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Sample records for plate ionization chamber

  1. Saturation curves of parallel-plate ionization chambers

    Energy Technology Data Exchange (ETDEWEB)

    Fallone, B.G.; Podgorsak, E.B.

    A new analytical expression is presented to describe the full saturation curve of parallel-plate ionization chambers. In contrast to the presently known expressions, which hold only for the near saturation region, this empirically determined expression is in excellent agreement with measurements in the whole collection efficiency range from 0 to 1 for x-ray sources with effective energies from 20 to 150 keV and cobalt-60 gamma rays. The dependence of the ion collection efficiency and the extrapolated electric field, which is a parameter in the new saturation curve expression, on electric field, dose, dose rate, beam quality, and chamber volume, is discussed. The effect of photoemission from the chamber polarizing electrode for low-energy x-ray beams on the saturation current is demonstrated. A universal ionization chamber constant is derived experimentally. It is shown that all parameters of the saturation curve equation and thus the saturation curve itself, can be calculated from one single measurement of ionization current at a given electric field and air gap thickness.

  2. Characterization tests of a new parallel plate ionization chamber for use in electron beams

    Science.gov (United States)

    Nonato, Fernanda B. C.; Sakuraba, Roberto K.; da Cruz, José Carlos; Caldas, Linda V. E.

    2014-11-01

    Linear accelerators with electron beams are used in several Brazilian hospitals. Consequently, there is an increasing demand for parallel-plate ionization chambers, to be utilized for dosimetry of electron beams. In Brazil, the commercial ionization chambers utilized are imported. The ionization chambers have usually a simple construction, using different materials and geometries. A homemade ionization chamber was developed to be used in electron beams of linear accelerator. The ionization chamber body is made of acrylic and the collecting electrode is painted with graphite powder mixed with nail polish. Several tests were applied, and the results showed values better than the limits established by the international recommendations, except for the polarity effect test, but the response of the developed ionization chamber, for this test, is similar in relation to the response of other commercial ionization chambers from the literature.

  3. Performance of a parallel plate ionization chamber in beta radiation dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Antonio, Patricia L.; Caldas, Linda V.E., E-mail: patrilan@ipen.b, E-mail: lcaldas@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    A homemade parallel plate ionization chamber with graphite collecting electrode, and developed for use in mammography beams, was tested in relation to its usefulness in beta radiation dosimetry at the Calibration Laboratory of IPEN. Characterization tests of this ionization chamber were performed, using the Sr-90 + Y-90, Kr-85 and Pm-147 sources of a beta secondary standard system. The results of saturation, leakage current, stabilization time, response stability, linearity, angular dependence, and calibration coefficients are within the recommended limits of international recommendations that indicate that this chamber may be used for beta radiation dosimetry. (author)

  4. Comparison of absorbed dose to air calibration factors for a parallel plate ionization chamber

    Energy Technology Data Exchange (ETDEWEB)

    Bulla, Roseli T.; Caldas, Linda V.E. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN), Sao Paulo, SP (Brazil)]. E-mail: lcaldas@ipen.br; rtbulla@ig.com.br

    2006-05-15

    Objective: the objective of this study was to compare the absorbed dose to air calibration factors determined in gamma ({sup 60}Co) and electron beams.Objective: an irradiator with a {sup 60}Co source and a Varian, Clinac 2100C linear accelerator with photon and electron beams were utilized. One thimble-type and three parallel-plate ionization chambers were tested. Results: The measurement systems were submitted to preliminary tests (response stability and leakage current), with quite good results. The absorbed dose to air calibration factors were determined using four measurement systems and two types of phantoms. Results were obtained in compliance with the international recommendations.Conclusion: absorbed dose to air calibration factors obtained for parallel plate ionization chambers, determined in {sup 60}Co beams, at maximum, are 1.2% higher than the values obtained in high energy electron beams. (author)

  5. The Time Response of Glass Resistive Plate Chambers to Heavily Ionizing Particles

    CERN Document Server

    Artamonov, A; Bogomilov, M; Booth, C; Borghi, S; Catanesi, M G; Chimenti, P; Gastaldi, Ugo; Giani, S; Graulich, J S; Grégoire, G; Grossheim, A; Guglielmi, A; Ivantchenko, V; Kolev, D; Meurer, C; Mezzetto, M; Panman, J; Popov, B; Radicioni, E; Schroeter, R; Temnikov, P; Chernyaev, E; Tsenov, R; Tsukerman, I; Wiebusch, C

    2007-01-01

    The HARP system of resistive plate chambers (RPCs) was designed to perform particle identification by the measurement of the difference in the time-of-flight of different particles. In previous papers an apparent discrepancy was shown between the response of the RPCs to minimum ionizing pions and heavily ionizing protons. Using the kinematics of elastic scattering off a hydrogen target a controlled beam of low momentum recoil protons was directed onto the chambers. With this method the trajectory and momentum, and hence the time-of-flight of the protons can be precisely predicted without need for a measurement of momentum of the protons. It is demonstrated that the measurement of the time-of-arrival of particles by the thin gas-gap glass RPC system of the HARP experiment depends on the primary ionization deposited by the particle in the detector.

  6. Multi-layered parallel plate ionization chamber for cross-section measurements of minor actinides

    Energy Technology Data Exchange (ETDEWEB)

    Hirose, K., E-mail: hirose@lns.tohoku.ac.j [Research Center for Electron Photon Science, Tohoku University, Sendai 982-0826 (Japan); Ohtsuki, T.; Shibasaki, Y. [Research Center for Electron Photon Science, Tohoku University, Sendai 982-0826 (Japan); Iwasa, N. [Department of Physics, Tohoku University, Sendai 980-8578 (Japan); Hori, J.; Takamiya, K.; Yashima, H. [Research Reactor Institute, Kyoto University, Kumatori-cho, Sennangun, Osaka 590-0494 (Japan); Nishio, K. [Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Kiyanagi, Y. [Graduate School of Engineering, Hokkaido University, Kita-13, Nishi-8, Kita-ku, Sapporo 060-8628 (Japan)

    2010-09-21

    A multi-layered parallel plate ionization chamber (MLPPIC) has been developed for the measurement of neutron-induced fission cross-sections using the lead slowing-down neutron spectrometer at the Research Reactor Institute, Kyoto University. The MLPPIC consists of two sets of multi-layered electrodes to detect fission fragments from two samples located back-to-back between them. The performance of the MLPPIC was tested with a spontaneous fission of {sup 248}Cm. The cross-section for the neutron-induced fission of {sup 241}Am was successfully obtained using that of {sup 235}U as a reference.

  7. Radiation induced currents in parallel plate ionization chambers: measurement and Monte Carlo simulation for megavoltage photon and electron beams.

    Science.gov (United States)

    Abdel-Rahman, Wamied; Seuntjens, Jan P; Verhaegen, Frank; Podgorsak, Ervin B

    2006-09-01

    Polarity effects in ionization chambers are caused by a radiation induced current, also known as Compton current, which arises as a charge imbalance due to charge deposition in electrodes of ionization chambers. We used a phantom-embedded extrapolation chamber (PEEC) for measurements of Compton current in megavoltage photon and electron beams. Electron contamination of photon beams and photon contamination of electron beams have a negligible effect on the measured Compton current. To allow for a theoretical understanding of the Compton current produced in the PEEC effect we carried out Monte Carlo calculations with a modified user code, the COMPTON/ EGSnrc. The Monte Carlo calculated COMPTON currents agree well with measured data for both photon and electron beams; the calculated polarity correction factors, on the other hand, do not agree with measurement results. The conclusions reached for the PEEC can be extended to parallel-plate ionization chambers in general.

  8. Calculation of the charge spectrum generated by ionizing particles in Resistive Plate Chambers at low gas gain

    CERN Document Server

    Fonte, P

    2012-01-01

    The charge spectrum generated by ionizing particles in Resistive Plate Chambers under Townsend avalanche conditions, that is, for sufficiently small avalanches not affected by space-charge, has not been calculated from first principles. In this article it is shown that, just neglecting cluster statistics, it follows closely the statistical gamma distribution. Remarkably, this distribution seems to describe as well data measured beyond these assumptions, rising some interpretation issues.

  9. Determination of the recombination correction for the BIPM parallel-plate ionization chamber type in a pulsed photon beam

    Energy Technology Data Exchange (ETDEWEB)

    Picard, Susanne; Burns, David T. [Bureau International des Poids et Mesures, Pavillon de Breteuil, F92312 Sevres cedex (France); Ostrowsky, Aime [Laboratoire National Henri Becquerel - LNHB, CEA Saclay - 91191 Gif-sur-Yvette Cedex (France)

    2011-09-15

    The correction factor for recombination losses k{sub s} has been determined for the BIPM parallel-plate ionization chamber type in the pulsed photon beam of a clinical linear accelerator. Initial recombination is in agreement with that obtained for the same chamber type in a continuous beam, while linearity in the volume recombination loss is confirmed at dose rates up to 80 pC per pulse, which corresponds to about 0.33 mGy per pulse (or around 2 Gy min{sup -1} at 100 Hz)

  10. Super-resolution non-parametric deconvolution in modelling the radial response function of a parallel plate ionization chamber.

    Science.gov (United States)

    Kulmala, A; Tenhunen, M

    2012-11-07

    The signal of the dosimetric detector is generally dependent on the shape and size of the sensitive volume of the detector. In order to optimize the performance of the detector and reliability of the output signal the effect of the detector size should be corrected or, at least, taken into account. The response of the detector can be modelled using the convolution theorem that connects the system input (actual dose), output (measured result) and the effect of the detector (response function) by a linear convolution operator. We have developed the super-resolution and non-parametric deconvolution method for determination of the cylinder symmetric ionization chamber radial response function. We have demonstrated that the presented deconvolution method is able to determine the radial response for the Roos parallel plate ionization chamber with a better than 0.5 mm correspondence with the physical measures of the chamber. In addition, the performance of the method was proved by the excellent agreement between the output factors of the stereotactic conical collimators (4-20 mm diameter) measured by the Roos chamber, where the detector size is larger than the measured field, and the reference detector (diode). The presented deconvolution method has a potential in providing reference data for more accurate physical models of the ionization chamber as well as for improving and enhancing the performance of the detectors in specific dosimetric problems.

  11. General collection efficiency for liquid isooctane and tetramethylsilane used as sensitive media in a parallel-plate ionization chamber.

    Science.gov (United States)

    Johansson, B; Wickman, G

    1997-01-01

    The general collection efficiency has been measured in liquid isooctane (C8H18) and tetramethylsilane (Si(CH3)4) used as the sensitive media in a parallel-plate ionization chamber, with an electrode distance of 1 mm, intended for photon and electron dosimetry applications. The liquid ionization chamber was irradiated at different dose rates by 140 keV photons from the decay of radioactive 99mTc. The measurements were made at potential differences of 50, 100, 200 and 500 V. Measurements were performed for each liquid and electric field strength, with the decay rate of 99mTc used as the dose-rate reference. The maximum dose rate was about 150 mGy min-1 in each experiment. When the measured general collection efficiency values are compared with the theoretical predictions for collection efficiency in gases, it is found that the latter also describe the general collection efficiency in the two liquids within 1% of the saturation current for collection efficiencies down to 60% when using experimentally determined recombination rate constants and on mobilities characteristic of each of the liquids.

  12. A method to increase the nominal range resolution of a stack of parallel-plate ionization chambers

    Science.gov (United States)

    Rinaldi, I.; Brons, S.; Jäkel, O.; Voss, B.; Parodi, K.

    2014-09-01

    A detector prototype based on a stack of 61 parallel-plate ionisation chambers (PPIC) interleaved with absorber plates of polymethyl methacrylate (PMMA) was assembled for transmission imaging purposes in ion beam therapy. The thickness of the absorber sheets in the PPIC stack determines the nominal range resolution of the detector. In the current set-up, 3 mm PMMA slabs are used. The signal of the 61 active channels of the stack thereby provides a discrete approximation of the Bragg curve in the detector. In this work, a data processing method to increase the range resolution (MIRR) in a stack of ionization chambers is presented. In the MIRR the position of the maximum of the Bragg curve is deduced from the ratio of measured signals in adjacent PPIC channels. The method is developed based on Bragg curves obtained from Monte Carlo simulations and validated with experimental data of a wedge-shaped PMMA phantom acquired with the PPIC stack using carbon ion beams. The influence of the initial beam energy and of phantom inhomogeneities on the MIRR is quantitatively evaluated. Systematic errors as well as inaccuracies related to signal noise are discussed and quantified. It is shown that with the MIRR an increased range resolution of 0.7 mm PMMA equivalent or 0.8 mm water equivalent thickness is achieved for the considered experimental data.

  13. Investigation and performance tests of a new parallel plate ionization chamber with double sensitive volume for measuring diagnostic X-rays

    Science.gov (United States)

    Sharifi, B.; Zamani Zeinali, H.; Soltani, J.; Negarestani, A.; Shahvar, A.

    2015-01-01

    Medical diagnostic equipment, like diagnostic radiology and mammography require a dosimeter with high accuracy for dosimetry of the diagnostic X-ray beam. Ionization chambers are suitable instruments for dosimetry of diagnostic-range X-ray beams because of their appropriate response and high reliability. This work introduces the design and fabrication of a new parallel plate ionization chamber with a PMMA body, graphite-coated PMMA windows (0.5 mm thick) and a graphite-foil central electrode (0.1 mm thick, 0.7 g/cm3 dense). This design improves upon the response characteristics of existing designs through the specific choice of materials as well as the appropriate size and arrangement of the ionization chamber components. The results of performance tests conducted at the Secondary Standard Dosimetry laboratory in Karaj-Iran demonstrated the short and long-term stability, the low leakage current, the low directional dependence, and the high ion collection efficiency of the design. Furthermore, the FLUKA Monte Carlo simulations confirmed the low effect of central electrode on this new ionization chamber response. The response characteristics of the parallel plate ionization chamber presented in this work makes the instrument suitable for use as a standard dosimeter in laboratories.

  14. Investigation and performance tests of a new parallel plate ionization chamber with double sensitive volume for measuring diagnostic X-rays

    Energy Technology Data Exchange (ETDEWEB)

    Sharifi, B., E-mail: babak_sharifi88@yahoo.com [Graduate University of Advanced Technology, Kerman (Iran, Islamic Republic of); Zamani Zeinali, H. [Application of Radiation Research School, Nuclear Science and Technology Research Institute, AEOI, Karaj (Iran, Islamic Republic of); Soltani, J.; Negarestani, A. [Graduate University of Advanced Technology, Kerman (Iran, Islamic Republic of); Shahvar, A. [Application of Radiation Research School, Nuclear Science and Technology Research Institute, AEOI, Karaj (Iran, Islamic Republic of)

    2015-01-11

    Medical diagnostic equipment, like diagnostic radiology and mammography require a dosimeter with high accuracy for dosimetry of the diagnostic X-ray beam. Ionization chambers are suitable instruments for dosimetry of diagnostic-range X-ray beams because of their appropriate response and high reliability. This work introduces the design and fabrication of a new parallel plate ionization chamber with a PMMA body, graphite-coated PMMA windows (0.5 mm thick) and a graphite-foil central electrode (0.1 mm thick, 0.7 g/cm{sup 3} dense). This design improves upon the response characteristics of existing designs through the specific choice of materials as well as the appropriate size and arrangement of the ionization chamber components. The results of performance tests conducted at the Secondary Standard Dosimetry laboratory in Karaj-Iran demonstrated the short and long-term stability, the low leakage current, the low directional dependence, and the high ion collection efficiency of the design. Furthermore, the FLUKA Monte Carlo simulations confirmed the low effect of central electrode on this new ionization chamber response. The response characteristics of the parallel plate ionization chamber presented in this work makes the instrument suitable for use as a standard dosimeter in laboratories.

  15. Characteristics of a miniature parallel-plate free-air ionization chamber for measuring the intensity of synchrotron radiation from an undulator

    Science.gov (United States)

    Nariyama, Nobuteru

    2004-09-01

    In order to develop an absolute intensity monitor for synchrotron radiation from an undulator, the characteristics of a parallel-plate free-air ionization chamber with a plate separation of 4.2 mm, which was considered to be as narrow as possible, were investigated using 8-30 keV monoenergetic photons at SPring-8. Using a Si-PIN photodiode as the reference monitor, saturation was confirmed at 8-30 keV at a photon intensity of an order of 1013 photons/s. The collection efficiency became almost unity at 8 and 10 keV within 3.8% and 1.1%, respectively, which gradually decreased with increasing energy and attained 0.52 at 30 keV because some of the high-energy electrons escaped from the sensitive volume. When the pair of electrodes was transferred from the upper and lower sides to the left and right sides of the beam axis in order to investigate the influence of linear polarization of synchrotron radiation, a decrease in the collection efficiency was observed. Monte Carlo simulations considering linear polarization showed that the plate separation required for no electron loss was 26, 14, and 8 mm for 30, 20, and 15 keV photons, respectively. For 20 keV photons, saturation characteristics were investigated using an ionization chamber with 14 mm plate separation.

  16. Ionization Chamber Measures Extreme Ultraviolet

    Science.gov (United States)

    Carlson, Robert W.

    1987-01-01

    Ionization chamber operates in nearly total photon absorption as stable, self-calibrating detector of ionizing extreme ultraviolet radiation. Working gas of instrument is neon; photoionization properties well known and readily applicable to absolute measurements. Designed for measurements of solar ultraviolet flux aboard sounding rocket, instrument used on Earth to measure ultraviolet radiation in vacuum systems. Ionization chamber collects positive neon ions and electrons produced by irradiation of neon gas by ultraviolet photons. Approximately one ion produced by each photon; consequently, photoionization current nearly proportional to photon flux.

  17. Ionization chambers for LET determination

    DEFF Research Database (Denmark)

    Kaiser, Franz-Joachim; Bassler, Niels; Tölli, Heikki

    2010-01-01

    resolution and high sensitivity are necessary. For exact dosimetry which is done using ionization chambers (ICs), the recombination taking place in the IC has to be known. Up to now, recombination is corrected phenomenologically and more practical approaches are currently used. Nevertheless, Jaff´e's theory...... of columnar recombination was designed to model the detector efficiency of an ionization chamber. Here, we have shown that despite the approximations and simplification made, the theory is correct for the LETs typically found in clinical radiotherapy employing particles from protons to carbon ions...

  18. Improvement of a New Gas Ionization Chamber

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In order to identify heavier elements, we have developed a new longitudinal field gas ionization chamber (IC)with an angle of 30° of plate (as shown in Fig.1). The IC is operated in flowing iso-butane gas at a pressure of 10kPa. After testing by using a 3- component α particle source and comparing with the old longitudinal field

  19. The multigap resistive plate chamber

    Energy Technology Data Exchange (ETDEWEB)

    Zeballos, E. Cerron [European Organization for Nuclear Research (CERN), Geneva (Switzerland); World Lab., Lausanne (Switzerland); Crotty, I. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Hatzifotiadou, D. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); World Lab., Lausanne (Switzerland); Valverde, J. Lamas [European Organization for Nuclear Research (CERN), Geneva (Switzerland); World Lab., Lausanne (Switzerland); Univ. Louis Pasteur, Strasbourg (France); Neupane, S. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); World Lab., Lausanne (Switzerland); Williams, M. C. S. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Zichichi, A. [Univ. of Bologna, Bologna (Italy)

    2015-02-03

    The paper describes the multigap resistive plate chamber (RPC). This is a variant of the wide gap RPC. However it has much improved time resolution, while keeping all the other advantages of the wide gap RPC design.

  20. Conception and realization of a parallel-plate free-air ionization chamber for the absolute dosimetry of an ultrasoft X-ray beam.

    Science.gov (United States)

    Groetz, J-E; Ounoughi, N; Mavon, C; Belafrites, A; Fromm, M

    2014-08-01

    We report the design of a millimeter-sized parallel plate free-air ionization chamber (IC) aimed at determining the absolute air kerma rate of an ultra-soft X-ray beam (E = 1.5 keV). The size of the IC was determined so that the measurement volume satisfies the condition of charged-particle equilibrium. The correction factors necessary to properly measure the absolute kerma using the IC have been established. Particular attention was given to the determination of the effective mean energy for the 1.5 keV photons using the PENELOPE code. Other correction factors were determined by means of computer simulation (COMSOL™ and FLUKA). Measurements of air kerma rates under specific operating parameters of the lab-bench X-ray source have been performed at various distances from that source and compared to Monte Carlo calculations. We show that the developed ionization chamber makes it possible to determine accurate photon fluence rates in routine work and will constitute substantial time-savings for future radiobiological experiments based on the use of ultra-soft X-rays.

  1. Conception and realization of a parallel-plate free-air ionization chamber for the absolute dosimetry of an ultrasoft X-ray beam

    Energy Technology Data Exchange (ETDEWEB)

    Groetz, J.-E., E-mail: jegroetz@univ-fcomte.fr; Mavon, C.; Fromm, M. [Laboratoire Chrono-Environnement, UMR CNRS 6249, Université de Franche-Comté, 16 route de Gray, 25030 Besançon Cedex (France); Ounoughi, N. [Laboratoire Chrono-Environnement, UMR CNRS 6249, Université de Franche-Comté, 16 route de Gray, 25030 Besançon Cedex (France); Laboratoire de Physique des Rayonnements et Applications, Université de Jijel, B.P. 98 Ouled Aissa, Jijel 18000 (Algeria); Belafrites, A. [Laboratoire de Physique des Rayonnements et Applications, Université de Jijel, B.P. 98 Ouled Aissa, Jijel 18000 (Algeria)

    2014-08-15

    We report the design of a millimeter-sized parallel plate free-air ionization chamber (IC) aimed at determining the absolute air kerma rate of an ultra-soft X-ray beam (E = 1.5 keV). The size of the IC was determined so that the measurement volume satisfies the condition of charged-particle equilibrium. The correction factors necessary to properly measure the absolute kerma using the IC have been established. Particular attention was given to the determination of the effective mean energy for the 1.5 keV photons using the PENELOPE code. Other correction factors were determined by means of computer simulation (COMSOL™and FLUKA). Measurements of air kerma rates under specific operating parameters of the lab-bench X-ray source have been performed at various distances from that source and compared to Monte Carlo calculations. We show that the developed ionization chamber makes it possible to determine accurate photon fluence rates in routine work and will constitute substantial time-savings for future radiobiological experiments based on the use of ultra-soft X-rays.

  2. Conception and realization of a parallel-plate free-air ionization chamber for the absolute dosimetry of an ultrasoft X-ray beam

    Science.gov (United States)

    Groetz, J.-E.; Ounoughi, N.; Mavon, C.; Belafrites, A.; Fromm, M.

    2014-08-01

    We report the design of a millimeter-sized parallel plate free-air ionization chamber (IC) aimed at determining the absolute air kerma rate of an ultra-soft X-ray beam (E = 1.5 keV). The size of the IC was determined so that the measurement volume satisfies the condition of charged-particle equilibrium. The correction factors necessary to properly measure the absolute kerma using the IC have been established. Particular attention was given to the determination of the effective mean energy for the 1.5 keV photons using the PENELOPE code. Other correction factors were determined by means of computer simulation (COMSOL™and FLUKA). Measurements of air kerma rates under specific operating parameters of the lab-bench X-ray source have been performed at various distances from that source and compared to Monte Carlo calculations. We show that the developed ionization chamber makes it possible to determine accurate photon fluence rates in routine work and will constitute substantial time-savings for future radiobiological experiments based on the use of ultra-soft X-rays.

  3. A new ring-shaped graphite monitor ionization chamber

    Science.gov (United States)

    Yoshizumi, M. T.; Caldas, L. V. E.

    2010-07-01

    A ring-shaped monitor ionization chamber was developed at the Instituto de Pesquisas Energéticas e Nucleares. This ionization chamber presents an entrance window of aluminized polyester foil. The guard ring and collecting electrode are made of graphite coated Lucite plates. The main difference between this new ionization chamber and commercial monitor chambers is its ring-shaped design. The new monitor chamber has a central hole, allowing the passage of the direct radiation beam without attenuation; only the penumbra radiation is measured by the sensitive volume. This kind of ionization chamber design has already been tested, but using aluminium electrodes. By changing the electrode material from aluminium to a graphite coating, an improvement in the chamber response stability was expected. The pre-operational tests, as saturation curve, recombination loss and polarity effect showed satisfactory results. The repeatability and the long-term stability tests were also evaluated, showing good agreement with international recommendations.

  4. A new ring-shaped graphite monitor ionization chamber

    Energy Technology Data Exchange (ETDEWEB)

    Yoshizumi, M.T., E-mail: mairaty@ipen.b [Instituto de Pesquisas Energeticas e Nucleares IPEN - CNEN/SP, Av. Prof. Lineu Prestes 2242, 05508-000, Sao Paulo-SP (Brazil); Caldas, L.V.E., E-mail: lcaldas@ipen.b [Instituto de Pesquisas Energeticas e Nucleares IPEN - CNEN/SP, Av. Prof. Lineu Prestes 2242, 05508-000, Sao Paulo-SP (Brazil)

    2010-07-21

    A ring-shaped monitor ionization chamber was developed at the Instituto de Pesquisas Energeticas e Nucleares. This ionization chamber presents an entrance window of aluminized polyester foil. The guard ring and collecting electrode are made of graphite coated Lucite plates. The main difference between this new ionization chamber and commercial monitor chambers is its ring-shaped design. The new monitor chamber has a central hole, allowing the passage of the direct radiation beam without attenuation; only the penumbra radiation is measured by the sensitive volume. This kind of ionization chamber design has already been tested, but using aluminium electrodes. By changing the electrode material from aluminium to a graphite coating, an improvement in the chamber response stability was expected. The pre-operational tests, as saturation curve, recombination loss and polarity effect showed satisfactory results. The repeatability and the long-term stability tests were also evaluated, showing good agreement with international recommendations.

  5. Loss of ions in cavity ionization chambers

    Energy Technology Data Exchange (ETDEWEB)

    Takata, N. [Ionizing Radiation Section, NMIJ/AIST, Tsukuba 305-8568 (Japan)]. E-mail: n.takata@aist.go.jp; Tran, N.T. [Institute for Nuclear Science and Technique, VAEC, Hanoi (Viet Nam); Kim, E. [Radiation Safety Section, NIRS, Inageku, Chiba-city 263-8555 (Japan); Marsoem, P. [P3KRBiN-BATAN, JL Cinere-Pasar Jum' at, Jakarta 12070 (Indonesia); Kurosawa, T. [Ionizing Radiation Section, NMIJ/AIST, Tsukuba 305-8568 (Japan); Koyama, Y. [Ionizing Radiation Section, NMIJ/AIST, Tsukuba 305-8568 (Japan)

    2005-12-01

    Ion losses due to initial recombination, volume recombination, and back diffusion were each determined by measurements and calculations for different size cylindrical ionization chambers and spherical ionization chambers. By measuring signal currents from these ionization chambers irradiated with {sup 60}Co gamma rays, two groups of ion losses were obtained. (Group 1) Ion loss due to initial recombination and diffusion, which changes proportionally to the inverse of the voltage applied to the ionization chambers; (and group 2) ion loss due to volume recombination, which changes proportionally to the inverse of the square of the applied voltage. The diffusion loss was obtained separately by computing electric field distributions in the ionization chambers. It was found that diffusion loss is larger than initial recombination loss for the cylindrical ionization chambers and vise versa for the spherical ionization chambers.

  6. Surface and buildup region dose measurements with Markus parallel-plate ionization chamber, Gafchromic EBT3 film and MOSFET detector for high energy photon beams

    CERN Document Server

    Akbas, Ugur; Koksal, Canan; Bilge, Hatice

    2016-01-01

    The aim of the study was to investigate surface and buildup region doses for 6 MV photon beams using a Markus parallel-plate ionization chamber, GafChromic EBT3 film and MOSFET detector for different field sizes and beam angles. The measurements were made in a water equivalent solid phantom at the surface and in the buildup region of the 6 MV photon beams at 100 cm source-detector distance (SDD) for 5x5, 10x10 and 20x20 cm2 field sizes and 0, 30, 60, 80 and 90 beam angles. The surface doses for 10x10 cm2 field size were found to be 20.33%, 18.80% and 25.48% for Markus chamber, EBT3 film and MOSFET detector, respectively. The surface dose increased with field size for all dosimeters. As the angle of the incident radiation beam became more oblique, the surface dose increased. The effective measurement depths of dosimeters vary, thus the results of the measurements could be different. This issue can lead to mistakes at surface and buildup dosimetry, and must be taken into account.

  7. Surface and Buildup Region Dose Measurements with Markus Parallel-Plate Ionization Chamber, GafChromic EBT3 Film, and MOSFET Detector for High-Energy Photon Beams

    Directory of Open Access Journals (Sweden)

    Ugur Akbas

    2016-01-01

    Full Text Available The aim of the study was to investigate surface and buildup region doses for 6 MV and 15 MV photon beams using a Markus parallel-plate ionization chamber, GafChromic EBT3 film, and MOSFET detector for different field sizes and beam angles. The measurements were made in a water equivalent solid phantom at the surface and in the buildup region of the 6 MV and 15 MV photon beams at 100 cm source-detector distance for 5 × 5, 10 × 10, and 20 × 20 cm2 field sizes and 0°, 30°, 60°, and 80° beam angles. The surface doses using 6 MV photon beams for 10 × 10 cm2 field size were found to be 20.3%, 18.8%, and 25.5% for Markus chamber, EBT3 film, and MOSFET detector, respectively. The surface doses using 15 MV photon beams for 10 × 10 cm2 field size were found to be 14.9%, 13.4%, and 16.4% for Markus chamber, EBT3 film, and MOSFET detector, respectively. The surface dose increased with field size for all dosimeters. As the angle of the incident radiation beam became more oblique, the surface dose increased. The effective measurement depths of dosimeters vary; thus, the results of the measurements could be different. This issue can lead to mistakes at surface and buildup dosimetry and must be taken into account.

  8. An ionization chamber with magnetic levitated electrodes

    CERN Document Server

    Kawaguchi, T

    1999-01-01

    A new type of ionization chamber which has magnetically levitated electrodes has been developed. The electrodes are supplied voltages for the repelling of ions by a battery which is also levitated with the electrodes. The characteristics of this ionization chamber are investigated in this paper.

  9. Multi-anode ionization chamber

    Energy Technology Data Exchange (ETDEWEB)

    Bolotnikov, Aleksey E. (South Setauket, NY); Smith, Graham (Port Jefferson, NY); Mahler, George J. (Rocky Point, NY); Vanier, Peter E. (Setauket, NY)

    2010-12-28

    The present invention includes a high-energy detector having a cathode chamber, a support member, and anode segments. The cathode chamber extends along a longitudinal axis. The support member is fixed within the cathode chamber and extends from the first end of the cathode chamber to the second end of the cathode chamber. The anode segments are supported by the support member and are spaced along the longitudinal surface of the support member. The anode segments are configured to generate at least a first electrical signal in response to electrons impinging thereon.

  10. Gridded Ionization Chambers for Time Resolved X-Ray Absorption Spectroscopy

    Science.gov (United States)

    Müller, O.; Stötzel, J.; Lützenkirchen-Hecht, D.; Frahm, R.

    2013-03-01

    Common parallel plate ionization chambers are bandwidth limited by the ion drift velocity. Therefore they can severely decrease the effective energy resolution of time resolved EXAFS or XANES spectra. We therefore developed gridded ionization chambers which suppress the ionic component of the ionization current, which results in a substantial improvement of its bandwidth of typically two orders of magnitude. The rise time of these chambers is measured to be less than 5.5 μs. We have investigated the step response of parallel plate and gridded ionization chambers and discuss their influence on QEXAFS spectra.

  11. Classification of the LHC BLM Ionization Chamber

    CERN Document Server

    Stockner, M; Fabjan, Christian Wolfgang; Holzer, E B; Kramer, Daniel

    2008-01-01

    The LHC beam loss monitoring (BLM) system must prevent the super conducting magnets from quenching and protect the machine components from damage. The main monitor type is an ionization chamber. About 4000 of them will be installed around the ring. The lost beam particles initiate hadronic showers through the magnets and other machine components. These shower particles are measured by the monitors installed on the outside of the accelerator equipment. For the calibration of the BLM system the signal response of the ionization chamber is simulated in GEANT4 for all relevant particle types and energies (keV to TeV range). For validation, the simulations are compared to measurements using protons, neutrons, photons and mixed radiation fields at various energies and intensities. This paper will focus on the signal response of the ionization chamber to various particle types and energies including space charge effects at high ionization densities.

  12. Detailed models for timing and efficiency in resistive plate chambers

    CERN Document Server

    Riegler, Werner

    2003-01-01

    We discuss detailed models for detector physics processes in Resistive Plate Chambers, in particular including the effect of attachment on the avalanche statistics. In addition, we present analytic formulas for average charges and intrinsic RPC time resolution. Using a Monte Carlo simulation including all the steps from primary ionization to the front-end electronics we discuss the dependence of efficiency and time resolution on parameters like primary ionization, avalanche statistics and threshold.

  13. The GODDESS ionization chamber: developing robust windows

    Science.gov (United States)

    Blanchard, Rose; Baugher, Travis; Cizewski, Jolie; Pain, Steven; Ratkiewicz, Andrew; Goddess Collaboration

    2015-10-01

    Reaction studies of nuclei far from stability require high-efficiency arrays of detectors and the ability to identify beam-like particles, especially when the beam is a cocktail beam. The Gammasphere ORRUBA Dual Detectors for Experimental Structure Studies (GODDESS) is made up of the Oak Ridge-Rutgers University Barrel Array (ORRUBA) of silicon detectors for charged particles inside of the gamma-ray detector array Gammasphere. A high-rate ionization chamber is being developed to identify beam-like particles. Consisting of twenty-one alternating anode and cathode grids, the ionization chamber sits downstream of the target chamber and is used to measure the energy loss of recoiling ions. A critical component of the system is a thin and robust mylar window which serves to separate the gas-filled ionization chamber from the vacuum of the target chamber with minimal energy loss. After construction, windows were tested to assure that they would not break below the required pressure, causing harm to the wire grids. This presentation will summarize the status of the ionization chamber and the results of the first tests with beams. This work is supported in part by the U.S. Department of Energy and National Science Foundation.

  14. Making MUSIC: A multiple sampling ionization chamber

    Energy Technology Data Exchange (ETDEWEB)

    Shumard, B. [Argonne National Laboratory, Building 203 H-113, Argonne, IL 60439 (United States)]. E-mail: shumard@phy.anl.gov; Henderson, D.J. [Argonne National Laboratory, Building 203 H-113, Argonne, IL 60439 (United States); Rehm, K.E. [Argonne National Laboratory, Building 203 H-113, Argonne, IL 60439 (United States); Tang, X.D. [Argonne National Laboratory, Building 203 H-113, Argonne, IL 60439 (United States)

    2007-08-15

    A multiple sampling ionization chamber (MUSIC) was developed for use in conjunction with the Atlas scattering chamber (ATSCAT). This chamber was developed to study the ({alpha}, p) reaction in stable and radioactive beams. The gas filled ionization chamber is used as a target and detector for both particles in the outgoing channel (p + beam particles for elastic scattering or p + residual nucleus for ({alpha}, p) reactions). The MUSIC detector is followed by a Si array to provide a trigger for anode events. The anode events are gated by a gating grid so that only ({alpha}, p) reactions where the proton reaches the Si detector result in an anode event. The MUSIC detector is a segmented ionization chamber. The active length of the chamber is 11.95 in. and is divided into 16 equal anode segments (3.5 in. x 0.70 in. with 0.3 in. spacing between pads). The dead area of the chamber was reduced by the addition of a Delrin snout that extends 0.875 in. into the chamber from the front face, to which a mylar window is affixed. 0.5 in. above the anode is a Frisch grid that is held at ground potential. 0.5 in. above the Frisch grid is a gating grid. The gating grid functions as a drift electron barrier, effectively halting the gathering of signals. Setting two sets of alternating wires at differing potentials creates a lateral electric field which traps the drift electrons, stopping the collection of anode signals. The chamber also has a reinforced mylar exit window separating the Si array from the target gas. This allows protons from the ({alpha}, p) reaction to be detected. The detection of these protons opens the gating grid to allow the drift electrons released from the ionizing gas during the ({alpha}, p) reaction to reach the anode segment below the reaction.

  15. Liquid ionization chambers for LET determination

    DEFF Research Database (Denmark)

    Kaiser, Franz-Joachim; Bassler, Niels; Tölli, Heikki

    Liquid ionization chambers [1] (LICs) have have been used in the last decades as background dosemeters. Since a few years LICs are also commercially available for dosimetry and are used for measurements of dose distributions where a high spatial distribution is necessary. Also in the last decades...

  16. Precision electronics for ionization chamber measurements

    Energy Technology Data Exchange (ETDEWEB)

    Santry, D.C.; Bowes, G.C.; Munzenmayer, K.

    1987-01-01

    By using commercially available units, an electrometer and an IBM personal computer, it was relatively inexpensive and simple to assemble a system which permits ..gamma..-ray-emitting radionuclide activities to be measured in an ionization chamber with an uncertainty of + - 0.5% and a reproducibility of + - 0.05%.

  17. IKAR, a ionization chamber for WA9

    CERN Document Server

    1976-01-01

    This ionization chamber arrived at CERN from Leningrad for a high precision study of hadron elastic scattering by a CERN-Clermont-Ferrand-Leningrad-Lyon-Uppsala Collaboration in the H3 beam (WA9). G.A. Korolev (third from right) looks at the drawings.

  18. 基于微通道板的电离室及其在同步辐射中的应用%Ionization chamber based on multichannel plate and its application on synchrotron radiation

    Institute of Scientific and Technical Information of China (English)

    李俊琴; 邹鹰; 陈振华; 薛莲; 王勇; 邰仁忠

    2016-01-01

    Background: The measurement of energy resolution is an essential task for commissioning a beamline in synchrotron radiation facility. The ionization chamber plays an important role in the evaluation of energy resolution. The conventional type based on electrode probe has the disadvantage of a low detection upper limit for energy resolution due to collision broadening on peak profiles by high working pressure (up to 1.33Pa). Purpose: To improve the upper limit of resolution measurement, we aim to set up and deploy the ionization chamber based on multichannel plate (MCP) in China, including vacuum system, gas inlet system, detection system and data acquisition and processing system.Methods: Taking advantage of high amplification of a MCP detector, gas ionization absorption spectra can be measured under much low working pressure (1.33×10−4Pa). By analyzing the width of absorption peak, the instrument broadening caused by a beam line can be obtained.Results: An ionization chamber based on MCP can achieve higher upper limit than those based on electrode probe in evaluating energy resolution. Conclusion: A MCP ionization chamber provides an important diagnosis for energy resolution in commissioning high performance beamlines.%在同步辐射装置中,气体电离室是定标光束线能量和评估能量分辨率的一个重要实验装置。为了摆脱电极探针式电离室的气体展宽对束线能量分辨率测定的限制,本文将微通道板(Microchannel Plate, MCP)应用于同步辐射光束线中的电离室,研制成功了具有高能量分辨率的电离吸收谱的探测系统。利用此系统测量标准气体在X射线入射时的电离吸收谱,通过分析测量所得谱线中吸收峰的展宽,可获得光束线的仪器展宽,本文以Ar的吸收谱为例给出了测量结果。

  19. Resistive plate chambers for tomography and radiography

    National Research Council Canada - National Science Library

    C. Thomay; P. Baesso; D. Cussans; J. Davies; P. Glaysher; S. Quillin; S. Robertson; C. Steer; C. Vassallo; J. Velthuis

    2012-01-01

    Resistive Plate Chambers (RPCs) are widely used in high energy physics for both tracking and triggering purposes, due to their excellent time resolution, rate capability, and good spatial resolution...

  20. Investigation of electric field distribution on FAC-IR-300 ionization chamber

    Science.gov (United States)

    Mohammadi, S. M.; Tavakoli-Anbaran, H.; Zeinali, H. Z.

    2016-07-01

    One of the important parameters for establishing charge particle equilibrium (CPE) conditions of free-air ionization chamber is an electric field distribution. In this paper, electric field distribution inside the ionization chamber was investigated by finite element method. For this purpose, the effects of adding guard plate and guard strips on the electric field distribution in the ionization chamber were studied. it is necessary to apply a lead box around the ionization chamber body to avoid of scattered radiation effects on the ionization chamber operation, but the lead box changes the electric field distribution. In the following, the effect of lead box on the electric field distribution was studied. Finally, electric field distribution factor (kfield) was calculated by the simulation. The results of the simulation showed that presence of the guard plate and guard strips, and applying a suitable potential to lead box, a convergence of kfield to 1 was achieved.

  1. Free-air ionization chamber, FAC-IR-300, designed for medium energy X-ray dosimetry

    Science.gov (United States)

    Mohammadi, S. M.; Tavakoli-Anbaran, H.; Zeinali, H. Z.

    2017-01-01

    The primary standard for X-ray photons is based on parallel-plate free-air ionization chamber (FAC). Therefore, the Atomic Energy Organization of Iran (AEOI) is tried to design and build the free-air ionization chamber, FAC-IR-300, for low and medium energy X-ray dosimetry. The main aim of the present work is to investigate specification of the FAC-IR-300 ionization chamber and design it. FAC-IR-300 dosimeter is composed of two parallel plates, a high voltage (HV) plate and a collector plate, along with a guard electrode that surrounds the collector plate. The guard plate and the collector were separated by an air gap. For obtaining uniformity in the electric field distribution, a group of guard strips was used around the ionization chamber. These characterizations involve determining the exact dimensions of the ionization chamber by using Monte Carlo simulation and introducing correction factors.

  2. LET measurements with a liquid ionization chamber

    Energy Technology Data Exchange (ETDEWEB)

    Tegami, Sara

    2013-02-08

    Deep-seated tumors can be efficiently treated with heavy charged particles. The characteristic depth dose profile inside the tissue (Bragg peak) allows to deliver a high dose inside the tumor, while sparing the neighboring healthy tissue. As compared to protons, heavy ions like carbon or oxygen produce a higher amount of ionization events along their track (and in particular at the end of the ion beam path), resulting in an irreparable damage to the DNA of the tumor cells. The density of such ionization events is described in terms of Linear Energy Transfer (LET), an important physical quantity, but difficult to be measured directly. The aim of this work is to determine LET of hadrontherapy beams by using Liquid Ionization Chambers (LIC). The ionization signal in LICs is affected by recombination effects that depend on the LET of the incident radiation. Differences in recombination effects in LICs and air-filled ionization chambers can be exploited to obtain the recombination index, which can be related to the LET, calculated by Monte Carlo methods. We thus developed a method to construct a calibration curve, which relates the recombination index with the LET at each depth in water. The result of this work can be used for online monitoring of the ion beam quality.

  3. Smart ionization chamber for gamma-ray monitoring

    OpenAIRE

    Drndarević Vujo R.; Jevtić Nenad J.; Rajović Vladimir M.; Stanković Srboljub J.

    2014-01-01

    A design and implementation of a smart ionization chamber suitable for connection into gamma radiation monitoring networks is presented in this paper. The smart ionization chamber consists of air-equivalent one liter ionization chamber with associated electronics and a built-in memory for storage of electronic data specifications. Generally, operating and measurement characteristics of the used ionization chamber are written into the memory chip attached to...

  4. Characterization tests and application of special ionization chambers in standard mammography beams

    Energy Technology Data Exchange (ETDEWEB)

    Honda, Cristiane J.C.; Caldas, Linda V.E., E-mail: cristianehonda@usp.br, E-mail: lcaldas@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Silva, Jonas O., E-mail: jonas.silva@ufg.br [Universidade Federal de Goias (UFG), Goiania, GO (Brazil). Instituto de Fisica

    2015-07-01

    The most used instrument for quality assurance programs in mammography beams is the ionization chamber. At the Calibration Laboratory of IPEN three different ionization chambers were recently designed and assembled for dosimetry in standard mammography beams. These ionization chambers are parallel plate chambers, with different geometries. The objective of this work was to study the performance of all three ionization chambers in relation to a commercial one. The established standard beams at an industrial X-ray system Pantak-Seifert were used for the characterization tests of the ionization chambers as short- and medium-term stability, saturation curves, polarity effect, ion collection efficiency, response linearity and angular dependence. All of the results obtained were within the limits recommended by the international standards IEC 61674 and IEC 60731. (author)

  5. Calibration of a pencil ionization chamber with and without preamplifier

    OpenAIRE

    Maia, Ana Figueiredo

    2004-01-01

    The pencil ionization chamber is a cylindrical dosimeter developed for computed tomography beams. Many kinds of ionization chambers have a preamplifier connected to the chamber to make it electrically more stable, specially for field instruments. In this study, the performance of a Victoreen pencil ionization chamber with the original preamplifier and after its removal was compared. The objective of the preamplifier removal was to enable connecting the chamber to other kinds of electromete...

  6. Study of the response of low pressure ionization chambers

    CERN Document Server

    Nebot Del Busto, E; Effinger, E; Grishin, V; Herranz Alvarez, J

    2012-01-01

    The Beam Loss Monitoring System (BLM) of the Large Hadron Collider (LHC) is based on parallel plate Ionization Chambers (IC) with active volume 1.5l and a nitrogen filling gas at 0.1 bar overpressure. At the largest loss locations, the ICs generate signals large enough to saturate the read-out electronics. A reduction of the active volume and filling pressure in the ICs would decrease the amount of charge collected in the electrodes, and so provide a higher saturation limit using the same electronics. This makes Little Ionization Chambers (LIC) with both reduced pressure and small active volume a good candidate for these high radiation areas. In this contribution we present measurements performed with several LIC monitors with reduced active volume and various filling pressures. These detectors were tested under various conditions with different beam setups, with standard LHC ICs used for calibration purposes

  7. Nuclear Fission Investigation with Twin Ionization Chamber

    Science.gov (United States)

    Zeynalova, O.; Zeynalov, Sh.; Nazarenko, M.; Hambsch, F.-J.; Oberstedt, S.

    2011-11-01

    The purpose of the present paper was to report the recent results, obtained in development of digital pulse processing mathematics for prompt fission neutron (PFN) investigation using twin ionization chamber (TIC) along with fast neutron time-of-flight detector (ND). Due to well known ambiguities in literature (see refs. [4, 6, 9 and 11]), concerning a pulse induction on TIC electrodes by FF ionization, we first presented detailed mathematical analysis of fission fragment (FF) signal formation on TIC anode. The analysis was done using Ramo-Shockley theorem, which gives relation between charged particle motion between TIC electrodes and so called weighting potential. Weighting potential was calculated by direct numerical solution of Laplace equation (neglecting space charge) for the TIC geometry and ionization, caused by FF. Formulae for grid inefficiency (GI) correction and digital pulse processing algorithms for PFN time-of-flight measurements and pulse shape analysis are presented and discussed.

  8. Ionization Chamber for Prompt Fission Neutron Investigations

    OpenAIRE

    ZEYNALOV Sh.; ZEYNALOVA O. V.; Hambsch, Franz-Josef; Sedyshev, P.; SHVETSOV V.

    2014-01-01

    In this work we report recent achievements in design of twin back-to-back ionization chamber (TIC) for fission fragment (FF) mass and kinetic energy measurement. Correlated FF kinetic energies, their masses and the angle of FF in respect to the axes in 3D Cartesian coordinates can be determined from analysis of the heights and shapes of the pulses induced by the fission fragments on the anodes of TIC. Anodes of TIC were designed as consisting of isolated strips each having independent electro...

  9. Smart ionization chamber for gamma-ray monitoring

    Directory of Open Access Journals (Sweden)

    Drndarević Vujo R.

    2014-01-01

    Full Text Available A design and implementation of a smart ionization chamber suitable for connection into gamma radiation monitoring networks is presented in this paper. The smart ionization chamber consists of air-equivalent one liter ionization chamber with associated electronics and a built-in memory for storage of electronic data specifications. Generally, operating and measurement characteristics of the used ionization chamber are written into the memory chip attached to the chamber. A microcontroller-based data acquisition system with a mixed-mode interface has been implemented for the purpose of reading electronic data specifications from the memory chip, and for configuration and interfacing of the ionization chamber to the monitoring network using plug-and-play concept. The details of smart ionization chamber implementation and test results are included in the paper. [Projekat Ministarstva nauke Republike Srbije, br. TR36047 i br. TR32043

  10. Characterization of a homemade ionization chamber for radiotherapy beams.

    Science.gov (United States)

    Neves, Lucio P; Perini, Ana P; dos Santos, Gelson P; Xavier, Marcos; Khoury, Helen J; Caldas, Linda V E

    2012-07-01

    A homemade cylindrical ionization chamber was studied for routine use in therapy beams of (60)Co and X-rays. Several characterization tests were performed: leakage current, saturation, ion collection efficiency, polarity effect, stability, stabilization time, chamber orientation and energy dependence. All results obtained were within international recommendations. Therefore the homemade ionization chamber presents usefulness for routine dosimetric procedures in radiotherapy beams.

  11. Experimental and Monte Carlo evaluation of an ionization chamber in a 60Co beam

    Science.gov (United States)

    Perini, A. P.; Neves, L. P.; Santos, W. S.; Caldas, L. V. E.

    2016-07-01

    Recently a special parallel-plate ionization chamber was developed and characterized at the Instituto de Pesquisas Energeticas e Nucleares. The operational tests presented results within the recommended limits. In order to determine the influence of some components of the ionization chamber on its response, Monte Carlo simulations were carried out. The experimental and simulation results pointed out that the dosimeter evaluated in the present work has favorable properties to be applied to 60Co dosimetry at calibration laboratories.

  12. Experimental and Monte Carlo evaluation of an ionization chamber in a {sup 60}Co beam

    Energy Technology Data Exchange (ETDEWEB)

    Perini, Ana P.; Neves, Lucio Pereira, E-mail: anapaula.perini@ufu.br [Universidade Federal de Uberlandia (INFIS/UFU), MG (Brazil). Instituto de Fisica; Santos, William S.; Caldas, Linda V.E. [Instituto de Pesquisas Energeticas e Nucleres (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    Recently a special parallel-plate ionization chamber was developed and characterized at the Instituto de Pesquisas Energeticas e Nucleares. The operational tests presented results within the recommended limits. In order to determine the influence of some components of the ionization chamber on its response, Monte Carlo simulations were carried out. The experimental and simulation results pointed out that the dosimeter evaluated in the present work has favorable properties to be applied to {sup 60}Co dosimetry at calibration laboratories. (author)

  13. Current-voltage characteristic of parallel-plane ionization chamber with inhomogeneous ionization

    Energy Technology Data Exchange (ETDEWEB)

    Stoyanov, D G [Faculty of Engineering and Pedagogy in Sliven, Technical University of Sofia, 59, Bourgasko Shaussee Blvd, 8800 Sliven (Bulgaria)

    2007-08-15

    The balances of particles and charges in the volume of parallel-plane ionization chamber are considered. Differential equations describing the distribution of current densities in the chamber volume are obtained. As a result of the differential equations solution an analytical form of the current-voltage characteristic of parallel-plane ionization chamber with inhomogeneous ionization in the volume is obtained.

  14. Current-voltage characteristic of parallel-plane ionization chamber with inhomogeneous ionization

    CERN Document Server

    Stoyanov, Dimitar G

    2007-01-01

    The balances of particles and charges in the volume of parallel-plane ionization chamber are considered. Differential equations describing the distribution of current densities in the chamber volume are obtained. As a result of the differential equations solution an analytical form of the current-voltage characteristic of parallel-plane ionization chamber with inhomogeneous ionization in the volume is got.

  15. Monte Carlo calculation of energy deposition in ionization chambers for tritium measurements

    Science.gov (United States)

    Zhilin, Chen; Shuming, Peng; Dan, Meng; Yuehong, He; Heyi, Wang

    2014-10-01

    Energy deposition in ionization chambers for tritium measurements has been theoretically studied using Monte Carlo code MCNP 5. The influence of many factors, including carrier gas, chamber size, wall materials and gas pressure, has been evaluated in the simulations. It is found that β rays emitted by tritium deposit much more energy into chambers flowing through with argon than with deuterium in them, as much as 2.7 times higher at pressure 100 Pa. As chamber size gets smaller, energy deposition decreases sharply. For an ionization chamber of 1 mL, β rays deposit less than 1% of their energy at pressure 100 Pa and only 84% even if gas pressure is as high as 100 kPa. It also indicates that gold plated ionization chamber results in the highest deposition ratio while aluminum one leads to the lowest. In addition, simulations were validated by comparison with experimental data. Results show that simulations agree well with experimental data.

  16. Angular resolution of stacked resistive plate chambers

    CERN Document Server

    Samuel, Deepak; Murgod, Lakshmi P

    2016-01-01

    We present here detailed derivations of mathematical expressions for the angular resolution of a set of stacked resistive plate chambers (RPCs). The expressions are validated against experimental results using data collected from the prototype detectors (without magnet) of the upcoming India-based Neutrino Observatory (INO). In principle, these expressions can be used for any other detector with an architecture similar to that of RPCs.

  17. Development and progress in resistive plate chamber

    Institute of Scientific and Technical Information of China (English)

    CHEN Hong-Fang; WU Jian

    2004-01-01

    Resistive Plate Chamber (RPC) is a robust and low cost gas detector, which is extensively used in high-energy physics, cosmic and astroparticle physics experiments. Over the past twenty years, as a particle detector,RPC has made remarkable progress. The main achievements, features and results of experiemantal tests including R&D and production of the RPCs by several Chinese groups in recent years are reported in this article.

  18. Performance of the ATLAS resistive plate chambers

    Energy Technology Data Exchange (ETDEWEB)

    Cattani, Giordano, E-mail: giordano.cattani@cern.ch [INFN and University of Rome & #x27; Tor Vergata& #x27; , via della Ricerca Scientifica, 1 00133 Rome (Italy)

    2012-01-01

    An overview and results of the effort to monitor and measure the relevant quantities of the Resistive Plate Chamber detectors are presented, addressing in particular three aspects. First, the full exploitation of the high-precision tracking provided by ATLAS Monitored Drift Tubes when measuring the performance of the RPCs. Second, the use of a dedicated data stream to achieve the required statistics. Last, the central role of GRID facilities in providing the necessary computing resources.

  19. Monte Carlo Simulation Optimizing Design of Grid Ionization Chamber

    Institute of Scientific and Technical Information of China (English)

    ZHENG; Yu-lai; WANG; Qiang; YANG; Lu

    2013-01-01

    The grid ionization chamber detector is often used for measuring charged particles.Based on Monte Carlo simulation method,the energy loss distribution and electron ion pairs of alpha particle with different energy have been calculated to determine suitable filling gas in the ionization chamber filled with

  20. High counting rate resistive-plate chamber

    Science.gov (United States)

    Peskov, V.; Anderson, D. F.; Kwan, S.

    1993-05-01

    Parallel-plate avalanche chambers (PPAC) are widely used in physics experiments because they are fast (less than 1 ns) and have very simple construction: just two parallel metallic plates or mesh electrodes. Depending on the applied voltage they may work either in spark mode or avalanche mode. The advantage of the spark mode of operation is a large signal amplitude from the chamber, the disadvantage is that there is a large dead time (msec) for the entire chamber after an event. The main advantage of the avalanche mode is high rate capability 10(exp 5) counts/mm(sup 2). A resistive-plate chamber (RPC) is similar to the PPAC in construction except that one or both of the electrodes are made from high resistivity (greater than 10(exp 10) Omega(cm) materials. In practice RPC's are usually used in the spark mode. Resistive electrodes are charged by sparks, locally reducing the actual electric field in the gap. The size of the charged surface is about 10 mm(sup 2), leaving the rest of the detector unaffected. Therefore, the rate capability of such detectors in the spark mode is considerably higher than conventional spark counters. Among the different glasses tested the best results were obtained with electron type conductive glasses, which obey Ohm's law. Most of the work with such glasses was done with high pressure parallel-plate chambers (10 atm) for time-of-flight measurements. Resistive glasses have been expensive and produced only in small quantities. Now resistive glasses are commercially available, although they are still expensive in small scale production. From the positive experience of different groups working with the resistive glasses, it was decided to review the old idea to use this glass for the RPC. This work has investigated the possibility of using the RPC at 1 atm and in the avalanche mode. This has several advantages: simplicity of construction, high rate capability, low voltage operation, and the ability to work with non-flammable gases.

  1. Simulation of the CMS Resistive Plate Chambers

    CERN Document Server

    Hadjiiska, R; Pavlov, B; Petkov, P; Dimitrov, A; Beernaert, K; Cimmino, A; Costantini, S; Garcia, G; Lellouch, J; Marinov, A; Ocampo, A; Strobbe, N; Thyssen, F; Tytgat, M; Verwilligen, P; Yazgan, E; Zaganidis, N; Aleksandrov, A; Genchev, V; Iaydjiev, P; Rodozov, M; Shopova, M; Sultanov, G; Ban, Y; Cai, J; Xue, Z; Ge, Y; Li, Q; Qian, S; Avila, C; Chaparro, L F; Gomez, J P; Moreno, B Gomez; Oliveros, A F Osorio; Sanabria, J C; Assran, Y; Sharma, A; Abbrescia, M; Colaleo, A; Pugliese, G; Loddo, F; Calabria, C; Maggi, M; Benussi, L; Bianco, S; Colafranceschi, S; Piccolo, D; Carrillo, C; Iorio, O; Buontempo, S; Paolucci, P; Vitulo, P; Berzano, U; Gabusi, M; Kang, M; Lee, K S; Park, S K; Shin, S; Kim, M S; Seo, H; Goh, J; Choi, Y; Shoaib, M

    2013-01-01

    The Resistive Plate Chamber (RPC) muon subsystem contributes significantly to the formation of the trigger decision and reconstruction of the muon trajectory parameters. Simulation of the RPC response is a crucial part of the entire CMS Monte Carlo software and directly influences the final physical results. An algorithm based on the parametrization of RPC efficiency, noise, cluster size and timing for every strip has been developed. Experimental data obtained from cosmic and proton-proton collisions at $\\sqrt{s}=7$ TeV have been used for determination of the parameters. A dedicated validation procedure has been developed. A good agreement between the simulated and experimental data has been achieved.

  2. Induced signals in resistive plate chambers

    CERN Document Server

    Riegler, W

    2002-01-01

    We derive theorems for induced signals on electrodes embedded in a medium with a position and frequency dependent permittivity $\\vep(\\vx,s)$ and conductivity $\\sigma(\\vx,s)$ that are connected with arbitrary discrete elements. The problem is treated using the quasi-static approximation of Maxwell's equations for weakly conducting media \\cite{melcher}\\cite{quasi}. The induced signals can be derived by time dependent weighting fields and potentials and the result is the same as the one given in \\cite{gatti}. We also show how these time dependent weighting fields can be derived from electrostatic solutions. Finally we will apply the results to Resistive Plate Chambers (RPCs) where we discuss the effects of the resistive plates and thin resistive layers on the signals induced on plane electrodes and strips.

  3. Resistive Plate Chamber Efficiency & Rate Capability Analysis

    Science.gov (United States)

    Candocia, Max

    2012-10-01

    Bakelite-based resistive plate chambers (RPCs) are particle detectors commonly used in muon trigger systems for high-energy physics experiments. Bakelite RPCs combine fast response, sufficient position resolution and low cost, and they can be operated at instantaneous background rates up to approximately 1.5 kHz/cm^2. Current and future collider experiments will demand operation of trigger RPCs under background rates higher than what is currently achieved. The rate capability is related to the bulk and surface conductivities of the Bakelite material used for the plates bordering the active gas volume in the RPCs. At the LHC and RHIC, these surfaces are coated with linseed oil, which lowers the surface resistivity of the Bakelite, which, to a point, improves the rate capability of the detectors. We have doped our own plates with various concentrations of carbon black. Over the past year we have tested RPCs with Bakelite plates of different resistivity using cosmic ray muons and radioactive Fe55 sources to emulate different levels of background in the detector. Results on the RPC efficiencies at different background rates and for different Bakelite coatings will be presented.

  4. A Fast Ionization Chamber for GODDESS

    Science.gov (United States)

    Lumb, R. T.; Lipman, A. S.; Baugher, T.; Cizewski, J. A.; Ratkiewicz, A.; Pain, S. D.; Kozub, R. L.

    2014-09-01

    Transfer reactions are among the main methods used in nuclear physics to probe the structure of nuclei. Such information is needed to constrain nuclear models and to understand various nucleosynthesis processes. In many cases, the nuclear level densities are too high to be resolved in transfer reactions via charged particle detection alone. This problem and issues arising from contaminants in radioactive beams can be addressed by using particle- γ coincidence techniques along with heavy recoil identification in inverse kinematics. A device to accomplish these tasks is Gammasphere ORRUBA: Dual Detectors for Experimental Structure Studies (GODDESS), currently being commissioned for the ATLAS facility at ANL. We are currently building a compact, tilted grid ionization chamber for GODDESS to detect and identify beam-like recoils near zero degrees in the lab. The tilt (30 degrees off normal to the beam) helps the ion pairs to be detected quickly, after drifting only a short distance away from the beam axis. This reduces the response time, allowing counting rates of ~500,000/s. The design and current status of the project will be presented. Research supported by the U. S. DOE.

  5. Preliminary studies of a new monitor ionization chamber.

    Science.gov (United States)

    Yoshizumi, Maíra T; Vivolo, Vitor; Caldas, Linda V E

    2010-01-01

    A new monitor ionization chamber was developed at Instituto de Pesquisas Energéticas e Nucleares (IPEN) in order to monitor X-ray beams. The main difference of this monitor ionization chamber in relation to other monitor chambers is its geometry, which consists of a ring-shaped sensitive volume. Because of this geometry, the monitor chamber has a central hole through which the direct radiation beam passes. The operational characteristics of the monitor chamber were evaluated: saturation, ion collection efficiency and polarity effect. Besides these tests, the short- and medium-term stabilities of its response were also evaluated. During the tests the leakage current was always negligible. All results showed values within those recommended internationally (IEC, 1997. Medical electrical equipment-dosimeters with ionization chambers and/or semi-conductor detectors as used in X-ray diagnostic imaging. IEC 61674. International Electrotechnical Commission, Genève). Copyright 2009 Elsevier Ltd. All rights reserved.

  6. Characterization of a homemade ionization chamber for radiotherapy beams

    Energy Technology Data Exchange (ETDEWEB)

    Neves, Lucio P., E-mail: lpneves@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Comissao Nacional de Energia Nuclear, Av. Prof. Lineu Prestes 2242, 05508-000 Sao Paulo (Brazil); Perini, Ana P., E-mail: aperini@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Comissao Nacional de Energia Nuclear, Av. Prof. Lineu Prestes 2242, 05508-000 Sao Paulo (Brazil); Santos, Gelson P. dos, E-mail: gpsantos@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Comissao Nacional de Energia Nuclear, Av. Prof. Lineu Prestes 2242, 05508-000 Sao Paulo (Brazil); Xavier, Marcos, E-mail: mxavier@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Comissao Nacional de Energia Nuclear, Av. Prof. Lineu Prestes 2242, 05508-000 Sao Paulo (Brazil); Khoury, Helen J., E-mail: khoury@ufpe.br [Universidade Federal de Pernambuco, Departamento de Energia Nuclear, Av. Prof. Luiz Freire 1000, 50740-540 Recife (Brazil); Caldas, Linda V.E., E-mail: lcaldas@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Comissao Nacional de Energia Nuclear, Av. Prof. Lineu Prestes 2242, 05508-000 Sao Paulo (Brazil)

    2012-07-15

    A homemade cylindrical ionization chamber was studied for routine use in therapy beams of {sup 60}Co and X-rays. Several characterization tests were performed: leakage current, saturation, ion collection efficiency, polarity effect, stability, stabilization time, chamber orientation and energy dependence. All results obtained were within international recommendations. Therefore the homemade ionization chamber presents usefulness for routine dosimetric procedures in radiotherapy beams. - Highlights: Black-Right-Pointing-Pointer A homemade ionization chamber was studied for routine use in radiotherapy. Black-Right-Pointing-Pointer Several characterization tests were performed and the results were satisfactory. Black-Right-Pointing-Pointer This chamber was compared to commercial ones and the results were similar. Black-Right-Pointing-Pointer This chamber is suitable for calibration procedures in {sup 60}Co beams.

  7. Development of a pixel ionization chamber for beam monitor in proton therapy

    Science.gov (United States)

    La Rosa, A.; Garella, M. A.; Attili, A.; Bourhaleb, F.; Cirio, R.; Donetti, M.; Giordanengo, S.; Givehchi, N.; Marchetto, F.; Mazza, G.; Meyroneinc, S.; Pecka, A.; Peroni, C.; Pittà, G.

    2007-03-01

    We have developed a detector to be used as monitor for proton therapy beam lines. The detector is a 2-D parallel plate ionization chamber, with the anode segmented in 1024 square pixels arranged in a 32×32 matrix. The detector characterization is presented.

  8. Development of a pixel ionization chamber for beam monitor in proton therapy

    Energy Technology Data Exchange (ETDEWEB)

    La Rosa, A. [Dipartimento di Fisica Sperimentale, Universita di Torino, Via P. Giuria 1, Turin 10125 (Italy) and INFN, Sezione di Torino, Via P. Giuria, Turin 10125 (Italy)]. E-mail: larosa@to.infn.it; Garella, M.A. [INFN, Sezione di Torino, Via P. Giuria, Turin 10125 (Italy); Attili, A. [Dipartimento di Fisica Sperimentale, Universita di Torino, Via P. Giuria 1, Turin 10125 (Italy); Bourhaleb, F. [Fondazione TERA, Via Puccini 11, Novara 28100 (Italy); Cirio, R. [INFN, Sezione di Torino, Via P. Giuria, Turin 10125 (Italy); Donetti, M. [INFN, Sezione di Torino, Via P. Giuria, Turin 10125 (Italy); Fondazione CNAO, Via Caminadella 16, Milan 20123 (Italy); Giordanengo, S. [INFN, Sezione di Torino, Via P. Giuria, Turin 10125 (Italy); Givehchi, N. [Dipartimento di Fisica Sperimentale, Universita di Torino, Via P. Giuria 1, Turin 10125 (Italy); INFN, Sezione di Torino, Via P. Giuria, Turin 10125 (Italy); Marchetto, F. [INFN, Sezione di Torino, Via P. Giuria, Turin 10125 (Italy); Mazza, G. [INFN, Sezione di Torino, Via P. Giuria, Turin 10125 (Italy); Meyroneinc, S. [Institut Curie-Centre de Protontherapie de Orsay, Bat. 101 Campus Universitaire, Orsay Cedex 91898 (France); Pecka, A. [Dipartimento di Fisica Sperimentale, Universita di Torino, Via P. Giuria 1, Turin 10125 (Italy); Peroni, C. [Dipartimento di Fisica Sperimentale, Universita di Torino, Via P. Giuria 1, Turin 10125 (Italy); INFN, Sezione di Torino, Via P. Giuria, Turin 10125 (Italy); Pitta, G. [Fondazione TERA, Via Puccini 11, Novara 28100 (Italy)

    2007-03-01

    We have developed a detector to be used as monitor for proton therapy beam lines. The detector is a 2-D parallel plate ionization chamber, with the anode segmented in 1024 square pixels arranged in a 32x32 matrix. The detector characterization is presented.

  9. Tests of a Novel Design of Resistive Plate Chambers

    CERN Document Server

    Bilki, B; Freund, B; Neubüser, C; Onel, Y; Repond, J; Schlereth, J; Xia, L

    2015-01-01

    A novel design of Resistive Plate Chambers (RPCs), using only a single resistive plate, is being proposed. Based on this design, two large size prototype chambers were constructed and were tested with cosmic rays and in particle beams. The tests confirmed the viability of this new approach. In addition to showing an improved single-particle response compared to the traditional 2-plate design, the novel chambers also prove to be suitable for calorimetric applications.

  10. Progress in timing Resistive Plate Chambers

    Energy Technology Data Exchange (ETDEWEB)

    Blanco, A. [Laboratorio de Instrumentacao e Fisica Experimental de Particulas (LIP), Universidade de Coimbra, Dep. de Fisica, 3004-516 Coimbra (Portugal); Carolino, N. [Laboratorio de Instrumentacao e Fisica Experimental de Particulas (LIP), Universidade de Coimbra, Dep. de Fisica, 3004-516 Coimbra (Portugal); Correia, C.M.B.A. [Laboratorio de Instrumentacao e Fisica Experimental de Particulas (LIP), Universidade de Coimbra, Dep. de Fisica, 3004-516 Coimbra (Portugal)] [and others

    2004-12-11

    Timing RPCs are Resistive Plate Chambers made with glass and metal electrodes separated by precision spacers. Typical gas gaps are a few hundred micrometers wide. Such counters were introduced in 1999 and have since reached timing accuracies below 50ps {sigma} with efficiencies above 99% for MIPs. Applications in high-energy physics have already taken place with several more under study.Some recent developments include the extension of the counting rate capability by over one order of magnitude, to 25kHz/cm2, with time resolutions below 100ps {sigma}. A prototype RPC-based Positron Emission Tomograph yielded a reconstructed point-source resolution of 0.6 mm FWHM and a modified timing RPC design, featuring 50{mu}m pitch anode strips, allowed to reach extremely good position resolution for hard X-rays in digital readout mode.An analytically solvable model has allowed us to clarify the basic factors influencing the time resolution.

  11. Development of standard ionization chamber counting system for activity measurements

    CERN Document Server

    Pyun, W B; Lee, H Y; Park, T S

    1998-01-01

    This study is to set up the activity measuring system using a 4 pi gamma ionization chamber as used mainly in national standards laboratories that are responsible for radionuclide metrology. The software for automatic control between the electrometer and personal computer is developed using Microsoft visual basic 4.0 and IEEE488 Interface. The reproducibility of this 4 pi gamma ionization chamber is about 0.02% and the background current is 0.054+-0.024 pA. this 4 pi gamma ionization chamber is calibrated by 6 standard gamma emitting radionuclides from KRISS. According to the result of this study, it is revealed that this 4 pi gamma ionization chamber counting system can be used as a secondary standard instrument for radioactivity measurement.

  12. Detector Physics of Resistive Plate Chambers

    CERN Document Server

    Lippmann, Christian; Riegler, W

    2003-01-01

    Resistive Plate Chambers (RPCs) are gaseous parallel plate avalanche detectors that implement electrodes made from a material with a high volume resistivity between 10^7 and 10^12 Ohm cm. Large area RPCs with 2mm single gaps operated in avalanche mode provide above 98% efficiency and a time resolution of around 1ns up to a flux of several kHz/cm2. These Trigger RPCs will, as an example, equip the muon detector system of the ATLAS experiment at CERN on an area of 3650m2 and with 355.000 independent read out channels. Timing RPCs with a gas gap of 0.2 to 0.3mm are widely used in multi gap configurations and provide 99% efficiency and time resolution down to 50ps. While their performance is comparable to existing scintillator-based Time-Of-Flight (TOF) technology, Timing RPCs feature a significantly, up to an order of magnitude, lower price per channel. They will for example equip the 176m2 TOF barrel of the ALICE experiment at CERN with 160.000 independent read out cells. RPCs were originally operated in stream...

  13. Response and Monte Carlo evaluation of a reference ionization chamber for radioprotection level at calibration laboratories

    Science.gov (United States)

    Neves, Lucio P.; Vivolo, Vitor; Perini, Ana P.; Caldas, Linda V. E.

    2015-07-01

    A special parallel plate ionization chamber, inserted in a slab phantom for the personal dose equivalent Hp(10) determination, was developed and characterized in this work. This ionization chamber has collecting electrodes and window made of graphite, and the walls and phantom made of PMMA. The tests comprise experimental evaluation following international standards and Monte Carlo simulations, employing the PENELOPE code to evaluate the design of this new dosimeter. The experimental tests were conducted employing the radioprotection level quality N-60 established at the IPEN, and all results were within the recommended standards.

  14. Development of Master Chamber Software for Data Acquisition of Ionization Chamber for Indus 2 RRCAT

    OpenAIRE

    Priyesh Soni; Mrs. B. Harita; Nawaz Ali Sayed

    2013-01-01

    The main goal of this paper was to Develop Master control software for DAQ of ionization chamber for INDUS-2 beam lines for detection of X-ray flux by an Ionization chamber that will remotely control and monitor the ultra low current signal detection analog module precisely. This application will be useful to measure the intensity of X-ray flux through ionization chamber in a beam line of synchrotron radiation source which is mounted in INDUS-2. It is one of new technique of detection. Beam l...

  15. Electrostatic fields in an ionization chamber electret

    Science.gov (United States)

    Fallone, B. G.; Podgorsak, E. B.

    1983-09-01

    The theory of linear systems is used to derive the potential and electric field in distance space in a cylindrical polarization/depolarization electret chamber. General solutions for the near, intermediate, and far regions are given and their domains of convergence discussed. On the axis of the chamber the solutions for the electret surface are equal to those obtained from Gauss's and Kirchoff's laws, and at large distances from the surface to those obtained from the introduction of a dipole layer model.

  16. Comparative study of ionization chamber detectors vis-a-vis a CCD detector for dispersive XAS measurement in transmission geometry

    Energy Technology Data Exchange (ETDEWEB)

    Poswal, A. K.; Agrawal, A.; Bhattachryya, D.; Jha, S. N.; Sahoo, N. K. [Applied Spectroscopy Division, Bhabha Atomic Research Centre, Mumbai -400 085 (India)

    2013-02-05

    We have designed and fabricated parallel plate ionization chamber detectors and voltage vs. current characteristics (V-I curve) of the detectors were recorded with synchrotron radiation to qualify for use in X-ray Absorption Spectroscopy (XAS) measurements. After qualifying the ionization chambers, the detectors were used in the dispersive EXAFS beamline (BL-08) at INDUS-2 SRS in Turbo-XAS geometry. Using the same setup and under the same setting, XAS spectra were also recorded with a CCD detector and the observation on relative performance of the ionization chamber vis-a-vis the CCD detector is presented in this paper.

  17. Performance of vintage direct reading pocket ionization chambers.

    Science.gov (United States)

    Bergen, Robert J; Harvey, John A; Kearfott, Kimberlee J

    2010-05-01

    The linearity, accuracy, and precision of each of two groups of vintage 51.6 microC-kg-1 maximum scale passive direct reading pocket ionization chambers, each from a different manufacturer and all aged at least 50 years since manufacture, were tested. The pocket ionization chambers were suspended on a phantom and exposed using a 137Cs source. Variations from trial to trial were smaller than variations from chamber to chamber. The average percent standard deviations ranged from 5.7% to 14% across all exposures. The accuracy of the dosimeter readings increased as the exposure level increased. Percent error from known exposure values decreased as exposure increased. An independent samples t test indicated there was a statistically significant difference between the two groups only at a delivered exposure of 6.45 microC-kg-1. Testing was performed in a 222Rn drum to determine the effect of Rn on the pocket ionization chambers. Exposure of five chambers to an average Rn level of 4.70 kBq m-3 and thirty chambers to 3.86 kBq m-3 over a 7-d period produced abnormally high readings at least three times background in eight of the 35 chambers tested.

  18. Quantification of static magnetic field effects on radiotherapy ionization chambers

    Science.gov (United States)

    Agnew, J.; O’Grady, F.; Young, R.; Duane, S.; Budgell, G. J.

    2017-03-01

    Integrated magnetic resonance (MR) imaging and radiotherapy (RT) delivery machines are currently being developed, with some already in clinical use. It is anticipated that the strong magnetic field used in some MR-RT designs will have a significant impact on routine measurements of dose in the MR-linac performed using ionization chambers, which provide traceability back to a primary standard definition of dose. In particular, the presence of small air gaps around ionization chambers may introduce unacceptably high uncertainty into these measurements. In this study, we investigate and quantify the variation attributable to air gaps for several routinely-used cylindrical ionization chambers in a magnetic field, as well as the effect of the magnetic field alone on the response of the chambers. The measurements were performed in a Co-60 beam, while the ionization chambers were positioned in custom-made Perspex phantoms between the poles of an electromagnet, which was capable of generating magnetic fields of up to 2 T field strength, although measurements were focused around 1.5 T. When an asymmetric air gap was rotated at cardinal angles around the ionization chambers investigated here, variation of up to 8.5  ±  0.2 percentage points (PTW 31006 chamber) was observed in an applied magnetic field of 1.5 T. The minimum peak-to-peak variation was 1.1  ±  0.1% (Exradin A1SL). When the same experiment was performed with a well-defined air gap of known position using the PTW 30013 chamber, a variation of 3.8  ±  0.2% was observed. When water was added to the phantom cavity to eliminate all air gaps, the variation for the PTW 30013 was reduced to 0.2  ±  0.01%.

  19. Characterization of a CT ionization chamber for radiation field mapping

    Energy Technology Data Exchange (ETDEWEB)

    Perini, Ana P., E-mail: aperini@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN), Comissao Nacional de Energia Nuclear, Av. Prof. Lineu Prestes 2242, 05508-000, Sao Paulo, SP (Brazil); Neves, Lucio P., E-mail: lpneves@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN), Comissao Nacional de Energia Nuclear, Av. Prof. Lineu Prestes 2242, 05508-000, Sao Paulo, SP (Brazil); Vivolo, Vitor, E-mail: vivolo@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN), Comissao Nacional de Energia Nuclear, Av. Prof. Lineu Prestes 2242, 05508-000, Sao Paulo, SP (Brazil); Xavier, Marcos, E-mail: mxavier@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN), Comissao Nacional de Energia Nuclear, Av. Prof. Lineu Prestes 2242, 05508-000, Sao Paulo, SP (Brazil); Khoury, Helen J., E-mail: hjkhoury@gmail.com [Universidade Federal de Pernambuco, Departamento de Energia Nuclear, Av. Prof. Luiz Freire 1000, 50740-540, Recife, PE (Brazil); Caldas, Linda V.E., E-mail: lcaldas@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN), Comissao Nacional de Energia Nuclear, Av. Prof. Lineu Prestes 2242, 05508-000, Sao Paulo, SP (Brazil)

    2012-07-15

    A pencil-type ionization chamber, developed at Instituto de Pesquisas Energeticas e Nucleares (IPEN), was characterized with the objective to verify the possibility of its application in radiation field mapping procedures. The characterization tests were evaluated, and the results were satisfactory. The results obtained for the X radiation field mapping with the homemade chamber were compared with those of a PTW Farmer-type chamber (TN 30011-1). The maximum difference observed in this comparison was only 1.25%, showing good agreement. - Highlights: Black-Right-Pointing-Pointer A new ionization chamber was made and tested for radiation field mapping. Black-Right-Pointing-Pointer This ionization chamber was made using only accessible low cost materials. Black-Right-Pointing-Pointer The operational tests were made and the results were within the recommended limits. Black-Right-Pointing-Pointer The field map was compared with a commercial chamber presenting a 1.25% difference. Black-Right-Pointing-Pointer Our chamber presents potential for assurance reliability in calibration procedures.

  20. LET measurements with a Liquid Ionization Chamber

    OpenAIRE

    Tegami, S.

    2013-01-01

    Deep-seated tumors can be efficiently treated with heavy charged particles. The characteristic depth dose profile inside the tissue (Bragg peak) allows to deliver a high dose inside the tumor, while sparing the neighboring healthy tissue. As compared to protons, heavy ions like carbon or oxygen produce a higher amount of ionization events along their track (and in particular at the end of the ion beam path), resulting in an irreparable damage to the DNA of the tumor cells. T...

  1. Construction and commissioning of a position-sensitive ionization chamber

    Science.gov (United States)

    Kwag, M. S.; Chae, K. Y.; Cha, S. M.; Kim, A.; Kim, M. J.; Lee, E. J.; Lee, J. H.

    2016-05-01

    A position-sensitive ionization chamber has been constructed and commissioned at the Physics Department of Sungkyunkwan University to extract position information on incident charged particles for future nuclear reaction measurements. By utilizing the newly-designed position-sensitive anodes and the previously-commissioned portable gas-filled ionization chamber by Chae et al., position information on incident particles could be obtained. The device was tested with an 241Am α-emitting source, and the standard deviation of the fitted Gaussian distribution was measured to be 1.76 mm when a collimator with a 2 mm hole was used.

  2. Characterization of a free air ionization chamber for low energies

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Natalia F.; Xavier, Marcos; Vivolo, Vitor; Caldas, Linda V.E., E-mail: nsilva@ipen.br, E-mail: mxavier@ipen.br, E-mail: vivolo@ipen.br, E-mail: lcaldas@ipen.br [Instituto de Pesquisas Energeticas e Nucleres (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    Free air ionization chambers are used by most primary metrology laboratories as primary standards of the quantities air kerma and exposure in X-ray beams. The free air ionization chamber for low energies of the Calibration Laboratory (LCI) of IPEN showed in a characterization test a problem in the set responsible for the variation of its sensitive volume. After a modification in the support of the micrometers used for the movement of the internal cylinder and the establishment of a new alignment system protocol, the tests were redone. The objective of this work was to present the results obtained in the new condition. (author)

  3. Gridded Ionization Chamber; Camara de ionizacion con reja

    Energy Technology Data Exchange (ETDEWEB)

    Manero Amoros, F.

    1962-07-01

    In the present paper the working principles of a gridded ionization chamber are given, and all the different factors that determine its resolution power are analyzed in detail. One of these devices, built in the Physics Division of the JEN and designed specially for use in measurements of alpha spectroscopy, is described. finally the main applications, in which the chamber can be used, are shown. (Author) 17 refs.

  4. The response of ionization chambers to relativistic heavy nuclei

    Science.gov (United States)

    Newport, B. J.; Stone, E. C.; Waddington, C. J.; Binns, W. R.; Fixsen, D. J.; Garrard, T. L.; Grimm, G.; Israel, M. H.; Klarmann, J.

    1985-01-01

    The LBL Bevalac for the Heavy Nuclei Experiment on HEAO-3, compared the response of a set of laboratory ionization chambers to beams of 26Fe, 36Kr, 54Xe, 67 Ho, and 79Au nuclei at maximum energies ranging from 1666 MeV/amu for Fe to 1049 MeV/amu for Au. The response of these chambers shows a significant deviation from the expected energy dependence, but only a slight deviation from Z sq scaling.

  5. Experimental and calculated calibration of ionization chambers with air circulation

    CERN Document Server

    Peetermans, A

    1972-01-01

    The reports describes the method followed in order to calibrate the different ionization chambers with air circulation, used by the 'Health Physics Group'. The calculations agree more precisely with isotopes cited previously (/sup 11/C, /sup 13/N, /sup 15/O, /sup 41 /Ar, /sup 14/O, /sup 38/Cl) as well as for /sup 85/Kr, /sup 133/Xe, /sup 14/C and tritium which are used for the experimental standardisation of different chambers.

  6. Ionization Chambers for Monitoring in High-Intensity Neutrino Beams

    CERN Document Server

    McDonald, J; Velissaris, C; Erwin, A R; Ping, H; Viren, B M; Diwan, M V

    2002-01-01

    Radiation-hard ionization chambers were tested using an intense electron beam from the accelerator test facility (ATF) at the Brookhaven National Laboratory (BNL). The detectors were designed to be used as the basic element for monitoring muons in the Main Injector Neutrino beamline (NuMI) at the Fermi National Accelerator Laboratory (FNAL). Measurements of linearity of response, voltage dependence, and the onset of ionization saturation as a function of gap voltage were performed.

  7. LET measurements with a Liquid Ionization Chamber

    OpenAIRE

    Tegami, S.

    2013-01-01

    Deep-seated tumors can be efficiently treated with heavy charged particles. The characteristic depth dose profile inside the tissue (Bragg peak) allows to deliver a high dose inside the tumor, while sparing the neighboring healthy tissue. As compared to protons, heavy ions like carbon or oxygen produce a higher amount of ionization events along their track (and in particular at the end of the ion beam path), resulting in an irreparable damage to the DNA of the tumor cells. The density of such...

  8. Characterization of a CT ionization chamber for radiation field mapping.

    Science.gov (United States)

    Perini, Ana P; Neves, Lucio P; Vivolo, Vitor; Xavier, Marcos; Khoury, Helen J; Caldas, Linda V E

    2012-07-01

    A pencil-type ionization chamber, developed at Instituto de Pesquisas Energéticas e Nucleares (IPEN), was characterized with the objective to verify the possibility of its application in radiation field mapping procedures. The characterization tests were evaluated, and the results were satisfactory. The results obtained for the X radiation field mapping with the homemade chamber were compared with those of a PTW Farmer-type chamber (TN 30011-1). The maximum difference observed in this comparison was only 1.25%, showing good agreement. Copyright © 2011 Elsevier Ltd. All rights reserved.

  9. Segmented ionization chambers for beam monitoring in hadrontherapy

    Science.gov (United States)

    Braccini, Saverio; Cirio, Roberto; Donetti, Marco; Marchetto, Flavio; Pittà, Giuseppe; Lavagno, Marco; La Rosa, Vanessa

    2015-06-01

    Segmented ionization chambers represent a good solution to monitor the position, the intensity and the shape of ion beams in hadrontherapy. Pixel and strip chambers have been developed for both passive scattering and active scanning dose delivery systems. In particular, strip chambers are optimal for pencil beam scanning, allowing for spatial and time resolutions below 0.1 mm and 1 ms, respectively. The MATRIX pixel and the Strip Accurate Monitor for Beam Applications (SAMBA) detectors are described in this paper together with the results of several beam tests and industrial developments based on these prototypes.

  10. Computational evaluation of a pencil ionization chamber in a standard diagnostic radiology beam

    Energy Technology Data Exchange (ETDEWEB)

    Mendonca, Dalila Souza Costa; Neves, Lucio Pereira; Perini, Ana Paula, E-mail: anapaula.perini@ufu.br [Universidade Federal de Uberlandia (UFU), MG (Brazil). Instituto de Fisica; Santos, William S.; Caldas, Linda V.E. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Belinato, Walmir [Instituto Federal de Educacao, Ciencia e Tecnologia da Bahia (IFBA), Vitoria da Conquista, BA (Brazil)

    2016-07-01

    In this work a pencil ionization chamber was evaluated. This evaluation consisted in the determination of the influence of the ionization chamber components in its response. For this purpose, the Monte Carlo simulations and the spectrum of the standard diagnostic radiology beam (RQR5) were utilized. The results obtained, showed that the influence of the ionization chamber components presented no significant influence on the chamber response. Therefore, this ionization chamber is a good alternative for dosimetry in diagnostic radiology. (author)

  11. Pencil beam proton radiography using a multilayer ionization chamber

    NARCIS (Netherlands)

    Farace, Paolo; Righetto, Roberto; Meijers, Arturs

    2016-01-01

    A pencil beam proton radiography (PR) method, using a commercial multilayer ionization chamber (MLIC) integrated with a treatment planning system (TPS) was developed. A Giraffe (IBA Dosimetry) MLIC (+/- 0.5 mm accuracy) was used to obtain pencil beam PR by delivering spots uniformly positioned at a

  12. A multiple sampling ionization chamber for the External Target Facility

    Science.gov (United States)

    Zhang, X. H.; Tang, S. W.; Ma, P.; Lu, C. G.; Yang, H. R.; Wang, S. T.; Yu, Y. H.; Yue, K.; Fang, F.; Yan, D.; Zhou, Y.; Wang, Z. M.; Sun, Y.; Sun, Z. Y.; Duan, L. M.; Sun, B. H.

    2015-09-01

    A multiple sampling ionization chamber used as a particle identification device for high energy heavy ions has been developed for the External Target Facility. The performance of this detector was tested with a 239Pu α source and RI beams. A Z resolution (FWHM) of 0.4-0.6 was achieved for nuclear fragments of 18O at 400 AMeV.

  13. Space-charge effects in liquid argon ionization chambers

    Science.gov (United States)

    Rutherfoord, J. P.; Walker, R. B.

    2015-03-01

    We have uniformly irradiated liquid argon ionization chambers with betas from high-activity 90Sr sources. The radiation environment is similar to that in the liquid argon calorimeters which are part of the ATLAS detector installed at CERN's Large Hadron Collider (LHC). We measured the resulting ionization current over a wide range of applied potential for two different source activities and for three different chamber gaps. These studies provide operating experience at exceptionally high ionization rates. In particular they indicate a stability at the 0.1% level for these calorimeters over years of operation at the full LHC luminosity when operated in the normal mode at an electric field E = 1.0 kV / mm. We can operate these chambers in the normal mode or in the space-charge limited regime and thereby determine the transition point between the two. This transition point is parameterized by a positive argon ion mobility of μ+ = 0.08 ± 0.02mm2 / V s at a temperature of 88.0±0.5 K and at a pressure of 1.02±0.02 bar. In the space-charge limited regime the ionization currents are degraded and show signs of instability. At the highest electric fields in our study (6.7 kV/mm) the ionization current is still slowly rising with increasing electric field.

  14. Measurements of the Rate Capability of Various Resistive Plate Chambers

    CERN Document Server

    Affatigato, M; Bilki, B; Corriveau, F; Freund, B; Johnson, N; Neubueser, C; Onel, Y; Repond, J; Xia, L

    2015-01-01

    Resistive Plate Chambers (RPCs) exhibit a significant loss of efficiency for the detection of particles, when subjected to high particle fluxes. This rate limitation is related to the usually high resistivity of the resistive plates used in their construction. This paper reports on measurements of the performance of three different glass RPC designs featuring a different total resistance of the resistive plates. The measurements were performed with 120 GeV protons at varying beam intensities

  15. On the Frisch-Grid signal in ionization chambers

    Energy Technology Data Exchange (ETDEWEB)

    Al-Adili, A. [EC-JRC - Institute for Reference Materials and Measurements, B-2440 Geel (Belgium); Division of Applied Nuclear Physics, Uppsala University, S-751 20 Uppsala (Sweden); Hambsch, F.-J., E-mail: Franz-Josef.HAMBSCH@ec.europa.eu [EC-JRC - Institute for Reference Materials and Measurements, B-2440 Geel (Belgium); Bencardino, R. [EC-JRC - Institute for Reference Materials and Measurements, B-2440 Geel (Belgium); Pomp, S. [Division of Applied Nuclear Physics, Uppsala University, S-751 20 Uppsala (Sweden); Oberstedt, S. [EC-JRC - Institute for Reference Materials and Measurements, B-2440 Geel (Belgium); Zeynalov, Sh. [JINR - Joint Institute for Nuclear Research, Dubna, R-141980 (Russian Federation)

    2012-04-11

    A recent theoretical approach concerning the grid-inefficiency (GI) problem in Twin Frisch-Grid Ionization Chambers was validated experimentally. The experimental verification focused on the induced signal on the anode plate. In this work the investigation was extended by studying the grid signal. The aim was to verify the grid-signal dependency on the grid inefficiency {sigma}. The measurements were made with fission fragments from {sup 252}Cf(sf), using two different grids, with 1 and 2 mm wire distances, leading to the GI values: {sigma}=0.031 and {sigma}=0.083, respectively. The theoretical grid signal was confirmed because the detected grid pulse-height distribution was smaller for the larger {sigma}. By applying the additive GI correction approach, the two grid pulse heights were consistent. In the second part of the work, the corrected grid signal was used to deduce emission angles of the fission fragments. It is inconvenient to treat the grid signal by means of conventional analogue electronics, because of its bipolarity. Therefore, the anode and grid signals were summed to create a unipolar, angle-dependent pulse height. Until now the so-called summing method has been the well-established approach to deduce the angle from the grid signal. However, this operation relies strongly on an accurate and stable calibration between the two summed signals. By application of digital-signal processing, the grid signal's bipolarity is no longer an issue. Hence one can bypass the intermediate summation step of the two different pre-amplifier signals, which leads to higher stability. In this work the grid approach was compared to the summing method in three cases: {sup 252}Cf(sf), {sup 235}U(n,f) and {sup 234}U(n,f). By using the grid directly, the angular resolution was found equally good in the first case but gave 7% and 20% improvements, respectively, in the latter cases.

  16. NIST Ionization Chamber “A” Sample-Height Corrections

    OpenAIRE

    Fitzgerald, Ryan

    2012-01-01

    For over 30 years scientists in the NIST radioactivity group have been using their pressurized ionization chamber “A” (PIC “A”) to make measurements of radioactivity and radioactive half-lives. We now have evidence that some of those reported measurements were incorrect due to slippage of the source positioning ring over time. The temporal change in the holder caused an error in the source-height within the chamber, which was thought to be invariant. This unaccounted-for height change caused ...

  17. Neutron Dosimetry Using a Tissue-Equivalent Ionization Chamber.

    Science.gov (United States)

    1980-05-01

    procedures are described, and correction factors discussed. /’ On a montg et v~rifiA un systtme de niesure d’oZz la dose ou le kerma tissulaire neutronique ...tube 3.8 cm in diameter. At the same time, it is advantageous to keep the active volume as large as possible in order to maximize sensitivity. The...CHAMBER The construction of the FWT TE Ionization chamber is Illustrated in figure 1. The active volume lies between the central electrode and the

  18. Imaging with high Dynamic using an Ionization Chamber

    OpenAIRE

    Menk, Ralf-Hendrik; Amenitsch, Heinz; Arfelli, Fulvia; Bernstorff, Sigrid; Besch, Hans Juergen; Voltolina, Francesco

    2010-01-01

    In this work a combination of an ionization chamber with one-dimensional spatial resolution and a MicroCAT structure will be presented. The combination between gas gain operations and integrating front-end electronics yields a dynamic range as high as eight to nine orders of magnitude. Therefore this device is well suitable for medical imaging or applications such as small angle x-ray scattering, where the requirements on the dynamic of the detector are exceptional high. Basically the describ...

  19. A multiple sampling ionization chamber for the External Target Facility

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, X.H., E-mail: zhxh@impcas.ac.cn [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Tang, S.W.; Ma, P.; Lu, C.G.; Yang, H.R.; Wang, S.T.; Yu, Y.H.; Yue, K.; Fang, F. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Yan, D.; Zhou, Y.; Wang, Z.M.; Sun, Y. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Sun, Z.Y.; Duan, L.M. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Sun, B.H. [School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191 (China)

    2015-09-21

    A multiple sampling ionization chamber used as a particle identification device for high energy heavy ions has been developed for the External Target Facility. The performance of this detector was tested with a {sup 239}Pu α source and RI beams. A Z resolution (FWHM) of 0.4–0.6 was achieved for nuclear fragments of {sup 18}O at 400 AMeV.

  20. Cosmic Rays Response of High-pressure Ionization Chamber

    Institute of Scientific and Technical Information of China (English)

    GAO; Fei; XIAO; Xue-fu; NI; Ning; ZHANG; Xi; HOU; Jin-bing; SONG; Ming-zhe; WANG; Hong-yu

    2013-01-01

    In order to study cosmic rays response characteristics of self-designed HPIC(high pressure ionization chamber),model JLZ-Ⅲ,the JLZ-Ⅲwas placed on a boat which is 3 meters much deeper and at least 1 kilometer away from land to measure air kerma rate in the open water in Miyun Reservoir(geomagnetic latitude 29°N,altitude 160 m),Beijing.The result was compared with the measurement

  1. Two-dimensional position sensitive ionization chamber with GEM

    Science.gov (United States)

    Kitamura, Noritaka; Noro, Tetsuo; Sakaguchi, Satoshi; Takao, Hideaki; Nishio, Yasutaka

    2014-09-01

    We have been developing a multi-anode ionization chamber for Accelerator Mass Spectrometry (AMS) at Kyushu University. Furthermore, we are planning to construct a neutron detector with high position resolution by combining the chamber with Gas Electron Multiplier (GEM) and a neutron converter. One of purposes is the measurement of p-> , pn knockout reaction from unstable nuclei. The multi-anode ionization chamber is composed of subdivided multiple anodes, a cathode to produce an uniform electric field, and a Frisch grid. The chamber must have position sensitivity because obtaining a beam profile is required for AMS measurements, where counting loss should be avoided. Also in the case of the neutron detector, it is necessary to measure the position to deduce the scattering angles. We have recently established a two-dimensional position readout system by the following methods: the measurement of horizontal position is enabled by trimming some anodes into wedge-like shape, and vertical position can be determined by the ratio of induced charge on the grid to the total charge on anodes. In addition, improvement of S/N ratio is important for isotope separation and position resolution. We installed a rectangular-shaped GEM and tried improving S/N ratio by electron amplification.

  2. HF production in CMS-Resistive Plate Chambers

    Energy Technology Data Exchange (ETDEWEB)

    Abbrescia, M. [Dipartimento interateneo di Fisica and sezione INFN, Bari (Italy); Colaleo, A. [Dipartimento interateneo di Fisica and sezione INFN, Bari (Italy); Guida, R. [Dipartimento interateneo di Fisica and sezione INFN, Bari (Italy)]. E-mail: Roberto.Guida@ba.infn.it; Iaselli, G. [Dipartimento interateneo di Fisica and sezione INFN, Bari (Italy); Loddo, F. [Dipartimento interateneo di Fisica and sezione INFN, Bari (Italy); Maggi, M. [Dipartimento interateneo di Fisica and sezione INFN, Bari (Italy); Marangelli, B. [Dipartimento interateneo di Fisica and sezione INFN, Bari (Italy); Natali, S. [Dipartimento interateneo di Fisica and sezione INFN, Bari (Italy); Nuzzo, S. [Dipartimento interateneo di Fisica and sezione INFN, Bari (Italy); Pugliese, G. [Dipartimento interateneo di Fisica and sezione INFN, Bari (Italy); Ranieri, A. [Dipartimento interateneo di Fisica and sezione INFN, Bari (Italy); Romano, F. [Dipartimento interateneo di Fisica and sezione INFN, Bari (Italy); Trentadue, R. [Dipartimento interateneo di Fisica and sezione INFN, Bari (Italy); Cavallo, N. [Universita degli studi della Basilicata and Sezione INFN, Naples (Italy); Fabozzi, F. [Universita degli studi della Basilicata and Sezione INFN, Naples (Italy); Paolucci, P. [Dipartimento di Fisica and Sezione INFN, Naples (Italy); Piccolo, D.; Polese, G.; Sciacca, C. [Dipartimento di Fisica and Sezione INFN, Naples (Italy); Belli, G.; Necchi, M.; Ratti, S.; Riccardi, C.; Torre, P.; Vitulo, P. [Dipartimento di Fisica Nucleare e Teorica and Sezione INFN, Pavia (Italy); Anguelov, T.; Genchev, V.; Panev, B.; Piperov, S.; Sultanov, G.; Vankov, P. [INRNE, BAS, Soa (Bulgaria); Litov, L.; Pavlov, B.; Petkov, P. [University of Soa St. Kliment Ohridski (Bulgaria)

    2006-08-15

    The formation of highly reactive compounds in the gas mixture during Resistive Plate Chambers (RPCs) operation at the CERN Gamma Irradiation Facility (GIF) is studied. Results from two different types of chambers are discussed: 50 x 50 cm{sup 2} RPC prototypes and two final CMS-RB1 chambers. The RB1 detectors were also connected to a closed loop gas system. Gas composition, possible additional impurities as well as fluoride ions have been monitored in different gamma irradiation conditions both in open and closed loop mode. The chemical composition of the RPC electrode surface has also been analyzed using an electron microscope equipped with an EDS/X-ray.

  3. High rate resistive plate chamber for LHC detector upgrades

    Energy Technology Data Exchange (ETDEWEB)

    Haddad, Y., E-mail: haddad@llr.in2p3.fr [Laboratoire Leprince-Ringuet (LLR), École Polytechnique, 91120 Palaiseau (France); Laktineh, I.; Grenier, G.; Lumb, N. [IPNL, Villeurbanne 69622 Lyon (France); Cauwenbergh, S. [Ghent University, Ghent (Belgium)

    2013-08-01

    The limitation of the detection rate of standard bakelite resistive plate chambers (RPCs) used as muon detectors in the LHC experiments has prevented the use of such detectors in the high rate regions in both CMS and ATLAS detectors. One alternative to these detectors is RPCs made with low resistivity glass plates (10{sup 10}Ωcm), a beam test at DESY has shown that such detectors can operate at few thousand Hz/cm{sup 2} with high efficiency (>90%)

  4. Methodology for calibration of ionization chambers for X-ray of low energy in absorbed dose to water

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, C.T.; Vivolo, V.; Potiens, M.P.A., E-mail: camila_fmedica@hotmail.com [Instituto de Pesquisas Energeticas e Nucleres (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    The beams of low energy X-ray (10 to 150 kV) are used in several places in the world to treat a wide variety of surface disorders, and between these malignancies. As in Brazil, at this moment, there is no calibration laboratory providing the control service or calibration of parallel plate ionization chambers, the aim of this project was to establish a methodology for calibration of this kind of ionization chambers at low energy X-ray beams in terms of absorbed dose to water using simulators in the LCI. (author)

  5. Project, construction and characterization of ionization chambers for use as standard systems in X and gamma radiation beams; Projeto, construcao e caracterizacao de camaras de ionizacao para utilizacao como sistemas padroes em feixes de radiacao X e gama

    Energy Technology Data Exchange (ETDEWEB)

    Perini, Ana Paula

    2013-07-01

    Ionization chambers present some advantages in relation to other dosimeters: easiness of handling, low energy dependence and high precision. The advantages associated to ionization chambers and the large number of diagnostic radiology exams and therapeutic treatments motivated the development of this PhD program. In this project ionization chambers were developed and characterized to be applied in diagnostic radiology and therapy beam dosimetry, with high precision and performance, in compliance with international recommendations. They were assembled in a simple way, utilizing low-cost national materials, so they can be reproduced and applied at calibration laboratories. The project of these ionization chambers presents some differences in relation to commercial ionization chambers, as the materials utilized and geometrical arrangements. Besides the development of the ionization chambers to be utilized in standard X-ray beam dosimetry as work standard systems, two graphite parallel-plate ionization chambers were developed and characterized to be applied as reference standard systems for determining the air kerma rates of gamma radiation sources. Comparing the air kerma rates determined with the reference standard of the Calibration Laboratory of IPEN, a Farmer ionization chamber, with the values of the air kerma rates obtained with the graphite ionization chambers, the maximum differences obtained were only 1.7% and 1.2% for the G1 and G2 graphite ionization chambers, respectively. Moreover, these ionization chambers presented correction factors close to 1.000, which is ideal for an ionization chamber be characterized as a reference standard system. (author)

  6. Response of ionization chamber based pocket dosimeter to beta radiation.

    Science.gov (United States)

    Kumar, Munish; Gupta, Anil; Pradhan, S M; Bakshi, A K; Chougaonkar, M P; Babu, D A R

    2013-12-01

    Quantitative estimate of the response of ionization chamber based pocket dosimeters (DRDs) to various beta sources was performed. It has been established that the ionization chamber based pocket dosimeters do not respond to beta particles having energy (Emax)1 MeV, the DRDs exhibit measureable response and the values are ~8%, ~14% and ~27% per mSv for natural uranium, (90)Sr/(90)Y and (106)Ru/(106)Rh beta sources respectively. As the energy of the beta particles increases, the response also increases. The response of DRDs to beta particles having energy>1 MeV arises due to the fact that the thickness of the chamber walls is less than the maximum range of beta particles. This may also be one of the reasons for disparity between doses measured with passive/legal dosimeters (TLDs) and DRDs in those situations in which radiation workers are exposed to mixed field of gamma photons and beta particles especially at uranium processing plants, nuclear (power and research) reactors, waste management facilities and fuel reprocessing plants etc. The paper provides the reason (technical) for disparity between the doses recorded by TLDs and DRDs in mixed field of photons and beta particles.

  7. Establishment of a tandem ionization chamber system in standard mammography beams

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Jonas O. da; Caldas, L.V.E., E-mail: jonas.silva@ipen.b, E-mail: lcaldas@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    A double-faced tandem ionization chamber system was developed at the Calibration Laboratory of IPEN. It has different collecting electrode materials: aluminium and graphite. The response repeatability and reproducibility and the energy dependence test of this tandem ionization chamber were evaluated. The chamber response stability is within the {+-}3% limit recommended in international standards. The energy dependence test of the ionization chamber system using the tandem curve obtained, presented agreement with literature results. (author)

  8. Analytical form of current-voltage characteristic of cylindrical and spherical ionization chambers

    CERN Document Server

    Stoyanov, Dimitar G

    2007-01-01

    The basic processes of ionization and recombination of gas-filled ionization chamber are presented in this article. A differential equation describing the distribution of current densities in the volume of the ionization chamber is obtained from the balance of the particles and charges densities. As a result of the differential equation solving an analytical form of the current-voltage characteristic of cylindrical and spherical ionization chambers is got.

  9. ALICE EXPERIMENT Time of Flight Multigap Resistive Plate Chambers

    CERN Multimedia

    2003-01-01

    Charged particules are identified in ALICE by Time-Of-Flight (TOF); heavier particles are slower and it takes for them longer to reach the outer layers of the detector. For TOF system ALICE uses detectors called Multigap Resistive Plate Chambers (MRPC), like the prototype shown here.

  10. A position-sensitive twin ionization chamber for fission fragment and prompt neutron correlation experiments

    Energy Technology Data Exchange (ETDEWEB)

    Göök, A.; Geerts, W.; Hambsch, F.-J.; Oberstedt, S.; Vidali, M. [European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel (Belgium); Zeynalov, Sh. [Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Mosow region (Russian Federation)

    2016-09-11

    A twin position-sensitive Frisch grid ionization chamber, intended as a fission fragment detector in experiments to study prompt fission neutron correlations with fission fragment properties, is presented. Fission fragment mass and energies are determined by means of the double kinetic energy technique, based on conservation of mass and linear momentum. The position sensitivity is achieved by replacing each anode plate in the standard twin ionization chamber by a wire plane and a strip anode, both readout by means of resistive charge division. This provides information about the fission axis orientation, which is necessary to reconstruct the neutron emission process in the fully accelerated fragment rest-frame. The energy resolution compared to the standard twin ionization chamber is found not to be affected by the modification. The angular resolution of the detector relative to an arbitrarily oriented axis is better than 7° FWHM. Results on prompt fission neutron angular distributions in {sup 235}U(n,f) obtained with the detector in combination with an array of neutron scintillation detectors is presented as a proof of principle.

  11. A position-sensitive twin ionization chamber for fission fragment and prompt neutron correlation experiments

    Science.gov (United States)

    Göök, A.; Geerts, W.; Hambsch, F.-J.; Oberstedt, S.; Vidali, M.; Zeynalov, Sh.

    2016-09-01

    A twin position-sensitive Frisch grid ionization chamber, intended as a fission fragment detector in experiments to study prompt fission neutron correlations with fission fragment properties, is presented. Fission fragment mass and energies are determined by means of the double kinetic energy technique, based on conservation of mass and linear momentum. The position sensitivity is achieved by replacing each anode plate in the standard twin ionization chamber by a wire plane and a strip anode, both readout by means of resistive charge division. This provides information about the fission axis orientation, which is necessary to reconstruct the neutron emission process in the fully accelerated fragment rest-frame. The energy resolution compared to the standard twin ionization chamber is found not to be affected by the modification. The angular resolution of the detector relative to an arbitrarily oriented axis is better than 7° FWHM. Results on prompt fission neutron angular distributions in 235U(n,f) obtained with the detector in combination with an array of neutron scintillation detectors is presented as a proof of principle.

  12. Development of Master Chamber Software for Data Acquisition of Ionization Chamber for Indus 2 RRCAT

    Directory of Open Access Journals (Sweden)

    Priyesh Soni

    2013-02-01

    Full Text Available The main goal of this paper was to Develop Master control software for DAQ of ionization chamber for INDUS-2 beam lines for detection of X-ray flux by an Ionization chamber that will remotely control and monitor the ultra low current signal detection analog module precisely. This application will be useful to measure the intensity of X-ray flux through ionization chamber in a beam line of synchrotron radiation source which is mounted in INDUS-2. It is one of new technique of detection. Beam line area is highly restricted because of hazardous radiation, so through this application remote interfacing is provided for the ultra low current signal detection card that can be controlled by Master software. The development of such type arrangement we used software in C#.NET there are many issues like develop code, Design forms, to achieve the specified response from the CPU card, code developed in C# .NET. Initially, I explored and gained the knowledge of C#.NET. I practices some small modular projects as part to learn how the system works. I used programming language C#.NET architecture version 3.5 in Visual Studio 2008

  13. Wave Damping over a Perforated Plate with Water Chambers

    Institute of Scientific and Technical Information of China (English)

    ZHU Shutang

    2006-01-01

    The movement of waves propagating over a horizontally submerged perforated plate with waterfilled chambers bellow the plate was investigated by using linear potential theory. The analytical solution was compared with laboratory experiments on wave blocking. The analysis of the wave energy dissipation on the perforated bottom surface shows that the effects of the perforated plate on thewave motion depend mainly on the plate porosity, the wave height, and the wave period. The wave number is a complex number when the wave energy dissipation on the perforated plate is considered. The real part of the wave number refers to the spatial periodicity while the imaginary part represents the damping modulus. The characteristics of the wave motion were explored for several possible conditions.

  14. Use of a liquid ionization chamber for stereotactic radiotherapy dosimetry.

    Science.gov (United States)

    Wagner, A; Crop, F; Lacornerie, T; Vandevelde, F; Reynaert, N

    2013-04-21

    Liquid ionization chambers (LICs) offer an interesting tool in the field of small beam dosimetry, allowing better spatial resolution and reduced perturbation effects. However, some aspects remain to be addressed, such as the higher recombination and the effects from the materials of the detector. Our aim was to investigate these issues and their impact. The first step was the evaluation of the recombination effects. Measurements were performed at different SSDs to vary the dose per pulse, and the collection efficiency was obtained. The BEAMnrc code was then used to model the Cyberknife head. Finally, the liquid ionization chamber itself was modelled using the EGSnrc-based code Cavity allowing the evaluation of the influence of the volume and the chamber materials. The liquid ionization charge collection efficiency is approximately 0.98 at 1.5 mGy pulse(-1), the highest dose per pulse that we have measured. Its impact on the accuracy of output factors is less than half a per cent. The detector modelling showed a significant contribution from the graphite electrode, up to 6% for the 5 mm collimator. The dependence of the average electronic mass collision stopping power of iso-octane with beam collimation is negligible and thus has no influence on output factor measurements. Finally, the volume effect reaches 5% for the small 5 mm collimator and becomes much smaller (<0.5%) for diameters above 10 mm. LICs can effectively be used for small beam relative dosimetry as long as adequate correction factors are applied, especially for the electrode and volume effects.

  15. An online monitor ionization chamber used in particle therapy

    Institute of Scientific and Technical Information of China (English)

    TANG Bin; HU Zhengguo; MAO Ruishi; XU Zhiguo; WANG Jiansong; YUE Ke; TU Xiaolin; WU Dapeng; CHEN Jinda; ZHANG Jie; WANG Meng; SUN Zhiyu; ZHANG Xueheng; LI Qiang; XU Hushan; XIOA Guoqing

    2009-01-01

    The clinical trials of tumor therapy using heavy ions beam 12C are now in progress at Institute of Modern Physics in Lanzhou. In order to achieve the precise radiotherapy with the high energy 12C beam in active pencil beam scanning mode, we have developed an ionization chamber(IC) as an online monitor for beam intensity and also a do-simeter after calibration. Through the choosing of working gas and voltage, optimizing of the electrics and the read-out system, calibrating the linearity, the detector system provide us one of the simple and highly reliable way to monitoring the beam during the active pencil beam scanning treatments. The measurement results of this detector sys-tem show that it could work well under the condition of high energy 12C beam in active pencil beam scanning mode.

  16. Amplitude distribution of ionization jerks in ionization-chamber ASK-1 according long-term measurements

    Science.gov (United States)

    Timofeev, Vladislav

    2016-07-01

    As part of the Yakut complex systems by measuring the intensity of cosmic rays has a unique device spherical - ionization chamber ASK-1 with a lead screen thickness of 12 cm. The camera allows you to explore the physical characteristics of the so-called "ionization jerks " - sharp increases ionization current caused by the passage through the device much ionizing particles of cosmic origin. Due to a large increase in current nuclear cascade "showers", formed mainly by particles of cosmic rays in the camera screen. Over the entire period of observation (50 years old) camera ASK-1 was registered 59125 aftershocks. Their nature and properties still does not sufficiently studied, especially in medium and large amplitudes.

  17. Performance parameters of a liquid filled ionization chamber array.

    Science.gov (United States)

    Poppe, B; Stelljes, T S; Looe, H K; Chofor, N; Harder, D; Willborn, K

    2013-08-01

    In this work, the properties of the two-dimensional liquid filled ionization chamber array Octavius 1000SRS (PTW-Freiburg, Germany) for use in clinical photon-beam dosimetry are investigated. Measurements were carried out at an Elekta Synergy and Siemens Primus accelerator. For measurements of stability, linearity, and saturation effects of the 1000SRS array a Semiflex 31013 ionization chamber (PTW-Freiburg, Germany) was used as a reference. The effective point of measurement was determined by TPR measurements of the array in comparison with a Roos chamber (type 31004, PTW-Freiburg, Germany). The response of the array with varying field size and depth of measurement was evaluated using a Semiflex 31010 ionization chamber as a reference. Output factor measurements were carried out with a Semiflex 31010 ionization chamber, a diode (type 60012, PTW-Freiburg, Germany), and the detector array under investigation. The dose response function for a single detector of the array was determined by measuring 1 cm wide slit-beam dose profiles and comparing them against diode-measured profiles. Theoretical aspects of the low pass properties and of the sampling frequency of the detector array were evaluated. Dose profiles measured with the array and the diode detector were compared, and an intensity modulated radiation therapy (IMRT) field was verified using the Gamma-Index method and the visualization of line dose profiles. The array showed a short and long term stability better than 0.1% and 0.2%, respectively. Fluctuations in linearity were found to be within ±0.2% for the vendor specified dose range. Saturation effects were found to be similar to those reported in other studies for liquid-filled ionization chambers. The detector's relative response varied with field size and depth of measurement, showing a small energy dependence accounting for maximum signal deviations of ±2.6% from the reference condition for the setup used. The σ-values of the Gaussian dose response

  18. Performance parameters of a liquid filled ionization chamber array

    Energy Technology Data Exchange (ETDEWEB)

    Poppe, B.; Stelljes, T. S.; Looe, H. K.; Chofor, N. [Clinic for Radiation Therapy, Pius-Hospital, Oldenburg 26121, Germany and WG Medical Radiation Physics, Carl von Ossietzky University, Oldenburg 26121 (Germany); Harder, D. [Prof. em., Medical Physics and Biophysics, Georg August University, Göttingen 37073 (Germany); Willborn, K. [Clinic for Radiation Therapy, Pius-Hospital, Oldenburg 26121 (Germany)

    2013-08-15

    Purpose: In this work, the properties of the two-dimensional liquid filled ionization chamber array Octavius 1000SRS (PTW-Freiburg, Germany) for use in clinical photon-beam dosimetry are investigated.Methods: Measurements were carried out at an Elekta Synergy and Siemens Primus accelerator. For measurements of stability, linearity, and saturation effects of the 1000SRS array a Semiflex 31013 ionization chamber (PTW-Freiburg, Germany) was used as a reference. The effective point of measurement was determined by TPR measurements of the array in comparison with a Roos chamber (type 31004, PTW-Freiburg, Germany). The response of the array with varying field size and depth of measurement was evaluated using a Semiflex 31010 ionization chamber as a reference. Output factor measurements were carried out with a Semiflex 31010 ionization chamber, a diode (type 60012, PTW-Freiburg, Germany), and the detector array under investigation. The dose response function for a single detector of the array was determined by measuring 1 cm wide slit-beam dose profiles and comparing them against diode-measured profiles. Theoretical aspects of the low pass properties and of the sampling frequency of the detector array were evaluated. Dose profiles measured with the array and the diode detector were compared, and an intensity modulated radiation therapy (IMRT) field was verified using the Gamma-Index method and the visualization of line dose profiles.Results: The array showed a short and long term stability better than 0.1% and 0.2%, respectively. Fluctuations in linearity were found to be within ±0.2% for the vendor specified dose range. Saturation effects were found to be similar to those reported in other studies for liquid-filled ionization chambers. The detector's relative response varied with field size and depth of measurement, showing a small energy dependence accounting for maximum signal deviations of ±2.6% from the reference condition for the setup used. The σ-values of

  19. Analytical form of current-voltage characteristic of parallel-plane, cylindrical and spherical ionization chambers with homogeneous ionization

    CERN Document Server

    Stoyanov, Dimitar G

    2007-01-01

    The elementary processes taking place in the formation of charged particles and their flow in the ionization chamber are considered. On the basic of particles and charges balance a differential equation describing the distribution of current densities in the ionization chamber volume is obtained. As a result of the differential equation solution an analytical form of the current-voltage.

  20. Imaging with high Dynamic using an Ionization Chamber

    CERN Document Server

    Menk, Ralf-Hendrik; Arfelli, Fulvia; Bernstorff, Sigrid; Besch, Hans Juergen; Voltolina, Francesco

    2010-01-01

    In this work a combination of an ionization chamber with one-dimensional spatial resolution and a MicroCAT structure will be presented. The combination between gas gain operations and integrating front-end electronics yields a dynamic range as high as eight to nine orders of magnitude. Therefore this device is well suitable for medical imaging or applications such as small angle x-ray scattering, where the requirements on the dynamic of the detector are exceptional high. Basically the described detector is an ionization chamber adapted to fan beam geometry with an active area of 192 cm and a pitch of the anode strips of 150 micrometer. In the vertical direction beams as high as 10 mm can be accepted. Every read-out strip is connected to an analogue integrating electronics channel realized in a custom made VLSI chip. A MicroCAT structure utilized as a shielding grid enables frame rates as high as 10kHz. The high dynamic range observed stems from the fact that the MicroCAT enables active electron amplification ...

  1. Development of a portable gas-filled ionization chamber

    Energy Technology Data Exchange (ETDEWEB)

    Chae, K. Y.; Cha, S. M.; Gwak, M. S. [Sungkyunkwan University, Suwon (Korea, Republic of)

    2014-02-15

    A new portable gas-filled ionization chamber has been designed and constructed at the Physics Department of Sung Kyun Kwan University. To overcome the maximum count rate of ∼ 10{sup 5} particles per second of a conventional ionization chamber, which utilizes a Frisch grid, and to enhance the portability of a detector, we adopted the design of multiple electrodes and modified it from the original designs by Kimura et al. and Chae et al. The new design utilizes a stack of multiple electrodes installed perpendicular to the optical beam axis. This configuration provides a fast response time for the detector, which is essential for high-rate counting. The device has been tested with a {sup 241}Am (t{sub 1/2} = 432.2 years) radioactive α source, which mainly emits 5.486-MeV (branching ratio of 85%) and 5.443-MeV (branching ratio of 13%) α particles. An energy resolution of 6.3% was achieved.

  2. An ionization chamber shower detector for the LHC luminosity monitor

    CERN Document Server

    Beche, J F; Datte, P S; Haguenauer, Maurice; Manfredi, P F; Millaud, J E; Placidi, Massimo; Ratti, L; Re, V; Riot, V J; Schmickler, Hermann; Speziali, V; Turner, W C

    2000-01-01

    The front IR quadrupole absorbers (TAS) and the IR neutral particle absorbers (TAN) in the high luminosity insertions of the Large Hadron Collider (LHC) each absorb approximately 1.8 TeV of forward collision products on average per pp interaction (~235 W at design luminosity 10/sup 34/ cm/sup -2/ s/sup -1/). This secondary particle flux can be exploited to provide a useful storage ring operations tool for optimization of luminosity. A novel segmented, multi-gap, pressurized gas ionization chamber is being developed for sampling the energy deposited near the maxima of the hadronic/electromagnetic showers in these absorbers. The system design choices have been strongly influenced by optimization of signal to noise ratio and by the very high radiation environment. The ionization chambers are instrumented with low noise, fast, pulse shaping electronics to be capable of resolving individual bunch crossings at 40 MHz. Data on each bunch are to be separately accumulated over multiple bunch crossings until the desire...

  3. Resistive Plate Chambers for Imaging Calorimetry - the DHCAL

    CERN Document Server

    Repond, Jose

    2014-01-01

    The DHCAL, the Digital Hadron Calorimeter, is a prototype calorimeter based on Resistive Plate Chambers (RPCs). The design emphasizes the imaging capabilities of the detector in an effort to optimize the calorimeter for the application of Particle Flow Algorithms (PFAs) to the reconstruction of hadronic jet energies in a colliding beam environment. The readout of the chambers is segmented into 1 x 1 cm2 pads, each read out with a 1-bit (single threshold) resolution. The prototype with approximately 500,000 readout channels underwent extensive testing in both the Fermilab and CERN test beams. This talk presents preliminary findings from the analysis of data collected at the test beams.

  4. The Detector Control Systems for the CMS Resistive Plate Chamber

    CERN Document Server

    Paolucci, P; Gómez-Reino, R; Viviani, C; Shahzad, R; Khurshid, T

    2010-01-01

    The Resistive Plate Chamber system is composed by 912 double-gap chambers equipped with about $10^4$ front-end boards. The correct and safe operation of the RPC system requires a sophisticated and complex online Detector Control System, able to monitor and control 2$\\cdot10^4$ hardware devices distributed on an area of about 5000 m$^2$. The RPC DCS acquires, monitors and stores about $10^5$ parameters coming from the detector, the electronics, the power system, the gas, and cooling systems. The DCS system and the first results, obtained during the 2007 and 2008 CMS cosmic runs, will be described in this paper.

  5. A high time resolution multi-gap resistive plate chamber

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Research on a single cell Multi-gap Resistive Plate Chamber (MR PC)was carried out for the Time Of Flight detector (TOF) R and D of the STAR experi-ment. The property of the single chamber was tested with the test beam facility T10at CERN in Geneva. The MRPC was scanned with the test beam to get the efficiencyand time resolution at different position of the active area. The HV plateau was alsomeasured. The time resolution is 65 ps which satisfies the requirement of STAR. Theworking mechanism of the MRPC is also explained.

  6. Cosmic ray tests of large area Multigap Resistive Plate Chambers

    CERN Document Server

    An, S; Kim, J; Williams, M C S; Zichichi, A; Zuyeuski, R

    2007-01-01

    We have built Multigap Resistive Plate Chambers (MRPC) with six gas gaps and an active area of . The signals are generated on 2.5 cm wide copper pickup strips; these are read out at each end thus allowing the position of the hit along the strip to be obtained from the time difference. Using three of these chambers we have set up a cosmic tracking system in a similar manner as planned for the Extreme Energy Events (EEE) project. The details of the set-up are presented in this paper. In addition we discuss the time and position resolution of these MRPCs measured using cosmic rays.

  7. Analytical form of current-voltage characteristic of parallel-plane, cylindrical and spherical ionization chambers with homogeneous ionization

    Energy Technology Data Exchange (ETDEWEB)

    Stoyanov, D G [Faculty of Engineering and Pedagogy in Sliven, Technical University of Sofia, 59, Bourgasko Shaussee Blvd, 8800 Sliven (Bulgaria)

    2007-11-15

    The elementary processes taking place in the formation of charged particles and their flow in parallel-plane, cylindrical and spherical geometry cases of ionization chamber are considered. On the basis of particles and charges balance a differential equation describing the distribution of current densities in the ionization chamber volume is obtained. As a result of the differential equation solution an analytical form of the current-voltage characteristic of an ionization chamber with homogeneous ionization is obtained. For the parallel-plane case comparision with experimental data is performed.

  8. Comparison between a commercial and homemade ionization chamber for dosimetry of {sup 60}Co beams

    Energy Technology Data Exchange (ETDEWEB)

    Neves, Lucio P.; Perini, Ana P.; Caldas, Linda V.E., E-mail: lpneves@ipen.b, E-mail: aperini@ipen.b, E-mail: lcaldas@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    The Calibration Laboratory at IPEN/CNEN (LCI) has developed several ionization detectors for dosimetry in diagnostic radiology, radiation protection and radiotherapy. Recently, a cylindrical ionization chamber, with a sensitive volume of 1.06cm{sup 3}, was developed, and several tests were performed to characterize this ionization chamber for radiotherapy level. The results showed that its performance was within the recommended international limits. In order to complement the studies regarding the response of this ionization chamber, in this work, the chamber response was compared with that of a commercial ionization chamber Farmer PTW, model TN30011-1. The ionization chamber produced at LCI is made of PVC and PMMA. A special build-up cap for {sup 60}Co beams was made of acrylic, with 4.00 mm thickness. All tests of both ionization chambers were performed under the same conditions, allowing good geometrical reproducibility. The performed tests were: saturation, ion collection efficiency, polarity effect and chamber tilt. The results obtained in this comparison program were all within the international recommendations, and demonstrate a good agreement of the performance of the commercial and the homemade ionization chambers. From this comparison results and from previous data, it is possible to conclude that the ionization chamber produced at IPEN presents usefulness for dosimetric applications at radiotherapy level in {sup 60}Co beams.(author)

  9. Simulation of space charge effects in resistive plate chambers

    CERN Document Server

    Lippmann, Christian

    2003-01-01

    Multigap resistive plate chambers with 0.3-mm gas gaps operated in avalanche mode at atmospheric pressure have reached timing accuracies below 50 ps (standard deviation) with efficiencies above 99% . The avalanches in high homogeneous electric fields of 100 kV/cm are strongly influenced by space charge effects which are the main topic of this paper. We extend a previously discussed Monte Carlo simulation model of avalanches in resistive plate chambers by the dynamic calculation of the electric field in the avalanches. We complete the previously presented results on time resolution and efficiency data with simulated charge spectra. The simulated data shows good agreement with measurements. The detailed simulation of the avalanche saturation due to the space charge fields explains the small observed charges, the shape of the spectra, and the linear increase of average charges with high voltage. (22 refs).

  10. Resistive plate chambers for time-of-flight measurements

    Energy Technology Data Exchange (ETDEWEB)

    Blanco, A.; Fonte, P. E-mail: fonte@lipc.fis.uc.pt; Lopes, L.; Mangiarotti, A.; Ferreira-Marques, R.; Policarpo, A

    2003-11-01

    The applications of Resistive Plate Chambers (RPCs) have recently been extended by the development of counters with time resolution below 100 ps {sigma} for minimum ionising particles. Applications to HEP experiments have already taken place and many further applications are under study. In this work, we address the operating principles of such counters along with some present challenges, with emphasis on counter ageing. Possible applications to radioisotope imaging will be outlined.

  11. Resistive Plate Chambers commissioning and performance results for 2015

    CERN Document Server

    CMS Collaboration

    2016-01-01

    The Resistive Plate Chamber (RPC) detector system at the Compact Muon Solenoid experiment at the LHC confers robustness and redundancy to the muon trigger. During the first long shutdown of the LHC (2013-2014) the CMS muon RPC system has been upgraded with 144 double-gap chambers on the forth forward stations. A total of 1056 double-gap chambers cover the pseudo-rapidity region up to 1.6. The main detector parameters are constantly and closely monitored to achieve operational stability and high quality data in the harsh conditions of the second run period of the LHC (13 TeV and 25 ns bunch spacing). Resistive Plate Chambers (RPC) performance results for 2015 with pp collisions at 13 TeV are presented. These results include the occupancy, efficiency of newly installed detectors after applying new working point, history plots for the RPC relevant variables such as: Cluster Size, Efficiency, percentage of inactive detector during operation and Rates and overall system noise. RPC variables are studied as funct...

  12. An automated ionization chamber for secondary radioactivity standards.

    Science.gov (United States)

    Fitzgerald, R

    2010-01-01

    I report on the operation and characterization of a new ionization chamber system, "AUTOIC", featuring a commercial digital electrometer and a commercial robotic sample changer. The relative accuracy of the electrometer was improved significantly beyond the manufacturer's specifications through an in-house calibration of the various ranges, applied via software. The measurement precision and repeatability of the system have been determined by measuring multiple samples of the same radionuclide over the span of two or three years. The linearity of the system was examined by following the decay of (99m)Tc, (99)Mo and (133)Xe sources for up to 19 half-lives and determining half-life values. All of these values agree with the accepted literature values, within their combined uncertainties.

  13. An automated ionization chamber for secondary radioactivity standards

    Energy Technology Data Exchange (ETDEWEB)

    Fitzgerald, R., E-mail: ryan.fitzgerald@nist.go [Physics Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899 (United States)

    2010-07-15

    I report on the operation and characterization of a new ionization chamber system, 'AUTOIC', featuring a commercial digital electrometer and a commercial robotic sample changer. The relative accuracy of the electrometer was improved significantly beyond the manufacturer's specifications through an in-house calibration of the various ranges, applied via software. The measurement precision and repeatability of the system have been determined by measuring multiple samples of the same radionuclide over the span of two or three years. The linearity of the system was examined by following the decay of {sup 99m}Tc, {sup 99}Mo and {sup 133}Xe sources for up to 19 half-lives and determining half-life values. All of these values agree with the accepted literature values, within their combined uncertainties.

  14. Investigation of electron-loss and photon scattering correction factors for FAC-IR-300 ionization chamber

    Science.gov (United States)

    Mohammadi, S. M.; Tavakoli-Anbaran, H.; Zeinali, H. Z.

    2017-02-01

    The parallel-plate free-air ionization chamber termed FAC-IR-300 was designed at the Atomic Energy Organization of Iran, AEOI. This chamber is used for low and medium X-ray dosimetry on the primary standard level. In order to evaluate the air-kerma, some correction factors such as electron-loss correction factor (ke) and photon scattering correction factor (ksc) are needed. ke factor corrects the charge loss from the collecting volume and ksc factor corrects the scattering of photons into collecting volume. In this work ke and ksc were estimated by Monte Carlo simulation. These correction factors are calculated for mono-energy photon. As a result of the simulation data, the ke and ksc values for FAC-IR-300 ionization chamber are 1.0704 and 0.9982, respectively.

  15. NIST Ionization Chamber “A” Sample-Height Corrections

    Science.gov (United States)

    Fitzgerald, Ryan

    2012-01-01

    For over 30 years scientists in the NIST radioactivity group have been using their pressurized ionization chamber “A” (PIC “A”) to make measurements of radioactivity and radioactive half-lives. We now have evidence that some of those reported measurements were incorrect due to slippage of the source positioning ring over time. The temporal change in the holder caused an error in the source-height within the chamber, which was thought to be invariant. This unaccounted-for height change caused a change in the detector response and thus a relative error in measured activity on the order of 10−5 to 10−3 per year, depending on the radionuclide. The drifting detector response affected calibration factors and half-life determinations. After discovering the problem, we carried out historic research and new sensitivity tests. As a result, we have created a quantitative model of the effect and have used that model to estimate corrections to some of the past measurement results from PIC “A”. In this paper we report the details and results of that model. Meanwhile, we have fixed the positioning ring and are recalibrating the detector using primary measurement methods and enhanced quality control measures. PMID:26900515

  16. NIST Ionization Chamber "A" Sample-Height Corrections.

    Science.gov (United States)

    Fitzgerald, Ryan

    2012-01-01

    For over 30 years scientists in the NIST radioactivity group have been using their pressurized ionization chamber "A" (PIC "A") to make measurements of radioactivity and radioactive half-lives. We now have evidence that some of those reported measurements were incorrect due to slippage of the source positioning ring over time. The temporal change in the holder caused an error in the source-height within the chamber, which was thought to be invariant. This unaccounted-for height change caused a change in the detector response and thus a relative error in measured activity on the order of 10(-5) to 10(-3) per year, depending on the radionuclide. The drifting detector response affected calibration factors and half-life determinations. After discovering the problem, we carried out historic research and new sensitivity tests. As a result, we have created a quantitative model of the effect and have used that model to estimate corrections to some of the past measurement results from PIC "A". In this paper we report the details and results of that model. Meanwhile, we have fixed the positioning ring and are recalibrating the detector using primary measurement methods and enhanced quality control measures.

  17. Performance of the ETH gas ionization chamber at low energy

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, A.M., E-mail: arnold.mueller@phys.ethz.ch [Laboratory of Ion Beam Physics, ETH-Zurich, Schafmattstrasse 20, CH-8093 Zurich (Switzerland); Doebeli, M.; Suter, M.; Synal, H.-A. [Laboratory of Ion Beam Physics, ETH-Zurich, Schafmattstrasse 20, CH-8093 Zurich (Switzerland)

    2012-09-15

    The performance of gas ionization chambers (GIC) for the detection of low energy ions has been considerably improved in the past years by the use of silicon nitride entrance windows and low noise preamplifiers. This has led to an increased use of high resolution GICs in the fields of accelerator mass spectrometry and ion beam analysis. This development and the underlying physical principles are reviewed and the latest technical status of such devices is summarized. A detailed study on energy resolution and pulse height defect is presented with projectiles covering a wide particle mass range (H, {sup 9}Be, {sup 13}C, {sup 27}Al, {sup 35}Cl, {sup 127}I, {sup 232}Th) with energies between 0.1 and 2.2 MeV. The dependence of energy resolution and charge output per unit particle energy on the nuclear charge of the projectile is investigated and parametrized. SRIM calculations of ionizing energy loss considerably differ from these experimental findings. For 1 MeV particles discrepancies up to 50% are observed. The performance of GICs and their practical use is compared to that of solid state detectors. The potential for further improvement of the technology and its fields of application are assessed.

  18. Polarity correction factor for flattening filter free photon beams in several cylindrical ionization chambers.

    Science.gov (United States)

    Ogata, Toshiyuki; Uehara, Kazuyuki; Nakayama, Masao; Tsudou, Shinji; Masutani, Takashi; Okayama, Takanobu

    2016-07-01

    In this study, we aimed to compare the polarity correction factor in ionization chambers for flattening filter free (FFF) photon beams and flattening filter (FF) beams. Measurements were performed with both 6 and 10 MV FFF and FF beams. Five commercial ionization chambers were evaluated: PTW TN30013; IBA Dosimetry CC01, CC04, and CC13; and Exradin A12S. Except for the CC01 ionization chamber, the other four chambers showed less than a 0.3 % difference in the polarity effect between the FFF and the FF beams. The CC01 chamber showed a strong field-size-dependence, unlike the other chambers. The polarity effect for all chambers with FFF beams did not change with the dose rate. Except in the case of the CC01 chamber, the difference in the polarity effect between FFF and FF beams was not significant.

  19. Theoretical Calculation and Monte Carlo Simulation of Photon Energy Response of Large Size Cavity Ionization Chamber

    Institute of Scientific and Technical Information of China (English)

    SONG; Ming-zhe; WEI; Ke-xin; HOU; Jin-bing; WANG; Hong-yu; GAO; Fei; NI; Ning

    2015-01-01

    The Bragg-Gray cavity theory(B-G theory)provided a theoretical basis for the analytical calculation of the energy response for ionization chamber.It was widely used in the theoretical calculation of the ionization chamber detector and the tissue equivalent detector.However,the B-G

  20. A time dependent solution for the operation of ion chambers in a high ionization background

    CERN Document Server

    Velissaris, C

    2005-01-01

    We have derived a time dependent solution describing the development of space charge inside an ion chamber subjected to an externally caused ionization rate N. The solution enables the derivation of a formula that the operational parameters of the chamber must satisfy for saturation free operation. This formula contains a correction factor to account for the finite duration of the ionization rate N.

  1. A measure method of the time respond function for gas ionization chamber

    CERN Document Server

    Wang Li; Qing Shang Yu

    2002-01-01

    In quick scanning radiography system, the time respond speed of array gas ionization chamber effects the image clarity directly. The author presents a measure method of the time respond function for gas ionization chamber. The image clarity will be improved by inverse convoluting the image data

  2. Use of a novel two-dimensional ionization chamber array for pencil beam scanning proton therapy beam quality assurance.

    Science.gov (United States)

    Lin, Liyong; Kang, Minglei; Solberg, Timothy D; Mertens, Thierry; Baeumer, Christian; Ainsley, Christopher G; McDonough, James E

    2015-05-08

    The need to accurately and efficiently verify both output and dose profiles creates significant challenges in quality assurance of pencil beam scanning (PBS) proton delivery. A system for PBS QA has been developed that combines a new two-dimensional ionization chamber array in a waterproof housing that is scanned in a water phantom. The MatriXX PT has the same detector array arrangement as the standard MatriXX(Evolution) but utilizes a smaller 2 mm plate spacing instead of 5mm. Because the bias voltage of the MatriXX PT and Evolution cannot be changed, PPC40 and FC65-G ionization chambers were used to assess recombination effects. The PPC40 is a parallel plate chamber with an electrode spacing of 2mm, while the FC65-G is a Farmer chamber FC65-G with an electrode spacing of 2.8 mm. Three bias voltages (500, 200, and 100 V) were used for both detectors to determine which radiation type (continuous, pulse or pulse-scanned beam) could closely estimate Pion from the ratios of charges collected. In comparison with the MatriXX(Evolution), a significant improvement in measurement of absolute dose with the MatriXX PT was observed. While dose uncertainty of the MatriXX(Evolution) can be up to 4%, it is 1%; chambers with an electrode spacing of 2 mm or smaller are recommended.

  3. Study of Performance of Bakelite Resistive Plate Chamber (RPC)

    CERN Document Server

    Ganai, R; Roy, A; Muduli, B; Chattopadhyay, S; Ahammed, Z; Das, G; Ramnarayan, S

    2016-01-01

    Resistive Plate Chamber (RPC) is a type of gaseous detector having excellent time and position resolutions. VECC is involved in the R\\&D of indigenously developed bakelite RPCs. The largest size of bakelite RPC developed in India is 100 cm $\\times$ 100 cm. We present here the test results of a bakelite sample along with the cosmic ray test results of a bakelite RPC (30 cm $\\times$ 30 cm $\\times$ 0.2cm) fabricated at VECC. The steps taken towards the development of a large size (240 cm $\\times$ 120 cm $\\times$ 0.2 cm) bakelite RPC have also been discussed.

  4. Resistive plate chambers for muon detection at LHC

    Institute of Scientific and Technical Information of China (English)

    叶沿林; 应军; 班勇; 刘洪涛; 蔡建新; 朱子美; 马经国; 陈陶; 钱思进

    2002-01-01

    One resistive plate chamber made of Chinese materials and one Italian resistive platechamber have been tested in the Gamma Irradiation Facility (GIF) at CERN on a high intensitymuon beam together with a 137Cs source to give a uniform photon background, and simulatingconditions close to those expected for an LHC muon detector. The results are analyzed. Goodspace and time resolutions are obtained which satisfy the future CMS experiment requirements.The detection efficiency is different between two RPCs against a high irradiation background. Thereason is discussed.

  5. A new method for measuring the response time of the high pressure ionization chamber.

    Science.gov (United States)

    Wang, Zhentao; Shen, Yixiong; An, Jigang

    2012-08-01

    Time response is an important performance characteristic for gas-pressurized ionization chambers. To study the time response, it is especially crucial to measure the ion drift time in high pressure ionization chambers. In this paper, a new approach is proposed to study the ion drift time in high pressure ionization chambers. It is carried out with a short-pulsed X-ray source and a high-speed digitizer. The ion drift time in the chamber is then determined from the digitized data. By measuring the ion drift time of a 15 atm xenon testing chamber, the method has been proven to be effective in the time response studies of ionization chambers.

  6. Comparação entre fatores de calibração em termos de dose absorvida no ar para uma câmara de ionização de placas paralelas Comparison of absorbed dose to air calibration factors for a parallel plate ionization chamber

    Directory of Open Access Journals (Sweden)

    Roseli T. Bulla

    2006-06-01

    Full Text Available OBJETIVO: O objetivo deste trabalho foi realizar uma comparação entre os fatores de calibração em termos de dose absorvida no ar determinados em feixes gama (60Co e de elétrons. MATERIAIS E MÉTODOS: Foram utilizados um irradiador de 60Co e um acelerador linear Varian, modelo Clinac 2100C, com feixes de fótons e de elétrons. Foram testadas uma câmara de ionização cilíndrica e três de placas paralelas. RESULTADOS: Os sistemas de medidas foram submetidos aos testes preliminares (estabilidade de resposta e corrente de fuga, com resultados muito bons. Os fatores de calibração em termos de dose absorvida no ar foram determinados utilizando-se quatro sistemas de medidas e dois tipos de objetos simuladores, com a obtenção de resultados dentro das recomendações internacionais. CONCLUSÃO: Os resultados mostraram que os fatores de calibração em termos de dose absorvida no ar obtidos para câmaras de ionização de placas paralelas, determinados em feixes de 60Co, são no máximo 1,2% mais altos que os valores obtidos em feixes de elétrons de altas energias.OBJECTIVE: The objective of this study was to compare the absorbed dose to air calibration factors determined in gamma (60Co and electron beams. MATERIALS AND METHODS: An irradiator with a 60Co source and a Varian, Clinac 2100C linear accelerator with photon and electron beams were utilized. One thimble-type and three parallel-plate ionization chambers were tested. RESULTS: The measurement systems were submitted to preliminary tests (response stability and leakage current, with quite good results. The absorbed dose to air calibration factors were determined using four measurement systems and two types of phantoms. Results were obtained in compliance with the international recommendations. CONCLUSION: Absorbed dose to air calibration factors obtained for parallel plate ionization chambers, determined in 60Co beams, at maximum, are 1.2% higher than the values obtained in high energy

  7. Parallel plate chambers for monitoring the profiles of high-intensity pulsed antiproton beams

    CERN Document Server

    Hori, Masaki

    2004-01-01

    Two types of beam profile monitor with thin parallel-plate electrodes have been used in experiments carried out at the Low Energy Antiproton Ring (LEAR) and Antiproton Decelerator (AD) of CERN. The detectors were used to measure non-destructively the spatial profiles, absolute intensities, and time structures of 100-300-ns- long beam pulses containing between 10**7 and 10**9 antiprotons. The first of these monitors was a parallel plate ionization chamber operated at gas pressure P=65 mbar. The other was a secondary electron emission detector, and was operated in the ultra-high vacuum of the AD. Both designs may be useful in medical and commercial applications. The position-sensitive electrodes in these detectors were manufactured by a novel method in which a laser trimmer was used to cut strip patterns on metallized polyester foils.

  8. Strip Ionization Chamber as Beam Monitor in the Proton Therapy Eye Treatment

    Science.gov (United States)

    Marchetto, F.; Cirio, R.; Garella, M. A.; Giordanengo, S.; Boriano, A.; Givehchi, N.; La Rosa, A.; Peroni, C.; Donetti, M.; Bourhaleb, F.; Pitta', G.; Cirrone, G. A. P.; Cuttone, G.; Raffaele, L.; Sabini, M. G.; Valastro, L.

    2006-04-01

    Since spring 2002, ocular pathologies have been treated in Catania at the Centro di AdroTerapia e Applicazioni Nucleari Avanzate (CATANA) within a collaboration between INFN Laboratori Nazionali del Sud (LNS), Physics Department, Ophthalmology Institute, Radiology Institute of the Catania University and CSFNSM Catania. A beam line from a 62 MeV Superconducting Cyclotron is used to treat shallow tumors. The beam is conformed to the tumor shape with a passive delivery system. A detector system has been developed in collaboration with INFN-Torino to be used as real time beam monitor. The detector, placed upstream of the patient collimator, consists of two parallel plate ionization chambers with the anode segmented in strips. Each anode is made of 0.5 mm-wide 256 strips corresponding to (12.8 × 12.8) cm2 sensitive area. With the two strip ionization chambers one can measure the relevant beam parameters during treatment to probe both asymmetry and flatness. In the test carried out at CATANA the detector has been used under different and extreme beam conditions. Preliminary results are given for profiles and skewness, together with a comparison with reference detectors.

  9. A double faced ionization chamber for quality control in diagnostic radiology beams.

    Science.gov (United States)

    Silva, Jonas O; Caldas, Linda V E

    2012-07-01

    The development of new radiation detectors of low cost but with adequate materials is a very important task for countries that have to import ionization chambers such as Brazil. A special double faced ionization chamber was developed for use in conventional diagnostic radiology beams and computed tomography energy ranges. The results show that this new chamber present applicability in conventional diagnostic radiology and computed tomography quality control programs.

  10. High spatial resolution dosimetric response maps for radiotherapy ionization chambers measured using kilovoltage synchrotron radiation

    Science.gov (United States)

    Butler, D. J.; Stevenson, A. W.; Wright, T. E.; Harty, P. D.; Lehmann, J.; Livingstone, J.; Crosbie, J. C.

    2015-11-01

    Small circular beams of synchrotron radiation (0.1 mm and 0.4 mm in diameter) were used to irradiate ionization chambers of the types commonly used in radiotherapy. By scanning the chamber through the beam and measuring the ionization current, a spatial map of the dosimetric response of the chamber was recorded. The technique is able to distinguish contributions to the large-field ionization current from the chamber walls, central electrode and chamber stem. Scans were recorded for the NE 2571 Farmer chamber, the PTW 30013, IBA FC65-G Farmer-type chambers, the NE 2611A and IBA CC13 thimble chambers, the PTW 31006 and 31014 pinpoint chambers, the PTW Roos and Advanced Markus plane-parallel chambers, and the PTW 23342 thin-window soft x-ray chamber. In all cases, large contributions to the response arise from areas where the incident beam grazes the cavity surfaces. Quantitative as well as qualitative information about the relative chamber response was extracted from the maps, including the relative contribution of the central electrode. Line scans using monochromatic beams show the effect of the photon energy on the chamber response. For Farmer-type chambers, a simple Monte Carlo model was in good agreement with the measured response.

  11. A new mini gas ionization chamber for IBA applications

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, A.M., E-mail: arnold.mueller@phys.ethz.ch [Laboratory of Ion Beam Physics, ETH Zurich, 8093 Zurich (Switzerland); Cassimi, A., E-mail: cassimi@ganil.fr [CIMAP/CIRIL, CEA/CNRS/ENSICAEN, BP5133, F-14070 Caen cedex 5 (France); Doebeli, M., E-mail: doebeli@phys.ethz.ch [Laboratory of Ion Beam Physics, ETH Zurich, 8093 Zurich (Switzerland); Mallepell, M., E-mail: mallepell@phys.ethz.ch [Laboratory of Ion Beam Physics, ETH Zurich, 8093 Zurich (Switzerland); Monnet, I., E-mail: monnet@ganil.fr [CIMAP/CIRIL, CEA/CNRS/ENSICAEN, BP5133, F-14070 Caen cedex 5 (France); Simon, M.J. [Laboratory of Ion Beam Physics, ETH Zurich, 8093 Zurich (Switzerland); Suter, M., E-mail: martin.suter@phys.ethz.ch [Laboratory of Ion Beam Physics, ETH Zurich, 8093 Zurich (Switzerland); Synal, H.-A., E-mail: synal@phys.ethz.ch [Laboratory of Ion Beam Physics, ETH Zurich, 8093 Zurich (Switzerland)

    2011-12-15

    Novel prototypes of high resolution gas ionization chambers (GIC) were designed with increased compactness and simplicity of the setup. They have no Frisch-grid and a simple anode wire. Under certain operating conditions these mini detectors have an energy resolution comparable with that of state-of-the-art GICs of much higher complexity. They can be operated both under vacuum and atmospheric pressure. First measurements were made with protons in the energy range of 0.3-1.0 MeV. For protons at 0.3 MeV an energy resolution of about 12 keV was achieved. With a 72 MeV {sup 129}Xe beam a relative resolution of 1.4% was obtained. Due to their versatility and reduced size the detectors can easily be applied in the field of ion beam analysis (IBA) and accelerator mass spectrometry (AMS). Since they are almost completely insensitive to radiation damage they are especially suited for use in high fluence applications such as scanning transmission ion microscopy (STIM). A comparison of the radiation hardness of the mini GIC with a Si PIN diode was therefore performed. The GIC showed no peak shift or change in energy resolution at all after collecting 10{sup 15} protons per cm{sup 2} while the performance of the Si detector clearly started to degrade at 10{sup 12} particles per cm{sup 2}.

  12. A correction to Birks' Law in liquid argon ionization chamber simulations for highly ionizing particles

    Energy Technology Data Exchange (ETDEWEB)

    Burdin, Sergey [Department of Physics, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Horbatsch, Marko [Department of Physics and Astronomy, York University, Toronto, ON, M3J 1P3 (Canada); Taylor, Wendy, E-mail: taylorw@yorku.ca [Department of Physics and Astronomy, York University, Toronto, ON, M3J 1P3 (Canada)

    2012-02-01

    We present a study of the performance of Birks' Law in liquid argon ionization chamber simulations as applied to highly ionizing particles, such as particles with multiple electric charges or with magnetic charge. We used Birks' Law to model recombination effects in a GEANT4 simulation of heavy ions in a liquid argon calorimeter. We then compared the simulation to published heavy-ion data to extract a highly ionizing particle correction to Birks' Law.

  13. A double faced ionization chamber for quality control in diagnostic radiology beams

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Jonas O., E-mail: josofisico@yahoo.com.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Av. Prof. Lineu Prestes, 2242, 05508-000, Sao Paulo (Brazil); Caldas, Linda V.E. [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Av. Prof. Lineu Prestes, 2242, 05508-000, Sao Paulo (Brazil)

    2012-07-15

    The development of new radiation detectors of low cost but with adequate materials is a very important task for countries that have to import ionization chambers such as Brazil. A special double faced ionization chamber was developed for use in conventional diagnostic radiology beams and computed tomography energy ranges. The results show that this new chamber present applicability in conventional diagnostic radiology and computed tomography quality control programs. - Highlights: Black-Right-Pointing-Pointer We constructed a double faced ionization chamber. Black-Right-Pointing-Pointer It was submitted to conventional diagnostic and computed tomography X-rays beams. Black-Right-Pointing-Pointer The results obtained showed good agreement with international standards. Black-Right-Pointing-Pointer This ionization chamber can be used in clinic quality control program.

  14. Low-level measurements of Ra-226/Rn-222 by pulse ionization chambers

    Science.gov (United States)

    El-Daoushy, Fand; Garcia-Tenorio, Rafael

    1988-10-01

    Characteristics of two ionization chambers have been studied and the chambers utilized for 226Ra/ 222Rn measurements for more than ten years. The results obtained show that coating of internal surfaces with a pure and thin Ag-layer enhances the background of ionization chambers in spite of some improvements at the early stages of operation. In addition to previously known parameters influencing the accuracy in routine measurements, new correction factors are suggested. 226Ra impurities in the body of ionization chambers are found to act not only as a permanent, but also as a temperature-dependent source of background. Earlier accuracies of 226Ra/ 222Rn measurements have been considerably improved by assuring long-term mechanical and thermal stability of the ionization chambers.

  15. Experimental determination of wall correction factors. Pt. 2; NACP and Markus plane-parallel ionization chambers

    Energy Technology Data Exchange (ETDEWEB)

    Wittkaemper, F.W.; Mijnheer, B.J. (Nederlands Kanker Inst. ' Antoni van Leeuwenhoekhuis' , Amsterdam (Netherlands)); Aalbers, A.H.L. (Netherlands Measurements Inst., Bilthoven (Netherlands))

    1992-04-01

    The formalism to derive the absorbed dose to water from ionization chamber measurements in a phantom includes several wall correction factors depending on shape, size and composition of the chamber. Wall correction factors have been measured for a number of NACP and PTW/Markers Chambers. Significant deviations from calculated values occur due to uncertainties in the contribution to the total ionization from the different materials of these inhomogeneous ionization chambers. The discrepancies illustrate the need for the development of a homogeneous plane-parallel chamber. In addition, detailed Monte Carlo calculations, taking the different wall materials into account, are required to quantitatively predict the response of heterogeneous plane-parallel chambers in photon beams. (UK).

  16. Calibration of ionization chamber for ¹⁸F and ⁶⁸Ga.

    Science.gov (United States)

    da Silva, Carlos J; de Oliveira, Estela M; Iwahara, A; Delgado, José U; Poledna, R; de Oliveira, Antônio E; Moreira, Denise S; da Silva, Ronaldo L; Gomes, Regio dos Santos; de Veras, Eduardo V

    2014-05-01

    In order to maintain the results of primary activity standardizations carried out in 2011 the LNMRI has determined the calibration factors for a pressurized 4π-ionization chamber for the nuclides (18)F and (68)Ga. This ionization chamber is coupled to a 6517A Keithley electrometer which is controlled by a homemade LabVIEW program. This paper will describe the main issues related to the calibration of an ionization chamber system for positron emitters and short half-life radionuclides such as timing, current measurement, background, decay, and (226)Ra check source measurements.

  17. a High Resolution Ionization Chamber for the SPIDER Fission Fragment Detector

    Science.gov (United States)

    Meierbachtol, K.; Tovesson, F.; Arnold, C. W.; Laptev, A. B.; Bredeweg, T. A.; Jandel, M.; Nelson, R. O.; White, M. C.; Hecht, A. A.; Mader, D.

    2014-09-01

    An ionization chamber for measuring the energy loss and kinetic energy of fragments produced through neutron-induced fission at the Los Alamos Neutron Science Center (LANSCE) has been designed as a component of the the new SPIDER detector. Design criteria included energy resolutions of <1% for high energy resolution and increased charge resolution. The ionization chamber will be combined with a high resolution time-of-flight detector to achieve fragment yield measurements with mass and nuclear charge resolutions of 1 amu and Z=1. The present status of the ionization chamber will be presented.

  18. Traceability of the ionization chambers calibrated at Kyushu regional center (I) for standard doses in medicine

    Energy Technology Data Exchange (ETDEWEB)

    Araki, Fujio; Noda, Hiroji; Higashida, Yoshiharu; Matsumoto, Masanori [Kumamoto Univ. (Japan). Coll. of Medical Science

    1997-12-01

    We investigated the traceability of the ionization chambers calibrated by the standard dosimeter with Kyushu regional center (I) for standard doses in medicine. Accuracy management of the ionization chambers of Kyushu regional center (I) has been maintained within 0.5% by intercomparison with that of the National Institute of Radiological Sciences (NIRS). The number of hospitals and the number of intercomparisons were 17 and 33 on an average per year, respectively. Accuracy of the ionization chambers of each hospital in recent years was less than 0.5% to the hospitals of 65-80% and less than 1.0% to those of 80-90%. (author)

  19. Dosimetric Performance of Newly Developed Farmer-Type Ionization Chamber in Radiotherapy Practice.

    Science.gov (United States)

    Saminathan, Sathiyan; Godson, Henry Finlay; Ponmalar, Retna; Manickam, Ravikumar; Mazarello, James; Fernandes, Rahul

    2016-12-01

    Dose measurement with ionization chamber is essential to deliver accurate dose to the tumor in radiotherapy. The cylindrical Farmer-type ionization chamber is recommended by various dosimetry protocols for dose measurement of radiotherapy beams. The air-equivalent graphite wall Farmer-type ionization chamber (FAR 65 GB) of active volume 0.65 cm(3) with aluminum as the central electrode material was fabricated. Various dosimetric parameters were studied for the newly developed ionization chamber in cobalt-60, 6 and 18 MV photon beams. The preirradiation and postirradiation leakage of the chamber was within 0.08%. The long-term stability and the stem effect of the chamber were within 0.07% and 0.3%, respectively. The sensitivity of the ionization chamber was found to be 22.15 nC/Gy. The chamber shows linear response with dose for cobalt-60, 6 and 18 MV photon beams. The ion recombination correction factor increases with increase in bias voltage. For all energies and field sizes, the polarity correction factor is almost closer to unity. The ion recombination and polarity correction measurements show that the polarizing potential and polarity recommended during the calibration of ionization chamber should be used for routine measurement to avoid the uncertainty. The chamber response is independent of dose rate and energy. The chamber is cost-effective and shows precise and reproducible response. The study carried out confirms that the newly fabricated ion chamber can be used in the measurement of absolute dose for high-energy photon beams.

  20. LARGE VOLUME IONIZATION CHAMBER USED AS LABORATORY REFERENCE FOR LOW ENERGY X—RAY MEASUREMENT

    Institute of Scientific and Technical Information of China (English)

    杨国山; 薛永库; 等

    1994-01-01

    A large volume spherical ionization chamber of 195mm diameter and 0.36mg/cm2 wall thickness made from conducting carbon-fibre epoxy composite material has been developed.The mechanical intensity of the chamber is satisfactory for a good longterm volume stability.Owing to its large volume and thin wall,the chamber is sensitive to low energy photon beams and has excellent energy-response characteristics.This ionization chamber is suitable not only for a laboratory reference but also for measurement of low energy photon beam exposure rates at protection-level.

  1. Resistive Plate Chamber Digitization in a Hadronic Shower Environment

    CERN Document Server

    Deng, Z; Wang, Y; Yue, Q; Yang, Z; Apostolakis, J; Folger, G; Grefe, C; Ivantchenko, V; Ribon, A; Uzhinskiy, V; Boumediene, D; Carloganu, C; Français, V; Cho, G; Kim, D-W; Lee, S C; Park, W; Vallecorsa, S; Cauwenbergh, S; Tytgat, M; Pingault, A; Zaganidis, N; Brianne, E; Ebrahimi, A; Gadow, K; Göttlicher, P; Günter, C; Hartbrich, O; Hermberg, B; Irles, A; Krivan, F; Krüger, K; Kvasnicka, J; Lu, S; Lutz, B; Morgunov, V; Neubüser, C; Provenza, A; Reinecke, M; Sefkow, F; Schuwalow, S; Tran, H L; Garutti, E; Laurien, S; Matysek, M; Ramilli, M; Schroeder, S; Bilki, B; Norbeck, E; Northacker, D; Onel, Y; Chang, S; Khan, A; Kim, D H; Kong, D.J; Oh, Y D; Kawagoe, K; Hirai, H; Sudo, Y; Suehara, T; Sumida, H; Yoshioka, T; Gil, E Cortina; Mannai, S; Buridon, V; Combaret, C; Caponetto, L; Eté, R; Garillot, G; Grenier, G; Han, R; Ianigro, J C; Kieffer, R; Laktineh, I; Lumb, N; Mathez, H; Mirabito, L; Petrukhin, A; Steen, A; Antequera, J Berenguer; Alamillo, E Calvo; Fouz, M-C; Marin, J; Puerta-Pelayo, J; Verdugo, A; Chadeeva, M; Danilov, M; Gabriel, M; Goecke, P; Kiesling, C; vanderKolk, N; Simon, F; Szalay, M; Bilokin, S; Bonis, J; Cornebise, P; Richard, F; Pöschl, R; Rouëné, J; Thiebault, A; Zerwas, D; Anduze, M; Balagura, V; Belkadhi, K; Boudry, V; Brient, J-C; Cornat, R; Frotin, M; Gastaldi, F; Haddad, Y; Magniette, F; Ruan, M; Rubio-Roy, M; Shpak, K; Videau, H; Yu, D; Callier, S; di Lorenzo, S Conforti; Dulucq, F; Martin-Chassard, G; de la Taille, Ch; Raux, L; Seguin-Moreau, N; Kotera, K; Ono, H; Takeshita, T; Corriveau, F

    2016-01-01

    The CALICE Semi-Digital Hadron Calorimeter (SDHCAL) technological prototype is a sampling calorimeter using Glass Resistive Plate Chamber detectors with a three-threshold readout as the active medium. This technology is one of the two options proposed for the hadron calorimeter of the International Large Detector for the International Linear Collider. The prototype was exposed to beams of muons, electrons and pions of different energies at the CERN Super Proton Synchrotron. To be able to study the performance of such a calorimeter in future experiments it is important to ensure reliable simulation of its response. In this paper we present our prototype simulation performed with GEANT4 and the digitization procedure achieved with an algorithm called SimDigital. A detailed description of this algorithm is given and the methods to determinate its parameters using muon tracks and electromagnetic showers are explained. The comparison with hadronic shower data shows a good agreement up to 50 GeV. Discrepancies are ...

  2. Gas mixture studies for streamer operated Resistive Plate Chambers

    Science.gov (United States)

    Paoloni, A.; Longhin, A.; Mengucci, A.; Pupilli, F.; Ventura, M.

    2016-06-01

    Resistive Plate Chambers operated in streamer mode are interesting detectors in neutrino and astro-particle physics applications (like OPERA and ARGO experiments). Such experiments are typically characterized by large area apparatuses with no stringent requirements on detector aging and rate capabilities. In this paper, results of cosmic ray tests performed on a RPC prototype using different gas mixtures are presented, the principal aim being the optimization of the TetraFluoroPropene concentration in Argon-based mixtures. The introduction of TetraFluoroPropene, besides its low Global Warming Power, is helpful because it simplifies safety requirements allowing to remove also isobutane from the mixture. Results obtained with mixtures containing SF6, CF4, CO2, N2 and He are also shown, presented both in terms of detectors properties (efficiency, multiple-streamer probability and time resolution) and in terms of streamer characteristics.

  3. Very high position resolution gamma imaging with resistive plate chambers

    Energy Technology Data Exchange (ETDEWEB)

    Blanco, A. [LIP, Laboratorio de Instrumentacao e Fisica Experimental de Particulas, Coimbra 3004-516 (Portugal)]. E-mail: alberto@coimbra.lip.pt; Carolino, N. [LIP, Laboratorio de Instrumentacao e Fisica Experimental de Particulas, Coimbra 3004-516 (Portugal); Correia, C.M.B.A. [CEI, Centro de Electronica e Instrumentacao, Universidade de Coimbra, Coimbra 3004-516 (Portugal); Fazendeiro, L. [LIP, Laboratorio de Instrumentacao e Fisica Experimental de Particulas, Coimbra 3004-516 (Portugal); Ferreira, Nuno C. [IBILI, Instituto Biomedico de Investigacao de Luz e Imagem, Faculty of Medicine, Coimbra 3000 (Portugal); Marques, M.F. Ferreira [ICEMS, Departamento de Fisica, Universidade de Coimbra, Coimbra 3004-516 (Portugal); ISEC, Instituto Superior de Engenharia de Coimbra, Coimbra 3031-199 (Portugal); Marques, R. Ferreira [LIP, Laboratorio de Instrumentacao e Fisica Experimental de Particulas, Coimbra 3004-516 (Portugal); Departamento de Fisica, Universidade de Coimbra, Coimbra 3004-516 (Portugal); Fonte, P. [LIP, Laboratorio de Instrumentacao e Fisica Experimental de Particulas, Coimbra 3004-516 (Portugal); ISEC, Instituto Superior de Engenharia de Coimbra, Coimbra 3031-199 (Portugal); Gil, C. [ICEMS, Departamento de Fisica, Universidade de Coimbra, Coimbra 3004-516 (Portugal); Macedo, M.P. [CEI, Centro de Electronica e Instrumentacao, Universidade de Coimbra, Coimbra 3004-516 (Portugal); ISEC, Instituto Superior de Engenharia de Coimbra, Coimbra 3031-199 (Portugal)

    2006-11-01

    In this study we present experimental results from a first prototype of a positron emission tomography system based on the resistive plate chamber (RPC) technology. The system is composed of two counting heads, each one containing 16 single-gap RPC detectors capable of detecting the photon interaction point in the transaxial plane. Uniformity studies were performed for image resolution and sensitivity, yielding a rather uniform image resolution close to 0.3 mm FWHM across the field of view. The contribution of the photons noncolinearity effect to the intrinsic spatial resolution was also studied, causing a variation from 0.52 to 0.63 mm when the system diameter ranges from 60 to 120 mm, in agreement with calculations.

  4. Development of Glass Resistive Plate Chambers for INO

    CERN Document Server

    Bheesette, Satyanarayana

    2008-01-01

    The India-based Neutrino Observatory (INO) collaboration is planning to build a massive 50kton magnetised Iron Calorimeter (ICAL) detector, to study atmospheric neutrinos and to make precision measurements of the parameters related to neutrino oscillations. Glass Resistive Plate Chambers (RPCs) of about 2m X 2m in size are going to be used as active elements for the ICAL detector. We have fabricated a large number of glass RPC prototypes of 1m X 1m in size and have studied their performance and long term stability. In the process, we have developed and produced a number of materials and components required for fabrication of RPCs. We have also designed and optimised a number of fabrication and quality control procedures for assembling the gas gaps. In this paper we will review our activities towards development of glass RPCs for the INO ICAL detector and will present results of the characterisation studies of the RPCs.

  5. Experience with the BaBar Resistive Plate Chambers

    Energy Technology Data Exchange (ETDEWEB)

    Band, H.

    2005-04-06

    The BaBar detector has operated over 2000 m{sup 2} of Resistive Plates Chambers (RPCs) as muon and neutral hadron detectors since 1999. Most of the original RPC production have lost significant efficiency and many are now completely inefficient. Both the linseed oil used to coat the inner surfaces and the graphite coating on the outer surfaces are implicated as contributors to the efficiency loss which was accelerated by the operation of the RPCs at 29 to 34 C during the first summer. RPCs from 2 more recent production runs have been installed and tested. The most recent RPCs have exhibited stable efficiencies and high voltage plateaus during the first 8 months of service. Some have shown increased dark currents and noise rates.

  6. Optical observation of discharge in resistive plate chamber

    CERN Document Server

    Kitayama, I; Teramoto, Y; Chinomi, S; Inoue, Y; Nakano, E; Takahashi, T

    1999-01-01

    Pictures of the discharge in a resistive plate chamber (RPC) were taken using a glass RPC, an image intensifier and a CCD camera. Measurements were separately made for cosmic rays (trigger mode) and self-discharge (non-tigger mode), in vertical and horizontal views, operated in the streamer mode with various gas mixtures. Streamers are observed as narrow strings with diameters <500 mu m, extending between the anode and the cathode surfaces. Each streamer accompanies disk-shaped discharges of 2-4 mm diameter, on both the cathode and the anode surfaces. With a gas mixture that gives a high detection efficiency, discharge patterns are similar for both the cosmic rays and self-discharges.

  7. Development of linseed oil-free bakelite resistive plate chambers

    Science.gov (United States)

    Biswas, S.; Bhattacharya, S.; Bose, S.; Chattopadhyay, S.; Saha, S.; Viyogi, Y. P.

    2009-06-01

    In this paper we would like to present a few characteristics of the Resistive Plate Chambers (RPCs) made of a particular grade of bakelite paper laminates (P-120, NEMA LI-1989 Grade XXX), produced and commercially available in India. This particular grade is used for high voltage insulation in humid conditions. The chambers are tested with cosmic rays in the streamer mode using argon, tetrafluroethane and isobutane in 34:59:7 mixing ratio. In the first set of detectors made with such grade, a thin coating of silicone fluid on the inner surfaces of the bakelite was found to be necessary for operation of the detector. Those silicone coated RPCs were found to give satisfactory performance with stable efficiency of >90% continuously for a long period as reported earlier. Results of the crosstalk measurement of these silicone coated RPC will be presented in this paper. Very recently RPCs made with the same grade of bakelite but having better surface finish are found to give equivalent performance even without any coating inside. Preliminary results of this type of RPCs are also being presented.

  8. Ceramic resistive plate chambers for high rate environments

    Energy Technology Data Exchange (ETDEWEB)

    Laso Garcia, Alejandro; Kaempfer, Burkhard; Kaspar, Markus; Kotte, Roland; Peschke, Richard; Stach, Daniel; Wendisch, Christian; Wuestenfeld, Joern [Helmholtz Zentrum, Dresden-Rossendorf (Germany); Collaboration: CBM-Collaboration

    2012-07-01

    Multi-gap resistive plate chambers will be used to build the time of flight wall of the compressed baryonic matter experiment (CBM) at FAIR with a time resolution better than 80 ps. The high fluxes expected at the innermost part of the detector, 20 x 10{sup 3} cm{sup -2}s{sup -1} have made necessary the development of new materials capable of withstanding such fluxes. At Helmholtz Zentrum Dresden-Rossendorf, several RPC prototypes of 10 x 10 cm{sup 2} and 20 x 20 cm{sup 2} have been built with ceramic plates with bulk resistivities in the range of 10{sup 9}-10{sup 10} Ohm cm. They have been tested at the superconducting electron accelerator facility ELBE with 30 MeV electrons and at COSY, Juelich, with 2.7 Gev/c protons. We present characteristics of the ceramic electrodes and the latest results concerning the performance of these prototypes in electron and proton beams up to fluxes of 10{sup 6} cm{sup -2}s{sup -1}.

  9. Rate Capability in Bakelite Based Resistive Plate Chambers

    Science.gov (United States)

    Candocia, Max

    2011-10-01

    Bakelite-based resistive plate chambers (RPCs) are particle detectors commonly used in muon trigger systems for high-energy physics experiments. Bakelite RPCs combine fast response, sufficient position resolution and low cost, and they can be operated at instantaneous background rates up to about 1.5 kHz/cm2. Current and future collider experiments will demand operation of trigger RPCs under background rates higher than what is currently achieved. The rate capability is related to the bulk and surface conductivities of the Bakelite material used for the plates bordering the active gas volume in the RPCs. The inner surface of present Bakelite RPCs used at the LHC and RHIC is coated with linseed oil, lowering the surface resistivity of the raw Bakelite. Methods of increasing the surface conductivity of Bakelite sheets via dispersion of carbon blacks in linseed oil are being developed. Performance tests of prototype RPCs are carried out in a test stand that utilizes cosmic ray muons and radioactive 55Fe sources. In this presentation different dispersion methods and the rate capability of the resulting prototype RPCs will be compared.

  10. Initial recombination in the track of heavy charged particles: Numerical solution for air filled ionization chambers

    DEFF Research Database (Denmark)

    Kaiser, Franz-Joachim; Bassler, Niels; Tölli, Heikki

    2012-01-01

    Introduction Modern particle therapy facilities enable sub-millimeter precision in dose deposition. Here, also ionization chambers (ICs) are used, which requires knowledge of the recombination effects. Up to now, recombination is corrected using phenomenological approaches for practical reasons...

  11. Study of the energy response of high pressure ionization chamber for high energy gamma-ray

    Institute of Scientific and Technical Information of China (English)

    HUA Zheng-Dong; XU Xun-Jiang; WANG Jian-Hua; LIU Shu-Dong; LI Jian-Ping

    2008-01-01

    The energy response calibration of the commonly used high pressure ionization chamber is very difficult to obtain when the gamma-ray energy is more than 3 MeV.In order to get the calibration of the higher part of the high pressure ionization chamber,we use the Fluka Monte Carlo program to perfclrm the energy response in both the spherical and the cylindrical high pressure ionization chamber which are full of argon gas.The results compared with prior study when the gamma-ray energy is less than 1.25 MeV.Our result of Monte Carlo calculation shows agreement with those obtained by measurement within the uncertainty of the respective methods.The calculation of this study is significant for the high pressure ionization chamber to measure the high energy gamma-ray.

  12. Stability results of a free air ionization chamber in standard mammography beams

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Natalia F.; Xavier, Marcos; Vivolo, Vitor; Caldas, Linda V.E., E-mail: nsilva@ipen.br, E-mail: mxavier@ipen.br, E-mail: vivolo@ipen.br, E-mail: lcaldas@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    Free air ionization chambers are absolute dosimeters, because they can measure basic physical quantities directly without the need of their calibration in a standard radiation beam. They are used for measuring exposure and air kerma in X and gamma radiation beams. The Calibration Laboratory (LCI) of IPEN has a free air ionization chamber of the cylindrical type for low energies. The characterization of this ionization chamber was already performed and reported in a previous study. After a modification in the support of the micrometers used for the movement of the internal cylinder devices, the tests were redone. The objective of this work was to present the new alignment protocol of the free air ionization chamber in low energies of X-ray beams of standard mammography qualities, assuring the positioning reproducibility, and new results of stability tests performed with the application of this protocol will be presented. (author)

  13. Investigating the contamination of accelerated radioactive beams with an ionization chamber at MINIBALL

    CERN Document Server

    Zidarova, Radostina

    2017-01-01

    My summer student project involved the operation and calibration of an ionization chamber, which was used at MINIBALL for investigating and determining the contamination in post-accelerated radioactive beams used for Coulomb excitation and transfer reaction experiments.

  14. On line high dose static position monitoring by ionization chamber detector for industrial gamma irradiators.

    Science.gov (United States)

    Rodrigues, Ary A; Vieira, Jose M; Hamada, Margarida M

    2010-01-01

    A 1 cm(3) cylindrical ionization chamber was developed to measure high doses on line during the sample irradiation in static position, in a (60)Co industrial plant. The developed ionization chamber showed to be suitable for use as a dosimeter on line. A good linearity of the detector was found between the dose and the accumulated charge, independently of the different dose rates caused by absorbing materials.

  15. On line high dose static position monitoring by ionization chamber detector for industrial gamma irradiators

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Ary A. [Universidade Estadual de Londrina-Depto de Fisica, Rodovia Celso Garcia Cid, km 38, 086051-990 Londrina (Brazil); Vieira, Jose M. [Instituto de Pesquisas Energeticas e Nucleares-IPEN/CNEN-SP, Prof. Lineu Prestes, 2242-Cidade Universitaria, 05508-900 Sao Paulo (Brazil); Hamada, Margarida M. [Instituto de Pesquisas Energeticas e Nucleares-IPEN/CNEN-SP, Prof. Lineu Prestes, 2242-Cidade Universitaria, 05508-900 Sao Paulo (Brazil)], E-mail: mmhamada@ipen.br

    2010-04-15

    A 1 cm{sup 3} cylindrical ionization chamber was developed to measure high doses on line during the sample irradiation in static position, in a {sup 60}Co industrial plant. The developed ionization chamber showed to be suitable for use as a dosimeter on line. A good linearity of the detector was found between the dose and the accumulated charge, independently of the different dose rates caused by absorbing materials.

  16. The magic cube and the pixel ionization chamber: detectors for monitor and dosimetry of radiotherapy beams

    Science.gov (United States)

    Amerio, S.; Boriano, A.; Bourhaleb, F.; Cirio, R.; Donetti, M.; Garelli, E.; Giordanengo, S.; Madon, E.; Marchetto, F.; Nastasi, U.; Peroni, C.; Sanz Freire, C. J.; Sardo, A.; Trevisiol, E.

    2003-09-01

    Tumor therapy takes advantage of the energy deposition of radiation to concentrate high doses in the target while sparing healthy tissue. Elective pathologies for highly conformal radiotherapies such as photon Intensity Modulated Radiotherapy (IMRT) and radiotherapy with hadrons are head and neck, eye, prostate and in general all tumors that are either deep or located close to critical organs. In the world there are several centers that are using such techniques and a common problem that is being experienced is the verification of treatment plans and monitoring of the beam. We have designed and built two detectors that allow 2D and 3D measurements of dose and fluence of such beams. The detectors allow measurements on big surfaces, up to 25∗25 cm2. The active media are parallel plate, strip and pixel segmented ionization chambers with front-end Very Large Scale Integration (VLSI) readout and PC based data acquistion. The description of dosimeter, chamber and electronics will be given with results from beam tests and therapy plan verification.

  17. The magic cube and the pixel ionization chamber: detectors for monitor and dosimetry of radiotherapy beams

    Energy Technology Data Exchange (ETDEWEB)

    Amerio, S.; Boriano, A.; Bourhaleb, F.; Cirio, R.; Donetti, M.; Garelli, E.; Giordanengo, S.; Madon, E.; Marchetto, F.; Nastasi, U.; Peroni, C.; Sanz Freire, C.J.; Sardo, A.; Trevisiol, E

    2003-09-01

    Tumor therapy takes advantage of the energy deposition of radiation to concentrate high doses in the target while sparing healthy tissue. Elective pathologies for highly conformal radiotherapies such as photon Intensity Modulated Radiotherapy (IMRT) and radiotherapy with hadrons are head and neck, eye, prostate and in general all tumors that are either deep or located close to critical organs. In the world there are several centers that are using such techniques and a common problem that is being experienced is the verification of treatment plans and monitoring of the beam. We have designed and built two detectors that allow 2D and 3D measurements of dose and fluence of such beams. The detectors allow measurements on big surfaces, up to 25*25 cm{sup 2}. The active media are parallel plate, strip and pixel segmented ionization chambers with front-end Very Large Scale Integration (VLSI) readout and PC based data acquistion. The description of dosimeter, chamber and electronics will be given with results from beam tests and therapy plan verification.

  18. Pencil beam proton radiography using a multilayer ionization chamber

    Science.gov (United States)

    Farace, Paolo; Righetto, Roberto; Meijers, Arturs

    2016-06-01

    A pencil beam proton radiography (PR) method, using a commercial multilayer ionization chamber (MLIC) integrated with a treatment planning system (TPS) was developed. A Giraffe (IBA Dosimetry) MLIC (±0.5 mm accuracy) was used to obtain pencil beam PR by delivering spots uniformly positioned at a 5.0 mm distance in a 9  ×  9 square of spots. PRs of an electron-density (with tissue-equivalent inserts) phantom and a head phantom were acquired. The integral depth dose (IDD) curves of the delivered spots were computed by the TPS in a volume of water simulating the MLIC, and virtually added to the CT at the exit side of the phantoms. For each spot, measured and calculated IDD were overlapped in order to compute a map of range errors. On the head-phantom, the maximum dose from PR acquisition was estimated. Additionally, on the head phantom the impact on the range errors map was estimated in case of a 1 mm position misalignment. In the electron-density phantom, range errors were within 1 mm in the soft-tissue rods, but greater in the dense-rod. In the head-phantom the range errors were  -0.9  ±  2.7 mm on the whole map and within 1 mm in the brain area. On both phantoms greater errors were observed at inhomogeneity interfaces, due to sensitivity to small misalignment, and inaccurate TPS dose computation. The effect of the 1 mm misalignment was clearly visible on the range error map and produced an increased spread of range errors (-1.0  ±  3.8 mm on the whole map). The dose to the patient for such PR acquisitions would be acceptable as the maximum dose to the head phantom was  <2cGyE. By the described 2D method, allowing to discriminate misalignments, range verification can be performed in selected areas to implement an in vivo quality assurance program.

  19. A 200 cm x 50 cm large multigap resistive plate chamber based neutron detector

    Energy Technology Data Exchange (ETDEWEB)

    Yakorev, Dmitry; Elekes, Zoltan; Bemmerer, Daniel; Kempe, Mathias; Sobiella, Manfred; Stach, Daniel; Wagner, Andreas [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden (Germany); Roeder, Marko; Zuber, Kai [TU Dresden (Germany); Cowan, Thomas [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden (Germany); TU Dresden (Germany)

    2012-07-01

    A prototype for a multigap resistive plate chamber (MRPC) based detector of 200 cm x 50 cm size for 1 GeV neutrons has been developed, built and tested. The principle of operation is the conversion of the high-energy neutron to a charged particle in an iron converter, and the detection of the charged particle in the MRPC. Experiments using the single-electron mode of operation of the ELBE 40 MeV electron accelerator showed that a time resolution of {sigma}{sub t}<100 ps was reached for minimum-ionizing particles, at nearly full efficiency. Extensive simulations show that it is feasible to construct a time-of-flight detector for GeV neutrons based on such a principle.

  20. Beam Tests of Ionization Chambers for the NuMI Neutrino Beam

    CERN Document Server

    Zwaska, R M; Kopp, S E; Proga, M; Erwin, A R; Ping, H; Velissaris, C; Harris, D A; Naples, D; McDonald, J; Northacker, D; Diwan, M V; Viren, B M; Hall, James; Kopp, Sacha E.; Proga, Marek; Erwin, Albert R.; Ping, Huican; Velissaris, Christos; Harris, Deborah A.; Naples, Donna; Donald, Jeffrey Mc; Northacker, David; Diwan, Milind; Viren, Brett

    2003-01-01

    We have conducted tests at the Fermilab Booster of ionization chambers to be used as monitors of the NuMI neutrino beamline. The chambers were exposed to proton fluxes of up to 10$^{12}$ particles/cm$^2$/1.56$\\mu$s. We studied space charge effects which can reduce signal collection from the chambers at large charged particle beam intensities.

  1. Pre-evaluation of an ionization chamber for clinical radiotherapy dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Neves, Lucio P.; Perini, Ana P.; Xavier, Marcos; Caldas, Linda V.E., E-mail: mxavier@ipen.b, E-mail: lcaldas@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Khoury, Helen J., E-mail: khoury@ufpe.b [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear

    2011-07-01

    This work presents some pre-operational tests for characterization of a new homemade ionization chamber developed at the Calibration Laboratory of Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP). This chamber was designed for use in radiotherapy dosimetry. To study the utilization of this chamber in radiotherapy, some tests were undertaken: short- and medium-term stabilities, saturation curve, recombination loss, polarity effect and leakage current. All results obtained in these tests were within the international recommendations. (author)

  2. D-IMRT verification with a 2D pixel ionization chamber: dosimetric and clinical results in head and neck cancer

    Science.gov (United States)

    Stasi, M.; Giordanengo, S.; Cirio, R.; Boriano, A.; Bourhaleb, F.; Cornelius, I.; Donetti, M.; Garelli, E.; Gomola, I.; Marchetto, F.; Porzio, M.; Sanz Freire, C. J.; Sardo, A.; Peroni, C.

    2005-10-01

    Dynamic intensity-modulated radiotherapy (D-IMRT) using the sliding-window technique is currently applied for selected treatments of head and neck cancer at Institute for Cancer Research and Treatment of Candiolo (Turin, Italy). In the present work, a PiXel-segmented ionization Chamber (PXC) has been used for the verification of 19 fields used for four different head and neck cancers. The device consists of a 32 × 32 matrix of 1024 parallel-plate ionization chambers arranged in a square of 24 × 24 cm2 area. Each chamber has 0.4 cm diameter and 0.55 cm height; a distance of 0.75 cm separates the centre of adjacent chambers. The sensitive volume of each single ionization chamber is 0.07 cm3. Each of the 1024 independent ionization chambers is read out with a custom microelectronics chip. The output factors in water obtained with the PXC at a depth of 10 cm were compared to other detectors and the maximum difference was 1.9% for field sizes down to 3 × 3 cm2. Beam profiles for different field dimensions were measured with the PXC and two other types of ionization chambers; the maximum distance to agreement (DTA) in the 20-80% penumbra region of a 3 × 3 cm2 field was 0.09 cm. The leaf speed of the multileaf collimator was varied between 0.07 and 2 cm s-1 and the detector response was constant to better than 0.6%. The behaviour of the PXC was measured while varying the dose rate between 0.21 and 1.21 Gy min-1; the mean difference was 0.50% and the maximum difference was 0.96%. Using fields obtained with an enhanced dynamic wedge and a staircase-like (step) IMRT field, the PXC has been tested for simple 1D modulated beams; comparison with film gave a maximum DTA of 0.12 cm. The PXC was then used to check four different IMRT plans for head and neck cancer treatment: cervical chordoma, parotid, ethmoid and skull base. In the comparison of the PXC versus film and PXC versus treatment planning system, the number of pixels with γ parameter <=1 was 97.7% and 97

  3. D-IMRT verification with a 2D pixel ionization chamber: dosimetric and clinical results in head and neck cancer

    Energy Technology Data Exchange (ETDEWEB)

    Stasi, M [Institute for Cancer Research and Treatment (IRCC), Candiolo and A.S.O. Ordine Maurizano, Torino (Italy); Giordanengo, S [Istituto Nazionale di Fisica Nucleare (INFN), Via P. Giuria 1, I-10125 Torino (Italy); Cirio, R [Istituto Nazionale di Fisica Nucleare (INFN), Via P. Giuria 1, I-10125 Torino (Italy)] [and others

    2005-10-07

    Dynamic intensity-modulated radiotherapy (D-IMRT) using the sliding-window technique is currently applied for selected treatments of head and neck cancer at Institute for Cancer Research and Treatment of Candiolo (Turin, Italy). In the present work, a PiXel-segmented ionization Chamber (PXC) has been used for the verification of 19 fields used for four different head and neck cancers. The device consists of a 32 x 32 matrix of 1024 parallel-plate ionization chambers arranged in a square of 24 x 24 cm{sup 2} area. Each chamber has 0.4 cm diameter and 0.55 cm height; a distance of 0.75 cm separates the centre of adjacent chambers. The sensitive volume of each single ionization chamber is 0.07 cm{sup 3}. Each of the 1024 independent ionization chambers is read out with a custom microelectronics chip. The output factors in water obtained with the PXC at a depth of 10 cm were compared to other detectors and the maximum difference was 1.9% for field sizes down to 3 x 3 cm{sup 2}. Beam profiles for different field dimensions were measured with the PXC and two other types of ionization chambers; the maximum distance to agreement (DTA) in the 20-80% penumbra region of a 3 x 3 cm{sup 2} field was 0.09 cm. The leaf speed of the multileaf collimator was varied between 0.07 and 2 cm s{sup -1} and the detector response was constant to better than 0.6%. The behaviour of the PXC was measured while varying the dose rate between 0.21 and 1.21 Gy min{sup -1}; the mean difference was 0.50% and the maximum difference was 0.96%. Using fields obtained with an enhanced dynamic wedge and a staircase-like (step) IMRT field, the PXC has been tested for simple 1D modulated beams; comparison with film gave a maximum DTA of 0.12 cm. The PXC was then used to check four different IMRT plans for head and neck cancer treatment: cervical chordoma, parotid, ethmoid and skull base. In the comparison of the PXC versus film and PXC versus treatment planning system, the number of pixels with {gamma

  4. X-ray detector for automatic exposure control using ionization chamber filled with xenon gas

    CERN Document Server

    Nakagawa, A; Yoshida, T

    2003-01-01

    This report refers to our newly developed X-ray detector for reliable automatic X-ray exposure control, which is to be widely used for X-ray diagnoses in various clinical fields. This new detector utilizes an ionization chamber filled with xenon gas, in contrast to conventional X-ray detectors which use ionization chambers filled with air. Use of xenon gas ensures higher sensitivity and thinner design of the detector. The xenon gas is completely sealed in the chamber, so that the influence of the changes in ambient environments is minimized. (author)

  5. A boron-coated ionization chamber for ultra-cold neutron detection

    Energy Technology Data Exchange (ETDEWEB)

    Salvat, D.J., E-mail: dsalvat@indiana.edu [Indiana University Center for Exploration of Energy and Matter, Bloomington, IN 47408 (United States); Morris, C.L.; Wang, Z. [Los Alamos National Laboratory, Los Alamos, NM 87544 (United States); Adamek, E.R. [Indiana University Center for Exploration of Energy and Matter, Bloomington, IN 47408 (United States); Bacon, J. [Los Alamos National Laboratory, Los Alamos, NM 87544 (United States); Hickerson, K.P. [California Institute of Technology, Pasadena, CA 91125 (United States); Hoagland, J.; Holley, A.T. [North Carolina State University, Raleigh, NC 27695 (United States); Liu, C.-Y. [Indiana University Center for Exploration of Energy and Matter, Bloomington, IN 47408 (United States); Makela, M.; Ramsey, J. [Los Alamos National Laboratory, Los Alamos, NM 87544 (United States); Reid, A. [North Carolina State University, Raleigh, NC 27695 (United States); Rios, R. [Idaho State University, Pocatello, ID 83209 (United States); Saunders, A.; Sjue, S.K.L. [Los Alamos National Laboratory, Los Alamos, NM 87544 (United States); VornDick, B.; Young, A.R. [North Carolina State University, Raleigh, NC 27695 (United States)

    2012-11-01

    The design and performance of a boron-coated ionization chamber for the detection of ultra-cold neutrons (UCN) are presented. We detect UCN from the solid deuterium-based UCN source at the Los Alamos Neutron Science Center. Our results indicate comparable efficiency to {sup 3}He ionization chambers and proportional counters currently used at the UCN source. In addition, the ion chamber is used to detect thermal neutrons; a comparison of the thermal neutron and UCN pulse-height spectra indicates that UCN mostly capture near the layer surface.

  6. Monitoring the Resistive Plate Chambers in the Muon Spectrometer of ATLAS.

    CERN Document Server

    Al-Qahtani, Shaikha

    2017-01-01

    A software was developed to monitor the resistive plate chambers. The purpose of the program is to detect any weak or dead chambers and locate them for repair. The first use of the program was able to spot several chambers with problems to be investigated.

  7. Elements Discrimination in the Study of Super-Heavy Elements using an Ionization Chamber

    CERN Document Server

    Wieloch, A; Péter, J; Lojek, K; Alamanos, N; Amar, N; Anne, R; Angélique, J C; Auger, G; Dayras, R; Drouart, A; Fontbonne, J M; Gillibert, A; Grévy, S; Hanappe, F; Hannachi, F; Hue, R; Khouaja, A; Legou, T; López-Martens, A; Liénard, E; Manduci, L; De Oliveira-Santos, F; Politi, G; Saint-Laurent, M G; Stodel, C; Stuttgé, L; Tillier, J; De Tourreil, R; Villari, A C C; Wieleczko, J P

    2004-01-01

    Dedicated ionization chamber was built and installed to measure the energy loss of very heavy nuclei at 2.7 MeV/u produced in fusion reactions in inverse kinematics (beam of 208Pb). After going through the ionization chamber, products of reactions on 12C, 18O targets are implanted in a Si detector. Their identification through their alpha decay chain is ambiguous when their half-life is short. After calibration with Pb and Th nuclei, the ionization chamber signal allowed us to resolve these ambiguities. In the search for rare super-heavy nuclei produced in fusion reactions in inverse or symmetric kinematics, such a chamber will provide direct information on the nuclear charge of each implanted nucleus.

  8. A twin-type airflow pulse ionization chamber for continuous alpha-radioactivity monitoring in atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Kada, Wataru, E-mail: kada@nf.eie.eng.osaka-u.ac.j [Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); Dwaikat, Nidal; Datemichi, Jun; Sato, Fuminobu; Murata, Isao; Kato, Yushi; Iida, Toshiyuki [Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan)

    2010-10-15

    A simple and inexpensive twin-type airflow pulse ionization chamber was developed for the continuous monitoring of alpha-radioactivity in atmosphere under high humidity condition. The symmetrical structure of the twin-type ionization chamber was effective in the improvement of the ratio of signal to noise in the measurement of pulses induced by alpha-rays. Outdoor alpha-ray measurement was well performed with this ionization chamber by applying sufficiently high bias voltage to the electrodes, except for at very high humidity conditions. It was confirmed that the declination of the counting efficiency due to wetting was easily recovered by the dry-up of the inside of the chamber. Alpha-radioactivity from radon and other alpha-emitting radionuclide in atmosphere was satisfactorily monitored by the detector.

  9. Ceramic resistive plate chambers for high rate environments

    Energy Technology Data Exchange (ETDEWEB)

    Laso Garcia, Alejandro; Kaspar, Marcus; Kaempfer, Burkhard; Kotte, Roland; Naumann, Lothar; Stach, Daniel; Wendisch, Christian; Wuestenfeld, Joern [Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Sachsen (Germany); Collaboration: CBM-Collaboration

    2013-07-01

    The future Compressed Baryonic Matter Experiment to be built at FAIR is foreseen to use Resistive Plate Chambers as Time of Flight detectors. However, for the most central part of the ToF Wall high particle fluxes are expected, the simulations predict fluxes in the order of 2.10{sup 4} particles/cm{sup 2} s and even higher the closer the wall approaches the beampipe. This high fluxes show the need to develop new materials. At Helmholtz-Zentrum Dresden Rossendorf, new semiconductor ceramic composites have been developed, several prototypes of RPCs with ceramic electrodes up to 20 x 20 cm{sup 2} have been developed and tested. In this talk, the performance of this detectors in electron (ELBE) and proton (COSY) beams is presented, as well as, the performance of this detectors under irradiation in Ni+Pb collisions at 1.9 AGeV (SIS18, GSI). This performance can be quantified as an efficiency close to 100% and a time resolution better than 100 ps.

  10. Temperature study on PHENIX Resistive Plate Chamber 1

    Science.gov (United States)

    Solomon, Mathew

    2012-10-01

    The PHENIX collaboration is investigating the results of polarized proton + proton collisions generated by the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. Studying these collisions will help gain perspective on the overall spin structure of the proton. PHENIX has developed a trigger upgrade for the muon arms to select single high transverse momentum (p/T) muons. A major part of this upgrade is the inclusion of 2 stations of Resistive Plate Chambers (RPC) in each arm of PHENIX. The RPCs are constructed with two gas gaps made of Bakelite and coated with linseed oil, which closely follows the CMS design. These materials are known to be sensitive to high temperatures and within PHENIX a station of RPC's are installed between two large magnets, which could cause the temperature environment to elevate. In order to gain a better understanding of the temperature of the gas gaps, we will compare the externally monitored temperature data from Run-12 to the temperatures acquired from a dedicated temperature profile study. Overall this will help the collaboration operate the RPCs in a manner that will improve their performance and extend their lifetime.

  11. Development of glass resistive plate chambers for INO experiment

    Energy Technology Data Exchange (ETDEWEB)

    Datar, V.M. [Bhabha Atomic Research Centre, Mumbai (India); Jena, Satyajit [Indian Institute of Technology Bombay, Mumbai (India); Kalmani, S.D. [Tata Institute of Fundamental Research, Mumbai (India); Mondal, N.K. [Tata Institute of Fundamental Research, Mumbai (India)], E-mail: nkm@tifr.res.in; Nagaraj, P.; Reddy, L.V.; Saraf, M.; Satyanarayana, B.; Shinde, R.R.; Verma, P. [Tata Institute of Fundamental Research, Mumbai (India)

    2009-05-01

    The India-based Neutrino Observatory (INO) collaboration is planning to build a massive 50 kton magnetised Iron Calorimeter (ICAL) detector, to study atmospheric neutrinos and to make precision measurements of the parameters related to neutrino oscillations. Glass Resistive Plate Chambers (RPCs) of about 2 mx2 m in size are going to be used as active elements for the ICAL detector. We have fabricated a large number of glass RPC prototypes of 1 mx1 m in size and have studied their performance and long term stability. In the process, we have developed and produced a number of materials and components required for fabrication of RPCs. We have also designed and optimised a number of fabrication and quality control procedures for assembling the gas gaps. In this paper we will review our various activities towards development of glass RPCs for the INO ICAL detector. We will present results of the characterisation studies of the RPCs and discuss our plans to prototype 2 mx2 m sized RPCs.

  12. Polarity and ion recombination corrections in continuous and pulsed beams for ionization chambers with high Z chamber walls.

    Science.gov (United States)

    Aldosary, Ghada; Safigholi, Habib; Song, William; Seuntjens, Jan; Sarfehnia, Arman

    2017-03-01

    In this work, the response of Farmer-type ionization chambers fitted with high atomic number (Z) walls is studied, and results of the effects of such walls on polarity and ion recombination correction factors in both continuous and pulsed beams are presented. Measurements were made in a continuous Co-60 beam and a pulsed 6MV linac beam using an Exradin-A12 ionization chamber fitted with the manufacturer's C-552 plastic wall, as well as geometrically identical walls made from aluminum, copper and molybdenum. The bias voltage was changed between 10values (range: +50 to +560V). Ion recombination was determined from Jaffé plots and by using the "two-voltage technique". The saturation charge measured with each chamber wall was extrapolated from Jaffé plots. Additionally, the effect of different wall materials on chamber response was studied using MCNP simulations. Results showed that the polarity correction factor is not significantly affected by changes in chamber wall material (within 0.1%). Furthermore, although the saturation charges greatly vary with each chamber wall material, and charge multiplication increases for higher atomic number wall materials, the standard methods of calculating ion recombination yielded results that differed by only 0.2%. Therefore, polarity and ion recombination correction factors are not greatly affected by the chamber wall material. The experimental saturation charges for all the different wall materials agreed well within the uncertainty with MCNP simulations. The breakdown of the linear relationship in Jaffé plots that was previously reported to exist for conventional chamber walls was also observed with the different wall materials.

  13. [Influence on measurements of pre-irradiation due to differences in ionization chamber shape or frequency in use].

    Science.gov (United States)

    Shimono, Tetsunori; Nambu, Hidekazu; Matsubara, Kosuke; Koshida, Kichiro; Gomi, Tsutomu

    2012-01-01

    Ionization chamber measurements in radiation therapy should be repeatedly performed until a stable reading is obtained. Ionization chambers exhibit a response which depends on time elapsed since the previous irradiation. In this study, we investigated the response of a set of two Farmer-style, one Plane parallel, and seven small ionization chambers, which are exposed to 4, 6, 10, and 14 MV. The results show that Farmer-style and Plane parallel ionization chambers settle quickly within 9-20 min. On the other hand, small ionization chambers exhibit settling times of 12-33 min for 6, 10, and 14 MV. It will take longer for a settling time of 4 MV. The settling time showed time dependent irradiation. The first reading was up to 0.76% lower in the Farmer-style and Plane parallel ionization chambers. The small ionization chambers had a 2.60% lower first reading and more gradual response in reaching a stable reading. In this study, individual ionization chambers can vary significantly in their settling behavior. Variation of the responses on ionization chambers were confirmed not only when radiation was not used for a week but also when it was halted for a month. Pre-irradiation of small ionization chambers is clearly warranted for eliminating inadvertent error in the calibration of radiation beams.

  14. Quality assurance of proton beams using a multilayer ionization chamber system

    Energy Technology Data Exchange (ETDEWEB)

    Dhanesar, Sandeep; Sahoo, Narayan; Kerr, Matthew; Taylor, M. Brad; Summers, Paige; Zhu, X. Ronald; Poenisch, Falk; Gillin, Michael [Department of Radiation Physics and Proton Therapy Center, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 94, Houston, Texas 77030 (United States); Department of Radiation Physics and Proton Therapy Center, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 94, Houston, Texas 77030 and The University of Texas at Houston Graduate School of Biomedical Sciences, 6767 Bertner Avenue, S3.8344, Houston, Texas 77030 (United States); Department of Radiation Physics and Proton Therapy Center, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 94, Houston, Texas 77030 (United States); Department of Radiation Physics and Proton Therapy Center, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 94, Houston, Texas 77030 and The University of Texas at Houston Graduate School of Biomedical Sciences, 6767 Bertner Avenue, S3.8344, Houston, Texas 77030 (United States)

    2013-09-15

    Purpose: The measurement of percentage depth-dose (PDD) distributions for the quality assurance of clinical proton beams is most commonly performed with a computerized water tank dosimetry system with ionization chamber, commonly referred to as water tank. Although the accuracy and reproducibility of this method is well established, it can be time-consuming if a large number of measurements are required. In this work the authors evaluate the linearity, reproducibility, sensitivity to field size, accuracy, and time-savings of another system: the Zebra, a multilayer ionization chamber system.Methods: The Zebra, consisting of 180 parallel-plate ionization chambers with 2 mm resolution, was used to measure depth-dose distributions. The measurements were performed for scattered and scanned proton pencil beams of multiple energies delivered by the Hitachi PROBEAT synchrotron-based delivery system. For scattered beams, the Zebra-measured depth-dose distributions were compared with those measured with the water tank. The principal descriptors extracted for comparisons were: range, the depth of the distal 90% dose; spread-out Bragg peak (SOBP) length, the region between the proximal 95% and distal 90% dose; and distal-dose fall off (DDF), the region between the distal 80% and 20% dose. For scanned beams, the Zebra-measured ranges were compared with those acquired using a Bragg peak chamber during commissioning.Results: The Zebra demonstrated better than 1% reproducibility and monitor unit linearity. The response of the Zebra was found to be sensitive to radiation field sizes greater than 12.5 × 12.5 cm; hence, the measurements used to determine accuracy were performed using a field size of 10 × 10 cm. For the scattered proton beams, PDD distributions showed 1.5% agreement within the SOBP, and 3.8% outside. Range values agreed within −0.1 ± 0.4 mm, with a maximum deviation of 1.2 mm. SOBP length values agreed within 0 ± 2 mm, with a maximum deviation of 6 mm. DDF

  15. Backscattered radiation into a transmission ionization chamber: measurement and Monte Carlo simulation.

    Science.gov (United States)

    Yoshizumi, Maíra T; Yoriyaz, Hélio; Caldas, Linda V E

    2010-01-01

    Backscattered radiation (BSR) from field-defining collimators can affect the response of a monitor chamber in X-radiation fields. This contribution must be considered since this kind of chamber is used to monitor the equipment response. In this work, the dependence of a transmission ionization chamber response on the aperture diameter of the collimators was studied experimentally and using a Monte Carlo (MC) technique. According to the results, the BSR increases the chamber response of over 4.0% in the case of a totally closed collimator and 50 kV energy beam, using both techniques. The results from Monte Carlo simulation confirm the validity of the simulated geometry.

  16. Evaluation of a plane-parallel ionization chamber for low-energy radiotherapy beams

    Energy Technology Data Exchange (ETDEWEB)

    Perini, Ana Paula; Neves, Lucio Pereira; Santos, William de Souza; Caldas, Linda V.E., E-mail: aperini@ipen.br, E-mail: lpneves@ipen.br, E-mail: wssantos@ipen.br, E-mail: lcaldas@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2014-07-01

    A plane-parallel ionization chamber, with a sensitive volume of 6.3 cm{sup 3}, developed at the Calibration Laboratory of IPEN (LCI), was utilized to verify the possibility of its application in low-energy X-ray beam qualities for radiotherapy (T-qualities). This homemade ion chamber was manufactured using polymethyl methacrylate (PMMA) coated with graphite, and co-axial cables. In order to evaluate the performance of this ionization chamber, some characterization tests were performed: short- and medium-term stability, leakage current, saturation, ion collection efficiency, polarity effect and linearity of response. The maximum value obtained in the short-term stability test was 0.2%, in accordance with the limit value of 0.3% provided by the IEC 60731 standard. The saturation curve was obtained varying the applied voltage from -400 V to +400 V, in steps of 50 V, using the charge collecting time of 20 s. From the saturation curve two other characteristics were analyzed: the polarity effect and the ion collection efficiency, with results within the international recommendations. The leakage current of the ionization chamber was measured in time intervals of 20 minutes, before and after its irradiations, and all the results obtained were in agreement with the IEC 60731 standard. The linearity of response was verified utilizing the T-50(b) radiation quality, and the ionization chamber was exposed to different air kerma rates. The response of the ionization chamber presented a linear behavior. Therefore, all results were considered satisfactory, within international recommendations, indicating that this homemade ionization chamber presents potential routine use in dosimetry of low-energy radiotherapy beams. (author)

  17. Dosimetric evaluation of newly developed well-type ionization chamber for use in the calibration of brachytherapy sources

    Directory of Open Access Journals (Sweden)

    Sathiyan Saminathan

    2016-01-01

    Full Text Available The well-type ionization chamber has been designed for convenient use in brachytherapy source strength calibration. The chamber has a volume of 240 cm 3 , weight of 2.5 kg, and is open to atmospheric conditions. The well-type ionization chamber dosimetric characteristics such as leakage current, stability, scattering effect, ion collection efficiency, and nominal response with energy were studied. The evaluated dosimetric characteristics of well-type ionization chamber were compared with two other commercially available well-type ionization chambers. The study shows that the newly developed well-type ionization chamber is reliable for air-kerma strength calibration. The results obtained confirm that this chamber can be used for the calibrations of high-dose rate brachytherapy sources.

  18. Dosimetric evaluation of newly developed well-type ionization chamber for use in the calibration of brachytherapy sources.

    Science.gov (United States)

    Saminathan, Sathiyan; Godson, Henry Finlay; Ponmalar, Retna; Manickam, Ravikumar; Mazarello, James

    2016-01-01

    The well-type ionization chamber has been designed for convenient use in brachytherapy source strength calibration. The chamber has a volume of 240 cm(3), weight of 2.5 kg, and is open to atmospheric conditions. The well-type ionization chamber dosimetric characteristics such as leakage current, stability, scattering effect, ion collection efficiency, and nominal response with energy were studied. The evaluated dosimetric characteristics of well-type ionization chamber were compared with two other commercially available well-type ionization chambers. The study shows that the newly developed well-type ionization chamber is reliable for air-kerma strength calibration. The results obtained confirm that this chamber can be used for the calibrations of high-dose rate brachytherapy sources.

  19. An open-walled ionization chamber appropriate to tritium monitoring for glovebox.

    Science.gov (United States)

    Chen, Zhilin; Chang, Ruiming; Mu, Long; Song, Guoyang; Wang, Heyi; Wu, Guanyin; Wei, Xiye

    2010-07-01

    An open-walled ionization chamber is developed to monitor the tritium concentration in gloveboxes in tritium processing systems. Two open walls are used to replace the sealed wall in common ionization chambers, through which the tritium gas can diffuse into the chamber without the aid of pumps and pipelines. Some basic properties of the chamber are examined to evaluate its performance. Results turn out that an open-walled chamber of 1 l in volume shows a considerably flat plateau over 700 V for a range of tritium concentration. The chamber also gives a good linear response to gamma fields over 4 decades under a pressure condition of 1 atm. The pressure dependence characteristics show that the ionization current is only sensitive at low pressures. The pressure influence becomes weaker as the pressure increases mainly due to the decrease in the mean free path of beta particles produced by tritium decay. The minimum detection limit of the chamber is 3.7x10(5) Bq/m(3).

  20. Absolute dosimetry on a dynamically scanned sample for synchrotron radiotherapy using graphite calorimetry and ionization chambers

    Science.gov (United States)

    Lye, J. E.; Harty, P. D.; Butler, D. J.; Crosbie, J. C.; Livingstone, J.; Poole, C. M.; Ramanathan, G.; Wright, T.; Stevenson, A. W.

    2016-06-01

    The absolute dose delivered to a dynamically scanned sample in the Imaging and Medical Beamline (IMBL) on the Australian Synchrotron was measured with a graphite calorimeter anticipated to be established as a primary standard for synchrotron dosimetry. The calorimetry was compared to measurements using a free-air chamber (FAC), a PTW 31 014 Pinpoint ionization chamber, and a PTW 34 001 Roos ionization chamber. The IMBL beam height is limited to approximately 2 mm. To produce clinically useful beams of a few centimetres the beam must be scanned in the vertical direction. In practice it is the patient/detector that is scanned and the scanning velocity defines the dose that is delivered. The calorimeter, FAC, and Roos chamber measure the dose area product which is then converted to central axis dose with the scanned beam area derived from Monte Carlo (MC) simulations and film measurements. The Pinpoint chamber measures the central axis dose directly and does not require beam area measurements. The calorimeter and FAC measure dose from first principles. The calorimetry requires conversion of the measured absorbed dose to graphite to absorbed dose to water using MC calculations with the EGSnrc code. Air kerma measurements from the free air chamber were converted to absorbed dose to water using the AAPM TG-61 protocol. The two ionization chambers are secondary standards requiring calibration with kilovoltage x-ray tubes. The Roos and Pinpoint chambers were calibrated against the Australian primary standard for air kerma at the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA). Agreement of order 2% or better was obtained between the calorimetry and ionization chambers. The FAC measured a dose 3-5% higher than the calorimetry, within the stated uncertainties.

  1. Evaluation of a tissue equivalent ionization chamber in X-ray beams

    Energy Technology Data Exchange (ETDEWEB)

    Perini, Ana Paula; Neves, Lucio Pereira; Santos, William de Souza; Caldas, Linda V.E., E-mail: aperini@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Frimaio, Audrew [Seal Technology Ind. Com. Ltda, Sao Paulo, SP (Brazil); Costa, Paulo R. [Universidade de Sao Paulo (USP/IF), Sao Paulo, SP (Brazil). Inst. de Fisica

    2014-07-01

    Tissue equivalent materials present a variety of uses, including routine quality assurance and quality control programs in both diagnostic and therapeutic physics. They are frequently used in research facilities to measure doses delivered to patients undergoing various clinical procedures. This work presents the development and evaluation of a tissue equivalent ionization chamber, with a sensitive volume of 2.3 cm{sup 3}, for routine use in X-rays beams. This ionization chamber was developed at the Calibration Laboratory/IPEN. The new tissue equivalent material was developed at the Physics Institute of the University of Sao Paulo. In order to evaluate the dosimetric performance of the new ionization chamber, several tests described by international standards were undertaken, and all results were within the recommended limits. (author)

  2. Initial test results of an ionization chamber shower detector for a LHC luminosity monitor

    CERN Document Server

    Datte, P S; Haguenauer, Maurice; Manfredi, P F; Manghisoni, M; Millaud, J E; Placidi, Massimo; Ratti, L; Riot, V J; Schmickler, Hermann; Speziali, V; Traversi, G; Turner, W C

    2003-01-01

    A novel segmented multigap pressurized gas ionization chamber is being developed for optimization of the luminosity of the Large Hadron Collider (LHC). The ionization chambers are to be installed in the front quadrupole and 0 degrees neutral particle absorbers in the high luminosity interaction regions (IRs) and sample the energy deposited near the maxima of the hadronic/electromagnetic showers in these absorbers. The ionization chambers are instrumented with low noise, fast pulse-shaping electronics to be capable of resolving individual bunch crossings at 40 MHz. In this paper, we report the initial results of our second test of this instrumentation in a super proton synchrotron (SPS) external proton beam. Single 300 GeV protons are used to simulate the hadronic/electromagnetic showers produced by the forward collision products from the interaction regions of the LHC. The capability of instrumentation to measure the luminosity of individual bunches in a 40 MHz bunch train is demonstrated. (10 refs) .

  3. Calibration of KRISS reference ionization chamber for key comparison of (99m)Tc measurement.

    Science.gov (United States)

    Lee, Jong-Man; Lee, K B; Lee, S H; Park, Tae Soon

    2012-09-01

    KRISS, as the national metrology institute of Korea, has used a reference ionization chamber system to certify the activity of (99m)Tc aqueous sources, but could only recently participate in a comparison exercise by the BIPM (BIPM.RI(II)-K4.Tc-99m) to secure the international equivalence of (99m)Tc radioactivity measurement by way of the BIPM transfer instrument (SIRTI). The KRISS ionization chamber system was calibrated about 100 days before the comparison with a (99m)Tc solution source standardized by the 4πβ(LS)-γ(NaI(Tl)) coincidence counting method. During the comparison, beginning with a higher activity mother solution, the KRISS ionization chamber measured its specific activity without a dilution. The activity of a diluted-solution source was measured by the SIRTI at the same time.

  4. Measurement of ion and electron drift velocity and electronic attachment in air for ionization chambers

    CERN Document Server

    Boissonnat, Guillaume; Colin, Jean; Remadi, Aurelien; Salvador, Samuel

    2016-01-01

    Air-ionization chambers have been used in radiotherapy and particle therapy for decades. However, fundamental parameters in action in the detector responses are sparsely studied. In this work we aimed to measure the electronic attachment, electrons and ions mobilities of an ionization chamber (IC) in air. The main idea is to extract these from the actual response of the IC to a single ionizing particle in order to insure that they were measured in the same condition they are to be used while neglecting undesired phenomena: recombination and space charge effect. The non-standard signal shape analysis performed here were also confronted to a more standard drift chamber measurements using time-of-flight. It was found that both detectors displayed compatible results concerning positive and negative ions drift velocities where literature data is well spread out. In the same time, electron attachment measurements sit in the middle of known measurements while electron drift velocities seemed to show an offset compar...

  5. Development of an Ionization Chamber for the SPIDER Fission Fragment Detector

    Science.gov (United States)

    Meierbachtol, K.; Tovesson, F.; Arnold, C. W.; Laptev, A. B.; Bredeweg, T. A.; Jandel, M.; Nelson, R. O.; White, M. C.

    2014-05-01

    The ionization chamber component of the SPIDER detector has been designed to measure energy loss and kinetic energy of fragments produced through neutron-induced fission with energy resolutions of <1% and a time-dependent signal collection. Important design elements implemented are an axial configuration of the electrodes for improved energy loss and measurement and a thin silicon nitride entrance window to minimize both energy loss and energy straggling of the incoming fragments. High energy resolution and improved charge resolution from the ionization chamber are combined with the high precision of the upstream time-of-flight component of SPIDER to achieve resolutions in mass and nuclear charge of 1 AMU and Z=1. A discussion of the present resolution capabilities of the ionization chamber will be presented.

  6. Design and preliminary test of a free-air ionization chamber for low-energy X-ray

    Institute of Scientific and Technical Information of China (English)

    WU Jin-Jie; YANG Yuan-Di; WANG Pei-Wei; CHEN Jing; LIU Jia-Cheng

    2011-01-01

    A free-air ionization chamber in low-energy X-ray has been designed and manufactured at theNational Institute of Metrology (NIM, China) according to the defination of alr-kerma. The results of a preliminary test show that the leakage current of ionization chamber is around 2×10A, and the correction factor of ion recombination for the ionization chamber is also obtained. The free-air ionization chamber is suitable for the primary standard in low-energy X-rays.

  7. Dosimetric characterization of a large area pixel-segmented ionization chamber.

    Science.gov (United States)

    Amerio, S; Boriano, A; Bourhaleb, F; Cirio, R; Donetti, M; Fidanzio, A; Garelli, E; Giordanengo, S; Madon, E; Marchetto, F; Nastasi, U; Peroni, C; Piermattei, A; Sanz Freire, C J; Sardo, A; Trevisiol, E

    2004-02-01

    A pixel-segmented ionization chamber has been designed and built by Torino University and INFN. The detector features a 24 x 24 cm2 active area divided in 1024 independent cylindrical ionization chambers and can be read out in 500 micros without introducing dead time; the digital charge quantum can be adjusted between 100 fC and 800 fC. The sensitive volume of each single ionization chamber is 0.07 cm3. The purpose of the detector is to ease the two-dimensional (2D) verifications of fields with complex shapes and large gradients. The detector was characterized in a PMMA phantom using 60Co and 6 MV x-ray photon beams. It has shown good signal linearity with respect to dose and dose rate to water. The average sensitivity of a single ionization chamber was 2.1 nC/Gy, constant within 0.5% over one month of daily measurements. Charge collection efficiency was 0.985 at the operating polarization voltage of 400 V and 3.5 Gy/min dose rate. Tissue maximum ratio and output factor have been compared with a Farmer ionization chamber and were found in good agreement. The dose profiles have been compared with the ones obtained with an ionization chamber in water phantom for the field sizes supplied by a 3D-Line dynamic multileaf collimator. These results show that this detector can be used for 2D dosimetry of x-ray photon beams, supplying a good spatial resolution and sensibly reducing the time spent in dosimetric verification of complex radiation fields.

  8. Preliminary results with a strip ionization chamber used as beam monitor for hadrontherapy treatments

    Science.gov (United States)

    Boriano, A.; Bourhaleb, F.; Cirio, R.; Cirrone, G. A. P.; Cuttone, G.; Donetti, M.; Garelli, E.; Giordanengo, S.; Luparia, A.; Marchette, F.; Peroni, C.; Raffaele, L.; Sabini, M. G.; Valastro, L.

    2006-01-01

    Preliminary results are presented from a test of a parallel plate ionization chamber with the anode segmented in strips (MOPI) to be used as a beam monitor for therapeutical treatments on the 62 MeV proton beam line of the INFN-LNS Superconducting Cyclotron. Ocular pathologies have been treated at the Catana facility since March 2002. The detector, placed downstream of the patient collimator, will allow the measurement of the relevant beam diagnostic parameters during treatment such as integrated beam fluence, for dose determination; the beam baricentre, width and asymmetry will be obtained from the fluence profile sampled with a resolution of about 100 Urn at a rate up to 1 kHz with no dead time. In this test, carried out at LNS, the detector has been exposed to different beam shapes and the integrated fluence derived by the measured beam profiles has been compared with that obtained with other dosimeters normally used for treatment. The skewness of the beam profile has been measured and shown to be suitable to on-line check variations of the beam shape.

  9. Update of NIST half-life results corrected for ionization chamber source-holder instability.

    Science.gov (United States)

    Unterweger, M P; Fitzgerald, R

    2014-05-01

    As reported at the ICRM 2011, it was discovered that the source holder used for calibrations in the NIST 4πγ ionization chamber (IC) was not stable. This has affected a large number of half-life measurement results previously reported and used in compilations of nuclear data. Corrections have been made on all of the half-life data based on the assumption that the changes to the ionization chamber response were gradual. The corrections are energy dependent and therefore radionuclide specific. This presentation will review our results and present the recommended changes in half-life values and/or uncertainties.

  10. Construction of a fast ionization chamber for high-rate particle identification

    Energy Technology Data Exchange (ETDEWEB)

    Chae, K.Y., E-mail: kchae@skku.edu [Department of Physics, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Ahn, S. [Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 (United States); Bardayan, D.W. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Chipps, K.A. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 (United States); Department of Physics, Colorado School of Mines, Golden, CO 80401 (United States); Manning, B. [Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854 (United States); Pain, S.D. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Peters, W.A. [Oak Ridge Associated Universities, Oak Ridge, TN 37831 (United States); Schmitt, K.T. [Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 (United States); Smith, M.S. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Strauss, S.Y. [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854 (United States)

    2014-07-01

    A new gas-filled ionization chamber for high count rate particle identification has been constructed and commissioned at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory (ORNL). To enhance the response time of the ionization chamber, a design utilizing a tilted entrance window and tilted electrodes was adopted, which is modified from an original design by Kimura et al. [1]. A maximum counting rate of ∼700,000 particles per second has been achieved. The detector has been used for several radioactive beam measurements performed at the HRIBF.

  11. Performance of three pencil-type ionization chambers (10 cm) in computed tomography standard beams

    Science.gov (United States)

    de Castro, Maysa C.; Xavier, Marcos; Caldas, Linda V. E.

    2016-07-01

    The use of computed tomography (CT) has increased over the years, thus generating a concern about the doses received by patients undergoing this procedure. Therefore, it is necessary to perform routinely beam dosimetry with the use of a pencil-type ionization chamber. This detector is the most utilized in the procedures of quality control tests on this kind of equipment. The objective of this work was to perform some characterization tests in standard CT beams, as the saturation curve, polarity effect, ion collection efficiency and linearity of response, using three ionization chambers, one commercial and two developed at the IPEN.

  12. Determination of (137)Cs half-life with an ionization chamber.

    Science.gov (United States)

    Juget, Frédéric; Nedjadi, Youcef; Buchillier, Thierry; Bochud, François; Bailat, Claude

    2016-12-01

    The half-life of (137)Cs was measured with an ionization chamber by following the decay of 5 sources over a 30 years period between 1983 and 2013. The ratio between the ionization chamber current for the cesium sources and (226)Ra source was used for the half-life calculation. The value found for the (137)Cs half-life is 10,955.2±10.7 days, where the uncertainty evaluation combines type A and B for one standard deviation.

  13. Characterization of a free air ionization chamber for low energy X-rays

    Science.gov (United States)

    Silva, N. F.; Xavier, M.; Vivolo, V.; Caldas, L. V. E.

    2016-07-01

    Free air ionization chambers are used by most primary metrology laboratories as primary standards of the quantities air kerma and exposure in X-ray beams. The free air ionization chamber for low energies of the Calibration Laboratory (LCI) of IPEN showed in a characterization test a problem in the set responsible for the variation of its sensitive volume. After a modification in the support of the micrometers used for the movement of the internal cylinder and the establishment of a new alignment system protocol, the tests were redone. The objective of this work was to present the results obtained in the new condition.

  14. Construction of a fast ionization chamber for high-rate particle identification

    Science.gov (United States)

    Chae, K. Y.; Ahn, S.; Bardayan, D. W.; Chipps, K. A.; Manning, B.; Pain, S. D.; Peters, W. A.; Schmitt, K. T.; Smith, M. S.; Strauss, S. Y.

    2014-07-01

    A new gas-filled ionization chamber for high count rate particle identification has been constructed and commissioned at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory (ORNL). To enhance the response time of the ionization chamber, a design utilizing a tilted entrance window and tilted electrodes was adopted, which is modified from an original design by Kimura et al. [1]. A maximum counting rate of ~700,000 particles per second has been achieved. The detector has been used for several radioactive beam measurements performed at the HRIBF.

  15. Influence of the radioactive source position inside the well-type ionization chamber

    Energy Technology Data Exchange (ETDEWEB)

    Kuahara, L.T.; Correa, E.L.; Potiens, M.P.A., E-mail: liliankuahara@usp.br [Instituto de Pesquisas Energeticas e Nucleres (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    The activimeter, instrument used in radionuclide activity measurement, consists primarily of a well type ionization chamber coupled to a special electronic device. Its response, after calibration, is shown in activity units (Becquerel or Curie). The goal of this study is to verify radioactive source position influence over activity measured by this instrument. Radioactive sources measurements were made at different depths inside the ionization chamber well. Results showed maximum variation of -23 %, -28 % and -15 % for {sup 57}Co, {sup 133}Ba and {sup 137}Cs, respectively. (author)

  16. Performance of three pencil-type ionization chambers (10 cm) in computed tomography standard beams

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Maysa C. de; Xavier, Marcos; Caldas, Linda V.E., E-mail: mcastro@ipen.br, E-mail: mxavier@ipen.br, E-mail: lcaldas@ipen.br [Instituto de Pesquisas Energeticas e Nucleres (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    The use of computed tomography (CT) has increased over the years, thus generating a concern about the doses received by patients undergoing this procedure. Therefore, it is necessary to perform routinely beam dosimetry with the use of a pencil-type ionization chamber. This detector is the most utilized in the procedures of quality control tests on this kind of equipment. The objective of this work was to perform some characterization tests in standard CT beams, as the saturation curve, polarity effect, ion collection efficiency and linearity of response, using three ionization chambers, one commercial and two developed at the IPEN. (author)

  17. Two-dimensional and quasi-three-dimensional dosimetry of hadron and photon beams with the Magic Cube and the Pixel Ionization Chamber

    Science.gov (United States)

    Cirio, R.; Garelli, E.; Schulte, R.; Amerio, S.; Boriano, A.; Bourhaleb, F.; Coutrakon, G.; Donetti, M.; Giordanengo, S.; Koss, P.; Madon, E.; Marchetto, F.; Nastasi, U.; Peroni, C.; Santuari, D.; Sardo, A.; Scielzo, G.; Stasi, M.; Trevisiol, E.

    2004-08-01

    Two detectors for fast two-dimensional (2D) and quasi-three-dimensional (quasi-3D) verification of the dose delivered by radiotherapy beams have been developed at University and Istituto Nazionale di Fisica Nucleare (INFN) of Torino. The Magic Cube is a stack of strip-segmented ionization chambers interleaved with water-equivalent slabs. The parallel plate ionization chambers have a sensitive area of 24 × 24 cm2, and consist of 0.375 cm wide and 24 cm long strips. There are a total of 64 strips per chamber. The Magic Cube has been tested with the clinical proton beam at Loma Linda University Medical Centre (LLUMC), and was shown to be capable of fast and precise quasi-3D dose verification. The Pixel Ionization Chamber (PXC) is a detector with pixel anode segmentation. It is a 32 × 32 matrix of 1024 cylindrical ionization cells arranged in a square 24 × 24 cm2 area. Each cell has 0.4 cm diameter and 0.55 cm height, at a pitch of 0.75 cm separates the centre of adjacent cells. The sensitive volume of each single ionization cell is 0.07 cm3. The detectors are read out using custom designed front-end microelectronics and a personal computer-based data acquisition system. The PXC has been used to verify dynamic intensity-modulated radiotherapy for head-and-neck and breast cancers.

  18. Design of ionization chambers for use in teaching x-ray dosimetry

    Science.gov (United States)

    Ross, Joseph

    Ionization chambers are one of the most commonly used radiation detectors in radiation dosimetry. In this project, nine ionization chambers were constructed for use in teaching radiation dosimetry to students of health physics, medical physics, nuclear engineering, and related disciplines. The components of these detectors such as detector wall composition, type of electrode, type of leakage current guard ring, fill gas pressure, and interior conducting material differ in a systematic way to show that various parameters of ionization chamber design can affect the response of the detectors. Each of these variables was investigated using an 80 keV x-ray machine to determine detector response in terms of absorbed dose, HVL, polarity, and operating voltage. Of the components studied, wall thickness and composition was found to be the most sensitive variable. The pressure inside the chamber did have a significant effect on the amount of charge collected and the absorbed dose. The leakage current guard ring was not a critical component for this ionization chamber design.

  19. A ΔE-E Telescope with Ionization Chamber Used in Excitation Function Measurement

    Institute of Scientific and Technical Information of China (English)

    LiSonglin; WangQi; DongYuchuan; XuHuagen; ChenRuofu

    2003-01-01

    A thorough study of excitation function in dissipative heavy ion collision requires the identification of the nuclear charge number Z of the reaction products. For this purpose, a special designed ΔE-E telescope is employed, which consists of a gas filled ionization chamber to detect the energy loss and a position sensitive semiconductor Si detector (300μm in thickness and 8 mm×45 mm in active area) as the residual energy detector. The ionization chamber with a sensitive length of about 60 mm, is divided into two parts of ΔE1 and ΔE2, each with length of 30 mm. The trajectory of the incident particles is parallel to the direction of the electric field in the ionization chamber. The anodes of ΔE1 and ΔE2 are realized through the rectangular empty metallic frames. In order to collect ionized charge produced by the incident particle inside the ionization chamber effectively, two equipotential frame-shape electrodes were placed on both sides of each anode, to form a strong electric focused field toward the anode. The advantages of this type of the detector arc as follows: (1)lower energy detection threshold; (2) wide dynamical range both for the light particles and the heavy fragments;(3) larger solid angle coverage with a relatively smaller detector size based on the position information from the Si detector.

  20. A magnetically levitated electrode ionization chamber of the noncontact measurement type

    CERN Document Server

    Kawaguchi, T

    2002-01-01

    A new type of ionization chamber with levitated electrode has been developed. In this ionization chamber, an ion-collection electrode levitates in the air without getting any physical support from the insulator. The electrode is charged by an electrostatic charger without physical contact. The charge of the electrode is read out at a Faraday cage periodically at a given time interval without physical contact. Because its electrode levitates, the ionization chamber produces no background current caused by leaks or piezo current. In addition, as the charging of its electrode and the read-out of its charge are carried out without physical contact, no irregular charge or contact potential difference due to the chattering between electrode and contact point occurs. Through experiments, it was found that this ionization chamber was able to measure the gamma-ray dose such as the environmental radiation with a high degree of sensitivity. The minimum detectable value of ionization current when accumulated for 1 h is a...

  1. Comparison of experimental and calculated calibration coefficients for a high sensitivity ionization chamber.

    Science.gov (United States)

    Amiot, M N; Mesradi, M R; Chisté, V; Morin, M; Rigoulay, F

    2012-09-01

    The response of a Vacutec 70129 ionization chamber was calculated using the PENELOPE-2008 Monte Carlo code and compared to experimental data. The filling gas mixture composition and its pressure have been determined using IC simulated response adjustment to experimental results. The Monte Carlo simulation revealed a physical effect in the detector response to photons due to the presence of xenon in the chamber. A very good agreement is found between calculated and experimental calibration coefficients for 17 radionuclides.

  2. A comparative study of three ionizing chambers for measurements of personal dose equivalent, Hp(10)

    Science.gov (United States)

    Oliveira, C.; Cardoso, J.; Silva, H.

    2015-11-01

    A comparative study of three ionization chambers which directly measure the quantity personal dose equivalent Hp(10), was performed. Results show that the ratio between the response (air kerma) determined by Monte Carlo and the experimental response (collected charge) normalized by the monitor unit is the same whatever is the chamber and that this ratio is proportional to the conversion coefficients for air kerma from photon fluence.

  3. Ionization chambers for monitoring in high-intensity charged particle beams

    CERN Document Server

    McDonald, J; Viren, B; Diwan, M; Erwin, A R; Naples, D; Ping, H

    2003-01-01

    Radiation-hard ionization chambers were tested using an intense electron beam from the accelerator test facility at the Brookhaven National Laboratory. The detectors were designed to be used as the basic element for monitoring muons in the Main Injector Neutrino beamline at the Fermi National Accelerator Laboratory. Measurements of linearity of response, voltage dependence, and the onset of ionization saturation as a function of gap voltage were performed.

  4. Digital mammography with multi-electrode ionization chamber

    CERN Document Server

    Groshev, V R; Nifontov, V I; Pishenuok, S M; Samsonov, A A; Shekhtman, L I; Telnov, V I

    2000-01-01

    For viewing micro-calcifications smaller than 100 mu m investigation of image formation in mammography shows that a significant dose to the patient is imperative. We propose a novel one-dimensional Multi- electrode Ionisation Chamber (MIC), with high spatial resolution, and lowered doses. In this work, first results from a prototype are presented. High spatial resolution is demonstrated working with Xe mixture at high pressure. An addition of a Gas Electron Multiplier (GEM) allowed an improvement in sensitivity up to almost single- photon level. (8 refs).

  5. Development of a Grid Ionization Chamber for a Dram of α Ray

    Directory of Open Access Journals (Sweden)

    YANG Lu;WANG Qiang;ZHENG Yu-lai;WANG Guo-bao

    2016-11-01

    Full Text Available This article introduced the parallel grid ionization chamber that used to measure the α radioactivity, which had a independent vacuum system. The system was composed of main body of the chamber, gas-filled and electronics system. Energy resolution was 26 keV for 239Pu, background was 10 counts for one hour from 4 MeV to 6 MeV energy range, the stability of 24 hours was less than 0.5% . The chamber can measure the energy of nuclide and analyze the energy spectrum structure to identify nuclear.

  6. 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.

  7. Beam test results on double-gap resistive plate chambers proposed for CMS experiment

    Science.gov (United States)

    Abbrescia, M.; Bruno, G.; Colaleo, A.; Iaselli, G.; Lamanna, G.; Loddo, F.; Maggi, M.; Marangelli, B.; Natali, S.; Nuzzo, S.; Pugliese, G.; Ranieri, A.; Romano, F.; Gianini, G.; Ratti, S. P.; Vitulo, P.

    Resistive Plate Chambers were tested in a muon and pion beam to study the performances at different running conditions. Results on a first chamber built without the linseed oil treatment of the bakelite surfaces are presented together with an evaluation of the local effects due to the spacers. These results are extrapolated to the conditions expected at LHC.

  8. Beam Test Results on Resistive Plate Chambers for the CMS Experiment

    CERN Document Server

    Abbrescia, Marcello; Calaeo, A; Iaselli, Giuseppe; Lammana, G; Loddo, Flavio; Maggi, Marcello; Marangelli, Bartolomeo; Natali, Sergio; Nuzzo, Salvatore; Puglise, G; Ranieri, Riccardo; Ratti, Sergio P; Romano, Francesco; Vitulo, Paolo

    1998-01-01

    Resistive Plate Chambers were tested in a muon and a pion beam to study the performances at different running conditions. Results on a first chamber built without the linseed oil treatment of the bakelite surfaces are presented together with an evaluation of the local effects dut to spacers. These results are extrapolated to the conditions expected at LHC.

  9. Determination of saturation charge and collection efficiency for ionization chambers in continuous beams.

    Science.gov (United States)

    Zankowski, C; Podgorsak, E B

    1998-06-01

    The procedure recommended by radiation dosimetry protocols for determining the collection efficiency f of an ionization chamber assumes the predominance of general recombination and ignores other charge loss mechanisms such as initial recombination and ionic diffusion. For continuous radiation beams, general recombination theory predicts that f can be determined from a linear relationship between 1/Q and 1/V2 in the near saturation region (f > 0.7), where Q is the measured charge and V the applied chamber potential. Measurements with Farmer-type cylindrical ionization chambers exposed to cobalt-60 gamma rays reveal that the assumed linear relationship between 1/Q and 1/V2 breaks down in the extreme near-saturation region (f > 0.99) where Q increases with V at a rate exceeding the predictions of general recombination theory. A comprehensive model is developed to describe the saturation characteristics of ionization chambers. The model accounts for dosimetric charge loss (initial recombination, ionic diffusion, and general recombination) and nondosimetric charge multiplication in an ionization chamber, and suggests that charge multiplication plays a significant role under typical chamber operating conditions (300 V) used in radiation dosimetry. Through exclusion of charge multiplication from the measured chamber signal Q, the model predicts the breakdown of the 1/Q vs 1/V2 relationship and shows that the final approach to saturation is governed by initial recombination and ionic diffusion which are characterized by a linear relationship between 1/Q and 1/V. Collection efficiencies calculated with this model differ by up to 0.4% from those determined through a rigorous application of general recombination theory alone.

  10. Determination of relative ion chamber calibration coefficients from depth-ionization measurements in clinical electron beams

    Science.gov (United States)

    Muir, B. R.; McEwen, M. R.; Rogers, D. W. O.

    2014-10-01

    A method is presented to obtain ion chamber calibration coefficients relative to secondary standard reference chambers in electron beams using depth-ionization measurements. Results are obtained as a function of depth and average electron energy at depth in 4, 8, 12 and 18 MeV electron beams from the NRC Elekta Precise linac. The PTW Roos, Scanditronix NACP-02, PTW Advanced Markus and NE 2571 ion chambers are investigated. The challenges and limitations of the method are discussed. The proposed method produces useful data at shallow depths. At depths past the reference depth, small shifts in positioning or drifts in the incident beam energy affect the results, thereby providing a built-in test of incident electron energy drifts and/or chamber set-up. Polarity corrections for ion chambers as a function of average electron energy at depth agree with literature data. The proposed method produces results consistent with those obtained using the conventional calibration procedure while gaining much more information about the behavior of the ion chamber with similar data acquisition time. Measurement uncertainties in calibration coefficients obtained with this method are estimated to be less than 0.5%. These results open up the possibility of using depth-ionization measurements to yield chamber ratios which may be suitable for primary standards-level dissemination.

  11. Calibration coefficient of reference brachytherapy ionization chamber using analytical and Monte Carlo methods.

    Science.gov (United States)

    Kumar, Sudhir; Srinivasan, P; Sharma, S D

    2010-06-01

    A cylindrical graphite ionization chamber of sensitive volume 1002.4 cm(3) was designed and fabricated at Bhabha Atomic Research Centre (BARC) for use as a reference dosimeter to measure the strength of high dose rate (HDR) (192)Ir brachytherapy sources. The air kerma calibration coefficient (N(K)) of this ionization chamber was estimated analytically using Burlin general cavity theory and by the Monte Carlo method. In the analytical method, calibration coefficients were calculated for each spectral line of an HDR (192)Ir source and the weighted mean was taken as N(K). In the Monte Carlo method, the geometry of the measurement setup and physics related input data of the HDR (192)Ir source and the surrounding material were simulated using the Monte Carlo N-particle code. The total photon energy fluence was used to arrive at the reference air kerma rate (RAKR) using mass energy absorption coefficients. The energy deposition rates were used to simulate the value of charge rate in the ionization chamber and N(K) was determined. The Monte Carlo calculated N(K) agreed within 1.77 % of that obtained using the analytical method. The experimentally determined RAKR of HDR (192)Ir sources, using this reference ionization chamber by applying the analytically estimated N(K), was found to be in agreement with the vendor quoted RAKR within 1.43%.

  12. Time-resolved dosimetry using a pinpoint ionization chamber as quality assurance for IMRT and VMAT

    NARCIS (Netherlands)

    Louwe, R.J.; Wendling, M.; Monshouwer, R.; Satherley, T.; Day, R.A.; Greig, L.

    2015-01-01

    PURPOSE: To develop a method to verify the dose delivery in relation to the individual control points of intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) using an ionization chamber. In addition to more effective problem solving during patient-specific quality assu

  13. A VLSI analog pipeline read-out for electrode segmented ionization chambers

    CERN Document Server

    Bonazzola, G C; Cirio, R; Donetti, M; Figus, M; Marchetto, F; Peroni, C; Pernigotti, E; Thénard, J M; Zampieri, A

    1999-01-01

    We report on the design and test of a 32-channel VLSI chip based on the analog pipeline memory concept. The charge from a strip of a ionization chamber, is stored as a function of time in a switched capacitor array. The cell reading can be done in parallel with the writing.

  14. Measurement of surface alpha-acrivity of different samples with ion pulse ionization chamber

    CERN Document Server

    Gavriljuk, Yu M; Gangapshev, A M; Kazalov, V V; Kuzminov, V V; Panasenko, S I; Ratkevich, S S

    2007-01-01

    The construction of an ion pulse ionization chamber aimed at measuring ultra-low levels of surface alpha-activity of different samples is described. The results of measurement carried out with alpha-source and copper samples and light-reflecting film VM2000 are presented.

  15. A VLSI analog pipeline read-out for electrode segmented ionization chambers

    Science.gov (United States)

    Bonazzola, G. C.; Bouvier, S.; Cirio, R.; Donetti, M.; Figus, M.; Marchetto, F.; Peroni, C.; Pernigotti, E.; Thenard, J. M.; Zampieri, A.

    1999-05-01

    We report on the design and test of a 32-channel VLSI chip based on the analog pipeline memory concept. The charge from a strip of a ionization chamber, is stored as a function of time in a switched capacitor array. The cell reading can be done in parallel with the writing.

  16. Source geometry factors for HDR 192Ir brachytherapy secondary standard well-type ionization chamber calibrations

    Science.gov (United States)

    Shipley, D. R.; Sander, T.; Nutbrown, R. F.

    2015-03-01

    Well-type ionization chambers are used for measuring the source strength of radioactive brachytherapy sources before clinical use. Initially, the well chambers are calibrated against a suitable national standard. For high dose rate (HDR) 192Ir, this calibration is usually a two-step process. Firstly, the calibration source is traceably calibrated against an air kerma primary standard in terms of either reference air kerma rate or air kerma strength. The calibrated 192Ir source is then used to calibrate the secondary standard well-type ionization chamber. Calibration laboratories are usually only equipped with one type of HDR 192Ir source. If the clinical source type is different from that used for the calibration of the well chamber at the standards laboratory, a source geometry factor, ksg, is required to correct the calibration coefficient for any change of the well chamber response due to geometric differences between the sources. In this work we present source geometry factors for six different HDR 192Ir brachytherapy sources which have been determined using Monte Carlo techniques for a specific ionization chamber, the Standard Imaging HDR 1000 Plus well chamber with a type 70010 HDR iridium source holder. The calculated correction factors were normalized to the old and new type of calibration source used at the National Physical Laboratory. With the old Nucletron microSelectron-v1 (classic) HDR 192Ir calibration source, ksg was found to be in the range 0.983 to 0.999 and with the new Isodose Control HDR 192Ir Flexisource ksg was found to be in the range 0.987 to 1.004 with a relative uncertainty of 0.4% (k = 2). Source geometry factors for different combinations of calibration sources, clinical sources, well chambers and associated source holders, can be calculated with the formalism discussed in this paper.

  17. Performance of a Roos ionization chamber in gamma radiation beams ({sup 60}Co)

    Energy Technology Data Exchange (ETDEWEB)

    Perini, Ana P.; Neves, Lucio P.; Caldas, Linda V.E., E-mail: lcaldas@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    Among the different types of dosimetry instruments, the ionization chambers are the most practical and and important radiation measurement devices due to their high sensitivity and relatively constant response within a wide range of energies. A commercial PTW ionization chamber (Roos electron chamber) usually utilized in X-ray beams, was tested to verify the possibility of its dosimetric application in {sup 60}Co beams. The main tests in this work were: short- and long-term stability, saturation, ion collection efficiency, polarity effect, leakage current and angular dependence. The characterization tests were performed using a Gammatron {sup 60}Co irradiator and a special goniometer made of PMMA. All results were within international recommendations. The reproducibility test presented results within the recommended limit of {+-}1%, and all coefficients of variation observed in the repeatability test were lower than {+-}0.07%. The ion collection efficiency was better than 99.9% for both polarities. For all pairs of polarity evaluated during the saturation test, the polarity effect was lower than the recommended limit. The maximum variation obtained for angular dependence test was only 0.5%. The chamber tested in this work achieved the expected results in the case of all pre-operational tests realized: stability, leakage current, angular dependence, saturation, ion collection and polarity effect. Evaluating the satisfactory results obtained, it is possible to indicate the usefulness of this ionization chamber for dosimetry in {sup 60}Co gamma radiation beams. (author)

  18. a Solution for Dosimetry and Quality Assurance in Imrt and Hadrontherapy:. the Pixel Ionization Chamber

    Science.gov (United States)

    Amerio, S.; Coda, S.; Nastasi, U.; Belletti, S.; Ghedi, B.; Boriano, A.; Cirio, R.; Luparia, A.; Marchetto, F.; Peroni, C.; Sanz Freire, C. J.; Donetti, M.; Madon, E.; Trevisiol, E.; Urgesi, A.

    2002-11-01

    The new radiotherapy techniques require new detectors to monitor and measure the clinical field. The Intensity Modulated Radiation Therapy (IMRT) techniques like step and shoot, sliding window, dynamic wedge or scanning beam add the time variable to the treatment field. In this case the water phantom with a single ionization chamber moving inside the field needs very long measurement time. Linear arrays of ionization chambers or diodes measure the field only along a line. 2D detectors like radiographic or gafchromic film are not suitable to be used as on line detectors. We have developed, built and tested an ionization chamber segmented in pixels that measure the dose in a plane at several points. Every channel has a dedicated electronic chain that digitizes the collected charge and data from all the channels are sent to the computer that performs the data acquisition. One read out cycle is very fast allowing to measure in real time the fluency and the shape of the field. The chamber can be used in two different ways, as monitor chamber and as relative dosemeter. A description of the detector, the electronics, and test results with both photon and hadron beams will be reported.

  19. On the wall perturbation correction for a parallel-plate NACP-02 chamber in clinical electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Zink, K.; Wulff, J. [University Hospital Marburg, Philipps-University, D-35043 Marburg, Germany and Institut fuer Medizinische Physik und Strahlenschutz - IMPS, University of Applied Sciences Giessen-Friedberg, D-35390 Giessen (Germany); Institut fuer Medizinische Physik und Strahlenschutz - IMPS, University of Applied Sciences Giessen-Friedberg, D-35390 Giessen (Germany)

    2011-02-15

    Purpose: In recent years, several Monte Carlo studies have been published concerning the perturbation corrections of a parallel-plate chamber in clinical electron beams. In these studies, a strong depth dependence of the relevant correction factors (p{sub wall} and p{sub cav}) for depth beyond the reference depth is recognized and it has been shown that the variation with depth is sensitive to the choice of the chamber's effective point of measurement. Recommendations concerning the positioning of parallel-plate ionization chambers in clinical electron beams are not the same for all current dosimetry protocols. The IAEA TRS-398 as well as the IPEM protocol and the German protocol DIN 6800-2 interpret the depth of measurement within the phantom as the water equivalent depth, i.e., the nonwater equivalence of the entrance window has to be accounted for by shifting the chamber by an amount {Delta}z. This positioning should ensure that the primary electrons traveling from the surface of the water phantom through the entrance window to the chamber's reference point sustain the same energy loss as the primary electrons in the undisturbed phantom. The objective of the present study is the determination of the shift {Delta}z for a NACP-02 chamber and the calculation of the resulting wall perturbation correction as a function of depth. Moreover, the contributions of the different chamber walls to the wall perturbation correction are identified. Methods: The dose and fluence within the NACP-02 chamber and a wall-less air cavity is calculated using the Monte Carlo code EGSnrc in a water phantom at different depths for different clinical electron beams. In order to determine the necessary shift to account for the nonwater equivalence of the entrance window, the chamber is shifted in steps {Delta}z around the depth of measurement. The optimal shift {Delta}z is determined from a comparison of the spectral fluence within the chamber and the bare cavity. The wall

  20. High-resolution ion pulse ionization chamber with air filling for the Rn-222 decays detection

    CERN Document Server

    Gavrilyuk, Yu M; Gezhaev, A M; Etezov, R A; Kazalov, V V; Kuzminov, V V; Panasenko, S I; Ratkevich, S S; Tekueva, D A; Yakimenko, S P

    2015-01-01

    The construction and characteristics of the cylindrical ion pulse ionization chamber (CIPIC) with a working volume of 3.2 L are described. The chamber is intended to register alpha-particles from the $^{222}$Rn and its daughter's decays in the filled air sample. The detector is less sensitive to electromagnetic pick-ups and mechanical noises. The digital pulse processing method is proposed to improve the energy resolution of the ion pulse ionization chamber. An energy resolution of 1.6% has been achieved for the 5.49 MeV alpha-line. The dependence of the energy resolution on high voltage and working media pressure has been investigated and the results are presented.

  1. High-resolution ion pulse ionization chamber with air filling for the 222Rn decays detection

    Science.gov (United States)

    Gavrilyuk, Yu. M.; Gangapshev, A. M.; Gezhaev, A. M.; Etezov, R. A.; Kazalov, V. V.; Kuzminov, V. V.; Panasenko, S. I.; Ratkevich, S. S.; Tekueva, D. A.; Yakimenko, S. P.

    2015-11-01

    The construction and characteristics of the cylindrical ion pulse ionization chamber (CIPIC) with a working volume of 3.2 L are described. The chamber is intended to register α-particles from the 222Rn and its daughter's decays in the filled air sample. The detector is less sensitive to electromagnetic pick-ups and mechanical noises. The digital pulse processing method is proposed to improve the energy resolution of the ion pulse ionization chamber. An energy resolution of 1.6% has been achieved for the 5.49 MeV α-line. The dependence of the energy resolution on high voltage and working media pressure has been investigated and the results are presented.

  2. Development and production of the ionization chamber for the T2K muon monitor

    Energy Technology Data Exchange (ETDEWEB)

    Matsuoka, K., E-mail: matsuoka@scphys.kyoto-u.ac.j [Kyoto University, Kitashirakawa-Oiwake-cho Sakyo-ku, Kyoto 606-8502 (Japan); Ichikawa, A.; Kubo, H. [Kyoto University, Kitashirakawa-Oiwake-cho Sakyo-ku, Kyoto 606-8502 (Japan); Maruyama, T. [High Energy Accelerator Research Organization (KEK), Oho 1-1, Tsukuba 305-0801 (Japan); Murakami, A.; Nakaya, T.; Yokoyama, M. [Kyoto University, Kitashirakawa-Oiwake-cho Sakyo-ku, Kyoto 606-8502 (Japan)

    2010-11-01

    We report on the development of an ionization chamber for the muon monitor in the T2K (Tokai-to-Kamioka) long baseline neutrino oscillation experiment. In the T2K experiment, we generate a muon neutrino beam using the 50-GeV proton synchrotron in J-PARC and detect it in the Super-Kamiokande detector, which is 295 km away from J-PARC. We aim the neutrino beam off-axis by 2.5{sup o} from Super-Kamiokande in order to maximize the sensitivity to the neutrino oscillation measurement. Since the beam direction is required to be aimed within 1 mrad, we need to monitor it with a precision better than 1 mrad. The muon monitor is the only instrument that can monitor the neutrino beam direction in real time by measuring a profile of muons which are generated along with neutrinos. It is required to measure the intense muon beam precisely and stably in a high radiation area. Therefore, we use two independent systems for the muon monitor: an array of ionization chambers and another array of solid-state detectors. We developed the ionization chamber and performed beam tests with an electron beam at the Laboratory of Particle Beam Science in Kyoto University. We also had a long-term test in the NuMI beamline at Fermilab. Then we finalized the design of the ionization chamber and built it. We expect the ionization chambers as the muon monitor to monitor the beam direction with a precision of 0.2 mrad.

  3. kQ factors for ionization chamber dosimetry in clinical proton beams.

    Science.gov (United States)

    Vatnitsky, S M; Siebers, J V; Miller, D W

    1996-01-01

    We discuss a formalism for clinical proton beam dosimetry based on the use of ionization chamber absorbed dose-to-water calibration and beam quality correction factors. A quantity kQ, the beam quality correction factor, is defined which corrects the absorbed dose-to-water calibration factor ND,w in a reference beam of quality Q0 to that in a user's beam of quality Q1. This study of proton beam quality correction factors used 60Co (kQ gamma) and proton (kQp) reference beams. The kQ gamma factors were measured using combined water calorimetry and ionometry for PTW and Capintec-Farmer-type ionization chambers, and were computed from standard dosimetry protocols. Agreement between measured and calculated kQ gamma values for both chambers was found within 1.2% in the plateau region for a monoenergetic 250-MeV beam and within 1.8% at the spread-out Bragg peak for a 155-MeV range-modulated beam. Comparison of absorbed doses to water determined in the range-modulated 155-MeV beam was performed with the PTW chamber using three calibration methods: Ngas calibration (AAPM Report 16), ND,w,gamma calibration in a 60Co beam in conjunction with a kQ gamma factor, and ND,w,p calibration in a proton beam in conjunction with a kQp factor. Absorbed doses to water obtained with the three methods agreed within 2% when ionization chamber dosimetry data were analyzed using the proton W-value for air from the AAPM Report 16 and the ICRU 49 proton stopping powers. The use of the proton-calibrated reference ionization chamber, in conjunction with the beam quality correction factor kQp, significantly reduced the systematic uncertainty of the absorbed dose determination.

  4. Performance evaluation of multi sampling ionization chamber for heavy ion beams by comparison with GEANT4 simulation

    Science.gov (United States)

    Kanke, Yuki; Himac H093 Collaboration

    2014-09-01

    In high-energy heavy-ion accelerator facilities, multi sampling ionization chambers are often used for the identification of the atomic number Z by detecting the energy deposit in it. In the study at GSI, the picture of the escape of secondary electrons, δ rays, from the ionization chamber explains the experimental data of pulse-height resolution. If this picture is correct, the pulse-height resolution should depend on the effective area of the ionization chamber. The experiment have been performed at NIRS-HIMAC. The pulse-height resolutions of two ionization chambers with different effective area were compared by using a 400-MeV/u Ni beam and their fragments. The difference in the pulse-height resolutions was observed. By comparison with the GEANT4 simulation including the δ-rays emission, the performance of the ionization chamber have been evaluated.

  5. Improvements to parallel plate flow chambers to reduce reagent and cellular requirements

    Directory of Open Access Journals (Sweden)

    Larson Richard S

    2001-09-01

    Full Text Available Abstract Background The parallel plate flow chamber has become a mainstay for examination of leukocytes under physiologic flow conditions. Several design modifications have occurred over the years, yet a comparison of these different designs has not been performed. In addition, the reagent requirements of many designs prohibit the study of rare leukocyte populations and require large amounts of reagents. Results In this study, we evaluate modifications to a newer parallel plate flow chamber design in comparison to the original parallel plate flow chamber described by Lawrence et al. We show that modifications in the chamber size, internal tubing diameters, injection valves, and a recirculation design may dramatically reduce the cellular and reagent requirements without altering measurements. Conclusions These modifications are simple and easily implemented so that study of rare leukocyte subsets using scarce or expensive reagents can occur.

  6. Determination of ion recombination correction factors for a liquid ionization chamber in megavoltage photon beams

    Science.gov (United States)

    Choi, Sang Hyoun; Kim, Kum-Bae; Ji, Young Hoon; Kim, Chan Hyeong; Kim, Seonghoon; Huh, Hyun Do

    2015-05-01

    The aim of this study is to determine the ion recombination correction factor for a liquid ionization chamber in a high energy photon beam by using our experimental method. The ion recombination correction factors were determined by using our experimental method and were compared with theoretical and experimental methods proposed by using the theoretical method (Greening, Johansson) and the two-dose rate method in a cobalt beam and a high energy photon beam. In order to apply the liquid ionization chamber in a reference and small field dosimetry, we acquired the absorbed dose to water correction coefficient, the beam quality correction factor, and the influence quantities for the microLion chamber according to the TRS-398 protocol and applied the results to a high energy photon beam used in clinical fields. As a result, our experimental method for ion recombination in a cobalt beam agreed with the results from the heoretical method (Greening theory) better than it did with the results from the two-dose rate method. For high energy photon beams, the two-dose rate and our experimental methods were in good agreement, less than 2% deviation, while the theoretical general collection efficiency (Johansson et al.) deviated greatly from the experimental values. When we applied the factors for the absorbed dose to water measurement, the absorbed dose to water for the microLion chamber was in good agreement, within 1%, compared with the values for the PTW 30013 chamber in 6 and 10 MV Clinac iX and 6 and 15 MV Oncor impression. With these results, not only can the microLion ionization chamber be used to measure the absorbed dose to water in a reference condition, it can also be used to a the chamber for small, non-standard field dosimetry.

  7. Evaluation of linearity of response and angular dependence of an ionization chamber for dosimetry in computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Perini, Ana P.; Neves, Lucio P.; Xavier, Marcos; Caldas, Linda V.E., E-mail: mxavier@ipen.b, E-mail: lcaldas@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Khoury, Helen J., E-mail: khoury@ufpe.b [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear

    2011-07-01

    In this paper a pencil-type ionization chamber designed and manufactured at Instituto de Pesquisas Energeticas e Nucleares was evaluated for dosimetric applications in computed tomography beams. To evaluate the performance of this chamber two tests were undertaken: linearity of response and angular dependence. The results obtained in these tests showed good results, within the international recommendations. Moreover, this homemade ionization chamber is easy to manufacture, of low cost and efficient. (author)

  8. Response of Multi-strip Multi-gap Resistive Plate Chamber

    CERN Document Server

    Datta, Ushasi; Rahaman, A; Basu, P; Basu, J; Bemmerer, D; Boretzky, K; Elekes, Z; Kempe, M; Munzenberg, G; Simon, H; Sobiella, M; Stach, D; Wagner, A; Yakorev, D

    2015-01-01

    A prototype of Multi-strip Multi-gap Resistive Plate chamber (MMRPC) with active area 40 cm $\\times$ 20 cm has been developed at SINP, Kolkata. Detailed response of the developed detector was studied with the pulsed electron beam from ELBE at Helmholtz-Zentrum Dresden-Rossendorf. In this report the response of SINP developed MMRPC with different controlling parameters is described in details. The obtained time resolution ($\\sigma_t$) of the detector after slew correction was 91.5$ \\pm $3 ps. Position resolution measured along ($\\sigma_x$) and across ($\\sigma_y$) the strip was 2.8$\\pm$0.6 cm and 0.58 cm, respectively. The measured absolute efficiency of the detector for minimum ionizing particle like electron was 95.8$\\pm$1.3 $\\%$. Better timing resolution of the detector can be achieved by restricting the events to a single strip. The response of the detector was mainly in avalanche mode but a few percentage of streamer mode response was also observed. A comparison of the response of these two modes with trig...

  9. An ionization chamber for (n,z) reaction cross section measurements on gaseous targets

    CERN Document Server

    Machrafi, R; Son, D; Gledenov, Yu M; Salatskii, V I; Sedyshev, P V; Andrzejewski, J; Szalanski, P; Gledenov, Yu.M.

    2002-01-01

    An ionization chamber with gaseous samples has been designed. It has been tested on the beam of the pulsed reactor IBR-30 of FLNP, JINR-Dubna. The experiment has been carried out with resonance neutrons. The exposed gas volume serves as a target for neutron beam. We have compared the chamber to samples on substrates, the background component due to Li and B microimpurities in this case is totally absent. It has been tested also the recovery capability of the chamber after the reactor power pulse using the protons from the 3He(n,p)3H reaction, alpha-particles from a U-source and a pulsed precision generator. Moreover the energy resolution of the chamber with its equipment has been carried out.

  10. Study of Neutron-Induced Ionization in Helium and Argon Chamber Gases

    CERN Document Server

    Indurthy, D; Harris, D; Kopp, S; Proga, M; Zwaska, R M

    2004-01-01

    Ion chambers used to monitor the secondary hadron and tertiary muon beam in the NuMI neutrino beamline will be exposed to background particles, including low energy neutrons produced in the beam dump. To understand these backgrounds, we have studied Helium- and Argon-filled ionization chambers exposed to intense neutron fluxes from PuBe neutron sources ($E_n=1-10$ MeV). The sources emit about 10$^8$ neutrons per second. The number of ion pairs in the chamber gas volume per incident neutron is derived. While limited in precision because of a large gamma ray background from the PuBe sources, our results are consistent with the expectation that the neutrons interact purely elastically in the chamber gas.

  11. A free-air ionization chamber with a large aperture diaphragm

    Energy Technology Data Exchange (ETDEWEB)

    Takata, N., E-mail: n.takata@aist.go.j [Ionizing Radiation Section, NMIJ, AIST, Tsukuba, Ibaraki 305-8568 (Japan)

    2010-07-21

    Calculations of the electric field distributions in free-air ionization chambers reveal that the distortion of the charge collection volume is small even for wide X-ray beam passage if the diaphragm and the X-ray shielding box are kept at a potential equal to half that applied to the high-voltage electrode. Applying this potential to the diaphragm and the shielding box permits a larger aperture diaphragm to be used. This will allow a wider X-ray beam to enter the chamber, thus generating a larger signal. In addition, the distance between the diaphragm and the charge collection volume can be shortened to reduce the amount of X-ray attenuation. It is also possible to calibrate a dosimeter against a free-air ionization chamber that has a diaphragm whose aperture size is equal to the size of the dosimeter in an X-ray field that is collimated to the same size. This is important since free-air ionization chambers are not sensitive to X-rays that are incident at large angles, such as those scattered by the collimator, filters and air.

  12. SU-E-T-623: Polarity Effects for Small Volume Ionization Chambers in Cobalt-60 Beams

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Y; Bhatnagar, J; Huq, M Saiful [Department of Radiation Oncology, University of Pittsburgh Cancer Institute and UPMC Cancer Center, Pittsburgh, PA (United States)

    2015-06-15

    Purpose: To investigate the polarity effects for small volume ionization chambers in {sup 60}Co gamma-ray beams using the Leksell Gamma Knife Perfexion. Methods: Measurements were made for 7 small volume ionization chambers (a PTW 31016, an Exradin A14, 2 Capintec PR0-5P, and 3 Exradin A16) using a PTW UNIDOSwebline Universal Dosemeter and an ELEKTA solid water phantom with proper inserts. For each ion chamber, the temperature/pressure corrected electric charge readings were obtained for 16 voltage values (±50V, ±100V, ±200V, ±300V, ±400V, ±500V, ±600V, ±700V). For each voltage, a five-minute leakage charge reading and a series of 2-minute readings were continuously taken during irradiation until 5 stable signals (less than 0.05% variation) were obtained. The average of the 5 reading was then used for the calculation of the polarity corrections at the voltage and for generating the saturation curves. Results: The polarity effects are more pronounced at high or low voltages than at the medium voltages for all chambers studied. The voltage dependence of the 3 Exradin A16 chambers is similar in shape. The polarity corrections for the Exradin A16 chambers changes rapidly from about 1 at 500V to about 0.98 at 700V. The polarity corrections for the 7 ion chambers at 300V are in the range from 0.9925 (for the PTW31016) to 1.0035 (for an Exradin A16). Conclusion: The polarity corrections for certain micro-chambers are large even at normal operating voltage.

  13. Calculation of correction factors for ionization chamber measurements with small fields in low-density media.

    Science.gov (United States)

    Pisaturo, O; Pachoud, M; Bochud, F O; Moeckli, R

    2012-07-21

    The quantity of interest for high-energy photon beam therapy recommended by most dosimetric protocols is the absorbed dose to water. Thus, ionization chambers are calibrated in absorbed dose to water, which is the same quantity as what is calculated by most treatment planning systems (TPS). However, when measurements are performed in a low-density medium, the presence of the ionization chamber generates a perturbation at the level of the secondary particle range. Therefore, the measured quantity is close to the absorbed dose to a volume of water equivalent to the chamber volume. This quantity is not equivalent to the dose calculated by a TPS, which is the absorbed dose to an infinitesimally small volume of water. This phenomenon can lead to an overestimation of the absorbed dose measured with an ionization chamber of up to 40% in extreme cases. In this paper, we propose a method to calculate correction factors based on the Monte Carlo simulations. These correction factors are obtained by the ratio of the absorbed dose to water in a low-density medium □D(w,Q,V1)(low) averaged over a scoring volume V₁ for a geometry where V₁ is filled with the low-density medium and the absorbed dose to water □D(w,QV2)(low) averaged over a volume V₂ for a geometry where V₂ is filled with water. In the Monte Carlo simulations, □D(w,QV2)(low) is obtained by replacing the volume of the ionization chamber by an equivalent volume of water, according to the definition of the absorbed dose to water. The method is validated in two different configurations which allowed us to study the behavior of this correction factor as a function of depth in phantom, photon beam energy, phantom density and field size.

  14. Evaluation of dose distributions in gamma chamber using glass plate detector

    Directory of Open Access Journals (Sweden)

    Narayan Pradeep

    2008-01-01

    Full Text Available A commercial glass plate of thickness 1.75 mm has been utilized for evaluation of dose distributions inside the irradiation volume of gamma chamber using optical densitometry technique. The glass plate showed linear response in the dose range 0.10 Kilo Gray (kGy to 10 kGy of cobalt-60 gamma radiation with optical sensitivity 0.04 Optical Density (OD /kGy. The change in the optical density at each identified spatial dose matrix on the glass plate in relation to the position in the irradiation volume has been presented as dose distributions inside the gamma chamber. The optical density changes have been graphically plotted in the form of surface diagram of color washes for different percentage dose rate levels as isodose distributions in gamma chamber. The variation in dose distribution inside the gamma chamber unit, GC 900, BRIT India make, using this technique has been observed within ± 15%. This technique can be used for routine quality assurances and dose distribution validation of any gamma chamber during commissioning and source replacement. The application of commercial glass plate for dose mapping in gamma chambers has been found very promising due to its wider dose linearity, quick measurement, and lesser expertise requirement in application of the technique.

  15. Towards reference dosimetry for the MR-linac: magnetic field correction of the ionization chamber reading.

    Science.gov (United States)

    Smit, K; van Asselen, B; Kok, J G M; Aalbers, A H L; Lagendijk, J J W; Raaymakers, B W

    2013-09-07

    In the UMC Utrecht a prototype MR-linac has been installed. The system consists of a 6 MV Elekta (Crawley, UK) linear accelerator and a 1.5 T Philips (Best, The Netherlands) Achieva MRI system. This paper investigates the feasibility to correct the ionization chamber reading for the magnetic field within the dosimetry calibration method described by Almond et al (1999 Med. Phys. 26 1847-70). Firstly, the feasibility of using an ionization chamber in an MR-linac was assessed by investigating possible influences of the magnetic field on NE2571 Farmer-type ionization chamber characteristics: linearity, repeatability, orientation in the magnetic field; and AAPM TG51 correction factor for voltage polarity and ion recombination. We found that these AAPM correction factors for the NE2571 chamber were not influenced by the magnetic field. Secondly, the influence of the permanent 1.5 T magnetic field on the NE2571 chamber reading was quantified. The reading is influenced by the magnetic field; therefore, a correction factor has been added. For the standardized setup used in this paper, the NE2571 chamber reading increases by 4.9% (± 0.2%) due to the transverse 1.5 T magnetic field. Dosimetry measurements in an MR-linac are feasible, if a setup-specific magnetic field correction factor (P1.5 T) for the charge reading is introduced. For the setup investigated in this paper, the P1.5 T has a value of 0.953.

  16. The wall correction factor for a spherical ionization chamber used in brachytherapy source calibration

    Energy Technology Data Exchange (ETDEWEB)

    Piermattei, A [Istituto di Fisica, Universita Cattolica S Cuore, Rome (Italy); Azario, L [Istituto di Fisica, Universita Cattolica S Cuore, Rome (Italy); Fidanzio, A [Istituto di Fisica, Universita Cattolica S Cuore, Rome (Italy); Viola, P [Istituto di Fisica, Universita Cattolica S Cuore, Rome (Italy); Dell' Omo, C [Istituto di Fisica, Universita Cattolica S Cuore, Rome (Italy); Iadanza, L [Centro di Riferimento Oncologico della Basilicata-Rionero in Vulture, Pz (Italy); Fusco, V [Centro di Riferimento Oncologico della Basilicata-Rionero in Vulture, Pz (Italy); Lagares, J I [Universidad de Sevilla, Facultad de Medicina, Dpto Fisiologia Medica y Biofisica, Sevilla (Spain); Capote, R [Universidad de Sevilla, Facultad de Medicina, Dpto Fisiologia Medica y Biofisica, Sevilla (Spain)

    2003-12-21

    The effect of wall chamber attenuation and scattering is one of the most important corrections that must be determined when the linear interpolation method between two calibration factors of an ionization chamber is used. For spherical ionization chambers the corresponding correction factors A{sub w} have to be determined by a non-linear trend of the response as a function of the wall thickness. The Monte Carlo and experimental data here reported show that the A{sub w} factors obtained for an Exradin A4 chamber, used in the brachytherapy source calibration, in terms of reference air kerma rate, are up to 1.2% greater than the values obtained by the linear extrapolation method for the studied beam qualities. Using the A{sub w} factors derived from Monte Carlo calculations, the accuracy of the calibration factor N{sub K,Ir} for the Exradin A4, obtained by the interpolation between two calibration factors, improves about 0.6%. The discrepancy between the new calculated factor and that obtained using the complete calibration curve of the ion-chamber and the {sup 192}Ir spectrum is only 0.1%.

  17. A pixel ionization chamber used as beam monitor at the Institut Curie—Centre de Protontherapie de Orsay (CPO)

    Science.gov (United States)

    La Rosa, A.; Garella, M. A.; Bourhaleb, F.; Cirio, R.; Donetti, M.; Giordanengo, S.; Givehchi, N.; Marchetto, F.; Martin, F.; Meyroneinc, S.; Peroni, C.; Pittà, G.

    2006-09-01

    The Dipartimento di Fisica Sperimentale and the Istituto Nazionale di Fisica Nucleare (INFN), Torino, in collaboration with the Institut Curie—Centre de Protontherapie de Orsay (CPO), have developed and built a pixel parallel plate ionization chamber to be used as monitor for the proton therapy beam line at the Institut Curie—CPO (Orsay, France). The sensitive area of the detector is (160×160) mm 2, with the anode segmented in 1024 square pixels arranged in a 32×32 matrix; the area of each pixel is (5×5) mm 2. The detector has been placed on the beam line just upstream of the last collimator to monitor the beam shape and to measure the stability and reproducibility of the delivery system. In this paper, we present a detailed description of the detector and the results of a set of preliminary tests.

  18. A pixel ionization chamber used as beam monitor at the Institut Curie-Centre de Protontherapie de Orsay (CPO)

    Energy Technology Data Exchange (ETDEWEB)

    La Rosa, A. [Dipartimento di Fisica Sperimentale, Universita di Torino. Via P. Giuria 1, Torino 10125 (Italy) and INFN. Via P. Giuria 1, Turin 10125 (Italy)]. E-mail: larosa@to.infn.it; Garella, M.A. [INFN. Via P. Giuria 1, Turin 10125 (Italy); Bourhaleb, F. [Fondazione TERA. Via Puccini 11, Novara 28100 (Italy); Cirio, R. [INFN. Via P. Giuria 1, Turin 10125 (Italy); Donetti, M. [INFN. Via P. Giuria 1, Turin 10125 (Italy); Fondazione CNAO. Via Caminadella 16, Milan 20123 (Italy); Giordanengo, S. [INFN. Via P. Giuria 1, Turin 10125 (Italy); Givehchi, N. [Dipartimento di Fisica Sperimentale, Universita di Torino. Via P. Giuria 1, Turin 10125 (Italy); INFN. Via P. Giuria 1, Turin 10125 (Italy); Marchetto, F. [INFN. Via P. Giuria 1, Turin 10125 (Italy); Martin, F. [Institut Curie-Centre de Protontherapie de Orsay. Bat. 101 Campus Universitaire, Orsay Cedex 91898 (France); Meyroneinc, S. [Institut Curie-Centre de Protontherapie de Orsay. Bat. 101 Campus Universitaire, Orsay Cedex 91898 (France); Peroni, C. [Dipartimento di Fisica Sperimentale, Universita di Torino. Via P. Giuria 1, Turin 10125 (Italy); INFN. Via P. Giuria 1, Turin 10125 (Italy); Pitta, G. [Fondazione TERA. Via Puccini 11, Novara 28100 (Italy)

    2006-09-15

    The Dipartimento di Fisica Sperimentale and the Istituto Nazionale di Fisica Nucleare (INFN), Torino, in collaboration with the Institut Curie-Centre de Protontherapie de Orsay (CPO), have developed and built a pixel parallel plate ionization chamber to be used as monitor for the proton therapy beam line at the Institut Curie-CPO (Orsay, France). The sensitive area of the detector is (160x160) mm{sup 2}, with the anode segmented in 1024 square pixels arranged in a 32x32 matrix; the area of each pixel is (5x5) mm{sup 2}. The detector has been placed on the beam line just upstream of the last collimator to monitor the beam shape and to measure the stability and reproducibility of the delivery system. In this paper, we present a detailed description of the detector and the results of a set of preliminary tests.

  19. Beam-loss monitoring system with free-air ionization chambers

    Science.gov (United States)

    Nakagawa, H.; Shibata, S.; Hiramatsu, S.; Uchino, K.; Takashima, T.

    1980-08-01

    A monitoring system for proton beam losses was installed in the proton synchrotron at the National Laboratory for High Energy Physics in Japan (KEK). The system consists of 56 air ionization chambers (AIC) for radiation detectors, 56 integrators, 56 variable gain amplifiers, two multiplexers, a computer interface circuit, a manual controller and a high tension power supply. The characteristics of the AIC, time resolution, radiation measurement upper limit saturation, kinetic energy dependence of the sensitivity, chamber activation effect, the beam loss detection system and the results of observations with the monitoring system are described.

  20. Set-Up on the Basis of Multiwire Proportional and Ionization Chambers for Radioactive Beam Experiments

    CERN Document Server

    Astabatyan, R A; Kavalov, R L; Kugler, A; Kuznetsov, I V; Kushniruk, V F; Lobastov, S P; Lukyanov, S M; Markaryan, E R; Maslov, V A; Mikhailov, L; Penionzhkevich, Yu E; Poroshin, N O; Skobelev, N K; Smirnov, V I; Sobolev, Yu G; Ugryumov, V Yu

    2002-01-01

    A large-aperture set-up designed for nuclear physics experiments on beams of radioactive nuclei is described. The set-up includes Multiwire Proportional Chamber (MWPC) for measuring the beam profile, MWPC for measuring reaction product angular distributions, a CsI(Tl)-crystal detector and a longitudinal drift ionization chamber for identifying scattered particles and measuring their energy. The results of tests of coordinate MWPCs, particle identification on photon and ion beams, and preliminary measurements of the elastic scattering and the charge exchange reaction of 170 MeV ^{6}He on a CH_{2} target are presented.

  1. Total diesel exhaust particulate length measurements using a modified household smoke alarm ionization chamber.

    Science.gov (United States)

    Vojtisek-Lom, Michal

    2011-02-01

    To evaluate the effectiveness of various means to combat the negative health effects of ultrafine particles emitted by internal combustion engines, a reliable, low-cost instrument for dynamic measurements of the exhaust emissions of ultrafine particulate matter (PM) is needed. In this study, an ordinary ionization-type building smoke detector was modified to serve as a measuring ionization chamber and utilized for dynamic measurements of PM emissions from diesel engines. When used with diluted exhaust, the readings show an excellent correlation with total particulate length. The instrument worked well with raw and diluted exhaust and with varying emission levels and is well suitable for on-board use.

  2. Studies of gaseous multiplication coefficient in isobutane using a resistive plate chamber

    Energy Technology Data Exchange (ETDEWEB)

    Goncalves, Josemary A.C.; Botelho, Suzana; Tobias, Carmen C.B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Pontificia Univ. Catolica de Sao Paulo (PUC/SP), SP (Brazil); Lima, Iara B.; Vivaldini, Tulio C. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Ridenti, Marco A.; Pascholati, Paulo R. [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Fisica. Lab. do Acelerador Linear; Fonte, Paulo; Mangiarotti, Alessio [Universidade de Coimbra (Portugal). Dept. de fisica. Lab. de Instrumentacao e Fisica Experimental de Particulas

    2009-07-01

    Full text: Due to the increasing demands concerning High Energy Physics, Nuclear Medicine and other Nuclear Applications about gaseous detectors operating in high electric fields, many efforts have been done about the choice of filling gases that fulfill these requirements. In this context, the electron transport parameters in gases, as the gaseous multiplication coefficient, play an important role not only for detector design but also for simulation and modeling of discharges, allowing the validation of electron impact cross-sections. In the present work the preliminary measurements of gaseous multiplication coefficient, as function of the reduced electric field (from 36V/cm.Torr until 93V/cm.Torr), for isobutane are presented. Among several filling gases, isobutane is widely used in resistive plate chambers RPCs, and other gaseous detectors, due to its timing properties. Although its characteristics, there is a lack of swarm parameters data in literature for this gas, mainly at high electric fields. The experimental method used is based on the Pulsed Townsend technique, which follows from Townsend equation solution for a uniform electric field. Considering the ratio between the current (I), measured in avalanche mode, and the primary ionization current (I{sub 0}), the effective multiplication coefficient can be determined, since alpha = d{sup -1}ln(I/I{sub 0}), where d is the gap between the electrodes. In our configuration, the experimental setup consists of two parallel plates enclosure in a stainless steel chamber at gas flow regime. The anode, is made of a high resistivity (2.10{sup 12}{omega}.cm) glass (3mm thick and 14mm diameter), while the cathode is of aluminium (40mm diameter). Primary electrons are produced by irradiating the cathode with a nitrogen laser (LTB MNL200-LD) and are accelerated toward the anode by means of a high voltage power supply (Bertan 225-30). In order to validate the technique and to analyze effects of non-uniformity, results for

  3. Characterization of Tandem systems of commercial ionization chambers for radiation dosimetry (radiotherapy level)

    CERN Document Server

    Galhardo, E P

    1998-01-01

    The use of X rays for radiotherapy purposes is of great importance for Medicine, and it is necessary to control periodically the performance of the ionization chambers and the radiation beams in order to obtain the best results. The verification of the beam characteristics is made by using standard dosimetry procedures which include the determination of the half-value layers and the exposure rates or the absorbed dose rates in air. Several Tandem systems were set up and tested, using commercial ionization chambers in the energy interval from 14 up to 130 KeV at the Instrumentation Calibration Laboratory of IPEN and at other three institutions, in substitution to the routine conventional procedure of determination of half-value layers using absorbers. The obtained results show the usefulness of these Tandem system for the routine dosimetric procedures of radiotherapy X radiation beams.

  4. Neutron and gamma detector using an ionization chamber with an integrated body and moderator

    Science.gov (United States)

    Ianakiev, Kiril D.; Swinhoe, Martyn T.; Lestone, John Paul

    2006-07-18

    A detector for detecting neutrons and gamma radiation includes a cathode that defines an interior surface and an interior volume. A conductive neutron-capturing layer is disposed on the interior surface of the cathode and a plastic housing surrounds the cathode. A plastic lid is attached to the housing and encloses the interior volume of the cathode forming an ionization chamber, into the center of which an anode extends from the plastic lid. A working gas is disposed within the ionization chamber and a high biasing voltage is connected to the cathode. Processing electronics are coupled to the anode and process current pulses which are converted into Gaussian pulses, which are either counted as neutrons or integrated as gammas, in response to whether pulse amplitude crosses a neutron threshold. The detector according to the invention may be readily fabricated into single or multilayer detector arrays.

  5. Source self-attenuation in ionization chamber measurements of (57)Co solutions.

    Science.gov (United States)

    Cessna, Jeffrey T; Golas, Daniel B; Bergeron, Denis E

    2016-03-01

    Source self-attenuation for solutions of (57)Co of varying density and carrier concentration was measured in nine re-entrant ionization chambers maintained at NIST. The magnitude of the attenuation must be investigated to determine whether a correction is necessary in the determination of the activity of a source that differs in composition from the source used to calibrate the ionization chamber. At our institute, corrections are currently made in the measurement of (144)Ce, (109)Cd, (67)Ga, (195)Au, (166)Ho, (177)Lu, and (153)Sm. This work presents the methods used as recently applied to (57)Co. A range of corrections up to 1% were calculated for dilute to concentrated HCl at routinely used carrier concentrations.

  6. Measurements and Simulations of Ionization Chamber Signals in Mixed Radiation Fields for the LHC BLM System

    CERN Document Server

    Dehning, B; Ferioli, G; Holzer, EB; Stockner, M

    2006-01-01

    The LHC beam loss monitoring (BLM) system must prevent the super conducting magnets from quenching and protect the machine components from damage. The main monitor type is an ionization chamber. About 4000 of them will be installed around the ring. The lost beam particles initiate hadronic showers through the magnets, which are measured by the monitors installed outside of the cryostat around each quadrupole magnet. They probe the far transverse tail of the hadronic shower. The specification for the BLM system includes a factor of two absolute precision on the prediction of the quench levels. To reach this accuracy a number of simulations are being combined to calibrate the monitor signals. To validate the monitor calibration the simulations are compared with test measurements. This paper will focus on the simulated prediction of the development of the hadronic shower tails and the signal response of ionization chambers to various particle types and energies. Test measurements have been performed at CERN and ...

  7. Hard disk drive based microsecond x-ray chopper for characterization of ionization chambers and photodiodes

    Science.gov (United States)

    Müller, O.; Lützenkirchen-Hecht, D.; Frahm, R.

    2015-03-01

    A fast X-ray chopper capable of producing ms long X-ray pulses with a typical rise time of few μs was realized. It is ideally suited to investigate the temporal response of X-ray detectors with response times of the order of μs to ms, in particular, any kind of ionization chambers and large area photo diodes. The drive mechanism consists of a brushless DC motor and driver electronics from a common hard disk drive, keeping the cost at an absolute minimum. Due to its simple construction and small dimensions, this chopper operates at home lab based X-ray tubes and synchrotron radiation sources as well. The dynamics of the most important detectors used in time resolved X-ray absorption spectroscopy, namely, ionization chambers and Passivated Implanted Planar Silicon photodiodes, were investigated in detail. The results emphasize the applicability of this X-ray chopper.

  8. Using a tandem ionization chamber for quality control of X-ray beams

    Energy Technology Data Exchange (ETDEWEB)

    Yoshizumi, Maira T.; Caldas, Linda V.E., E-mail: mairaty@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    X-ray beam qualities are defined by both the mean energies and by the half-value layers (HVL). Many international protocols use the half-value layer and the beam voltage to characterize the X-ray beam quality. A quality control program for X-ray equipment includes the constancy check of beam qualities, i.e., the periodical verification of the half-value layer, which can be a time consumable procedure. A tandem ionization chamber, developed at Instituto de Pesquisas Energeticas e Nucleares, was used to determine the HVL and its constancy for five radiotherapy standard beam qualities. This ionization chamber is composed by two sensitive volumes with inner electrodes made of different materials: aluminum and graphite. The beam quality constancy check test was performed during two months and the maximum variation obtained was 1.24% for the radiation beam quality T-10. This result is very satisfactory according to national recommendations. (author)

  9. PTRAC File Utilization for Calculation of Free-Air Ionization Chamber Correction Factors by MCNPX

    Science.gov (United States)

    Šolc, Jaroslav; Sochor, Vladimír

    2014-06-01

    A free-air ionization chamber is used as a standard of photon air-kerma. Several correction factors are applied to the air-kerma value. Correction factors for electron loss (kloss) and for additional ionization current caused by photon scatter (ksc), photon fluorescence (kfl), photon transmission through diaphragm edge (kdtr), and photon scatter from the surface of the diaphragm aperture (kdsc) were determined by the MCNPX code utilizing information stored in Particle Track (PTRAC) output files. Individual steps of the procedure are described and the calculated values of the correction factors are presented. The values are in agreement with the correction factors published in a literature for similar free-air chambers.

  10. Hard disk drive based microsecond x-ray chopper for characterization of ionization chambers and photodiodes

    Energy Technology Data Exchange (ETDEWEB)

    Müller, O., E-mail: o.mueller@uni-wuppertal.de; Lützenkirchen-Hecht, D.; Frahm, R. [Bergische Universität Wuppertal, Gaußstraße 20, Wuppertal 42119 (Germany)

    2015-03-15

    A fast X-ray chopper capable of producing ms long X-ray pulses with a typical rise time of few μs was realized. It is ideally suited to investigate the temporal response of X-ray detectors with response times of the order of μs to ms, in particular, any kind of ionization chambers and large area photo diodes. The drive mechanism consists of a brushless DC motor and driver electronics from a common hard disk drive, keeping the cost at an absolute minimum. Due to its simple construction and small dimensions, this chopper operates at home lab based X-ray tubes and synchrotron radiation sources as well. The dynamics of the most important detectors used in time resolved X-ray absorption spectroscopy, namely, ionization chambers and Passivated Implanted Planar Silicon photodiodes, were investigated in detail. The results emphasize the applicability of this X-ray chopper.

  11. Recent experimental results and developments on the resistive plate chambers for the CMS experiment

    CERN Document Server

    Altieri, S; Bruno, G; Guida, R; Merlo, M; Ratti, S P; Riccardi, C; Torre, P; Vitulo, P; Abbrescia, M; Colaleo, A; Iaselli, Giuseppe; Loddo, F; Maggi, M; Marangelli, B; Natali, S; Nuzzo, S; Pugliese, G; Ranieri, A; Romano, F

    2001-01-01

    Resistive plate chambers (RPC) have been chosen as dedicated trigger detectors for the CMS experiment at the LHC. The expected severe operating conditions have required an intense research and development activity on these detectors over the past years. Experimental results on overall performance of large chambers, rate capability, ageing and photon sensitivity are reviewed. In all of these tests the detector has proven to achieve good enough performance for successful use at the LHC. (6 refs).

  12. Some specific features of ionization chamber calibrations in linac x-ray beams at the LNE-LNHB.

    Science.gov (United States)

    Delaunay, F; Ostrowsky, A

    2007-05-07

    The purpose of this note is to give some details about the modus operandi employed today to calibrate ionization chambers in radiotherapy linac photon beams at the Laboratoire National Henri Becquerel (LNE-LNHB). Some specific features are described: first the equipment (including the external monitoring ionization chambers), second the calculations of the profile or radial non-uniformity correction factors (up to 0.5% effect for commonly used ionization chambers) and finally the calculations to get the calibration coefficients for customer beam qualities.

  13. Detection of scintillation light in coincidence with ionizing tracks in a liquid argon time projection chamber

    CERN Document Server

    Cennini, P; Rubbia, Carlo; Sergiampietri, F; Bueno, A G; Campanelli, M; Goudsmit, P; Rubbia, André; Periale, L; Suzuki, S; Chen, C; Chen, Y; He, K; Huang, X; Li, Z; Lu, F; Ma, J; Xu, G; Xu, Z; Zhang, C; Zhang, Q; Zheng, S; Cavanna, F; Mazza, D; Piano Mortari, G; Petrera, S; Rossi, C; Mannocchi, G; Picchi, P; Arneodo, F; De Mitri, I; Palamara, O; Cavalli, D; Ferrari, A; Sala, P R; Borio di Tigliole, A A; Cesana, A; Terrani, M; Zavattari, C; Baibusinov, S; Bettini, A; Carpanese, C; Centro, Sandro; Favaretto, D; Pascoli, D; Pepato, Adriano; Pietropaolo, F; Ventura, Sandro; Benetti, P; Calligarich, E; Campo, S; Coco, S; Dolfini, R; Ghedi, B; Gigli-Berzolari, A; Mauri, F; Mazzone, L; Montanari, C; Piazzoli, A; Rappoldi, A; Raselli, G L; Rebuzzi, D; Rossella, M; Scannicchio, D A; Torre, P; Vignoli, C; Cline, D; Otwinowski, S; Wang, H; Woo, J

    1999-01-01

    A system to detect light from liquid argon scintillation has been implemented in a small, ICARUS-like, liquid argon time projection chamber. The system, which uses a VUV-sensitive photomultiplier to collect the light, has recorded many ionizing tracks from cosmic-rays in coincidence with scintillation signals. Our measurements demonstrate that scintillation light detection can provide an effective method for absolute time measurement of events and eventually a useful trigger signal. (19 refs).

  14. SU-E-T-525: Ionization Chamber Perturbation in Flattening Filter Free Beams

    Energy Technology Data Exchange (ETDEWEB)

    Czarnecki, D; Voigts-Rhetz, P von [Technische Hochschule Mittelhessen - University of Applied Sciences, Giessen, DE (Germany); Zink, K [Technische Hochschule Mittelhessen - University of Applied Sciences, Giessen, DE (Germany); Germany and Department of Radiotherapy and Radiooncology, University Medical Center Giessen-Marburg, Marburg, DE (Germany)

    2015-06-15

    Purpose: Changing the characteristic of a photon beam by mechanically removing the flattening filter may impact the dose response of ionization chambers. Thus, perturbation factors of cylindrical ionization chambers in conventional and flattening filter free photon beams were calculated by Monte Carlo simulations. Methods: The EGSnrc/BEAMnrc code system was used for all Monte Carlo calculations. BEAMnrc models of nine different linear accelerators with and without flattening filter were used to create realistic photon sources. Monte Carlo based calculations to determine the fluence perturbations due to the presens of the chambers components, the different material of the sensitive volume (air instead of water) as well as the volume effect were performed by the user code egs-chamber. Results: Stem, central electrode, wall, density and volume perturbation factors for linear accelerators with and without flattening filter were calculated as a function of the beam quality specifier TPR{sub 20/10}. A bias between the perturbation factors as a function of TPR{sub 20/10} for flattening filter free beams and conventional linear accelerators could not be observed for the perturbations caused by the components of the ionization chamber and the sensitive volume. Conclusion: The results indicate that the well-known small bias between the beam quality correction factor as a function of TPR20/10 for the flattening filter free and conventional linear accelerators is not caused by the geometry of the detector but rather by the material of the sensitive volume. This suggest that the bias for flattening filter free photon fields is only caused by the different material of the sensitive volume (air instead of water)

  15. Dosimetric characteristics of the novel 2D ionization chamber array OCTAVIUS Detector 1500

    Energy Technology Data Exchange (ETDEWEB)

    Stelljes, T. S., E-mail: tenzin.s.stelljes@uni-oldenburg.de; Looe, H. K.; Chofor, N.; Poppe, B. [Clinic for Radiation Therapy, Pius-Hospital, Oldenburg 26121, Germany and WG Medical Radiation Physics, Carl von Ossietzky University, Oldenburg 26129 (Germany); Harmeyer, A.; Reuter, J. [WG Medical Radiation Physics, Carl von Ossietzky University, Oldenburg 26129 (Germany); Harder, D. [Prof. em., Medical Physics and Biophysics, Georg August University, Göttingen 37073 (Germany)

    2015-04-15

    Purpose: The dosimetric properties of the OCTAVIUS Detector 1500 (OD1500) ionization chamber array (PTW-Freiburg, Freiburg, Germany) have been investigated. A comparative study was carried out with the OCTAVIUS Detector 729 and OCTAVIUS Detector 1000 SRS arrays. Methods: The OD1500 array is an air vented ionization chamber array with 1405 detectors in a 27 × 27 cm{sup 2} measurement area arranged in a checkerboard pattern with a chamber-to-chamber distance of 10 mm in each row. A sampling step width of 5 mm can be achieved by merging two measurements shifted by 5 mm, thus fulfilling the Nyquist theorem for intensity modulated dose distributions. The stability, linearity, and dose per pulse dependence were investigated using a Semiflex 31013 chamber (PTW-Freiburg, Freiburg, Germany) as a reference detector. The effective depth of measurement was determined by measuring TPR curves with the array and a Roos chamber type 31004 (PTW-Freiburg, Freiburg, Germany). Comparative output factor measurements were performed with the array, the Semiflex 31010 ionization chamber and the Diode 60012 (both PTW-Freiburg, Freiburg, Germany). The energy dependence of the OD1500 was measured by comparing the array’s readings to those of a Semiflex 31010 ionization chamber for varying mean photon energies at the depth of measurement, applying to the Semiflex chamber readings the correction factor k{sub NR} for nonreference conditions. The Gaussian lateral dose response function of a single array detector was determined by searching the convolution kernel suitable to convert the slit beam profiles measured with a Diode 60012 into those measured with the array’s central chamber. An intensity modulated dose distribution measured with the array was verified by comparing a OD1500 measurement to TPS calculations and film measurements. Results: The stability and interchamber sensitivity variation of the OD1500 array were within ±0.2% and ±0.58%, respectively. Dose linearity was within 1

  16. Dosimetric characteristics of the novel 2D ionization chamber array OCTAVIUS Detector 1500.

    Science.gov (United States)

    Stelljes, T S; Harmeyer, A; Reuter, J; Looe, H K; Chofor, N; Harder, D; Poppe, B

    2015-04-01

    The dosimetric properties of the OCTAVIUS Detector 1500 (OD1500) ionization chamber array (PTW-Freiburg, Freiburg, Germany) have been investigated. A comparative study was carried out with the OCTAVIUS Detector 729 and OCTAVIUS Detector 1000 SRS arrays. The OD1500 array is an air vented ionization chamber array with 1405 detectors in a 27 × 27 cm(2) measurement area arranged in a checkerboard pattern with a chamber-to-chamber distance of 10 mm in each row. A sampling step width of 5 mm can be achieved by merging two measurements shifted by 5 mm, thus fulfilling the Nyquist theorem for intensity modulated dose distributions. The stability, linearity, and dose per pulse dependence were investigated using a Semiflex 31013 chamber (PTW-Freiburg, Freiburg, Germany) as a reference detector. The effective depth of measurement was determined by measuring TPR curves with the array and a Roos chamber type 31004 (PTW-Freiburg, Freiburg, Germany). Comparative output factor measurements were performed with the array, the Semiflex 31010 ionization chamber and the Diode 60012 (both PTW-Freiburg, Freiburg, Germany). The energy dependence of the OD1500 was measured by comparing the array's readings to those of a Semiflex 31010 ionization chamber for varying mean photon energies at the depth of measurement, applying to the Semiflex chamber readings the correction factor kNR for nonreference conditions. The Gaussian lateral dose response function of a single array detector was determined by searching the convolution kernel suitable to convert the slit beam profiles measured with a Diode 60012 into those measured with the array's central chamber. An intensity modulated dose distribution measured with the array was verified by comparing a OD1500 measurement to TPS calculations and film measurements. The stability and interchamber sensitivity variation of the OD1500 array were within ±0.2% and ±0.58%, respectively. Dose linearity was within 1% over the range from 5 to 1000 MU. The

  17. Rapid measurement of 210Po in seafood with large area grid ionization chamber α spectrometry

    Institute of Scientific and Technical Information of China (English)

    Li Yucheng; Yin Liangliang; Chen Fei; Shao Xianzhang; Shen Baoming; Kong Xiangyin; Ji Yanqin

    2015-01-01

    Objective To develop a rapid and reliable method for determination of 210Po using large-area grid ionization chamber α spectrometry.Methods Samples were digested using a microwave digestion system.After preparation of sample source,the concentration of 210Po in clam was detected by large-area grid ionization chamber (φ 25 cm).209Po tracer was used to obtain the recovery.Results Large-area grid ionization chamber could achieve better counting and α spectrum resolution when the optimized thickness was 250 μg/cm2.By spiking 209Po tracer in clam,the minimum detectable activity was 9.870 × 10 4 Bq and the recovery of 210Po was 98%.Conclusions Compared with the traditional method,the developed method can avoid separation process,using less quantity of sample (0.2-0.5 g dry) and simplify the measurement process.This method may be has broad application prospects.

  18. Development and characterization of a new graphite ionization chamber for dosimetry of {sup 60}Co beams

    Energy Technology Data Exchange (ETDEWEB)

    Neves, Lucio Pereira; Perini, Ana Paula; Santos, William de Souza; Caldas, Linda V.E., E-mail: lpneves@ipen.br, E-mail: aperini@ipen.br, E-mail: wssantos@ipen.br, E-mail: lcaldas@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2014-07-01

    Ionization chambers are the most employed dosimeters for precise measurements, as those required in radiotherapy. In this work, a new graphite ionization chamber was developed and characterized in order to compose a primary standard system for the beam dosimetry of the {sup 60}Co sources. This dosimeter is a cylindrical type ionization chamber, with walls and collecting electrode made of high-purity graphite, and the insulators and stem made of Teflon®. The walls are 3.0 mm thick, and it has a sensitive volume of 1.40 cm{sup 3}. The characterization was divided in two steps: experimental and Monte Carlo evaluations. This new dosimeter was evaluated in relation to its saturation curve, ion collection efficiency, polarity effect, short- and medium-term stabilities, leakage current, stabilization time, linearity of response and angular dependence. All results presented values within the established limits. The second part of the characterization process involved the determination of the correction factors, obtained by Monte Carlo simulations. Comparing these correction factors values with those from other primary standard laboratories, the highest differences were those for the wall and stem correction factors. The air-kerma rate of the {sup 60}Co source was determined with this new dosimeter and with the IPEN standard system, presenting a difference of 1.7%. These results indicate that this new dosimeter may be used as a primary standard system for {sup 60}Co gamma beams. (author)

  19. Air-kerma determination using a variable-volume cavity ionization chamber standard.

    Science.gov (United States)

    Burns, D T; Kessler, C; Roger, P

    2007-12-01

    A graphite-walled cavity ionization chamber of modular design and variable volume has been used to determine the air-kerma rate in the reference 60Co field at the BIPM. The chamber can be configured in five sizes. High-accuracy mechanical measurements of the volume of the air cavity were made for each configuration using a co-ordinate measuring machine. Ionization current measurements were made for each configuration and corrected for the effects of ion recombination and diffusion, stem scatter and chamber orientation. Monte Carlo calculations of cavity dose were made to evaluate the correction factors kwall and kan. A reproducibility of the ionization current per mass of 1.5 parts in 10(4) was achieved on the repeated assembly of each configuration. The results show an air-kerma rate determination that increases with volume, the total change being around 8 parts in 10(4). When analysed differentially, the air-kerma rate relative to the BIPM standard is Kdiff/KBIPM = 1.0026(6). A detailed uncertainty budget is presented. Possible reasons for the observed behaviour are discussed that might have consequences for all existing standards for air-kerma.

  20. Saturation current and collection efficiency for ionization chambers in pulsed beams.

    Science.gov (United States)

    DeBlois, F; Zankowski, C; Podgorsak, E B

    2000-05-01

    Saturation currents and collection efficiencies in ionization chambers exposed to pulsed megavoltage photon and electron beams are determined assuming a linear relationship between 1/I and 1/V in the extreme near-saturation region, with I and V the chamber current and polarizing voltage, respectively. Careful measurements of chamber current against polarizing voltage in the extreme near-saturation region reveal a current rising faster than that predicted by the linear relationship. This excess current combined with conventional "two-voltage" technique for determination of collection efficiency may result in an up to 0.7% overestimate of the saturation current for standard radiation field sizes of 10X10 cm2. The measured excess current is attributed to charge multiplication in the chamber air volume and to radiation-induced conductivity in the stem of the chamber (stem effect). These effects may be accounted for by an exponential term used in conjunction with Boag's equation for collection efficiency in pulsed beams. The semiempirical model follows the experimental data well and accounts for both the charge recombination as well as for the charge multiplication effects and the chamber stem effect.

  1. Comments on 'Ionization chamber volume determination and quality assurance using micro-CT imaging'.

    Science.gov (United States)

    Ross, C K

    2009-03-21

    The authors of a recent paper (McNiven et al 2008 Phys. Med. Biol. 53 5029-43) measured the volume of a particular type of a small ionization chamber using CT images. Using four Exradin A1SL chambers, they find that the volume measured using CT imaging is, on average, 4.3% larger than the value derived from the chamber calibration coefficient. Although they point out that the effective chamber volume is defined by electric field lines between the collector and the chamber body, they do not estimate how the mechanical volume might differ from the effective volume. We have used a commercial software package to calculate the electric field in the cavity and we show that the field lines define a volume that is about 11% smaller than the mechanical volume. We also show that the effective volume is very sensitive to small changes in the chamber geometry near the base of the collector. We conclude that simply determining the mechanical volume without careful consideration of the electric field lines within the cavity is not a useful dosimetric technique.

  2. Test and characterization of multigap resistive plate chambers for the EEE project

    CERN Document Server

    Bossini, E

    2016-01-01

    The Extreme Energy Events project is based on the deployment of cosmic-ray telescopes in Italian high schools with the active contribution of students and teachers. Each telescope is made by three Multigap Resistive Plate Chambers readout by strips. With around 50 telescopes already built and others under construction, specific systems to test and characterize the chambers are needed. In this article I will present a flexible and software-configurable solution to perform chamber efficiency studies with a set of scintillators and hardware to automatically scan detector strips to identify electrical issues. Both systems can provide accurate information but at the same time they can be easily operated by students.

  3. Test and characterization of multigap resistive plate chambers for the EEE project

    Science.gov (United States)

    Bossini, E.; EEE Collaboration

    2016-03-01

    The Extreme Energy Events project is based on the deployment of cosmic-ray telescopes in Italian high schools with the active contribution of students and teachers. Each telescope is made by three Multigap Resistive Plate Chambers readout by strips. With around 50 telescopes already built and others under construction, specific systems to test and characterize the chambers are needed. In this article I will present a flexible and software-configurable solution to perform chamber efficiency studies with a set of scintillators and hardware to automatically scan detector strips to identify electrical issues. Both systems can provide accurate information but at the same time they can be easily operated by students.

  4. A numerical model of initial recombination for high-LET irradiation: Application to liquid-filled ionization chambers

    Science.gov (United States)

    Aguiar, P.; Pardo-Montero, J.

    2016-02-01

    In this paper we present a numerical model of initial recombination in media irradiated with high linear energy transfer (LET) ions, which relies on an amorphous track model of ionization of high LET particles, and diffusion, drift and recombination of ionized charge carriers. The model has fundamental applications for the study of recombination in non-polar liquids, as well as practical ones, like in modelling hadrontherapy dosimetry with ionization chambers. We have used it to study the response of liquid-filled ionization chambers to hadrontherapy beams: dependence of initial recombination on ion species, energy and applied external electric field.

  5. Theoretical study of Jesse effect in tritium measurements using ionization chambers

    Science.gov (United States)

    Chen, Zhilin; Peng, Shuming; Lu, Hanghang; Tan, Zhaoyi; Wang, Heyi; Long, Xingui; Masao, Matsuyama

    2016-01-01

    Jesse effect caused by impurities in helium might enhance the output signal significantly in tritium measurements with ionization chamber, which will lead to overestimation of tritium concentration in experiments. A theoretical method was proposed to evaluate Jesse effect quantitatively. Results indicate that besides Penning ionization, sub-excitation electrons also place very important influence on ionization enhancement by Jesse effect. An experiential expression about the relationship between enhancement factor and impurity concentration was established, in which second order of it fits experimental results very well. Theoretical calculation method in this paper is also applicable to evaluate Jesse effect in other kinds of mixtures besides hydrogen as impurities in helium. In addition, Jesse effects about tritium molecules as impurities have also been investigated.

  6. Application of the two-dose-rate method for general recombination correction for liquid ionization chambers in continuous beams

    Science.gov (United States)

    Andersson, Jonas; Tölli, Heikki

    2011-01-01

    A method to correct for the general recombination losses for liquid ionization chambers in continuous beams has been developed. The proposed method has been derived from Greening's theory for continuous beams and is based on measuring the signal from a liquid ionization chamber and an air filled monitor ionization chamber at two different dose rates. The method has been tested with two plane parallel liquid ionization chambers in a continuous radiation x-ray beam with a tube voltage of 120 kV and with dose rates between 2 and 13 Gy min-1. The liquids used as sensitive media in the chambers were isooctane (C8H18) and tetramethylsilane (Si(CH3)4). The general recombination effect was studied using chamber polarizing voltages of 100, 300, 500, 700 and 900 V for both liquids. The relative standard deviation of the results for the collection efficiency with respect to general recombination was found to be a maximum of 0.7% for isooctane and 2.4% for tetramethylsilane. The results are in excellent agreement with Greening's theory for collection efficiencies over 90%. The measured and corrected signals from the liquid ionization chambers used in this work are in very good agreement with the air filled monitor chamber with respect to signal to dose linearity.

  7. Application of the two-dose-rate method for general recombination correction for liquid ionization chambers in continuous beams

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, Jonas; Toelli, Heikki, E-mail: jonas.andersson@radfys.umu.se [Department of Radiation Sciences, Radiation Physics, Umeaa University, SE-901 85 Umeaa (Sweden)

    2011-01-21

    A method to correct for the general recombination losses for liquid ionization chambers in continuous beams has been developed. The proposed method has been derived from Greening's theory for continuous beams and is based on measuring the signal from a liquid ionization chamber and an air filled monitor ionization chamber at two different dose rates. The method has been tested with two plane parallel liquid ionization chambers in a continuous radiation x-ray beam with a tube voltage of 120 kV and with dose rates between 2 and 13 Gy min{sup -1}. The liquids used as sensitive media in the chambers were isooctane (C{sub 8}H{sub 18}) and tetramethylsilane (Si(CH{sub 3}){sub 4}). The general recombination effect was studied using chamber polarizing voltages of 100, 300, 500, 700 and 900 V for both liquids. The relative standard deviation of the results for the collection efficiency with respect to general recombination was found to be a maximum of 0.7% for isooctane and 2.4% for tetramethylsilane. The results are in excellent agreement with Greening's theory for collection efficiencies over 90%. The measured and corrected signals from the liquid ionization chambers used in this work are in very good agreement with the air filled monitor chamber with respect to signal to dose linearity.

  8. Development of a Resistive Plate Chamber with heat strengthened glass

    Science.gov (United States)

    Majumder, G.; Datar, V. M.; Kalmani, S. D.; Mondal, N. K.; Mondal, S.; Satyanarayana, B.; Shinde, R. R.

    2016-09-01

    The INO-ICAL is a proposed neutrino physics experiment, in which RPCs will be used as active detectors. The Iron Calorimeter (ICAL) detector will be made of 50 kTon of low carbon magnetized steel layers, tiled with 4 m × 2 m × 56 mm thick plates, alternating with layers of RPCs. The total number of 2 × 2 m2 RPCs required will be about 29000. However, during the assembly of RPCs, handling the 2 × 2 m2 normal float glass of thickness 3 mm is both difficult and risky. This prompted us to make RPCs with toughened glass and to characterize them. Toughened and tempered glass have higher mechanical strength compared to normal float glass and their processing involves controlled thermal or chemical treatment during the industrial production. This paper presents a comparison of the characteristics, such as noise rate, dark current, particle detection efficiency and time resolution, of normal and hardened glass RPCs.

  9. Calibration of the KRISS reference ionization chamber for certification of ²²²Rn gaseous sources.

    Science.gov (United States)

    Lee, J M; Lee, K B; Lee, S H; Oh, P J; Park, T S; Kim, B C; Lee, M S

    2013-11-01

    A primary measurement system for gaseous (222)Rn based on the defined solid angle counting method has recently been constructed at KRISS and the reference ionization chamber used to measure the activities of gamma-emitting single radionuclides was adopted as a secondary standard for gaseous (222)Rn. A 20 mL flame-sealed glass ampoule source from the primary measurement system was used to calibrate the ionization chamber for (222)Rn. The (222)Rn efficiency of the ionization chamber was compared with that calculated by using a photon energy-dependent efficiency curve and that measured by using a standard (226)Ra solution. From the comparisons we draw the conclusion that the reference ionization chamber for gamma-emitting radionuclides can be a suitable secondary measurement system for gaseous (222)Rn sources.

  10. Design and construction of the first prototype ionization chamber for CSNS and PA beam loss monitor (BLM) system

    Institute of Scientific and Technical Information of China (English)

    XU Mei-Hang; TIAN Jian-Min; CHEN Chang; CHEN Yuan-Bo; XU Tao-Guang; LU Shuang-Tong

    2009-01-01

    Design and construction of the first prototype ionization chamber for CSNS and Proton Accelerator (PA) beam loss monitor (BLM) system is reported. The low leakage current (<0.1 pA), good plateau (≈800 V) and linearity range up to 200 Roentgen/h axe obtained in the first prototype. All of these give us good experience for further improving the ionization chamber construction.

  11. Fluid modeling of resistive plate chambers: impact of transport data on development of streamers and induced signals

    Science.gov (United States)

    Bošnjaković, D.; Petrović, Z. Lj; Dujko, S.

    2016-10-01

    We discuss the implementation of transport data in modeling of resistive plate chambers (RPCs), which are used for timing and triggering purposes in many high energy physics experiments. Particularly, we stress the importance of making a distinction between flux and bulk transport data when non-conservative collisions, such as attachment and/or ionization, are present. A 1.5-dimensional fluid model with photoionization is employed to demonstrate how the duality of transport data affects the calculated signals of the ATLAS triggering RPC and ALICE timing RPC used at CERN, and also a timing RPC with high \\text{S}{{\\text{F}}6} content. It is shown that in the case of timing RPCs, the difference between the induced charges calculated using flux and bulk transport data can reach several hundred percent at lower operating electric fields. The effects of photoionization and space charge are also discussed.

  12. Characterization of a 2D ionization chamber array for IMRT plan verification

    Energy Technology Data Exchange (ETDEWEB)

    Alashrah, S. [Universiti Sains Malaysia, Penang (Malaysia); Kandaiya, S., E-mail: sivamany@usm.m [Universiti Sains Malaysia, Penang (Malaysia); Yong, S.Y.; Cheng, S.K. [Mount Miriam Hospital, Penang (Malaysia)

    2010-07-21

    A commercialized array of 2D pixel ionization chambers MatriXX from Scanditronix Wellhoefer was evaluated with the objective to implement for quality assurance in IMRT treatment plan verification. The device consists of 1020 chambers arranged in a 32x32 grid. The distance between the chamber centres is 7.6 mm and the volume of the chamber is 0.08 cm{sup 3}. The effective point measurement of the MatriXX was verified and it agreed with the MatriXX's manual specifications. The start-up behaviour, and the short- and long-term reproducibilities of the array detector were tested. Dose linearity and energy independence were also analyzed. The results showed that the dose was linear within the range 9-800 cGy and the response of the 2D array was independent of energy for 6 and 10 MV photon beams. The MatriXX was independent of dose rate ranging from 183 to 483 cGy/min. For field sizes 3x3 cm{sup 2} and above the output factors of the 2D agreed within 1% with those obtained using the FC65-G ionization chamber. But at field size 2x2 cm{sup 2} the percentage difference was 5%. However, there was a poor correlation with differences greater than 1 mm in the penumbra region. The preliminary investigations indicate that the detector is suitable for IMRT plan verifications but corrections have to be applied in regions of high dose gradient.

  13. A liquid-filled ionization chamber for high precision relative dosimetry.

    Science.gov (United States)

    González-Castaño, D M; Gómez, F; Brualla, L; Roselló, J V; Planes, D; Sánchez, M; Pombar, M

    2011-04-01

    Radiosurgery and intensity modulated radiation therapy (IMRT) treatments are based on the delivery of narrow and/or irregularly shaped megavoltage photon beams. This kind of beams present both lack of charged particle equilibrium and steep dose gradients. Quality assurance (QA) measurements involved in these techniques must therefore be carried out with a dosimeter featuring high small volume. In order to obtain a good signal to noise ratio, a relatively dense material is needed as active medium. Non-polar organic liquids were proposed as active mediums with both good tissue equivalence and showing high signal to noise ratio. In this work, a liquid-filled ionization chamber is presented. Some results acquired with this detector in relative dosimetry are studied and compared with results obtained with unshielded diode. Medium-term stability measurements were also carried out and its results are shown. The liquid-filled ionization chamber presented here shows its ability to perform profile measurements and penumbrae determination with excellent accuracy. The chamber features a proper signal stability over the period studied.

  14. Measurement of photon flux with a miniature gas ionization chamber in a Material Testing Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Fourmentel, D., E-mail: damien.fourmentel@cea.fr [CEA, DEN, DER, Instrumentation Sensors and Dosimetry Laboratory, Cadarache, F-13108 St-Paul-Lez-Durance (France); Filliatre, P.; Villard, J.F.; Lyoussi, A. [CEA, DEN, DER, Instrumentation Sensors and Dosimetry Laboratory, Cadarache, F-13108 St-Paul-Lez-Durance (France); Reynard-Carette, C. [Aix-Marseille Université, LISA EA 4672, cedex 20, Marseille 13397 (France); Carcreff, H. [CEA, DEN, DRSN, Saclay, F-91191 Gif-sur-Yvette (France)

    2013-10-01

    Nuclear heating measurements in Material Testing Reactors (MTR) are crucial for the design of the experimental devices and the prediction of the temperature of the hosted samples. Nuclear heating in MTR materials (except fuel) is mainly due to the energy deposition by the photon flux. Therefore, the photon flux is a key input parameter for the computer codes which simulate nuclear heating and temperature reached by samples/devices under irradiation. In the Jules Horowitz MTR under construction at the CEA Cadarache, the maximal expected nuclear heating levels will be about 15 to 18 W g{sup −1} and it will be necessary to assess this parameter with the best accuracy. An experiment was performed at the OSIRIS reactor to combine neutron flux, photon flux and nuclear heating measurements to improve the knowledge of the nuclear heating in MTR. There are few appropriate sensors for selective measurement of the photon flux in MTR even if studies and developments are ongoing. An experiment, called CARMEN-1, was conducted at the OSIRIS MTR and we used in particular a gas ionization chamber based on miniature fission chamber design to measure the photon flux. In this paper, we detail Monte-Carlo simulations to analyze the photon fluxes with ionization chamber measurements and we compare the photon flux calculations to the nuclear heating measurements. These results show a good accordance between photon flux measurements and nuclear heating measurement and allow improving the knowledge of these parameters.

  15. Proton beam dosimetry: a comparison between a plastic scintillator, ionization chamber and Faraday cup.

    Science.gov (United States)

    Ghergherehchi, Mitra; Afarideh, Hossein; Ghannadi, Mohammad; Mohammadzadeh, Ahmad; Aslani, Golam Reza; Boghrati, Behzad

    2010-01-01

    In this study, a comparison was made between a plastic scintillator (BC400), a Faraday Cup (FC) and an ionization chamber (IC) used for routine proton dosimetry. Thin scintillators can be applied to proton dosimetry and consequently to proton therapy as relative dosimeters because of their water-equivalent nature, high energy-light conversion efficiency, low dimensions and good proportionality to the absorbed dose at low stopping powers. To employ such scintillators as relative dosimeters in proton therapy, the corrective factors must be applied to correct the quenching luminescence at the Bragg peak. A fine linear proportionality between the luminescence light yield Y and the proton flux in a thin (0.5 mm) scintillator for the 20 and 30 MeV proton beams were observed. The experimental peak/plateau ratios of Bragg Curve for 2, 1 and 0.5 mm scintillators with an accuracy of 0.5% were obtained to be 1.87, 1.91 and 2.30, respectively. With combination of the Markus chamber and the CR-39 detector, the peak/plateau ratio was improved to 3.26. The obtained data of the luminescence yield as a function of the specific energy loss is in agreement with the Craun-Birk's theory. Results show that the FC and Markus ionization chamber are in agreement within 4%, while the FC gives a lower dose evaluation. For a defined beam, the data for the fluence measurements are reproducible within a good accuracy.

  16. Use of relativistic rise in ionization chambers for measurement of high energy heavy nuclei

    Science.gov (United States)

    Barthelmy, S. D.; Israel, M. H.; Klarmann, J.; Vogel, J. S.

    1983-01-01

    A balloon-borne instrument has been constructed to measure the energy spectra of cosmic-ray heavy nuclei in the range of about 0.3 to about 100 GeV/amu. It makes use of the relativistic rise portion of the Bethe-Bloch curve in ionization chambers for energy determination in the 10- to 100-GeV/amu interval. The instrument consists of six layers of dual-gap ionization chambers for energy determination above 10 GeV/amu. Charge is determined with a NE114 scintillator and a Pilot 425 plastic Cerenkov counter. A CO2 gas Cerenkov detector (1 atm; threshold of 30 GeV/amu) calibrates the ion chambers in the relativistic rise region. The main emphasis of the instrument is the determination of the change of the ratio of Iron (26) to the Iron secondaries (21-25) in the energy range of 10 to 100 GeV/amu. Preliminary data from a balloon flight in the fall of 1982 from Palestine, TX is presented.

  17. Space charge effect measurements for a multi-channel ionization chamber used for synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Nasr, Amgad

    2012-07-18

    In vivo coronary angiography is one of the techniques used to investigate the heart diseases, by using catheter to inject a contrast medium of a given absorption coefficient into the heart vessels. Taking X-ray images produced by X-ray tube or synchrotron radiation for visualizing the blood in the coronary arteries. As the synchrotron radiation generated by the relativistic charged particle at the bending magnets, which emits high intensity photons in comparison with the X-ray tube. The intensity of the synchrotron radiation is varies with time. However for medical imaging it's necessary to measure the incoming intensity with the integrated time. The thesis work includes building a Multi-channel ionization chamber which can be filled with noble gases N{sub 2}, Ar and Xe with controlled inner pressure up to 30 bar. This affects the better absorption efficiency in measuring the high intensity synchrotron beam fluctuation. The detector is a part of the experimental setup used in the k-edge digital subtraction angiography project, which will be used for correcting the angiography images taken by another detector at the same time. The Multi-channel ionization chamber calibration characteristics are measured using 2 kW X-ray tube with molybdenum anode with characteristic energy of 17.44 keV. According to the fast drift velocity of the electrons relative to the positive ions, the electrons will be collected faster at the anode and will induce current signals, while the positive ions is still drifting towards the cathode. However the accumulation of the slow ions inside the detector disturbs the homogeneous applied electric field and leads to what is known a space charge effect. In this work the space charge effect is measured with very high synchrotron photons intensity from EDR beam line at BESSYII. The strong attenuation in the measured amplitude signal occurs when operating the chamber in the recombination region. A plateau is observed at the amplitude signal when

  18. Performance of Resistive Plate Chambers installed during the first long shutdown of the CMS experiment

    CERN Document Server

    Shopova, M; Hadjiiska, R; Iaydjiev, P; Sultanov, G; Rodozov, M; Stoykova, S; Assran, Y; Sayed, A; Radi, A; Aly, S; Singh, G; Abbrescia, M; Iaselli, G; Maggi, M; Pugliese, G; Verwilligen, P; Van Doninck, W; Colafranceschi, S; Sharma, A; Benussi, L; Bianco, S; Piccolo, D; Primavera, F; Cimmino, A; Crucy, S; Rios, A A O; Tytgat, M; Zaganidis, N; Gul, M; Fagot, A; Bhatnagar, V; Singh, J; Kumari, R; Mehta, A; Ahmad, A; Awan, I M; Shahzad, H; Hoorani, H; Asghar, M I; Muhammad, S; Ahmed, W; Shah, M A; Cho, S W; Choi, S Y; Hong, B; Kang, M H; Lee, K S; Lim, J H; Park, S K; Kim, M S; Laktineh, I B; Lagarde, F; Gouzevitch, M; Grenier, G; Pedraza, I; Bernardino, S Carpinteyro; Estrada, C Uribe; Moreno, S Carrillo; Valencia, F Vazquez; Pant, L M; Buontempo, S; Cavallo, N; Fabozzi, F; Orso, I; Lista, L; Meola, S; Merola, M; Paolucci, P; Thyssen, F; Lanza, G; Esposito, M; Braghieri, A; Magnani, A; Riccardi, C; Salvini, P; Vai, I; Vitulo, P; Montagna, P; Ban, Y; Qian, S J; Choi, M; Choi, Y; Goh, J; Kim, D; Dimitrov, A; Litov, L; Petkov, P; Pavlov, B; Bagaturia, I; Lomidze, D; Avila, C; Cabrera, A; Sanabria, J C; Crotty, I; Vaitkus, J

    2016-01-01

    The CMS experiment, located at the CERN Large Hadron Collider, has a redundant muon system composed by three different detector technologies: Cathode Strip Chambers (in the forward regions), Drift Tubes (in the central region) and Resistive Plate Chambers (both its central and forward regions). All three are used for muon reconstruction and triggering. During the first long shutdown (LS1) of the LHC (2013-2014) the CMS muon system has been upgraded with 144 newly installed RPCs on the forth forward stations. The new chambers ensure and enhance the muon trigger efficiency in the high luminosity conditions of the LHC Run2. The chambers have been successfully installed and commissioned. The system has been run successfully and experimental data has been collected and analyzed. The performance results of the newly installed RPCs will be presented.

  19. Fabrication and Characterisation of Oil-Free Large Bakelite Resistive Plate Chamber

    CERN Document Server

    Ganai, Rajesh; Agarwal, Kshitij; Ahammed, Zubayer; Choudhury, Subikash; Chattopadhyay, Subhasis

    2015-01-01

    A large (240 cm $\\times$ 120 cm $\\times$ 0.2 cm) oil-free bakelite Resistive Plate Chamber (RPC) has been developed at VECC-Kolkata using locally available P-301 OLTC grade bakelite paper laminates. The chamber has been operated in streamer mode using Argon, Freon(R134a) and Iso-butane in a ratio of 34:57:9 by volume. The electrodes and glue samples were characterised by measuring their electrical parameters like bulk resistivity and surface resistivity. The performance of the chamber was studied by measuring the efficiency, time resolution and uniformity in detection of cosmic muons. The chamber showed an efficiency $>$95$\\%$ and time resolution ($\\sigma$) of $\\sim$0.83 ns. Details of the material characterisation, fabrication procedure and performance studies have been discussed.

  20. Operation and performance of the CMS Resistive Plate Chambers during LHC run II

    CERN Document Server

    Eysermans, Jan

    2017-01-01

    The Resitive Plate Chambers (RPC) at the Compact Muon Solenoid (CMS) experiment at the CERN Large Hadron Collider (LHC) provide redundancy to the Drift Tubes in the barrel and Cathode Strip Chambers in the endcap regions. Consisting of 1056 double gap RPC chambers, the main detector parameters and environmental conditions are carefully monitored during the data taking period. At a center of mass energy of 13 TeV, the luminosity reached record levels which was challenging from the operational and performance point of view. In this work, the main operational parameters are discussed and the overall performance of the RPC system is reported for the LHC run II data taking period. With a low amount of inactive chambers, a good and stable detector performance was achieved with high efficiency.

  1. Determination of small-field correction factors for cylindrical ionization chambers using a semiempirical method.

    Science.gov (United States)

    Park, Kwangwoo; Bak, Jino; Park, Sungho; Choi, Wonhoon; Park, Suk Won

    2016-02-07

    A semiempirical method based on the averaging effect of the sensitive volumes of different air-filled ionization chambers (ICs) was employed to approximate the correction factors for beam quality produced from the difference in the sizes of the reference field and small fields.We measured the output factors using several cylindrical ICs and calculated the correction factors using a mathematical method similar to deconvolution; in the method, we modeled the variable and inhomogeneous energy fluence function within the chamber cavity. The parameters of the modeled function and the correction factors were determined by solving a developed system of equations as well as on the basis of the measurement data and the geometry of the chambers. Further, Monte Carlo (MC) computations were performed using the Monaco® treatment planning system to validate the proposed method.The determined correction factors () were comparable to the values derived from the MC computations performed using Monaco®. For example, for a 6 MV photon beam and a field size of 1  ×  1 cm2, was calculated to be for a PTW 31010 chamber and for a PTW 31016 chamber. On the other hand, the values determined from the MC computations were 1.121 and 1.031, respectively; the difference between the proposed method and the MC computation is less than 2%. In addition, we determined the values for PTW 30013, PTW 31010, PTW 31016, IBA FC23-C, and IBA CC13 chambers as well.We devised a method for determining from both the measurement of the output factors and model-based mathematical computation. The proposed method can be useful in case the MC simulation would not be applicable for the clinical settings.

  2. Analysis of dose perturbation factors of a NACP-02 ionization chamber in clinical electron beams.

    Science.gov (United States)

    Chin, E; Palmans, H; Shipley, D; Bailey, M; Verhaegen, F

    2009-01-21

    For well-guarded plane-parallel ionization chambers, international dosimetry protocols recommend a value of unity for electron perturbation factors in water. However, recent data published by various groups have challenged this. Specifically for the NACP-02 chamber, non-unity electron perturbation factors have already been published by Verhaegen et al (2006 Phys. Med. Biol. 51 1221-35) and Buckley and Rogers (2006 Med. Phys. 33 1788-96). Recently it was found that the mass thickness of the front chamber window can be 35% greater than is listed in the IAEA's TRS-398 absorbed dose protocol (Chin et al 2008 Phys. Med. Biol. 53 N119-26). This study therefore recalculated NACP-02 electron perturbation correction factors for energies 4-18 MeV at depths z(ref) and R(50) to determine the effect of the chamber model change. Results showed that perturbation factors at z(ref) are fairly stable for similar chamber models but become highly sensitive to small changes at deeper depths. The results also showed some dependence on using 1 keV versus 10 keV for the transport cut-off. Additional investigations revealed that the wall perturbation factor, p(wall), is strongly influenced by the chamber back wall at z(ref) and at larger depths small changes in the positioning of the effective point of measurement cause large fluctuations in the final value. Finally, the cavity perturbation factor, p(cav), was found to be primarily influenced by electron backscatter.

  3. Characterization of a new ionization chamber in radiotherapy beams: angular dependence and variation of response with distance.

    Science.gov (United States)

    Silva, Jonas O; Linda V E, Caldas

    2012-10-01

    A new double faced ionization chamber was constructed at the Calibration Laboratory of IPEN. It has different collecting electrode materials: aluminum and graphite. It was irradiated in standard radiotherapy beams ((60)Co and X-rays). The response variation with distance and the angular dependence of this ionization chamber were evaluated. It was verified that the chamber response follows the inverse square law within a maximum variation of 11.2% in relation to the reference value. For the angular dependence it showed good agreement with international standards.

  4. Detection and measurement of delay in the yield of negative ions from the ionization chamber of a mass spectrometer

    Science.gov (United States)

    Lukin, V. G.; Khvostenko, O. G.; Tuimedov, G. M.

    2016-02-01

    The times of extraction of negative ions from the ionization chamber of a mass spectrometer have been measured. The obtained values amount to several dozen microseconds or above—that is, significantly exceed the time of free ion escape from the chamber. It is established that ions are retained in the ionization chamber because of their adsorption on the inner surface. This leads to distortion of the experimentally measured lifetimes of negative ions that become unstable with respect to autodetachment of the excess electron.

  5. Fabrication of Free Air Well Type Ionization Chamber and Calculational Assessment and Measurement of Its Operational Characteristics

    Directory of Open Access Journals (Sweden)

    Koroush Arbabi

    2007-12-01

    Full Text Available Introduction: Well type ionization chamber is a measuring device which is used to determine the activity of brachytherapy sources. The chamber has a cylindrical volume in which a cylindrical tube is mounted in the middle of the chamber. For the measurements, the brachytherapy sources are transferred to the middle of the tube. Materials and Methods: For designing the well type chamber, the measurement principals of well type chambers were considered and MCNP-4C code as a calculation tool was used. The designed chamber was simulated and the response of the chamber was evaluated. In this investigation, the chamber operational parameters such as operating voltage, leakage current, reproducibility, reference measuring point, recombination and polarization factors as well as response stability for 137Cs, 57Co and 241Am sources were studied. Results: The chamber leakage currents at the operating voltage in comparison to the chamber response for the measurement of the above mentioned sources were negligible. The responses of the fabricated chamber for these sources are reproducible and its reference measurement position for these sources was obtained at 6 cm from the bottom of the chamber. The recombination factor for the well type chamber was negligible and the polarization factor is close to 1. Therefore, these two factors were not considered in the measurements. The reproducibility of the measurements in different intervals shows the stability of the chamber response for each source. Also the results of the chamber current measurement in term of source strength were compared to the response of the simulated chamber for different source positions and energy ranges of the used sources. Discussion and Conclusion: The results show that the measurement of the reference positions for each source in the simulated and fabricated chamber is quite in a good agreement. Regarding the reliable operational properties of the fabricated chamber, this chamber can be

  6. Multi-Sampling Ionization Chamber (MUSIC) for measurements of fusion reactions with radioactive beams

    Energy Technology Data Exchange (ETDEWEB)

    Carnelli, P.F.F. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Laboratorio TANDAR, Comisión Nacional de Energía Atómica, Av. Gral. Paz 1499, B1650KNA, San Martín, Buenos Aires (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas, Av. Rivadavia 1917, C1033AAJ Buenos Aires (Argentina); Almaraz-Calderon, S. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Rehm, K.E., E-mail: rehm@anl.gov [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Albers, M.; Alcorta, M.; Bertone, P.F.; Digiovine, B.; Esbensen, H. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Fernández Niello, J. [Laboratorio TANDAR, Comisión Nacional de Energía Atómica, Av. Gral. Paz 1499, B1650KNA, San Martín, Buenos Aires (Argentina); Universidad Nacional de San Martín, Campus Miguelete, B1650BWA San Martín, Buenos Aires (Argentina); Henderson, D.; Jiang, C.L. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Lai, J. [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States); Marley, S.T.; Nusair, O.; Palchan-Hazan, T.; Pardo, R.C. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Paul, M. [Racah Institute of Physics, Hebrew University, Jerusalem (Israel); Ugalde, C. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States)

    2015-11-01

    A detection technique for high-efficiency measurements of fusion reactions with low-intensity radioactive beams was developed. The technique is based on a Multi-Sampling Ionization Chamber (MUSIC) operating as an active target and detection system, where the ionization gas acts as both target and counting gas. In this way, we can sample an excitation function in an energy range determined by the gas pressure, without changing the beam energy. The detector provides internal normalization to the incident beam and drastically reduces the measuring time. In a first experiment we tested the performance of the technique by measuring the {sup 10,13,15}C+{sup 12}C fusion reactions at energies around the Coulomb barrier.

  7. Multi-Sampling Ionization Chamber (MUSIC) for measurements of fusion reactions with radioactive beams

    Science.gov (United States)

    Carnelli, P. F. F.; Almaraz-Calderon, S.; Rehm, K. E.; Albers, M.; Alcorta, M.; Bertone, P. F.; Digiovine, B.; Esbensen, H.; Fernández Niello, J.; Henderson, D.; Jiang, C. L.; Lai, J.; Marley, S. T.; Nusair, O.; Palchan-Hazan, T.; Pardo, R. C.; Paul, M.; Ugalde, C.

    2015-11-01

    A detection technique for high-efficiency measurements of fusion reactions with low-intensity radioactive beams was developed. The technique is based on a Multi-Sampling Ionization Chamber (MUSIC) operating as an active target and detection system, where the ionization gas acts as both target and counting gas. In this way, we can sample an excitation function in an energy range determined by the gas pressure, without changing the beam energy. The detector provides internal normalization to the incident beam and drastically reduces the measuring time. In a first experiment we tested the performance of the technique by measuring the 10,13,15C+12C fusion reactions at energies around the Coulomb barrier.

  8. (n, {alpha}) cross section measurement of light nuclei using gridded ionization chamber and gaseous sample

    Energy Technology Data Exchange (ETDEWEB)

    Sanami, Toshiya; Baba, Mamoru; Saito, Keiichiro; Ibara, Yasutaka; Yamazaki, Tetsuro; Sato, Jun; Hirakawa, Naohiro [Tohoku Univ., Sendai (Japan)

    1998-03-01

    We have developed a measuring method of (n, {alpha}) cross section by using gaseous sample in a gridded ionization chamber. In this study, we measured the {sup 12}C(n, {alpha}{sub 0}) and the {sup 16}O(n, {alpha}{sub 0}), (n, {alpha}{sub 123}) cross sections for En=11.5 and 12.8 MeV neutrons. We also deduced the {sup 12}C(n, x{alpha}) spectrum and analyzed the data by a kinematic calculation combined with the reaction data of the {sup 12}C(n, n`3{alpha}). (author)

  9. Calibration and efficiency curve of SANAEM ionization chamber for activity measurements.

    Science.gov (United States)

    Yeltepe, Emin; Kossert, Karsten; Dirican, Abdullah; Nähle, Ole; Niedergesäß, Christiane; Kemal Şahin, Namik

    2016-03-01

    A commercially available Fidelis ionization chamber was calibrated and assessed in PTB with activity standard solutions. The long-term stability and linearity of the system was checked. Energy-dependent efficiency curves for photons and beta particles were determined, using an iterative method in Excel™, to enable calibration factors to be calculated for radionuclides which were not used in the calibration. Relative deviations between experimental and calculated radionuclide efficiencies are of the order of 1% for most photon emitters and below 5% for pure beta emitters. The system will enable TAEK-SANAEM to provide traceable activity measurements.

  10. IFIN-HH ionization chamber calibration and its validation; electrometric system improvement.

    Science.gov (United States)

    Sahagia, M; Wätjen, A C; Luca, A; Ivan, C

    2010-01-01

    The paper presents the results obtained in the calibration of the CENTRONIC IG12/20A ionization chamber for 18 gamma ray emitters, and its improvement with a Keithley 6517A electrometer. The calibration figures were determined either directly in pA MBq(-1) units, or calculated from old units, by using the system capacity value. The calibration figures, determined with RML's standards, are compared with those deduced from the KCRV or the mean of the comparisons, and the values determined at PTB-Germany.

  11. Application of patent BR102013018500-0 in well type ionization chambers

    Science.gov (United States)

    Sousa, C. H. S.; Peixoto, J. G. P.

    2016-07-01

    The definition of the radioactive sample position in a well type ionization chamber is the largest source of uncertainty in the measurement of quantity activity. The determination of this parameter in two activimeters helped to improve their accuracies, from 2.62 and 2.59% to 3.87 and 1.74%, with and without the use of the positioning device, concluding, that with their use has reached an uncertainty of U =2276 and 0.2677% (k = 2) 95.45%.

  12. Air filled ionization chambers and their response to high LET radiation

    DEFF Research Database (Denmark)

    Kaiser, Franz-Joachim; Bassler, Niels; Tölli, Heikki

    Background Air filled ionization chambers (ICs) are widely used for absolute dosimetry, not only in photon beams but also in beams of heavy charged particles. Within the IC, electron hole pairs are generated by the energy deposition originating from incoming radiation. High-LET particles create...... structure theory. More specifically, we solved the equation for the geometrical setup of the Bragg-peak IC, which is a plane parallel IC with a 2 mm spacing between the electrodes. The sensitive volume of the IC is located in a thermoplastic housing of several mm thickness. Results We compare...

  13. IFIN-HH ionization chamber calibration and its validation; electrometric system improvement

    Energy Technology Data Exchange (ETDEWEB)

    Sahagia, M., E-mail: msahagia@nipne.r [' Horia Hulubei' National Institute of R and D for Physics and Nuclear Engineering, IFIN-HH, P.O. Box MG-6, Bucharest, RO-77125 (Romania); Waetjen, A.C.; Luca, A.; Ivan, C. [' Horia Hulubei' National Institute of R and D for Physics and Nuclear Engineering, IFIN-HH, P.O. Box MG-6, Bucharest, RO-77125 (Romania)

    2010-07-15

    The paper presents the results obtained in the calibration of the CENTRONIC IG12/20A ionization chamber for 18 gamma ray emitters, and its improvement with a Keithley 6517A electrometer. The calibration figures were determined either directly in pA MBq{sup -1} units, or calculated from old units, by using the system capacity value. The calibration figures, determined with RML's standards, are compared with those deduced from the KCRV or the mean of the comparisons, and the values determined at PTB-Germany.

  14. (n,{alpha}) cross section measurement of gaseous sample using gridded ionization chamber. Cross section determination

    Energy Technology Data Exchange (ETDEWEB)

    Sanami, Toshiya; Baba, Mamoru; Saito, Keiichiro; Ibara, Yasutaka; Hirakawa, Naohiro [Tohoku Univ., Sendai (Japan). Faculty of Engineering

    1997-03-01

    We are developing a method of (n,{alpha}) cross section measurement using gaseous samples in a gridded ionization chamber (GIC). This method enables cross section measurements in large solid angle without the distortion by the energy loss in a sample, but requires a method to estimate the detection efficiency. We solve this problem by using GIC signals and a tight neutron collimation. The validity of this method was confirmed through the {sup 12}C(n,{alpha}{sub 0}){sup 9}Be measurement. We applied this method to the {sup 16}O(n,{alpha}){sup 13}C cross section around 14.1 MeV. (author)

  15. Application of patent BR102013018500-0 in well type ionization chambers

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, C.H.S.; Peixoto, J.G.P., E-mail: chenriques2@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2015-07-01

    The definition of the radioactive sample position in a well type ionization chamber is the largest source of uncertainty in the measurement of quantity activity. The determination of this parameter in two activimeter helped to improve their accuracies, from 2.62 and 2.59% to 3.87 and 1.74%, with and without the use of the positioning device, concluding, that with their use has reached an uncertainty of U = 0.2276 and 0.2677 % (k = 2) 95.45%. (author)

  16. Development and characterization of a graphite-walled ionization chamber as a reference dosimeter for 60Co beams

    Science.gov (United States)

    Perini, Ana P.; Neves, Lucio P.; Caldas, Linda V. E.

    2014-11-01

    A graphite-walled ionization chamber with a sensitive volume of 6.4 cm3 was developed at the Calibration Laboratory of IPEN (LCI) to determine the air kerma rate of a 60Co source. This new prototype was developed to be a simple chamber, without significant nongraphite components and with a simple set-up, which allows the determination of its various required correction factors by Monte Carlo simulations. This new ionization chamber was characterized according to the IEC 60731 standard, and all results were obtained within its limits. Furthermore, Monte Carlo simulations were undertaken to obtain the correction factors involved with the air kerma determination. The air kerma rate obtained with the graphite-walled ionization chamber was compared with that from the reference dosimeter at the LCI, a PTW ionization chamber (model TN30002). The results obtained showed good agreement within the statistical uncertainties. A graphite ionization chamber was assembled and characterized as a reference dosimeter. The characterization test results were within recommended limits. Monte Carlo simulations were undertaken to obtain the correction factors. The air kerma rate of a 60Co source was obtained with satisfactory results.

  17. Comparison of CMS Resistive Plate Chambers performance during LHC RUN-1 and RUN-2

    CERN Document Server

    Shah, Mehar Ali

    2016-01-01

    The Resistive Plate Chambers detector system at the CMS experiment at the LHC provides robustness and redundancy to the muon trigger. A total of 1056 double-gap chambers cover the pseudo-rapidity region < 1.6. The main detector parameters and environmental conditions are constantly and closely monitored to achieve operational stability and high quality data in the harsh conditions of the second run period of the LHC with center-of-mass energy of 13 TeV. First results of overall detector stability with 2015 data and comparisons with data from the LHC RUN-1 period at 8 TeV are presented.

  18. Comparison of CMS Resistive Plate Chambers performance during LHC RUN-1 and RUN-2

    CERN Document Server

    Shah, Mehar Ali

    2016-01-01

    The Resistive Plate Chambers detector system at the CMS experiment at the LHC provides robustness and redundancy to the muon trigger. A total of 1056 double-gap chambers cover the pseudo-rapidity region lt 1.6. The main detector parameters and environmental conditions are constantly and closely monitored to achieve operational stability and high quality data in the harsh conditions of the second run period of the LHC with center-of-mass energy of 13 TeV. First results of overall detector stability with 2015 data and comparisons with data from the LHC RUN-1 period at 8 TeV are presented.

  19. Study of the effect of water vapor on a resistive plate chamber with glass electrodes

    CERN Document Server

    Sakai, H H; Teramoto, Y; Nakano, E E; Takahashi, T T

    2002-01-01

    We studied the effects of water vapor on the efficiencies of resistive plate chambers with glass electrodes, operated in the streamer mode. With moisture in the chamber gas that has freon as a component (water vapor approx 1000 ppm), a decrease in the efficiency (approx 20%) has been observed after operating for a period of several weeks to a few months. From our study, the cause of the efficiency decrease was identified as a change on the cathode surface. In addition, a recovery method was found: flushing for 1 day with argon bubbled through water containing >=3% ammonia, followed by a few weeks of training with dry gas.

  20. Use of a two-dimensional ionization chamber array for proton therapy beam quality assurance.

    Science.gov (United States)

    Arjomandy, Bijan; Sahoo, Narayan; Ding, Xiaoning; Gillin, Michael

    2008-09-01

    Two-dimensional ion chamber arrays are primarily used for conventional and intensity modulated radiotherapy quality assurance. There is no commercial device of such type available on the market that is offered for proton therapy quality assurance. We have investigated suitability of the MatriXX, a commercial two-dimensional ion chamber array detector for proton therapy QA. This device is designed to be used for photon and electron therapy QA. The device is equipped with 32 x 32 parallel plate ion chambers, each with 4.5 mm diam and 7.62 mm center-to-center separation. A 250 MeV proton beam was used to calibrate the dose measured by this device. The water equivalent thickness of the buildup material was determined to be 3.9 mm using a 160 MeV proton beam. Proton beams of different energies were used to measure the reproducibility of dose output and to evaluate the consistency in the beam flatness and symmetry measured by MatriXX. The output measurement results were compared with the clinical commissioning beam data that were obtained using a 0.6 cc Farmer chamber. The agreement was consistently found to be within 1%. The profiles were compared with film dosimetry and also with ion chamber data in water with an excellent agreement. The device is found to be well suited for quality assurance of proton therapy beams. It provides fast two-dimensional dose distribution information in real time with the accuracy comparable to that of ion chamber measurements and film dosimetry.

  1. Long term response stability of a well-type ionization chamber used in calibration of high dose rate brachytherapy sources

    Directory of Open Access Journals (Sweden)

    Vandana S

    2010-01-01

    Full Text Available Well-type ionization chamber is often used to measure strength of brachytherapy sources. This study aims to check long term response stability of High Dose Rate (HDR -1000 Plus well-type ionization chamber in terms of reference air kerma rate (RAKR of a reference 137 Cs brachytherapy source and recommend an optimum frequency of recalibration. An HDR-1000 Plus well-type ionization chamber, a reference 137 Cs brachytherapy source (CDCSJ5, and a MAX-4000 electrometer were used in this study. The HDR-1000 Plus well-type chamber was calibrated in terms of reference air kerma rate by the Standards Laboratory of the International Atomic Energy Agency (IAEA, Vienna. The response of the chamber was verified at regular intervals over a period of eight years using the reference 137 Cs source. All required correction factors were applied in the calculation of the RAKR of the 137 Cs source. This study reveals that the response of the HDR-1000 Plus well-type chamber was well within ±0.5% for about three years after calibration/recalibration. However, it shows deviations larger than ±0.5% after three years of calibration/recalibration and the maximum variation in response of the chamber during an eight year period was 1.71%. The optimum frequency of recalibration of a high dose rate well-type chamber should be three years.

  2. Long term response stability of a well-type ionization chamber used in calibration of high dose rate brachytherapy sources.

    Science.gov (United States)

    Vandana, S; Sharma, S D

    2010-04-01

    Well-type ionization chamber is often used to measure strength of brachytherapy sources. This study aims to check long term response stability of High Dose Rate (HDR)-1000 Plus well-type ionization chamber in terms of reference air kerma rate (RAKR) of a reference (137)Cs brachytherapy source and recommend an optimum frequency of recalibration. An HDR-1000 Plus well-type ionization chamber, a reference (137)Cs brachytherapy source (CDCSJ5), and a MAX-4000 electrometer were used in this study. The HDR-1000 Plus well-type chamber was calibrated in terms of reference air kerma rate by the Standards Laboratory of the International Atomic Energy Agency (IAEA), Vienna. The response of the chamber was verified at regular intervals over a period of eight years using the reference (137)Cs source. All required correction factors were applied in the calculation of the RAKR of the (137)Cs source. This study reveals that the response of the HDR-1000 Plus well-type chamber was well within +/-0.5% for about three years after calibration/recalibration. However, it shows deviations larger than +/-0.5% after three years of calibration/recalibration and the maximum variation in response of the chamber during an eight year period was 1.71%. The optimum frequency of recalibration of a high dose rate well-type chamber should be three years.

  3. Latest results on the performance of the multigap resistive plate chamber used for the ALICE TOF

    CERN Document Server

    Akindinov, A; Anselmo, F; Antonioli, P; Basile, M; Cara Romeo, G; Cifarelli, Luisa; Cindolo, F; Cosenza, F; D'Antone, I; De Caro, A; De Pasquale, S; Di Bartolomeo, A; Fusco-Girard, M; Golovine, V; Guerzoni, M; Guida, M; Hatzifotiadou, D; Kaidalov, A B; Kim, D H; Kim, D W; Kisselev, S M; Laurenti, G; Lioublev, E; Lee, K; Lee, S C; Luvisetto, M L; Margotti, A; Martemyanov, A N; Massera, F; Meneghini, S; Michinelli, R; Nania, R; Otiougova, P; Pancaldi, G; Pesci, A; Pilastrini, R; Pinazza, O; Polozov, P A; Rizzi, M; Scapparone, E; Scioli, G; Sellitto, S B; Semeria, F; Serra, S; Smirnitsky, A V; Tchoumakov, M M; Ugolini, E; Usenko, E; Valenti, G; Voloshin, K G; Williams, M C S; Zagreev, B V; Zampolli, C; Zichichi, A; Zucchini, A; Zuffa, M

    2004-01-01

    For the identification of particles in the momentum range 0.5-2.5 GeV /c, the ALICE experiment uses a Time Of Flight array consisting of Multigap Resistive Plate Chambers (MRPC) in the form of long strips. The design of the detector elements is as follows: double stack MRPCs with glass resistive plates and 5 gas gaps of 250 mum per stack. The latest results on the performance of these MRPCs are presented. Typical values of time resolution sigma are better than 50 ps, with an efficiency of 99.9% and a long, more than 1.5kV, streamer-free plateau.

  4. High-rate axial-field ionization chamber for particle identification of Radioactive beams

    Science.gov (United States)

    Desouza, Romualdo; Vadas, Justin; Singh, Varinderjit; Visser, G.; Alexander, A.; Hudan, S.; Huston, J.; Wiggins, B.; Chbihi, A.; Famiano, M.; Bischak, M.

    2017-01-01

    The design, construction and performance characteristics of a simple axial-field ionization chamber suitable for identifying ions in a radioactive beam are presented. The detector is optimized for use with low-energy radioactive beams (<) 5 MeV/A. A fast charge sensitive amplifier (CSA) integrated into the detector design is also described. Coupling this fast CSA to the axial field ionization chamber produces an output pulse with a rise-time of 60 to 70 ns and a fall time of 100 ns, making the detector capable of sustaining a relatively high rate while providing a time resolution of 6 to 8 ns. Tests with an α source establish the detector energy resolution as 8 % for an energy deposit of 3.5 MeV. Beam tests indicate that the detector is an effective tool for the characterization of low-energy radioactive beams at beam intensities up to 3 x 105 ions/s. Supported by the U.S. DOE under Award # DE-FG02-88ER-40404 and the NSF under Grant No. 1342962.

  5. High-rate axial-field ionization chamber for particle identification of radioactive beams

    CERN Document Server

    Vadas, J; Visser, G; Alexander, A; Hudan, S; Huston, J; Wiggins, B B; Chbihi, A; Famiano, M; Bischak, M M; deSouza, R T

    2016-01-01

    The design, construction and performance characteristics of a simple axial-field ionization chamber suitable for identifying ions in a radioactive beam are presented. Optimized for use with low-energy radioactive beams (< 5 MeV/A) the detector presents only three 0.5 $\\mu$m/cm$^2$ foils to the beam in addition to the detector gas. A fast charge sensitive amplifier (CSA) integrated into the detector design is also described. Coupling this fast CSA to the axial field ionization chamber produces an output pulse with a risetime of 60-70 ns and a fall time of 100 ns, making the detector capable of sustaining a relatively high rate. Tests with an $\\alpha$ source establish the detector energy resolution as $\\sim$8 $\\%$ for an energy deposit of $\\sim$3.5 MeV. The energy resolution with beams of 2.5 and 4.0 MeV/A $^{39}$K ions and the dependence of the energy resolution on beam intensity is measured. At an instantaneous rate of 3 x 10$^5$ ions/s the energy resolution has degraded to 14% with a pileup of 12%. The go...

  6. Development of Gas Ionization Chambers with Coplanar Electrodes for Alpha-ray Spectrometry

    Science.gov (United States)

    Iwasaki, Kenta; Tanaka, Naomichi; Murakami, Kohei; Kusano, Hiroki; Shibamura, Eido; Hasebe, Nobuyuki; Miyajima, Mitsuhiro

    A large-area alpha-ray spectrometer is required to measure the low level alpha emitters in environmental samples, which may be distributed in the vicinity of nuclear power plants. A gas ionization chamber with a coplanar electrode has attractive features such as with mechanical ruggedness, easy handling, easy fabrication of large electrode, and relatively well-known performance. We have investigated the performance of a gas ionization chamber with a coplanar electrode for alpha-ray spectrometry, particularly in the energy resolution. The present experiment shows that the energy resolution in the full width at half maximum (FWHM) is 129 keV (= 2.7%) for alpha-rays from Np with an energy of 4.78 MeV, 120 keV (= 2.2%) for those with 5.49 MeV from Am, and 109 keV (= 1.9%) for those with 5.81 MeV from Cm. It is found that the energy resolution obtained at the present experiment is dominated in the electronic noise caused by the large capacitance existed between the collecting anode (CA) and non-collecting anode (NCA) in the coplanar electrode.

  7. Proton energy determination using activated yttrium foils and ionization chambers for activity assay

    Energy Technology Data Exchange (ETDEWEB)

    Avila-Rodriguez, M.A. [Turku PET Centre, University of Turku, Kiinamyllynkatu 4-8, 20520 Turku (Finland); Unidad PET/CT-Ciclotron, Facultad de Medicina, Universidad Nacional Autonoma de Mexico, Edificio de Investigacion P.B, Cd. Universitaria, Circ. Interior, C.P. 04510 Mexico D.F. (Mexico)], E-mail: avilarod@uwalumni.com; Rajander, J.; Lill, J.-O. [Turku PET Centre, Abo Akademi University, Porthansg 3, 20500 Turku (Finland); Gagnon, K. [Edmonton PET Centre, Cross Cancer Institute, 11560 University Ave., Edmonton, AB, T6G 1Z2 (Canada); Schlesinger, J. [Turku PET Centre, University of Turku, Kiinamyllynkatu 4-8, 20520 Turku (Finland); Wilson, J.S.; McQuarrie, S.A. [Edmonton PET Centre, Cross Cancer Institute, 11560 University Ave., Edmonton, AB, T6G 1Z2 (Canada); Solin, O. [Turku PET Centre, University of Turku, Kiinamyllynkatu 4-8, 20520 Turku (Finland)

    2009-05-15

    Excitation functions of the {sup 89}Y(p, xn) nuclear reactions were measured up to 18 MeV by the conventional activation method using the stacked-foil technique, and the irradiation of single foils. Activity assays of the irradiated foils were performed via ionization chamber and gamma spectroscopy methods. Activity ratios of the activation products were measured in two different facilities and evaluated for use as a practical and simple method for proton energy determinations. Cross section values measured in this work were compared with published data and with theoretical values as determined by the nuclear reaction model code EMPIRE II. In general, there was a good agreement between the experimental and theoretical values of the cross section data. Activity ratios of the isomeric and ground state of {sup 89}Zr measured via ionization chamber were found to be useful for proton energy determinations in the energy range from 7 to 15 MeV. Proton energies above 13 MeV were accurately determined using the {sup 89g}Zr/{sup 88}Zr and {sup 89g}Zr/{sup 88}Y activity ratios measured via gamma spectroscopy.

  8. Effects of variation of environmental parameters on the performance of Resistive Plate Chamber detectors

    Energy Technology Data Exchange (ETDEWEB)

    Meghna, K.K. [INO Graduate Training Programme and Saha Institute of Nuclear Physics, Kolkata 700064 (India); Homi Bhabha National Institute, Mumbai 400085 (India); Biswas, S. [School of Physical Sciences, National Institute of Science Education and Research, Bhubaneswar 751005 (India); Jash, A. [INO Graduate Training Programme and Saha Institute of Nuclear Physics, Kolkata 700064 (India); Homi Bhabha National Institute, Mumbai 400085 (India); Chattopadhyay, S. [Variable Energy Cyclotron Centre, Kolkata 700064 (India); Homi Bhabha National Institute, Mumbai 400085 (India); Saha, S., E-mail: satyajit.saha@saha.ac.in [Applied Nuclear Physics Division, Saha Institute of Nuclear Physics, Kolkata 700064 (India); Homi Bhabha National Institute, Mumbai 400085 (India)

    2016-04-21

    Performance of single gap Resistive Plate Chamber (RPC) detectors is investigated under variation of environmental parameters, such as temperature and relative humidity. Operational characteristics of the RPCs depend on both the environmental temperature and the relative humidity. Sensitivity to such dependence is found to be more on temperature rather than the relative humidity. Qualitative interpretation of some of the results obtained is given based on the known properties of the electrode materials and gases used in the detectors. - Highlights: • Performance of single gap bakelite Resistive Plate Chamber (RPC) detectors is investigated under independent variation of environmental temperature and relative humidity. • Parameters such as leakage currents, noise rates, efficiency and timing characteristics of RPCs are investigated. • Operational characteristics of the RPCs depend on both the environmental temperature and the relative humidity. • Sensitivity of the operational parameters to variation of environmental parameters is found to be more on temperature rather than the relative humidity.

  9. Laboratory implantation for well type ionization chambers calibration; Implantacao de um laboratorio para calibracao de camaras de ionizacao tipo poco

    Energy Technology Data Exchange (ETDEWEB)

    Vianello, E.A.; Dias, D.J.; Almeida, C.E. de [Laboratorio de Ciencias Radiologicas- LCR- DBB (UERJ). R. Sao Francisco Xavier, 524- Pav. HLC, sala 136 terreo- CEP 20.550-013. Rio de Janeiro (Brazil)

    1998-12-31

    The Radiological Science Laboratory is implanting a service for calibration of well type chambers by IAEA training program. The kerma rate in the air (mu Gy/h) of the linear Cs-137 reference source CDCS-J4 have been determined using a well type chamber Standard Imaging HDR-1000 model, which have been calibrated at Secondary Standard Laboratory Calibration of IAEA, whereas two HDR-1000 Plus chambers were calibrated too, following the same standards. The results were compared with Wisconsin University calibration certification and has demonstrated that well type ionization chamber calibration can be used in brachytherapy for several kinds of radionuclides. (Author)

  10. Resistive Plate Chambers performance with Cosmic Rays in the CMS experiment

    CERN Document Server

    Piccolo, D; Genchev, V; Iaydjiev, P; Stoykova, S; Sultanov, G; Trayanov, R; Dimitrov, A; Litov, L; Pavlov, B; Petkov, P; Marinov, A; Thyssen, F; Tytgat, M; Verwilligen, P; Zaganidis, N; Akimenko, S; Ball, A; Crotty, I; Guida, R; Sharma, A; Van Doninck, W; Abbrescia, M; Iaselli, G; Marangelli, B; Nuzzo, S; Pugliese, G; Romano, F; Roselli, G; Trentadue, R; Tupputi, S; Colaleo, A; Loddo, F; Ranieri, A; Cimmino, A; Sciacca, C; Buontempo, S; Cavallo, N; Fabozzi, F; Lomidze, D; Paolucci, P; Benussi, L; Bertani, M; Bianco, S; Colafranceschi, S; Fabbri, F L; Baesso, P; Pagano, D; Ratti, S P; Vitulo, P; Viviani, C; Avila, C; Carrillo, C; Gomez, B; Ocampo, A; Osorio, A; Sanabria, J C; Polese, G; Tuuva, T; Bunkowski, K; Cwiok, M; Doroba, K; Kalinowski, A; Konecki, M; Krolikowski, J; Kierzkowski, K; Kudla, I M; Oklinski, W; Pietrusinski, M; Bluj, M; Fruboes, T; Gorski, M; Kazana, M; Szleper, M; Wrochna, G; Zalewski, P; Poznik, K T; Zabolotny, W; Ban, Y; Qian, S J; Ye, Y L; Ahmad, M; Ahmed, I; Ahmed, W; Asghar, M I; Butt, J B; Hoorani, H R; Hussain, I; Khan, W A; Khurshid, T; Malik, I A; Muhammad, S; Qazi, S F; Shahzad, H; Cho, S W; Jo, M; Hong, B; Kim, C; Kim, H C; Kim, J H; Lee, H S; Lee, K S; Moon, D H; Park, S; Rhee, H B; Seo, E S; Shin, S S; Sim, K S; Lee, J S; Lee, S E

    2010-01-01

    The Resistive Plate Chambers are used in the CMS experiment as a dedicated muon trigger both in barrel and endcap system. About 4000 square meter of double gap RPCs have been produced and have been installed in the experiment since more than one year and half. The full barrel system and a fraction of the endcaps have been monitored to study dark current behaviour and system stability, and have been extensively commissioned with Cosmic Rays collected by the full CMS experiment.

  11. Operation of the multigap resistive plate chamber using a gas mixture free of flammable components

    CERN Document Server

    Akindinov, A; Antonioli, P; Arcelli, S; Basile, M; Cara Romeo, G; Cifarelli, Luisa; Cindolo, F; De Caro, A; De Pasquale, S; Di Bartolomeo, A; Fusco-Girard, M; Golovine, V; Guida, M; Hatzifotiadou, D; Kaidalov, A B; Kim, D H; Kim, D W; Kisselev, S M; Laurenti, G; Lee, K; Lee, S C; Lioublev, E; Luvisetto, M L; Margotti, A; Martemyanov, A N; Nania, R; Noferini, F; Otiougova, P; Pesci, A; Pinazza, O; Polozov, P A; Scapparone, E; Scioli, G; Sellitto, S B; Semeria, F; Smirnitsky, A V; Tchoumakov, M M; Usenko, E; Valenti, G; Voloshin, K G; Williams, M C S; Zagreev, B V; Zampolli, C; Zichichi, A

    2004-01-01

    We have investigated the operation of the multigap resistive plate chamber (MRPC) for the ALICE-TOF system with a gas mixture free of flammable components. Two different gas mixtures, with and without iso-C//4H//1//0 have been used to measure the performance of the MRPC. The efficiency, time resolution, total charge, and the fast to total charge ratio have been found to be comparable.

  12. The multigap resistive plate chamber as a time-of-flight detector

    CERN Document Server

    Akindinov, A; Basile, M; Cerron-Zeballos, E; Cifarelli, Luisa; Cindolo, F; Choi, J; Cozzoni, B; De Caro, A; De Pasquale, S; Kim, D W; Kim, N Y; Klempt, W; Kluge, A; Laurenti, G; Lee, S C; Golovine, V; Hatzifotiadou, D; Martemyanov, A N; Martinengo, P; Pesci, A; Platner, E D; Roberts, J; Seganti, A; Semak, A A; Smirnitsky, A V; Spegel, M; Szymanski, P; Valenti, G; Vicinanza, D; Williams, M C S; Zichichi, A

    2000-01-01

    The goal of this R&D has been to reach the time resolution needed for time-of-flight detectors using the Multigap Resistive Plate Chamber (MRPC). We present here a MRPC with a time resolution of 70 ps. This prototype has been studied within the R&D program for the very large area TOF array of the ALICE experiment at the CERN LHC. (5 refs).

  13. Assembly and tests of Resistive Plate Chambers (RPC) for the CMS barrel detector

    CERN Multimedia

    Gabriella Pugliese, Bari

    2006-01-01

    The pictures 1-3 show some assembly steps of Resistive Plate Chambers in Bari and their tests with cosmic rays (4-6: moving RPC to the test towers; 7-8 cosmic tests). Pictures 9-10 show assembly and tests in Sofia, 11 shows RPC coupling with drift tubes at ISR and 12-13 tests at the CMS site at CERN.

  14. Radiation-hard ceramic Resistive Plate Chambers for forward TOF and T0 systems

    Science.gov (United States)

    Akindinov, A.; Dreyer, J.; Fan, X.; Kämpfer, B.; Kiselev, S.; Kotte, R.; Garcia, A. Laso; Malkevich, D.; Naumann, L.; Nedosekin, A.; Plotnikov, V.; Stach, D.; Sultanov, R.; Voloshin, K.

    2017-02-01

    Resistive Plate Chambers with ceramic electrodes are the main candidates for a use in precise multi-channel timing systems operating in high-radiation conditions. We report the latest R&D results on these detectors aimed to meet the requirements of the forward T0 counter at the CBM experiment. RPC design, gas mixture, limits on the bulk resistivity of ceramic electrodes, efficiency, time resolution, counting rate capabilities and ageing test results are presented.

  15. Performance Study of the CMS Barrel Resistive Plate Chambers with Cosmic Rays

    CERN Document Server

    Chatrchyan, S; Sirunyan, A M; Adam, W; Arnold, B; Bergauer, H; Bergauer, T; Dragicevic, M; Eichberger, M; Erö, J; Friedl, M; Frühwirth, R; Ghete, V M; Hammer, J; Hänsel, S; Hoch, M; Hörmann, N; Hrubec, J; Jeitler, M; Kasieczka, G; Kastner, K; Krammer, M; Liko, D; Magrans de Abril, I; Mikulec, I; Mittermayr, F; Neuherz, B; Oberegger, M; Padrta, M; Pernicka, M; Rohringer, H; Schmid, S; Schöfbeck, R; Schreiner, T; Stark, R; Steininger, H; Strauss, J; Taurok, A; Teischinger, F; Themel, T; Uhl, D; Wagner, P; Waltenberger, W; Walzel, G; Widl, E; Wulz, C E; Chekhovsky, V; Dvornikov, O; Emeliantchik, I; Litomin, A; Makarenko, V; Marfin, I; Mossolov, V; Shumeiko, N; Solin, A; Stefanovitch, R; Suarez Gonzalez, J; Tikhonov, A; Fedorov, A; Karneyeu, A; Korzhik, M; Panov, V; Zuyeuski, R; Kuchinsky, P; Beaumont, W; Benucci, L; Cardaci, M; De Wolf, E A; Delmeire, E; Druzhkin, D; Hashemi, M; Janssen, X; Maes, T; Mucibello, L; Ochesanu, S; Rougny, R; Selvaggi, M; Van Haevermaet, H; Van Mechelen, P; 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Johns, W; Pathak, S; Sheldon, P; Andelin, D; Arenton, M W; Balazs, M; Boutle, S; Buehler, M; Conetti, S; Cox, B; Hirosky, R; Ledovskoy, A; Neu, C; Phillips II, D; Ronquest, M; Yohay, R; Gollapinni, S; Gunthoti, K; Harr, R; Karchin, P E; Mattson, M; Sakharov, A; Anderson, M; Bachtis, M; Bellinger, J N; Carlsmith, D; Crotty, I; Dasu, S; Dutta, S; Efron, J; Feyzi, F; Flood, K; Gray, L; Grogg, K S; Grothe, M; Hall-Wilton, R; Jaworski, M; Klabbers, P; Klukas, J; Lanaro, A; Lazaridis, C; Leonard, J; Loveless, R; Magrans de Abril, M; Mohapatra, A; Ott, G; Polese, G; Reeder, D; Savin, A; Smith, W H; Sourkov, A; Swanson, J; Weinberg, M; Wenman, D; Wensveen, M; White, A

    2010-01-01

    In October and November 2008, the CMS collaboration conducted a programme of cosmic ray data taking, which has recorded about 270 million events. The Resistive Plate Chamber system, which is part of the CMS muon detection system, was successfully operated in the full barrel. More than 98% of the channels were operational during the exercise with typical detection efficiency of 90%. In this paper, the performance of the detector during these dedicated runs is reported.

  16. Studies on fast timing and high precision tracking performance of Resistive Plate Chamber

    CERN Document Server

    Han, L; The ATLAS collaboration

    2013-01-01

    Resistive plate chambers (RPC), produced in large scales, are widely used as trigger detectors with O(ns) time resolution in high energy and high intensity experiments. To confront the future high experimental frontiers, such as the super-LHC, RPCs equipped with fine-pitch readout strips were tested with 180GeV/c muon at CERN SPS H8 beam line, to assess the viability of using RPCs for both fast timing and high precision tracking trigger.

  17. Efficiency determination of resistive plate chambers for fast quasi-monoenergetic neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Roeder, M.; Cowan, T.E.; Kempe, M.; Yakorev, D. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Technische Universitaet Dresden, Dresden (Germany); Elekes, Z. [MTA ATOMKI, Debrecen (Hungary); Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Aumann, T.; Caesar, C. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Technische Universitaet Darmstadt, Darmstadt (Germany); Bemmerer, D.; Sobiella, M.; Stach, D.; Wagner, A. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Boretzky, K.; Hehner, J.; Heil, M. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Maroussov, V. [Universitaet zu Koeln, Koeln (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Nusair, O. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Al-Balqa Applied University, Salt (Jordan); Prokofiev, A.V. [Uppsala University, The Svedberg Laboratory, Uppsala (Sweden); Reifarth, R. [Johann Wolfgang Goethe - Universitaet, Frankfurt am Main (Germany); Zilges, A. [Universitaet zu Koeln, Koeln (Germany); Zuber, K. [Technische Universitaet Dresden, Dresden (Germany); Collaboration: R3B Collaboration

    2014-07-15

    Composite detectors made of stainless-steel converters and multigap resistive plate chambers have been irradiated with quasi-monoenergetic neutrons with a peak energy of 175 MeV. The neutron detection efficiency has been determined using two different methods. The data are in agreement with the output of Monte Carlo simulations. The simulations are then extended to study the response of a hypothetical array made of these detectors to energetic neutrons from a radioactive ion beam experiment. (orig.)

  18. Performance Study of the CMS Barrel Resistive Plate Chambers with Cosmic Rays

    CERN Document Server

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Bendavid, J; Busza, W; Butz, E; Cali, I A; Chan, M; D'Enterria, D; Everaerts, P; Gomez Ceballos, G; Hahn, K A; Harris, P; Jaditz, S; Kim, Y; Klute, M; Lee, Y J; Li, W; Loizides, C; Ma, T; Miller, M; Nahn, S; Paus, C; Roland, C; Roland, G; Rudolph, M; Stephans, G; Sumorok, K; Sung, K; Vaurynovich, S; Wenger, E A; Wyslouch, B; Xie, S; Yilmaz, Y; Yoon, A S; Bailleux, D; Cooper, S I; Cushman, P; Dahmes, B; De Benedetti, A; Dolgopolov, A; Dudero, P R; Egeland, R; Franzoni, G; Haupt, J; Inyakin, A; Klapoetke, K; Kubota, Y; Mans, J; Mirman, N; Petyt, D; Rekovic, V; Rusack, R; Schroeder, M; Singovsky, A; Zhang, J; Cremaldi, L M; Godang, R; Kroeger, R; Perera, L; Rahmat, R; Sanders, D A; Sonnek, P; Summers, D; Bloom, K; Bockelman, B; Bose, S; Butt, J; Claes, D R; Dominguez, A; Eads, M; Keller, J; Kelly, T; Kravchenko, I; Lazo-Flores, J; Lundstedt, C; Malbouisson, H; Malik, S; Snow, G R; Baur, U; Iashvili, I; Kharchilava, A; Kumar, A; Smith, K; Strang, M; Alverson, G; Barberis, E; Boeriu, O; Eulisse, G; Govi, G; McCauley, T; Musienko, Y; Muzaffar, S; Osborne, I; Paul, T; Reucroft, S; Swain, J; Taylor, L; Tuura, L; Anastassov, A; Gobbi, B; Kubik, A; Ofierzynski, R A; Pozdnyakov, A; Schmitt, M; Stoynev, S; Velasco, M; Won, S; Antonelli, L; Berry, D; Hildreth, M; Jessop, C; Karmgard, D J; Kolberg, T; Lannon, K; Lynch, S; Marinelli, N; Morse, D M; Ruchti, R; Slaunwhite, J; Warchol, J; Wayne, M; Bylsma, B; Durkin, L S; Gilmore, J; Gu, J; Killewald, P; Ling, T Y; Williams, G; Adam, N; Berry, E; Elmer, P; Garmash, A; Gerbaudo, D; Halyo, V; Hunt, A; Jones, J; Laird, E; Marlow, D; Medvedeva, T; Mooney, M; Olsen, J; Piroué, P; Stickland, D; Tully, C; Werner, J S; Wildish, T; Xie, Z; Zuranski, A; Acosta, J G; Bonnett Del Alamo, M; Huang, X T; Lopez, A; Mendez, H; Oliveros, S; Ramirez Vargas, J E; Santacruz, N; Zatzerklyany, A; Alagoz, E; Antillon, E; Barnes, V E; Bolla, G; Bortoletto, D; Everett, A; Garfinkel, A F; Gecse, Z; Gutay, L; Ippolito, N; Jones, M; Koybasi, O; Laasanen, A T; Leonardo, N; Liu, C; Maroussov, V; Merkel, P; Miller, D H; Neumeister, N; Sedov, A; Shipsey, I; Yoo, H D; Zheng, Y; Jindal, P; Parashar, N; Cuplov, V; Ecklund, K M; Geurts, F J M; Liu, J H; Maronde, D; Matveev, M; Padley, B P; Redjimi, R; Roberts, J; Sabbatini, L; Tumanov, A; Betchart, B; Bodek, A; Budd, H; Chung, Y S; de Barbaro, P; Demina, R; Flacher, H; Gotra, Y; Harel, A; Korjenevski, S; Miner, D C; Orbaker, D; Petrillo, G; Vishnevskiy, D; Zielinski, M; Bhatti, A; Demortier, L; Goulianos, K; Hatakeyama, K; Lungu, G; Mesropian, C; Yan, M; Atramentov, O; Bartz, E; Gershtein, Y; Halkiadakis, E; Hits, D; Lath, A; Rose, K; Schnetzer, S; Somalwar, S; Stone, R; Thomas, S; Watts, T L; Cerizza, G; Hollingsworth, M; Spanier, S; Yang, Z C; York, A; Asaadi, J; Aurisano, A; Eusebi, R; Golyash, A; Gurrola, A; Kamon, T; Nguyen, C N; Pivarski, J; Safonov, A; Sengupta, S; Toback, D; Weinberger, M; Akchurin, N; Berntzon, L; Gumus, K; Jeong, C; Kim, H; Lee, S W; Popescu, S; Roh, Y; Sill, A; Volobouev, I; Washington, E; Wigmans, R; Yazgan, E; Engh, D; Florez, C; Johns, W; Pathak, S; Sheldon, P; Andelin, D; Arenton, M W; Balazs, M; Boutle, S; Buehler, M; Conetti, S; Cox, B; Hirosky, R; Ledovskoy, A; Neu, C; Phillips II, D; Ronquest, M; Yohay, R; Gollapinni, S; Gunthoti, K; Harr, R; Karchin, P E; Mattson, M; Sakharov, A; Anderson, M; Bachtis, M; Bellinger, J N; Carlsmith, D; Crotty, I; Dasu, S; Dutta, S; Efron, J; Feyzi, F; Flood, K; Gray, L; Grogg, K S; Grothe, M; Hall-Wilton, R; Jaworski, M; Klabbers, P; Klukas, J; Lanaro, A; Lazaridis, C; Leonard, J; Loveless, R; Magrans de Abril, M; Mohapatra, A; Ott, G; Polese, G; Reeder, D; Savin, A; Smith, W H; Sourkov, A; Swanson, J; Weinberg, M; Wenman, D; Wensveen, M; White, A

    2010-01-01

    In October and November 2008, the CMS collaboration conducted a programme of cosmic ray data taking, which has recorded about 270 million events. The Resistive Plate Chamber system, which is part of the CMS muon detection system, was successfully operated in the full barrel. More than 98% of the channels were operational during the exercise with typical detection efficiency of 90%. In this paper, the performance of the detector during these dedicated runs is reported.

  19. Technical Note: Experimental determination of the effective point of measurement of two cylindrical ionization chambers in a clinical proton beam

    Energy Technology Data Exchange (ETDEWEB)

    Sugama, Yuya, E-mail: yuya.sugama@gmail.com [Proton Therapy Center, Aizawa Hospital, Nagano 390-0821, Japan and Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Yamanashi 409-3898 (Japan); Nishio, Teiji [Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima 734-8551 (Japan); Onishi, Hiroshi [Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Yamanashi 409-3898 (Japan)

    2015-07-15

    Purpose: IAEA TRS-398 notes that cylindrical ionization chambers are preferred for reference proton dosimetry. If a cylindrical ionization chamber is used in a phantom to measure the dose as a function of depth, the effective point of measurement (EPOM) must be taken into account. IAEA TRS-398 recommends a displacement of 0.75 times the inner cavity radius (0.75R) for heavy ion beams. Theoretical models by Palmans and by Bhullar and Watchman confirmed this value. However, the experimental results vary from author to author. The purpose of this study is to accurately measure the displacement and explain the past experimental discrepancies. Methods: In this work, we measured the EPOM of cylindrical ionization chambers with high accuracy by comparing the Bragg-peak position obtained with cylindrical ionization chambers (PTW 30013, PTW 31016) to that obtained using a plane-parallel ionization chamber (PTW 34045). Results: The EPOMs of PTW 30013 and 31016 were shifted by 0.92 ± 0.07 R with R = 3.05 mm and 0.90 ± 0.14 R with R = 1.45 mm, respectively, from the reference point toward the source. Conclusions: The EPOMs obtained were greater than the value of 0.75R proposed by the IAEA TRS-398 and the analytical results.

  20. Resistive Plate Chambers commissioning and performance results for 2011-2013.

    CERN Document Server

    CMS Collaboration

    2014-01-01

    Resistive Plate Chambers (RPC) performance results for the period between 2011-2013 are presented. These results include history plots for the RPC relevant variables such as: Cluster Size, Efficiency, percentage of inactive detector during operation, Rates, and Currents. RPC variables are studied as function of relevant parameters such as the averaged instantaneous luminosity of the LHC, time, and CMS cavern pressure. Results obtained with the monitoring tools used by CMS such as the Web Based Monitoring tool (WBM) are also shown. RPC Background rates measured during 2010, 2011, and 2012 are presented and compared. Preparations for the 2015 Run include the installation of a new couple of disks of RPCs in the endcap regions, results obtained during quality control campaigns for the new RPCs are also presented, these results include High voltage scans that probe the quality and standards of the RPC construction procedures, as well as tests on chamber gas leaks and current behavior for the new chambers. Basic p...

  1. Operation, performance and upgrade of the CMS Resistive Plate Chamber system at LHC

    Energy Technology Data Exchange (ETDEWEB)

    Abbrescia, Marcello, E-mail: Marcello.Abbrescia@ba.infn.it

    2013-12-21

    The Resistive Plate Chambers are used in CMS as dedicated muon trigger detectors in both barrel and endcap regions. They also contribute to the identification, reconstruction and tracking of the muons, together with Drift Tubes in the barrel and Cathode Strip Chambers in the endcaps. In this paper a detailed report about the operation and performance of the system after three years of LHC activities with increasing instantaneous luminosity is given. This period allowed to accumulate enough statistics to measure the detector performance with an unprecedented accuracy on such a large amount of chambers. This provided new insights both on the detector fundamentals and on the related operational aspects. Special attention was devoted to the working point calibration procedures and to the stability of the system. A comparison between the initial and present performance is made, and an overview is given of what has been learned in almost three years of operation of one of the largest systems based on RPCs.

  2. Development of special ionization chambers for a quality control program in mammography; Desenvolvimento de camaras de ionizacao especiais para controle de qualidade em mamografia

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Jonas Oliveira da

    2013-07-01

    Mammography is an imaging method that uses X-rays. The use of ionization chambers in mammography quality control programs presents an essential role which is to verify whether the parameters of the patient exposure are correct. However, the commercial ionization chambers for dosimetry in mammography represent a high cost for small and medium size clinics that wish to have this equipment or for professionals that work with quality control programs. The innovative feature of this work was to develop ionization chambers for this purpose. In this work ionization chambers for X radiation beams in the mammography energy range were designed, constructed and characterized. The ionization chambers were tested in standard X radiation beams at the LCI/IPEN. The main characterization tests performed with the ionization chambers were: saturation curve, linearity of response, angular and energy dependence. The response stability tests of the ionization chambers were also conducted at the LCI, presenting results within 2.0 % for long-term stability. The results of the remaining tests are in accordance with international standards. These ionization chambers were also submitted to quality control tests of mammography equipment: linearity of the air kerma rates, determination of half-value layers and mean glandular doses. The results for air kerma rate linearity were less than 10 %, as recommended in international standards. The mean glandular dose obtained with the developed chambers presented values comparable to those of commercial ionization chambers tested, with an estimated variation within international standards. (author)

  3. Assessment of ionization chamber correction factors in photon beams using a time saving strategy with PENELOPE code.

    Science.gov (United States)

    Reis, C Q M; Nicolucci, P

    2016-02-01

    The purpose of this study was to investigate Monte Carlo-based perturbation and beam quality correction factors for ionization chambers in photon beams using a saving time strategy with PENELOPE code. Simulations for calculating absorbed doses to water using full spectra of photon beams impinging the whole water phantom and those using a phase-space file previously stored around the point of interest were performed and compared. The widely used NE2571 ionization chamber was modeled with PENELOPE using data from the literature in order to calculate absorbed doses to the air cavity of the chamber. Absorbed doses to water at reference depth were also calculated for providing the perturbation and beam quality correction factors for that chamber in high energy photon beams. Results obtained in this study show that simulations with phase-space files appropriately stored can be up to ten times shorter than using a full spectrum of photon beams in the input-file. Values of kQ and its components for the NE2571 ionization chamber showed good agreement with published values in the literature and are provided with typical statistical uncertainties of 0.2%. Comparisons to kQ values published in current dosimetry protocols such as the AAPM TG-51 and IAEA TRS-398 showed maximum percentage differences of 0.1% and 0.6% respectively. The proposed strategy presented a significant efficiency gain and can be applied for a variety of ionization chambers and clinical photon beams.

  4. Matrix:. AN Innovative Pixel Ionization Chamber for On-Line Beam Monitoring in Hadrontherapy

    Science.gov (United States)

    Braccini, S.; Pitta', G.; Donetti, M.; Cirio, R.; La Rosa, A.; Garella, M. A.; Giordanengo, S.; Marchetto, F.; Peroni, C.

    2006-04-01

    The control of intensity, position and shape of clinical beams are key issues in the treatment of tumours using hadron beams, especially in the case of active dose distribution systems. For this purpose an innovative pixel ionization chamber, named MATRIX, has been designed, constructed and tested. The chamber is conceived to be located very near the patient to precisely monitor the beam parameters used to verify the treatment planning specifications. MATRIX operates in air and is characterized by a 21 × 21 cm2 sensitive area subdivided in 1024 pixels of 6.5 × 6.5 mm2. To minimize the amount of material crossed by the beam, the anode is made of a 50 μm kapton foil, with a deposit of 17 μm copper on each side. A very sensitive electronics is used for the readout, based on a dedicated chip. In this paper the construction of the chamber and the very positive results of the first beam tests are described.

  5. Evaluation of a special pencil ionization chamber by the Monte Carlo method; Avaliacao de uma camara de ionizacao tipo lapis especial pelo metodo de Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Mendonca, Dalila; Neves, Lucio P.; Perini, Ana P., E-mail: anapaula.perini@ufu.br [Universidade Federal de Uberlandia (INFIS/UFU), Uberlandia, MG (Brazil). Instituto de Fisica; Santos, William S.; Caldas, Linda V.E. [Instituto de Pesquisas Energeticas e Nucleres (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    A special pencil type ionization chamber, developed at the Instituto de Pesquisas Energeticas e Nucleares, was characterized by means of Monte Carlo simulation to determine the influence of its components on its response. The main differences between this ionization chamber and commercial ionization chambers are related to its configuration and constituent materials. The simulations were made employing the MCNP-4C Monte Carlo code. The highest influence was obtained for the body of PMMA: 7.0%. (author)

  6. A new standard cylindrical graphite-walled ionization chamber for dosimetry in 60Co beams at calibration laboratories

    Science.gov (United States)

    Neves, Lucio P.; Perini, Ana P.; Caldas, Linda V. E.

    2014-11-01

    60Co sources are used mostly at dosimetry laboratories for calibration of ionization chambers utilized for radiotherapy dosimetry, mainly in those laboratories where there is no linear accelerator available. In this work, a new cylindrical ionization chamber was developed and characterized to be used as a reference dosimeter at the Calibration Laboratory of the IPEN. The characterization tests were performed according to the IEC 60731 standard, and all tests presented results within its recommended limits. Furthermore, the correction factors for the wall, stem, central collecting electrode, nonaxial uniformity and the mass-energy absorption coefficient were determined using the EGSnrc Monte Carlo code. The air kerma rate determined with this new dosimeter was compared to the one obtained with the IPEN standard, presenting a difference of 1.5%. Therefore, the new ionization chamber prototype developed and characterized in this work presents potential use as a primary standard dosimeter at radiation metrology laboratories.

  7. Determination of small-field correction factors for cylindrical ionization chambers using a semiempirical method

    Science.gov (United States)

    Park, Kwangwoo; Bak, Jino; Park, Sungho; Choi, Wonhoon; Park, Suk Won

    2016-02-01

    A semiempirical method based on the averaging effect of the sensitive volumes of different air-filled ionization chambers (ICs) was employed to approximate the correction factors for beam quality produced from the difference in the sizes of the reference field and small fields. We measured the output factors using several cylindrical ICs and calculated the correction factors using a mathematical method similar to deconvolution; in the method, we modeled the variable and inhomogeneous energy fluence function within the chamber cavity. The parameters of the modeled function and the correction factors were determined by solving a developed system of equations as well as on the basis of the measurement data and the geometry of the chambers. Further, Monte Carlo (MC) computations were performed using the Monaco® treatment planning system to validate the proposed method. The determined correction factors (k{{Q\\text{msr}},Q}{{f\\text{smf}}, {{f}\\text{ref}}} ) were comparable to the values derived from the MC computations performed using Monaco®. For example, for a 6 MV photon beam and a field size of 1  ×  1 cm2, k{{Q\\text{msr}},Q}{{f\\text{smf}}, {{f}\\text{ref}}} was calculated to be 1.125 for a PTW 31010 chamber and 1.022 for a PTW 31016 chamber. On the other hand, the k{{Q\\text{msr}},Q}{{f\\text{smf}}, {{f}\\text{ref}}} values determined from the MC computations were 1.121 and 1.031, respectively; the difference between the proposed method and the MC computation is less than 2%. In addition, we determined the k{{Q\\text{msr}},Q}{{f\\text{smf}}, {{f}\\text{ref}}} values for PTW 30013, PTW 31010, PTW 31016, IBA FC23-C, and IBA CC13 chambers as well. We devised a method for determining k{{Q\\text{msr}},Q}{{f\\text{smf}}, {{f}\\text{ref}}} from both the measurement of the output factors and model-based mathematical computation. The proposed method can be useful in case the MC simulation would not be applicable for the clinical settings.

  8. [Theoretical investigation of the saturation correction for ionization chambers irradiated with pulsed beams of arbitrary pulse length].

    Science.gov (United States)

    Karsch, Leonhard; Pawelke, Jörg

    2014-09-01

    In ionization chambers, not all released charge is collected due to the recombination of charge carriers. This effect is taken into account by the saturation correction factor kS. A physical description of the correction factor has been established for pulsed radiation. However, it is only accurate when the pulse length is short compared with the collection time of the ionization chamber. In this paper we develop a description of the saturation correction for radiation pulses of arbitrary length. For this, a system of partial differential equations is solved iteratively. The numerical solutions are verified experimentally for a Roos ionization chamber (PTW TM34001) exposed to a pulsed electron beam. The results of this iterative procedure describe the experimental data well. The calculations are also possible for beam structures which are experimentally hard to get and thereby contribute to a better understanding and correct description of the saturation correction at arbitrary pulse length. Among other things the pulse length dependent distributions of the charge carriers in the ionization chamber is calculated, inclusive of the transition to the conditions prevailing in the case of continuous irradiation. Furthermore is shown that the formula for kS established by Hochhäuser and Balk is applicable even at arbitrary pulse length, if pulse duration dependent effective values are used for the parameters a and p. These effective values have been determined for the Roos chamber at pulse lengths up to 300 μs.

  9. Performance of a multi-axis ionization chamber array in a 1.5 T magnetic field.

    Science.gov (United States)

    Smit, K; Kok, J G M; Lagendijk, J J W; Raaymakers, B W

    2014-04-07

    At the UMC Utrecht a prototype MR-linac has been installed. The system consists of an 8 MV Elekta linear accelerator and a 1.5 T Philips MRI system. This paper investigates the performance of the IC PROFILER™, a multi-axis ionization chamber array, in a 1.5 T magnetic field. The influence of the magnetic field on the IC PROFILER™ reproducibility, dose response linearity, pulse rate frequency dependence, power to electronics, panel orientation and ionization chamber shape were investigated. The linearity, reproducibility, pulse rate frequency dependence, panel orientation and ionization chamber shape are unaffected by the magnetic field. When the measurements results are normalized to the centre reference chamber, the measurements can commence unaltered. Orientation of the ionization chambers in the magnetic field is of importance, therefore caution must be taken when comparing or normalizing results from several different axes. IC PROFILER™ dose profiles were compared with film dose profiles obtained simultaneously in the MR-linac. Deviation between the film and the IC PROFILER™ data was caused by the noise in the film, indicating correct performance of the IC PROFILER™ in the transverse 1.5 T magnetic field.

  10. Performance of a multi-axis ionization chamber array in a 1.5 T magnetic field

    Science.gov (United States)

    Smit, K.; Kok, J. G. M.; Lagendijk, J. J. W.; Raaymakers, B. W.

    2014-04-01

    At the UMC Utrecht a prototype MR-linac has been installed. The system consists of an 8 MV Elekta linear accelerator and a 1.5 T Philips MRI system. This paper investigates the performance of the IC PROFILER™, a multi-axis ionization chamber array, in a 1.5 T magnetic field. The influence of the magnetic field on the IC PROFILER™ reproducibility, dose response linearity, pulse rate frequency dependence, power to electronics, panel orientation and ionization chamber shape were investigated. The linearity, reproducibility, pulse rate frequency dependence, panel orientation and ionization chamber shape are unaffected by the magnetic field. When the measurements results are normalized to the centre reference chamber, the measurements can commence unaltered. Orientation of the ionization chambers in the magnetic field is of importance, therefore caution must be taken when comparing or normalizing results from several different axes. IC PROFILER™ dose profiles were compared with film dose profiles obtained simultaneously in the MR-linac. Deviation between the film and the IC PROFILER™ data was caused by the noise in the film, indicating correct performance of the IC PROFILER™ in the transverse 1.5 T magnetic field.

  11. A general algorithm for calculation of recombination losses in ionization chambers exposed to ion beams

    CERN Document Server

    Christensen, Jeppe brage; Bassler, Niels

    2016-01-01

    Dosimetry with ionization chambers in clinical ion beams for radiation therapy requires correction for recombination effects. However, common radiation protocols discriminate between initial and general recombination and provide no universal correction method for the presence of both recombination types in ion beams of charged particles heavier than protons. Here, we present the open source code IonTracks, where the combined initial and general recombination effects in principle can be predicted for any ion beam with arbitrary particle-energy spectrum and temporal structure. IonTracks uses track structure theory to distribute the charge carriers in ion tracks. The charge carrier movements are governed by a pair of coupled differential equations, based on fundamental physical properties as charge carrier drift, diffusion, and recombination, which are solved numerically while the initial and general charge carrier recombination is computed. The algorithm is numerically stable and in accordance with experimental...

  12. A large area position-sensitive ionization chamber for heavy-ion-induced reaction studies

    Energy Technology Data Exchange (ETDEWEB)

    Pant, L.M. E-mail: lalit.pant@exp2.physik.uni-giessen.de; Biswas, D.C.; Dinesh, B.V.; Thomas, R.G.; Saxena, A.; Sawant, Y.S.; Choudhury, R.K

    2002-12-11

    A large area position-sensitive ionization chamber with a wide dynamic range has been developed to measure the mass, charge and energy of the heavy ions and the fission fragments produced in heavy-ion-induced reactions. The split anode geometry of the detector makes it suitable for both particle identification and energy measurements for heavy ions and fission fragments. The detector has been tested with {alpha} particles from {sup 241}Am-{sup 239}Pu source, fission fragments from {sup 252}Cf and the heavy-ion beams from the 14UD Mumbai Pelletron accelerator facility. Using this detector, measurements on mass and total kinetic energy distributions in heavy-ion-induced fusion-fission reactions have been carried out for a wide range of excitation energies. Results on deep inelastic collisions and mass-energy correlations on different systems using this detector setup are discussed.

  13. Improved design and construction of an ionization chamber for the CSNS beam loss monitor (BLM)

    Institute of Scientific and Technical Information of China (English)

    TIAN Jian-Min; XU Mei-Hang; ZHAO Zhong-Liang; CHEN Chang; RUAN Xiang-Dong; CHEN Yuan-Bo; XU Tao-Guang; LU Shuang-Tong

    2012-01-01

    Based on the first ionization chamber (IC) prototype,the structure,working gas component and electrode material of the IC are improved.The test of the improved IC shows that the plateau length is about 2000 V,the plateau slope is less than 0.2%/100 V,the sensitivity is 19.6 pA/rad.h-1,the up-limitation of the linearity can be up to 3.6× 105 rad/h,and the applied voltage can be operated to 3500 V.The test results show that the performance of the improved IC meets the requirements of the beam loss monitor.

  14. A new multi-strip ionization chamber used as online beam monitor for heavy ion therapy

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Zhiguo [Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Rd., Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Mao, Ruishi [Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Rd., Lanzhou 730000 (China); Duan, Limin, E-mail: lmduan@impcas.ac.cn [Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Rd., Lanzhou 730000 (China); She, Qianshun; Hu, Zhengguo; Li, He; Lu, Ziwei; Zhao, Qiecheng; Yang, Herun; Su, Hong; Lu, Chengui; Hu, Rongjiang; Zhang, Junwei [Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Rd., Lanzhou 730000 (China)

    2013-11-21

    A multi-strip ionization chamber has been built for precise and fast monitoring of the carbon beam spatial distribution at Heavy Ion Researched Facility of Lanzhou Cooling Storing Ring (HIRFL-CSR). All the detector's anode, cathode and sealed windows are made by 2μm aluminized Mylar film in order to minimize the beam lateral deflection. The sensitive area of the detector is (100×100)mm{sup 2}, with the anode segmented in 100 strips, and specialized front-end electronics has been developed for simplifying the data acquisition and quick feedback of the relevant parameters to beam control system. It can complete one single beam profile in 200μs.

  15. A large area position-sensitive ionization chamber for heavy-ion-induced reaction studies

    CERN Document Server

    Pant, L M; Dinesh, B V; Thomas, R G; Saxena, A; Sawant, Y S; Choudhury, R K

    2002-01-01

    A large area position-sensitive ionization chamber with a wide dynamic range has been developed to measure the mass, charge and energy of the heavy ions and the fission fragments produced in heavy-ion-induced reactions. The split anode geometry of the detector makes it suitable for both particle identification and energy measurements for heavy ions and fission fragments. The detector has been tested with alpha particles from sup 2 sup 4 sup 1 Am- sup 2 sup 3 sup 9 Pu source, fission fragments from sup 2 sup 5 sup 2 Cf and the heavy-ion beams from the 14UD Mumbai Pelletron accelerator facility. Using this detector, measurements on mass and total kinetic energy distributions in heavy-ion-induced fusion-fission reactions have been carried out for a wide range of excitation energies. Results on deep inelastic collisions and mass-energy correlations on different systems using this detector setup are discussed.

  16. Comparison of pencil-type ionization chamber calibration results and methods between dosimetry laboratories.

    Science.gov (United States)

    Hourdakis, Costas J; Büermann, Ludwig; Ciraj-Bjelac, Olivera; Csete, Istvan; Delis, Harry; Gomola, Igor; Persson, Linda; Novak, Leos; Petkov, Ivailo; Toroi, Paula

    2016-01-01

    A comparison of calibration results and procedures in terms of air kerma length product, PKL, and air kerma, K, was conducted between eight dosimetry laboratories. A pencil-type ionization chamber (IC), generally used for computed tomography dose measurements, was calibrated according to three calibration methods, while its residual signal and other characteristics (sensitivity profile, active length) were assessed. The results showed that the "partial irradiation method" is the preferred method for the pencil-type IC calibration in terms of PKL and it could be applied by the calibration laboratories successfully. Most of the participating laboratories achieved high level of agreement (>99%) for both dosimetry quantities (PKL and K). Estimated relative standard uncertainties of comparison results vary among laboratories from 0.34% to 2.32% depending on the quantity, beam quality and calibration method applied. Detailed analysis of the assigned uncertainties have been presented and discussed.

  17. Ionization chamber array for patient specific VMAT, Tomotherapy and IMRT QA

    Energy Technology Data Exchange (ETDEWEB)

    Stathakis, Sotiri, E-mail: Stathakis@uthscsa.ed [Department of Radiation Oncology, Cancer Therapy and Research Center at the University of Texas Health Science Center, San Antonio TX 78229 (United States)

    2010-11-01

    The evaluation between measured and calculated dose is essential in the patient specific quality assurance procedures for intensity modulated radiation therapy. The high complexity of volumetric arc radiotherapy, Tomotherpay and intensity modulated radiation therapy deliveries attributed to the dynamic and synchronization requirements of such techniques require new methods and potentially new tools for the quality assurance of such techniques. Studies evaluating the dosimetric performance of EDR2 film and a 2D ionization chamber array quality assurance device have been performed in our institution. Our results showed that differences between the detector systems are small. The respective gamma index histograms showed that when 3% dose difference and 3mm distance to agreement are used, more than 90% of the evaluated points were within the tolerance criteria

  18. Performance of a Large Area Avalanche Photodiode in a Liquid Xenon Ionization and Scintillation Chamber

    CERN Document Server

    Ni, K; Day, D; Giboni, K L; Lopes, J A M; Majewski, P; Yamashita, M

    2005-01-01

    Scintillation light produced in liquid xenon (LXe) by alpha particles, electrons and gamma-rays was detected with a large area avalanche photodiode (LAAPD) immersed in the liquid. The alpha scintillation yield was measured as a function of applied electric field. We estimate the quantum efficiency of the LAAPD to be 45%. The best energy resolution from the light measurement at zero electric field is 7.5%(sigma) for 976 keV internal conversion electrons from Bi-207 and 2.6%(sigma) for 5.5 MeV alpha particles from Am-241. The detector used for these measurements was also operated as a gridded ionization chamber to measure the charge yield. We confirm that using a LAAPD in LXe does not introduce impurities which inhibit the drifting of free electrons.

  19. Unexpected bias in NIST 4πγ ionization chamber measurements.

    Science.gov (United States)

    Unterweger, M P; Fitzgerald, R

    2012-09-01

    In January of 2010, it was discovered that the source holder used for calibrations in the NIST 4πγ ionization chamber (IC) has not been stable. The positioning ring that determines the height of the sample in the reentrant tube of the IC has slowly shifted during 35 years of use. This has led to a slow change in the calibration factors for the various radionuclides measured by this instrument. The changes are dependent on γ-ray energy and the time the IC was calibrated for a given radionuclide. A review of the historic data with regard to when the calibrations were done has enabled us to approximate the magnitude of the changes with time. This requires a number of assumptions, and corresponding uncertainty components, including whether the changes in height were gradual or in steps as will be shown in drawings of sample holder. For calibrations the changes in calibration factors have been most significant for low energy gamma emitters such as (133)Xe, (241)Am, (125)I and (85)Kr. The corrections to previous calibrations can be approximated and the results corrected with an increase in the overall uncertainty. At present we are recalibrating the IC based on new primary measurements of the radionuclides measured on the IC. Likewise we have been calibrating a new automated ionization-chamber system. A bigger problem is the significant number of half-life results NIST has published over the last 35 years that are based on IC measurements. The effect on half-life is largest for long-lived radionuclei, especially low-energy γ-ray emitters. This presentation will review our results and recommend changes in values and/or uncertainties. Any recommendation for withdrawal of any results will also be undertaken.

  20. Dependence with air density of the response of the PTW SourceCheck ionization chamber for low energy brachytherapy sources

    Energy Technology Data Exchange (ETDEWEB)

    Tornero-López, Ana M.; Guirado, Damián; Ruiz-Arrebola, Samuel [Servicio de Radiofísica y Protección Radiológica, Hospital Universitario San Cecilio, E-18012 Granada (Spain); Perez-Calatayud, Jose [Servicio de Radioterapia, Unidad de Radiofísica, Hospital Universitario y Politécnico La Fe, E-46026 Valencia (Spain); Simancas, Fernando; Lallena, Antonio M. [Departamento de Física Atómica, Molecular y Nuclear, Universidad de Granada, E-18071 Granada (Spain); Gazdic-Santic, Maja [Department of Medical Physics and Radiation Safety, Clinical Centre of Sarajevo University, 71000 Sarajevo (Bosnia and Herzegovina)

    2013-12-15

    Purpose: Air-communicating well ionization chambers are commonly used to assess air kerma strength of sources used in brachytherapy. The signal produced is supposed to be proportional to the air density within the chamber and, therefore, a density-independent air kerma strength is obtained when the measurement is corrected to standard atmospheric conditions using the usual temperature and pressure correction factor. Nevertheless, when assessing low energy sources, the ionization chambers may not fulfill that condition and a residual density dependence still remains after correction. In this work, the authors examined the behavior of the PTW 34051 SourceCheck ionization chamber when measuring the air kerma strength of {sup 125}I seeds.Methods: Four different SourceCheck chambers were analyzed. With each one of them, two series of measurements of the air kerma strength for {sup 125}I selectSeed{sup TM} brachytherapy sources were performed inside a pressure chamber and varying the pressure in a range from 747 to 1040 hPa (560 to 780 mm Hg). The temperature and relative humidity were kept basically constant. An analogous experiment was performed by taking measurements at different altitudes above sea level.Results: Contrary to other well-known ionization chambers, like the HDR1000 PLUS, in which the temperature-pressure correction factor overcorrects the measurements, in the SourceCheck ionization chamber they are undercorrected. At a typical atmospheric situation of 933 hPa (700 mm Hg) and 20 °C, this undercorrection turns out to be 1.5%. Corrected measurements show a residual linear dependence on the density and, as a consequence, an additional density dependent correction must be applied. The slope of this residual linear density dependence is different for each SourceCheck chamber investigated. The results obtained by taking measurements at different altitudes are compatible with those obtained with the pressure chamber.Conclusions: Variations of the altitude and

  1. Scintillation properties of N2 and CF4 and performances of a scintillating ionization chamber

    Science.gov (United States)

    Lehaut, G.; Salvador, S.; Fontbonne, J.-M.; Lecolley, F.-R.; Perronnel, J.; Vandamme, Ch.

    2015-10-01

    In this work, we studied the emission yields, decay times and coincidence resolving times (CRT) of two gases, nitrogen (N2) and tetrafluoromethane (CF4), used for particle detection in the context of fission products measurement. The set-up was made of an ionization chamber and two photomultiplier tubes (PMTs) placed front-to-front on each side of the active zone of the chamber. Using the photomultiplier tubes, the number of photoelectrons (phe) converted at the photocathodes from the scintillation processes in each gas was quantified and the scintillation time spectra were recorded. A scintillation emission yield of 24 phe MeV-1 with a decay time of τd = 2.5 ns in N2, and 225 phe MeV-1 with τd = 6.2 ns for CF4, has been measured. With our set-up, the coincidence resolving time (σ values) between the two PMTs have been measured using alpha particles at 1.4 ns and 0.34 ns for N2 and CF4, respectively.

  2. Multiple sampling ionization chamber (MUSIC) for measuring the charge of relativistic heavy ions

    Energy Technology Data Exchange (ETDEWEB)

    Christie, W.B.; Romero, J.L.; Brady, F.P.; Tull, C.E.; Castaneda, C.M.; Barasch, E.F.; Webb, M.L.; Drummond, J.R.; Crawford, H.J.; Flores, I.

    1987-04-01

    A large area (1 m x 2 m) multiple sampling ionization chamber (MUSIC) has been constructed and tested. The MUSIC detector makes multiple measurements of energy 'loss', dE/dx, for a relativistic heavy ion. Given the velocity, the charge of the ion can be extracted from the energy loss distributions. The widths of the distributions we observe are much narrower than predicted by Vavilov's theory for energy loss while agreeing well with the theory of Badhwar which deals with the energy deposited. The versatile design of MUSIC allows a variety of anode configurations which results in a large dynamic range of charge. In our tests to date we have observed charge resolutions of 0.25e fwhm for 727 MeV/nucleon /sup 40/Ar and 0.30e fwhm for 1.08 GeV/nucleon /sup 139/La and /sup 139/La fragments. Vertical position and multiple track determination are obtained by using time projection chamber electronics. Preliminary tests indicate that the position resolution is also very good with sigmaapprox. =100 ..mu..m.

  3. Fast-neutron spectrometry using a ³He ionization chamber and digital pulse shape analysis.

    Science.gov (United States)

    Chichester, D L; Johnson, J T; Seabury, E H

    2012-08-01

    Digital pulse shape analysis (dPSA) has been used with a Cuttler-Shalev type (3)He ionization chamber to measure the fast-neutron spectra of a deuterium-deuterium electronic neutron generator, a bare (252)Cf spontaneous fission neutron source, and of the transmitted fast neutron spectra of a (252)Cf source attenuated by water, graphite, liquid nitrogen, and magnesium. Rise-time dPSA has been employed using the common approach for analyzing n +(3)He→(1)H+(3)H ionization events and improved to account for wall-effect and pile-up events, increasing the fidelity of these measurements. Simulations have been performed of the different experimental arrangements and compared with the measurements, demonstrating general agreement between the dPSA-processed fast-neutron spectra and predictions. The fast-neutron resonance features of the attenuation cross sections of the attenuating materials are clearly visible within the resolution limits of the electronics used for the measurements, and the potential applications of high-resolution fast-neutron spectrometry for nuclear nonproliferation and safeguards measurements are discussed.

  4. Accurate simulation of ionization chamber response with the Monte Carlo code PENELOPE

    Energy Technology Data Exchange (ETDEWEB)

    Sempau, Josep [Technical University of Catalonia (Spain)

    2010-07-01

    Full text. Ionization chambers (IC) are routinely used in hospitals for the dosimetry of the photon and electron beams used for radiotherapy treatments. The determination of absorbed dose to water from the absorbed dose to the air filling the cavity requires the introduction of stopping power ratios and perturbation factors, which account for the disturbance caused by the presence of the chamber. Although this may seem a problem readily amenable to Monte Carlo simulation, the fact is that the accurate determination of IC response has been, during the last 20 years, one of the most important challenges of the simulation of electromagnetic showers. The main difficulty stems from the use of condensed history techniques for electron and positron transport. This approach, which involves grouping a large number of interactions into a single artificial event, is known to produce the so-called interface effects when particles travel across surfaces separating different media. These effects are extremely important when the electron step length is not negligible compared to the size of the region being crossed, as it is the case with the cavity of an IC. The artifact, which becomes apparent when the chamber response shows a marked dependence on the adopted step size, can be palliated with the use of sophisticated electron transport algorithms. These topics will be discussed in the context of the transport model implemented in the Penelope code. The degree of violation of the Fano theorem for a simple, planar geometry, will be used as a measure of the stability of the algorithm with respect to variations of the electron step length, thus assessing the 'quality' of its condensed history scheme. It will be shown that, with a suitable choice of transport parameters, Penelope can simulate IC response with an accuracy of the order of 0.1%. (author)

  5. Eco-friendly gas mixtures for Resistive Plate Chambers based on tetrafluoropropene and Helium

    Science.gov (United States)

    Abbrescia, M.; Benussi, L.; Piccolo, D.; Bianco, S.; Ferrini, M.; Muhammad, S.; Passamonti, L.; Pierluigi, D.; Piccolo, D.; Primavera, F.; Russo, A.; Saviano, G.

    2016-08-01

    Due to the recent restrictions deriving from the application of the Kyoto protocol, the main components of the gas mixtures presently used in the Resistive Plate Chambers systems of the LHC experiments will be most probably phased out of production in the coming years. Identifying possible replacements with the adequate characteristics requires an intense R&D activity, which was recently started, in collaborations with various experiments. Possible new gases have been proposed and are thoroughly investigated. Some tests on one of the most promising candidate—HFO-1234ze, an allotropic form of tetrafluoropropane—have already been reported. Here an innovative approach, based on the use of Helium, to solve the problem related to the high operating voltage needed to operate the chambers with HFO-1234ze based gas mixtures, is discussed and the first results are shown.

  6. A convolution model for obtaining the response of an ionization chamber in static non standard fields

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Castano, D. M.; Gonzalez, L. Brualla; Gago-Arias, M. A.; Pardo-Montero, J.; Gomez, F.; Luna-Vega, V.; Sanchez, M.; Lobato, R. [Radiation Physics Laboratory, Universidad de Santiago de Compostela, 15782 (Spain) and Dpto de Fisica de Particulas, Universidad de Santiago de Compostela, 15782 (Spain); Servicio de Radiofisica ERESA, Consorcio Hospital General Universitario de Valencia, 46014 (Spain); Dpto de Fisica de Particulas, Universidad de Santiago de Compostela, 15782 (Spain); Radiation Physics Laboratory, Universidad de Santiago de Compostela, 15782 Spain and Dpto de Fisica de Particulas, Universidad de Santiago de Compostela, 15782 (Spain); Servicio de Radiofisica y Proteccion Radiologica, Hospital Clinico Universitario de Santiago, Santiago de Compostela, 15782 (Spain)

    2012-01-15

    Purpose: This work contains an alternative methodology for obtaining correction factors for ionization chamber (IC) dosimetry of small fields and composite fields such as IMRT. The method is based on the convolution/superposition (C/S) of an IC response function (RF) with the dose distribution in a certain plane which includes chamber position. This method is an alternative to the full Monte Carlo (MC) approach that has been used previously by many authors for the same objective. Methods: The readout of an IC at a point inside a phantom irradiated by a certain beam can be obtained as the convolution of the dose spatial distribution caused by the beam and the IC two-dimensional RF. The proposed methodology has been applied successfully to predict the response of a PTW 30013 IC when measuring different nonreference fields, namely: output factors of 6 MV small fields, beam profiles of cobalt 60 narrow fields and 6 MV radiosurgery segments. The two-dimensional RF of a PTW 30013 IC was obtained by MC simulation of the absorbed dose to cavity air when the IC was scanned by a 0.6 x 0.6 mm{sup 2} cross section parallel pencil beam at low depth in a water phantom. For each of the cases studied, the results of the IC direct measurement were compared with the corresponding obtained by the C/S method. Results: For all of the cases studied, the agreement between the IC direct measurement and the IC calculated response was excellent (better than 1.5%). Conclusions: This method could be implemented in TPS in order to calculate dosimetry correction factors when an experimental IMRT treatment verification with in-phantom ionization chamber is performed. The miss-response of the IC due to the nonreference conditions could be quickly corrected by this method rather than employing MC derived correction factors. This method can be considered as an alternative to the plan-class associated correction factors proposed recently as part of an IAEA work group on nonstandard field dosimetry.

  7. Effect of the linseed oil surface treatment on the performance of resistive plate chambers

    Science.gov (United States)

    Abbrescia, M.; Colaleo, A.; Iaselli, G.; Maggi, M.; Marangelli, B.; Natali, S.; Nuzzo, S.; Ranieri, A.; Romano, F.; Arena, V.; Bonomi, G.; Braj, A.; Gianini, G.; Liguori, G.; Ratti, S. P.; Riccardi, C.; Viola, L.; Vitulo, P.

    1997-02-01

    Results on the behaviour of several bakelite Resistive Plate Chambers (RPCs) without the linseed oil treatment of the internal electrodes will be presented. Efficiency, collected charge and cluster size distributions will be compared to the ones of a standard oiled RPC. Currents and single rate are the quantities most affected by the surface treatment of the electrodes beyond the optical/mechanical properties. A factor 4 less in currents and at least a factor 10 less in single rate is achieved using standard oiled RPCs operated in streamer mode.

  8. Aging study for resistive plate chambers of the CMS muon trigger detector

    CERN Document Server

    Abbrescia, M; Iaselli, G; Loddo, F; Maggi, M; Marangelli, B; Natali, S; Nuzzo, S; Pugliese, G; Ranieri, A; Romano, F; Altieri, S; Belli, G; Bruno, G; Guida, R; Ratti, S P; Riccardi, C; Torre, P; Vitulo, P

    2003-01-01

    A long-term aging test of a Resistive Plate Chamber (RPC) was carried out with an intense gamma **1**3**7Cs source. The detector was operated in avalanche mode and had the bakelite surface treated with linseed oil. After the irradiation the estimated dose, charge and fluence were approximately equal to the expected values after 10 years of operation in the CMS barrel region. During and after the irradiation, the RPC performance was monitored with cosmic muons and showed no relevant aging effects. Moreover, no variation of the bakelite resistance was observed.

  9. Development of Multi-gap Resistive Plate Chamber (MRPC) for medical imaging

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, A.; Roy, A. [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata 700 064 (India); Biswas, S., E-mail: saikat.ino@gmail.com [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata 700 064 (India); GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt 64291 (Germany); Chattopadhyay, S.; Das, G.; Pal, S. [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata 700 064 (India)

    2013-08-01

    The low cost and high resolution Multi-gap Resistive Plate Chamber (MRPC) opens up a new possibility to find an efficient alternative detector for the Time of Flight (TOF) based Positron Emission Tomography, where the sensitivity of the system depends largely on the time resolution of the detector. In a layered structure, suitable converters can be used to increase the photon detection efficiency. In this paper results of the cosmic ray test of a four-gap bakelite-based prototype MRPC operated in streamer mode and six-gap glass-based MRPC operated in avalanche mode are discussed.

  10. A multigap resistive plate chamber array for the Extreme Energy Events project

    Science.gov (United States)

    De Gruttola, D.; Abbrescia, M.; Agocs, A.; Aiola, S.; Antolini, R.; Avanzini, C.; Baldini Ferroli, R.; Bencivenni, G.; Bossini, E.; Bressan, E.; Chiavassa, A.; Cicalò, C.; Cifarelli, L.; Coccia, E.; De Pasquale, S.; Di Giovanni, A.; D'Incecco, M.; Dreucci, M.; Fabbri, F. L.; Frolov, V.; Garbini, M.; Gemme, G.; Gnesi, I.; Gustavino, C.; Hatzifotiadou, D.; La Rocca, P.; Li, S.; Librizzi, F.; Maggiora, A.; Massai, M.; Miozzi, S.; Panareo, M.; Paoletti, R.; Perasso, L.; Pilo, F.; Piragino, G.; Regano, A.; Riggi, F.; Righini, G. C.; Sartorelli, G.; Scapparone, E.; Scribano, A.; Selvi, M.; Serci, S.; Siddi, E.; Spandre, G.; Squarcia, S.; Taiuti, M.; Tosello, F.; Votano, L.; Williams, M. C. S.; Yanez, G.; Zichichi, A.; Zouyevski, R.

    2014-10-01

    The Extreme Energy Events (EEE) Project is a Centro Fermi - CERN - INFN - MIUR Collaboration Project for the study of extremely high energy cosmic rays, which exploits the Multigap Resistive Plate Chamber (MRPC) technology. The excellent time resolution and good tracking capability of this kind of detector allows us to study Extensive Air Showers (EAS) with an array of MRPC telescopes distributed across the Italian territory. Each telescope is installed in a high school, with the further goal to introduce students to particle and astroparticle Physics. The status of the experiment and the results obtained are reported.

  11. GEANT4 simulation of gamma ray in a double-gap resistive plate chamber

    Institute of Scientific and Technical Information of China (English)

    J. T. Rhee; M. Jamil; Steve Hall; Y. J. Jeon

    2006-01-01

    For more than 20 years nuclear physicists have used the GEANT code to simulate particle-matter interaction. In most recent version, GEANT4 is a toolkit for simulating the passage of particles though matter, which contains a complete range of functionality including tracking, geometry, physics models, and hits. In this article, an attempt to use GEANT4 to model a double-gap resistive plate chamber (RFC) with its improved efficiency is presented. The efficiencies of the double-gap RFC have been evaluated as a function of gamma energy range 0.005-1OOOMeV. A comparison to available previous simulation package GEANT3 data is also performed.

  12. The EEE Project: Cosmic rays, multigap resistive plate chambers and high school students

    CERN Document Server

    Abbrescia, M.; Antolini, R; Avanzini, C; Baldini Ferroli, R; Bencivenni, G; Bossini, E; Bressan, E; Chiavassa, A; Cicalo, C; Cifarelli, L; Coccia, E; De Gruttula, D; De Pasquale, S; Di Giovanni, A; D'Incecco, M; Doroud, K; Dreucci, M; Fabbri, FL; Frolov, V; Garbini, M; Gemme, G; Gnesi, I; Gustavino, C; Hatzifotiadu, D; La Rocca, P; Li, S; Moro, R; Miozzi, S; Massai, M; Maggiora, A; Librizzi, F; Piragino, G; Pilo, F; Perasso, L; Paoletti, R; Righini, GC; Scapparone, E; Sartorelli, G; Romano, F; Serci, S; Selvi, M; Scribano, A; Riggi, F; Regano, A; Squarcia, S; Spandre, G; Toselli, F; Taiuti, M; Zichichi, A; Zouyevski, R; Williams, MCS; Votano, L; Siddi, E; Panareo, M

    2012-01-01

    The Gas Gain Monitoring (GGM) system of the Resistive Plate Chamber (RPC) muon detector in the Compact Muon Solenoid (CMS) experiment provides fast and accurate determination of the stability in the working point conditions due to gas mixture changes in the closed loop recirculation system. In 2011 the GGM began to operate using a feedback algorithm to control the applied voltage, in order to keep the GGM response insensitive to environmental temperature and atmospheric pressure variations. Recent results are presented on the feedback method used and on alternative algorithms.

  13. Design and preliminary test of a free-air ionization chamber for low-energy X-ray

    Institute of Scientific and Technical Information of China (English)

    吴金杰; 杨元第; 王培玮; 陈靖; 柳加成

    2011-01-01

    A free-air ionization chamber in low-energy X-ray has been designed and manufactured at the National Institute of Metrology (NIM, China) according to the defination of air-kerma. The results of a preliminary test show that the leakage current of ionizatio

  14. Consequences of air around an ionization chamber : Are existing solid phantoms suitable for reference dosimetry on an MR-linac?

    NARCIS (Netherlands)

    Hackett, S. L.; Van Asselen, B.; Wolthaus, J. W H; Kok, J. G M; Woodings, S. J.; Lagendijk, J. J W; Raaymakers, B. W.

    2016-01-01

    Purpose: A protocol for reference dosimetry for the MR-linac is under development. The 1.5 T magnetic field changes the mean path length of electrons in an air-filled ionization chamber but has little effect on the electron trajectories in a surrounding phantom. It is therefore necessary to correct

  15. An allene-doped liquid argon ionization chamber for Ar and Ca ions at around 100 MeV/n

    CERN Document Server

    Yunoki, A; Fukuda, N; Kase, M; Kato, T; Kikuchi, J; Masuda, K; Niimura, M; Okada, H; Ozaki, K; Piao, Y; Shibamura, E; Tanaka, M; Tanihata, I; Terasawa, K

    1999-01-01

    An allene-doped liquid argon ionization chamber with 48 mmx48 mmx40 mm sensitive volume has been constructed for precise energy measurement of heavy ions at around 100 MeV/n. An energy resolution of 0.6%-0.7% (FWHM) was achieved for Ca and Ar ions both at 78 MeV/n. (author)

  16. A two-dose-rate method for general recombination correction for liquid ionization chambers in pulsed beams

    Energy Technology Data Exchange (ETDEWEB)

    Toelli, Heikki; Sjoegren, Rickard; Wendelsten, Mikael, E-mail: heikki.tolli@radfys.umu.s [Department of Radiation Sciences, Radiation Physics, Umeaa University, SE-901 85 Umeaa (Sweden)

    2010-08-07

    The correction for general recombination losses in liquid ionization chambers (LICs) is more complex than that in air-filled ionization chambers. The reason for this is that the saturation charge in LICs, i.e. the charge that escapes initial recombination, depends on the applied voltage. This paper presents a method, based on measurements at two different dose rates in a pulsed beam, for general recombination correction in LICs. The Boag theory for pulsed beams is used and the collection efficiency is determined by numerical methods which are equivalent to the two-voltage method used in dosimetry with air-filled ionization chambers. The method has been tested in experiments in water in a 20 MeV electron beam using two LICs filled with isooctane and tetramethylsilane. The dose per pulse in the electron beam was varied between 0.1 mGy/pulse and 8 mGy/pulse. The relative standard deviations of the collection efficiencies determined with the two-dose-rate method ranged between 0.1% and 1.5%. The dose-rate variations of the general recombination corrected charge measured with the LICs are in excellent agreement with the corresponding values obtained with an air-filled plane parallel ionization chamber.

  17. Source geometry factors for HDR ¹⁹²Ir brachytherapy secondary standard well-type ionization chamber calibrations.

    Science.gov (United States)

    Shipley, D R; Sander, T; Nutbrown, R F

    2015-03-21

    Well-type ionization chambers are used for measuring the source strength of radioactive brachytherapy sources before clinical use. Initially, the well chambers are calibrated against a suitable national standard. For high dose rate (HDR) (192)Ir, this calibration is usually a two-step process. Firstly, the calibration source is traceably calibrated against an air kerma primary standard in terms of either reference air kerma rate or air kerma strength. The calibrated (192)Ir source is then used to calibrate the secondary standard well-type ionization chamber. Calibration laboratories are usually only equipped with one type of HDR (192)Ir source. If the clinical source type is different from that used for the calibration of the well chamber at the standards laboratory, a source geometry factor, k(sg), is required to correct the calibration coefficient for any change of the well chamber response due to geometric differences between the sources. In this work we present source geometry factors for six different HDR (192)Ir brachytherapy sources which have been determined using Monte Carlo techniques for a specific ionization chamber, the Standard Imaging HDR 1000 Plus well chamber with a type 70010 HDR iridium source holder. The calculated correction factors were normalized to the old and new type of calibration source used at the National Physical Laboratory. With the old Nucletron microSelectron-v1 (classic) HDR (192)Ir calibration source, ksg was found to be in the range 0.983 to 0.999 and with the new Isodose Control HDR (192)Ir Flexisource k(sg) was found to be in the range 0.987 to 1.004 with a relative uncertainty of 0.4% (k = 2). Source geometry factors for different combinations of calibration sources, clinical sources, well chambers and associated source holders, can be calculated with the formalism discussed in this paper.

  18. High-resolution ion pulse ionization chamber with air filling for the {sup 222}Rn decays detection

    Energy Technology Data Exchange (ETDEWEB)

    Gavrilyuk, Yu.M.; Gangapshev, A.M.; Gezhaev, A.M.; Etezov, R.A.; Kazalov, V.V.; Kuzminov, V.V. [Baksan Neutrino Observatory,Institute for Nuclear Research RAS, 361609 Neutrino (Russian Federation); Panasenko, S.I. [V.N.Karazin Kharkiv National University, 61022 Kharkiv (Ukraine); Ratkevich, S.S., E-mail: ssratk@gmail.com [V.N.Karazin Kharkiv National University, 61022 Kharkiv (Ukraine); Tekueva, D.A.; Yakimenko, S.P. [Baksan Neutrino Observatory,Institute for Nuclear Research RAS, 361609 Neutrino (Russian Federation)

    2015-11-21

    The construction and characteristics of the cylindrical ion pulse ionization chamber (CIPIC) with a working volume of 3.2 L are described. The chamber is intended to register α-particles from the {sup 222}Rn and its daughter's decays in the filled air sample. The detector is less sensitive to electromagnetic pick-ups and mechanical noises. The digital pulse processing method is proposed to improve the energy resolution of the ion pulse ionization chamber. An energy resolution of 1.6% has been achieved for the 5.49 MeV α-line. The dependence of the energy resolution on high voltage and working media pressure has been investigated and the results are presented. - Highlights: • The construction and characteristics of the cylindrical ion pulse ionization chamber (CIPIC) with a working volume of 3.2 L are described. • The chamber is intended to register alpha-particles from {sup 222}Rn and its daughter's decays in the filled air sample. • The detector is less sensitive to electromagnetic pick-ups and mechanical noises. • An energy resolution of 1.6% has been achieved for the 5.49 MeV alpha-line. The dependence of the energy resolution on high voltage and working media pressure have been investigated and the results are presented.

  19. Correction factors for the INER-improved free-air ionization chambers calculated with the Monte Carlo method.

    Science.gov (United States)

    Lin, Uei-Tyng; Chu, Chien-Hau

    2006-05-01

    Monte Carlo method was used to simulate the correction factors for electron loss and scattered photons for two improved cylindrical free-air ionization chambers (FACs) constructed at the Institute of Nuclear Energy Research (INER, Taiwan). The method is based on weighting correction factors for mono-energetic photons with X-ray spectra. The newly obtained correction factors for the medium-energy free-air chamber were compared with the current values, which were based on a least-squares fit to experimental data published in the NBS Handbook 64 [Wyckoff, H.O., Attix, F.H., 1969. Design of free-air ionization chambers. National Bureau Standards Handbook, No. 64. US Government Printing Office, Washington, DC, pp. 1-16; Chen, W.L., Su, S.H., Su, L.L., Hwang, W.S., 1999. Improved free-air ionization chamber for the measurement of X-rays. Metrologia 36, 19-24]. The comparison results showed the agreement between the Monte Carlo method and experimental data is within 0.22%. In addition, mono-energetic correction factors for the low-energy free-air chamber were calculated. Average correction factors were then derived for measured and theoretical X-ray spectra at 30-50 kVp. Although the measured and calculated spectra differ slightly, the resulting differences in the derived correction factors are less than 0.02%.

  20. Simulation of ionization-front-forming process at injection of relativistic electron beam with a gas chamber

    Energy Technology Data Exchange (ETDEWEB)

    Dolya, S.N.; Zhidkov, E.P.; Rubin, S.B.; Semerdzhiev, Kh.I.

    1982-01-01

    The methodical work on creation of computer program for numerical study of the processes of forming and motion of a virtual cathode at the injection of relativistic electron beam into a short cylindrical chamber, filled with gas, has been carried out. The obtained plots of the distributions of fields, potential and density appearing out of ion and electron gas of the beam itself are presented. The dependence of cross-section ionization on the electron velocity has been taken into account at the calculation; the resonance contribution into summarized cross-section of ionization was simulated. It is shown that the injection into the chamber without gas, some oscillations of the virtual cathode are observed. At the presence of the final front of the beam, the fields level at the initial stage is smaller than for the beam with a sharp front. However, in some time the field amplitudes are compared. The motion of simulated probe ions in the chamber is analyzed.

  1. Determinations of the correction factors for small fields in cylindrical ionization chambers based on measurement and numerical calculation

    Science.gov (United States)

    Park, Kwangwoo; Choi, Wonhoon; Park, Sungho; Choi, Jin Hwa; Park, Suk Won; Bak, Jino

    2015-07-01

    We investigated the volume averaging effect for air-filled cylindrical ionization chambers to determine the correction factors in a small photon field for a given chamber. We measured output factors with several cylindrical ionization chambers, and by using a mathematical method similar to deconvolution, we modeled the non-constant and inhomogeneous exposure function in the cavity of the chamber. The parameters in the exposure function and the correction factors were determined by solving a system of equations that we had developed by using the measured data and the geometry of the given chamber. The correction factors (CFs) were very similar to those obtained from Monte Carlo (MC) simulations. For example, the CFs in this study were found to be 1.116 for PTW31010 and 1.0225 for PTW31016 while the CFs obtained from MC simulations were reported as being approximately between 1.17 and 1.20 for PTW31010 and between 1.02 and 1.06 for PTW31016 in a 6-MV photon beam of 1 × 1 cm2. Furthermore, the method of deconvolution combined with the MC result for the chamber's response function showed a similar CF for PTW 30013, which was reported as 2.29 and 1.54 for a 1 × 1 cm2 and a 1.5 × 1.5 cm2 field size, respectively. The CFs from our method were similar, 2.42 and 1.54. In addition, we report CFs for PTW30013, PTW31010, PTW31016, IBA FC23-C, and IBA CC13. As a consequence, we suggest the use of our method to measure the correct output factor by using the fact that an inhomogeneous exposure causes a volume averaging effect in the cavity of air-filled cylindrical ionization chamber. The result obtained by using our method is very similar to that obtained from MC simulations. The method we developed can easily be applied in clinics.

  2. CMS Resistive Plate Chambers performance at $\\sqrt{s}=$13 TeV

    CERN Document Server

    Cabrera Mora, Andres Leonardo

    2016-01-01

    During 2015, the Large Hadron Collider (LHC) at CERN has reached the record-breaking center-of-mass energy of 13 TeV for proton-proton collisions. The LHC restarted operations successfully after a two-year technical stop, known as Long Shutdown 1 (LS1), needed for servicing and consolidating the CERN accelerator complex. The Compact Muon Solenoid detector, a general-purpose detector at LHC, benefited from LS1 by performing crucial tasks necessary to operate the detector at higher energies. In particular, the Resistive Plate Chamber (RPC) system, one of the three muon detector technologies in CMS, was serviced, re-commissioned, and upgraded with 144 new chambers to enhance muon trigger efficiency. The CMS RPC system confers robustness and redundancy to the muon trigger. A total of 1056 double-gap chambers cover the pseudo-rapidity region $ \\lvert\\eta\\rvert \\leq$1.6. The CMS RPC collaboration has exploited early data samples at 13 TeV for detector performance studies. These data allowed for a first characte...

  3. Time-resolved dosimetry using a pinpoint ionization chamber as quality assurance for IMRT and VMAT

    Energy Technology Data Exchange (ETDEWEB)

    Louwe, Robert J. W., E-mail: rob.louwe@ccdbh.org.nz; Satherley, Thomas; Day, Rebecca A.; Greig, Lynne [Department of Radiation Oncology, Wellington Blood and Cancer Centre, Wellington Hospital, Wellington 6242 (New Zealand); Wendling, Markus; Monshouwer, René [Department of Radiation Oncology, Radboud University Medical Center, Nijmegen 6500 HB (Netherlands)

    2015-04-15

    Purpose: To develop a method to verify the dose delivery in relation to the individual control points of intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) using an ionization chamber. In addition to more effective problem solving during patient-specific quality assurance (QA), the aim is to eventually map out the limitations in the treatment chain and enable a targeted improvement of the treatment technique in an efficient way. Methods: Pretreatment verification was carried out for 255 treatment plans that included a broad range of treatment indications in two departments using the equipment of different vendors. In-house developed software was used to enable calculation of the dose delivery for the individual beamlets in the treatment planning system (TPS), for data acquisition, and for analysis of the data. The observed deviations were related to various delivery and measurement parameters such as gantry angle, field size, and the position of the detector with respect to the field edge to distinguish between error sources. Results: The average deviation of the integral fraction dose during pretreatment verification of the planning target volume dose was −2.1% ± 2.2% (1 SD), −1.7% ± 1.7% (1 SD), and 0.0% ± 1.3% (1 SD) for IMRT at the Radboud University Medical Center (RUMC), VMAT (RUMC), and VMAT at the Wellington Blood and Cancer Centre, respectively. Verification of the dose to organs at risk gave very similar results but was generally subject to a larger measurement uncertainty due to the position of the detector at a high dose gradient. The observed deviations could be related to limitations of the TPS beam models, attenuation of the treatment couch, as well as measurement errors. The apparent systematic error of about −2% in the average deviation of the integral fraction dose in the RUMC results could be explained by the limitations of the TPS beam model in the calculation of the beam penumbra. Conclusions: This

  4. An evaluation of semiconductor and ionization chamber detectors for diagnostic x-ray dosimetry measurements.

    Science.gov (United States)

    Martin, C J

    2007-08-07

    Dosemeters for performance testing of x-ray equipment may utilize semiconductor technology or ionization chambers (ICs). Semiconductor dosemeters incorporate several elements into the detectors from which compensation for variations in response with photon energy is derived. The design of the detectors influences their response with angle and this is different from that of ICs. The responses of semiconductor detectors (SDs) and ICs to x-ray beams with a variety of radiation qualities have been measured in order to assess differences in response. Measurements have been made with experimental arrangements simulating use of the detectors in performance testing of digital radiography and fluoroscopy equipment. Results show that differences in photon energy responses between the detectors are small, but because ICs are sensitive to radiation incident from all angles, they record more scattered radiation than SDs. Implications of differences in detector responses are discussed and recommendations made about their use. SDs are more appropriate for measurements of image receptor doses and are recommended for setting up automatic exposure control devices for digital radiography. ICs are suitable for assessment of patient entrance surface dose rate measurements. Correction factors that could be applied to allow comparisons between measurements with different dosemeters are proposed.

  5. Liquid ionization chamber initial recombination dependence on LET for electrons and photons.

    Science.gov (United States)

    Johansson, Erik; Andersson, Jonas; Johansson, Lennart; Tölli, Heikki

    2013-06-21

    The possibility of indirect measurements of linear energy transfer (LET) with a liquid ionization chamber (LIC) has been investigated by studying initial recombination losses at different applied voltages. A linear fit is made to the voltage-signal curve and the intersection point of the fit and the voltage-axis is shown to correlate with LET. The LIC applied voltages were 100-700 V, which corresponds to electric field strengths between 0.3 and 2.0 MV m(-1). Several different photon and electron beams have been studied, and by using MCNPX™ the respective LET spectra have been determined. The beam qualities in this study were found to have a fluence averaged LET between 0.17 and 1.67 keV µm(-1) and a corresponding dose averaged LET between 0.97 and 4.62 keV µm(-1). For the experimental data in this study the linear fit method yields consistent results with respect to Monte Carlo simulated LET values. A calibration curve for LET determination is provided for the LIC used in the present work.

  6. Detecting MLC errors in stereotactic radiotherapy plans with a liquid filled ionization chamber array.

    Science.gov (United States)

    O'Connor, Patrick; Seshadri, Venkatakrisnan; Charles, Paul

    2016-03-01

    Quality assurance of stereotactic radiotherapy demands the use of equipment with the highest resolution and sensitivity available. This study examines the sensitivity of a commercially available liquid-filled ionization chamber array--the Octavius 1000 SRS (PTW, Frieburg, Germany) for detecting small (sub-millimetre) multi-leaf collimator (MLC) alignment errors in static square fields (side length 16-40 mm). Furthermore, the effectiveness of detecting small MLC errors in clinical stereotactic radiotherapy patient plans using the device was also evaluated. The commonly used gamma pass rate metric (of the measurements compared with treatment planning system generated results) was used. The gamma pass rates were then evaluated as a function of MLC position error (MLC error size 0.1-2.5 mm). The detector array exhibited a drop in pass rate between plans without error and those which had MLC errors induced. For example a drop in pass rate of 4.5% (gamma criteria 3%, 1 mm) was observed when a 0.8 mm error was introduced into a 16 mm square field. Furthermore the drop in pass rate increased as the MLC position error increased. This study showed that the Octavius 1000 SRS array could be a useful tool for applications requiring the detection of small geometric delivery uncertainties.

  7. Optimization of signal extraction and front-end design in a fast,multigap ionization chamber

    Energy Technology Data Exchange (ETDEWEB)

    Datte, P.S.; Manfredi, P.F.; Millaud, J.E.; Placidi, M.; Ratti,L.; Speziali, V.; Traversi, G.; Turner, W.C.

    2001-11-05

    This paper discusses the criteria that have been adopted tooptimize the signal processing in a shower detector to be employed as LHCbeam luminosity monitor. The original aspect ofthis instrument is itsablility to operate on a bunch-by-bunch basis. This means that it mustperform accurate charge measurements at a repetition rate of 40 MHz. Thedetector must withstand an integrated dose of 100 Grad, that is, two tothree orders of magnitude beyond those expected in the experiments. Tomeet the above requirements, an ionization chamber consisting of severalgaps of thickness 0.5 mm, filled with a gas that is expected to beradiation resistant, has been designed. Crucial in the development of thesystem is the signal processing, as the electronic noise may set thedominant limitation to the accuracy of the measurement. This is relatedto two aspects. One is the short time available for the chargemeasurement. The second one is the presence of a few meter cable betweenthe detector and the preamplifier, as this must be located out of theregion of highest radiation field. Therefore the optimization of thesignal-to-noise ratio requires that the best configuration of the chambergaps be determined under the constraint of the presence of a cable ofnon-negligible length between detector and preamplifier. The remoteplacement of the amplifying electronics will require that the front-endelectronics be radiation hard although to a lesser extent than thedetector.

  8. Measurement of differential (n,x{alpha}) cross section using 4{pi} gridded ionization chamber

    Energy Technology Data Exchange (ETDEWEB)

    Sanami, Toshiya; Baba, Mamoru; Matsuyama, Shigeo; Kiyosumi, Takehide; Nauchi, Yasushi; Saito, Keiichiro; Hirakawa, Naohiro [Tohoku Univ., Sendai (Japan). Faculty of Engineering; Kawano, Toshihiko

    1997-03-01

    We carried out the measurements of high resolution {alpha} emission spectra of {sup 58}Ni and {sup nat}Ni between 4.5 and 6.5 MeV, and {sup 12}C(n,x{alpha}) cross section using a 4{pi} gridded ionization chamber. In Ni measurement, overall energy resolution was improved to around 200 keV by optimizing a sample thickness and a neutron source width. Measured alpha spectra showed separate peaks corresponding to the ground and low-lying excited states of the residual nucleus ({sup 55}Fe). These results were compared with another direct measurement and statistical model calculations. In {sup 12}C measurement, GIC was applied for (n,x{alpha}) reactions of light nuclei. This application is difficult to (n,x{alpha}) cross sections of light nuclei, because of the influences of large recoil energy and multi-body break-up. We developed new methods which eliminate the effects of recoil nuclei and multi-body break-up and applied them to {sup 12}C(n,x{alpha}) reaction at En=14.1 MeV. In our experiment, the {sup 12}C(n,{alpha}{sub 0}){sup 9}Be angular differential cross section and {sup 12}C(n,n`3{alpha}) cross section were obtained. (author)

  9. The control system of the multi-strip ionization chamber for the HIMM

    Science.gov (United States)

    Li, Min; Yuan, Y. J.; Mao, R. S.; Xu, Z. G.; Li, Peng; Zhao, T. C.; Zhao, Z. L.; Zhang, Nong

    2015-03-01

    Heavy Ion Medical Machine (HIMM) is a carbon ion cancer treatment facility which is being built by the Institute of Modern Physics (IMP) in China. In this facility, transverse profile and intensity of the beam at the treatment terminals will be measured by the multi-strip ionization chamber. In order to fulfill the requirement of the beam position feedback to accomplish the beam automatic commissioning, less than 1 ms reaction time of the Data Acquisition (DAQ) of this detector must be achieved. Therefore, the control system and software framework for DAQ have been redesigned and developed with National Instruments Compact Reconfigurable Input/Output (CompactRIO) instead of PXI 6133. The software is Labview-based and developed following the producer-consumer pattern with message mechanism and queue technology. The newly designed control system has been tested with carbon beam at the Heavy Ion Research Facility at Lanzhou-Cooler Storage Ring (HIRFL-CSR) and it has provided one single beam profile measurement in less than 1 ms with 1 mm beam position resolution. The fast reaction time and high precision data processing during the beam test have verified the usability and maintainability of the software framework. Furthermore, such software architecture is easy-fitting to applications with different detectors such as wire scanner detector.

  10. Testing an ionization chamber with gaseous samples and measurements of the (n, alpha) reaction cross sections

    CERN Document Server

    Gledenov, Yu M; Salatskii, V I; Sedyshev, P V; Andrzejewski, J; Szalanski, P

    1999-01-01

    A new ionization chamber with gaseous samples (GIC) has been designed and tested on the thermal and resonance neutron beams of FLNP's neutron sources. The exposed gas volume serves as a target for neutrons. The obtained thermal cross sections for the sup 1 sup 7 O(n, alpha) sup 1 sup 4 C, sup 2 sup 1 Ne(n, alpha) sup 1 sup 8 O and sup 3 sup 6 Ar(n, alpha) sup 3 sup 3 S reactions are (233+-12) mb, (0.18+-0.09) mb and (5.43+-0.27) mb, respectively. These measurements have been performed on a pure beam of thermal neutrons from the high flux reactor IBR-2; and they demonstrated high efficiency and reliability of the method. Compared to samples on substrates, the application of gaseous samples makes the beam background essentially lower, and what is more important, the background component is totally absent due to the absence of Li and B microimpurities in gaseous samples while they do present in the samples on substrates. The method is also applicable to measurements with resonance neutrons. The recovery capabili...

  11. The control system of the multi-strip ionization chamber for the HIMM

    Energy Technology Data Exchange (ETDEWEB)

    Li, Min, E-mail: limin@impcas.ac.cn [Institute of Modern Physics, Chinese Academy of Science, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Yuan, Y.J. [Institute of Modern Physics, Chinese Academy of Science, Lanzhou 730000 (China); Mao, R.S., E-mail: Maorsh@impcas.ac.cn [Institute of Modern Physics, Chinese Academy of Science, Lanzhou 730000 (China); Xu, Z.G.; Li, Peng; Zhao, T.C.; Zhao, Z.L. [Institute of Modern Physics, Chinese Academy of Science, Lanzhou 730000 (China); Zhang, Nong [Institute of Modern Physics, Chinese Academy of Science, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China)

    2015-03-11

    Heavy Ion Medical Machine (HIMM) is a carbon ion cancer treatment facility which is being built by the Institute of Modern Physics (IMP) in China. In this facility, transverse profile and intensity of the beam at the treatment terminals will be measured by the multi-strip ionization chamber. In order to fulfill the requirement of the beam position feedback to accomplish the beam automatic commissioning, less than 1 ms reaction time of the Data Acquisition (DAQ) of this detector must be achieved. Therefore, the control system and software framework for DAQ have been redesigned and developed with National Instruments Compact Reconfigurable Input/Output (CompactRIO) instead of PXI 6133. The software is Labview-based and developed following the producer–consumer pattern with message mechanism and queue technology. The newly designed control system has been tested with carbon beam at the Heavy Ion Research Facility at Lanzhou-Cooler Storage Ring (HIRFL-CSR) and it has provided one single beam profile measurement in less than 1 ms with 1 mm beam position resolution. The fast reaction time and high precision data processing during the beam test have verified the usability and maintainability of the software framework. Furthermore, such software architecture is easy-fitting to applications with different detectors such as wire scanner detector.

  12. Quantitative Verification of Dynamic Wedge Dose Distribution Using a 2D Ionization Chamber Array.

    Science.gov (United States)

    Sahnoun, Tarek; Farhat, Leila; Mtibaa, Anis; Besbes, Mounir; Daoud, Jamel

    2015-10-01

    The accuracy of two calculation algorithms of the Eclipse 8.9 treatment planning system (TPS)--the anisotropic analytic algorithm (AAA) and pencil-beam convolution (PBC)--in modeling the enhanced dynamic wedge (EDW) was investigated. Measurements were carried out for 6 and 18 MV photon beams using a 2D ionization chamber array. Accuracy of the TPS was evaluated using a gamma index analysis with the following acceptance criteria for dose differences (DD) and distance to agreement (DTA): 3%/3 mm and 2%/2 mm. The TPS models the dose distribution accurately except for 20×20 cm(2) field size, 60 (°) and 45 (°) wedge angles using PBC at 6 MV photon energy. For these latter fields, the pass rate and the mean value of gamma were less than 90% and more than 0.5, respectively at the (3%/3 mm) acceptance criteria. In addition, an accuracy level of (2%/2 mm) was achieved using AAA with better agreement for 18 MV photon energy.

  13. A high dynamic Micro Strips Ionization Chamber featuring Embedded Multi DSP Processing

    CERN Document Server

    Voltolina, Francesco; Carrato, Sergio; 10.1109/NSSMIC.2004.1466924

    2010-01-01

    An X-ray detector will be presented that is the combination of a segmented ionization chamber featuring one-dimensional spatial resolution integrated with an intelligent ADC front-end, multi DSP processing and embedded PC platform. This detector is optimized to fan beam geometry with an active area of 192 mm (horizontal) and a vertical acceptance of 6 mm. Spatial resolution is obtained by subdividing the anode into readout strips, having pitch of 150 micrometers, which are connected to 20 custom made integrating VLSI chips (each capable of 64-channel read-out and multiplexing) and read out by 14 bits 10 MHz ADCs and fast adaptive PGAs into DSP boards. A bandwidth reaching 3.2Gbit/s of raw data, generated from the real time sampling of the 1280 micro strips, is cascaded processed with FPGA and DSP to allow data compression resulting in several days of uninterrupted acquisition capability. Fast acquisition rates reaching 10 kHz are allowed due to the MicroCAT structure utilized not only as a shielding grid in i...

  14. Calibration of ionization energy loss at relativistic rise with STAR Time Projection Chamber

    CERN Document Server

    Xu, Yichun; Bichsel, Hans; Dong, Xin; Fachini, Patricia; Fisyak, Yuri; Kocolosky, Adam; Mohanty, Bedanga; Netrakanti, Pawan; Ruan, Lijuan; Suarez, Maria Cristina; Tang, Zebo; van Buren, Gene; Xu, Zhangbu

    2008-01-01

    We derive a method to improve particle identification (PID) at high transverse momentum ($p_T$) using the relativistic rise of the ionization energy loss ($rdE/dx$) when charged particles traverse the Time Projection Chamber (TPC) at STAR. Electrons triggered and identified by the Barrel Electro-Magnetic Calorimeter (BEMC), pure protons and pions from $\\Lambda\\to p+\\pi^{-}$ ($\\bar{\\Lambda}\\to \\bar{p}+\\pi^{+}$), and $K^{0}_{S}\\to\\pi^{+}+\\pi^{-}$ decays are used to obtain the $dE/dx$ value and its width at given $\\beta\\gamma=p/m$. We found that the deviation of the $dE/dx$ from the Bichsel function can be up to $0.4\\sigma$ ($\\sim3%$) in p+p collisions at $\\sqrt{s_{NN}}=200$ GeV taken and subsequently calibrated in year 2005. The deviation is approximately a function of $\\beta\\gamma$ independent of particle species and can be described with a function of $f(x) = A+\\frac{B}{C+x^{2}}$. The deviations obtained with this method are used to re-calibrate the data sample from p+p collision for physics analysis of ident...

  15. Dose verifications by use of liquid ionization chamber of an electronic portal imaging device (EPID).

    Science.gov (United States)

    Tateoka, Kunihiko; Oouchi, Atsushi; Nakata, Kensei; Hareyama, Masato

    2008-07-01

    In this study, we examined the ability of an L-EPID to verify rectangular and irregular fields and to measure the transmitted exit doses. With respect to the beam profile of rectangular and irregular fields and the doses transmitted through an inhomogeneous phantom, the L-EPID dose obtained from the L-EPID measurement was compared with the conventional dose measured by use of a 0.12-cc ionization chamber and a 3D water phantom. In the comparison of the rectangular and irregular fields, the difference in the off-center ratio (OCR) between the L-EPID dose and the conventional dose was approximately 3% in the steep-dose-gradient region (penumbra regions, >30%/cm) and approximately +/-0.5% in the gentle-dose-gradient region (5%/cm). On the other hand, the dose differences between the L-EPID and the measured doses were less than approximately 2% in the gentle-dose-gradient region. In addition, in the steep-dose-gradient region, the maximum difference was 30%. However, the differences in the distance-to-agreement (DTA) were less than approximately +/-1 mm and were unrelated to the dose gradient. These results suggest that dose verification by L-EPID is very useful in clinical applications.

  16. Determination of Correction Factors for Small Field Based on Measurement and Numerical Calculation using Cylindrical Ionization Chambers

    CERN Document Server

    Park, Kwangwoo; Park, Sungho; Choi, Jin Hwa; Park, Suk Won; Bak, Jino

    2015-01-01

    We studied the investigation of volume averaging effect for air-filled cylindrical ionization chambers to determine correction factors in small photon field for the given chamber. As a method, we measured output factors using several cylindrical ionization chambers and calculated with mathematical method similar to deconvolution in which we modeled non-constant and inhomogeneous exposure function in the cavity of chamber. The parameters in exposure function and correction factors were determined by solving a system of equations we developed with measurement data and geometry of the given chamber. Correction factors (CFs) we had found are very similar to that from Monte Carlo (MC) simulation. For example, CFs in this study were computed as 1.116 for PTW31010, and 1.0225 for PTW31016, while CFs from MC were reported as approximately between 1.17 and 1.20 for PTW31010, and between 1.02 and 1.06 for PTW31016 in of 6MV photon beam . Furthermore, the result from the method of deconvolution combined with MC for cham...

  17. Dielectric barrier discharge ionization in characterization of organic compounds separated on thin-layer chromatography plates.

    Science.gov (United States)

    Cegłowski, Michał; Smoluch, Marek; Babij, Michał; Gotszalk, Teodor; Silberring, Jerzy; Schroeder, Grzegorz

    2014-01-01

    A new method for on-spot detection and characterization of organic compounds resolved on thin layer chromatography (TLC) plates has been proposed. This method combines TLC with dielectric barrier discharge ionization (DBDI), which produces stable low-temperature plasma. At first, the compounds were separated on TLC plates and then their mass spectra were directly obtained with no additional sample preparation. To obtain good quality spectra the center of a particular TLC spot was heated from the bottom to increase volatility of the compound. MS/MS analyses were also performed to additionally characterize all analytes. The detection limit of proposed method was estimated to be 100 ng/spot of compound.

  18. [Morphology determination of ionization region in multi-needle-to-plate negative corona discharge].

    Science.gov (United States)

    Su, Peng-Hao; Zhu, Yi-Min; Chen, Hai-Feng

    2007-11-01

    Based on the former work on the current-voltage characteristics of a multi-needle-to-plate negative corona discharge at atmospheric pressure, the present work uses the method of OES (optical emission spectrum) for measuring N2 emission spectrum, and the morphology determination of the ionization region has been investigated. According to the distribution of N2 second positive band's intensity I(SPB), the highest of all bands, the outline of the ionization region was drawn fairly accurately. The relationship between I(SPB) and discharge current I can be obtained through the volume integral of the I(SPB). The experimental results show that the size of the ionization region enhances with the rise of the applied voltage U, and the electron avalanche begins at about 1 mm off the tips of needle electrode and multiplies only in the range of several millimeters, indicating that, the range of the ionization region is at the magnitude of mm. The electron avalanche along the axis of the needle develops farther than that along the radial direction of needle, and the shape of the ionization region looks like a bullet. The integral of I(SPB) is second-order linear to I, with a very second order coefficient, meaning that the main excited substance is N2. Energetic electrons mainly exist in ionization region while ions are the main charged particles to form discharge current in the transfer region.

  19. Investigation of the initial and volume recombination losses in gamma versatile cylindrical ionization chamber VGIC developed for gamma ray dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Fares, M.; Mameri, S.; Abdlani, I.; Negara, K. [COMENA, Laboratoire Detection et Mesures, CRNB, BP no. 180 Ain-Oussera 17200 W. de Djelfa (Algeria)

    2015-07-01

    A versatile Gamma ionization chambers are used for flow control in systems with gamma nuclear reactors and reprocessing plants in and monitoring atmosphere around these facilities, this in order to protect staff. In the Laboratory Detection and Measures (LDM) Division for Study and Development of Nuclear Instrumentation (DSDNI) of CRNB, we designed, developed and characterized a versatile gamma ionization chamber (VGIC) to study experimentally its characteristics according to the geometry of the electrodes, the volume and pressure of the filler gas for the design of a gamma sealed chamber. The tests were conducted under the IEC (International Electro-technical Commission). In this paper, we present the results obtained in the various nuclear tests for characterization and calibration that we have made on the ionization chamber gamma VGIC prototype developed at our Department. To do this, three irradiators were operated at the Laboratory Calibration (SSDL) of the Department of Medical Physics Nuclear Research Center of Algiers (CRNA). Irradiator intensive gamma ({sup 60}Co: 1.25 MeV), one medium intensity gamma ({sup 137}Cs: 0.662 MeV) and 3rd low intensity ({sup 60}Co). Saturation curves and linearity were identified and the operating range and the sensitivity of the chamber have been deducted. The (I,V) characteristics of the chamber filled, with argon gas at 3 bar (0.3 M pa) pressure, for gamma ray irradiator sources were studied. To do so, the chamber was irradiated with gamma rays using different numbers of gamma sources (i.e. Up to 5). The plateau region is reached above 200 V and the detector operating voltage is found to be 600 V. It is observed that in the plateau region the slope is constant with an increase in the exposure rate. The (1/I, 1/V) and (I, l/V{sup 2}) characteristic curves reveal the presence of the initial and volume recombination losses. The volume recombination losses are found to be smaller than the initial recombination losses. Finally

  20. Effect of the calibration in water and the build-up cap on the Mg(Ar) ionization chamber measurements.

    Science.gov (United States)

    Koivunoro, H; Hyvönen, H; Uusi-Simola, J; Jokelainen, I; Kosunen, A; Kortesniemi, M; Seppälä, T; Auterinen, I; Savolainen, S

    2011-12-01

    Magnesium-walled argon gas flow ionization chamber (Mg(Ar)) is used for photon dose measurements in the epithermal neutron beam of FiR 1 reactor in Finland. In this study, the photon dose measurements were re-evaluated against calculations applying a new chamber calibration factor defined in water instead of in air. Also, effect of the build-up cap on the measurements was investigated. The new calibration factor provides improved agreement between measured and calculated photon dose. Use of the build-up cap does not affect the measured signal in water in neutron beam.

  1. Effect of the calibration in water and the build-up cap on the Mg(Ar) ionization chamber measurements

    Energy Technology Data Exchange (ETDEWEB)

    Koivunoro, H., E-mail: hanna.koivunoro@helsinki.fi [Boneca Corporation, FI-00290 Helsinki (Finland)] [Department of Physics, P.O.B. 64, FI-00014 University of Helsinki (Finland)] [Department of Oncology, Helsinki University Central Hospital, P.O.B. 180, 00029 HUS (Finland); Hyvoenen, H. [Boneca Corporation, FI-00290 Helsinki (Finland); Uusi-Simola, J. [HUS Helsinki Medical Imaging Center, University of Helsinki (Finland); Jokelainen, I.; Kosunen, A. [Radiation Metrology Laboratory, Radiation and Nuclear Safety Authority-STUK, FI-00881 (Finland); Kortesniemi, M. [HUS Helsinki Medical Imaging Center, University of Helsinki (Finland); Seppaelae, T. [Department of Oncology, Helsinki University Central Hospital, P.O.B. 180, 00029 HUS (Finland); Auterinen, I. [VTT Technical Research Centre of Finland, Espoo (Finland); Savolainen, S. [Department of Physics, P.O.B. 64, FI-00014 University of Helsinki (Finland)] [HUS Helsinki Medical Imaging Center, University of Helsinki (Finland)

    2011-12-15

    Magnesium-walled argon gas flow ionization chamber (Mg(Ar)) is used for photon dose measurements in the epithermal neutron beam of FiR 1 reactor in Finland. In this study, the photon dose measurements were re-evaluated against calculations applying a new chamber calibration factor defined in water instead of in air. Also, effect of the build-up cap on the measurements was investigated. The new calibration factor provides improved agreement between measured and calculated photon dose. Use of the build-up cap does not affect the measured signal in water in neutron beam.

  2. A patient-specific quality assurance study on absolute dose verification using ionization chambers of different volumes in RapidArc treatments

    Energy Technology Data Exchange (ETDEWEB)

    Syam Kumar, S.A., E-mail: skppm@rediffmail.com [Department of Medical Physics, Cancer Institute (WIA), Adyar, Chennai, Tamil Nadu (India); Sukumar, Prabakar; Sriram, Padmanaban; Rajasekaran, Dhanabalan; Aketi, Srinu; Vivekanandan, Nagarajan [Department of Medical Physics, Cancer Institute (WIA), Adyar, Chennai, Tamil Nadu (India)

    2012-01-01

    The recalculation of 1 fraction from a patient treatment plan on a phantom and subsequent measurements have become the norms for measurement-based verification, which combines the quality assurance recommendations that deal with the treatment planning system and the beam delivery system. This type of evaluation has prompted attention to measurement equipment and techniques. Ionization chambers are considered the gold standard because of their precision, availability, and relative ease of use. This study evaluates and compares 5 different ionization chambers: phantom combinations for verification in routine patient-specific quality assurance of RapidArc treatments. Fifteen different RapidArc plans conforming to the clinical standards were selected for the study. Verification plans were then created for each treatment plan with different chamber-phantom combinations scanned by computed tomography. This includes Medtec intensity modulated radiation therapy (IMRT) phantom with micro-ionization chamber (0.007 cm{sup 3}) and pinpoint chamber (0.015 cm{sup 3}), PTW-Octavius phantom with semiflex chamber (0.125 cm{sup 3}) and 2D array (0.125 cm{sup 3}), and indigenously made Circular wax phantom with 0.6 cm{sup 3} chamber. The measured isocenter absolute dose was compared with the treatment planning system (TPS) plan. The micro-ionization chamber shows more deviations when compared with semiflex and 0.6 cm{sup 3} with a maximum variation of -4.76%, -1.49%, and 2.23% for micro-ionization, semiflex, and farmer chambers, respectively. The positive variations indicate that the chamber with larger volume overestimates. Farmer chamber shows higher deviation when compared with 0.125 cm{sup 3}. In general the deviation was found to be <1% with the semiflex and farmer chambers. A maximum variation of 2% was observed for the 0.007 cm{sup 3} ionization chamber, except in a few cases. Pinpoint chamber underestimates the calculated isocenter dose by a maximum of 4.8%. Absolute dose

  3. A patient-specific quality assurance study on absolute dose verification using ionization chambers of different volumes in RapidArc treatments.

    Science.gov (United States)

    Syam Kumar, S A; Sukumar, Prabakar; Sriram, Padmanaban; Rajasekaran, Dhanabalan; Aketi, Srinu; Vivekanandan, Nagarajan

    2012-01-01

    The recalculation of 1 fraction from a patient treatment plan on a phantom and subsequent measurements have become the norms for measurement-based verification, which combines the quality assurance recommendations that deal with the treatment planning system and the beam delivery system. This type of evaluation has prompted attention to measurement equipment and techniques. Ionization chambers are considered the gold standard because of their precision, availability, and relative ease of use. This study evaluates and compares 5 different ionization chambers: phantom combinations for verification in routine patient-specific quality assurance of RapidArc treatments. Fifteen different RapidArc plans conforming to the clinical standards were selected for the study. Verification plans were then created for each treatment plan with different chamber-phantom combinations scanned by computed tomography. This includes Medtec intensity modulated radiation therapy (IMRT) phantom with micro-ionization chamber (0.007 cm(3)) and pinpoint chamber (0.015 cm(3)), PTW-Octavius phantom with semiflex chamber (0.125 cm(3)) and 2D array (0.125 cm(3)), and indigenously made Circular wax phantom with 0.6 cm(3) chamber. The measured isocenter absolute dose was compared with the treatment planning system (TPS) plan. The micro-ionization chamber shows more deviations when compared with semiflex and 0.6 cm(3) with a maximum variation of -4.76%, -1.49%, and 2.23% for micro-ionization, semiflex, and farmer chambers, respectively. The positive variations indicate that the chamber with larger volume overestimates. Farmer chamber shows higher deviation when compared with 0.125 cm(3). In general the deviation was found to be <1% with the semiflex and farmer chambers. A maximum variation of 2% was observed for the 0.007 cm(3) ionization chamber, except in a few cases. Pinpoint chamber underestimates the calculated isocenter dose by a maximum of 4.8%. Absolute dose measurements using the semiflex

  4. Plastic scintillator-based hodoscope for the characterization of large-area resistive plate chambers

    Indian Academy of Sciences (India)

    V K S KASHYAP; C YADAV; S T SEHGAL; R SEHGAL; R G THOMAS; L M PANT; A K MOHANTY

    2016-12-01

    A scintillator-based hodoscope is fully operational at Nuclear Physics Division, Bhabha Atomic Research Centre (NPD-BARC). It was used for characterizing the resistive plate chambers (RPCs) assembled for the RE4 upgrade for the compact muon solenoid (CMS) experiment, installed during the long shut-down (LS1) using cosmic muons. It has now been employed for R & D related to gas mixtures and glass RPCs for the Indiabased neutrino observatory (INO) and muon tomography studies. The hodoscope is equipped with gas flow lines,LV, HV and VME-based DAQ with multihit TDCs. CERN-based software was adapted, implemented and along with the cosmic trigger, was used to evaluate the functional parameters for the RPCs, such as efficiency, clustersize etc.

  5. A new type of detector time of flight - multi-gap resistive plate chamber

    CERN Document Server

    Chen, H; Eppley, G; Geurts, F J M; Huang, S; Li, C; Liu, H; Llope, W J; Ruan, L; Shao, M; Wang, X L; Wang, Z; Wu, J; Xu, Z; Zhang, Z

    2004-01-01

    Multi-gap resistive plate chamber is a new detector technology. It was first developed by the LHC-ALICE group at CERN in the late 1990s. The MRPC is a ideal detector for time-of-flight measurement due to its small gaps and works in the proportional (avalanche) mode. The beam test of single module result shows that MRPC tuning resolution is better than 70ps and the detection efficiency is higher than 95%. It is also radiation hard. A time-of-flight tray with 28 on MRPC modules. was tested at AGS. The average timing resolution is about 75ps (including the 4cm of beam spread) and detection efficiency is better than 95%. This tray has been installed on STAR detector system in October 2002 and used on the 200GeV d+Au experiment.

  6. Eco-friendly gas mixtures for Resistive Plate Chambers based on Tetrafluoropropene and Helium

    CERN Document Server

    Abbrescia, M; Bianco, S; Ferrini, M; Muhammad, S; Passamonti, L; Pierluigi, D; Piccolo, D; Primavera, F; Russo, A; Saviano, G

    2016-01-01

    Due to the recent restrictions deriving from the application of the Kyoto protocol, the main components of the gas mixtures presently used in the Resistive Plate Chambers systems of the LHC experiments will be most probably phased out of production in the coming years. Identifying possible replacements with the adequate characteristics requires an intense R&D, which was recently started, also in collaborations across the various experiments. Possible candidates have been proposed and are thoroughly investigated. Some tests on one of the most promising candidate - HFO-1234ze, an allotropic form of tetrafluoropropane- have already been reported. Here an innovative approach, based on the use of Helium, to solve the problems related to the too elevate operating voltage of HFO-1234ze based gas mixtures, is discussed and the relative first results are shown.

  7. Multigap resistive plate chambers for EAS study in the EEE Project

    CERN Document Server

    An, S; Badalà, A; Zichichi, A

    2007-01-01

    The EEE (Extreme Energy Events) Project, conceived by its leader Antonino Zichichi, is an experiment to study very high-energetic air showers (EAS) through the detection of the shower's muon component using a network of tracking detectors, installed in Italian high schools. The single tracking telescope is composed of three large area () Multi-gap Resistive Plate Chambers (MRPCs). The data collected by the telescopes will be used for studies of air showers and also for the search of time correlations between sites which are far apart. The first telescope, recently installed in the Liceo B. Touschek in Grottaferrata (Rome), is successfully running, and other telescopes are going to be installed in a short time in other towns, opening up the way for the first search of long-distance coincidences over a total area of .

  8. Development of TOF-PET detectors based on the Multi-Gap Resistive Plate Chambers

    Science.gov (United States)

    Amaldi, U.; Borghi, G.; Bucciantonio, M.; Kieffer, R.; Samarati, J.; Sauli, F.; Watts, D.

    2015-04-01

    We describe the development, construction and preliminary results obtained with medium-size Multi-Gap Resistive Plate Chambers prototypes designed to detect and localize 511 keV photons for Positron Emission Tomography imaging applications. The devices are intended for in-beam monitoring of the treatment plans throughout deep tumor therapy with hadron beams; emphasis is put on achieving coincidence time resolutions of few hundred ps, in order to exploit optimized reconstruction algorithm and reduce the heavy non-correlated background contributions distinctive of this operation. Using technologies developed for high energy physics experiments, the detectors can be built for covering large areas, thus leading the way to the conception of full-body PET systems at low cost.

  9. A large-area glass-resistive plate chamber with multistrip readout

    CERN Document Server

    Petrovici, M; Hildenbrand, K D; Augustinski, G; Ciobanu, M; Cruceru, I; Duma, M; Hartmann, O; Koczón, P; Kress, T; Marquardt, M; Moisa, D; Petris, M; Schröder, C; Simion, V; Stoicea, G; Weinert, J

    2002-01-01

    A completely new configuration of a glass resistive-plate chamber (GRPC) was built and tested. It consists of a double two-gap structure of electrodes with an active area of about 400 cm sup 2 and is read out via a central multistrip printed circuit board. In measurements with a sup 6 sup 0 Co source and p, d particles of 1.5 A GeV time resolutions better than 80 ps, position resolution along the strips of 5-6 mm and efficiencies larger than 95% were obtained using available fast standard electronics. These results open the possibility of constructing compact TOF detectors of high resolution and high granularity.

  10. Signal coupling and signal integrity in multi-strip Resistive Plate Chambers used for timing applications

    CERN Document Server

    Gonzalez-Diaz, Diego; Wang, Yi

    2011-01-01

    We have systematically studied the transmission of electrical signals along several 2-strip Resistive Plate Chambers (RPCs) in the frequency range $f=0.1-3.5$GHz. Such a range was chosen to fully cover the bandwidth associated to the very short rise-times of signals originated in RPCs used for sub-100ps timing applications. This work conveys experimental evidence of the dominant role of modal dispersion in counters built at the 1 meter scale, a fact that results in large cross-talk levels and strong signal shaping. It is shown that modal dispersion appears in RPCs due to the intrinsic unbalance between the capacitive and the inductive coupling $C_m/C_o \

  11. Target Plate Material Influence on Fullerene-C60 Laser Desorption/Ionization Efficiency.

    Science.gov (United States)

    Zeegers, Guido P; Günthardt, Barbara F; Zenobi, Renato

    2016-04-01

    Systematic laser desorption/ionization (LDI) experiments of fullerene-C60 on a wide range of target plate materials were conducted to gain insight into the initial ion formation in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The positive and negative ion signal intensities of precursor, fragment, and cluster ions were monitored, varying both the laser fluence (0-3.53 Jcm(-2)) and the ion extraction delay time (0-950 ns). The resulting species-specific ion signal intensities are an indication for the ionization mechanisms that contribute to LDI and the time frames in which they operate, providing insight in the (MA)LDI primary ionization. An increasing electrical resistivity of the target plate material increases the fullerene-C60 precursor and fragment anion signal intensity. Inconel 625 and Ti90/Al6/V4, both highly electrically resistive, provide the highest anion signal intensities, exceeding the cation signal intensity by a factor ~1.4 for the latter. We present a mechanism based on transient electrical field strength reduction to explain this trend. Fullerene-C60 cluster anion formation is negligible, which could be due to the high extraction potential. Cluster cations, however, are readily formed, although for high laser fluences, the preferred channel is formation of precursor and fragment cations. Ion signal intensity depends greatly on the choice of substrate material, and careful substrate selection could, therefore, allow for more sensitive (MA)LDI measurements. Graphical Abstract ᅟ.

  12. Target Plate Material Influence on Fullerene-C60 Laser Desorption/Ionization Efficiency

    Science.gov (United States)

    Zeegers, Guido P.; Günthardt, Barbara F.; Zenobi, Renato

    2016-04-01

    Systematic laser desorption/ionization (LDI) experiments of fullerene-C60 on a wide range of target plate materials were conducted to gain insight into the initial ion formation in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The positive and negative ion signal intensities of precursor, fragment, and cluster ions were monitored, varying both the laser fluence (0-3.53 Jcm-2) and the ion extraction delay time (0-950 ns). The resulting species-specific ion signal intensities are an indication for the ionization mechanisms that contribute to LDI and the time frames in which they operate, providing insight in the (MA)LDI primary ionization. An increasing electrical resistivity of the target plate material increases the fullerene-C60 precursor and fragment anion signal intensity. Inconel 625 and Ti90/Al6/V4, both highly electrically resistive, provide the highest anion signal intensities, exceeding the cation signal intensity by a factor ~1.4 for the latter. We present a mechanism based on transient electrical field strength reduction to explain this trend. Fullerene-C60 cluster anion formation is negligible, which could be due to the high extraction potential. Cluster cations, however, are readily formed, although for high laser fluences, the preferred channel is formation of precursor and fragment cations. Ion signal intensity depends greatly on the choice of substrate material, and careful substrate selection could, therefore, allow for more sensitive (MA)LDI measurements.

  13. The non-uniformity correction factor for the cylindrical ionization chambers in dosimetry of an HDR 192Ir brachytherapy source

    Directory of Open Access Journals (Sweden)

    Majumdar Bishnu

    2006-01-01

    Full Text Available The aim of this study is to derive the non-uniformity correction factor for the two therapy ionization chambers for the dose measurement near the brachytherapy source. The two ionization chambers of 0.6 cc and 0.1 cc volume were used. The measurement in air was performed for distances between 0.8 cm and 20 cm from the source in specially designed measurement jig. The non-uniformity correction factors were derived from the measured values. The experimentally derived factors were compared with the theoretically calculated non-uniformity correction factors and a close agreement was found between these two studies. The experimentally derived non-uniformity correction factor supports the anisotropic theory.

  14. Physical fundamentals for the functional simulation of the ionization transmission chamber in X-ray diagnostics; Physikalische Grundlagen fuer die Funktionssimulation der Ionisations-Durchstrahlkammer in der Roentgendiagnostik

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Horst

    2012-11-01

    The presentation of the physical fundamentals for the functional simulation of the ionization transmission chamber in X-ray diagnostics covers the mathematical description of the interaction of photons with solid materials in Mote Carlo compliable way, including Rayleigh and Compton scattering and photoabsorption. The energy dependence of the emitted secondary electrons is described according the Coulomb and Moeller scattering theory. The simulation is aimed to determine the spectral electron flux density in the air-filled measuring space of the ionization chamber for the defined X-ray energy spectrum dependent on the voltage at the X-ray tube. The influence of geometry and materials on the spectral energy flux density provides hints for the construction of the ionization transmission chamber. The differential energy loss of the secondary electrons in air is determined allowing the calculation of the ionization rate. The ionization of air is described, providing the conditions for a linear relation between ionization rate and ionic current.

  15. The research on the consistency of the testing accuracy for smoke measuring equipment based on ionization chamber principle

    Directory of Open Access Journals (Sweden)

    Wang Ting Ting

    2016-01-01

    Full Text Available A convenient method is proposed here to determine the relative accuracy of measuring ionization chamber (MIC. A non-dimensional quantity is presented here to characterize the relative accuracy of the testing sample to the reference sample. There are two key points of the program. One is comparison by pairs. The other is eliminating the uncertainty in the program by exchanging the position and control unit in each testing group.

  16. Study of ionization-chamber measurement systems for activity determination; Untersuchung von Ionisationskammer-Messsystemen fuer Aktivitaetsbestimmungen

    Energy Technology Data Exchange (ETDEWEB)

    Niedergesaess, Christiane; Schrader, Heinrich; Kossert, Karsten

    2011-04-15

    The present report describes the performance and results of a common project of the company MED Nuklear-Medizintechnik Dresden GmbH and the Working Group 6.11 ''Activity Unit'' of the Physikalisch-Technischen Bundesanstalt (PTB) in Braunschweig with the subject ''Activity measurements with radionuclide calibrators (activity meters) for nuclear medicine and metrology''. In the frame of this project, the company MED provided three ionization chamber measuring systems, whereas the PTB adjoined the necessary personal, technical support and the radioactive sources and standards for the calibration in terms of activity. The goal of the project was a systematic study of the performance of the ionization chambers for activity measurements. This covers the subject of determination of various radionuclide efficiencies (calibration factors) necessary for activity determinations in practice. Using two of the ionization chambers of identical construction, a comparison of the reproducibility within exemplars was made using common calibration results. Furthermore, the instrument stability during a period of about two years and the system linearity for activity values within a range of about four orders of magnitude were studied. In addition, the energy-dependent efficiency curves were determined, which allowed the calculation of calibration factors for the three ionization chamber measuring systems using emission probabilities of the corresponding radionuclide. The uncertainties of the involved measurands, particularly for the activity values to be determined, were calculated using the rules of the ''Guide to the expression of uncertainty in measurement'' (GUM, JCGM, 2008). (orig.)

  17. Studies of purification of the Resistive Plate Chamber gas mixture for the Large Hadron Collider experiments

    CERN Document Server

    Capeans, M; Guida, R; Hahn, F; Haider, S

    2009-01-01

    The Resistive Plate Chambers (RPCs) installed as part of the large muon detectors at the Large Hadron Collider (LHC) experiments use a gas mixture of 94.7% C2H2F4, 5% iC(4)H(10) and 0.3% SF6. Based on economical grounds, the design philosophy of the gas systems for the ATLAS and CMS RPC's foresees to recirculate the gas mixture in 90-95% closed loop circulation. At the LHC, RPC chambers are operated in a high radiation environment, conditions for which large amount of impurities in the return gas have been observed in earlier studies. They are potentially dangerous for the stable operation of the detectors, the materials in the detector and the gas system. While several purification stages have been foreseen in the present gas systems, chemical reactions between the absorber and the impurities are yet not well understood. Furthermore, the effects on the gas mixture of the foreseen factor 10 increase of luminosity for the LHC upgraded phase should be studied. We present the results of systematic studies of the...

  18. A standard Fricke dosimeter compared to an ionization chamber used for dosimetric characterization of 60Co photon beam

    Science.gov (United States)

    Moussous, Ouiza; Medjadj, Toufik

    2016-06-01

    The main objective of this study was to investigate the Fricke dosimeter water equivalent system for measurement of dosimetric parameters for photon beam. The parameters measured with the Fricke dosimeter were compared to those obtained with an ionization chamber. In this work characteristics for 60Co γ-rays of field sizes ranging from 5 × 5 cm2 to 20 × 20 cm2 are reported. The measurements were carried out in the secondary standard dosimetry laboratory using a collimated 60Co gamma source therapy unit. The 60Co beam output in terms of absorbed dose to water was obtained as per IAEA TRS 398 recommendations using cylindrical ionization chamber, whose ND,w has been supplied by the IAEA's reference laboratory. Specific quantities measured include: output factors, peak scatter factor, lateral beam profiles and percentage depth dose. The Fricke dosimeters were irradiated in a water phantom using the suitable poly (methyl methacrylate), PMMA stand. Our results demonstrate that Fricke dosimeter and ionization chamber agree with each other.

  19. Monte Carlo calculation of beam quality correction factors in proton beams using detailed simulation of ionization chambers

    Science.gov (United States)

    Gomà, Carles; Andreo, Pedro; Sempau, Josep

    2016-03-01

    This work calculates beam quality correction factors (k Q ) in monoenergetic proton beams using detailed Monte Carlo simulation of ionization chambers. It uses the Monte Carlo code penh and the electronic stopping powers resulting from the adoption of two different sets of mean excitation energy values for water and graphite: (i) the currently ICRU 37 and ICRU 49 recommended {{I}\\text{w}}=75~\\text{eV} and {{I}\\text{g}}=78~\\text{eV} and (ii) the recently proposed {{I}\\text{w}}=78~\\text{eV} and {{I}\\text{g}}=81.1~\\text{eV} . Twelve different ionization chambers were studied. The k Q factors calculated using the two different sets of I-values were found to agree with each other within 1.6% or better. k Q factors calculated using current ICRU I-values were found to agree within 2.3% or better with the k Q factors tabulated in IAEA TRS-398, and within 1% or better with experimental values published in the literature. k Q factors calculated using the new I-values were also found to agree within 1.1% or better with the experimental values. This work concludes that perturbation correction factors in proton beams—currently assumed to be equal to unity—are in fact significantly different from unity for some of the ionization chambers studied.

  20. The stability of liquid-filled matrix ionization chamber electronic portal imaging devices for dosimetry purposes.

    Science.gov (United States)

    Louwe, R J W; Tielenburg, R; van Ingen, K M; Mijnheer, B J; van Herk, M B

    2004-04-01

    This study was performed to determine the stability of liquid-filled matrix ionization chamber (LiFi-type) electronic portal imaging devices (EPID) for dosimetric purposes. The short- and long-term stability of the response was investigated, as well as the importance of factors influencing the response (e.g., temperature fluctuations, radiation damage, and the performance of the electronic hardware). It was shown that testing the performance of the electronic hardware as well as the short-term stability of the imagers may reveal the cause of a poor long-term stability of the imager response. In addition, the short-term stability was measured to verify the validity of the fitted dose-response curve immediately after beam startup. The long-term stability of these imagers could be considerably improved by correcting for room temperature fluctuations and gradual changes in response due to radiation damage. As a result, the reproducibility was better than 1% (1 SD) over a period of two years. The results of this study were used to formulate recommendations for a quality control program for portal dosimetry. The effect of such a program was assessed by comparing the results of portal dosimetry and in vivo dosimetry using diodes during the treatment of 31 prostate patients. The improvement of the results for portal dosimetry was consistent with the deviations observed with the reproducibility tests in that particular period. After a correction for the variation in response of the imager, the average difference between the measured and prescribed dose during the treatment of prostate patients was -0.7%+/-1.5% (1 SD), and -0.6%+/-1.1% (1 SD) for EPID and diode in vivo dosimetry, respectively. It can be concluded that a high stability of the response can be achieved for this type of EPID by applying a rigorous quality control program.

  1. Comparison and uncertainty evaluation of different calibration protocols and ionization chambers for low-energy surface brachytherapy dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Candela-Juan, C., E-mail: ccanjuan@gmail.com [Radiation Oncology Department, La Fe University and Polytechnic Hospital, Valencia 46026 (Spain); Vijande, J. [Department of Atomic, Molecular, and Nuclear Physics, University of Valencia, Burjassot 46100, Spain and Instituto de Física Corpuscular (UV-CSIC), Paterna 46980 (Spain); García-Martínez, T. [Radiation Oncology Department, Hospital La Ribera, Alzira 46600 (Spain); Niatsetski, Y.; Nauta, G.; Schuurman, J. [Elekta Brachytherapy, Veenendaal 3905 TH (Netherlands); Ouhib, Z. [Radiation Oncology Department, Lynn Regional Cancer Center, Boca Raton Community Hospital, Boca Raton, Florida 33486 (United States); Ballester, F. [Department of Atomic, Molecular, and Nuclear Physics, University of Valencia, Burjassot 46100 (Spain); Perez-Calatayud, J. [Radiation Oncology Department, La Fe University and Polytechnic Hospital, Valencia 46026, Spain and Department of Radiotherapy, Clínica Benidorm, Benidorm 03501 (Spain)

    2015-08-15

    Purpose: A surface electronic brachytherapy (EBT) device is in fact an x-ray source collimated with specific applicators. Low-energy (<100 kVp) x-ray beam dosimetry faces several challenges that need to be addressed. A number of calibration protocols have been published for x-ray beam dosimetry. The media in which measurements are performed are the fundamental difference between them. The aim of this study was to evaluate the surface dose rate of a low-energy x-ray source with small field applicators using different calibration standards and different small-volume ionization chambers, comparing the values and uncertainties of each methodology. Methods: The surface dose rate of the EBT unit Esteya (Elekta Brachytherapy, The Netherlands), a 69.5 kVp x-ray source with applicators of 10, 15, 20, 25, and 30 mm diameter, was evaluated using the AAPM TG-61 (based on air kerma) and International Atomic Energy Agency (IAEA) TRS-398 (based on absorbed dose to water) dosimetry protocols for low-energy photon beams. A plane parallel T34013 ionization chamber (PTW Freiburg, Germany) calibrated in terms of both absorbed dose to water and air kerma was used to compare the two dosimetry protocols. Another PTW chamber of the same model was used to evaluate the reproducibility between these chambers. Measurements were also performed with two different Exradin A20 (Standard Imaging, Inc., Middleton, WI) chambers calibrated in terms of air kerma. Results: Differences between surface dose rates measured in air and in water using the T34013 chamber range from 1.6% to 3.3%. No field size dependence has been observed. Differences are below 3.7% when measurements with the A20 and the T34013 chambers calibrated in air are compared. Estimated uncertainty (with coverage factor k = 1) for the T34013 chamber calibrated in water is 2.2%–2.4%, whereas it increases to 2.5% and 2.7% for the A20 and T34013 chambers calibrated in air, respectively. The output factors, measured with the PTW chambers

  2. Study of gas mixtures and ageing of the multigap resistive plate chamber used for the ALICE TOF

    CERN Document Server

    Akindinov, A; Anselmo, F; Antonioli, P; Basile, M; Cara Romeo, G; Cifarelli, Luisa; Cindolo, F; Cosenza, F; D'Antone, I; De Caro, A; De Pasquale, S; Di Bartolomeo, A; Fusco-Girard, M; Golovine, V; Guerzoni, M; Guida, M; Hatzifotiadou, D; Kaidalov, A B; Kim, D H; Kim, D W; Kisselev, S M; Laurenti, G; Lioublev, E; Lee, K; Lee, S C; Luvisetto, M L; Margotti, A; Martemyanov, A N; Massera, F; Meneghini, S; Michinelli, R; Nania, R; Otiougova, P; Pancaldi, G; Pesci, A; Pilastrini, R; Pinazza, O; Polozov, P A; Rizzi, M; Scapparone, E; Scioli, G; Sellitto, S B; Semeria, F; Serra, S; Smirnitsky, A V; Tchoumakov, M M; Ugolini, E; Usenko, E; Valenti, G; Voloshin, K G; Williams, M C S; Zagreev, B V; Zampolli, C; Zichichi, A; Zucchini, A; Zuffa, M

    2004-01-01

    We present in this paper a study of the ALICE-TOF Multigap Resistive Plate Chamber (MRPC) performance by using several gas mixtures. We also present a search for possible ageing effects, by studying two MRPCs irradiated at the CERN Gamma Irradiation Facility.

  3. Air bubble-induced detachment of polystyrene particles with different sizes from collector surfaces in a parallel plate flow chamber

    NARCIS (Netherlands)

    Gomez-Suarez, C; van der Mei, HC; Busscher, HJ

    2001-01-01

    Particle size was found to be an important factor in air bubble-induced detachment of colloidal particles from collector surfaces in a parallel plate flow chamber and generally polystyrene particles with a diameter of 806 nm detached less than particles with a diameter of 1400 nm. Particle

  4. Development and characterization of special ionization chambers for computed tomography beams; Desenvolvimento e caracterizacao de camaras de ionizacao especiais para feixes de tomografia computadorizada

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Maysa Costa de

    2016-10-01

    The use of computed tomography (CT) for imaging procedures is growing due to advances in the CT equipment technology, because they allow the obtention of images with better resolution than through other techniques. Therefore, they are responsible for increasing the dose radiation of patients during the procedure. This fact led to a greater concern about the doses received by patients who undergo this type of examination. To perform the dosimetry in CT beams, the most widely used instrument is the pencil type ionization chamber, because this dosimeter has a uniform response to the incident radiation beam for all angles. The conventional ionization chamber, which is available on the market, has a sensitive volume length of 10 cm; however, some studies have shown that this dosimeter has underestimated the dose values. Therefore, in this study two ionization chambers with sensitive volume lengths of 10 cm and 30 cm, making use of low cost national materials, were developed at the Calibration Laboratory of Instruments (LCI-IPEN/CNEN). The characterization of these chambers was performed, and the results were obtained within the international recommended limits. As an application, the developed ionization chambers and a commercial chamber were tested in a clinical tomograph. The developed ionization chambers were analyzed in a complete way for their possible uses. (author)

  5. SU-E-T-415: An Ionization Chamber Array with High Spatial Resolution for External Beam Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Togno, M [Klinikum rechts der Isar, Technische Universitaet Muenchen, Muenchen (Germany); IBA Dosimetry, Schwarzenbruck (Germany); Wilkens, J [Klinikum rechts der Isar, Technische Universitaet Muenchen, Muenchen (Germany); Menichelli, D [IBA Dosimetry, Schwarzenbruck (Germany)

    2014-06-01

    Purpose: To characterize an ionization chamber array technology with high spatial resolution and high charge collection efficiency for external beam radiotherapy. Methods: The prototype under test is a linear array of air vented ionization chambers developed by IBA Dosimetry, consisting of 80 pixels with 3.5mm spatial resolution and 4mm{sup 3} sensitive volume. The detector was characterized in a plastic phantom with {sup 60} Co radiation and MV X-rays from an ELEKTA Agility LINAC (with flattened and unflattened beam qualities). Bias voltage was varied in order to evaluate charge collection efficiency. A commercial array of ionization chambers (MatriXX Evolution, IBA Dosimetry) and an amorphous silicon flat panel in direct conversion configuration were used as references. Results: Repeatability (0.4%) and stability under continuous gamma irradiation (0.3%) are very good, in spite of low active volume and sensitivity (∼200pC/Gy). Charge collection efficiency is higher than 99% already at 150V with ∼2mGy dose per pulse, leading to a ±1.1% sensitivity change with dose per pulse in the range 0.09-2mGy (covering all flattened and unflattened applications). Measured dose profiles are in agreement with MatriXX for fields larger than 2×2cm{sup 2}, in which case the linear array offers a much better characterization of the penumbra region. Down to 1×1cm{sup 2}, measured profiles are in very good agreement with the flat panel. Conclusion: The array represents a valuable tool for the characterization of treatment fields in which high spatial resolution is required, together with the dosimetric performance of air vented ionization chambers. Such a technology would be particularly valuable in association with advanced treatment modalities such as rotational radiotherapy, stereotactic treatments (even with unflattened beam qualities) and proton therapy, due to the insensitivity of the chambers on dose per pulse. In the future, a two dimensional prototype based on this

  6. Characterization of recombination effects in a liquid ionization chamber used for the dosimetry of a radiosurgical accelerator.

    Science.gov (United States)

    Wagner, Antoine; Crop, Frederik; Lacornerie, Thomas; Reynaert, Nick

    2014-05-09

    Most modern radiation therapy devices allow the use of very small fields, either through beamlets in Intensity-Modulated Radiation Therapy (IMRT) or via stereotactic radiotherapy where positioning accuracy allows delivering very high doses per fraction in a small volume of the patient. Dosimetric measurements on medical accelerators are conventionally realized using air-filled ionization chambers. However, in small beams these are subject to nonnegligible perturbation effects. This study focuses on liquid ionization chambers, which offer advantages in terms of spatial resolution and low fluence perturbation. Ion recombination effects are investigated for the microLion detector (PTW) used with the Cyberknife system (Accuray). The method consists of performing a series of water tank measurements at different source-surface distances, and applying corrections to the liquid detector readings based on simultaneous gaseous detector measurements. This approach facilitates isolating the recombination effects arising from the high density of the liquid sensitive medium and obtaining correction factors to apply to the detector readings. The main difficulty resides in achieving a sufficient level of accuracy in the setup to be able to detect small changes in the chamber response.

  7. First demonstration of a sub-keV electron recoil energy threshold in a liquid argon ionization chamber

    Energy Technology Data Exchange (ETDEWEB)

    Sangiorgio, S., E-mail: samuele@llnl.gov [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94550 (United States); Joshi, T.H. [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94550 (United States); Department of Nuclear Engineering, University of California, Berkeley, CA 94720 (United States); Bernstein, A. [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94550 (United States); Coleman, J. [Department of Physics, University of Liverpool, Oxford St, Liverpool L69 7Ze (United Kingdom); Foxe, M. [Department of Mechanical and Nuclear Engineering, Pennsylvania State University, University Park, PA 16802 (United States); Hagmann, C. [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94550 (United States); Jovanovic, I. [Department of Mechanical and Nuclear Engineering, Pennsylvania State University, University Park, PA 16802 (United States); Kazkaz, K. [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94550 (United States); Mavrokoridis, K. [Department of Physics, University of Liverpool, Oxford St, Liverpool L69 7Ze (United Kingdom); Mozin, V.; Pereverzev, S.; Sorensen, P. [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94550 (United States)

    2013-11-11

    We describe the first demonstration of a sub-keV electron recoil energy threshold in a dual-phase liquid argon time projection chamber. This is an important step in an effort to develop a detector capable of identifying the ionization signal resulting from nuclear recoils with energies of order a few keV and below. We obtained this result by observing the peaks in the energy spectrum at 2.82 keV and 0.27 keV, following the K- and L-shell electron capture decay of {sup 37}Ar respectively. The {sup 37}Ar source preparation is described in detail, since it enables calibration that may also prove useful in dark matter direct detection experiments. An internally placed {sup 55}Fe x-ray source simultaneously provided another calibration point at 5.9 keV. We discuss the ionization yield and electron recombination in liquid argon at those three calibration energies. -- Highlights: • We measure sub-keV electron recoils in a dual-phase argon time projection chamber. • Ar-37 is produced via neutron irradiation and used as calibration source. • Ar-37 electron captures at 2.82 and 0.27 keV are measured together with Fe-55 x-rays. • Spurious single ionization electrons provided absolute calibration of charge signal. • Modified Thomas–Imel model describes low-energy electron-recoils in liquid Ar.

  8. A liquid xenon ionization chamber in an all-fluoropolymer vessel

    CERN Document Server

    LePort, F; Baussan, E; Breidenbach, M; Conley, R; DeVoe, R; Diez, M M; Fairbank, W; Farine, J; Fierlinger, P; Flatt, B; Gratta, G; Green, M; Hall, C; Hall, K; Hallman, D; Hargrove, C K; Hodgson, J; Jeng, S; Koffas, T; Leonard, D S; Mackay, D; Martin, Y; Neilson, R; O'Sullivan, K; Odian, A; Ounalli, L; Piepke, A; Pocar, A; Prescott, C Y; Rowson, P C; Schenker, D; Sinclair, D; Skarpaas, K V; Stekhanov, V; Strickland, V; Virtue, C; Vuilleumier, J L; Vuilleumier, J M; Waldman, S J; Wamba, K; Weber, P; Wodin, J; Woisard, D

    2006-01-01

    A novel technique has been developed to build vessels for liquid xenon ionization detectors entirely out of ultra-clean fluoropolymer. We describe the advantages in terms of low radioactivity contamination, provide some details of the construction techniques, and show the energy resolution achieved with a prototype all-fluoropolymer ionization detector.

  9. A Liquid Xenon Ionization Chamber in an All-fluoropolymer Vessel

    Energy Technology Data Exchange (ETDEWEB)

    LePort, F.; Pocar, A.; Bartoszek, L.; DeVoe, R.; Fierlinger, P.; Flatt, B.; Gratta, G.; Green, M.; Montero Diez, M.; Neilson, R.; O' Sullivan, K.; Wodin, J.; Woisard, D.; Baussan, E.; Breidenbach, M.; Conley, R.; Fairbank, W., Jr.; Farine, J.; Hall, K.; Hallman, D.; Hargrove, C.; /Stanford U., Phys. Dept. /Applied Plastics Technology, Bristol

    2007-02-26

    A novel technique has been developed to build vessels for liquid xenon ionization detectors entirely out of ultra-clean fluoropolymer. We describe the advantages in terms of low radioactivity contamination, provide some details of the construction techniques, and show the energy resolution achieved with a prototype all-fluoropolymer ionization detector.

  10. Pooled human immunoglobulins reduce adhesion of Pseudomonas aeruginosa in a parallel plate flow chamber.

    Science.gov (United States)

    Poelstra, K A; van der Mei, H C; Gottenbos, B; Grainger, D W; van Horn, J R; Busscher, H J

    2000-08-01

    The influence of pooled polyclonal immunoglobulin (IgG) interactions with both bacteria and model substrates in altering Pseudomonas aeruginosa surface adhesion is reported. Opsonization of this pathogen by polyclonal human IgG and preadsorption of IgG to glass surfaces both effectively reduce initial deposition rates and surface growth of P. aeruginosa IFO3455 from dilute nutrient broth in a parallel plate flow chamber. Polyclonal IgG depleted of P. aeruginosa-specific antibodies reduces the initial deposition rate or surface growth to levels intermediate between exposed and nonexposed IgG conditions. Bacterial surface properties are changed in the presence of opsonizing IgG. Plateau contact angle analysis via sessile drop technique shows a drop in P. aeruginosa surface hydrophobicity after IgG exposure consistent with a more hydrophilic IgG surface coat. Zeta potential values for opsonized versus nonopsonized bacteria exhibit little change. X-ray photoelectron spectroscopy measurements provide surface compositional evidence for IgG attachment to bacterial surfaces. Surface elemental ratios attributed to IgG protein signals versus those attributed primarily to bacterial polysaccharide surface or lipid membrane change with IgG opsonization. Direct evidence for antibody-modified P. aeruginosa surface properties correlates both with reduction of bacterial adhesion to glass surfaces under flow in nutrient medium reported and previous reports of IgG efficacy against P. aeruginosa motility in vitro and infection in vivo.

  11. Analysis and interpretation of the performance degradation of glass Resistive Plate Chambers operated in streamer mode

    CERN Document Server

    Calcaterra, A; Patteri, P; Piccolo, M; Della Mea, G; Restello, S; Ferri, F; Musella, P; Redaelli, N; Tabarelli de Fatis, T; Tinti, G; Mannocchi, G; Trinchero, G

    2007-01-01

    The long-term stability of Resistive Plate Chambers (RPCs) with glass electrodes was studied for one year with a dedicated test station hosting about 10 m2 of detectors. RPCs were operated in streamer mode with a ternary gas mixture containing argon (27%), isobutane (9%) and tetrafluoroethane (64%). Environmental conditions were kept under control and, in particular, the water pollution in the gas, deemed responsible for the degradation of glass RPC performance, was monitored never to exceed 30 ppm in the exhaust line. Evidence for a substantial aging of the detectors was observed, resulting in a loss of efficiency correlated to an increased rate of spurious streamers. This can be ascribed to the chemical attack of the glass surface by hydrofluoric acid formed in the streamer process, as confirmed by detailed morphological and chemical analyses of the electrode surface. Our results strengthen the indication that the instability of glass RPCs in the long term is related to the use of fluorocarbons as quenching...

  12. Development of a fully differential multi-gap resistive plate chamber for the CBM experiment

    Energy Technology Data Exchange (ETDEWEB)

    Deppner, Ingo Martin

    2013-11-21

    The subject of this thesis is the development of a modern time-of-flight detector, a MRPC (Multi-gap Resistive Plate Chamber) for the Compressed Baryonic Matter (CBM) experiment. The main goal of CBM is the investigation of the phase diagram of strongly interacting matter in the region of the highest baryon densities. In order to measure the necessary observables with unprecedented precision an excellent particle identification is required. The key element providing hadron identification in heavy ion reaction at incident energies between 2 and 35 AGeV is a 120 m{sup 2} large Time-of-Flight (ToF) wall composed of MRPCs. The ToF-wall is subdivided in a high rate, an intermediate rate and a low rate region. In this thesis we present a full-size demonstrator for the intermediate rate region and for the low rate region. In-beam and cosmic ray tests demonstrated that these fully differential prototypes fulfill the necessary requirements which are a counter time resolution of about 50 ps, an efficiency above 95 %, a rate capability of about 1 kHz/cm{sup 2} and a granularity between 25 - 50 cm{sup 2}. Based on these counters the so-called ''outer ToF-wall'' was designed in this work.

  13. Front-End electronics development for the new Resistive Plate Chamber detector of HADES

    Science.gov (United States)

    Gil, A.; Belver, D.; Cabanelas, P.; Díaz, J.; Garzón, J. A.; González-Díaz, D.; Koenig, W.; Lange, J. S.; Marín, J.; Montes, N.; Skott, P.; Traxler, M.

    2007-11-01

    In this paper we present the new RPC wall, which is being installed in the HADES detector at Darmstadt GSI. It consists of time-of-flight (TOF) detectors used for both particle identification and triggering. Resistive Plate Chamber (RPC) detectors are becoming widely used because of their excellent TOF capabilities and reduced cost. The wall will contain 1024 RPC modules, covering an active area of around 7 m2, replacing the old TOFino detector at the low polar angle region. The excellent TOF and good charge resolutions of the new detector will improve the time resolution to values better than 100 ps. The Front-End electronics for the readout of the RPC signals is implemented with two types of boards to satisfy the space constraints: the Daughterboards are small boards that amplify the low level signals from the detector and provide fast discriminators for time of flight measurements, as well as an integrator for charge measurements. The Motherboard provides stable DC voltages and a stable ground, threshold DACs for the discriminators, multiplicity trigger and impedance matched paths for transfer of time window signals that contain information about time and charge. These signals are sent to a custom TDC board that label each event and send data through Ethernet to be conveniently stored.

  14. ANALYSIS OF PULSATILE FLOW IN THE PARALLEL-PLATE FLOW CHAMBER WITH SPATIAL SHEAR STRESS GRADIENT

    Institute of Scientific and Technical Information of China (English)

    QIN Kai-rong; HU Xu-qu; LIU Zhao-rong

    2007-01-01

    The Parallel-Plate Flow Chamber (PPFC), of which the height is far smaller than its own length and width, is one of the main apparatus for the in-vitro study of the mechanical behavior of cultured vascular Endothelical Cells (ECs) exposed to fluid shear stress. The steady flow in different kinds of PPFC has been extensively investigated, whereas, the pulsatile flow in the PPFC has little attention. In consideration of the characteristics of geometrical size and pulsatile flow in the PPFC, the 3-D pulsatile flow was decomposed into a 2-D pulsatile flow in the vertical plane, and an incompressible plane potential flow in the horizontal plane. A simple method was then proposed to analyze the pulsatile flow in the PPFC with spatial shear stress gradient. On the basis of the method, the pulsatile fluid shear stresses in several reported PPFCs with spatial shear stress gradients were calculated. The results were theoretically meaningful for applying the PPFCs in-vitro, to simulate the pulsatile fluid shear stress environment, to which cultured ECs were exposed.

  15. Multigap Resistive Plate Chambers for EAS study in the EEE Project

    Science.gov (United States)

    Abbrescia, M.; An, S.; Antolini, R.; Badala, A.; Baldini Ferroli, R.; Bencivenni, G.; Blanco, F.; Bressan, E.; Chiavassa, A.; Chiri, C.; Cifarelli, L.; Cindolo, F.; Coccia, E.; de Pasquale, S.; di Giovanni, A.; Hatzifotiadou, D.; Imponente, G.; Kim, J.; La Rocca, P.; Librizzi, F.; Maggiora, A.; Menghetti, H.; Miozzi, S.; Moro, R.; Panareo, M.; Pappalardo, G.S.; Piragino, G.; Riggi, F.; Romano, F.; Sartorelli, G.; Sbarra, C.; Selvi, M.; Serci, S.; Williams, C.; Zichichi, A.; Zuyenski, R.

    The EEE (Extreme Energy Event) Project is an extensive air shower experiment devoted to the study of very high energy events through the detection at ground of the muon component of the shower. The detectors are installed inside many Italian High Schools, involving students in the experiment. The detector used is a tracking telescope made of 3 planes of Multi-gap Resistive Plate Chambers (MRPCs), a simplified, large and cheap version of the detector designed for the time of flight measurements (TOF) of the ALICE experiment at LHC. Exploiting the concept of the multiple small gas gaps combined with the use of high gain and fast gas mixture (Freon and SF6 based), the MRPCs show an overall time resolution of 100 ps. The particle tracking is performed equipping MRPCs with 24 copper strips read at both ends by front end electronics based on NINO ASIC and using commercial multi-hit TDCs. The MRPCs for the EEE experiment are built at CERN by Italian High School students and teachers under the supervision of INFN and Centro “E. Fermi” experts. After construction they are shipped to Italy and after preliminary tests they are installed inside the schools. Here we present the status and first results of the already operating stations.

  16. The analog Resistive Plate Chamber detector of the ARGO-YBJ experiment

    CERN Document Server

    Bartoli, B; Bi, X J; Cao, Z; Catalanotti, S; Chen, S Z; Chen, T L; Cui, S W; Dai, B Z; D'Amone, A; Danzengluobu,; De Mitri, I; Piazzoli, B D'Ettorre; Di Girolamo, T; Di Sciascio, G; Feng, C F; Feng, Zhaoyang; Feng, Zhenyong; Gou, Q B; Guo, Y Q; He, H H; Hu, Haibing; Hu, Hongbo; Iacovacci, M; Iuppa, R; Jia, H Y; Labaciren,; Li, H J; Liu, C; Liu, J; Liu, M Y; Lu, H; Ma, L L; Ma, X H; Mancarella, G; Mari1, S M; Marsella, G; Mastroianni, S; Montini, P; Ning, C C; Perrone, L; Pistilli, P; Salvini1, P; Santonico, R; Shen, P R; Sheng, X D; Shi, F; Surdo, A; Tan, Y H; Vallania, P; Vernetto, S; Vigorito, C; Wang, H; Wu, C Y; Wu, H R; Xue, L; Yang, Q Y; Yang, X C; Yao, Z G; Yuan, A F; Zha, M; Zhang, H M; Zhang, L; Zhang, X Y; Zhang, Y; Zhao, J; Zhaxiciren,; Zhaxisangzhu,; Zhou, X X; Zhu, F R; Zhu, Q Q

    2015-01-01

    The ARGO-YBJ experiment has been in stable data taking from November 2007 till February 2013 at the YangBaJing Cosmic Ray Observatory (4300 m a.s.l.). The detector consists of a single layer of Resistive Plate Chambers (RPCs) ( about 6700 m^2}) operated in streamer mode. The signal pick-up is obtained by means of strips facing one side of the gas volume. The digital readout of the signals, while allows a high space-time resolution in the shower front reconstruction, limits the measurable energy to a few hundred TeV. In order to fully investigate the 1-10 PeV region, an analog readout has been implemented by instrumenting each RPC with two large size electrodes facing the other side of the gas volume. Since December 2009 the RPC charge readout has been in operation on the entire central carpet (about 5800 m^2). In this configuration the detector is able to measure the particle density at the core position where it ranges from tens to many thousands of particles per m^2. Thus ARGO-YBJ provides a highly detailed...

  17. Improvement of time resolution in large area single gap Resistive Plate Chambers

    Science.gov (United States)

    Bhatt, A. D.; Majumder, G.; Mondal, N. K.; Pathaleswar; Satyanarayana, B.

    2017-02-01

    The intrinsic gain of a single gap Resistive Plate Chamber (RPC) is affected by several factors, e.g., variation in the thicknesses of glass electrode, button and side spacer, different composition of gas due to improper flow, leaks in the detector volume, etc. The position dependent gain is one of the dominant components of the time resolution of a large area single gap RPC. Besides, strip multiplicity as well as lateral position of the trajectory of the charged particle in RPC strip also result in variation of timing information. The observation of large signals produced by the charged particles passing close to the button spacers also has some repercussion on the overall timing resolution of an RPC. A new offline correction technique to achieve time resolution below 1 ns is reported in this paper. This technique is validated using an RPC cosmic ray telescope (1 × 1m2) at TIFR. We also suggest a few alternative solutions to improve the time resolution during the operational phase of the INO-ICAL experiment. The techniques presented here are useful not only for ICAL, but also for any detector deploying RPCs in large scale.

  18. Patient specific quality assurance of RapidArc pre treatment plans using semiflex 0.125 cc ionization chamber

    Science.gov (United States)

    Kumar, S. A. Syam; Vivekanandan, Nagarajan

    2017-01-01

    Patient specific pre-treatment quality assurance for RapidArc plans were analyzed for hundred patients for different sites. Verification plan was created for each treatment plan in Eclipse 8.6 treatment planning system with the semiflex ionization chamber and the octavius phantom. Absolute point dose were measured for head and neck, thorax and abdomen cases using semiflex (0.125 cc) ionization chamber. Positive absolute mean dose variation of 0.56% was observed with thorax cases with a standard deviation (SD) of ±1.13 between the plans with a range of -1.78% to 2.70%. Negative percentage dose errors were found with head and neck and abdomen cases, with a mean variation of -0.43% (SD±1.50), (range -3.25% to 2.85%) and -0.35% (SD±1.48), (range -3.10% to 2.65%) for head and neck and abdomen cases respectively. Evaluation has been done using PTW verisoft software by keeping the passing criteria as 3 mm DTA, 3% DD, for 95% of the evaluated dose points. The maximum percentage value failed in gamma analysis was found to be 4.95, 4.75, and 4.88 for head and neck, thorax, and abdomen cases respectively. In all the cases analyzed the percentage dose points failed the gamma criteria is less than 5%. On the basis of the studies performed it can be concluded that the semiflex ionization chamber having a volume of 0.125 cc can be used efficiently for measuring the pre-treatment quality assurance of RapidArc plans for all the sites.

  19. First demonstration of a sub-keV electron recoil energy threshold in a liquid argon ionization chamber

    CERN Document Server

    Sangiorgio, S; Coleman, J; Foxe, M; Hagmann, C; Joshi, T H; Jovanovic, I; Kazkaz, K; Mavrokoridis, K; Mozin, V; Pereverzev, S; Sorensen, P

    2013-01-01

    We make a first demonstration of a sub-keV electron recoil energy threshold in a dual-phase liquid argon time-projection chamber. This is an important step in a program to build a detector capable of identifying the ionization signal resulting from nuclear recoils at a few keV and below. We obtained this result by observing the peaks in the energy spectrum at 2.82 keV and 0.27 keV, following the K- and L-shell electron capture decay of Ar-37. We describe the details of the Ar-37 source preparation, as this calibration technique may prove useful, e.g. for dark matter direct detection experiments. A Fe-55 internal x-ray source was also measured simultaneously and provided another calibration point at 5.9 keV. We discuss the ionization yield and electron recombination in liquid argon at the three calibration energies.

  20. Correction factors for ionization chamber dosimetry in CyberKnife: Machine-specific, plan-class, and clinical fields

    Energy Technology Data Exchange (ETDEWEB)

    Gago-Arias, Araceli; Antolin, Elena; Fayos-Ferrer, Francisco; Simon, Rocio; Gonzalez-Castano, Diego M.; Palmans, Hugo; Sharpe, Peter; Gomez, Faustino; Pardo-Montero, Juan [Departamento de Fisica de Particulas, Facultad de Fisica, Universidade de Santiago de Compostela, A Coruna 15782 (Spain); Servicio de Fisica Medica, Hospital Ruber Internacional, Madrid 28034 (Spain); Departamento de Fisica de Particulas, Facultad de Fisica, Universidade de Santiago de Compostela, A Coruna 15782, Spain and Laboratorio de Radiofisica, Universidade de Santiago de Compostela, Santiago de Compostela, A Coruna 15782 (Spain); National Physical Laboratory, Teddington, Middx TW11 OLW (United Kingdom); Departamento de Fisica de Particulas, Facultad de Fisica, Universidade de Santiago de Compostela, A Coruna 15782, Spain and Laboratorio de Radiofisica, Universidade de Santiago de Compostela, Santiago de Compostela, A Coruna 15782 (Spain); Departamento de Fisica de Particulas, Facultad de Fisica, Universidade de Santiago de Compostela, A Coruna 15782 (Spain)

    2013-01-15

    Purpose: The aim of this work is the application of the formalism for ionization chamber reference dosimetry of small and nonstandard fields [R. Alfonso, P. Andreo, R. Capote, M. S. Huq, W. Kilby, P. Kjaell, T. R. Mackie, H. Palmans, K. Rosser, J. Seuntjens, W. Ullrich, and S. Vatnitsky, 'A new formalism for reference dosimetry of small and nonstandard fields,' Med. Phys. 35, 5179-5186 (2008)] to the CyberKnife robotic radiosurgery system. Correction factors for intermediate calibration fields, a machine-specific reference field (msr) and two plan-class specific reference fields (pcsr), have been studied. Furthermore, the applicability of the new formalism to clinical dosimetry has been analyzed through the investigation of two clinical treatments. Methods: PTW31014 and Scanditronix-Wellhofer CC13 ionization chamber measurements were performed for the fields under investigation. Absorbed dose to water was determined using alanine reference dosimetry, and experimental correction factors were calculated from alanine to ionization chamber readings ratios. In addition, correction factors were calculated for the intermediate calibration fields and one of the clinical treatment fields using the Monte Carlo method and these were compared with the experimental values. Results: Overall correction factors deviating from unity by approximately 2% were obtained from both measurements and simulations, with values below and above unity for the studied intermediate calibration fields and clinical fields for the ionization chambers under consideration. Monte Carlo simulations yielded correction factors comparable with those obtained from measurements for the machine-specific reference field, although differences from 1% to 3.3% were observed between measured and calculated correction factors for the composite intermediate calibration fields. Dose distribution inhomogeneities are thought to be responsible for such discrepancies. Conclusions: The differences found between

  1. A method for measuring the electron drift velocity in working gas using a Frisch-grid ionization chamber

    Science.gov (United States)

    Bai, Huaiyong; Wang, Zhimin; Zhang, Luyu; Chen, Jinxiang; Zhang, Guohui

    2016-12-01

    A method for measuring the electron drift velocity in working gas is proposed. Based on the cathode and the anode signal waveforms of the Frisch-grid ionization chamber, the electron drift velocity is extracted. With this method, the electron drift velocities in Ar + 10% CH4, Ar + 3.5% CO2 and Kr + 2.7% CO2 gases have been measured and the results are compared with the existing measurements and the simulating results. Using this method, the electron drift velocity can be monitored throughout the experiment of charged particle without bothering the measurement of other parameters, such as the energy and orientation.

  2. Evaluation of dosimetric characteristics of multi-leaf and conventional collimated radiation fields using a scanning liquid ionization chamber EPID.

    Science.gov (United States)

    Mohammadi, M; Bezak, E

    2008-12-01

    The characteristics of radiation fields set up using conventional and Multi-Leaf collimators were investigated using a Scanning Liquid Ionization Chamber Electronic Portal Imaging Device (SLIC-EPID). Results showed that the radiation fields set up using MLCs are generally larger than those set up using conventional collimators. A significant difference was observed between the penumbra width for conventional and MLC radiation fields. SLIC-EPID was found to be a sensitive device to evaluate the characteristics of the radiation fields generated with MLCs.

  3. A prototype liquid Argon Time Projection Chamber for the study of UV laser multi-photonic ionization

    CERN Document Server

    Rossi, B; Ereditato, A; Haug, S; Hanni, R; Hess, M; Janos, S; Juget, F; Kreslo, I; Lehmann, S; Lutz, P; Mathieu, R; Messina, M; Moser, U; Nydegger, F; Schutz, H U; Weber, M S; Zeller, M

    2009-01-01

    This paper describes the design, realization and operation of a prototype liquid Argon Time Projection Chamber (LAr TPC) detector dedicated to the development of a novel online monitoring and calibration system exploiting UV laser beams. In particular, the system is intended to measure the lifetime of the primary ionization in LAr, in turn related to the LAr purity level. This technique could be exploited by present and next generation large mass LAr TPCs for which monitoring of the performance and calibration plays an important role. Results from the first measurements are presented together with some considerations and outlook.

  4. Discovery of multiple, ionization-created CS{sub 2} anions and a new mode of operation for drift chambers

    Energy Technology Data Exchange (ETDEWEB)

    Snowden-Ifft, Daniel P. [Department of Physics, Occidental College, Los Angeles, California 90041 (United States)

    2014-01-15

    This paper focuses on the surprising discovery of multiple species of ionization-created CS{sub 2} anions in gas mixtures containing electronegative CS{sub 2} and O{sub 2}, identified by their slightly different drift velocities. Data are presented to understand the formation mechanism and identity of these new anions. Regardless of the micro-physics, however, this discovery offers a new, trigger-less mode of operation for the drift chambers. A demonstration of trigger-less operation is presented.

  5. Evaluation of the energy dependence of ionization chambers pencil type calibrated beam tomography standards; Avaliacao da dependencia energetica de camaras de ionizacao do tipo lapis calibradas em feixes padroes de tomografia

    Energy Technology Data Exchange (ETDEWEB)

    Fontes, Ladyjane Pereira; Potiens, Maria da Penha A., E-mail: lpfontes@ipen.br [Instituto de Pesquisas Energeticas e Nucleres (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    The Instrument Calibration Laboratory of IPEN (LCI - IPEN) performs calibrations of pencil-type ionization chambers (IC) used in measures of dosimetric survey on clinical systems of Computed Tomography (CT). Many users make mistakes when using a calibrated ionization chamber in their CT dosimetry systems. In this work a methodology for determination of factors of correction for quality (Kq) through the calibration curve that is specific for each ionization chamber was established. Furthermore, it was possible to demonstrate the energy dependence on an pencil-type Ionization Chamber(IC) calibrated at the LCI - IPEN. (author)

  6. Direct determination of k Q for Farmer-type ionization chambers in a clinical scanned carbon ion beam using water calorimetry.

    Science.gov (United States)

    Osinga-Blättermann, J-M; Brons, S; Greilich, S; Jäkel, O; Krauss, A

    2017-03-21

    Until now, the dosimetry of carbon ions with ionization chambers has not reached the same level of accuracy as that of high-energy photons. This is mainly caused by the approximately threefold larger uncertainty of the k Q factor of ionization chambers, which, due to the lack of experimental data, is still derived by calculations. Measurements of absorbed dose to water, D w, by means of water calorimetry have now been performed in the entrance channel of a scanned 6 cm  ×  6 cm radiation field of 429 MeV/u carbon ions, allowing the direct calibration of ionization chambers and thus the experimental determination of k Q. Within this work, values for k Q have been determined for the Farmer-type ionization chambers FC65-G and TM30013. A detailed investigation of the radiation field enabled the accurate determination of correction factors needed for both calorimetric and ionometric measurements. Finally, a relative standard measurement uncertainty of 0.8% (k  =  1) could be achieved for the experimental k Q values. For both chambers, the experimental k Q factors were found to be about 1% larger than those tabulated in the German DIN 6801-1 protocol, whereas compared to the theoretical values stated in the TRS-398 protocol, the experimental k Q value agrees within 0.4% for the TM30013 chamber but is about 1% lower in the case of the FC65-G chamber.

  7. Direct determination of k Q for Farmer-type ionization chambers in a clinical scanned carbon ion beam using water calorimetry

    Science.gov (United States)

    Osinga-Blättermann, J.-M.; Brons, S.; Greilich, S.; Jäkel, O.; Krauss, A.

    2017-03-01

    Until now, the dosimetry of carbon ions with ionization chambers has not reached the same level of accuracy as that of high-energy photons. This is mainly caused by the approximately threefold larger uncertainty of the k Q factor of ionization chambers, which, due to the lack of experimental data, is still derived by calculations. Measurements of absorbed dose to water, D w, by means of water calorimetry have now been performed in the entrance channel of a scanned 6 cm  ×  6 cm radiation field of 429 MeV/u carbon ions, allowing the direct calibration of ionization chambers and thus the experimental determination of k Q. Within this work, values for k Q have been determined for the Farmer-type ionization chambers FC65-G and TM30013. A detailed investigation of the radiation field enabled the accurate determination of correction factors needed for both calorimetric and ionometric measurements. Finally, a relative standard measurement uncertainty of 0.8% (k  =  1) could be achieved for the experimental k Q values. For both chambers, the experimental k Q factors were found to be about 1% larger than those tabulated in the German DIN 6801-1 protocol, whereas compared to the theoretical values stated in the TRS-398 protocol, the experimental k Q value agrees within 0.4% for the TM30013 chamber but is about 1% lower in the case of the FC65-G chamber.

  8. Positioning of a plane-parallel ionization chamber in clinical electron beams and the impact on perturbation factors

    Energy Technology Data Exchange (ETDEWEB)

    Zink, K; Wulff, J [Institut fuer Medizinische Physik und Strahlenschutz-IMPS, University of Applied Sciences Giessen-Friedberg, Wiesenstr. 14, D-35390 Giessen (Germany)], E-mail: klemens.zink@tg.fh-giessen.de

    2009-04-21

    Current dosimetry protocols recommend the use of plane-parallel ionization chambers for the dosimetry of clinical electron beams. The necessary perturbation corrections p{sub wall} and p{sub cav} are assumed to be unity, independent of the depth of measurement and the energy of the primary electrons. To verify these assumptions detailed Monte Carlo studies of a Roos chamber in clinical electron beams with energies in the range of 6-21 MeV are performed at different depths in water and analyzed in terms of Spencer-Attix cavity theory. Separate simulations for the perturbation corrections p{sub wall} and p{sub cav} indicate quite different properties of both correction factors with depth. Dose as well as fluence calculations show a nearly depth-independent wall correction factor for a shift of the Roos chamber {delta}z = -0.017 cm toward the focus. This value is in good agreement with the positioning recommendation given in all dosimetry protocols. Regarding the fluence perturbation p{sub cav} the simulation of the electron fluence inside the air cavity in comparison to water unambiguously reveals an in-scattering of low energy electrons, despite the fact, that the cavity is 'well guarded'. For depths beyond the reference depth z{sub ref} this effect is superimposed by an increased loss of primary electrons from the beam resulting in p{sub cav} > 1. This effect is largest for low electron energies but present for all electron energies involved in this study. Based on the different depth dependences of p{sub wall} and p{sub cav} it is possible to choose a chamber shift {delta}z in a way to minimize the depth dependence of the overall perturbation factor p. For the Roos chamber this shift is {delta}z = -0.04 cm independent of electron energy.

  9. Positioning of a plane-parallel ionization chamber in clinical electron beams and the impact on perturbation factors.

    Science.gov (United States)

    Zink, K; Wulff, J

    2009-04-21

    Current dosimetry protocols recommend the use of plane-parallel ionization chambers for the dosimetry of clinical electron beams. The necessary perturbation corrections p(wall) and p(cav) are assumed to be unity, independent of the depth of measurement and the energy of the primary electrons. To verify these assumptions detailed Monte Carlo studies of a Roos chamber in clinical electron beams with energies in the range of 6-21 MeV are performed at different depths in water and analyzed in terms of Spencer-Attix cavity theory. Separate simulations for the perturbation corrections p(wall) and p(cav) indicate quite different properties of both correction factors with depth. Dose as well as fluence calculations show a nearly depth-independent wall correction factor for a shift of the Roos chamber Deltaz = -0.017 cm toward the focus. This value is in good agreement with the positioning recommendation given in all dosimetry protocols. Regarding the fluence perturbation p(cav) the simulation of the electron fluence inside the air cavity in comparison to water unambiguously reveals an in-scattering of low energy electrons, despite the fact, that the cavity is 'well guarded'. For depths beyond the reference depth z(ref) this effect is superimposed by an increased loss of primary electrons from the beam resulting in p(cav) > 1. This effect is largest for low electron energies but present for all electron energies involved in this study. Based on the different depth dependences of p(wall) and p(cav) it is possible to choose a chamber shift Deltaz in a way to minimize the depth dependence of the overall perturbation factor p. For the Roos chamber this shift is Deltaz = -0.04 cm independent of electron energy.

  10. Beta-efficiency of a typical gas-flow ionization chamber using GEANT4 Monte Carlo simulations

    Directory of Open Access Journals (Sweden)

    Hussain Abid

    2011-01-01

    Full Text Available GEANT4 based Monte Carlo simulations have been carried out for the determination of efficiency and conversion factors of a gas-flow ionization chamber for beta particles emitted by 86 different radioisotopes covering the average-b energy range of 5.69 keV-2.061 MeV. Good agreements were found between the GEANT4 predicted values and corresponding experimental data, as well as with EGS4 based calculations. For the reported set of b-emitters, the values of the conversion factor have been established in the range of 0.5×1013-2.5×1013 Bqcm-3/A. The computed xenon-to-air conversion factor ratios have attained the minimum value of 0.2 in the range of 0.1-1 MeV. As the radius and/or volume of the ion chamber increases, conversion factors approach a flat energy response. These simulations show a small, but significant dependence of ionization efficiency on the type of wall material.

  11. A combined segmented anode gas ionization chamber and time-of-flight detector for heavy ion elastic recoil detection analysis

    Science.gov (United States)

    Ström, Petter; Petersson, Per; Rubel, Marek; Possnert, Göran

    2016-10-01

    A dedicated detector system for heavy ion elastic recoil detection analysis at the Tandem Laboratory of Uppsala University is presented. Benefits of combining a time-of-flight measurement with a segmented anode gas ionization chamber are demonstrated. The capability of ion species identification is improved with the present system, compared to that obtained when using a single solid state silicon detector for the full ion energy signal. The system enables separation of light elements, up to Neon, based on atomic number while signals from heavy elements such as molybdenum and tungsten are separated based on mass, to a sample depth on the order of 1 μm. The performance of the system is discussed and a selection of material analysis applications is given. Plasma-facing materials from fusion experiments, in particular metal mirrors, are used as a main example for the discussion. Marker experiments using nitrogen-15 or oxygen-18 are specific cases for which the described improved species separation and sensitivity are required. Resilience to radiation damage and significantly improved energy resolution for heavy elements at low energies are additional benefits of the gas ionization chamber over a solid state detector based system.

  12. Design and Development of Ionization Chamber for Detection of X-Ray Beam AT INDUS-2 RRCAT

    Directory of Open Access Journals (Sweden)

    Nawaz Ali Sayed

    2013-02-01

    Full Text Available The goal of this paper was to design and develop a Microcontroller based data acquisition unit for detection of X-ray flux through Ionization chamber that will remotely control and monitor the ultra-low current signal detection analog module precisely. This application will be useful to measure the intensity of x-ray flux through the ionization chamber in a beam line of synchrotron radiation source which is mounted in INDUS-2. The beam line area is highly restricted because of hazardous radiation, so through this application remote interfacing provides for the ultra-low current signal detection card that can be controlled by personal computer. To design a perfect embedded system there are many issues like designing a proper PCB, to achieve the specified resolution of the ADC used in chip, code developed using any compiler should be within the limit of the memory of the microcontroller system and integrity of the devices used in the circuit. Initially explore and gain the knowledge of embedded systems by doing a small project and writing the code for the same, and gain a knowledge how the system works. Programming has done in assembly language 8051, for schematic design PCB design tool ORCAD (VERSION 9.0 use

  13. Correction of measured Gamma-Knife output factors for angular dependence of diode detectors and PinPoint ionization chamber.

    Science.gov (United States)

    Hršak, Hrvoje; Majer, Marija; Grego, Timor; Bibić, Juraj; Heinrich, Zdravko

    2014-12-01

    Dosimetry for Gamma-Knife requires detectors with high spatial resolution and minimal angular dependence of response. Angular dependence and end effect time for p-type silicon detectors (PTW Diode P and Diode E) and PTW PinPoint ionization chamber were measured with Gamma-Knife beams. Weighted angular dependence correction factors were calculated for each detector. The Gamma-Knife output factors were corrected for angular dependence and end effect time. For Gamma-Knife beams angle range of 84°-54°. Diode P shows considerable angular dependence of 9% and 8% for the 18 mm and 14, 8, 4 mm collimator, respectively. For Diode E this dependence is about 4% for all collimators. PinPoint ionization chamber shows angular dependence of less than 3% for 18, 14 and 8 mm helmet and 10% for 4 mm collimator due to volumetric averaging effect in a small photon beam. Corrected output factors for 14 mm helmet are in very good agreement (within ±0.3%) with published data and values recommended by vendor (Elekta AB, Stockholm, Sweden). For the 8 mm collimator diodes are still in good agreement with recommended values (within ±0.6%), while PinPoint gives 3% less value. For the 4 mm helmet Diodes P and E show over-response of 2.8% and 1.8%, respectively. For PinPoint chamber output factor of 4 mm collimator is 25% lower than Elekta value which is generally not consequence of angular dependence, but of volumetric averaging effect and lack of lateral electronic equilibrium. Diodes P and E represent good choice for Gamma-Knife dosimetry.

  14. DAVID--a translucent multi-wire transmission ionization chamber for in vivo verification of IMRT and conformal irradiation techniques.

    Science.gov (United States)

    Poppe, B; Thieke, C; Beyer, D; Kollhoff, R; Djouguela, A; Rühmann, A; Willborn, K C; Harder, D

    2006-03-07

    Permanent in vivo verification of IMRT photon beam profiles by a radiation detector with spatial resolution, positioned on the radiation entrance side of the patient, has not been clinically available so far. In this work we present the DAVID system, which is able to perform this quality assurance measurement while the patient is treated. The DAVID system is a flat, multi-wire transmission-type ionization chamber, placed in the accessory holder of the linear accelerator and constructed from translucent materials in order not to interfere with the light field. Each detection wire of the chamber is positioned exactly in the projection line of a MLC leaf pair, and the signal of each wire is proportional to the line integral of the ionization density along this wire. Thereby, each measurement channel essentially presents the line integral of the ionization density over the opening width of the associated leaf pair. The sum of all wire signals is a measure of the dose-area product of the transmitted photon beam and of the total radiant energy administered to the patient. After the dosimetric verification of an IMRT plan, the values measured by the DAVID system are stored as reference values. During daily treatment the signals are re-measured and compared to the reference values. A warning is output if there is a deviation beyond a threshold. The error detection capability is a leaf position error of less than 1 mm for an isocentric 1 cm x 1 cm field, and of 1 mm for an isocentric 20 cm x 20 cm field.

  15. Practical method for determination of air kerma by use of an ionization chamber toward construction of a secondary X-ray field to be used in clinical examination rooms.

    Science.gov (United States)

    Maehata, Itsumi; Hayashi, Hiroaki; Kimoto, Natsumi; Takegami, Kazuki; Okino, Hiroki; Kanazawa, Yuki; Tominaga, Masahide

    2016-07-01

    We propose a new practical method for the construction of an accurate secondary X-ray field using medical diagnostic X-ray equipment. For accurate measurement of the air kerma of an X-ray field, it is important to reduce and evaluate the contamination rate of scattered X-rays. To determine the rate quantitatively, we performed the following studies. First, we developed a shield box in which an ionization chamber could be set at an inner of the box to prevent detection of the X-rays scattered from the air. In addition, we made collimator plates which were placed near the X-ray source for estimation of the contamination rate by scattered X-rays from the movable diaphragm which is a component of the X-ray equipment. Then, we measured the exposure dose while changing the collimator plates, which had diameters of 25-90 mm(ϕ). The ideal value of the exposure dose was derived mathematically by extrapolation to 0 mm(ϕ). Tube voltages ranged from 40 to 130 kV. Under these irradiation conditions, we analyzed the contamination rate by the scattered X-rays. We found that the contamination rates were less than 1.7 and 2.3 %, caused by air and the movable diaphragm, respectively. The extrapolated value of the exposure dose has been determined to have an uncertainty of 0.7 %. The ionization chamber used in this study was calibrated with an accuracy of 5 %. Using this kind of ionization chamber, we can construct a secondary X-ray field with an uncertainty of 5 %.

  16. Air density dependence of the response of the PTW SourceCheck 4pi ionization chamber for (125)I brachytherapy seeds.

    Science.gov (United States)

    Torres Del Río, J; Tornero-López, A M; Guirado, D; Pérez-Calatayud, J; Lallena, A M

    2017-06-01

    To analyze the air density dependence of the response of the new SourceCheck 4pi ionization chamber, manufactured by PTW. The air density dependence of three different SourceCheck 4pi chambers was studied by measuring (125)I sources. Measurements were taken by varying the pressure from 746.6 to 986.6hPa in a pressure chamber. Three different HDR 1000 Plus ionization chambers were also analyzed under similar conditions. A linear and a potential-like function of the air density were fitted to experimental data and their achievement in describing them was analyzed. SourceCheck 4pi chamber response showed a residual dependence on the air density once the standard pressure and temperature factor was applied. The chamber response was overestimated when the air density was below that under normal atmospheric conditions. A similar dependence was found for the HDR 1000 Plus chambers analyzed. A linear function of the air density permitted a very good description of this residual dependence, better than with a potential function. No significant variability between the different specimens of the same chamber model studied was found. The effect of overestimation observed in the chamber responses once they are corrected for the standard pressure and temperature may represent a non-negligible ∼4% overestimation in high altitude cities as ours (700m AMSL). This overestimation behaves linearly with the air density in all cases analyzed. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  17. Calibration of well-type ionization chambers; Calibracao de camaras de ionizacao do tipo poco

    Energy Technology Data Exchange (ETDEWEB)

    Alves, C.F.E.; Leite, S.P.; Pires, E.J.; Magalhaes, L.A.G.; David, M.G.; Almeida, C.E. de, E-mail: cfealves@gmail.com [Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, RJ (Brazil). Lab. de Ciencias Radiologicas; Di Prinzio, R. [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2015-07-01

    This paper presents the methodology developed by the Laboratorio de Ciencias Radiologicas and presently in use for determining of the calibration coefficient for well-type chambers used in the dosimetry of {sup 192}Ir high dose rate sources. Uncertainty analysis involving the calibration procedure are discussed. (author)

  18. Determination of absorbed dose in electron beams using parallel-plane ionization chambers; Determinacao de dose absorvida em feixes de eletrons utilizando camaras de ionizacao de placas paralelas

    Energy Technology Data Exchange (ETDEWEB)

    Bulla, Roseli T.; Caldas, Linda V.E. [Instituto de Pesquisas Nucleares (IPEN), Sao Paulo, SP (Brazil)]. E-mail: lcaldas@ipen.br

    2004-06-01

    Objective: The objective of this paper was to establish a procedure for the determination of calibration factors and absorbed doses in electron beams. Materials And Methods: An irradiator with a {sup 60} Co source and a linear accelerator Varian, Clinac 2100C, with photon and electron beams, were utilized. Thimble type and parallel-plane ionization chambers were tested. Results: The measurement systems showed very good results in the preliminary tests (response stability and leakage current). The ionization chambers used for electron beam dosimetry were calibrated using four different methods. For the determination of absorbed dose, three methodologies recommended by the International Atomic Energy Agency were applied. Concordant results were obtained in almost all cases. Conclusion: The majority of the ionization chambers tested showed good results according to the established international limits. (author)

  19. Characterization of the PTW SourceCheck ionization chamber with the Valencia lodgment for (125)I seed verification.

    Science.gov (United States)

    Tornero-López, Ana M; Torres Del Río, Julia; Ruiz, Carmen; Perez-Calatayud, Jose; Guirado, Damián; Lallena, Antonio M

    2015-12-01

    In brachytherapy using (125)I seed implants, a verification of the air kerma strength of the sources used is required. Typically, between 40 and 100 seeds are implanted. Checking all of them is unaffordable, especially when seeds are disposed in sterile cartridges. Recently, a new procedure allowing the accomplishment of the international recommendations has been proposed for the seedSelectron system of Elekta Brachytherapy. In this procedure, the SourceCheck ionization chamber is used with a special lodgment (Valencia lodgment) that allows to measure up to 10 seeds simultaneously. In this work we analyze this procedure, showing the feasibility of the approximations required for its application, as well as the effect of the additional dependence with the air density that shows the chamber model used. Uncertainty calculations and the verification of the approximation needed to obtain a calibration factor for the Valencia lodgment are carried out. The results of the present work show that the chamber dependence with the air density is the same whether the Valencia lodgment is used or not. On the contrary, the chamber response profile is influenced by the presence of the lodgment. The determination of this profile requires various measurements due to the nonnegligible variability found between different experiments. If it is considered, the uncertainty in the determination of the air-kerma strength increases from 0.5% to 1%. Otherwise, a systematic additional uncertainty of 1% would occur. This could be relevant for the comparison between user and manufacturer measurements that is mandatory in the case studied here.

  20. 圆柱形电离室的能响补偿%Energy Compensation of Cylindrical Ionization Chamber

    Institute of Scientific and Technical Information of China (English)

    陈法国; 靳根; 刘倍; 徐园

    2012-01-01

    电离室由于其具有结构简单、使用方便的特点,目前仍被广泛应用于辐射监测领域.用于X、γ射线测量时,必须研究电离室的能量响应,并通过能响补偿使其灵敏度在一定的误差范围内是与入射X、γ射线的能量无关的常数.利用蒙特卡罗方法,模拟计算了圆柱形电离室对X、γ射线的灵敏度和能量响应;并根据计算结果的规律,对圆柱形电离室的能量响应进行了补偿,给出了补偿参数的最优范围.%Ionization chamber is still being widely used in radiation monitoring because of its simple structure and convenience. Used in X or gamma ray monitoring, the energy response of the chamber needs intense investigation and proper compensation filters must be designed in order to achieve a constant sensitivity which is independent of the energy of the incident X or gamma ray among a specified error range. The Monte - Carlo method is used to calculate the sensitivity and energy response characteristics of cylindrical ionization chamber to X or gamma ray. According to the results of simulation, the energy compensation of chamber is studied and the optimized compensation parameters are given.

  1. Resistive-plate-chamber background particles simulation studies for the endcap region of a compact muon solenoid/large hadron collider using the geometry and tracking code

    National Research Council Canada - National Science Library

    Jamil, M; Rhee, J T

    2005-01-01

    We present a method to simulate the double-gap resistive plate chambers (RPC) background particles for the endcap region of a compact muon solenoid/large hadron collider using the geometry and tracking (GEANT) code...

  2. A novel convolution-based approach to address ionization chamber volume averaging effect in model-based treatment planning systems

    Science.gov (United States)

    Barraclough, Brendan; Li, Jonathan G.; Lebron, Sharon; Fan, Qiyong; Liu, Chihray; Yan, Guanghua

    2015-08-01

    The ionization chamber volume averaging effect is a well-known issue without an elegant solution. The purpose of this study is to propose a novel convolution-based approach to address the volume averaging effect in model-based treatment planning systems (TPSs). Ionization chamber-measured beam profiles can be regarded as the convolution between the detector response function and the implicit real profiles. Existing approaches address the issue by trying to remove the volume averaging effect from the measurement. In contrast, our proposed method imports the measured profiles directly into the TPS and addresses the problem by reoptimizing pertinent parameters of the TPS beam model. In the iterative beam modeling process, the TPS-calculated beam profiles are convolved with the same detector response function. Beam model parameters responsible for the penumbra are optimized to drive the convolved profiles to match the measured profiles. Since the convolved and the measured profiles are subject to identical volume averaging effect, the calculated profiles match the real profiles when the optimization converges. The method was applied to reoptimize a CC13 beam model commissioned with profiles measured with a standard ionization chamber (Scanditronix Wellhofer, Bartlett, TN). The reoptimized beam model was validated by comparing the TPS-calculated profiles with diode-measured profiles. Its performance in intensity-modulated radiation therapy (IMRT) quality assurance (QA) for ten head-and-neck patients was compared with the CC13 beam model and a clinical beam model (manually optimized, clinically proven) using standard Gamma comparisons. The beam profiles calculated with the reoptimized beam model showed excellent agreement with diode measurement at all measured geometries. Performance of the reoptimized beam model was comparable with that of the clinical beam model in IMRT QA. The average passing rates using the reoptimized beam model increased substantially from 92.1% to

  3. Calibration of ionization chambers in IAEA water phantom; Kalibrering av ionekamre i IAEA-vannfantom

    Energy Technology Data Exchange (ETDEWEB)

    Bjerke, H.; Mikkelborg, O.

    1995-11-01

    The calibration in a water phantom is realised at the Secondary Standard Dosimetry Laboratory in Norway. The method is valid for chambers used in high energy radiation therapy. The method, setup and corrections in the calibration are described. The absorbed dose to air calibration factor, N{sub D}, will have an uncertainty of {approx}0.8% (k=1). 15 refs., 7 figs., 5 tabs.

  4. Comparison of the half-value layer: ionization chambers vs solid-state meters; Comparacao entre medidas de camada semirredutora: camara de ionizacao vs medidores de estado solido

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, L.C.S.; Navarro, V.C.C.; Navarro, M.V.T.; Macedo, E.M., E-mail: larapereira@ifba.edu.br [Instituto Federal da Bahia (LABPROSAUD/IFBA), Salvador, BA (Brazil). Laboratorio de Produtos para a Saude

    2015-07-01

    Generally, the half value layer (HVL) is determined by using ionization chambers and aluminum filters. However, some solid-state dosimeters allow simultaneous measurements of X-ray's parameters, among which the HVL. The main objective of this study was to compare the HVL's values indicated by four different solid-state dosimeters, whose values were measured by ionization chambers. The maximum difference found between the two methods was 11.42%, one the solid-state dosimeters, showing that the use these instruments to determine CSR in industrial X-ray should be subject to a more thorough evaluation. (author)

  5. Dosimetry in VMAT for prostate using ionization chambers of different volumes; Verificacao dosimetrica em VMAT para prostata com camaras de ionizacao de volumes diferentes

    Energy Technology Data Exchange (ETDEWEB)

    Groppo, Daniela P.; Anderson, Ernani; Pavan, Guilherme A., E-mail: danielagroppo@grupocoi.com, E-mail: ernanianderson@grupocoi.com [Clinicas Oncologicas Integradas (Grupo COI), Rio de Janeiro, RJ (Brazil); Caldas, Linda V.E., E-mail: lcaldas@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2016-07-01

    The volumetric modulated arc therapy is one of the most modern radiotherapy techniques. The advents of this modality in the dose delivery can also contribute to errors during the execution of the treatment, therefore various types of quality control are carried out. The individual assessment of dose delivered to the patient is also an important quality control test and required by the current regulations. The objective of this study was to evaluate the use of different volume ionization chambers for dosimetry of VMAT treatments for prostate cancer. Three ionization chambers were evaluated and all of them showed satisfactory results. (author)

  6. The laser desorption/laser ionization mass spectra of some methylated xanthines and the laser desorption of caffeine and theophylline from thin layer chromatography plates

    Science.gov (United States)

    Rogers, Kevin; Milnes, John; Gormally, John

    1993-02-01

    Laser desorption/laser ionization time-of-flight mass spectra of caffeine, theophylline, theobromine and xanthine are reported. These mass spectra are compared with published spectra obtained using electron impact ionization. Mass spectra of caffeine and theophylline obtained by IR laser desorption from thin layer chromatography plates are also described. The laser desorption of materials from thin layer chromatography plates is discussed.

  7. Maximum Alpha to Minimum Fission Pulse Amplitude for a Parallel-Plate and Hemispherical Cf-252 Ion-Chamber Instrumented Neutron Source

    Energy Technology Data Exchange (ETDEWEB)

    Oberer, R.B.

    2000-12-07

    In an instrumented Cf-252 neutron source, it is desirable to distinguish fission events which produce neutrons from alpha decay events. A comparison of the maximum amplitude of a pulse from an alpha decay with the minimum amplitude of a fission pulse shows that the hemispherical configuration of the ion chamber is superior to the parallel-plate ion chamber.

  8. Multi-concentric-ring open-air ionization chamber for high-intensity X-ray beams

    Science.gov (United States)

    Nariyama, Nobuteru

    2014-11-01

    An ionization chamber with four concentric ring electrodes was used to measure doses of white, 10, 15 and 20 keV synchrotron X-ray beams. The ring-shaped electrodes, which had diameters less than 11.8 mm, collected charges independently only around the beam, excluding strong in-beam charges when the beams passed through a small hole in the electrode centers. As a result, under low saturation voltages, the measured dose rates were confirmed to correlate with the beam intensity when conversion factors calculated with a Monte Carlo code were employed. The influence of the assumed beam sizes and incident positions on the current was almost negligible, with the exception of the incident position dependence at 10 keV.

  9. Study of the performance of the ATLAS monitored drift tube chambers under the influence of heavily ionizing $\\alpha$-particles

    CERN Document Server

    Sampsonidis, Dimitrios; Liolios, Anastasios; Manolopoulou, Metaxia; Petridou, C

    2004-01-01

    The MDT chambers of the ATLAS Muon Spectrometer will operate in a heavy LHC background environment mainly from photons and neutrons. The ionization produced by neutron recoils is much higher than the one from photons or muons and can be simulated by the use of alpha particles. A systematic study of the behavior of the ATLAS Monitored Drift Tubes (MDTs) under controlled irradiation has been performed. The presence of alpha particles results in the reduction of the gas gain due to space charge effects. The gas gain reduction has been studied in a single tube set up using a well controlled radium (/sup 226/Ra) source in order to enrich the tube gas (Ar/CO/sub 2/) with the alpha emitter /sup 220/Rn and irradiate the tubes internally. The results are confronted with Garfield simulations.

  10. Development for PRESPEC: New front end electronic for multi sampling ionization chambers of the GSI-fragment separator

    Energy Technology Data Exchange (ETDEWEB)

    Pietri, Stephane; Gerl, Juergen; Kurz, Nik; Nociforo, Chiara; Schaffner, Henning; Simon, Haik [GSI, Planckstrasse 1, 64291 Darmstadt (Germany)

    2009-07-01

    To study detailed structure effects during in-beam gamma spectroscopy experiments at the GSI fragment separator high particles rates are needed at the final focal plane. The use of new position detector (TPC) having higher rate capability than the previous Multi-Wire Proportional Counter put the ionization chambers (MUSICs) used for the {delta}-E measurement as the limiting factor. The current electronics used for those detector does not allow to sustain rates of up to 100 kHz that the coming experimental program will request. Indeed at those rates the analog electronic is not able to disentangle pile-up events and thus give a wrong Z identification for the incoming nucleus. The ongoing work on new digital electronic and on signal characterization to allow higher rates capability of those detectors is presented.

  11. Simulation of the Mg(Ar) ionization chamber currents by different Monte Carlo codes in benchmark gamma fields

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yi-Chun [Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Taiwan (China); Liu, Yuan-Hao, E-mail: yhl.taiwan@gmail.com [Boron Neutron Capture Therapy Center, Nuclear Science and Technology Development Center, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu City 30013, Taiwan (China); Nievaart, Sander [Institute for Energy, Joint Research Centre, European Commission, Petten (Netherlands); Chen, Yen-Fu [Department of Engineering and System Science, National Tsing Hua University, Taiwan (China); Wu, Shu-Wei; Chou, Wen-Tsae [Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Taiwan (China); Jiang, Shiang-Huei [Institute of Nuclear Engineering and Science, National Tsing Hua University, Taiwan (China)

    2011-10-01

    High energy photon (over 10 MeV) and neutron beams adopted in radiobiology and radiotherapy always produce mixed neutron/gamma-ray fields. The Mg(Ar) ionization chambers are commonly applied to determine the gamma-ray dose because of its neutron insensitive characteristic. Nowadays, many perturbation corrections for accurate dose estimation and lots of treatment planning systems are based on Monte Carlo technique. The Monte Carlo codes EGSnrc, FLUKA, GEANT4, MCNP5, and MCNPX were used to evaluate energy dependent response functions of the Exradin M2 Mg(Ar) ionization chamber to a parallel photon beam with mono-energies from 20 keV to 20 MeV. For the sake of validation, measurements were carefully performed in well-defined (a) primary M-100 X-ray calibration field, (b) primary {sup 60}Co calibration beam, (c) 6-MV, and (d) 10-MV therapeutic beams in hospital. At energy region below 100 keV, MCNP5 and MCNPX both had lower responses than other codes. For energies above 1 MeV, the MCNP ITS-mode greatly resembled other three codes and the differences were within 5%. Comparing to the measured currents, MCNP5 and MCNPX using ITS-mode had perfect agreement with the {sup 60}Co, and 10-MV beams. But at X-ray energy region, the derivations reached 17%. This work shows us a better insight into the performance of different Monte Carlo codes in photon-electron transport calculation. Regarding the application of the mixed field dosimetry like BNCT, MCNP with ITS-mode is recognized as the most suitable tool by this work.

  12. Quality control and database on resistive plate chambers for the BESⅢ experiment

    Institute of Scientific and Technical Information of China (English)

    HAN Ji-Feng; MA Lie-Hua; ZHANG Jia-Wen; CHEN Jin; ZHAO Jian-Bing; YAO Ning; LIU Qian; XIE Yu-Guang; ZHANG Qing-Min; QIAN Sen

    2008-01-01

    The chamber production and installation of the BESⅢ MUON identifier system have been finished.The cosmic ray test result after installation shows that the average efficiency is bigger than 95% and can meet the requirement of the design report. A database including all the chamber parameters and performance data has been constructed and is accessible online. The quality control procedures during the production and the database are described.

  13. Wall Attenuation and Scatter Characteristics of Ionization Chambers at Armed Forces Radiobiology Research Institute

    Science.gov (United States)

    1986-12-01

    0.5 0.10 TE 155 Exradin Cylindrical 0.05 0.10 TE, tissue-equivalent plastic type A-150; GR, graphite; MG, magnesium For each wall thickness, the...11 to be used in AAPM protocol (reference 16) tExtrapolated from Table III in reference 16 DISCUSSION The results shown in Table 2 and Appendix B...Physicists in Medicine ( AAPM ) Task Group 21 protocol for High Energy Photon and Electron Dosimetry (16). In this protocol, the chamber wall correction

  14. Preliminary results of Resistive Plate Chambers operated with eco-friendly gas mixtures for application in the CMS experiment

    CERN Document Server

    Abbrescia, M

    2016-01-01

    The operations of Resistive Plate Chambers in LHC experiments require Fluorine based (F-based) gases for optimal performance. Recent European regulations demand the use of environmentally unfriendly F-based gases to be limited or banned. In view of the CMS experiment upgrade, several tests are ongoing to measure the performance of the detector with these new ecological gas mixtures, in terms of efficiency, streamer probability, induced charge and time resolution. Prototype chambers with readout pads and with the standard CMS electronic setup are under test. In this paper preliminary results on performance of RPCs operated with a potential eco-friendly gas candidate 1,3,3,3-Tetrafluoropropene, commercially known as HFO-1234ze, with CO2 and CF3I based gas mixtures are presented and discussed for the possible application in the CMS experiment.

  15. Preliminary results of Resistive Plate Chambers operated with eco-friendly gas mixtures for application in the CMS experiment

    CERN Document Server

    Abbrescia, Marcello; Benussi, Luigi; Bianco, Stefano; Cauwenbergh, Simon Marc D; Ferrini, Mauro; Muhammad, Saleh; Passamontic, L; Pierluigi, Daniele; Piccolo, Davide; Primavera, Federica; Russo, Alessandro; Savianoc, G; Tytgat, Michael

    2016-01-01

    The operations of Resistive Plate Chambers in LHC experiments require F-based gases for optimal performance. Recent regulations demand the use of environmentally unfriendly F-based gases to be limited or banned. In view of the CMS experiment upgrade several tests are ongoing to measure the performance of the detector in terms of efficiency, streamer probability, induced charge and time resolution. Prototype chambers with readout pads and with the standard cms electronic setup are under test. In this talk preliminary results on performance of RPCs operated with a potential eco-friendly gas candidate 1,3,3,3-Tetrafluoropropene, commercially known as HFO-1234ze and with CO2 based gas mixtures are presented and discussed for the possible application in the CMS experiment.

  16. Scattering study at free air ionization chamber diaphragm; Estudo do espalhamento no diafragma da camara de ionizacao de ar livre

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Alexandre Lo Bianco dos

    2011-07-01

    The maim of this work consisted in the assessment of the correction factor for air kerma, due to scattered radiation in the diaphragm of the free-air ionization chamber model 481. LNMRl measurements were made to acquire x-ray spectra corresponding to the Qualities RQR-M, described in IEC 61627 standards (2005). These spectra were used as input data in the MC simulations. The operational range of energy spectra provide up to 35 keV. This energy range is typically used in diagnostic radiology, although there is not primary standard for air kerma. The determination of this factor is a fundamental process in the primary standardization of the air kerma. These factors were obtained by computer simulation using the Penelope code. The results are k{sub RQR-M1}=0,9946, k{sub RQR} {sub -M2}=0,9932, k{sub RQR-M3}=0,9978 and k{sub RQR-M4}=0,9885; with uncertainties of 0,007 and coverage factor equal to 2. lt can be concluded that, with respect to the diaphragm, the chamber can be used in the primary standard of air kerma. (author)

  17. Characterization and performances of a monitoring ionization chamber dedicated to IBA-universal irradiation head for Pencil Beam Scanning

    Energy Technology Data Exchange (ETDEWEB)

    Courtois, C. [LPC (IN2P3-ENSICAEN-UNICAEN), 6 Boulevard Maréchal Juin, 14050 Caen (France); Boissonnat, G., E-mail: boissonnat@lpccaen.in2p3.fr [LPC (IN2P3-ENSICAEN-UNICAEN), 6 Boulevard Maréchal Juin, 14050 Caen (France); Brusasco, C. [IBA, 3 Chemin du Cyclotron, 31348 Louvain-la-Neuve (Belgium); Colin, J.; Cussol, D.; Fontbonne, J.M. [LPC (IN2P3-ENSICAEN-UNICAEN), 6 Boulevard Maréchal Juin, 14050 Caen (France); Marchand, B.; Mertens, T.; Neuter, S. de [IBA, 3 Chemin du Cyclotron, 31348 Louvain-la-Neuve (Belgium); Peronnel, J. [LPC (IN2P3-ENSICAEN-UNICAEN), 6 Boulevard Maréchal Juin, 14050 Caen (France)

    2014-02-01

    Every radiotherapy center has to be equipped with real-time beam monitoring devices. In 2008, we developed an ionization chamber in collaboration with the IBA (Ion Beam Applications) company. This monitoring device called IC2/3 was developed to be used in IBA universal irradiation head for Pencil Beam Scanning (PBS). Here we present the characterization of the IC2/3 monitor in the energy and flux ranges used in protontherapy. The equipment has been tested with an IBA cyclotron able to deliver proton beams from 70 to 230 MeV. This beam monitoring device has been validated and is now installed at the Westdeutsches Protonentherapiezentrum Essen protontherapy center (WPE, Germany). The results obtained in both terms of spatial resolution and dose measurements are at least equal to the initial specifications needed for PBS purposes. The detector measures the dose with a relative uncertainty lower than 1% in the range from 0.5 Gy/min to 8 Gy/min while the spatial resolution is better than 250μm. The technology has been patented and five IC2/3 chambers were delivered to IBA. Nowadays, IBA produces the IC2/3 beam monitoring device as a part of its Proteus 235 product.

  18. A compact multi-plate fission chamber for the simultaneous measurement of 233U capture and fission cross-sections

    Directory of Open Access Journals (Sweden)

    Bacak M.

    2017-01-01

    Full Text Available 233U plays the essential role of fissile nucleus in the Th-U fuel cycle. A particularity of 233U is its small neutron capture cross-section which is about one order of magnitude lower than the fission cross-section on average. Therefore, the accuracy in the measurement of the 233U capture cross-section essentially relies on efficient capture-fission discrimination thus a combined setup of fission and γ-detectors is needed. At CERN n_TOF the Total Absorption Calorimeter (TAC coupled with compact fission detectors is used. Previously used MicroMegas (MGAS detectors showed significant γ-background issues above 100 eV coming from the copper mesh. A new measurement campaign of the 233U capture cross-section and alpha ratio is planned at the CERN n_TOF facility. For this measurement, a novel cylindrical multi ionization cell chamber was developed in order to provide a compact solution for 14 active targets read out by 8 anodes. Due to the high specific activity of 233U fast timing properties are required and achieved with the use of customized electronics and the very fast ionizing gas CF4 together with a high electric field strength. This paper describes the new fission chamber and the results of the first tests with neutrons at GELINA proving that it is suitable for the 233U measurement.

  19. A single Time-of-Flight tray based on multigap resistive plate chambers for the STAR experiment at RHIC

    Science.gov (United States)

    Bonner, B.; Chen, H.; Eppley, G.; Geurts, F.; Lamas-Valverde, J.; Li, Ch.; Llope, W. J.; Nussbaum, T.; Platner, E.; Roberts, J.

    2003-08-01

    The STAR experiment at RHIC plans to implement a 60 m2 Time-of-Flight (TOF) system. The Multigap Resistive Plate Chamber (MRPC) is a suitable candidate for the STAR TOF system due to its time resolution of order of 60 ps with efficiencies in excess of 97%. We obtained this result with modules composed of 6 gas gaps of 220 μm and pad area of 20 cm2. In this paper, we report on the performance of this MRPC module and present the current status of the construction and installation into STAR of a prototype tray.

  20. Performance testing of a long-strip two-end readout multi-gap resistive plate chamber

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-Bin; WANG Yi; LUO Ming; LI Yuan-Jing; CHENG Jian-Ping

    2009-01-01

    Multi-gap Resistive Plate Chamber (MRPC) is a new generation of gas detector with good tim-ing and spacial resolution, whose technique is widely applied in some recent high energy (nuclear) physics experiments. In this letter, we report a long-strip two-end readout MRPC and its test beam performance. The measurements show that the long-strip performs a transmission line characteristic and the impedance is independent of the length of strip. The MRPC module we developed is presented to gain a timing resolution of~80 ps and a spacial resolution of ~6.4 mm. The possible application of the MRPC is also discussed.

  1. Electron beam quality kQ,Q0 factors for various ionization chambers: a Monte Carlo investigation with penelope

    Science.gov (United States)

    Erazo, F.; Brualla, L.; Lallena, A. M.

    2014-11-01

    In this work we calculate the beam quality correction factor {{k}\\text{Q,{{\\text{Q}}0}}} for various plane-parallel ionization chambers. A set of Monte Carlo calculations using the code penelope/penEasy have been carried out to calculate the overall correction factor fc,Q for eight electron beams corresponding to a Varian Clinac 2100 C/D, with nominal energies ranging between 6 MeV and 22 MeV, for a 60Co beam, that has been used as the reference quality Q0 and also for eight monoenergetic electron beams reproducing the quality index R50 of the Clinac beams. Two field sizes, 10 × 10 cm2 and 20 × 20 cm2 have been considered. The {{k}\\text{Q,{{\\text{Q}}0}}} factors have been calculated as the ratio between fc,Q and {{f}\\text{c,{{\\text{Q}}0}}} . Values for the Exradin A10, A11, A11TW, P11, P11TW, T11 and T11TW ionization chambers, manufactured by Standard Imaging, as well as for the NACP-02 have been obtained. The results found with the Clinac beams for the two field sizes analyzed show differences below 0.6%, even in the case of the higher energy electron beams. The {{k}\\text{Q,{{\\text{Q}}0}}} values obtained with the Clinac beams are 1% larger than those found with the monoenergetic beams for the higher energies, above 12 MeV. This difference can be ascribed to secondary photons produced in the linac head and the air path towards the phantom. Contrary to what was quoted in a previous work (Sempau et al 2004 Phys. Med. Biol. 49 4427-44), the beam quality correction factors obtained with the complete Clinac geometries and with the monoenergetic beams differ significantly for energies above 12 MeV. Material differences existing between chambers that have the same geometry produce non-negligible modifications in the value of these correction factors.

  2. Use of a MicroStrip Gas Chamber conductive capillary plate for time-resolved X-ray area detection

    CERN Document Server

    Ochi, A; Nishi, Y; Nishi, Y; Nagayoshi, T; Ohashi, Y; Uekusa, H; Toyokawa, H

    2002-01-01

    The stable operation of MicroStrip Gas Chamber (MSGC) was successfully performed using glass capillary plate as an intermediate gas multiplier. Detection area of 95 mm sup 2 was available and fine position resolution of 90 mu m using digital readout was attained. A charge-up problem of capillary plate under intense radiation source was perfectly removed by surface conductivity inside of capillaries. The quantitative measurements using MSGC is now available in X-ray imaging. This paper also presents novel applications of X-ray diffraction studies and their preliminary results using an MSGC. Rapid measurements for X-ray crystallography of the order of a few tens of seconds were attained successfully.

  3. Test of a four-gap resistive plate chamber with cosmic muons and high-rate gamma rays

    Energy Technology Data Exchange (ETDEWEB)

    Park, S.K.; Shin, S.S.; Hong, B.; Jhang, G.; Jeong, M.S.; Jo, M.; Cho, S.W.; Joo, E.; Kim, C.; Kim, H.C. [Department of Physics and Korea Detector Laboratory, Korea University, Seoul 136-701 (Korea, Republic of); Lee, K.S., E-mail: kslee0421@korea.ac.kr [Department of Physics and Korea Detector Laboratory, Korea University, Seoul 136-701 (Korea, Republic of); Lee, K.S.; Lee, S.; Lee, S.K.; Lim, J.K.; Moon, D.H.; Shim, H.H.; Sim, K.S. [Department of Physics and Korea Detector Laboratory, Korea University, Seoul 136-701 (Korea, Republic of)

    2012-07-11

    We report a new development of a phenolic four-gap resistive plate chamber (RPC) for use as a high-rate particle trigger in high-energy physics experiments. In the current study, a prototype RPC equipped with four 1-mm-thick gaps made from high-pressure-laminated (HPL) resistive plates has been designed and built. The current detector R and D aims to reduce the probability of radiation-induced degradation of the core detector components of the RPCs, the gas gaps, as well as to improve the detection rate capability. The detector characteristics of the four-gap RPC were obtained though a series of tests with cosmic muons and gamma rays and were compared with those of the typical 2-mm thick double-gap RPCs currently used in the CMS experiment at the LHC and in the PHENIX experiment at the RHIC.

  4. Fast-Neutron Spectrometry Using a 3He Ionization Chamber and Digital Pulse Shape Analysis

    Energy Technology Data Exchange (ETDEWEB)

    D. L. Chichester; J. T. Johnson; E. H. Seabury

    2010-05-01

    Digital pulse shape analysis (dPSA) has been used with a Cuttler-Shalev type 3He proportional counter to measure the fast neutron spectra of bare 252Cf and 241AmBe neutron sources. Measurements have also been made to determine the attenuated fast neutron spectra of 252Cf shielded by several materials including water, graphite, liquid nitrogen, magnesium, and tungsten. Rise-time dPSA has been employed using the common rise-time approach for analyzing n +3He ? 1H + 3H ionization events and a new approach has been developed to improve the fidelity of these measurements. Simulations have been performed for the different experimental arrangements and are compared, demonstrating general agreement between the dPSA processed fast neutron spectra and predictions.

  5. Technical Note : A direct ray-tracing method to compute integral depth dose in pencil beam proton radiography with a multilayer ionization chamber

    NARCIS (Netherlands)

    Farace, Paolo; Righetto, Roberto; Deffet, Sylvain; Meijers, Arturs; Vander Stappen, Francois

    2016-01-01

    Purpose: To introduce a fast ray-tracing algorithm in pencil proton radiography (PR) with a multilayer ionization chamber (MLIC) for in vivo range error mapping. Methods: Pencil beam PR was obtained by delivering spots uniformly positioned in a square (45x45 mm(2) field-of-view) of 9x9 spots capable

  6. Dosimetry for the MRI accelerator: the impact of a magnetic field on the response of a Farmer NE2571 ionization chamber.

    Science.gov (United States)

    Meijsing, I; Raaymakers, B W; Raaijmakers, A J E; Kok, J G M; Hogeweg, L; Liu, B; Lagendijk, J J W

    2009-05-21

    The UMC Utrecht is constructing a 1.5 T MRI scanner integrated with a linear accelerator (Lagendijk et al 2008 Radiother. Oncol. 86 25-9). The goal of this device is to facilitate soft-tissue contrast based image-guided radiotherapy, in order to escalate the dose to the tumour while sparing surrounding normal tissues. Dosimetry for the MRI accelerator has to be performed in the presence of a magnetic field. This paper investigates the feasibility of using a Farmer NE2571 ionization chamber for absolute dosimetry. The impact of the mcagnetic field on the response of this ionization chamber has been measured and simulated using GEANT4 Monte Carlo simulations. Two orientations of the ionization chamber with respect to the incident beam and the magnetic field which are feasible in the MRI accelerator configuration are taken into account. Measurements are performed using a laboratory magnet ranging from 0 to 1.2 T. In the simulations a range from 0 to 2 T is used. For both orientations, the measurements and simulations agreed within the uncertainty of the measurements and simulations. In conclusion, the response of the ionization chamber as a function of the magnetic field is understood and can be simulated using GEANT4 Monte Carlo simulations.

  7. Determination of absorbed dose to water in a clinical carbon ion beam by means of fluorescent nuclear track detectors, ionization chambers, and water calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Osinga-Blaettermann, Julia-Maria

    2016-12-20

    Until now, dosimetry of carbon ions with ionization chambers has not reached the same level of accuracy as of high-energy photons. This is mainly caused by the threefold higher uncertainty of the k{sub Q,Q{sub 0}}-factor of ionization chambers, which is derived by calculations due to a lack of experimental data. The current thesis comprises two major aims with respect to the dosimetry of carbon ion beams: first, the investigation of the potential of fluorescent nuclear track detectors for fluence-based dosimetry and second, the experimental determination of the k{sub Q,Q{sub 0}}-factor. The direct comparison of fluence- and ionization-based measurements has shown a significant discrepancy of 4.5 %, which re-opened the discussion on the accuracy of calculated k{sub Q,Q{sub 0}}-factors. Therefore, absorbed dose to water measurements by means of water calorimetry have been performed allowing for the direct calibration of ionization chambers and thus for the experimental determination of k{sub Q,Q{sub 0}}. For the first time it could be shown that the experimental determination of k{sub Q,Q{sub 0}} for carbon ion beams is achievable with a standard measurement uncertainty of 0.8 %. This corresponds to a threefold reduction of the uncertainty compared to calculated values and therefore enables to significantly decrease the overall uncertainty related to ionization-based dosimetry of clinical carbon ion beams.

  8. 核电站事故后监测电离室设计方法%Designing methods for nuclear power station accident condition ionization chamber

    Institute of Scientific and Technical Information of China (English)

    孙光智; 王益元; 李亚坚; 代传波; 粱云; 左亮周

    2011-01-01

    介绍了一种用于核电站事故后γ辐射剂量率监测的电离室设计所需的模拟计算方法;用MCNP程序模拟计算了射线在不同结构、不同工作气体的电离室中灵敏度的能量响应特性,为事故后监测电离室的设计提供了理论依据.%Simulation and calculation methods for designing of ionization chamber used in nuclear power station during accident conditions were introduced in this paper. Using MCNP program,we calculated energy response of this chamber with various structures and sensitive gas,supplied theoretic dependence for designing of ionization chamber used during accident conditions.

  9. Long Term Performance Studies of Large Oil-Free Bakelite Resistive Plate Chamber

    CERN Document Server

    Ganai, Rajesh; Shiroya, Mehul Kumar; Agarwal, Kshitij; Ahammed, Zubayer; Choudhury, Subikash; Chattopadhyay, Subhasis

    2016-01-01

    Several high energy physics and neutrino physics experiments worldwide require large-size RPCs to cover wide acceptances. The muon tracking systems in the Iron calorimeter (ICAL) in the INO experiment, India and the near detector in DUNE at Fermilab are two such examples. A (240 cm $\\times$ 120 cm $\\times$ 0.2 cm) bakelite RPC has been built and tested at Variable Energy Cyclotron Centre, Kolkata, using indigenous materials procured from the local market. No additional lubricant, like oil has been used on the electrode surfaces for smoothening. The chamber is in operation for $>$ 365 days. We have tested the chamber for its long term operation. The leakage current, bulk resistivity, efficiency, noise rate and time resolution of the chamber have been found to be quite stable during the testing peroid. It showed an efficiency $>$ 95$\\%$ with an average time resolution of $\\sim$0.83 ns at the point of measurement at 9000 V throughout the testing period. Details of the long term performance of the chamber have be...

  10. Expected signal for the TBID and the ionization chambers downstream of the CNGS target station

    CERN Document Server

    Sarchiapone, L; Gschwendtner, E; Lorenzo-Sentis, M

    2006-01-01

    Downstream of the carbon graphite target of the CNGS (CERN Neutrinos to Gran Sasso) facility at CERN a secondary emission monitor called TBID (Target Beam Instrumentation Downstream) is installed to measure the multiplicities and the left/right as well as up/down asymmetries of secondary particles from the target. Calculations show that the titanium windows used to close off the TBID vacuum tank might not withstand the highest beam intensities with small spot sizes expected at CNGS, in case the proton beam accidentally misses the 4-5 mm diameter target rods. Therefore it has been suggested to place two ionisation chambers as a backup for the TBID, located left and right of the TBID monitor. Monte Carlo simulations with the particle transport code FLUKA were performed firstly to obtain the fluence of charged particles in the region of interest and secondly to estimate the induced radioactivity (background signal) in this area. This allows to assess the actual signal/noise situation and thus to determine the op...

  11. Laser Induced Fluorescence Spectroscopy of Neutral and Ionized Polycyclic Aromatic Hydrocarbons in the Cosmic Simulation Chamber

    Science.gov (United States)

    Bejaoui, Salma; Salama, Farid; Contreras, Cesar; Sciamma O'Brien, Ella; Foing, Bernard; Pascale, Ehrenfreund

    2015-01-01

    Polycyclic aromatic hydrocarbon (PAH) molecules are considered the best carriers to account for the ubiquitous infrared emission bands. PAHs have also been proposed as candidates to explain the diffuse interstellar bands (DIBs), a series of absorption features seen on the interstellar extinction curve and are plausible carriers for the extended red emission (ERE), a photoluminescent process associated with a wide variety of interstellar environments. Extensive efforts have been devoted over the past two decades to characterize the physical and chemical properties of PAH molecules and ions in space. Absorption spectra of PAH molecules and ions trapped in solid matrices have been compared to the DIBs. Absorption spectra of several cold, isolated gas-phase PAHs have also been measured under experimental conditions that mimic the interstellar conditions. The purpose of this study is to provide a new dimension to the existing spectroscopic database of neutral and single ionized PAHs that is largely based on absorption spectra by adding emission spectroscopy data. The measurements are based on the laser induced fluorescence (LIF) technique and are performed with the Pulsed Discharge Nozzle (PDN) of the COSmIC laboratory facility at NASA Ames laboratory. The PDN generates a plasma in a free supersonic jet expansion to simulate the physical and the chemical conditions in interstellar environments. We focus, here, on the fluorescence spectra of large neutral PAHs and their cations where there is a lack of fluorescence spectroscopy data. The astronomical implications of the data (e.g., ERE) are examined.

  12. Comparison of two dose-area-product ionization chambers with different conductive surface coating for over-table and under-table tube configurations

    Energy Technology Data Exchange (ETDEWEB)

    Bednarek, D.R.; Rudin, S.

    2000-03-01

    A custom-built graphite-coated transmission ionization chamber is compared to the VacuDAP 2001 (VacuTec, Dresden, Germany), which has transparent conductive electrodes. A study was made of the dependence of response on x-ray tube potential for both types of chamber under identical conditions of exposure using over-table and under-table x-ray tubes. Since the calibration factor is the dose-area product of the radiation incident on the patient per chamber reading, it depends on the intrinsic response of the chamber as well as the effect of material in the beam between the x-ray tube and patient. Differences of about 20% were measured between the intrinsic and the over-table calibration factors and between the over-table and the under-table calibration factors for both chambers. The VacuDAP display is specifically calibrated for the over-table condition and would overstate the actual DAP in the under-table case. The intrinsic response of the graphite chamber is nearly independent of tube potential. Although the variation of response with tube potential of the graphite chamber is increased when it is used as an over-table and an under-table patient monitor, it shows less overall variation of response than the VacuDAP. The average deviation of each range of 40 to 140 kVp for both chambers.

  13. Experimental analysis of general ion recombination in a liquid-filled ionization chamber in high-energy photon beams

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Eunah; Seuntjens, Jan [Medical Physics Unit, McGill University, Montreal General Hospital (L5-113), 1650 Cedar Avenue, Montreal, Quebec H3G 1A4 (Canada); Davis, Stephen [Department of Medical Physics, McGill University Health Centre, Montreal General Hospital (L5-112), 1650 Cedar Avenue, Montreal, Quebec H3G 1A4 (Canada)

    2013-06-15

    Purpose: To study experimentally the general ion recombination effect in a liquid-filled ionization chamber (LIC) in high-energy photon beams. Methods: The general ion recombination effect on the response of a micro liquid ion chamber (microLion) was investigated with a 6 MV photon beam in normal and SRS modes produced from a Varian{sup Registered-Sign} Novalis Tx{sup TM} linear accelerator. Dose rates of the linear accelerator were set to 100, 400, and 1000 MU/min, which correspond to pulse repetition frequencies of 60, 240, and 600 Hz, respectively. Polarization voltages applied to the microLion were +800 and +400 V. The relative collection efficiency of the microLion response as a function of dose per pulse was experimentally measured with changing polarization voltage and pulse repetition frequencies and was compared with the the