Showing papers on "Linear particle accelerator published in 1970"

Linear particle accelerator with coast through shield

Abstract: Charged particles injected into an energy beam, are accelerated by electric fields established in gaps between tubular electrodes through which the particles pass. Alternate gaps between the electrodes are enclosed by tubular shields through which the particles coast between the accelerating fields. The electrodes are charged by d.c. sources of opposite polarity.

Performance of a new 4 MeV standing wave linear accelerator.

Abstract: A new 4 MeV linear accelerator, utilizing a compact standing waveguide accelerator whose x-ray beam is colinear with th e electron beam, is described. An output of 350 rads /rninute is possible with a sharp beam and a narrow penumbra. Isodose curves are discussed and transverse plots analyzed in detail; decrement lines for different field widths are plotted and their significance established. Also included are rotational aspects and clinical considerations concerning adjacent fields and the dose at depth in the region of varioussize gaps.

The stability of the X-ray beam from an 8 MV linear accelerator designed for radiotherapy

Abstract: A study has been made of the stability of the X-ray beam from an 8 MV medical linear accelerator (M.E.L. Equipment Co. Ltd., type SL75 Super). The flatness of the beam and the intensity of the beam as measured by the built-in monitor are found to suffer small changes with gantry angulation and with time. Measurements have been extended over a year during which the accelerator has been in daily use for radiotherapy. The causes of the changes in the beam and the function of the stabilising circuits which largely counteract such changes are outlined. The resulting complex system must be controlled by radiation measurements on the beam. Simple measuring jigs have been made for the purpose and are described; they allow thimble ionisation chambers to be accurately positioned in the beam during gantry angulation and for daily, weekly and monthly checks. By routine use of these devices the changes of the beam have been monitored and appropriate control adjustments made to the accelerator when necessary. ...

Electromagnetic and mechanical properties of niobium cavities for a superconducting electron linear accelerator.

Abstract: This paper describes the computer studies of the electromagnetic and mechanical properties of an S-band superconducting accelerator. The structure under discussion is intended for a test accelerator using a 15-cavity niobium traveling-wave resonant-ring structure operating in the 28/3 mode. Many of the parameters for this short test accelerator, such as the frequency (2856 MHZ) and the accelerating field (33 MV/m), are the same as those proposed for the possible conversion of the SLAC two-mile long linear accelerator. The electromagnetic studies were made to optimize the various structure parameters including the quality factor Q, the shunt impedance r, the ratio r/Q, and the ratios of the peak-to-effective electric and magnetic fields. The resulting structure has a slight bulge at the disk tip and an elliptical cross section at the outer wall. ratios are f?/Eeff=l. 66 and fi/E,ff= The calculated values for the peak field 31 G/(MeV/m). The paper includes a comparison of these and other parameters for different modes between n/2 and T. The mechanical studies were made to determine the frequency shifts due to deflection of the walls by the rf fields. Changes were made to the mechanical design and to the fabrication techniques during the study to minimize these frequency shifts.

High intensity linear accelerators

Abstract: 1,220,496. Particle accelerators; heavy-ion beam tubes; cathode ray tubes. ROUMANIA, INSTITUTE OF ATOMIC PHYSICS. 10 April, 1968 [10 April, 1967], No. 17174/68. Heading H1D. A linear accelerator has a hollow tubular electron or ion beam formed by an annular source S at one end of an elongated evacuated chamber 7 and, after acceleration through the annular passage of a particle accelerator to the opposite end of chamber 7, the beam is focused on to the longitudinal axis of the chamber by a rotationally symmetrical deflector 6. As shown, the beam is accelerated by a continuous or pulsed electric field applied to tubular electrodes 2-5 and focused by tubular electrode 6. Alternatively, the beam is accelerated by a radiofrequency field existing in a waveguide which is loaded with discs which may have drift tubes, Figs. 3 and 4 (not shown), or the wave guide may have an interdigitated loading structure, Fig. 5 (not shown). Acceleration may also be obtained by using a cylindrical or coaxial cavity, Figs. 6A, 6B (not shown). A number of tubular beams of different radii may be used with a filiform beam to enhance the intensity.

Modification of the berkeley hilac.

Abstract: A program is presently in progress for the modification of the Hilac to make possible the acceleration of ions of all masses to a maximum energy of 8.5 MeV/N. Present scheduling calls for the shut down of the existing Hilac in January 1971 and first beams from the modified system in August 1971. The improved accelerator will consist of a pressurized 2.5 MV Cockcroft-Walton injecting ions of minimum charge-to-mass ratio ϵ=0.045, at 0.112 MeV/N into an Alvarez linac. The linac will be separated at 1.2 MeV/N where particles will be stripped to a minimum ϵ=0.16. The second linac section will be partitioned into individual cavities of approximately equal velocity increments. Adjustment of rf phase and gradient in these cavities will provide variable energy from 2.6 to 8.5 MeV/N. All cavities will operate at 70.2 MHz and magnetic quadrupole focusing will be used throughout.

Current Profile Monitor for Use in Scanning Electron Beam Irradiations

Abstract: A current profile monitor for the scanning electron beam from the accelerator is described. It utilizes the fact that the electrons scattered through large angles by the exit window of the scanner show a profile similar to that of the main beam at the irradiation site. The scattered electrons are collected by small probes arranged in a linear array parallel to the scanning direction, and the beam profile in this direction is displayed by a storage oscilloscope or an X‐Y recorder. This device has been used for electrons of energies 4–16 MeV from a linear accelerator and proved to be useful for continual monitoring with negligible disturbance to the irradiation in progress.

Investigation of hypervelocity microparticles impact phenomena

Abstract: Micrometeoroid linear accelerator for particle velocities up to 25 km/sec and thin film penetration studies