Development of an intermediate energy heavy-ion micro-beam irradiation system

The micro-beam irradiation system, which focuses the beam down to micron order and precisely delivers a predefined number of ions to a predefined spot of micron order, is a powerful tool for radio-biology, radio-biomedicine and micromachining. The Institute of Modern Physics of Chinese Academy of Sciences is developing a heavy-ion microbeam irradiation system up to intermediate energy. Based on the intermediate and low energy beam provided by Heavy Ion Research Facility of Lanzhou, the micro-beam system takes the form of the magnetic focusing. The heavy-ion beam is conducted to the basement by a symmetrical achromatic system consisting of two vertical bending magnets and a quadrupole in between. Then a beam spot of micron order is formed by a magnetic triplet quadrupole of very high gradient. The sample can be irradiated either in vacuum or in the air. This system will be the first opening platform capable of providing heavy ion micro-beam, ranging from low (10MeV/u) to intermediate energy (100MeV/u), for irradiation experiment with positioning and counting accuracy. Target material may be biology cell, tissue or other non-biological materials. It will be a help for unveiling the essence of heavy-ion interaction with matter and also a new means for exploring the application of heavy-ion irradiation.

Injection system design for a hadron therapy synchrotron

A synchrotron is designed for tumour therapy with C6+ ions or proton. Its injector is a cyclotron, which delivers C5+ or H-2(+) ions to the synchrotron. After comparing the methods of the single-turn injection, the multi-turn injection and the stripping injection, this paper chooses the stripping injection method. In addition, the concept design of the injection system is presented, in which the synchrotron lattice is optimized.

beta-delayed neutron decay of N-21

The beta-delayed neutron and gamma spectra of neutron-rich nucleus N-21 using beta-gamma and beta-n coincidence measurements were presented in this paper. Thirteen new neutron groups ranging from 0.28 MeV to 4.98 MeV and with a total branching ratio 88.7 +/- 4.2% were observed. One gamma transition among the excited states of O-21 and foury transitions among the excited states of O-20 were identified in the beta decay chain of N-21. The ungated half-life of 83.8 +/- 2.1 ms was also determined for N-21.

Efficiency calibration of neutron detector array for beta decay of exotic nuclei

The research of the in-beam efficiency calibration of Neutron Detector Array of Peking University using N-17 and C-16 beams was introduced in this paper. The efficiency of neutron wall and ball are comparable to the foreign similar devices and neutrons can be detected from low to high energies in high efficiency.

Isospin effect of projectile fragment yields

Isospin asymmetry is very important in the nuclear equation of state (EOS), isotope yield from the projectile fragments can give information of the reaction process. In this paper projectile fragment yields are measured in the collision Ar-36,Ar-40 + Ni-64 at incident energy 50 MeV/u with different isospin asymmetry project Ar-36,Ar-40, data analysis, particle identification and event selection are described. Isotope yields are compared in these two reactions, and axe also compared with the empirical parametrization of fragmentation cross-section calculated by EPAX.

Study on charge equilibration time of highly charged ions in carbon foils

Charge state distribution of 0.8MeV/u uranium ions after transmission through a thin carbon foil has been studied. It is observed that the charge state distribution is equilibrated after the uranium ions have passed through a 15 mu g/cm(2) carbon foil. The equilibrated average charge state is 33.72 and the charge equilibration time of uranium ions in carbon foil is less than 5.4fs.

Early effects of carbon-ion irradiation on murine lymphocytes and thymocytes

To estimate the biological risks from space radiation encountered by cosmonauts in outer space, the effects from whole-body exposure to carbon ions or X-rays irradiations at 0, 0.39, 0.55 and 1 Gy at a dose rate of 0.2 Gy/min were investigated in BALB/c mice. The relative thymus and spleen weights were measured at 24 h after exposure, and the cell cycle distribution and percentage of apoptosis of thymocytes and spleen and peripheral blood lymphocytes were determined by flow cytometry. The data showed that exposure to carbon ions delayed cell progression of peripheral blood lymphocytes in S-phase, and delayed thymocytes and spleen lymphocytes in G(0)/G(1)-phase. Apoptosis of thymocytes and peripheral blood lymphocytes induced by carbon ions increased more rapidly with dose than was the case for X-rays. There were some differences between the relative weight loss of the thymus and the spleen with increasing dose of either carbon ions or X-rays. The results obtained provide evidence of dose- and organ-specific differences induced by carbon ions compared to X-rays, with increased apoptosis in peripheral blood lymphocytes and thymocytes, but not spleen lymphocytes. Our data may suggest that further work would be of interest to estimate risk of changes in immune function during particle radiation exposures in space travel. (c) 2007 COSPAR

Angular dispersion and deflection function for heavy ion elastic scattering

The differential cross sections for elastic scattering products of F-17 on Pb-208 have been measured. The angular dispersion plots of ln(d sigma/d theta) versus theta(2) are obtained from the angular distribution of the elastic scattering differential cross sections. Systematical analysis on the angular dispersion for the available experimental data indicates that there is an angular dispersion turning angle at forward angular range within the grazing angle. This turning angle can be clarified as nuclear rainbow in classical deflection function. The exotic behaviour of the nuclear rainbow angle offers a new probe to investigate the halo and skin phenomena.

Measurement of total reaction cross section for neutron-rich nucleus Li-11 on Si-28 target at medium energy

The neutron-rich nucleus Li-11 is separated by the radioactive ion beam line RIBLL at HIRFL from the breakup of 50MeV/u C-13 on Be target. The total reaction cross sections for Li-11 at energies range from 25 to 45MeV/u on Si target have been measured by using the transmission method. The experimental data at high and low energies can be fitted well by Glauber model using two Gauss density distribution. The matter radius of Li-11 was also deduced.

Design of synchrotron for hadron therapy

According to the operation and development of radiation therapy in the world, in order to further promote the radiation therapy of tumour in China, a design of a special synchrotron with two super-periodicity for hadron therapy is presented, including lattice, injection system, RF acceleration and slow extraction of the third order resonance. The synchrotron accelerates the proton beam to 250MeV and the carbon beam to 4000MeV/u.

Antioxidant N-acetylcysteine attenuates the acute liver injury caused by X-ray in mice

The aim of this study was to evaluate the protective effects of different doses and administration modes of N-acetylcysteine (NAC) against X-ray-induced liver damage in mice. Kun-Ming mice were divided into four groups, each composed of six animals: two control groups and two NAC-treated groups. An acute study was carried out to determine alterations in lipid peroxidation (determined by measuring malondiadehyde (MDA) level), glutathione (GSH) content and superoxide dismutase (SOD) activity (assayed by colorimetric method), and DNA damage (characterized by DNA-single strand break using with comet assay) as well as cell apoptosis (measured by flow cytometry) at 12 h after irradiation. The results showed that there were dose-related decreases in MDA level, DNA damage and cell apoptosis, and dose-dependent increases in GSH content and SOD activity in all NAC-treated groups compared to control groups, indicating that pre-treatment or post-treatment with NAC significantly attenuates the acute liver damage caused by X-ray. In addition, significant positive correlations were observed between MDA level and DNA damage or cell apoptosis, implying that lipid peroxidation plays a major role in X-ray-induced liver injury. The data suggest that NAC exerts its radioprotective effect by counteracting accumulated reactive oxygen species in the liver through its properties as a direct antioxidant and a GSH precursor, when administered before or after X-ray irradiation.

The electron emission yield induced by the interaction of highly charged argon ions with silicon surface

The electron emission yield of the interaction of highly charged argon ions with silicon surface is reported. The experiment was done at the Atomic Physics Research Platform on the Electron Cyclotron Resonance (ECR) Ion Source of the National Laboratory HIRFL (Heavy Ion Research Facility in Lanzhou). In the experiment, the potential energy and kinetic energy was selected by varying the projectile charge states and extracting voltage, thus the contributions of the projectile potential energy deposition and electronic energy loss in the solid are extensively investigated. The results show that, the two main factors leading to surface electron emission, namely the potential energy deposition and the electronic energy loss, are both approximately proportional to the electron emission yield per ion.

Test experiments of gamma-ray linear polarization using a Clover detector

We have investigated the performance of a EXOGAM-Segmented-Clover with 16 segments as a Compton polarimeter to measure the linear polarization of gamma rays. The polarization sensitivity of the Clover detector has been measured at the energy of 1332keV through the coincidence measurements of cascade gamma-rays from Co-60. Experimental values were in good accord with our expectation.We have investigated the performance of a EXOGAM-Segmented-Clover with 16 segments as a Compton polarimeter to measure the linear polarization of gamma rays. The polarization sensitivity of the Clover detector has been measured at the energy of 1332keV through the coincidence measurements of cascade gamma-rays from Co-60. Experimental values were in good accord with our expectation.

First results of SECRAL at 18GHz for intense beam production of highly charged ions

A Superconducting ECR ion source with Advanced design in Lanzhou (SECRAL) was successfully built to produce intense beams of highly charged ions for Heavy Ion Research Facility in Lanzhou (HIRFL). The ion source has been optimized to be operated at 28GHz for its maximum performance. The superconducting magnet confinement configuration of the ion source consists of three axial solenoid coils and six sextupole coils with a cold iron structure as field booster and clamping. For 28GHz operation, the magnet assembly can produce peak mirror fields on axis 3.6T at injection, 2.2T at extraction and a radial sextupole field of 2.0T at plasma chamber wall. A unique feature of SECRAL is that the three axial solenoid coils are located inside of the sextupole bore in order to reduce the interaction forces between the sextupole coils and the solenoid coils. During the ongoing commissioning phase at 18GHz with a stainless steel chamber, tests with various gases and some metals have been conducted with microwave power less than 3.2kW and it turned out the performance is very promising. Some record ion beam intensities have been produced, for instance, 810e mu A of O7+, 505e mu A of Xe20+, 306e mu A of Xe27+, 21e mu A of Xe34+, 2.4e mu A of Xe38+ and so on. To reach better results for highly charged ion beams, further modifications such as an aluminium chamber with better cooling, higher microwave power and a movable extraction system will be done, and also emittance measurements are being prepared.

Commissioning test of LAPECR2 source on the 320kV HV platform

The high charge state all permanent Electron Cyclotron Resonance Ion Source (ECRIS) LAPECR2 (Lanzhou All Permanent magnet ECR ion source No.2) has been successfully put on the 320kV HV platform at IMP and also has been connected with the successive LEBT system. This source is the largest and heaviest all permanent magnet ECRIS in the world. The maximum mirror field is 1.28T (without iron plug) and the effective plasma chamber volume is as large as circle divide 67mm x 255mm. It was designed to be operated at 14.5GHz and aimed to produce medium charge state and high charge state gaseous and also metallic ion beams. The source has already successfully delivered some intense gaseous ion beams to successive experimental terminals. This paper will give a brief overview of the basic features of this permanent magnet ECRIS. Then commissioning results of this source on the platform, the design of the extraction system together with the successive LEBT system will be presented.