High Energy Heavy Ion Beams Research Articles

TRANSVERSE ENERGY PRODUCTION IN LIGHT AND HEAVY ION INTERACTIONS

Transverse energy distributions have proved to be useful in the understanding of reaction mechanisms of relativistic heavy ion interactions. The development of the subject is traced from its roots in elementary particle physics. A review and analysis of the data from recent measurements in high energy heavy ion beams at CERN and Brookhaven is presented.

Conversion efficiency for producing thermal radiation using high-energy heavy-ion beams

Using numerical simulations of radiation transport in homogeneous cylindrical targets heated by heavy-ion beams, we have explored the dependence of the

Surface metallurgy with high energy heavy ion beams

High energy noble gas ion beams are currently used to induce the formation of specific surface alloys from vacuum deposited multilayered thin film structures on metallic or insulating engineering components. We discuss in this paper the formation of metastable and stable, amorphous and crystalline phases by ion beam mixing. In particular we discuss the intermetallic compounds of the Fe-Al thin film bilayer system formed on the surface of insulating substrates by means of high vacuum furnace annealing, ion bombardment of the bilayer interface and the simultaneous combination of these two metallurgical treatments.

The propagation of relativistic heavy ions in multielement beam lines.

We describe calculations of the energy loss, range, stopping power, multiple scattering, and other related properties of a high-energy heavy-ion beam at any one of a set of beam line elements. A beam line element (e.g., any beam modification, detection, or control device) is characterized by its thickness, areal density, aperture, and function. The loss of multiply scattered particles to any finite-aperture detector is calculated in the small-angle approximation, and the position of the Bragg peak, as given by particles stopping in the second of two ionization chambers used for Bragg curve measurements, is estimated. A general purpose computer program, PROPAGATE, has been written to allow addition, deletion, and modification of the beam line elements used in the calculation and to provide a convenient means of repeating such calculations for arbitrary beam lines. Calculations and experimental measurements are compared and found to be in satisfactory agreement.

HEAVY ION SECONDARY BEAMS

The possibility of producing secondary beams of radioactive nuclei is an interesting application of medium and high energy heavy ion beams. After a first attempt at CERN (1) , two experiments have been performed at GANIL, using 44 MeV/u 40Ar (2) and 65 MeV/u 180 projectiles. This paper recalls the results of the Ar experiment, and presents new data obtained with the 180 beam.

Heavy ion beam pumped lasers

Particle beams with energy per particle ranging from a few keV to greater than 1 GeV have been used to pump gas lasers. Well-focused high energy heavy ion beams have a short range, low range straggling and high specific energy loss which increases with the square of the effective charge. They can be used to pump a small cylindrical volume which can be well-matched to the optical axis of a laser resonator. Results obtained to date are described with both cw and pulsed particle beams; and possible extensions using heavy ion storage rings considered.

Ion Irradiation Smoothing and Film Bonding for Laser Mirrors

ABSTRACTIrradiation with high energy heavy ion beams has been investigated as a technique for improving the quality of highly reflecting metallic surfaces to be used as laser mirrors. Properties such as reflectivity, corrosion resistance, film bonding, and threshold to laser surface damage have been examined. Modifications of composition and microstructure of the material associated with the heavy ion irradiation have been measured with RBS, TEM, SEM, Auger, and ESCA. Reflectivity and extinction coefficient measurements were made using ellipsometry techniques. Observations indicate that keV heavy ion irradiations in the fluence range of 1015 to 1016 cm−2 produce significant surface smoothing. Additionally, MeV implants of heavy ions into films of Cu, Ag, Au and Al deposited on molybdenum substrates resulted in improvements to both tarnish resistance and structural bonding integrity.

Novel low-temperature recrystallization of amorphous silicon by high-energy ion beam

An entirely new beam annealing method that employs a high-energy (∼2.5 MeV) heavy ion (As75, Kr84) beam is presented. With this technology, an amorphous Si layer is recrystallized at below ∼300 °C substrate temperature (much lower than the ordinary solid phase epitaxial growth temperature of ∼600 °C). The temperature just under the beam spot is estimated to be at most ∼20° C higher than that in the surrounding region, because of the large beam spot size (∼10 mmφ) and rapid scan speed (∼104 cm/s). This low-temperature annealing feature is quite different from the case for conventional furnace, laser, electron, and low-energy ion beam annealing. After recrystallization, impurity As atoms are located at substitutional sites with no tetrahedral interstitial components, and are scarcely redistributed.

Novel Low Temperature (\\lesssim300°C) Annealing of Amorphous Si by Scanned High Energy (∼2.5 MeV) Heavy Ion Beam

Novel ion beam annealing (HIBA, High energy heavy Ion Beam Annealing) with high energy (∼2.5 MeV) heavy ion beam is presented. By HIBA, an amorphous Si layer is recrystallized below (∼300°C of substrate temperature (much lower than oridinary solid phase epitaxial growth temperature ∼600°C). Also, the temperature just under the beam spot is estimated to be ∼20°C higher at most than that of surrounding region, because of large beam spot size (∼10 mmφ) and rapid scan speed (∼104 cm/s). This low temperature feature is quite different from the conventional furnace, laser, electron or low energy ion beam annealing. After HIBA, impurity As atoms are located at substitutional site with no tetrahedral interstitial component and are scarcely redistributed.

A method for fragmentation analysis of accelerated high-energy heavy-ion beams

A 570 MeV/nucleon argon Bevalac beam was degraded in water and stopped in a stack of Lexan plastic nuclear track detectors. By means of track etching and computerized image analysis, the tracks of beam fragments were measured between 18 and 22 g/cm 2 which is downstream of the original particles stopping point (17.6 g/cm 2). The charge distribution of the fragments measured in this experiment and the charge-specific distributions of stopping points in the plastic stack for the fragments are presented. The stopping point distributions are compared with results of a Monte Carlo calculation.

Microdosimetry of Range-Modulated Bearns of Heavy Ions: I. Determination of the Yield of Projectile Fragments from Microdosimetric Spectra for Neon- 10 Beams

A method for the calculation of projectile fragmentation spectra from microdosimetric distributions for heavy ions is proposed. The fundamental quantity determined in microdosimetric measurements is the distribution of energy deposited in a specified volume. It is known that, for high-energy heavy-ion beams, the nuclear interactions are dominated by projectile fragmentation in which the secondary particles are emitted with a velocity nearly equal to that of the primary particle. Therefore, it is possible to calculate the distribution of energy deposited for each particle type; the microdosimetric spectra can then be used to determine the relative contributions from each type of particle. Experimental microdosimetric data obtained for a range-modulated beam of 557 MeV/amu neon ions are presented and the data in the plateau are analyzed as an example of this technique.

Collective Longitudinal Motion in Intense Ion Beams

Inertial Confinement Fusion (ICF) using high energy heavy ion beams requires tight focussing of the igniting ion beams in longitudinal, as well as transverse, space at the pellet target. This sets significant requirements for stability in longitudinal motion. It has been previously noted that this motion can contain significant resistive wall instability. Results of numerical simulations of this instability in perturbed bunched beams are presented and analyzed. It is found that reflection of perturbations off bunch ends is distorted and delayed by space charge forces and that soliton waves can appear after reflection.

Semiconductor Detectors for Medical Tomography with High-Energy Heavy Ions

High-energy heavy ion beams are in use at the Lawrence Berkeley Laboratory for cancer therapy. In order to take full advantage of the very favorable depth-dose characteristics of those beams, it is necessary to determine the stopping characteristics of the ions in the complex media of a human with greater accuracy than obtainable with X-ray CAT scanning. Initial measurements with an array of Si dE/dx position sensitive detectors and a windowless thin planar Ge detector used in a side entry mode show the potential for fabricating an instrument for high accuracy on-line CAT scanning using the same ions to be used for therapy. It is estimated that one tomography can be obtained with a dose of 0.72 Rad-gm.

Inactivation of Human Kidney Cells by High-Energy Monoenergetic Heavy-Ion Beams

Presented are fundamental data on the biological effects of monoenergetic beams of carbon (400 MeV/amu), neon (425 MeV/amu), and argon (570 MeV/amu). Cell survival of human kidney T-1 cells was measured under aerobic and hypoxic conditions over a range of mean LETinfinity from 10 to 600 keV/..mu..m. RBE and OER were measured under hypoxic and aerobic conditions with attention paid to dose, mean LETinfinity, and particle charge effects. (DS)

Propagation of a high energy heavy ion beam through matter

Abstract The propagation of high energy nuclei through water is calculated considering the energy loss and the fragmentation of the nuclei. The probabilities for the production of beam fragments in nuclear collisions are derived from proton target cross sections. For heavier target nuclei an empirical scaling factor is used. In the paper the production of fragments from monoenergetic beams of C, Ne and Ar for various absorber depths is investigated. From the energy spectra of the remaining beam particles and of the fragments depths dose curves are derived. These results are compared with experimental data.

Controlled Thermonuclear Fusion Ignited by High Energy Heavy Ion Beams

Controlled Thermonuclear Fusion Ignited by High Energy Heavy Ion Beams

Systems Analysis of Accelerator and Storage Ring Systems for Inertial Fusion

A computerized systems model is being developed to help assess the relative merits of the various accelerator systems that appear able to meet the requirements for inertial fusion with high energy heavy ion beams. Assessment involves calculating the total cost and parameters that are critical to technical feasibility. Current results showing cost trends and important technical parameters for rf linac/storage ring systems using ions of different mass, charge state, and kinetic energy are presented.

The BEVALAC: high-energy heavy-ion beams for biomedical research

The BEVALAC is a compound accelerator consisting of the HILAC and the BEVATRON, for the purpose of obtaining large intensities of high-energy heavy ions. Biomedical facilities including irradiation caves for physical, biological and medical research are intended to be available as a national facility. High-energy heavy-ion beams have already been shown (at the PPA and the Bevatron) to have physical characteristics useful for biomedical investigations, including a high sharp Bragg peak, good depth-dose characteristics, high-LET, very low contamination and nuclear fragmentation cross-sections which do not 'spoil' the beam for lesion production or possible tumour irradiation deep in tissue. Several new applications to radiological physics are being studied, including radioactive beams, autoactivation for locating the beam track. and heavy ion radiography, tomography and laminography.

Composition of High-Energy Heavy-Ion Beams: Preliminary Measurements

MACCABEE, H. D. Composition of High-Energy Heavy-Ion Beams: Preliminary Measurements. Radiat. Res. 54, 495-509 (1973). Silicon semiconductor detector systems were used to measure the energy-deposition spectra of 240-MeV/nucleon oxygen ion beams at the Bevatron of Lawrence Berkeley Laboratory. The results are useful for determining the composition of the beam, before and after passing through varying thicknesses of water absorber. In particular, contamination of the incident oxygen beam by carbon ions on the order of 1% was detected and resolved. Secondary particles due to nuclear fragmentation in water were identified and quantified. The experimental estimate of the mean free path of fast oxygen ions in water is 20 g/cm2, in agreement with calculations from cosmic ray data and geometric cross sections.

First Phase of Heavy Ion Acceleration at the Bevatron

High Energy Heavy-Ion Beams have become a standard operational feature of the Bevatron. A diver-sified experimental program using these beams complement the traditional proton-physics program, and at present accounts for about one-quarter of the Bevatron operation time. Beams of ion species up to mass number 20 (neon), and with intensities up to 108 particles per pulse for carbon, are available on target in the extracted beam channel. Initial heavy-ion operation began a year-and-one-half ago and for the most part utilized existing Bevatron features and capabilities. Acceleration of ion species heavier than helium-ions, however, required the adaptation of a side-extracted PIG ion-source to the Bevatron pre-injector. The immediate success of this development effort and the concomitant demand for experimental beam time motivated an improvement program to provide higher beam intensities, improved beam control and monitoring, and closed-loop beam control for intensities as low as 106 particles per pulse. Single particle beam dynamics has been invest igated. Predicted operation settings based on these studies are found to be close to actual running parameters. Losses due to recomibination are well explained with existing theories for single electron capture.