Modification of ZnO films under high energy Xe-ion irradiations

ZnO films were deposited on (100) Si substrate by radio frequency magnetron sputtering. These films were irradiated at room temperature with 308 MeV Xe-ions to a fluence of 1.0 x 10(12), 1.0 x 10(13) or 1.0 x 10(14) Xe/cm(2). Then the samples were investigated using RBS, XRD, FESEM and PL analyses. The obtained experimental results showed that the deposited ZnO films were highly c-axis orientated and of high purity, 308 MeV Xe-ion irradiations could not change the c-axis oriented. The topography and PL properties of the ZnO films varied with increasing the Xe-ion irradiation fluence. For 1.0 x 10(13) or 1.0 x 10(14) Xe/cm(2) irradiated samples, surface cracks were observed. Furthermore, it was found that the 1.0 x 10(14) Xe/cm(2) irradiated sample exhibiting the strongest PL ability. The modification of structure and PL properties induced by 308 MeV Xe-ion irradiations were briefly discussed. (C) 2008 Elsevier B.V. All rights reserved.

DETERMINING THE DENSITY DEPENDENCE OF THE NUCLEAR SYMMETRY ENERGY USING HEAVY-ION REACTIONS

We review recent progress in the determination of the subsaturation density behavior of the nuclear symmetry energy from heavy-ion collisions as well as the theoretical progress in probing the high density behavior of the symmetry energy in heavy-ion reactions induced by high energy radioactive beams. We further discuss the implications of these results for the nuclear effective interactions and the neutron skin thickness of heavy nuclei.

Neutron-proton bremsstrahlung from intermediate energy heavy-ion reactions as a probe of the nuclear symmetry energy?

Hard photons from neutron-proton bremsstrahlung in intermediate energy heavy-ion reactions are examined as a potential probe of the nuclear symmetry energy within a transport model. Effects of the symmetry energy on the yields and spectra of hard photons are found to be generally smaller than those due to the currently existing uncertainties of both the in-medium nucleon-nucleon cross sections and the photon production probability in the elementary process pn -> pn gamma. Very interestingly, nevertheless, the ratio of hard photon spectra R-1/2(gamma) from two reactions using isotopes of the same element is not only approximately independent of these uncertainties but also quite sensitive to the symmetry energy. For the head-on reactions of Sn-132 + Sn-124 and Sn-112 + Sn-112 at E-beam/A = 50 MeV, for example, the R-1/2(gamma) displays a rise up to 15% when the symmetry energy is reduced by about 20% at rho = 1.3 rho(0) which is the maximum density reached in these reactions. (C) 2008 Elsevier B.V. All rights reserved.

Nuclear stopping and compression in heavy-ion collisions at intermediate energies

The nuclear stopping and the radial flow are investigated with an isospin-dependent quantum molecular dynamics (IQMD) model for Ni + Ni and Pb + Pb from 0.4 to and 1.2 GeV/u. The expansion velocity as well as the degree of nuclear stopping are higher in the heavier system at all energies. The ratio between the flow energy and the total available energy in center of mass of the colliding systems exhibits a positive correlation to the degree of nuclear stopping. The maximum density (rho(max)) achieved in the compression is comparable to the hydrodynamics prediction only if the non-zero collision time effect is taken into account in the later. Due to the partial transparency, the growing of the maximum density achieved in the central region of the fireball with the increase of beam energy becomes gradually flat in the 1 GeV/u energy regime. (C) 2008 Elsevier B.V. All rights reserved.

HIRFL today

HIRFL was upgraded from beginning 2000. Besides of researches on nuclear physics, atomic physics, irradiative material and biology, the cancer therapy by heavy ion and hadron physics are being developing. The injector system of SFC+SSC can provide all ions from proton to uranium with higher intensity. The Cooling Storage Ring (CSR) has accelerated beams successful. The ions C-12(6+), Ar-36(18+), Xe-129(27+) have been accelerated up 1000MeV/u, 235MeV/u with about 10(9)similar to 10(8) ions per spill respectively. The beam momentum dispersion was measured from 4x10(-3) to 2x10(-4) after cooling by the electron cooler or similar to 4x10(-4) after accelerated to 1000MeV/u without cooling. In order to improve the nuclear structure and heavy isotope research in SFC+SSC energy domain, A Wien filter was added in front of RIBLL and gas was filled in first section of RIBLL; a new spectrometry SHANS has being installed. Presently, there are two starting version experimental setups at CSR.

The influence of fractionation on cell survival and premature differentiation after carbon ion irradiation

Carbon ion radiotherapy/Fractionated irradiation/R-BE/Premature terminal differentiation. To investigate the influence of fractionation on cell survival and radiation induced premature differentiation as markers for early and late effects after X-rays and carbon irradiation. Normal human fibroblasts NHDF, AG1522B and WI-38 were irradiated With 250 kV X-rays, or 266 MeV/u, 195 MeV/u and I I MeV/u carbon ions. Cytotoxicity was measured by a clonogenic survival assay or by determination of the differentiation pattern. Experiments with high-energy carbon ions show that fractionation induced repair effects are similar to photon irradiation. The RBE10 values for clonogenic survival are 1.3 and 1.6 for irradiation in one or two fractions for NHDF cells and around 1.2 for AG1522B cells regardless of the fractionation scheme. The RBE for a doubling of post mitotic fibroblasts (PMF) in the population is I for both single and two fractionated irradiation of NHDF cells. Using I I MeV/u carbon ions, no repair effect can be seen in WI-38 cells. The RBE10 for clonogenic survival is 3.2 for single irradiation and 4.9 for two fractionated irradiations. The RBE for a doubling of PMF is 3.1 and 5.0 for single and two fractionated irradiations, respectively. For both cell lines the effects of high-energy carbon ions representing the irradiation of the skin and the normal tissue in the entrance channel are similar to the effects of X-rays. The fractionation effects are maintained. For the lower energy, which is representative for the irradiation of the tumor region. RBE is enhanced for clonogenic survival as well as for premature terminal differentiation. Fractionation effects are not detectable. Consequently, the therapeutic ratio is significantly enhanced by fractionated irradiation with carbon ions.

Vacuum window of intermediate energy heavy-ion microbeam irradiation facility

The beam must be extracted into the air through the vacuum window to irradiate the living cell. In the window design, the material and thickness must be chosen to compromise the beam spot size broadening and the window safety. The structure-static analysis on the window of different structures and materials is done with the finite element analysis method, and the deformation and the equivalent stress axe simulated. The safety of these candidates is investigated using the intensity theory. In addition, the small angle scattering and the transverse range of ions are simulated using SRIM code, including all the effects on the beam spot size broadening, such as the incident ion energy, the material and the thickness of the window and the air composing. At last, the appropriate vacuum windows are presented, including the structure, material and thickness.

Beam matching between SFC and SSC

The beam matching status between the two isochronous cyclotrons in the Heavy Ion Research Facility at the Lanzhou-Cooling Storage Ring (HIRFL-CSR) is described. Several methods which can be used to accomplish 100% matching are proposed. By comparing of them, the best method is determined. The advantage due to this method is discussed.

Investigation of PL properties of C-doped SiO2/Si samples after high energy Pb ion irradiation

Amorphous SiO2 thin films with about 400-500 nm in thickness were thermally grown on single crystalline silicon. These SiO2/Si samples were firstly implanted at room temperature (RT) with 100 keV carbon ions to 2.0 x 10(17),5.0 X 10(17) or 1.2 x 10(18) ions/cm(2), then irradiated at RT by 853 MeV Pb ions to 5.0 x 10(11), 1.0 X.10(12) 2.0 x 10(12) or 5.0 x 10(12) ions/cm(2), respectively. The variation of photoluminescence (PL) properties of these samples was analyzed at RT using a fluorescent spectroscopy. The obtained results showed that Pb-ion irradiations led to significant changes of the PL properties of the carbon ion implanted SiO2 films. For examples, 5.0 x 10(12) Pb-ions/cm(2) irradiation produced huge blue and green light-emitters in 2.0 x 10(17) C-ions/cm(2) implanted samples, which resulted in the appearance of two intense PL peaks at about 2.64 and 2.19 eV. For 5.0 x 10(17) carbon-ions/cm(2) implanted samples, 2.0 x 10(12) Pb-ions/cm(2) irradiation could induce the formation of a strong and wide violet band at about 2.90 eV, whereas 5.0 x 10(12) Pb-ionS/cm(2) irradiation could,create double peaks of light emissions at about 2.23 and 2.83 eV. There is no observable PL peak in the 1.2 x 10(18) carbon-ions/cm(2) implanted samples whether it was irradiated with Pb ions or not. All these results implied that special light emitters could be achieved by using proper ion implantation and irradiation conditions, and it will be very useful for the synthesis of new type Of SiO2-based light-emission materials.

Rotating wheel filter design and optimization for a uniform depth dose distribution in heavy ion therapy

Treatment planning of heavy-ion radiotherapy involves predictive calculation of not only the physical dose but also the biological dose in a patient body. The goal in designing beam-modulating devices for heavy ion therapy is to achieve uniform biological effects across the spread-out Bragg peak (SOBP). To achieve this, a mathematical model of Bragg peak movement is presented. The parameters of this model have been resolved with Monte Carlo method. And a rotating wheel filter is designed basing on the velocity of the Bragg peak movement.

Charge stripping accumulation of light heavy ions in HIRFL-CSR main ring

The charge stripping injection method has been adopted for the accumulation of light heavy ions in HIRFL-CSR. This method has some special requirements for the accelerating particles, and at the same time the structure of the injection orbit has to be changed. In this paper, the design of the orbit has been presented, as well as the calculation of the beam line matching. According to the result of commissioning, stripping injection can accumulate the beam to a higher current.

Advance in in-beam PET

Tumor radiotherapy was a promising modality and over 100 years. Beams of heavy-charged particles show high RBE advantages and become the optimum tool for tumors therapy. Newly, along with the development of accelerators, scintillators, micro-electronics and computers, the heavy ion tumor therapy has been recognized more and developed.

A high charge state all-permanent magnet ECR ion source for the IMP 320 kV HV platform

A 320 kV high voltage (HV) platform has been constructed at Institute of Modern Physics (IMP) to satisfy the increasing requirements of experimental studies in some heavy ion associated directions. A high charge state all-permanent magnet ECRIS-LAPECR2 has been designed and fabricated to provide intense multiple charge state ion beams (such as 1000 e mu A O6+, 16.7 e mu A Ar14+, 24 e mu A Xe27+, etc.) for the HV platform. LAPECR2 has a dimension of 0 650 mm x 560 mm. The powerful 3D magnetic confinement to the ECR plasma and the optimum designed magnetic field for the operation at 14.5 GHz makes it possible to obtain very good performances from this source. After a brief introduction of the ECRIS and accelerator development at IMP, the conceptual design of LAPECR2 source is presented. The first test results of this all-permanent magnet ECRIS are given in this paper.

Adaptive hormetic response of pre-exposure of mouse brain with low-dose C-12(6+) ion or Co-60 gamma-ray on growth hormone (GH) and body weight induced by subsequent high-dose irradiation

The brain of the Kun-Ming strain mice were irradiated with 0.05 Gy of C-12(6+) ion or Co-60 gamma-ray as the pre-exposure dose, and were then irradiated with 2 Gy of 12C6+ ion or Co-60 gamma-ray as challenging irradiation dose at 4 h after per-exposure. Body weight and serum growth hormone (GH) concentration were measured at 35th day after irradiation. The results showed that irradiation of mouse brain with 2 Gy of C-12(6+) ion or Co-60 gamma-ray significantly diminished mouse body weight and level of serum GH. The relative biological effectiveness values of a 2 Gy dose of C-12(6+) ion calculated with respect to Co-60 gamma-ray were 1.47 and 1.34 for body weight and serum GH concentration, respectively. Pre-exposure with a low-dose (0.05 Gy) of C-12(6+) ion or Co-60 gamma-ray significantly alleviated reductions of mouse body weight and level of serum GH induced by a subsequent high-dose (2 Gy) irradiation. The data suggested that low-dose ionizing irradiation can induce adaptive hormetic responses to the harmful effects of pituitary by subsequent high-dose exposure.

Observation of a pi h(9/2) circle times nu i(13/2) oblate band in Tl-188

Excited states in Tl-188 have been studied experimentally using the Gd-157(Cl-35;4n) reaction at a beam energy of 170 MeV. A rotational band built on the pi h(9/2) x nu i(13/2) configuration with oblate deformation has been established for Tl-188. Based on the structure systematics of the oblate pi h(9/2) x nu i(13/2) bands in the heavier odd-odd Tl nuclei, we have tentatively proposed spin values for the new band in Tl-188. The pi h(9/2) x nu i(13/2) oblate band in Tl-188 shows low-spin signature inversion, and it can be interpreted qualitatively by the two-quasiparticle plus rotor model including a J-dependent p-n residual interaction.