[en] Forward-angle differential cross sections for the (π⁺,π⁰) reaction leading to the Isobaric Analog State in the residual nuclei at 300, 435, 500 and 550 MeV have been measured. Targets ranged in mass from ⁷Li to ²⁰⁸Pb. A description of the experimental setup and the analysis is presented. The O⁰ cross sections are found to rise markedly between 300 and 435 MeV, contrary to the extrapolation from the lower energy data and to the behavior of the free pion-nucleon single charge exchange process. The angular distributions are sharply forward peaked. Systematics of the data indicate increased volume penetration with increasing pion beam energy. The cross sections are compared with the results of Glauber model calculations indicating the significance of higher order processes even at these energies

[en] Forward-angle differential cross sections for the (π⁺, π⁰) reaction leading to the Isobaric Analog State in the residual nuclei at 300, 425, 500 and 550 MeV have been measured. Targets ranged in mass from ⁷Li to ²⁰⁸Pb. A description of the experimental setup and the analysis is presented. The 0⁰ cross sections are found to rise markedly between 300 and 425 MeV, contrary to the extrapolation from the lower energy data and to the behavior of the free pion-nucleon single charge exchange process. The angular distributions are sharply forward peaked. Systematics of the data indicate increased volume penetration with increasing pion beam energy. The cross sections are compared with the results of Glauber model calculations indicating the significance of higher order processes even at these energies. 67 refs., 40 figs., 22 tabs

[en] An overview of operational radiation protection (RP) policies and practices at high-energy electron and proton accelerators used for physics research is presented. The different radiation fields and hazards typical of these facilities are described, as well as access control and radiation control systems. The implementation of an operational RP programme is illustrated, covering area and personnel classification and monitoring, radiation surveys, radiological environmental protection, management of induced radioactivity, radiological work planning and control, management of radioactive materials and wastes, facility dismantling and decommissioning, instrumentation and training.

[en] The LCLS, the world's first x-ray free electron laser, will be constructed at the Stanford Linear Accelerator Center and is expected to be completed in 2009. A two-mirror system will be used in order to reduce background radiation in near and far experimental hutches. This paper describes the layout of the two-mirror system and also reports on the shielding requirements for the experimental hutches. Two beam loss scenarios for radiation sources are discussed: losses from the high energy electron beam hitting beam components and x-rays produced in the 130 m long undulator and scattered on x-ray mirrors. The FLUKA Monte-Carlo particle transport code was used for the shielding design and for the determination of the radiation levels around the experimental hutches

[en] The authors describe some of the work that they have done as a contribution to the Next Linear Collider (NLC) Zeroth-Order Design Report (ZDR), with specific emphasis placed on radiation-protection issues. However, because of the very nature of this machine--namely, extremely-small beam spots of high intensity--a new approach in accelerator radiation-protection philosophy appears to be warranted. Accordingly, the presentation will first take a look at recent design studies directed at protecting the machine itself, since this has resulted in a much better understanding of the very short exposure times involved whenever beam is lost and radiation sources are created. At the end of the paper, the authors suggest a Beam Containment System (BCS) that would provide an independent, redundant guarantee that exposure times are, indeed, kept very short. This, in turn, has guided them in the determination of the transverse shield thickness for the machine

[en] The Program MUCARLO is a computer code developed at the Stanford Linear Accelerator Center (SLAC) to study the muon flux generated from beams of electrons and positrons on various targets. The MUCARLO program has been modified extensively in recent years; this paper describes the latest version. Preliminary results from this code are presented, and compared with results from another (TOMCAT) and with experimental data

[en] A low intensity electron beam parasitic to the operation of the Stanford Linear Collider (SLC) has been transported through the Final Focus Test Beam (FFTB) facility making secondary test beams available for users. Photons generated in collimation of the SLC electron and positron beams in the linac pass through a splitter magnet that deflects the primary beams away from the linac axis into the SLC beam lines. These photons are converted to electrons and positrons in a secondary production target located down beam on the linac axis. The secondary electrons are then transported through the FFTB beam line onto experimental detectors. The average power of the parasitic beam is very low, thus, it presents no hazards. However, various accident scenarios involving failure of the splitter magnet and the active protection devices could send much more powerful SLC beams (up to 90 kilo-watts) into this zero-degree secondary beam line. For the accident cases, the average power in the transmitted beam was calculated using the Monte Carlo programs EGS4 and TURTLE. Results from analysis of the radiation protection systems that assure safety during the parasitic operation are presented

[en] As the Stanford Synchrotron Radiation Lightsource (SSRL) of the SLAC National Accelerator Laboratory (SLAC) is moving toward Top-Off injection mode, SLAC's Radiation Protection Department is working with SSRL on minimizing the radiological hazards of this mode. One such hazard is radiation that is created inside the accelerator concrete enclosure by injected beam. Since during Top-Off injection the stoppers that would otherwise isolate the storage ring from the experimental area stay open, the stoppers no longer prevent such radiation from reaching the experimental area. The level of this stray radiation was measured in April 2008 during the first Top-Off injection tests. They revealed radiation dose rates of up to 18 microSv/h (1.8 millirem/h) outside the experimental hutches, significantly higher than our goal of 1 microSv/h (0.1 millirem/h). Non-optimal injection increased the measured dose rates by a factor two. Further tests in 2008 indicated that subsequent improvements by SSRL to the injection system have reduced the dose rates to acceptable levels. This presentation describes the studies performed before the Top-Off tests, the tests themselves and their major results (both under initial conditions and after improvements were implemented), and presents the controls being implemented for full and routine Top-Off injection.

[en] The Linac Coherent Light Source (LCLS), the world's first X-ray free electron laser, will be constructed at the Stanford Linear Accelerator Center (SLAC) and is expected to be completed in 2009. A two-mirror system will be used in order to reduce background radiation in near and far experimental hutches. This paper describes the layout of the two-mirror system and also reports on the shielding requirements for the experimental hutches. Two beam loss scenarios for radiation sources are discussed: losses from the high energy electron beam hitting beam components and X-rays produced in the 130 m long undulator and scattered on X-ray mirrors. The FLUKA Monte-Carlo particle transport code was used for the shielding design and for the determination of the radiation levels around the experimental hutches

[en] The Linac Coherent Light Source (LCLS) is a Self-Amplified Spontaneous Emission based Free Electron Laser (FEL) that is being designed and built at the Stanford Linear Accelerator Center (SLAC) by a multilaboratory collaboration. This facility will provide ultra-short pulses of coherent x-ray radiation with the fundamental harmonic energy tunable over the energy range of 0.82 to 8.2 keV. One-third of the existing SLAC LINAC will compress and accelerate the electron beam to energies ranging from 4.5 GeV to 14.35 GeV. The beam will then be transported through a 130-meter long undulator, emit FEL and spontaneous radiation. After passing through the undulator, the electron beam is bent to the main electron dump. The LCLS will have two experiment halls as well as x-ray optics and infrastructure necessary to make use of the FEL for research and development in a variety of scientific fields. The facility design will incorporate features that would make it possible to expand in future such that up to 6 independent undulators can be used. While some of the radiation protection issues for the LCLS are similar to those encountered at both high-energy electron linacs and synchrotron radiation facilities, LCLS poses new challenges as well. Some of these new issues include: the length of the facility and of the undulator, the experimental floor in line with the electron beam and the occupancy near zero degrees, and the very high instantaneous intensity of the FEL. The shielding design criteria, methodology, and results from Monte Carlo and analytical calculations are presented