectors is used mainly for environmental samples with very low content of radionuclides. National Radiation Protection Institute (SURO) in Prague is equipped with 14 HPGe detectors with relative efficiency up to 150%. The detectors are placed in a room built from materials with low content of natural radionuclides and equipped with a double isolation of the floor against radon. Detectors themselves are placed in lead or steel shielding. Steel shielding with one of these detectors with relative efficiency of 100% was chosen to be rebuilt to achieve lower minimum detectable activity (MDA). Additional lead and copper shielding was built up inside the original steel shielding to reduce the volume of the inner space and filled with nitrogen by means of evaporating liquid nitrogen. The additional lead and copper shielding, consequent reduction of the inner volume and supply of evaporated nitrogen, caused a decrease of the background count and accordingly MDA values as well. The effect of nitrogen evaporation on the net areas of peaks belonging to radon daughters is significant. The enhanced shielding adjustment has the biggest influence in low energy range, what can be seen in collected data. MDA values in energy range from 30 keV to 400 keV decreased to 0.65-0.85 of original value, in energy range from 400 keV to 2 MeV they fell to 0.70-0.97 of original value. (authors)

  9. Calculation of the structural shielding of the radiotherapy treatment room equipped with a linear accelerator type Tomo therapy Hi-Art in the Oncology Center of Chihuahua, Mexico

    International Nuclear Information System (INIS)

    Caballero G, C. A.; Plascencia, J. C.; Vargas V, M. X.; Toledo J, P.

    2010-09-01

    The helicoid tomo therapy is an external radiotherapy system of modulated intensity, guided by image, in which the radiation is imparted to the patient using a narrow radiation beam in helicoid form, in a similar way to the scanning process with a computerized tomography. The tomo therapy equipment (Tomo Therapy Hi-Art) consists in an electrons linear accelerator with acceleration voltages of 6 MV for treatment and 3.5 MV for image, coupled to a ring that turn around the patient as this is transferred through this ring in perpendicular sense to the radiation beam. The radiation beam is narrow because has the maximum size of 5 x 40 cm 2 in the isocenter. The intensity modulation of the beam is carried out with a binary dynamic collimator of 64 crisscross sheets, and the guide by image though a system of megavoltage computerized tomography. Opposed to the radiation beam, also coupled to the rotational ring, a group of lead plates exists with a total thickness of 13 cm that acts as barrier of the primary radiation beam. The special configuration of the tomography equipment makes to have the following characteristics: 1) the presence of the lead barrier of the equipment reduces the intensity of the primary beam that reaches the bunker walls in considerable way, 2) the disperse and leakage radiations are increased with regard to a conventional accelerator due to the increase in the necessary irradiation time to produce modulated intensity fields by means of the narrow radiation beam. These special characteristics of the tomo therapy equipment make that particularities exist in the application of the formulations for structural shielding calculations that appears in the NCRP reports 49, NCRP 151 and IAEA-SRS-47. For this reason, several researches have development analytic models based on geometric considerations of continuous rotation of the equipment ring to determine the shielding requirements for the primary beam, the dispersed and leakage radiation in tomo therapy

  10. Shielding in experimental areas

    International Nuclear Information System (INIS)

    Stevens, A.; Tarnopolsky, G.; Thorndike, A.; White, S.

    1979-01-01

    The amount of shielding necessary to protect experimental detectors from various sources of background radiation is discussed. As illustrated an experiment has line of sight to sources extending approx. 90 m upstream from the intersection point. Packing a significant fraction of this space with shielding blocks would in general be unacceptable because primary access to the ring tunnel is from the experimental halls. (1) From basic machine design considerations and the inherent necessity to protect superconducting magnets it is expected that experimental areas in general will be cleaner than at any existing accelerator. (2) Even so, it will likely be necessary to have some shielding blocks available to protect experimental apparatus, and it may well be necessary to have a large amount of shielding available in the WAH. (3) Scraping will likely have some influence on all halls, and retractable apparatus may sometimes be necessary. (4) If access to any tunnel is needed to replace a magnet, one has 96 h (4 days) available to move shielding away to permit access without additional downtime. This (the amount of shielding one can shuffle about in 96 h) is a reasonable upper limit to shielding necessary in a hall

  11. Effect of local sugar and base geometry on {sup 13}C and {sup 15}N magnetic shielding anisotropy in DNA nucleosides

    Energy Technology Data Exchange (ETDEWEB)

    Brumovska, Eva [University of South Bohemia and Biology Centre AS CR v.v.i., Faculty of Science (Czech Republic); Sychrovsky, Vladimir; Vokacova, Zuzana [Institute of Organic Chemistry and Biochemistry, AS CR v.v.i. (Czech Republic); Sponer, Jiri [Institute of Biophysics, AS CR v.v.i. (Czech Republic); Schneider, Bohdan [Biotechnological Institute AS CR (Czech Republic); Trantirek, Lukas [University of South Bohemia and Biology Centre AS CR v.v.i., Faculty of Science (Czech Republic)], E-mail: trant@paru.cas.cz

    2008-11-15

    Density functional theory was employed to study the dependence of {sup 13}C and {sup 15}N magnetic shielding tensors on the glycosidic torsion angle ({chi}) and conformation of the sugar ring in 2'-deoxyadenosine, 2'-deoxyguanosine, 2'-deoxycytidine, and 2'-deoxythymidine. In general, the magnetic shielding of the glycosidic nitrogens and the sugar carbons was found to depend on both the conformation of the sugar ring and {chi}. Our calculations indicate that the magnetic shielding anisotropy of the C6 atom in pyrimidine and the C8 atom in purine bases depends strongly on {chi}. The remaining base carbons were found to be insensitive to both sugar pucker and {chi} re-orientation. These results call into question the underlying assumptions of currently established methods for interpreting residual chemical shift anisotropies and {sup 13}C and {sup 15}N auto- and cross-correlated relaxation rates and highlight possible limitations of DNA applications of these methods.

  12. Electromagnetic shielding

    International Nuclear Information System (INIS)

    Tzeng, Wen-Shian V.

    1991-01-01

    Electromagnetic interference (EMI) shielding materials are well known in the art in forms such as gaskets, caulking compounds, adhesives, coatings and the like for a variety of EMI shielding purposes. In the past, where high shielding performance is necessary, EMI shielding has tended to use silver particles or silver coated copper particles dispersed in a resin binder. More recently, aluminum core silver coated particles have been used to reduce costs while maintaining good electrical and physical properties. (author). 8 figs

  13. Evaluation of the shield calculation adequacy of radiotherapy rooms through Monte Carlo Method and experimental measures; Avaliacao da adequacao do calculo de blindagens de salas de radioterapia atraves do metodo de Monte Carlos e medidas experimentais

    Energy Technology Data Exchange (ETDEWEB)

    Meireles, Ramiro Conceicao

    2016-07-01

    The shielding calculation methodology for radiotherapy services adopted in Brazil and in several countries is that described in publication 151 of the National Council on Radiation Protection and Measurements (NCRP 151). This methodology however, markedly employs several approaches that can impact both in the construction cost and in the radiological safety of the facility. Although this methodology is currently well established by the high level of use, some parameters employed in the calculation methodology did not undergo to a detailed assessment to evaluate the impact of the various approaches considered. In this work the MCNP5 Monte Carlo code was used with the purpose of evaluating the above mentioned approaches. TVLs values were obtained for photons in conventional concrete (2.35g / cm{sup 3}), considering the energies of 6, 10 and 25 MeV, respectively, first considering an isotropic radiation source impinging perpendicular to the barriers, and subsequently a lead head shielding emitting a shaped beam, in the format of a pyramid trunk. Primary barriers safety margins, taking in account the head shielding emitting photon beam pyramid-shaped in the energies of 6, 10, 15 and 18 MeV were assessed. A study was conducted considering the attenuation provided by the patient's body in the energies of 6,10, 15 and 18 MeV, leading to new attenuation factors. Experimental measurements were performed in a real radiotherapy room, in order to map the leakage radiation emitted by the accelerator head shielding and the results obtained were employed in the Monte Carlo simulation, as well as to validate the entire study. The study results indicate that the TVLs values provided by (NCRP, 2005) show discrepancies in comparison with the values obtained by simulation and that there may be some barriers that are calculated with insufficient thickness. Furthermore, the simulation results show that the additional safety margins considered when calculating the width of the

  14. Influence of the magnetic field orientation on the mixed state properties of high temperature superconductors: an ac shielding study

    International Nuclear Information System (INIS)

    Schmidt, B.

    1999-01-01

    This work deals with the influence of the orientation of an applied static magnetic field on the mixed state properties of high temperature superconducting cuprates. The mixed state is characterized by the presence of vortices (quanta of magnetic flux). Their properties have been tested via the dynamic approach of the shielding of an ac magnetic field. In pristine Bi 2 Sr 2 CaCu 2 O 8 crystals the first order transition of the vortex system from an ordered to a disordered state has been studied. It has been found that in the material the transition is mainly determined by the component of the field perpendicular to the superconducting copper oxide layers. However, the value of this component at the transition diminishes with the increase of the field component parallel to the layers. This is explained by the decrease of the Josephson coupling between 2D vortices in neighbouring planes in the presence of a parallel component. In heavy ion irradiated Bi 2 Sr 2 CaCu 2 O 8 the subject under investigation has been the pinning of the vortices by the irradiation tracks. These defects push the irreversibility line towards higher fields. In the field range that has become irreversible after irradiation pinning by columnar defects is anisotropic. This anisotropy in pinning indicates that a coupling exists between the 2D vortices that form a vortex line, in contrast to the behaviour in the pristine material in the same field range. HgBa 2 Ca 2 Cu 3 O 8 with columnar defects shows essentially the same behaviour as Bi 2 Sr 2 CaCu 2 O 8 , the differences being well explained by the lower anisotropy of HgBa 2 Ca 2 Cu 3 O 8 which leads to a more linear character of the vortices. Finally, it has been shown that in pristine Bi 2 Sr 2 CaCu 2 O 8 the concentration of the vortices in the center of the sample is explained by the surface barrier alone. (author)

  15. Influence of the magnetic field orientation on the mixed state properties of high temperature superconductors: an ac shielding study

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, B

    1999-07-01

    This work deals with the influence of the orientation of an applied static magnetic field on the mixed state properties of high temperature superconducting cuprates. The mixed state is characterized by the presence of vortices (quanta of magnetic flux). Their properties have been tested via the dynamic approach of the shielding of an ac magnetic field. In pristine Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} crystals the first order transition of the vortex system from an ordered to a disordered state has been studied. It has been found that in the material the transition is mainly determined by the component of the field perpendicular to the superconducting copper oxide layers. However, the value of this component at the transition diminishes with the increase of the field component parallel to the layers. This is explained by the decrease of the Josephson coupling between 2D vortices in neighbouring planes in the presence of a parallel component. In heavy ion irradiated Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} the subject under investigation has been the pinning of the vortices by the irradiation tracks. These defects push the irreversibility line towards higher fields. In the field range that has become irreversible after irradiation pinning by columnar defects is anisotropic. This anisotropy in pinning indicates that a coupling exists between the 2D vortices that form a vortex line, in contrast to the behaviour in the pristine material in the same field range. HgBa{sub 2}Ca{sub 2}Cu{sub 3}O{sub 8} with columnar defects shows essentially the same behaviour as Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}, the differences being well explained by the lower anisotropy of HgBa{sub 2}Ca{sub 2}Cu{sub 3}O{sub 8} which leads to a more linear character of the vortices. Finally, it has been shown that in pristine Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} the concentration of the vortices in the center of the sample is explained by the surface barrier alone. (author)

  16. Performance, Facility Pressure Effects, and Stability Characterization Tests of NASA's Hall Effect Rocket with Magnetic Shielding Thruster

    Science.gov (United States)

    Kamhawi, Hani; Huang, Wensheng; Haag, Thomas; Yim, John; Herman, Daniel; Williams, George; Gilland, James; Peterson, Peter; Hofer, Richard; Mikellides, Ioannis

    2016-01-01

    NASAs Hall Effect Rocket with Magnetic Shielding (HERMeS) 12.5 kW Technology Demonstration Unit-1 (TDU-1) Hall thruster has been the subject of extensive technology maturation in preparation for flight system development. Part of the technology maturation effort included experimental evaluation of the TDU-1 thruster with conducting and dielectric front pole cover materials in two different electrical configurations. A graphite front pole cover thruster configuration with the thruster body electrically tied to cathode and an alumina front pole cover thruster configuration with the thruster body floating were evaluated. Both configurations were also evaluated at different facility background pressure conditions to evaluate background pressure effects on thruster operation. Performance characterization tests found that higher thruster performance was attained with the graphite front pole cover configuration with the thruster electrically tied to cathode. A total thrust efficiency of 68 and a total specific impulse of 2,820 s was demonstrated at a discharge voltage of 600 V and a discharge power of 12.5 kW. Thruster stability regimes were characterized with respect to the thruster discharge current oscillations and with maps of the current-voltage-magnetic field (IVB). Analysis of TDU-1 discharge current waveforms found that lower normalized discharge current peak-to-peak and root mean square magnitudes were attained when the thruster was electrically floated with alumina front pole covers. Background pressure effects characterization tests indicated that the thruster performance and stability was mostly invariant to changes in the facility background pressure for vacuum chamber pressure below 110-5 Torr-Xe (for thruster flow rate above 8 mgs). Power spectral density analysis of the discharge current waveform showed that increasing the vacuum chamber background pressure resulted in a higher discharge current dominant frequency. Finally the IVB maps of the TDU-1

  17. Radiation shielding considerations for the repair and maintenance of a swimming pool-type tokamak reactor

    International Nuclear Information System (INIS)

    Seki, Y.; Mori, S.

    1984-01-01

    The radiation shielding relevant to the repair and maintenance of a swimming pool-type tokamak reactor is considered. The dose rate during the reactor operation can be made low enough for personnel access into the reactor room if a 2m thick water layer is installed above the magnet cryostat. The dose rate 24 h after shutdown is such that the human access is allowed above the magnet cryostat. Sufficient water layer thickness is provided in the inboard space for the operation of automatic welder/cutter while retaining the magnet shielding capability. Some forced cooling is required for the decay heat removal in the first wall. The penetration shield thickness around the neutral beam injector port is estimated to be barely sufficient in terms of the magnet radiation damage. (orig.)

  18. Room temperature deposition of perpendicular magnetic anisotropic Co{sub 3}Pt thin films on glass substrate

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yu-Shen; Dai, Hong-Yu; Hsu, Yi-Wei [Department of Chemical Engineering and Materials Science, Yuan-Ze University, Chung-Li 32003, Taiwan (China); Ou, Sin-Liang, E-mail: slo@mail.dyu.edu.tw [Department of Materials Science and Engineering, Da-Yeh University, Changhua 51591, Taiwan (China); Chen, Shi-Wei [National Synchrotron Radiation Research Center (NSRRC), Hsinchu 300, Taiwan (China); Lu, Hsi-Chuan; Wang, Sea-Fue [Department of Materials and Mineral Resources Engineering, National Taipei University of Technology, Taipei 106, Taiwan (China); Sun, An-Cheng, E-mail: acsun@saturn.yzu.edu.tw [Department of Chemical Engineering and Materials Science, Yuan-Ze University, Chung-Li 32003, Taiwan (China)

    2017-03-01

    Co{sub 3}Pt alloy thin films were deposited on the glass substrate at room temperature (RT) and 300 °C, which showed high perpendicular magnetic anisotropy (PMA) and isotropy magnetic behaviors, respectively. Co{sub 3}Pt HCP (0002) planes grew along the substrate plane for the films deposited at RT. The easy axis [0001] was consequently vertical to the substrate surface and obtained the predominant PMA. Large magnetic domains and sharp boundary also supported high PMA in RT-deposited samples. On the other hand, the PMA was significantly decreased with increasing the deposition temperature from RT to 300 °C. Hard HCP(0002) and soft A1(111) co-existed in the film and the magnetic exchanged coupling between these two phases induced isotropy magnetic behavior. In addition, the various thicknesses (t) of the RT-deposited Co{sub 3}Pt films were deposited with different base pressures prior to sputtering. The Kerr rotation loops showed high PMA and out-of-plane squareness (S{sub ⊥}) of ~0.9 were found in low base pressure chamber. Within high base pressure chamber, Co{sub 3}Pt films just show magnetic isotropy behaviors. This study provides a fabrication method for the preparation of high PMA HCP-type Co{sub 3}Pt films on the glass substrate without any underlayer at RT. The results could be the base for future development of RT-deposited magnetic alloy thin film with high PMA. - Highlights: • Fabricated high perpendicular magnetic anisotropy Co{sub 3}Pt thin film on glass substrate. • Prepared HCP Co{sub 3}Pt thin film at room temperature. • The key to enhance the PMA of the Co{sub 3}Pt films. • Thinner film is good to fabricate PMA Co{sub 3}Pt thin films.

  19. Minimizing magnetic fields for precision experiments

    Energy Technology Data Exchange (ETDEWEB)

    Altarev, I.; Fierlinger, P.; Lins, T.; Marino, M. G.; Nießen, B.; Petzoldt, G.; Reisner, M.; Stuiber, S., E-mail: stefan.stuiber@ph.tum.de; Sturm, M.; Taggart Singh, J.; Taubenheim, B. [Physikdepartment, Technische Universität München, D-85748 Garching (Germany); Rohrer, H. K. [Rohrer GmbH, D-80667 München (Germany); Schläpfer, U. [IMEDCO AG, CH-4614 Hägendorf (Switzerland)

    2015-06-21

    An increasing number of measurements in fundamental and applied physics rely on magnetically shielded environments with sub nano-Tesla residual magnetic fields. State of the art magnetically shielded rooms (MSRs) consist of up to seven layers of high permeability materials in combination with highly conductive shields. Proper magnetic equilibration is crucial to obtain such low magnetic fields with small gradients in any MSR. Here, we report on a scheme to magnetically equilibrate MSRs with a 10 times reduced duration of the magnetic equilibration sequence and a significantly lower magnetic field with improved homogeneity. For the search of the neutron's electric dipole moment, our finding corresponds to a 40% improvement of the statistical reach of the measurement. However, this versatile procedure can improve the performance of any MSR for any application.

  20. Minimizing magnetic fields for precision experiments

    International Nuclear Information System (INIS)

    Altarev, I.; Fierlinger, P.; Lins, T.; Marino, M. G.; Nießen, B.; Petzoldt, G.; Reisner, M.; Stuiber, S.; Sturm, M.; Taggart Singh, J.; Taubenheim, B.; Rohrer, H. K.; Schläpfer, U.

    2015-01-01

    An increasing number of measurements in fundamental and applied physics rely on magnetically shielded environments with sub nano-Tesla residual magnetic fields. State of the art magnetically shielded rooms (MSRs) consist of up to seven layers of high permeability materials in combination with highly conductive shields. Proper magnetic equilibration is crucial to obtain such low magnetic fields with small gradients in any MSR. Here, we report on a scheme to magnetically equilibrate MSRs with a 10 times reduced duration of the magnetic equilibration sequence and a significantly lower magnetic field with improved homogeneity. For the search of the neutron's electric dipole moment, our finding corresponds to a 40% improvement of the statistical reach of the measurement. However, this versatile procedure can improve the performance of any MSR for any application

  1. The UKB prescription and the heavy atom effects on the nuclear magnetic shielding of vicinal heavy atoms.

    Science.gov (United States)

    Maldonado, Alejandro F; Aucar, Gustavo A

    2009-07-21

    Fully relativistic calculations of NMR magnetic shielding on XYH3 (X = C, Si, Ge and Sn; Y = Br, I), XHn (n = 1-4) molecular systems and noble gases performed with a fully relativistic polarization propagator formalism at the RPA level of approach are presented. The rate of convergence (size of basis set and time involved) for calculations with both kinetic balance prescriptions, RKB and UKB, were investigated. Calculations with UKB makes it feasible to obtain reliable results for two or more heavy-atom-containing molecules. For such XYH3 systems, the influence of heavy vicinal halogen atoms on sigma(X) is such that heavy atom effects on heavy atoms (vicinal plus their own effects or HAVHA + HAHA effects) amount to 30.50% for X = Sn and Y = I; being the HAHA effect of the order of 25%. So the vicinal effect alone is of the order of 5.5%. The vicinal heavy atom effect on light atoms (HALA effect) is of the order of 28% for X = C and Y = I. A similar behaviour, but of opposite sign, is observed for sigma(Y) for which sigmaR-NR (I; X = C) (HAHA effect) is around 27% and sigmaR-NR(I; X = Sn) (HAVHA + HAHA effects) is close to 21%. Its electronic origin is paramagnetic for halogen atoms but both dia- and paramagnetic for central atoms. The effect on two bond distant hydrogen atoms is such that the largest variation of sigma(H) within the same family of XYH3 molecules appears for X = Si and Y = I: around 20%. In this case sigma(H; X = Sn, Y = I) = 33.45 ppm and sigma(H; X = Sn, Y = H) = 27.82 ppm.

  2. Nuclear Magnetic Shielding Constants from Quantum Mechanical/Molecular Mechanical Calculations Using Polarizable Embedding: Role of the Embedding Potential

    DEFF Research Database (Denmark)

    Steinmann, Casper; Olsen, Jógvan Magnus Haugaard; Kongsted, Jacob

    2014-01-01

    We present NMR shielding constants obtained through quantum mechanical/molecular mechanical (QM/MM) embedding calculations. Contrary to previous reports, we show that a relatively small QM region is sufficient, provided that a high-quality embedding potential is used. The calculated averaged NMR...... shielding constants of both acrolein and acetone solvated in water are based on a number of snapshots extracted from classical molecular dynamics simulations. We focus on the carbonyl chromophore in both molecules, which shows large solvation effects, and we study the convergence of shielding constants...

  3. Room-temperature superparamagnetism due to giant magnetic anisotropy in Mo S defected single-layer MoS2

    Science.gov (United States)

    Khan, M. A.; Leuenberger, Michael N.

    2018-04-01

    Room-temperature superparamagnetism due to a large magnetic anisotropy energy (MAE) of a single atom magnet has always been a prerequisite for nanoscale magnetic devices. Realization of two dimensional (2D) materials such as single-layer (SL) MoS2, has provided new platforms for exploring magnetic effects, which is important for both fundamental research and for industrial applications. Here, we use density functional theory (DFT) to show that the antisite defect (Mo S ) in SL MoS2 is magnetic in nature with a magnetic moment μ of  ∼2 μB and, remarkably, exhibits an exceptionally large atomic scale MAE =\\varepsilon\\parallel-\\varepsilon\\perp of  ∼500 meV. Our calculations reveal that this giant anisotropy is the joint effect of strong crystal field and significant spin–orbit coupling (SOC). In addition, the magnetic moment μ can be tuned between 1 μB and 3 μB by varying the Fermi energy \\varepsilonF , which can be achieved either by changing the gate voltage or by chemical doping. We also show that MAE can be raised to  ∼1 eV with n-type doping of the MoS2:Mo S sample. Our systematic investigations deepen our understanding of spin-related phenomena in SL MoS2 and could provide a route to nanoscale spintronic devices.

  4. Estimation of isotropic nuclear magnetic shieldings in the CCSD(T) and MP2 complete basis set limit using affordable correlation calculations

    DEFF Research Database (Denmark)

    Kupka, Teobald; Stachów, Michal; Kaminsky, Jakub

    2013-01-01

    , estimated from calculations with the family of polarizationconsistent pcS-n basis sets is reported. This dependence was also supported by inspection of profiles of deviation between CBS estimated nuclear shieldings and obtained with significantly smaller basis sets pcS-2 and aug-cc-pVTZ-J for the selected......A linear correlation between isotropic nuclear magnetic shielding constants for seven model molecules (CH2O, H2O, HF, F2, HCN, SiH4 and H2S) calculated with 37 methods (34 density functionals, RHF, MP2 and CCSD(T) ), with affordable pcS-2 basis set and corresponding complete basis set results...... set of 37 calculation methods. It was possible to formulate a practical approach of estimating the values of isotropic nuclear magnetic shielding constants at the CCSD(T)/CBS and MP2/CBS levels from affordable CCSD(T)/pcS-2, MP2/pcS-2 and DFT/CBS calculations with pcS-n basis sets. The proposed method...

  5. Shielding plugs

    International Nuclear Information System (INIS)

    Makishima, Kenji.

    1986-01-01

    Purpose: In shielding plugs of an LMFBR type reactor, to restrain natural convection of heat in an annular space between a thermal shield layer and a shield shell, to prevent the lowering of heat-insulation performance, and to alleviate a thermal stress in a reactor container and the shield shell. Constitution: A ring-like leaf spring split in the direction of height is disposed in an annular space between a thermal shield layer and a shield shell. In consequence, the space is partitioned in the direction of height and, therefore, if axial temperature conditions and space width are the same and the space is low, the natural convection is hard to occur. Thus the rise of upper surface temperature of the shielding plugs can prevent the lowering of the heat insulation performance which will result in the increment of shielding plug cooling capacity, thereby improving reliability. In the meantime, since there is mounted an earthquake-resisting support, the thermal shield layer will move for a slight gap in case of an earthquake, being supported by the earthquake-resisting support, and the movement of the thermal shield layer is restricted, thereby maintaining integrity without increasing the stroke of the ring-like spring. (Kawakami, Y.)

  6. Characterization of Magnetic Field Immersed Photomultipliers from Double Chooz Experiment. Design and Construction of their Magnetic Shields; Caracterizacion de los fotomultiplicadores del experimento Double Chooz bajo campo magnetico y diseno y construccion de sus blindajes magneticos

    Energy Technology Data Exchange (ETDEWEB)

    Valdivia Valero, F. J.

    2007-12-28

    Flavour oscillations of neutrinos are a quantum-mechanical effect widely demonstrated. It is explained through interferences of their mass eigenstates, therefore, belonging to the physical area beyond the Standard Model. This work deals with the CIEMAT collaboration in the neutrino experiment Double Chooz. Such an experiment aims to measure the mixture angle {theta}{sub 1}3, one of the PMNS leptonic mixture matrix, with a un reached-before sensibility by decrease of systematic errors. For this, two identical scintillator detectors, equipped with PMT's, will be sited at different distances from two reactors located in the nuclear power plant CHOOZ B (France). The electronic neutrino flux from these reactors will be compared, explaining its deficit by flavour oscillations of these particles. The identity of both detectors will be diminished by the magnetic field effects on the PMT's response. Therefore, this study serves as for quantifying such an effects as for fitting the magnetic shields design that minimize them. Shielding measurements and final design of magnetic shields as much as the effect these ones cause in the PMT's response immersed in a monitored magnetic field are presented. (Author) 85 refs.

  7. Characterization of Magnetic Field Immersed Photomultipliers from Double Chooz Experiment. Design and Construction of their Magnetic Shields; Caracterizacion de los fotomultiplicadores del experimento Double Chooz bajo campo magnetico y diseno y construccion de sus blindajes magneticos

    Energy Technology Data Exchange (ETDEWEB)

    Valdivia Valero, F J

    2007-12-28

    Flavour oscillations of neutrinos are a quantum-mechanical effect widely demonstrated. It is explained through interferences of their mass eigenstates, therefore, belonging to the physical area beyond the Standard Model. This work deals with the CIEMAT collaboration in the neutrino experiment Double Chooz. Such an experiment aims to measure the mixture angle {theta}{sub 1}3, one of the PMNS leptonic mixture matrix, with a un reached-before sensibility by decrease of systematic errors. For this, two identical scintillator detectors, equipped with PMT's, will be sited at different distances from two reactors located in the nuclear power plant CHOOZ B (France). The electronic neutrino flux from these reactors will be compared, explaining its deficit by flavour oscillations of these particles. The identity of both detectors will be diminished by the magnetic field effects on the PMT's response. Therefore, this study serves as for quantifying such an effects as for fitting the magnetic shields design that minimize them. Shielding measurements and final design of magnetic shields as much as the effect these ones cause in the PMT's response immersed in a monitored magnetic field are presented. (Author) 85 refs.

  8. Magnetic resonance imaging: project planning and management of a superconductive M.R.I. installation

    International Nuclear Information System (INIS)

    Condon, P.M.; Robertson, A.R.

    1989-01-01

    The planning and installation of a Superconductive Magnetic Resonance Imaging installation at the Royal Adelaide Hospital, Adelaide, South Australia is described. Tender specification, assessment of offers via criteria weighted analysis of technical and economic factors and the final recommendation for a 1.0 Tesla unit are discussed. Building and installation considerations are noted including fringe field effects, magnetic shielding, radiofrequency shielding, cryogens, metallic screening and specific considerations in the Magnet room. 9 refs., 7 figs

  9. Oscillations in the open solar magnetic flux with a period of 1.68 years: imprint on galactic cosmic rays and implications for heliospheric shielding

    Directory of Open Access Journals (Sweden)

    A. Rouillard

    2004-12-01

    Full Text Available An understanding of how the heliosphere modulates galactic cosmic ray (GCR fluxes and spectra is important, not only for studies of their origin, acceleration and propagation in our galaxy, but also for predicting their effects (on technology and on the Earth's environment and organisms and for interpreting abundances of cosmogenic isotopes in meteorites and terrestrial reservoirs. In contrast to the early interplanetary measurements, there is growing evidence for a dominant role in GCR shielding of the total open magnetic flux, which emerges from the solar atmosphere and enters the heliosphere. In this paper, we relate a strong 1.68-year oscillation in GCR fluxes to a corresponding oscillation in the open solar magnetic flux and infer cosmic-ray propagation paths confirming the predictions of theories in which drift is important in modulating the cosmic ray flux. Key words. Interplanetary physics (Cosmic rays, Interplanetary magnetic fields

  10. Improved room-temperature-selectivity between Nd and Fe in Nd recovery from Nd-Fe-B magnet

    Energy Technology Data Exchange (ETDEWEB)

    Kataoka, Y.; Kitagawa, J., E-mail: j-kitagawa@fit.ac.jp [Department of Electrical Engineering, Faculty of Engineering, Fukuoka Institute of Technology, 3-30-1 Wajiro-higashi, Higashi-ku, Fukuoka 811-0295 (Japan); Ono, T.; Tsubota, M. [Physonit Inc., 6-10 Minami-Horikawa, Kaita Aki, Hiroshima 736-0044 (Japan)

    2015-11-15

    The sustainable society requires the recycling of rare metals. Rare earth Nd is one of rare metals, accompanying huge consumption especially in Nd-Fe-B magnets. Although the wet process using acid is in practical use in the in-plant recycle of sludge, higher selectivity between Nd and Fe at room temperature is desired. We have proposed a pretreatment of corrosion before the dissolution into HCl and the oxalic acid precipitation. The corrosion produces γ-FeOOH and a Nd hydroxide, which have high selectivity for HCl solution at room temperature. Nd can be recovered as Mn{sub 2}O{sub 3}-type Nd{sub 2}O{sub 3}. The estimated recovery-ratio of Nd reaches to 97%.

  11. Improved room-temperature-selectivity between Nd and Fe in Nd recovery from Nd-Fe-B magnet

    Directory of Open Access Journals (Sweden)

    Y. Kataoka

    2015-11-01

    Full Text Available The sustainable society requires the recycling of rare metals. Rare earth Nd is one of rare metals, accompanying huge consumption especially in Nd-Fe-B magnets. Although the wet process using acid is in practical use in the in-plant recycle of sludge, higher selectivity between Nd and Fe at room temperature is desired. We have proposed a pretreatment of corrosion before the dissolution into HCl and the oxalic acid precipitation. The corrosion produces γ-FeOOH and a Nd hydroxide, which have high selectivity for HCl solution at room temperature. Nd can be recovered as Mn2O3-type Nd2O3. The estimated recovery-ratio of Nd reaches to 97%.

  12. Room temperature magnetic and dielectric properties of cobalt doped CaCu3Ti4O12 ceramics

    Science.gov (United States)

    Mu, Chunhong; Song, Yuanqiang; Wang, Haibin; Wang, Xiaoning

    2015-05-01

    CaCu3Ti4-xCoxO12 (x = 0, 0.2, 0.4) ceramics were prepared by a conventional solid state reaction, and the effects of cobalt doping on the room temperature magnetic and dielectric properties were investigated. Both X-ray diffraction and energy dispersive X-ray spectroscopy confirmed the presence of Cu and Co rich phase at grain boundaries of Co-doped ceramics. Scanning electron microscopy micrographs of Co-doped samples showed a striking change from regular polyhedral particle type in pure CaCu3Ti4O12 (CCTO) to sheet-like grains with certain growth orientation. Undoped CaCu3Ti4O12 is well known for its colossal dielectric constant in a broad temperature and frequency range. The dielectric constant value was slightly changed by 5 at. % and 10 at. % Co doping, whereas the second relaxation process was clearly separated in low frequency region at room temperature. A multirelaxation mechanism was proposed to be the origin of the colossal dielectric constant. In addition, the permeability spectra measurements indicated Co-doped CCTO with good magnetic properties, showing the initial permeability (μ') as high as 5.5 and low magnetic loss (μ″ < 0.2) below 3 MHz. And the interesting ferromagnetic superexchange coupling in Co-doped CaCu3Ti4O12 was discussed.

  13. Shielding container

    International Nuclear Information System (INIS)

    Darling, K.A.M.

    1981-01-01

    A shielding container incorporates a dense shield, for example of depleted uranium, cast around a tubular member of curvilinear configuration for accommodating a radiation source capsule. A lining for the tubular member, in the form of a close-coiled flexible guide, provides easy replaceability to counter wear while the container is in service. Container life is extended, and maintenance costs are reduced. (author)

  14. AC conductivity, magnetic and shielding effectiveness studies on polyaniline embedded Co0.5Mn0.5Fe2O4 nanoparticles for electromagnetic interference suppression

    Science.gov (United States)

    Gurusiddesh, M.; Madhu, B. J.; Shankaramurthy, G. J.

    2018-05-01

    Electrically conducting Polyaniline (PANI)/Co0.5Mn0.5Fe2O4 nanocomposites are synthesized by in situ polymerization of aniline monomer in the presence of Co0.5Mn0.5Fe2O4 nanoparticles. Structural studies on the synthesized samples have been carried out using X-ray diffraction technique, Field emission scanning electron microscopy and Energy dispersive X-ray spectroscopy. Frequency dependent ac conductivity studies on the prepared samples revealed that conductivity of the composite is high compared to Co0.5Mn0.5Fe2O4 nanoparticles. Further, both the samples exhibited hysteresis behavior under the applied magnetic field. Electromagnetic interference (EMI) shielding effectiveness of both the samples decreases with increase in the applied frequency in the studied frequency range. Maximum shielding effectiveness (SE) of 31.49 dB and 62.84 dB were obtained for Co0.5Mn0.5Fe2O4 nanoparticles and PANI/Co0.5Mn0.5Fe2O4 nanocomposites respectively in the studied frequency range. Observed higher EMI shielding in the composites was attributed to its high electrical conductivity.

  15. Room-temperature synthesis of core-shell structured magnetic covalent organic frameworks for efficient enrichment of peptides and simultaneous exclusion of proteins.

    Science.gov (United States)

    Lin, Guo; Gao, Chaohong; Zheng, Qiong; Lei, Zhixian; Geng, Huijuan; Lin, Zian; Yang, Huanghao; Cai, Zongwei

    2017-03-28

    Core-shell structured magnetic covalent organic frameworks (Fe 3 O 4 @COFs) were synthesized via a facile approach at room temperature. Combining the advantages of high porosity, magnetic responsiveness, chemical stability and selectivity, Fe 3 O 4 @COFs can serve as an ideal absorbent for the highly efficient enrichment of peptides and the simultaneous exclusion of proteins from complex biological samples.

  16. Study of the radiation scattered and produced by concrete shielding of radiotherapy rooms and its effects on equivalent doses in patients' organs; Estudo da radiacao espalhada e produzida pela blindagem de concreto de salas de radioterapia e seus efeitos sobre doses equivalentes nos orgaos dos pacientes

    Energy Technology Data Exchange (ETDEWEB)

    Braga, K.L.; Rebello, W.F.; Andrade, E.R.; Gavazza, S.; Medeiros, M.P.C.; Mendes, R.M.S.; Gomes, R.G.; Silva, M.G., E-mail: kelmo.lins@gmail.com, E-mail: rebello@ime.eb.br, E-mail: fisica.dna@gmail.com, E-mail: sergiogavazza@yahoo.com, E-mail: eng.cavaliere@gmail.com, E-mail: raphaelmsm@gmail.com, E-mail: ggrprojetos@gmail.com, E-mail: maglosilva15@gmail.com [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil). Secao de Engenharia Nuclear; Thalhofer, J.L.; Silva, A.X., E-mail: jardellt@yahoo.com.br, E-mail: ademir@con.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Energia Nuclear; Santos, R.F.G., E-mail: raphaelfgsantos@gmail.com [Centro Universitario Anhanguera, Niteroi, RJ (Brazil). Departamento de Engenharia

    2015-07-01

    Within a radiotherapy room, in addition to the primary beam, there is also secondary radiation due to the leakage of the accelerator head and the radiation scattering from room objects, patient and even the room's shielding itself, which is projected to protect external individuals disregarding its effects on the patient. This work aims to study the effect of concrete shielding wall over the patient, taking into account its contribution on equivalent doses. The MCNPX code was used to model the linear accelerator Varian 2100/2300 C/D operating at 18MeV, with MAX phantom representing the patient undergoing radiotherapy treatment for prostate cancer following Brazilian Institute of Cancer four-fields radiation application protocol (0°, 90°, 180° and 270°). Firstly, the treatment was patterned within a standard radiotherapy room, calculating the equivalent doses on patient's organs individually. In a second step, this treatment was modeled withdrawing the walls, floor and ceiling from the radiotherapy room, and then the equivalent doses calculated again. Comparing these results, it was found that the concrete has an average shielding contribution of around 20% in the equivalent dose on the patient's organs. (author)

  17. Room temperature photoinduced magnetism in [py.H]{sub 3}[FeCl{sub 4}]{sub 2}Cl

    Energy Technology Data Exchange (ETDEWEB)

    Baniasadi, F. [Physics Department, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Tehranchi, M.M., E-mail: teranchi@sbu.ac.ir [Physics Department, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Fathi, M.B. [Physics Department, Kharazmi University, Tehran (Iran, Islamic Republic of); Hamidi, S.M. [Laser and Plasma Research Institute, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Safari, N.; Amani, V. [Faculty of Chemistry, Shahid Beheshti University, Tehran (Iran, Islamic Republic of)

    2015-11-15

    Photoinduced magnetism in a homogeneous solution of [py.H]{sub 3}[FeCl{sub 4}]{sub 2}Cl is measured by Faraday rotation in visible light (λ∼450–750 nm) at room temperature. The physics of this phenomenon may be attributed to electronic transitions caused by absorption of light. X-ray diffraction and Debye function analysis are therefore applied to find the abundant unit of molecules dissolved in the solution which are being further utilized to investigate the electronic structure and molecular orbitals by means of hybrid density function theory (B3LYP). Faraday rotation is observed at certain wavelengths consistent with energy differences of HOMO-LUMO energy levels. Thus this work puts forward a new material with certain photomagnetic properties which may be used in fabrication of room temperature magneto-optical switches. - Highlights: • Photoinduced magnetism in (FeCl{sub 4}){sub 2}(py.H){sub 3}Cl is illustrated via Faraday rotation. • The abundant unit of molecule is characterized by Debye function analysis of XRD. • PIM in the molecule is attributed to the charge transfer between HOMO-LUMO.

  18. Near fifty percent sodium substituted lanthanum manganites—A potential magnetic refrigerant for room temperature applications

    Energy Technology Data Exchange (ETDEWEB)

    Sethulakshmi, N.; Anantharaman, M. R., E-mail: mraiyer@yahoo.com [Department of Physics, Cochin University of Science and Technology, Cochin 682022, Kerala (India); Al-Omari, I. A. [Department of Physics, Sultan Qaboos University, PC 123 Muscat, Sultanate of Oman (Oman); Suresh, K. G. [Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India)

    2014-03-03

    Nearly half of lanthanum sites in lanthanum manganites were substituted with monovalent ion-sodium and the compound possessed distorted orthorhombic structure. Ferromagnetic ordering at 300 K and the magnetic isotherms at different temperature ranges were analyzed for estimating magnetic entropy variation. Magnetic entropy change of 1.5 J·kg{sup −1}·K{sup −1} was observed near 300 K. An appreciable magnetocaloric effect was also observed for a wide range of temperatures near 300 K for small magnetic field variation. Heat capacity was measured for temperatures lower than 300 K and the adiabatic temperature change increases with increase in temperature with a maximum of 0.62 K at 280 K.

  19. Thermomechanical study of complex structures in the aperture of superconducting magnets: Application to the design of the High-Luminosity LHC shielded beam screen

    CERN Document Server

    AUTHOR|(CDS)2086332; Aurisicchio, Marco

    In the framework of the High-Luminosity Large Hadron Collider (HL-LHC) project, a complex structure, known as the beam screen, will be installed by 2024 in the aperture of the inner triplet superconducting magnets nearby the ATLAS and CMS experiments. The beam screen is an octagonal shaped pipe that shields the 1.9 K magnet cryogenic system from the heat loads and damage to the magnet coils that would be otherwise induced by the highly penetrating collision debris. It also ensures that the vacuum conditions, required for the stability of the beam, are met. This thesis describes the design of the beam screen and proposes extensions to important components and features. The unknown physical properties of the beam screen materials have been characterised. The thermal behaviour of the beam screen during normal working conditions has been optimised by simulations and validated by measurements. The behaviour of the beam screen during a magnet quench, a resistive transition of the superconducting magnet, has been st...

  20. Electromagnetic shield

    International Nuclear Information System (INIS)

    Miller, J.S.

    1987-01-01

    An electromagnetic shield is described comprising: closed, electrically-conductive rings, each having an open center; and binder means for arranging the rings in a predetermined, fixed relationship relative to each other, the so-arranged rings and binder means defining an outer surface; wherein electromagnetic energy received by the shield from a source adjacent its outer surface induces an electrical current to flow in a predetermined direction adjacent and parallel to the outer surface, through the rings; and wherein each ring is configured to cause source-induced alternating current flowing through the portion of the ring closest to the outer surface to electromagnetically induce an oppositely-directed current in the portion of the ring furthest from the surface, such oppositely-directed current bucking any source-induced current in the latter ring portion and thus reducing the magnitude of current flowing through it, whereby the electromagnetic shielding effected by the shield is enhanced

  1. Neutron shieldings

    International Nuclear Information System (INIS)

    Tarutani, Kohei

    1979-01-01

    Purpose: To decrease the stresses resulted by the core bendings to the base of an entrance nozzle. Constitution: Three types of round shielding rods of different diameter are arranged in a hexagonal tube. The hexagonal tube is provided with several spacer pads receiving the loads from the core constrain mechanism at its outer circumference, a handling head for a fuel exchanger at its top and an entrance nozzle for self-holding the neutron shieldings and flowing heat-removing coolants at its bottom. The diameters for R 1 , R 2 and R 3 for the round shielding rods are designed as: 0.1 R 1 2 1 and 0.2 R 1 2 1 . Since a plurality of shielding rods of small diameter are provided, soft structure are obtained and a plurality of coolant paths are formed. (Furukawa, Y.)

  2. Nuclear shields

    International Nuclear Information System (INIS)

    Linares, R.C.; Nienart, L.F.; Toelcke, G.A.

    1976-01-01

    A process is described for preparing melt-processable nuclear shielding compositions from chloro-fluoro substituted ethylene polymers, particularly PCTFE and E-CTFE, containing 1 to 75 percent by weight of a gadolinium compound. 13 claims, no drawings

  3. REACTOR SHIELD

    Science.gov (United States)

    Wigner, E.P.; Ohlinger, L.E.; Young, G.J.; Weinberg, A.M.

    1959-02-17

    Radiation shield construction is described for a nuclear reactor. The shield is comprised of a plurality of steel plates arranged in parallel spaced relationship within a peripheral shell. Reactor coolant inlet tubes extend at right angles through the plates and baffles are arranged between the plates at right angles thereto and extend between the tubes to create a series of zigzag channels between the plates for the circulation of coolant fluid through the shield. The shield may be divided into two main sections; an inner section adjacent the reactor container and an outer section spaced therefrom. Coolant through the first section may be circulated at a faster rate than coolant circulated through the outer section since the area closest to the reactor container is at a higher temperature and is more radioactive. The two sections may have separate cooling systems to prevent the coolant in the outer section from mixing with the more contaminated coolant in the inner section.

  4. A flexible numerical model to study an active magnetic refrigerator for near room temperature applications

    Energy Technology Data Exchange (ETDEWEB)

    Aprea, Ciro; Maiorino, Angelo [Department of Mechanical Engineering, University of Salerno, Via Ponte Don Melillo 1, 84084 Fisciano (Salerno) (Italy)

    2010-08-15

    Magnetic refrigeration is an emerging technology based on the magnetocaloric effect in solid-state refrigerants. This technology offers a smaller global environmental impact than the refrigeration obtained by means of the classical vapor compression machines operating with fluids such as HFCs. The Active Magnetic Regenerative Refrigeration (AMRR) is currently the most studied ant tested magnetic cycle. It combines the regenerative properties of a high specific heat solid porous matrix with the ability of performing thermo-magnetic cycles thanks to the magnetocaloric property of the refrigerant; while a fluid pulsing through the regenerator works as a heat transfer medium. An active magnetic regenerator can provide larger temperature spans making up for the local small temperature variation of the refrigerant. In the present paper, a practical model for predicting the performance and efficiency of an AMRR cycle has been developed. The model evaluates both the refrigerant properties and the entire cycle of an AMR operating in conformity with a Brayton regenerative cycle. The magnetocaloric material of choice is gadolinium, while the heat transfer medium is liquid water. With this model can be predicted the refrigeration capacity, the power consumption and consequently the Coefficient of Performance. The results show a greater COP when compared to a classical vapor compression plant working between the same temperature levels. (author)

  5. A flexible numerical model to study an active magnetic refrigerator for near room temperature applications

    International Nuclear Information System (INIS)

    Aprea, Ciro; Maiorino, Angelo

    2010-01-01

    Magnetic refrigeration is an emerging technology based on the magnetocaloric effect in solid-state refrigerants. This technology offers a smaller global environmental impact than the refrigeration obtained by means of the classical vapor compression machines operating with fluids such as HFCs. The Active Magnetic Regenerative Refrigeration (AMRR) is currently the most studied ant tested magnetic cycle. It combines the regenerative properties of a high specific heat solid porous matrix with the ability of performing thermo-magnetic cycles thanks to the magnetocaloric property of the refrigerant; while a fluid pulsing through the regenerator works as a heat transfer medium. An active magnetic regenerator can provide larger temperature spans making up for the local small temperature variation of the refrigerant. In the present paper, a practical model for predicting the performance and efficiency of an AMRR cycle has been developed. The model evaluates both the refrigerant properties and the entire cycle of an AMR operating in conformity with a Brayton regenerative cycle. The magnetocaloric material of choice is gadolinium, while the heat transfer medium is liquid water. With this model can be predicted the refrigeration capacity, the power consumption and consequently the Coefficient of Performance. The results show a greater COP when compared to a classical vapor compression plant working between the same temperature levels.

  6. Production Follow-Up of the LHC Main Dipoles through Magnetic Measurements at Room Temperature

    CERN Document Server

    Wildner, E; Remondino, Vittorio; Scandale, Walter; Todesco, Ezio; Völlinger, C

    2004-01-01

    In this paper we review the tools used for controlling the production of the LHC main dipoles through warm magnetic measurements. For the collared coil measurements, control limits are based on the statistics relative to the pre-series production. For the cold mass, the difference between collared coil and cold mass is considered, allowing a very stringent test. In both cases, measurements are split in straight part average, variations and coil ends contributions. Two different alarm levels exist in case the measured field is out of limits. The analysis can be carried out at the manufacturer and allows detection of anomalies in the measured magnetic field. These can be either due to wrong measurements or caused by assembly defects. Techniques used to work out information on the magnet assembly from the field harmonics are outlined. We summarize the experience gathered on about 180 collared coils and 120 cold masses, pointing out the bad cases and investigating the reliability of the measurements.

  7. Martensitic transition near room temperature and the temperature- and magnetic-field-induced multifunctional properties of Ni49CuMn34In16 alloy

    Science.gov (United States)

    Sharma, V. K.; Chattopadhyay, M. K.; Khandelwal, A.; Roy, S. B.

    2010-11-01

    A near room-temperature martensitic transition is observed in the ferromagnetic austenite state of Ni50Mn34In16 alloy with 2% Cu substitution at the Ni site. Application of magnetic field in the martensite state induces a reverse martensitic transition in this alloy. dc magnetization, magnetoresistance and strain measurements in this alloy reveal that associated with this martensitic transition there exist a large magnetocaloric effect, a large magnetoresitance and a magnetic-field temperature-induced strain. This NiMnIn alloy system thus is an example of an emerging class of magnetic materials whose physical properties can be tuned by suitable chemical substitutions, to achieve magnetic-field and temperature-induced multifunctional properties at and around room temperature

  8. Cage for shield-type support. Schildausbaugestell

    Energy Technology Data Exchange (ETDEWEB)

    Harryers, W; Blumenthal, G; Irresberger, H

    1981-08-13

    A cage for shield-type support containing a fracture shield supported by a hydraulic stamp and a projecting roof bar was constructed in such a way that no cellular shirt is needed to timber the caved room. The roof bar which is linked at a joint axis at the face-side end of the fracture shield is formed at the face side as a multiply foldable bar. (HGOE).

  9. Passive characterization and active testing of epoxy bonded regenerators for room temperature magnetic refrigeration

    DEFF Research Database (Denmark)

    Lei, Tian; Navickaité, Kristina; Engelbrecht, Kurt

    2017-01-01

    -layer AMR based on spherical particles is tested actively in a small reciprocating magnetic refrigerator, achieving a no-load temperature span of 16.8 °C using about 143 g of epoxy-bonded La(Fe,Mn,Si)13Hy materials. Simulations based on a one-dimensional (1D) AMR model are also implemented to validate......Epoxy bonded regenerators of both spherical and irregular La(Fe,Mn,Si)13Hy particles have been developed aiming at increasing the mechanical strength of active magnetic regenerators (AMR) loaded with brittle magnetocaloric materials and improving the flexibility of shaping the regenerator geometry....... Although the magnetocaloric properties of these materials are well studied, the flow and heat transfer characteristics of the epoxy bonded regenerators have seldom been investigated. This paper presents a test apparatus that passively characterizes regenerators using a liquid heat transfer fluid...

  10. Hidden magnetic states emergent under electric field, in a room temperature composite magnetoelectric multiferroic

    Czech Academy of Sciences Publication Activity Database

    Clarkson, J.D.; Fina, I.; Liu, Z.Q.; Lee, Y.; Kim, J.; Frontera, C.; Cordero, K.; Wisotzki, S.; Sánchez, F.; Sort, J.; Hsu, S.L.; Ko, C.; Aballe, L.; Foerster, M.; Wu, J.; Christen, H.M.; Heron, J.T.; Schlom, D. G.; Salahuddin, S.; Kioussis, N.; Fontcuberta, J.; Martí, Xavier; Ramesh, R.

    2017-01-01

    Roč. 7, č. 1 (2017), s. 1-7, č. článku 15460. ISSN 2045-2322 R&D Projects: GA ČR GB14-37427G Institutional support: RVO:68378271 Keywords : antiferromagnetic phase-transition * total-energy calculations * wave basis-set Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 4.259, year: 2016

  11. La0.7Sr0.3MnO3 Thin Films for Magnetic and Temperature Sensors at Room Temperature

    Directory of Open Access Journals (Sweden)

    Sheng Wu

    2012-03-01

    Full Text Available In this paper, the potentialities of the manganese oxide La0.7Sr0.3MnO3 (LSMO for the realization of sensitive room temperature thermometers and magnetic sensors are discussed. LSMO exhibits both a large change of the resistance versus temperature at its metal-to-insulator transition (about 330 K and low field magnetoresistive effects at room temperature. The sensor performances are described in terms of signal-to-noise ratio in the 1 Hz - 100 kHz frequency range. It is shown that due to the very low 1/f noise level, LSMO based sensors can exhibit competitive performances at room temperature.

  12. Doping dependent room-temperature ferromagnetism and structural properties of dilute magnetic semiconductor ZnO:Cu2+ nanorods

    International Nuclear Information System (INIS)

    Sharma, Prashant K.; Dutta, Ranu K.; Pandey, Avinash C.

    2009-01-01

    Copper doped ZnO nanoparticles were synthesized by the chemical technique based on the hydrothermal method. The crystallite structure, morphology and size were determined by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM) for different doping percentages of Cu 2+ (1-10%). TEM/SEM images showed formation of uniform nanorods, the aspect ratio of which varied with doping percentage of Cu 2+ . The wurtzite structure of ZnO gradually degrades with the increasing Cu 2+ doping concentration and an additional CuO associated diffraction peak was observed above 8% of Cu 2+ doping. The change in magnetic behavior of the nanoparticles of ZnO with varying Cu 2+ doping concentrations was investigated using a vibrating sample magnetometer (VSM). Initially these nanoparticles showed strong room-temperature ferromagnetic behavior, however at higher doping percentage of copper the ferromagnetic behavior was suppressed and paramagnetic nature was enhanced.

  13. Room Temperature Spin Mediated Coupling in Hybrid Magnetic, Organic, and Oxide Structures and Devices

    Science.gov (United States)

    2015-12-07

    ADDRESS (ES) U.S. Army Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 spintronics, magnetic memory , multiferroics, organic...nano-oscillators for memory and computation, Nanotechnology, (03 2011): 0. doi: 10.1088/0957-4484/22/9/095301 F. Wang, J. Rybicki, K. Hutchinson...A dI/dV characteristics ( colour coded) as a function of four-terminal voltage V23 and side gate voltage Vsg in the open wire. c, dI/dV

  14. Room-Temperature Spin-Mediated Coupling in Hybrid Magnetic, Organic, and Oxide Structures and Devices

    Science.gov (United States)

    2015-12-07

    ADDRESS (ES) U.S. Army Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 spintronics, magnetic memory , multiferroics, organic...nano-oscillators for memory and computation, Nanotechnology, (03 2011): 0. doi: 10.1088/0957-4484/22/9/095301 F. Wang, J. Rybicki, K. Hutchinson...A dI/dV characteristics ( colour coded) as a function of four-terminal voltage V23 and side gate voltage Vsg in the open wire. c, dI/dV

  15. Radiation shielding

    International Nuclear Information System (INIS)

    Aitken, D.

    1979-01-01

    Shields for equipment in which ionising radiation is associated with high electrical gradients, for example X-ray tubes and particle accelerators, incorporate a radiation-absorbing metal, as such or as a compound, and are electrically non-conducting and can be placed in the high electrical gradient region of the equipment. Substances disclosed include dispersions of lead, tungsten, uranium or oxides of these in acrylics polyesters, PVC, ABS, polyamides, PTFE, epoxy resins, glass or ceramics. The material used may constitute an evacuable enclosure of the equipment or may be an external shield thereof. (U.K.)

  16. Effect of Yb substitution on room temperature magnetic and dielectric properties of bismuth ferrite nanoparticles

    Science.gov (United States)

    Remya, K. P.; Amirthapandian, S.; Manivel Raja, M.; Viswanathan, C.; Ponpandian, N.

    2016-10-01

    Effect of the Yb dopant on the structural, magnetic, and electrical properties of the multiferroic BiFeO3 have been studied. The structural properties of sol-gel derived Bi1-xYbxFeO3 (x = 0.0, 0.1, and 0.2) nanoparticles reveal the formation of a rhombohedrally distorted perovskite in XRD and a reduction in the average grain size have been observed with an increase in the Yb concentration. Microstructural studies exhibited the formation of sphere like morphology with decreasing particle size with increase in the dopant concentration. The effective doping also resulted in larger magnetization as well as coercivity with the maximum of 257 Oe and 1.76 emu/g in the Bi0.8Yb0.2FeO3 nanoparticles. Ferroelectric as well as dielectric properties of the nanoparticles were also improved on doping. The best results were obtained for the BiFeO3 nanoparticles having Yb concentration x = 0.2.

  17. Preparation and characterization of magnetic nanoparticles (Fe_3O_4) coated with oleic acid at room temperature

    International Nuclear Information System (INIS)

    Souza, Marcio Nele de; Feuser, Paulo Emilio

    2010-01-01

    This work studied a method for preparation of Fe_3O_4 magnetic nanoparticles stabilized with acid oleic precipitating Fe"+"2 and Fe"+"3 (1:1) salts at room temperature. The method involved the coprecipitation of Fe_3O_4 in aqueous solution from FeCl_3·6H_2O and FeSO_4·7H_2O solutions using as NH_4OH (30%) precipitation agent. The final size of nanoparticles was 10nn with an initial pH of 0-1 and a final neutral pH, without addition of an acid and/ or hydroxide to adjust the pH of the material. The oleic acid coated nanoparticles were characterized by Ray-X of Diffraction (DRX), thermogravimetric analysis (TGA), scanning electron microscopy in field emission and dynamic light scattering (FEG-SEM). It is important to standardize the methods of preparation of Fe_3O_4 Magnetic Nanoparticles stabilized with oleic acid, to obtain a desired material for a given application it is in technology or Biomedical. (author)

  18. Effect of oxygen vacancy induced by pulsed magnetic field on the room-temperature ferromagnetic Ni-doped ZnO synthesized by hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Min [Shanghai University, Laboratory for Microstructures, School of Materials Science and Engineering, 149 Yanchang Road, 200072 Shanghai (China); Li, Ying, E-mail: liying62@shu.edu.cn [Shanghai University, Laboratory for Microstructures, School of Materials Science and Engineering, 149 Yanchang Road, 200072 Shanghai (China); Tariq, Muhammad; Hu, Yemin; Li, Wenxian; Zhu, Mingyuan; Jin, Hongmin [Shanghai University, Laboratory for Microstructures, School of Materials Science and Engineering, 149 Yanchang Road, 200072 Shanghai (China); Li, Yibing [School of Chemistry, The University of New South Wales, Sydney, NSW, 2052 (Australia)

    2016-08-05

    Room temperature ferromagnetic 2% Ni doped ZnO rods were synthesized by high pulsed magnetic field-assisted hydrothermal method. A detailed study on the effect of high pulsed magnetic field on morphology, structural and magnetic properties of the ZnO rods has been carried out systematically by varying the intensity of field from 0 to 4 T. X-ray diffraction, Energy-dispersive spectroscopy measurements, and Raman spectra analysis suggest that all the samples have hexagonal wurtzite structure without detectable impurity. Field emission scanning electron microscopy images indicate that the particle size of samples decrease with increasing intensity of field. High resolution transmission electron microscopy observation ensures that the Ni ions addition do not change the wurtzite host matrix. X-ray photoelectron spectroscopy confirms the incorporation of Ni elements as divalent state and the dominant presence of oxygen vacancies in samples fabricated under 4 T pulsed magnetic field. Hysteresis loops demonstrate that the saturation magnetization increased regularly with the mounting magnetic field. On the framework of bound magnetic polaron model, the rising content of oxygen vacancies, as donor defect, lead to the stronger ferromagnetism in samples with pulsed magnetic field. Our findings provide a new insight for tuning the defect density by precisely controlling the intensity of field in order to get the desired magnetic behavior at room temperature. - Graphical abstract: This figure shows the magnetization versus magnetic field curves for 2%Ni doped ZnO as prepared with 0, 1, 2, 3 and 4 T pulsed magnetic field at 290 K. For 0 T sample, no ferromagnetic response is observed. But all the samples synthesized with field were well-defined hysteresis loops. The saturation magnetization estimated from the hysteresis loop come out to be ∼0.0024, 0.0023, 0.0036 and 0.0061 emu/g for 1 T, 2 T, 3 T and 4 T samples, respectively. As shown in the curves, the room

  19. Gonadal shield.

    Science.gov (United States)

    Purdy, J A; Stiteler, R D; Glasgow, G P; Mill, W B

    1975-10-01

    A secondary gonadal shield for use in the pelvic irradiation of males was designed and built using material and apparatus available with the Cerrobend blocking system. The gonadal dose was reduced to approximately 1.5 to 2.5% of the given dose.

  20. Novel room-temperature spin-valve-like magnetoresistance in magnetically coupled nano-column Fe3O4/Ni heterostructure.

    Science.gov (United States)

    Xiao, Wen; Song, Wendong; Herng, Tun Seng; Qin, Qing; Yang, Yong; Zheng, Ming; Hong, Xiaoliang; Feng, Yuan Ping; Ding, Jun

    2016-08-25

    Herein, we design a room-temperature spin-valve-like magnetoresistance in a nano-column Fe3O4/Ni heterostructure without using a non-magnetic spacer or pinning layer. An Fe3O4 nano-column film is self-assembled on a Ni underlayer by the thermal decomposition method. The wet-chemical self-assembly is facile, economical and scalable. The magnetoresistance (MR) response of the Ni underlayer in the heterostructure under positive and negative out-of-plane magnetic fields differ by ∼0.25 at room temperature and ∼0.43 at 100 K. We attribute the spin-valve-like magnetoresistance to the unidirectional magnetic anisotropy of the Ni underlayer when being magnetically coupled by the Fe3O4 nano-column film. The out-of-plane negative-field magnetization is higher than the positive-field magnetization, affirming the unidirectional magnetic anisotropy of the Fe3O4/Ni heterostructure. Temperature-dependent magnetic and resistivity studies illustrate a close correlation between the magnetization transition of Fe3O4 and resistivity transition of Ni and prove a magnetic coupling between the Fe3O4 and Ni. First-principles calculations reveal that the Fe3O4/Ni model under a negative magnetic field is energetically more stable than that under a positive magnetic field. Furthermore, partial density of states (PDOS) analysis demonstrates the unidirectional magnetic anisotropy of the Ni 3d orbital. This is induced by the strong ferromagnetic coupling between Fe3O4 and Ni via oxygen-mediated Fe 3d-O 2p-Ni 3d hybridizations.

  1. The use of steel and lead shieldings in radiotherapy rooms and its comparison with respect to neutrons doses at patients; Comparacao de blindagens de aco e de chumbo usadas em salas de radioterapia quanto a dose devido a neutrons depositada em pacientes

    Energy Technology Data Exchange (ETDEWEB)

    Silva, M.G.; Rebello, W.F.; Andrade, E.R.; Medeiros, M.P.C.; Mendes, R.M.S.; Braga, K.L.; Gomes, R.G., E-mail: maglosilva15@gmail.com, E-mail: rebello@ime.eb.br, E-mail: fisica.dna@gmail.com, E-mail: eng.cavaliere@gmail.com, E-mail: raphaelmsm@gmail.com, E-mail: kelmo.lins@gmail.com, E-mail: ggrprojetos@gmail.com [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil); Santos, R.F.G., E-mail: raphaelfgsantos@gmail.com [Centro Universitario Anhanguera, Niteroi, RJ (Brazil). Departamento de Engenharia; Silva, Ademir X., E-mail: ademir@con.ufrj.br [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil)

    2015-07-01

    The NCRP Report No. 151, Structural Shielding Design and Evaluation for Megavoltage X- and Gamma-Ray Radiotherapy Facilities, considers, in shielding calculations for radiotherapy rooms, the use of lead and/or steel to be applied on bunker walls. The NCRP Report calculations were performed foreseeing a better protection of people outside the radiotherapy room. However, contribution of lead and steel to patient dose should be taken into account for radioprotection purposes. This work presents calculations performed by MCNPX code in analyzing the Ambient Dose Equivalent due to neutron, H*(10){sub n}, within a radiotherapy room, in the patients area, considering the use of additional shielding of 1 TVL of lead or 1 TVL of steel, positioned at the inner faces of walls and ceiling of a bunker. The head of the linear accelerator Varian 2100/2300 C/D was modeled working at 18MeV, with 5x5cm{sup 2}, 10x10cm{sup 2}, 20x20cm{sup 2}, 30x30cm{sup 2} and 40x40cm{sup 2} openings for jaws and MLC and operating in eight gantry's angles. This study shows that the use of lead generates an average value of H*(10){sub n} at patients area, 8.02% higher than the expected when using steel. Further studies should be performed based on experimental data for comparison with those from MCNPX simulation.

  2. Understanding newly discovered oscillation modes in magnetically shielded Hall thrusters utilizing state of the art high speed diagnostics.

    Data.gov (United States)

    National Aeronautics and Space Administration — I propose to investigate the newly discovered oscillation modes specific to Magnetically Shied (MS) Hall Effect Thrusters (HET). Although HETs are classified as a...

  3. Room Temperature Magnetic Field Measurements as a Tool to Localize Inter-turns Electrical Short Circuits in the LHC Main Dipole coils

    CERN Document Server

    Bellesia, B; Todesco, E

    2006-01-01

    In this report the method for the localization of the electric shorts circuits in the main LHC dipoles using the magnetic measurements at room temperature is presented. The steps of the method are discussed, and two cases are studied in detail. A complete statistics of the 12 cases analyzed up to now is given.

  4. Room temperature superconductors

    International Nuclear Information System (INIS)

    Sleight, A.W.

    1995-01-01

    If the Holy Grail of room temperature superconductivity could be achieved, the impact on could be enormous. However, a useful room temperature superconductor for most applications must possess a T c somewhat above room temperature and must be capable of sustaining superconductivity in the presence of magnetic fields while carrying a significant current load. The authors will return to the subject of just what characteristics one might seek for a compound to be a room temperature superconductor. 30 refs., 3 figs., 1 tab

  5. Radiation shielding

    International Nuclear Information System (INIS)

    Yue, D.D.

    1979-01-01

    Details are given of a cylindrical electric penetration assembly for carrying instrumentation leads, used in monitoring the performance of a nuclear reactor, through the containment wall of the reactor. Effective yet economical shielding protection against both fast neutron and high-energy gamma radiation is provided. Adequate spacing within the assembly allows excessive heat to be efficiently dissipated and means of monitoring all potential radiation and gas leakage paths are provided. (UK)

  6. Shielded container

    International Nuclear Information System (INIS)

    Fries, B.A.

    1978-01-01

    A shielded container for transportation of radioactive materials is disclosed in which leakage from the container is minimized due to constructional features including, inter alia, forming the container of a series of telescoping members having sliding fits between adjacent side walls and having at least two of the members including machine sealed lids and at least two of the elements including hand-tightenable caps

  7. A primary exploration to quasi-two-dimensional rare-earth ferromagnetic particles: holmium-doped MoS2 sheet as room-temperature magnetic semiconductor

    Science.gov (United States)

    Chen, Xi; Lin, Zheng-Zhe

    2018-05-01

    Recently, two-dimensional materials and nanoparticles with robust ferromagnetism are even of great interest to explore basic physics in nanoscale spintronics. More importantly, room-temperature magnetic semiconducting materials with high Curie temperature is essential for developing next-generation spintronic and quantum computing devices. Here, we develop a theoretical model on the basis of density functional theory calculations and the Ruderman-Kittel-Kasuya-Yoshida theory to predict the thermal stability of two-dimensional magnetic materials. Compared with other rare-earth (dysprosium (Dy) and erbium (Er)) and 3 d (copper (Cu)) impurities, holmium-doped (Ho-doped) single-layer 1H-MoS2 is proposed as promising semiconductor with robust magnetism. The calculations at the level of hybrid HSE06 functional predict a Curie temperature much higher than room temperature. Ho-doped MoS2 sheet possesses fully spin-polarized valence and conduction bands, which is a prerequisite for flexible spintronic applications.

  8. Role of Magnetocardiography in Emergency Room

    International Nuclear Information System (INIS)

    Kwon, H.; Kim, K.; Kim, J. M.; Lee, Y. H.; Kim, T. E.; Lim, H. K.; Park, Y. K.; Ko, Y. G.; Chung, N.

    2006-01-01

    In emergency rooms, patients with acute chest pain should be diagnosed as quickly as possible with higher diagnostic accuracy for an appropriate therapy to the patients with acute coronary syndrome or for avoiding unnecessary hospital admissions. At present, electrocardiography(ECG) and biochemical markers are generally used to detect myocardial infarction and coronary angiography is used as a gold standard to reveal the degree of narrowing of coronary artery. Magnetocardiography(MCG) has been proposed as a novel and non-invasive diagnostic tool fur the detection of cardiac electrical abnormality associated with myocardial ischemia. In this study, we examined whether the MCG can be used fur the detection of coronary artery disease(CAD) in patients, who were admitted to the emergency room with acute chest pain. MCG was recorded from 36 patients admitted to the emergency room with suspected acute coronary syndrome. The MCG recordings were obtained using a 64-channel SQUID MCG system in a magnetically shielded room. In result, presence of CAD could be found with a sensitivity of 88.2 % in patients with acute chest pain without 57 elevation in ECG, demonstrating a possible use in the emergency room to screen CAD patients.

  9. Initial progress in the first wall, blanket, and shield Engineering Test Program for magnetically confined fusion-power reactors

    International Nuclear Information System (INIS)

    Herman, H.; Baker, C.C.; Maroni, V.A.

    1981-10-01

    The first wall/blanket/shield (FW/B/S) Engineering Test Program (ETP) progressed from the planning stage into implementation during July, 1981. The program, generic in nature, comprises four Test Program Elements (TPE's), the emphasis of which is on defining the performance parameters for the Fusion Engineering Device (FED) and the major fusion device to follow FED. These elements are: (1) nonnuclear thermal-hydraulic and thermomechanical testing of first wall and component facsimiles with emphasis on surface heat loads and heat transient (i.e., plasma disruption) effects; (2) nonnuclear and nuclear testing of FW/B/S components and assemblies with emphasis on bulk (nuclear) heating effects, integrated FW/B/S hydraulics and mechanics, blanket coolant system transients, and nuclear benchmarks; (3) FW/B/S electromagnetic and eddy current effects testing, including pulsed field penetration, torque and force restraint, electromagnetic materials, liquid metal MHD effects and the like; and (4) FW/B/S Assembly, Maintenance and Repair (AMR) studies focusing on generic AMR criteria, with the objective of preparing an AMR designers guidebook; also, development of rapid remote assembly/disassembly joint system technology, leak detection and remote handling methods

  10. Neutron shield analysis and design for the PDX fusion facility

    International Nuclear Information System (INIS)

    Grimesey, R.A.; Nigg, D.W.; Scott, A.J.; Wheeler, F.J.; Jassby, D.L.; Perry, E.D.

    1979-01-01

    The basic component of the biological shield for PDX is an existing 81 cm thick high-density concrete shielding wall surrounding the machine. The principal additional shielding requirement is a roof shield over the machine to reduce air-scattered skyshine dose into the PDX control room and to the site boundary. The roof shield is designed in removable sections on a steel support structure permitting overhead crane access to major PDX components. After analysis of a number of alternate concepts, a roof shield consisting of 50 cm of water in polyethylene tanks was selected to meet design objectives of effectiveness, weight, removability, and cost

  11. Enhancement the Armor Shielding Properties of CF/epoxy Composite by Addition Nanoparticles of Magnetic Iron Oxide

    Directory of Open Access Journals (Sweden)

    Fouda Hany

    2017-01-01

    Full Text Available In the present investigation, we prepared two types of CF composites. The first prepared composite sample was CF/epoxy resin composite and the second was CF/epoxy resin / with a different weight ratio of magnetic iron oxide. Magnetic iron oxide was prepared by co-precipitation method, with particle sizes measured in range 25:35 nm. The resistance to penetration of high kinetic energy projectile of the prepared composite sample was measured and It was found that addition of 5% nano-particles of magnetic iron oxide to composite material sample decrease the residual velocity of projectile penetrating it by 9%.i.e increasing resistance of the sample to penetration of high kinetic energy projectile.it was found that the Resistance to penetration of sheet of composite material sampleC4 of weight=40.32kg to projectile 7.62×39 mm AP at distance 15m equivalent to resistance of steel sheet of weight =54.6 kg at distance 200m.Resistance to penetration of sheet of composite material sampleC4 to projectile 7.62×39 mm AP at distance 10m equivalent to the resistance of high-quality steel sheet(steel4340 of weight=47.85 kg at distance 25m.

  12. Shielding technology for high energy radiation production facility

    International Nuclear Information System (INIS)

    Lee, Byung Chul; Kim, Heon Il

    2004-06-01

    In order to develop shielding technology for high energy radiation production facility, references and data for high energy neutron shielding are searched and collected, and calculations to obtain the characteristics of neutron shield materials are performed. For the evaluation of characteristics of neutron shield material, it is chosen not only general shield materials such as concrete, polyethylene, etc., but also KAERI developed neutron shields of High Density PolyEthylene (HDPE) mixed with boron compound (B 2 O 3 , H 2 BO 3 , Borax). Neutron attenuation coefficients for these materials are obtained for later use in shielding design. The effect of source shape and source angular distribution on the shielding characteristics for several shield materials is examined. This effect can contribute to create shielding concept in case of no detail source information. It is also evaluated the effect of the arrangement of shield materials using current shield materials. With these results, conceptual shielding design for PET cyclotron is performed. The shielding composite using HDPE and concrete is selected to meet the target dose rate outside the composite, and the dose evaluation is performed by configuring the facility room conceptually. From the result, the proper shield configuration for this PET cyclotron is proposed

  13. Assessment of Alphamagnetic Spectrometer (AMS) Upper Experiment Structural Configuration Shielding Effectiveness Associated with Change from Cryo-Cooled Magnet to Permanent Magnet

    Science.gov (United States)

    Scully, Robert

    2012-01-01

    In the spring of 2010, the Alpha Magnetic Spectrometer 2 (AMS-02) underwent a series of system level electromagnetic interference control measurements, followed by thermal vacuum testing. Shortly after completion of the thermal vacuum testing, the project decided to remove the cryogenically cooled superconducting magnet, and replace it with the original permanent magnet design employed in the earlier AMS- 01 assembly. Doing so necessitated several structural changes, as well as removal or modification of numerous electronic and thermal control devices and systems. At this stage, the project was rapidly approaching key milestone dates for hardware completion and delivery for launch, and had little time for additional testing or assessment of any impact to the electromagnetic signature of the AMS-02. Therefore, an analytical assessment of the radiated emissions behavioural changes associated with the system changes was requested.

  14. Giant room-temperature magnetoresistance in La0.8Tb0.2MnO3 under the low magnetic fields

    International Nuclear Information System (INIS)

    Zhang Yingtang; Chen Ziyu; Wang Chunchang; Jie Qiu; Lue Huibin

    2009-01-01

    Polycrystalline perovskite La 0.8 Tb 0.2 MnO 3 (LTMO) with an orthorhombic phase was synthesized by conventional solid-state reaction. The magnetic and electric properties of La 0.8 Tb 0.2 MnO 3 were examined. The striking finding is that the material exhibits giant magnetoresistance at room temperature as high as -31.8% and -35.7% under the low magnetic fields of 100 and 1000 Oe, respectively. This result suggests that La 0.8 Tb 0.2 MnO 3 has a promising potential in future device developments

  15. Core-dependent and ligand-dependent relativistic corrections to the nuclear magnetic shieldings in MH4-n Y n (n = 0-4; M = Si, Ge, Sn, and Y = H, F, Cl, Br, I) model compounds.

    Science.gov (United States)

    Maldonado, Alejandro F; Aucar, Gustavo A; Melo, Juan I

    2014-09-01

    The nuclear magnetic shieldings of Si, Ge, and Sn in MH(4-n) Y(n) (M = Si, Ge, Sn; Y = F, Cl, Br, I and n = 1-4) molecular systems are highly influenced by the substitution of one or more hydrogens by heavy-halogen atoms. We applied the linear response elimination of small components (LRESC) formalism to calculate those shieldings and learn whether including only a few of the leading relativistic correction terms is sufficient to be able to quantitatively reproduce the full relativistic value. It was observed that the nuclear magnetic shieldings change as the number of heavy halogen substituents and their weights vary, and the pattern of σ(M) generally does not exhibit the normal halogen dependence (NHD) behavior that can be seen in similar molecular systems containing carbon atoms. We also analyzed each relativistic correction afforded by the LRESC method and split them in two: core-dependent and ligand-dependent contributions; we then looked for the electronic mechanisms involved in the different relativistic effects and in the total relativistic value. Based on this analysis, we were able to study the electronic mechanism involved in a recently proposed relativistic effect, the "heavy atom effect on vicinal heavy atom" (HAVHA), in more detail. We found that the main electronic mechanism is the spin-orbit or σ p (T(3)) correction, although other corrections such as σ p (S(1)) and σ p (S(3)) are also important. Finally, we analyzed proton magnetic shieldings and found that, for molecules containing Sn as the central atom, σ(H) decreases as the number of heavy halogen substituents (of the same type: either F, Cl, or Br) increases, albeit at different rates for different halogens. σ(H) only increase as the number of halogen substituents increases if the halogen is iodine.

  16. Magnetic-field-induced decrease of the spin Peltier effect in Pt/Y3Fe5O12 system at room temperature

    Science.gov (United States)

    Itoh, Ryuichi; Iguchi, Ryo; Daimon, Shunsuke; Oyanagi, Koichi; Uchida, Ken-ichi; Saitoh, Eiji

    2017-11-01

    We report the observation of magnetic-field-induced decrease of the spin Peltier effect (SPE) in a junction of a paramagnetic metal Pt and a ferrimagnetic insulator Y3Fe5O12 (YIG) at room temperature. For driving the SPE, spin currents are generated via the spin Hall effect from applied charge currents in the Pt layer, and injected into the adjacent thick YIG film. The resultant temperature modulation is detected by a commonly used thermocouple attached to the Pt/YIG junction. The output of the thermocouple shows sign reversal when the magnetization is reversed and linearly increases with the applied current, demonstrating the detection of the SPE signal. We found that the SPE signal decreases with the magnetic field. The observed decreasing rate was found to be comparable to that of the spin Seebeck effect (SSE), suggesting the dominant and similar contribution of the low-energy magnons in the SPE as in the SSE.

  17. Magnetic properties of nanocrystalline CoFe{sub 2}O{sub 4} powders prepared at room temperature: variation with crystallite size

    Energy Technology Data Exchange (ETDEWEB)

    Rajendran, M.; Pullar, R.C.; Bhattacharya, A.K. E-mail: ashokbhattacharya@warwick.ac.uk; Das, D.; Chintalapudi, S.N.; Majumdar, C.K

    2001-06-01

    The magnetic properties of nanocrystalline CoFe{sub 2}O{sub 4} powders prepared by a redox process at room temperature have been studied by vibrating sample magnetometer (VSM). The average crystallite size of the powders varied from 6 to 20 nm by changing the synthesis conditions and the corresponding saturation magnetisation (M{sub s}) value ranged from 9 to 38 emu g{sup -1}. On heating, the crystallite size increased with corresponding increase in M{sub s} values. At 1073 K all samples achieved M{sub s} values close to 73 emu g{sup -1}. On increasing the crystallite size, the coercivity (H{sub c}) increased passed through a maximum and dropped. Cobalt ferrite powder with an average crystallite size of 6 nm prepared at room temperature achieved desirable values of M{sub s}=60 emu g{sup -1} and H{sub c}=1.42 kOe after thermal annealing at 973 K. The Moessbauer spectra were recorded for CoFe{sub 2}O{sub 4} having a range of crystallite sizes at room temperature and at low temperatures down to 40 K. The magnetic and Moessbauer results are provided for nanocrystalline CoFe{sub 2}O{sub 4} as a function of crystallite size and measurement temperature.

  18. About the Scythian Shields

    Directory of Open Access Journals (Sweden)

    About the Scythian Shields

    2017-10-01

    Full Text Available Shields played major role in the armament system of the Scythians. Made from organic materials, they are poorly traced on the materials of archaeological excavations. Besides, scaly surface of shields was often perceived in practice as the remnants of the scaly armor. E. V. Chernenko was able to discern the difference between shields’ scaly plates and armor scales. The top edge of the scales was bent inwards, and shield plates had a wire fixation. These observations let significantly increase the number of shields, found in the burial complexes of the Scythians. The comparison of archaeological materials and the images of Scythian warriors allow distinguishing the main forms of Scythian shields. All shields are divided into fencing shields and cover shields. The fencing shields include round wooden shields, reinforced with bronze sheet, and round moon-shaped shields with a notch at the top, with a metal scaly surface. They came to the Scythians under the Greek influence and are known in the monuments of the 4th century BC. Oval shields with scaly surface (back cover shields were used by the Scythian cavalry. They protected the rider in case of frontal attack, and moved back in case of maneuver or closein fighting. Scythian battle tactics were based on rapid approaching the enemy and throwing spears and further rapid withdrawal. Spears stuck in the shields of enemies, forcing them to drop the shields, uncover, and in this stage of the battle the archers attacked the disorganized ranks of the enemy. That was followed by the stage of close fight. Oval form of a wooden shield with leather covering was used by the Scythian infantry and spearmen. Rectangular shields, including wooden shields and the shields pleached from rods, represented a special category. The top of such shield was made of wood, and a pleached pad on leather basis was attached to it. This shield could be a reliable protection from arrows, but it could not protect against javelins

  19. Survey of shielding calculation parameters in radiotherapy rooms used in the country and its impact in the existing calculation methodologies; Levantamento de parametros de calculos de blindagem de salas de radioterapia utilizados no pais e seu impacto nas metodologias de calculo existentes

    Energy Technology Data Exchange (ETDEWEB)

    Japiassu, Fernando Parois

    2013-07-01

    When designing radiotherapy treatment rooms, the dimensions of barriers are established on the basis of American calculation methodologies specifically; NCRP Report N° 49, NCRP Report N° 51, and more recently, NCRP Report N° 151. Such barrier calculations are based on parameters reflecting predictions of treatments to be performed within the room; which, in tum, reftect a specific reality found in a country. There exists, however, a variety of modern radiotherapy techniques, such as Intensity Modulated Radiation Therapy (IMRT); Total Body Irradiation (TBl) and radiosurgery (SRS); where patierits are treated in a much different way than during more conventional treatrnents, which are not taken into account the traditional shielding calculation methodology. This may lead to a faulty design of treattnent rooms. In order to establish a comparison between the methodology used to calculate shielding design and the reality of treatments performed in Brazil, two radiotherapy facilitie were selected, both of them offering traditional and modern treatment techniqued as described above. Data in relation with reatments perfotmed over a period of six (6)months of operations in both institutions were collected. Based on tlis informaton, a new set of realistic parameters required for shielding design was estãblished, whicb in turn allowed for a nwe caculation of barrier thickness for both facilities. The barrier thickness resultaing from this calculation was then compared with the barrier thickness propose as part of the original shielding design, approved by the regulatory authority. First, concerning the public facility, the thickness of all primary barriers proposed in the shielding design was actually larger than the thickness resulting from calculations based on realistic parameters. Second, concerning the private facility, the new data show that the thickness of three out of the four primary barriers described in the project is larger than the thickness oresulting from

  20. Shielding effectiveness of superconductive particles in plastics

    International Nuclear Information System (INIS)

    Pienkowski, T.; Kincaid, J.; Lanagan, M.T.; Poeppel, R.B.; Dusek, J.T.; Shi, D.; Goretta, K.C.

    1988-09-01

    The ability to cool superconductors with liquid nitrogen instead of liquid helium has opened the door to a wide range of research. The well known Meissner effect, which states superconductors are perfectly diamagnetic, suggests shielding applications. One of the drawbacks to the new ceramic superconductors is the brittleness of the finished material. Because of this drawback, any application which required flexibility (e.g., wire and cable) would be impractical. Therefore, this paper presents the results of a preliminary investigation into the shielding effectiveness of YBa 2 Cu 3 O/sub 7-x/ both as a composite and as a monolithic material. Shielding effectiveness was measured using two separate test methods. One tested the magnetic (near field) shielding, and the other tested the electromagnetic (far field) shielding. No shielding was seen in the near field measurements on the composite samples, and only one heavily loaded sample showed some shielding in the far field. The monolithic samples showed a large amount of magnetic shielding. 5 refs., 5 figs

  1. Shielding benchmark problems

    International Nuclear Information System (INIS)

    Tanaka, Shun-ichi; Sasamoto, Nobuo; Oka, Yoshiaki; Kawai, Masayoshi; Nakazawa, Masaharu.

    1978-09-01

    Shielding benchmark problems were prepared by the Working Group of Assessment of Shielding Experiments in the Research Comittee on Shielding Design of the Atomic Energy Society of Japan, and compiled by the Shielding Laboratory of Japan Atomic Energy Research Institute. Twenty-one kinds of shielding benchmark problems are presented for evaluating the calculational algorithm and the accuracy of computer codes based on the discrete ordinates method and the Monte Carlo method and for evaluating the nuclear data used in the codes. (author)

  2. Room temperature magnetic ordering, enhanced magnetization and exchange bias of GdMnO_3 nanoparticles in (GdMnO_3)_0_._7_0(CoFe_2O_4)_0_._3_0

    International Nuclear Information System (INIS)

    Mitra, A.; Mahapatra, A.S.; Mallick, A.; Chakrabarti, P.K.

    2017-01-01

    Nanoparticles of GdMnO_3 (GMO) are prepared by sol-gel method. To enhance the magnetic property and also to obtain the magnetic ordering at room temperature (RT), nanoparticles of GMO are incorporated in the matrix of CoFe_2O_4 (CFO). Desired crystallographic phases of CFO, GMO and GMO-CFO are confirmed by analyzing X-ray diffractrograms (XRD) using Rietveld method. The average size of nanoparticles and their distribution, crystallographic phase, nanocrystallinity etc. are studied by high-resolution transmission electron microscope (HRTEM). Magnetic hysteresis loops (M-H) of GMO-CFO under zero field cooled (ZFC) and field cooled (FC) conditions are observed at different temperatures down to 5 K. Magnetization vs. temperature (M-T) under ZFC and FC conditions are also recorded. Interestingly, exchange bias (EB) is found at low temperature which suggests the encapsulation of the ferromagnetic (FM) nanoparticles of GMO by the ferrimagnetic nanoparticles of CFO below ~100 K. Enhanced magnetization, EB effect and RT magnetic ordering of GMO-CFO would be interesting for both theoretical and experimental investigations. - Highlights: • Nanoparticles of GdMnO_3 are incorporated in the matrix of CoFe_2O_4. • RT magnetic ordering of GMO nanoparticles in GMO-CFO is observed. • Magnetic property of GMO-CFO is highly enhanced compared to GMO. • Exchange bias is found in GMO-CFO at low temperature.

  3. Radiation shielding device

    International Nuclear Information System (INIS)

    Nakagawa, Takahiro; Yamagami, Makoto.

    1996-01-01

    A fixed shielding member made of a radiation shielding material is constituted in perpendicular to an opening formed on radiation shielding walls. The fixed shielding member has one side opened and has other side, the upper portion and the lower portion disposed in close contact with the radiation shielding walls. Movable shielding members made of a radiation shielding material are each disposed openably on both side of the fixed shielding member. The movable shielding member has a shaft as a fulcrum on one side thereof for connecting it to the radiation shielding walls. The other side has a handle attached for opening/closing the movable shielding member. Upon access of an operator, when each one of the movable shielding members is opened/closed on every time, leakage of linear or scattered radiation can be prevented. Even when both of the movable shielding members are opened simultaneously, the fixed shielding member and the movable shielding members form labyrinth to prevent leakage of linear radioactivity. (I.N.)

  4. A comparison between rare earth and transition metals working as magnetic materials in an AMR refrigerator in the room temperature range

    International Nuclear Information System (INIS)

    Aprea, C.; Greco, A.; Maiorino, A.; Masselli, C.

    2015-01-01

    This paper describes a two-dimensional (2D) multiphysics model of a packed bed regenerator made of magnetocaloric material. The regenerator operates as a refrigerant for a magnetic refrigerator operating at room temperature on the strength of an active magnetic regenerator (AMR) cycle. The model is able to simulate the thermofluidodynamic behavior of the magnetocaloric material and the magnetocaloric effect of the refrigerant. The model has been validated by means of experimental results. Different magnetic materials have been tested with the model as refrigerants: pure gadolinium, second order phase magnetic transition Pr_0_._4_5Sr_0_._3_5MnO_3 and first order phase magnetic transition alloys Gd_5(Si_xGe_1_−_x)_4, LaFe_1_1_._3_8_4Mn_0_._3_5_6Si_1_._2_6H_1_._5_2, LaFe_1_1_._0_5Co_0_._9_4Si_1_._1_0 and MnFeP_0_._4_5As_0_._5_5. The tests were performed with fixed fluid flow rate (5 l/min), AMR cycle frequency (1.25 Hz) and cold heat exchanger temperature (288 K) while the hot heat exchanger temperature was varied in the range 295–302 K. The results, generated for a magnetic induction which varies from 0 to 1.5 T, are presented in terms of temperature span, refrigeration power and coefficient of performance. From a global point of view (performances and cost), the most promising materials are LaFeSi compounds which are really cheaper than rare earth compounds and they give a performance sufficiently higher than gadolinium. - Graphical abstract: • Active Magnetic Refrigeration (AMR) cycle; • First Order Transition magnetic materials (FOMT); • Second Order Transition magnetic materials (SOMT). - Highlights: • Comparison between different magnetic materials. • 2D model of an Active Magnetic Regenerative refrigeration cycle. • Validation of the model with experimental data. • Gd_5(Si_xGe_1_−_x)_4 is the most performant magnetic material. • The most promising are LaFeSi compounds which are cheaper and they give high performances.

  5. Valley Zeeman splitting of monolayer MoS2 probed by low-field magnetic circular dichroism spectroscopy at room temperature

    Science.gov (United States)

    Wu, Y. J.; Shen, C.; Tan, Q. H.; Shi, J.; Liu, X. F.; Wu, Z. H.; Zhang, J.; Tan, P. H.; Zheng, H. Z.

    2018-04-01

    The valley Zeeman splitting of monolayer two-dimensional (2D) materials in the magnetic field plays an important role in the valley and spin manipulations. In general, a high magnetic field (6-65 T) and low temperature (2-30 K) were two key measurement conditions to observe the resolvable valley Zeeman splitting of monolayer 2D materials in current reported experiments. In this study, we experimentally demonstrate an effective measurement scheme by employing magnetic circular dichroism (MCD) spectroscopy, which enables us to distinguish the valley Zeeman splitting under a relatively low magnetic field of 1 T at room temperature. MCD peaks related to both A and B excitonic transitions in monolayer MoS2 can be clearly observed. Based on the MCD spectra under different magnetic fields (-3 to 3 T), we obtained the valley Zeeman splitting energy and the g-factors of A and B excitons, respectively. Our results show that MCD spectroscopy is a high-sensitive magneto-optical technique to explore the valley and spin manipulation in 2D materials.

  6. Gonad Shielding for Patients Undergoing Conventional Radiological Examinations: Is There Cause for Concern?

    Directory of Open Access Journals (Sweden)

    Karami

    2016-04-01

    Full Text Available Background Gonad shielding is one of the fundamental methods by which to protect reproductive organs in patients undergoing conventional radiological examinations. A lack of or inadequate shielding of the gonads may increase the exposure of these organs and result in malignancies future generations. Objectives The aim of this study is to investigate the prevalence of gonad shielding in patients undergoing conventional radiological examinations and the availability of gonad shields and gonad shielding protocols in radiology departments. Materials and Methods A retrospective, observational cross-sectional study on the application of gonad shielding, the availability of gonad shields and the existence of gonad shielding protocols in radiology departments was performed in five different hospitals in Ahvaz, Iran. Results The highest application of gonad shielding was 6.6% for the pediatric hospital. The prevalence of gonad shielding was less than 0.2%. In 64.3% of the radiography rooms, at least one flat-contact gonad shield of a large size was available. Only large-sized gonad shields were available. Curved-contact and shadow gonad shields did not exist. Gonad shielding protocols were not existence in any of the fourteen radiography rooms investigated. Conclusions Comprehensive protection programs with on-the-job training courses for staff members are strongly recommended, as well as, the provision of radiological shields and gonad shielding protocols in radiology departments to reduce the patient’s radiation dose during radiological examinations.

  7. Compact electron storage ring JESCOS with normalconducting or superconducting magnets for X-ray lithography

    International Nuclear Information System (INIS)

    Anton, F.; Klein, U.; Krischel, D.; Anderberg, B.

    1992-01-01

    The layouts of a normal conducting electron storage ring and a storage ring with superconducting bending magnets are presented. The storage rings have a critical wavelength of 1 nm and are designed as compact sources for X-ray lithography. Each ring fits into a shielded room with a diameter of 14 m. (author) 3 refs.; 5 figs.; 1 tab

  8. Giant room-temperature magnetoresistance in La{sub 0.8}Tb{sub 0.2}MnO{sub 3} under the low magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yingtang [Physics of Department, Beijing University of Aeronautics and Astronautics, Beijing 100083 (China); Institute of Physics and Center for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100080 (China); School of Material Science and Engineering, Shaanxi University of Technology, Hanzhong 723003 (China)], E-mail: zhangyingtang76@sina.com; Chen Ziyu [Physics of Department, Beijing University of Aeronautics and Astronautics, Beijing 100083 (China)], E-mail: chenzy@buaa.edu.cn; Wang Chunchang; Jie Qiu; Lue Huibin [Institute of Physics and Center for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100080 (China)

    2009-05-15

    Polycrystalline perovskite La{sub 0.8}Tb{sub 0.2}MnO{sub 3} (LTMO) with an orthorhombic phase was synthesized by conventional solid-state reaction. The magnetic and electric properties of La{sub 0.8}Tb{sub 0.2}MnO{sub 3} were examined. The striking finding is that the material exhibits giant magnetoresistance at room temperature as high as -31.8% and -35.7% under the low magnetic fields of 100 and 1000 Oe, respectively. This result suggests that La{sub 0.8}Tb{sub 0.2}MnO{sub 3} has a promising potential in future device developments.

  9. Shielding Efficiency of a Fabric Based on Amorphous Glass-Covered Magnetic Microwires to Radiation Emitted by a Mobile Phone in 2G and 3G Communication Technologies

    Directory of Open Access Journals (Sweden)

    Miclăuş Simona

    2017-12-01

    Full Text Available A dual band mobile phone model was used to check the shielding properties of an amorphous ferromagnetic textile against the radiation emitted by the handset. Two frequencies belonging to the 2nd and 3rd generation of mobile emission technologies were used, 897 MHz and 1950 MHz. The specific absorption rate (SAR of energy deposition in a human head phantom was measured in standardized conditions. The textile contained micrometric-diameter wires of a ferromagnetic mixture embedded in a thin glass coat and weaved in a specific way. A set of fabric orientations and configurations (layering were provided in the experiment in order to achieve a better shielding to the phone’s radiation. Compared with the non-shielded handset, SAR deposited in the head while using the fabric-covered phone could be decreased up to 30 % of its initial value – in case of 2G technology and up to 24 % – in case of 3G technology. This type of material shows one of the highest shielding efficiencies of the electric-field component in near-field exposure conditions reported until now. A cubic curve of SAR decrease in depth of the head was revealed in both uncovered and covered handset, the effect of shielding being larger at the higher frequency.

  10. Facile Fabrication of Highly Active Magnetic Aminoclay Supported Palladium Nanoparticles for the Room Temperature Catalytic Reduction of Nitrophenol and Nitroanilines

    Directory of Open Access Journals (Sweden)

    Lei Jia

    2018-06-01

    Full Text Available Magnetically recyclable nanocatalysts with excellent performance are urgent need in heterogeneous catalysis, due to their magnetic nature, which allows for convenient and efficient separation with the help of an external magnetic field. In this research, we developed a simple and rapid method to fabricate a magnetic aminoclay (AC based an AC@Fe3O4@Pd nanocatalyst by depositing palladium nanoparticles (Pd NPs on the surface of the magnetic aminoclay nanocomposite. The microstructure and the magnetic properties of as-prepared AC@Fe3O4@Pd were tested using transmission electron microscopy (TEM, energy-dispersive X-ray spectroscopy (EDS, X-ray diffraction (XRD, and vibrating sample magnetometry (VSM analyses. The resultant AC@Fe3O4@Pd nanocatalyst with the magnetic Fe-based inner shell, catalytically activate the outer noble metal shell, which when combined with ultrafine Pd NPs, synergistically enhanced the catalytic activity and recyclability in organocatalysis. As the aminoclay displayed good water dispersibility, the nanocatalyst indicated satisfactory catalytic performance in the reaction of reducing nitrophenol and nitroanilines to the corresponding aminobenzene derivatives. Meanwhile, the AC@Fe3O4@Pd nanocatalyst exhibited excellent reusability, while still maintaining good activity after several catalytic cycles.

  11. Quest for high-Curie temperature MnxGe1-x diluted magnetic semiconductors for room-temperature spintronics applications

    Science.gov (United States)

    Nie, Tianxiao; Tang, Jianshi; Wang, Kang L.

    2015-09-01

    In this paper, we report the non-equilibrium growth of various Mn-doped Ge dilute magnetic semiconductor nanostructures using molecular-beam epitaxy, including quantum dots, nanodisks and nanowires. Their detailed structural and magnetic properties are characterized. By comparing the results with those in MnxGe1-x thin films, it is affirmed that the use of nanostructures helps eliminate crystalline defects and meanwhile enhance the carrier-mediate ferromagnetism from substantial quantum confinements. Our systematic studies provide a promising platform to build nonvolatile spinFET and other novel spintronic devices based upon dilute magnetic semiconductor nanostructures.

  12. RadShield: semiautomated shielding design using a floor plan driven graphical user interface.

    Science.gov (United States)

    DeLorenzo, Matthew C; Wu, Dee H; Yang, Kai; Rutel, Isaac B

    2016-09-08

    The purpose of this study was to introduce and describe the development of RadShield, a Java-based graphical user interface (GUI), which provides a base design that uniquely performs thorough, spatially distributed calculations at many points and reports the maximum air-kerma rate and barrier thickness for each barrier pursuant to NCRP Report 147 methodology. Semiautomated shielding design calculations are validated by two approaches: a geometry-based approach and a manual approach. A series of geometry-based equations were derived giv-ing the maximum air-kerma rate magnitude and location through a first derivative root finding approach. The second approach consisted of comparing RadShield results with those found by manual shielding design by an American Board of Radiology (ABR)-certified medical physicist for two clinical room situations: two adjacent catheterization labs, and a radiographic and fluoroscopic (R&F) exam room. RadShield's efficacy in finding the maximum air-kerma rate was compared against the geometry-based approach and the overall shielding recommendations by RadShield were compared against the medical physicist's shielding results. Percentage errors between the geometry-based approach and RadShield's approach in finding the magnitude and location of the maximum air-kerma rate was within 0.00124% and 14 mm. RadShield's barrier thickness calculations were found to be within 0.156 mm lead (Pb) and 0.150 mm lead (Pb) for the adjacent catheteriza-tion labs and R&F room examples, respectively. However, within the R&F room example, differences in locating the most sensitive calculation point on the floor plan for one of the barriers was not considered in the medical physicist's calculation and was revealed by the RadShield calculations. RadShield is shown to accurately find the maximum values of air-kerma rate and barrier thickness using NCRP Report 147 methodology. Visual inspection alone of the 2D X-ray exam distribution by a medical physicist may not

  13. Magneto-optical controlled transmittance alteration of PbS quantum dots by moderately applied magnetic fields at room temperature

    International Nuclear Information System (INIS)

    Singh, Akhilesh K.; Barik, Puspendu; Ullrich, Bruno

    2014-01-01

    We observed changes of the transmitted monochromatic light passing through a colloidal PbS quantum dot film on glass owing to an applied moderate (smaller than 1 T) magnetic field under ambient conditions. The observed alterations show a square dependence on the magnetic field increase that cannot be achieved with bulk semiconductors. The findings point to so far not recognized application potentials of quantum dots

  14. MAGNET

    CERN Multimedia

    B. Curé

    2012-01-01

      Following the unexpected magnet stops last August due to sequences of unfortunate events on the services and cryogenics [see CMS internal report], a few more events and initiatives again disrupted the magnet operation. All the magnet parameters stayed at their nominal values during this period without any fault or alarm on the magnet control and safety systems. The magnet was stopped for the September technical stop to allow interventions in the experimental cavern on the detector services. On 1 October, to prepare the transfer of the liquid nitrogen tank on its new location, several control cables had to be removed. One cable was cut mistakenly, causing a digital input card to switch off, resulting in a cold-box (CB) stop. This tank is used for the pre-cooling of the magnet from room temperature down to 80 K, and for this reason it is controlled through the cryogenics control system. Since the connection of the CB was only allowed for a field below 2 T to avoid the risk of triggering a fast d...

  15. Heating profiles on ICRF antenna Faraday shields

    International Nuclear Information System (INIS)

    Taylor, D.J.; Baity, F.W.; Hahs, C.L. Riemer, B.W.; Ryan, D.M.; Williamson, D.E.

    1992-01-01

    Poor definition of the heating profiles that occur during normal operation of Faraday shields for ion cyclotron resonant frequency (ICRF) antennas has complicated the mechanical design of ICRF system components. This paper reports that at Oak Ridge National Laboratory (ORNL), Faraday shield analysis is being used in defining rf heating profiles. In recent numerical analyses of proposed hardware for the Burning Plasma Experiment (BPX) and DIII-D, rf magnetic fields at Faraday shield surfaces were calculated, providing realistic predictions of the induced skin currents flowing on the shield elements and the resulting dissipated power profile. Detailed measurements on mock-ups of the Faraday shields for DIII-D and the Tokamak Fusion Test Reactor (TFTR) confirmed the predicted magnetic field distributions. A conceptual design for an uncooled Faraday shield for the BPX ion cyclotron resonance heating (ICRH) antenna, which should withstand the proposed long-pulse operation, has been completed. The analytical effort is described in detail, with emphasis on the design work for the BPX ICRH antenna conceptual design and for the replacement Faraday shield for the DIII-D FWCD antenna. Results of analyses are shown, and configuration issues involved in component modeling are discussed

  16. Hypoxia Room

    Data.gov (United States)

    Federal Laboratory Consortium — The Hypoxia Room is a 8x8x8 ft. clear vinyl plastic and aluminum frame construction enclosure located within USAREIM laboratory 028. The Hypoxia Room (manufactured...

  17. Analysis and reduction of thermal magnetic noise in liquid-He dewar for sensitive low-field nuclear magnetic resonance measurements

    International Nuclear Information System (INIS)

    Hwang, S. M.; Yu, K. K.; Lee, Y. H.; Kang, C. S.; Kim, K.; Lee, S. J.

    2013-01-01

    For sensitive measurements of micro-Tesla nuclear magnetic resonance (μT-NMR) signal, a low-noise superconducting quantum interference device (SQUID) system is needed. We have fabricated a liquid He dewar for an SQUID having a large diameter for the pickup coil. The initial test of the SQUID system showed much higher low-frequency magnetic noise caused by the thermal magnetic noise of the aluminum plates used for the vapor-cooled thermal shield material. The frequency dependence of the noise spectrum showed that the noise increases with the decrease of frequency. This behavior could be explained from a two-layer model; one generating the thermal noise and the other one shielding the thermal noise by eddy-current shielding. And the eddy-current shielding effect is strongly dependent on the frequency through the skin-depth. To minimize the loop size for the fluctuating thermal noise current, we changed the thermal shield material into insulated thin Cu mesh. The magnetic noise of the SQUID system became flat down to 0.1 Hz with a white noise of 0.3 fT√ Hz, including the other noise contributions such as SQUID electronics and magnetically shielded room, etc, which is acceptable for low-noise μT-NMR experiments.

  18. Handout on shielding calculation

    International Nuclear Information System (INIS)

    Heilbron Filho, P.F.L.

    1991-01-01

    In order to avoid the difficulties of the radioprotection supervisors in the tasks related to shielding calculations, is presented in this paper the basic concepts of shielding theory. It also includes exercises and examples. (author)

  19. Design of emergency shield

    International Nuclear Information System (INIS)

    Soliman, S.E.

    1993-01-01

    Manufacturing of an emergency movable shield in the hot laboratories center is urgently needed for the safety of personnel in case of accidents or spilling of radioactive materials. In this report, a full design for an emergency shield is presented and the corresponding dose rates behind the shield for different activities (from 1 mCi to 5 Ci) was calculated by using micro shield computer code. 4 figs., 1 tab

  20. Magnetic, thermal and luminescence properties in room-temperature nanosecond electron-irradiated various metal oxide nanopowders

    Science.gov (United States)

    Sokovnin, S. Yu; Balezin, M. E.; Il’ves, V. G.

    2018-03-01

    By means of pulsed electron beam evaporation in vacuum of targets non-magnetic, in bulk state, Al2O3 and YSZ (ZrO2-8% Y2O3) oxides, magnetic nanopowders (NPs) with a high specific surface were produced. The NPs were subsequently irradiated in air by electrons with energy of 700 keV, using a URT-1 accelerator for 15 and 30 minutes. The magnetic, thermal, and pulsed cathodoluminescence (PCL) characteristics of NPs were measured before and after irradiation. It was established that the electron irradiation non-monotonically changes the magnetization of the pristine samples. To the contrary, a clear correlation between the intensity of PCL and the irradiation doses is found in the oxides. There was a decrease in the intensity of PCL after irradiation. Luminescent and thermal properties reflect the transformation of structural defects in NPs more strongly after the exposure to a pulsed electron beam in comparison with corresponding changes of the NPs magnetic response.

  1. Design and testing of a magnetic shield for the Thomson scattering photomultiplier tubes in the stray fields of the ERASMUS tokamak

    International Nuclear Information System (INIS)

    Desoppere, E.; Van Oost, G.

    1983-01-01

    A multiple coaxial shield system has been designed for the photomultiplier tubes of the ERASMUS tokamak Thomson scattering diagnostic. A stray field of 75 x 10 -4 T was reduced to 0.01 x 10 -4 T for a field parallel to the tube axis, and to 0.03 x 10 -4 T for a perpendicular field

  2. Electromagnetically shielded building

    International Nuclear Information System (INIS)

    Takahashi, T.; Nakamura, M.; Yabana, Y.; Ishikawa, T.; Nagata, K.

    1992-01-01

    This invention relates to a building having an electromagnetic shield structure well-suited for application to an information network system utilizing electromagnetic waves, and more particularly to an electromagnetically shielded building for enhancing the electromagnetic shielding performance of an external wall. 6 figs

  3. Electromagnetically shielded building

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, T; Nakamura, M; Yabana, Y; Ishikawa, T; Nagata, K

    1992-04-21

    This invention relates to a building having an electromagnetic shield structure well-suited for application to an information network system utilizing electromagnetic waves, and more particularly to an electromagnetically shielded building for enhancing the electromagnetic shielding performance of an external wall. 6 figs.

  4. Determination of the exposure speed of radiation emitted by the linear accelerator, using the code MCNP5 to evaluate the radiotherapy room shields of ABC Hospital; Determinacion de la rapidez de exposicion de la radiacion emitida por el acelerador lineal, utilizando el codigo MCNP5, para evaluar los blindajes de la sala de radioterapia del Hospital ABC

    Energy Technology Data Exchange (ETDEWEB)

    Corral B, J. R.

    2015-07-01

    Humans should avoid exposure to radiation, because the consequences are harmful to health. Although there are different emission sources of radiation, generated by medical devices they are usually of great interest, since people who attend hospitals are exposed in one way or another to ionizing radiation. Therefore, is important to conduct studies on radioactive levels that are generated in hospitals, as a result of the use of medical equipment. To determine levels of exposure speed of a radioactive facility there are different methods, including the radiation detector and computational method. This thesis uses the computational method. With the program MCNP5 was determined the speed of the radiation exposure in the radiotherapy room of Cancer Center of ABC Hospital in Mexico City. In the application of computational method, first the thicknesses of the shields were calculated, using variables as: 1) distance from the shield to the source; 2) desired weekly equivalent dose; 3) weekly total dose equivalent emitted by the equipment; 4) occupation and use factors. Once obtained thicknesses, we proceeded to model the bunker using the mentioned program. The program uses the Monte Carlo code to probabilistic ally determine the phenomena of interaction of radiation with the shield, which will be held during the X-ray emission from the linear accelerator. The results of computational analysis were compared with those obtained experimentally with the detection method, for which was required the use of a Geiger-Muller counter and the linear accelerator was programmed with an energy of 19 MV with 500 units monitor positioning the detector in the corresponding boundary. (Author)

  5. Technology for SQUID systems for the application in magnetically disturbed environment. Final report

    International Nuclear Information System (INIS)

    Schultze, V.; Fritzsch, L.; Thrum, F.; Stolz, R.; Chwala, A.

    1996-06-01

    International available SQUID systems, as used for example in biomagnetic research, obtain high sensitivities for magnetic fields or magnetic fieldgradients. However, these systems were optimised for operation in magnetically shielded rooms. Goal of this project was to develop SQUIDs suppressing the external noise and therefore are able to operate without external shielding in normal environments. As a consequence, the required Nb/AlO x /Nb technology has also been developed. The resulting planar SQUID gradiometers as produced at the IPHT, reached a suppression of homogeneous fields up to 5 x 10 4 for a magnetic field sensitivity c , project. SQUID gradiometers, produced using YBCO technology, were successfully operated in non shielded eddy current NDE measurements in the lab. (orig.) [de

  6. Room temperature ferromagnetism in magic-sized Cr-doped CdS diluted magnetic semiconducting quantum dots

    International Nuclear Information System (INIS)

    Srivastava, Punita; Kumar, Pushpendra; Singh, Kedar

    2011-01-01

    Manipulation of carrier spins in semiconductors for spintronics applications has received great attention driven by improved functionalities and higher speed operation. Doping of semiconductor nanocrystals by transition-metal ions pronounced as diluted magnetic semiconductors (DMS) has attracted tremendous attention. Such doping is, however, difficult to achieve in low-dimensional strongly quantum-confined nanostructures by conventional growth procedures. In the present case, magic-sized, pure, and Cr-doped CdS DM-QDs have been synthesized by solution phase chemistry (lyothermal method). Structural, optical, and magnetic investigation suggest an intrinsic nature of ferromagnetism with highly quantum-confined system. Optical and magnetic results of pure and doped QDs reveal major physical consequences of dopant localization within the capacity to engineer dopant-carrier exchange interactions introducing magnetic functionalities within the host semiconductor lattice. Unpaired Cr ions in Cd substitutional sites could create spin ordering and ferromagnetic coupling. The results presented herein illustrate some of the remarkable and unexpected complexities that can arise in doped QDs.

  7. Perpendicular magnetic tunnel junction with tunneling magnetoresistance ratio of 64% using MgO (100) barrier layer prepared at room temperature

    International Nuclear Information System (INIS)

    Ohmori, Hideto; Hatori, Tomoya; Nakagawa, Shigeki

    2008-01-01

    MgO (100) textured films can be prepared by reactive facing targets sputtering at room temperature without postdeposition annealing process when they were deposited on (100) oriented Fe buffer layers. This method allows fabrication of perpendicular magnetic tunnel junction (p-MTJ) with MgO (100) tunneling barrier layer and rare-earth transition metal (RE-TM) alloy thin films as perpendicularly magnetized free and pinned layers. The 3-nm-thick MgO tunneling barrier layer in p-MTJ multilayer prepared on glass substrate revealed (100) crystalline orientation. Extraordinary Hall effect measurement clarified that the perpendicular magnetic components of 3-nm-thick Fe buffer layers on the two ends of MgO tunneling barrier layer were increased by exchange coupling with RE-TM alloy layers. The RA of 35 kΩ μm 2 and tunneling magnetoresistance ratio of 64% was observed in the multilayered p-MTJ element by current-in-plane-tunneling

  8. Electromagnetic shielding formulae

    International Nuclear Information System (INIS)

    Dahlberg, E.

    1979-02-01

    This addendum to an earlier collection of electromagnetic shielding formulae (TRITA-EPP-75-27) contains simple transfer matrices suitable for calculating the quasistatic shielding efficiency for multiple transverse-field and axial-field cylindrical and spherical shields, as well as for estimating leakage fields from long coaxial cables and the normal-incidence transmission of a plane wave through a multiple plane shield. The differences and similarities between these cases are illustrated by means of equivalent circuits and transmission line analogies. The addendum also includes a discussion of a possible heuristic improvement of some shielding formulae. (author)

  9. Shielding benchmark problems, (2)

    International Nuclear Information System (INIS)

    Tanaka, Shun-ichi; Sasamoto, Nobuo; Oka, Yoshiaki; Shin, Kazuo; Tada, Keiko.

    1980-02-01

    Shielding benchmark problems prepared by Working Group of Assessment of Shielding Experiments in the Research Committee on Shielding Design in the Atomic Energy Society of Japan were compiled by Shielding Laboratory in Japan Atomic Energy Research Institute. Fourteen shielding benchmark problems are presented newly in addition to twenty-one problems proposed already, for evaluating the calculational algorithm and accuracy of computer codes based on discrete ordinates method and Monte Carlo method and for evaluating the nuclear data used in codes. The present benchmark problems are principally for investigating the backscattering and the streaming of neutrons and gamma rays in two- and three-dimensional configurations. (author)

  10. Performance and analysis of wireless power charging system from room temperature to HTS magnet via strong resonance coupling method

    International Nuclear Information System (INIS)

    Chung, Y. D.; Lee, S. Y.; Lee, T. W.; Kim, J. S.; Lee, C. Y.

    2016-01-01

    The technology of supplying the electric power by wireless power transfer (WPT) is expected for the next generation power feeding system since it can supply the power to portable devices without any connectors through large air gap. As such a technology based on strongly coupled electromagnetic resonators is possible to deliver the large power and recharge them seamlessly; it has been considered as a noble option to wireless power charging system in the various power applications. Recently, various HTS wires have now been manufactured for demonstrations of transmission cables, motors, MAGLEV, and other electrical power components. However, since the HTS magnets have a lower index n value intrinsically, they are required to be charged from external power system through leads or internal power system. The portable area is limited as well as the cryogen system is bulkier. Thus, we proposed a novel design of wireless power charging system for superconducting HTS magnet (WPC4SM) based on resonance coupling method. As the novel system makes possible a wireless power charging using copper resonance coupled coils, it enables to portable charging conveniently in the superconducting applications. This paper presented the conceptual design and operating characteristics of WPC4SM using different shapes' copper resonance coil. The proposed system consists of four components; RF generator of 370 kHz, copper resonance coupling coils, impedance matching (IM) subsystem and HTS magnet including rectifier system

  11. Performance and analysis of wireless power charging system from room temperature to HTS magnet via strong resonance coupling method

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Y. D.; Lee, S. Y.; Lee, T. W.; Kim, J. S. [Suwon Science College, Suwon (Korea, Republic of); Lee, C. Y. [Korea Railroad Institute, Uiwang (Korea, Republic of)

    2016-03-15

    The technology of supplying the electric power by wireless power transfer (WPT) is expected for the next generation power feeding system since it can supply the power to portable devices without any connectors through large air gap. As such a technology based on strongly coupled electromagnetic resonators is possible to deliver the large power and recharge them seamlessly; it has been considered as a noble option to wireless power charging system in the various power applications. Recently, various HTS wires have now been manufactured for demonstrations of transmission cables, motors, MAGLEV, and other electrical power components. However, since the HTS magnets have a lower index n value intrinsically, they are required to be charged from external power system through leads or internal power system. The portable area is limited as well as the cryogen system is bulkier. Thus, we proposed a novel design of wireless power charging system for superconducting HTS magnet (WPC4SM) based on resonance coupling method. As the novel system makes possible a wireless power charging using copper resonance coupled coils, it enables to portable charging conveniently in the superconducting applications. This paper presented the conceptual design and operating characteristics of WPC4SM using different shapes' copper resonance coil. The proposed system consists of four components; RF generator of 370 kHz, copper resonance coupling coils, impedance matching (IM) subsystem and HTS magnet including rectifier system.

  12. Room Acoustics

    Science.gov (United States)

    Kuttruff, Heinrich; Mommertz, Eckard

    The traditional task of room acoustics is to create or formulate conditions which ensure the best possible propagation of sound in a room from a sound source to a listener. Thus, objects of room acoustics are in particular assembly halls of all kinds, such as auditoria and lecture halls, conference rooms, theaters, concert halls or churches. Already at this point, it has to be pointed out that these conditions essentially depend on the question if speech or music should be transmitted; in the first case, the criterion for transmission quality is good speech intelligibility, in the other case, however, the success of room-acoustical efforts depends on other factors that cannot be quantified that easily, not least it also depends on the hearing habits of the listeners. In any case, absolutely "good acoustics" of a room do not exist.

  13. Perpendicular magnetic anisotropy of non-epitaxial hexagonal Co{sub 50}Pt{sub 50} thin films prepared at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, F.T., E-mail: ftyuan@gmail.com [iSentek Ltd., Advanced Sensor Laboratory, New Taipei City 22101, Taiwan (China); Chang, H.W., E-mail: wei0208@gmail.com [Department of Applied Physics, Tunghai University, Taichung 40704, Taiwan (China); Lee, P.Y.; Chang, C.Y. [Department of Applied Physics, Tunghai University, Taichung 40704, Taiwan (China); Chi, C.C. [Department of Materials Sciences and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Ouyang, H., E-mail: houyang@mx.nthu.edu.tw [Department of Materials Sciences and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan (China)

    2015-04-15

    Highlights: • In this paper, we propose a non-epitaxially grown PMA thin film of disorder hexagonal Co{sub 50}Pt{sub 50} which can satisfy all the requirements at once. • Although the preparation temperature is at room temperature and no post annealing is required, the film also shows good thermal stability up to 400 °C. • Moreover, the easy-controlling single layer deposition process of the film largely enhances the feasibility of practical production. • Significant PMA is achieved in a wide range of film thickness from 2 nm to 20 nm, which expands the usage form a GMR or TMR magnetic junctions to perpendicular spin polarizer for spin current related engineering. • The presented results may open new opportunities for advanced spintronic devices. - Abstract: Non-epitaxially induced perpendicular magnetic anisotropy (PMA) of Co{sub 50}Pt{sub 50} thin films at room temperature (RT) is reported. The CoPt film having a disordered hcp structure shows a magnetocrystalline anisotropy (K{sub u}{sup RT}) of 1–2 × 10{sup 6} erg/cm{sup 3} in a wide range of layer thickness from 2 to 20 nm. K{sub u}{sup RT} of about 1 × 10{sup 6} erg/cm{sup 3} can be preserved after a 400 °C-thermal cycle in the 5-nm-thick sample. Moderate PMA, large thickness range, simple preparation process, low formation temperature but good thermal stability make presented hcp CoPt become a remarkable option for advanced spintronic devices.

  14. Development and application of high performance liquid shielding materials

    International Nuclear Information System (INIS)

    Miura, Toshimasa; Omata, Sadao; Otano, Naoteru; Hirao, Yoshihiro; Kanai, Yasuji

    1998-01-01

    Development of liquid shielding material with good performance for neutron and γ-ray was investigated. Lead, hydrogen and boron were selected as the elements of shielding materials which were made by the ultraviolet curing method. Good performance shielding materials with about 1 mm width to neutron and gamma ray were produced by mixing lead, boron compound and ultraviolet curing monomer with many hydrogens. The shielding performance was the same as a concrete with two times width. The activation was very small such as 1/10 6 -1/10 8 of the standard concrete. The weight and the external appearance did not charged from room temperature to 100degC. Polyfunctional monomer had good thermal resistance. This shielding material was applied to double bending cylindrical duct and annulus ring duct. The results proved the shielding materials developed had good performance. (S.Y.)

  15. Wake Shield Target Protection

    International Nuclear Information System (INIS)

    Valmianski, Emanuil I.; Petzoldt, Ronald W.; Alexander, Neil B.

    2003-01-01

    The heat flux from both gas convection and chamber radiation on a direct drive target must be limited to avoid target damage from excessive D-T temperature increase. One of the possibilities of protecting the target is a wake shield flying in front of the target. A shield will also reduce drag force on the target, thereby facilitating target tracking and position prediction. A Direct Simulation Monte Carlo (DSMC) code was used to calculate convection heat loads as boundary conditions input into ANSYS thermal calculations. These were used for studying the quality of target protection depending on various shapes of shields, target-shield distance, and protective properties of the shield moving relative to the target. The results show that the shield can reduce the convective heat flux by a factor of 2 to 5 depending on pressure, temperature, and velocity. The protective effect of a shield moving relative to the target is greater than the protective properties of a fixed shield. However, the protective effect of a shield moving under the drag force is not sufficient for bringing the heat load on the target down to the necessary limit. Some other ways of diminishing heat flux using a protective shield are discussed

  16. MAGNET

    CERN Multimedia

    B. Curé

    2011-01-01

    The magnet ran smoothly in the last few months until a fast dump occurred on 9th May 2011. Fortunately, this occurred in the afternoon of the first day of the technical stop. The fast dump was due to a valve position controller that caused the sudden closure of a valve. This valve is used to regulate the helium flow on one of the two current leads, which electrically connects the coil at 4.5 K to the busbars at room temperature. With no helium flow on the lead, the voltage drop and the temperatures across the leads increase up to the defined thresholds, triggering a fast dump through the Magnet Safety System (MSS). The automatic reaction triggered by the MSS worked properly. The helium release was limited as the pressure rise was just at the limit of the safety valve opening pressure. The average temperature of the magnet reached 72 K. It took four days to recover the temperature and refill the helium volumes. The faulty valve controller was replaced by a spare one before the magnet ramp-up resumed....

  17. Radiation shielding concrete

    International Nuclear Information System (INIS)

    Kunishima, Shigeru.

    1990-01-01

    The radiation shielding concretes comprise water, cement, fine aggregates consisting of serpentines and blown mist slags, coarse aggregates consisting of serpentines and kneading materials. Since serpentines containing a relatively great amount of water of crystallization in rocks as coarse aggregates and fine aggregates, the hydrogen content in the radiation shielding concretes is increased and the neutron shielding effect is improved. In addition, since serpentines are added as the fine aggregates and blown mists slags of a great specific gravity are used, the specific gravity of the shielding concretes is increased to improve the γ-ray shielding effect. Further, by the use of the kneading material having a water reducing effect and fluidizing effect, and by the bearing effect of the spherical blown mist slags used as the fine aggregates, concrete fluidity can be increased. Accordingly, workability of the radiation shielding concretes can be improved. (T.M.)

  18. Room temperature magnetism of few-nanometers-thick Fe{sub 3}O{sub 4}(111) films on Pt(111) and Ru(0001) studied in ambient conditions

    Energy Technology Data Exchange (ETDEWEB)

    Lewandowski, M., E-mail: lewandowski@amu.edu.pl [NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań (Poland); Miłosz, Z.; Michalak, N.; Ranecki, R. [Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań (Poland); Sveklo, I.; Kurant, Z.; Maziewski, A. [Faculty of Physics, University of Białystok, Lipowa 41, 15-424 Białystok (Poland); Mielcarek, S. [Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Luciński, T. [Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań (Poland); Jurga, S. [NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland)

    2015-09-30

    Few-nanometers-thick Fe{sub 3}O{sub 4}(111) films were epitaxially grown on Pt(111) and Ru(0001) single crystal supports by sequential iron deposition and oxidation in an ultra-high vacuum chamber. The growth of well-ordered magnetite films was confirmed by low energy electron diffraction. The films were covered with a protective Au layer and subjected to magnetic and structural studies in ambient conditions. Magnetic hysteresis loops, recorded using magneto-optical Kerr effect apparatus, confirmed magnetic ordering in both films at room temperature. The Kerr measurements indicated in-plane orientation of magnetization, which was supported by the lack of magnetic contrast in magnetic force microscopy images. Atomic force microscopy revealed significant differences in morphology of the films, tentatively attributed to different lattice mismatch with Pt(111) and Ru(0001) single crystal supports. - Highlights: • Few-nanometers-thick Fe{sub 3}O{sub 4}(111) films were grown on Pt(111) and Ru(0001). • Magnetic properties were studied using MOKE and AFM/MFM in ambient conditions. • The films exhibited in-plane magnetic ordering at room temperature. • Differences in magnetic properties were tentatively assigned to structural differences.

  19. Characteristics simulation of wireless power transfer system considering shielding distance

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yu Kyeong; Choi, Hyo Sang; Jung, Byung Ik; Jeong, In Sung [Chosun University, Gwangju (Korea, Republic of)

    2015-03-15

    Wireless power transfer technology is using the magnetic resonance recently drawing increased attention. It uses the resonance between transmitter and receiver coils to transfer power. Thus, it can improve the transfer distance and efficiency compared with the existing magnetic induction technique. The authors found from the previous study that the application of the superconductor coil to the magnetic resonance wireless power transfer system improved its efficiency. Its application to real life, however, requires the additional study on the effects of adjacent materials. In this study, the two resonance coils made by superconductor coils were used to aluminum and plastic shielding materials was placed between the coils. S-parameters were analyzed according to the position of the shielding material between the transmitter and receiver coils. As a result, the plastic of shielding material had no effect, but the aluminum of shielding material affected the wireless power transfer due to the shielding effectiveness.

  20. Characteristics simulation of wireless power transfer system considering shielding distance

    International Nuclear Information System (INIS)

    Lee, Yu Kyeong; Choi, Hyo Sang; Jung, Byung Ik; Jeong, In Sung

    2015-01-01

    Wireless power transfer technology is using the magnetic resonance recently drawing increased attention. It uses the resonance between transmitter and receiver coils to transfer power. Thus, it can improve the transfer distance and efficiency compared with the existing magnetic induction technique. The authors found from the previous study that the application of the superconductor coil to the magnetic resonance wireless power transfer system improved its efficiency. Its application to real life, however, requires the additional study on the effects of adjacent materials. In this study, the two resonance coils made by superconductor coils were used to aluminum and plastic shielding materials was placed between the coils. S-parameters were analyzed according to the position of the shielding material between the transmitter and receiver coils. As a result, the plastic of shielding material had no effect, but the aluminum of shielding material affected the wireless power transfer due to the shielding effectiveness

  1. Accelerator shielding benchmark problems

    International Nuclear Information System (INIS)

    Hirayama, H.; Ban, S.; Nakamura, T.

    1993-01-01

    Accelerator shielding benchmark problems prepared by Working Group of Accelerator Shielding in the Research Committee on Radiation Behavior in the Atomic Energy Society of Japan were compiled by Radiation Safety Control Center of National Laboratory for High Energy Physics. Twenty-five accelerator shielding benchmark problems are presented for evaluating the calculational algorithm, the accuracy of computer codes and the nuclear data used in codes. (author)

  2. Ligand field effects in the nuclear magnetic shielding of nitrogen-15 and cobalt-59 in bent nitrosyl complexes of cobalt(III)

    International Nuclear Information System (INIS)

    Duffin, P.A.; Larkworthy, L.F.; Mason, J.; Stephens, A.N.; Thompson, R.M.

    1987-01-01

    A range of square-pyramidal complexes of cobalt(III) with a bent apical nitrosyl ligand has been prepared and examined by 15 N and 59 Co NMR spectroscopy, in a study of nephelauxetic and spectrochemical effects at the metal and nitrogen nuclei in the bent Co-NO chromophore. The basal ligands in this comparison include dithiocarbamate, quadridentate Schiff base or porphine, and bis-chelating diamine or oximate, so as to give S 4 , S 2 N 2 , N 4 , OONN, or ONON coordination in the plane and a range of substituents in the chelate and phenylene rings. The shielding of both cobalt and nitrogen tends to decrease with decrease in the M(d) → π*(NO) back-bonding, as indicated by the MN and NO bond distances, the MNO angle and the NO stretching frequency. The shieldings decrease from sulfur to nitrogen to oxygen coligators and also with electron withdrawal by ring substituents (and vice versa), i.e. with decrease in the ligand field splitting and in the nephelauxetism of the coligands. These parallelisms of the cobalt and nitrogen shielding accord with the orbital theory that was developed to explain the bending of the MNO ligand and influences of the metal and coligands. Significant interdependence of spectrochemical and nephelauxetic effects at cobalt and nitrogen arises from the degree of overlap and similarity in energies of the frontier orbitals for the paramagnetic circulation at nitrogen [n(N) → π* (NO)] and at cobalt (d-d). 43 references, 5 figures, 2 tables

  3. Electromagnetic behaviour of the shield in turbogenerators with superconducting solenoids

    International Nuclear Information System (INIS)

    Del Vecchio, P.; Veca, G.M.; Sacerdoti, G.

    1975-11-01

    The structure of turbogenerators with superconducting solenoids is analyzed and the investigation of electromagnetic behaviour of the rotating shield is presented. The cases considered are: (a) An hypothetical operation with a single phase with nominal current; (b) Steady-state operation in inverse sequence with 10% of the nominal current; (c) A step variation of the magnetic field intensity in the shield

  4. MAGNET

    CERN Multimedia

    B. Curé

    2013-01-01

    The magnet is fully stopped and at room temperature. The maintenance works and consolidation activities on the magnet sub-systems are progressing. To consolidate the cryogenic installation, two redundant helium compressors will be installed as ‘hot spares’, to avoid the risk of a magnet downtime in case of a major failure of a compressor unit during operation. The screw compressors, their motors, the mechanical couplings and the concrete blocks are already available and stored at P5. The metallic structure used to access the existing compressors in SH5 will be modified to allow the installation of the two redundant ones. The plan is to finish the installation and commissioning of the hot spare compressors before the summer 2014. In the meantime, a bypass on the high-pressure helium piping will be installed for the connection of a helium drier unit later during the Long Shutdown 1, keeping this installation out of the schedule critical path. A proposal is now being prepared for the con...

  5. INTOR radiation shielding for personnel access

    International Nuclear Information System (INIS)

    Gohar, Y.; Abdou, M.

    1981-01-01

    The INTOR reactor shield system consists of the blanket, bulk shield, penetration shield, component shield, and biological shield. The bulk shield consists of two parts: (a) the inboard shield; and (b) the outboard shield. The distinction between the different components of the shield system is essential to satisfy the different design constraints and achieve various objectives

  6. Recovery Room

    African Journals Online (AJOL)

    defined postoperative unit or on the hospital ward. Patients were frequently transferred from the operating room directly to the ward where they were placed close to the nursing station. In 1947 the. Anesthesia Study Commission of the Philadelphia.

  7. Shielded regenerative neutron detector

    International Nuclear Information System (INIS)

    Terhune, J.H.; Neissel, J.P.

    1978-01-01

    An ion chamber type neutron detector is disclosed which has a greatly extended lifespan. The detector includes a fission chamber containing a mixture of active and breeding material and a neutron shielding material. The breeding and shielding materials are selected to have similar or substantially matching neutron capture cross-sections so that their individual effects on increased detector life are mutually enhanced

  8. The TPC shielding of the CAST experiment

    International Nuclear Information System (INIS)

    Ruz, J; Luzon, G; Beltran, B; Carmona, J M; Cebrian, S; Gomez, H; Irastorza, I G; Morales, J; Ortiz de Solorzano, A; RodrIguez, A; Villar, J A

    2006-01-01

    Sunset solar axions traversing the intense magnetic field of the CERN Axion Solar Telescope (CAST) experiment may be detected in a TPC detector, placed at one side of the magnet, as point-like X-rays signals. This signal could be masked, however, by the inhomogeneous radioactive background of materials and experimental site. Here we present the shielding built to reduce and homogenize the radioactive background levels of the TPC detector

  9. SU-E-T-270: Optimized Shielding Calculations for Medical Linear Accelerators (LINACs).

    Science.gov (United States)

    Muhammad, W; Lee, S; Hussain, A

    2012-06-01

    The purpose of radiation shielding is to reduce the effective equivalent dose from a medical linear accelerator (LINAC) to a point outside the room to a level determined by individual state/international regulations. The study was performed to design LINAC's room for newly planned radiotherapy centers. Optimized shielding calculations were performed for LINACs having maximum photon energy of 20 MV based on NCRP 151. The maximum permissible dose limits were kept 0.04 mSv/week and 0.002 mSv/week for controlled and uncontrolled areas respectively by following ALARA principle. The planned LINAC's room was compared to the already constructed (non-optimized) LINAC's room to evaluate the shielding costs and the other facilities those are directly related to the room design. In the evaluation process it was noted that the non-optimized room size (i.e., 610 × 610 cm 2 or 20 feet × 20 feet) is not suitable for total body irradiation (TBI) although the machine installed inside was having not only the facility of TBI but the license was acquired. By keeping this point in view, the optimized INAC's room size was kept 762 × 762 cm 2. Although, the area of the optimized rooms was greater than the non-planned room (i.e., 762 × 762 cm 2 instead of 610 × 610 cm 2), the shielding cost for the optimized LINAC's rooms was reduced by 15%. When optimized shielding calculations were re-performed for non-optimized shielding room (i.e., keeping room size, occupancy factors, workload etc. same), it was found that the shielding cost may be lower to 41 %. In conclusion, non- optimized LINAC's room can not only put extra financial burden on the hospital but also can cause of some serious issues related to providing health care facilities for patients. © 2012 American Association of Physicists in Medicine.

  10. Radiation shielding plate

    International Nuclear Information System (INIS)

    Kobayashi, Torakichi; Sugawara, Takeo.

    1983-01-01

    Purpose: To reduce the weight and stabilize the configuration of a radiation shielding plate which is used in close contact with an object to be irradiated with radiation rays. Constitution: The radiation shielding plate comprises a substrate made of lead glass and a metallic lead coating on the surface of the substrate by means of plating, vapor deposition or the like. Apertures for permeating radiation rays are formed to the radiation shielding plate. Since the shielding plate is based on a lead glass plate, a sufficient mechanical strength can be obtained with a thinner structure as compared with the conventional plate made of metallic lead. Accordingly, if the shielding plate is disposed on a soft object to be irradiated with radiation rays, the object and the plate itself less deform to obtain a radiation irradiation pattern with distinct edges. (Moriyama, K.)

  11. Analytic Ballistic Performance Model of Whipple Shields

    Science.gov (United States)

    Miller, J. E.; Bjorkman, M. D.; Christiansen, E. L.; Ryan, S. J.

    2015-01-01

    The dual-wall, Whipple shield is the shield of choice for lightweight, long-duration flight. The shield uses an initial sacrificial wall to initiate fragmentation and melt an impacting threat that expands over a void before hitting a subsequent shield wall of a critical component. The key parameters to this type of shield are the rear wall and its mass which stops the debris, as well as the minimum shock wave strength generated by the threat particle impact of the sacrificial wall and the amount of room that is available for expansion. Ensuring the shock wave strength is sufficiently high to achieve large scale fragmentation/melt of the threat particle enables the expansion of the threat and reduces the momentum flux of the debris on the rear wall. Three key factors in the shock wave strength achieved are the thickness of the sacrificial wall relative to the characteristic dimension of the impacting particle, the density and material cohesion contrast of the sacrificial wall relative to the threat particle and the impact speed. The mass of the rear wall and the sacrificial wall are desirable to minimize for launch costs making it important to have an understanding of the effects of density contrast and impact speed. An analytic model is developed here, to describe the influence of these three key factors. In addition this paper develops a description of a fourth key parameter related to fragmentation and its role in establishing the onset of projectile expansion.

  12. Design report for shielded glove box

    International Nuclear Information System (INIS)

    Ku, J. H.; Lee, J. C.; Seo, K. S.; Bang, K. S.; Lee, D. W.; Kim, J. H.; Min, D. K.; Park, S. W.

    1999-05-01

    For the examination of spent fuels and high radioactive specimens using a specially equipped scanning electron microscope, a shielded glove box was designed and constructed at PIE facility of KAERI. This glove box consisted of shielding walls, containment box, lead glasses, manipulators, gloves, ventilation systems, doors, hot-cell specimen cask adapter, etc. It was emphasized that both the easy operation and radiation safety are important factors in the shielded glove box were installed also considered as a important factor to build the basic concept of the assembling. Two sliding doors and one hinge-type door were installed for the easy installation, operation and maintenance of scanning electron microscope. Containment box which confines the radioactive material into the box consisted of reinforced transparent glasses, aluminum frames and stainless steel plate liner. Therefore everything beyond the containment box can be seen through the lead glass which installed at the front shielding wall. All shielding walls and doors were introduced separately into the room and assembled by bolting. (author). 3 refs., 5 tabs., 18 figs

  13. DETERMINATION OF ANALYTICAL CALCULATION ERROR OF MAGNETIC FIELD OF HIGH-VOLTAGE CABLE LINES WITH TWO-POINT BONDED CABLE SHIELDS CAUSED BY NON-UNIFORM CURRENT DISTRIBUTION IN THE SHIELDS

    Directory of Open Access Journals (Sweden)

    M. I. Baranov

    2017-06-01

    Full Text Available Purpose. To obtain new calculation correlations, determining approximate energy dissipation and electric erosion of massive basic metallic electrodes in the high-voltage high-current air switchboard (HVCAS of atmospheric pressure, in-use in the bit chain of the high-voltage electrophysics setting (HVES with the powerful capacity store of energy (CSE. Methodology. Electrophysics bases of technique of high-voltage and large impulsive currents (LIC, scientific and technical bases of development and planning of high-voltage heavy-current impulsive electro-devices, including HVES and powerful CSE, and also methods of measuring in their bit chains of LIC of the microsecond temporal range. Results. On the basis of new engineering approach the results of calculation estimation of excretions energy and electric erosion of massive basic metallic electrodes are resulted in probed HVCAS. New correlations are obtained for the approximate calculation of thermal energy, selected in an impulsive air spark and on the workings surfaces of anode and cathode of HVCAS. It is entered and a new electrophysics concept, touching equivalent active resistance of impulsive air spark, is mathematically certain. New formulas are obtained for the approximate calculation of most depth of single round crater of destruction on the workings surfaces of basic metallic electrodes of HVCAS, and also mass of metal, thrown out magnetic pressure from this crater of destruction on the electrodes of switch for one electric discharge through them powerful CSE HVES. It is shown that the radius of the indicated single crater of destruction is approximately equal to the maximal radius of plasma channel of a spark discharge between a cathode and anode of HVCAS. The executed high-current experiments in the bit chain of HVES with powerful CSE validated row of the got and in-use calculation correlations for the estimation of energy dissipation and electric erosion of metallic electrodes in

  14. An MR-compatible stereoscopic in-room 3D display for MR-guided interventions.

    Science.gov (United States)

    Brunner, Alexander; Groebner, Jens; Umathum, Reiner; Maier, Florian; Semmler, Wolfhard; Bock, Michael

    2014-08-01

    A commercial three-dimensional (3D) monitor was modified for use inside the scanner room to provide stereoscopic real-time visualization during magnetic resonance (MR)-guided interventions, and tested in a catheter-tracking phantom experiment at 1.5 T. Brightness, uniformity, radio frequency (RF) emissions and MR image interferences were measured. Due to modifications, the center luminance of the 3D monitor was reduced by 14%, and the addition of a Faraday shield further reduced the remaining luminance by 31%. RF emissions could be effectively shielded; only a minor signal-to-noise ratio (SNR) decrease of 4.6% was observed during imaging. During the tracking experiment, the 3D orientation of the catheter and vessel structures in the phantom could be visualized stereoscopically.

  15. Laboratory-scale shielded cell for 252Cf

    International Nuclear Information System (INIS)

    Anderl, R.A.; Cargo, C.H.

    1979-01-01

    A shielded-cell facility for storing and handling remotely up to 2 milligram quantities of unencapsulated 252 Cf has been built in a radiochemistry laboratory at the Test Reactor Area of the Idaho National Engineering Laboratory. Unique features of this facility are its compact bulk radiation shield of borated gypsum and transfer lines which permit the transport of fission product activity from 252 Cf fission sources within the cell to a mass separator and to a fast radiochemistry system in nearby rooms

  16. Radiation shielding and safety design

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yong Ouk; Gil, C. S.; Cho, Y. S.; Kim, D. H.; Kim, H. I.; Kim, J. W.; Lee, C. W.; Kim, K. Y.; Kim, B. H. [KAERI, Daejeon (Korea, Republic of)

    2011-07-15

    A benchmarking for the test facility, evaluations of the prompt radiation fields, evaluation of the induced activities in the facility, and estimation of the radiological impact on the environment were performed in this study. and the radiation safety analysis report for nuclear licensing was written based on this study. In the benchmark calculation, the neutron spectra was measured in the 20 Mev test facility and the measurements were compared with the computational results to verify the calculation system. In the evaluation of the prompt radiation fields, the shielding design for 100 MeV target rooms, evaluations of the leakage doses from the accidents and skyshine analysis were performed. The evaluation of the induced activities were performed for the coolant, inside air, structural materials, soil and ground-water. At last, the radiation safety analysis report was written based on results from these studies

  17. Concrete mix design for X-and gamma shielding

    International Nuclear Information System (INIS)

    Mohamad Pauzi Ismail; Noor Azreen Masenwat; Suhairy Sani; Abdul Bakhri Muhammad; Mohd Kamal Shah Shamsuddin; Rahmad Abd Rashid

    2012-01-01

    The design of X-ray or gamma ray radiographic exposure room requires some calculations on shielding to provide safe operation of the facility and minimum exposure to radiation workers. Careful design can lead to economical installations with minimal barriers. The design depends on such factors as: maximum energy, maximum intensity, permitted full-body dosage, workload, use factor, occupancy factor, maximum dose output and shielding materials. Choice of material for a barrier depends on convenience and cost. The radiographic exposure room is usually made of normal concrete with density of about 2.3 - 2.4 g/ cc. Normal concrete is often used for construction of exposure room because of cheap and ease of construction. This paper explained and discussed the optimum mix design for normal concrete used for X-and gamma shielding. (author)

  18. Research of the cold shield in cryogenic liquid storage

    Science.gov (United States)

    Chen, L. B.; Zheng, J. P.; Wu, X. L.; Cui, C.; Zhou, Y.; Wang, J. J.

    2017-12-01

    To realize zero boil-off storage of cryogenic liquids, a cryocooler that can achieve a temperature below the boiling point temperature of the cryogenic liquid is generally needed. Taking into account that the efficiency of the cryocooler will be higher at a higher operating temperature, a novel thermal insulation system using a sandwich container filled with cryogenic liquid with a higher boiling point as a cold radiation shield between the cryogenic tank and the vacuum shield in room temperature is proposed to reduce the electricity power consumption. A two-stage cryocooler or two separate cryocoolers are adopted to condense the evaporated gas from the cold shield and the cryogenic tank. The calculation result of a 55 liter liquid hydrogen tank with a liquid nitrogen shield shows that only 14.4 W of electrical power is needed to make all the evaporated gas condensation while 121.7 W will be needed without the liquid nitrogen shield.

  19. SHIELD 1.0: development of a shielding calculator program in diagnostic radiology

    International Nuclear Information System (INIS)

    Santos, Romulo R.; Real, Jessica V.; Luz, Renata M. da; Friedrich, Barbara Q.; Silva, Ana Maria Marques da

    2013-01-01

    In shielding calculation of radiological facilities, several parameters are required, such as occupancy, use factor, number of patients, source-barrier distance, area type (controlled and uncontrolled), radiation (primary or secondary) and material used in the barrier. The shielding design optimization requires a review of several options about the physical facility design and, mainly, the achievement of the best cost-benefit relationship for the shielding material. To facilitate the development of this kind of design, a program to calculate the shielding in diagnostic radiology was implemented, based on data and limits established by National Council on Radiation Protection and Measurements (NCRP) 147 and SVS-MS 453/98. The program was developed in C⌗ language, and presents a graphical interface for user data input and reporting capabilities. The module initially implemented, called SHIELD 1.0, refers to calculating barriers for conventional X-ray rooms. The program validation was performed by the comparison with the results of examples of shielding calculations presented in NCRP 147.

  20. Room temperature Q-band electron magnetic resonance study of radicals in X-ray-irradiated L-threonine single crystals

    International Nuclear Information System (INIS)

    Vanhaelewyn, Gauthier; Vrielinck, Henk; Callens, Freddy

    2014-01-01

    In the past, decennia radiation-induced radicals were successfully identified by electron magnetic resonance (EMR) in several solid-state amino acids and sugars. The authors present a room temperature (RT) EMR study of the stable radicals produced by X-ray-irradiation in the amino acid L-threonine (CH 3 CH(OH)CH(NH3 + )COO - ). Its chemical structure is similar to that of the well-known dosimetric material L-alanine (CH 3 CH(NH3 + )COO - ), and radiation defects in L-threonine may straightforwardly be compared with the extensively studied L-alanine radicals. The hyperfine coupling tensors of three different radicals were determined at RT using electron nuclear double resonance. These results indicate that the two most abundant radicals share the same basic structure CH 3 .C(OH)CH(NH3 + )COO - , obtained by H-abstraction, but are stabilised in slightly different conformations. The third radical is most probably obtained by deamination (CH 3 CH(OH).CHCOO - ), similar in structure to the stable alanine radical. (authors)

  1. Clean room actuators

    Energy Technology Data Exchange (ETDEWEB)

    Higuchi, Toshiro

    1987-06-01

    This report explains on the present status of the clean room actuators including the author's research results. In a clean room, there exists a possibility of dust generation, even when a direct human work is eliminated by the use of robots or automatic machines, from the machines themselves. For this, it is important to develop such clean robots and transfer/positioning mechanism that do not generate dusts, and to develop an actuator and its control technique. Topics described in the report are as follows: 1. Prevention of dust diffusion by means of sealing. 2. Elimination of mechanical contact (Linear induction motor and pneumatic float, linear motor and magnetic attraction float, linear motor and air bearing, and magnetic bearing). 3. Contactless actuator having a positioning mechanism (Use of linear step motor and rotary contactless actuator). (15 figs, 11 refs)

  2. Shielding member for thermonuclear device

    Energy Technology Data Exchange (ETDEWEB)

    Onozuka, Masanori

    1997-06-30

    In a thermonuclear device for shielding fast neutrons by shielding members disposed in a shielding vessel (vacuum vessel and structures such as a blanket disposed in the vacuum vessel), the shielding member comprises a large number of shielding wires formed fine and short so as to have elasticity. The shielding wires are sealed in a shielding vessel together with water, and when the width of the shielding vessel is changed, the shielding wires follow after the change of the width while elastically deforming in the shielding vessel, so that great stress and deformation are not formed thereby enabling to improve reliability. In addition, the length, the diameter and the shape of each of the shielding wires can be selected in accordance with the shielding space of the shielding vessel. Even if the shape of the shielding vessel is complicated, the shielding wires can be inserted easily. Accordingly, the filling rate of the shielding members can be changed easily. It can be produced more easily compared with a conventional spherical pebbles. It can be produced more easily than existent spherical shielding pebbles thereby enabling to reduce the production cost. (N.H.)

  3. Resistivity, hysteresis, and magnetization of 9% Cr stainless steel as a function of temperature and its electromagnetic shielding effects in cylindrical structures

    International Nuclear Information System (INIS)

    Praeg, W.F.

    1979-01-01

    Ferromagnetic stainless steels may offer significantly greater wall life-times for first wall/blanket and vacuum vessel structures than commonly used non-magnetic stainless steels. One steel under consideration has the following composition, in wt %, Fe(86.24), Cr(9), Mo(2), Mn(1), Si(0.75), Nb(0.50), V(0.30), C(0.15), P(0.3), S(0.30). There appears to be no literature on the electromagnetic properties of this material. Therefore, the resistivity, the hysteresis loops, and magnetization were measured as a function of temperature up to the Curie point

  4. Estimating ISABELLE shielding requirements

    International Nuclear Information System (INIS)

    Stevens, A.J.; Thorndike, A.M.

    1976-01-01

    Estimates were made of the shielding thicknesses required at various points around the ISABELLE ring. Both hadron and muon requirements are considered. Radiation levels at the outside of the shield and at the BNL site boundary are kept at or below 1000 mrem per year and 5 mrem/year respectively. Muon requirements are based on the Wang formula for pion spectra, and the hadron requirements on the hadron cascade program CYLKAZ of Ranft. A muon shield thickness of 77 meters of sand is indicated outside the ring in one area, and hadron shields equivalent to from 2.7 to 5.6 meters in thickness of sand above the ring. The suggested safety allowance would increase these values to 86 meters and 4.0 to 7.2 meters respectively. There are many uncertainties in such estimates, but these last figures are considered to be rather conservative

  5. Scintillation counter, segmented shield

    International Nuclear Information System (INIS)

    Olson, R.E.; Thumim, A.D.

    1975-01-01

    A scintillation counter, particularly for counting gamma ray photons, includes a massive lead radiation shield surrounding a sample-receiving zone. The shield is disassembleable into a plurality of segments to allow facile installation and removal of a photomultiplier tube assembly, the segments being so constructed as to prevent straight-line access of external radiation through the shield into radiation-responsive areas. Provisions are made for accurately aligning the photomultiplier tube with respect to one or more sample-transmitting bores extending through the shield to the sample receiving zone. A sample elevator, used in transporting samples into the zone, is designed to provide a maximum gamma-receiving aspect to maximize the gamma detecting efficiency. (U.S.)

  6. Shields for nuclear reactors

    International Nuclear Information System (INIS)

    Aspden, G.J.

    1984-01-01

    The patent concerns shields for nuclear reactors. The roof shield comprises a normally fixed radial outer portion, a radial inner portion rotatable about a vertical axis, and a connection between the inner and outer portions. In the event of hypothecal core disruption conditions, a cantilever system on the inner wall allows the upward movement of the inner wall, in order to prevent loss of containment. (UK)

  7. Radiation shielding curtain

    International Nuclear Information System (INIS)

    Winkler, N.T.

    1976-01-01

    A radiation shield is described in the form of a stranded curtain made up of bead-chains whose material and geometry are selected to produce a cross-sectional density that is the equivalent of 0.25 mm or more of lead and which curtain may be mounted on various radiological devices to shield against scattered radiation while offering a minimum of obstruction to the radiologist

  8. Shielded cells transfer automation

    International Nuclear Information System (INIS)

    Fisher, J.J.

    1984-01-01

    Nuclear waste from shielded cells is removed, packaged, and transferred manually in many nuclear facilities. Radiation exposure is absorbed by operators during these operations and limited only through procedural controls. Technological advances in automation using robotics have allowed a production waste removal operation to be automated to reduce radiation exposure. The robotic system bags waste containers out of glove box and transfers them to a shielded container. Operators control the system outside the system work area via television cameras. 9 figures

  9. Magnetic-field-induced irreversible antiferromagnetic–ferromagnetic phase transition around room temperature in as-cast Sm–Co based SmCo{sub 7−x}Si{sub x} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Feng, D.Y.; Zhao, L.Z.; Liu, Z.W., E-mail: zwliu@scut.edu.cn

    2016-04-15

    A magnetic-field-induced irreversible metamagnetic phase transition from antiferro- to ferromagnetism, which leads to an anomalous initial-magnetization curve lying outside the magnetic hysteresis loop, is reported in arc-melted SmCo{sub 7−x}Si{sub x} alloys. The transition temperatures are near room temperature, much higher than other compounds with similar initial curves. Detailed investigation shows that this phenomenon is dependent on temperature, magnetic field and Si content and shows some interesting characteristics. It is suggested that varying interactions between the Sm and Co layers in the crystal are responsible for the formation of a metastable AFM structure, which induces the anomalous phenomenon in as-cast alloys. The random occupation of 3g sites by Si and Co atoms also has an effect on this phenomenon.

  10. Creators Room

    DEFF Research Database (Denmark)

    Iversholt, Lene; Iversholt Toft, Karina

    2012-01-01

    Creators Room er et koncept til daginsitutioner, der indrammer og giver bud på en forståelse mellem inkluderende pædagogik og fysiske rammer. Konceptet er udviklet i et tværfagligt procesforløb, hvor formålet har været at skabe stadig bedre indendørsmiljøer for børn ved at forene pædagogiske...

  11. Remote handling devices for use behind shielding walls

    International Nuclear Information System (INIS)

    1974-11-01

    The standardized general dimensions as recommended in this standard will facilitate the planning and construction of shielding rooms in which master-slave manipulators as specified in this standard are to be used, as well as the interchangeability of these instruments. It will also help to shorten the time of delivery in the initial supply of master-slave manipulators for these rooms and in the supply of replacement parts. (orig./AK) [de

  12. An experimental study on a superconducting generator with dual machine shield system

    International Nuclear Information System (INIS)

    Ishigohka, T.; Ninomiya, A.; Okada, T.; Nitta, T.; Shintani, T.; Mukai, E.

    1988-01-01

    The authors have studied the optimal machine shield system through experiments on a 20kVa superconducting generator. The first experiment is carried out on a fully iron-less aluminum-shield machine which has only an aluminum eddy current machine shield in the stator. The second experiment is carried out on a generator with a dual-shield system which has both an aluminum eddy current shield and an iron magnetic shield. From the first one, the authors have got an experimental result that the aluminum-shield machine exhibits so large eddy current loss in the shield that it would be difficult to operate the machine continuously. On the other hand, the second experiment shows that the dual-shield machine exhibits much smaller loss in the shielding system, and that it has higher output power than the aluminum-shield machine. From these experiments, it becomes clear that insertion of a very thin iron shield between the armature winding and the eddy current shield can improve the machine performance eminently without large weight increase even if the iron shield were saturated

  13. Neutron shielding material

    International Nuclear Information System (INIS)

    Nodaka, M.; Iida, T.; Taniuchi, H.; Yosimura, K.; Nagahama, H.

    1993-01-01

    From among the neutron shielding materials of the 'kobesh' series developed by Kobe Steel, Ltd. for transport and storage packagings, silicon rubber base type material has been tested for several items with a view to practical application and official authorization, and in order to determine its adaptability to actual vessels. Silicon rubber base type 'kobesh SR-T01' is a material in which, from among the silicone rubber based neutron shielding materials, the hydrogen content is highest and the boron content is most optimized. Its neutron shielding capability has been already described in the previous report (Taniuchi, 1986). The following tests were carried out to determine suitability for practical application; 1) Long-term thermal stability test 2) Pouring test on an actual-scale model 3) Fire test The experimental results showed that the silicone rubber based neutron shielding material has good neutron shielding capability and high long-term fire resistance, and that it can be applied to the advanced transport packaging. (author)

  14. Concrete radiation shielding

    International Nuclear Information System (INIS)

    Kaplan, M.F.

    1989-01-01

    The increased use of nuclear energy has given rise to a growth in the amount of artificially produced radiation and radioactive materials. The design and construction of shielding to protect people, equipment and structures from the effects of radiation has never been more important. Experience has shown that concrete is an effective, versatile and economical material for the construction of radiation shielding. This book provides information on the principles governing the interaction of radiation with matter and on relevant nuclear physics to give the engineer an understanding of the design and construction of concrete shielding. It covers the physical, mechanical and nuclear properties of concrete; the effects of elevated temperatures and possible damage to concrete due to radiation; basic procedures for the design of concrete radiation shields and finally the special problems associated with their construction and cost. Although written primarily for engineers concerned with the design and construction of concrete shielding, the book also reviews the widely scattered data and information available on this subject and should therefore be of interest to students and those wishing to research further in this field. (author)

  15. Method for dismantling shields

    International Nuclear Information System (INIS)

    Fukuzawa, Rokuro; Kondo, Nobuhiro; Kamiyama, Yoshinori; Kawasato, Ken; Hiraga, Tomoaki.

    1990-01-01

    The object of the present invention is to enable operators to dismantle shieldings contaminated by radioactivity easily and in a short period of time without danger of radiation exposure. A plurality of introduction pipes are embedded previously to the shielding walls of shielding members which contain a reactor core in a state where both ends of the introduction pipes are in communication with the outside. A wire saw is inserted into the introduction pipes to cut the shieldings upon dismantling. Then, shieldings can be dismantled easily in a short period of time with no radiation exposure to operator's. Further, according to the present invention, since the wire saw can be set easily and a large area can be cut at once, operation efficiency is improved. Further, since remote control is possible, cutting can be conducted in water and complicated places of the reactor. Biting upon starting the wire saw in the introduction pipe is reduced to facilitate startup for the rotation. (I.S.)

  16. Mechanical shielded hot cell

    International Nuclear Information System (INIS)

    Higgy, H.R.; Abdel-Rassoul, A.A.

    1983-01-01

    A plan to erect a mechanical shielded hot cell in the process hall of the Radiochemical Laboratory at Inchas is described. The hot cell is designed for safe handling of spent fuel bundles, from the Inchas reactor, and for dismantling and cutting the fuel rods in preparation for subsequent treatment. The biological shielding allows for the safe handling of a total radioactivity level up to 10,000 MeV-Ci. The hot cell consists of an α-tight stainless-steel box, connected to a γ-shielded SAS, through an air-lock containing a movable carriage. The α-box is tightly connected with six dry-storage cavities for adequate storage of the spent fuel bundles. Both the α-box, with the dry-storage cavities, and the SAS are surrounded by 200-mm thick biological lead shielding. The α-box is equipped with two master-slave manipulators, a lead-glass window, a monorail crane and Padirac and Minirag systems. The SAS is equipped with a lead-glass window, tong manipulator, a shielded pit and a mechanism for the entry of the spent fuel bundle. The hot cell is served by adequate ventilation and monitoring systems. (author)

  17. Electrodynamic Dust Shield Demonstrator

    Science.gov (United States)

    Stankie, Charles G.

    2013-01-01

    The objective of the project was to design and manufacture a device to demonstrate a new technology developed by NASA's Electrostatics and Surface Physics Laboratory. The technology itself is a system which uses magnetic principles to remove regolith dust from its surface. This project was to create an enclosure that will be used to demonstrate the effectiveness of the invention to The Office of the Chief Technologist. ONE of the most important challenges of space exploration is actually caused by something very small and seemingly insignificant. Dust in space, most notably on the moon and Mars, has caused many unforeseen issues. Dirt and dust on Earth, while a nuisance, can be easily cleaned and kept at bay. However, there is considerably less weathering and erosion in space. As a result, the microscopic particles are extremely rough and abrasive. They are also electrostatically charged, so they cling to everything they make contact with. This was first noted to be a major problem during the Apollo missions. Dust would stick to the spacesuits, and could not be wiped off as predicted. Dust was brought back into the spacecraft, and was even inhaled by astronauts. This is a major health hazard. Atmospheric storms and other events can also cause dust to coat surfaces of spacecraft. This can cause abrasive damage to the craft. The coating can also reduce the effectiveness of thermal insulation and solar panels.' A group of engineers at Kennedy Space Center's Electrostatics and Surface Physics Laboratory have developed a new technology, called the Electrodynamic Dust Shield, to help alleviate these problems. It is based off of the electric curtain concept developed at NASA in 1967. "The EDS is an active dust mitigation technology that uses traveling electric fields to transport electrostatically charged dust particles along surfaces. To generate the traveling electric fields, the EDS consists of a multilayer dielectric coating with an embedded thin electrode grid

  18. Shield support frame. Schildausbaugestell

    Energy Technology Data Exchange (ETDEWEB)

    Plaga, K.

    1981-09-17

    A powered shield support frame for coal sheds is described comprising of two bottom sliding shoes, a large area gob shield and a larg area roof assembly, all joined movable together. The sliding shoes and the gob shield are joined by a lemniscate guide. Two hydraulic props are arranged at the face-side at one third of the length of the sliding shoes and at the goaf-side at one third of the length of the roof assembly. A nearly horizontal lying pushing prop unit joins the bottom wall sliding shoes to the goaf-side lemniscate guide. This assembly can be applied to seams with a thickness down to 45 cm. (OGR).

  19. Radiation shielding material

    International Nuclear Information System (INIS)

    Matsumoto, Akio; Isobe, Eiji.

    1976-01-01

    Purpose: To increase the shielding capacity of the radiation shielding material having an abundant flexibility. Constitution: A mat consisting of a lead or lead alloy fibrous material is covered with a cloth, and the two are made integral by sewing in a kilted fashion by using a yarn. Thereafter, the system is covered with a gas-tight film or sheet. The shielding material obtained in this way has, in addition to the above merits, advantages in that (1) it is free from restoration due to elasticity so that it can readily seal contaminants, (2) it can be used in a state consisting of a number of overlapped layers, (3) it fits the shoulder well and is readily portable and (4) it permits attachment of fasteners or the like. (Ikeda, J.)

  20. Reactor head shielding apparatus

    International Nuclear Information System (INIS)

    Schukei, G.E.; Roebelen, G.J.

    1992-01-01

    This patent describes a nuclear reactor head shielding apparatus for mounting on spaced reactor head lifting members radially inwardly of the head bolts. It comprises a frame of sections for mounting on the lifting members and extending around the top central area of the head, mounting means for so mounting the frame sections, including downwardly projecting members on the frame sections and complementary upwardly open recessed members for fastening to the lifting members for receiving the downwardly projecting members when the frame sections are lowered thereto with lead shielding supported thereby on means for hanging lead shielding on the frame to minimize radiation exposure or personnel working with the head bolts or in the vicinity thereof

  1. Double-layer neutron shield design as neutron shielding application

    Science.gov (United States)

    Sariyer, Demet; Küçer, Rahmi

    2018-02-01

    The shield design in particle accelerators and other high energy facilities are mainly connected to the high-energy neutrons. The deep penetration of neutrons through massive shield has become a very serious problem. For shielding to be efficient, most of these neutrons should be confined to the shielding volume. If the interior space will become limited, the sufficient thickness of multilayer shield must be used. Concrete and iron are widely used as a multilayer shield material. Two layers shield material was selected to guarantee radiation safety outside of the shield against neutrons generated in the interaction of the different proton energies. One of them was one meter of concrete, the other was iron-contained material (FeB, Fe2B and stainless-steel) to be determined shield thicknesses. FLUKA Monte Carlo code was used for shield design geometry and required neutron dose distributions. The resulting two layered shields are shown better performance than single used concrete, thus the shield design could leave more space in the interior shielded areas.

  2. Shielding research in France

    Energy Technology Data Exchange (ETDEWEB)

    Lafore, P

    1964-10-01

    Shielding research as an independent subject in France dates from 1956. The importance of these studies has been reflected in the contribution which they have made to power reactor design and in the resultant savings in expenditure for civil engineering and machinery for the removal of mobile shields. The Reactor Shielding Research Division numbers approximately 60 persons and uses several experimental facilities. These include: NAIADE I, installed near the ZOE reactor and operating with a natural uranium slab 2 cm thick (an effective diameter of 60 cm is the one most commonly used); the TRITON pool-type reactor, mainly used in shielding studies, includes an active-water loop, by means of which the secondary shields required for light-water reactors can be studied; core, NEREIDE, which is situated near a 2 m x 2 m aluminium window enables a large neutron source to be placed in a compartment without water in which large-scale mock-ups can be mounted for the study, in particular, of neutron diffusion in large cavities, and of reactor shielding of greater thickness than that in NAIADE I; SAMES 600 keV accelerator is used for monoenergetic neutron studies. Instrumentation studies are an important part of the work, mainly in the measurement of fast neutrons and their spectra by activation detectors. Of late, attention has been directed towards the use of (n, n') (rhodium) reactions and of heavy detectors for low-flux measurements. The simultaneous use of a large number of detectors poses automation problems. With our installation we can count 16 detectors simultaneously. Neutron spectrum studies are conducted with nuclear emulsions and a lithium-6 semiconductor spectrometer. As to the materials used, the research carried out in France involves chiefly graphite, iron and concrete at various temperatures up to 800 deg C. Different compounds, borated and non-borated and of densities up to between 1 and 9 are under consideration. Problems connected with applications are

  3. Post Three Mile Island shielding review - a case history

    International Nuclear Information System (INIS)

    Isakari, H.H.; Shaw, H.C.

    1983-01-01

    The radiation shielding review of the Diablo Canyon Nuclear Power Plant was performed in accordance with the requirement of the Three Mile Island Action Plan. The review covered plant shielding and environmental qualification of equipment for spaces and systems which may be used in post-accident operations. Radiation doses during postulated loss-of-coolant accident and high-energy-line-break accident were calculated for equipment located both inside and outside the containment. Vital areas, those requiring post-accident access and occupancy, were identified and their associated dose rates and integrated doses were calculated. It was found that all four of the vital areas (Control Room, Technical Support Center, Switchgear Room, and Emergency Sampling Compartment) are shielded from external sources of radiation sufficiently to permit personnel access and occupancy that would not be unduly limited by the radiation environment caused by the postulated accidents. (author)

  4. Radiation shielding bricks

    International Nuclear Information System (INIS)

    Crowe, G.J.W.

    1983-01-01

    A radiation shielding brick for use in building dry walls to form radiation proof enclosures and other structures is described. It is square in shape and comprises a sandwich of an inner layer of lead or similar shielding material between outer layers of plastics material, for structural stability. The ability to mechanically interlock adjacent bricks is provided by shaping the edges as cooperating external and internal V-sections. Relatively leak-free joints are ensured by enlarging the width of the inner layer in the edge region. (author)

  5. Effects of the thermal and magnetic paths on first order martensite transition of disordered Ni45Mn44Sn9In2 Heusler alloy exhibiting a giant magnetocaloric effect and magnetoresistance near room temperature

    Science.gov (United States)

    Chabri, T.; Ghosh, A.; Nair, Sunil; Awasthi, A. M.; Venimadhav, A.; Nath, T. K.

    2018-05-01

    The existence of a first order martensite transition in off-stoichiometric Ni45Mn44Sn9In2 ferromagnetic shape memory Heusler alloy has been clearly observed by thermal, magnetic, and magneto-transport measurements. Field and thermal path dependence of the change in large magnetic entropy and negative magnetoresistance are observed, which originate due to the sharp change in magnetization driven by metamagnetic transition from the weakly magnetic martensite phase to the ferromagnetic austenite phase in the vicinity of the martensite transition. The noticeable shift in the martensite transition with the application of a magnetic field is the most significant feature of the present study. This shift is due to the interplay of the austenite and martensite phase fraction in the alloy. The different aspects of the first order martensite transition, e.g. broadening of the martensite transition and the field induced arrest of the austenite phase are mainly related to the dynamics of coexisting phases in the vicinity of the martensite transition. The alloy also shows a second order ferromagnetic  →  paramagnetic transition near the Curie temperature of the austenite phase. A noticeably large change in magnetic entropy (ΔS M   =  24 J kg‑1 K‑1 at 298 K) and magnetoresistance (=  ‑33% at 295 K) has been observed for the change in 5 and 8 T magnetic fields, respectively. The change in adiabatic temperature for the change in a magnetic field of 5 T is found to be  ‑3.8 K at 299 K. The low cost of the ingredients and the large change in magnetic entropy very near to the room temperature makes Ni45Mn44Sn9In2 alloy a promising magnetic refrigerant for real technological application.

  6. Self-Shielding Of Transmission Lines

    Energy Technology Data Exchange (ETDEWEB)

    Christodoulou, Christos [Univ. of New Mexico, Albuquerque, NM (United States)

    2017-03-01

    The use of shielding to contend with noise or harmful EMI/EMR energy is not a new concept. An inevitable trade that must be made for shielding is physical space and weight. Space was often not as much of a painful design trade in older larger systems as they are in today’s smaller systems. Today we are packing in an exponentially growing number of functionality within the same or smaller volumes. As systems become smaller and space within systems become more restricted, the implementation of shielding becomes more problematic. Often, space that was used to design a more mechanically robust component must be used for shielding. As the system gets smaller and space is at more of a premium, the trades starts to result in defects, designs with inadequate margin in other performance areas, and designs that are sensitive to manufacturing variability. With these challenges in mind, it would be ideal to maximize attenuation of harmful fields as they inevitably couple onto transmission lines without the use of traditional shielding. Dr. Tom Van Doren proposed a design concept for transmission lines to a class of engineers while visiting New Mexico. This design concept works by maximizing Electric field (E) and Magnetic Field (H) field containment between operating transmission lines to achieve what he called “Self-Shielding”. By making the geometric centroid of the outgoing current coincident with the return current, maximum field containment is achieved. The reciprocal should be true as well, resulting in greater attenuation of incident fields. Figure’s 1(a)-1(b) are examples of designs where the current centroids are coincident. Coax cables are good examples of transmission lines with co-located centroids but they demonstrate excellent field attenuation for other reasons and can’t be used to test this design concept. Figure 1(b) is a flex circuit design that demonstrate the implementation of self-shielding vs a standard conductor layout.

  7. Radiation shielding calculations for the vista spacecraft

    International Nuclear Information System (INIS)

    Sahin, Suemer; Sahin, Haci Mehmet; Acir, Adem

    2005-01-01

    The VISTA spacecraft design concept has been proposed for manned or heavy cargo deep space missions beyond earth orbit with inertial fusion energy propulsion. Rocket propulsion is provided by fusion power deposited in the inertial confined fuel pellet debris and with the help of a magnetic nozzle. The calculations for the radiation shielding have been revised under the fact that the highest jet efficiency of the vehicle could be attained only if the propelling plasma would have a narrow temperature distribution. The shield mass could be reduced from 600 tons in the original design to 62 tons. Natural and enriched lithium were the principle shielding materials. The allowable nuclear heating in the superconducting magnet coils (up to 5 mW/cm 3 ) is taken as the crucial criterion for dimensioning the radiation shielding structure of the spacecraft. The space craft mass is 6000 tons. Total peak nuclear power density in the coils is calculated as ∼5.0 mW/cm 3 for a fusion power output of 17 500 MW. The peak neutron heating density is ∼2.0 mW/cm 3 , and the peak γ-ray heating density is ∼3.0 mW/cm 3 (on different points) using natural lithium in the shielding. However, the volume averaged heat generation in the coils is much lower, namely 0.21, 0.71 and 0.92 mW/cm 3 for the neutron, γ-ray and total nuclear heating, respectively. The coil heating will be slightly lower if highly enriched 6 Li (90%) is used instead of natural lithium. Peak values are then calculated as 2.05, 2.15 and 4.2 mW/cm 3 for the neutron, γ-ray and total nuclear heating, respectively. The corresponding volume averaged heat generation in the coils became 0.19, 0.58 and 0.77 mW/cm 3

  8. Radiation shielding cloth

    International Nuclear Information System (INIS)

    Ijiri, Yasuo; Fujinuma, Tadashi; Tamura, Shoji.

    1989-01-01

    Radiation shielding cloth having radiation shielding layers comprising a composition of inorganic powder of high specific gravity and rubber are excellentin flexibility and comfortable to put on. However, since they are heavy in the weight, operators are tired upon putting them for a long time. In view of the above, the radiation ray shielding layers are prepared by calendering sheets obtained by preliminary molding of the composition to set the variation of the thickness within a range of +15% to -0% of prescribed thickness. Since the composition of inorganic powder at high specific gravity and rubber used for radiation ray shielding comprises a great amount of inorganic powder at high specific gravity blended therein, it is generally poor in fabricability. Therefor, it is difficult to attain fine control for the sheet thickness by merely molding a composition block at once. Then, the composition is at first preliminarily molded into a sheet-like shape which is somewhat thickener than the final thickness and then finished by calendering, by which the thickness can be reduced in average as compared with conventional products while keeping the prescribed thickness and reducing the weight reduce by so much. (N.H.)

  9. Electrostatic shielding of transformers

    Energy Technology Data Exchange (ETDEWEB)

    De Leon, Francisco

    2017-11-28

    Toroidal transformers are currently used only in low-voltage applications. There is no published experience for toroidal transformer design at distribution-level voltages. Toroidal transformers are provided with electrostatic shielding to make possible high voltage applications and withstand the impulse test.

  10. Penetration portion shielding structure

    International Nuclear Information System (INIS)

    Hayashi, Katsumi; Narita, Hitoshi; Handa, Hiroyuki; Takeuchi, Jun; Tozuka, Fumio.

    1994-01-01

    Openings of a plurality of shieldings for penetration members are aligned to each other, and penetration members are inserted from the openings. Then, the openings of the plurality of shielding members are slightly displaced with each other to make the penetration portions into a helical configuration, so that leakage of radiation is reduced. Upon removal of the members, reverse operation is conducted. When a flowable shielding material is used, the penetration portions are constituted with two plates having previously formed openings and pipes for connecting the openings with each other and a vessel covering the entire of them. After passing the penetration members such as a cable, the relative position of the two plates is changed by twisting, to form a helical configuration which reduces radiation leakage. Since they are bent into the helical configuration, shielding performance is extremely improved compared with a case that radiation leakage is caused from an opening of a straight pipe. In addition, since they can be returned to straight pipes, attachment, detachment and maintenance can be conducted easily. (N.H.)

  11. Dosimetry and shielding

    International Nuclear Information System (INIS)

    Farinelli, U.

    1977-01-01

    Today, reactor dosimetry and shielding have wide areas of overlap as concerns both problems and methods. Increased interchange of results and know-how would benefit both. The areas of common interest include calculational methods, sensitivity studies, theoretical and experimental benchmarks, cross sections and other nuclear data, multigroup libraries and procedures for their adjustment, experimental techniques and damage functions. This paper reviews the state-of-the-art and the latest development in each of these areas as far as shielding is concerned, and suggests a number of interactions that could be profitable for reactor dosimetry. Among them, re-evaluation of the potentialities of calculational methods (in view of the recent developments) in predicting radiation environments of interest; the application of sensitivity analysis to dosimetry problems; a common effort in the field of theoretical benchmarks; the use of the shielding one-material propagation experiments as reference spectra for detector cross sections; common standardization of the detector nuclear data used in both fields; the setting up of a common (or compatible) multigroup structure and library applicable to shielding, dosimetry and core physics; the exchange of information and experience in the fields of cross section errors, correlations and adjustment; and the intercomparison of experimental techniques

  12. Radiation shielding glass

    International Nuclear Information System (INIS)

    Kido, Kazuhiro; Ueda, Hajime.

    1997-01-01

    It was found that a glass composition comprising, as essential ingredients, SiO 2 , PbO, Gd 2 O 3 and alkali metal oxides can provide a shielding performance against electromagnetic waves, charged particles and neutrons. The present invention provides radiation shielding glass containing at least from 16 to 46wt% of SiO 2 , from 47 to 75wt% of PbO, from 1 to 10wt% of Gd 2 O 3 , from 0 to 3wt% of Li 2 O, from 0 to 7wt% of Na 2 O, from 0 to 7wt% of K 2 O provided that Li 2 O + Na 2 O + K 2 O is from 1 to 10wt%, B 2 O 3 is from 0 to 10wt%, CeO 2 is from 0 to 3wt%, As 2 O 3 is from 0 to 1wt% and Sb 2 O 3 is from 0 to 1wt%. Since the glass can shield electromagnetic waves, charged particles and neutrons simultaneously, radiation shielding windows can be designed and manufactured at a reduced thickness and by less constitutional numbers in a circumstance where they are present altogether. (T.M.)

  13. SU-E-T-400: Evaluation of Shielding and Activation at Two Pencil Beam Scanning Proton Facilities

    International Nuclear Information System (INIS)

    Remmes, N; Mundy, D; Classic, K; Beltran, C; Kruse, J; Herman, M; Stoker, J; Nelson, K; Bues, M

    2015-01-01

    Purpose: To verify acceptably low dose levels around two newly constructed identical pencil beam scanning proton therapy facilities and to evaluate accuracy of pre-construction shielding calculations. Methods: Dose measurements were taken at select points of interest using a WENDI-2 style wide-energy neutron detector. Measurements were compared to pre-construction shielding calculations. Radiation badges with neutron dose measurement capabilities were worn by personnel and also placed at points throughout the facilities. Seven neutron and gamma detectors were permanently installed throughout the facility, continuously logging data. Potential activation hazards have also been investigated. Dose rates near water tanks immediately after prolonged irradiation have been measured. Equipment inside the treatment room and accelerator vault has been surveyed and/or wipe tested. Air filters from air handling units, sticky mats placed outside of the accelerator vault, and water samples from the magnet cooling water loops have also been tested. Results: All radiation badges have been returned with readings below the reporting minimum. Measurements of mats, air filters, cooling water, wipe tests and surveys of equipment that has not been placed in the beam have all come back at background levels. All survey measurements show the analytical shielding calculations to be conservative by at least a factor of 2. No anomalous events have been identified by the building radiation monitoring system. Measurements of dose rates close to scanning water tanks have shown dose rates of approximately 10 mrem/hr with a half-life less than 5 minutes. Measurements around the accelerator show some areas with dose rates slightly higher than 10 mrem/hr. Conclusion: The shielding design is shown to be adequate. Measured dose rates are below those predicted by shielding calculations. Activation hazards are minimal except in certain very well defined areas within the accelerator vault and for objects

  14. Neutral and plasma shielding model for pellet ablation

    International Nuclear Information System (INIS)

    Houlberg, W.A.; Milora, S.L.; Attenberger, S.E.

    1987-10-01

    The neutral gas shielding model for ablation of frozen hydrogenic pellets is extended to include the effects of an initial Maxwelliam distribution of incident electron energies; a cold plasma shield outside the neutral shield and extended along the magnetic field; energetic neutral beam ions and alpha particles; and self-limiting electron ablation in the collisionless plasma limit. Including the full electron distribution increases ablation, but adding the cold ionized shield reduces ablation; the net effect is a modest reduction in pellet penetration compared with the monoenergetic electron neutral shielding model with no plasma shield. Unlike electrons, fast ions can enter the neutral shield directly without passing through the cold ionized shield because their gyro-orbits are typically larger than the diameter of the cold plasma tube. Fast alpha particles should not enhance the ablation rate unless their population exceeds that expected from local classical thermalization. Fast beam ions, however, may enhance ablation in the plasma periphery if their population is high enough. Self-limiting ablation in the collisionless limit leads to a temporary distortion of the original plasma electron Maxwellian distribution function through preferential depopulation of the higher-energy electrons. 23 refs., 9 figs

  15. Gonad shielding in diagnostic radiology

    International Nuclear Information System (INIS)

    Anon.

    1975-01-01

    The use of gonad shielding is an important radiation protection technique, intended to reduce unnecessary x-ray exposure of the gonads of patients from diagnostic x-ray procedures. The types of gonad shields in use are discussed as are the types of diagnostic examinations that should include gonad shielding. It was found that when properly used, most shields provided substantial gonad dose reductions

  16. SHIELD 1.0: development of a shielding calculator program in diagnostic radiology; SHIELD 1.0: desenvolvimento de um programa de calculo de blindagem em radiodiagnostico

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Romulo R.; Real, Jessica V.; Luz, Renata M. da [Hospital Sao Lucas (PUCRS), Porto Alegre, RS (Brazil); Friedrich, Barbara Q.; Silva, Ana Maria Marques da, E-mail: ana.marques@pucrs.br [Pontificia Universidade Catolica do Rio Grande do Sul (PUCRS), Porto Alegre, RS (Brazil)

    2013-08-15

    In shielding calculation of radiological facilities, several parameters are required, such as occupancy, use factor, number of patients, source-barrier distance, area type (controlled and uncontrolled), radiation (primary or secondary) and material used in the barrier. The shielding design optimization requires a review of several options about the physical facility design and, mainly, the achievement of the best cost-benefit relationship for the shielding material. To facilitate the development of this kind of design, a program to calculate the shielding in diagnostic radiology was implemented, based on data and limits established by National Council on Radiation Protection and Measurements (NCRP) 147 and SVS-MS 453/98. The program was developed in C⌗ language, and presents a graphical interface for user data input and reporting capabilities. The module initially implemented, called SHIELD 1.0, refers to calculating barriers for conventional X-ray rooms. The program validation was performed by the comparison with the results of examples of shielding calculations presented in NCRP 147.

  17. Shielding experiments for accelerator facilities

    Energy Technology Data Exchange (ETDEWEB)

    Nakashima, Hiroshi; Tanaka, Susumu; Sakamoto, Yukio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment] [and others

    2000-06-01

    A series of shielding experiments was carried out by using AVF cyclotron accelerator of TIARA at JAERI in order to validate shielding design methods for accelerator facilities in intermediate energy region. In this paper neutron transmission experiment through thick shields and radiation streaming experiment through a labyrinth are reported. (author)

  18. Shielding experiments for accelerator facilities

    International Nuclear Information System (INIS)

    Nakashima, Hiroshi; Tanaka, Susumu; Sakamoto, Yukio

    2000-01-01

    A series of shielding experiments was carried out by using AVF cyclotron accelerator of TIARA at JAERI in order to validate shielding design methods for accelerator facilities in intermediate energy region. In this paper neutron transmission experiment through thick shields and radiation streaming experiment through a labyrinth are reported. (author)

  19. Shielding Design and Radiation Shielding Evaluation for LSDS System Facility

    International Nuclear Information System (INIS)

    Kim, Younggook; Kim, Jeongdong; Lee, Yongdeok

    2015-01-01

    As the system characteristics, the target in the spectrometer emits approximately 1012 neutrons/s. To efficiently shield the neutron, the shielding door designs are proposed for the LSDS system through a comparison of the direct shield and maze designs. Hence, to guarantee the radiation safety for the facility, the door design is a compulsory course of the development of the LSDS system. To improve the shielding rates, 250x250 covering structure was added as a subsidiary around the spectrometer. In this study, the evaluations of the suggested shielding designs were conducted using MCNP code. The suggested door design and covering structures can shield the neutron efficiently, thus all evaluations of all conditions are satisfied within the public dose limits. From the Monte Carlo code simulation, Resin(Indoor type) and Tungsten(Outdoor type) were selected as the shielding door materials. From a comparative evaluation of the door thickness, In and Out door thickness was selected 50 cm

  20. Shielding assessment for the proposed HRIBF upgrade to the National ISOL Facility

    International Nuclear Information System (INIS)

    Slater, C.O.; Olsen, D.K.; Johnson, J.O.; Lillie, R.A.; Gabriel, T.A.

    1997-04-01

    An upgrade of the existing ORNL Holifield Radioactive Ion Beam Facility (HRIBF) to the National Radioactive Ion Beam Isotope Separator On Line (RIB ISOL) Facility is being proposed. Part of the upgrade involves increasing the source proton energy and current, resulting in more intense, higher energy radiation. Shielding requirements for the proposed upgrade to the HRIBF have been assessed with respect to weight, space, and dose-rate constraints. Shielding assessments were made for operating, shutdown, and accident conditions. The results indicate reasonable shielding solutions for the target room except for the marginal dose rate on the roof. Shielding requirements in the target room were greatly reduced by decisions to move the target to a more interior room and to direct the proton beam downward into the target. A slightly more difficult shielding problem arises for proton beam extraction losses from the cyclotron. Here, the assumed isotropic beam losses (hence, neutron emissions) mean higher roof dose rates than those over the target room unless substantial localized shielding is placed over the cyclotron. Shutdown dose rates were found to present no problems. While dose rates through the sides of the facility during accident conditions will probably satisfy the accident dose-rate constraints, dose rates above the roof will be well above the constraints unless a solution is devised to shield the locations where beam losses are likely to occur. Ground activation analysis was postponed for this study

  1. Studies of the Room-Temperature Multiferroic Pb(Fe0.5Ta0.5)0.4(Zr0.53Ti0.47)0.6O3: Resonant Ultrasound Spectroscopy, Dielectric, and Magnetic Phenomena

    Science.gov (United States)

    Schiemer, J; Carpenter, M A; Evans, D M; Gregg, J M; Schilling, A; Arredondo, M; Alexe, M; Sanchez, D; Ortega, N; Katiyar, R S; Echizen, M; Colliver, E; Dutton, S; Scott, J F

    2014-01-01

    Recently, lead iron tantalate/lead zirconium titanate (PZTFT) was demonstrated to possess large, but unreliable, magnetoelectric coupling at room temperature. Such large coupling would be desirable for device applications but reproducibility would also be critical. To better understand the coupling, the properties of all 3 ferroic order parameters, elastic, electric, and magnetic, believed to be present in the material across a range of temperatures, are investigated. In high temperature elastic data, an anomaly is observed at the orthorhombic mm2 to tetragonal 4mm transition, Tot = 475 K, and a softening trend is observed as the temperature is increased toward 1300 K, where the material is known to become cubic. Thermal degradation makes it impossible to measure elastic behavior up to this temperature, however. In the low temperature region, there are elastic anomalies near ≈40 K and in the range 160–245 K. The former is interpreted as being due to a magnetic ordering transition and the latter is interpreted as a hysteretic regime of mixed rhombohedral and orthorhombic structures. Electrical and magnetic data collected below room temperature show anomalies at remarkably similar temperature ranges to the elastic data. These observations are used to suggest that the three order parameters in PZTFT are strongly coupled. PMID:25844085

  2. RKKY coupling in the gadolinium with shielded exchange interaction

    International Nuclear Information System (INIS)

    Aveline, A.

    1973-01-01

    The model of magnetic interation by indirect exchange mechanism (RKKY) is studied. The shielding effect is estimated and exchange integral J(K vector, K' vector) and magnetic interaction energy Jmn(r) analysis is made. The magnetic interaction energy is determinated in two approximations and compared to the Ruderman-Kittel formula. The free electrons model, to conduction electrons, and 4f wave functions, to localized electrons were utilized [pt

  3. External dosimetry sources and shielding

    International Nuclear Information System (INIS)

    Calisto, Washington

    1994-01-01

    A definition of external dosimetry r external sources dosimetry,physical and mathematical treatment of the interaction of gamma radiation with a minimal area in that direction. Concept of attenuation coefficient, cumulated effect by polyenergetic sources, exposition rate, units, cumulated dose,shielding, foton shielding, depth calculation, materials used for shielding.Beta shielding, consideration of range and maximum β energy , low stopping radiation by use of low Z shielding. Tables for β energy of β emitters, I (tau) factor, energy-range curves for β emitters in aqueous media, gamma attenuation factors for U, W and Pb. Y factor for bone tissue,muscle and air, build-up factors

  4. Radiation shielding calculation using MCNP

    International Nuclear Information System (INIS)

    Masukawa, Fumihiro

    2001-01-01

    To verify the Monte Carlo code MCNP4A as a tool to generate the reference data in the shielding designs and the safety evaluations, various shielding benchmark experiments were analyzed using this code. These experiments were categorized in three types of the shielding subjects; bulk shielding, streaming, and skyshine. For the variance reduction technique, which is indispensable to get meaningful results with the Monte Carlo shielding calculation, we mainly used the weight window, the energy dependent Russian roulette and spitting. As a whole, our analyses performed enough small statistical errors and showed good agreements with these experiments. (author)

  5. Room temperature ferromagnetic and photoluminescence ...

    Indian Academy of Sciences (India)

    32

    electrode, photo electronic devices, photo sensors, liquid crystal displays, electrochromic windows, solar panels and transparent coatings for solar-energy heat mirrors [11-13]. Here we report on magnetic properties of ITO nanoparticles at room temperature and at 100 K. 2. Experimental. The In1.9Sn0.1O3 powder samples ...

  6. Synthesis and room-temperature ferromagnetic properties of single-crystalline Co-doped SnO2 nanocrystals via a high magnetic field

    International Nuclear Information System (INIS)

    Xu Yongbin; Tang Yongjun; Li Chuanjun; Cao Guanghui; Ren Weili; Xu Hui; Ren Zhongming

    2009-01-01

    The magnetic field-assisted approach has been used in the synthesis of Co-doped SnO 2 diluted magnetic semiconductor nanocrystals. By annealing under the condition with or without magnetic field, 1D growth of the nanostructures can be induced, and the magnetic properties of the obtained nanocrystals are improved. Various techniques such as X-ray diffraction (XRD), transmission electron microscope (TEM), UV-visible spectrometry (UV-vis), Raman spectrometry and vibrating sample magnetometer (VSM) have been used to characterize the obtained products. The results show that the magnetic field holds important effects on the crystal growth of the Co-doped SnO 2 nanostructures, and improvement of magnetic properties. The intrinsic reasons are discussed.

  7. Shielding benchmark test

    International Nuclear Information System (INIS)

    Kawai, Masayoshi

    1984-01-01

    Iron data in JENDL-2 have been tested by analyzing shielding benchmark experiments for neutron transmission through iron block performed at KFK using CF-252 neutron source and at ORNL using collimated neutron beam from reactor. The analyses are made by a shielding analysis code system RADHEAT-V4 developed at JAERI. The calculated results are compared with the measured data. As for the KFK experiments, the C/E values are about 1.1. For the ORNL experiments, the calculated values agree with the measured data within an accuracy of 33% for the off-center geometry. The d-t neutron transmission measurements through carbon sphere made at LLNL are also analyzed preliminarily by using the revised JENDL data for fusion neutronics calculation. (author)

  8. Neutron shielding material

    International Nuclear Information System (INIS)

    Suzuki, Shigenori; Iimori, Hiroshi; Kobori, Junzo.

    1980-01-01

    Purpose: To provide a neutron shielding material which incorporates preferable shielding capacity, heat resistance, fire resistance and workability by employing a mixture of thermosetting resin, polyethylene and aluminium hydroxide in special range ratio and curing it. Constitution: A mixture containing 20 to 60% by weight of thermosetting resin having preferable heat resistance, 10 to 40% by weight of polyethylene powder having high hydrogen atom density and 1000 to 60000 of molecular weight, and 15 to 55% by weight of Al(OH) 3 for imparting fire resistance and self-fire extinguishing property thereto is cured. At this time approx. 0.5 to 5% of curing catalyst of the thermosetting resin is contained in 100 parts by weight of the mixture. (Sekiya, K.)

  9. Radiation shielding wall structure

    International Nuclear Information System (INIS)

    Nishimura, Yoshitaka; Oka, Shinji; Kan, Toshihiko; Misato, Takeshi.

    1990-01-01

    A space between a pair of vertical steel plates laterally disposed in parallel at an optional distance has a structure of a plurality of vertically extending tranks partitioned laterally by vertically placed steel plates. Then, cements are grouted to the tranks. Strip-like steel plates each having a thickness greater than the gap between the each of the vertically placed steel plates and the cement are bonded each at the surface for each of the vertically placed steel plates opposing to the cements. A protrusion of a strip width having radiation shielding performance substantially identical with that by the thickness of the cement is disposed in the strip-like steel plates. With such a constitution, a safety radiation shielding wall structure with no worry of radiation intrusion to gaps, if formed, between the steel plates and the grouted cements due to shrinkage of the cements. (I.N.)

  10. Radiation shielding material

    International Nuclear Information System (INIS)

    Kawakubo, Takamasa; Yamada, Fumiyuki; Nakazato, Kenjiro.

    1976-01-01

    Purpose: To provide a material, which is used for printing a samples name and date on an X-ray photographic film at the same time an X-ray radiography. Constitution: A radiation shielding material of a large mass absorption coefficient such as lead oxide, barium oxide, barium sulfate, etc. is added to a solution of a radiation permeable substance capable of imparting cold plastic fluidity (such as microcrystalline wax, paraffin, low molecular polyethylene, polyvinyl chloride, etc.). The resultant system is agitated and then cooled, and thereafter it is press fitted to or bonded to a base in the form of a film of a predetermined thickness. This radiation shielding layer is scraped off by using a writing tool to enter information to be printed in a photographic film, and then it is laid over the film and exposed to X-radiation to thereby print the information on the film. (Seki, T.)

  11. Multilayer radiation shield

    Science.gov (United States)

    Urbahn, John Arthur; Laskaris, Evangelos Trifon

    2009-06-16

    A power generation system including: a generator including a rotor including a superconductive rotor coil coupled to a rotatable shaft; a first prime mover drivingly coupled to the rotatable shaft; and a thermal radiation shield, partially surrounding the rotor coil, including at least a first sheet and a second sheet spaced apart from the first sheet by centripetal force produced by the rotatable shaft. A thermal radiation shield for a generator including a rotor including a super-conductive rotor coil including: a first sheet having at least one surface formed from a low emissivity material; and at least one additional sheet having at least one surface formed from a low emissivity material spaced apart from the first sheet by centripetal force produced by the rotatable shaft, wherein each successive sheet is an incrementally greater circumferential arc length and wherein the centripetal force shapes the sheets into a substantially catenary shape.

  12. Light shielding apparatus

    Science.gov (United States)

    Miller, Richard Dean; Thom, Robert Anthony

    2017-10-10

    A light shielding apparatus for blocking light from reaching an electronic device, the light shielding apparatus including left and right support assemblies, a cross member, and an opaque shroud. The support assemblies each include primary support structure, a mounting element for removably connecting the apparatus to the electronic device, and a support member depending from the primary support structure for retaining the apparatus in an upright orientation. The cross member couples the left and right support assemblies together and spaces them apart according to the size and shape of the electronic device. The shroud may be removably and adjustably connectable to the left and right support assemblies and configured to take a cylindrical dome shape so as to form a central space covered from above. The opaque shroud prevents light from entering the central space and contacting sensitive elements of the electronic device.

  13. Shielding container for radioactive isotopes

    International Nuclear Information System (INIS)

    Sumi, Tetsuo; Tosa, Masayoshi; Hatogai, Tatsuaki.

    1975-01-01

    Object: To effect opening and closing bidirectional radiation used particularly for a gamma densimeter or the like by one operation. Structure: This device comprises a rotatable shielding body for receiving radioactive isotope in the central portion thereof and having at least two radiation openings through which radiation is taken out of the isotope, and a shielding container having openings corresponding to the first mentioned radiation openings, respectively. The radioactive isotope is secured to a rotational shaft of the shielding body, and the shielding body is rotated to register the openings of the shielding container with the openings of the shielding body or to shield the openings, thereby effecting radiation and cut off of gamma ray in the bidirection by one operation. (Kamimura, M.)

  14. Primary shield displacement and bowing

    International Nuclear Information System (INIS)

    Scott, K.V.

    1978-01-01

    The reactor primary shield is constructed of high density concrete and surrounds the reactor core. The inlet, outlet and side primary shields were constructed in-place using 2.54 cm (1 in) thick steel plates as the forms. The plates remained as an integral part of the shields. The elongation of the pressure tubes due to thermal expansion and pressurization is not moving through the inlet nozzle hardware as designed but is accommodated by outward displacement and bowing of the inlet and outlet shields. Excessive distortion of the shields may result in gas seal failures, intolerable helium gas leaks, increased argon-41 emissions, and shield cooling tube failures. The shield surveillance and testing results are presented

  15. Shielding calculations using FLUKA

    International Nuclear Information System (INIS)

    Yamaguchi, Chiri; Tesch, K.; Dinter, H.

    1988-06-01

    The dose equivalent on the surface of concrete shielding has been calculated using the Monte Carlo code FLUKA86 for incident proton energies from 10 to 800 GeV. The results have been compared with some simple equations. The value of the angular dependent parameter in Moyer's equation has been calculated from the locations where the values of the maximum dose equivalent occur. (author)

  16. How the Performance of a Superconducting Magnet is affected by the Connection between a small cooler and the Magnet

    International Nuclear Information System (INIS)

    Green, Michael A.

    2005-01-01

    As low temperature cryocoolers become more frequently used to cool superconducting magnets, it becomes increasingly apparent that the connection between the cooler and the magnet has an effect on the design and performance of the magnet. In general, the use of small coolers can be considered in two different temperature ranges; (1) from 3.8 to 4.8 K for magnet fabricated with LTS conductor and (2) from 18 to 35 K for magnets fabricated using HTS conductor. In general, both temperature ranges call for the use of a two-stage cooler. The best method for connecting a cooler to the magnet depends on a number of factors. The factors include: (1) whether the cooler must be used to cool down the magnet from room temperature, (2) whether the magnet must have one or more reservoirs of liquid cryogen to keep the magnet cold during a loss of cooling, and (3) constraints on the distance from the cooler cold heads and the magnet and its shield. Two methods for connecting low temperature coolers to superconducting magnets have been studied. The first method uses a cold strap to connect the cold heads directly to the loads. This method is commonly used for cryogen-free magnets. The second method uses a thermal siphon and liquid cryogens to make the connection between the load being cooled and the cold head. The two methods of transferring heat from the magnet to the cooler low temperature cold head are compared for the two temperature ranges given above

  17. Shielding Benchmark Computational Analysis

    International Nuclear Information System (INIS)

    Hunter, H.T.; Slater, C.O.; Holland, L.B.; Tracz, G.; Marshall, W.J.; Parsons, J.L.

    2000-01-01

    Over the past several decades, nuclear science has relied on experimental research to verify and validate information about shielding nuclear radiation for a variety of applications. These benchmarks are compared with results from computer code models and are useful for the development of more accurate cross-section libraries, computer code development of radiation transport modeling, and building accurate tests for miniature shielding mockups of new nuclear facilities. When documenting measurements, one must describe many parts of the experimental results to allow a complete computational analysis. Both old and new benchmark experiments, by any definition, must provide a sound basis for modeling more complex geometries required for quality assurance and cost savings in nuclear project development. Benchmarks may involve one or many materials and thicknesses, types of sources, and measurement techniques. In this paper the benchmark experiments of varying complexity are chosen to study the transport properties of some popular materials and thicknesses. These were analyzed using three-dimensional (3-D) models and continuous energy libraries of MCNP4B2, a Monte Carlo code developed at Los Alamos National Laboratory, New Mexico. A shielding benchmark library provided the experimental data and allowed a wide range of choices for source, geometry, and measurement data. The experimental data had often been used in previous analyses by reputable groups such as the Cross Section Evaluation Working Group (CSEWG) and the Organization for Economic Cooperation and Development/Nuclear Energy Agency Nuclear Science Committee (OECD/NEANSC)

  18. Muon shielding for PEP

    International Nuclear Information System (INIS)

    Jenkins, T.M.; Thomas, R.H.

    1974-01-01

    The first stage of construction of PEP will consist of electron and positron storage rings. At a later date a 200 GeV proton storage ring may be added. It is judicious therefore, to ensure that the first and second phases of construction are compatible with each other. One of several factors determining the elevation at which the storage rings will be constructed is the necessity to provide adequate radiation shielding. The overhead shielding of PEP is determined by the reproduction of neutrons in the hadron cascade generated by primary protons lost from the storage ring. The minimum overburden planned for PEP is 5.5 meters of earth (1100 gm cm/sup /minus/2/). To obtain a rough estimate of the magnitude of the muon radiation problem this note presents some preliminary calculations. Their purpose is intended merely to show that the presently proposed design for PEP will present no major shielding problems should the protons storage ring be installed. More detailed calculations will be made using muon yield computer codes developed at CERN and NAL and muon transport codes developed at SLAC, when details of the proton storage ring become settled. 9 refs., 4 figs

  19. Shielding calculations for NET

    International Nuclear Information System (INIS)

    Verschuur, K.A.; Hogenbirk, A.

    1991-05-01

    In the European Fusion Technology Programme there is only a small activity on research and development for fusion neutronics. Never-the-less, looking further than blanket design now, as ECN is getting involved in design of radiation shields for the coils and biological shields, it becomes apparent that fusion neutronics as a whole still needs substantial development. Existing exact codes for calculation of complex geometries like MCNP and DORT/TORT are put over the limits of their numerical capabilities, whilst approximate codes for complex geometries like FURNACE and MERCURE4 are put over the limits of their modelling capabilities. The main objective of this study is just to find out how far we can get with existing codes in obtaining reliable values for the radiation levels inside and outside the cryostat/shield during operation and after shut-down. Starting with a 1D torus model for preliminary parametric studies, more dimensional approximation of the torus or parts of it including the main heterogeneities should follow. Regular contacts with the NET-Team are kept, to be aware of main changes in NET design that might affect our calculation models. Work on the contract started 1 July 1990. The technical description of the contract is given. (author). 14 refs.; 4 figs.; 1 tab

  20. Magnets

    International Nuclear Information System (INIS)

    Young, I.R.

    1984-01-01

    A magnet pole piece for an NMR imaging magnet is made of a plurality of magnetic wires with one end of each wire held in a non-magnetic spacer, the other ends of the wires being brought to a pinch, and connected to a magnetic core. The wires may be embedded in a synthetic resin and the magnetisation and uniformity thereof can be varied by adjusting the density of the wires at the spacer which forms the pole piece. (author)

  1. The AA disappearing under concrete shielding

    CERN Multimedia

    CERN PhotoLab

    1982-01-01

    When the AA started up in July 1980, the machine stood freely in its hall, providing visitors with a view through the large window in the AA Control Room. The target area, in which the high-intensity 26 GeV/c proton beam from the PS hit the production target, was heavily shielded, not only towards the outside but also towards the AA-Hall. However, electrons and pions emanating from the target with the same momentum as the antiprotons, but much more numerous, accompanied these through the injection line into the AA ring. The pions decayed with a half-time corresponding to approximately a revolution period (540 ns), whereas the electrons lost energy through synchrotron radiation and ended up on the vacuum chamber wall. Electrons and pions produced the dominant component of the radiation level in the hall and the control room. With operation times far exceeding original expectations, the AA had to be buried under concrete shielding in order to reduce the radiation level by an order of magnitude.

  2. Development of a computer code for determining the thickness of shielding used in cardiac angiography techniques

    International Nuclear Information System (INIS)

    Lava, Deise D.; Borges, Diogo da S.; Affonso, Renato R.W.; Moreira, Maria de L.; Guimaraes, Antonio C.F.

    2014-01-01

    The construction of an effective shielding against the interaction of ionizing radiation in X-ray rooms requires consideration of many variables. The methodology used for specification of a primary and secondary shielding thickness of a X-ray room considers the following factors: use factor, occupational factor, distance between the source and the wall, workload, Kerma in the air and distance between the patient and the receptor. The program built from this data, has the objective of identifying and using variables in functions obtained through linear regressions of graphics offered by NCRP Report-147 (Structural Shielding Design for Medical X-Ray Imaging Facilities) for the shielding calculation of the room walls as wall dark room and adjacent areas. With the methodology constructed a program validation is done by comparison of results with a base case provided by that report. The values of the thicknesses obtained comprise various materials such as steel, wood and concrete. Once validated an application is made in a real case of X-ray room. His visual construction is done with the help of software used in modeling of interiors and exteriors. The construction of shielding calculating program has the goal of being an easy tool for planning of X-ray rooms in order to meet the established limits by CNEN-NN-3:01 published in September 2011

  3. Flux trapping and shielding in irreversible superconductors

    International Nuclear Information System (INIS)

    Frankel, D.J.

    1978-05-01

    Flux trappings and shielding experiments were carried out on Pb, Nb, Pb-Bi, Nb-Sn, and Nb-Ti samples of various shapes. Movable Hall probes were used to measure fields near or inside the samples as a function of position and of applied field. The trapping of transverse multipole magnetic fields in tubular samples was accomplished by cooling the samples in an applied field and then smoothly reducing the applied field to zero. Transverse quadrupole and sextupole fields with gradients of over 2000 G/cm were trapped with typical fidelity to the original impressed field of a few percent. Transverse dipole fields of up to 17 kG were also trapped with similar fidelity. Shielding experiments were carried out by cooling the samples in zero field and then gradually applying an external field. Flux trapping and shielding abilities were found to be limited by two factors, the pinning strength of the material, and the susceptibility of a sample to flux jumping. The trapping and shielding behavior of flat disk samples in axial fields and thin-walled tubular samples in transverse fields was modeled. The models, which were based on the concept of the critical state, allowed a connection to be made between the pinning strength and critical current level, and the flux trapping and shielding abilities. Adiabatic and dynamic stability theories are discussed and applied to the materials tested. Good qualitative, but limited quantitative agreement was obtained between the predictions of the theoretical stability criteria and the observed flux jumping behavior

  4. Joule loss on a Faraday shield of JT-60 ICRF test antenna

    International Nuclear Information System (INIS)

    Fujii, Tsuneyuki; Saigusa, Mikio; Ikeda, Yoshitaka; Kimura, Haruyuki; Hirashima, Teruhisa; Uehara, Munenori.

    1988-01-01

    Joule loss on a Faraday shield of JT-60 ICRF test antenna with a conductive casing is investigated at the frequency range of 120 MHz. The magnetic field radiated from the antenna is measured by three-dimensionally scanning an rf probe both inside and outside the antenna casing. The magnetic field perpendicular to the Faraday shield, B x , is found to be the largest component near the Faraday shield. It consequently gives the major part of the joule loss on the Faraday shield. The temperature distribution of the Faraday shield due to joule loss is measured directly with a thermocamera. It is confirmed that the area of the high temperature rise is consistent with the peak positions of the B x field. Faraday shield resistance which is estimated from power measurements agrees with the theoretical value. (author)

  5. Working conditions of a radiodiagnostic room

    International Nuclear Information System (INIS)

    Chikirdin, Eh.G.

    1983-01-01

    The concept of ''operating load'' of an X-ray diagnostic room is explained. The concept includes the calculation of the Week's maximum exposure calculation and monitoring of stationary radiation shielding, measurements of exposure dose rate at working places. In this case the substitution of the actual repeated short-time regime of emitter operation for the calculated continuous regime is performed. The data on the ''operating load'' of X-ray diagnostic room are presented taking into account the method of X-ray investigation

  6. Radiation shielding calculation for the MOX fuel fabrication plant Melox

    International Nuclear Information System (INIS)

    Lee, Y.K.; Nimal, J.C.; Chiron, M.

    1994-01-01

    Radiation shielding calculation is an important engineering work in the design of the MOX fuel fabrication plant MELOX. Due to the recycle of plutonium and uranium from UO2 spent fuel reprocessing and the large capacity of production (120t HM/yr.), the shielding design requires more attention in this LWR fuel plant. In MELOX, besides several temporary storage facilities of massive fissile material, about one thousand radioactive sources with different geometries, forms, densities, quantities and Pu concentrations, are distributed through different workshops from the PuO 2 powder reception unit to the fuel assembly packing room. These sources, with or without close shield, stay temporarily in different locations, containers and glove boxes. In order to optimize the dimensions, the material and the cost of shield as well as to limit the calculation work in a reasonable engineer-hours, a calculation scheme for shielding design of MELOX is developed. This calculation scheme has been proved to be useful in consideration of the feedback from the evolutionary design and construction. The validated shielding calculations give a predictive but reliable radiation doses information. (authors). 2 figs., 10 refs

  7. Shielding from cosmic radiation for interplanetary missions Active and passive methods

    CERN Document Server

    Spillantini, P; Durante, M; Müller-Mellin, R; Reitz, G; Rossi, L; Shurshakov, V; Sorbi, M

    2007-01-01

    Shielding is arguably the main countermeasure for the exposure to cosmic radiation during interplanetary exploratory missions. However, shielding of cosmic rays, both of galactic or solar origin, is problematic, because of the high energy of the charged particles involved and the nuclear fragmentation occurring in shielding materials. Although computer codes can predict the shield performance in space, there is a lack of biological and physical measurements to benchmark the codes. An attractive alternative to passive, bulk material shielding is the use of electromagnetic fields to deflect the charged particles from the spacecraft target. Active shielding concepts based on electrostatic fields, plasma, or magnetic fields have been proposed in the past years, and should be revised based on recent technological improvements. To address these issues, the European Space Agency (ESA) established a Topical Team (TT) in 2002 including European experts in the field of space radiation shielding and superconducting magn...

  8. A contribution to shielding effectiveness analysis of shielded tents

    Directory of Open Access Journals (Sweden)

    Vranić Zoran M.

    2004-01-01

    Full Text Available An analysis of shielding effectiveness (SE of the shielded tents made of the metallised fabrics is given. First, two electromagnetic characteristic fundamental for coupling through electrically thin shield, the skin depth break frequency and the surface resistance or transfer impedance, is defined and analyzed. Then, the transfer function and the SE are analyzed regarding to the frequency range of interest to the Electromagnetic Compatibility (EMC Community.

  9. Conceptual design for the thermal shield bridges and multilayer insulation in the interconnect region for the SSC

    International Nuclear Information System (INIS)

    Baritchi, D.; Nicol, T.; Boroski, W.

    1991-01-01

    The interconnect region serves as the connection area between magnets. In order to minimize radiant heat transfer in the interconnect area, the authors used shield bridges which span the 80K and 20K shield gap between adjacent magnets. A sliding joint between bridge sections on adjacent magnets accommodates contraction during cool-down. An investigation was done to determine which attachment schemes (riveted or bolted versus welded) are better for heat transfer. Each shield bridge is covered with the same multilayer insulation scheme used throughout the body of the magnet. These shield bridges also contain pressure reliefs for each shield in the event of an internal piping failure. The reliefs are located in the upper half of the shield section in order to prevent liquid spills from impinging directly onto the vacuum vessel wall

  10. Radiation shielding quality assurance

    Science.gov (United States)

    Um, Dallsun

    For the radiation shielding quality assurance, the validity and reliability of the neutron transport code MCNP, which is now one of the most widely used radiation shielding analysis codes, were checked with lot of benchmark experiments. And also as a practical example, follows were performed in this thesis. One integral neutron transport experiment to measure the effect of neutron streaming in iron and void was performed with Dog-Legged Void Assembly in Knolls Atomic Power Laboratory in 1991. Neutron flux was measured six different places with the methane detectors and a BF-3 detector. The main purpose of the measurements was to provide benchmark against which various neutron transport calculation tools could be compared. Those data were used in verification of Monte Carlo Neutron & Photon Transport Code, MCNP, with the modeling for that. Experimental results and calculation results were compared in both ways, as the total integrated value of neutron fluxes along neutron energy range from 10 KeV to 2 MeV and as the neutron spectrum along with neutron energy range. Both results are well matched with the statistical error +/-20%. MCNP results were also compared with those of TORT, a three dimensional discrete ordinates code which was developed by Oak Ridge National Laboratory. MCNP results are superior to the TORT results at all detector places except one. This means that MCNP is proved as a very powerful tool for the analysis of neutron transport through iron & air and further it could be used as a powerful tool for the radiation shielding analysis. For one application of the analysis of variance (ANOVA) to neutron and gamma transport problems, uncertainties for the calculated values of critical K were evaluated as in the ANOVA on statistical data.

  11. Shielding of electromagnetic fields by metallic glasses with Fe and Co matrix

    International Nuclear Information System (INIS)

    Nowosielski, R.; Griner, S.

    1997-01-01

    The influence of chemical composition and magnetic and electric properties for shielding of electromagnetic fields with frequency 10-1000 kHz, by metallic glasses has been analysed. For investigation were selected two groups of metallic glasses with matrix of Fe and Co. Particularly, in there were selected metallic glasses as follows; Fe 78 Si 9 B 13 , Co 68 Fe 4 Mo 1.5 Si 13.5 B 13 , Co 69 Mo 2 Fe 4 Si 14 B 11 , Co 70.5 Fe 2.5 Mn 4 Mo 1 Si 9 B 15 . The experiments were realised for casting metallic glasses by the CMBS method in the form of strips with width 10 mm. Obtained results of shielding indicate clear for very good shielding effectiveness of one layer shields both electric and magnetic components of electromagnetic fields, although shielding of magnetic component is smaller than electric. (author). 17 refs, 5 figs, 9 tabs

  12. Neutronic reactor thermal shield

    International Nuclear Information System (INIS)

    Lowe, P.E.

    1976-01-01

    A shield for a nuclear reactor includes at least two layers of alternating wide and narrow rectangular blocks so arranged that the spaces between blocks in adjacent layers are out of registry, each block having an opening therein equally spaced from the sides of the blocks and nearer the top of the block than the bottom, the distance from the top of the block to the opening in one layer being different from this distance in adjacent layers, openings in blocks in adjacent layers being in registry. 1 claim, 7 drawing figures

  13. A shield against distraction

    OpenAIRE

    Halin, N.; Marsh, J.E.; Hellman, A.; Hellstrom, I.; Sörqvist, Patrik

    2014-01-01

    In this paper, we apply the basic idea of a trade-off between the level of concentration and distractibility to test whether a manipulation of task difficulty can shield against distraction. Participants read, either in quiet or with a speech noise background, texts that were displayed either in an easy-to-read or a hard-to-read font. Background speech impaired prose recall, but only when the text was displayed in the easy-to-read font. Most importantly, recall was better in the background sp...

  14. Room temperature ferromagnetism with large magnetic moment at low field in rare-earth-doped BiFeO₃ thin films.

    Science.gov (United States)

    Kim, Tae-Young; Hong, Nguyen Hoa; Sugawara, T; Raghavender, A T; Kurisu, M

    2013-05-22

    Thin films of rare earth (RE)-doped BiFeO3 (where RE=Sm, Ho, Pr and Nd) were grown on LaAlO3 substrates by using the pulsed laser deposition technique. All the films show a single phase of rhombohedral structure with space group R3c. The saturated magnetization in the Ho- and Sm-doped films is much larger than the values reported in the literature, and is observed at quite a low field of 0.2 T. For Ho and Sm doping, the magnetization increases as the film becomes thinner, suggesting that the observed magnetism is mostly due to a surface effect. In the case of Nd doping, even though the thin film has a large magnetic moment, the mechanism seems to be different.

  15. Measuring space radiation shielding effectiveness

    OpenAIRE

    Bahadori Amir; Semones Edward; Ewert Michael; Broyan James; Walker Steven

    2017-01-01

    Passive radiation shielding is one strategy to mitigate the problem of space radiation exposure. While space vehicles are constructed largely of aluminum, polyethylene has been demonstrated to have superior shielding characteristics for both galactic cosmic rays and solar particle events due to the high hydrogen content. A method to calculate the shielding effectiveness of a material relative to reference material from Bragg peak measurements performed using energetic heavy charged particles ...

  16. Selective shielding device for scintiphotography

    International Nuclear Information System (INIS)

    Harper, J.W.; Kay, T.D.

    1976-01-01

    A selective shielding device to be used in combination with a scintillation camera is described. The shielding device is a substantially oval-shaped configuration removably secured to the scintillation camera. As a result of this combination scanning of preselected areas of a patient can be rapidly and accurately performed without the requirement of mounting any type of shielding paraphernalia on the patient. 1 claim, 2 drawing figures

  17. Tax Shield, Insolvenz und Zinsschranke

    OpenAIRE

    Arnold, Sven; Lahmann, Alexander; Schwetzler, Bernhard

    2010-01-01

    Dieser Beitrag analysiert den Wertbeitrag fremdfinanzierungsbedingter Steuervorteile (Tax Shield) unter realistischen Bedingungen (keine Negativsteuer; mögliche Insolvenz) für unterschiedliche Finanzierungspolitiken. Zusätzlich wird der Effekt der sogenannten Zinsschranke auf den Wert des Tax Shield ermittelt. Die Bewertung des Tax Shield mit und ohne Zinsschranke findet im einperiodigen Fall auf der Basis von Optionspreismodellen und im mehrperiodigen Fall auf der Basis von Monte Carlo Simul...

  18. Room temperature magnetic ordering, enhanced magnetization and exchange bias of GdMnO{sub 3} nanoparticles in (GdMnO{sub 3}){sub 0.70}(CoFe{sub 2}O{sub 4}){sub 0.30}

    Energy Technology Data Exchange (ETDEWEB)

    Mitra, A.; Mahapatra, A.S.; Mallick, A.; Chakrabarti, P.K., E-mail: pabitra_c@hotmail.com

    2017-02-15

    Nanoparticles of GdMnO{sub 3} (GMO) are prepared by sol-gel method. To enhance the magnetic property and also to obtain the magnetic ordering at room temperature (RT), nanoparticles of GMO are incorporated in the matrix of CoFe{sub 2}O{sub 4} (CFO). Desired crystallographic phases of CFO, GMO and GMO-CFO are confirmed by analyzing X-ray diffractrograms (XRD) using Rietveld method. The average size of nanoparticles and their distribution, crystallographic phase, nanocrystallinity etc. are studied by high-resolution transmission electron microscope (HRTEM). Magnetic hysteresis loops (M-H) of GMO-CFO under zero field cooled (ZFC) and field cooled (FC) conditions are observed at different temperatures down to 5 K. Magnetization vs. temperature (M-T) under ZFC and FC conditions are also recorded. Interestingly, exchange bias (EB) is found at low temperature which suggests the encapsulation of the ferromagnetic (FM) nanoparticles of GMO by the ferrimagnetic nanoparticles of CFO below ~100 K. Enhanced magnetization, EB effect and RT magnetic ordering of GMO-CFO would be interesting for both theoretical and experimental investigations. - Highlights: • Nanoparticles of GdMnO{sub 3} are incorporated in the matrix of CoFe{sub 2}O{sub 4}. • RT magnetic ordering of GMO nanoparticles in GMO-CFO is observed. • Magnetic property of GMO-CFO is highly enhanced compared to GMO. • Exchange bias is found in GMO-CFO at low temperature.

  19. SHIELD verification and validation report

    International Nuclear Information System (INIS)

    Boman, C.

    1992-02-01

    This document outlines the verification and validation effort for the SHIELD, SHLDED, GEDIT, GENPRT, FIPROD, FPCALC, and PROCES modules of the SHIELD system code. Along with its predecessors, SHIELD has been in use at the Savannah River Site (SRS) for more than ten years. During this time the code has been extensively tested and a variety of validation documents have been issued. The primary function of this report is to specify the features and capabilities for which SHIELD is to be considered validated, and to reference the documents that establish the validation

  20. Multifunctional Hot Structure Heat Shield

    Data.gov (United States)

    National Aeronautics and Space Administration — This project is performing preliminary development of a Multifunctional Hot Structure (HOST) heat shield for planetary entry. Results of this development will...

  1. Radiation shield for nuclear reactors

    International Nuclear Information System (INIS)

    Weissenfluh, J.A.

    1978-01-01

    A shield for use with nuclear reactor systems to attenuate radiation resulting from reactor operation is described. The shield comprises a container preferably of a thin, flexible or elastic material, which may be in the form of a bag, a mattress, a toroidal segment or toroid or the like filled with radiation attenuating liuid. Means are provided in the container for filling and draining the container in place. Due to its flexibility, the shield readily conforms to irregularities in surfaces with which it may be in contact in a shielding position

  2. New Toroid shielding design

    CERN Multimedia

    Hedberg V

    On the 15th of June 2001 the EB approved a new conceptual design for the toroid shield. In the old design, shown in the left part of the figure above, the moderator part of the shielding (JTV) was situated both in the warm and cold areas of the forward toroid. It consisted both of rings of polyethylene and hundreds of blocks of polyethylene (or an epoxy resin) inside the toroid vacuum vessel. In the new design, shown to the right in the figure above, only the rings remain inside the toroid. To compensate for the loss of moderator in the toroid, the copper plug (JTT) has been reduced in radius so that a layer of borated polyethylene can be placed around it (see figure below). The new design gives significant cost-savings and is easier to produce in the tight time schedule of the forward toroid. Since the amount of copper is reduced the weight that has to be carried by the toroid is also reduced. Outgassing into the toroid vacuum was a potential problem in the old design and this is now avoided. The main ...

  3. SHIELDS Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Jordanova, Vania Koleva [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-10-03

    Predicting variations in the near-Earth space environment that can lead to spacecraft damage and failure, i.e. “space weather”, remains a big space physics challenge. A new capability was developed at Los Alamos National Laboratory (LANL) to understand, model, and predict Space Hazards Induced near Earth by Large Dynamic Storms, the SHIELDS framework. This framework simulates the dynamics of the Surface Charging Environment (SCE), the hot (keV) electrons representing the source and seed populations for the radiation belts, on both macro- and micro-scale. In addition to using physics-based models (like RAM-SCB, BATS-R-US, and iPIC3D), new data assimilation techniques employing data from LANL instruments on the Van Allen Probes and geosynchronous satellites were developed. An order of magnitude improvement in the accuracy in the simulation of the spacecraft surface charging environment was thus obtained. SHIELDS also includes a post-processing tool designed to calculate the surface charging for specific spacecraft geometry using the Curvilinear Particle-In-Cell (CPIC) code and to evaluate anomalies' relation to SCE dynamics. Such diagnostics is critically important when performing forensic analyses of space-system failures.

  4. Radiation shielding analysis

    International Nuclear Information System (INIS)

    Moon, S.H.; Ha, C.W.; Kwon, S.K.; Lee, J.K.; Choi, H.S.

    1982-01-01

    The theoretical bases of radiation streaming analysis in power reactors, such as ducts or reactor cavity, have been investigated. Discrete ordinates-Monte Carlo or Monte Carlo-Monte Carlo coupling techniques are suggested for the streaming analysis of ducts or reactor cavity. Single albedo scattering approximation code (SINALB) has been developed for simple and quick estimation of gamma-ray ceiling scattering, where the ceiling is assumed to be semi-infinite medium. This code has been employed to calculate the gamma-ray ceiling scattering effects in the laboratory containing a Co-60 source. The SINALB is applicable to gamma-ray scattering, only where the ceiling is thicker than Σsup(-1) and the height is at least twice higher than the shield wall. This code can be used for the purpose of preliminary radiation shield design. The MORSE code has been improved to analyze the gamma-ray scattering problem with on approximation method in respect to the random walk and estimation processes. This improved MORSE code has been employed to the gamma-ray ceiling scattering problem. The results of the improved MORSE calculation are in good agreement with the SINALB and standard MORSE. (Author)

  5. X-ray face mask and chest shield device

    International Nuclear Information System (INIS)

    Moti, S.

    1981-01-01

    A protective face mask is designed to shield an x-ray technician or machine operator primarily from random secondary or scatter x-rays deflected towards his face, head and neck by the table, walls, equipment and other reflecting elements in an x-ray room or chamber. The face mask and chest shield device can be mounted on a patient's shoulders in reverse attitude to protect the back of a patient's head and neck from the x-ray beam. The face mask is relatively or substantially transparent and contains lead in combination with a plastic ionomer or comonomer, which to a degree absorbs or resists penetration of the random deflected secondary or scatter x-rays or the x-ray beam through the mask. The face mask is removably attachable to the chest shield for easy application of the device to and support upon the shoulders of the technician or the patient. (author)

  6. Room-temperature ferromagnetic transitions and the temperature dependence of magnetic behaviors in FeCoNiCr-based high-entropy alloys

    Science.gov (United States)

    Na, Suok-Min; Yoo, Jin-Hyeong; Lambert, Paul K.; Jones, Nicholas J.

    2018-05-01

    High-entropy alloys (HEAs) containing multiple principle alloying elements exhibit unique properties so they are currently receiving great attention for developing innovative alloy designs. In FeCoNi-based HEAs, magnetic behaviors strongly depend on the addition of alloying elements, usually accompanied by structural changes. In this work, the effect of non-magnetic components on the ferromagnetic transition and magnetic behaviors in equiatomic FeCoNiCrX (X=Al, Ga, Mn and Sn) HEAs was investigated. Alloy ingots of nominal compositions of HEAs were prepared by arc melting and the button ingots were cut into discs for magnetic measurements as functions of magnetic field and temperature. The HEAs of FeCoNiCrMn and FeCoNiCrSn show typical paramagnetic behaviors, composed of solid solution FCC matrix, while the additions of Ga and Al in FeCoNiCr exhibit ferromagnetic behaviors, along with the coexistence of FCC and BCC phases due to spinodal decomposition. The partial phase transition in both HEAs with the additions of Ga and Al would enhance ferromagnetic properties due to the addition of the BCC phase. The saturation magnetization for the base alloy FeCoNiCr is 0.5 emu/g at the applied field of 20 kOe (TC = 104 K). For the HEAs of FeCoNiCrGa and FeCoNiCrAl, the saturation magnetization significantly increased to 38 emu/g (TC = 703 K) and 25 emu/g (TC = 277 K), respectively. To evaluate the possibility of solid solution FCC and BCC phases in FeCoNiCr-type HEAs, we introduced a parameter of valence electron concentration (VEC). The proposed rule for solid solution formation by the VEC was matched with FeCoNiCr-type HEAs.

  7. A novel recipe to improve the magnetic properties of Mn doped CeO{sub 2} as a room temperature ferromagnetic diluted metal oxide

    Energy Technology Data Exchange (ETDEWEB)

    Al-Agel, Faisal A., E-mail: fagel2@yahoo.com [King Abdulaziz University, Faculty of Science, Department of Physics, Jeddah (Saudi Arabia); Al-Arfaj, Esam [Umm Alqura University, Department of Physics, Makkah (Saudi Arabia); Al-Ghamdi, Ahmed A. [King Abdulaziz University, Faculty of Science, Department of Physics, Jeddah (Saudi Arabia); Losovyj, Yaroslav [Indiana University, Department of Chemistry, Bloomington, IN 47405 (United States); Bronstein, Lyudmila M. [King Abdulaziz University, Faculty of Science, Department of Physics, Jeddah (Saudi Arabia); Indiana University, Department of Chemistry, Bloomington, IN 47405 (United States); Mahmoud, Waleed E. [King Abdulaziz University, Faculty of Science, Department of Physics, Jeddah (Saudi Arabia); Suez Canal University, Faculty of Science, Department of Physics, Ismailia (Egypt)

    2014-06-01

    Mn doped ceria nanocrystals have been prepared using hexamethylene triperoxide diamine assisted solvothermal technique for the first time. The impact of this novel recipe on the structure, magnetic and spectroscopic behaviors was discussed. The doped oxides were studied using X-ray powder diffraction (XRD), transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), and magnetic measurements. The XRD analysis revealed that all the powders can be indexed to the pure cubic ceria, revealing complete solubility of Mn atoms in the ceria crystal structure with an interstitial substitution of Mn in the Ce sites. At the percolation concentration x=0.08 (Mn{sub 0.08}Ce{sub 0.92}O{sub 2}), the Mn doped cerium oxide displays a very high saturation magnetization of 4.48 emu/g and coercivity of 175.5 Oe. The enhanced magnetic properties are attributed to the formation of the complex between the Mn ion and an oxygen vacancy which is confirmed by the XPS analysis. According to the obtained results, one can say that this novel synthetic recipe increased the solubility of Mn ions into the CeO{sub 2} crystal structure and improved the magnetization by more than 37 times compared to the Mn doped CeO{sub 2} prepared by conventional methods. - Highlights: • Mn doped ceria was prepared by HMTD assisted solvothermal technique. • Complete solubility of Mn atoms in the ceria structure was achieved up to 10 at%. • High saturation magnetization of 4.48 emu/g was achieved at 8 at%. • The magnetization was improved by more than 37 times compared to conventional methods.

  8. AA, radiation shielding curtain along the target area

    CERN Multimedia

    CERN PhotoLab

    1980-01-01

    At the far left is the beam tube for the high-intensity proton beam from the 26 GeV PS. The tube ends in a thin window and the proton beam continues in air through a hole in the shielding blocks (see also 8010308), behind which the target (see 7905091, 7905094)was located. After the target followed the magnetic horn, focusing the antiprotons, and the first part of the injection line with a proton dump. The antiprotons, deflected by a magnet, left the target area through another shielding wall, to make their way to the AA ring. Laterally, this sequence of components was shielded with movable, suspended, concrete blocks: the "curtain". Balasz Szeless, who had constructed it, is standing at its side.

  9. Revised neutral gas shielding model for pellet ablation - combined neutral and plasma shielding

    International Nuclear Information System (INIS)

    Houlberg, W.A.; Schuresko, D.D.; Attenberger, S.E.

    1986-01-01

    The ablation and penetration of pellets in early ORMAK and ISX-A experiments were reliably predicted by the neutral gas shielding model of Milora and Foster. These experiments demonstrated that the principle components of the model - a self-generated shield which reduces the heat flux at the plasma surface - were correct. In more recent experiments with higher temperature plasmas, this model consistently predicts greater penetration than observed in the experiments. Upgarding known limitations of the original model brings the predicted and observed penetration values into agreement. These improvements include: (1) treating the incident electrons as having distribution in energy rather than being monoenergetic; (2) including the shielding effects of cold, dense plasma extending along the magnetic field outside the neutral shield; and (3) modifying the finite plasma, self-limiting incident heat flux so that it represents a collisionless plasma limit rather than a collisional limit. Comparisons are made between the models for a selection of ISX-B Alcator-C, and TFTR shots. The net effect of the changes in the model is an increase in pellet ablation rates and decrease in penetration for current and future experiments

  10. Shielding performance of the NET vacuum vessel

    International Nuclear Information System (INIS)

    Arkuszewski, J.J.; Jaeger, J.F.

    1988-01-01

    To corroborate 1-D deterministic shielding calculations on the Next European Torus (NET) vacuum vessel/shield and shielding blanket, 3-D Monte Carlo calculations have been done with the MCNP code. This should provide information on the poloidal and the toroidal variations. Plasma source simulation and the geometrical model are described, as are other assumptions. The calculations are based on the extended plasma power of 714 MW. The results reported here are the heat deposition in various parts of the device, on the one hand, and the neutron and photon currents at the outer boundary of the vacuum vessel, on the other hand. The latter are needed for the detailed design of the super-conducting magnetic coils. A reasonable statistics has been obtained on the outboard side of the torus, though this cannot be said for the inboard side. The inboard is, however, much more toroidally symmetric than the outboard, so that other methods could be applied such as 2-D deterministic calculations, for instance. (author) 4 refs., 44 figs., 42 tabs

  11. ELECTROMAGNETIC FIELDS IN CYLINDRICAL INDUCTION INDUCTOR SYSTEM WITH MASSIVE SHIELD

    Directory of Open Access Journals (Sweden)

    D. Piskun

    2010-12-01

    Full Text Available The processes in a cylindrical induction inductor system with a massive additional non-magnetic shield and a thin ferromagnetic sheet blank are considered and the formula for induced currents and the strength of excited fields have been obtained.

  12. Shielding estimation for nuclear medicine therapy ward: our experience

    International Nuclear Information System (INIS)

    Skopljak-Beganovic, A.; Kucukalic-Selimovic, E.; Beganovic, A.; Drljevic, A.

    2008-01-01

    Full text: The aim of this study was to calculate and estimate the shielding thickness for a new Nuclear Medicine Therapy Ward. Parameters available for shielding calculation were: ground plan of the ward, radionuclides planned for use, maximum administered activity of I-131, maximum delivered activity of I-131 to the ward per week, average time spent in the hospital after the treatment. The most hazardous and most commonly used radioisotope is I-131. The target dose that needs to be met for occupationally exposed workers is 0.3 mSv per year. There are several factors that could be changed in order to achieve this value: distance from the source, shielding thickness, angle of incidence, occupational and usage factors. The maximum dose rate at 1 meter from the thyroid gland of the patient was considered to be 100 mSv/h. The distances and incidence angles could not be changed since these vales were predetermined in the ground plan. Different usage and occupational factors were used for different rooms in the ward. We used occupational factor 1 for the bed and 1/6 for the bathroom, and usage factor 1 for nurses' room and patient room and 1/6 for the corridors, etc. The easiest way of calculating dose attenuation in material was by introducing the HVL and TVL for broad beams. TVL and HVL were taken from the graph.The results show that shielding thickness should be in the range of 3 mmPb for room doors to 30 mmPb for the wall adjacent to the nurse's office. Most of the walls are 20 mmPb thick. These values were calculated using conservative assumptions and are more then enough to protect staff, patients and public from external radiation. If the construction cannot support the weight of lead some rearrangements regarding patient positions could be made. (author)

  13. Radiation shield for PWR reactors

    International Nuclear Information System (INIS)

    Esenov, Amra; Pustovgar, Andrey

    2013-01-01

    One of the chief structures of a reactor pit is a 'dry' shield. Setting up a 'dry' shield includes the technologically complex process of thermal processing of serpentinite concrete. Modern advances in the area of materials technology permit avoiding this complex and demanding procedure, and this significantly decreases the duration, labor intensity, and cost of setting it up. (orig.)

  14. Nuclear data for radiation shielding

    International Nuclear Information System (INIS)

    Miyasaka, Shunichi; Takahashi, Hiroshi.

    1976-01-01

    The third shielding expert conference was convened in Paris in Oct. 1975 for exchanging informations about the sensitivity evaluation of nuclear data in shielding calculation and integral bench mark experiment. The requirements about nuclear data presented at present from the field of nuclear design do not reflect sufficiently the requirements of shielding design, therefore it was the object to gather the requirements about nuclear data from the field of shielding. The nuclides used for shielding are numerous, and the nuclear data on these isotopes are required. Some of them cannot be ignored as the source of secondary γ-ray or in view of the radioactivation of materials. The requirements for the nuclear data of neutrons in the field of shielding are those concerning the reaction cross sections producing secondary γ-ray, the reaction cross sections including the production of secondary neutrons, elastic scattering cross sections, and total cross sections. The topics in the Paris conference about neutron shielding data are described, such as the methodology of sensitivity evaluation, the standardization of group constant libraries, the bench mark experiment on iron and sodium, and the cross section of γ-ray production. In the shielding of nuclear fission reactors, the γ-ray production owing to nuclear fission reaction is also important. In (d, t) fusion reactors, high energy neutrons are generated, and high energy γ-ray is emitted through giant E1 resonance. (Kako, I.)

  15. Concrete shielding exterior to iron

    International Nuclear Information System (INIS)

    Yurista, P.; Cossairt, D.

    1983-08-01

    A rule of thumb at Fermilab has been to use 3 feet of concrete exterior to iron shielding. A recent design of a shield with a severe dimensional constraint has prompted a re-evaluation of this rule of thumb and has led to the following calculations of the concrete thickness required to nullify this problem. 4 references, 4 figures

  16. Gonad shielding in diagnostic radiology

    International Nuclear Information System (INIS)

    1975-06-01

    The use of gonad shielding is an important radiation protection technique, intended to reduce unnecessary x-ray exposure of the gonads of patients from diagnostic x-ray procedures. This pamphlet will provide physicians and radiologic technologists with information which will aid their appropriate use of gonad shielding

  17. The Imperial Shield

    DEFF Research Database (Denmark)

    Mortensen, Simon Valentin

    2006-01-01

      The title of this Ph.d. dissertation is "The Imperial Shield: Imperial Overstretch, Assured Destruction, and the ban on nationwide ABM-defense with particular emphasis on the Johnson and the Nixon Administration". The dissertation set out to explain the origins of the ABM Treaty's central meaning....... Domestic spending continued to increase by more in real terms than the GDP, and the Democratically controlled Congress also made some very expensive modifications in Nixon tax bill in the fall of 1969, once again plunging the budget into the red.The economic crisis was partly caused by, and partly...... the Administration debated the deployment of new ABM-sites in early 1970, Kissinger could not prevail against these forces, but had to settle for a compromise, which he regarded as less than a definite commitment to nationwide ABM-defense.The political developments were of even greater importance. A strong link has...

  18. Shielded Canister Transporter

    International Nuclear Information System (INIS)

    Eidem, G.G. Jr.; Fages, R.

    1993-01-01

    The Hanford Waste Vitrification Plant (HWVP) will produce canisters filled with high-level radioactive waste immobilized in borosilicate glass. This report discusses a Shielded Canister Transporter (SCT) which will provide the means for safe transportation and handling of the canisters from the Vitrification Building to the Canister Storage Building (CSB). The stainless steel canisters are 0.61 meters in diameter, 3.0 meters tall, and weigh approximately 2,135 kilograms, with a maximum exterior surface dose rate of 90,000 R/hr. The canisters are placed into storage tubes to a maximum of three tall (two for overpack canisters) with an impact limiter placed at the tube bottom and between each canister. A floor plug seals the top of the storage tube at the operating floor level of the CSB

  19. ITER shielding blanket

    Energy Technology Data Exchange (ETDEWEB)

    Strebkov, Yu [ENTEK, Moscow (Russian Federation); Avsjannikov, A [ENTEK, Moscow (Russian Federation); Baryshev, M [NIAT, Moscow (Russian Federation); Blinov, Yu [ENTEK, Moscow (Russian Federation); Shatalov, G [KIAE, Moscow (Russian Federation); Vasiliev, N [KIAE, Moscow (Russian Federation); Vinnikov, A [ENTEK, Moscow (Russian Federation); Chernjagin, A [DYNAMICA, Moscow (Russian Federation)

    1995-03-01

    A reference non-breeding blanket is under development now for the ITER Basic Performance Phase for the purpose of high reliability during the first stage of ITER operation. More severe operation modes are expected in this stage with first wall (FW) local heat loads up to 100-300Wcm{sup -2}. Integration of a blanket design with protective and start limiters requires new solutions to achieve high reliability, and possible use of beryllium as a protective material leads to technologies. The rigid shielding blanket concept was developed in Russia to satisfy the above-mentioned requirements. The concept is based on a copper alloy FW, austenitic stainless steel blanket structure, water cooling. Beryllium protection is integrated in the FW design. Fabrication technology and assembly procedure are described in parallel with the equipment used. (orig.).

  20. Welding shield for coupling heaters

    Science.gov (United States)

    Menotti, James Louis

    2010-03-09

    Systems for coupling end portions of two elongated heater portions and methods of using such systems to treat a subsurface formation are described herein. A system may include a holding system configured to hold end portions of the two elongated heater portions so that the end portions are abutted together or located near each other; a shield for enclosing the end portions, and one or more inert gas inlets configured to provide at least one inert gas to flush the system with inert gas during welding of the end portions. The shield may be configured to inhibit oxidation during welding that joins the end portions together. The shield may include a hinged door that, when closed, is configured to at least partially isolate the interior of the shield from the atmosphere. The hinged door, when open, is configured to allow access to the interior of the shield.

  1. Penetration shielding applications of CYLSEC

    International Nuclear Information System (INIS)

    Dexheimer, D.T.; Hathaway, J.M.

    1985-01-01

    Evaluation of penetration and discontinuity shielding is necessary to meet 10CFR20 regulations for ensuring personnel exposures are as low as reasonably achievable (ALARA). Historically, those shielding evaluations have been done to some degree on all projects. However, many early plants used conservative methods due to lack of an economical computer code, resulting in costly penetration shielding programs. With the increased industry interest in cost effectively reducing personnel exposures to meet ALARA regulations and with the development of the CYLSEC gamma transport computer code at Bechtel, a comprehensive effort was initiated to reduce penetration and discontinuity shielding but still provide a prudent degree of protection for plant personnel from radiation streaming. This effort was more comprehensive than previous programs due to advances in shielding analysis technology and increased interest in controlling project costs while maintaining personnel exposures ALARA. Methodology and resulting cost savings are discussed

  2. Shield calculations, optimization vs. paradigm

    International Nuclear Information System (INIS)

    Cornejo D, N.; Hernandez S, A.; Martinez G, A.

    2006-01-01

    Many shieldings have been designed under the criteria of 'Maximum dose rates of project'. It has created the paradigm of those 'low dose rates', for the one which not few specialists would consider unacceptable levels of dose rate superior to the units of μSv.h -1 , independently of the exposure times. At the present time numerous shieldings are being designed considering dose restrictions in real times of exposure. After these new shieldings, the dose rates could be notably superior to those after traditional shieldings, without it implies inadequate designs or constructive errors. In the work significant differences in levels of dose rates and thickness of shieldings estimated by both methods for some typical facilities. It was concluded that the use of real times of exposure is more adequate for the optimization of the Radiological Protection, although this method demands bigger care in its application. (Author)

  3. Modular reactor head shielding system

    International Nuclear Information System (INIS)

    Jacobson, E. B.

    1985-01-01

    An improved modular reactor head shielding system is provided that includes a frame which is removably assembled on a reactor head such that no structural or mechanical alteration of the head is required. The shielding system also includes hanging assemblies to mount flexible shielding pads on trolleys which can be moved along the frame. The assemblies allow individual pivoting movement of the pads. The pivoting movement along with the movement allowed by the trolleys provides ease of access to any point on the reactor head. The assemblies also facilitate safe and efficient mounting of the pads directly to and from storage containers such that workers have additional shielding throughout virtually the entire installation and removal process. The flexible shielding pads are designed to interleave with one another when assembled around the reactor head for substantially improved containment of radiation leakage

  4. Parameters calculation of shielding experiment

    International Nuclear Information System (INIS)

    Gavazza, S.

    1986-02-01

    The radiation transport methodology comparing the calculated reactions and dose rates for neutrons and gama-rays, with experimental measurements obtained on iron shield, irradiated in the YAYOI reactor is evaluated. The ENDF/B-IV and VITAMIN-C libraries and the AMPX-II modular system, for cross sections generation collapsed by the ANISN code were used. The transport calculations were made using the DOT 3.5 code, adjusting the boundary iron shield source spectrum to the reactions and dose rates, measured at the beginning of shield. The neutron and gamma ray distributions calculated on the iron shield presented reasonable agreement with experimental measurements. An experimental arrangement using the IEA-R1 reactor to determine a shielding benchmark is proposed. (Author) [pt

  5. Remote auscultatory patient monitoring during magnetic resonance imaging

    DEFF Research Database (Denmark)

    Henneberg, S; Hök, B; Wiklund, L

    1992-01-01

    A system for patient monitoring during magnetic resonance imaging (MRI) is described. The system is based on remote auscultation of heart sounds and respiratory sounds using specially developed pickup heads that are positioned on the precordium or at the nostrils and connected to microphones via...... can be simultaneously auscultated both inside and outside the shielded MRI room by infrared transmission through a metal mesh window. Bench tests of the system show that common mode acoustic noise is suppressed by approximately 30 dB in the frequency region of interest (100-1,000 Hz), and that polymer...

  6. Magnetic hysterysis evolution of Ni-Al alloy with Fe and Mn substitution by vacuum arc melting to produce the room temperature magnetocaloric effect material

    Energy Technology Data Exchange (ETDEWEB)

    Notonegoro, Hamdan Akbar [PPS Materials Science, FMIPA-Universitas Indonesia, Depok 16424 (Indonesia); Mechanical Engineering Dept., FT-Universitas Sultan Ageng Tirtayasa, Cilegon 42435 (Indonesia); Kurniawan, Budhy; Manaf, Azwar, E-mail: azwar@sci.ui.ac.id [PPS Materials Science, FMIPA-Universitas Indonesia, Depok 16424 (Indonesia); Setiawan, Jan [Center for Nuclear Fuel Tecnology-Badan Tenaga Atom Nasional, Tangerang Selatan 15310 (Indonesia)

    2016-06-17

    The development of magnetocaloric effect (MCE) material is done in order to reduce the damage of the ozone layer caused by the chlorofluorocarbons (CFCs) emitted into the air. The research dealing with synthesis of magnetocaloric materials based of Ni-Al Heusler Alloy structure and by varying substitution some atoms of Ni with Fe and Al with Mn on Ni-Al Heusler Alloy structure to become Ni{sub 44}Fe{sub 6}Mn{sub 32}Al{sub 18}. Vacuum Arc Melting (VAM) equipment is used to form the alloys on vacuum condition and by flowing argon gas atmosphere and then followed by annealing process for 72 hours. X-Ray Diffraction (XRD) reveals that crystallite structure of material is observed. We define that Ni{sub 44}Fe{sub 6} as X{sub 2}, Mn{sub 25} as Y, and Al{sub 18}Mn{sub 7} as Z. Based on the XRD result, we observed that the general formula X{sub 2}YZ is not changed. The PERMAGRAF measurement revealed that there exists of magnetic hysterysis. The hysterysis show that the magnetic structures of the system undego evolution from diamagnetic to soft ferromagnetic material which all of the compound have the same crystallite structure. This evolution indicated that the change in the composition has led to changes the magnetic composition. Mn is the major element that gives strong magnetic properties to the sample. When Mn partially replaced position of Al, the sample became dominant to be influenced to improve their magnetic properties. In addition, substitution a part of Ni by Fe in the composition reveals a pinning of the domain walls in the sample.

  7. Neutron shielding and its impact on the ITER machine design

    International Nuclear Information System (INIS)

    Daenner, W.; El Guebaly, L.; Sawan, M.; Gohar, Y.; Maki, K.; Rado, V.; Schchipakin, O.; Zimin, S.

    1991-01-01

    This paper describes the efforts made in the frame of the ITER project to analyze the shielding of the superconducting magnets. First, the radiation limits to be achieved are specified as well as the neutron source in terms of wall loading on the first wall of the machine. Then the general shield concept is explained, including the most essential details of the various shield components. A brief section is devoted to the calculational tools, the data base, and the safety factors to be applied to the results obtained. The neutronics models of four different configurations are summarized as they were used to study the most critical parts of the machine. This section is followed by a presentation of the most important results from one-, two- and three-dimensional calculations. They are given for both the reference design and an improved one in which the critical regions are reinforced with respect to their shielding capability. It is concluded that the ITER shield layout just marginally meets the stated limits provided that some tungsten is included in the critical regions. A slight revision of the overall machine dimensions with the aim to achieve a less complex shield and a higher margin with respect to the limits is, however, seen the better solution. (orig.)

  8. Pre-evaluation of fusion shielding benchmark experiment

    International Nuclear Information System (INIS)

    Hayashi, K.; Handa, H.; Konno, C.

    1994-01-01

    Shielding benchmark experiment is very useful to test the design code and nuclear data for fusion devices. There are many types of benchmark experiments that should be done in fusion shielding problems, but time and budget are limited. Therefore it will be important to select and determine the effective experimental configurations by precalculation before the experiment. The authors did three types of pre-evaluation to determine the experimental assembly configurations of shielding benchmark experiments planned in FNS, JAERI. (1) Void Effect Experiment - The purpose of this experiment is to measure the local increase of dose and nuclear heating behind small void(s) in shield material. Dimension of the voids and its arrangements were decided as follows. Dose and nuclear heating were calculated both for with and without void(s). Minimum size of the void was determined so that the ratio of these two results may be larger than error of the measurement system. (2) Auxiliary Shield Experiment - The purpose of this experiment is to measure shielding properties of B 4 C, Pb, W, and dose around superconducting magnet (SCM). Thickness of B 4 C, Pb, W and their arrangement including multilayer configuration were determined. (3) SCM Nuclear Heating Experiment - The purpose of this experiment is to measure nuclear heating and dose distribution in SCM material. Because it is difficult to use liquid helium as a part of SCM mock up material, material composition of SCM mock up are surveyed to have similar nuclear heating property of real SCM composition

  9. Design experience: CRBRP radiation shielding

    International Nuclear Information System (INIS)

    Disney, R.K.; Chan, T.C.; Gallo, F.G.; Hedgecock, L.R.; McGinnis, C.A.; Wrights, G.N.

    1978-11-01

    The Clinch River Breeder Reactor Plant (CRBRP) is being designed as a fast breeder demonstration project in the U.S. Liquid Metal Fast Breeder Reactor (LMFBR) program. Radiation shielding design of the facility consists of a comprehensive design approach to assure compliance with design and government regulatory requirements. Studies conducted during the CRBRP design process involved the aspects of radiation shielding dealing with protection of components, systems, and personnel from radiation exposure. Achievement of feasible designs, while considering the mechanical, structural, nuclear, and thermal performance of the component or system, has required judicious trade-offs in radiation shielding performance. Specific design problems which have been addressed are in-vessel radial shielding to protect permanent core support structures, flux monitor system shielding to isolate flux monitoring systems for extraneous background sources, reactor vessel support shielding to allow personnel access to the closure head during full power operation, and primary heat transport system pipe chaseway shielding to limit intermediate heat transport system sodium system coolant activation. The shielding design solutions to these problems defined a need for prototypic or benchmark experiments to provide assurance of the predicted shielding performance of selected design solutions and the verification of design methodology. Design activities of CRBRP plant components an systems, which have the potential for radiation exposure of plant personnel during operation or maintenance, are controlled by a design review process related to radiation shielding. The program implements design objectives, design requirements, and cost/benefit guidelines to assure that radiation exposures will be ''as low as reasonably achievable''

  10. Preliminary shielding calculation for the system of CyberKnife robotic radiosurgery

    International Nuclear Information System (INIS)

    Toreti, Dalila; Xavier, Clarice; Moura, Fabio

    2011-01-01

    The CyberKnife robotic system uses a manipulator with six grade of freedom for positioning a 6 MV Linac accelerator for treatment of lesions. This paper presents calculations for a standard room, with 200 cm of thickness walls primary, build for a CyberKnife system, and calculations for a room originally designed for a Linac conventional (with gantry), with secondary barriers of 107 cm thickness. After the realization of shielding for both rooms, the results shown that walls of standard room with 200 cm thickness are adequate for the secondary shield, and for a room with a conventional Linac, from all six evaluated points, two would require additional shielding of nine cm and four cm of concrete with 2.4 g/cubic cm. This shows that the CyberKnife system can be installed in a originally designed room for a conventional Linac with neither restrict nor any shielding, since no incidence of beams on the secondary barriers is existent

  11. MAGNET

    CERN Multimedia

    by B. Curé

    2011-01-01

    The magnet operation was very satisfactory till the technical stop at the end of the year 2010. The field was ramped down on 5th December 2010, following the successful regeneration test of the turbine filters at full field on 3rd December 2010. This will limit in the future the quantity of magnet cycles, as it is no longer necessary to ramp down the magnet for this type of intervention. This is made possible by the use of the spare liquid Helium volume to cool the magnet while turbines 1 and 2 are stopped, leaving only the third turbine in operation. This obviously requires full availability of the operators to supervise the operation, as it is not automated. The cryogenics was stopped on 6th December 2010 and the magnet was left without cooling until 18th January 2011, when the cryoplant operation resumed. The magnet temperature reached 93 K. The maintenance of the vacuum pumping was done immediately after the magnet stop, when the magnet was still at very low temperature. Only the vacuum pumping of the ma...

  12. TORE-SUPRA: design of thermal radiation shield at 80 K

    International Nuclear Information System (INIS)

    Aymar, R.; Cordier, J.J.; Deschamps, P.; Gauthier, A.; Perin, J.P.

    1982-09-01

    The TORE-SUPRA superconducting toroidal magnet operating at liquid helium temperature, must be protected against thermal radiation from the vessels. For this purpose, stainless steel heat shields, cooled at 80 K, are positioned between coil casings at 4.5 K and the vessels, and constitute a double stiff toroid which completely surrounds the magnet. Mockups have been manufactured to study their design and operating problems. Calculations have also been made to analyse the mechanical behaviour of these shields

  13. Transparent fast neutron shielding material and shielding method

    International Nuclear Information System (INIS)

    Nashimoto, Tetsuji; Katase, Haruhisa.

    1993-01-01

    Polyisobutylene having a viscosity average molecular weight of 20,000 to 80,000 and a hydrogen atom density of greater than 7.0 x 10 22 /cm 3 is used as a fast neutron shielding material. The shielding material is excellent in the shielding performance against fast neutrons, and there is no worry of leakage even when holes should be formed to a vessel. Further, it is excellent in fabricability, relatively safe even upon occurrence of fire and, in addition, it is transparent to enable to observe contents easily. (T.M.)

  14. Nonlinear AC susceptibility, surface and bulk shielding

    Science.gov (United States)

    van der Beek, C. J.; Indenbom, M. V.; D'Anna, G.; Benoit, W.

    1996-02-01

    We calculate the nonlinear AC response of a thin superconducting strip in perpendicular field, shielded by an edge current due to the geometrical barrier. A comparison with the results for infinite samples in parallel field, screened by a surface barrier, and with those for screening by a bulk current in the critical state, shows that the AC response due to a barrier has general features that are independent of geometry, and that are significantly different from those for screening by a bulk current in the critical state. By consequence, the nonlinear (global) AC susceptibility can be used to determine the origin of magnetic irreversibility. A comparison with experiments on a Bi 2Sr 2CaCu 2O 8+δ crystal shows that in this material, the low-frequency AC screening at high temperature is mainly due to the screening by an edge current, and that this is the unique source of the nonlinear magnetic response at temperatures above 40 K.

  15. Investigation of water content in primary upper shield of high temperature engineering test reactor (HTTR)

    International Nuclear Information System (INIS)

    Sumita, Junya; Sawa, Kazuhiro; Mogi, Haruyoshi; Itahashi, Shuuji; Kitami, Toshiyuki; Akutu, Youichi; Fuchita, Yasuhiro; Kawaguchi, Toru; Moriya, Masahiro

    1999-09-01

    A primary upper shield of the High Temperature Engineering Test Reactor (HTTR) is composed of concrete (grout) which is packed into iron frames. The main function of the primary upper shield is to attenuate neutron and gamma ray from the core, that leads to satisfy dose equivalent rate limit of operating floor and stand-pipe room. Water content in the concrete is one of the most important things because it strongly affects neutron-shielding ability. Then, we carried out out-of-pile experiments to investigate relationship between temperature and water content in the concrete. Based on the experimental results, a hydrolysis-diffusion model was developed to investigate water release behavior from the concrete. The model showed that water content used for shielding design in the primary upper shield of the HTTR will be maintained if temperature during operating life is under 110degC. (author)

  16. The influence of the iron shield of the solenoid on spin tracking

    Directory of Open Access Journals (Sweden)

    Toprek Dragan

    2005-01-01

    Full Text Available The influence of the iron shield of the solenoid on spin tracking is studied in this paper. In the case of the 200 MeV proton, the study has been numerically done in the ZGOUBI code. The distribution of the magnetic field was done by POISSON. We have come to the conclusion that the influence of the solenoid’s shielding on spin tracking is the same at its entrance and exit and that is directly proportional to the intensity of the magnetic induction B on the axis of the solenoid. We have also determined that the influence of the solenoid’s shielding is much stronger on transversal components of the spin than on its longitudinal component. The differences between components of the spin for the shielded and not-shielded solenoid diminish with the in crease in the distance from the solenoid.

  17. Optimized Shielding and Fabrication Techniques for TiN and Al Microwave Resonators

    Science.gov (United States)

    Kreikebaum, John Mark; Kim, Eunseong; Livingston, William; Dove, Allison; Calusine, Gregory; Hover, David; Rosenberg, Danna; Oliver, William; Siddiqi, Irfan

    We present a systematic study of the effects of shielding and packaging on the internal quality factor (Qi) of Al and TiN microwave resonators designed for use in qubit readout. Surprisingly, Qi =1.3x106 TiN samples investigated at 100 mK exhibited no significant changes in linewidth when operated without magnetic shielding and in an open cryo-package. In contrast, Al resonators showed systematic improvement in Qi with each successive shield. Measurements were performed in an adiabatic demagnetization refrigerator, where typical ambient fields of 0.2 mT are present at the sample stage. We discuss the effect of 100 mK and 500 mK Cu radiation shields and cryoperm magnetic shielding on resonator Q as a function of temperature and input power in samples prepared with a variety of surface treatments, fabrication recipes, and embedding circuits. This research was supported by the ARO and IARPA.

  18. Radiation shielding for fusion reactors

    International Nuclear Information System (INIS)

    Santoro, R.T.

    2000-01-01

    Radiation shielding requirements for fusion reactors present different problems than those for fission reactors and accelerators. Fusion devices, particularly tokamak reactors, are complicated by geometry constraints that complicate disposition of fully effective shielding. This paper reviews some of these shielding issues and suggested solutions for optimizing the machine and biological shielding. Radiation transport calculations are essential for predicting and confirming the nuclear performance of the reactor and, as such, must be an essential part of the reactor design process. Development and optimization of reactor components from the first wall and primary shielding to the penetrations and containment shielding must be carried out in a sensible progression. Initial results from one-dimensional transport calculations are used for scoping studies and are followed by detailed two- and three-dimensional analyses to effectively characterize the overall radiation environment. These detail model calculations are essential for accounting for the radiation leakage through ports and other penetrations in the bulk shield. Careful analysis of component activation and radiation damage is cardinal for defining remote handling requirements, in-situ replacement of components, and personnel access at specific locations inside the reactor containment vessel. (author)

  19. Shield calculation of project for instrument calibration integrated laboratory of IPEN-Sao Paulo, Brazil

    International Nuclear Information System (INIS)

    Barros, Gustavo A.S.J.; Caldas, Linda V.E.

    2009-01-01

    This work performed the shield calculation of the future rooms walls of the five X-ray equipment of the Instrument Calibration Laboratory of the IPEN, Sao Paulo, Brazil, which will be constructed in project of laboratory enlargement. The obtained results by application of a calculation methodology from an international regulation have shown that the largest thickness of shielding (25.7 cm of concrete or 7.1 mm of lead) will be of the wall which will receive the primary beam of the equipment with a 320 kV voltage. The cost/benefit analysis indicated the concrete as the best material option for the shielding

  20. Morphometry of terrestrial shield volcanoes

    Science.gov (United States)

    Grosse, Pablo; Kervyn, Matthieu

    2018-03-01

    Shield volcanoes are described as low-angle edifices built primarily by the accumulation of successive lava flows. This generic view of shield volcano morphology is based on a limited number of monogenetic shields from Iceland and Mexico, and a small set of large oceanic islands (Hawaii, Galápagos). Here, the morphometry of 158 monogenetic and polygenetic shield volcanoes is analyzed quantitatively from 90-meter resolution SRTM DEMs using the MORVOLC algorithm. An additional set of 24 lava-dominated 'shield-like' volcanoes, considered so far as stratovolcanoes, are documented for comparison. Results show that there is a large variation in shield size (volumes from 0.1 to > 1000 km3), profile shape (height/basal width (H/WB) ratios mostly from 0.01 to 0.1), flank slope gradients (average slopes mostly from 1° to 15°), elongation and summit truncation. Although there is no clear-cut morphometric difference between shield volcanoes and stratovolcanoes, an approximate threshold can be drawn at 12° average slope and 0.10 H/WB ratio. Principal component analysis of the obtained database enables to identify four key morphometric descriptors: size, steepness, plan shape and truncation. Hierarchical cluster analysis of these descriptors results in 12 end-member shield types, with intermediate cases defining a continuum of morphologies. The shield types can be linked in terms of growth stages and shape evolution, related to (1) magma composition and rheology, effusion rate and lava/pyroclast ratio, which will condition edifice steepness; (2) spatial distribution of vents, in turn related to the magmatic feeding system and the tectonic framework, which will control edifice plan shape; and (3) caldera formation, which will condition edifice truncation.

  1. Novel room temperature ferromagnetic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Amita [KTH Royal Inst. of Technology, Stockholm (Sweden)

    2004-06-01

    Today's information world, bits of data are processed by semiconductor chips, and stored in the magnetic disk drives. But tomorrow's information technology may see magnetism (spin) and semiconductivity (charge) combined in one 'spintronic' device that exploits both charge and 'spin' to carry data (the best of two worlds). Spintronic devices such as spin valve transistors, spin light emitting diodes, non-volatile memory, logic devices, optical isolators and ultra-fast optical switches are some of the areas of interest for introducing the ferromagnetic properties at room temperature in a semiconductor to make it multifunctional. The potential advantages of such spintronic devices will be higher speed, greater efficiency, and better stability at a reduced power consumption. This Thesis contains two main topics: In-depth understanding of magnetism in Mn doped ZnO, and our search and identification of at least six new above room temperature ferromagnetic semiconductors. Both complex doped ZnO based new materials, as well as a number of nonoxides like phosphides, and sulfides suitably doped with Mn or Cu are shown to give rise to ferromagnetism above room temperature. Some of the highlights of this work are discovery of room temperature ferromagnetism in: (1) ZnO:Mn (paper in Nature Materials, Oct issue, 2003); (2) ZnO doped with Cu (containing no magnetic elements in it); (3) GaP doped with Cu (again containing no magnetic elements in it); (4) Enhancement of Magnetization by Cu co-doping in ZnO:Mn; (5) CdS doped with Mn, and a few others not reported in this thesis. We discuss in detail the first observation of ferromagnetism above room temperature in the form of powder, bulk pellets, in 2-3 mu-m thick transparent pulsed laser deposited films of the Mn (<4 at. percent) doped ZnO. High-resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS) spectra recorded from 2 to 200nm areas showed homogeneous

  2. Study on the adjustment capability of the excitation system located inside superconducting machine electromagnetic shield

    Science.gov (United States)

    Xia, D.; Xia, Z.

    2017-12-01

    The ability for the excitation system to adjust quickly plays a very important role in maintaining the normal operation of superconducting machines and power systems. However, the eddy currents in the electromagnetic shield of superconducting machines hinder the exciting magnetic field change and weaken the adjustment capability of the excitation system. To analyze this problem, a finite element calculation model for the transient electromagnetic field with moving parts is established. The effects of three different electromagnetic shields on the exciting magnetic field are analyzed using finite element method. The results show that the electromagnetic shield hinders the field changes significantly, the better its conductivity, the greater the effect on the superconducting machine excitation.

  3. Freely oriented portable superconducting magnet

    Science.gov (United States)

    Schmierer, Eric N [Los Alamos, NM; Prenger, F Coyne [Los Alamos, NM; Hill, Dallas D [Los Alamos, NM

    2010-01-12

    A freely oriented portable superconducting magnet is disclosed. Coolant is supplied to the superconducting magnet from a repository separate from the magnet, enabling portability of the magnet. A plurality of support assemblies structurally anchor and thermally isolate the magnet within a thermal shield. A plurality of support assemblies structurally anchor and thermally isolate the thermal shield within a vacuum vessel. The support assemblies restrain movement of the magnet resulting from energizing and cooldown, as well as from changes in orientation, enabling the magnet to be freely orientable.

  4. Room-temperature antiferromagnetic memory resistor.

    Science.gov (United States)

    Marti, X; Fina, I; Frontera, C; Liu, Jian; Wadley, P; He, Q; Paull, R J; Clarkson, J D; Kudrnovský, J; Turek, I; Kuneš, J; Yi, D; Chu, J-H; Nelson, C T; You, L; Arenholz, E; Salahuddin, S; Fontcuberta, J; Jungwirth, T; Ramesh, R

    2014-04-01

    The bistability of ordered spin states in ferromagnets provides the basis for magnetic memory functionality. The latest generation of magnetic random access memories rely on an efficient approach in which magnetic fields are replaced by electrical means for writing and reading the information in ferromagnets. This concept may eventually reduce the sensitivity of ferromagnets to magnetic field perturbations to being a weakness for data retention and the ferromagnetic stray fields to an obstacle for high-density memory integration. Here we report a room-temperature bistable antiferromagnetic (AFM) memory that produces negligible stray fields and is insensitive to strong magnetic fields. We use a resistor made of a FeRh AFM, which orders ferromagnetically roughly 100 K above room temperature, and therefore allows us to set different collective directions for the Fe moments by applied magnetic field. On cooling to room temperature, AFM order sets in with the direction of the AFM moments predetermined by the field and moment direction in the high-temperature ferromagnetic state. For electrical reading, we use an AFM analogue of the anisotropic magnetoresistance. Our microscopic theory modelling confirms that this archetypical spintronic effect, discovered more than 150 years ago in ferromagnets, is also present in AFMs. Our work demonstrates the feasibility of fabricating room-temperature spintronic memories with AFMs, which in turn expands the base of available magnetic materials for devices with properties that cannot be achieved with ferromagnets.

  5. Conservative method for determination of material thickness used in shielding of veterinary facilities

    International Nuclear Information System (INIS)

    Lava, Deise D.; Borges, Diogo da S.; Affonso, Renato R.W.; Moreira, Maria de L.; Guimaraes, Antonio C.F.

    2014-01-01

    For determination of an effective method for shielding of veterinary rooms, was provided shielding methods generally used in rooms which works with X-ray production and radiotherapy. Every calculation procedure is based in traditional variables used to transmission calculation. The thickness of the materials used for primary and secondary shieldings are obtained to respect the limits set by the Brazilian National Nuclear Energy Commission (CNEN). This work presents the development of a computer code in order to serve as a practical tool for determining rapid and effective materials and their thicknesses to shield veterinary facilities. The code determines transmission values of the shieldings and compares them with data from transmission 'maps' provided by NCRP-148 report. These 'maps' were added to the algorithm through interpolation techniques of curves of materials used for shielding. Each interpolation generates about 1,000,000 points that are used to generate a new curve. The new curve is subjected to regression techniques, which makes possible to obtain nine degree polynomial, and exponential equations. These equations whose variables consist of transmission of values, enable trace all the points of this curve with high precision. The data obtained from the algorithm were satisfactory with official data presented by the National Council of Radiation Protection and Measurements (NCRP) and can contribute as a practical tool for verification of shielding of veterinary facilities that require using Radiotherapy techniques and X-ray production

  6. A study of gamma shielding

    International Nuclear Information System (INIS)

    Roogtanakait, N.

    1981-01-01

    Gamma rays have high penetration power and its attenuation depends upon the thickness and the attenuation coefficient of the shield, so it is necessary to use the high density shield to attenuate the gamma rays. Heavy concrete is considered to be used for high radiation laboratory and the testing of the shielding ability and compressibility of various types of heavy concrete composed of baryte, hematite, ilmenite and galena is carried out. The results of this study show that baryte-ilmenite concrete is the most suitable for high radiation laboratory in Thailand

  7. Radiation protection/shield design

    International Nuclear Information System (INIS)

    Disney, R.K.

    1977-01-01

    Radiation protection/shielding design of a nuclear facility requires a coordinated effort of many engineering disciplines to meet the requirements imposed by regulations. In the following discussion, the system approach to Clinch River Breeder Reactor Plant (CRBRP) radiation protection will be described, and the program developed to implement this approach will be defined. In addition, the principal shielding design problems of LMFBR nuclear reactor systems will be discussed in realtion to LWR nuclear reactor system shielding designs. The methodology used to analyze these problems in the U.S. LMFBR program, the resultant design solutions, and the experimental verification of these designs and/or methods will be discussed. (orig.) [de

  8. Shielding synchrotron light sources: Advantages of circular shield walls tunnels

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, S.L. [Design and Accelerator Operations Consulting, 568 Wintergreen Ct Ridge, NY 11961 (United States); Ghosh, V.J.; Breitfeller, M. [NSLS-II, Brookhaven National Laboratory, Upton, NY 11973 (United States)

    2016-08-11

    Third generation high brightness light sources are designed to have low emittance and high current beams, which contribute to higher beam loss rates that will be compensated by Top-Off injection. Shielding for these higher loss rates will be critical to protect the projected higher occupancy factors for the users. Top-Off injection requires a full energy injector, which will demand greater consideration of the potential abnormal beam miss-steering and localized losses that could occur. The high energy electron injection beam produce significantly higher neutron component dose to the experimental floor than lower energy injection and ramped operations. High energy neutrons produced in the forward direction from thin target beam losses are a major component of the dose rate outside the shield walls of the tunnel. The convention has been to provide thicker 90° ratchet walls to reduce this dose to the beam line users. We present an alternate circular shield wall design, which naturally and cost effectively increases the path length for this forward radiation in the shield wall and thereby substantially decreasing the dose rate for these beam losses. This shield wall design will greatly reduce the dose rate to the users working near the front end optical components but will challenge the beam line designers to effectively utilize the longer length of beam line penetration in the shield wall. Additional advantages of the circular shield wall tunnel are that it's simpler to construct, allows greater access to the insertion devices and the upstream in tunnel beam line components, as well as reducing the volume of concrete and therefore the cost of the shield wall.

  9. MAGNET

    CERN Multimedia

    Benoit Curé

    2010-01-01

    Operation of the magnet has gone quite smoothly during the first half of this year. The magnet has been at 4.5K for the full period since January. There was an unplanned short stop due to the CERN-wide power outage on May 28th, which caused a slow dump of the magnet. Since this occurred just before a planned technical stop of the LHC, during which access in the experimental cavern was authorized, it was decided to leave the magnet OFF until 2nd June, when magnet was ramped up again to 3.8T. The magnet system experienced a fault also resulting in a slow dump on April 14th. This was triggered by a thermostat on a filter choke in the 20kA DC power converter. The threshold of this thermostat is 65°C. However, no variation in the water-cooling flow rate or temperature was observed. Vibration may have been the root cause of the fault. All the thermostats have been checked, together with the cables, connectors and the read out card. The tightening of the inductance fixations has also been checked. More tem...

  10. MAGNET

    CERN Multimedia

    B. Curé

    2012-01-01

      The magnet was energised at the beginning of March 2012 at a low current to check all the MSS safety chains. Then the magnet was ramped up to 3.8 T on 6 March 2012. Unfortunately two days later an unintentional switch OFF of the power converter caused a slow dump. This was due to a misunderstanding of the CCC (CERN Control Centre) concerning the procedure to apply for the CMS converter control according to the beam-mode status at that time. Following this event, the third one since 2009, a discussion was initiated to define possible improvement, not only on software and procedures in the CCC, but also to evaluate the possibility to upgrade the CMS hardware to prevent such discharge from occurring because of incorrect procedure implementations. The magnet operation itself was smooth, and no power cuts took place. As a result, the number of magnetic cycles was reduced to the minimum, with only two full magnetic cycles from 0 T to 3.8 T. Nevertheless the magnet suffered four stops of the cryogeni...

  11. Survivor shielding. Part C. Improvements in terrain shielding

    International Nuclear Information System (INIS)

    Egbert, Stephen D.; Kaul, Dean C.; Roberts, James A.; Kerr, George D.

    2005-01-01

    A number of atomic-bomb survivors were affected by shielding provided by terrain features. These terrain features can be a small hill, affecting one or two houses, or a high mountain that shields large neighborhoods. In the survivor dosimetry system, terrain shielding can be described by a transmission factor (TF), which is the ratio between the dose with and without the terrain present. The terrain TF typically ranges between 0.1 and 1.0. After DS86 was implemented at RERF, the terrain shielding categories were examined and found to either have a bias or an excessive uncertainty that could readily be removed. In 1989, an improvement in the terrain model was implemented at RERF in the revised DS86 code, but the documentation was not published. It is now presented in this section. The solution to the terrain shielding in front of a house is described in this section. The problem of terrain shielding of survivors behind Hijiyama mountain at Hiroshima and Konpirasan mountain at Nagasaki has also been recognized, and a solution to this problem has been included in DS02. (author)

  12. Radiation shielding member

    International Nuclear Information System (INIS)

    Nemezawa, Isao; Kimura, Tadahiro; Mizuochi, Akira; Omori, Tetsu

    1998-01-01

    A single body of a radiation shield comprises a bag prepared by welding or bonding a polyurethane sheet which is made flat while interposing metal plates at the upper and the lower portion of the bag. Eyelet fittings are disposed to the upper and the lower portions of the bag passing through the metal plates and the flat portion of the bag. Water supplying/draining ports are disposed to two upper and lower places of the bag at a height where the metal plates are disposed. Reinforcing walls welded or bonded to the inner wall surface of the bag are elongated in vertical direction to divide the inside of the bag to a plurality of cells. The bag is suspended and supported from a frame with S-shaped hooks inserted into the eyelet fittings as connecting means. A plurality of bags are suspended and supported from the frame at a required height by way of the eyelets at the lower portion of the suspended and supported bag and the eyelet fittings at the upper portion of the bag below the intermediate connection means. (I.N.)

  13. Self-shielding factors

    International Nuclear Information System (INIS)

    Kaul, D.C.

    1982-01-01

    Throughout the last two decades many efforts have been made to estimate the effect of body self-shielding on organ doses from externally incident neutrons and gamma rays. These began with the use of simple geometry phantoms and have culminated in the use of detailed anthropomorphic phantoms. In a recent effort, adjoint Monte Carlo analysis techniques have been used to determine dose and dose equivalent to the active marrow as a function of energy and angle of neutron fluence externally incident on an anthropomorphic phantom. When combined with fluences from actual nuclear devices, these dose-to-fluence factors result in marrow dose values that demonstrate great sensitivity to variations in device type, range, and body orientation. Under a state-of-the-art radiation transport analysis demonstration program for the Japanese cities, sponsored by the Defense Nuclear Agency at the request of the National Council on Radiation Protection and Measurements, the marrow dose study referred to above is being repeated to obtain spectral distributions within the marrow for externally incident neutrons and gamma rays of arbitrary energy and angle. This is intended to allow radiobiologists and epidemiologists to select and to modify numbers of merit for correlation with health effects and to permit a greater understanding of the relationship between human and laboratory subject dosimetry

  14. Shielding plug device

    International Nuclear Information System (INIS)

    Orii, Shoichi; Hasegawa, Satoshi; Makishima, Kenji.

    1976-01-01

    Object: To reduce the size of and extend the life of a revolving bearing and facilitate the laying of driving cables and duct lines, this being accomplished by providing plug raising means of a fast breeder on a stationary plug mounting base so as to prevent the shearing force of sodium from acting upon the revolving bearing. Structure: The shield plug means comprises a stationary plug secured to the open end of the reactor container, a rotary plug rotatable with respect to the stationary plug, an annular base formed on top of the stationary plug so as to cover the rotary plug, a bearing secured to the rotary plug edge lower face and upper and lower locking plates. At the time of the rotation of the rotary plug, the upper locking plate is withdrawn, the stationary plug is raised to release the seal structure, and the lower locking plate is inserted between the bearing and stationary plug. In this way, smooth rotation of the rotary plug can be obtained. (Horiuchi, T.)

  15. Superconducting shielding for a polarized target in PANDA

    Energy Technology Data Exchange (ETDEWEB)

    Mora Espi, Maria Carmen; Froehlich, Bertold; Dbeyssi, Alaa; Aguar Bartolome, Patricia; Gerz, Kathrin; Ahmed, Samer; Wang, Yadi; Lin, Dexu; Feldbauer, Florian [Helmholtz-Institut Mainz (Germany); Penuelas, Ana [Universitat de Valencia (Spain); Collaboration: PANDA-Collaboration

    2016-07-01

    The measurement of the phase between the electric and the magnetic form factors of the proton can be measured using a polarized interaction. A feasible possibility to allow this kind of reactions would be to develop a transversely polarized proton target to be used in the PANDA experiment. The first step to achieve the transverse target polarization is to study the feasibility of shielding the target region from the external 2 T longitudinal magnetic field generated by the PANDA solenoid. BSCOO-2212, a new high-temperature superconductor material, has been identified as a possible candidate to be used for shielding this external magnetic field. Tests at 4 K have taken place in the Helmholtz Institute Mainz with this material, and the first preliminary results are shown here.

  16. SNF shipping cask shielding analysis

    International Nuclear Information System (INIS)

    Johnson, J.O.; Pace, J.V. III.

    1996-01-01

    The Waste Management and Remedial Action Division has planned a modification sequence for storage facility 7827 in the Solid Waste Storage Area (SWSA). The modification cycle is: (1) modify an empty caisson, (2) transfer the spent nuclear fuel (SNF) of an occupied caisson to a hot cell in building 3525 for inspection and possible repackaging, and (3) return the package to the modified caisson in the SWSA. Although the SNF to be moved is in the solid form, it has different levels of activity. Thus, the following 5 shipping casks will be available for the task: the Loop Transport Carrier, the In- Pile Loop LITR HB-2 Carrier, the 6.5-inch HRLEL Carrier, the HFIR Hot Scrap Carrier, and the 10-inch ORR Experiment Removal Shield Cask. This report describes the shielding tasks for the 5 casks: determination of shielding characteristics, any streaming avenues, estimation of thermal limits, and shielding calculational uncertainty for use in the transportation plan

  17. Active Radiation Shield, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — DEC-Shield technology offers the means to generate electric power from cosmic radiation sources and fuse dissimilar systems and functionality into a structural...

  18. Gonad shielding in computerized tomography

    International Nuclear Information System (INIS)

    Rockstroh, G.

    1984-01-01

    The reduction of gonadal dose by shielding of the gonads was investigated for a Somatom 2 using an anthropomorphic phantom. For small distances from the slice examined the gonadal dose results from intracorporal secondary radiation and is only insignificantly reduced by shielding. For greater distances shielding is relatively more effective, the gonadal dose however is small because of the approximately exponential decay. Shielding of the gonads therefore does not seem adequate for the reduction of gonadal dose. From dose measurements in cylinder phantoms of several diameters it appears that no different results would be obtained for children and young adults. An effective reduction of gonadal dose is only possible with lead capsules for males. (author)

  19. Radiation shielding for neutron guides

    International Nuclear Information System (INIS)

    Ersez, T.; Braoudakis, G.; Osborn, J.C.

    2005-01-01

    Full text: Models of the neutron guide shielding for the out of bunker guides on the thermal and cold neutron beam lines of the OPAL Reactor (ANSTO) were constructed using the Monte Carlo code MCNP 4B. The neutrons that were not reflected inside the guides but were absorbed by the supermirror (SM) layers were noted to be a significant source of gammas. Gammas also arise from neutrons absorbed by the B, Si, Na and K contained in the glass. The proposed shielding design has produced compact shielding assemblies. These arrangements are consistent with safety requirements, floor load limits, and cost constraints. To verify the design a prototype was assembled consisting of 120mm thick Pb(96%)Sb(4%) walls resting on a concrete block. There was good agreement between experimental measurements and calculated dose rates for bulk shield regions. (authors)

  20. Shielding calculations. Optimization vs. Paradigms

    International Nuclear Information System (INIS)

    Cornejo Diaz, Nestor; Hernandez Saiz, Alejandro; Martinez Gonzalez, Alina

    2005-01-01

    Many radiation shielding barriers in Cuba have been designed according to the criterion of Maxi-mum Projected Dose Rates. This fact has created the paradigm of low dose rates. Because of this, dose rate levels greater than units of Sv.h-1 would be considered unacceptable by many specialists, regardless of the real exposure times. Nowadays many shielding barriers are being designed using dose constraints in real exposure times. Behind the new barriers, dose rates could be notably greater than those behind the traditional ones, and it does not imply inadequate designs or constructive errors. In this work were obtained significant differences in dose rate levels and shield-ing thicknesses calculated by both methods for some typical installations. The work concludes that real exposure time approach is more adequate in order to optimise Radiation Protection, although this method should be carefully applied