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本工作研究了自由核子和冷原子核物质的动力学产生的海夸克和胶子分布。在动力学部分子模型中,所有的海夸克和胶子纯粹来自DGLAP方程描述的QCD涨落过程,而较少的固有海夸克成分忽略不计。在$Q_0^2\sim 0.1$ GeV2标度,选择最大熵方法估计的三价夸克分布作为非微扰输入。使用了在低$Q^2$ (本工作研究了自由核子和冷原子核物质的动力学产生的海夸克和胶子分布。在动力学部分子模型中,所有的海夸克和胶子纯粹来自DGLAP方程描述的QCD涨落过程,而较少的固有海夸克成分忽略不计。在$Q_0^2\sim 0.1$ GeV2标度,选择最大熵方法估计的三价夸克分布作为非微扰输入。使用了在低$Q^2$ ($<1$ GeV2)下饱和的跑动强耦合常数。关于原子核效应,考虑了核子变胖和部分子-部分子重组增强的影响。核子及冷核物质的动力学部分子分布均符合实验观测。应用预言的原子核部分子分布抽取得到部分子在穿过冷核物质时的能量损失。 相似文献
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目前高能核乳胶实验利用的束流,主要是加速器产生的能量达几GeV/N至200GEV/N的重原子核。例如:前苏联杜布纳联合原子核研究所(JINR)重离子加速器上产生的3.7GEV/N~(16)O,美国布鲁克海 相似文献
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现代科学已经证实,原子核是由核子(质子和中子)组成的,而核子可能是由夸克和胶子组成的.为了研究核子、夸克和胶子的性质,美国于90年代起建造两台大型加速器装置,它们分别是连续电子束加速器装置和相对论性重离子对撞机. 相似文献
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对每核子200GeV的S+Pb中心碰撞中产生的∧粒子的横向极化度消失的现象作了细致研究,用相对论核-核碰撞的Monte-Carlo事件产生器--LUCIAE产生了相应能量下的S+Pb中心碰撞事例,定量分析了消除∧粒子横向极化度的各种因素,研究了反应中的二次散射、二次产生以及∑,E等超子衰变产生的粒子在总的实验测量的∧总数中的比例,确定了由这些∧粒子造成的退极化度对总的∧极化度的影响,模拟和计算结果表明,以上3个效应强烈地影响了∧的横向极化度,但不可能使终态假定为强子气时∧粒子的横向极化度完全消失,为了解释∧极化度近于零的实验结果,可能需要在相对论重核碰撞中引进∧粒子产生的新的机制,包括存在形成夸克-胶子等离子体(QGP)的弱效应。 相似文献
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基于相对论流体力学,指出了新近报道的首次实测的纯光子谱虽然具有线性,但并不意味着极端相对论性原子核碰撞后的系统在整体上达到了热平衡. 运用动态相变机制的计算结果可以预言,若强子化相变是一级相变,当碰撞能量高于200GeV/u时,纯光子谱将呈现凹形曲线,可以用作诊断夸克-胶子等离子体是否存在的信号. 相似文献
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对每核子200GeV的S+Pb中心碰撞中产生的Λ粒子的横向极化度消失的现象作了细致研究.用相对论核–核碰撞的Monte-Carlo事例产生器——LUCIAE产生了相应能量下的S+Pb中心碰撞事例,定量地分析了消除Λ粒子横向极化度的各种因素,研究了反应中的二次散射、二次产生以及Σ,Ξ等超子衰变产生的Λ粒子在总的实验测量到的Λ总数中的比例,确定了由这些Λ粒子造成的退极化度对总的Λ极化度的影响.模拟和计算结果表明,以上3个效应强烈地影响了Λ的横向极化度,但不可能使终态假定为强子气时Λ粒子的横向极化度完全消失.为了解释Λ极化度近于零的实验结果,可能需要在相对论重核碰撞中引进Λ粒子产生的新的机制,包括存在形成夸克–胶子等离子体(QGP)的弱效应. 相似文献
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金原子核组成的高能束流的对撞在微观上再现了宇宙大爆炸时的高热、高密度物质状态。3年来,布鲁克海文实验室一直用相对论重离子对撞机(RelativisticHeavyIonCollider,RHIC)在极端相对论能区做高达每核子100GeV的重核对撞实验。这种非同寻常的新加速器在探寻物质新的高能状态,继续探究几个世纪以来的老问题,试图从根本上了解自然和物质的起源。RHIC实验的早期结果揭示了高温和高密度状态下核物质的奥秘;在高温和高密度状态下,核子和介子已不复存在,核物质只以夸克和胶子的形态存在。 相似文献
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WEI Tao YANG Guo-Jun HE Xiao-Zhong LONG Ji-Dong ZHANG Zhuo WANG Shao-Heng YANG Zhen LI Wei-Feng LI Hong YANG Xing-Lin WANG Min-Hong SHI Jin-Shui ZHANG Kai-Zhi DENG Jian-Jun ZHANG Lin-Wen 《中国物理C(英文版)》2010,34(11):1754-1756
A proton radiography system is an accelerator-based facility.Especially high-energy proton radiography is an advanced hydrodynamics diagnostic tool,and it is the trend of radiography technology development.In this paper,a 20 GeV accelerator complex scenario,including a 35 MeV linac,a 1 GeV booster and a 20 GeV main ring,is introduced.The overall physics design of the proton radiography accelerator is described,including the design of each part of the accelerator and the choice of the main parameters. 相似文献
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It is emphasized that a coming accelerator complex should be designed by wide application of beam manipulation. On the basis of this opinion, conceptual designs of two kinds of accelerator complexes of a 30 GeV/nucleon uranium-ion collider and of an intense 30 GeV proton accelerator are studied independently of each other. Moreover, it is shown from these designs that an accelerator complex with accelerator parameters common to both is possibly designed with the help of good beam manuipulation if mutual concessions of beam parameters of heavy ions and of intense protons are accepted. The optimum accelerator complex consists of at least three synchrotrons and three dc rings. The expected beam performance is 450 MeV/nucleon and 30 GeV/nucleon for uranium ions as a typical example of heavy ions, and 150 A below 2.7 GeV and 10 A below 30 GeV for intense protons. 相似文献
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Shi-Lun Guo Yu-Lan Wang R. Brandt P. Vater B. A. Kulakov M. I. Krivopustov V. S. Butsev V. Bradnova Benhao Sa Yuming Zheng 《Radiation measurements》1995,25(1-4):261-264
Fast neutrons produced in 44 and 22 GeV 12C+Cu interactions have been recorded and analysed with a CR-39 detector stack. The irradiation of the CR-39 stack to fast neutrons was carried out at the accelerator Synchrophasotron, Joint Institute for Nuclear Research, Dubna, Russia. Areal and volume densities of tracks induced by fast neutrons in the CR-39 at different positions and for different etching time have been measured. The neutron production ratio of 44 GeV to 22 GeV 12C+Cu interactions has been obtained, which is 2.17 ± 0.30 by areal track density, or 2. 12±0.33 by step etch technique, or 2.03±0.34 by volume track density measurement. These results confirm that the production rate at 44 GeV 12C+Cu interactions is more than theoretical estimation. 相似文献
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Shoji Nagamiya 《Hyperfine Interactions》2001,138(1-4):25-33
From JFY01, which started on April 1, 2001, a new accelerator project to provide high-intensity proton beams proceeded into
a construction phase. This project is conducted under a cooperation of two institutions, KEK and JAERI. The accelerator complex
will provide 1 MW proton beams at 3 GeV and 0.75 MW beams at 50 GeV. The project will be completed within six years. In this
article I will describe (a) the project itself, (b) sciences to be pursued at this new accelerator complex and (c) the present
status and future plans of the project.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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Subramanyam Swaminathan 《Synchrotron Radiation News》2013,26(4):16-24
Construction work on the new MAX IV synchrotron light facility in northeastern Lund, Sweden, began on May 18, 2011. The MAX IV accelerator system will consist of three parts: one 3 GeV injector linac (also used for the production of short X-ray pulses) and two storage rings operated at 1.5 GeV and 3 GeV, respectively. The two-ring concept will allow the production of synchrotron radiation from optimized undulators within a broad spectral region. The 3 GeV ring has an emittance between 0.2 and 0.4 nm rad, depending on the ID configuration, and the emittance of the 1.5 GeV ring is 5 nm rad. 相似文献
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《Zeitschrift für Physik A Hadrons and Nuclei》1997,359(1):65-73
The production of π 0 and η mesons has been investigated in the system 12C+12C at 0.8A GeV, 1.0A GeV, and 2.0A GeV using the TAPS photon detector. The production cross sections and transverse-momentum distributions measured around midrapidity extend the existing systematics of neutral-meson production to light systems and the highest energy available at the GSI accelerator facility. At all beam energies scaling of the differential production cross section with the transverse mass of the emitted meson is observed. In addition π0 production has been studied in the mass-asymmetric systems 12C+197Au and 197Au+12C at 0.8A GeV. 相似文献
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A. A. Baldin A. I. Berlev M. Paraipan S. I. Tyutyunnikov 《Physics of Particles and Nuclei Letters》2017,14(1):132-138
A comparative analysis and optimization of energy efficiency for proton and ion beams in ADS systems is performed via simulation using a GEANT4 code with account for energy consumption for different accelerator types. It is demonstrated that for light nuclei, beginning from 7Li, with energies above 1 GeV/nucleon, ion beams are considerably (several times) more efficient than the 1–3 GeV proton beam. The possibility of achieving energy deposition equivalent to 1 GeV protons in a quasi-infinite uranium target with higher efficiency (and twice as small accelerator size) in the case of acceleration of light ions is substantiated. 相似文献
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J. Ball M. Beddo Y. Bedfer J. Bystrický P.-A. Chamouard M. Combet Ph. Demierre J.-M. Fontaine G. Gaillard D. Grosnick R. Hess R. Kunne F. Lehar A. de Lesquen D. Lopiano D. Rapin J.-L. Sans H.M. Spinka 《The European Physical Journal C - Particles and Fields》1999,10(3):409-413
The pp elastic scattering analyzing power was measured in small energy steps in the vicinity of the accelerator depolarizing resonance
at 2.202 GeV. A vertically polarized proton beam was extracted from SATURNE II at energies above the resonance and passed
through different copper degraders. The beam was focused on the beam line polarimeter CH target. Its halo was removed by four powerful magnets. Measurements at degraded energies were complemented by data obtained
with the directly extracted polarized beam outside the resonance region. Analyzing power results at fixed laboratory angles
are compared with existing data in the region under discussion, with polynomial fits from 1.6 to 3.5 GeV, and with phase shift
analysis predictions.
Received: 24 March 1999 / Published online: 12 August 1999 相似文献
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M. Dehn K. Aulenbacher R. Heine H. -J. Kreidel U. Ludwig-Mertin A. Jankowiak 《The European physical journal. Special topics》2011,198(1):19-47
The demand for CW electron beam energies of more than 1?GeV led to the decision of constructing a worldwide unique accelerator – the Harmonic Double-Sided Microtron (HDSM). This machine nearly doubles the beam energy of the Mainz Microtron cascade from up to 855?MeV to now 1.6?GeV to extend the experimental capabilities for nuclear and particle physics experiments to higher excitation energies. For the recent decade the construction and commissioning of the HDSM at the Institut für Kernphysik has been the major task of the accelerator department. 相似文献