Proton Beam Facility Research Articles

Compact designs for comprehensive proton beam clinical facilities

The use of accelerated beams of protons in cancer therapy has proven to be of great value. The accelerators currently being used for such therapy were originally built for other purposes, e.g. physics research. Several institutions are presently hoping to construct medically dedicated proton accelerators, and because of the great expense associated with added space in medical facilities there is great interest in designing complete proton-beam facilities that are as compact as possible. The shielding and other requirements for such facilities are discussed and applied to a specific example: a facility with a movable isocentric gantry (for beam delivery to the patient from a variety of angles) and two fixed beams.

Extension of 400 keV proton beam facility for the characterisation of superlattices: AKMM Haque and LR Howard, Department of Physical Sciences and Scientific Computing, Polytechnic of the South Bank, London SE1 0AA, UK

Extension of 400 keV proton beam facility for the characterisation of superlattices: AKMM Haque and LR Howard, Department of Physical Sciences and Scientific Computing, Polytechnic of the South Bank, London SE1 0AA, UK

Elemental analysis of liquids by external beam PIXE down to PPB level

A method is reported for the direct elemental analysis of solutions and liquids by PIXE, utilizing the external proton beam facility at the Van de Graaff accelerator of the Atomic Energy Centre, Dacca. The samples were irradiated in liquid form through a thin Mylar window holding the liquid in a small polyethylene cup. The proton beam was allowed to pass from the vacuum into the air through a 7 μm Be window, then through an air path of 23 mm and the Mylar window of the sample cup, into the solution. Mylar windows up to 1 mg/cm 2 in thickness were used. The X-rays were detected at 90° relative to the beam with a Si(Li) detector. Minimum detection limits and efficiency curves are reported, and the behaviour of some ions during irradiation is discussed. It is shown that under favourable conditions the sensitivity of the method can reach the ppb level.

Superconducting spin tipping solenoids for ZGS polarized beam facility

Two superconducting solenoids have been designed and built for the Argonne Zero Gradient Synchrotron (ZGS) Polarized Proton Beam Facility. Each solenoid will have a central field of 8.0 T, an effective field length of about 1.75 m, and a cold clear bore of 11.5 cm. It will generate a spin-tipping integral field of about 14 T-m. The integral field homogeneity over the cold bore is ± 4%. The magnet stored energy is about 0.7 MJ. Described in detail is the stability simulation on a high current density intrinsic stable coil. Comparisons are made between the simulation data and data obtained from the magnet performance tests. The cryostat design and construction are also presented.

ISABELLE e-p Option

During the ISABELLE preliminary design study it became clear from the response of the high energy physics community that the addition of an electron ring to the proposed 200-GeV colliding proton beam facility would be very attractive. It was felt that with the capability of this ring to reach an energy of 15 GeV the already wide range of experimental possibilities of ISABELLE would be greatly extended. Basic design features for such an electron ring have been worked out. Lattice parameters, rf system, injection scheme and characteristics of its interaction with one of the proton rings will be presented. The resulting luminosity was estimated to range from ? 1033 to ? 0.5 × 1032 cm-2 sec-1 for c.m. energies from 65 to 109 GeV.

Differential cross sections and polarizations in elastic p-d scattering at medium energies

Differential cross sections for p-d elastic scattering have been measured at 22.0, 35.0 and 46.3 MeV using the energy-analysed external proton beam of the UCLA sector-focussed cyclotron. The angular distributions cover centre-of-mass angles between 9° and 168°. At forward angles both protons and deuterons were observed using a d E/d x- E telescope counter consisting of a fully depleted surface-barrier detector ( ΔE) and a NaI(Tl) scintillation detector. ( E). At larger angles, protons were observed using an array of four NaI(Tl) scintillation detectors. The differential cross sections have in general a relative uncertainty less than 2%, while the absolute scale of the measurements has an uncertainty of 1.7%. The proton polarization angular distributions at 35.0 and 40.0 MeV were also measured. In this part of the experiment, the polarized proton beam facility was used. The polarized proton beam was obtained by scattering the internal beam of the cyclotron from a carbon scatterer. At 35.0 MeV, the polarization angular distribution covers centre-of-mass angles between 20° and 164°. At 40.0 MeV, measurements were made for centre-of-mass angles greater than 130° only. Scattered particles were observed using six NaI(Tl) scintillation detectors placed in groups of three on either side of the incident beam. The target used when detecting elastically scattered protons was deuterium gas. The backward part of the angular distribution was measured by detecting recoil deuterons from a deuterated polythylene target. The available proton polarization data for p-d elastic scattering have been used to construct a polarization contour diagram for the energy range of 10–400 MeV.