Download or read book Dose Measurements of Bremsstrahlung produced Neutrons from Thick Targets at the Advanced Photon Source written by and published by . This book was released on 1998 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bremsstrahlung is produced in the Advanced Photon Source storage ring when the positron beam interacts with the storage-ring components or with the residual gas molecules in the storage-ring vacuum. This bremsstrahlung has an energy range of zero to 7.0 GeV, which is the maximum energy of the positron beam. Bremsstrahlung photons of sufficient high energy can interact with beamline components such as beam stops and collimators, generating neutrons of varying energies. This paper presents the results of simultaneous measurements, conducted at the Advanced Photon Source, of bremsstrahlung and the corresponding photoneutron production from thick targets of iron, copper, tungsten and lead, which allow one to correlate photoneutron dose rates from these metals as a function of bremsstrahlung power. The average photoneutron dose equivalent rates, normalized to the bremsstrahlung power, are measured as 2.7 " 0.5 rem/h/W for iron, 3.2 " 0.5 rem/h/W for copper, 3.9 " 0.5 rem/h/W for tungsten, and 4.6 " 0.8 rem/h/W for lead targets. These are measured at 80 cm lateral from the center of the targets, perpendicular to the photon beam direction.
Download or read book Dose Measurements of Bremsstrahlung Produced Neutrons at the Advanced Photon Source written by and published by . This book was released on 1998 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bremsstrahlung is generated in the storage rings of the synchrotron radiation facilities by the radiative interaction of the circulating particle beam with both the residual gas molecules and storage ring components. These bremsstrahlung photons, having an energy range of zero to the maximum energy of the particle beam, interact with beamline components like beam stops and collimators generating photoneutrons of varying energies. There are three main processes by which photoneutrons may be produced by the high energy bremsstrahlung photons: giant nuclear dipole resonance and decay (10 MeV E{sub {gamma}} 30 MeV), quasi-deuteron production and decay (50 MeV
Download or read book Dose Calculations Using MARS for Bremsstrahlung Beam Stops and Collimators in APS Beamline Stations written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Monte Carlo radiation transport code MARS is used to model the generation of gas bremsstrahlung (GB) radiation from 7-GeV electrons which scatter from residual gas atoms in undulator straight sections within the Advanced Photon Source (APS) storage ring. Additionally, MARS is employed to model the interactions of the GB radiation with components along the x-ray beamlines and then determine the expected radiation dose-rates that result. In this manner, MARS can be used to assess the adequacy of existing shielding or the specifications for new shielding when required. The GB radiation generated in the 'thin-target' of an ID straight section will consist only of photons in a 1/E-distribution up to the full energy of the stored electron beam. Using this analytical model, the predicted GB power for a typical APS 15.38-m insertion device (ID) straight section is 4.59 x 10−7 W/nTorr/mA, assuming a background gas composed of air (Z{sub eff} = 7.31) at room temperature (293K). The total GB power provides a useful benchmark for comparisons between analytical and numerical approaches. We find good agreement between MARS and analytical estimates for total GB power. The extended straight section 'target' creates a radial profile of GB, which is highly peaked centered on the electron beam. The GB distribution reflects the size of the electron beam that creates the radiation. Optimizing the performance of MARS in terms of CPU time per incident trajectory requires the use of a relatively short, high-density gas target (air); in this report, the target density is [rho]L = 2.89 x 10−2 g/cm2 over a length of 24 cm. MARS results are compared with the contact dose levels reported in TB-20, which used EGS4 for radiation transport simulations. Maximum dose-rates in 1 cc of tissue phantom form the initial basis for comparison. MARS and EGS4 results are approximately the same for maximum 1-cc dose-rates and attenuation in the photon-dominated regions; for thicker targets, however, the dose-rate no longer depends only on photon attenuation, as photoneutrons (PNs) begin to dominate. The GB radiation-induced photoneutron measurements from four different metals (Fe, Cu, W, and Pb) are compared with MARS predictions. The simulated dose-rates for beamline 6-ID are approximately 3-5 times larger than the measured values, whereas those for beamline 11-ID are much closer. Given the uncertainty in local values of pressure and Z, the degree of agreement between MARS and the PN measurements is good. MARS simulations of GB-induced radiation in and around the FOE show the importance of using actual pressure and gas composition (Z{sub eff}) to obtain accurate PN dose. For a beam current of 300 mA, extrapolating pressure data measured in previously published studies predicts an average background gas pressure of 27 nTorr. An average atomic number of Z{sub eff} = 4.0 is obtained from the same studies. In addition, models of copper masks presently in use at the APS are included. Simulations show that inclusion of exit masks make significant differences in both the radiation spatial distribution within the FOE, as well as the peak intensity. Two studies have been conducted with MARS to assess shielding requirements. First, dose levels in contact with the outside wall of the FOE are examined when GB radiation strikes Pb or W beam stops of varying transverse size within the FOE. Four separate phantom regions are utilized to measure the dose, two at beam elevation and two at the horizontal beam position. The first two phantoms are used for scoring FOE dose along the outside and back walls, horizontally; the second two collect dose on the roof and vertically on the back wall. In all cases, the beam stop depth is maintained at 30 cm. Inclusion of front end (FE) exit masks typically cause a 1-2 order-of-magnitude increase in the dose-rates relative to the case with no masks. Masks place secondary bremsstrahlung sources inside the FOE, and therefore they must be shielded appropriately. The MARS model does not fully account for all shielding present in the hutches; localized shielding is employed in individual hutches. Typically, a collimator, placed downstream of the FE exit masks, mitigates the possible increase in dose. Regarding beam stop transverse size, a modest reduction in dose on the back wall is noted as the stop dimension (square cross section) is increased from 12 cm to 24 cm. In the second study, the thickness of Pb required to shield against the GB extremal ray is determined. In this study, we are interested in finding the thickness of material necessary to add at the edge of a stop to adequately block GB radiation; therefore, we look at the case of no masks in order to have a well-defined GB beam edge. Simulations show the separation between the extremal ray and the edge of the shielding should be 2R{sub m}, where R{sub m} is the Moliere radius.
Download or read book The Photoneutron Yield Predictions by PICA and Comparison with the Measurements written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The photoneutron yields at higher photon energies have become very important since the advent of high energy electron accelerators. Bremsstrahlung is produced when the particle beam interacts with the storage-ring components or residual-gas molecules in the storage-ring vacuum. Bremsstrahlung thus produced interacts with the high-Z materials in the beamline like the beam dumps and collimators to produce photoneutrons. There are three modes of neutron production by bremsstrahlung. At low energies ([>=]525 MeV), photons are absorbed by the dipole interaction and the compound nucleus thus formed decays emitting protons and neutrons and other heavier particles. At higher energies ([>=]25 MeV), photon interacts with the nucleus through absorption on a quasi-deuteron, which subsequently decays producing a neutron and proton pair which can interact with the rest of the nucleus. At still higher energies the photopion production becomes possible and competes with the quasi-deuteron process. In this paper we have calculated the photoneutron yield from a thick copper target using the photonuclear interaction code PICA. Using this as the neutron source, we have calculated the dose rates through heavy concrete and compared it with the measurements made at the Advanced Photon Source at Argonne National Lab.
Download or read book Proceedings of the Specialists Meeting on Shielding Aspects of Accelerators Targets and Irradiation Facilities written by and published by . This book was released on 1999 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Accelerator Radiation Protection written by G. R. Stevenson and published by . This book was released on 2001 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurements of Neutron Emission Spectra from 14 MeV Neutrons on Thick Targets written by and published by . This book was released on 1974 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1973 with total page 516 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Production of Neutrons and Photons from Thick Targets Exposed to Light Ions and Penetration Through Shielding Materials written by T. Nakamura and published by . This book was released on 1982 with total page 241 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1972-06 with total page 1112 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analytical Methods for Nonproliferation written by Edward C. Morse and published by Springer. This book was released on 2016-04-04 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is intended to be used as a textbook and research reference for the field of nuclear nonproliferation. The book is primarily technical and focussed on methods of detecting clandestine nuclear material that might be illicitly transported. The book also touches on nuclear forensics, i.e. methods for identification, attribution, and establishment of transport pathways for illicit nuclear material. Also covered are topics of methods used for arms control and treaty verification, and an assessment of technologies under development for all of the above. A description of the government and international agencies involved in nuclear terrorism prevention, nuclear safeguards, and arms control is also included.
Download or read book Proceedings of the Second Specialists Meeting on Shielding Aspects of Accelerators Targets and Irradiation Facilities written by OECD Nuclear Energy Agency and published by OECD. This book was released on 1996 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proton Therapy Physics written by Harald Paganetti and published by CRC Press. This book was released on 2016-04-19 with total page 691 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proton Therapy Physics goes beyond current books on proton therapy to provide an in-depth overview of the physics aspects of this radiation therapy modality, eliminating the need to dig through information scattered in the medical physics literature. After tracing the history of proton therapy, the book summarizes the atomic and nuclear physics background necessary for understanding proton interactions with tissue. It describes the physics of proton accelerators, the parameters of clinical proton beams, and the mechanisms to generate a conformal dose distribution in a patient. The text then covers detector systems and measuring techniques for reference dosimetry, outlines basic quality assurance and commissioning guidelines, and gives examples of Monte Carlo simulations in proton therapy. The book moves on to discussions of treatment planning for single- and multiple-field uniform doses, dose calculation concepts and algorithms, and precision and uncertainties for nonmoving and moving targets. It also examines computerized treatment plan optimization, methods for in vivo dose or beam range verification, the safety of patients and operating personnel, and the biological implications of using protons from a physics perspective. The final chapter illustrates the use of risk models for common tissue complications in treatment optimization. Along with exploring quality assurance issues and biological considerations, this practical guide collects the latest clinical studies on the use of protons in treatment planning and radiation monitoring. Suitable for both newcomers in medical physics and more seasoned specialists in radiation oncology, the book helps readers understand the uncertainties and limitations of precisely shaped dose distribution.
Download or read book Elements of Slow Neutron Scattering written by J. M. Carpenter and published by Cambridge University Press. This book was released on 2015-09-24 with total page 539 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a comprehensive and up-to-date introduction to the fundamental theory and applications of slow-neutron scattering.
Download or read book Proceedings written by and published by . This book was released on 1995 with total page 788 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings of the 1995 Particle Accelerator Conference written by and published by . This book was released on 1996 with total page 794 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Photon Electron Proton and Neutron Interaction Data for Body Tissues written by and published by International Commission on Radiation. This book was released on 1992-01-01 with total page 207 pages. Available in PDF, EPUB and Kindle. Book excerpt:
