Institutional Repository of Institute of Modern Physics, CAS
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DISTURBANCE EFFECTS CAUSED BY RF POWER LEAKING OUT FROM CAVITIES IN THE PSI RINGCYCLOTRON
No full textWhile commissioning the PSI high intensity proton
beam facility after the shutdown 2010, direct and indirect
phenomena of interaction occurred between the RF power
leaking out from the cavities and the electrostatic septa at
the injection and extraction region in the Ringcyclotron.
As an indirect influence RF fields outside the cavities
generate plasma clouds in the peripheral area of magnet
poles. Accelerated plasma ions sputtered metallic atoms
from the vacuum chamber wall, which then covered the
insulator surface with an electrically conductive layer.
The septum therefore had to be replaced. Directly, RF
power dissipated from the 150 MHz flattop cavity was
redirected by a beam stopper in such a way, that a linear
correlation between the RF pick up signal monitored at
the extraction septum (EEC) and the leakage current
across the septum insulator could be observed. As an
instant mending action the beam stopper, which is not
permanently used, has been removed. The long term
attempt to minimize these disturbing effects will be an
asymmetrical setting of the hydraulic cavity tuning
system and an effective RF grounding of build in
componentsIMP;Chinese Academy of Science
HIGH POWER RF SYSTEMS AND RESONATORS FOR SECTOR CYCLOTRONS
No full textThe Proscan cyclotron is routinely operated for medical
cancer treatment and the Injector II and Ring-Cyclotron are
routinely used for acceleration of a high intensity proton
beam. In the framework of the high intensity upgrade, it is
planned to replace two existing 150MHz resonators of the
Injector II cyclotron by two new 50MHz resonators. The
first prototype resonator has been manufactured by SDMS
and first vacuum and RF-measurements have been carried
out. Tuners, coupler and pickups have been mounted and
high power RF tests are in progress on a teststand. A new
building for the RF-installation has been constructed and is
ready to house the power amplifiers.IMP;Chinese Academy of Science
兰州冷却储存实验环高可靠性低电平控制系统
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">In order to get an RF electric field which has stable amplitude, phase and frequency, the radio frequency low level control system for HIRFL-CSRe has been constructed at Institute of Modern Physics. To ensure the control of stability, reliability and real-time, analogous modules are mainly used. At the same time, digital module is used to coordinate the modules and compensate for non-linear error of some function modules. The system is consisted of three subsystems-phase stabilizing system amplitude control system and frequency tuning system, and mainly uses the technology as PID, RF phase detect, DSP, FPGA and so on. Low-level control system of HIRFL-CSRe has been tested through a long-term stability experiments and high-power experiments, the control accuracy meeting the amplitude accuracy +or-1% and phase control accuracy +or-3deg, frequency tuning accuracy +or-5deg of the technical requirements.</span
重离子诱变技术选育碱性蛋白酶高产菌株；The Selection for High-yield Alkaline Protease Producing Strain by Heavy-ion Irradiation
No full text从采集的土壤样品中分离筛选出一株碱性蛋白酶产生菌G-41,经16S rRNA分子鉴定为芽孢杆菌属菌株。该菌株在发酵培养基中能产生较高产量的胞外碱性蛋白酶(1.7×104U/mL)。以G-41为出发菌株,对其进行重离子辐照诱变处理,获得突变株G-41-68,将该突变株再次经重离子诱变,从大量突变株中筛选出碱性蛋白酶高产菌株15Gy-54,其酶活力达到6.22×104U/mL。与出发菌株相比较,突变株G-41-68和15Gy-54的酶活力分别提高了1.58倍和2.65倍。对突变株15Gy-54的发酵条件进行了优化研究,结果表明,该菌株的碱性蛋白酶活力得到进一步提高,达到7.18×104U/mL,其最适发酵条件为:培养基(g/100mL)为胰蛋白胨1、酵母膏0.5、乳糖5、Na2HPO4·12H2O0.4、KH2PO40.03、Na2CO30.1、MgSO40.0481(4×10-3mol/L)、pH8.0,培养温度41℃,振荡培养时间42-48h。实验结果表明,重离子辐照诱变技术是一种非常有效的微生物诱变育种新技术
低速~(40)Ar~(17+)离子入射金属Be表面发射的近红外光谱线和X射线谱；Infrared Light and X-ray Emissions of ~(40)Ar~(17+) Impacting on Be Surface ；
No full text用速度不同的(动能EK=272和357keV,速度v=1.14×106和1.72×106m/s)的高电荷态离子40Ar17+分别入射金属Be表面,同时测量这种相互作用过程中产生的近红外光谱线和X射线谱。实验结果表明,在低速范围内(速度小于玻尔速度vBohr=2.19×106m/s),速度较小的40Ar17+离子在到达金属的表面临界距离Rc到进入表面(2—3原子层)的进程中,形成了较多的高激发态Ar原子,其退激辐射较强的光谱线,进而验证了经典过垒模型
DIRECT MASS MEASUREMENTS OF EXOTIC NUCLEI IN STORAGE RINGS
No full textMass measurements of exotic nuclei is a fast, developing field which is essential for basic nuclear physics and a wide range of applications. The method of storage ring mass spectrometry has many advantages: (1) a large amount of nuclides can be simultaneously measured; (2) very short-lived (T-1/2 greater than or similar to 50 mu s) and very rare species (yields down to single ions) can be accessed; (3) nuclides in several atomic charge states can be investigated, (4) half-life measurements can be performed with time-resolved mass spectrometry. In this contribution we concentrate on some recent achievements and future perspectives of the storage ring mass spectrometry
Tetrahedral instability in superheavy nuclei
No full textThe present study reports the possibility that the tetrahedral symmetry may manifest itself in superheavy elements through the nortaxial octupole Y-32 deformation. The calculations of nortaxial octupole bands are performed by using the Reflection Asymmetric Shell Model for some transfermium nuclei where the spectroscopic data are available, and a very good agreement between theory and experiment has been achieved
Radiosensitivity to high energy iron ions is influenced by heterozygosity for Atm, Rad9 and Brca1
No full textLoss of function of DNA repair genes has been implicated in the development of many types of cancer. In the last several years, heterozygosity leading to haploinsufficiency for proteins involved in DNA repair was shown to play a role in genomic instability and carcinogenesis after DNA damage is induced, for example by ionizing radiation. Since the effect of heterozygosity for one gene is relatively small, we hypothesize that predisposition to cancer could be a result of the additive effect of heterozygosity for two or more genes critical to pathways that control DNA damage signaling, repair or apoptosis. We investigated the role of heterozygosity for Aim, Rad9 and Brad on cell oncogenic transformation and cell survival induced by 1 GeV/n Fe-56 ions. Our results show that cells heterozygous for both Aim and Rad9 or A tin and Brca1 have high survival rates and are more sensitive to transformation by high energy iron ions when compared with wild-type controls or cells haploinsufficient for only one of these proteins. Since mutations or polymorphisms for similar genes exist in a small percentage of the human population, we have identified a radiosensitive sub-population. This finding has several implications. First, the existence of a radiosensitive sub-population may distort the shape of the dose response relationship. Second, it would not be ethical to put exceptionally radiosensitive individuals into a setting where they may potentially be exposed to substantial doses of radiation. (C) 2010 COSPAR. Published by Elsevier Ltd. All rights reserved
Microscopic examination of NpNn dominance in the evolution of nuclear structure
No full textThe proton-neutron interaction in determining the evolution of nuclear structure has been studied by using the Brillouin-Wigner perturbation expansion. The particle-hole and particle-particle p-n interactions are unifiedly described in the theory. The obtained formulas of level energies and excitation energies scaled in the small- and large-NpNn limits can well explain the linearity of the extracted proton-neutron interaction energies and the attenuation of the 2(1)(+) excitation energies against the valence nucleon product NpNn for five mass regions from A = 100-200