共查询到20条相似文献,搜索用时 31 毫秒
1.
《IEEE transactions on nuclear science》2006,53(2):500-505
The trigger system of the ATLAS experiment at the LHC aims at a high selectivity in order to keep the full physics potential while reducing the 40 MHz initial event rate imposed by the LHC bunch crossing down to /spl sim/100 Hz, as required by the data acquisition system. Algorithms working in the final stage of the trigger environment (Event Filter) are implemented to run both in a "wrapped" mode (reconstructing tracks in the entire Muon Spectrometer) and in a "seeded" mode (according to a dedicated strategy that performs pattern recognition only in regions of the detector where trigger hypotheses have been produced at earlier stages). The working principles of the offline muon reconstruction and identification algorithms (MOORE and MuId) implemented and used in the framework of the Event Filter are discussed in this paper. The reconstruction performance of these algorithms is presented for both modes in terms of efficiency, momentum resolution, rejection power and execution times on several samples of simulated single muon events, also taking into account the high background environment expected for ATLAS. 相似文献
2.
EicC(the highly polarized electronion collider in China)是由中国科学院近代物理研究所提出的极化电子-离子对撞机装置。在电子-质子对撞模式中,EicC的电子环(eRing)内有256个电子束团,质子环(pRing)内有448个质子束团。由于两个环内的束团数不同,当束流中的束团出现缺失时,束团缺失带来的影响会通过束束相互作用传递给多个电子与质子束团,进而可能会使束流不稳定。为研究束团缺失对束流稳定性的影响,本文使用束束相互作用模拟程序AthenaGPU进行了自洽的模拟研究。模拟结果显示,缺失电子束团不会使束流出现相干不稳定,但缺失一定数目的质子束团时会引起偶极或四极不稳定,且使对撞亮度迅速衰减。调节名义工作点后可使束流避开共振区,不再出现偶极或四极不稳定。 相似文献
3.
In the LHC/ALICE experiments, photon production will be studied with the PHOS electromagnetic calorimeter. A pre-shower detector has been proposed with a passive converter sandwiched by two MICROMEGAS detectors covering PHOS module to improve the photon identification, with respect to the set-up with only CPV in front of PHOS. The PPSD will considerably improve the rejection of neutral hadrons and the identification of overlapping showers. 相似文献
4.
《IEEE transactions on nuclear science》2005,52(4):874-878
The PHENIX detector at RHIC has been designed to study hadronic and leptonic signatures of the Quark Gluon Plasma in heavy ion collisions and spin dependent structure functions in polarized proton collisions. The baseline detector measures muons in two muon spectrometers located forward and backward of mid-rapidity, and measures hadrons, electrons, and photons in two central spectrometer arms, each of which covers 90$^circ$ in azimuth and 0.35 units of rapidity. Further progress requires extending rapidity coverage for hadronic and electromagnetic signatures by upgrading the functionality of the PHENIX muon spectrometers to include photon and jet measurement capabilities. Tungsten calorimeters with silicon pixel readout and fine transverse and longitudinal segmentation are proposed to attain this goal. The use of such a design provides the highest density and finest granularity possible in a calorimeter. 相似文献
5.
A. P. Elokhin R. S. Khlopotin D. F. Rau A. N. Tkachev A. D. Rumyantsev V. M. Berkovich 《Atomic Energy》2009,107(6):387-399
A dosimetric system for determining the rate at which gas-aerosol radioactive impurities are discharged during a radiological
emergency is examined. It is shown that the optimal system for evaluating the rate of discharge is one that consists of flow-through
and closed (hermetic) ionization chambers. The addition of a xenon spectrometer to the system makes it possible to determine
the partial rate of emission of individual radionuclides and the total emission rate of all nuclides. The optimal parameters
of the ionization chambers making it possible to record the emission rate of a radioactive impurity with air flow rate to
12 m/sec against background dose rate up to 200 Sv/h are found. 相似文献
6.
7.
Joerg Konheiser Carsten Brachem Marcus Seidl 《Journal of Nuclear Science and Technology》2017,54(2):188-195
This work shows the impact of potential displacements of the fuel assembly positions in the reactor core on the signal values of the ex-core instrumentation of a pressurized water reactor in order to understand in detail the impact on the calibration factor of ex-core detectors. This was done with a range of Monte Carlo calculations that simulated the detailed geometrical effect by stepwise changing of the positions of fuel assemblies for selected, conservative scenarios. First, criticality calculations were carried out for the chosen core configurations, and corresponding surface sources on the core barrel were determined. In these calculations, the distances were varied between the fuel assemblies which were in the line of sight of the ex-core instrumentation. A maximal change of the fluxes on the surface of the core barrel of 4%/mm could be calculated under conservative assumptions for the combination of displaced fuel assemblies. In addition, a dependence of this effect as a function of cycle burn-up was analyzed. In a second step, transport calculations for the ionization chambers were performed using the surface sources. An increase of the reaction rate at the chambers of up to 3%/mm has been calculated. 相似文献
8.
Jan C. Baggesen 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2009,267(16):2662-2666
When a lead beam is collimated in the CERN LHC some of the ions fragment in the collimators causing problems downstream. For design purposes the fragmentation probability needs to be assessed. At LHC energies (γ?3000; the Lorentz-factor γ is the total energy of an ion in units of its rest energy) electromagnetic dissociation dominates the fragmentation in medium to heavy target materials. Due to the extended range of the interaction at high energies, atomic screening affects the dissociation in the LHC collimators. We determine the magnitude of the reduction in cross section relative to the unscreened case for various collimator materials and find a significant effect for tungsten, the heaviest candidate planned for use. 相似文献
9.
《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》1988,34(4):512-517
Characteristics of two ionization chambers have been studied and the chambers utilized for 226Ra/222Rn measurements for more than ten years. The results obtained show that coating of internal surfaces with a pure and thin Ag-layer enhances the background of ionization chambers in spite of some improvements at the early stages of operation. In addition to previously known parameters influencing the accuracy in routine measurements, new correction factors are suggested. 226Ra impurities in the body of ionization chambers are found to act not only as a permanent, but also as a temperature-dependent source of background. Earlier accuracies of 226Ra/222Rn measurements have been considerably improved by assuring long-term mechanical and thermal stability of the ionization chambers. 相似文献
10.
11.
快循环同步加速器(RCS)是中国散裂中子源(CSNS)的重要组成部分。负氢粒子束经直线加速器加速至80 MeV,剥离成质子束注入至RCS环并加速累积至1.6 GeV引出打靶。束流通过安装在RCS环的壁电流探测器(WCM)感应得到束流的强度信息,环高频与环主二极磁铁的失配会导致束流的实际振荡偏离理论预测。本文通过对WCM的数据进行分析得到了纵向工作点、束流的实际振荡频率、束团的电荷量、束团的形状变化等信息,方便了加速器的调束,并对参数测量中的测量误差进行了分析。 相似文献
12.
R. Moore 《Atomic Energy》2002,93(6):930-933
The Run II Tevatron series at the Enrico Fermi Laboratory was started in March 2001. Numerous improvements to the accelerator complex were made in order to ensure operation of the proton–antiproton Tevatron accelerator with peak luminosity (2–4)·1032 cm–2·sec–1 and to obtain a total luminosity above 5 fb–1 before the LHC physical program starts. The current status of the Run II series and the technical requirements which must be met to achieve the stated goals are described. 相似文献
13.
JIN Sunjun WANG Kun WANG Zhipeng FAN Yaodong YANG Xiaoyuan ZHANG Jian HE Pengbo SHEN Guosheng DAI Tianyuan LI Qiang 《原子能科学技术》1959,54(9):1722-1728
The absorbed-dose to water of heavy ion beam is a fundamental quantity for heavy ion therapy. It is necessary to perform the relevant work with in-direct measurement prior to the study of the reproduction for the absorbed-dose to water of heavy ion beam. The absorbed-dose to water of a carbon ion beam, whose incident energy was 400 MeV/u and spread-out Bragg peak was 6 cm, was studied with conventional ionization method. The correction factors of polarity and ion recombination for the ionization chambers were evaluated with the incident heavy ion beam. The uncertainty components for the measurement of the absorbed-dose to water of heavy ion beam are significantly larger than that of the 60Co γ radiation, in terms of the corrections for the polarity and ion recombination of the ionization chambers. The absorbed-dose to water of heavy ion beam deduced from different ionization chambers is consistent within the acceptance of uncertainty. Based on the measurement with ionization chambers, it is crucial to conduct more intensive research activities of radiation dosimetry including the absolute measurement with calorimetric facility, with the purpose of further optimizing the uncertainty in the measurement for the absorbed-dose to water of heavy ion beam. 相似文献
14.
15.
重离子束水吸收剂量是开展重离子束治疗最基本的物理量。在开展重离子束水吸收剂量的量值复现研究前,需用间接测量的方法开展相关工作以熟悉实验条件。本文用传统电离法开展了能量400 MeV/u、具有6 cm展宽Bragg峰的碳离子束的水吸收剂量测量研究,并评价了重离子束条件下的相关电离室的极化、离子复合修正因子。在电离室的极化和离子复合修正项方面,重离子束水吸收剂量测量的相关不确定度分量显著大于60Co γ辐射水吸收剂量的相关值。用不同电离室测量重离子束水吸收剂量的结果在不确定度允许的范围内符合。以电离室测量为基础,开展更深入的包括量热法绝对测量在内的辐射剂量学研究,对进一步优化重离子束水吸收剂量测量的不确定度至关重要。 相似文献
16.
束团长度是中国散裂中子源(CSNS)快循环同步加速器(RCS)束流动力学的关键参数,通过对束团长度的研究,可了解RCS的机器性能并进一步指导机器优化研究。本文对RCS 100 kW时的束团长度进行精确测量,100 kW引出时的束团长度为105 ns。RCS 500 kW时束团长度可能超过无损引出允许值,需压缩束团长度。理论上提高腔压可压缩束团长度,本文模拟研究500 kW时束团长度随腔压曲线的变化规律,模拟结果表明提高加速后半阶段的腔压可压缩束团长度,给出了500 kW时无束流损失引出的腔压曲线。基于100 kW束流条件实验验证了通过提高加速后半阶段腔压来压缩束团长度的有效性和可行性,实验测量结果与模拟结果一致。因此,提高加速后半阶段腔压是500 kW时无损引出束流的有效方法。 相似文献
17.
Rameika R. Cox B. Jenkins C. M. Judd D. J. Hale G. Mazur P. O. Murphy C. T. Turkot F. Wagoner D. E. Conetti S. Haire M. Lebrun P. Leroy C. Ryan T. Turnbull L. Gearhart R. A. Shen C. 《IEEE transactions on nuclear science》1984,31(1):60-63
A hodoscope has been constructed from 100 ?m diameter wires and brass tubes (1.2 × 0.7 cm2 cross section) filled with a mixture of argon, ethane and ethyl alchohol. It has been tested in the saturated avalanche mode in an SCG1-C electromagnetic shower detector to determine its properties for the measurement of the position and size of electromagnetic showers. Two of these tube hodoscopes were positioned 3.5 radiation lengths deep in the detector and the profiles of 1-25 GeV electromagnetic showers were measured. Simultaneous measurements were performed using a plane of twenty, 0.5 cm wide scintillation counters positioned immediately behind the gas tube hodoscope. In addition the transition between saturated avalanche and limited streamer modes has been measured for the tube hodoscopes. 相似文献
18.
19.