Measurement of secondary particle production induced by particle therapy ion beams impinging on a PMMA target

Directory of Open Access Journals (Sweden)

Toppi M.

2016-01-01

Full Text Available Particle therapy is a technique that uses accelerated charged ions for cancer treatment and combines a high irradiation precision with a high biological effectiveness in killing tumor cells [1]. Informations about the secondary particles emitted in the interaction of an ion beam with the patient during a treatment can be of great interest in order to monitor the dose deposition. For this purpose an experiment at the HIT (Heidelberg Ion-Beam Therapy Center beam facility has been performed in order to measure fluxes and emission profiles of secondary particles produced in the interaction of therapeutic beams with a PMMA target. In this contribution some preliminary results about the emission profiles and the energy spectra of the detected secondaries will be presented.

A multiwire secondary emission profile monitor for small emittance beams

International Nuclear Information System (INIS)

Chehab, R.; Bonnard, J.; Humbert, G.; Leblond, B.; Saury, J.L.

1985-01-01

A secondary emission monitor using two multiwire grids separated by a positively biased collector has been constructed and tested with a 1 GeV electron beam at the Orsay Linac. The monitor installed just before the electron-positron converter has 8 gold-plated-tungsten wires of 0.1 mm diameter equally spaced 0.2 mm apart in each plane. Each wire is connected with an integrator using a low-bias current operational amplifier. The wire planes and the collector are moved into the beam by a stepping motor : that allows beam-position verification. We measured narrow profiles for 1 Amp peak current pulses of 30 nanoseconds width. Profiles are displayed on a scope and allow emittance determination by the three gradient method. Such a monitor is very useful to control the electron beam position and dimensions on the converter, because the positron source dimensions are rather bigger than those of the incident beam and the geometrical acceptance of the positron Linac is limited

Proceedings of the RCNP cascade project workshop 'heavy ion secondary beam course'

International Nuclear Information System (INIS)

1991-10-01

In the Research Center for Nuclear Physics (RCNP), Osaka University, as one of the experimental facilities utilizing the heavy ion beam from the ring cyclotron, the construction of the heavy ion secondary beam course has been in progress. This course can supply the unstable nuclei produced by a heavy ion reaction as a secondary beam, and is expected to become the powerful experimental facility for elucidating the condition of atomic nuclei in the extreme condition and their reaction mode. At present, the arrangement is advanced aiming at the utilization from the end of fiscal year 1991. Toward the start of joint utilization experiment, in order to examine the expected physics, concrete experimental plan and the preparation plan accompanying them, the workshop including the introduction of the course was held. On December 15, 1990, the workshop with the theme on the nuclear reaction by unstable nucleus beam was held, and on January 26, 1991, that with the theme on the spectroscopy of unstable nuclei was held. In each meeting, there were more than 20 participants. In this report, the gists of 18 papers are collected. (K.I.)

Setup for fission and evaporation cross-section measurements in reactions induced by secondary beams

International Nuclear Information System (INIS)

Hassan, A.A.; Luk'yanov, S.M.; Kalpakchieva, R.; Skobelev, N.K.; Penionzhkevich, Yu.Eh.; Dlouhy, Z.; Radnev, S.; Poroshin, N.V.

2002-01-01

A setup for studying reactions induced by secondary radioactive beams has been constructed. It allows simultaneous measurement of α-particle and fission fragment energy spectra. By measuring the α-particles, identification of evaporation residues is achieved. A set of three targets can be used so as to ensure sufficient statistics. Two silicon detectors, located at 90 degrees to the secondary beam direction, face each target, thus covering 30% of the solid angle. This experimental setup is to be used to obtain excitation functions of fusion-fission reactions and of reactions leading to evaporation residue production

Production of secondary radioactive beams from 44 MeV/u Ar projectiles

International Nuclear Information System (INIS)

Bimbot, R.; Della Negra, S.; Aguer, P.; Bastin, G.; Anne, R.; Delagrange, H.; Hubert, F.

1985-01-01

Secondary beams have been produced through interaction of a 1760 MeV Ar beam with a 99 mg/cm 2 Be target. An achromatic spectrometer is used to select the magnetic rigidity corresponding to a given beam, and to transport this beam over a distance of about 18 m. The beam purity is studied using a solid state ΔE-E telescope. Beams of 38 S and 39 Cl are produced with a purity of about 80% and production rates of 1.5 10 -6 Isub(o) and 5.10 -5 Isub(o) respectively. Here Isub(o) denotes the primary beam intensity. Beams of 38 Ar, 39 Ar and 41 Kr are produced with about the same abundances as 39 Cl but with lower purities. It is shown that, by setting properly the experimental parameters, the beam production can be improved by a factor 2 to 5. This could lead to intensities of about 2.10 6 pps for 38 S and of 10 7 to 10 8 pps for the four other beams. The possibility of purifying these beams by placing a degrader between the two dipoles of the spectrometer is shown experimentally

Control of secondary electrons from ion beam impact using a positive potential electrode

Energy Technology Data Exchange (ETDEWEB)

Crowley, T. P., E-mail: tpcrowley@xanthotechnologies.com; Demers, D. R.; Fimognari, P. J. [Xantho Technologies, LLC, Madison, Wisconsin 53705 (United States)

2016-11-15

Secondary electrons emitted when an ion beam impacts a detector can amplify the ion beam signal, but also introduce errors if electrons from one detector propagate to another. A potassium ion beam and a detector comprised of ten impact wires, four split-plates, and a pair of biased electrodes were used to demonstrate that a low-voltage, positive electrode can be used to maintain the beneficial amplification effect while greatly reducing the error introduced from the electrons traveling between detector elements.

Magnet power supply and beam line control for a secondary beam line K6

International Nuclear Information System (INIS)

Suzuki, Y.; Takasaki, M.; Minakawa, M.; Ishii, H.; Kato, Y.; Ieiri, M.; Tanaka, K.H.; Noumi, H.; Yamanoi, Y.

1992-01-01

K6 is a secondary separated-beam line with momentum range up to 2.0 GeV/c in the north experimental hall at the KEK 12 GeV Proton Synchrotron (KEK-PS). On the construction, newly developed magnet power supplies (MPSs), in each of them a microprocessor is embedded, are introduced. The features of the MPS are as follows: 1, The MPS is connected to an upper-level beam line controller (BLC) by GPIB highway for exchanging simple messages. 2, All the operations of the MPS are supervised by the microprocessor, which has its individual parameters and fault messages. It reduces the load of the upper-level controller. 3, The MPS has functions to inspect itself and to report the result. It saves much time and labor of maintenance. (author)

Monte Carlo modeling of ion beam induced secondary electrons

Energy Technology Data Exchange (ETDEWEB)

Huh, U., E-mail: uhuh@vols.utk.edu [Biochemistry & Cellular & Molecular Biology, University of Tennessee, Knoxville, TN 37996-0840 (United States); Cho, W. [Electrical and Computer Engineering, University of Tennessee, Knoxville, TN 37996-2100 (United States); Joy, D.C. [Biochemistry & Cellular & Molecular Biology, University of Tennessee, Knoxville, TN 37996-0840 (United States); Center for Nanophase Materials Science, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

2016-09-15

Ion induced secondary electrons (iSE) can produce high-resolution images ranging from a few eV to 100 keV over a wide range of materials. The interpretation of such images requires knowledge of the secondary electron yields (iSE δ) for each of the elements and materials present and as a function of the incident beam energy. Experimental data for helium ions are currently limited to 40 elements and six compounds while other ions are not well represented. To overcome this limitation, we propose a simple procedure based on the comprehensive work of Berger et al. Here we show that between the energy range of 10–100 keV the Berger et al. data for elements and compounds can be accurately represented by a single universal curve. The agreement between the limited experimental data that is available and the predictive model is good, and has been found to provide reliable yield data for a wide range of elements and compounds. - Highlights: • The Universal ASTAR Yield Curve was derived from data recently published by NIST. • IONiSE incorporated with the Curve will predict iSE yield for elements and compounds. • This approach can also handle other ion beams by changing basic scattering profile.

Analytical linear energy transfer model including secondary particles: calculations along the central axis of the proton pencil beam

International Nuclear Information System (INIS)

Marsolat, F; De Marzi, L; Mazal, A; Pouzoulet, F

2016-01-01

In proton therapy, the relative biological effectiveness (RBE) depends on various types of parameters such as linear energy transfer (LET). An analytical model for LET calculation exists (Wilkens’ model), but secondary particles are not included in this model. In the present study, we propose a correction factor, L sec , for Wilkens’ model in order to take into account the LET contributions of certain secondary particles. This study includes secondary protons and deuterons, since the effects of these two types of particles can be described by the same RBE-LET relationship. L sec was evaluated by Monte Carlo (MC) simulations using the GATE/GEANT4 platform and was defined by the ratio of the LET d distributions of all protons and deuterons and only primary protons. This method was applied to the innovative Pencil Beam Scanning (PBS) delivery systems and L sec was evaluated along the beam axis. This correction factor indicates the high contribution of secondary particles in the entrance region, with L sec values higher than 1.6 for a 220 MeV clinical pencil beam. MC simulations showed the impact of pencil beam parameters, such as mean initial energy, spot size, and depth in water, on L sec . The variation of L sec with these different parameters was integrated in a polynomial function of the L sec factor in order to obtain a model universally applicable to all PBS delivery systems. The validity of this correction factor applied to Wilkens’ model was verified along the beam axis of various pencil beams in comparison with MC simulations. A good agreement was obtained between the corrected analytical model and the MC calculations, with mean-LET deviations along the beam axis less than 0.05 keV μm −1 . These results demonstrate the efficacy of our new correction of the existing LET model in order to take into account secondary protons and deuterons along the pencil beam axis. (paper)

Current control of the electron beam formed in the magnetron gun with a secondary-emission cathode

International Nuclear Information System (INIS)

Dovbnya, A.N.; Reshetnyak, N.G.; Zakutin, V.V.; Chertishchev, I.A.; Romas'ko, V.P.; Dovbnyan, N.A.

2013-01-01

Data are reported on electron beam generation and beam current control in two types of secondary-emission cathode magnetron guns. The influence of the magnetic field value and field distribution on the formation of the beam and its parameters has been investigated in the electron energy range between 20 and 150 keV. The influence of local magnetic field variations on the cathode and the electron beam characteristics has been studied. The possibility to control the electron beam current in various ways has been demonstrated

Beam profile measurement of ES-200 using secondary electron emission monitor

Directory of Open Access Journals (Sweden)

E Ebrahimi Basabi

2015-09-01

Full Text Available Up to now, different designs have been introduced for measurement beam profile accelerators. Secondary electron emission monitors (SEM are one of these devices which have been used for this purpose. In this work, a SEM has been constructed to measure beam profile of ES-200 accelerator, a proton electrostatic accelerator which is installed at SBU. Profile grid for both planes designed with 16 wires which are insulated relative to each other. The particles with maximum energy of 200 keV and maximum current of 400 μA are stopped in copper wires. Each of the wires has an individual current-to-voltage amplifier. With a multiplexer, the analogue values are transported to an ADC. The ADCs are read out by a microcontroller and finally profile of beam shows by a user interface program

Evaluation of secondary electron filter for removing contaminant electrons from high-energy 6 MV x-ray beam

International Nuclear Information System (INIS)

Kumagai, Kozo

1988-01-01

When using high energy X-rays, the dose increases at the skin surface and build-up region of beam contamination of secondary electrons coming out from the inner surface of the lineac head. At our radiotherapy department, many cases of external otitis from severe skin reactions, particularly resulting from whole brain irradiation of primary and metastatic brain tumors with a 6 MV X-ray lineac, have been encountered. An investigation was made of the physical aspects of a 6 MV X-ray beam using three electron filters, lead lucite, lead glass and lucite to remove secondary electrons. Transparent materials for filters should be preferable for locating the light field. The following results were obtained: 1) For removing secondary electrons, a lead lucite filter was found best. 2) The lead lucite filter proved most effective for removing secondary electrons from the area of treatment. It reduced the dose of irradiation to the skin surface and build-up region, and furthermore improved the depth dose relative to that without filters. 3) From a clinical standpoint, skin reactions such as external otitis remarkably decreased using a lead lucite filter. 4) It thus appears necessary to use a high energy X-ray with newly designed filters to reduce beam contamination of secondary electrons. (author)

Secondary particle tracks generated by ion beam irradiation

Science.gov (United States)

García, Gustavo

2015-05-01

The Low Energy Particle Track Simulation (LEPTS) procedure is a powerful complementary tool to include the effect of low energy electrons and positrons in medical applications of radiation. In particular, for ion-beam cancer treatments provides a detailed description of the role of the secondary electrons abundantly generated around the Bragg peak as well as the possibility of using transmuted positron emitters (C11, O15) as a complement for ion-beam dosimetry. In this study we present interaction probability data derived from IAM-SCAR corrective factors for liquid environments. Using these data, single electron and positron tracks in liquid water and pyrimidine have been simulated providing information about energy deposition as well as the number and type of interactions taking place in any selected ``nanovolume'' of the irradiated area. In collaboration with Francisco Blanco, Universidad Complutense de Madrid; Antonio Mu noz, Centro de Investigaciones Energéticas Medioambientales y Tecnológicas and Diogo Almeida, Filipe Ferreira da Silva, Paulo Lim ao-Vieira, Universidade Nova de Lisboa. Supported by the Spanish and Portuguese governments.

Multigroup and coupled forward-adjoint Monte Carlo calculation efficiencies for secondary neutron doses from proton beams

International Nuclear Information System (INIS)

Kelsey IV, Charles T.; Prinja, Anil K.

2011-01-01

We evaluate the Monte Carlo calculation efficiency for multigroup transport relative to continuous energy transport using the MCNPX code system to evaluate secondary neutron doses from a proton beam. We consider both fully forward simulation and application of a midway forward adjoint coupling method to the problem. Previously we developed tools for building coupled multigroup proton/neutron cross section libraries and showed consistent results for continuous energy and multigroup proton/neutron transport calculations. We observed that forward multigroup transport could be more efficient than continuous energy. Here we quantify solution efficiency differences for a secondary radiation dose problem characteristic of proton beam therapy problems. We begin by comparing figures of merit for forward multigroup and continuous energy MCNPX transport and find that multigroup is 30 times more efficient. Next we evaluate efficiency gains for coupling out-of-beam adjoint solutions with forward in-beam solutions. We use a variation of a midway forward-adjoint coupling method developed by others for neutral particle transport. Our implementation makes use of the surface source feature in MCNPX and we use spherical harmonic expansions for coupling in angle rather than solid angle binning. The adjoint out-of-beam transport for organs of concern in a phantom or patient can be coupled with numerous forward, continuous energy or multigroup, in-beam perturbations of a therapy beam line configuration. Out-of-beam dose solutions are provided without repeating out-of-beam transport. (author)

Measurement of secondary radiation during ion beam therapy with the pixel detector Timepix

Science.gov (United States)

Martišíková, Mária; Jakubek, Jan; Granja, Carlos; Hartmann, Bernadette; Opálka, Lukáš; Pospíšil, Stanislav; Jäkel, Oliver

2011-11-01

In ion beam therapy the finite range of the ion beams in tissue and the presence of the Bragg-peak are exploited. Unpredictable changes in the patient`s condition can alter the range of the ion beam in the body. Therefore it is desired to verify the actual ion range during the treatment, preferably in a non-invasive way. Positron emission tomography (PET) has been used successfully to monitor the applied dose distributions. This method however suffers from limited applicability and low detection efficiency. In order to increase the detection efficiency and to decrease the uncertainties, in this study we investigate the possibility to measure secondary charged particles emerging from the patient during irradiation. An initial experimental study to register the particle radiation coming out of a patient phantom during the therapy was performed at the Heidelberg Ion Beam Therapy Center (HIT) in Germany. A static narrowly-focused beam of carbon ions was directed into a head phantom. The emerging secondary radiation was measured with the position-sensitive Timepix detector outside of the phantom. The detector, developed by the Medipix Collaboration, consists of a silicon sensor bump bonded to a pixelated readout chip (256 × 256 pixels with 55 μm pitch). Together with the USB-based readout interface, Timepix can operate as an active nuclear emulsion registering single particles online with 2D-track visualization. In this contribution we measured the signal behind the head phantom and investigated its dependence on the beam energy (corresponding to beam range in water 2-30 cm). Furthermore, the response was measured at four angles between 0 and 90 degrees. At all investigated energies some signal was registered. Its pattern corresponds to ions. Differences in the total amount of signal for different beam energies were observed. The time-structure of the signal is correlated with that of the incoming beam, showing that we register products of prompt processes. Such

Measurement of secondary radiation during ion beam therapy with the pixel detector Timepix

International Nuclear Information System (INIS)

Martišíková, Mária; Hartmann, Bernadette; Jäkel, Oliver; Jakubek, Jan; Granja, Carlos; Opálka, Lukáš; Pospíšil, Stanislav

2011-01-01

In ion beam therapy the finite range of the ion beams in tissue and the presence of the Bragg-peak are exploited. Unpredictable changes in the patient's condition can alter the range of the ion beam in the body. Therefore it is desired to verify the actual ion range during the treatment, preferably in a non-invasive way. Positron emission tomography (PET) has been used successfully to monitor the applied dose distributions. This method however suffers from limited applicability and low detection efficiency. In order to increase the detection efficiency and to decrease the uncertainties, in this study we investigate the possibility to measure secondary charged particles emerging from the patient during irradiation. An initial experimental study to register the particle radiation coming out of a patient phantom during the therapy was performed at the Heidelberg Ion Beam Therapy Center (HIT) in Germany. A static narrowly-focused beam of carbon ions was directed into a head phantom. The emerging secondary radiation was measured with the position-sensitive Timepix detector outside of the phantom. The detector, developed by the Medipix Collaboration, consists of a silicon sensor bump bonded to a pixelated readout chip (256 × 256 pixels with 55 μm pitch). Together with the USB-based readout interface, Timepix can operate as an active nuclear emulsion registering single particles online with 2D-track visualization. In this contribution we measured the signal behind the head phantom and investigated its dependence on the beam energy (corresponding to beam range in water 2–30 cm). Furthermore, the response was measured at four angles between 0 and 90 degrees. At all investigated energies some signal was registered. Its pattern corresponds to ions. Differences in the total amount of signal for different beam energies were observed. The time-structure of the signal is correlated with that of the incoming beam, showing that we register products of prompt processes. Such

Off-axis dose equivalent due to secondary neutrons from uniform scanning proton beams during proton radiotherapy

Science.gov (United States)

Islam, M. R.; Collums, T. L.; Zheng, Y.; Monson, J.; Benton, E. R.

2013-11-01

The production of secondary neutrons is an undesirable byproduct of proton therapy and it is important to quantify the contribution from secondary neutrons to patient dose received outside the treatment volume. The purpose of this study is to investigate the off-axis dose equivalent from secondary neutrons experimentally using CR-39 plastic nuclear track detectors (PNTD) at ProCure Proton Therapy Center, Oklahoma City, OK. In this experiment, we placed several layers of CR-39 PNTD laterally outside the treatment volume inside a phantom and in air at various depths and angles with respect to the primary beam axis. Three different proton beams with max energies of 78, 162 and 226 MeV and 4 cm modulation width, a 5 cm diameter brass aperture, and a small snout located 38 cm from isocenter were used for the entire experiment. Monte Carlo simulations were also performed based on the experimental setup using a simplified snout configuration and the FLUKA Monte Carlo radiation transport code. The measured ratio of secondary neutron dose equivalent to therapeutic primary proton dose (H/D) ranged from 0.3 ± 0.08 mSv Gy-1 for 78 MeV proton beam to 37.4 ± 2.42 mSv Gy-1 for 226 MeV proton beam. Both experiment and simulation showed a similar decreasing trend in dose equivalent with distance to the central axis and the magnitude varied by a factor of about 2 in most locations. H/D was found to increase as the energy of the primary proton beam increased and higher H/D was observed at 135° compared to 45° and 90°. The overall higher H/D in air indicates the predominance of external neutrons produced in the nozzle rather than inside the body.

Off-axis dose equivalent due to secondary neutrons from uniform scanning proton beams during proton radiotherapy

International Nuclear Information System (INIS)

Islam, M R; Collums, T L; Monson, J; Benton, E R; Zheng, Y

2013-01-01

The production of secondary neutrons is an undesirable byproduct of proton therapy and it is important to quantify the contribution from secondary neutrons to patient dose received outside the treatment volume. The purpose of this study is to investigate the off-axis dose equivalent from secondary neutrons experimentally using CR-39 plastic nuclear track detectors (PNTD) at ProCure Proton Therapy Center, Oklahoma City, OK. In this experiment, we placed several layers of CR-39 PNTD laterally outside the treatment volume inside a phantom and in air at various depths and angles with respect to the primary beam axis. Three different proton beams with max energies of 78, 162 and 226 MeV and 4 cm modulation width, a 5 cm diameter brass aperture, and a small snout located 38 cm from isocenter were used for the entire experiment. Monte Carlo simulations were also performed based on the experimental setup using a simplified snout configuration and the FLUKA Monte Carlo radiation transport code. The measured ratio of secondary neutron dose equivalent to therapeutic primary proton dose (H/D) ranged from 0.3 ± 0.08 mSv Gy −1  for 78 MeV proton beam to 37.4 ± 2.42 mSv Gy −1  for 226 MeV proton beam. Both experiment and simulation showed a similar decreasing trend in dose equivalent with distance to the central axis and the magnitude varied by a factor of about 2 in most locations. H/D was found to increase as the energy of the primary proton beam increased and higher H/D was observed at 135° compared to 45° and 90°. The overall higher H/D in air indicates the predominance of external neutrons produced in the nozzle rather than inside the body. (paper)

Experimental verification of secondary effects of prestressed beam at ULS

Directory of Open Access Journals (Sweden)

Peter Pažma

2016-03-01

Full Text Available The paper deals with secondary effects of prestressing at ultimate limit state when statically indeterminate structure has changed its structural form due to development of plastic hinges in critical cross-sections. The article presents results of an experimental program which was carried out at Slovak University of Technology in Bratislava on two span continuous beams post-tensioned by two single-strand tendons subjected to experimental load which has changed structural system into kinematic mechanism.

Contributions of secondary fragmentation by carbon ion beams in water phantom: Monte Carlo simulation

International Nuclear Information System (INIS)

Ying, C K; Bolst, David; Tran, Linh T.; Guatelli, Susanna; Rosenfeld, A. B.; Kamil, W A

2017-01-01

Heavy-particle therapy such as carbon ion therapy is currently very popular because of its superior conformality in terms of dose distribution and higher Relative Biological Effectiveness (RBE). However, carbon ion beams produce a complex mixed radiation field, which needs to be fully characterised. In this study, the fragmentation of a 290 MeV/u primary carbon ion beam was studied using the Geant4 Monte Carlo Toolkit. When the primary carbon ion beam interacts with water, secondary light charged particles (H, He, Li, Be, B) and fast neutrons are produced, contributing to the dose, especially after the distal edge of the Bragg peak. (paper)

Implementation of a secondary-ion tritium beam by means of the associated particle technique and its test on a gold target

Energy Technology Data Exchange (ETDEWEB)

Policroniades, R.; Fernández-Arnáiz, J.; Murillo, G.; Moreno, E.; Villaseñor, P.; Méndez, B. [Departamento de Aceleradores, Instituto Nacional de Investigaciones Nucleares, Carr. México-Toluca S/N, Ocoyoacac, Estado de México 52750 (Mexico); Chávez, E.; Ortíz-Salazar, M.E.; Huerta, A. [Instituto de Física, Universidad Nacional Autónoma de México, A.P. 20-364, México, D.F. 01000 (Mexico); Varela-González, A. [Centro de Ciencias de la Atmósfera, Universidad Nacional Autónoma de México, A.P. 20-364, México, D.F. 01000 (Mexico)

2014-05-21

In this work we present the implementation and characterization of a (secondary ion) tritium beam generated through the D(d,t)p reaction, at deuteron energies of 2.0 and 1.88 MeV, tagging the tritium ions with the associated particle technique. In order to prove its utility as a projectile for scientific applications, this beam was made to impinge on a thin gold target to observe expected elastic scattering events. - Highlights: • A new secondary ion tritium beam obtained through the D(d,t)3He reaction. • Tritium beam tagging by the associated particle technique. • A low energy Tritium beam without radiation contamination of equipment. • Tritium elastic scattering on gold.

Implementation of a secondary-ion tritium beam by means of the associated particle technique and its test on a gold target

International Nuclear Information System (INIS)

Policroniades, R.; Fernández-Arnáiz, J.; Murillo, G.; Moreno, E.; Villaseñor, P.; Méndez, B.; Chávez, E.; Ortíz-Salazar, M.E.; Huerta, A.; Varela-González, A.

2014-01-01

In this work we present the implementation and characterization of a (secondary ion) tritium beam generated through the D(d,t)p reaction, at deuteron energies of 2.0 and 1.88 MeV, tagging the tritium ions with the associated particle technique. In order to prove its utility as a projectile for scientific applications, this beam was made to impinge on a thin gold target to observe expected elastic scattering events. - Highlights: • A new secondary ion tritium beam obtained through the D(d,t)3He reaction. • Tritium beam tagging by the associated particle technique. • A low energy Tritium beam without radiation contamination of equipment. • Tritium elastic scattering on gold

Test beam results of a low-pressure micro-strip gas chamber with a secondary-electron emitter

International Nuclear Information System (INIS)

Kwan, S.; Anderson, D.F.; Zimmerman, J.; Sbarra, C.; Salomon, M.

1994-10-01

We present recent results, from a beam test, on the angular dependence of the efficiency and the distribution of the signals on the anode strips of a low-pressure microstrip gas chamber with a thick CsI layer as a secondary-electron emitter. New results of CVD diamond films as secondary-electron emitters are discussed

Selection of K+ mesons in a secondary beam of Saturne (1961)

International Nuclear Information System (INIS)

Van Rossum, L.

1961-01-01

The electronic device is described which permitted the determination of the number of K + mesons produced in a secondary beam of the 'Saturne' proton synchrotron. The selective criteria and the tests which allowed the identification of the K + mesons, are analysed in detail. For the ratio π + / K + = 400, and with a momentum of 600 MeV/c, less than 5 p. 100 of the detected particles corresponded to spurious events. (authors) [fr

The rapid secondary electron imaging system of the proton beam writer at CIBA

International Nuclear Information System (INIS)

Udalagama, C.N.B.; Bettiol, A.A.; Kan, J.A. van; Teo, E.J.; Watt, F.

2007-01-01

The recent years have witnessed a proliferation of research involving proton beam (p-beam) writing. This has prompted investigations into means of optimizing the process of p-beam writing so as to make it less time consuming and more efficient. One such avenue is the improvement of the pre-writing preparatory procedures that involves beam focusing and sample alignment which is centred on acquiring images of a resolution standard or sample. The conventional mode of imaging used up to now has utilized conventional nuclear microprobe signals that are of a pulsed nature and are inherently slow. In this work, we report the new imaging system that has been introduced, which uses proton induced secondary electrons. This in conjunction with software developed in-house that uses a National Instruments DAQ card with hardware triggering, facilitates large data transfer rates enabling rapid imaging. Frame rates as much as 10 frames/s have been achieved at an imaging resolution of 512 x 512 pixels

Matching Electron Beams Without Secondary Collimation for Treatment of Extensive Recurrent Chest-Wall Carcinoma

International Nuclear Information System (INIS)

Feygelman, Vladimir; Mandelzweig, Yuri; Baral, Ed

2015-01-01

Matching electron beams without secondary collimators (applicators) were used for treatment of extensive, recurrent chest-wall carcinoma. Due to the wide penumbra of such beams, the homogeneity of the dose distribution at and around the junction point is clinically acceptable and relatively insensitive to positional errors. Specifically, dose around the junction point is homogeneous to within ±4% as calculated from beam profiles, while the positional error of 1 cm leaves this number essentially unchanged. The experimental isodose distribution in an anthropomorphic phantom supports this conclusion. Two electron beams with wide penumbra were used to cover the desired treatment area with satisfactory dose homogeneity. The technique is relatively simple yet clinically useful and can be considered a viable alternative for treatment of extensive chest-wall disease. The steps are suggested to make this technique more universal.

Angular Dependence of the Ion-Induced Secondary Electron Emission for He+ and Ga+ Beams

NARCIS (Netherlands)

Castaldo, V.; Withagen, J.; Hagen, C.; Kruit, P.; Van Veldhoven, E.

2011-01-01

In recent years, novel ion sources have been designed and developed that have enabled focused ion beam machines to go beyond their use as nano-fabrication tools. Secondary electrons are usually taken to form images, for their yield is high and strongly dependent on the surface characteristics, in

SLIM (secondary emission monitor for low interception monitoring) an innovative non-destructive beam monitor for the extraction lines of a hadrontherapy centre

International Nuclear Information System (INIS)

Gibson, P.N.; Holzwarth, U.; Abbas, K.

2005-01-01

Real time monitoring of hadron therapy beam intensity and profile is a critical issue for the optimisation of dose delivery to carcinogenic tissue, patient safety and operation of the accelerator complex. For this purpose an innovative beam monitor, SLIM (Secondary electron emission for Low Interception Monitoring) is being developed in the framework of the EC-funded SUCIMA (Silicon Ultra-fast Cameras for electrons and gamma sources In Medical Application) project. The detector system is based on the secondary emission of electrons by a non-perturbative, sub-micron thick Al foil placed directly in the extracted beam path. The secondary electrons, accelerated by an electrostatic focusing system, are detected by a monolithic silicon position-sensitive sensor, which provides the beam intensity and its position with a precision of 1 mm at 10 kHz frame rate. The results of the laboratory tests of the first system prototype with thermoionic electrons emitted from a hot Tungsten wire are presented together with the measurements performed on a low intensity hadron beam at the Cyclotron of the Joint Research Centre in Ispra. (author)

The optics of secondary polarized proton beams

International Nuclear Information System (INIS)

Carey, D.C.

1990-05-01

Polarized protons can be produced by the parity-violating decay of either lambda or sigma hyperons. A secondary bema of polarized protons can then be produced without the difficult procedure of accelerating polarized protons. The preservation of the polarization while the protons are being transmitted to a final focus places stringent limitations on the optics of the beam line. The equations of motion of a polarized particle in a magnetic field have been solved to first order for quadrupole and dipole magnets. The lowest order terms indicate that the polarization vector will be restored to its original direction upon passage through a magnetic system if the momentum vector is unaltered. Higher-order terms may be derived by an expansion in commutators of the rotation matrix and its longitudinal derivative. The higher-order polarization rotation terms then arise from the non-commutivity of the rotation matrices by large angles in three-dimensional space. 5 refs., 3 figs

Multiwire secondary-emission monitor and the emittance measurement of the AGS beam

International Nuclear Information System (INIS)

Weng, W.T.; Chiang, I.H.; Smith, G.A.; Soukas, A.

1983-01-01

For CBA injection the transverse emittances and the Twiss parameters of the AGS beam have to be well defined to minimize the phase space dilution in CBA. Althoug there exists a profile monitor device at U165, there are three reasons why construction of multiwire profile monitor system at three locations from U500 to U168 is required: (1) the dispersion function is not zero at U165 which makes it harder to interpret the measurement; (2) the original single wire device takes five minutes to traverse the whole beam; (3) a three station multiwire system can provide the profile information at all locations in one pulse which makes on-line analysis possible. In summary, a set of three stations of Multiwire Secondary Emission Monitor (MSEM) has been built and installed in the fast external beam line for the measurement of beam profiles. Each unit consists of two planes each with 30 nickel wires having a diameter of 5 mils. The signal is linear within the range of 10 10 to 10 13 incident protons on the wire and the resolution of the signal is well within a few percent. A least-square fitting routine has been used to extract the emittance and phase space parameters of the beam. The emittances obtained at various intensities will help us to understand the AGS acceleration process and to choose the optimal injection scheme for CBA

Is low-energy-ion bombardment generated X-ray emission a secondary mutational source to ion-beam-induced genetic mutation?

Energy Technology Data Exchange (ETDEWEB)

Thongkumkoon, P. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Prakrajang, K. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Faculty of Science, Maejo University, Chiang Mai 50290 (Thailand); Thopan, P.; Yaopromsiri, C. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Suwannakachorn, D. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Yu, L.D., E-mail: yuld@fnrf.science.cmu.ac.th [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand)

2013-07-15

Highlights: ► Detected X-ray emission from metal, plastic and biological samples. ► Characteristic X-ray emission was detected from metal but not from non-metals. ► Low-energy ion bombarded bacteria held in different sample holders. ► Bacteria held in metal holder had higher mutation rate than in plastic holder. ► Ion-beam-induced X-ray from biological sample is not a basic mutation source. -- Abstract: Low-energy ion beam biotechnology has achieved tremendous successes in inducing crop mutation and gene transfer. However, mechanisms involved in the related processes are not yet well understood. In ion-beam-induced mutation, ion-bombardment-produced X-ray has been proposed to be one of the secondary mutation sources, but the speculation has not yet been experimentally tested. We carried out this investigation to test whether the low-energy ion-beam-produced X-ray was a source of ion-beam-induced mutation. In the investigation, X-ray emission from 29-keV nitrogen- or argon- ion beam bombarded bacterial Escherichia coli (E. coli) cells held in a metal or plastic sample holder was in situ detected using a highly sensitive X-ray detector. The ion beam bombarded bacterial cells held in different material holders were observed for mutation induction. The results led to a conclusion that secondary X-ray emitted from ion-beam-bombarded biological living materials themselves was not a, or at least a negligible, mutational source, but the ion-beam-induced X-ray emission from the metal that made the sample holder could be a source of mutation.

Is low-energy-ion bombardment generated X-ray emission a secondary mutational source to ion-beam-induced genetic mutation?

International Nuclear Information System (INIS)

Thongkumkoon, P.; Prakrajang, K.; Thopan, P.; Yaopromsiri, C.; Suwannakachorn, D.; Yu, L.D.

2013-01-01

Highlights: ► Detected X-ray emission from metal, plastic and biological samples. ► Characteristic X-ray emission was detected from metal but not from non-metals. ► Low-energy ion bombarded bacteria held in different sample holders. ► Bacteria held in metal holder had higher mutation rate than in plastic holder. ► Ion-beam-induced X-ray from biological sample is not a basic mutation source. -- Abstract: Low-energy ion beam biotechnology has achieved tremendous successes in inducing crop mutation and gene transfer. However, mechanisms involved in the related processes are not yet well understood. In ion-beam-induced mutation, ion-bombardment-produced X-ray has been proposed to be one of the secondary mutation sources, but the speculation has not yet been experimentally tested. We carried out this investigation to test whether the low-energy ion-beam-produced X-ray was a source of ion-beam-induced mutation. In the investigation, X-ray emission from 29-keV nitrogen- or argon- ion beam bombarded bacterial Escherichia coli (E. coli) cells held in a metal or plastic sample holder was in situ detected using a highly sensitive X-ray detector. The ion beam bombarded bacterial cells held in different material holders were observed for mutation induction. The results led to a conclusion that secondary X-ray emitted from ion-beam-bombarded biological living materials themselves was not a, or at least a negligible, mutational source, but the ion-beam-induced X-ray emission from the metal that made the sample holder could be a source of mutation

SU-F-J-202: Secondary Radiation Measurements for Charged Particle Therapy Monitoring: Fragmentation of Therapeutic He, C and O Ion Beams Impinging On a PMMA Target

Energy Technology Data Exchange (ETDEWEB)

Rucinski, A; Mancini-Terracciano, C; Paramatti, R; Pinci, D; Russomando, A; Voena, C [Istituto Nazionale di Fisica Nucleare - Sezione di Roma, Rome, Rome (Italy); Battistoni, G; Muraro, S [Istituto Nazionale di Fisica Nucleare - Sezione di Milano, Milano, Milano (Italy); Collamati, F; Faccini, R; Camillocci, E Solfaroli [Istituto Nazionale di Fisica Nucleare - Sezione di Roma, Italy, Dipartiment, Rome, Rome (Italy); Collini, F [Istituto Nazionale di Fisica Nucleare - Sezione di Pisa, Pisa, Pisa (Italy); De Lucia, E; Piersanti, L; Toppi, M [Laboratori Nazionali di Frascati, Frascati (rome), Rome (Italy); Frallicciardi, P [Museo Storico della Fisica e Centro Studi e Ricerche E. Fermi, Rome, Rome (Italy); Marafini, M [Istituto Nazionale di Fisica Nucleare - Sezione di Roma, Museo Storico dell, Rome, Rome (Italy); Patera, V; Sciubba, A; Traini, G [Istituto Nazionale di Fisica Nucleare - Sezione di Roma, Dipartimento di Sc, Rome, Rome (Italy); and others

2016-06-15

Purpose: In Charged Particle Therapy (CPT), besides protons, there has been recently a growing interest in 4He, 12C and 16O beams. The secondary radiation produced in the interaction of those beams with a patient could be potentially used for on-line monitoring of range uncertainties in order to fully exploit the advantages of those light ions resulting from increased Radio Biological Effectiveness, reduced multiple scattering and Oxygen Enhancement Ratio. The study and precise characterization of secondary radiation (beta+, prompt gamma, charged fragments) is the cornerstone of any R&D activity aiming for online monitoring development and purpose of the analysis presented here. Methods: We present the measurements of the secondary radiation generated by He, C and O beams impinging on a beam stopping PMMA target. The data has been collected at the Heidelberg Ionbeam Therapy center (HIT), where several millions of collisions were recorded at different energies, relevant for therapeutical applications. Results: The experimental setup, as well as the analysis strategies will be reviewed. The detected particle fluxes as a function of the primary beam energy and the emission angle with respect to the beam direction will be presented and compared to the results of other available measurements. In addition, the energy spectra and emission shapes of charged secondary particles will be shown and discussed in the context of the primary beam range monitoring technique that is being developed by the ARPG collaboration, within the INSIDE project funded by the Italian research ministry. The implications for dose monitoring applications will be discussed, in the context of the current (or planned) state-of- the-art detector solutions. Conclusion: The characterization of the radiation produced by 12C, 4He and 16O beams fully supports the feasibility of on-line range monitoring in the clinical practice of CPT by means of secondary particles detection.

SU-F-J-202: Secondary Radiation Measurements for Charged Particle Therapy Monitoring: Fragmentation of Therapeutic He, C and O Ion Beams Impinging On a PMMA Target

International Nuclear Information System (INIS)

Rucinski, A; Mancini-Terracciano, C; Paramatti, R; Pinci, D; Russomando, A; Voena, C; Battistoni, G; Muraro, S; Collamati, F; Faccini, R; Camillocci, E Solfaroli; Collini, F; De Lucia, E; Piersanti, L; Toppi, M; Frallicciardi, P; Marafini, M; Patera, V; Sciubba, A; Traini, G

2016-01-01

Purpose: In Charged Particle Therapy (CPT), besides protons, there has been recently a growing interest in 4He, 12C and 16O beams. The secondary radiation produced in the interaction of those beams with a patient could be potentially used for on-line monitoring of range uncertainties in order to fully exploit the advantages of those light ions resulting from increased Radio Biological Effectiveness, reduced multiple scattering and Oxygen Enhancement Ratio. The study and precise characterization of secondary radiation (beta+, prompt gamma, charged fragments) is the cornerstone of any R&D activity aiming for online monitoring development and purpose of the analysis presented here. Methods: We present the measurements of the secondary radiation generated by He, C and O beams impinging on a beam stopping PMMA target. The data has been collected at the Heidelberg Ionbeam Therapy center (HIT), where several millions of collisions were recorded at different energies, relevant for therapeutical applications. Results: The experimental setup, as well as the analysis strategies will be reviewed. The detected particle fluxes as a function of the primary beam energy and the emission angle with respect to the beam direction will be presented and compared to the results of other available measurements. In addition, the energy spectra and emission shapes of charged secondary particles will be shown and discussed in the context of the primary beam range monitoring technique that is being developed by the ARPG collaboration, within the INSIDE project funded by the Italian research ministry. The implications for dose monitoring applications will be discussed, in the context of the current (or planned) state-of- the-art detector solutions. Conclusion: The characterization of the radiation produced by 12C, 4He and 16O beams fully supports the feasibility of on-line range monitoring in the clinical practice of CPT by means of secondary particles detection.

Secondary Electron Yield Measurements and Groove Chambers Tests in the PEP-II Beam Line Straights Sections

International Nuclear Information System (INIS)

Pivi, M

2008-01-01

Beam instability caused by the electron cloud has been observed in positron and proton storage rings and it is expected to be a limiting factor in the performance of the positron Damping Ring (DR) of future Linear Colliders such as ILC and CLIC [1, 2]. In the Positron Low Energy Ring (LER) of the PEP-II accelerator, we have installed vacuum chambers with rectangular grooves in a straight magnetic-free section to test this promising possible electron cloud mitigation technique. We have also installed a special chamber to monitor the secondary electron yield of TiN and TiZrV (NEG) coating, Copper, Stainless Steel and Aluminum under the effect of electron and photon conditioning in situ in the beam line. In this paper, we describe the ongoing R and D effort to mitigate the electron cloud effect for the ILC damping ring, the latest results on in situ secondary electron yield conditioning and recent update on the groove tests in PEP-II

Accurate Profile Measurement of the low Intensity Secondary Beams in the CERN Experimental Areas

CERN Document Server

AUTHOR|(CDS)2084531; Tranquille, Gerard

2018-02-23

The CERN accelerators deliver a wide spectrum of secondary beams to the Experimental Areas. These beams are composed of hadrons, leptons, and heavy ions that can vary greatly in momentum (1 GeV/c to 400 GeV/c) and intensity (10^2 to 10^8 particles per second). The profile, position, and intensity of these beams are measured utilising particle detectors. However, the current systems show several problems that limit the quality of this kind of monitoring. The aim of this doctoral thesis is to investigate the best detector technology that could replace the existing monitors and build a first prototype of it. A review of the existing detection techniques has led to the choice of Scintillating Fibres (SciFi) read-out with Silicon Photomultipliers (SiPM). This detection technology has the potential to perform better in terms of material budget, range of intensities measured, and active area size. In addition, it has particle counting capabilities, which could extend its application to momentum spectrometry or Time...

Mass spectrum of secondary ions knocked-out from copper surface by argon ion beam

International Nuclear Information System (INIS)

Koval', A.G.; Bobkov, V.V.; Klimovskij, Yu.A.; Fogel', Ya.M.

1976-01-01

The mass-spectrum of secondary ions was studied within a mass range of 1-400. The ions were knocked-out by the beam of ions Ar + from the copper surface with different content of oxygen and sulphur solved in the volume. The studies were conducted at three temperatures of the target. The atomic and molecular ions of the metal matrix, volumetric impurities of metal and ions of chemical compounds molecules of the metal under study with gas particles adsorbed on its surface and atoms of the metal volumetric admixtures may be observed in the mass spectrum. Detection of secondary ions of the copper multi-atomic complexes and ions of these complexes compounds with the adsorbed molecules is of interest

Reduction of the energy of secondary beams down to the Coulomb barrier

International Nuclear Information System (INIS)

Yang Yong Feng; Mittig, W.; Roussel-Chomaz, P.; Lewitowicz, M.; Sida, J.L.; Alamanos, N.; Auger, F.; Gillibert, A.; Volant, C.; Cabot, C.; Borcea, C.

1993-01-01

With the doubly achromatic spectrometer LISE at GANIL, the energy of a secondary 11 Be beam produced by the reaction of 63 MeV/nucleon 18 O with a 9 Be target has been reduced to Coulomb barrier energies using various thick targets and a thinner target plus a thick degrader. The experimental results were compared with calculations performed with the program INTENSITY and with simple analytical expressions. It was found that in the present device, the thick target method is more convenient and efficient than the achromatic degrader

Coronary cineangiography and ionizing radiation exposure to patients: analysis of primary and secondary beam

International Nuclear Information System (INIS)

Ramirez, Alfredo; Leyton, Fernando; Silva, Ana Maria; Farias, Eric

2001-01-01

The purpose of this work was to determine the level of exposure dose to patients during coronariographies in different areas of body. This study has presented the medical surveillance of 18 cases and the radiation monitoring of these patients by TLD in thyroid and pelvis (secondary beam) and, in the right and left scapular region (primary beam) for each one of these procedures. The ionizing radiation received was 215 ± 200 mGy in left scapular region (range 1-710) and 255±213 mGy in the right scapular region (range 22-635) p=NS. In the pelvic region the ionizing radiation was 0,22±0,06 mGy and in the thyroid region was 3,62±2,44 mGy

Radioactive beam production at the Bevalac

International Nuclear Information System (INIS)

Alonso, J.R.; Feinberg, B.; Kalnins, J.G.; Krebs, G.F.; McMahan, M.A.; Tanihata, I.

1989-10-01

At the Bevalac radioactive beams are routinely produced by the fragmentation process. The effectiveness of this process with respect to the secondary beam's emittance, intensity and energy spread depends critically on the nuclear reaction kinematics and the magnitude of the incident beam energy. When this beam energy significantly exceeds the energies of the nuclear reaction process, many of the qualities of the incident beam can be passed on to the secondary beam. Factors affecting secondary beam quality are discussed along with techniques for isolating and purifying a specific reaction product. The on-going radioactive beam program at the Bevalac is used as an example with applications, present performance and plans for the future. 6 refs., 6 figs., 1 tab

Isotope separation of relativistic projectile fragments as well as cross section measurements on 8,9,11Li secondary beams

International Nuclear Information System (INIS)

Blank, B.

1991-06-01

In the framework of this thesis the method of the 'momentum-loss achromate' was for the first time tested at relativistic energies. This experiment is presented in chapter 2 of the thesis. In a second experiment the method was then used, in order to make secondary beams of 8,9,11 Li available. With these secondary beams cross section measurements were performed, from which beside information on the nuclear radii of these nuclei also further information on the internal structure of the lithium isotopes can be derived. This experiment is described in chapter 3 of the thesis. In the framework of these two experiments for the applied heavy ions energy-loss measurements were performed. The results of these measurements are presented in chapter 4. (orig.) [de

The cedar counters for particle identification in the SPS secondary beams: A description and an operation manual

International Nuclear Information System (INIS)

Bovet, C.; Maleyran, R.; Piemontese, L.; Placci, A.; Placidi, M.

1982-01-01

The Cerenkov Differential counter with Achromatic Ring Focus (Cedar) has been designed and a number built at Cern for the identification (and selection) of particles in the secondary beams of a high-energy accelerator. Cedar-N can separate kaons from pions up to 300 GeV/c but can detect protons only down to 60 GeV/c; Cedar-W can flag protons of 12 GeV/c and separate kaons from pions up to 150 GeV/c. After a brief account of the relevant physics of the Cerenkov effect, this report describes Cedars with emphasis on those characteristics and construction features that are of interest to the user. Details are given of the high-precision optical system, the mechanical construction to achieve uniform temperature (0.1 K) and rigidity, and the gas handling and measurement. The layout of the Cedars in the secondary beams of the Cern Super Proton Synchrotron is described. The signals provided to the user are listed and explained, together with the programs for on-line control of the counters. Details are given of the performances attained, together with various hints and suggestions on the procedure to follow in order to set-up, tune, and operate a Cedar. The dependence of the performance on beam optics is stressed. (orig.)

Secondary beam line phase space measurement and modeling at LAMPF

International Nuclear Information System (INIS)

Floyd, R.; Harrison, J.; Macek, R.; Sanders, G.

1979-01-01

Hardware and software have been developed for precision on-line measurement and fitting of secondary beam line phase space parameters. A system consisting of three MWPC planes for measuring particle trajectories, in coincidence with a time-of-flight telescope and a range telescope for particle identification, has been interfaced to a computer. Software has been developed for on-line track reconstruction, application of experimental cuts, and fitting of two-dimensional phase space ellipses for each particle species. The measured distributions have been found to agree well with the predictions of the Monte Carlo program DECAY TURTLE. The fitted phase space ellipses are a useful input to optimization routines, such as TRANSPORT, used to search for superior tunes. Application of this system to the LAMPF Stopped Muon Channel is described

Analysis of secondary particle behavior in multiaperture, multigrid accelerator for the ITER neutral beam injector.

Science.gov (United States)

Mizuno, T; Taniguchi, M; Kashiwagi, M; Umeda, N; Tobari, H; Watanabe, K; Dairaku, M; Sakamoto, K; Inoue, T

2010-02-01

Heat load on acceleration grids by secondary particles such as electrons, neutrals, and positive ions, is a key issue for long pulse acceleration of negative ion beams. Complicated behaviors of the secondary particles in multiaperture, multigrid (MAMuG) accelerator have been analyzed using electrostatic accelerator Monte Carlo code. The analytical result is compared to experimental one obtained in a long pulse operation of a MeV accelerator, of which second acceleration grid (A2G) was removed for simplification of structure. The analytical results show that relatively high heat load on the third acceleration grid (A3G) since stripped electrons were deposited mainly on A3G. This heat load on the A3G can be suppressed by installing the A2G. Thus, capability of MAMuG accelerator is demonstrated for suppression of heat load due to secondary particles by the intermediate grids.

Consideration of fluctuation in secondary beam intensity of heavy ion beam probe measurements

Energy Technology Data Exchange (ETDEWEB)

Fujisawa, A.; Iguchi, H.; Lee, S.; Hamada, Y.

1997-01-01

Heavy ion beam probes have capability to detect local electron density fluctuation in the interior of plasmas through the detected beam intensity fluctuation. However, the intensity fluctuation should suffer a certain degree of distortion from electron density and temperature fluctuations on the beam orbits, and as a result the signal can be quite different from the local density fluctuation. This paper will present a condition that the intensity fluctuation can be regarded as being purely local electron density fluctuation, together with discussion about the contamination of the fluctuation along the beam orbits to the beam intensity fluctuation. (author)

High purity radioactive beams at the bevalac

International Nuclear Information System (INIS)

Alonso, J.R.; Chatterjee, A.; Tobias, C.A.

1979-03-01

Peripheral nuclear fragmentation reactions of primary Bevalac heavy ion beams are used to produce secondary beams of radioactive nuclei. The large cross section and small deflection of the projectile fragments lead to high production and delivery efficiency for these beams. Dispersive beam transport allows good separation and purification of the desired secondary beams. 11 C and 19 Ne beams of high purity and good intensity (almost 0.2% of the primary beam current) are presently being used for biomedical experiments

Study of electron beam effects on surfaces using x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS)

International Nuclear Information System (INIS)

Gettings, M.; Coad, J.P.

1976-02-01

Discrepancies in the surface analyses of oxidised or heavily contaminated materials have been observed between X-ray Photoelectron Spectroscopy (XPS) and techniques using electron beams (primarily Auger Electron Spectroscopy (AES)). These discrepancies can be ascribed to the influence of the primary electron beam and to illustrate the various types of electron effects different materials were analysed using XPS and Secondary Ion Mass Spectroscopy (SIMS) before and after large area electron bombardment. The materials used included chrome and stainless steels, nickel, platinum, glass and brass. (author)

Polarized secondary radioactive beams

International Nuclear Information System (INIS)

Zaika, N.I.

1992-01-01

Three methods of polarized radioactive nuclei beam production: a) a method nuclear interaction of the non-polarized or polarized charged projectiles with target nuclei; b) a method of polarization of stopped reaction radioactive products in a special polarized ion source with than following acceleration; c) a polarization of radioactive nuclei circulating in a storage ring are considered. Possible life times of the radioactive ions for these methods are determined. General schemes of the polarization method realizations and depolarization problems are discussed

Production of an 15O beam using a stable oxygen ion beam for in-beam PET imaging

Science.gov (United States)

Mohammadi, Akram; Yoshida, Eiji; Tashima, Hideaki; Nishikido, Fumihiko; Inaniwa, Taku; Kitagawa, Atsushi; Yamaya, Taiga

2017-03-01

In advanced ion therapy, the 15O ion beam is a promising candidate to treat hypoxic tumors and simultaneously monitor the delivered dose to a patient using PET imaging. This study aimed at production of an 15O beam by projectile fragmentation of a stable 16O beam in an optimal material, followed by in-beam PET imaging using a prototype OpenPET system, which was developed in the authors' group. The study was carried out in three steps: selection of the optimal target based on the highest production rate of 15O fragments; experimental production of the beam using the optimal target in the Heavy Ion Medical Accelerator Chiba (HIMAC) secondary beam course; and realization of in-beam PET imaging for the produced beam. The optimal target evaluations were done using the Monte Carlo simulation code PHITS. The fluence and mean energy of the secondary particles were simulated and the optimal target was selected based on the production rate of 15O fragments. The highest production rate of 15O was observed for a liquid hydrogen target, 3.27% for a 53 cm thick target from the 16O beam of 430 MeV/u. Since liquid hydrogen is not practically applicable in the HIMAC secondary beam course a hydrogen-rich polyethylene material, which was the second optimal target from the simulation results, was selected as the experimental target. Three polyethylene targets with thicknesses of 5, 11 or 14 cm were used to produce the 15O beam without any degrader in the beam course. The highest production rate was measured as around 0.87% for the 11 cm thick polyethylene target from the 16O beam of 430 MeV/u when the angular acceptance and momentum acceptance were set at ±13 mrad and ±2.5%, respectively. The purity of the produced beam for the three targets were around 75%, insufficient for clinical application, but it was increased to 97% by inserting a wedge shape aluminum degrader with a thickness of 1.76 cm into the beam course and that is sufficiently high. In-beam PET imaging was also

Experimental Observations of In-Situ Secondary Electron Yield Reduction in the PEP-II Particle Accelerator Beam Line

International Nuclear Information System (INIS)

Pivi, Mauro

2010-01-01

Beam instability caused by the electron cloud has been observed in positron and proton storage rings and it is expected to be a limiting factor in the performance of the positron Damping Ring (DR) of future Linear Colliders (LC) such as ILC and CLIC. To test a series of promising possible electron cloud mitigation techniques as surface coatings and grooves, in the Positron Low Energy Ring (LER) of the PEP-II accelerator, we have installed several test vacuum chambers including (i) a special chamber to monitor the variation of the secondary electron yield of technical surface materials and coatings under the effect of ion, electron and photon conditioning in situ in the beam line; (ii) chambers with grooves in a straight magnetic-free section; and (iii) coated chambers in a dedicated newly installed 4-magnet chicane to study mitigations in a magnetic field region. In this paper, we describe the ongoing R and D effort to mitigate the electron cloud effect for the LC damping ring, focusing on the first experimental area and on results of the reduction of the secondary electron yield due to in situ conditioning.

Revised data taking schedule with ion beams

CERN Document Server

Gazdzicki, Marek; Aduszkiewicz, A; Andrieu, B; Anticic, T; Antoniou, N; Argyriades, J; Asryan, A G; Baatar, B; Blondel, A; Blumer, J; Boldizsar, L; Bravar, A; Brzychczyk, J; Bubak, A; Bunyatov, S A; Choi, K U; Christakoglou, P; Chung, P; Cleymans, J; Derkach, D A; Diakonos, F; Dominik, W; Dumarchez, J; Engel, R; Ereditato, A; Feofilov, G A; Fodor, Z; Ferrero, A; Gazdzicki, M; Golubeva, M; Grebieszkow, K; Grzeszczuk, A; Guber, F; Hasegawa, T; Haungs, A; Igolkin, S; Ivanov, A S; Ivashkin, A; Kadija, K; Katrynska, N; Kielczewska, D; Kikola, D; Kisiel, J; Kobayashi, T; Kolesnikov, V I; Kolev, D; Kolevatov, R S; Kondratiev, V P; Kowalski, S; Kurepin, A; Lacey, R; Laszlo, A; Lyubushkin, V V; Majka, Z; I Malakhov, A; Marchionni, A; Marcinek, A; Maris, I; Matveev, V; Melkumov, G L; Meregaglia, A; Messina, M; Mijakowski, P; Mitrovski, M; Montaruli, T; Mrówczynski, St; Murphy, S; Nakadaira, T; Naumenko, P A; Nikolic, V; Nishikawa, K; Palczewski, T; Pálla, G; Panagiotou, A D; Peryt, W; Planeta, R; Pluta, J; Popov, B A; Posiadala, M; Przewlocki, P; Rauch, W; Ravonel, M; Renfordt, R; Röhrich, D; Rondio, E; Rossi, B; Roth, M; Rubbia, A; Rybczynski, M; Sadovskii, A; Sakashita, K; Schuster, T; Sekiguchi, T; Seyboth, P; Shibata, M; Sissakian, A N; Skrzypczak, E; Slodkowski, M; Sorin, A S; Staszel, P; Stefanek, G; Stepaniak, J; Strabel, C; Ströbele, H; Susa, T; Szentpétery, I; Szuba, M; Tada, M; Taranenko, A; Tsenov, R; Ulrich, R; Unger, M; Vassiliou, M; Vechernin, V V; Vesztergombi, G; Wlodarczyk, Z; Wojtaszek, A; Zipper, W; CERN. Geneva. SPS and PS Experiments Committee; SPSC

2009-01-01

This document presents the revised data taking schedule of NA61 with ion beams. The revision takes into account limitations due to the new LHC schedule as well as final results concerning the physics performance with secondary ion beams. It is proposed to take data with primary Ar and Xe beams in 2012 and 2014, respectively, and to test and use for physics a secondary B beam from primary Pb beam fragmentation in 2010, 2011 and 2013.

Production of an {sup 15}O beam using a stable oxygen ion beam for in-beam PET imaging

Energy Technology Data Exchange (ETDEWEB)

Mohammadi, Akram, E-mail: mohammadi.akram@qst.go.jp; Yoshida, Eiji; Tashima, Hideaki; Nishikido, Fumihiko; Inaniwa, Taku; Kitagawa, Atsushi; Yamaya, Taiga

2017-03-21

In advanced ion therapy, the {sup 15}O ion beam is a promising candidate to treat hypoxic tumors and simultaneously monitor the delivered dose to a patient using PET imaging. This study aimed at production of an {sup 15}O beam by projectile fragmentation of a stable {sup 16}O beam in an optimal material, followed by in-beam PET imaging using a prototype OpenPET system, which was developed in the authors’ group. The study was carried out in three steps: selection of the optimal target based on the highest production rate of {sup 15}O fragments; experimental production of the beam using the optimal target in the Heavy Ion Medical Accelerator Chiba (HIMAC) secondary beam course; and realization of in-beam PET imaging for the produced beam. The optimal target evaluations were done using the Monte Carlo simulation code PHITS. The fluence and mean energy of the secondary particles were simulated and the optimal target was selected based on the production rate of {sup 15}O fragments. The highest production rate of {sup 15}O was observed for a liquid hydrogen target, 3.27% for a 53 cm thick target from the {sup 16}O beam of 430 MeV/u. Since liquid hydrogen is not practically applicable in the HIMAC secondary beam course a hydrogen-rich polyethylene material, which was the second optimal target from the simulation results, was selected as the experimental target. Three polyethylene targets with thicknesses of 5, 11 or 14 cm were used to produce the {sup 15}O beam without any degrader in the beam course. The highest production rate was measured as around 0.87% for the 11 cm thick polyethylene target from the {sup 16}O beam of 430 MeV/u when the angular acceptance and momentum acceptance were set at ±13 mrad and ±2.5%, respectively. The purity of the produced beam for the three targets were around 75%, insufficient for clinical application, but it was increased to 97% by inserting a wedge shape aluminum degrader with a thickness of 1.76 cm into the beam course and that is

Lise: a recoil spectrometer at GANIL for the production and study of secondary radioactive beams. Present status and future

International Nuclear Information System (INIS)

Mueller, A.C.

1989-01-01

The doubly achromatic spectrometer LISE, installed at the intermediate-energy heavy-ion facility GANIL is now operating since five years. Essentially, it is composed by two dipole-magnets selecting (in A/Z) and refocusing (achromatically) the projectile-like radioactive fragment-beams emitted at 0 0 . We shall review some of the essential properties of LISE. Some selected examples will be used to demonstrate experimental results which have been obtained so far (discovery of numerous new nuclei up to the drip-lines, half-life measurements, β-γ and delayed-particle spectroscopy, spin-aligned beams, total reaction cross-sections). We shall also discuss several improvements, in particular a cross-field electrostatic/electromagnetic post separator, which are expected to provide in the near future secondary beams of still increased intensity and isotopic purity

Electron-beam-induced-current and active secondary-electron voltage-contrast with aberration-corrected electron probes

Energy Technology Data Exchange (ETDEWEB)

Han, Myung-Geun, E-mail: mghan@bnl.gov [Condensed Matter Physics & Materials Science, Brookhaven National Laboratory, Upton, NY 11973 (United States); Garlow, Joseph A. [Condensed Matter Physics & Materials Science, Brookhaven National Laboratory, Upton, NY 11973 (United States); Materials Science and Engineering Department, Stony Brook University, Stony Brook, NY 11794 (United States); Marshall, Matthew S.J.; Tiano, Amanda L. [Department of Chemistry, Stony Brook University, Stony Brook, NY 11974 (United States); Wong, Stanislaus S. [Condensed Matter Physics & Materials Science, Brookhaven National Laboratory, Upton, NY 11973 (United States); Department of Chemistry, Stony Brook University, Stony Brook, NY 11974 (United States); Cheong, Sang-Wook [Department of Physics and Astronomy, Rutgers Center for Emergent Materials, Rutgers University, Piscataway, NJ 08854 (United States); Walker, Frederick J.; Ahn, Charles H. [Department of Applied Physics and Center for Research on Interface Structures and Phenomena, Yale University, New Haven, CT 06520 (United States); Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT 06520 (United States); Zhu, Yimei [Condensed Matter Physics & Materials Science, Brookhaven National Laboratory, Upton, NY 11973 (United States)

2017-05-15

Highlights: • Electron-beam-induced-current (EBIC) and active secondary-electron voltage-contrast (SE-VC) are demonstrated in STEM mode combined with in situ electrical biasing in a TEM. • Electrostatic potential maps in ferroelectric thin films, multiferroic nanowires, and single crystals obtained by off-axis electron holography were compared with EBIC and SE-VC data. • Simultaneous EBIC and active SE-VC performed with atomic resolution STEM are demonstrated. - Abstract: The ability to map out electrostatic potentials in materials is critical for the development and the design of nanoscale electronic and spintronic devices in modern industry. Electron holography has been an important tool for revealing electric and magnetic field distributions in microelectronics and magnetic-based memory devices, however, its utility is hindered by several practical constraints, such as charging artifacts and limitations in sensitivity and in field of view. In this article, we report electron-beam-induced-current (EBIC) and secondary-electron voltage-contrast (SE-VC) with an aberration-corrected electron probe in a transmission electron microscope (TEM), as complementary techniques to electron holography, to measure electric fields and surface potentials, respectively. These two techniques were applied to ferroelectric thin films, multiferroic nanowires, and single crystals. Electrostatic potential maps obtained by off-axis electron holography were compared with EBIC and SE-VC to show that these techniques can be used as a complementary approach to validate quantitative results obtained from electron holography analysis.

Diagnostic performance of cone-beam computed tomography on detection of mechanically-created artificial secondary caries

Energy Technology Data Exchange (ETDEWEB)

Charuakkra, Arnon; Prapayasatok, Sangsom; Janhom, Apirum; Pongsirwet, Surawut; Verochana, Karune; Mahasantipiya, Phattaranant [Faculty of Dentistry, Chiang Mai University, Chiang Mai (Thailand)

2011-12-15

The aim of this study was to compare the diagnostic accuracy of cone-beam computed tomography (CBCT) images and bitewing images in detection of secondary caries. One hundred and twenty proximal slots of Class II cavities were randomly prepared on human premolar and molar teeth, and restored with amalgam (n=60) and composite resin (n=60). Then, artificial secondary caries lesions were randomly created using round steel No. 4 bur. The teeth were radiographed with a conventional bitewing technique and two CBCT systems; Pax-500ECT and Promax 3D. All images were evaluated by five observers. The area under the receiver operating characteristic (ROC) curve (Az) was used to evaluate the diagnostic accuracy. Significant difference was tested using the Friedman test (p value<0.05). The mean Az values for bitewing, Pax-500ECT, and Promax 3D imaging systems were 0.882, 0.995, and 0.978, respectively. Significant differences were found between the two CBCT systems and film (p=0.007). For CBCT systems, the axial plane showed the greatest Az value. Based on the design of this study, CBCT images were better than bitewing radiographs in detection of secondary caries.

Diagnostic performance of cone-beam computed tomography on detection of mechanically-created artificial secondary caries

International Nuclear Information System (INIS)

Charuakkra, Arnon; Prapayasatok, Sangsom; Janhom, Apirum; Pongsirwet, Surawut; Verochana, Karune; Mahasantipiya, Phattaranant

2011-01-01

The aim of this study was to compare the diagnostic accuracy of cone-beam computed tomography (CBCT) images and bitewing images in detection of secondary caries. One hundred and twenty proximal slots of Class II cavities were randomly prepared on human premolar and molar teeth, and restored with amalgam (n=60) and composite resin (n=60). Then, artificial secondary caries lesions were randomly created using round steel No. 4 bur. The teeth were radiographed with a conventional bitewing technique and two CBCT systems; Pax-500ECT and Promax 3D. All images were evaluated by five observers. The area under the receiver operating characteristic (ROC) curve (Az) was used to evaluate the diagnostic accuracy. Significant difference was tested using the Friedman test (p value<0.05). The mean Az values for bitewing, Pax-500ECT, and Promax 3D imaging systems were 0.882, 0.995, and 0.978, respectively. Significant differences were found between the two CBCT systems and film (p=0.007). For CBCT systems, the axial plane showed the greatest Az value. Based on the design of this study, CBCT images were better than bitewing radiographs in detection of secondary caries.

Dose distribution of secondary radiation in a water phantom for a proton pencil beam-EURADOS WG9 intercomparison exercise

Czech Academy of Sciences Publication Activity Database

Stolarczyk, L.; Trinkl, S.; Romero-Exposito, M.; Mojzeszek, N.; Ambrožová, Iva; Domingo, C.; Davídková, Marie; Farah, J.; Klodowska, M.; Kneževic, Z.; Liszka, M.; Majer, M.; Miljanic, S.; Ploc, Ondřej; Schwarz, M.; Harrison, R. M.; Olko, P.

2018-01-01

Roč. 63, č. 8 (2018), č. článku 085017. ISSN 0031-9155 Institutional support: RVO:61389005 Keywords : passive detectors * neutron dosimetry * gamma radiation dosimetry * water phantom measurements * secondary radiation measurements * pencil beam scanning proton radiotherapy Subject RIV: FP - Other Medical Disciplines OBOR OECD: Radiology, nuclear medicine and medical imaging Impact factor: 2.742, year: 2016

The role of charged secondaries from nonelastic nuclear interactions by therapy proton beams in a PERSPEX target

International Nuclear Information System (INIS)

Mesa, Joel; Gomes, Viviam da Silva; Evseev, Ivan

2007-01-01

The dose distribution delivered in charged particle therapy is due to both primary and secondary particles. The inclusion of the proton induced non-elastic nuclear reactions in the absorbed dose calculations carried out in proton-therapy, can modify the absorbed dose in two ways: by changing the energy spectrum as consequence of the primary proton fluence decreasing, and by giving rise to secondary products (i.e. p, n, α, d, t, 3 He) which contribute to the absorbed energy, thus affecting the irradiated target, as well as critical organs outside the target volume, besides enhancing the biological dose due to the high LET values. In this preliminary work, the dose distributions from primary and secondary charged particles for a pencil beam of protons with energies between 100 and 200 MeV in a PERSPEX (PMMA, Polymethyl Methacrylate, Lucite or Plexiglass) target was studied theoretically in the continuous-slowing-down-approximation (CSDA) considering secondary particles energy spectra. In this sense, we have used a quite sophisticate multicollisional Monte Carlo code (MCMC) for pre-equilibrium emission, plus de-excitation of residual nucleus by fragmentation process. (author)

Estimate of the shielding effect on secondary cancer risk due to cone-beam CT in image-guided radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Sung, Jiwon; Baek, Taeseong; Yoon, Myonggeun [Korea University, Seoul (Korea, Republic of); Kim, Dongwook; Kim, Donghyun [Kyung Hee University Hospital at Gangdong, Seoul (Korea, Republic of)

2014-09-15

This study evaluated the effect of a simple shielding method using a thin lead sheet on the imaging dose caused by cone-beam computed tomography (CBCT) in image-guided radiation therapy (IGRT). Reduction of secondary doses from CBCT was measured using a radio-photoluminescence glass dosimeter (RPLGD) placed inside an anthropomorphic phantom. The entire body, except for the region scanned by using CBCT, was shielded by wrapping it with a 2-mm lead sheet. Changes in secondary cancer risk due to shielding were calculated using BEIR VII models. Doses to out-of-field organs for head-and-neck, chest, and pelvis scans were decreased 15 ∼ 100%, 23 ∼ 90%, and 23 ∼ 98%, respectively, and the average reductions in lifetime secondary cancer risk due to the 2-mm lead shielding were 1.6, 11.5, and 12.7 persons per 100,000, respectively. These findings suggest that a simple, thin-lead-sheet-based shielding method can effectively decrease secondary doses to out-of-field regions for CBCT, which reduces the lifetime cancer risk on average by 9 per 100,000 patients.

Beam diagnostics for low energy beams

Directory of Open Access Journals (Sweden)

J. Harasimowicz

2012-12-01

Full Text Available Low-energetic ion and antimatter beams are very attractive for a number of fundamental studies. The diagnostics of such beams, however, is a challenge due to low currents down to only a few thousands of particles per second and significant fraction of energy loss in matter at keV beam energies. A modular set of particle detectors has been developed to suit the particular beam diagnostic needs of the ultralow-energy storage ring (USR at the future facility for low-energy antiproton and ion research, accommodating very low beam intensities at energies down to 20 keV. The detectors include beam-profile monitors based on scintillating screens and secondary electron emission, sensitive Faraday cups for absolute intensity measurements, and capacitive pickups for beam position monitoring. In this paper, the design of all detectors is presented in detail and results from beam measurements are shown. The resolution limits of all detectors are described and options for further improvement summarized. Whilst initially developed for the USR, the instrumentation described in this paper is also well suited for use in other low-intensity, low-energy accelerators, storage rings, and beam lines.

Calculated intensity of high-energy neutron beams

International Nuclear Information System (INIS)

Mustapha, B.; Nolen, J.A.; Back, B.B.

2004-01-01

The flux, energy and angular distributions of high-energy neutrons produced by in-flight spallation and fission of a 400 MeV/A 238 U beam and by the break-up of a 400 MeV/A deuteron beam are calculated. In both cases very intense secondary neutron beams are produced, peaking at zero degrees, with a relatively narrow energy spread. Such secondary neutron beams can be produced with the primary beams from the proposed rare isotope accelerator driver linac. The break-up of a 400 kW deuteron beam on a liquid-lithium target can produce a neutron flux of >10 10 neutrons/cm 2 /s at a distance of 10 m from the target

Secondary reactions as a tool to produce exotic nuclei

International Nuclear Information System (INIS)

Dufour, J.P.; Fleury, A.; Bimbot, R.

1980-01-01

The possibility of using secondary reactions as tool to produce new isotopes is considered. This question is renewed with the emergence of intense beams of energetic heavy ions in the range of 20 to 100 MeV/nucleon. Three different methods are considered. They involve either the 'in situ' production of a secondary radioactive target, which interacts with the primary beam, or the production of a radioactive secondary beam by an inverse fusion or a fragmentation process. Very heavy or very neutron deficient isotopes can be produced by these methods

Beam intensity monitoring for the external proton beam at LAMPF

International Nuclear Information System (INIS)

Barrett, R.J.; Anderson, B.D.; Willard, H.B.; Anderson, A.N.; Jarmie, N.

1975-07-01

Three different intensity monitors were tested in the external proton beam at LAMPF, and together cover the entire range of beam currents available. A 800 kg Faraday cup was installed and used to measure the absolute intensity to better than 1 percent for beam currents up to several nanoamperes. A high gain ion chamber was used as part of the calibration procedure for the Faraday cup, and was found to be useful when monitoring very small beam intensities, being reliable down to the few picoampere level. A secondary emission monitor was also tested, calibrated, and found to be trustworthy only for beams of greater than 50 pA intensity. (auth)

Simulation of the Production of Secondary Particles from a Neutron Beam on Polyethylene Targets using the GEANT4 Simulation Tool

CERN Document Server

Ilgner, C

2003-01-01

In view of a beam test of RadFET semiconductor detectors and optically stimulated luminescence (OSL) detectors as on-line dosimeters for radiation monitoring purposes in the caverns of the Large Hadron Collider (LHC) experiments, a simulation on the production of secondary particles from a neutron beam on a polyethylene target was carried out. We describe the yield of recoil protons, scattered neutrons as well as electrons, positrons and photons, when neutrons of an average energy of 20 MeV hit polyethylene targets of several thicknesses. The simulation was carried out using the latest release 5.2 of the GEANT4 detector description and simulation tool, including advanced hadron interaction models.

Numerical Simulations for the Beam-Induced Electron Cloud in the LHC Beam Screen

CERN Document Server

Brüning, Oliver Sim

1998-01-01

The following work summarises simulation results obtained at CERN for the beam-induced electron cloud and looks at possible cures for the heat load in the LHC beam screen. The synchrotron radiation in the LHC creates a continuous flow of photoelectrons. These electrons are accelerated by the electric field of the bunch and hit the vacuum chamber on the opposite side of the beam pipe where they crea te secondary electrons which are again accelerated by the next bunch. For a large secondary emission yield the above mechanism leads to an exponential growth of the electron cloud which is limited by space charge forces. The simulations use a two-dimensional mesh for the space charge calculations and include the effect of image charges on the vacuum chamber wall. Depending on the quantum yield for the production of photoelectrons, the secondary emission yield and the reflectivity, the heat load can vary from 0.1 W/m to more than 15 W/m.

Secondary beam monitors for the NuMI facility at FNAL

International Nuclear Information System (INIS)

Kopp, S.; Bishai, M.; Dierckxsens, M.; Diwan, M.; Erwin, A.R.; Harris, D.A.; Indurthy, D.; Keisler, R.; Kostin, M.; Lang, M.; MacDonald, J.; Marchionni, A.; Mendoza, S.; Morfin, J.; Naples, D.; Northacker, D.; Pavlovic, Z.; Phelps, L.; Ping, H.; Proga, M.; Vellissaris, C.; Viren, B.; Zwaska, R.

2006-01-01

The Neutrinos at the Main Injector (NuMI) facility is a conventional neutrino beam which produces muon neutrinos by focusing a beam of mesons into a long evacuated decay volume. We have built four arrays of ionization chambers to monitor the position and intensity of the hadron and muon beams associated with neutrino production at locations downstream of the decay volume. This article describes the chambers' construction, calibration, and commissioning in the beam

Secondary emission electron gun using external primaries

Science.gov (United States)

Srinivasan-Rao, Triveni [Shoreham, NY; Ben-Zvi, Ilan [Setauket, NY

2009-10-13

An electron gun for generating an electron beam is provided, which includes a secondary emitter. The secondary emitter includes a non-contaminating negative-electron-affinity (NEA) material and emitting surface. The gun includes an accelerating region which accelerates the secondaries from the emitting surface. The secondaries are emitted in response to a primary beam generated external to the accelerating region. The accelerating region may include a superconducting radio frequency (RF) cavity, and the gun may be operated in a continuous wave (CW) mode. The secondary emitter includes hydrogenated diamond. A uniform electrically conductive layer is superposed on the emitter to replenish the extracted current, preventing charging of the emitter. An encapsulated secondary emission enhanced cathode device, useful in a superconducting RF cavity, includes a housing for maintaining vacuum, a cathode, e.g., a photocathode, and the non-contaminating NEA secondary emitter with the uniform electrically conductive layer superposed thereon.

Numerical investigation of out-of-plane secondary stress in the web of floor beam of steel truss bridge. Ko torasu kyo no yukageta web ni shojiru mengai niji oryoku no suchiteki gen'in bunseki

Energy Technology Data Exchange (ETDEWEB)

Sato, T. (Kisarazu National College of Technology, Chiba (Japan)); Kuranishi, S. (Kanto Gakuin Univ., Kanagawa (Japan). Faculty of Engineering); Nakazawa, M. (Tohoku Univ., Sendai (Japan). Faculty of Enginering)

1994-06-20

Comparative investigation of numerical analysis results of out-of-plane secondary stress caused in a cross beam web around scallop before reinforcement and around cutting portion of vertical stiffeners after reinforcement was carried out. In case of steel truss bridge, there exists difference in axial thrust between outside stringers which continue through a cross beam, and it was revealed that this axial thrust was the main factor which causes partial bending stress in a cross beam web plate. When the lower end of vertical stiffeners is not connected to a cross beam foot flange considering of welding, out-of-plane secondary stress was caused partially in a cross beam web plate around scallop, because of the difficult to transmit adjoining stringers axial thrust difference directly to foot flange. In case of the actual analysis, cross beam web plate around cutting portion of vertical stiffeners causes partial out-of-plane secondary stress in web plate, due to being pressed partially by comparatively high stiffness vertical stiffeners. When repair and reinforcement of steel road truss bridge are carried out, it is necessary to take close attention specially on the structure of the parts in which outside stringers is connected to cross beam. 18 refs., 16 figs.

Comparison endpoint study of process plasma and secondary electron beam exciter optical emission spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Stephan Thamban, P. L.; Yun, Stuart; Padron-Wells, Gabriel; Hosch, Jimmy W.; Goeckner, Matthew J. [Department of Mechanical Engineering, University of Texas at Dallas, 800W Campbell Road, Richardson, Texas 75080 (United States); Department of Electrical Engineering, University of Texas at Dallas, 800W Campbell Road, Richardson, Texas 75080 (United States); Verity Instruments, Inc., 2901 Eisenhower Street, Carrollton, Texas 75007 (United States); Department of Mathematical Sciences, University of Texas at Dallas, 800 W Campbell Road, Richardson, Texas 75080 (United States)

2012-11-15

Traditionally process plasmas are often studied and monitored by optical emission spectroscopy. Here, the authors compare experimental measurements from a secondary electron beam excitation and direct process plasma excitation to discuss and illustrate its distinctiveness in the study of process plasmas. They present results that show excitations of etch process effluents in a SF{sub 6} discharge and endpoint detection capabilities in dark plasma process conditions. In SF{sub 6} discharges, a band around 300 nm, not visible in process emission, is observed and it can serve as a good indicator of etch product emission during polysilicon etches. Based on prior work reported in literature the authors believe this band is due to SiF{sub 4} gas phase species.

UNUSUAL ENERGY-DEPENDENCE OF THE TOTAL NUCLEAR-REACTION CROSS-SECTION FOR A SECONDARY ISOMERIC NUCLEAR BEAM (F-18(M), J(PI)=5(+), E(X)=1.1 MEV)

NARCIS (Netherlands)

ROBERTS, DA; BECCHETTI, FD; BROWN, JA; JANECKE, J; PHAM, K; ODONNELL, TW; WARNER, RE; RONNINGEN, RM; WILSCHUT, HW

1995-01-01

A primary O-17 beam has been used to produce a 22.3 MeV/nucleon F-18(m) isomeric secondary beam via a single nucleon transfer reaction on a carbon target. The total nuclear reaction cross sections for F-18(m) and F-18(g.s.) in silicon were measured in a stack of seven silicon solid-state detectors.

High intensity beam profile monitors for the LAMPF primary beam lines

International Nuclear Information System (INIS)

Hoffman, E.W.; Macek, R.J.; van Dyck, O.; Lee, D.; Harvey, A.; Bridge, J.; Cainet, J.

1979-01-01

Two types of beam profile monitors are in use at LAMPF to measure the properties of the 800 MeV, 500 μA proton beam external to the linac. Both types use secondary electron emission from a wire to produce a current signal proportional to the amount of proton beam that intercepts the wire. The wire scanner system uses a pair of orthogonal wires which are passed through the beam and the harp system uses two fixed planes of parallel wires. Most of the harps are not retractable and are exposed continuously to the primary beam. The high beam intensities available lead to a number of technical problems for instruments that intercept the beam or are close to primary beam targets. The thermal, electrical, radiation-damage, and material selection problems encountered, and some solutions which have been implemented are discussed

Interference-aware random beam selection for spectrum sharing systems

KAUST Repository

Abdallah, Mohamed M.

2012-09-01

Spectrum sharing systems have been introduced to alleviate the problem of spectrum scarcity by allowing secondary unlicensed networks to share the spectrum with primary licensed networks under acceptable interference levels to the primary users. In this paper, we develop interference-aware random beam selection schemes that provide enhanced throughput for the secondary link under the condition that the interference observed at the primary link is within a predetermined acceptable value. For a secondary transmitter equipped with multiple antennas, our schemes select a random beam, among a set of power- optimized orthogonal random beams, that maximizes the capacity of the secondary link while satisfying the interference constraint at the primary receiver for different levels of feedback information describing the interference level at the primary receiver. For the proposed schemes, we develop a statistical analysis for the signal-to-noise and interference ratio (SINR) statistics as well as the capacity of the secondary link. Finally, we present numerical results that study the effect of system parameters including number of beams and the maximum transmission power on the capacity of the secondary link attained using the proposed schemes. © 2012 IEEE.

Secondary ion emission from cleaned surfaces bombarded by 100 MeV accelerator beams at the GSI Darmstadt

International Nuclear Information System (INIS)

Wien, K.; Becker, O.; Guthier, W.; Knippelberg, W.; Koczon, P.

1988-01-01

The 1.4 MeV/n beam facility for the UNILAC/GSI has been used to study secondary ion emission from surfaces cleaned under UHV conditions by ion etching or cleaving of crystals. The desorption phenomena observed by means of TOF mass spectrometry can be classified as follows: (1) Clean metal surfaces emit metal ions being ejected by atomic collisions cascades. Electronic excitation of surface states seems to support ionization. (2) The desorption of contaminants adsorbed at the metal surface is strongly correlated with the electronic energy loss of the projectiles - even, if the content of impurities is very low. (3) Ion formation at the epitaxial surface of fluoride crystals as CaF 2 , MgF 2 and NaF is initiated by the electronic excitation of the crystal. At high beam energies the mass spectrum is dominated by a series of cluster ions. These cluster ions disappear below a certain energy deposit threshold, whereas small atomic ions are observed over the whole energy range

Secondary electron emission from insulators

International Nuclear Information System (INIS)

Kanaya, K.; Ono, S.; Ishigaki, F.

1978-01-01

The high yield of secondary electron emission from insulators due to electron bombardment may be the result of an increase of the depth of escape. The free-electron scattering theory is applied to the high energy of primary beams, but cannot be applied to the low energy of secondary escaping beams because of the large energy gap of the insulators. The plasmon loss with the valence electron is considered when the secondary electrons escape. Based on the energy retardation power formula of the penetration and energy loss of an electron probe into solid targets, secondary electron emissions from insulators are calculated from the assumptions that the distribution of the secondary electrons due to both incident and back-scattered electrons within the target is isotropic and that it follows the absorption law of the Lenard type. The universal yield-energy curve of the secondary electron emission, which is deduced as a function of three parameters such as ionisation potential, valence electron and the back-scattered coefficient in addition to the free-electron density effect, is found to be in good agreement with the experimental results. (author)

Electron beam water calorimetry measurements to obtain beam quality conversion factors.

Science.gov (United States)

Muir, Bryan R; Cojocaru, Claudiu D; McEwen, Malcolm R; Ross, Carl K

2017-10-01

To provide results of water calorimetry and ion chamber measurements in high-energy electron beams carried out at the National Research Council Canada (NRC). There are three main aspects to this work: (a) investigation of the behavior of ionization chambers in electron beams of different energies with focus on long-term stability, (b) water calorimetry measurements to determine absorbed dose to water in high-energy beams for direct calibration of ion chambers, and (c) using measurements of chamber response relative to reference ion chambers, determination of beam quality conversion factors, k Q , for several ion chamber types. Measurements are made in electron beams with energies between 8 MeV and 22 MeV from the NRC Elekta Precise clinical linear accelerator. Ion chamber measurements are made as a function of depth for cylindrical and plane-parallel ion chambers over a period of five years to investigate the stability of ion chamber response and for indirect calibration. Water calorimetry measurements are made in 18 MeV and 22 MeV beams. An insulated enclosure with fine temperature control is used to maintain a constant temperature (drifts less than 0.1 mK/min) of the calorimeter phantom at 4°C to minimize effects from convection. Two vessels of different designs are used with calibrated thermistor probes to measure radiation induced temperature rise. The vessels are filled with high-purity water and saturated with H 2 or N 2 gas to minimize the effect of radiochemical reactions on the measured temperature rise. A set of secondary standard ion chambers are calibrated directly against the calorimeter. Finally, several other ion chambers are calibrated in the NRC 60 Co reference field and then cross-calibrated against the secondary standard chambers in electron beams to realize k Q factors. The long-term stability of the cylindrical ion chambers in electron beams is better (always <0.15%) than plane-parallel chambers (0.2% to 0.4%). Calorimetry measurements

Local in-depth analysis of ceramic materials by neutral beam secondary ion mass spectrometry

International Nuclear Information System (INIS)

Borchardt, G.; Scherrer, H.; Weber, S.; Scherrer, S.

1980-01-01

Local microanalysis of non-conducting surfaces by means of modern physical methods which use charged low-energy primary particles brings about severe problems because of the electrostatic charge accumulated on the sample surface. This is also true of secondary ion mass spectrometry (SIMS) where ions are usually used as primary particles. In the present work the basic features for production of neutral primary beams in commercial SIMS instruments by a simple technique are described. With suitably high sputtering rates, surface analyses and in-depth profiles can be made in reasonable measuring times. Results are given for chemical concentration distributions in the near-surface regions of an oxide glass and for the isotopic diffusion of Si-30 in a crystalline silicate with olivine structure (Co 2 SiO 4 ). (orig.)

Secondary magnetic field harmonics dependence on vacuum beam chamber geometry

Directory of Open Access Journals (Sweden)

S. Y. Shim

2013-08-01

Full Text Available The harmonic magnetic field properties due to eddy currents have been studied with respect to the geometry of the vacuum beam chamber. We derived a generalized formula enabling the precise prediction of any field harmonics generated by eddy currents in beam tubes with different cross-sectional geometries. Applying our model to study the properties of field harmonics in beam tubes with linear dipole magnetic field ramping clearly proved that the circular cross section tube generates only a dipole field from eddy currents. The elliptic tube showed noticeable magnitudes of sextupole and dipole fields. We demonstrate theoretically that it is feasible to suppress the generation of the sextupole field component by appropriately varying the tube wall thickness as a function of angle around the tube circumference. This result indicates that it is possible to design an elliptical-shaped beam tube that generates a dipole field component with zero magnitude of sextupole. In a rectangular-shaped beam tube, one of the selected harmonic fields can be prevented if an appropriate wall thickness ratio between the horizontal and vertical tube walls is properly chosen. Our generalized formalism can be used for optimization of arbitrarily complex-shaped beam tubes, with respect to suppression of detrimental field harmonics.

The influence of beam divergence on ion-beam induced surface patterns

International Nuclear Information System (INIS)

Kree, R.; Yasseri, T.; Hartmann, A.K.

2009-01-01

We present a continuum theory and a Monte Carlo model of self-organized surface pattern formation by ion-beam sputtering including effects of beam profiles. Recently, it has turned out that such secondary ion-beam parameters may have a strong influence on the types of emerging patterns. We first discuss several cases, for which beam profiles lead to random parameters in the theory of pattern formation. Subsequently we study the evolution of the averaged height profile in continuum theory and find that the typical Bradley-Harper scenario of dependence of ripple patterns on the angle of incidence can be changed qualitatively. Beam profiles are implemented in Monte Carlo simulations, where we find generic effects on pattern formation. Finally, we demonstrate that realistic beam profiles, taken from experiments, may lead to qualitative changes of surface patterns.

Secondary standard dosimetry laboratory at INFLPR

Energy Technology Data Exchange (ETDEWEB)

Scarlat, F.; Minea, R.; Scarisoreanu, A.; Badita, E.; Sima, E.; Dumitrascu, M.; Stancu, E.; Vancea, C., E-mail: scarlat.f@gmail.com [National Institute for Laser, Plasma and Radiation Physics - INFLPR, Bucharest (Romania)

2011-07-01

National Institute for Laser, Plasma and Radiation Physics (INFLPR) has constructed a High Energy Secondary Standard Dosimetry Laboratory SSDL-STARDOOR - for performing dosimetric calibrations according to ISO IEC SR/EN 17025:2005 standards. This is outfitted with UNIDOS Secondary Standard Dosimeter from PTW (Freiburg Physikalisch-Technische Werksttaten) calibrated at the PTB-Braunschweig (German Federal Institute of Physics and Metrology). A radiation beam of the quality of Q used by our laboratory as calibration source are provided by INFLPR 7 MeV electron beam linear accelerator mounted in our facility. (author)

Modeling beam-front dynamics at low gas pressures

International Nuclear Information System (INIS)

Briggs, R.J.; Yu, S.

1982-01-01

The dynamics of space charge neutralization at the front of an intense self-focused electron beam pulse exhibits important differences in different gas pressure regimes. At very low pressures, the beam front is in the so-called ion-focused regime (IFR) where all secondary electrons are expelled from the beam region by the radial electric field without causing significant additional ionization. We estimate the upper pressure boundary of this regime by considering the distance scale length for cascade (avalanche) ionization. Data from the FX-25 diode experiments indicate a critical transition pressure (P/sub c/) that agrees with this estimate and with its scaling among various gas types. Normal mobility-limited treatments (local conductivity models) of the secondary electrons at the beam front are not justified until the gas pressure is 10 to 50 times higher than P/sub c/, due to runaway of these secondary electrons in the strong space-charge electric field at the lower pressures. The main conclusion of this study is that a non-local phase space (Boltzmann) treatment of the secondary electrons is required to accurately describe these different beam front regimes and the transitions between them; such a code model is currently under development

HIBP primary beam detector

International Nuclear Information System (INIS)

Schmidt, T.W.

1979-01-01

A position measuring detector was fabricated for the Heavy Ion Beam Probe. The 11 cm by 50 cm detector was a combination of 15 detector wires in one direction and 63 copper bars - .635 cm by 10 cm to measure along an orthogonal axis by means of a current divider circuit. High transmission tungsten meshes provide entrance windows and suppress secondary electrons. The detector dimensions were chosen to resolve the beam position to within one beam diameter

Overview of in-beam gamma-ray spectroscopy at the RIBF

Energy Technology Data Exchange (ETDEWEB)

Doornenbal, Pieter [RIKEN Nishina Center, Wako, Saitama 351-0198 (Japan)

2016-07-07

At the Radioactive Isotope Beam Factory stable primary beams are accelerated up to 345 MeV/u and incident on a primary target to produce cocktail secondary beams with the fragment separator BigRIPS ranging from the lightest nuclei up to the lead region. For in-beam γ-ray spectroscopy, the secondary beams impinge on a reaction target at energies between 100 and 300 MeV/u. Reaction residues are identified with the ZeroDegree spectrometer and γ-rays detected with the NaI(Tl) based DALI2 array. This conference paper outlines the experimental setup and presents recent exemplary results.

Secondary-electron-bremsstrahlung imaging for proton therapy

Energy Technology Data Exchange (ETDEWEB)

Yamaguchi, Mitsutaka; Nagao, Yuto [Takasaki Advanced Radiation Research Institute, Quantum Beam Science Research Directorate, National Institutes for Quantum and Radiological Science and Technology, 1233 Watanuki-Machi, Takasaki, Gunma (Japan); Ando, Koki; Yamamoto, Seiichi [Department of Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, 1-1-20 Daiko-Minami, Higashi-Ku, Nagoya, Aichi (Japan); Toshito, Toshiyuki [Department of Proton Therapy Physics, Nagoya Proton Therapy Center, Nagoya City West Medical Center, 1-1-1 Hirate-cho, Kita-Ku, Nagoya, Aichi (Japan); Kataoka, Jun [Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo (Japan); Kawachi, Naoki [Takasaki Advanced Radiation Research Institute, Quantum Beam Science Research Directorate, National Institutes for Quantum and Radiological Science and Technology, 1233 Watanuki-Machi, Takasaki, Gunma (Japan)

2016-10-11

A feasibility study on an imaging technique of a therapeutic proton-beam trajectory using a gamma camera by measuring secondary electron bremsstrahlung (SEB) was performed by means of Monte Carlo simulations and a beam-irradiation experiment. From the simulation and experimental results, it was found that a significant amount of SEB yield exists between the beam-injection surface and the range position along the beam axis and the beam trajectory is clearly imaged by the SEB yield. It is concluded that the SEB imaging is a promising technique for monitoring of therapeutic proton-beam trajectories.

Power consumption in positive ion beam converter with electrostatic electron suppressor

International Nuclear Information System (INIS)

Hashimoto, Kiyoshi; Sugawara, Tohru

1985-01-01

The power recovery characteristics of an in-line direct beam converter provided with electrostatic electron suppressor were studied numerically by tracing the orbits of fast primary ions and secondary charged particles generated along their beam path by collision with background gas molecules. It is shown that, in reference to the electrostatic field potential at the point of impact, the energy distribution of secondary ions impinging on the suppressor has two peaks-one corresponding to a zone of high positive potential surrounding the collector and the other to one of slightly negative potential around the electron suppressor. Secondary electron emission from the suppressor is ascribed mainly to the latter peak, associated with impingement of slower secondary ions. Far much power consumed in secondary particle acceleration is spent for emitting electrons from the suppressor than for secondary ions generated by beam-gas collision. The upper limit of background pressure is discussed on the basis of criteria prescribed for restricting the power consumed in this secondary particle acceleration, as for practical convenience of electrode cooling. Numerical examples are given of calculations based on particle trajectory analysis of both primary ions and secondary particles, for the case of a 100 keV-proton sheet beam 10 cm thick of 35 mA/cm 2 current density. (author)

Individual analysis of nonmetallic Inclusions in Steel by using the gallium focused ion beam secondary ion mass spectrometry

International Nuclear Information System (INIS)

Tomiyasu, Bunbunoshin; Inami, Akihiro; Abe, Masakazu; Nihei, Yoshimasa.

1995-01-01

Nonmetallic inclusions frequently exert a lot of unfavorable influences on the quality of steel. The size of nonmetallic inclusions in current steel products is less than a few μm in diameter. It is desirable to make clear the origin and generation process of such small particles of nonmetallic inclusion. In order to measure the shape, size, composition and inner elemental distribution, development of characterization methods for each inclusion particle is required. By employing a gallium focused ion beam (FIB) as a primary ion beam of secondary ion mass spectrometry (SIMS), the particle analysis with high spatial resolution is easily achieved. In this paper, we present the novel individual analysis of nonmetallic inclusions in steel by gallium FIB SIMS. We analyzed in two ways the nonmetallic inclusion particles segregated by electron beam melting. (1) By cross-sectioning of the particle using a gallium FIB, elemental maps of cross-section were obtained. The elements were distributed inhomogeneously on the cross-section. (2) We carried out the compositional analysis for several particles individually. Ten particles were analyzed by the shave-off analysis and the multivariate cluster analysis. Based on the composition of each particle, the inclusions were classified into six types. (author)

BEAM web server: a tool for structural RNA motif discovery.

Science.gov (United States)

Pietrosanto, Marco; Adinolfi, Marta; Casula, Riccardo; Ausiello, Gabriele; Ferrè, Fabrizio; Helmer-Citterich, Manuela

2018-03-15

RNA structural motif finding is a relevant problem that becomes computationally hard when working on high-throughput data (e.g. eCLIP, PAR-CLIP), often represented by thousands of RNA molecules. Currently, the BEAM server is the only web tool capable to handle tens of thousands of RNA in input with a motif discovery procedure that is only limited by the current secondary structure prediction accuracies. The recently developed method BEAM (BEAr Motifs finder) can analyze tens of thousands of RNA molecules and identify RNA secondary structure motifs associated to a measure of their statistical significance. BEAM is extremely fast thanks to the BEAR encoding that transforms each RNA secondary structure in a string of characters. BEAM also exploits the evolutionary knowledge contained in a substitution matrix of secondary structure elements, extracted from the RFAM database of families of homologous RNAs. The BEAM web server has been designed to streamline data pre-processing by automatically handling folding and encoding of RNA sequences, giving users a choice for the preferred folding program. The server provides an intuitive and informative results page with the list of secondary structure motifs identified, the logo of each motif, its significance, graphic representation and information about its position in the RNA molecules sharing it. The web server is freely available at http://beam.uniroma2.it/ and it is implemented in NodeJS and Python with all major browsers supported. marco.pietrosanto@uniroma2.it. Supplementary data are available at Bioinformatics online.

Geometric beam coupling impedance of LHC secondary collimators

Science.gov (United States)

Frasciello, Oscar; Tomassini, Sandro; Zobov, Mikhail; Salvant, Benoit; Grudiev, Alexej; Mounet, Nicolas

2016-02-01

The High Luminosity LHC project is aimed at increasing the LHC luminosity by an order of magnitude. One of the key ingredients to achieve the luminosity goal is the beam intensity increase. In order to keep beam instabilities under control and to avoid excessive power losses a careful design of new vacuum chamber components and an improvement of the present LHC impedance model are required. Collimators are among the major impedance contributors. Measurements with beam have revealed that the betatron coherent tune shifts were higher by about a factor of 2 with respect to the theoretical predictions based on the LHC impedance model up to 2012. In that model the resistive wall impedance has been considered as the dominating impedance contribution for collimators. By carefully simulating also their geometric impedance we have contributed to the update of the LHC impedance model, reaching also a better agreement between the measured and simulated betatron tune shifts. During the just ended LHC Long Shutdown I (LSI), TCS/TCT collimators were replaced by new devices embedding BPMs and TT2-111R ferrite blocks. We present here preliminary estimations of their broad-band impedance, showing that an increase of about 20% is expected in the kick factors with respect to previous collimators without BPMs.

Beam Diagnostics Challenges in the FAIR Project at GSI

International Nuclear Information System (INIS)

Peters, Andreas; Forck, Peter

2006-01-01

The planned FAIR (Facility for Antiproton and Ion Research) project consists of two heavy ion synchrotrons and four large storage rings, the existing GSI facility together with a new high-current proton linac will be used as the injector chain. The fast cycling, superconducting synchrotrons are build for high current operation with the aim of secondary ion and antiproton production. A large variety of low current secondary beams as well as the antiprotons are stored and cooled in the four storage rings. A complex operation scheme with multiple use of transport lines is foreseen. This demands an exceptional high dynamic range for the beam instrumentation. Due to the enormous beam power, non-destructive methods are mandatory for high currents as well as for the low current secondary beams due to the low repetition rate. Precise measurements of all beam parameters and automatic steering or feedback capabilities are required due to the necessary exploitation of the full ring acceptances. Moreover, online beam-corrections with short response times are mandatory for the fast ramping super-conducting magnets. An overview of the challenges and projected innovative solutions for various diagnostic installations will be given

Application of Beam Diagnostics for Intense Heavy Ion Beams at the GSI UNILAC

CERN Document Server

Barth, W; Glatz, J; Groening, L; Richter, S; Yaramishev, S

2003-01-01

With the new High Current Injector (HSI) of the GSI UNILAC the beam pulse intensity had been increased by approximately two orders of magnitudes. The HSI was mounted and commissioned in 1999; since this time the UNILAC serves as an injector for the synchrotron SIS, especially for high uranium intensities. Considering the high beam power of up to 1250 kW and the short stopping range for the UNILAC beam energies (≤12 MeV/u), accelerator components could be destroyed, even during a single beam pulse. All diagnostic elements had to be replaced preferably by non-destructive devices. The beam current is mainly measured by beam transformers instead of Faraday cups, beam positions are measured with segmented capacitive pick-ups and secondary beam monitors instead of profile harps. The 24 installed pick-ups are also used to measure intensities, widths and phase of the bunches, as well beam energies by evaluating pick-ups at different positions. The residual gas ionization monitors allow on-line measurements ...

Secondary emission monitor (SEM) grids.

CERN Multimedia

Patrice Loïez

2002-01-01

A great variety of Secondary Emission Monitors (SEM) are used all over the PS Complex. At other accelerators they are also called wire-grids, harps, etc. They are used to measure beam density profiles (from which beam size and emittance can be derived) in single-pass locations (not on circulating beams). Top left: two individual wire-planes. Top right: a combination of a horizontal and a vertical wire plane. Bottom left: a ribbon grid in its frame, with connecting wires. Bottom right: a SEM-grid with its insertion/retraction mechanism.

Short bunch length detector for ion beam with high bunch density

International Nuclear Information System (INIS)

Tron, A.M.; Shako, V.V.

1993-01-01

The secondary electron rf monitors for short ion bunch phase distribution measurements are presented. Construction particularities of the monitors, influence of space charge of both the primary and the secondary electron beams on the phase resolution, thermal regime of the target during beam-target interaction are considered

Secondary Moments due to Prestressing with Different Bond at the Ultimate Limit State

Directory of Open Access Journals (Sweden)

Halvoník Jaroslav

2018-03-01

Full Text Available Secondary effects of prestressing develop in statically indeterminate structures (e.g., continuous beams due to the restraint of deformations imposed by hyperstatic restraints. These effects may significantly influence internal forces and stresses in prestressed structures. Secondary effects are influenced by the redundancy of a structural system, which raises the question of whether they will remain constant after a change in the structural system, e.g., due to the development of plastic hinge(s in a critical cross-section(s or after the development of a kinematic mechanism, or if they will disappear when the structure changes into a sequence of simply supported beams. The paper deals with an investigation of the behavior of continuous post-tensioned beams subjected to an ultimate load with significant secondary effects from prestressing. A total of 6 two-span beams prestressed by tendons with different bonds were tested in a laboratory with a load that changed their structural system into a kinematic mechanism. The internal forces and secondary effects of the prestressing were controlled through measurements of the reactions in all the supports. The results revealed that the secondary effects remained as a permanent part of the action on the experimental beams, even after the development of the kinematic mechanism. The results obtained confirmed that secondary effects should be included in all combinations of actions for verifications of ultimate limit states (ULS.

Secondary Moments due to Prestressing with Different Bond at the Ultimate Limit State

Science.gov (United States)

Halvoník, Jaroslav; Pažma, Peter; Vida, Radoslav

2018-03-01

Secondary effects of prestressing develop in statically indeterminate structures (e.g., continuous beams) due to the restraint of deformations imposed by hyperstatic restraints. These effects may significantly influence internal forces and stresses in prestressed structures. Secondary effects are influenced by the redundancy of a structural system, which raises the question of whether they will remain constant after a change in the structural system, e.g., due to the development of plastic hinge(s) in a critical cross-section(s) or after the development of a kinematic mechanism, or if they will disappear when the structure changes into a sequence of simply supported beams. The paper deals with an investigation of the behavior of continuous post-tensioned beams subjected to an ultimate load with significant secondary effects from prestressing. A total of 6 two-span beams prestressed by tendons with different bonds were tested in a laboratory with a load that changed their structural system into a kinematic mechanism. The internal forces and secondary effects of the prestressing were controlled through measurements of the reactions in all the supports. The results revealed that the secondary effects remained as a permanent part of the action on the experimental beams, even after the development of the kinematic mechanism. The results obtained confirmed that secondary effects should be included in all combinations of actions for verifications of ultimate limit states (ULS).

Effect of Film Dressing on Acute Radiation Dermatitis Secondary to Proton Beam Therapy

International Nuclear Information System (INIS)

Arimura, Takeshi; Ogino, Takashi; Yoshiura, Takashi; Toi, Yuya; Kawabata, Michiko; Chuman, Ikuko; Wada, Kiyotaka; Kondo, Naoaki; Nagayama, Shinichi; Hishikawa, Yoshio

2016-01-01

Purpose: Acute radiation dermatitis (ARD) is one of the most common adverse events of proton beam therapy (PBT), and there is currently no effective method to manage ARD. The purpose of this study was to examine the prophylactic effect of a film dressing using Airwall on PBT-induced ARD compared with standard skin managements. Methods and Materials: A total of 271 patients with prostate cancer who were scheduled for PBT at our center were divided into 2 groups based on their own requests: 145 patients (53%) chose Airwall (group A) and 126 patients (47%) received standard treatments (group B). We evaluated irradiated skin every other day during PBT and followed up once a week for a month after completion of PBT. Results: Grade 0, 1, 2, and 3 dermatitis were seen in 2, 122, 21, and 0 and 0, 65, 57, and 4 patients in groups A and B, respectively (P<.001). Numbers of days to grades 1 and 2 ARD development were 34.9 ± 14.3 and 54.7 ± 10.3 and 31.8 ± 11.3 and 54.4 ± 11.6 in groups A and B, respectively. There were no significant differences between the 2 groups. Eighteen patients (12%) in group A who experienced problems in the region covered with Airwall switched to standard skin care after peeling the film off. Conclusions: Film dressing using Airwall reduced the severity of ARD without delaying the response time of the skin to proton beam irradiation compared with standard skin management. Hence, film dressing is considered a promising measure for preventing ARD secondary to PBT.

Effect of Film Dressing on Acute Radiation Dermatitis Secondary to Proton Beam Therapy

Energy Technology Data Exchange (ETDEWEB)

Arimura, Takeshi, E-mail: arimura-takeshi@medipolis.org [Medipolis Proton Therapy and Research Center, Ibusuki (Japan); Department of Radiology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima (Japan); Ogino, Takashi [Medipolis Proton Therapy and Research Center, Ibusuki (Japan); Yoshiura, Takashi [Department of Radiology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima (Japan); Toi, Yuya; Kawabata, Michiko; Chuman, Ikuko; Wada, Kiyotaka; Kondo, Naoaki; Nagayama, Shinichi; Hishikawa, Yoshio [Medipolis Proton Therapy and Research Center, Ibusuki (Japan)

2016-05-01

Purpose: Acute radiation dermatitis (ARD) is one of the most common adverse events of proton beam therapy (PBT), and there is currently no effective method to manage ARD. The purpose of this study was to examine the prophylactic effect of a film dressing using Airwall on PBT-induced ARD compared with standard skin managements. Methods and Materials: A total of 271 patients with prostate cancer who were scheduled for PBT at our center were divided into 2 groups based on their own requests: 145 patients (53%) chose Airwall (group A) and 126 patients (47%) received standard treatments (group B). We evaluated irradiated skin every other day during PBT and followed up once a week for a month after completion of PBT. Results: Grade 0, 1, 2, and 3 dermatitis were seen in 2, 122, 21, and 0 and 0, 65, 57, and 4 patients in groups A and B, respectively (P<.001). Numbers of days to grades 1 and 2 ARD development were 34.9 ± 14.3 and 54.7 ± 10.3 and 31.8 ± 11.3 and 54.4 ± 11.6 in groups A and B, respectively. There were no significant differences between the 2 groups. Eighteen patients (12%) in group A who experienced problems in the region covered with Airwall switched to standard skin care after peeling the film off. Conclusions: Film dressing using Airwall reduced the severity of ARD without delaying the response time of the skin to proton beam irradiation compared with standard skin management. Hence, film dressing is considered a promising measure for preventing ARD secondary to PBT.

Beam-plasma discharge in a Kyoto beam-plasma-ion source

International Nuclear Information System (INIS)

Ishikawa, J.; Takagi, T.

1983-01-01

A beam-plasma type ion source employing an original operating principle has been developed by the present authors. The ion source consists of an ion extraction region with an electron gun, a thin long drift tube as the plasma production chamber, and a primary electron beam collector. An electron beam is effectively utilized for the dual purpose of high density plasma production as a result of beam-plasma discharge, and high current ion beam extraction with ion space-charge compensation. A high density plasma of the order of 10 11 --10 13 cm -3 was produced by virtue of the beam-plasma discharge which was caused by the interaction between a space-charge wave on the electron beam and a high frequency plasma wave. The plasma density then produced was 10 2 --10 3 times the density produced only by collisional ionization by the electron beam. In order to obtain a stable beam-plasma discharge, a secondary electron beam emitted from the electron collector should be utilized. The mechanism of the beam-plasma discharge was analyzed by use of a linear theory in the case of the small thermal energy of the electron beam, and by use of a quasilinear theory in the case of the large thermal energy. High current ion beams of more than 0.1 A were extracted even at a low extraction voltage of 1--5 kV

Numerical simulation of electron beam welding with beam oscillations

Science.gov (United States)

Trushnikov, D. N.; Permyakov, G. L.

2017-02-01

This research examines the process of electron-beam welding in a keyhole mode with the use of beam oscillations. We study the impact of various beam oscillations and their parameters on the shape of the keyhole, the flow of heat and mass transfer processes and weld parameters to develop methodological recommendations. A numerical three-dimensional mathematical model of electron beam welding is presented. The model was developed on the basis of a heat conduction equation and a Navier-Stokes equation taking into account phase transitions at the interface of a solid and liquid phase and thermocapillary convection (Marangoni effect). The shape of the keyhole is determined based on experimental data on the parameters of the secondary signal by using the method of a synchronous accumulation. Calculations of thermal and hydrodynamic processes were carried out based on a computer cluster, using a simulation package COMSOL Multiphysics.

Fast electron beam charge injection and switching in dielectrics

Energy Technology Data Exchange (ETDEWEB)

Fitting, Hans-Joachim; Schreiber, Erik [Institute of Physics, University of Rostock, Universitaetsplatz 3, 18051 Rostock (Germany); Touzin, Matthieu [Laboratoire de Structure et Proprietes de l' Etat Solide, UMR CNRS 8008, Universite de Lille 1, 59655 Villeneuve d' Ascq (France)

2011-04-15

Basic investigations of secondary electrons (SE) relaxation and attenuation are made by means of Monte Carlo simulations using ballistic electron scattering and interactions with optical and acoustic phonons as well as impact ionization of valence band electrons. Then the electron beam induced selfconsistent charge transport and secondary electron emission in insulators are described by means of an electron-hole flight-drift model (FDM). Ballistic secondary electrons and holes, their attenuation and drift, as well as their recombination, trapping, and field- and temperature-dependent Poole-Frenkel detrapping are included. Whereas the initial switching-on of the secondary electron emission proceeds over milli-seconds due to long-lasting selfconsistent charging, the switching-off process occurs much faster, even over femto-seconds. Thus a rapid electron beam switching becomes possible with formation of ultra-short electron beam pulses offering an application in stroboscopic electron microscopy and spectroscopy. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

GANIL beam profile detectors

International Nuclear Information System (INIS)

Tribouillard, C.

1997-01-01

In the design phase of GANIL which started in 1977, one of the priorities of the project management was equipping the beamlines with a fast and efficient system for visualizing the beam position, thus making possible adjustment of the beam transport lines optics and facilitating beam control. The implantation of some thirty detectors was foreseen in the initial design. The assembly of installed detectors (around 190) proves the advantages of these detectors for displaying all the beams extracted from GANIL: transfer and transport lines, beam extracted from SISSI, very high intensity beam, secondary ion beams from the production target of the LISE and SPEG spectrometers, different SPIRAL project lines. All of these detectors are based on standard characteristics: - standard flange diameter (DN 160) with a standard booster for all the sensors; - identical analog electronics for all the detectors, with networking; - unique display system. The new micro-channel plate non-interceptive detectors (beam profile and ion packet lengths) make possible in-line control of the beam quality and accelerator stability. (author)

Design of the radioactive ion beam facility at the LNS

International Nuclear Information System (INIS)

Migneco, E.; Alba, R.; Calabretta, L.; Ciavola, G.; Cuttone, G.; Di Giacomo, M.; Gammino, S.; Gmaj, P.; Moscatello, M.H.; Raia, G.

1992-01-01

At the Laboratorio Nazionale del Sud the existing 15 MV Tandem will be coupled to the Superconducting Cyclotron booster, which will provide light and heavy ion beams in the energy range 100-20 MeV/n. Using these beams, secondary radioactive beams can be produced by projectile fragmentation. A fragment separator will collect the secondary beam produced at energies near that of the projectile and deliver it into the experimental areas. The possibility of using an ECRIS source for the axial injection into the Cyclotron and producing radioactive ions on a thick source placed inside the Tandem preinjector is also discussed. (author) 7 refs.; 2 figs.; 1 tab

An assessment of the secondary neutron dose in the passive scattering proton beam facility of the national cancer center

Energy Technology Data Exchange (ETDEWEB)

Han, Sang Eun [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of); Cho, Gyuseong [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Lee, Se Byeong [Proton Therapy Center, National Cancer Center, Goyang (Korea, Republic of)

2017-06-15

The purpose of this study is to assess the additional neutron effective dose during passive scattering proton therapy. Monte Carlo code (Monte Carlo N-Particle 6) simulation was conducted based on a precise modeling of the National Cancer Center's proton therapy facility. A three-dimensional neutron effective dose profile of the interior of the treatment room was acquired via a computer simulation of the 217.8-MeV proton beam. Measurements were taken with a 3He neutron detector to support the simulation results, which were lower than the simulation results by 16% on average. The secondary photon dose was about 0.8% of the neutron dose. The dominant neutron source was deduced based on flux calculation. The secondary neutron effective dose per proton absorbed dose ranged from 4.942 ± 0.031 mSv/Gy at the end of the field to 0.324 ± 0.006 mSv/Gy at 150 cm in axial distance.

Design of a new low momentum kaon beam for the AGS

International Nuclear Information System (INIS)

Lazarus, D.M.

1976-01-01

The low momentum beam described is to be a unique source of antiprotons as well as kaons. The discussion covers (1) choice of production angle; (2) secondary beams; (3) the use of sector dipole magnets for minimizing aberrations; (4) beam bending magnets; (5) beam separators; and (6) beam acceptance

Electron beam irradiation process applied to primary and secondary recycled high density polyethylene

International Nuclear Information System (INIS)

Cardoso, Jéssica R.; Moura, Eduardo de; Geraldo, Áurea B.C.

2017-01-01

Plastic bags, packaging and furniture items are examples of plastic utilities always present in life. However, the end-of-life of plastics impacts the environment because of this ubiquity and also often their high degradation time. Recycling processes are important in this scenario because they offer many solutions to this problem. Basically, four ways are known for plastic recycling: primary recycling, which consists in re-extrusion of clean plastic scraps from a production plant; secondary recycling, that uses end-of-life products that generally are reduced in size by extrusion to obtain a more desirable shape for reprocessing (pellets and powder); tertiary recover which is related to thermo-chemical methods to produce fuels and petrochemical feedstock; and quaternary route, that is related to energy recovery and it is done in appropriate reactors. In this work, high density polyethylene (HDPE) was recovered to simulate empirically the primary and secondary recycling ways using materials which ranged from pristine to 20-fold re-extrused materials. The final 20-fold recycled thermoplastic was irradiated in an electron beam accelerator under a dose rate of 22.4 kGy/s and absorbed doses of 50 kGy and 100 kGy. The characterization of HDPE in distinct levels of recovering was performed by infrared spectroscopy (FTIR) and thermogravimetric degradation. In the HDPE recycling, degradation and crosslinking are consecutive processes; degradation is very noticeable in the 20-fold recycled product. Despite this, the 20-fold recycled product presents crosslinking after irradiation process and the post-irradiation product presents similarities in spectroscopic and thermal degradation characteristics of pristine, irradiated HDPE. These results are discussed. (author)

Electron beam irradiation process applied to primary and secondary recycled high density polyethylene

Energy Technology Data Exchange (ETDEWEB)

Cardoso, Jéssica R.; Moura, Eduardo de; Geraldo, Áurea B.C., E-mail: ageraldo@ipen.br [Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP), São Paulo, SP (Brazil)

2017-07-01

Plastic bags, packaging and furniture items are examples of plastic utilities always present in life. However, the end-of-life of plastics impacts the environment because of this ubiquity and also often their high degradation time. Recycling processes are important in this scenario because they offer many solutions to this problem. Basically, four ways are known for plastic recycling: primary recycling, which consists in re-extrusion of clean plastic scraps from a production plant; secondary recycling, that uses end-of-life products that generally are reduced in size by extrusion to obtain a more desirable shape for reprocessing (pellets and powder); tertiary recover which is related to thermo-chemical methods to produce fuels and petrochemical feedstock; and quaternary route, that is related to energy recovery and it is done in appropriate reactors. In this work, high density polyethylene (HDPE) was recovered to simulate empirically the primary and secondary recycling ways using materials which ranged from pristine to 20-fold re-extrused materials. The final 20-fold recycled thermoplastic was irradiated in an electron beam accelerator under a dose rate of 22.4 kGy/s and absorbed doses of 50 kGy and 100 kGy. The characterization of HDPE in distinct levels of recovering was performed by infrared spectroscopy (FTIR) and thermogravimetric degradation. In the HDPE recycling, degradation and crosslinking are consecutive processes; degradation is very noticeable in the 20-fold recycled product. Despite this, the 20-fold recycled product presents crosslinking after irradiation process and the post-irradiation product presents similarities in spectroscopic and thermal degradation characteristics of pristine, irradiated HDPE. These results are discussed. (author)

High current density ion beam measurement techniques

International Nuclear Information System (INIS)

Ko, W.C.; Sawatzky, E.

1976-01-01

High ion beam current measurements are difficult due to the presence of the secondary particles and beam neutralization. For long Faraday cages, true current can be obtained only by negative bias on the target and by summing the cage wall and target currents; otherwise, the beam will be greatly distorted. For short Faraday cages, a combination of small magnetic field and the negative target bias results in correct beam current. Either component alone does not give true current

Measurements of secondary electron cross sections by the pulsed electron beam time-of-flight method. I. Molecular nitrogen

International Nuclear Information System (INIS)

Goruganthu, R.R.; Wilson, W.G.; Bonham, R.A.

1983-01-01

The secondary electron cross sections for gaseous molecular nitrogen are reported at ejection angles of 30, 45, 60, 75, 90, 105, 120, 135 and 150 0 , for the energy range 1.5 eV to 20 eV and incident electron energy of 1 keV. The pulsed electron beam time-of-flight methd was employed. The results were placed on an absolute scale by normalization to the elastic scattering. They were compared, where possible, with those reported by Opal, Beaty, and Peterson (OBP). The agreement is somewhat better when the OBP data are divided by 0.53 + 0.47 sintheta as suggested by Rudd and DuBois. Fits of our data by Legendre-polynomial expansions are used to estimate the low-energy portion of the cross-section, dsigma/dE. This work suggests that existing experimental cross sections for secondary electron ejection as a function of angle and ejected energy may be no better known than +-40%, especially in the low energy region. 7 references, 14 figures, 2 tables

Beam damage of self-assembled monolayers

International Nuclear Information System (INIS)

Rieke, P.C.; Baer, D.R.; Fryxell, G.E.; Engelhard, M.H.; Porter, M.S.

1993-01-01

X-ray and electron beam damage studies were performed on Br-terminated and methyl-terminated alkylsilane self-assembled monolayers. X-ray beam initiated damage was primarily limited to removal of the labile Br group and did not significantly damage the hydrocarbon chain. Some of the x-ray beam damage could be attributed to low-energy electrons emitted by the non-monochromatic source, but further damage was attributed to secondary electrons produced in the sample by x-ray exposure. Electron beams caused significant damage to the hydrocarbon chains. Maximum damage occurred with a beam energy of 600 eV and a dosage of 6x10 -3 C/cm 2

The ideal neutrino beams

CERN Document Server

Lindroos, Mats

2009-01-01

The advance in neutrino oscillation physics is driven by the availability of well characterized and high flux neutrino beams. The three present options for the next generation neutrino oscillation facility are super beams, neutrino factories and beta-beams. A super-beam is a very high intensity classical neutrino beam generated by protons impinging on a target where the neutrinos are generated by the secondary particles decaying in a tunnel down streams of the target. In a neutrino factory the neutrinos are generated from muons decaying in a storage ring with long straight sections pointing towards the detectors. In a beta-beam the neutrinos are also originating from decay in a storage ring but the decaying particles are radioactive ions rather than muons. I will in this presentation review the three options and discuss the pros and cons of each. The present joint design effort for a future high intensity neutrino oscillation in Europe within a common EU supported design study, EURONU, will also be presented....

Experimental study on secondary electron emission characteristics of Cu

Science.gov (United States)

Liu, Shenghua; Liu, Yudong; Wang, Pengcheng; Liu, Weibin; Pei, Guoxi; Zeng, Lei; Sun, Xiaoyang

2018-02-01

Secondary electron emission (SEE) of a surface is the origin of the multipacting effect which could seriously deteriorate beam quality and even perturb the normal operation of particle accelerators. Experimental measurements on secondary electron yield (SEY) for different materials and coatings have been developed in many accelerator laboratories. In fact, the SEY is just one parameter of secondary electron emission characteristics which include spatial and energy distribution of emitted electrons. A novel experimental apparatus was set up in China Spallation Neutron Source, and an innovative method was applied to obtain the whole characteristics of SEE. Taking Cu as the sample, secondary electron yield, its dependence on beam injection angle, and the spatial and energy distribution of secondary electrons were achieved with this measurement device. The method for spatial distribution measurement was first proposed and verified experimentally. This contribution also tries to give all the experimental results a reasonable theoretical analysis and explanation.

SU-D-BRB-02: Investigations of Secondary Ion Distributions in Carbon Ion Therapy Using the Timepix Detector.

Science.gov (United States)

Gwosch, K; Hartmann, B; Jakubek, J; Granja, C; Soukup, P; Jaekel, O; Martisikova, M

2012-06-01

Due to the high conformity of carbon ion therapy, unpredictable changes in the patient's geometry or deviations from the planned beam properties can result in changes of the dose distribution. PET has been used successfully to monitor the actual dose distribution in the patient. However, it suffers from biological washout processes and low detection efficiency. The purpose of this contribution is to investigate the potential of beam monitoring by detection of prompt secondary ions emerging from a homogeneous phantom, simulating a patient's head. Measurements were performed at the Heidelberg Ion-Beam Therapy Center (Germany) using a carbon ion pencil beam irradiated on a cylindrical PMMA phantom (16cm diameter). For registration of the secondary ions, the Timepix detector was used. This pixelated silicon detector allows position-resolved measurements of individual ions (256×256 pixels, 55μm pitch). To track the secondary ions we used several parallel detectors (3D voxel detector). For monitoring of the beam in the phantom, we analyzed the directional distribution of the registered ions. This distribution shows a clear dependence on the initial beam energy, width and position. Detectable were range differences of 1.7mm, as well as vertical and horizontal shifts of the beam position by 1mm. To estimate the clinical potential of this method, we measured the yield of secondary ions emerging from the phantom for a beam energy of 226MeV/u. The differential distribution of secondary ions as a function of the angle from the beam axis for angles between 0 and 90° will be presented. In this setup the total yield in the forward hemisphere was found to be in the order of 10 -1 secondary ions per primary carbon ion. The presented measurements show that tracking of secondary ions provides a promising method for non-invasive monitoring of ion beam parameters for clinical relevant carbon ion fluences. Research with the pixel detectors was carried out in frame of the Medipix

Glow-discharge-created electron beams and beam-excited lasers

International Nuclear Information System (INIS)

Meyer, J.D.

1989-01-01

Efficiently created glow discharge electron beams have been developed and studied in detail. The beam mode of operation occurs in the abnormal glow adjacent to the glow-to-arc transition regime. In contrast to electron beams generated in high vacuum from thermionic electron emitting sources, this type of discharge creates electrons directly in soft vacuum by secondary electron emission from cold cathode surfaces following the bombardment of the cathode surface by fast ions and neutral atoms. Factors influencing the efficient electron emission from cold cathodes are presented with emphasis on cathode materials. Sintered ceramic-metal cathodes and oxide-coated cathodes are presented, both of which can produce high power, efficiently generated, d.c. electron beams with discharge currents up to 1 amp (∼130 mA/cm 2 ) at volt ages of up to 6 kV. Novel cathode designs and discharge geometries are presented with specific emphasis on both self-focussed beams emitted from circular cathodes and line-source electron beams emitted from rectangular cathodes forming a thin sheet of electrons. Electrostatically focussed line-source electron beams are spatially characterized by experimentally measuring the effect of discharge parameters and cathode design upon the focussed beam width, focal point, and uniformity. This is achieved by scanning a current collecting detector in three dimensions in order to profile the distribution of electron beam current. Discharge electron beams are further characterized by their electron energy distribution. Measured electron flux energy distributions of transmitted beam electrons in the negative glow are compared to theoretical models. The relative effects of elastic and inelastic collisions mechanisms upon both the overall form and detailed structure of the energy distribution are discussed

The T10 beam produces a few hits per event. In ALICE the SSD will have to cope with many hits per strip. In the three centimeters of aluminium the beam will produce many secondary particles. This increases the chance of multiple hits per strip, although not to the level in ALICE.

CERN Multimedia

Nooren, G.

2004-01-01

The T10 beam produces a few hits per event. In ALICE the SSD will have to cope with many hits per strip. In the three centimeters of aluminium the beam will produce many secondary particles. This increases the chance of multiple hits per strip, although not to the level in ALICE.

Emittance growth due to space charge compensation and beam intensity instabilities in negative ion beams

Directory of Open Access Journals (Sweden)

C. A. Valerio-Lizarraga

2018-03-01

Full Text Available The need to extract the maximum beam intensity with low transversal emittance often comes with the drawback of operating the ion source to limits where beam current instabilities arise, such fluctuations can change the beam properties producing a mismatch in the following sections of the machine. The space charge compensation (SCC generated by the beam particles colliding with the residual gas reaches a steady state after a build-up time. This paper shows how once in the steady state, the beam ends with a transversal emittance value bigger than the case without compensation. In addition, we study how the beam intensity variation can disturb the SCC dynamics and its impact on the beam properties. The results presented in this work come from 3-D simulations using tracking codes taking into account the secondary ions to estimate the degree of the emittance growth due to space charge and SCC.

High resolution line for secondary radioactive beams at the U400M cyclotron

International Nuclear Information System (INIS)

Rodin, A.M.; Sidorchuk, S.I.; Stepantsov, S.V.

1996-01-01

For implementation of an experimental program for studying nuclear reactions with radioactive ion beams in the energy domain of 20 through 80 MeV · A the high resolution beam line ACCULINNA was put into commissioning on a primary beam line of the JINR U-400M cyclotron. By means of nuclear fragmentation of the 14 N beam with the energy of 51 MeV · A on the 170 mg/cm 2 carbon target radioactive beams of 6 He, 8 He and 8 B were obtained. Possibilities of further development of the set-up are discussed. 6 refs., 7 figs., 2 tabs

Plasma properties of a modified beam-plasma type ion source

International Nuclear Information System (INIS)

Ishikawa, Junzo; Sano, Fumimichi; Tsuji, Hiroshi; Ektessabi, A.M.; Takagi, Toshinori

1978-01-01

The properties of the plasma produced by beam-plasma discharge were experimentally investigated. The ion source used for this work consists of three parts, that is, the ion-extracting region with an electron gun, the drift space and the collector region. Primary and secondary electron beams are injected in to the drift tube. The interaction between plasma and these electron beams causes production of high density plasma by virtue of the beam-plasma discharge. The gas inlet is located in the middle of the drift tube, so that the gas conductance is high. The energy of the primary and secondary electron beams is transferred to that microwaves through beam-plasma interaction. The microwaves heat the plasma electrons by the cyclotron resonance or other mechanism. The amount of the energetic plasma electrons is much larger than that of the beam electrons, so that neutral gas is ionized. The density of the produced plasma is 10 2 or 10 3 times as large as the plasma produced by impact ionization. With a probe located in the middle of the drift tube, the plasma density and the electron temperature can be measured, and the power and spectra of the microwaves can be detected. The microwave oscillation, the primary electron beam characteristics, and the gas pressure characteristics were studied. Larger current of the high energy primary of secondary electron beam is required for the effective discharge. The ion source has to be operated at the minimum gas pressure. The length of beam-plasma interaction and the magnetic field intensity in the drift tube are also important parameters. (Kato, T.)

Exposure parameters in proton beam writing for hydrogen silsesquioxane

International Nuclear Information System (INIS)

Kan, J.A. van; Zhang, F.; Zhang, C.; Bettiol, A.A.; Watt, F.

2008-01-01

In proton beam writing (PBW) a focused MeV proton beam is scanned in a predetermined pattern over a resist (e.g. PMMA, SU-8 or HSQ), which is subsequently chemically developed. In e-beam writing as well as p-beam writing the energy loss of the primary beam is dominated by energy transfer to substrate electrons. Unlike the high energy secondary electrons generated during e-beam writing the secondary electrons induced by the primary proton beam have low energy and therefore a limited range, resulting in minimal proximity effects. The low proximity effects exhibited by p-beam writing coupled with the straight trajectory and high penetration of the proton beam enables the production of high aspect ratio, high density 3D micro and nanostructures with well defined smooth side walls to be directly written into resist materials. This property together with the stability and focusing power of the end station ensures even exposures with nm smoothness and allows fabrication of details down to the 20 nm level. In this paper, we present results like contrast and sensitivity for PBW using, hydrogen silsesquioxane (HSQ) and XR-1541, both are non-C based resists. Unlike PMMA and SU-8 resist HSQ shows aging effects, requiring optimized processing parameters in PBW

Beam profile monitor

International Nuclear Information System (INIS)

Krausse, G.J.; Gram, P.A.M.

1978-05-01

A system used to monitor secondary beam profiles at the LAMPF Linac for channel tune-up and diagnostics is described. The multiwire proportional chamber design is discussed, and descriptions and drawings of the gate card, the amplifier/multiplexer card, the output amplifier card, and the overall system are given

Surrey Ion Beam Centre: the EPSRC MRF for ion beam applications - 01002

International Nuclear Information System (INIS)

Webb, R.P.

2016-01-01

The SIBC (Surrey Ion Beam Centre) is an element of the Virtual Ion Beam Centre that coordinates 3 U.K. experimental facilities: SIBC (University of Surrey) for implantation and ion beam applications, Miami and MEIS facility (University of Huddersfield) and gamma ray and neutron irradiation emulation facility (University of Manchester). The SIBC works actively with industry, developing bespoke processes and services, particularly for the photonics industry and provides ion beam facilities to about 20 companies across the world. It operates a stringent quality control program and is one of the few ion beam laboratories in the world to operate under ISO 9001 certification. The equipment of SIBC is presented and some applications of ion beam analysis concerning the identification of gunshot residues, the determination of the origin of a painting, the analysis of proteins are described. Different techniques such as PIXE (Particle Induced X-ray Emission), RBS (Rutherford Backscattering Spectroscopy), NRA (Nuclear Reaction Analysis), SIMS (Secondary Ion Mass Spectrometry) are also explained in the slides of the presentation that have been added at the end of the paper

Interference-aware random beam selection schemes for spectrum sharing systems

KAUST Repository

Abdallah, Mohamed

2012-10-19

Spectrum sharing systems have been recently introduced to alleviate the problem of spectrum scarcity by allowing secondary unlicensed networks to share the spectrum with primary licensed networks under acceptable interference levels to the primary users. In this work, we develop interference-aware random beam selection schemes that provide enhanced performance for the secondary network under the condition that the interference observed by the receivers of the primary network is below a predetermined/acceptable value. We consider a secondary link composed of a transmitter equipped with multiple antennas and a single-antenna receiver sharing the same spectrum with a primary link composed of a single-antenna transmitter and a single-antenna receiver. The proposed schemes select a beam, among a set of power-optimized random beams, that maximizes the signal-to-interference-plus-noise ratio (SINR) of the secondary link while satisfying the primary interference constraint for different levels of feedback information describing the interference level at the primary receiver. For the proposed schemes, we develop a statistical analysis for the SINR statistics as well as the capacity and bit error rate (BER) of the secondary link.

Secondary Electron Yield on Cryogenic Surfaces as a Function of Physisorbed Gases

CERN Document Server

Kuzucan, Asena; Taborelli, Mauro

2011-01-01

In LHC the electron cloud induced by photoelectrons, gas ionization and secondary electrons emitted from the beam pipe walls could be a limitation of the performance. The electron cloud induce heat load on the cryogenic system, cause pressure rise, emittance growth and beam instabilities, which in the end will limit the beam’s lifetime. Beam- induced multipacting, which can arise through oscillatory motion of photoelectrons and low-energy secondary electrons bouncing back and forth between opposite walls of the vacuum chamber during successive passage of proton bunches, represent therefore a potential problem for the machine. The secondary electron yield (SEY) is one of the key parameters for the electron cloud build up and multipacting phenomenon. An electron cloud occurs if the metal surface secondary electron yield is high enough for electron multiplication. This parameter has been extensively studied on room temperature samples but uncertainties remain for samples at cryogenic temperature. Indeed, at l...

Applications of ion beam analysis workshop. Workshop handbook

International Nuclear Information System (INIS)

1995-01-01

A workshop on applications of ion beam analysis was held at ANSTO, immediate prior to the IBMM-95 Conference in Canberra. It aims was to review developments and current status on use of ion beams for analysis, emphasizing the following aspects: fundamental ion beam research and secondary effects of ion beams; material sciences, geological, life sciences, environmental and industrial applications; computing codes for use in accelerator research; high energy heavy ion scattering and recoil; recent technological development using ion beams. The handbook contains the workshop's program, 29 abstracts and a list of participants

Ion-beam apparatus and method for analyzing and controlling integrated circuits

Science.gov (United States)

Campbell, Ann N.; Soden, Jerry M.

1998-01-01

An ion-beam apparatus and method for analyzing and controlling integrated circuits. The ion-beam apparatus comprises a stage for holding one or more integrated circuits (ICs); a source means for producing a focused ion beam; and a beam-directing means for directing the focused ion beam to irradiate a predetermined portion of the IC for sufficient time to provide an ion-beam-generated electrical input signal to a predetermined element of the IC. The apparatus and method have applications to failure analysis and developmental analysis of ICs and permit an alteration, control, or programming of logic states or device parameters within the IC either separate from or in combination with applied electrical stimulus to the IC for analysis thereof. Preferred embodiments of the present invention including a secondary particle detector and an electron floodgun further permit imaging of the IC by secondary ions or electrons, and allow at least a partial removal or erasure of the ion-beam-generated electrical input signal.

Standard beam PWC for Fermilab

International Nuclear Information System (INIS)

Fenker, H.

1983-02-01

As one of its projects the Fermilab Experimental Areas Department has been designed and tested a relatively small proportional wire chamber for use in the secondary beam lines. It is intended to supplement the variety of detectors known in the vernacular as SWICS that are used to obtain profiles for beam tuning. The new detector, described in this report, operates in the limited proportional mode and allows experimenters to use a standard, lab supported device for associating trajectories of individual beam particles with events triggering their own experiment's apparatus. A completed triple plane module is shown

Overview of linac applications at future radioactive beam facilities

International Nuclear Information System (INIS)

Nolen, J.A.

1996-01-01

There is considerable interest worldwide in the research which could be done at a next generation, advanced radioactive beam facility. To generate high quality, intense beams of accelerated radionuclides via the open-quotes isotope separator on-lineclose quotes (ISOL) method requires two major accelerator components: a high power (100 kW) driver device to produce radionuclides in a production target/ion source complex, and a secondary beam accelerator to produce beams of radioactive ions up to energies on the order of 10 MeV per nucleon over a broad mass range. In reviewing the technological challenges of such a facility, several types of modem linear accelerators appear well suited. This paper reviews the properties of the linacs currently under construction and those proposed for future facilities for use either as the driver device or the radioactive beam post-accelerator. Other choices of accelerators, such as cyclotrons, for either the driver or secondary beam devices of a radioactive beam complex will also be compared. Issues to be addressed for the production accelerator include the choice of ion beam types to be used for cost-effective production of radionuclides. For the post-accelerator the choice of ion source technology is critical and dictates the charge-to-mass requirements at the injection stage

A critical study of emittance measurements of intense low-energy proton beams

CERN Document Server

Evans, Lyndon R

1972-01-01

The measurement of emittance in low energy proton beams suffers from two perturbing effects: 1) the neutralisation of the beam by backstreaming secondary electrons and 2) the space charge blowup of the beam sample between defining and analysing apparatus. An experimental study shows a significant change of the emittance orientation when bias is used to eliminate the secondary electrons. Biased and non-biased cases are also compared with computed dynamics including space charge. Criteria for the slit size and drift distance which make the space charge blow-up negligible are derived. In addition a transverse coherent oscillation of the proton beam, which was revealed the measurements, is discussed briefly. (11 refs).

Imaging and characterization of primary and secondary radiation in ion beam therapy

Energy Technology Data Exchange (ETDEWEB)

Granja, Carlos, E-mail: carlos.granja@utef.cvut.cz; Opalka, Lukas [Institute of Experimental and Applied Physics, Czech Technical University in Prague (Czech Republic); Martisikova, Maria; Gwosch, Klaus [German Cancer Research Center, Heidelberg (Germany); Jakubek, Jan [Advacam, Prague (Czech Republic)

2016-07-07

Imaging in ion beam therapy is an essential and increasingly significant tool for treatment planning and radiation and dose deposition verification. Efforts aim at providing precise radiation field characterization and online monitoring of radiation dose distribution. A review is given of the research and methodology of quantum-imaging, composition, spectral and directional characterization of the mixed-radiation fields in proton and light ion beam therapy developed by the IEAP CTU Prague and HIT Heidelberg group. Results include non-invasive imaging of dose deposition and primary beam online monitoring.

Imaging and characterization of primary and secondary radiation in ion beam therapy

International Nuclear Information System (INIS)

Granja, Carlos; Opalka, Lukas; Martisikova, Maria; Gwosch, Klaus; Jakubek, Jan

2016-01-01

Imaging in ion beam therapy is an essential and increasingly significant tool for treatment planning and radiation and dose deposition verification. Efforts aim at providing precise radiation field characterization and online monitoring of radiation dose distribution. A review is given of the research and methodology of quantum-imaging, composition, spectral and directional characterization of the mixed-radiation fields in proton and light ion beam therapy developed by the IEAP CTU Prague and HIT Heidelberg group. Results include non-invasive imaging of dose deposition and primary beam online monitoring.

A target concept for intense radioactive beams in the 132Sn Region

International Nuclear Information System (INIS)

Nolen, J.A. Jr.

1993-01-01

To produce intense secondary beams of radioactive isotopes, primary beams of up to 100 kW are being proposed at some facilities. There are plans to test production targets with 800 MeV protons at such higher power at the Rutherford Appleton Laboratory. In this paper the use of high energy neutrons as a possible alternative is presented. The concept is to generate an intense beam of neutrons in a well-cooled target with a primary deuteron beam. The neutrons have a high cross section for producing fission fragments in a thick uranium target which is coupled to the ion source for the secondary beams. The effective target thickness is large and the power dissipated in the ISOL target is relatively small, which should lead to intense beams of neutron-rich, intermediate-mass isotopes such as 132 Sn

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

1D numerical simulation of charge trapping in an insulator submitted to an electron beam irradiation. Part I: Computation of the initial secondary electron emission yield

International Nuclear Information System (INIS)

Aoufi, A.; Damamme, G.

2011-01-01

The aim of this work is to study by numerical simulation a mathematical modelling technique describing charge trapping during initial charge injection in an insulator submitted to electron beam irradiation. A two-fluxes method described by a set of two stationary transport equations is used to split the electron current j e (z) into coupled forward j e+ (z) and backward j e (z) currents and such that j e (z) = j e+ (z) - j e- (z). The sparse algebraic linear system, resulting from the vertex-centered finite-volume discretization scheme is solved by an iterative decoupled fixed point method which involves the direct inversion of a bi-diagonal matrix. The sensitivity of the initial secondary electron emission yield with respect to the energy of incident primary electrons beam, that is penetration depth of the incident beam, or electron cross sections (absorption and diffusion) is investigated by numerical simulations. (authors)

Comparison of specular H-atomic-beam intensity and C+ secondary-ion yield at thermally activated decrease of a carbon layer on a Ni(110) surface

International Nuclear Information System (INIS)

Kaarmann, H.; Hoinkes, H.; Wilsch, H.

1983-01-01

The thermally activated disappearance of a carbon layer on a Ni(110) surface was investigated by the scattering of atomic hydrogen and by secondary-ion mass spectrometry. Decreasing C coverage at surface temperatures kept constant in each case at values between 650 and 750 K resulted in an exponential decrease of specular H-beam intensity as well as C + secondary-ion yield. This decrease in both cases fits first-order kinetics (presumable diffusion into the bulk) with an identical rate constant as a function of surface temperature and results finally in a preexponential frequency ν = 10/sup() 10plus-or-minus1/ s -1 and an activation energy E/sub A/ = 1.8 +- 0.2 eV

Determination of average conversion coefficients between kerma in air and H⁎(10) using primary and secondary X-ray beams and transmitted in the diagnostic radiology energy range

International Nuclear Information System (INIS)

Santos, Josilene C.; Gonzalez, Alejandro H.L.; Costa, Paulo R.

2016-01-01

Brazilian regulation establishes 1.14 Sv/Gy as unique conversion coefficient to convert air-kerma into the operational quantity ambient dose equivalent H⁎(10) disregarding its beam quality dependence. The present study computed mean conversion coefficients from primary, secondary and transmitted X-ray beams through barite mortar plates used in shielding of dedicated chest radiographic facilities in order to improve the current assessment of H⁎(10). To compute the mean conversion coefficients, the weighting of conversion coefficients corresponding to monoenergetic beams with the spectrum energy distribution in terms of air-kerma was considered. The maximum difference between the obtained conversion coefficients and the constant value recommended in national regulation is 53.4%. The conclusion based on these results is that a constant coefficient is not adequate for deriving the H⁎(10) from air-kerma measurements. (author)

Interference-aware random beam selection for spectrum sharing systems

KAUST Repository

Abdallah, Mohamed M.; Sayed, Mostafa M.; Alouini, Mohamed-Slim; Qaraqe, Khalid A.

2012-01-01

. In this paper, we develop interference-aware random beam selection schemes that provide enhanced throughput for the secondary link under the condition that the interference observed at the primary link is within a predetermined acceptable value. For a secondary

Monitor of SC beam profiles

CERN Document Server

CERN PhotoLab

1977-01-01

A high-resolution secondary emission grid for the measurement of SC beam profiles. Modern techniques of metal-ceramic bonding, developed for micro-electronics, have been used in its construction. (See Annual Report 1977 p. 105 Fig. 12.)

A research of possibility for negative muon production by a low energy electron beam accompanying ion beam

International Nuclear Information System (INIS)

Uramoto, Joshin.

1993-12-01

A low energy electron beam (≤ 2000 eV) is injected perpendicularly to a uniform magnetic field, together with a low energy positive ion beam. On this magnetic mass analysis (using the uniform magnetic field), a peak of secondary electron current to the beam collector (arranging as a mass analyzer of 90deg type), appears at an analyzing magnetic field which corresponds exactly to a relation of negative muon μ - (the mass m=207 m e and the charge q=e, where m e and e are mass and charge of electron). The ion beam is essential for the peak appearance, which is produced by decelerating electrically the electron beam in front of the entrance slit of the mass analyzer, and by introducing a neutral gas into the electron beam region and producing a plasma through the ionization. We consider that a very small amount of negative muons may be produced through local cyclotron motions of the injected beam electrons in the ion beam or by an interaction between the bunched beam electrons and beam ions. (author)

Biomedical applications of medium energy particle beams at LAMPF

International Nuclear Information System (INIS)

Bradbury, J.N.

1978-01-01

At LAMPF an 800-MeV proton accelerator is used to produce intense beams of secondary protons, pi mesons, and muons which are being employed in several areas of biomedical research. The primary proton beam is used to produce short-lived radioisotopes of clinical interest. Carefully tailored secondary proton beams are used to obtain density reconstructions of samples with a dose much less than that required by x-ray CT scanners. The elemental composition of tissue samples is being determined non-destructively with muonic x-ray analysis. Finally, an extensive program, with physical, biological, and clinical components, is underway to evaluate negative pi mesons for use in cancer radiotherapy. The techniques used in these experiments and recent results are described

Performance of the KTeV high-energy neutral kaon beam at Fermilab

International Nuclear Information System (INIS)

Bocean, V.

1998-01-01

The performance of the primary and secondary beams for the KTeV experiments E832 and E799-II is reviewed. The beam was commissioned in the summer of 1996 and initially operated for approximately one year. The report includes results on the primary beam, target station including primary beam dump and muon sweeping system, neutral beam collimation system, and alignment

Determination of the secondary energy from the electron beam with a flattening foil by computer. Percentage depth dose curve fitting using the specific higher order polynomial

Energy Technology Data Exchange (ETDEWEB)

Kawakami, H [Kyushu Univ., Beppu, Oita (Japan). Inst. of Balneotherapeutics

1980-09-01

A computer program written in FORTRAN is described for determining the secondary energy of the electron beam which passed through a flattening foil, using a time-sharing computer service. The procedure of this program is first to fit the specific higher order polynomial to the measured percentage depth dose curve. Next, the practical range is evaluated by the point of intersection R of the line tangent to the fitted curve at the inflection point P and the given dose E, as shown in Fig. 2. Finally, the secondary energy corresponded to the determined practical range can be obtained by the experimental equation (2.1) between the practial range R (g/cm/sup 2/) and the electron energy T (MeV). A graph for the fitted polynomial with the inflection points and the practical range can be plotted on a teletype machine by request of user. In order to estimate the shapes of percentage depth dose curves correspond to the electron beams of different energies, we tried to find some specific functional relationships between each coefficient of the fitted seventh-degree equation and the incident electron energies. However, exact relationships could not be obtained for irreguarity among these coefficients.

Manufacturing prepainted steel sheet by electron beam curing

International Nuclear Information System (INIS)

Oka, Joji

1987-01-01

Several advantages are offered by electron beam curing. A formidably hard and stain resistant paint film which is difficult to obtain by heat curing paint is developed. As a result, a unique new prepainted steel is produced. Four technologies are involved: development high-quality paint, selection of optimum electron beam processor, technology to control electron beam processing atmosphere and secondary X-ray shield technology. These technologies are described in detail. (A.J.)

High energy high intensity coherent photon beam for the SSC

International Nuclear Information System (INIS)

Tannenbaum, M.J.

1984-01-01

What is proposed for the 20 TeV protons hitting a fixed target is to make a tertiary electron beam similar to that which is the basis of the tagged photon beam at Fermilab. Briefly, a zero degree neutral beam is formed by sweeping out the primary proton beam and any secondary charged particles. Then the photons, from the decay of π 0 in the neutral beam, are converted to e + e - pairs in a lead converter and a high quality electron beam is formed. This beam is brought to the target area where it is converted to a photon beam by Bremsstrahlung in a radiator

Monte Carlo simulation of secondary neutron dose for scanning proton therapy using FLUKA.

Directory of Open Access Journals (Sweden)

Chaeyeong Lee

Full Text Available Proton therapy is a rapidly progressing field for cancer treatment. Globally, many proton therapy facilities are being commissioned or under construction. Secondary neutrons are an important issue during the commissioning process of a proton therapy facility. The purpose of this study is to model and validate scanning nozzles of proton therapy at Samsung Medical Center (SMC by Monte Carlo simulation for beam commissioning. After the commissioning, a secondary neutron ambient dose from proton scanning nozzle (Gantry 1 was simulated and measured. This simulation was performed to evaluate beam properties such as percent depth dose curve, Bragg peak, and distal fall-off, so that they could be verified with measured data. Using the validated beam nozzle, the secondary neutron ambient dose was simulated and then compared with the measured ambient dose from Gantry 1. We calculated secondary neutron dose at several different points. We demonstrated the validity modeling a proton scanning nozzle system to evaluate various parameters using FLUKA. The measured secondary neutron ambient dose showed a similar tendency with the simulation result. This work will increase the knowledge necessary for the development of radiation safety technology in medical particle accelerators.

A test beam upgrade based on the BEPC-LINAC

International Nuclear Information System (INIS)

Li Jiacai; Wu Yuanming; Cui Xiangzong; Zhang Liangsheng; Zhou Baoqing; Liu Zhengquan; Zhang Shaoping; Sun Changchun; Zhang Zhuxiang; Zhang Caidi; Zheng Linsheng; Liu Shixing; Shen Ji; Yin Zejie; Zhang Yongming; Chen Ziyu

2004-01-01

A total of three beam lines, E1, E2 and E3 have based on the LINAC of BEPC. The E1 beam is to be used for intense slow-positron facility. The E2 is a primary positron or electron beam with an energy of 1.3-1.5 GeV. The E3 is a secondary electron or pion test beam with a momentum can be adjustable continuously. The position accuracy of a detected particle is 0.2-0.4 mm with an event rate of 3 - 4 Hz. This beam has been successfully used for some detectors beam test. (author)

In-beam γ-ray spectroscopy of the neutron rich 39Si

International Nuclear Information System (INIS)

Sohler, D.; Dombradi, Zs.; Achouri, N.L.; Angelique, J.C.; Bastin, B.; Azaiez, F.; Baiborodin, D.; Borcea, R.

2009-01-01

Complete text of publication follows. In order to clarify the role of proton excitations across the Z = 14 subshell closure in neutron-rich Si isotopes, we investigated the structure of the 14 39 Si 25 isotope, having three neutron-hole configurations with respect to an N = 28 core. The excited states of 39 Si were studied by in-beam γ-ray spectroscopy trough fragmentation of radioactive beams. The experiment was performed at the GANIL facility in France. The radioactive beams were produced by the fragmentation of the stable 48 Ca beam of 60 MeV/u energy and 4μA intensity on a 12 C target in the SISSI device. The cocktail beam produced was impinged onto a 9 Be target. The nuclei produced in the secondary fragmentation reaction were selected and unambiguously identified by the SPEG spectrometer. In the performed experiment the 39 Si nuclei were obtained via 1p, 1p1n, 2p1n and 2p2n knockout reactions from the 40,41 P and 42,43 S secondary beams. To measure the γ rays emitted from the excited states, the secondary target was surrounded by the 4π 'Chateau de Crystal' array consisting of 74 BaF 2 scintillators. The γ-ray spectra were generated by gating event-by-event on the incoming secondary beam particles and the ejectiles after the secondary target. For the γ rays emitted by the fast moving fragments accurate Doppler correction was performed. From the obtained γ spectra of 39 Si displayed in Figure 1, two strong γ transitions at 163 and 397 keV as well as weaker ones at 303, 657, 906, 1143 and 1551 keV have been identified. γγ coincidences were obtained in 39 Si after having added all data from the various reaction channels giving rise to 39 Si. Analysing these data the 163 keV transition was found to be in coincidence with the 657, 1143 and 1551 keV ones, but not with the 397 keV transition. The two lines of the 303+397 keV doublet are in mutual coincidence, and one or both of them are found in coincidence with the 906 keV transition.

Development of a beam ion velocity detector for the heavy ion beam probe

International Nuclear Information System (INIS)

Fimognari, P. J.; Crowley, T. P.; Demers, D. R.

2016-01-01

In an axisymmetric plasma, the conservation of canonical angular momentum constrains heavy ion beam probe (HIBP) trajectories such that measurement of the toroidal velocity component of secondary ions provides a localized determination of the poloidal flux at the volume where they originated. We have developed a prototype detector which is designed to determine the beam angle in one dimension through the detection of ion current landing on two parallel planes of detecting elements. A set of apertures creates a pattern of ion current on wires in the first plane and solid metal plates behind them; the relative amounts detected by the wires and plates determine the angle which beam ions enter the detector, which is used to infer the toroidal velocity component. The design evolved from a series of simulations within which we modeled ion beam velocity changes due to equilibrium and fluctuating magnetic fields, along with the ion beam profile and velocity dispersion, and studied how these and characteristics such as the size, cross section, and spacing of the detector elements affect performance.

Development of a beam ion velocity detector for the heavy ion beam probe

Energy Technology Data Exchange (ETDEWEB)

Fimognari, P. J., E-mail: PJFimognari@XanthoTechnologies.com; Crowley, T. P.; Demers, D. R. [Xantho Technologies, LLC, Madison, Wisconsin 53705 (United States)

2016-11-15

In an axisymmetric plasma, the conservation of canonical angular momentum constrains heavy ion beam probe (HIBP) trajectories such that measurement of the toroidal velocity component of secondary ions provides a localized determination of the poloidal flux at the volume where they originated. We have developed a prototype detector which is designed to determine the beam angle in one dimension through the detection of ion current landing on two parallel planes of detecting elements. A set of apertures creates a pattern of ion current on wires in the first plane and solid metal plates behind them; the relative amounts detected by the wires and plates determine the angle which beam ions enter the detector, which is used to infer the toroidal velocity component. The design evolved from a series of simulations within which we modeled ion beam velocity changes due to equilibrium and fluctuating magnetic fields, along with the ion beam profile and velocity dispersion, and studied how these and characteristics such as the size, cross section, and spacing of the detector elements affect performance.

Beam Loss Detection at Radiation Source ELBE

CERN Document Server

Michel, P; Schurig, R; Langenhagen, H

2003-01-01

The Rossendorf superconducting Electron Linac of high Brilliance and low Emittance (ELBE) delivers an 40 MeV, 1 mA cw-beam for different applications such as bremsstrahlung production, electron channelling, free-electron lasers or secondary particle beam generation. In this energy region in case of collisions of the electron beam with the pipe nearly all beam power will be deposited into the pipe material. Therefore a reliable beam loss monitoring is essential for machine protection at ELBE. Different systems basing on photo multipliers, compton diodes and long ionization chambers were studied. The pros and cons of the different systems will be discussed. Ionization chambers based on air-isolated RF cables installed some cm away parallel to the beam line turned out to be the optimal solution. The beam shut-off threshold was adjusted to 1 μC integral charge loss during a 100 ms time interval. Due to the favourable geometry the monitor sensitivity varies less than ±50% along the beam line (di...

Overview of LHC Beam Loss Measurements

CERN Document Server

Dehning, B; Effinger, E; Emery, J; Fadakis, E; Holzer, E B; Jackson, S; Kruk, G; Kurfuerst, C; Marsili, A; Misiowiec, M; Nebot Del Busto, E; Nordt, A; Priebe, A; Roderick, C; Sapinski, M; Zamantzas, C; Grishin, V; Griesmayer, E

2011-01-01

The LHC beam loss monitoring system provides measurements with an update rate of 1 Hz and high time resolution data by event triggering. These informations are used for the initiation of beam aborts, fixed displays and the off line analysis. The analysis of fast and localized loss events resulted in the determination of its rate, duration, peak amplitudes, its scaling with intensity, number of bunches and beam energy. The calibration of the secondary shower beam loss signal in respect to the needed beam energy deposition to quench the magnet coil is addressed at 450GeV and 3.5T eV . The adjustment of collimators is checked my measuring the loss pattern and its variation in the collimation regions of the LHC. Loss pattern changes during a fill allow the observation of non typical fill parameters.

Development of focused ion beam systems with various ion species

International Nuclear Information System (INIS)

Ji Qing; Leung, K.-N.; King, Tsu-Jae; Jiang Ximan; Appleton, Bill R.

2005-01-01

Conventional focused ion beam systems employ a liquid-metal ion source (LMIS) to generate high-brightness beams, such as Ga + beams. Recently there has been an increased need for focused ion beams in areas like biological studies, advanced magnetic-film manufacturing and secondary-ion mass spectroscopy (SIMS). In this article, status of development on focused ion beam systems with ion species such as O 2 + , P + , and B + will be reviewed. Compact columns for forming focused ion beams from low energy (∼3keV), to intermediate energy (∼35keV) are discussed. By using focused ion beams, a SOI MOSFET is fabricated entirely without any masks or resist

Pion beam development for the LAMPF biomedical project

International Nuclear Information System (INIS)

Paciotti, M.; Amols, H.; Bradbury, J.; Rivera, O.; Hogstrom, K.; Smith, A.; Inoue, H.; Laubacher, D.; Sandford, S.

1979-01-01

Common to both static and dynamic patient irradiations at the LAMPF linac is the problem of maintaining good quality control of beams form a secondary channel. A major contributor to therapy beam variation has been change in electron contamination due to the change in target geometry and proton beam steering. The electron variation problem is described and a solution is presented that has been realized as a result o a new target geometry that allows some control of the electron fraction

Observation of strong leakage reduction in crystal assisted collimation of the SPS beam

Energy Technology Data Exchange (ETDEWEB)

Scandale, W. [CERN, European Organization for Nuclear Research, CH-1211 Geneva 23 (Switzerland); Laboratoire de l' Accelerateur Lineaire (LAL), Universite Paris Sud Orsay, Orsay (France); INFN Sezione di Roma, Piazzale Aldo Moro 2, 00185 Rome (Italy); Arduini, G.; Butcher, M.; Cerutti, F.; Garattini, M.; Gilardoni, S.; Lechner, A.; Losito, R.; Masi, A.; Mereghetti, A.; Metral, E. [CERN, European Organization for Nuclear Research, CH-1211 Geneva 23 (Switzerland); Mirarchi, D. [CERN, European Organization for Nuclear Research, CH-1211 Geneva 23 (Switzerland); Imperial College, London (United Kingdom); Montesano, S.; Redaelli, S. [CERN, European Organization for Nuclear Research, CH-1211 Geneva 23 (Switzerland); Rossi, R. [CERN, European Organization for Nuclear Research, CH-1211 Geneva 23 (Switzerland); INFN Sezione di Roma, Piazzale Aldo Moro 2, 00185 Rome (Italy); Schoofs, P.; Smirnov, G. [CERN, European Organization for Nuclear Research, CH-1211 Geneva 23 (Switzerland); Bagli, E.; Bandiera, L.; Baricordi, S. [INFN Sezione di Ferrara, Dipartimento di Fisica, Università di Ferrara, Ferrara (Italy); and others

2015-09-02

In ideal two-stage collimation systems, the secondary collimator–absorber should have its length sufficient to exclude practically the exit of halo particles with large impact parameters. In the UA9 experiments on the crystal assisted collimation of the SPS beam a 60 cm long tungsten bar is used as a secondary collimator–absorber which is insufficient for the full absorption of the halo protons. Multi-turn simulation studies of the collimation allowed to select the position for the beam loss monitor downstream the collimation area where the contribution of particles deflected by the crystal in channeling regime but emerging from the secondary collimator–absorber is considerably reduced. This allowed observation of a strong leakage reduction of halo protons from the SPS beam collimation area, thereby approaching the case with an ideal absorber.

Slaw extracted proton beam formation and monitoring for the ''QUARTZ'' setup

International Nuclear Information System (INIS)

Bushnin, Yu.B.; Gres', V.N.; Davydenko, Yu.P.

1982-01-01

The version of optical mode of the beam channel providing with simultaneous operating the experimental setups FODS and ''QUARTZ'' at consecutive usage of the slow extracted proton beam is reported. The ''QUARTZ'' setup beam diagnostics system comprises two subsystems: for measuring beam profile beam timing structure and beam intensity and operates in the beam extraction duration from 20 ns to few seconds at beam intensity from 10 10 to 5x10 12 protons/pulse. The ''QUARTZ'' setup represents a focusing crystal-diffraction spectrometer with 5-meter focal distance and Ge(Li) special construction detector. High efficiency target is applied in the setup. The ''QUARTZ'' setup is designed for studying exotic atoms produced by negative charged heavy particles (π, K, μ, P tilde) and atomic nuclei. Precise energy measurement of X ray transitions in such atoms is performed. For measuring beam geometric parameters 32-channel secondary emission chambers are used. As detector of beam intensity and timing structure of slow extracted beam the secondary emission chamber is employed. The principle circuit of current integrator is given. As data transmission line a 50-pair telephone cable is used. Information conversion into digital form and its subsequent processing is performed in the CAMAC system and the SM-3 computer. The proton beam full intensity measuring system provides with accuracy not worse than +-4.5% in the 10 10 -10 12 proton/sec range. The implemented optical mode of the beam channel and proton beam monitoring system permitted to begin fulfillment of the experimental program on the ''QUARTZ'' setup

Accelerator development for a radioactive beam facility based on ATLAS

International Nuclear Information System (INIS)

Shepard, K. W.

1998-01-01

The existing superconducting linac ATLAS is in many respects an ideal secondary beam accelerator for an ISOL (Isotope separator on-line) type radioactive beam facility. Such a facility would require the addition of two major accelerator elements: a low charge state injector for the existing heavy ion linac, and a primary beam accelerator providing 220 MV of acceleration for protons and light ions. Development work for both of these elements, including the option of superconducting cavities for the primary beam accelerator is discussed

Accelerator development for a radioactive beam facility based on ATLAS.

Energy Technology Data Exchange (ETDEWEB)

Shepard, K. W.

1998-01-08

The existing superconducting linac ATLAS is in many respects an ideal secondary beam accelerator for an ISOL (Isotope separator on-line) type radioactive beam facility. Such a facility would require the addition of two major accelerator elements: a low charge state injector for the existing heavy ion linac, and a primary beam accelerator providing 220 MV of acceleration for protons and light ions. Development work for both of these elements, including the option of superconducting cavities for the primary beam accelerator is discussed.

Carbon buildup monitoring using RBS: Correlation with secondary electrons

International Nuclear Information System (INIS)

Aguilera, E.F.; Rosales, P.; Martinez-Quiroz, E.; Murillo, G.; Fernandez, M.C.

2006-01-01

The RBS technique is applied to solve the problem of on-line monitoring of the carbon deposited on a thin backed foil under ion bombardment. An iterative method is used to reliably extract quantities such as number of projectiles and target thickness in spite of beam energy changes and detector unstabilities. Experimental values for secondary electron yields are also deduced. Results are reported for the thickness variation of thin carbon foils bombarded with carbon ions of energies between 8.95 and 13 MeV. A linear correlation of this variation is found with both, the ion fluence at target and the number of secondary electrons emitted. The correlation exists even though a wide range of beam currents, beam energies and bombarding times was used during the experiment. The measured electron yields show evidence for a change in the emission process between the original foils and the deposited layer, possibly due to a texture change

The ideal neutrino beams

Science.gov (United States)

Lindroos, Mats

2009-06-01

The advance in neutrino oscillation physics is driven by the availability of well characterized and high flux neutrino beams. The three present options for the next generation neutrino oscillation facility are super beams, neutrino factories and beta-beams. A super-beam is a very high intensity classical neutrino beam generated by protons impinging on a target where the neutrinos are generated by the secondary particles decaying in a tunnel down streams of the target. In a neutrino factory the neutrinos are generated from muons decaying in a storage ring with long straight sections pointing towards the detectors. In a beta-beam the neutrinos are also originating from decay in a storage ring but the decaying particles are radioactive ions rather than muons. I will in this presentation review the three options and discuss the pros and cons of each. The present joint design effort for a future high intensity neutrino oscillation in Europe within a common EU supported design study, EURONU, will also be presented. The design study will explore the physics reach, the detectors, the feasibility, the safety issues and the cost for each of the options so that the the community can take a decision on what to build when the facilities presently under exploitation and construction have to be replaced.

Development of an energy analyzer as diagnostic of beam-generated plasma in negative ion beam systems

Science.gov (United States)

Sartori, E.; Carozzi, G.; Veltri, P.; Spolaore, M.; Cavazzana, R.; Antoni, V.; Serianni, G.

2017-08-01

The measurement of the plasma potential and the energy spectrum of secondary particles in the drift region of a negative ion beam offers an insight into beam-induced plasma formation and beam transport in low pressure gasses. Plasma formation in negative-ion beam systems, and the characteristics of such a plasma are of interest especially for space charge compensation, plasma formation in neutralizers, and the development of improved schemes of beam-induced plasma neutralisers for future fusion devices. All these aspects have direct implications in the ITER Heating Neutral Beam and the operation of the prototypes, SPIDER and MITICA, and also have important role in the conceptual studies for NBI systems of DEMO, while at present experimental data are lacking. In this paper we present the design and development of an ion energy analyzer to measure the beam plasma formation and space charge compensation in negative ion beams. The diagnostic is a retarding field energy analyzer (RFEA), and will measure the transverse energy spectra of plasma molecular ions. The calculations that supported the design are reported, and a method to interpret the measurements in negative ion beam systems is also proposed. Finally, the experimental results of the first test in a magnetron plasma are presented.

Coronary cineangiography and ionizing radiation exposure to patients: analysis of primary and secondary beam; Cineangiografia coronaria y radiacion ionizante a pacientes. Analisis en haz primario y secundario

Energy Technology Data Exchange (ETDEWEB)

Ramirez, Alfredo; Leyton, Fernando; Silva, Ana Maria; Farias, Eric [Universidad de Chile, Santiago (Chile). Hospital Clinico; Gamarra, Jorge; Oyarzun, Carlos [Comision Chilena de Energia Nuclear (CCHEN), Santiago (Chile)

2001-07-01

The purpose of this work was to determine the level of exposure dose to patients during coronariographies in different areas of body. This study has presented the medical surveillance of 18 cases and the radiation monitoring of these patients by TLD in thyroid and pelvis (secondary beam) and, in the right and left scapular region (primary beam) for each one of these procedures. The ionizing radiation received was 215 {+-} 200 mGy in left scapular region (range 1-710) and 255{+-}213 mGy in the right scapular region (range 22-635) p=NS. In the pelvic region the ionizing radiation was 0,22{+-}0,06 mGy and in the thyroid region was 3,62{+-}2,44 mGy.

Joint opportunistic beam and spectrum selection schemes for spectrum sharing systems with limited feedback

KAUST Repository

Sayed, Mostafa M.

2014-11-01

Spectrum sharing systems have been introduced to alleviate the problem of spectrum scarcity by allowing an unlicensed secondary user (SU) to share the spectrum with a licensed primary user (PU) under acceptable interference levels to the primary receiver (PU-Rx). In this paper, we consider a secondary link composed of a secondary transmitter (SU-Tx) equipped with multiple antennas and a single-antenna secondary receiver (SU-Rx). The secondary link is allowed to share the spectrum with a primary network composed of multiple PUs communicating over distinct frequency spectra with a primary base station. We develop a transmission scheme where the SU-Tx initially broadcasts a set of random beams over all the available primary spectra for which the PU-Rx sends back the index of the spectrum with the minimum interference level, as well as information that describes the interference value, for each beam. Based on the feedback information on the PU-Rx, the SU-Tx adapts the transmitted beams and then resends the new beams over the best primary spectrum for each beam to the SU-Rx. The SU-Rx selects the beam that maximizes the received signal-to-interference-plus-noise ratio (SINR) to be used in transmission over the next frame. We consider three cases for the level of feedback information describing the interference level. In the first case, the interference level is described by both its magnitude and phase; in the second case, only the magnitude is considered; and in the third case, we focus on a q-bit description of its magnitude. In the latter case, we propose a technique to find the optimal quantizer thresholds in a mean-square-error sense. We also develop a statistical analysis for the SINR statistics and the capacity and bit error rate of the secondary link and present numerical results that study the impact of the different system parameters.

Fundamental limits to imaging resolution for focused ion beams

International Nuclear Information System (INIS)

Orloff, J.; Swanson, L.W.; Utlaut, M.

1996-01-01

This article investigates the limitations on the formation of focused ion beam images from secondary electrons. We use the notion of the information content of an image to account for the effects of resolution, contrast, and signal-to-noise ratio and show that there is a competition between the rate at which small features are sputtered away by the primary beam and the rate of collection of secondary electrons. We find that for small features, sputtering is the limit to imaging resolution, and that for extended small features (e.g., layered structures), rearrangement, redeposition, and differential sputtering rates may limit the resolution in some cases. copyright 1996 American Vacuum Society

First radioactive beams at ACCULINNA-2 facility and first proposed experiment

Science.gov (United States)

Bezbakh, A. A.; Beekman, W.; Chudoba, V.; Fomichev, A. S.; Golovkov, M. S.; Gorshkov, A. V.; Grigorenko, L. V.; Kaminski, G.; Krupko, S. A.; Mentel, M.; Nikolskii, E. Yu.; Parfenova, Yu. L.; Plucinski, P.; Sidorchuk, S. I.; Slepnev, R. S.; Sharov, P. G.; Ter-Akopian, G. M.; Zalewski, B.

2018-04-01

New fragment separator ACCULINNA-2 was installed at the primary beam line of the U-400M cyclotron in 2016. Recently, first radioactive ion beams were obtained. The design parameters of new facility were experimentally confirmed. Intensity, purity and transverse profile of several secondary beams at the final focal plane were studied. The intensities obtained for the secondary beams of 14B, 12Be, 9;11Li, 6;8He in the fragmentation reaction 15N (49.7 AMeV) + Be (2 mm) are in average 15 times higher in comparison to the ones produced at its forerunner ACCULINNA separator. The ACCULINNA-2 separator will become a backbone facility at the FLNR for the research in the field of light exotic nuclei in the vicinity of the nuclear drip lines. The planned first experiment, aimed for the observation of the 7H nucleus at ACCULINNA-2, is outlined.

A comparison of protocols for external beam radiotherapy beam calibrations

International Nuclear Information System (INIS)

Saeed Al-Ahbabi, Salma; Bradley, D.A.; Beyomi, M.; Alkatib, Z.; Adhaheri, S.; Darmaki, M.; Nisbet, A.

2012-01-01

A number of codes of practice (CoP) for electron and photon radiotherapy beam dosimetry are currently in use. Comparison is made of the more widely used of these, specifically those of the International Atomic Energy Agency (IAEA TRS-398), the American Association of Physicists in Medicine (AAPM TG-51) and the Institute of Physics and Engineering in Medicine (IPEM 2003). All are based on calibration of ionization chambers in terms of absorbed dose to water, each seeking to reduce uncertainty in delivered dose, providing an even stronger system of primary standards than previous air-kerma based approaches. They also provide a firm, traceable and straight-forward formalism. Included in making dose assessments for the three CoP are calibration coefficients for a range of beam quality indices. Measurements have been performed using clinical photon and electron beams, the absorbed dose to water being obtained following the recommendations given by each code. Electron beam comparisons have been carried out using measurements for electron beams of nominal energies 6, 9, 12, 16 and 20 MeV. Comparisons were also carried out for photon beams of nominal energies 6 and 18 MV. For photon beams use was made of NE2571 cylindrical graphite walled ionization chambers, cross-calibrated against an NE2611 Secondary Standard; for electron beams, PTW Markus and NACP-02 plane-parallel chambers were used. Irradiations were made using Varian 600C/2100C linacs, supported by water tanks and Virtual Water™ phantoms. The absorbed doses for photon and electron beams obtained following these CoP are all in good agreement, with deviations of less than 2%. A number of studies have been carried out by different groups in different countries to examine the consistency of dosimetry codes of practice or protocols. The aim of these studies is to confirm that the goal of those codes is met, namely uniformity in establishment of dosimetry of all radiation beam types used in cancer therapy in the world

Recent results on reactions with radioactive beams at RIBRAS (Radioactive Ion Beams in Brazil)

Science.gov (United States)

Lépine-Szily, A.; Lichtenthäler, R.; Guimarães, V.; Arazi, A.; Barioni, A.; Benjamim, E. A.; de Faria, P. N.; Descouvemont, P.; Gasques, L. R.; E; Leistenschneider; Mendes, D. R., Jr.; Morais, M. C.; Morcelle, V.; Moro, A. M.; Pampa Condori, R.; Pires, K. C. C.; Rodriguez-Gallardo, M.; Scarduelli, V.; Shorto, J. M. B.; Zamora, J. C.

2015-04-01

We present a quick description of RIBRAS (Radioactive Ion beams in Brazil), which is a superconducting double solenoid system, installed at the Pelletron Laboratory of the University of São Paulo and extends the capabilities of the original Pelletron Tandem Accelerator of 8MV terminal voltage (8UD) by producing secondary beams of unstable nuclei. The experimental program of the RIBRAS covers the study of elastic and inelastic scattering with the objective to study the interaction potential and the reaction mechanisms between weakly bound (RIB) and halo (6He and 8B) projectiles on light, medium and heavy mass targets. With highly purified beams, the study of resonant elastic scattering and resonant transfer reactions, using inverse kinematics and thick targets, have also been included in our recent experimental program.

Radioactive ion beam facilities at INFN LNS

International Nuclear Information System (INIS)

Rifuggiato, D; Calabretta, L; Celona, L; Chines, F; Cosentino, L; Cuttone, G; Finocchiaro, P; Pappalardo, A; Re, M; Rovelli, A

2011-01-01

Radioactive ion beams are produced at INFN- Laboratori Nazionali del Sud (LNS) by means of the two operating accelerators, the Tandem and the Superconducting Cyclotron (CS), originally designed to accelerate stable beams. Both the ISOL (Isotope Separation On Line) and the IFF (In-Flight Fragmentation) methods are exploited to produce RIBs in two different ways at different energies: in the first case, the Cyclotron is the primary accelerator and the Tandem accelerates the secondary beams, while in the second case radioactive fragments are produced by the Cyclotron beam in a thin target with energies comparable to the primary beam energy. The ISOL facility is named EXCYT (Exotics at the Cyclotron and Tandem) and was commissioned in 2006, when the first radioactive beam ( 8 Li) has been produced. The IFF installation is named FRIBs (in Flight Radioactive Ion Beams), and it has started to produce radioactive beams in 2001, placing a thin target in the extraction beam line of the Cyclotron. The development of both facilities to produce and accelerate radioactive ion beams at LNS, is briefly described, with some details on the future prospects that are presently under consideration or realization.

Flying wire beam profile monitor at the J-PARC MR

International Nuclear Information System (INIS)

Igarashi, Susumu; Arakawa, Dai; Hashimoto, Yoshinori; Teshima, Masaki; Toyama, Takeshi; Hanamura, Kotoku

2008-01-01

A flying wire beam profile monitor has been assembled and installed at the main ring of the Japan Proton Accelerator Research Complex. The monitor is to measure the horizontal beam profile using a carbon fiber of 7 μmφ. The fiber crosses the beam with the speed of 10 m/s. Secondary particles from the beam-wire scattering is detected using a scintillation counter. The scintillator signal as a function of the wire position is to be reconstructed as a beam profile. The high scanning speed and the minimum material are necessary for the accurate beam profile measurement. The monitor has been operated in the beam commissioning run of the main ring. The beam profile data have been successfully acquired after the reduction of the beam background. (author)

Beam collimator for a particle accelerator. [German patent

Energy Technology Data Exchange (ETDEWEB)

Benedetti, R

1977-12-01

The beam collimator for the electron beam coming from an electron accelerator consists of aperture plates and penumbra trimmers aligned parallel to them. To protect the patient from scattered radiation, additional tube plates are arranged between the radiation source and the patient. Continuous matching of the radiation field to the dimensions of a focus is achieved by providing a support plate outside the beam path which holds the tube plates. In this arrangement, the tube plates are aligned parallel to the edges of the aperture plates limiting the beam cone. The tube plates have different widths. They can be moved out of the beam path. Lining the inner walls of the tube plates with acrylic glass prevents the generation of secondary electrons and X-rays.

An MLC-based version for the ecliptic method for the determination of backscatter into the beam monitor chambers in photon beams of medical accelerators

International Nuclear Information System (INIS)

Nelli, Flavio Enrico

2016-01-01

A very simple method to measure the effect of the backscatter from secondary collimators into the beam monitor chambers in linear accelerators equipped with multi-leaf collimators (MLC) is presented here. The backscatter to the monitor chambers from the upper jaws of the secondary collimator was measured on three beam-matched linacs by means of three methods: this new methodology, the ecliptic method, and assessing the variation of the beam-on time per monitor unit with dose rate feedback disabled. This new methodology was used to assess the backscatter characteristics of asymmetric over-traveling jaws. Excellent agreement between the backscatter values measured using the new methodology introduced here and the ones obtained using the other two methods was established. The experimental values reported here differ by less than 1 % from published data. The sensitivity of this novel technique allowed differences in backscatter due to the same opening of the jaws, when placed at different positions on the beam path, to be resolved. The introduction of the ecliptic method has made the determination of the backscatter to the monitor chambers an easy procedure. The method presented here for machines equipped with MLCs makes the determination of backscatter to the beam monitor chambers even easier, and suitable to characterize linacs equipped with over-traveling asymmetric secondary collimators. This experimental procedure could be simply implemented to fully characterize the backscatter output factor constituent when detailed dosimetric modeling of the machine’s head is required. The methodology proved to be uncomplicated, accurate and suitable for clinical or experimental environments.

Commissioning of polarized-proton and antiproton beams at Fermilab

International Nuclear Information System (INIS)

Yokosawa, A.

1988-01-01

The author described the polarized-proton and polarized-antiproton beams up to 200 GeV/c at Fermilab. The beam line, called MP, consists of the 400-m long primary and 350-m long secondary beam line followed by 60-m long experimental hall. We discuss the characteristics of the polarized beams. The Fermilab polarization projects are designated at E-581/704 initiated and carried out by an international collaboration, Argonne (US), Fermilab (US), Kyoto-Kyushu-Hiroshima-KEK (Japan), LAPP (France), Northwestern University (US), Los Alamos Laboratory (US), Rice (US), Saclay (France), Serpukhov (USSR), INFN Trieste (Italy), and University of Texas (US)

Beam losses in heavy ion drivers

CERN Document Server

Mustafin, E R; Hofmann, I; Spiller, P J

2002-01-01

While beam loss issues have hardly been considered in detail for heavy ion fusion scenarios, recent heavy ion machine developments in different labs (European Organization for Nuclear Research (CERN), Gesellschaft fur Schwerionenforschung (GSI), Institute for Theoretical and Experimental Physics (ITEP), Relativistic Heavy-Ion Collider (RHIC)) have shown the great importance of beam current limitations due to ion losses. Two aspects of beam losses in heavy ion accelerators are theoretically considered: (1) secondary neutron production due to lost ions, and (2) vacuum pressure instability due to charge exchange losses. Calculations are compared and found to be in good agreement with measured data. The application to a Heavy-Ion Driven Inertial Fusion (HIDIF) scenario is discussed. 12 Refs.

Beam-induced heat loads on the beam screens of the inner triplets for the HL-LHC

CERN Document Server

Skripka, Galina; CERN. Geneva. ATS Department

2018-01-01

The expected heat load induced on the beam screens has been evaluated for the triplet assemblies in the four experimental Insertion Regions (IRs) of the HL-LHC. The contribution from electron cloud effects has been estimated using PyECLOUD macroparticle simulations. The presence of a surface treatment for the reduction of the Secondary Electron Yield has been taken into account. The contribution from the impedance of the beam screen has been evaluated taking into account the impact of the temperature and of the magnetic field on the resistivity of the surface.

The role of space charge compensation for ion beam extraction and ion beam transport (invited)

International Nuclear Information System (INIS)

Spädtke, Peter

2014-01-01

Depending on the specific type of ion source, the ion beam is extracted either from an electrode surface or from a plasma. There is always an interface between the (almost) space charge compensated ion source plasma, and the extraction region in which the full space charge is influencing the ion beam itself. After extraction, the ion beam is to be transported towards an accelerating structure in most cases. For lower intensities, this transport can be done without space charge compensation. However, if space charge is not negligible, the positive charge of the ion beam will attract electrons, which will compensate the space charge, at least partially. The final degree of Space Charge Compensation (SCC) will depend on different properties, like the ratio of generation rate of secondary particles and their loss rate, or the fact whether the ion beam is pulsed or continuous. In sections of the beam line, where the ion beam is drifting, a pure electrostatic plasma will develop, whereas in magnetic elements, these space charge compensating electrons become magnetized. The transport section will provide a series of different plasma conditions with different properties. Different measurement tools to investigate the degree of space charge compensation will be described, as well as computational methods for the simulation of ion beams with partial space charge compensation

Beam induced heat loads on the beam-screens of the twin-bore magnets in the IRs of the HL-LHC

CERN Document Server

Iadarola, Giovanni; Rumolo, Giovanni

2016-01-01

The expected heat load induced on the beam screens has been evaluated for all the twin-bore magnets in the Insertion Regions (IRs) of the HL-LHC. The contribution from the impedance of the beam screen has been evaluated taking into account the presence of a longitudinal weld in the beam screen and the impact of the temperature and of the magnetic field on the resistivity of the surface. The contribution coming from electron cloud effects has been evaluated for different values of the Secondary Electron Yield of the surface based PyECLOUD build-up simulations.

Monte Carlo study of radial energy deposition from primary and secondary particles for narrow and large proton beamlet source models

International Nuclear Information System (INIS)

Peeler, Christopher R; Titt, Uwe

2012-01-01

In spot-scanning intensity-modulated proton therapy, numerous unmodulated proton beam spots are delivered over a target volume to produce a prescribed dose distribution. To accurately model field size-dependent output factors for beam spots, the energy deposition at positions radial to the central axis of the beam must be characterized. In this study, we determined the difference in the central axis dose for spot-scanned fields that results from secondary particle doses by investigating energy deposition radial to the proton beam central axis resulting from primary protons and secondary particles for mathematical point source and distributed source models. The largest difference in the central axis dose from secondary particles resulting from the use of a mathematical point source and a distributed source model was approximately 0.43%. Thus, we conclude that the central axis dose for a spot-scanned field is effectively independent of the source model used to calculate the secondary particle dose. (paper)

Experiments with neutron-rich isomeric beams

International Nuclear Information System (INIS)

Rykaczewski, K.; Lewitowicz, M.; Pfuetzner, M.

1998-01-01

A review of experimental results obtained on microsecond-isomeric states in neutron-rich nuclei produced in fragmentation reactions and studied with SISSI-Alpha-LISE3 spectrometer system at GANIL Caen is given. The perspectives of experiments based on secondary reactions with isomeric beams are presented

Fast automatic system for measurements of beam parameters of the MMF linac

International Nuclear Information System (INIS)

Reinhardt-Nickulin, P.; Bragin, S.; Ilinsky, N.; Senichev, Yu.

1992-01-01

Fast transverse beam profile and current monitoring systems have been tested at the Linear Accelerator of Moscow Meson Factory. The signals for each system are derived from multiwire secondary emission chamber and beam current transformer. Each beam pulse is digitized by fast ADC's. There are two modes for systems. First one is for detailed beam adjustment and second one is for normal 100 Hz rate of the MMF Linac. Essential features of the hardware, software, data acquisition, measurement accuracy and beam results are presented. (author)

Beam Dynamics Studies for High-Intensity Beams in the CERN Proton Synchrotron

CERN Document Server

AUTHOR|(CDS)2082016; Benedikt, Michael

With the discovery of the Higgs boson, the existence of the last missing piece of the Standard Model of particle physics (SM) was confirmed. However, even though very elegant, this theory is unable to explain, for example, the generation of neutrino masses, nor does it account for dark energy or dark matter. To shed light on some of these open questions, research in fundamental particle physics pursues two complimentary approaches. On the one hand, particle colliders working at the high-energy frontier, such as the Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN), located in Geneva, Switzerland, are utilized to investigate the fundamental laws of nature. Alternatively, fixed target facilities require high-intensity beams to create a large flux of secondary particles to investigate, for example, rare particle decay processes, or to create neutrino beams. This thesis investigates limitations arising during the acceleration of high-intensity beams at the CERN Proton Synchrotro...

Induced radioactivity of a GSO scintillator by secondary fragments in carbon ion therapy and its effects on in-beam OpenPET imaging.

Science.gov (United States)

Hirano, Yoshiyuki; Nitta, Munetaka; Nishikido, Fumihiko; Yoshida, Eiji; Inadama, Naoko; Yamaya, Taiga

2016-07-07

The accumulation of induced radioactivity within in-beam PET scanner scintillators is of concern for its long-term clinical usage in particle therapy. To estimate the effects on OpenPET which we are developing for in-beam PET based on GSOZ (Zi doped Gd2SiO5), we measured the induced radioactivity of GSO activated by secondary fragments in a water phantom irradiation by a (12)C beam with an energy of 290 MeV u(-1). Radioisotopes of Na, Ce, Eu, Gd, Nd, Pm and Tb including positron emitters were observed in the gamma ray spectra of the activated GSO with a high purity Ge detector and their absolute radioactivities were calculated. We used the Monte Carlo simulation platform, Geant4 in which the observed radioactivity was assigned to the scintillators of a precisely reproduced OpenPET and the single and coincidence rates immediately after one treatment and after one-year usage were estimated for the most severe conditions. Comparing the highest coincidence rate originating from the activated scintillators (background) and the expected coincidence rate from an imaging object (signal), we determined the expected signal-to-noise ratio to be more than 7 within 3 min and more than 10 within 1 min from the scan start time. We concluded the effects of scintillator activation and their accumulation on the OpenPET imaging were small and clinical long-term usage of the OpenPET was feasible.

Electron and photon spread contributions to the radiological penumbra for small monoenergetic x-ray beam (<=2 MeV)

Science.gov (United States)

Pignol, Jean-Philippe; Keller, Brian M.

2009-05-01

Our team has previously published that submegavoltage photons could significantly improve the radiological penumbra for small size radiation fields. The present work uses Monte Carlo simulation to evaluate the contributions of secondary electrons and photon scatter to the penumbra region for various field sizes (5, 10, 20, and 40 mm in diameters) and for various monoenergetic photon beams (200, 400, 600, 800, 1000, and 2000 keV, and a standard 6 MV beam), minimizing geometrical and transmission penumbra. For field sizes less than 2 cm in diameter, photon scatter is negligible such that the secondary electrons are the main contributor to the radiological penumbra. Reducing the photon beam energy to the submegavoltage range reduces the range of secondary electrons and eventually improves the beam boundary sharpness. Provided that the geometrical penumbra and patient immobilization system are optimized, submegavoltage photon beams with effective photon energies in the 300 to 600 keV range, present significant advantages for multiple beam stereotactic irradiations of tumors less than 2 cm in diameter.

Influence of ion beam and geometrical parameters on properties of Si thin films grown by Ar ion beam sputtering

Energy Technology Data Exchange (ETDEWEB)

Bundesmann, Carsten; Feder, Rene; Neumann, Horst [Leibniz-Institut fuer Oberflaechenmodifizierung e.V., Leipzig (Germany)

2012-07-01

Ion beam sputtering (IBS) offers, in contrast to other physical vapour deposition techniques, such as magnetron sputtering or electron beam evaporation, the opportunity to change the properties of the layer forming particles (sputtered and scattered particles) by varying ion beam parameters (ion species, ion energy) and geometrical parameters (ion incidence angle, emission angle). Consequently, these effects can be utilized to tailor thin film properties [1]. The goal is to study systematically the correlations between the primary and secondary parameters and, at last, the effects on the properties of Si thin films, such as optical properties, stress, surface topography and composition. First experimental results are presented for Ar-ion sputtering of Si.

Very High Radiation Detector for the LHC BLM System Based on Secondary Electron Emission

CERN Document Server

Dehning, B; Holzer, EB; Kramer, D

2007-01-01

Beam Loss Monitoring (BLM) system plays a vital role in the active protection of the LHC accelerators elements. It should provide the number of particles lost from the primary hadron beam by measuring the radiation field induced by their interaction with matter surrounding the beam pipe. The LHC BLM system will use ionization chambers as standard detectors but in the areas where very high dose rates are expected, the Secondary Emission Monitor (SEM) chambers will be employed because of their high linearity, low sensitivity and fast response. The SEM needs a high vacuum for proper operation and has to be functional for up to 20 years, therefore all the components were designed according to the UHV requirements and a getter pump was included. The SEM electrodes are made of Ti because of its Secondary Emission Yield (SEY) stability. The sensitivity of the SEM was modeled in Geant4 via the Photo-Absorption Ionization module together with custom parameterization of the very low energy secondary electron production...

THE SECONDARY EXTINCTION CORRECTION

Energy Technology Data Exchange (ETDEWEB)

Zachariasen, W. H.

1963-03-15

It is shown that Darwin's formula for the secondary extinction correction, which has been universally accepted and extensively used, contains an appreciable error in the x-ray diffraction case. The correct formula is derived. As a first order correction for secondary extinction, Darwin showed that one should use an effective absorption coefficient mu + gQ where an unpolarized incident beam is presumed. The new derivation shows that the effective absorption coefficient is mu + 2gQ(1 + cos/sup 4/2 theta )/(1 plus or minus cos/sup 2/2 theta )/s up 2/, which gives mu + gQ at theta =0 deg and theta = 90 deg , but mu + 2gQ at theta = 45 deg . Darwin's theory remains valid when applied to neutron diffraction. (auth)

Characteristics of Sissi beams in the transport lines of Ganil

International Nuclear Information System (INIS)

Nghiem, P.; Payet, J.; Tkatchenko, A.

1994-01-01

This study is the following of the Sissi primary beam characteristics definition. Its aim is to determine the performances in resolution and in transmission of transport lines which guide the secondary beams until the experimentation rooms. The first part concerns the study of the secondary order characteristics with the help of BETA matrix code for the nominal case. The second part is the same study but but of superior orders carried out with the Zgoubi program. The third part consists to search new regulating to minimise the losses of particles due to the effect of non-linearity. (O.L.). 3 refs., 34 figs., 5 tabs

The cryogenic silicon Beam Tracker of NA60 for heavy ion and proton beams

International Nuclear Information System (INIS)

Rosinsky, P.; Borer, K.; Casagrande, L.; Devaux, A.; Granata, V.; Guettet, N.; Hess, M.; Heuser, J.; Jarron, P.; Li, Z.; Lourenco, C.; Manso, F.; Niinikoski, T.O.; Palmieri, V.G.; Radermacher, E.; Shahoyan, R.; Sonderegger, P.

2003-01-01

The cryogenic silicon Beam Tracker of NA60 is the first detector based on the Lazarus effect used in a high-energy physics experiment. It employs single-sided silicon strip sensors of 50 μm pitch operated at a temperature of 130 K. Two tracking stations determine the transverse coordinates of the interaction point at the target with 20 μm resolution, to improve the determination of the offset of secondary vertices. This impact parameter measurement allows NA60 to distinguish between prompt dimuons and muon pairs from D-meson decays. The detector concept and technical feasibility have been demonstrated in beam time periods between 1999 and 2002

Process and device of elementary and chemical analysis of a sample through a spectral analysis of the secondary electron energies

International Nuclear Information System (INIS)

Le Gressus, Claude; Massignon, Daniel; Sopizet, Rene.

1975-01-01

The present invention relates to a method of chemical and elementary analysis of samples through a spectral analysis of secondary electrons (Auger electrons) emitted from said sample under a primary monokinetic electron beam concentrated on its surface. Said method is characterized in that the intensity of the primary monokinetic electron beam emitted from an electron gun is modulated at a frequency ω; and in that the secondary electrons of energy E emitted from the sample are then collected. A reference voltage corresponding to the modulation in intensity of the primary electron beam is applied at the input of a phase sensitive detector together with a voltage proportional to the intensity of the flux of said collected secondary electrons to obtain at the output of said detector a voltage proportional to the number of the secondary electrons of energy E. The secondary emission energy spectrum of the sample is then plotted [fr

A possible method to produce a polarized antiproton beam at intermediate energies

International Nuclear Information System (INIS)

Spinka, H.; Vaandering, E.W.; Hofmann, J.S.

1994-01-01

A feasible and conservative design for a medium energy polarized antiproton beam has been presented. The design requires an intense beam of unpolarized antiprotons (≥ 10 7 /sec) from a typical secondary beam line in order to achieve reasonable anti pp elastic scattering count rates. All three beam spin directions can be achieved. Methods were discussed to reverse the spin directions in modest times, and to change to a polarized proton beam if desired. It is expected that experiments with such a beam would have a profound effect on the understanding of the anti NN interaction at intermediate energies

Failure analysis of prestressed concrete beam under impact loading

International Nuclear Information System (INIS)

Ishikawa, N.; Sonoda, Y.; Kobayashi, N.

1993-01-01

This paper presents a failure analysis of prestressed concrete (PC) beam under impact loading. At first, the failure analysis of PC beam section is performed by using the discrete section element method in order to obtain the dynamic bending moment-curvature relation. Secondary, the failure analysis of PC beam is performed by using the rigid panel-spring model. Finally, the numerical calculation is executed and is compared with the experimental results. It is found that this approach can simulate well the experiments at the local and overall failure of the PC beam as well as the impact load and the displacement-time relations. (author)

The Performance of the New TCDQ System in the LHC Beam Dumping Region

CERN Document Server

Presland, Andrew; Weterings, Wim

2005-01-01

The superconducting quadrupole magnet Q4 and other downstream LHC machine elements risk destruction in the event of a beam dump that is not synchronised with the abort gap. In order to protect these elements, a single sided mobile graphite diluter block TCDQ, in combination with a two-sided secondary collimator TCS and iron shield TCDQM, will be installed in front of Q4. This protection system should also intercept spurious particles in the beam abort gap to prevent quenches from occurring during regular beam aborts, and must also intercept the particles from the secondary halo during low beam lifetime without provoking quenches. The conceptual design of the TCDQ system is briefly presented, with the load conditions and performance criteria. The FLUKA simulations are described results discussed in the context of the expected performance levels for LHC operation.

Beam Collimation Studies for the ILC Positron Source

Energy Technology Data Exchange (ETDEWEB)

Drozhdin, A.; /Fermilab; Nosochkov, Y.; Zhou, F.; /SLAC

2008-06-26

Results of the collimation studies for the ILC positron source beam line are presented. The calculations of primary positron beam loss are done using the ELEGANT code. The secondary positron and electron beam loss, the synchrotron radiation along the beam line and the bremsstrahlung radiation in the collimators are simulated using the STRUCT code. The first part of the collimation system, located right after the positron source target (0.125 GeV), is used for protection of the RF Linac sections from heating and radiation. The second part of the system is used for final collimation before the beam injection into the Damping Ring at 5 GeV. The calculated power loss in the collimation region is within 100 W/m, with the loss in the collimators of 0.2-5 kW. The beam transfer efficiency from the target to the Damping Ring is 13.5%.

Radioactive nuclear beam facilities based on projectile fragmentation

International Nuclear Information System (INIS)

Sherrill, B.M.

1992-01-01

The production of radioactive beams using direct separation techniques is discussed. The reaction mechanisms which can be used to produce radioactive beams with these techniques can be broadly divided into three groups, projectile fragmentation, nucleon transfer, and Coulomb disassociation. Radioactive nuclei produced in these ways have large forward momenta with relatively sharp angular distributions peaked near zero degrees which are suitable for collection with magnetic devices. Secondary beam intensities of up to a few percent of the primary beam intensity are possible, although depending on the production mechanism the beam emittance may be poor. Further beam purification can be achieved using atomic processes with profiled energy degraders. The features of the production reaction mechanism, separation techniques, and a review of world wide efforts are presented. The advantages and disadvantages of the method are presented, with discussion of techniques to overcome some of the disadvantages. (Author)

IFR code for secondary particle dynamics

International Nuclear Information System (INIS)

Teague, M.R.; Yu, S.S.

1985-01-01

A numerical simulation has been constructed to obtain a detailed, quantitative estimate of the electromagnetic fields and currents existing in the Advanced Test Accelerator under conditions of laser guiding. The code treats the secondary electrons by particle simulation and the beam dynamics by a time-dependent envelope model. The simulation gives a fully relativistic description of secondary electrons moving in self-consistent electromagnetic fields. The calculations are made using coordinates t, x, y, z for the electrons and t, ct-z, r for the axisymmetric electromagnetic fields and currents. Code results, showing in particular current enhancement effects, will be given

Optical design of beam lines at the KEK-PS new experimental hall

International Nuclear Information System (INIS)

Tanaka, K.H.; Ieiri, M.; Noumi, H.; Minakawa, M.; Yamanoi, Y.; Kato, Y.; Ishii, H.; Suzuki, Y.; Takasaki, M.

1995-01-01

A new counter experimental hall [K.H. Tanaka et al., IEEE Trans. Magn. 28 (1992) 697] was designed and constructed at the KEK 12-GeV Proton Synchrotron (KEK-PS). The extracted proton beam from the KEK-PS is introduced to the new hall through the newly-prepared primary beam line, EP1, and hits two production targets in cascade. The upstream target provides secondary particles to the low momentum (0.4-0.6 GeV/c) separated beam line, K5, and the downstream target is connected to the medium momentum (0.6-2.0 GeV/c) separated beam line, K6. Several new ideas were employed in the beam optical designs of EP1, K5 and K6 in order to increase the number and the purity of the short-lived secondary particles, such as kaons and pions, under the limited energy and intensity of the primary protons provided by the KEK-PS. These new ideas are described in this paper as well as the first commissioning results. (orig.)

Monoatomic and cluster beam effect on ToF-SIMS spectra of self-assembled monolayers on gold

Energy Technology Data Exchange (ETDEWEB)

Tuccitto, N. [Dipartimento di Scienze Chimiche Universita degli Studi di Catania, v.le A. Doria 6, 95125, Catania (Italy)], E-mail: n.tuccitto@unict.it; Torrisi, V.; Delfanti, I.; Licciardello, A. [Dipartimento di Scienze Chimiche Universita degli Studi di Catania, v.le A. Doria 6, 95125, Catania (Italy)

2008-12-15

Self-assembled monolayers represent well-defined systems that is a good model surface to study the effect of primary ion beams used in secondary ion mass spectrometry. The effect of polyatomic primary beams on both aliphatic and aromatic self-assembled monolayers has been studied. In particular, we analysed the variation of the relative secondary ion yield of both substrate metal-cluster (Au{sub n}{sup -}) in comparison with the molecular ions (M{sup -}) and clusters (M{sub x}Au{sub y}{sup -}) by using Bi{sup +}, Bi{sub 3}{sup +}, Bi{sub 5}{sup +} beams. Moreover, the differences in the secondary ion generation efficiency are discussed. The main effect of the cluster beams is related to an increased formation of low-mass fragments and to the enhancement of the substrate related gold-clusters. The results show that, at variance of many other cases, the static SIMS of self-assembled monolayers does not benefit of the use of polyatomic primary ions.

Current neutralization of nanosecond risetime, high-current electron beam

International Nuclear Information System (INIS)

Lidestri, J.P.; Spence, P.W.; Bailey, V.L.; Putnam, S.D.; Fockler, J.; Eichenberger, C.; Champney, P.D.

1991-01-01

This paper reports that the authors have recently investigated methods to achieve current neutralization in fast risetime (<3 ns) electron beams propagating in low-pressure gas. For this investigation, they injected a 3-MV, 30-kA intense beam into a drift cell containing gas pressures from 0.10 to 20 torr. By using a fast net current monitor (100-ps risetime), it was possible to observe beam front gas breakdown phenomena and to optimize the drift cell gas pressure to achieve maximum current neutralization. Experimental observations have shown that by increasing the drift gas pressure (P ∼ 12.5 torr) to decrease the mean time between secondary electron/gas collisions, the beam can propagate with 90% current neutralization for the full beam pulsewidth (16 ns)

Method and apparatus for real time imaging and monitoring of radiotherapy beams

Science.gov (United States)

Majewski, Stanislaw [Yorktown, VA; Proffitt, James [Newport News, VA; Macey, Daniel J [Birmingham, AL; Weisenberger, Andrew G [Yorktown, VA

2011-11-01

A method and apparatus for real time imaging and monitoring of radiation therapy beams is designed to preferentially distinguish and image low energy radiation from high energy secondary radiation emitted from a target as the result of therapeutic beam deposition. A detector having low sensitivity to high energy photons combined with a collimator designed to dynamically image in the region of the therapeutic beam target is used.

Tests of SEC stability in high flux proton beams

International Nuclear Information System (INIS)

Agoritsas, V.; Witkover, R.L.

1979-01-01

The Secondary Emission Chamber (SEC) is used to measure the beam intensity in slow extracted beam channels of proton synchrotrons around the world. With the improvements in machine intensity, these monitors have been exposed to higher flux conditions than in the past. A change in sensitivity of up to 25% has been observed in the region around the beam spot. Using SEC's of special construction, a series of tests was performed at FNAL, BNL-AGS and CERN-PS. The results of these tests and conclusions about the construction of more stable SEC's are presented

Study on neutron beam probe. Study on the focused neutron beam

Energy Technology Data Exchange (ETDEWEB)

Kotajima, Kyuya; Suzuki, K.; Fujisawa, M.; Takahashi, T.; Sakamoto, I. [Tohoku Univ., Sendai (Japan). Faculty of Engineering; Wakabayashi, T.

1998-03-01

A monoenergetic focused neutron beam has been produced by utilizing the endoenergetic heavy ion reactions on hydrogen. To realize this, the projectile heavy ion energy should be taken slightly above the threshold energy, so that the excess energy converted to the neutron energy should be very small. In order to improve the capability of the focused neutron beam, some hydrogen stored metal targets have also been tested. Separating the secondary heavy ions (associated particles) from the primary ions (accelerated particles) by using a dipole magnet, a rf separator, and a particle identification system, we could directly count the produced neutrons. This will leads us to the possibility of realizing the standard neutron field which had been the empty dream of many neutron-related researchers in the world. (author)

Physical properties of charged particle beams for use in radiotherapy

International Nuclear Information System (INIS)

Knapp, E.A.

1975-01-01

The physical properties of the possible charged particle beams used for cancer radiotherapy are reviewed. Each property is discussed for all interesting particles (π, p, α, Ne ion) and the differences are emphasized. This is followed by a short discussion of the several beam delivery systems used in particle therapy today, emphasizing the differences in the problems for the several different radiations, particularly the differences between the accelerated particle beams and those of a secondary nature. Dose calculation techniques are described

Experimental study of the stability of a neutralized electron beam

International Nuclear Information System (INIS)

Kudelainen, V.I.; Parkhomchuk, V.V.; Pestrikov, D.V.

1983-01-01

Results are reported from measurements of the spectral properties of a long neutralized electron beam in the NAP-M proton storage ring. It is shown that when the number of secondary electrons is small, both the longitudinal and the transverse oscillations are strongly damped, so that beam instability is suppressed. The current density of the neutralized electron beam produced in the experiments was approx.10 2 times greater than the theoretical value determined from the instability threshold for nonaxisymmetric oscillations

Electron beam instabilities in unmagnetized plasmas via the Stieltjes transform (linear theory and nonlinear mode coupling)

International Nuclear Information System (INIS)

Krishan, S.

2007-01-01

The Stieltjes transform has been used in place of a more common Laplace transform to determine the time evolution of the self-consistent field (SCF) of an unmagnetized semi-infinite plasma, where the plasma electrons together with a primary and a low-density secondary electron beam move perpendicular to the boundary surface. The secondary beam is produced when the primary beam strikes the grid. Such a plasma system has been investigated by Griskey and Stanzel [M. C. Grisky and R. L. Stenzel, Phys. Rev. Lett. 82, 556 (1999)]. The physical phenomenon, observed in their experiment, has been named by them as ''secondary beam instability.'' The character of the instability observed in the experiment is not the same as predicted by the conventional treatments--the field amplitude does not grow with time. In the frequency spectrum, the theory predicts peak values in the amplitude of SCF at the plasma frequency of plasma and secondary beam electrons, decreasing above and below it. The Stieltjes transform for functions, growing exponentially in the long time limit, does not exist, while the Laplace transform technique gives only exponentially growing solutions. Therefore, it should be interesting to know the kind of solutions that an otherwise physically unstable plasma will yield. In the high-frequency limit, the plasma has been found to respond to any arbitrary frequency of the initial field differentiated only by the strength of the resulting SCF. The condition required for exponential growth in the conventional treatments, and the condition for maximum amplitude (with respect to frequency) in the present treatment, have been found to be the same. Nonlinear mode coupling between the modes excited by the plasma electrons and the low-density secondary beam gives rise to two frequency-dependent peaks in the field amplitude, symmetrically located about the much stronger peak due to the plasma electrons, as predicted by the experiment

Upgrade of the Proton West secondary beamline

International Nuclear Information System (INIS)

Spiegel, L.

1989-01-01

As originally designed and operated, protons entering PW6 were steered by a series of EPB dipoles into a single interaction length beryllium target, some 43 feet from the enclosure wall. Ensuing secondary beams, either p + /π + or p - /π - , were collected by a string of quadrupoles following the target, steered westward, away from the Proton Center line, through PW6 and PW7, and ultimately focussed on experiment production targets located within the large PW8 hall. Around the Spring of 1988 it was decided to upgrade the existing Proton West secondary beamline to allow for transport of a primary proton beam, anticipated to be either 800 or 900 GeV/c, through PW8. This upgrade project, which is now nearing completion, was largely motivated by the then recent approval of E-771, a hadronic beauty production experiment located in PW8. E-771 represents the third in a series of experiments for the large-acceptance dimuon spectrometer presently located at the end of the Proton West beamline. This Technical Memo is a summary of the upgrade --- an explanation of the underlying strategy and a documentation of the final locations of the secondary beamline elements. 6 refs., 2 figs., 2 tabs

High spin isomer beam line at RIKEN

Energy Technology Data Exchange (ETDEWEB)

Kishida, T.; Ideguchi, E.; Wu, H.Y. [Institute of Physical and Chemical Research, Saitama (Japan)] [and others

1996-12-31

Nuclear high spin states have been the subject of extensive experimental and theoretical studies. For the production of high spin states, fusion reactions are usually used. The orbital angular momentum brought in the reaction is changed into the nuclear spin of the compound nucleus. However, the maximum induced angular momentum is limited in this mechanism by the maximum impact parameter of the fusion reaction and by the competition with fission reactions. It is, therefore, difficult to populate very high spin states, and as a result, large {gamma}-detector arrays have been developed in order to detect subtle signals from such very high spin states. The use of high spin isomers in the fusion reactions can break this limitation because the high spin isomers have their intrinsic angular momentum, which can bring the additional angular momentum without increasing the excitation energy. There are two methods to use the high spin isomers for secondary reactions: the use of the high spin isomers as a target and that as a beam. A high spin isomer target has already been developed and used for several experiments. But this method has an inevitable shortcoming that only {open_quotes}long-lived{close_quotes} isomers can be used for a target: {sup 178}Hf{sup m2} (16{sup +}) with a half-life of 31 years in the present case. By developing a high spin isomer beam, the authors can utilize various short-lived isomers with a short half-life around 1 {mu}s. The high spin isomer beam line of RIKEN Accelerator Facility is a unique apparatus in the world which provides a high spin isomer as a secondary beam. The combination of fusion-evaporation reaction and inverse kinematics are used to produce high spin isomer beams; in particular, the adoption of `inverse kinematics` is essential to use short-lived isomers as a beam.

Fundamental properties of secondary negative ion emission by sputtering

International Nuclear Information System (INIS)

Shimizu, Toshiki; Tsuji, Hiroshi; Ishikawa, Junzo

1989-01-01

The report describes some results obtained from preliminary experiments on secondary negative ion emission from a cesiated surface by Xe-ion beam sputtering, which give the production probability. A measuring system is constructed for secondary negative ion emission. The system consists of a microwave ion source with a lens, a sputtering target holder with a heater, a cesium oven, a limiting aperture with a substrate for deposition, a negative-ion extractor and lens, and a ExB type mass separator. Observations are made on the dependence of negative ion current on cesium supply, dependence of negative ion current on target temperature, and negative ion production probability. The cesium supply and the target temperature are found to strongly influence the negative ion emission. By controlling these factors, the optimum condition for secondary negative ion emission is achieved with a minimum surface work function. The production probability of the negative ion is found to be very high, about 20% for carbon. Therefore, the secondary negative ion emission is considered a useful and highly efficient method to obtain high current ion beams. The constant in the Rasser's theoretical equation is experimentally determined to be 4.1 x 10 -4 eV sec/m. (N.K.)

Construction and tests of an in-beam PET-like demonstrator for hadrontherapy beam ballistic control

Energy Technology Data Exchange (ETDEWEB)

Montarou, G., E-mail: montarou@clermont.in2p3.fr [Clermont University, Blaise Pascal University, CNRS/IN2P3, Laboratoire de Physique Corpusculaire, BP 10448, Clermont-Ferrand F-63000 (France); Bony, M.; Busato, E.; Chadelas, R. [Clermont University, Blaise Pascal University, CNRS/IN2P3, Laboratoire de Physique Corpusculaire, BP 10448, Clermont-Ferrand F-63000 (France); Donnarieix, D. [Centre Jean Perrin, Service de Physique Médicale, Clermont-Ferrand F-63000 (France); Force, P.; Guicheney, C.; Insa, C.; Lambert, D.; Lestand, L.; Magne, M.; Martin, F. [Clermont University, Blaise Pascal University, CNRS/IN2P3, Laboratoire de Physique Corpusculaire, BP 10448, Clermont-Ferrand F-63000 (France); Millardet, C. [Centre Jean Perrin, Service de Physique Médicale, Clermont-Ferrand F-63000 (France); Nivoix, M.; Podlyski, F.; Rozes, A. [Clermont University, Blaise Pascal University, CNRS/IN2P3, Laboratoire de Physique Corpusculaire, BP 10448, Clermont-Ferrand F-63000 (France)

2017-02-11

We present the first results obtained with a detector, called Large Area Pixelized Detector (LAPD), dedicated to the study the ballistic control of the beam delivered to the patient by in-beam and real time detection of secondary particles, emitted during its irradiation in the context of hadrontherapy. These particles are 511 keV γ from the annihilation of a positron issued from the β{sup +} emitters induced in the patient tissues along the beam path. The LAPD basic concepts are similar to a conventional PET camera. The 511 keV γ are detected and the reconstructed lines of response allow to measure the β{sup +} activity distribution. Nevertheless, when trying to use γ from positron annihilation for the ballistic control in hadrontherapy, the large prompt γ background should be taken into account and properly rejected. First reconstruction results, obtained with a phantom filled with a high intensity FDG source at the cancer research centre of Clermont-Ferrand are shown. We also report results of measurements performed at the Heidelberg Ion-Beam Therapy Centre with one third of the detector, using proton and carbon ion beams.

Fundamental studies on electron beam welding on heat resistant superalloys for nuclear plants, 6

International Nuclear Information System (INIS)

Susei, Syuzo; Shimizu, Sigeki; Nagai, Hiroyoshi; Aota, Toshikazu; Satoh, Keisuke

1980-01-01

In this report, base metal of superalloys for nuclear plants, its electron beam and TIG weld joints were compared with each other in the mechanical properties. Obtained conclusions are summarized as follows: 1) TIG weld joint is superior to electron beam weld joint and base metal in 0.2% proof stress irrespective of the material, and electron beam weld joint is also superior to base metal. There is an appreciable difference in tensile stress between base metal and weld joint regardless of the materials. Meanwhile, electron beam weld joint is superior to TIG weld joint in both elongation and reduction of area. 2) Electron beam weld joint has considerably higher low-cycle fatigue properties at elevated temperatures than TIG weld joint, and it is usually as high as base metal. 3) In the secondary creep rate, base metal of Hastelloy X (HAEM) has higher one than its weld joints. However, electron beam weld joint is nearly comparable to the base metal. 4) There is hardly any appreciable difference between base metal and weld joint in the creep rupture strength without distinction of the material. In the ductility, base metal is much superior and is followed by electron beam weld joint and TIG weld joint in the order of high ductility. However, electron beam weld joint is rather comparable to base metal. 5) In consideration of welded pipe with a circumferential joint, the weld joint should be evaluated in terms of secondary creep rate, elongation and rupture strength. As the weld joint of high creep rupture strength approaches the base metal in the secondary creep rate and the elongation, it seems to be more resistant against the fracture due to creep deformation. In this point of view, electron beam weld joint is far superior to TIG weld joint and nearly comparable to the base metal. (author)

Temperature dependence of the beam-foil interaction

International Nuclear Information System (INIS)

Gay, T.J.; Berry, H.G.

1978-01-01

The beam energy dependence between 50 and 200 keV of the linear polarization fraction (M/I) of the 2s 1 S--3p 1 P, 5016 A transition in He I on temperature was measured. The thin carbon exciter foils were heated externally by nichrome resistance elements. The measurements of Hight et al. are duplicated; the energy and current dependences are the same for corresponding between beam heating and external heating. It was also observed that γ, the number of slow secondary electrons produced per incident ion, decreases with increasing foil temperature. These two effects, in conjunction, offer a plausible explanation for the variation of polarization with beam current density. 5 figures

Electron beam spectrum monitor using synchrotron light

International Nuclear Information System (INIS)

Reagan, D.; Hostetler, T.E.

1979-03-01

This instrument shows the positions, widths, and shapes of momentum spectra of SLAC beams. It uses synchrotron light produced when the beam is deflected by a magnet. Some of the light is focused on the face of an image splitter consisting of acrylic light pipes. The light pipes illuminate twelve photomultiplier tubes. Pulses from the PM tubes are integrated, multiplexed, and displayed on an oscilloscope. The resolution of the instrument is usually better than 0.2%. It has some advantages over the secondary emitter foil spectrum monitors (SEM's) currently in use at SLAC. It need never be put out of service to avoid disturbing the beam. It is as sensitive as the most sensitive SLAC SEM. (Its performance has been optimized for high-current beams; it can easily be made much more sensitive.) It provides information on a pulse-to-pulse basis and, with better cables, could indicate electron beam pulse shapes

Heavy neutron-deficient radioactive beams: fission studies and fragment distributions

Energy Technology Data Exchange (ETDEWEB)

Schmidt, K.H.; Benlliure, J.; Heinz, A.; Voss, B. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Boeckstiegel, C.; Grewe, A.; Steinhaeuser, S.; Clerc, H.G.; Jong, M. de; Junghans, A.R.; Mueller, J. [Technische Hochschule Darmstadt (Germany). Inst. fuer Kernphysik; Pfuetzner, M. [Warsaw Univ. (Poland). Inst. of Experimental Physics

1998-02-01

The secondary-beam facility of GSI Darmstadt was used to study the fission process of short-lived radioactive nuclei. Relativistic secondary projectiles were produced by fragmentation of a 1 A GeV {sup 238}U primary beam and identified in nuclear charge and mass number. Their production cross sections were determined, and the fission competition in the statistical deexcitation was deduced for long isotopical chains. New results on the enhancement of the nuclear level density in spherical and deformed nuclei due to collective rotational and vibrational excitations were obtained. Using these reaction products as secondary beams, the dipole giant resonance was excited by electromagnetic interactions in a secondary lead target, and fission from excitation energies around 11 MeV was induced. The fission fragments were identified in nuclear charge, and their velocity vectors were determined. Elemental yields and total kinetic energies have been determined for a number of neutron-deficient actinides and preactinides which were not accessible with conventional techniques. The characteristics of multimodal fission of nuclei around {sup 226}Th were systematically investigated and related to the influence of shell effects on the potential energy and on the level density between fission barrier and scission. A systematic view on the large number of elemental yields measured gave rise to a new interpretation of the enhanced production of even elements in nuclear fission and allowed for a new understanding of pair breaking in large-scale collective motion. (orig.)

Monte Carlo investigation of the low-dose envelope from scanned proton pencil beams

International Nuclear Information System (INIS)

Sawakuchi, Gabriel O; Titt, Uwe; Mirkovic, Dragan; Ciangaru, George; Zhu, X Ronald; Sahoo, Narayan; Gillin, Michael T; Mohan, Radhe

2010-01-01

Scanned proton pencil beams carry a low-dose envelope that extends several centimeters from the individual beam's central axis. Thus, the total delivered dose depends on the size of the target volume and the corresponding number and intensity of beams necessary to cover the target volume uniformly. This dependence must be considered in dose calculation algorithms used by treatment planning systems. In this work, we investigated the sources of particles contributing to the low-dose envelope using the Monte Carlo technique. We used a validated model of our institution's scanning beam line to determine the contributions to the low-dose envelope from secondary particles created in a water phantom and particles scattered in beam line components. Our results suggested that, for high-energy beams, secondary particles produced by nuclear interactions in the water phantom are the major contributors to the low-dose envelope. For low-energy beams, the low-dose envelope is dominated by particles undergoing multiple Coulomb scattering in the beam line components and water phantom. Clearly, in the latter situation, the low-dose envelope depends directly on beam line design features. Finally, we investigated the dosimetric consequences of the low-dose envelope. Our results showed that if not modeled properly the low-dose envelope may cause clinically relevant dose disturbance in the target volume. This work suggested that this low-dose envelope is beam line specific for low-energy beams, should be thoroughly experimentally characterized and validated during commissioning of the treatment planning system, and therefore is of great concern for accurate delivery of proton scanning beam doses.

Comparative test results of various beam loss monitors in preparation for LHC

OpenAIRE

Bosser, Jacques; Ferioli, G

1999-01-01

Beam loss detectors will play an important role in the protection of the superconducting LHC magnets. Different types of detectors have been tested in the SPS ring and secondary beam lines with a view to their possible use for this application. This paper describes the measurements made with: microcalorimeters at cryogenic temperatures, PIN diodes, ionisation chambers, scintillators, and ACEMs. Measurements made using proton beams showing their relative sensitivities, linearities in counting ...

On the absorbed dose determination method in high energy electrons beams

International Nuclear Information System (INIS)

Scarlat, F.; Scarisoreanu, A.; Oane, M.; Mitru, E.; Avadanei, C.

2008-01-01

The absorbed dose determination method in water for electron beams with energies in the range from 1 MeV to 50 MeV is presented herein. The dosimetry equipment for measurements is composed of an UNIDOS.PTW electrometer and different ionization chambers calibrated in air kerma in a Co 60 beam. Starting from the code of practice for high energy electron beams, this paper describes the method adopted by the secondary standard dosimetry laboratory (SSDL) in NILPRP - Bucharest

The TMX heavy ion beam probe

International Nuclear Information System (INIS)

Hallock, G.A.

1994-01-01

A heavy ion beam probe has been used to measure the radial space potential distribution in the central cell of TMX. This was the first beam probe system to utilize computer control, CAMAC instrumentation, and fast time response for broadband fluctuation capabilities. The fast time response was obtained using off-line processing of the energy analyzer detector signals and wideband transimpedance amplifiers. The on-axis space potential was found to be 300--400 V, with φ e /T ec ∼8. The radial potential profile is parabolic when gas box fueling is used. The frequency of observed fluctuations was found to agree with the E x B plasma rotation frequency during the discharge. The measured Tl ++ secondary ion current level is consistent with calculations, given reasonable assumptions for beam attenuation

Wire Scanner Beam Profile Measurements for the LANSCE Facility

International Nuclear Information System (INIS)

Gilpatrick, John D.; Gruchalla, Michael E.; Martinez, Derwin; Pillai, Chandra; Rodriguez Esparza, Sergio; Sedillo, James Daniel; Smith, Brian G.

2012-01-01

The Los Alamos Neutron Science Center (LANSCE) is replacing beam profile measurement systems, commonly known as Wire Scanners (WS). Using the principal of secondary electron emission, the WS measurement system moves a wire or fiber across an impinging particle beam, sampling a projected transverse-beam distribution. Because existing WS actuators and electronic components are either no longer manufactured or home-built with antiquated parts, a new WS beam profile measurement is being designed, fabricated, and tested. The goals for these new WS's include using off-the-shelf components while eliminating antiquated components, providing quick operation while allowing for easy maintainability, and tolerating external radioactivation. The WS measurement system consists of beam line actuators, a cable plant, an electronics processor chassis, and software located both in the electronics chassis (National Instruments LabVIEW) and in the Central Control Room (EPICS-based client software). This WS measurement system will measure Hand H + LANSCE-facility beams and will also measure less common beams. This paper describes these WS measurement systems.

Application of electron-beam ionized discharges to switches - a comparison of experiment with theory

International Nuclear Information System (INIS)

Hallada, M.R.; Bailey, W.F.; Bletzinger, P.

1982-01-01

A theoretical investigation of high-pressure discharges ionized by an external electron beam (e-beam) was conducted. Only when secondary emission from the cathode and electron-impact ionization of metastable states were included in the analysis did calculated current-voltage (I-V) characteristics for argon and methane discharges compare well with experimental data. The I-V characteristics obtained reveal a sharp rise in the current at a certain threshold voltage. This threshold voltage and the entire I-V characteristic are shifted to lower voltages when metastable ionization is significant. Below the threshold voltage and at low external ionization source strengths, a region of negative differential conductivity is obtained. In the high-current region, the I-V slope is controlled by the secondary emission coefficient. The additional cathode sheath ionization from secondary emission and ionization from metastable states significantly reduces the discharge voltage. This important effect can be used to reduce e-beam switch losses and increase lifetime through judicious gas mixture selection and proper cathode conditioning

Directional Secondary Emission of a Semiconductor Microcavity

DEFF Research Database (Denmark)

Langbein, Wolfgang; Jensen, Jacob Riis; Hvam, Jørn Märcher

2000-01-01

We investigate the time-resolved secondary emission of a homogeneously broadened microcavity after resonant excitation. The sample consists of a 25nm GaAs single quantum well (QW) in the center of a wedged ¥ë cavity with AlAs/AlGaAs Bragg reflectors, grown by molecular beam epitaxy. At zero detun...

CATS, a low pressure multiwire proportional chamber for secondary beam tracking at GANIL

CERN Document Server

Ottini-Hustache, S; Auger, F; Musumarra, A; Alamanos, N; Cahan, B; Gillibert, A; Lagoyannis, A; Maillard, O; Pollacco, E; Sida, J L; Riallot, M

1999-01-01

A beam detector system, CATS (Chambre A Trajectoires de Saclay), was designed to provide event-by-event particle tracking in experiments with radioactive beams at GANIL. It consists of two low pressure multiwire proportional chambers with one plane of anode wires placed between two cathode planes (active area: 70x70 mm sup 2), respectively segmented into 28 vertical or horizontal strips (2.54 mm wide). The anode wires deliver a time signal allowing a time of flight measurement with an accuracy between 440 ps and 1.2 ns, depending on the energy loss of incident particles in the detector. The cathode strips are individually read out and the position of incoming particles is reconstructed using a charge centroid finding algorithm. A spatial resolution of 400 mu m (700 mu m) was achieved during in beam experiment, with a counting rate of 1.5x10 sup 5 (10 sup 6) particles per second. (author)

On the spectrum of the secondary auroral electrons

International Nuclear Information System (INIS)

Fung, S.F.; Hoffman, R.A.

1988-01-01

We present the results from a statistical study of the spectral characteristics of the (power law portion) secondary electrons associated with inverted-V electron precipitation events. A total of 106 inverted-V events observed at low altitudes ( - /sup γ/ with an averaged γ = 1.85. This spectral parameter is relatively insensitive to the variation of locations of the inverted-V events, but it depends on the primary beam parameters. We compare our results with the predictions and assess the applicabilities of the current theories on the generation of the low-energy auroral power law secondary electrons. Our analysis shows that collisional processes are the dominant source of the secondary electrons. copyright American Geophysical Union 1988

Controlled Roof Collapse during Secondary Mining in Coal Mines

Directory of Open Access Journals (Sweden)

Ashleigh Hutchinson

2012-01-01

Full Text Available The problem considered is an investigation of the possible collapse of the roof between the pillar next to be mined in secondary coal mining and the first line of pillar remnants called snooks. The roof rock between the pillar, which is the working face, and the snook is modelled as an Euler-Bernoulli beam acted on at each end by a horizontal force and by its weight per unit length. The beam is clamped at the pillar and simply supported (hinged at the snook. The dimensionless differential equation for the beam and the boundary conditions depend on one dimensionless number . We consider the range of values of before the displacement and curvature first become singular at =1. The model predicts that for all practical purposes, the beam will break at the clamped end at the pillar. The failure of the beam for values of greater than 1 is investigated computationally.

Secondary Electron Emission Yields from PEP-II Accelerator Materials

International Nuclear Information System (INIS)

Kirby, Robert E.

2000-01-01

The PEP-II B-Factory at SLAC operates with aluminum alloy and copper vacuum chambers, having design positron and electron beam currents of 2 and 1 A, respectively. Titanium nitride coating of the aluminum vacuum chamber in the arcs of the positron ring is needed in order to reduce undesirable electron-cloud effects. The total secondary electron emission yield of TiN-coated aluminum alloy has been measured after samples of beam chamber material were exposed to air and again after electron-beam bombardment, as a function of incident electron beam angle and energy. The results may be used to simulate and better understand electron-cloud effects under actual operating conditions. We also present yield measurements for other accelerator materials because new surface effects are expected to arise as beam currents increase. Copper, in particular, is growing in popularity for its good thermal conductivity and self-radiation-shielding properties. The effect of electron bombardment, ''conditioning'', on the yield of TiN and copper is shown

Measurements of the Secondary Electron Emission of Some Insulators

CERN Document Server

Bozhko, Y.; Hilleret, N.

2013-01-01

Charging up the surface of an insulator after beam impact can lead either to reverse sign of field between the surface and collector of electrons for case of thick sample or appearance of very high internal field for thin films. Both situations discard correct measurements of secondary electron emission (SEE) and can be avoided via reducing the beam dose. The single pulse method with pulse duration of order of tens microseconds has been used. The beam pulsing was carried out by means of an analog switch introduced in deflection plate circuit which toggles its output between "beam on" and "beam off" voltages depending on level of a digital pulse. The error in measuring the beam current for insulators with high value of SEE was significantly reduced due to the use for this purpose a titanium sample having low value of the SEE with DC method applied. Results obtained for some not coated insulators show considerable increase of the SEE after baking out at 3500C what could be explained by the change of work functi...

Joint random beam and spectrum selection for spectrum sharing systems with partial channel state information

KAUST Repository

Abdallah, Mohamed M.

2013-11-01

In this work, we develop joint interference-aware random beam and spectrum selection scheme that provide enhanced performance for the secondary network under the condition that the interference observed at the primary receiver is below a predetermined acceptable value. We consider a secondary link composed of a transmitter equipped with multiple antennas and a single-antenna receiver sharing the same spectrum with a set of primary links composed of a single-antenna transmitter and a single-antenna receiver. The proposed schemes jointly select a beam, among a set of power-optimized random beams, as well as the primary spectrum that maximizes the signal-to-interference-plus-noise ratio (SINR) of the secondary link while satisfying the primary interference constraint. In particular, we consider the case where the interference level is described by a q-bit description of its magnitude, whereby we propose a technique to find the optimal quantizer thresholds in a mean square error (MSE) sense. © 2013 IEEE.

Joint random beam and spectrum selection for spectrum sharing systems with partial channel state information

KAUST Repository

Abdallah, Mohamed M.; Sayed, Mostafa M.; Alouini, Mohamed-Slim; Qaraqe, Khalid A.

2013-01-01

In this work, we develop joint interference-aware random beam and spectrum selection scheme that provide enhanced performance for the secondary network under the condition that the interference observed at the primary receiver is below a predetermined acceptable value. We consider a secondary link composed of a transmitter equipped with multiple antennas and a single-antenna receiver sharing the same spectrum with a set of primary links composed of a single-antenna transmitter and a single-antenna receiver. The proposed schemes jointly select a beam, among a set of power-optimized random beams, as well as the primary spectrum that maximizes the signal-to-interference-plus-noise ratio (SINR) of the secondary link while satisfying the primary interference constraint. In particular, we consider the case where the interference level is described by a q-bit description of its magnitude, whereby we propose a technique to find the optimal quantizer thresholds in a mean square error (MSE) sense. © 2013 IEEE.

Large Reactional Osteogenesis in Maxillary Sinus Associated with Secondary Root Canal Infection Detected Using Cone-beam Computed Tomography.

Science.gov (United States)

Estrela, Carlos; Porto, Olavo César Lyra; Costa, Nádia Lago; Garrote, Marcel da Silva; Decurcio, Daniel Almeida; Bueno, Mike R; Silva, Brunno Santos de Freitas

2015-12-01

Inflammatory injuries in the maxillary sinus may originate from root canal infections and lead to bone resorption or regeneration. This report describes the radiographic findings of 4 asymptomatic clinical cases of large reactional osteogenesis in the maxillary sinus (MS) associated with secondary root canal infection detected using cone-beam computed tomographic (CBCT) imaging. Apical periodontitis, a consequence of root canal infection, may lead to a periosteal reaction in the MS and osteogenesis seen as a radiopaque structure on imaging scans. The use of a map-reading strategy for the longitudinal and sequential slices of CBCT images may contribute to the definition of diagnoses and treatment plans. Root canal infections may lead to reactional osteogenesis in the MS. High-resolution CBCT images may reveal changes that go unnoticed when using conventional imaging. Findings may help define initial diagnoses and therapeutic plans, but only histopathology provides a definitive diagnosis. Surgical enucleation of the periapical lesion is recommended if nonsurgical root canal treatment fails to control apical periodontitis. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Advances in Charge-Compensation in Secondary Ion Mass Spectrometry (SIMS)

Science.gov (United States)

Hervig, R. L.; Chen, J.; Schauer, S.; Stanley, B. D.; Moore, G. M.; Roggensack, K.

2012-12-01

In secondary ion mass spectrometry (SIMS), a sample is bombarded by a charged particle beam (the primary ion) and sputtered positive or negative secondary ions are analyzed in a mass spectrometer. When the target is not conducting (like many geological materials), sample charging can result in variable deflection of secondary ions away from the mass spectrometer and a low, unstable, or absent signal. Applying a thin conducting coat (e.g., C, Au) to polished samples is required, and if the primary ion beam is negatively-charged, the build-up of negative charge can be alleviated by secondary electrons draining to the conducting coat at the edge of the crater (if a positive potential is applied to the sample for the collection of positive secondary ions) or accelerated away from the crater (if a negative potential is applied for negative ion study). Unless the sputtered crater in the conducting coat becomes too large, sample charging can be kept at a controllable level, and high-quality trace element analyses and isotope ratios have been obtained using this technique over the past 3+ decades. When a positive primary beam is used, the resulting build-up of positive charge in the sample requires an electron gun to deliver sufficient negative charge to the sputtered crater. While there are many examples of successful analyses using this approach, the purpose of this presentation is to describe a very simple technique for aligning the electron gun on Cameca nf and 1270/80 SIMS instruments. This method allows reproducible analyses of insulating phases with a Cs+ primary beam and detection of negative secondary ions. Normally, the filament voltage on the E-gun is the same as the sample voltage; thus electrons do not strike the sample except when a positive charge has built up (e.g., in the analysis crater!). In this method, we decrease the sample voltage by 3 or more kV, so that the impact energy of the electrons is sufficient to induce a cathodoluminescent (CL) image on an

Plasma-parameter measurements using neutral-particle-beam attenuation

International Nuclear Information System (INIS)

Foote, J.H.; Molvik, A.W.; Turner, W.C.

1982-01-01

Intense and energetic neutral-particle-beam injection used for fueling or heating magnetically confined, controlled-fusion experimental plasmas can also provide diagnostic measurements of the plasmas. The attenuation of an atomic beam (mainly from charge-exchange and ionization interactions) when passing through a plasma gives the plasma line density. Orthogonal arrays of highly collimated detectors of the secondary-electron-emission type have been used in magnetic-mirror experiments to measure neutral-beam attenuation along chords through the plasma volume at different radial and axial positions. The radial array is used to infer the radial plasma-density profile; the axial array, to infer the axial plasma-density profile and the ion angular distribution at the plasma midplane

Beam Loss Patterns at the LHC Collimators Measurements & Simulations

CERN Document Server

Böhlen, Till Tobias

2008-01-01

The Beam Loss Monitoring (BLM) system of the Large Hadron Collider (LHC) detects particle losses of circulating beams and initiates an emergency extraction of the beam in case that the BLM thresholds are exceeded. This protection is required as energy deposition in the accelerator equipment due to secondary shower particles can reach critical levels; causing damage to the beam-line components and quenches of superconducting magnets. Robust and movable beam line elements, so-called collimators, are the aperture limitations of the LHC. Consequently, they are exposed to the excess of lost beam particles and their showers. Proton loss patterns at LHC collimators have to be determined to interpret the signal of the BLM detectors and to set adequate BLM thresholds for the protection of collimators and other equipment in case of unacceptably increased loss rates. The first part of this work investigates the agreement of BLM detector measurements with simulations for an LHC-like collimation setup. The setup consists ...

Assessment of organ dose reduction and secondary cancer risk associated with the use of proton beam therapy and intensity modulated radiation therapy in treatment of neuroblastomas

International Nuclear Information System (INIS)

Fuji, Hiroshi; Harada, Hideyuki; Asakura, Hirofumi; Nishimura, Tetsuo; Schneider, Uwe; Ishida, Yuji; Konno, Masahiro; Yamashita, Haruo; Kase, Yuki; Murayama, Shigeyuki; Onoe, Tsuyoshi; Ogawa, Hirofumi

2013-01-01

To compare proton beam therapy (PBT) and intensity-modulated radiation therapy (IMRT) with conformal radiation therapy (CRT) in terms of their organ doses and ability to cause secondary cancer in normal organs. Five patients (median age, 4 years; range, 2–11 years) who underwent PBT for retroperitoneal neuroblastoma were selected for treatment planning simulation. Four patients had stage 4 tumors and one had stage 2A tumor, according to the International Neuroblastoma Staging System. Two patients received 36 Gy, two received 21.6 Gy, and one received 41.4 Gy of radiation. The volume structures of these patients were used for simulations of CRT and IMRT treatment. Dose–volume analyses of liver, stomach, colon, small intestine, pancreas, and bone were performed for the simulations. Secondary cancer risks in these organs were calculated using the organ equivalent dose (OED) model, which took into account the rates of cell killing, repopulation, and the neutron dose from the treatment machine. In all evaluated organs, the mean dose in PBT was 20–80% of that in CRT. IMRT also showed lower mean doses than CRT for two organs (20% and 65%), but higher mean doses for the other four organs (110–120%). The risk of secondary cancer in PBT was 24–83% of that in CRT for five organs, but 121% of that in CRT for pancreas. The risk of secondary cancer in IMRT was equal to or higher than CRT for four organs (range 100–124%). Low radiation doses in normal organs are more frequently observed in PBT than in IMRT. Assessments of secondary cancer risk showed that PBT reduces the risk of secondary cancer in most organs, whereas IMRT is associated with a higher risk than CRT

Synthesis and investigation of superheavy elements - perspectives with radioactive beams

International Nuclear Information System (INIS)

Muenzenberg, G.

1997-09-01

The perspectives for the investigation of heavy and superheavy elements with intense beams of radioactive nuclei available from the new generation of secondary beam facilities in combination with modern experimental developments are the subject of this paper. The nuclear properties of the recently discovered shell nuclei centered at Z=108 and N=164 and predictions on the location of the superheavy region with improved theoretical models will be discussed. (orig.)

Secondary electron yields of carbon-coated and polished stainless steel

International Nuclear Information System (INIS)

Ruzic, D.; Moore, R.; Manos, D.; Cohen, S.

1982-01-01

To increase the power throughput to a plasma of an existing lower hybrid waveguide, secondary electron production on the walls and subsequent electron multiplication must be reduced. Since carbon has a low secondary electron coefficient (delta), measurements were performed for several UHV compatible carbon coatings (Aquadag/sup X/, vacuum pyrolyzed Glyptal/sup X/, and lamp black deposited by electrophoresis) as a function of primary beam voltage (35 eV to 10 keV), surface roughness (60 through 600 grit mechanical polishing and electropolishing), coating thickness, and angle of incidence (theta). Also measured were uncoated stainless steel, Mo, Cu, Ti, TiC, and ATJ graphite. The yields were obtained by varying the sample bias and measuring the collected current while the samples were in the electron beam of a scanning Auger microprobe. This technique allows delta measurements of Auger characterized surfaces with < or =0.3 mm spatial resolution. Results show delta to have a typical energy dependence, with a peak occurring at 200 to 300 eV for normal incidence, and at higher energy for larger theta. In general, delta increases with theta more for smooth surfaces than for rough ones. Ninety percent of the secondary electrons have energies less than 25 eV. Some carbonized coating and surface treatment combinations give delta/sub max/ = 0.88 +- 0.01 for normal electron beam incidence: a reduction of almost 40% compared to untreated stainless steel

Progress report on the neutral beam radiation hardening study

International Nuclear Information System (INIS)

Lee, J.D.; Condit, R.H.; Hoenig, C.L.; Wilcox, T.P.; Erickson, J.

1978-01-01

A neutral beam injector as presently conceived directly views the plasma it is sustaining. In turn the injector is exposed to the primary fusion neutrons plus secondary neutrons and gammas streaming back up the neutral beam duct. The intent of this work is to examine representative beam lines to see how performance and lifetimes could be affected by this radiation environment and to determine how unacceptable effects could be alleviated. Potential radiation induced problems addressed in this report have been limited to: (1) overheating of cryopanels and insulators, (2) gamma flux induced electrical conductivity increase of insulators, and (3) neutron and gamma fluence induced damage to insulator materials

Biomaterial imaging with MeV-energy heavy ion beams

Energy Technology Data Exchange (ETDEWEB)

Seki, Toshio, E-mail: seki@sakura.nucleng.kyoto-u.ac.jp [Department of Nuclear Engineering, Kyoto Univ., Uji, Kyoto 611-0011 (Japan); CREST, Japan Science and Technology Agency (JST), Chiyoda, Tokyo 102-0075 (Japan); Wakamatsu, Yoshinobu; Nakagawa, Shunichiro [Department of Nuclear Engineering, Kyoto Univ., Uji, Kyoto 611-0011 (Japan); Aoki, Takaaki [Department of Electronic Science and Engineering, Kyoto Univ., Nishikyo, Kyoto 615-8510 (Japan); CREST, Japan Science and Technology Agency (JST), Chiyoda, Tokyo 102-0075 (Japan); Ishihara, Akihiko [Laboratory of Cell Biology and Life Science, Graduate School of Human and Environmental Studies, Kyoto Univ., Sakyo, Kyoto 606-8501 (Japan); Matsuo, Jiro [Quantum Science and Engineering Center, Kyoto Univ., Uji, Kyoto 611-0011 (Japan); CREST, Japan Science and Technology Agency (JST), Chiyoda, Tokyo 102-0075 (Japan)

2014-08-01

The spatial distribution of several chemical compounds in biological tissues and cells can be obtained with mass spectrometry imaging (MSI). In conventional secondary ion mass spectrometry (SIMS) with keV-energy ion beams, elastic collisions occur between projectiles and atoms of constituent molecules. The collisions produce fragments, making the acquisition of molecular information difficult. In contrast, ion beams with MeV-energy excite near-surface electrons and enhance the ionization of high-mass molecules; hence, SIMS spectra of fragment-suppressed ionized molecules can be obtained with MeV-SIMS. To compare between MeV and conventional SIMS, we used the two methods based on MeV and Bi{sub 3}-keV ions, respectively, to obtain molecular images of rat cerebellum. Conventional SIMS images of m/z 184 were clearly observed, but with the Bi{sub 3} ion, the distribution of the molecule with m/z 772.5 could be observed with much difficulty. This effect was attributed to the low secondary ion yields and we could not get many signal counts with keV-energy beam. On the other hand, intact molecular ion distributions of lipids were clearly observed with MeV-SIMS, although the mass of all lipid molecules was higher than 500 Da. The peaks of intact molecular ions in MeV-SIMS spectra allowed us to assign the mass. The high secondary ion sensitivity with MeV-energy heavy ions is very useful in biomaterial analysis.

Biomaterial imaging with MeV-energy heavy ion beams

International Nuclear Information System (INIS)

Seki, Toshio; Wakamatsu, Yoshinobu; Nakagawa, Shunichiro; Aoki, Takaaki; Ishihara, Akihiko; Matsuo, Jiro

2014-01-01

The spatial distribution of several chemical compounds in biological tissues and cells can be obtained with mass spectrometry imaging (MSI). In conventional secondary ion mass spectrometry (SIMS) with keV-energy ion beams, elastic collisions occur between projectiles and atoms of constituent molecules. The collisions produce fragments, making the acquisition of molecular information difficult. In contrast, ion beams with MeV-energy excite near-surface electrons and enhance the ionization of high-mass molecules; hence, SIMS spectra of fragment-suppressed ionized molecules can be obtained with MeV-SIMS. To compare between MeV and conventional SIMS, we used the two methods based on MeV and Bi 3 -keV ions, respectively, to obtain molecular images of rat cerebellum. Conventional SIMS images of m/z 184 were clearly observed, but with the Bi 3 ion, the distribution of the molecule with m/z 772.5 could be observed with much difficulty. This effect was attributed to the low secondary ion yields and we could not get many signal counts with keV-energy beam. On the other hand, intact molecular ion distributions of lipids were clearly observed with MeV-SIMS, although the mass of all lipid molecules was higher than 500 Da. The peaks of intact molecular ions in MeV-SIMS spectra allowed us to assign the mass. The high secondary ion sensitivity with MeV-energy heavy ions is very useful in biomaterial analysis

Wire Scanner Beam Profile Measurements for the LANSCE Facility

Energy Technology Data Exchange (ETDEWEB)

Gilpatrick, John D. [Los Alamos National Laboratory; Gruchalla, Michael E. [Los Alamos National Laboratory; Martinez, Derwin [Los Alamos National Laboratory; Pillai, Chandra [Los Alamos National Laboratory; Rodriguez Esparza, Sergio [Los Alamos National Laboratory; Sedillo, James Daniel [Los Alamos National Laboratory; Smith, Brian G. [Los Alamos National Laboratory

2012-05-15

The Los Alamos Neutron Science Center (LANSCE) is replacing beam profile measurement systems, commonly known as Wire Scanners (WS). Using the principal of secondary electron emission, the WS measurement system moves a wire or fiber across an impinging particle beam, sampling a projected transverse-beam distribution. Because existing WS actuators and electronic components are either no longer manufactured or home-built with antiquated parts, a new WS beam profile measurement is being designed, fabricated, and tested. The goals for these new WS's include using off-the-shelf components while eliminating antiquated components, providing quick operation while allowing for easy maintainability, and tolerating external radioactivation. The WS measurement system consists of beam line actuators, a cable plant, an electronics processor chassis, and software located both in the electronics chassis (National Instruments LabVIEW) and in the Central Control Room (EPICS-based client software). This WS measurement system will measure Hand H{sup +} LANSCE-facility beams and will also measure less common beams. This paper describes these WS measurement systems.

Monte Carlo-based investigations on the impact of removing the flattening filter on beam quality specifiers for photon beam dosimetry.

Science.gov (United States)

Czarnecki, Damian; Poppe, Björn; Zink, Klemens

2017-06-01

The impact of removing the flattening filter in clinical electron accelerators on the relationship between dosimetric quantities such as beam quality specifiers and the mean photon and electron energies of the photon radiation field was investigated by Monte Carlo simulations. The purpose of this work was to determine the uncertainties when using the well-known beam quality specifiers or energy-based beam specifiers as predictors of dosimetric photon field properties when removing the flattening filter. Monte Carlo simulations applying eight different linear accelerator head models with and without flattening filter were performed in order to generate realistic radiation sources and calculate field properties such as restricted mass collision stopping power ratios (L¯/ρ)airwater, mean photon and secondary electron energies. To study the impact of removing the flattening filter on the beam quality correction factors k Q , this factor for detailed ionization chamber models was calculated by Monte Carlo simulations. Stopping power ratios (L¯/ρ)airwater and k Q values for different ionization chambers as a function of TPR1020 and %dd(10) x were calculated. Moreover, mean photon energies in air and at the point of measurement in water as well as mean secondary electron energies at the point of measurement were calculated. The results revealed that removing the flattening filter led to a change within 0.3% in the relationship between %dd(10) x and (L¯/ρ)airwater, whereby the relationship between TPR1020 and (L¯/ρ)airwater changed up to 0.8% for high energy photon beams. However, TPR1020 was a good predictor of (L¯/ρ)airwater for both types of linear accelerator with energies filter within 1.1% and 1.6% was observed for TPR1020 and %dd(10) x respectively. The results of this study have shown that removing the flattening filter led to a change in the relationship between the well-known beam quality specifiers and dosimetric quantities at the point of measurement

Beam-Beam Effects

International Nuclear Information System (INIS)

Herr, W; Pieloni, T

2014-01-01

One of the most severe limitations in high-intensity particle colliders is the beam-beam interaction, i.e. the perturbation of the beams as they cross the opposing beams. This introduction to beam-beam effects concentrates on a description of the phenomena that are present in modern colliding beam facilities

Ninth international conference on ion beam modification of materials. Book of abstracts

International Nuclear Information System (INIS)

1995-01-01

The conference focused on new developments and current status in the use of ion beams for modification of materials including: fundamental ion beam research and secondary effects of ion beams; materials modifications and techniques; biomedical and industrial applications; low energy processes; point defects and damage, nanocrystals in insulators, plasma immersion ion implantation, molecular dynamics simulations of ion-surface interactions, ion-beam mixing of insulators, GeV ion irradiation, electro-optical materials, polymers, tribological materials, and semiconductor processing. The handbook contains the workshop's program, abstracts and an author index. Separate abstracts were prepared for all papers in this volume

Ninth international conference on ion beam modification of materials. Book of abstracts

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-12-31

The conference focused on new developments and current status in the use of ion beams for modification of materials including: fundamental ion beam research and secondary effects of ion beams; materials modifications and techniques; biomedical and industrial applications; low energy processes; point defects and damage, nanocrystals in insulators, plasma immersion ion implantation, molecular dynamics simulations of ion-surface interactions, ion-beam mixing of insulators, GeV ion irradiation, electro-optical materials, polymers, tribological materials, and semiconductor processing. The handbook contains the workshop`s program, abstracts and an author index. Separate abstracts were prepared for all papers in this volume.

Tertiary particle production and target optimization of the H2 beam line in the SPS North Area

CERN Document Server

AUTHOR|(CDS)2079540; Tellander, Felix; CERN. Geneva. ATS Department

2016-01-01

In this note, the tertiary particle yield from secondary targets of different materials placed at the ‘filter’ position of the H2 beam line of SPS North Area are presented. The production is studied for secondary beams of different momenta in the range of 50-250 GeV/c. More specifically, we studied six different targets: two copper cylinders with a radius of 40 mm and lengths of 100 and 300 mm, one solid tungsten cylinder with a radius of 40 mm and a length of 150 mm and three polyethylene cylinders with radius of 40 mm and lengths of 550, 700 and 1000 mm. Eight different momenta of the secondary beam (50, 60, 70, 100, 120, 150, 200 and 250 GeV/c) as well as two different physics lists (QGSP_BIC and FTFP_BERT) have been extensively studied. The purpose of this study is (a) to optimize (using the appropriate filter target) the particle production from the secondary targets as demanded by the experiments (b) investigate the proton production (with respect to the pion production) in the produced tertiary bea...

A superconducting radio-frequency cavity for manipulating the phase space of pion beams at LAMPF

Energy Technology Data Exchange (ETDEWEB)

O' Donnell, J.M.; Davis, J.; DeHaven, R.A.; Gray, E.; Johnson, R.; Lomax, R.E.; McCloud, B.J.; McGill, J.A.; Morris, C.L.; Novak, J.; Rusnak, B.; Tubb, G. (Los Alamos National Lab., Los Alamos, NM (United States)); Applegate, J.M.; Averett, T.D.; Beck, J.; Ritchie, B.G. (Arizona State Univ., Tempe, AZ (United States)); Haebel, E. (CERN, Geneva (Switzerland)); Kiehlmann, D.; Klein, U.; Peniger, M.; Schaefer, P.; Vogel, H. (Siemens AG, Accelerator and Magnet Technology, Bergisch Gladbach (Germany)); Ward, H.; Moore, C.F. (Univ. of Texas, Austin, TX (United States))

1992-07-15

The SCRUNCHER is a superconducting radio-frequency cavity for manipulating the longitudinal phase space of the secondary pion beam from the low energy pion channel at LAMPF. Test results of the cavity performance and initial results from in-beam tests are presented. (orig.).

A superconducting radio-frequency cavity for manipulating the phase space of pion beams at LAMPF

Science.gov (United States)

O'Donnell, J. M.; Davis, J.; DeHaven, R. A.; Gray, E.; Johnson, R.; Lomax, R. E.; McCloud, B. J.; McGill, J. A.; Morris, C. L.; Novak, J.; Rusnak, B.; Tubb, G.; Applegate, J. M.; Averett, T. D.; Beck, J.; Ritchie, B. G.; Haebel, E.; Kiehlmann, D.; Klein, U.; Peiniger, M.; Schäfer, P.; Vogel, H.; Ward, H.; Fred Moore, C.

1992-07-01

The SCRUNCHER is a superconducting radio-frequency cavity for manipulating the longitudinal phase space of the secondary pion beam from the low energy pion channel at LAMPF. Test results of the cavity performance and initial results from in-beam tests are presented.

Crystal Collimation with Lead Ion Beams at Injection Energy in the LHC

CERN Document Server

Rossi, Roberto; Andreassen, Arvid; Butcher, Mark; Dionisio Barreto, Cristovao Andre; Masi, Alessandro; Mirarchi, Daniele; Montesano, Simone; Lamas Garcia, Inigo; Redaelli, Stefano; Scandale, Walter; Serrano Galvez, Pablo; Rijllart, Adriaan; Valentino, Gianluca; Galluccio, Francesca; CERN. Geneva. ATS Department

2015-01-01

During this MD, performed on December 2nd 2015, bent silicon crystals were tested with ion beams for a possible usage of crystal-assisted collimation. Tests were performed at injection energy, using both horizontal and vertical crystals. Ion channeling was observed for the first time with LHC beams at the record energy of 450 GeV and the channeled beams were probed with scans performed with secondary collimators. Measurements of cleaning efficiency of a crystal-based collimation system were also performed.

Event displays from Beam 2 in ATLAS, November 20th, 2009

CERN Multimedia

ATLAS collaboration

2009-01-01

ATLAS event displays and related information from the LHC restart in 2009. We recorded today, Friday November 20th, the first so-called "Beam Splash" events. For these events the beam in one arm of the LHC was dumped onto closed collimators located 140 meters upstream and downstream of ATLAS. The collision leads to a large number of detectable secondary particles longitudinally traversing the detect

Event displays from Beam Halo in ATLAS, November 20th, 2009

CERN Multimedia

ATLAS collaboration

2009-01-01

ATLAS event displays and related information from the LHC restart in 2009. We recorded today, Friday November 20th, the first so-called "Beam Splash" events. For these events the beam in one arm of the LHC was dumped onto closed collimators located 140 meters upstream and downstream of ATLAS. The collision leads to a large number of detectable secondary particles longitudinally traversing the detect

Event displays from Beam 01 in ATLAS, November 20th, 2009

CERN Multimedia

atlas collaboration

2009-01-01

ATLAS event displays and related information from the LHC restart in 2009. We recorded on, Friday November 20th, the first so-called "Beam Splash" events. For these events the beam in one arm of the LHC was dumped onto closed collimators located 140 meters upstream and downstream of ATLAS. The collision leads to a large number of detectable secondary particles longitudinally traversing the detector

High resolution, position sensitive detector for energetic particle beams

International Nuclear Information System (INIS)

Marsh, E.P.; Strathman, M.D.; Reed, D.A.; Odom, R.W.; Morse, D.H.; Pontau, A.E.

1993-01-01

The performance and design of an imaging position sensitive, particle beam detector will be presented. The detector is minimally invasive, operates a wide dynamic range (>10 10 ), and exhibits high spatial resolution. The secondary electrons produced when a particle beam passes through a thin foil are imaged using stigmatic ion optics onto a two-dimensional imaging detector. Due to the low scattering cross section of the 6 nm carbon foil the detector is a minimal perturbation on the primary beam. A prototype detector with an image resolution of approximately 5 μm for a field of view of 1 mm has been reported. A higher resolution detector for imaging small beams (<50 μm) with an image resolution of better than 0.5 μm has since been developed and its design is presented. (orig.)

Transport channel of secondary ion beam of experimental setup for selective laser ionization with gas cell GALS

Science.gov (United States)

Gulbekyan, G. G.; Zemlyanoy, S. G.; Bashevoy, V. V.; Ivanenko, I. A.; Kazarinov, N. Yu; Kazacha, V. I.; Osipov, N. F.

2017-07-01

GALS is the experimental setup intended for production and research of isobaric and isotopically pure heavy neutron-rich nuclei. The beam line consists of two parts. The initial part is used for transport of the primary 136Xe ion beam with the energy of 4.5-9.0 MeV/amu from the FLNR cyclotron U-400M to the Pb target for production of the studying ion beams. These beams have the following design parameters: the charge Z = +1, the mass A = 180-270 and the kinetic energy W = 40 keV. The second part placed after the target consists of the SPIG (QPIG) system, the accelerating gap, the electrostatic Einzel lens, 90-degree spectrometric magnet (calculated value of the mass-resolution is equal to 1400) and the beam line for the transportation of the ions from the magnet focal plane to a particle detector. The results of simulation of the particle dynamics and the basic parameters of all elements of the beam line are presented.

Carbon filament beam profile monitor for high energy proton-antiproton storage rings

International Nuclear Information System (INIS)

Evans, L.R.; Shafer, R.E.

1979-01-01

The measurement of the evolution of the transverse profile of the stored beams in high energy proton storage rings such as the p-anti p colliders at CERN and at FNAL is of considerable importance. In the present note, a simple monitor is discussed which will allow almost non-destructive measurement of the profile of each individual proton and antiproton bunch separately. It is based on the flying wire technique first used at CEA and more recently at the CPS. A fine carbon filament is passed quickly through the beam, acting as a target for secondary particle production. The flux of secondary particles is measured by two scintillator telescopes, one for protons and one for antiprotons, having an angular acceptance between 30 and 100 mrad. Measurements of secondary particle production performed at FNAL in this angular range show that a very respectable flux can be expected

Characteristics of Sissi primary beam

International Nuclear Information System (INIS)

Nghiem, P.; Payet, J.; Tkatchenko, A.

1994-01-01

This study concerns the definition of the Sissi primary beam characteristics. The calculations have been carried out in two steps : -a study of primary and secondary order with the help of BETA matrix code -a study of superior orders with the help of ZGOUBI code which is able to take into consideration the measured fields and in which the movement equations are integrated numerically. (O.L.). 9 figs., 3 tabs

A new online secondary path modeling method for adaptive active structure vibration control

International Nuclear Information System (INIS)

Pu, Yuxue; Zhang, Fang; Jiang, Jinhui

2014-01-01

This paper proposes a new variable step size FXLMS algorithm with an auxiliary noise power scheduling strategy for online secondary path modeling. The step size for the secondary path modeling filter and the gain of auxiliary noise are varied in accordance with the parameters available directly. The proposed method has a low computational complexity. Computer simulations show that an active vibration control system with the proposed method gives much better vibration attenuation and modeling accuracy at a faster convergence rate than existing methods. National Instruments’ CompactRIO is used as an embedded processor to control simply supported beam vibration. Experimental results indicate that the vibration of the beam has been effectively attenuated. (papers)

Heavy ion beam probe development for the plasma potential measurement on the TUMAN-3M tokamak

International Nuclear Information System (INIS)

Askinazi, L.G.; Kornev, V.A.; Lebedev, S.V.; Tukachinsky, A.S.; Zhubr, N.A.; Dreval, N.B.; Krupnik, L.I.

2004-01-01

The peculiarities of the heavy ion beam probe implementation on the small aspect ratio tokamak TUMAN-3M are analyzed. The toroidal displacement of beam trajectory due to the high I pl /B tor ratio is taken into account when designing the layout of the diagnostic. Numerical calculation of beam trajectories using realistic configuration of TUMAN-3M magnetic fields and parabolic plasma current profile resulted in proper adjustment of probing and detection parameters (probing ion material, energy, entrance angles, detector location, and orientation). Secondary ion energy analyzer gain functions G and F were measured in situ using neutral hydrogen puffed in the tokamak vessel as a target for secondary ions production. The detector unit featured split-plate design and had additional electrodes for secondary electron emission suppression. As a result, the diagnostic is now capable of plasma potential evolution measurement and is sensitive enough to trace the potential profile evolution at the L-H mode transition

A self-calibrating ionisation chamber for the precise intensity calibration of high-energy heavy-ion beam monitors

International Nuclear Information System (INIS)

Junghans, A.

1996-01-01

The intensity of a 136 Xe(600 A MeV) beam has been determined by simultaneously measuring the particle rate and the corresponding ionisation current with an ionisation chamber. The ionisation current of this self-calibrating device was compared at higher intensities with the current of a secondary-electron monitor and a calibration of the secondary-electron current was achieved with a precision of 2%. This method can be applied to all high-energy heavy-ion beams. (orig.)

Crystals channel high-energy beams in the LHC

CERN Multimedia

CERN Bulletin

2015-01-01

Bent crystals can be used to deflect particle beams, as suggested by E. Tsyganov in 1976. Experimental demonstrations have been carried out for four decades in various laboratories worldwide. In recent tests, a bent crystal inserted into the LHC beam halo successfully channelled and deflected 6.5 TeV protons into an absorber, with reduced secondary irradiation.    Quasimosaic crystal for the LHC (developed by PNPI). Bent crystal technology was introduced at CERN and further developed for the LHC by the UA9 Collaboration. For about ten years, experts from CERN, INFN (Italy), Imperial College (UK), LAL (France), and PNPI, IHEP and JINR (Russia) have been investigating the advantages of using bent crystals in the collimation systems of high-energy hadron colliders. A bent crystal replacing the primary collimator can deflect the incoming halo deeply inside the secondary collimators, improving their absorption efficiency. “The bent crystals we have just tested at the world-record en...

Ionisation Chambers for the LHC Beam Loss Detection

CERN Document Server

Gschwendtner, E; Dehning, B; Ferioli, G; Kain, V

2003-01-01

At the Large Hadron Collider (LHC) a beam loss system will be used to prevent and protect superconducting magnets against coil quenches and coil damages. Since the stored particle beam intensity is 8 orders of magnitude larger than the lowest quench level value particular attention is paid to the design of the secondary particle shower detectors. The foreseen ionisation chambers are optimised in geometry simulating the probable loss distribution along the magnets and convoluting the loss distribution with the secondary particle shower distributions. To reach the appropriate coverage of a particle loss and to determine the quench levels with a relative accuracy of 2 the number of the detectors and their lengths is weighted against the particle intensity density variation. In addition attention is paid to the electrical ionisation chamber signal to minimise the ion tail extension. This optimisation is based on time resolved test measurements in the PS booster. A proposal for a new ionisation chamber will be pre...

Importance of beam-beam tune spread to collective beam-beam instability in hadron colliders

International Nuclear Information System (INIS)

Jin Lihui; Shi Jicong

2004-01-01

In hadron colliders, electron-beam compensation of beam-beam tune spread has been explored for a reduction of beam-beam effects. In this paper, effects of the tune-spread compensation on beam-beam instabilities were studied with a self-consistent beam-beam simulation in model lattices of Tevatron and Large Hodron Collider. It was found that the reduction of the tune spread with the electron-beam compensation could induce a coherent beam-beam instability. The merit of the compensation with different degrees of tune-spread reduction was evaluated based on beam-size growth. When two beams have a same betatron tune, the compensation could do more harm than good to the beams when only beam-beam effects are considered. If a tune split between two beams is large enough, the compensation with a small reduction of the tune spread could benefit beams as Landau damping suppresses the coherent beam-beam instability. The result indicates that nonlinear (nonintegrable) beam-beam effects could dominate beam dynamics and a reduction of beam-beam tune spread by introducing additional beam-beam interactions and reducing Landau damping may not improve the stability of beams

DART: A simulation code for charged particle beams

International Nuclear Information System (INIS)

White, R.C.; Barr, W.L.; Moir, R.W.

1989-01-01

This paper presents a recently modified version of the 2-D code, DART, which can simulate the behavior of a beam of charged particles whose trajectories are determined by electric and magnetic fields. This code was originally used to design laboratory-scale and full-scale beam direct converters. Since then, its utility has been expanded to allow more general applications. The simulation includes space charge, secondary electrons, and the ionization of neutral gas. A beam can contain up to nine superimposed beamlets of different energy and species. The calculation of energy conversion efficiency and the method of specifying the electrode geometry are described. Basic procedures for using the code are given, and sample input and output fields are shown. 7 refs., 18 figs

Preliminary design of electrostatic sensors for MITICA beam line components

Energy Technology Data Exchange (ETDEWEB)

Spagnolo, S., E-mail: spagnolo@igi.cnr.it; Spolaore, M.; Dalla Palma, M.; Pasqualotto, R.; Sartori, E.; Serianni, G.; Veltri, P. [Consorzio RFX, Associazione EURATOM-ENEA sulla Fusione, 35127 Padova (Italy)

2016-02-15

Megavolt ITER Injector and Concept Advancement, the full-scale prototype of ITER neutral beam injector, is under construction in Italy. The device will generate deuterium negative ions, then accelerated and neutralized. The emerging beam, after removal of residual ions, will be dumped onto a calorimeter. The presence of plasma and its parameters will be monitored in the components of the beam-line, by means of specific electrostatic probes. Double probes, with the possibility to be configured as Langmuir probes and provide local ion density and electron temperature measurements, will be employed in the neutralizer and in the residual ion dump. Biased electrodes collecting secondary emission electrons will be installed in the calorimeter with the aim to provide a horizontal profile of the beam.

Production of hypernuclei in relativistic ion beams

International Nuclear Information System (INIS)

Bando, H.; Sano, M.; Wakai, M.; Zofka, J.

1988-05-01

The hypernuclear formation in collisions of relativistic beams of 4 He, 7 Li, 12 C and 19 F with target of 12 C is calculated at energies used in the recent Dubna experiment. The hyperfragments optimal for observation are pointed out and the secondary (π + K + ) formation is evaluated and found to be nonnegligible. (author)

Experiments on secondary ion emission with multicharged keV ion bombardement

International Nuclear Information System (INIS)

Della Negra, S.; Depauw, J.; Joret, H.; Le Beyec, Y.; Schweikert, E.A.

1987-01-01

An electron cyclotron resonance ion source was used to study the influence of the incident charge state of keV ions on secondary ion emission. The experiments were run with 18 keV Arn+ (1 < n < 11) beams produced by a minimafios source. Various types of targets were bombarded by the ion beam and the sputtered ionized species were identified by time of flight mass spectrometry. The experimental arrangement is detailed and preliminary results are indicated

The influence of secondary reconstruction slice thickness on NewTom 3G cone beam computed tomography-based radiological interpretation of sheep mandibular condyle fractures.

Science.gov (United States)

Sirin, Yigit; Guven, Koray; Horasan, Sinan; Sencan, Sabri; Bakir, Baris; Barut, Oya; Tanyel, Cem; Aral, Ali; Firat, Deniz

2010-11-01

The objective of this study was to examine the diagnostic accuracy of the different secondary reconstruction slice thicknesses of cone beam computed tomography (CBCT) on artificially created mandibular condyle fractures. A total of 63 sheep heads with or without condylar fractures were scanned with a NewTom 3G CBCT scanner. Multiplanar reformatted (MPR) views in 0.2-mm, 1-mm, 2-mm, and 3-mm secondary reconstruction slice thicknesses were evaluated by 7 observers. Inter- and intraobserver agreements were calculated with weighted kappa statistics. The receiver operating characteristic (ROC) curve analysis was used to statistically compare the area under the curve (AUC) of each slice thickness. The kappa coefficients varied from fair and to excellent. The AUCs of 0.2-mm and 1-mm slice thicknesses were found to be significantly higher than those of 2 mm and 3 mm for some type of fractures. CBCT was found to be accurate in detecting all variants of fractures at 0.2 mm and 1 mm. However, 2-mm and 3-mm slices were not suitable to detect fissure, complete, and comminuted types of mandibular condyle fractures. Copyright © 2010 Mosby, Inc. All rights reserved.

The Beam Loss Detection System of the LHC Ring

CERN Document Server

Gschwendtner, E; Ferioli, G; Friesenbichler, W; Kain, V

2002-01-01

At the Large Hadron Collider (LHC) a beam loss system will be installed in the arc, dispersion suppressor and the straight regions for a continuous surveillance of particle losses. These beam particles deposit their energy partially in the super-conducting coils leading to temperature increase, possible magnet quenches and damages. The primary and secondary halo of the beam is absorbed by the collimation system. The tertiary halo will be lost at aperture limits in the ring. Its loss distribution along the magnets has been studies. At the positions, where most of the beam losses are expected, simulations of the particle fluences outside the cryostat and induced by lost protons at the aperture have been performed with the Monte Carlo Code Geant 3.2.1. This allows determining the most suitable positions of the detectors, the needed number of monitors and the impact on the dynamic range of the detectors. The design of the beam loss monitor system is presented that meet the required sensitivity, dynamic range and ...

A study for the installation of the TEXT heavy-ion beam probe on DIII-D

Science.gov (United States)

Edmonds, P. H.; Solano, E. R.; Bravenec, R. V.; Wootton, A. J.; Schoch, P. M.; Crowley, T. P.; Hickok, R. L.; West, W. P.; Leuer, J.; Anderson, P.

1997-01-01

An assessment of the feasibility of installing the TEXT 2 MeV heavy-ion beam probe on the DIII-D tokamak has been completed. Detailed drawings of the machine cross section were imported into the CAD application AutoCAD. A set of programs written in AutoLisp were used to generate trajectories. Displays of the accessible cross section of the plasma, scan lines for the entire range of primary beam energy and injection angle ranges, and sample-volume dimensions can be rapidly generated. Because of the large deflection between the primary input beam and the emergent secondary beam, either the analyzer needs to be tracked over a ±20° angle or secondary poloidal deflector plates need to be installed at the exit port. Toroidal deflector plates will be installed at both the injection and exit ports to compensate for toroidal displacements and deflections. The sample volumes generated by this procedure are within a few centimeters of the locations derived from a full three-dimensional calculation.

Equipment response spectra for base-isolated shear beam structures

International Nuclear Information System (INIS)

Ahmadi, G.; Su, L.

1992-01-01

Equipment response spectra in base-isolated structure under seismic ground excitations are studied. The equipment is treated as a single-degree-of-freedom system attached to a nonuniform elastic beam structural model. Several leading base isolation systems, including the laminated rubber bearing, the resilient-friction base isolator with and without a sliding upper plate, and the EDF system are considered. Deflection and acceleration response spectra for the equipment and the shear beam structure subject to a sinusoidal and the accelerogram of the N00W component of El Centro 1940 earthquake are evaluated. Primary-secondary interaction effects are included in the analysis. Several numerical parametric studies are carried out and the effectiveness of different base isolation systems in protecting the nonstructural components is studied. It is shown that use of properly designed base isolation systems provides considerable protection for secondary systems, as well as, the structure against severe seismic loadings. (orig.)

Interference-aware random beam selection schemes for spectrum sharing systems

KAUST Repository

Abdallah, Mohamed; Qaraqe, Khalid; Alouini, Mohamed-Slim

2012-01-01

users. In this work, we develop interference-aware random beam selection schemes that provide enhanced performance for the secondary network under the condition that the interference observed by the receivers of the primary network is below a

Beam, vacuum and walls, a 3-body interaction

International Nuclear Information System (INIS)

Arianer, J.

2002-11-01

The interactions between beams of accelerated particles, residual gas and walls involve complex physical processes. In most cases these interactions affect the quality of the vacuum and the value of the pressure. This course reviews all these interactions in a pedagogical and practical way that may be useful for any user of devices involving beams of particles. This document is made up of 6 chapters: 1) basic notions (Maxwell-Boltzmann distribution, kinematics of charged particles, collisions, excitation and ionization), 2) properties of beams (emittance, local effects, and synchrotron radiation), 3) interactions between residual gas and particle beams (Bremsstrahlung radiation, energy loss due to ionization, charge shift of ion beams, photo-absorption and photo-ionization, and slowing-down in a plasma), 4) surface properties (crystal structure, and interaction between surface and the residual gas), 5) interaction between the beam and walls (reflection and diffraction of electrons, secondary emission of electrons, desorption induced by electron and ion impacts, photon production, ion-wall interaction, sputtering, ion penetration, surface ionization and thermal-ionization), and 6) radiation-wall interaction (diffusion, damping, photo-electric effect, desorption induced by photons, pair production and laser-surface interaction). (A.C.)

High resolution, position sensitive detector for energetic particle beams

Energy Technology Data Exchange (ETDEWEB)

Marsh, E P [Charles Evans and Associates, Redwood City, CA (United States); Strathman, M D [Charles Evans and Associates, Redwood City, CA (United States); Reed, D A [Charles Evans and Associates, Redwood City, CA (United States); Odom, R W [Charles Evans and Associates, Redwood City, CA (United States); Morse, D H [Sandia National Labs., Livermore, CA (United States); Pontau, A E [Sandia National Labs., Livermore, CA (United States)

1993-05-01

The performance and design of an imaging position sensitive, particle beam detector will be presented. The detector is minimally invasive, operates a wide dynamic range (>10[sup 10]), and exhibits high spatial resolution. The secondary electrons produced when a particle beam passes through a thin foil are imaged using stigmatic ion optics onto a two-dimensional imaging detector. Due to the low scattering cross section of the 6 nm carbon foil the detector is a minimal perturbation on the primary beam. A prototype detector with an image resolution of approximately 5 [mu]m for a field of view of 1 mm has been reported. A higher resolution detector for imaging small beams (<50 [mu]m) with an image resolution of better than 0.5 [mu]m has since been developed and its design is presented. (orig.)

Production of light radioactive ion beams (RIB) using inverse kinematics

International Nuclear Information System (INIS)

Das, J.J.; Sugathan, P.; Madhavan, N.; Madhusudhana Rao, P.V.; Jhingan, A.; Varughese, T.; Barua, S.; Nath, S.; Sinha, A.K.; Kumar, B.; Zacharias, J.

2005-01-01

At Nuclear Science Centre (NSC), New Delhi, we have implemented a facility to produce low energy light radioactive ion beams (RIBs) using (p,n) type of reactions in inverse kinematics. For this purpose primary beams from the 15-UD Pelletron accelerator impinged on a thin polypropylene foil mounted on a rotating/linearly moving target assembly. For efficiently separating the secondary beam from primary beam, the existing recoil mass spectrometer (RMS) HIRA was operated with new ion optics. Suitable hardware modifications were also made. Using this facility, we have extracted a 7 Be beam of purity better than 99% and spot-size ∼4 mm in diameter. This 7 Be beam has been utilized in a variety of experiments in the energy range of 15-22 MeV. Typical beam parameters are: intensity 10 4 pps, angular spread ±30 mrad and energy spread ±0.5 MeV. Development of appropriate detector setup/target arrangement were also made to perform these experiments. In this paper, we describe the implementation of this project

Secondary emission detectors for fixed target experiments at Fermilab

International Nuclear Information System (INIS)

Drucker, R.; Ford, R.; Tassotto, G.

1998-02-01

A description of a Secondary Emission Electron Detector (SEED) is given. The SEEDs provide accurate profiles and positions at small wire spacing (125-500 mm) in a high energy, high rate environment that exceeds the capabilities of traditional segmented wire ion chambers (SWICs). This device has been designed and constructed to monitor beam position and profile of two fixed target beamlines, namely, KTeV (FNAL E-799, E-832) with an average beam sigma at target of 0.22 mm and NuTeV (FNAL E-815) with a sigma = 0.6 mm. KTeV took beam at an intensity of up to 5E12 800 GeV protons over a 20 sec spill and NuTeV received 1E13 800 GeV protons in five pings/spill

The ISOL exotic beam facility at LNS: the EXCYT project

International Nuclear Information System (INIS)

Ciavola, G.; Calabretta, L.; Cuttone, G.; Di Bartolo, G.; Finocchiaro, P.; Gammino, S.; Gu, M.; Migneco, E.; Raia, G.; Rifuggiato, D.; Rovelli, A.; Vinciguerra, D.; Qin, J.; Wollnik, H.

1997-01-01

The aim of the EXCYT project (exotics with cyclotron and tandem) is the development of a facility for producing and accelerating exotic beams from 0.2 up to 8 MeV/amu. EXCYT is based on the ''two accelerators'' method. A K=800 superconducting cyclotron, axially injected by the ECR ion source SERSE, will deliver the primary beam. Such a beam will produce the required nuclear species in a modified ISOLDE type target-source complex. When required, a 15 MV tandem Van der Graaff will accelerate the secondary beams. Both accelerators are existing and operational at Laboratorio Nazionale del Sud. Concerning the status of the project, progress has been made in most of the key issues of the project, like the construction of SERSE, cyclotron upgrading, modification of the existing building, high resolution mass separator, and diagnostic equipment for low energy, low intensity beams. (orig.)

The ISOL exotic beam facility at LNS: the EXCYT project

Energy Technology Data Exchange (ETDEWEB)

Ciavola, G.; Calabretta, L.; Cuttone, G.; Di Bartolo, G.; Finocchiaro, P.; Gammino, S.; Gu, M.; Migneco, E.; Raia, G.; Rifuggiato, D.; Rovelli, A.; Vinciguerra, D. [Istituto Nazionale di Fisica Nucleare, Catania (Italy); Qin, J. [Institute of Atomic Energy, Beijing (China); Wollnik, H. [Giessen Univ. (Germany)

1997-04-01

The aim of the EXCYT project (exotics with cyclotron and tandem) is the development of a facility for producing and accelerating exotic beams from 0.2 up to 8 MeV/amu. EXCYT is based on the ``two accelerators`` method. A K=800 superconducting cyclotron, axially injected by the ECR ion source SERSE, will deliver the primary beam. Such a beam will produce the required nuclear species in a modified ISOLDE type target-source complex. When required, a 15 MV tandem Van der Graaff will accelerate the secondary beams. Both accelerators are existing and operational at Laboratorio Nazionale del Sud. Concerning the status of the project, progress has been made in most of the key issues of the project, like the construction of SERSE, cyclotron upgrading, modification of the existing building, high resolution mass separator, and diagnostic equipment for low energy, low intensity beams. (orig.). 8 refs.

Fast pencil beam dose calculation for proton therapy using a double-Gaussian beam model

Directory of Open Access Journals (Sweden)

Joakim eda Silva

2015-12-01

Full Text Available The highly conformal dose distributions produced by scanned proton pencil beams are more sensitive to motion and anatomical changes than those produced by conventional radiotherapy. The ability to calculate the dose in real time as it is being delivered would enable, for example, online dose monitoring, and is therefore highly desirable. We have previously described an implementation of a pencil beam algorithm running on graphics processing units (GPUs intended specifically for online dose calculation. Here we present an extension to the dose calculation engine employing a double-Gaussian beam model to better account for the low-dose halo. To the best of our knowledge, it is the first such pencil beam algorithm for proton therapy running on a GPU. We employ two different parametrizations for the halo dose, one describing the distribution of secondary particles from nuclear interactions found in the literature and one relying on directly fitting the model to Monte Carlo simulations of pencil beams in water. Despite the large width of the halo contribution, we show how in either case the second Gaussian can be included whilst prolonging the calculation of the investigated plans by no more than 16%, or the calculation of the most time-consuming energy layers by about 25%. Further, the calculation time is relatively unaffected by the parametrization used, which suggests that these results should hold also for different systems. Finally, since the implementation is based on an algorithm employed by a commercial treatment planning system, it is expected that with adequate tuning, it should be able to reproduce the halo dose from a general beam line with sufficient accuracy.

DART: a simulation code for charged particle beams

International Nuclear Information System (INIS)

White, R.C.; Barr, W.L.; Moir, R.W.

1988-01-01

This paper presents a recently modified verion of the 2-D DART code designed to simulate the behavior of a beam of charged particles whose paths are affected by electric and magnetic fields. This code was originally used to design laboratory-scale and full-scale beam direct converters. Since then, its utility has been expanded to allow more general applications. The simulation technique includes space charge, secondary electron effects, and neutral gas ionization. Calculations of electrode placement and energy conversion efficiency are described. Basic operation procedures are given including sample input files and output. 7 refs., 18 figs

Plasma-Sheath Instability in Hall Thrusters Due to Periodic Modulation of the Energy of Secondary Electrons in Cyclotron Motion

International Nuclear Information System (INIS)

Sydorenko, D.; Smolyakov, A.; Kaganovich, I.; Raitses, Y.

2008-01-01

Particle-in-cell simulation of Hall thruster plasmas reveals a plasma-sheath instability manifesting itself as a rearrangement of the plasma sheath near the thruster channel walls accompanied by a sudden change of many discharge parameters. The instability develops when the sheath current as a function of the sheath voltage is in the negative conductivity regime. The major part of the sheath current is produced by beams of secondary electrons counter-streaming between the walls. The negative conductivity is the result of nonlinear dependence of beam-induced secondary electron emission on the plasma potential. The intensity of such emission is defined by the beam energy. The energy of the beam in crossed axial electric and radial magnetic fields is a quasi-periodical function of the phase of cyclotron rotation, which depends on the radial profile of the potential and the thruster channel width. There is a discrete set of stability intervals determined by the final phase of the cyclotron rotation of secondary electrons. As a result, a small variation of the thruster channel width may result in abrupt changes of plasma parameters if the plasma state jumps from one stability interval to another

Collimation Cleaning at the LHC with Advanced Secondary Collimator Materials

CERN Document Server

AUTHOR|(CDS)2085459; Bruce, Roderik; Mereghetti, Alessio; Redaelli, Stefano; Rossi, A

2015-01-01

The LHC collimation system must ensure efficient beam halo cleaning in all machine conditions. The first run in 2010-2013 showed that the LHC performance may be limited by collimator material-related concerns, such as the contribution from the present carbon-based secondary collimators to the machine impedance and, consequently, to the beam instability. Novel materials based on composites are currently under development for the next generation of LHC collimators to address these limitations. Particle tracking simulations of collimation efficiency were performed using the Sixtrack code and a material database updated to model these composites. In this paper, the simulation results will be presented with the aim of studying the effect of the advanced collimators on the LHC beam cleaning.

Coherent beam-beam effects

International Nuclear Information System (INIS)

Chao, A.W.

1992-01-01

There are two physical pictures that describe the beam-beam interaction in a storage ring collider: The weak-strong and the strong-strong pictures. Both pictures play a role in determining the beam-beam behavior. This review addresses only the strong-strong picture. The corresponding beam dynamical effects are referred to as the coherent beam-beam effects. Some basic knowledge of the weak-strong picture is assumed. To be specific, two beams of opposite charges are considered. (orig.)

An MCNP-based model of a medical linear accelerator x-ray photon beam.

Science.gov (United States)

Ajaj, F A; Ghassal, N M

2003-09-01

The major components in the x-ray photon beam path of the treatment head of the VARIAN Clinac 2300 EX medical linear accelerator were modeled and simulated using the Monte Carlo N-Particle radiation transport computer code (MCNP). Simulated components include x-ray target, primary conical collimator, x-ray beam flattening filter and secondary collimators. X-ray photon energy spectra and angular distributions were calculated using the model. The x-ray beam emerging from the secondary collimators were scored by considering the total x-ray spectra from the target as the source of x-rays at the target position. The depth dose distribution and dose profiles at different depths and field sizes have been calculated at a nominal operating potential of 6 MV and found to be within acceptable limits. It is concluded that accurate specification of the component dimensions, composition and nominal accelerating potential gives a good assessment of the x-ray energy spectra.

Space charge compensation on the low energy beam transport of Linac4

CERN Document Server

AUTHOR|(SzGeCERN)733270; Scrivens, Richard; Jesus Castillo, Santos

Part of the upgrade program in the injector chains of the CERN accelerator complex is the replacement of the the proton accelerator Linac2 for the brand new Linac4 which will accelerate H$^-$ and its main goal is to increase the beam intensity in the next sections of the LHC accelerator chain. The Linac4 is now under commissioning and will use several ion sources to produce high intensity unbunched H$^-$ beams with different properties, and the low energy beam transport (LEBT) is the system in charge of match all these different beams to the Radio frequency quadrupole (RFQ). The space charge forces that spread the beam ions apart of each other and cause emittance growth limits the maximum intensity that can be transported in the LEBT, but the space charge of intense unbunched ion beams can be compensated by the generated ions by the impact ionization of the residual gas, which creates a source of secondary particles inside the beam pipe. For negative ion beams, the effect of the beam electric field is to ex...

A high resolution wire scanner beam profile monitor with a microprocessor data acquisition system

International Nuclear Information System (INIS)

Cutler, R.I.; Mohr, D.L.; Whittaker, J.K.; Yoder, N.R.

1983-01-01

A beam profile monitor has been constructed for the NBS-LANL Racetrack Microtron. The monitor consists of two perpendicular 30 μm diameter carbon wires that are driven through an electron beam by a pneumatic actuator. A long-lifetime, electroformed nickel bellows is used for the linear-motion vacuum feedthrough. Secondary emission current from the wires and a signal from a transducer measuring the position of the wires are simultaneously digitized by a microprocessor to yield beam current density profiles in two dimensions. The wire scanner is designed for use with both pulsed and cw beams

Angular distributions of absorbed dose of Bremsstrahlung and secondary electrons induced by 18-, 28- and 38-MeV electron beams in thick targets.

Science.gov (United States)

Takada, Masashi; Kosako, Kazuaki; Oishi, Koji; Nakamura, Takashi; Sato, Kouichi; Kamiyama, Takashi; Kiyanagi, Yoshiaki

2013-03-01

Angular distributions of absorbed dose of Bremsstrahlung photons and secondary electrons at a wide range of emission angles from 0 to 135°, were experimentally obtained using an ion chamber with a 0.6 cm(3) air volume covered with or without a build-up cap. The Bremsstrahlung photons and electrons were produced by 18-, 28- and 38-MeV electron beams bombarding tungsten, copper, aluminium and carbon targets. The absorbed doses were also calculated from simulated photon and electron energy spectra by multiplying simulated response functions of the ion chambers, simulated with the MCNPX code. Calculated-to-experimental (C/E) dose ratios obtained are from 0.70 to 1.57 for high-Z targets of W and Cu, from 15 to 135° and the C/E range from 0.6 to 1.4 at 0°; however, the values of C/E for low-Z targets of Al and C are from 0.5 to 1.8 from 0 to 135°. Angular distributions at the forward angles decrease with increasing angles; on the other hand, the angular distributions at the backward angles depend on the target species. The dependences of absorbed doses on electron energy and target thickness were compared between the measured and simulated results. The attenuation profiles of absorbed doses of Bremsstrahlung beams at 0, 30 and 135° were also measured.

Research on AutoCAD secondary development and function expansion based on VBA technology

Science.gov (United States)

Zhang, Runmei; Gu, Yehuan

2017-06-01

AutoCAD is the most widely used drawing tool among the similar design drawing products. In the process of drawing different types of design drawings of the same product, there are a lot of repetitive and single work contents. The traditional manual method uses a drawing software AutoCAD drawing graphics with low efficiency, high error rate and high input cost shortcomings and many more. In order to solve these problems, the design of the parametric drawing system of the hot-rolled I-beam (steel beam) cross-section is completed by using the VBA secondary development tool and the Access database software with large-capacity storage data, and the analysis of the functional extension of the plane drawing and the parametric drawing design in this paper. For the secondary development of AutoCAD functions, the system drawing work will be simplified and work efficiency also has been greatly improved. This introduction of parametric design of AutoCAD drawing system to promote the industrial mass production and related industries economic growth rate similar to the standard I-beam hot-rolled products.

Pulsed system for obtaining microdosimetric data with high intensity beams

International Nuclear Information System (INIS)

Zaider, M.; Dicello, J.F.; Hiebert, R.D.

1977-01-01

The use of heavy particle accelerators for radiation therapy requires high intensity beams in order to produce useful dose rates. The 800-MeV proton beam at LAMPF passes through different production targets to generate secondary pion beams. Conventional microdosimetric techniques are not applicable under these conditions because exceedingly high count rates result in detector damage, gas breakdown, and saturation effects in the electronics. We describe a new microdosimetric system developed at the Pion Biomedical Channel of LAMPF. The accelerator provides a variable low intensity pulse once every ten high intensity macropulses. The voltage on the detector is pulsed in coincidence with the low intensity pulse so that we were able to operate the detector under optimum data-taking conditions. A low noise two-stage preamplifier was built in connection with the pulsed mode operation. A comparison is made between data obtained in pulsed (high intensity beam) and unpulsed (low intensity beam) modes. The spectra obtained by the two methods agree within the experimental uncertainties

SU-E-T-542: Measurement of Internal Neutrons for Uniform Scanning Proton Beams

Energy Technology Data Exchange (ETDEWEB)

Islam, M; Ahmad, S [University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma (United States); Zheng, Y; Rana, S [Procure Proton Therapy Center, Oklahoma City, OK (United States); Collums, T [University of Iowa Hospitals and Clinics, Iowa City, IA (United States); Monsoon, J; Benton, E [Oklahoma State University, Stillwater, OK (United States)

2015-06-15

Purpose: In proton radiotherapy, the production of neutrons is a wellknown problem since neutron exposure can lead to increased risk of secondary cancers later in the patient’s lifetime. The assessment of neutron exposure is, therefore, important for the overall quality of proton radiotherapy. This study investigates the secondary neutrons created inside the patient from uniform scanning proton beams. Methods: Dose equivalent due to secondary neutrons was measured outside the primary field as a function of distance from beam isocenter at three different angles, 45, 90 and 135 degree, relative to beam axis. Plastic track nuclear detector (CR-39 PNTD) was used for the measurement of neutron dose. Two experimental configurations, in-air and cylindrical-phantom, were designed. In a cylindrical-phantom configuration, a cylindrical phantom of 5.5 cm diameter and 35 cm long was placed along the beam direction and in an in-air configuration, no phantom was used. All the detectors were placed at nearly identical locations in both configurations. Three proton beams of range 5 cm, 18 cm, and 32 cm with 4 cm modulation width and a 5 cm diameter aperture were used. The contribution from internal neutrons was estimated from the differences in measured dose equivalent between in-air and cylindrical-phantom configurations at respective locations. Results: The measured ratio of neutron dose equivalent to the primary proton dose (H/D) dropped off with distance and ranged from 27 to 0.3 mSv/Gy. The contribution of internal neutrons near the treatment field edge was found to be up to 64 % of the total neutron exposure. As the distance from the field edge became larger, the external neutrons from the nozzle appear to dominate and the internal neutrons became less prominent. Conclusion: This study suggests that the contribution of internal neutrons could be significant to the total neutron dose equivalent.

Electron beam injection during active experiments. 2. Collisional effects

International Nuclear Information System (INIS)

Winglee, R.M.

1990-01-01

During active beam experiments the presence of high neutral densities at low altitudes and/or during thruster firings has been observed to modify the spacecraft charging and the properties of the beam. Two-dimensional (three velocity) electromagnetic particle simulations with ionizing collisions incorporated are used to investigate the modification of the beam-plasma interaction as the neutral density is increased. It is shown that when the spacecraft is uniformly immersed in a neutral cloud, most of the ionization is produced by direct ionization by the beam and its secondaries, rather than via vehicle-induced or wave-ineuced ionization for the neutral densities considered. This ionization enhances the return current into the spacecraft with the spacecraft potential being reduced well below the beam energy whent he collison period is shorter than the spacecraft charging time. Neutral densities of about 10 11 -10 12 cm -3 are required to produce this reduction in the spacecraft potential for typical ionospheric and beam parameters. At these densities, the beam is able to propagate away from the spacecraft with little distortion except in the case of thruster firings where the beam can be subject to large space-charge oscillations near the boundaries of the neutral cloud. The ionization of neutrals in the beam region also modifies the wave emissions and spatial profile of return currents into the spacecraft, both of which tend to become localized to the beam region in high neutral densities

Design of automatic tracking system for electron beam welding

International Nuclear Information System (INIS)

He Chengdan; Chinese Academy of Space Technology, Lanzhou; Li Heqi; Li Chunxu; Ying Lei; Luo Yan

2004-01-01

The design and experimental process of an automatic tracking system applied to local vacuum electron beam welding are dealt with in this paper. When the annular parts of an exactitude apparatus were welded, the centre of rotation of the electron gun and the centre of the annular weld are usually not superposed because of the machining error, workpiece's setting error and so on. In this teaching process, a little bundle of electron beam is used to scan the weld groove, the amount of the secondary electrons reflected from the workpiece is different when the electron beam scans the both sides and the centre of the weld groove. The difference can indicate the position of the weld and then a computer will record the deviation between the electron beam spot and the centre of the weld groove. The computer will analyze the data and put the data into the storage software. During the welding process, the computer will modify the position of the electron gun based on the deviation to make the electron beam spot centered on the annular weld groove. (authors)

A study for the installation of the TEXT heavy-ion beam probe on DIII-D

International Nuclear Information System (INIS)

Edmonds, P.H.; Solano, E.R.; Bravenec, R.V.; Wootton, A.J.; Schoch, P.M.; Crowley, T.P.; Hickok, R.L.; West, W.P.; Leuer, J.; Anderson, P.

1997-01-01

An assessment of the feasibility of installing the TEXT 2 MeV heavy-ion beam probe on the DIII-D tokamak has been completed. Detailed drawings of the machine cross section were imported into the CAD application AutoCAD. A set of programs written in AutoLisp were used to generate trajectories. Displays of the accessible cross section of the plasma, scan lines for the entire range of primary beam energy and injection angle ranges, and sample endash volume dimensions can be rapidly generated. Because of the large deflection between the primary input beam and the emergent secondary beam, either the analyzer needs to be tracked over a ±20 degree angle or secondary poloidal deflector plates need to be installed at the exit port. Toroidal deflector plates will be installed at both the injection and exit ports to compensate for toroidal displacements and deflections. The sample volumes generated by this procedure are within a few centimeters of the locations derived from a full three-dimensional calculation.copyright 1997 American Institute of Physics

SLIM (SEM for Low Interception Monitoring) An Innovative Non-Destructive Beam Monitor for the Extraction Lines of a Hadrontherapy Centre

CERN Document Server

Badano, L; Pezzetta, M; Molinari, G

2003-01-01

Real time monitoring of hadrontherapy beam intensity and profile is a critical issue for the optimisation of the dose delivery to the patient carcinogenic tissue, the patient safety and the operation of the accelerator complex. For this purpose an innovative beam monitor, based on the secondary emission of electrons by a nonperturbative, sub-micron thick Al target placed directly in the extracted beam path, is being proposed. The secondary electrons, accelerated by an electrostatics focusing system, are detected by a monolithic silicon position sensitive sensor, which provides the beam intensity and its position with a precision of 1 mm at 10 kHz frame rate. The conceptual design and the engineering study optimised for hadrontherapy, together with the results of the preliminary tests of the first system prototype, will be presented.

The H line: a brand new beam line for fundamental physics at the J-PARC muon facility

International Nuclear Information System (INIS)

Kawamura, N; Shimomura, K; Miyake, Y; Toyoda, A; Saito, N; Mihara, S; Aoki, M

2013-01-01

The muon facility, J-PARC (Muon Science Establishment; MUSE), has been operated since first beam in 2008. Starting with a 200 kW proton beam, the beam intensity has reached 3×10 6 / muons/s, the most intense pulsed muon beam in the world. A 2 cm thick graphite target permits the extraction of four secondary muon beams. A brand new beam line, the H line, is planned to be constructed. The new beam line is designed to have a large acceptance, will provide the ability to tune the momentum, and use a kicker magnet and/or Wien filter. This beam line will provide an intense beam for experiments that require high statistics and must occupy the experimental areas for a relatively long period.

High-efficiency detector of secondary and backscattered electrons for low-dose imaging in the ESEM.

Science.gov (United States)

Neděla, Vilém; Tihlaříková, Eva; Runštuk, Jiří; Hudec, Jiří

2018-01-01

A new Combined System for high-efficiency detection of Secondary and Backscattered Electrons (CSSBE) in the ESEM consists of three detectors: an ionisation SE detector, an improved scintillation BSE detector, and a new Ionisation Secondary Electron Detector with an electrostatic Separator (ISEDS). The ISEDS optimizes conditions for electron-gas ionisation phenomena in the ESEM to achieve a strongly amplified signal from the secondary electrons with a minimal contribution from backscattered and beam electrons. For this purpose, it is originally equipped with an electrostatic separator, which focuses signal electrons towards a detection electrode and controls the concentration of positive ions above the sample. The working principle of the ISEDS is explained by simulations of signal electron trajectories in gas using the EOD program with our Monte Carlo module. The ability to detect the signal electrons in a selected range of energies is described with Geant4 Monte Carlo simulations of electron-solid interactions and proven by experimental results. High-efficiency detection of the ISEDS is demonstrated by imaging a low atomic number sample under a reduced beam energy of 5 keV, very low beam currents of up to 0.2 pA, and gas pressure of hundreds of Pa. Copyright © 2017 Elsevier B.V. All rights reserved.

Sub 100 nm proton beam micromachining: theoretical calculations on resolution limits

International Nuclear Information System (INIS)

Kan, J.A. van; Sum, T.C.; Osipowicz, T.; Watt, F.

2000-01-01

Proton beam micromachining is a novel direct-write process for the production of three-dimensional (3D) microstructures. A focused beam of MeV protons is scanned in a pre-determined pattern over a suitable resist material (e.g. PMMA or SU-8) and the latent image formed is subsequently developed chemically. In this paper calculations on theoretical resolution limits of proton beam micromachined three-dimensional microstructures are presented. Neglecting the finite beam size, a Monte Carlo ion transport code was used in combination with a theoretical model describing the delta-ray (δ-ray) energy deposition to determine the lateral energy deposition distribution in PMMA resist material. The energy deposition distribution of ion induced secondary electrons (δ-rays) has been parameterized using analytical models. It is assumed that the attainable resolution is limited by a convolution of the spread of the ion beam and energy deposition of the δ-rays

Spectra of the linear energy transfer measured with a track etch spectrometer in the beam of 1 GeV protons and the contribution of secondary charged particles to the dose

International Nuclear Information System (INIS)

Spurny, F.; Vlcek, B.; Bamblevskij, V.P.; Timoshenko, G.N.

1999-01-01

A spectrometer of the linear energy transfer (LET) on the base of CR-39 detector was used to establish the spectra of LET in the beam of protons with the primary energy of 1 GeV. It was found out that the LET spectra of secondary charged particles between 100 and 7000 MeV cm 2 g -1 do not depend on the radiator. The average quality factors for the LET region mentioned were obtained about 11.6 with ICRP 26 quality factors and about 14.0 with ICRP 60 quality factors. The spectra obtained permitted to calculate the contributions of these secondary charged particles to the dosimetric quantities. It was observed that these contributions were about 7.0% for the total absorbed dose of protons and close 90% in the case of the equivalent doses. It is more than it was found out for few hundred MeV protons

Secondary neutron doses received by patients of different ages during intracranial proton therapy treatments

International Nuclear Information System (INIS)

Sayah, R.

2012-01-01

Proton therapy is an advanced radiation therapy technique that allows delivering high doses to the tumor while saving the healthy surrounding tissues due to the protons' ballistic properties. However, secondary particles, especially neutrons, are created during protons' nuclear reactions in the beam-line and the treatment room components, as well as inside the patient. Those secondary neutrons lead to unwanted dose deposition to the healthy tissues located at distance from the target, which may increase the secondary cancer risks to the patients, especially the pediatric ones. The aim of this work was to calculate the neutron secondary doses received by patients of different ages treated at the Institut Curie-centre de Protontherapie d'Orsay (ICPO) for intracranial tumors, using a 178 MeV proton beam. The treatments are undertaken at the new ICPO room equipped with an IBA gantry. The treatment room and the beam-line components, as well as the proton source were modeled using the Monte Carlo code MCNPX. The obtained model was then validated by a series of comparisons between model calculations and experimental measurements. The comparisons concerned: a) depth and lateral proton dose distributions in a water phantom, b) neutron spectrometry at one position in the treatment room, c) ambient dose equivalents at different positions in the treatment room and d) secondary absorbed doses inside a physical anthropomorphic phantom. A general good agreement was found between calculations and measurements, thus our model was considered as validated. The University of Florida hybrid voxelized phantoms of different ages were introduced into the MCNPX validated model, and secondary neutron doses were calculated to many of these phantoms' organs. The calculated doses were found to decrease as the organ's distance to the treatment field increases and as the patient's age increases. The secondary doses received by a one year-old patient may be two times higher than the doses

Electron cloud effects in intense, ion beam linacs theory and experimental planning for heavy-ion fusion

International Nuclear Information System (INIS)

Molvik, A.W.; Cohen, R.H.; Lund, S.M.; Bieniosek, F.M.; Lee, E.P.; Prost, L.R.; Seidl, P.A.; Vay, Jean-Luc

2002-01-01

Heavy-ion accelerators for HIF will operate at high aperture-fill factors with high beam current and long pulses. This will lead to beam ions impacting walls: liberating gas molecules and secondary electrons. Without special preparation a large fractional electron population ((ge)1%) is predicted in the High-Current Experiment (HCX), but wall conditioning and other mitigation techniques should result in substantial reduction. Theory and particle-in-cell simulations suggest that electrons, from ionization of residual and desorbed gas and secondary electrons from vacuum walls, will be radially trapped in the ∼4 kV ion beam potential. Trapped electrons can modify the beam space charge, vacuum pressure, ion transport dynamics, and halo generation, and can potentially cause ion-electron instabilities. Within quadrupole (and dipole) magnets, the longitudinal electron flow is limited to drift velocities (E x B and (del)B) and the electron density can vary azimuthally, radially, and longitudinally. These variations can cause centroid misalignment, emittance growth and halo growth. Diagnostics are being developed to measure the energy and flux of electrons and gas evolved from walls, and the net charge and gas density within magnetic quadrupoles, as well as the their effect on the ion beam

Beam loss monitor system for machine protection

CERN Document Server

Dehning, B

2005-01-01

Most beam loss monitoring systems are based on the detection of secondary shower particles which depose their energy in the accelerator equipment and finally also in the monitoring detector. To allow an efficient protection of the equipment, the likely loss locations have to be identified by tracking simulations or by using low intensity beams. If superconducting magnets are used for the beam guiding system, not only a damage protection is required but also quench preventions. The quench levels for high field magnets are several orders of magnitude below the damage levels. To keep the operational efficiency high under such circumstances, the calibration factor between the energy deposition in the coils and the energy deposition in the detectors has to be accurately known. To allow a reliable damage protection and quench prevention, the mean time between failures should be high. If in such failsafe system the number of monitors is numerous, the false dump probability has to be kept low to keep a high operation...

Design and performance of a Tesla transformer type relativistic electron beam generator

International Nuclear Information System (INIS)

Jain, K.K.; Chennareddy, D.; John, P.I.; Saxena, Y.C.

1986-01-01

A relativistic electron beam generator driven by an air core Tesla transformer is described. The Tesla transformer circuit analysis is outlined and computational results are presented for the case when the coaxial water line has finite resistance. The transformer has a coupling coefficient of 0.56 and a step-up ratio of 25. The Tesla transformer can provide 800 kV at the peak of the second half cycle of the secondary output voltage and has been tested up to 600 kV. A 100-200 keV, 15-20 kA electron beam having 150 ns pulse width has been obtained. The beam generator described is being used for the beam injection into a toroidal device BETA. (author). 20 refs. 9 figures

A novel method to survey parameters of an ion beam and its interaction with a target

Science.gov (United States)

Long, J. D.; Yang, Z.; Li, J.; Wang, X. H.; Wang, T.; Lan, C. H.; Dong, P.; Li, X.; He, J. L.; Zheng, L.; Liu, P.

2017-09-01

Beam profile and composition of the pulsed ion beam from a vacuum arc source are valuable information for designing a high-intensity deuterium-tritium neutron generator. Traditional methods are notoriously difficult to obtain the information at the same time. A novel off-line diagnostic method is presented, which can obtain the transverse beam profile with high resolution as well as species of the ions in the beam. The method is using a silicon target with high purity to interact with the ion beam, and then use secondary ion mass spectrometry (SIMS) to analyze the interaction zone of the target to get the beam information. More information on beam-target interaction could get simultaneously. Proof-of-principle simulation and experimental works have demonstrated this method is practical.

Preparation of thermal resistant-enhanced separators for lithium ion battery by electron beam irradiation

Energy Technology Data Exchange (ETDEWEB)

Sohn, Joon Yong; Shin, Junhwa; Nho, Youngchang [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2012-03-15

Micro-porous membrane made of polyethylene (PE) or polypropylene (PP) is most widely used as physical separators between the cathode and anode in lithium secondary batteries. However, the polymer membranes so soften or melt when the temperature reaches 130 .deg. C or higher because of thermal shrinkage of the polyolefin separators, and thaw low thermal stability may cause internal short circuiting or lead to thermal runaway. In this study, to realize a highly safe battery, we prepared three type separators as crosslinked PE separator, polymer-coated PE separator, and ceramic-coated PE separators, for lithium secondary battery by electron beam irradiation. We prepared crosslinked PE separators with the improved thermal stability by irradiating a commercial PE separator with an electron beam. A polymer-coated PE separator was prepared by a dip-coating of PVDF-HFP/PEGDMA on both sides of a PE separator followed by an electron beam irradiation. Ceramic-coated PE separator was prepared by coating ceramic particles on a PE separator followed by an electron beam irradiation. The prepared separators were characterized with FT-IR, SEM, electrolyte uptake, ion conductivity, thermal shrinkage and battery performance test.

Radiation and Background Levels in a CLIC Detector due to Beam-Beam Effects Optimisation of Detector Geometries and Technologies

CERN Document Server

Sailer, André; Lohse, Thomas

2013-01-10

The high charge density---due to small beam sizes---and the high energy of the proposed CLIC concept for a linear electron--positron collider with a centre-of-mass energy of up to 3~TeV lead to the production of a large number of particles through beam-beam interactions at the interaction point during every bunch crossing (BX). A large fraction of these particles safely leaves the detector. A still significant amount of energy will be deposited in the forward region nonetheless, which will produce secondary particles able to cause background in the detector. Furthermore, some particles will be created with large polar angles and directly cause background in the tracking detectors and calorimeters. The main sources of background in the detector, either directly or indirectly, are the incoherent $mathrm{e}^{+}mathrm{e}^{-}$ pairs and the particles from $gammagamma ightarrow$ hadron events. The background and radiation levels in the detector have to be estimated, to study if a detector is feasible, that can han...

Processes in a dense long-pulse electron beam focused on a solid target

Energy Technology Data Exchange (ETDEWEB)

Arkhipov, A V; Sominskij, G G [St. Petersburg Technical Univ. (Russian Federation)

1997-12-31

The results obtained in beam-target experiments with dense medium-energy electron beam in the regime of long single pulses are presented. The measured power density of the focused beam at the target reached 20 MW/cm{sup 2} in these experiments. The processes caused by dense flows of secondary particles and by a dense target ablation plasma were studied in detail. Substantial target shielding occurs when the energy density at the target exceeds the value of about 1 kJ/cm{sup 2}. The target plasma and the sputtered matter that is responsible for shielding affects also the beam structure, as well as the target etching rates. (J.U.). 3 figs., 5 refs.

Processes in a dense long-pulse electron beam focused on a solid target

International Nuclear Information System (INIS)

Arkhipov, A.V.; Sominskij, G.G.

1996-01-01

The results obtained in beam-target experiments with dense medium-energy electron beam in the regime of long single pulses are presented. The measured power density of the focused beam at the target reached 20 MW/cm 2 in these experiments. The processes caused by dense flows of secondary particles and by a dense target ablation plasma were studied in detail. Substantial target shielding occurs when the energy density at the target exceeds the value of about 1 kJ/cm 2 . The target plasma and the sputtered matter that is responsible for shielding affects also the beam structure, as well as the target etching rates. (J.U.). 3 figs., 5 refs

Multi-channel electronics for secondary emission grid profile monitor of TTF linac

International Nuclear Information System (INIS)

Reingardt-Nikoulin, P.; Gaidash, V.; Mirzojan, A.; Kocharyan, V.; Noelle, D.

2004-01-01

According to the TTF beam experimental program, a measurement f the time dependence of the energy spread within the bunch train should be done by means of a standard device for profile measurements, that is Secondary Emission Grid (SEMG). SEMG on the high-energy TTF beam is placed in the focal plane of the magnet spectrometer. It should measure the total energy spread in the range from 0.1% up to a few percents for any single or any group of electron bunches in the bunch train of TTF Linac. SEMG profile measurements with new high sensitive electronics are described. Beam results of SEMG Monitor test are given for two modifications of an electronic preamplifier

Experimental results of beryllium exposed to intense high energy proton beam pulses

CERN Document Server

Ammigan, K; Hurh, P; Zwaska, R; Butcher, M; Guinchard, M; Calviani, M; Losito, R; Roberts, S; Kuksenko, V; Atherton, A; Caretta, O; Davenne, T; Densham, C; Fitton, M; Loveridge, J; O'Dell, J

2017-01-01

Beryllium is extensively used in various accelerator beam lines and target facilities as a material for beam windows, and to a lesser extent, as secondary particle production targets. With increasing beam intensities of future accelerator facilities, it is critical to understand the response of beryllium under extreme conditions to reliably operate these components as well as avoid compromising particle production efficiency by limiting beam parameters. As a result, an exploratory experiment at CERN’s HiRadMat facility was carried out to take advantage of the test facility’s tunable high intensity proton beam to probe and investigate the damage mechanisms of several beryllium grades. The test matrix consisted of multiple arrays of thin discs of varying thicknesses as well as cylinders, each exposed to increasing beam intensities. This paper outlines the experimental measurements, as well as findings from Post-Irradiation-Examination (PIE) work where different imaging techniques were used to analyze and co...

Experimental results of beryllium exposed to intense high energy proton beam pulses

Energy Technology Data Exchange (ETDEWEB)

Ammigan, K. [Fermilab; Hartsell, B. [Fermilab; Hurh, P. [Fermilab; Zwaska, R. [Fermilab; Butcher, M. [CERN; Guinchard, M. [CERN; Calviani, M. [CERN; Losito, R. [CERN; Roberts, S. [Culham Lab; Kuksenko, V. [Oxford U.; Atherton, A. [Rutherford; Caretta, O. [Rutherford; Davenne, T. [Rutherford; Densham, C. [Rutherford; Fitton, M. [Rutherford; Loveridge, J. [Rutherford; O' Dell, J. [Rutherford

2017-02-10

Beryllium is extensively used in various accelerator beam lines and target facilities as a material for beam windows, and to a lesser extent, as secondary particle production targets. With increasing beam intensities of future accelerator facilities, it is critical to understand the response of beryllium under extreme conditions to reliably operate these components as well as avoid compromising particle production efficiency by limiting beam parameters. As a result, an exploratory experiment at CERN’s HiRadMat facility was carried out to take advantage of the test facility’s tunable high intensity proton beam to probe and investigate the damage mechanisms of several beryllium grades. The test matrix consisted of multiple arrays of thin discs of varying thicknesses as well as cylinders, each exposed to increasing beam intensities. This paper outlines the experimental measurements, as well as findings from Post-Irradiation-Examination (PIE) work where different imaging techniques were used to analyze and compare surface evolution and microstructural response of the test matrix specimens.

Low Secondary Electron Yield Carbon Coatings for Electron Cloud Mitigation in Modern Particle Accelerators

CERN Document Server

Yin Vallgren, Christina; Taborelli, Mauro

2011-01-01

In order to upgrade the Large Hadron Collider (LHC) performance to be oriented towards higher energies and higher intensities in the future, a series of improvements of the existing LHC injectors is planned to take place over the next few years. Electron cloud effects are expected to be enhanced and play a central role in limiting the performance of the machines of the CERN complex. Electron cloud phenomena in beam pipes are based on electron multiplication and can be sufficiently suppressed if the Secondary Electron Yield (SEY) of the surface of the beam pipes is lower than unity. The goal of this work is to find and study a thin film coating with reliably low initial Secondary Electron Yield (SEY), which does not require bake-out or conditioning in situ with photons, is robust again air exposure and can easily be applied in the beam pipes of accelerators. In this work, amorphous carbon (a-C) thin films have been prepared by DC magnetron sputtering for electron cloud mitigation and antimultipactor applicatio...

HIE-ISOLDE Faraday cups tested with ion beams at TRIUMF

CERN Document Server

Cantero, E D

2014-01-01

The future HIE-ISOLDE Faraday cups for both the intercryomodule regions and the HEBTs have been tested using 34S+7, 4He+, 23Na+6 and 20Ne+5 beams from the ISAC-II accelerator at TRIUMF. Their performance has been characterized together with the Faraday cups from REX-ISOLDE and those from ISAC-II. The measurements were done at E/A = 1.5, 2.85 and 5.5 MeV/u, with beam intensities in the range of 100 pA to 4 nA. The performance of these Faraday cups has been compared under the same beam conditions for different bias voltages up to -350 V. Within the experimental uncertainties, most of them coming from fluctuations in beam intensity, all devices showed similar results. Biasing the Faraday cup repeller ring to voltages of at least -60 V, the escape of secondary electrons was suppressed.

The Effect of Gas Ion Bombardment on the Secondary Electron Yield of TiN, TiCN and TiZrV Coatings For Suppressing Collective Electron Effects in Storage Rings

International Nuclear Information System (INIS)

Le Pimpec, F.; Kirby, R.E.; King, F.K.; Pivi, M.

2006-01-01

In many accelerator storage rings running positively charged beams, ionization of residual gas and secondary electron emission (SEE) in the beam pipe will give rise to an electron cloud which can cause beam blow-up or loss of the circulating beam. A preventative measure that suppresses electron cloud formation is to ensure that the vacuum wall has a low secondary emission yield (SEY). The SEY of thin films of TiN, sputter deposited Non-Evaporable Getters and a novel TiCN alloy were measured under a variety of conditions, including the effect of re-contamination from residual gas

Secondary radiation dose during high-energy total body irradiation

Energy Technology Data Exchange (ETDEWEB)

Janiszewska, M.; Raczkowski, M. [Lower Silesian Oncology Center, Medical Physics Department, Wroclaw (Poland); Polaczek-Grelik, K. [University of Silesia, Medical Physics Department, Katowice (Poland); Szafron, B.; Konefal, A.; Zipper, W. [University of Silesia, Department of Nuclear Physics and Its Applications, Katowice (Poland)

2014-05-15

The goal of this work was to assess the additional dose from secondary neutrons and γ-rays generated during total body irradiation (TBI) using a medical linac X-ray beam. Nuclear reactions that occur in the accelerator construction during emission of high-energy beams in teleradiotherapy are the source of secondary radiation. Induced activity is dependent on the half-lives of the generated radionuclides, whereas neutron flux accompanies the treatment process only. The TBI procedure using a 18 MV beam (Clinac 2100) was considered. Lateral and anterior-posterior/posterior-anterior fractions were investigated during delivery of 2 Gy of therapeutic dose. Neutron and photon flux densities were measured using neutron activation analysis (NAA) and semiconductor spectrometry. The secondary dose was estimated applying the fluence-to-dose conversion coefficients. The main contribution to the secondary dose is associated with fast neutrons. The main sources of γ-radiation are the following: {sup 56}Mn in the stainless steel and {sup 187}W of the collimation system as well as positron emitters, activated via (n,γ) and (γ,n) processes, respectively. In addition to 12 Gy of therapeutic dose, the patient could receive 57.43 mSv in the studied conditions, including 4.63 μSv from activated radionuclides. Neutron dose is mainly influenced by the time of beam emission. However, it is moderated by long source-surface distances (SSD) and application of plexiglass plates covering the patient body during treatment. Secondary radiation gives the whole body a dose, which should be taken into consideration especially when one fraction of irradiation does not cover the whole body at once. (orig.) [German] Die zusaetzliche Dosis durch sekundaere Neutronen- und γ-Strahlung waehrend der Ganzkoerperbestrahlung mit Roentgenstrahlung aus medizinischen Linearbeschleunigern wurde abgeschaetzt. Bei der Emission hochenergetischer Strahlen zur Teletherapie finden hauptsaechlich im Beschleuniger

Secondary electron measurement and XPS characterization of NEG coatings

International Nuclear Information System (INIS)

Sharma, R. K.; Sinha, Atul K.; Gupta, Nidhi; Nuwad, J.; Jagannath,; Gadkari, S. C.; Singh, M. R.; Gupta, S. K.

2014-01-01

Ternary alloy coatings of IVB and VB materials provide many of benefits over traditional material surfaces such as creation of extreme high vacuum(XHV), lower secondary electron yield(SEY), low photon desorption coefficient. XHV (pressure −10 mbar) is very useful to the study of surfaces of the material in as it is form, high energy particle accelerators(LHC, Photon Factories), synchrotrons (ESRF, Ellectra) etc.. Low secondary electron yield leads to very low multi-pacting utilizes to increase beam life time. In this paper preparation of the coatings and a study of secondary electron yield measurement after heating at different temperatures has been shown also results of their surface characterization based on shift in binding energy has been produced using the surface techniques XPS. Stoichiometry of the film was measured by Energy dispersive x-ray analysis (EDX)

Electron beam effects in auger electron spectroscopy and scanning electron microscopy

International Nuclear Information System (INIS)

Fontaine, J.M.; Duraud, J.P.; Le Gressus, C.

1979-01-01

Electron beam effects on Si(100) and 5% Fe/Cr alloy samples have been studied by measurements of the secondary electron yield delta, determination of the surface composition by Auger electron spectroscopy and imaging with scanning electron microscopy. Variations of delta as a function of the accelerating voltage Esub(p) (0.5 -9 Torr has no effect on technological samples covered with their reaction layers; the sensitivities to the beam depend rather on the earlier mechanical, thermal and chemical treatment of the surfaces. (author)

Propagation of modulated electron and X-ray beams through matter and interactions with radio-frequency structures

Science.gov (United States)

Harris, J. R.; Miller, R. B.

2018-02-01

The generation and evolution of modulated particle beams and their interactions with resonant radiofrequency (RF) structures are of fundamental interest for both particle accelerator and vacuum electronic systems. When the constraint of propagation in a vacuum is removed, the evolution of such beams can be greatly affected by interactions with matter including scattering, absorption, generation of atmospheric plasma, and the production of multiple generations of secondary particles. Here, we study the propagation of 21 MeV and 25 MeV electron beams produced in S-band and L-band linear accelerators, and their interaction with resonant RF structures, under a number of combinations of geometry, including transmission through both air and metal. Both resonant and nonresonant interactions were observed, with the resonant interactions indicating that the RF modulation on the electron beam is at least partially preserved as the beam propagates through air and metal. When significant thicknesses of metal are placed upstream of a resonant structure, preventing any primary beam electrons from reaching the structure, RF signals could still be induced in the structures. This indicated that the RF modulation present on the electron beam was also impressed onto the x-rays generated when the primary electrons were stopped in the metal, and that this RF modulation was also present on the secondary electrons generated when the x-rays struck the resonant structures. The nature of these interactions and their sensitivities to changes in system configurations will be discussed.

Electron-beam induced structural and function change of microbial peroxiredoxin

Energy Technology Data Exchange (ETDEWEB)

Hong, S. H.; An, B. C.; Lee, S. S.; Lee, E. M.; Chung, B. Y. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2012-03-15

Pseudomonas aerogenes peroxiredoxin (PaPrx) has dual functions acting as thioredoxin (Trx)-dependent peroxidase and molecular chaperone. The function of PaPrx is controlled by its structural status. In this study, we examined the effect of electron beam on structural modification related to chaperone activity. When irradiated electron beam at 1 kGy, the structural and functional changes of PaPrx were initiated. The enhanced chaperone activity was increased about 3- 40 4-fold at 2 kGy compared with non-irradiated, while the peroxidase activity was decreased. We also investigated the influence of the electron beam on protein physical property factors such as hydrophobicity and secondary structure. The exposure of hydrophobic domains reached a peak at 2 kGy of electron beam and then dose-dependently decreased with increasing electron beam irradiation. In addition, the electron beam irradiated PaPrx significantly increased exposure of {beta}-sheet and random coil elements on the protein surface whereas exposure of {alpha}-helix and turn elements was decreased. Our results suggest that highly enhanced chaperone activity could be applied to use in bio-engineering system and various industrial applications.

Electron-beam induced structural and function change of microbial peroxiredoxin

International Nuclear Information System (INIS)

Hong, S. H.; An, B. C.; Lee, S. S.; Lee, E. M.; Chung, B. Y.

2012-01-01

Pseudomonas aerogenes peroxiredoxin (PaPrx) has dual functions acting as thioredoxin (Trx)-dependent peroxidase and molecular chaperone. The function of PaPrx is controlled by its structural status. In this study, we examined the effect of electron beam on structural modification related to chaperone activity. When irradiated electron beam at 1 kGy, the structural and functional changes of PaPrx were initiated. The enhanced chaperone activity was increased about 3- 40 4-fold at 2 kGy compared with non-irradiated, while the peroxidase activity was decreased. We also investigated the influence of the electron beam on protein physical property factors such as hydrophobicity and secondary structure. The exposure of hydrophobic domains reached a peak at 2 kGy of electron beam and then dose-dependently decreased with increasing electron beam irradiation. In addition, the electron beam irradiated PaPrx significantly increased exposure of β-sheet and random coil elements on the protein surface whereas exposure of α-helix and turn elements was decreased. Our results suggest that highly enhanced chaperone activity could be applied to use in bio-engineering system and various industrial applications

Simulation of an antiprotons beam applied to the radiotherapy

International Nuclear Information System (INIS)

Prata, Leonardo de Almeida

2006-07-01

Results for the interaction of a antiproton beam with constituent nuclei of the organic matter are presented. This method regards of the application of an computational algorithm to determine quantitatively the differential cross sections for the scattered particles, starting from the interaction of these antiprotons with the nuclei, what will allow in the future to draw the isodose curve for antiproton therapy, once these beams are expected to be used in cancer treatment soon. The calculation will be done through the application of the concepts of the method of intranuclear cascade, providing yield and differential cross sections of the scattered particles, present in the software MCMC. Th algorithm was developed based on Monte Carlo's method, already taking into account a validate code. The following physical quantities are presented: the yield of secondary particles, their spectral and angular distributions for these interactions. For the energy range taken into account the more important emitted particles are protons, neutrons and pions. Results shown that emitted secondary particles can modify the isodose curves, because they present high yield and energy for transverse directions. (author)

Secondary electron emission studied by secondary electron energy loss coincidence spectroscopy (SE2ELCS)

International Nuclear Information System (INIS)

Khalid, R.

2013-01-01

Emission of secondary electrons is of importance in many branches of fundamental and applied science. It is widely applied in the electron microscope for the investigation of the structure and electronic state of solid surfaces and particle detection in electron multiplier devices, and generally it is related to the energy dissipation of energetic particles moving inside a solid. The process of secondary electron emission is a complex physical phenomenon, difficult to measure experimentally and treat theoretically with satisfactory accuracy. The secondary electron spectrum measured with single electron spectroscopy does not provide detailed information of the energy loss processes responsible for the emission of secondary electrons. This information can be accessed when two correlated electron pairs are measured in coincidence and the pair consists of a backscattered electron after a given energy loss and a resulting emitted secondary electron. To investigate the mechanisms responsible for the emission of secondary electrons, a reflection (e,2e) coincidence spectrometer named Secondary Electron Electron Energy Loss Coincidence Spectrometer (SE2ELCS) has been developed in the framework of this thesis which allows one to uncover the relation between the features in the spectra which are due to energy losses and true secondary electron emission structures. The correlated electron pairs are measured with a hemispherical mirror analyzer (HMA) and a time of flight analyzer (TOF) by employing a continuous electron beam. An effort has been made to increase the coincidence count rate by increasing the effective solid angle of the TOF analyzer and optimizing the experimental parameters to get optimum energy resolution. Double differential coincidence spectra for a number of materials namely, nearly free electron metals (Al, Si), noble metals (Ag, Au, Cu, W) and highly oriented pyrolytic graphite (HOPG) have been measured using this coincidence spectrometer. The

On the regularities of gamma-ray initiated emission of really-secondary electrons

International Nuclear Information System (INIS)

Grudskij, M.Ya.; Roldugin, N.N.; Smirnov, V.V.

1982-01-01

Emission regularities of the really-secondary electrons from metals are discussed on the basis of experimental data on electron emission characteristics under gamma radiation of incident quanta produced for a wide energy range (Esub(γ)=0.03+-2 MeV) and atomic numbers of target materials (Z=13+-79). Comparison with published experimental and calculated data is performed. It is shown that yield of the really-secondary electrons into vacuum from the target surface bombarded with a normally incident collimated beam of gamma radiation calculating on energy unit absorbed in the yield zone of the really-secondary electrons is determined only with the target material emittivity and can be calculated if spatial-energy distributions and the number of secondary fast electrons emitted out of the target are known

MONDO: A tracker for the characterization of secondary fast and ultrafast neutrons emitted in particle therapy

Science.gov (United States)

Mirabelli, R.; Battistoni, G.; Giacometti, V.; Patera, V.; Pinci, D.; Sarti, A.; Sciubba, A.; Traini, G.; Marafini, M.

2018-01-01

In Particle Therapy (PT) accelerated charged particles and light ions are used for treating tumors. One of the main limitation to the precision of PT is the emission of secondary particles due to the beam interaction with the patient: secondary emitted neutrons can release a significant dose far from the tumor. Therefore, a precise characterization of their flux, production energy and angle distribution is eagerly needed in order to improve the Treatment Planning Systems (TPS) codes. The principal aim of the MONDO (MOnitor for Neutron Dose in hadrOntherapy) project is the development of a tracking device optimized for the detection of fast and ultra-fast secondary neutrons emitted in PT. The detector consists of a matrix of scintillating square fibres coupled with a CMOS-based readout. Here, we present the characterization of the detector tracker prototype and CMOS-based digital SPAD (Single Photon Avalanche Diode) array sensor tested with protons at the Beam Test Facility (Frascati, Italy) and at the Proton Therapy Centre (Trento, Italy), respectively.

Beam emittance of the Stony Brook Tandem-LINAC booster

International Nuclear Information System (INIS)

Scholldorf, A.H.

1984-01-01

This dissertation is primarily a study of the longitudinal and transverse beam emittance of the Stony Brook Heavy Ion Tandem LINAC Accelerator Facility, with a secondary emphasis on the beam dynamical design of two key elements of the system: a low energy double-drift buncher, and an achromatic double-90 0 LINAC injection system. A transverse emittance measuring system consisting of two translation stages controlled by stepper motors is described. Each stage carried a pair of beam defining slits mounted so that both horizontal and vertical emittances could be measured with only linear motion of the stage assembly. Beam currents were measured directly by a low-noise, high-sensitivity electrometer circuit integrated with the second slit-stage assembly. A mini-computer controlled the motors and acquired and displayed the data. Transverse emittance areas of beams of 12 C, 16 O, 32 S, and 58 Ni were measured at ion source extraction potential, after ion source acceleration, after tandem acceleration, and after LINAC acceleration. The results were analyzed in terms of source sputter-cone geometry, angle straggling in gas and foil strippers, and a variety of other factors

Spill control and intensity monitoring for the Bevatron--Bevalac external particle beams

International Nuclear Information System (INIS)

Barale, J.J.; Crebbin, K.C.

1975-03-01

Time-intensity modulation in beam spill can be of primary concern in some experiments. The major source of this beam structure is from main-guide field-magnet power supply ripple. If the time constants are appropriate, then final control of beam structure can be accomplished by closed loop control of the intensity of beam spill. The response characteristics of the feedback system will determine the final structure. At high beam fluxes signal to noise ratio of beam detectors, in the feedback loop, can be improved by at least four orders of magnitude by using photomultiplier tubes and a water Cherenkov counter in place of the normal secondary emission monitor. At beam fluxes below 10 10 particles per second (PPS), a plastic scintillator and photomultiplier tube are used in the feedback system. A plastic scintillator and photomultiplier are also used in the beam as intensity monitors. At intensities below about 10 7 PPS standard counting techniques are used. For intensities between 10 6 to 110 9 PPS, the photomultiplier is used as a current source driving an integrating circuit which is then calibrated to read the number of particles per pulse. (U.S.)

In-vacuum sensors for the beamline components of the ITER neutral beam test facility

Energy Technology Data Exchange (ETDEWEB)

Dalla Palma, M., E-mail: mauro.dallapalma@igi.cnr.it; Pasqualotto, R.; Spagnolo, S.; Spolaore, M. [Consorzio RFX, Padova 35127 (Italy); Sartori, E. [Consorzio RFX, Padova 35127 (Italy); Università degli Studi di Padova, Padova 35122 (Italy); Veltri, P. [Consorzio RFX, Padova 35127 (Italy); INFN-LNL, Legnaro (PD) 35020 (Italy)

2016-11-15

Embedded sensors have been designed for installation on the components of the MITICA beamline, the prototype ITER neutral beam injector (Megavolt ITER Injector and Concept Advancement), to derive characteristics of the particle beam and to monitor the component conditions during operation for protection and thermal control. Along the beamline, the components interacting with the particle beam are the neutralizer, the residual ion dump, and the calorimeter. The design and the positioning of sensors on each component have been developed considering the expected beam-surface interaction including non-ideal and off-normal conditions. The arrangement of the following instrumentation is presented: thermal sensors, strain gages, electrostatic probes including secondary emission detectors, grounding shunt for electrical currents, and accelerometers.

Investigations of the neutron halo by radioactive beam experiments

International Nuclear Information System (INIS)

Mueller, A.C.

1993-01-01

Recently, a new tool has become available to study the behaviour of nuclei at the limits of particle stability. Heavy-ion projectile fragmentation, in combination with efficient recoil spectrometers, allows to prepare 'exotic' beams which can be used to induce secondary nuclear reactions. First experiments have revealed surprising features in the reactions of the most neutron-rich light nuclei. There is now conclusive evidence that the observed effects are due to long-tail matter distributions ('neutron halo') which occur for the last, very weakly bound neutrons. The results of some recent radioactive beam experiments, made by means of the spectrometer LISE3 at GANIL, are presented. (author) 24 refs.; 7 figs

Measurements of secondary emissions from plasma arc and laser cutting in standard experiments

International Nuclear Information System (INIS)

Pilot, G.; Noel, J.P.; Leautier, R.; Steiner, H.; Tarroni, G.; Waldie, B.

1992-01-01

As part of an inter-facility comparison of secondary emissions from plasma arc and laser-cutting techniques, standard cutting tests have been done by plasma arc underwater and in air, and by laser beam in air. The same team was commissioned to measure the secondary emissions (solid and gaseous) in each contractor's facility with the same measuring rig. 20 mm and 40 mm thick, grade 304 stainless-steel plates were cut by plasma-torch in three different facilities: Heriot Watt University of Edinburgh, Institut fuer Werkstoffkunde of Universitaet Hannover and CEA/CEN Cadarache. 10 mm and in some cases 20 mm thick, grade 304, stainless-steel plates were cut by laser beam in five different facilities: CEA-CEN Fontenay, CEA-CEN Saclay, Institut fuer Werkstoffkunde of Universitaet Hannover and ENEA/Frascati. The results obtained in the standard experiments are rather similar, and the differences that appear can be explained by the various scales of the involved facilities (semi-industrial and laboratory) and by some particularities in the cutting parameters (an additional secondary gas flow of oxygen in plasma cutting at Universitaet Hannover, for example)

Measurements of secondary emissions from plasma arc and laser cutting in standard experiments

International Nuclear Information System (INIS)

Pilot, G.; Noel, M.; Leautier, R.; Steiner, H.; Tarroni, G.; Waldie, B.

1990-01-01

As part of an inter-facility comparison of secondary emissions from plasma-arc and laser cutting techniques, standard cutting tests have been done by plasma arc underwater and in air and laser beam in air. The same team, CEA/DPT/SPIN, was commissioned to measure the secondary emissions (solid and gaseous) in each contractor's facility with the same measuring rig. 20 mm and 40 mm thick grade 304 stainless steel plates were cut by plasma-torch in three different facilities: Heriot Watt University of Edinburgh, Institute fuer Werkstoffkunde of Hannover and CEA/CEN Cadarache. 10 mm and sometimes 20 mm thick grade 304 stainless steel plates were cut by laser beam in four different facilities: CEA/CEN Fontenay, CEA/CEN Saclay, Institute fuer Werkstoffkunde of Hannover and ENEA/FRASCATI. The results obtained in the standard experiments are rather similar, the differences that appear can be explained by the various scales of the facilities (semi-industrial and laboratory scale) and by some particularity in the cutting parameters (additional secondary gas flow of oxygen in plasma cutting at Hannover for example). Some supplementary experiments show the importance of some cutting parameters. (author)

Yield calculations for a facility for short-lived nuclear beams

CERN Document Server

Jiang, C L; Gomes, I; Heinz, A M; Nolen, Jerry A; Rehm, K E; Savard, G; Schiffer, J P

2002-01-01

Yields for a broad range of radioactive nuclei produced by spallation reactions, neutron-induced fission, in-flight projectile fragmentation and in-flight fission have been calculated for beams of stable nuclei at energies of 100-1000 MeV/u. Calculations of cross-sections and yields, attenuation effects due to absorption, production from secondary reactions, and transport efficiencies for mass selection are discussed. Rare isotope yields as functions of bombarding energies for both reaccelerated and directly produced fast-fragmentation beams are presented. This information provides a foundation for a cost-effective design of a next generation rare isotope accelerator.

Study of absorbed dose distribution to high energy electron beams

International Nuclear Information System (INIS)

Cecatti, E.R.

1983-01-01

The depth absorbed dose distribution by electron beams was studied. The influence of the beam energy, the energy spread, field size and design characteristics of the accelerator was relieved. Three accelerators with different scattering and collimation systems were studied leading todifferent depth dose distributions. A theoretical model was constructed in order to explain the increase in the depth dose in the build-up region with the increase of the energy. The model utilizes a three-dimensional formalism based on the Fermi-Eyges multiple scattering theory, with the introduction of modifications that takes into account the criation of secondary electrons. (Author) [pt

arXiv Mapping the material in the LHCb vertex locator using secondary hadronic interactions

CERN Document Server

INSPIRE-00160626; Barter, W.; Bay, A.; Bel, L.J.; van Beuzekom, M.; Bogdanova, G.; Borghi, S.; Bowcock, T.J.V.; Buchanan, E.; Buytaert, J.; Carvalho Akiba, K.; Chen, S.; Coco, V.; Collins, P.; Crocombe, A.; Da Cunha Marinho, F.; Dall'Occo, E.; De Capua, S.; Dean, C.T.; Dettori, F.; Dossett, D.; Dreimanis, K.; Dujany, G.; Eklund, L.; Evans, T.; Ferro-Luzzi, M.; Gersabeck, M.; Gershon, T.; Hadavizadeh, T.; Harrison, J.; Hennessy, K.; Hulsbergen, W.; Hutchcroft, D.; Ilten, P.; Jans, E.; John, M.; Kopciewicz, P.; Koppenburg, P.; Lafferty, G.; Latham, T.; Leflat, A.; Majewski, M.W.; McNulty, R.; Mylroie-Smith, J.; Oblakowska-Mucha, A.; Parkes, C.; Pearce, A.; Poluektov, A.; Pritchard, A.; Qian, W.; Redford, S.; Richards, S.; Rinnert, K.; Rodrigues, E.; Sarpis, G.; Schiller, M.; Schindler, H.; Smith, M.; Smith, N.A.; Szumlak, T.; Velthuis, J.J.; Volkov, V.; Wallace, C.; Wark, H.M.; Webber, A.; Williams, M.R.J.; Williams, M.

2018-06-13

Precise knowledge of the location of the material in the LHCb vertex locator (VELO) is essential to reducing background in searches for long-lived exotic particles, and in identifying jets that originate from beauty and charm quarks. Secondary interactions of hadrons produced in beam-gas collisions are used to map the location of material in the VELO. Using this material map, along with properties of a reconstructed secondary vertex and its constituent tracks, a $p$-value can be assigned to the hypothesis that the secondary vertex originates from a material interaction. A validation of this procedure is presented using photon conversions to dimuons.

Propagation of a nonrelativistic electron beam in a plasma in a magnetic field

International Nuclear Information System (INIS)

Okuda, H.; Horton, R.; Ono, M.; Ashour-Abdalla, M.

1987-01-01

Propagation of a nonrelativistic electron beam in a plasma in a strong magnetic field has been studied using electrostatic one-dimensional particle simulation models. Electron beams of finite pulse length and of continuous injection are followed in time to study the effects of beam--plasma interaction on the beam propagation. For the case of pulsed beam propagation, it is found that the beam distribution rapidly spreads in velocity space generating a plateaulike distribution with a high energy tail extending beyond the initial beam velocity. This rapid diffusion takes place within a several amplification length of the beam--plasma instability given by (ω/sub p/ω 2 /sub b/) -1 /sup // 3 V 0 , where ω/sub p/, ω/sub b/, and V 0 are the target plasma, beam--plasma frequencies, and the beam drift speed. This plateaulike distribution, however, becomes unstable as the high energy tail electrons free-stream, generating a secondary beam. A similar process is observed to take place for the case of continuous beam injection when the beam density is small compared with the total density n/sub b//n/sub t/<1. In particular, the electron velocity distribution is found monotonically decreasing in energy, having a high energy tail whose energy reaches twice the initial beam energy. Such an electron distribution is also seen in laboratory experiments and in computer simulations performed for a uniform, periodic system

Measurement of charged particle yields from therapeutic beams in view of the design of an innovative hadrontherapy dose monitor

CERN Document Server

Battistoni, G; Bini, F; Collamati, F; Collini, F; De Lucia, E; Durante, M; Faccini, R; Ferroni, F; Frallicciardi, P M; La Tessa, C; Marafini, M; Mattei, I; Miraglia, F; Morganti, S; Ortega, P G; Patera, V; Piersanti, L; Pinci, D; Russomando, A; Sarti, A; Schuy, C; Sciubba, A; Senzacqua, M; Solfaroli Camillocci, E; Vanstalle, M; Voena, C

2015-01-01

Particle Therapy (PT) is an emerging technique, which makes use of charged particles to efficiently cure different kinds of solid tumors. The high precision in the hadrons dose deposition requires an accurate monitoring to prevent the risk of under-dosage of the cancer region or of over-dosage of healthy tissues. Monitoring techniques are currently being developed and are based on the detection of particles produced by the beam interaction into the target, in particular: charged particles, result of target and/or projectile fragmentation, prompt photons coming from nucleus de-excitation and back-to-back γ s, produced in the positron annihilation from β + emitters created in the beam interaction with the target. It has been showed that the hadron beam dose release peak can be spatially correlated with the emission pattern of these secondary particles. Here we report about secondary particles production (charged fragments and prompt γ s) performed at different beam and energies that have a particular relevan...

High resolution silicon detectors for colliding beam physics

International Nuclear Information System (INIS)

Amendolia, S.R.; Bedeschi, F.; Bertolucci, E.; Bettoni, D.; Bosisio, L.; Bottigli, U.; Bradaschia, C.; Dell'Orso, M.; Fidecaro, F.; Foa, L.; Focardi, E.; Giannetti, P.; Giorgi, M.A.; Marrocchesi, P.S.; Menzione, A.; Raso, G.; Ristori, L.; Scribano, A.; Stefanini, A.; Tenchini, R.; Tonelli, G.; Triggiani, G.

1984-01-01

Resolution and linearity of the position measurement of Pisa multi-electrode silicon detectors are presented. The detectors are operated in slightly underdepleted mode and take advantage of their intrinsic resistivity for resistive charge partition between adjacent strips. 22 μm resolution is achieved with readout lines spaced 300 μm. Possible applications in colliding beam experiments for the detection of secondary vertices are discussed. (orig.)

Status report on the relativistic electron beam technology

International Nuclear Information System (INIS)

Iyyengar, S.K.; Ron, P.H.; Rohatgi, V.K.

1974-01-01

The status of technology of the pulsed relativistic electron beam (REB) has been examined and summarised in this report. With the present technology the beam generator can be used either as a source of intense electron burst or to produce bursts of positive ions x and γ-rays, and neutrons by suitable secondary reactions. A large number of applications have been identified where this technology can play an important role. Typical applications of the technology include : (a) generation and heating of fusion plasma (b) development of high power laser and (c) sterilisation and radiation sources. The present day cost of radiation produced by REB is competitive with the cost of radiation produced from Co 60 source. At the same time there are indications that the cost of radiation from REB source can be significantly reduced with advanced technology. The type of equipment developed by various laboratories to study realitivistic electron beams is also included in this report. (author)

Ionization Chambers for the LHC Beam Loss Detection

CERN Document Server

Assmann, R W; Ferioli, G; Gschwendtner, E; Kain, V

2003-01-01

At the Large Hadron Collider (LHC) a beam loss system will be used to prevent and protect superconducting magnets against coil quenches and coil damages. Ionisation chambers will be mounted outside the cryostat to measure the secondary shower particles caused by lost beam particles. Since the stored particle beam intensity is eight orders of magnitude larger than the lowest quench level and the losses should be detected with a relative error of two, the design and the location of the detectors have to be optimised. For that purpose a two-fold simulation was carried out. The longitudinal loss locations of the tertiary halo is investigated by tracking the halo through several magnet elements. These loss distributions are combined with simulations of the particle fluence outside the cryostat, which is induced by lost protons at the vacuum pipe. The base-line ionisation chamber has been tested at the PS Booster in order to determine the detector response at the high end of the dynamic range.

Secondary emissions during fiber laser cutting of nuclear material

Energy Technology Data Exchange (ETDEWEB)

Lopez, A., E-mail: beatriz.mendes.lopez@gmail.com [IDMEC, Instituto Superior Técnico, Universidade de Lisboa, Lisboa (Portugal); Assunção, E. [IDMEC, Instituto Superior Técnico, Universidade de Lisboa, Lisboa (Portugal); European Federation for Welding, Joining and Cutting, Porto Salvo 2740-120 (Portugal); Pires, I. [IDMEC, Instituto Superior Técnico, Universidade de Lisboa, Lisboa (Portugal); Quintino, L. [IDMEC, Instituto Superior Técnico, Universidade de Lisboa, Lisboa (Portugal); European Federation for Welding, Joining and Cutting, Porto Salvo 2740-120 (Portugal)

2017-04-15

The laser process has been studied for dismantling work for more than 10 years, however there is almost no data available concerning secondary emissions generated during the process. These emissions are inevitable during the laser cutting process and can have detrimental effects in human health and in the equipment. In terms of safety, for nuclear decommissioning, is crucial to point out ways of controlling the emissions of the process. This paper gives indications about the parameters to be used in order to reduce these secondary emissions and about the influence of these parameters on the particles size distribution. In general, for producing minimal dross and fume emissions the beam focus should be placed on the surface of the material. The higher percentage of secondary emissions which present higher diameter, increases approximately linearly with the stand-off distance and with the use of low air pressure.

On the absorbed dose determination method in high energy photon beams

International Nuclear Information System (INIS)

Scarlat, F.; Scarisoreanu, A.; Oane, M.; Mitru, E.; Avadanei, C.

2008-01-01

The absorbed dose determination method in water, based on standards of air kerma or exposure in high energy photon beams generated by electron with energies in the range of 1 MeV to 50 MeV is presented herein. The method is based on IAEA-398, AAPM TG-51, DIN 6800-2, IAEA-381, IAEA-277 and NACP-80 recommendations. The dosimetry equipment is composed of UNIDOS T 10005 electrometer and different ionization chambers calibrated in air kerma method in a Co 60 beam. Starting from the general formalism showed in IAEA-381, the determination of absorbed dose in water, under reference conditions in high energy photon beams, is given. This method was adopted for the secondary standard dosimetry laboratory (SSDL) in NILPRP-Bucharest

Secondary emission ion analyzer provided with an electron gun for insulating material analysis

International Nuclear Information System (INIS)

Blanchard, Bruno; Carrier, Patrick; Marguerite, J.-L.; Rocco, J.-C.

1976-01-01

This invention relates to a secondary emission ion analyser, fitted with an electron gun. It is used in the mass spectrometry analysis of electrically insulating bodies. It has already been suggested to bombard the target with an electron beam in conjunction with the beam of primary particles, in order to reduce the space charge near the target. The object of this invention is the application of this known process to appliances of the ion analyser type with a high electric field near the target. Its main characteristic is the use of an electron gun emitting an electron beam through the extraction lens placed opposite the target. The extraction electric field influences the path of the electrons but the electric and mechanical specifications of the electron gun in the invention are such that the target is correctly sprayed by the electron beam [fr

Ion beam probe diagnostic system. Technical progress report, 1 January 1979-30 June 1980. RPDL report No. 80-17

International Nuclear Information System (INIS)

Hickok, R.L.; Jennings, W.C.; Woo, J.T.; Connor, K.A.

1980-07-01

Tokomak plasmas suitable for diagnostic development were produced during this period in RENTOR following technological improvements in the vacuum chamber and discharge cleaning systems. Secondary ion signals were obtained from the heavy ion beam probe on RENTOR leading to initial estimates of the plasma space potential, which appears to vary by several hundred volts during the plasma pulse. The principle of measuring space potential in a minimum-B geometry was established using an ion gun mounted at the center of the ALEX baseball coil. The neutral beam probe was installed for measuring the space potential using actual secondary ion signals from a hollow cathode arc in ALEX and preliminary tests have begun. The ion beam test stand was significantly altered to allow more flexibility in testing energy analyzers, ion guns, and ion focusing concepts

Beam-Beam Interaction Studies at LHC

CERN Document Server

Schaumann, Michaela; Alemany Fernandez, R

2011-01-01

The beam-beam force is one of the most important limiting factors in the performance of a collider, mainly in the delivered luminosity. Therefore, it is essential to measure the effects in LHC. Moreover, adequate understanding of LHC beam-beam interaction is of crucial importance in the design phases of the LHC luminosity upgrade. Due to the complexity of this topic the work presented in this thesis concentrates on the beam-beam tune shift and orbit effects. The study of the Linear Coherent Beam-Beam Parameter at the LHC has been determined with head-on collisions with small number of bunches at injection energy (450 GeV). For high bunch intensities the beam-beam force is strong enough to expect orbit effects if the two beams do not collide head-on but with a crossing angle or with a given offset. As a consequence the closed orbit changes. The closed orbit of an unperturbed machine with respect to a machine where the beam-beam force becomes more and more important has been studied and the results are as well ...

Collective effects and experimental verification of the CLIC drive beam and decelerator

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00418229; Stapnes, Steinar; Adli, Erik

The Compact Linear Collider (CLIC) is a potential next-generation particle collider, in which electrons and positrons collide at a center-of-mass energy of up to 3 TeV. In order to reach a high accelerating gradient and reduce the length of the machine, CLIC uses a novel two-beam scheme. Here, the acceleration energy for the main beam is provided by energy extraction from a secondary electron drive beam, by the use of Power Extraction and Transfer Structures (PETS). This Ph.D. thesis describes deceleration measurements from the CLIC Test Facility 3 at CERN, from a beam that had up to 37 % of its kinetic energy converted into 12 GHz rf power. The results are part of the feasibility demonstration of the CLIC scheme. The measured difference in beam energy of the decelerated beam is correlated with particle tracking simulations and with predictions based on analytical formulae, and a very good agreement is demonstrated. The evolution of the transverse emittance was also studied, since it is critical to contain th...

Collision dynamics of methyl radicals and highly vibrationally excited molecules using crossed molecular beams

International Nuclear Information System (INIS)

Chu, P.M.Y.

1991-10-01

The vibrational to translational (V→T) energy transfer in collisions between large highly vibrationally excited polyatomics and rare gases was investigated by time-of-flight techniques. Two different methods, UV excitation followed by intemal conversion and infrared multiphoton excitation (IRMPE), were used to form vibrationally excited molecular beams of hexafluorobenzene and sulfur hexafluoride, respectively. The product translational energy was found to be independent of the vibrational excitation. These results indicate that the probability distribution function for V→T energy transfer is peaked at zero. The collisional relaxation of large polyatomic molecules with rare gases most likely occurs through a rotationally mediated process. Photodissociation of nitrobenzene in a molecular beam was studied at 266 nm. Two primary dissociation channels were identified including simple bond rupture to produce nitrogen dioxide and phenyl radical and isomerization to form nitric oxide and phenoxy radical. The time-of-flight spectra indicate that simple bond rupture and isomerization occurs via two different mechanisms. Secondary dissociation of the phenoxy radicals to carbon monoxide and cyclopentadienyl radicals was observed as well as secondary photodissociation of phenyl radical to give H atom and benzyne. A supersonic methyl radical beam source is developed. The beam source configuration and conditions were optimized for CH 3 production from the thermal decomposition of azomethane. Elastic scattering of methyl radical and neon was used to differentiate between the methyl radicals and the residual azomethane in the molecular beam

Beam test of Cherenkov counter prototype for ZDF setup

International Nuclear Information System (INIS)

Kacharava, A.K.; Macharashvili, G.G.; Nioradze, M.S.; Komarov, V.I.; Sopov, V.S.; Chernyshev, V.P.

1995-01-01

We describe a Cherenkov counter of total internal reflection for particle separation in the momentum range where all types of particles radiate Cherenkov light. The Cherenkov counter prototype with the lucite radiator was tested on the secondary beam of the ITEP (Moscow) accelerator. Dependence of the photomultiplier pulse height on the particle entrance angle was clearly observed. 4 refs., 4 figs

Results of the studies on energy deposition in IR6 superconducting magnets from continuous beam loss on the TCDQ system

CERN Document Server

Bracco, C; Presland, A; Redaelli, S; Sarchiapone, L; Weiler, T

2007-01-01

A single sided mobile graphite diluter block TCDQ, in combination with a two-sided secondary collimator TCS and an iron shield TCDQM, will be installed in front of the superconducting quadrupole Q4 magnets in IR6, in order to protect it and other downstream LHC machine elements from destruction in the event of a beam dump that is not synchronised with the abort gap. The TCDQ will be positioned close to the beam, and will intercept the particles from the secondary halo during low beam lifetime. Previous studies (1-4) have shown that the energy deposited in the Q4 magnet coils can be close to or above the quench limit. In this note the results of the latest FLUKA energy deposition simulations for Beam 2 are described, including an upgrade possibility for the TCDQ system with an additional shielding device. The results are discussed in the context of the expected performance levels for the different phases of LHC operation.

Electron beam propagation in the ion focused regime (IFR) with the experimental test accelerator (ETA)

International Nuclear Information System (INIS)

Struve, K.W.; Lauer, E.J.; Chambers, F.W.

1983-01-01

The IFR is a well-known stable, low pressure (0.10 to 0.120 torr in air) propagation window. Secondary electrons created by collisions of beam electrons with gas atoms are rapidly expelled by the strong radial electric field of the beam charge. The ions that remain inside the beam partially neutralize the electric field, allowing magnetic pinch forces to focus the beam. Experiments with the ETA beam have re-verified this stable window and are reported. Image forces from a close wall IFR propagation tank are also experimentally shown to center the beam and damp transverse oscillations. Results of experiments using 5 and 15 cm dia beam tubes are reported. For p tau > 2 torr-nsec (gas pressure x time into pulse the beam charge becomes completely neutralized by the ions, allowing a build up of plasma and resultant beam-plasma instabilities. The onset of these instabilities has been measured using rf pickup loops (0 to 2 GHz) and microwave detectors (6 to 40 GHz), and are also reported

Beam-beam phenomenology

International Nuclear Information System (INIS)

Teng, L.C.

1980-01-01

In colliding beam storage rings the beam collision regions are generally so short that the beam-beam interaction can be considered as a series of evenly spaced non-linear kicks superimposed on otherwise stable linear oscillations. Most of the numerical studies on computers were carried out in just this manner. But for some reason this model has not been extensively employed in analytical studies. This is perhaps because all analytical work has so far been done by mathematicians pursuing general transcendental features of non-linear mechanics for whom this specific model of the specific system of colliding beams is too parochial and too repugnantly physical. Be that as it may, this model is of direct interest to accelerator physicists and is amenable to (1) further simplification, (2) physical approximation, and (3) solution by analogy to known phenomena

Slow neutrons and secondary gamma ray distributions in concrete shields followed by reflecting layers

International Nuclear Information System (INIS)

Makarious, A.S.; Swilem, Y.I.; Awwad, Z.; Bayomy, T.

1993-01-01

Slow neutrons and secondary gamma ray distributions in concrete shields with and without a reflecting layer behind layer behind the concrete shield have been investigated first in case of using a bare reactor beam and then on using a B-4 C filtered beam. The total and capture secondary gamma ray coefficient (B gamma and B gamma C ), the ratio of the reflected thermal neutron (gamma) the ratio of the secondary gamma rays caused by reflected neutrons to those caused transmitted neutrons (Th I gamma/F I gamma) and the effect of inserting a blocking layer (a B-4 C layer) between the concrete shield and the reflector on the suppression of the produced secondary gamma rays have been investigated. It was found that the presence of the reflector layer behind the concrete shield reflects some thermal neutrons back to the concrete shields and so it increases the number of thermal neutrons at the interface between the concrete shield and the reflector. Also the capture secondary gamma rays was increased at the interface between the two medii due to the capture of the reflected thermal neutrons in the concrete shields. It was shown that B-gamma is higher than and that B g amma B gamma C and I gamma T h/ I gamma i f for the different concrete types is higher in case of using the graphite reflector than that in using either water or paraffin reflectors. Putting a blocking layer (B 4 C layer) between the concrete shield and the reflector decreases the produced secondary gamma rays due to the absorption of the reflected thermal neutrons. 17 figs

Spatial resolution test of a beam diagnostic system for DESIREE

Science.gov (United States)

Das, Susanta; Kallberg, A.

2010-11-01

A diagnostic system based on the observation of low energy ( ˜ 10 eV) secondary electrons (SE) produced by a beam, striking a metallic foil has been built to monitor and to cover the wide range of beam intensities and energies for Double ElectroStatic Ion Ring ExpEriment [1,2].The system consists of a Faraday cup to measure the beam current, a collimator with circular apertures of different diameters to measure the spatial resolution of the system, a beam profile monitoring system (BPMS), and a control unit. The BPMS, in turn, consists of an aluminim (Al) foil, a grid placed in front of the Al foil to accelerate the SE, position sensitive MCP, fluorescent screen, and a CCD camera to capture the images. The collimator contains a set of circular holes of different diameters and separations (d) between them. The collimator cuts out from the beam areas equal to the holes with separation d mm between the beams centers and creates well separated (distinguishable) narrow beams of approximately same intensity close to each other. A 10 keV proton beam was used. The spatial resolution of the system was tested for different Al plate and MCP voltages and resolution of better than 2 mm was achieved. Ref.: 1. K. Kruglov {et al}., NIM A 441 (2000) 595; 701 (2002) 193c, 2. MSL and Atomic Physics, Stockholm Univ.(www.msl.se, http://www.atom.physto.se/Cederquist/desiree/web/hc.html).

Radar observations of the overdense ionospheric ionization created by the artificial electron beam in the 'Zarnitza-2' experiment

International Nuclear Information System (INIS)

Zhulin, I.A.; Kustov, A.V.; Uspensky, M.V.; Miroshnikova, T.V.

1980-01-01

This work contains an analysis of experimental radar data obtained in the 'Zarnitza-2' experiment when the artificial electron beam was injected into the ionosphere below 100 km. The signals observed just after switching off the electron gun are interpreted as radio echoes of overdense secondary ionization produced by the beam. The size of the secondary ionization torch is estimated and distributions of ionization over the cross-section of the torch are calculated and represented at different time moments, taking into account the motion of the rocket. The azimuth dependence of the echo amplitudes is discussed. The obtained Doppler velocity distribution can be interpreted as a height profile of ionospheric winds

Beam Collimation and Machine-Detector Interface at the International Linear Collider

CERN Document Server

Mokhov, Nikolai V; Kostin, Mikhail A

2005-01-01

Synchrotron radiation, spray from the dumps and extraction lines, beam-gas and beam halo interactions with collimators and other components in the ILC beam delivery system create fluxes of muons and other secondaries which can exceed the tolerable levels at a detector by a few orders of magnitude. It is shown that with a multi-stage collimation system, magnetized iron spoilers which fill the tunnel and a set of masks in the detector, one can hopefully meet the design goals. Results of modeling with the STRUCT and MARS15 codes of beam loss and energy deposition effects are presented in this paper. We concentrate on collimation system and mask design and optimization, short- and long-term survivability of the critical components (spoilers, absorbers, magnets, separators, dumps), dynamic heat loads and radiation levels in magnets and other components, machine-related backgrounds and damage in collider detectors, and environmental aspects (prompt dose, ground-water and air activation).

Ultra-shallow arsenic implant depth profiling using low-energy nitrogen beams

International Nuclear Information System (INIS)

Fearn, Sarah; Chater, Richard; McPhail, David

2004-01-01

Sputtering of silicon by low-energy nitrogen primary ion beams has been studied by a number of authors to characterize the altered layer, ripple formation and the sputtered yields of secondary ions [Surf. Sci. 424 (1999) 299; Appl. Phys. A: Mater. Sci. Process 53 (1991) 179; Appl. Phys. Lett. 73 (1998) 1287]. This study examines the application of low-energy nitrogen primary ion beams for the possible depth profiling of ultra-shallow arsenic implants into silicon. The emphasis of this work is on the matrix silicon signals in the pre-equilibrium surface region that are used for dose calibration. Problems with these aspects of the concentration depth profiling can give significant inconsistencies well outside the error limits of the quoted dose for the arsenic implantation as independently verified by CV profiling. This occurs during depth profiling with either oxygen primary ion beams (with and without oxygen leaks) or cesium primary ion beams

A symplectic coherent beam-beam model

International Nuclear Information System (INIS)

Furman, M.A.

1989-05-01

We consider a simple one-dimensional model to study the effects of the beam-beam force on the coherent dynamics of colliding beams. The key ingredient is a linearized beam-beam kick. We study only the quadrupole modes, with the dynamical variables being the 2nd-order moments of the canonical variables q, p. Our model is self-consistent in the sense that no higher order moments are generated by the linearized beam-beam kicks, and that the only source of violation of symplecticity is the radiation. We discuss the round beam case only, in which vertical and horizontal quantities are assumed to be equal (though they may be different in the two beams). Depending on the values of the tune and beam intensity, we observe steady states in which otherwise identical bunches have sizes that are equal, or unequal, or periodic, or behave chaotically from turn to turn. Possible implications of luminosity saturation with increasing beam intensity are discussed. Finally, we present some preliminary applications to an asymmetric collider. 8 refs., 8 figs

Dosimetry at the location of secondary tumors after radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Baas, H W; Davelaar, J J; Broerse, J J; Noordijk, E M [University Hospital, Leiden (Netherlands). Dept. of Clinical Oncology

1995-12-01

After a latency period of many years the incidence of a secondary tumor is considered a serious late effect of radiotherapy. Analysis of about 200 patients, treated by radiotherapy for Hodgkin`s disease in our hospital, shows an actuarial risk for the incidence of a secondary tumor of about 7% after 10 years. The chance of tumor induction depends on the dose at the location of the tumor and therefore a good dose estimation is mandatory. Radiotherapy was given with Co-60 in the early years and with linear accelerators thereafter, exposing the target areas to 36 - 40 Gy. For dose estimations at the penumbra and outside the beam, where tumor incidence is expected to be high, we used a.o. Monte Carlo calculations. We developed an EGS4 computer simulation for a treatment beam from a linear accelerator irradiating a mathematical phantom representing the patient geometry (GSF ADAM phantom). The isodose curves at certain energies were obtained for a water phantom and fitted quite well with measurements. In addition to Monte Carlo calculations we also used existing treatment planning systems. The dose estimations of a number of patients and the derived risk per unit of dose, which is important for both radiotherapy as well as radiation protection in general, is discussed.

Neutron flux density and secondary-particle energy spectra at the 184-inch synchrocyclotron medical facility

International Nuclear Information System (INIS)

Smith, A.R.; Schimmerling, W.; Henson, A.M.; Kanstein, L.L.; McCaslin, J.B.; Stephens, L.D.; Thomas, R.H.; Ozawa, J.; Yeater, F.W.

1978-07-01

Helium ions, with an energy of 920 MeV, produced by the 184-inch synchrocyclotron of the Lawrence Berkeley Laboratory are now being used in a pilot series to determine their efficacy in the treatment of tumors of large volume. The techniques for production of the large uniform radiation fields required for these treatments involve the use of beam-limiting collimators and energy degraders. Interaction of the primary beam with these beam components produces secondary charged particles and neutrons. The sources of neutron production in the beam transport system of the alpha-particle beam have been identified and their magnitudes have been determined. Measurements with activation detectors and pulse counters of differing energy responses have been used to determine secondary particle spectra at various locations on the patient table. These spectra are compared to a calculation of neutron production based on best estimates derived from published cross sections. Agreement between the calculated spectra and those derived from experimental measurements is obtained (at the 10 to 20% level) when the presence of charged particles is taken into account. The adsorbed dose in soft tissue is not very sensitive to the shape of the incident neutron energy spectrum, and the values obtained from unfolding the experimental measurements agree with the values obtained from the calculated spectra within the estimated uncertainty of +-25%. These values are about 3 x 10 -3 rad on the beam axis and about 1 x 10 -3 rad at 20 cm or more from the beam axis, per rad deposited by the incident alpha-particle beam. Estimates of upper limit dose to the lens of the eye and red bone marrow are approximately 10 rad and approximately 1 rad, respectively, for a typical treatment plan. The absorbed dose to the lens of the eye is thus well below the threshold value for cataractogenesis estimated for fission neutrons. An upper limit for the risk of leukemia is estimated to be approximately 0.04%

Part 1: characterization of beam synthesized catalytic materials. Part 2: further development of molecular SIMS

International Nuclear Information System (INIS)

Scheifers, S.M.

1985-01-01

Part I of this thesis concerns characterization of catalyst materials prepared by an ion beam implanter and by a multiple expansion cluster source. Ion beam synthesis was carried out on a 250-kev ion implanter. After assembling a special reaction chamber, zeolites were implanted with phosphorous and iron. This work contributed to development of a sputter reactor for ion beam synthesis. Silver catalysts were examined in a reactor designed, built and evaluated for catalysts produced by the sputter reactor and by a multiple expansion cluster source. Small surface area silver foil catalysts and silver cluster catalysts showed kinetic activity for epoxidation of ethylene. Positive results for the small surface area silver cluster catalyst demonstrate the feasibility of studying these catalysts with the special reactor. Part 2 concerns fundamentals and applications of secondary ion mass spectrometry. A data system was implemented for a secondary ion mass spectrometer that involved design and construction of a computer interface. Software routines for the interface were written in assembly language for increased operation efficiency

Beam halo in high-intensity beams

International Nuclear Information System (INIS)

Wangler, T.P.

1993-01-01

In space-charge dominated beams the nonlinear space-charge forces produce a filamentation pattern, which in projection to the 2-D phase spaces results in a 2-component beam consisting of an inner core and a diffuse outer halo. The beam-halo is of concern for a next generation of cw, high-power proton linacs that could be applied to intense neutron generators for nuclear materials processing. The author describes what has been learned about beam halo and the evolution of space-charge dominated beams using numerical simulations of initial laminar beams in uniform linear focusing channels. Initial results are presented from a study of beam entropy for an intense space-charge dominated beam

Transient Thermo-Mechanical Analysis of the TPSG4 Beam Diluter

CERN Document Server

Goddard, B; Herrera-Martínez, A; Kadi, Y; Marque, S

2002-01-01

A new extraction channel is being built in the Super Proton Synchrotron (SPS) Long Straight Section 4 (LSS4) to transfer proton beams to the Large Hadron Collider (LHC) and also to the CERN Neutrino to Gran Sasso (CNGS) target. The beam is extracted in a fast mode during a single turn. For this purpose a protection of the MSE copper septum coil, in the form of a beam diluting element placed upstream, will be required to cope with the new failure modes associated with the fast extraction operation. The present analysis focuses on the thermo-mechanical behavior of the proposed TPSG4 diluter element irradiated by a fast extracted beam (up to 4.9 x 10^13 protons per 7.2 mus pulse) from the SPS. The deposited energy densities, estimated from primary and secondary particle simulations using the high-energy particle transport code FLUKA, were converted to internal heat generation rates taken as a thermal load input for the finite-element engineering analyses code ANSYS. According to the time dependence of the extrac...

Implementation of depolarization due to beam-beam effects in the beam-beam interaction simulation tool GUINEA-PIG++

Science.gov (United States)

Rimbault, C.; Le Meur, G.; Blampuy, F.; Bambade, P.; Schulte, D.

2009-12-01

Depolarization is a new feature in the beam-beam simulation tool GUINEA-PIG++ (GP++). The results of this simulation are studied and compared with another beam-beam simulation tool, CAIN, considering different beam parameters for the International Linear Collider (ILC) with a centre-of-mass energy of 500 GeV.

Influence of e-Beam Irradiation on the Performance of Energy Storage and Conversion Electrode

Energy Technology Data Exchange (ETDEWEB)

Baeok, Sung Hyeon; Jo, Won Jun; Lee, Duwon; Lee, Myung An [Inha Univ., Incheon (Korea, Republic of); Shin, Joong Hyeok; Lee, Byung Cheol [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2013-07-01

Electron beam irradiation was known as an effective method to improve the stability and performance of electrodes by varying the chemical and physical properties. It has been reported that surface morphology, oxidation state, optical properties, and electrochemical properties can be modified by e-beam irradiation. In this work, influence of electron beam irradiation on the performance of electrode was studied for the applications in energy storage and conversion, such as secondary battery, supercapacitor, and fuel cell. Changes in physical and chemical properties of electrodes before and after e-beam irradiation were investigated. The crystallinity of the synthesized materials was investigated by X-ray diffraction, and the oxidation states were determined by X-ray photoelectron spectroscopy. Scanning electron microscopy was utilized to examine surface morphology. Crystallinity, surface morphology, and oxidation state were significantly changed by electron beam irradiation, and were found to be strongly dependent on irradiation time.

Ion beam characteristics of the controlatron/zetatron family of the gas filled neutron tubes

Energy Technology Data Exchange (ETDEWEB)

Berg, R.S.; Shope, L.A.; O' Neal, M.L.; Boers, J.E.; Bickes, R.W. Jr.

1981-03-01

A gas filled tube used to produce a neutron flux with the D(T,He/sup 4/)n reaction is described. Deuterium and tritium ions generated in a reflex discharge are extracted and accelerated to 100 keV by means of an accelerator electrode onto a deutero-tritide target electrode. The electrodes are designed to focus the ion beam onto the target. Total tube currents consisting of extracted ions, unsuppressed secondary electrons, and ions generated by interactions with the background gas are typically 100 mA. The characteristics of the extracted ion beam are discussed. Accelerating voltages greater than 50 kV are required to focus the beam through the accelerator aperture for configurations that give beams with the proper energy density onto the target. The perveance of the beam is discussed. Maximum perveance values are 2 to 20 nanopervs. Tube focusing and neutron production characteristics are described.

Beam-plasma instability in ion beam systems used in neutral beam generation

International Nuclear Information System (INIS)

Hooper, E.B. Jr.

1977-02-01

The beam-plasma instability is analyzed for the ion beams used for neutral beam generation. Both positive and negative ion beams are considered. Stability is predicted when the beam velocity is less than the electron thermal velocity; the only exception occurs when the electron density accompanying a negative ion beam is less than the ion density by nearly the ratio of electron to ion masses. For cases in which the beam velocity is greater than the electron thermal velocity, instability is predicted near the electron plasma frequency

Low-energy positron and electron diffraction and positron-stimulated secondary electron emission from Cu(100)

International Nuclear Information System (INIS)

Weiss, A.H.

1983-01-01

The results of two series of experiments are reported. In the first, an electrostatically guided beam of low-energy (40-400 eV) positrons, delta/sub p/ was used to study low-energy positron diffraction (LEPD) from a Cu(100) surface under ultrahigh-vacuum conditions. Low-energy electron diffraction (LEED) data were obtained from the same sample in the same apparatus. Comparison of LEPD and LEED intensity versus energy data with model calculations made using computer programs developed by C.B. Duke and collaborators indicated that: LEPD data is adequately modeled using potentials with no exchange-correlation term. The inelastic mean free path, lambda/sub ee/, is shorter for positrons than for electrons at low (< approx.80 eV). LEED is better than LEPD at making a determination of the first-layer spacing of Cu(100) for the particular data set reported. In the second set of experiments, the same apparatus and sample were used to compare positron- and electron-stimulated secondary-electron emission (PSSEE and ESSEE). The results were found to be consistent with existing models of secondary-electron production for metals. The energy distributions of secondary-electrons had broad low-energy (<10 eV) peaks for both positron and electron stimulation. But the PSEE distribution showed no elastic peak. Measurements of secondary-electron angular distributions, found to be cosine-like in both the PSSEE and ESSEE case, were used to obtain total secondary yield ratios, delta, at four beam energies ranging from 40-400 eV. The secondary yield ratio for primary positrons and the yield for primary electrons, delta/sub e/, were similar at these energies. For 400-eV primary particles the secondary yields were found to be delta/sub p/ = 0.94 +/- 0.12 and delta/sub e/ = 0.94 +/- 0./12, giving a ratio of unity for positron-stimulated secondary yield to electron-stimulated secondary yield

High-energy acceleration of an intense negative ion beam

International Nuclear Information System (INIS)

Takeiri, Y.; Ando, A.; Kaneko, O.

1995-02-01

A high-current H - ion beam has been accelerated with the two-stage acceleration. A large negative hydrogen ion source with an external magnetic filter produces more than 10 A of the H - ions from the grid area of 25cm x 50cm with the arc efficiency of 0.1 A/kW by seeding a small amount of cesium. The H - ion current increases according to the 3/2-power of the total beam energy. A 13.6 A of H - ion beam has been accelerated to 125 keV at the operational gas pressure of 3.4 mTorr. The optimum beam acceleration is achieved with nearly the same electric fields in the first and the second acceleration gaps on condition that the ratio of the first acceleration to the extraction electric fields is adjusted for an aspect ratio of the extraction gap. The ratio of the acceleration drain current to the H - ion current is more than 1.7. That is mainly due to the secondary electron generated by the incident H - ions on the extraction grid and the electron suppression grid. The neutralization efficiency was measured and agrees with the theoretical calculation result. (author)

Isomeric Targets and Beams

International Nuclear Information System (INIS)

Oganesyan, Yu.Ts.; Karamyan, S.A.

1994-01-01

One of the main topics of modern nuclear physics is the investigation of exotic nuclei including hyper-nuclei, trans fermium elements, proton and neutron rich isotopes near drip lines as well as high-spin excited states and states with anomalous deformation. The isomerism of nuclei is closely related with such phenomena as the alignment of single-particle orbitals, the coexistence of various deformations and the manifestation of intruder-levels from neighbouring shells. The investigation of electromagnetic and nuclear interactions of isomers could give important information on their shell structure and its role in the mechanism of nuclear reactions. For such experiments one can either make isomeric targets (sufficiently long-lived) or use the methods of acceleration of isomeric nuclei. Recently, an exotic 16 + four-quasiparticle isomer of 178 Hf m 2 was produced in a micro weight quantity and the first nuclear reactions on it were successfully observed. The talk describes these experiments as well as new ideas for the continuation of the studies and some advantageous ways for the isomeric beams production by the method of direct acceleration or by the secondary beam method. 35 refs., 15 figs., 8 tabs

Photon beam convolution using polyenergetic energy deposition kernels

International Nuclear Information System (INIS)

Hoban, P.W.; Murray, D.C.; Round, W.H.

1994-01-01

In photon beam convolution calculations where polyenergetic energy deposition kernels (EDKs) are used, the primary photon energy spectrum should be correctly accounted for in Monte Carlo generation of EDKs. This requires the probability of interaction, determined by the linear attenuation coefficient, μ, to be taken into account when primary photon interactions are forced to occur at the EDK origin. The use of primary and scattered EDKs generated with a fixed photon spectrum can give rise to an error in the dose calculation due to neglecting the effects of beam hardening with depth. The proportion of primary photon energy that is transferred to secondary electrons increases with depth of interaction, due to the increase in the ratio μ ab /μ as the beam hardens. Convolution depth-dose curves calculated using polyenergetic EDKs generated for the primary photon spectra which exist at depths of 0, 20 and 40 cm in water, show a fall-off which is too steep when compared with EGS4 Monte Carlo results. A beam hardening correction factor applied to primary and scattered 0 cm EDKs, based on the ratio of kerma to terma at each depth, gives primary, scattered and total dose in good agreement with Monte Carlo results. (Author)

Kinetic plasma simulation of ion beam extraction from an ECR ion source

International Nuclear Information System (INIS)

Elliott, S.M.; White, E.K.; Simkin, J.

2012-01-01

Designing optimized ECR (electron cyclotron resonance) ion beam sources can be streamlined by the accurate simulation of beam optical properties in order to predict ion extraction behavior. The complexity of these models, however, can make PIC-based simulations time-consuming. In this paper, we first describe a simple kinetic plasma finite element simulation of extraction of a proton beam from a permanent magnet hexapole ECR ion source. Second, we analyze the influence of secondary electrons generated by ion collisions in the residual gas on the space charge of a proton beam of a dual-solenoid ECR ion source. The finite element method (FEM) offers a fast modeling environment, allowing analysis of ion beam behavior under conditions of varying current density, electrode potential, and gas pressure. The new version of SCALA/TOSCA v14 permits the making of simulations in tens of minutes to a few hours on standard computer platforms without the need of particle-in-cell methods. The paper is followed by the slides of the presentation. (authors)

NA61/SHINE facility at the CERN SPS: beams and detector system

CERN Document Server

Abgrall, N.; Aduszkiewicz, A.; Ali, Y.; Anticic, T.; Antoniou, N.; Baatar, B.; Bay, F.; Blondel, A.; Blumer, J.; Bogomilov, M.; Bogusz, M.; Bravar, A.; Brzychczyk, J.; Bunyatov, S.A.; Christakoglou, P.; Czopowicz, T.; Davis, N.; Debieux, S.; Dembinski, H.; Diakonos, F.; Di Luise, S.; Dominik, W.; Drozhzhova, T.; Dumarchez, J.; Dynowski, K.; Engel, R.; Efthymiopoulos, I.; Ereditato, A.; Fabich, A.; Feofilov, G.A.; Fodor, Z.; Fulop, A.; Gazdzicki, M.; Golubeva, M.; Grebieszkow, K.; Grzeszczuk, A.; Guber, F.; Haesler, A.; Hasegawa, T.; Hierholzer, M.; Idczak, R.; Igolkin, S.; Ivashkin, A.; Jokovic, D.; Kadija, K.; Kapoyannis, A.; Kaptur, E.; Kielczewska, D.; Kirejczyk, M.; Kisiel, J.; Kiss, T.; Kleinfelder, S.; Kobayashi, T.; Kolesnikov, V.I.; Kolev, D.; Kondratiev, V.P.; Korzenev, A.; Koversarski, P.; Kowalski, S.; Krasnoperov, A.; Kurepin, A.; Larsen, D.; Laszlo, A.; Lyubushkin, V.V.; Maćkowiak-Pawlowska, M.; Majka, Z.; Maksiak, B.; Malakhov, A.I.; Maletic, D.; Manglunki, D.; Manic, D.; Marchionni, A.; Marcinek, A.; Marin, V.; Marton, K.; Mathes, H.J; Matulewicz, T.; Matveev, V.; Melkumov, G.L.; Messina, M.; Mrówczyński, St.; Murphy, S.; Nakadaira, T.; Nirkko, M.; Nishikawa, K.; Palczewski, T.; Palla, G.; Panagiotou, A.D.; Paul, T.; Peryt, W.; Petukhov, O.; Pistillo, C.; Planeta, R.; Pluta, J.; Popov, B.A.; Posiadala, M.; Puławski, S.; Puzovic, J.; Rauch, W.; Ravonel, M.; Redij, A.; Renfordt, R.; Richter-Was, E.; Robert, A.; Röhrich, D.; Rondio, E.; Rossi, B.; Roth, M.; Rubbia, A.; Rustamov, A.; Rybczyński, M.; Sadovsky, A.; Sakashita, K.; Savic, M.; Schmidt, K.; Sekiguchi, T.; Seyboth, P.; Sgalaberna, D.; Shibata, M.; Sipos, R.; Skrzypczak, E.; Słodkowski, M.; Sosin, Z.; Staszel, P.; Stefanek, G.; Stepaniak, J.; Stroebele, H.; Susa, T.; Szuba, M.; Tada, M.; Tereshchenko, V.; Tolyhi, T.; Tsenov, R.; Turko, L.; Ulrich, R.; Unger, M.; Vassiliou, M.; Veberic, D.; Vechernin, V.V.; Vesztergombi, G.; Vinogradov, L.; Wilczek, A.; Włodarczyk, Z.; Wojtaszek-Szwarz, A.; Wyszyński, O.; Zambelli, L.; Zipper, W.

2014-01-01

NA61/SHINE (SPS Heavy Ion and Neutrino Experiment) is a multi-purpose experimental facility to study hadron production in hadron-proton, hadron-nucleus and nucleus-nucleus collisions at the CERN Super Proton Synchrotron. It recorded the first physics data with hadron beams in 2009 and with ion beams (secondary 7Be beams) in 2011. NA61/SHINE has greatly profited from the long development of the CERN proton and ion sources and the accelerator chain as well as the H2 beamline of the CERN North Area. The latter has recently been modified to also serve as a fragment separator as needed to produce the Be beams for NA61/SHINE. Numerous components of the NA61/SHINE set-up were inherited from its predecessors, in particular, the last one, the NA49 experiment. Important new detectors and upgrades of the legacy equipment were introduced by the NA61/SHINE Collaboration. This paper describes the state of the NA61/SHINE facility - the beams and the detector system - before the CERN Long Shutdown I, which started in March ...

Studies of nuclei using radioactive beams

International Nuclear Information System (INIS)

Piercey, R.B.

1989-07-01

The 12 month period from May 1988 to July 1989 represents the first full year of our 18 month pilot program in nuclear structure research. In this period, research was initiated to develop a capability for radioactive secondary beams at Argonne National Laboratory using the Atlas and the new Fragment Mass Analyzer (FMA), which is currently under construction. Two major new detector facilities are currently in the final stages of design and testing. The Large-Area, Scintillator Telescope (LAST) detector is fully operational and will be shipped to Argonne National Laboratory in August for fit-tests and in-beam calibrations. The first segments of a new sixteen-segment neutron multiplicity detector have been built and tested. The remaining segments are currently being constructed. Research was continued in the areas of (1) Coulomb excitation studies of rare earth and actinide nuclei; (2) In-beam, gamma-ray spectroscopy of nuclei in the mass 100 region, and (3) Advanced detector design. Several journal articles and abstracts were published or submitted for publication in the reporting period, and others are currently in preparation. Three graduate students participated in the program, one from the University of Florida and two from the Royal Institute of Technology, Stockholm, Sweden

Production and use of radioactive nuclear beams

International Nuclear Information System (INIS)

Tanihata, Isao

1994-01-01

Two different production method of radioactive nuclear beams (RNB) are reviewed, in this paper. One is the secondary beam method that use a high-energy heavy-ion reaction and a separator and the other is the reacceleration method. The RNB is also expected to have following properties that are useful to the application in wider research and technical usage; 1. any elements and isotopes can be used as a beam. 2. it is easy to control a position and a depth of the implantation. 3. an extremely sensitive detection is possible because they emit radiations. 4. one can select the lifetime among the isotopes suitable for a specific phenomenon. 5. one can select a spin among the isotopes for specific selectivity to the phenomenon. These useful properties of the RNB and a few recent examples of study are discussed. Among them are the discovery of the neutron skin and the neutron halo in nuclei near the limit of existence, the first determinations of reactions relevant to the synthesis of the heavy elements in the universe, and an application to the PET. (J.P.N.)

Examination of Beryllium Under Intense High Energy Proton Beam at CERN's HiRadMat Facility

CERN Document Server

Ammigan, K.; Hurh, P.; Zwaska, R.; Atherton, A.; Caretta, O.; Davenne,T.; Densham, C.; Fitton, M.; Loveridge, P.; O'Dell, J.; Roberts, S.; Kuksenko, V.; Butcher, M.; Calviani, M.; Guinchard, M.; Losito, R.

2017-01-01

Beryllium is extensively used in various accelerator beam lines and target facilities as material for beam win- dows, and to a lesser extent, as secondary particle produc- tion targets. With increasing beam intensities of future ac- celerator facilities, it is critical to understand the response of beryllium under extreme conditions to avoid compro- mising particle production efficiency by limiting beam pa- rameters. As a result, the planned experiment at CERN’s HiRadMat facility will take advantage of the test facility’s tunable high intensity proton beam to probe and investigate the damage mechanisms of several grades of beryllium. The test matrix will consist of multiple arrays of thin discs of varying thicknesses as well as cylinders, each exposed to increasing beam intensities. Online instrumentations will acquire real time temperature, strain, and vibration data of the cylinders, while Post-Irradiation-Examination (PIE) of the discs will exploit advanced microstructural characteri- zation and imagin...

Examination of Beryllium Under Intense High Energy Proton Beam at CERN's HiRadMat Facility

CERN Document Server

Ammigan, K; Hurh, P; Zwaska, R; Atherton, A; Caretta, O; Davenne, t; Densham, C; Fitton, M; Loveridge, P; O'Dell, J; Roberts, S; Kuksenko, v; Butcher, M; Calviani, M; Guinchard, M; Losito, R

2015-01-01

Beryllium is extensively used in various accelerator beam lines and target facilities as material for beam win- dows, and to a lesser extent, as secondary particle produc- tion targets. With increasing beam intensities of future ac- celerator facilities, it is critical to understand the response of beryllium under extreme conditions to avoid compro- mising particle production efficiency by limiting beam pa- rameters. As a result, the planned experiment at CERN’s HiRadMat facility will take advantage of the test facility’s tunable high intensity proton beam to probe and investigate the damage mechanisms of several grades of beryllium. The test matrix will consist of multiple arrays of thin discs of varying thicknesses as well as cylinders, each exposed to increasing beam intensities. Online instrumentations will acquire real time temperature, strain, and vibration data of the cylinders, while Post-Irradiation-Examination (PIE) of the discs will exploit advanced microstructural characteri- zation and imagin...

Beam Techniques - Beam Control and Manipulation

International Nuclear Information System (INIS)

Minty, Michiko G

2003-01-01

We describe commonly used strategies for the control of charged particle beams and the manipulation of their properties. Emphasis is placed on relativistic beams in linear accelerators and storage rings. After a brief review of linear optics, we discuss basic and advanced beam control techniques, such as transverse and longitudinal lattice diagnostics, matching, orbit correction and steering, beam-based alignment, and linac emittance preservation. A variety of methods for the manipulation of particle beam properties are also presented, for instance, bunch length and energy compression, bunch rotation, changes to the damping partition number, and beam collimation. The different procedures are illustrated by examples from various accelerators. Special topics include injection and extraction methods, beam cooling, spin transport and polarization

Beam Techniques - Beam Control and Manipulation

Energy Technology Data Exchange (ETDEWEB)

Minty, Michiko G

2003-04-24

We describe commonly used strategies for the control of charged particle beams and the manipulation of their properties. Emphasis is placed on relativistic beams in linear accelerators and storage rings. After a brief review of linear optics, we discuss basic and advanced beam control techniques, such as transverse and longitudinal lattice diagnostics, matching, orbit correction and steering, beam-based alignment, and linac emittance preservation. A variety of methods for the manipulation of particle beam properties are also presented, for instance, bunch length and energy compression, bunch rotation, changes to the damping partition number, and beam collimation. The different procedures are illustrated by examples from various accelerators. Special topics include injection and extraction methods, beam cooling, spin transport and polarization.

Beam-beam studies for FCC-hh

CERN Document Server

AUTHOR|(CDS)2068329; Pieloni, Tatiana; Buffat, Xavier; Furuseth, Sondre Vik

2017-01-01

The Future Circular Collider hadron-hadron (FCC-hh) design study is currently exploring different IR design possibilities including round and flat optics or different crossing schemes. The present study intends to evaluate each scenario from the beam-beam effects point of view. In particular the single particle long term stability to maximize beam lifetimes and luminosity reach is used to quantify the differences. The impact of strong head on interactions on the beam quality and lifetime is addressed by means of GPU accelerated simulations code featuring a weak-strong 6-dimensional beam-beam interaction.

Dynamical chaos and beam-beam models

International Nuclear Information System (INIS)

Izrailev, F.M.

1990-01-01

Some aspects of the nonlinear dynamics of beam-beam interaction for simple one-dimensional and two-dimensional models of round and flat beams are discussed. The main attention is paid to the stochasticity threshold due to the overlapping of nonlinear resonances. The peculiarities of a round beam are investigated in view of using the round beams in storage rings to get high luminosity. 16 refs.; 7 figs

Beam, multi-beam and broad beam production with COMIC devices

International Nuclear Information System (INIS)

Sortais, P.; Lamy, T.; Medard, J.; Angot, J.; Peaucelle, C.

2012-01-01

The COMIC discharge cavity is a very versatile technology. We will present new results and devices that match new applications like: molecular beams, ultra compact beam line for detectors calibrations, quartz source for on-line application, high voltage platform source, sputtering /assistance broad beams and finally, a quite new use, high energy multi-beam production for surface material modifications. In more details, we will show that the tiny discharge of COMIC can mainly produce molecular ions (H 3+ ). We will present the preliminary operation of the fully quartz ISOLDE COMIC version, in collaboration with IPN Lyon, we will present a first approach for a slit extraction version of a three cavity device, and after discussing about various extraction systems on the multi discharge device (41 cavities) we will show the low energy broad beam (2 KV) and high energy multi-beams (10 beams up to 30 KV) productions. We will specially present the different extraction systems adapted to each application and the beams characteristics which are strongly dependent on the voltage distribution of an accel-accel two electrodes extraction system. The paper is followed by the slides of the presentation. (authors)

Workshop on Physics with Neutral Kaon Beam at JLab (KL2016) Mini-Proceedings

Energy Technology Data Exchange (ETDEWEB)

Strakovsky, Igor I. [George Washington Univ., Washington, DC (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Amaryan, Moskov [Old Dominion Univ., Norfolk, VA (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Chudakov, Eugene A. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Meyer, Curtis A. [Carnegie Mellon Univ., Pittsburgh, PA (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Pennington, Michael R. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Ritman, James L. [Forschungszentrum Juelich Institut fuer Kernphysik

2016-05-01

The KL2016 Workshop is following the Letter of Intent LoI12-15-001 "Physics Opportunities with Secondary KL beam at JLab" submitted to PAC43 with the main focus on the physics of excited hyperons produced by the Kaon beam on unpolarized and polarized targets with GlueX setup in Hall D. Such studies will broaden a physics program of hadron spectroscopy extending it to the strange sector. The Workshop was organized to get a feedback from the community to strengthen physics motivation of the LoI and prepare a full proposal.

Ultrahigh resolution focused electron beam induced processing: the effect of substrate thickness

DEFF Research Database (Denmark)

van Dorp, Willem F; Lazic, Ivan; Beyer, André

2011-01-01

It is often suggested that the growth in focused electron beam induced processing (FEBIP) is caused not only by primary electrons, but also (and even predominantly) by secondary electrons (SEs). If that is true, the growth rate for FEBIP can be changed by modifying the SE yield. Results from our ...

Electron beam charging of insulators: A self-consistent flight-drift model

International Nuclear Information System (INIS)

Touzin, M.; Goeuriot, D.; Guerret-Piecourt, C.; Juve, D.; Treheux, D.; Fitting, H.-J.

2006-01-01

Electron beam irradiation and the self-consistent charge transport in bulk insulating samples are described by means of a new flight-drift model and an iterative computer simulation. Ballistic secondary electron and hole transport is followed by electron and hole drifts, their possible recombination and/or trapping in shallow and deep traps. The trap capture cross sections are the Poole-Frenkel-type temperature and field dependent. As a main result the spatial distributions of currents j(x,t), charges ρ(x,t), the field F(x,t), and the potential slope V(x,t) are obtained in a self-consistent procedure as well as the time-dependent secondary electron emission rate σ(t) and the surface potential V 0 (t). For bulk insulating samples the time-dependent distributions approach the final stationary state with j(x,t)=const=0 and σ=1. Especially for low electron beam energies E 0 G of a vacuum grid in front of the target surface. For high beam energies E 0 =10, 20, and 30 keV high negative surface potentials V 0 =-4, -14, and -24 kV are obtained, respectively. Besides open nonconductive samples also positive ion-covered samples and targets with a conducting and grounded layer (metal or carbon) on the surface have been considered as used in environmental scanning electron microscopy and common SEM in order to prevent charging. Indeed, the potential distributions V(x) are considerably small in magnitude and do not affect the incident electron beam neither by retarding field effects in front of the surface nor within the bulk insulating sample. Thus the spatial scattering and excitation distributions are almost not affected

Secondary vertex detection at the SLC

International Nuclear Information System (INIS)

Anon.

1982-01-01

The vertex topology of a high energy e + e - interaction contains a wealth of information. These interactions copiously produce the tau lepton and hadrons containing the c and b quarks; all these particles decay within a millimeter or so of the primary interaction point, giving these interactions a rich secondary vertex structure. With suitable detectors, one can hope to reconstruct these vertices and so tag events with tau's, c's and b's; measure lifetimes and mixing angles; and perhaps directly measure the flavor of c and b jets. The spatial resolution and track-pair resolution required of such detectors demand detector development, but several techniques, including solid state microstrip and CCD detectors, pressurized drift chambers, and holographic bubbble chambers look promising. Vertex detection in the colliding beam environment has already yielded a measurement of the tau lifetime. The SLC, with its micron-sized beam and one-centimeter sized beam pipe is uniquely suited for these studies. Compared to conventional storage rings, it offers a well-defined and minute primary interaction point, the possibility of locating a detector within a centimeter of the interaction (an order of magnitude improvement over LEP), negligibly thin beam pipes, and a repetition rate low enough to permit novel detectors and readout schemes. This report discusses the physics accessible with vertex detectors, depicts the physics environment at 100 GeV - particle multiplicities, momenta, angular correlations, and topologies of charm decays, sketches the elements of a vertex detector, and, through some model studies evaluates the spatial resolution and track-pair resolution requirements, and summarizes the detector technologies which seem most promising for vertex detection

Acceleration of laser-injected electron beams in an electron-beam driven plasma wakefield accelerator

International Nuclear Information System (INIS)

Knetsch, Alexander

2018-03-01

Plasma wakefields deliver accelerating fields that are approximately a 100 times higher than those in conventional radiofrequency or even superconducting radiofrequency cavities. This opens a transformative path towards novel, compact and potentially ubiquitous accelerators. These prospects, and the increasing demand for electron accelerator beamtime for various applications in natural, material and life sciences, motivate the research and development on novel plasma-based accelerator concepts. However, these electron beam sources need to be understood and controlled. The focus of this thesis is on electron beam-driven plasma wakefield acceleration (PWFA) and the controlled injection and acceleration of secondary electron bunches in the accelerating wake fields by means of a short-pulse near-infrared laser. Two laser-triggered injection methods are explored. The first one is the Trojan Horse Injection, which relies on very good alignment and timing control between electron beam and laser pulse and then promises electron bunches with hitherto unprecedented quality as regards emittance and brightness. The physics of electron injection in the Trojan Horse case is explored with a focus on the final longitudinal bunch length. Then a theoretical and numerical study is presented that examines the physics of Trojan Horse injection when performed in an expanding wake generated by a smooth density down-ramp. The benefits are radically decreased drive-electron bunch requirements and a unique bunch-length control that enables longitudinal electron-bunch shaping. The second laser-triggered injection method is the Plasma Torch Injection, which is a versatile, all-optical laser-plasma-based method capable to realize tunable density downramp injection. At the SLAC National Laboratory, the first proof-of-principle was achieved both for Trojan Horse and Plasma Torch injection. Setup details and results are reported in the experimental part of the thesis along with the commissioning

Self-focusing of a pulsed electron beam in gases and their ionization

International Nuclear Information System (INIS)

Hotta, Hiroshi; Arai, Hidehiko; Tanaka, Ryuichi; Sunaga, Hiromi.

1982-06-01

A relativistic high-intensity pulsed electron beam generated from a Febetron 706 was strongly self-focused in two pressure regions, i.e., below and above 5 Torr. The dependence of the electron energy spectrum on pressure and path length in He was at first studied by measuring depth-dose distributions in an aluminum-blue cellophane stack. Then, maximum doses of the depth-dose curves in the dosimeter placed on the beam axis at 10.4 cm from the cell window were measured as functions of pressure in He, Ne, Ar, Kr, Xe, H 2 , D 2 , N 2 , O 2 , N 2 O, CO 2 , SF 6 , CH 4 , C 2 H 2 , C 2 H 4 , C 2 H 6 , C 3 H 8 , CH 3 F, CHClF 2 , CCl 2 F 2 , He + X, Ar + X, and O 2 + X (X: additive gas). The strong self-focusing at pressure lower than 5 Torr is attributed to space-charge neutralization by positive ions due to escaping of secondary electrons. Therefore, relative total ionization cross sections for beam electrons could be obtained in this region. When the spa ce-charge neutralization time becomes shorter than a rise time of the pulsed beam, secondary electrons are accelerated by a backward electric field E sub(z) induced by the pulsed beam so that the self-focusing declines abruptly due to electron avalanching. The beam is self-focused again gradually with further increasing pressure because of suppression of this avalanching. The avalanching was analyzed self-consistently for He, Ar, H 2 , N 2 , and CH 4 by a computer simulation in the pressure region between 5 and 300 Torr. The present computational results indicate that the larger cose is given by the longer mean ionization time t sub(i) which depends on E sub(z)/p. The value of t sub(i) increases with increasing pressure in the pressure region of gradually-increasing self-focusing. (J.P.N.)

Design Considerations of a Novel Two-Beam Accelerator

Science.gov (United States)

Luginsland, John William

This thesis reports the design study of a new type of charged particle accelerator called the Twobetron. The accelerator consists of two beams of electrons traveling through a series of pillbox cavities. The power of a high current annular beam excites an electromagnetic mode in the cavities, which, in turn, drives a low current on-axis pencil beam to high energy. We focus on the design considerations that would make use of existing pulsed power systems, for a proof-of-principle experiment. Potential applications of this new device include radiotherapy, materials processing, and high energy accelerators. The first phase of the research involves analytic description of the accelerating process. This reveals the problem of phase slippage. Derbenev's proposed cure of beam radius modulation is analyzed. Further studies include the effect of initial phase and secondary beam loading. Scaling laws to characterize the Twobetron's performance are derived. Computer simulation is performed to produce a self-consistent analysis of the dynamics of the space charge and its interaction with the accelerator structure. Particle -in-cell simulations answer several questions concerning beam stability, cavity modes, and the nature of the structure. Specifically, current modulation on the primary beam is preserved in the simulations. However, these simulations also revealed that mode competition and significant cavity coupling are serious issues that need to be addressed. Also considered is non-axisymmetric instability on the driver beam of the Twobetron, in particular, the beam breakup instability (BBU), which is known to pose a serious threat to linear accelerators in general. We extend the classical analysis of BBU to annular beams. The effect of higher order non-axisymmetric modes is also examined. It is shown that annular beams are more stable than pencil beams to BBU in general. Our analysis also reveals that the rf magnetic field is more important than the rf electric field in

A photomultiplier-based secondary electron imaging system for a nuclear microprobe

International Nuclear Information System (INIS)

Alves, L.C.; Breese, M.B.H.; Silva, M.F. da; Soares, J.C.

2002-01-01

The ability to define, or recognise particular regions of interest or surface features is vital to the analysis and interpretation of spatially-resolved images collected with a nuclear microprobe. However, good topographic image contrast is difficult to accomplish using PIXE or RBS images due to their inherent insensitivity to topography, lack of elemental variation or poor statistics. Topographic image contrast is commonly obtained in scanning electron microscopy (SEM) by detecting a large flux of secondary electrons produced by the focused keV electron beam. Similar systems have not been widely used on nuclear microprobes due to ion beam intensity fluctuations, which limit the minimum resolvable contrast and present a major limitation for this technique. This paper describes a secondary electron imaging system which has been developed on the Lisbon microprobe. It is based on a scintillator, a photomultiplier operated in a pulsed mode, a pulse shaping electronic chain and ADC, and requires no changes to the existing data acquisition system. Examples of the images obtained from materials such as patterned SiGe wafers and hydrogen-implanted silicon are given, and compared with SEM or optical images

Microdosimetric Characteristics of the Clinical Proton Beams at the JINR Phasotron, Dubna

CERN Document Server

Vlcek, B; Spurny, F

2002-01-01

The contribution of the high LET particles to dosimetric and microdosimetric characteristics of 150 and 205 MeV clinical proton beams was experimentally studied using track etched detectors. Secondary heavy charged particles produced from nuclear interactions and degraded protons at the Bragg peak region are particles with high LET. The method of the LET spectra measurement with track etched detectors allows one to determine the contribution of high LET particles to dosimetric characteristics of clinical proton beams: absorbed dose, equivalent dose and the value of the Relative Biological Effectiveness (RBE). Track detectors were irradiated in the various depth of clinical proton beams with the primary energies of 150 and 205 MeV. The LET spectra between 10 and 700 keV/m were measured by means of CR-39 track etched detectors and the automatic optical image analyzer LUCIA-II. The relative contribution of the high LET particles to absorbed dose increases from several per cent at the beam entrance to several ten...

Modeling the biophysical effects in a carbon beam delivery line by using Monte Carlo simulations

Science.gov (United States)

Cho, Ilsung; Yoo, SeungHoon; Cho, Sungho; Kim, Eun Ho; Song, Yongkeun; Shin, Jae-ik; Jung, Won-Gyun

2016-09-01

The Relative biological effectiveness (RBE) plays an important role in designing a uniform dose response for ion-beam therapy. In this study, the biological effectiveness of a carbon-ion beam delivery system was investigated using Monte Carlo simulations. A carbon-ion beam delivery line was designed for the Korea Heavy Ion Medical Accelerator (KHIMA) project. The GEANT4 simulation tool kit was used to simulate carbon-ion beam transport into media. An incident energy carbon-ion beam with energy in the range between 220 MeV/u and 290 MeV/u was chosen to generate secondary particles. The microdosimetric-kinetic (MK) model was applied to describe the RBE of 10% survival in human salivary-gland (HSG) cells. The RBE weighted dose was estimated as a function of the penetration depth in the water phantom along the incident beam's direction. A biologically photon-equivalent Spread Out Bragg Peak (SOBP) was designed using the RBE-weighted absorbed dose. Finally, the RBE of mixed beams was predicted as a function of the depth in the water phantom.

CRionScan: A stand-alone real time controller designed to perform ion beam imaging, dose controlled irradiation and proton beam writing

Science.gov (United States)

Daudin, L.; Barberet, Ph.; Serani, L.; Moretto, Ph.

2013-07-01

High resolution ion microbeams, usually used to perform elemental mapping, low dose targeted irradiation or ion beam lithography needs a very flexible beam control system. For this purpose, we have developed a dedicated system (called “CRionScan”), on the AIFIRA facility (Applications Interdisciplinaires des Faisceaux d'Ions en Région Aquitaine). It consists of a stand-alone real-time scanning and imaging instrument based on a Compact Reconfigurable Input/Output (Compact RIO) device from National Instruments™. It is based on a real-time controller, a Field Programmable Gate Array (FPGA), input/output modules and Ethernet connectivity. We have implemented a fast and deterministic beam scanning system interfaced with our commercial data acquisition system without any hardware development. CRionScan is built under LabVIEW™ and has been used on AIFIRA's nanobeam line since 2009 (Barberet et al., 2009, 2011) [1,2]. A Graphical User Interface (GUI) embedded in the Compact RIO as a web page is used to control the scanning parameters. In addition, a fast electrostatic beam blanking trigger has been included in the FPGA and high speed counters (15 MHz) have been implemented to perform dose controlled irradiation and on-line images on the GUI. Analog to Digital converters are used for the beam current measurement and in the near future for secondary electrons imaging. Other functionalities have been integrated in this controller like LED lighting using Pulse Width Modulation and a “NIM Wilkinson ADC” data acquisition.

CRionScan: A stand-alone real time controller designed to perform ion beam imaging, dose controlled irradiation and proton beam writing

Energy Technology Data Exchange (ETDEWEB)

Daudin, L., E-mail: daudin@cenbg.in2p3.fr [Université Bordeaux, CENBG, UMR 5797, F-33170 Gradignan (France); CNRS, IN2P3, CENBG, UMR 5797, F-33170 Gradignan (France); Barberet, Ph.; Serani, L.; Moretto, Ph. [Université Bordeaux, CENBG, UMR 5797, F-33170 Gradignan (France); CNRS, IN2P3, CENBG, UMR 5797, F-33170 Gradignan (France)

2013-07-01

High resolution ion microbeams, usually used to perform elemental mapping, low dose targeted irradiation or ion beam lithography needs a very flexible beam control system. For this purpose, we have developed a dedicated system (called “CRionScan”), on the AIFIRA facility (Applications Interdisciplinaires des Faisceaux d’Ions en Région Aquitaine). It consists of a stand-alone real-time scanning and imaging instrument based on a Compact Reconfigurable Input/Output (Compact RIO) device from National Instruments™. It is based on a real-time controller, a Field Programmable Gate Array (FPGA), input/output modules and Ethernet connectivity. We have implemented a fast and deterministic beam scanning system interfaced with our commercial data acquisition system without any hardware development. CRionScan is built under LabVIEW™ and has been used on AIFIRA’s nanobeam line since 2009 (Barberet et al., 2009, 2011) [1,2]. A Graphical User Interface (GUI) embedded in the Compact RIO as a web page is used to control the scanning parameters. In addition, a fast electrostatic beam blanking trigger has been included in the FPGA and high speed counters (15 MHz) have been implemented to perform dose controlled irradiation and on-line images on the GUI. Analog to Digital converters are used for the beam current measurement and in the near future for secondary electrons imaging. Other functionalities have been integrated in this controller like LED lighting using Pulse Width Modulation and a “NIM Wilkinson ADC” data acquisition.

Study of the Clinical Proton Beam Relative Biological Effectiveness at the JINR Phasotron, Dubna

CERN Document Server

Vitanova, A; Gaevskii, V N; Molokonov, A G; Spurny, F; Fadeeva, T A; Shmakova, N L

2002-01-01

Proton clinical beams contain particles with high linear energy transfer (LET). Secondary heavy charged particles produced from nuclear interactions and degraded protons at the Bragg peak region are particles with high LET. These particles could enhance the Relative Biological Effectiveness (RBE) of the proton beam. We have carried out two radiobiological experiments to investigate the RBE of 150 MeV clinical proton beam. The irradiation of the Chinese Hamster V79 cells were performed at two points of the depth-dose distribution - at the beam entrance and at the Bragg peak. The contribution of the high LET particles to dosimetric and microdosimetric characteristics in the various depth of proton beam was also experimentally studied using the CR-39 track etched detectors. The LET spectra between 10 and 700 keV/{\\mu}m were measured by means of track detectors and the automatic optical image analyzer LUCIA-II. The relative contribution of the high LET particles to ab! sorbed dose increases from several per cent ...

Beam-beam limit in e+e- circular colliders

International Nuclear Information System (INIS)

Ohmi, K.; Tawada, M.; Kamada, S.; Oide, K.; Cai, Y.; Qiang, J.

2004-01-01

Beam-beam effects limit the luminosity of circular colliders. Once the bunch population exceeds a threshold, the luminosity increases at a slower rate. This phenomenon is called the beam-beam limit. Onset of the beam-beam limit has been analyzed with various simulation methods based on the weak-strong and strong-strong models. We have observed that an incoherent phenomenon is mainly concerned in the beam-beam limit. The simulation have shown that equilibrium distributions of the two colliding beams are distorted from Gaussians when the luminosity is limited. The beam-beam limit is estimated to be ξ∼0.1 for a B factory with damping time of several thousand turns

Beam-beam interactions in p-p storage rings

CERN Document Server

Keil, Eberhard

1977-01-01

There are two lectures. The first one (sections 2 to 5) deals with the theoretical aspects of the beam-beam interaction, and the second one (sections 6 to 8) describes the results of experiments in the ISR. Section 3 describes the strength of the beam-beam interaction in terms of the linear tune shift Delta Q which has been calculated for several models. Because of the non-uniform density distribution in the beam the force results in a tune spread. This can be calculated by a perturbation method as explained in section 4. Section 5 discusses the simulation of the beam-beam interaction on a computer. Finally, section 6 reviews beam-beam phenomena observed in the CERN-ISR. These include the absence of observable beam-beam effects in unbunched beams, overlap knock-out resonances, collisions between a low-energy beam and a high-intensity stack, experiments with a nonlinear lens, and experiments with a high- beta insertion. (20 refs).

Assessment of doses due to secondary neutrons received by patient treated by proton therapy

International Nuclear Information System (INIS)

Sayah, R.; Martinetti, F.; Donadille, L.; Clairand, I.; Delacroix, S.; De Oliveira, A.; Herault, J.

2010-01-01

Proton therapy is a specific technique of radiotherapy which aims at destroying cancerous cells by irradiating them with a proton beam. Nuclear reactions in the device and in the patient himself induce secondary radiations involving mainly neutrons which contribute to an additional dose for the patient. The author reports a study aimed at the assessment of these doses due to secondary neutrons in the case of ophthalmological and intra-cranial treatments. He presents a Monte Carlo simulation of the room and of the apparatus, reports the experimental validation of the model (dose deposited by protons in a water phantom, ambient dose equivalent due to neutrons in the treatment room, absorbed dose due to secondary particles in an anthropomorphic phantom), and the assessment with a mathematical phantom of doses dues to secondary neutrons received by organs during an ophthalmological treatment. He finally evokes current works of calculation of doses due to secondary neutrons in the case of intra-cranial treatments

Extraction of a long-pulsed intense electron beam from a pulsed plasma based on hollow cathode discharge

International Nuclear Information System (INIS)

Uramoto, Johshin.

1977-05-01

An intense electron beam (up to 1.0 kV, 0.8 kA in 0.8 cm phi) is extracted along a uniform magnetic field with a long decay time (up to 2 msec) from a pulsed high density plasma source which is produced with a fast rise time (< 100 μsec) by a secondary discharge based on a dc hollow cathode discharge. Through a back stream of ionized ions from a beam-extracting anode region where a neutral gas is fed, a space charge limit of the electron beam is so reduced that the beam current is determined by an initially injected electron flux and concentrated in a central aperture of the extracting anode. Moreover, the beam pulse width is much extended by the neutral gas feed into the anode space. (auth.)

Transport of secondary electrons and reactive species in ion tracks

Science.gov (United States)

Surdutovich, Eugene; Solov'yov, Andrey V.

2015-08-01

The transport of reactive species brought about by ions traversing tissue-like medium is analysed analytically. Secondary electrons ejected by ions are capable of ionizing other molecules; the transport of these generations of electrons is studied using the random walk approximation until these electrons remain ballistic. Then, the distribution of solvated electrons produced as a result of interaction of low-energy electrons with water molecules is obtained. The radial distribution of energy loss by ions and secondary electrons to the medium yields the initial radial dose distribution, which can be used as initial conditions for the predicted shock waves. The formation, diffusion, and chemical evolution of hydroxyl radicals in liquid water are studied as well. COST Action Nano-IBCT: Nano-scale Processes Behind Ion-Beam Cancer Therapy.

Spatial and temporal beam profile monitor with nanosecond resolution for CERN's Linac4 and Superconducting Proton Linac

CERN Document Server

Hori, M

2008-01-01

The Linac4, now being developed at CERN, will provide 160-MeV H- beams of high intensity . Before this beam can be injected into the CERN Proton Synchrotron Booster or future Superconducting Proton Linac for further acceleration, some sequences of 500-ps-long micro-bunches must be removed from it, using a beam chopper. These bunches, if left in the beam, would fall outside the longitudinal acceptance of the accelerators and make them radioactive. We developed a monitor to measure the time structure and spatial profile of this chopped beam, with respective resolutions and . Its large active area and dynamic range also allows investigations of beam halos. The ion beam first struck a carbon foil, and secondary electrons emerging from the foil were accelerated by a series of parallel grid electrodes. These electrons struck a phosphor screen, and the resulting image of the scintillation light was guided to a thermoelectrically cooled, charge-coupled device camera. The time resolution was attained by applying high-...

Chromium Waste Treatment from Leather Manufacture Using Electron Beam Radiation Technic

International Nuclear Information System (INIS)

Didiek Herhady, R.; Sukarsono, R.

2007-01-01

Leather manufacture chromium waste treatment using chemical methods have an essential disadvantage, because of the production of the secondary contamination of wastes and separated sediments used by reagents. Therefore, a new technique is needed to solve this problem. The aim of the research to learn the advantages of electron beam radiation for chromium waste treatment. Water radiolysis can be produced by the interaction between electron beam and water or liquid substances. This phenomenon produces many reducing agents and ions that could reduce chromium concentrations in the liquid waste. Ethyl alcohol as a scavenger was added in the waste samples, then the pH of varied from 1, 4, 8 to 12, then were irradiated. Irradiation were done by Electron Beam Machine with dose 15, 25, and 35 kGy. After irradiation, chromium concentration in the samples were analyzed by AAS and UV-vis spectrophotometer. The results had shown that chromium could be reduced by high dose electron beam. The optimum reduction of chromium was achieved at liquid waste pH 8 and irradiation dose 35 kGy. (author)

Sheath structure transition controlled by secondary electron emission

Science.gov (United States)

Schweigert, I. V.; Langendorf, S. J.; Walker, M. L. R.; Keidar, M.

2015-04-01

In particle-in-cell Monte Carlo collision (PIC MCC) simulations and in an experiment we study sheath formation over an emissive floating Al2O3 plate in a direct current discharge plasma at argon gas pressure 10-4 Torr. The discharge glow is maintained by the beam electrons emitted from a negatively biased hot cathode. We observe three types of sheaths near the floating emissive plate and the transition between them is driven by changing the negative bias. The Debye sheath appears at lower voltages, when secondary electron emission is negligible. With increasing applied voltage, secondary electron emission switches on and a first transition to a new sheath type, beam electron emission (BEE), takes place. For the first time we find this specific regime of sheath operation near the floating emissive surface. In this regime, the potential drop over the plate sheath is about four times larger than the temperature of plasma electrons. The virtual cathode appears near the emissive plate and its modification helps to maintain the BEE regime within some voltage range. Further increase of the applied voltage U initiates the second smooth transition to the plasma electron emission sheath regime and the ratio Δφs/Te tends to unity with increasing U. The oscillatory behavior of the emissive sheath is analyzed in PIC MCC simulations. A plasmoid of slow electrons is formed near the plate and transported to the bulk plasma periodically with a frequency of about 25 kHz.

Simulation of Beam-Beam Background at CLIC

CERN Document Server

Sailer, Andre

2010-01-01

The dense beams used at CLIC to achieve a high luminosity will cause a large amount of background particles through beam-beam interactions. Generator level studies with GuineaPig and full detector simulation studies with an ILD based CLIC detector have been performed to evaluate the amount of beam-beam background hitting the vertex detector.

Simulation of Beam-Beam Background at CLIC

CERN Document Server

Sailer, A

2010-01-01

The dense beams used at CLIC to achieve a high luminosity will cause a large amount of background particles through beam-beam interactions. Generator level studies with GUINEAPIG and full detector simulation studies with an ILD based CLIC detector have been performed to evaluate the amount of beam-beam back- ground hitting the vertex detector.

Beam-beam interactions in p-p storage rings

International Nuclear Information System (INIS)

Keil, E.

1977-01-01

There are two lectures: the first part of this paper (sections 2 to 5) deals with the theoretical aspects of the beam-beam interaction, and the second part (sections 6 to 8) describe the results of experiments in the ISR. Section 3 describes the strengths of the beam-beam interaction in terms of the linear tune shift ΔQ which has been calculated for several models. Because of the non-uniform density distribution in the beam the force results in a tune spread. This can be calculated by a perturbation method as explained in section 4. Section 5 discusses the simulation of the beam-beam interaction on a computer. Finally, section 6 reviews beam-beam phenomena observed in the CERN-ISR. These include the absence of observable beam-beam effects in unbunched beams, overlap knock-out resonances, collisions between a low-energy beam and a high-intensity stack, experiments with a nonlinear lens, and experiments with a high-β insertion. Section 7 contains a few concluding remarks. (Auth.)

Beam tests with microstrip gas counters

International Nuclear Information System (INIS)

Landry, M.R.; Birchall, J.; Crow, K.; Davis, C.A.; Faszer, W.; Gan, L.; Lee, L.; van Oers, W.T.H.; Page, S.A.; Ramsay, W.D.; Salomon, M.

1994-10-01

We have measured the efficiency, timing and pulse heights in several types of microstrip Gas Chambers with plastic substrates passivated with a thin Nickel layer. We used as active gas mixtures Argon/Isobutane and CF 4 /Isobutane. We placed the detectors in a secondary beam at TRIUMF tuned to a momentum of 100 MeV/c of pions, muons and electrons. Preliminary results indicate good efficiency for minimum ionizing particles in Argon/Isobutane mixtures but lesser efficiency in CF 4 based gases indicating the importance of high quality preamplifiers to increase the signal to noise ratio. (author). 20 refs., 6 figs

Studies of the beam-beam interaction for the LHC

International Nuclear Information System (INIS)

Krishnagopal, S.; Furman, M.A.; Turner, W.C.

1999-01-01

The authors have used the beam-beam simulation code CBI to study the beam-beam interaction for the LHC. We find that for nominal LHC parameters, and assuming only one bunch per beam, there are no collective (coherent) beam-beam instabilities. We have investigated the effect of sweeping one of the beams around the other (a procedure that could be used as a diagnostic for head-on beam-beam collisions). We find that this does not cause any problems at the nominal current, though at higher currents there can be beam blow-up and collective beam motion. consequence of quadrupole collective effects

Design of a compact Faraday cup for low energy, low intensity ion beams

Energy Technology Data Exchange (ETDEWEB)

Cantero, E.D., E-mail: esteban.cantero@cern.ch [CERN, 1211 Geneva 23 (Switzerland); Sosa, A. [CERN, 1211 Geneva 23 (Switzerland); The University of Liverpool, Liverpool (United Kingdom); Andreazza, W.; Bravin, E.; Lanaia, D.; Voulot, D. [CERN, 1211 Geneva 23 (Switzerland); Welsch, C.P. [The University of Liverpool, Liverpool (United Kingdom); The Cockcroft Institute, Sci-Tech Daresbury, Daresbury, Warrington (United Kingdom)

2016-01-21

Beam intensity is one of the key parameters in particle accelerators, in particular during machine commissioning, but also during operation for experiments. At low beam energies and low intensities a number of challenges arise in its measurement as commonly used non-invasive devices are no longer sensitive enough. It then becomes necessary to stop the beam in order to measure its absolute intensity. A very compact Faraday cup for determining ion beam currents from a few nanoamperes down to picoamperes for the HIE-ISOLDE post-accelerator at CERN has been designed, built and tested with beam. It has a large aperture diameter of 30 mm and a total length of only 16 mm, making it one of the most compact designs ever used. In this paper we present the different steps that were involved in the design and optimization of this device, including beam tests with two early prototypes and the final monitor. We also present an analysis of the losses caused by secondary particle emission for different repelling electrode voltages and beam energies. Finally, we show that results obtained from an analytical model for electron loss probability combined with Monte Carlo simulations of particles trajectories provide a very good agreement with experimental data.

Measurement and calculation of secondary gamma rays resulting from exposure of Fe, Pb, and H/sub 2/O to the ARERR-1 spectrum

Energy Technology Data Exchange (ETDEWEB)

Makarious, A.S.; Ford, W.E. III; Turnbull, K.R.

1977-08-01

Integral experiments were performed to measure the angular distribution of secondary gamma rays produced when various thicknesses of Fe, Pb, and H/sub 2/O samples were exposed to bare and to B/sub 4/C-filtered neutron beams from the Research Reactor of Egypt. For selected experiments, multigroup coupled neutron-gamma cross sections and a discrete ordinates transport theory code (DOT4PI-M) were used to calculate the secondary gamma rays and the transport of primary gamma rays. Integral comparisons between the calculated and measured spectra were favorable. Graphical comparisons of the measured flux for various angles of incidence of the neutron beams on the samples, for various angles of exit on the transmitted side of the samples, and for various sample thicknesses are shown. The comparisons show that the angular distribution of secondary gamma rays for the three materials changes slightly with a change in the angle of beam incident on the sample, but increasing the angle between the normal to the sample and the detector by 60/sup 0/ decreases the measured secondary gamma-ray flux up to a factor of two. An investigation was made to determine the consequences of using single scatter Compton theory versus using discrete ordinates transport calculations to estimate the primary gamma-ray contribution to the measured photon spectra.

Measurements of the Secondary Electron Emission from Rare Gases at 4.2K

CERN Document Server

Bozhko, Y.; Hilleret, N.

2013-01-01

Dependence of the secondary electron yield (SEY) from the primary beam incident energy and the coverage has been measured for neon, argon, krypton and xenon condensed on a target at 4.2K. The beam energy ranged between 100 eV and 3 keV, the maximal applied coverage have made up 12000, 4700, 2500 and 1400 monolayers correspondingly for neon, argon, krypton and xenon. The SEY results for these coverages can be considered as belonging only to investigated gases without influence of the target material. The SEY dependencies versus the primary beam energy for all gases comprise only an ascending part and therefore, the maximal measured SEY values have been obtained for the beam energy of 3keV and have made up 62, 73, 60.5 and 52 for neon, argon, krypton and xenon correspondingly. Values of the first cross-over have made up 21 eV for neon, 14 eV for argon, 12.5 eV for krypton and 10.5 eV for xenon. An internal field appearing across a film due to the beam impact can considerably affect the SEY measurements that dem...

Beam divergence scaling in neutral beam injectors

International Nuclear Information System (INIS)

Holmes, A.J.T.

1976-01-01

One of the main considerations in the design of neutral beam injectors is to monimize the divergence of the primary ion beam and hence maximize the beam transport and minimize the input of thermal gas. Experimental measurements of the divergence of a cylindrical ion beam are presented and these measurements are used to analyze the major components of ion beam divergence, namely: space charge expansion, gas-ion scattering, emittance and optical aberrations. The implication of these divergence components in the design of a neutral beam injector system is discussed and a method of maximizing the beam current is described for a given area of source plasma

Beam-beam diagnostics from closed-orbit distortion

International Nuclear Information System (INIS)

Furman, M.; Chin, Y.H.; Eden, J.; Kozanecki, W.; Tennyson, J.; Ziemann, V.

1992-07-01

We study the applicability of beam-beam deflection techniques as a tuning tool for asymmetric B factories, focusing on PEP-II as an example. Assuming that the closed orbits of the two beams are separated vertically at the interaction point by a local orbit bump that is nominally closed, we calculate the residual beam orbit distortions due to the beam-beam interaction. Difference orbit measurements, performed at points conveniently distant from the interaction point (IP), provide distinct signatures that can be used to maintain the beams in collision and perform detailed optical diagnostics at the IP. A proposal to test this method experimentally at the TRISTAN ring is briefly discussed

Ultrafast Melting of Carbon Induced by Intense Proton Beams

International Nuclear Information System (INIS)

Pelka, A.; Guenther, M. M.; Harres, K.; Otten, A.; Roth, M.; Gregori, G.; Gericke, D. O.; Vorberger, J.; Glenzer, S. H.; Kritcher, A. L.; Heathcote, R.; Li, B.; Neely, D.; Kugland, N. L.; Niemann, C.; Makita, M.; Riley, D.; Mithen, J.; Schaumann, G.; Schollmeier, M.

2010-01-01

Laser-produced proton beams have been used to achieve ultrafast volumetric heating of carbon samples at solid density. The isochoric melting of carbon was probed by a scattering of x rays from a secondary laser-produced plasma. From the scattering signal, we have deduced the fraction of the material that was melted by the inhomogeneous heating. The results are compared to different theoretical approaches for the equation of state which suggests modifications from standard models.

Adjuvant Ab Interno Tumor Treatment After Proton Beam Irradiation.

Science.gov (United States)

Seibel, Ira; Riechardt, Aline I; Heufelder, Jens; Cordini, Dino; Joussen, Antonia M

2017-06-01

This study was performed to show long-term outcomes concerning globe preservation in uveal melanoma patients after proton beam therapy with the main focus on outcomes according to different adjuvant ab interno surgical procedures. Retrospective cohort study. All patients treated with primary proton beam therapy for choroidal or ciliary body melanoma between June 1998 and June 2015 were included. A total of 2499 patients underwent primary proton beam therapy, with local tumor control and globe preservation rates of 95.9% and 94.8% after 5 years, respectively. A total of 110 (4.4%) patients required secondary enucleation. Unresponsive neovascular glaucoma was the leading cause of secondary enucleation in 78 of the 2499 patients (3.1%). The 5-year enucleation-free survival rate was 94.8% in the endoresection group, 94.3% in the endodrainage group, and 93.5% in the comparator group. The log-rank test showed P = .014 (comparator group vs endoresection group) and P = .06 (comparator group vs endodrainage-vitrectomy group). Patients treated with endoresection or endodrainage-vitrectomy developed less radiation retinopathy (30.5% and 37.4% after 5 years, P = .001 and P = .048 [Kaplan-Meier], respectively) and less neovascular glaucoma (11.6% and 21.3% after 5 years, P = .001 and P = .01 [Kaplan-Meier], respectively) compared with the comparator group (52.3% radiation retinopathy and 57.8% neovascular glaucoma after 5 years). This study suggests that in larger tumors the enucleation and neovascular glaucoma rates might be reduced by adjuvant surgical procedures. Although endoresection is the most promising adjuvant treatment option, the endodrainage-vitrectomy is recommended in patients who are ineligible for endoresection. Copyright © 2017 Elsevier Inc. All rights reserved.

Radiation protection commissioning of neutron beam instruments at the OPAL research reactor

International Nuclear Information System (INIS)

Parkes, Alison; Saratsopoulos, John; Deura, Michael; Kenny, Pat

2008-01-01

The neutron beam facilities at the 20 MW OPAL Research Reactor were commissioned in 2007 and 2008. The initial suite of eight neutron beam instruments on two thermal neutron guides, two cold neutron guides and one thermal beam port located at the reactor face, together with their associated shielding were progressively installed and commissioned according to their individual project plans. Radiation surveys were systematically conducted as reactor power was raised in a step-wise manner to 20 MW in order to validate instrument shielding design and performance. The performance of each neutron guide was assessed by neutron energy spectrum and flux measurements. The activation of beam line components, decay times assessments and access procedures for Bragg Institute beam instrument scientists were established. The multiple configurations for each instrument and the influence of operating more than one instrument or beamline simultaneously were also tested. Areas of interest were the shielding around the secondary shutters, guide shield and bunker shield interfaces and monochromator doors. The shielding performance, safety interlock checks, improvements, radiation exposures and related radiation protection challenges are discussed. This paper discusses the health physics experience of commissioning the OPAL Research Reactor neutron beam facilities and describes health physics results, actions taken and lessons learned during commissioning. (author)

Full Scale RC Beam-Column Joints Strengthened with Steel Reinforced Polymer Systems

Science.gov (United States)

De Vita, Alessandro; Napoli, Annalisa; Realfonzo, Roberto

2017-07-01

This paper presents the results of an experimental campaign performed at the Laboratory of Materials and Structural Testing of the University of Salerno (Italy) in order to investigate the seismic performance of RC beam-column joints strengthened with Steel Reinforced Polymer (SRP) systems. With the aim to represent typical façade frames’ beam-column subassemblies found in existing RC buildings, specimens were provided with two short beam stubs orthogonal to the main beam and were designed with inadequate seismic details. Five members were strengthened by using two different SRP layouts while the remaining ones were used as benchmarks. Once damaged, two specimens were also repaired, retrofitted with SRP and subjected to cyclic test again. The results of cyclic tests performed on SRP strengthened joints are examined through a comparison with the outcomes of the previous experimental program including companion specimens not provided with transverse beam stubs and strengthened by Carbon Fiber Reinforced Polymer (CFRP) systems. In particular, both qualitative and quantitative considerations about the influence of the confining effect provided by the secondary beams on the joint response, the suitability of all the adopted strengthening solutions (SRP/CFRP systems), the performances and the failure modes experienced in the several cases studied are provided.

Beam-beam interaction in e+-e- storage rings

International Nuclear Information System (INIS)

Le Duff, J.

1977-01-01

Colliding beams in electron-positron storage rings are discussed with particular reference to the space charge forces occuring during beam-beam interactions and their effect on beam current and consequently machine performance (maximum luminosity). The first section deals with linear beam-beam effects and discussses linear tune shift; the second section considers non-linear beam-beam effects and the creation on non-linear resonances. The last section poses questions of the possibility of extrapolating present results to future machines and discusses optimization of storage ring performance. (B.D.)

Novel field emission SEM column with beam deceleration technology

International Nuclear Information System (INIS)

Jiruše, Jaroslav; Havelka, Miloslav; Lopour, Filip

2014-01-01

A novel field-emission SEM column has been developed that features Beam Deceleration Mode, high-probe current and ultra-fast scanning. New detection system in the column is introduced to detect true secondary electron signal. The resolution power at low energy was doubled for conventional SEM optics and moderately improved for immersion optics. Application examples at low landing energies include change of contrast, imaging of non-conductive samples and thin layers. - Highlights: • A novel field-emission SEM column has been developed. • Implemented beam deceleration improves the SEM resolution at 1 keV two times. • New column maintains high analytical potential and wide field of view. • Detectors integrated in the column allow gaining true SE and BE signal separately. • Performance of the column is demonstrated on low energy applications

Novel field emission SEM column with beam deceleration technology

Energy Technology Data Exchange (ETDEWEB)

Jiruše, Jaroslav; Havelka, Miloslav; Lopour, Filip

2014-11-15

A novel field-emission SEM column has been developed that features Beam Deceleration Mode, high-probe current and ultra-fast scanning. New detection system in the column is introduced to detect true secondary electron signal. The resolution power at low energy was doubled for conventional SEM optics and moderately improved for immersion optics. Application examples at low landing energies include change of contrast, imaging of non-conductive samples and thin layers. - Highlights: • A novel field-emission SEM column has been developed. • Implemented beam deceleration improves the SEM resolution at 1 keV two times. • New column maintains high analytical potential and wide field of view. • Detectors integrated in the column allow gaining true SE and BE signal separately. • Performance of the column is demonstrated on low energy applications.

Booster gold beam injection efficiency and beam loss

International Nuclear Information System (INIS)

Zhang, S.Y.; Ahrens, L.A.

1998-01-01

The Relativistic Heavy Ion Collider (RHIC) at the BNL requires the AGS to provide Gold beam with the intensity of 10 9 ions per bunch. Over the years, the Tandem Van de Graaff has provided steadily increasing intensity of gold ion beams to the AGS Booster. However, the gold beam injection efficiency at the Booster has been found to decrease with the rising intensity of injected beams. As the result, for Tandem beams of the highest intensity, the Booster late intensity is lower than with slightly lower intensity Tandem beam. In this article, the authors present two experiments associated with the Booster injection efficiency and beam intensity. One experiment looks at the Booster injection efficiency by adjusting the Tandem beam intensity, and another looks at the beam life time while scraping the beam in the Booster. The studies suggest that the gold beam injection efficiency at the AGS Booster is related to the beam loss in the ring, rather than the intensity of injected beam or circulating beam. A close look at the effect of the lost gold ion at the Booster injection leads to the prediction that the lost gold ion creates large number of positive ions, and even larger number of electrons. The lost gold beam is also expected to create large numbers of neutral particles. In 1998 heavy ion run, the production of positive ions and electrons due to the lost gold beam has been observed. Also the high vacuum pressure due to the beam loss, presumably because of the neutral particles it created, has been measured. These results will be reported elsewhere

The renormalized theory of beam-beam interaction

International Nuclear Information System (INIS)

Chin, Yong Ho.

1988-06-01

A new approach to calculate analytically the particle distribution in the presence of beam-beam interaction and synchrotron radiation effects for an electron-positron colliding beam storage ring is presented. The method is based on correct calculation of the Green's function which includes the full effect of the beam-beam force on the distortion of particle orbits, borrowing the renormalization technique of quantum field therory. By this way, the theory is applicable to any level of beam-beam interaction, no matter whether chaos ensues in phase space or not. This paper is devoted mostly to verificaiton of the theory by comparison with the results of computer simulations. Fairly good agreements are obtained. 5 refs., 3 figs

Pitfalls of tungsten multileaf collimator in proton beam therapy

Energy Technology Data Exchange (ETDEWEB)

Moskvin, Vadim; Cheng, Chee-Wai; Das, Indra J. [Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, Indiana 46202 (United States) and Indiana University Health Proton Therapy Center (Formerly Midwest Proton Radiotherapy Institute), Bloomington, Indiana 47408 (United States)

2011-12-15

Purpose: Particle beam therapy is associated with significant startup and operational cost. Multileaf collimator (MLC) provides an attractive option to improve the efficiency and reduce the treatment cost. A direct transfer of the MLC technology from external beam radiation therapy is intuitively straightforward to proton therapy. However, activation, neutron production, and the associated secondary cancer risk in proton beam should be an important consideration which is evaluated. Methods: Monte Carlo simulation with FLUKA particle transport code was applied in this study for a number of treatment models. The authors have performed a detailed study of the neutron generation, ambient dose equivalent [H*(10)], and activation of a typical tungsten MLC and compared with those obtained from a brass aperture used in a typical proton therapy system. Brass aperture and tungsten MLC were modeled by absorber blocks in this study, representing worst-case scenario of a fully closed collimator. Results: With a tungsten MLC, the secondary neutron dose to the patient is at least 1.5 times higher than that from a brass aperture. The H*(10) from a tungsten MLC at 10 cm downstream is about 22.3 mSv/Gy delivered to water phantom by noncollimated 200 MeV beam of 20 cm diameter compared to 14 mSv/Gy for the brass aperture. For a 30-fraction treatment course, the activity per unit volume in brass aperture reaches 5.3 x 10{sup 4} Bq cm{sup -3} at the end of the last treatment. The activity in brass decreases by a factor of 380 after 24 h, additional 6.2 times after 40 days of cooling, and is reduced to background level after 1 yr. Initial activity in tungsten after 30 days of treating 30 patients per day is about 3.4 times higher than in brass that decreases only by a factor of 2 after 40 days and accumulates to 1.2 x 10{sup 6} Bq cm{sup -3} after a full year of operation. The daily utilization of the MLC leads to buildup of activity with time. The overall activity continues to increase

Dose calculation methods in photon beam therapy using energy deposition kernels

International Nuclear Information System (INIS)

Ahnesjoe, A.

1991-01-01

The problem of calculating accurate dose distributions in treatment planning of megavoltage photon radiation therapy has been studied. New dose calculation algorithms using energy deposition kernels have been developed. The kernels describe the transfer of energy by secondary particles from a primary photon interaction site to its surroundings. Monte Carlo simulations of particle transport have been used for derivation of kernels for primary photon energies form 0.1 MeV to 50 MeV. The trade off between accuracy and calculational speed has been addressed by the development of two algorithms; one point oriented with low computional overhead for interactive use and one for fast and accurate calculation of dose distributions in a 3-dimensional lattice. The latter algorithm models secondary particle transport in heterogeneous tissue by scaling energy deposition kernels with the electron density of the tissue. The accuracy of the methods has been tested using full Monte Carlo simulations for different geometries, and found to be superior to conventional algorithms based on scaling of broad beam dose distributions. Methods have also been developed for characterization of clinical photon beams in entities appropriate for kernel based calculation models. By approximating the spectrum as laterally invariant, an effective spectrum and dose distribution for contaminating charge particles are derived form depth dose distributions measured in water, using analytical constraints. The spectrum is used to calculate kernels by superposition of monoenergetic kernels. The lateral energy fluence distribution is determined by deconvolving measured lateral dose distributions by a corresponding pencil beam kernel. Dose distributions for contaminating photons are described using two different methods, one for estimation of the dose outside of the collimated beam, and the other for calibration of output factors derived from kernel based dose calculations. (au)

Beam-beam effect and luminosity in SPEAR

International Nuclear Information System (INIS)

Wiedemann, H.

1980-01-01

Many measurements on the beam-beam limit in SPEAR have been performed over the past years. The goal for these measurements was to find the proper parameterization of the beam-beam effect. All measurements presented were done with both beams equally blown up by control of the flip-flop phenomenon. Colliding beam measurements were made at energies as low as 600 MeV and together with earlier measurements the author presents the scaling of some relevant storage ring parameters from 600 MeV up to almost 4 GeV. (Auth.)

An investigation of the mass spectra of secondary ions ejected from the single crystal surface of semiconductors

International Nuclear Information System (INIS)

Koval', A.G.; Mel'nikov, V.N.; Enukov, Yu.V.

1976-01-01

The mass spectra of secondary positive and negative ions, ejected by an Ar + ion beam from the (100) face of an epitaxial film of the semiconductor Alsub(x)Gasub(1-x)As were investigated. There are many various secondary ions in the mass spectrum under investigation. They may be divided into four groups according to their origins. Mass spectra of secondary positive and negative secondary ions differ much, either in their composition or the intensities of homogeneous ions. The I(T) dependences (I=the current of corresponding secondary ions, T=target temperature) were obtained for secondary and negative ions taken from groups differing by their origin. The I(T) dependences were obtained at several oxygen pressures in a chamber. For the ions with 'superficial' origin a strong dependence of their current on target temperature is observed. Oxygen pressure increase leads to substantial change of the I(T)curves. (Auth.)

Magnetic field influences on the lateral dose response functions of photon-beam detectors: MC study of wall-less water-filled detectors with various densities.

Science.gov (United States)

Looe, Hui Khee; Delfs, Björn; Poppinga, Daniela; Harder, Dietrich; Poppe, Björn

2017-06-21

The distortion of detector reading profiles across photon beams in the presence of magnetic fields is a developing subject of clinical photon-beam dosimetry. The underlying modification by the Lorentz force of a detector's lateral dose response function-the convolution kernel transforming the true cross-beam dose profile in water into the detector reading profile-is here studied for the first time. The three basic convolution kernels, the photon fluence response function, the dose deposition kernel, and the lateral dose response function, of wall-less cylindrical detectors filled with water of low, normal and enhanced density are shown by Monte Carlo simulation to be distorted in the prevailing direction of the Lorentz force. The asymmetric shape changes of these convolution kernels in a water medium and in magnetic fields of up to 1.5 T are confined to the lower millimetre range, and they depend on the photon beam quality, the magnetic flux density and the detector's density. The impact of this distortion on detector reading profiles is demonstrated using a narrow photon beam profile. For clinical applications it appears as favourable that the magnetic flux density dependent distortion of the lateral dose response function, as far as secondary electron transport is concerned, vanishes in the case of water-equivalent detectors of normal water density. By means of secondary electron history backtracing, the spatial distribution of the photon interactions giving rise either directly to secondary electrons or to scattered photons further downstream producing secondary electrons which contribute to the detector's signal, and their lateral shift due to the Lorentz force is elucidated. Electron history backtracing also serves to illustrate the correct treatment of the influences of the Lorentz force in the EGSnrc Monte Carlo code applied in this study.

Beam-beam effects for the PEP-II B Factory

International Nuclear Information System (INIS)

Furman, M.A.; Eden, J.R.

1993-05-01

We present a summary of a fairly extensive study of beam-beam issues that arise in the design of PEP-II. Most of these studies are carried out with ''strong-strong'' multiparticle tracking simulations. We focus on: choice of nominal beam-beam parameter, strength of the parasitic collisions, injection issues, performance and tradeoffs with unequal beam-beam parameters. We comment only briefly on beam lifetime. We conclude that: the beams are sufficiently well separated so that the parasitic collisions are effectively weak; that small inequalities in the beam-beam parameters may imply more comfortable performance margins; and that vertical injection with vertical beam separation is more comfortable than horizontal

Combined phenomena of beam-beam and beam-electron cloud interactionsin circular e^{+}e^{-} colliders

Directory of Open Access Journals (Sweden)

Kazuhito Ohmi

2002-10-01

Full Text Available An electron cloud causes various effects in high intensity positron storage rings. The positron beam and the electron cloud can be considered a typical two-stream system with a certain plasma frequency. Beam-beam interaction is another important effect for high luminosity circular colliders. Colliding two beams can be considered as a two-stream system with another plasma frequency. We study the combined phenomena of the beam-electron cloud and beam-beam interactions from a viewpoint of two complex two-stream effects with two plasma frequencies.

Beam position monitor sensitivity for low-β beams

International Nuclear Information System (INIS)

Shafer, R.E.

1993-01-01

At low velocities, the EM field of a particle in a conducting beam tube is no longer a TEM wave, but has a finite longitudinal extent. The net effect of this is to reduce the coupling of the high-frequency Fourier components of the beam current to BPM (beam position monitor) electrodes, which modifies the BPM sensitivity to beam displacement. This effect is especially pronounced for high-frequency, large-aperture pickups used for low-β beams. Non-interceptive beam position monitors used in conjunction with high frequency RFQ (radio-frequency-quadrupole) and DTL (drift-tube-linac) accelerators fall into this category. When testing a BPM with a thin wire excited with either pulses or high-frequency sinusoidal currents, the EM wave represents the principal (TEM) mode in a coaxial transmission line, which is equivalent to a highly relativistic (β = 1) beam. Thus wire measurements are not suitable for simulating slow particle beams in high bandwidth diagnostic devices that couple to the image currents in the beam tube wall. Attempts to load the tin wire either capacitively or inductively to slow the EM wave down have met with limited success. In general, the equations used to represent the 2-D response of cylindrical-geometry BPMs to charged-particle beams make several assumptions: (1) the BPM electrodes are flush with and grounded to the surface of the conducting beam tube; (2) the beam is a line source (pencil beam); (3) the longitudinal extent of the EM field of a beam particle at the beam tube wall is zero, corresponding to a highly relativistic beam. The purpose of this paper is to make some quantitative estimates of the corrections to the conventional approximations when a BPM is used to measure the position of low velocity (low-β) beams