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OPTIMIZATION OF SECTOR GEOMETRY OF A COMPACT CYCLOTRON BY RANDOM SEARCH METHOD
No full textThis paper describes the procedure of optimizing the
sector geometry of the magnet to obtain the desired
isochronous field. The hill shape of the magnet is
described in terms of a small number of parameters which
are iteratively determined by random search technique
geared to minimize the frequency error. 3D magnetic field
data and results of equilibrium orbit code are used as
input for the iterative optimization process.IMP;Chinese Academy of Science
DESIGN STUDY OF MAGNETIC CHANNEL AT NIRS-AVF930
No full textIn the NIRS-AVF930 cyclotron, a current magnetic
channel has been used for ten years, and the flow of
cooling water gradually decreases. Therefore, the high
energy operation such as 70 MeV proton became recently
difficult. As the design specification of this magnetic
channel is very severe, the flow velocity of cooling water
is very fast as 5.4 m/sec. The condition of the current
magnetic channel and the design consideration of a new
one will be presented.IMP;Chinese Academy of Science
ACCELERATION ABOVE THE COULOMB BARRIER – COMPLETION OF THE ISAC-II PROJECT AT TRIUMF
No full textThe ISAC-II project at TRIUMF was proposed to boost
the final energy of the radioactive ion beams of the
TRIUMF ISAC facility above the Coulomb barrier. The
nominal goal of 6.5MeV/u for ions with A/q=6 was
recently achieved. The ISAC-II project consists of 40MV
of installed heavy ion superconducting linac to broaden
the energy reach and a charge state booster to broaden the
mass reach. The project and commissioning is describedIMP;Chinese Academy of Science
DESIGN STUDY OF K100 SEPARATED SECTOR CYCLOTRON FOR ISOL
No full textStarting from April 2010, KoRIA was launched in
Republic of Korea; the main objects of this project are
fundamental and applied researches, e.g. production of
radioisotope beam for the basic science research, nuclear
structure, material and life sciences and medical isotope
production. A K=100 separated sector cyclotron will be
used as a driving accelerator for ISOL, and it will provide
70-100 MeV, ~1 mA of proton beam and 35-50 MeV,
~1mA of deuteron ion beam, the SSC cyclotron will be
injected by 8 MeV proton beam from 2 sector focused
cyclotrons. In this paper we will describe briefly about the
conceptual design of the cyclotron including the design of
injector cyclotron, separated sector cyclotron.IMP;Chinese Academy of Science
BEAM DIAGNOSTICS FOR RIBF IN RIKEN
No full textThe Radioisotope Beam Factory (RIBF) at RIEKN
started its operation in the end of 2006 with the aim of
conducting systematic studies on the physics of radioactive
isotopes. The simultaneous use of five accelerators
in series necessitates precise measurement of beam properties
such as beam intensities, beam energies, and bunch
lengths. Hence, a beam diagnostic system plays an important
role in the efficient and stable operation of RIBF. In
this paper, we provide a brief summary of the conventional
beam monitors used during the daily operations of RIBF.
In addition, new non-destructive monitors that have been
developed bearing in mind forthcoming intensity upgrades
are described.IMP;Chinese Academy of Science
Observation of an Antimatter Hypernucleus
No full textNuclear collisions recreate conditions in the universe microseconds after the Big Bang. Only a very small fraction of the emitted fragments are light nuclei, but these states are of fundamental interest. We report the observation of antihypertritons-comprising an antiproton, an antineutron, and an antilambda hyperon-produced by colliding gold nuclei at high energy. Our analysis yields 70 +/- 17 antihypertritons (3/Lambda(H) over bar) and 157 +/- 30 hypertritons (H-3(Lambda)). The measured yields of H-3(Lambda) (3/Lambda(H) over bar) and He-3 ((3)(He) over bar) are similar, suggesting an equilibrium in coordinate and momentum space populations of up, down, and strange quarks and antiquarks, unlike the pattern observed at lower collision energies. The production and properties of antinuclei, and of nuclei containing strange quarks, have implications spanning nuclear and particle physics, astrophysics, and cosmology
Isobaric yield ratios and the symmetry energy in heavy-ion reactions near the Fermi energy
No full textThe relative isobaric yields of fragments produced in a series of heavy-ion-induced multifragmentation reactions have been analyzed in the framework of a modified Fisher model, primarily to determine the ratio of the symmetry energy coefficient to the temperature, a(sym)/T, as a function of fragment mass A. The extracted values increase from 5 to similar to 16 as A increases from 9 to 37. These values have been compared to the results of calculations using the antisymmetrized molecular dynamics (AMD) model together with the statistical decay code GEMINI. The calculated ratios are in good agreement with those extracted from the experiment. In contrast, the values extracted from the ratios of the primary isobars from the AMD model calculation are similar to 4 to 5 and show little variation with A. This observation indicates that the value of the symmetry energy coefficient derived from final fragment observables may be significantly different than the actual value at the time of fragment formation. The experimentally observed pairing effect is also studied within the same simulations. The Coulomb coefficient is also discussed
Long-distant contribution and chi(c1) radiative decays to light vector meson
No full textThe discrepancy between the PQCD calculation and the CLEO data for chi (c1)->gamma V (V=rho (0), omega, phi) stimulates our interest in exploring other mechanisms of chi (c1) decay. In this work, we apply an important non-perturbative QCD effect, i.e., the hadronic loop mechanism, to study chi (c1)->gamma V radiative decay. Our numerical result shows that the theoretical results including the hadronic loop contribution and the PQCD calculation of chi (c1)->gamma V are consistent with the corresponding CLEO data of chi (c1)->gamma V. We expect further experimental measurement of chi (c1)->gamma V, which will be helpful to test the hadronic loop effect on chi (c1) decay
Effect of substrate and annealing on the structural and optical properties of ZnO:Al films
No full textZnO:Al thin films with c-axis preferred orientation were deposited on glass and Si substrates using RF magnetron sputtering technique. The effect of substrate on the structural and optical properties of ZnO:Al films were investigated. The results showed a strong blue peak from glass-substrate ZnO:Al film whose intensity became weak when deposited on Si substrate. However, the full width at half maxima (FWHM) of the Si-substrate ZnO:Al (0 0 2) peaks decreased evidently and the grain size increased. Finally, we discussed the influence of annealing temperature on the structural and optical properties of Si-substrate ZnO:Al films. After annealing, the crystal quality of Si-substrate ZnO:Al thin films was markedly improved and the intensity of blue peak (similar to 445 nm) increased noticeably. This observation may indicate that the visible emission properties of the ZnO:Al films are dependent more on the film crystallinity than on the film stoichiometry. Crown Copyright (C) 2009 Published by Elsevier Ltd. All rights reserved
94MeV Xe离子辐照引起的薄膜硅光学带隙变化研究；Modification of Optical Bandgap of Thin Silicon Films Induced by 94 MeV Xe Ion Irradiation
No full text室温下,用94MeV的Xe离子辐照纳米晶和非晶硅薄膜以及单晶硅样品,辐照量分别为1.0×1011,1.0×1012和1.0×1013ions/cm2。所有样品均在室温下用UV/VIS/NIR光谱仪进行检测分析。通过对比研究了纳米晶、非晶、单晶硅样品的光学带隙随Xe离子辐照量的变化。结果表明,不同结构的硅材料中Xe离子辐照引起的光学带隙变化规律差异显著:随着Xe离子辐照量的增加,单晶硅的光学带隙基本不变,非晶硅薄膜的光学带隙由初始的约1.78eV逐渐减小到约1.54eV,而纳米晶硅薄膜的光学带隙则由初始的约1.50eV快速增大至约1.81eV,然后再减小至约1.67eV。对硅材料结构影响辐照效应的机理进行了初步探讨