Vacuum Insulation Tandem Accelerator Research Articles

VITA high flux neutron source for various applications

A high flux neutron source based on a vacuum-insulated tandem accelerator (VITA) and a lithium target has been proposed and developed at the Budker Institute of Nuclear Physics in Novosibirsk, Russia. We describe VITA which provides a dc proton/deuteron beam with an energy within a range of 0.6–2.3 MeV with a current from 1 nA to 10 mA. VITA is also capable of producing α-particles through the 7Li(p,α)α and 11B(p,α) α α reactions, 478 keV photons through the 7Li(p,p ′ γ)7Li reaction and positrons through the 19F(p,e+e−)16O reaction. We present several applications of this source: boron neutron capture therapy, nuclear cross sections determination, lithium target study, radiation blistering of metals during proton implantation and the radiation testing of promising materials.

Increasing the Electric Strength of a Vacuum-Insulated Tandem Accelerator

The electric strength of ceramic insulators was tested at a dedicated high-voltage vacuum facility and the electric strength of a vacuum-insulated tandem accelerator with redesigned feedthrough insulators was studied. Based on the results of the investigations and the upgrade the voltage in the accelerator was increased from 1.00 to 1.15 MV; the operating mode was achieved without high-voltage breakdowns.

A Fast-Neutron Source Based on a Vacuum-Insulated Tandem Accelerator and a Lithium Target

The production of a deuteron beam in a vacuum-insulated tandem accelerator and the generation of fast neutrons from a lithium target have been investigated. The possibility of using a source of fast neutrons for radiation testing of materials and for fast-neutron therapy is discussed.

Development of continuous wave high voltage negative ion beam injector for tandem accelerator.

A vacuum-insulated tandem accelerator, delivering the continuous wave 8 mA, 2 MeV proton beam, is operated regularly at the Budker Institute of Nuclear Physics, where a 10 mA, 25 keV negative ion injector is used. Recently, a new injector with an upgraded negative ion source and beam preacceleration has been developed to increase the tandem accelerated current. The transport line of the new injector is composed of a bending magnet with 90° ion beam turn, an acceleration tube for negative ion acceleration to the energy up to 150 keV, and a 0.6 m long transport section. The H- ion beam production, its acceleration, and transport were studied at a test stand, which is equipped with electrical and optical diagnostics. The data on 14 mA, 133 keV continuous wave negative ion beam production and transport are presented. The undesirable coacceleration of secondary electrons, produced in the acceleration tube, was recorded as well. The coaccelerated electrons' current contributed up to 2% of the total accelerated beam at the operational vacuum in the low energy beam transport. The coaccelerated electrons were removed from the beam with a magnetic filter. The numerical modeling of the beam transport was carried out. A reasonable agreement between the modeled and experimental data was obtained.

A Novel Dedicated HVE 14C AMS System

ABSTRACTHigh Voltage Engineering Europa (HVE) has designed a vacuum-insulated tandem accelerator dedicated to radiocarbon (14C) analysis. A unique feature of the design is a magnetic charge state selector that is incorporated in the high voltage terminal, which reduces the primary source of background that originates from the injection of 13CH− to negligible levels. As a result, background levels in the low 10−16 regimes are anticipated, thus supporting the most stringent 14C dating applications. Another feature of the system is the incorporation of several slit feedback loops for stabilization of the position of the ion beam throughout the system, which avoids drift and ensures stable, long-term operation. Finally, this article presents measurements and quantitative analysis of background contributions from 13CH−.

In Situ Observations of Blistering of a Metal Irradiated with 2-MeV Protons

A vacuum-insulated tandem accelerator was used to observe in situ blistering during 2-MeV proton irradiation of metallic samples to a fluence of up to 6.7 × 1020 cm−2. Samples consisting of copper of different purity, tantalum and tantalum-copper compounds were placed on the proton beam path and forced to cool. The surface state of the samples was observed using a charge-coupled device camera with a remote microscope. Thermistors, a pyrometer and an infrared camera were applied to measure the temperature of the samples during irradiation. After irradiation, the samples were analyzed on an X-ray diffractometer, laser and electron microscopes. The present study describes the experiment, presents the results obtained and notes their relevance and significance in the development of a lithium target for an accelerator-based neutron source, for use in boron neutron capture therapy of cancer.

Studying the energy stability of a vacuum-insulated tandem accelerator using γ-resonance reactions

Experiments on the detection of γ rays generated in the 13C(p, γ)14N reaction at the Novosibirsk vacuum-insulated tandem accelerator were carried out. Owing to the updated detection system, it was possible to measure the energy spread of beam protons and develop a method for long-term stabilization of the slow drift of the beam energy. The measured energy spread was 1.20 ± 0.15 keV, which was only 0.07% of the total beam energy. This makes the tandem accelerator developed by the vacuum-insulated Budker Institute of Nuclear Physics an attractive tool for solving various research and applied problems.

Experiments to increase the parameters of the vacuum insulation tandem accelerator for boron neutron capture therapy

An epithermal neutron source that is based on a vacuum insulation tandem accelerator (VITA) and lithium target was created in the Budker Institute of Nuclear Physics for the development of boron neutron capture therapy (BNCT). A stationary proton beam with 2 MeV energy and 1.6 mA current has been obtained. To carry out BNCT, it is necessary to increase the beam parameters up to 2.3 MeV and 3 mА. Ways to increase the parameters of the proton beam have been proposed and discussed in this paper. The results of the experiments are presented.

A new concept of a vacuum insulation tandem accelerator

A tandem accelerator with vacuum insulation has been proposed and developed in the Budker Institute of Nuclear Physics. Negative hydrogen ions are accelerated by the positive 1MV potential of the high voltage electrode, converted into protons in the gas stripping target inside the electrode, and then the protons are accelerated again by the same potential. The potential for high voltage and intermediate electrodes is supplied by the sectioned rectifier through a sectioned bushing insulator with a resistive divider. In this work, we propose a radical improvement of the accelerator concept. It is proposed to abandon the separate placement of the accelerator and the power supply and connect them through the bushing insulator. The source of high voltage is proposed to be located inside the accelerator insulator with high voltage and intermediate electrodes mounted on it. This will reduce the facility height from 7m to 3m and make it really compact and attractive for placing in a clinic. This will significantly increase the stability of the accelerator because the potential for intermediate electrodes can be fed directly from the relevant sections of the rectifier.

BINP accelerator based epithermal neutron source

Innovative facility for neutron capture therapy has been built at BINP. This facility is based on compact vacuum insulation tandem accelerator designed to produce proton current up to 10 mA. Epithermal neutrons are proposed to be generated by 1.915-2.5 MeV protons bombarding a lithium target using (7)Li(p,n)(7)Be threshold reaction. In the article, diagnostic techniques for proton beam and neutrons developed are described, results of experiments on proton beam transport and neutron generation are shown, discussed, and plans are presented.

Dosimetry and spectrometry at accelerator based neutron source for boron neutron capture therapy

Abstract An innovative accelerator-based neutron source for boron neutron capture therapy has started operation at the Budker Institute of Nuclear Physics, Novosibirsk. This facility is based on a compact vacuum insulation tandem accelerator designed to produce proton current up to 10 mA. Epithermal neutrons are proposed to be generated by 1.915 MeV protons bombarding a lithium target using 7 Li( p , n ) 7 Be threshold reaction. In the article, techniques to detect neutron and gamma-rays at the facility are described. Gamma radiation is measured with NaI and BGO gamma-spectrometers. The total yield of neutrons is determined by measuring the 477 keV γ-quanta from beryllium decay. For the rough analysis of the generated neutron spectrum we used bubble detectors. As the epithermal neutrons are of interest for neutron capture therapy the NaI detector is used as activation detector. We plan to use a time-of-flight technique for neutron spectra measurement. To realize this technique a new solution of short time neutron generation is proposed.

The detection of nitrogen using nuclear resonance absorption of mono-energetic gamma rays

A new vacuum-insulated tandem accelerator capable of producing a 5-mA proton beam with energy up to 2MeV was used to produce a mono-energetic beam of 9.17-MeV gamma rays from the resonant production reaction, 13C(p,γ)14N, at 1.76MeV. A graphite target enriched with 13C capable of withstanding the proton beam power was designed and fabricated. The 9.17-MeV gamma rays were subsequently resonantly absorbed in 14N via the inverse reaction, 14N(γ,p)13C. The data acquisition system to measure the resonance absorption in nitrogen includes a BGO detector and a goniometer and collimator assembly that rotate around the axis produced by the intersection of the proton beam and the production target. The accuracy of rotation of the detector around the target is approximately 0.1°. The results of the resonance gamma ray absorption measurements are presented to demonstrate the feasibility of the method to sensitively and selectively detect high concentrations of nitrogen, comparable to those found in most explosives.

First neutron generation in the BINP accelerator based neutron source

Pilot innovative facility for neutron capture therapy was built at Budker Institute of Nuclear Physics, Novosibirsk. This facility is based on a compact vacuum insulation tandem accelerator designed to produce proton current up to 10 mA. Epithermal neutrons are proposed to be generated by 1.915 MeV protons bombarding a lithium target using 7Li(p,n) 7Be threshold reaction. The results of the first experiments on neutron generation are reported and discussed.

The Effect of the Gas Released by the Charge Exchange Target of a Tandem Electrostatic Accelerator with Vacuum Insulation on the Electric Strength of Its High-Voltage Gaps

As part of a program aimed at the development of a vacuum-insulation tandem accelerator with a proton energy of 2.5 MeV and a current of several tens of milliamperes, the distribution of the density of the gas released into an evacuated volume by the stripping target was measured. The results from high-voltage tests of a coaxial 45-mm vacuum gap with an electrode area of 0.71 m2, obtained at various values of residual pressure, are presented.