High Energy Heavy Ion Microbeam Research Articles

Beam optics of upgraded high energy heavy ion microbeam in Lanzhou

In order to expand applications of the Lanzhou microbeam the resent improvements were introduced in its slits, lens system and target chamber. In this study a beam optics of the new system was calculated for the 12C+6 ion beam of 966 MeV. To compensate a negative influence of a sector magnet dispersion on the beam dynamics an excitation of the magnetic quadrupole between two bending dipoles was determined. By varying parameters of the final triplet of magnetic quadrupole lenses a set of the microbeam systems with a stigmatic focusing were obtained. The best two of them were selected applying an optimization for a beam collimation by object and divergence slits. Simulation of the beam dynamics after the collimation allowed to determine the slit sizes that provide the highest current in the 1 µm probe on the target for these microbeam systems.Additionally, to improve the beam parameters at the microbeam entrance and then match the system parameters with this beam, the approach of an automatic probe-forming system is proposed. It is aimed at providing the highest possible resolution of the microbeam for the different beam varieties from a cyclotron.

The data acquisition and beam control system at the IMP microbeam facility

To perform routine irradiation and spatial analysis using ion microbeam, a compact data acquisition and beam control system was developed at the high energy heavy ion microbeam facility in the Institute of Modern Physics (IMP), CAS. The system comprises PXI modules from National Instruments. Together with the in-house developed Cell Exposure and Nuclear Application (CENA) software using LabVIEW, the system implements beam scanning, single ion targeting, ion counting, energy spectrum measurement, spectrum mapping and sample irradiation. This paper introduces the hardware configuration, software design and preliminary tests of the data acquisition and beam control system.

High energy heavy ion microbeam irradiation facility at IMP

A high energy heavy ion microbeam irradiation facility was designed and installed in the Institute of Modern Physics (IMP) of Chinese Academy of Sciences (CAS). It can deliver well-focused ions into the targets at exact locations. With the advantage of allowing vertical irradiation as well as focusing ions from Carbon to Uranium with high energies in a broad energy range (7MeV/u to 100MeV/u for Carbon ions), this setup is able to deliver a preset number of ions into pre-selected target positions. Material specimens in vacuum and living cells in air can also be irradiated by this facility. Detailed description of this microbeam facility as well as its beam optics is presented in this paper. Some preliminary test results are also given.

Study of the aberrations of the IMP heavy ion microbeam irradiation system

A high energy heavy ion microbeam irradiation system is constructed at the Institute of Modern Physics (IMP) of the Chinese Academy of Sciences (CAS). A quadrupole focusing system, in combination with a series of slits, has been designed here. The IMP microbeam system is described in detail. The intrinsic and parasitic aberrations associated with the magnets are simulated. The ion beam optics of this microbeam system is investigated systematically. Then the optimized initial beam parameters are given for high spatial resolution and high hitting rates.

Design of the IMP microbeam irradiation system for 100 MeV/u heavy ions

A state-of-the-art high energy heavy ion microbeam irradiation system is constructed at the Institute of Modern Physics of the Chinese Academy of Sciences. This microbeam system operates in both full current intensity mode and single ion mode. It delivers a predefined number of ions to pre-selected targets for research in biology and material science. The characteristic of this microbeam system is high energy and vertical irradiation. A quadrupole focusing system, in combination with a series of slits, has been designed to optimize the spatial resolution. A symmetrically achromatic system leads the beam downwards and serves simultaneously as an energy analyzer. A high gradient quadrupole triplet finally focuses a C6+ ion beam to 1 μm in the vacuum chamber within the energy range from 10 MeV/u to 100 MeV/u. In this paper, the IMP microbeam system is described in detail. A systematic investigation of the ion beam optics of this microbeam system is presented together with the associated aberrations. Comparison is made between the IMP microbeam system and the other existing systems to further discuss the performance of this microbeam. Then the optimized initial beam parameters are given for high resolution and high hitting efficiency. At last, the experiment platform is briefly introduced.

Heavy ion beam micromachining on LiNbO 3

In this work 3D micromachining of x-cut lithium niobate crystals was performed using the high energy heavy ion microbeam (HIM) at the Tandar Laboratory, Buenos Aires. The samples were machined using 35Cl beams at 70 MeV bombarding energy combined with wet etching with hydrofluoric acid solutions at room temperature. As the ion beam penetrates the sample, it induces lattice damage increasing dramatically the local etching rate of the material. This technique was applied to the fabrication of 3D waveguides with long control electrodes. The resulting structures indicate that well defined contours with nearly vertical sidewalls can be made. The results also show that with fluences of only 5 × 10 12 ions/cm 2, this technique is suitable for the fabrication of different shapes of LiNbO 3 control-waveguides that can be used in different optical devices and matched with the existing optical fibers.

Characteristics of focusing high-energy heavy ion microbeam system at the JAEA AVF cyclotron

Ion optical analysis was made for a new focusing high-energy heavy ion microbeam system connected to the AVF cyclotron ( K=110) at the accelerator facility, TIARA of JAEA Takasaki. The focusing performance of the microbeam system was estimated from both the calculation up to third-order term using TRANSPORT code and the measurement of beam resolution with the secondary electron imaging. As a result, a minimum beam size was evaluated at 0.56 and 0.62 μm in FWHM for the X and Y directions, respectively. The high-energy heavy ion microbeam system seemed to have been established as designed by the calculation with the TRANSPORT code, because it was confirmed that the calculation results was fairly reproduced by the measurement result.

Focusing high-energy heavy ion microbeam system at the JAEA AVF cyclotron

Performance of a focusing high-energy heavy ion microbeam system in TIARA facility of JAEA Takasaki was tested for the spatial resolution and for the hitting accuracy at a target. A 260 MeV 20Ne 7+ ion beam was successfully extracted from the JAEA AVF cyclotron ( K = 110) with the smallest momentum spread (Δ P/ P = δ) at present. The beam was focused by the microbeam lens system, and a spatial resolution of 260 MeV 20Ne 7+ microbeam was measured from a secondary electron image of a Cu grid which had sharp edges, and the hitting accuracy was estimated using single ion hitting onto a CR-39 film. From those two methods of measurement, both the spatial resolution and the hitting accuracy were evaluated at less than 1 μm.

Design of a focusing high-energy heavy ion microbeam system at the JAERI AVF cyclotron

For bio-medical applications of single-ion hit techniques such as radio-microsurgery, a focused high-energy heavy ion microbeam was designed and installed as a vertical beam line connected to the AVF cyclotron ( K=110) facility at JAERI Takasaki. By extracting a heavy ion microbeam into atmosphere, living cells can be irradiated with an accuracy smaller than typical cellular sizes. In addition, a high-speed automatic targeting and single-ion irradiation system was combined with a two-dimensional microbeam scanning system allowing more than 1000 targets per minute to be hit within a set field of view. Such high speeds targeting is necessary when examining statistically significant trends in cell irradiation studies within feasible time constraints. A real-time single-ion hit position detecting system was also designed to further increase the reliability of such irradiations.

Development of an automated single cell irradiation system combined with a high-energy heavy ion microbeam system

An automated single cell recognition and irradiation system has been developed at a high-energy heavy ion microbeam. The system has been installed on a vertical beam line of the JAERI Takasaki AVF-cyclotron accelerator to irradiate individual biological cells in an air environment with energies of more than 10 MeV/u by single ions. The system consists of high-precision stages, optical microscopes with CCD camera, a computer network and software packages to obtain positional data from a cluster of individual samples randomly placed on a holder before irradiation and to irradiate them with individual ions according to the obtained data. This paper will describe the new systems, and show results from irradiation experiments for CR-39.