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显示 2025年07月11日, 星期五 新的列表

总共 7 条目
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[1] arXiv:2507.07109 (交叉列表自 physics.ins-det) [中文pdf, pdf, html, 其他]
标题: VAMOS++磁谱仪原子电荷态和原子序数的分析,使用深度神经网络和部分标记事件
标题: Analysis of Atomic Charge State and Atomic Number for VAMOS++ Magnetic Spectrometer using Deep Neural Networks and Fractionally Labelled Events
M. Rejmund, A. Lemasson
主题: 仪器与探测器 (physics.ins-det) ; 核实验 (nucl-ex) ; 原子物理 (physics.atom-ph) ; 数据分析、统计与概率 (physics.data-an)

VAMOS++磁谱仪是一个多参数系统,将离子光学磁性元件与多探测器堆栈集成在一起。 磁性元件,连同跟踪和定时探测器以及轨迹重建方法,提供了对磁刚度、束流相互作用点与谱仪焦平面之间轨迹长度以及相关的速度和质荷比的分析。 分段电离室提供了分析原子电荷态和原子序数所需的能量测量。 然而,这种分析由于电离室入口窗的厚度变化和不均匀性以及其他探测器缺陷而受到固有局限性的严重影响。 传统上,这种细致而详细的分析非常繁琐,通常需要几个月的时间才能完成。 我们提出了一种新方法,利用深度神经网络,该网络仅在实验数据集上进行训练,该数据集仅包含最低且分辨最好的原子电荷态或原子序数的少量精确标记事件。 这种方法使网络能够自主且准确地对剩余事件进行分类。 该方法大大加快了高分辨率原子电荷态和原子序数谱的获取,将分析时间从几个月缩短到几小时。 至关重要的是,通过消除人为偏见,这种方法以前所未有的效率确保了标准化、最优和可重复的结果。

The VAMOS++ magnetic spectrometer is a multi-parametric system that integrates ion optical magnetic elements with a multi-detector stack. The magnetic elements, along with the tracking and timing detectors and the trajectory reconstruction method, provide the analysis of the magnetic rigidity, the trajectory length between the beam interaction point and the focal plane of the spectrometer, and the related velocity and mass-over-charge ratio. The segmented ionization chamber provides the energy measurements necessary to analyze the atomic charge state and atomic number. However, this analysis critically suffers from inherent limitations due to the variable thickness and non-uniformity of the entrance window of the ionization chamber and other detector imperfections. Conventionally, this meticulous, detailed analysis is exceptionally tedious, often requiring several months to complete. We present a novel method utilizing deep neural networks, trained on an experimental dataset with only a small fraction of precisely labeled events for the lowest and best-resolved atomic charge states or numbers. This innovative approach enables the networks to autonomously and accurately classify the remaining events. This method drastically accelerates the acquisition of high-resolution atomic charge state and atomic number spectra, reducing analysis time from months to mere hours. Crucially, by discarding human bias, this approach ensures standardized, optimal, and reproducible results with unprecedented efficiency.

[2] arXiv:2507.07127 (交叉列表自 physics.ins-det) [中文pdf, pdf, html, 其他]
标题: 快速定时中的振幅行走:双阈值的作用
标题: Amplitude Walk in Fast Timing: The Role of Dual Thresholds
Sebastian White, Alessio Boletti
评论: 准备提交至JINST。12页,9图
主题: 仪器与探测器 (physics.ins-det) ; 高能物理 - 实验 (hep-ex) ; 核实验 (nucl-ex)

为HL-LHC运行做准备,正在建造一些新的探测器系统,其物理对象的时间精度为$\leq50$皮秒。 这些时间戳将减少堆叠引起的背景水平,因为每束流的相互作用数量将达到100-200的数量级。 在本报告中我们注意到,这种高堆叠水平将需要一种新的方法来校准这些大型时间阵列(通常具有几个$\times10^5$通道),因为在常规数据获取中很难获得单一的t$_{0}$参考。 我们证明,通过增加第二个阈值时间来增强通常的时间ASIC数据(即阈值时间和幅度或过阈值时间),可以大大简化幅度行走的分析。 由于阈值处的斜率直接与幅度行走相关,第一天的行走校准通常可以有解析解。

In preparation for HL-LHC operation, a number of new detector systems are being constructed with timing precision on physics objects of $\leq50$ picoseconds. These time stamps will reduce the level of pileup induced backgrounds as the number of interactions per crossing will reach of order 100-200. In this report we note that this high pileup level will necessitate a new approach to calibration of these large timing arrays (typically with several $\times10^5$ channels) since a single t$_{0}$ reference is hard to come by in regular data taking. We demonstrate that enhancing the usual pair of timing ASIC data (ie threshold time and amplitude or time-over-threshold) with a 2nd threshold time greatly simplifies the analysis of amplitude walk. Since slope at threshold is directly relevant for amplitude walk, day-1 walk calibration can often have an analytical solution.

[3] arXiv:2507.07864 (交叉列表自 hep-ph) [中文pdf, pdf, html, 其他]
标题: 飞秒学研究$DN$和$\bar{D}N$系统
标题: Femtoscopy of $DN$ and $\bar{D}N$ systems
Mikel F. Barbat, Juan M. Torres-Rincon, Angels Ramos, Laura Tolos
评论: 13页,9图
主题: 高能物理 - 现象学 (hep-ph) ; 核实验 (nucl-ex) ; 核理论 (nucl-th)

ALICE@LHC和STAR@RHIC实验重建$D$介子的能力,使得在小系统和大系统中对开放底介子的费米尺度相关测量成为可能。 在这项工作中,我们基于应用到这些高能碰撞产生的系统的Koonin-Pratt形式,对$D$和$\bar{D}$介子与核子的相关函数进行了理论计算。 我们使用了一个有效拉格朗日量,用于描述底介子与重子之间的相互作用。 从单位化的实轴振幅中,我们提取了低能散射参数,并利用Lednický-Lyuboshitz近似计算相关函数。 此外,我们将TROY形式应用于获得耦合通道中的非壳上$T$-矩阵,并重构完整的波函数,将其纳入Koonin-Pratt公式中。 我们比较了这两种方法,并提供了不同相关对的预测,包括耦合通道的库仑相互作用和热权重的影响。 这些结果可以与ALICE和STAR合作组在质子-质子和重离子碰撞中的当前和未来实验数据进行对比。

The capability of the ALICE@LHC and STAR@RHIC experiments to reconstruct $D$ mesons has enabled femtoscopic correlation measurements of open-charm mesons in both small and large systems. In this work, we present a theoretical calculation of the correlation functions of $D$ and $\bar{D}$ mesons with nucleons, based on the Koonin-Pratt formalism applied to the systems produced in these high-energy collisions. We use an effective Lagrangian that models the interaction between charmed mesons and baryons. From the unitarized on-shell amplitudes, we extract the low-energy scattering parameters and compute the correlation functions using the Lednick\'y-Lyuboshitz approximation. Additionally, we apply the TROY formalism to obtain the off-shell $T$-matrix in coupled channels and reconstruct the full wave function, which we incorporate into the Koonin-Pratt formula. We compare these two approaches and provide predictions for different correlated pairs, including the effects of the Coulomb interaction and thermal weights for the coupled channels. These results can be tested against current and future experimental data from ALICE and STAR collaborations in both proton-proton and heavy-ion collisions.

替换提交 (展示 4 之 4 条目 )

[4] arXiv:2506.18832 (替换) [中文pdf, pdf, html, 其他]
标题: UrQMD 在高重子密度下金-金碰撞中高阶累积量的模拟
标题: UrQMD Simulations of Higher-order Cumulants in Au+Au Collisions at High Baryon Density
Xin Zhang, Yu Zhang, Xiaofeng Luo, Nu Xu
评论: 5页,6图,1表
主题: 核实验 (nucl-ex) ; 高能物理 - 现象学 (hep-ph)

高重数守恒量,如净重子数、净电荷和净奇异性,在重离子碰撞中对由QCD临界点(CP)引起的涨落敏感。 守恒荷的高阶矩的事例逐事例分析已被广泛用于实验中寻找CP,尤其是在RHIC-STAR实验中。 为了建立{\it 动态非临界基线},特别是在高重子密度区域,我们对金-金碰撞在3$\leq$$\sqrt{s_{NN}}$ $\leq$ 9.2 GeV碰撞中的质子多重性分布进行了系统分析。 从强子传输模型UrQMD的计算中提取了质子(因子)累积量在束流能量、中心度和快速度宽度方面的结果,最高到$4^{th}$阶。 此外,还讨论了初始体积涨落的影响。 这些结果在我们分析RHIC束流能量扫描(BES)数据时将非常重要,特别是对于固定靶数据和未来FAIR的CBM实验的实验数据。

High moments of conserved quantities such as net-baryon, net-electric charge, and net-strangeness in heavy-ion collisions are sensitive to fluctuations caused by the QCD critical point (CP). The event-by-event analysis of high moments of the conserved charges has been widely used in experiments to search for the CP, especially in the RHIC-STAR experiment. In order to establish a {\it dynamical non-critical base line}, especially at the high baryon density region, we have performed a systematic analysis of the proton multiplicity distributions from Au+Au collisions at 3 $\leq$ $\sqrt{s_{NN}}$ $\leq$ 9.2 GeV collisions. The results on beam energy, centrality and rapidity width dependence of proton (factorial) cumulants, up to the $4^{th}$ order, are extracted from the calculations of the hadronic transport model UrQMD. In addition, the effects of initial volume fluctuation is also discussed. These results will be important when we do physics analysis the RHIC beam energy scan (BES) data, especially for the fixed-target data and experimental data from future CBM experiment at FAIR.

[5] arXiv:2409.10260 (替换) [中文pdf, pdf, html, 其他]
标题: 硬剥离反应中的多重再散射效应 $\mathbf{^2\mbox{H}(p,2p)n}$
标题: Multiple rescattering effects in the hard knockout reaction $\mathbf{^2\mbox{H}(p,2p)n}$
A.B. Larionov
评论: 30页,9图,新增模型输入章节,其他小的更正,版本已被《欧洲物理杂志A》接受
主题: 核理论 (nucl-th) ; 高能物理 - 实验 (hep-ex) ; 高能物理 - 现象学 (hep-ph) ; 核实验 (nucl-ex)

质子与氘核的相互作用是最简单的核反应。 然而,它允许研究核介质效应的前驱现象,如初始态/最终态相互作用(ISI/FSI)。 在硬质质子剥离的情况下,ISI/FSI偏离“标准”值可能携带颜色透明性的信号。 在这方面,尽可能精确地定义“标准”是很重要的。 本工作继续在广义射线近似(GEA)框架内的先前研究。 重点是参与质子在观察中子上经历多次软散射的过程。 结果表明,正确处理出射质子轨迹偏离纵向方向的偏差,会导致具有两个出射质子软散射的部分振幅显著改变,以及具有入射和出射质子散射的非零振幅。 对多次散射的新处理在具有前向观察中子的动量范围内很重要。

The interaction of a proton with a deuteron is the simplest nuclear reaction. However, it allows the study of precursors of nuclear medium effects such as initial-state/final-state interactions (ISI/FSI). In case of hard proton knockout, the deviation of ISI/FSI from the 'standard' values may carry a signal of color transparency. In this regard, it is important to define the 'standard' as precisely as possible. This work continues previous studies within the framework of the Generalized Eikonal Approximation (GEA). The focus is on processes where the participating protons experience multiple soft rescattering on the spectator neutron. It is shown that correct treatment of deviations of the trajectories of outgoing protons from the longitudinal direction leads to a significant modification of partial amplitudes with soft rescattering of two outgoing protons and non-vanishing amplitudes with rescattering of incoming and outgoing protons. The new treatment of multiple rescattering is important in kinematics with a forward spectator neutron.

[6] arXiv:2504.12200 (替换) [中文pdf, pdf, html, 其他]
标题: 全局$Λ$极化在高重子密度的核碰撞中的研究
标题: Global $Λ$ polarization in heavy-ion collisions at high baryon density
Yu. B. Ivanov
评论: 12页,12图,小幅度修改,发表于中国物理C
期刊参考: 物理评论C 112 (2025) 1, 014902
主题: 核理论 (nucl-th) ; 高能物理 - 现象学 (hep-ph) ; 核实验 (nucl-ex)

基于三流体动力学(3FD)模型,计算了在3 $\leq\sqrt{s_{NN}}\leq$ 9 GeV的Au+Au碰撞中,整体$\Lambda$极化($P_\Lambda$),此时重子密度较高。 考虑了各种因素对$P_\Lambda$的贡献:热涡旋、介子场、热剪切和自旋霍尔效应。 此外,还考虑了来自高能共振的反馈。 将结果与现有数据进行了比较。 特别关注碰撞能量为$\sqrt{s_{NN}}=$ 3、3.2、3.5、3.9和4.5 GeV时,对$P_\Lambda$的能量、快速度和中心性依赖性进行了全面分析。 3 GeV的结果相当好地重现了相应的STAR数据。 而在 $\sqrt{s_{NN}}=$ 3.2、3.5、3.9 和 4.5 GeV 处的结果可以被视为对 STAR 固定目标 (STAR-FXT) 计划中近期测量结果的预测。 预测在$P_\Lambda$在$\sqrt{s_{NN}}\approx$3--3.9 GeV 处达到一个宽峰,其确切位置取决于观测的中间快速度范围的中心性和宽度。介子场、热剪切和自旋霍尔效应对$P_\Lambda$的贡献也进行了研究。

Based on the model of three-fluid dynamics (3FD), the global $\Lambda$ polarization ($P_\Lambda$) is calculated in Au+Au collisions at 3 $\leq\sqrt{s_{NN}}\leq$ 9 GeV, in which high baryon density is achieved. Various contributions to $P_\Lambda$ are considered: those from the thermal vorticity, meson field, thermal shear and spin-Hall effect. Feed-down from higher-lying resonances is also taken into account. The results are compared with available data. Special attention is payed to the collision energies of $\sqrt{s_{NN}}=$ 3, 3.2, 3.5, 3.9, and 4.5 GeV, for which a thorough scan of the energy, rapidity, and centrality dependence of $P_\Lambda$ is performed. The results for 3 GeV reasonably well reproduce the corresponding STAR data. While the results at $\sqrt{s_{NN}}=$ 3.2, 3.5, 3.9, and 4.5 GeV can be considered as predictions for results of measurements within the STAR fixed-target (STAR-FXT) programthat are expected in the nearest future. It is predicted that a broad maximum of $P_\Lambda$ is reached at $\sqrt{s_{NN}}\approx$ 3--3.9 GeV, exact position of which depends on the centrality and width of the midrapidity range of observation. Impact of the meson-field, thermal-shear and spin-Hall-effect contributions to $P_\Lambda$ is also studied.

[7] arXiv:2504.14909 (替换) [中文pdf, pdf, html, 其他]
标题: 基于固定磁场交替梯度结构的存储环设计,用于重离子束的随机电荷态转换内部靶装置
标题: Design of a Storage Ring based on a Fixed Field Alternating Gradient Configuration with an Internal Target for Heavy-Ion Beams with Stochastic Charge State Conversions
Yoshihiro Ishi, Tomonori Uesugi, Yoshiharu Mori, Katsuhisa Nishio
评论: 11页,15图
主题: 加速器物理 (physics.acc-ph) ; 核实验 (nucl-ex)

在重离子加速器的一般使用中,加速的束流打在靶上后被送入束流终止器。 为了更有效地利用束流,在所谓的能量回收内部靶(ERIT)框架下提出了通过靶后的束流回收方法。 在ERIT系统中,通过使用射频腔回收靶中损失的能量,使靶在循环束流中受到照射。 到目前为止,这种系统仅在质子束中实现过。 在这里,首次展示了用于重离子束的ERIT系统。 一个具有挑战性的问题是不同原子电荷的全部离子的循环。 一个离子在通过靶后具有平衡电荷态分布的概率,与初始电荷态无关。 这种随机电荷态转换(SCSC)现象会导致束流发射度迅速增长。 为了解决这个问题,我们开发了一种方法,基于缩放固定场交替梯度(FFA)晶格结构,在环中目标位置匹配不同电荷态束流的闭合轨道和贝特atron函数。 我们提出了这种FFA环的设计,并通过完整的6D束流跟踪模拟表明,即使存在SCSC,横向发射度增长也可以得到有效抑制。

In the general use of a heavy-ion accelerator, an accelerated beam impinged on a target is spoiled into a beam dump. To make more efficient use of the beam, recycling of the beam passed through the target is proposed in the framework of the so-called energy recovery internal target (ERIT). In the ERIT system, the target is irradiated inside the circulating beam by recovering the energy lost in the target using rf cavities. So far, such a system has been realized only for proton beams. Here, the ERIT system for heavy-ion beam is demonstrated for the first time. A challenging issue is the circulation of all ions with different atomic charge. An ion has a probability of equilibrated charge state distribution after passing through the target, independent of the initial charge state. This phenomenon of stochastic charge state conversion (SCSC) causes rapid beam-emittance growth. To solve this problem, we developed a method to match the closed orbits and betatron functions of the beams in different charge states at the target location in a ring based on a scaling fixed field alternating gradient (FFA) lattice structure. We present the design of such an FFA ring and show, through full 6D beam tracking simulations, that transverse emittance growth can be effectively suppressed even in the presence of SCSC.

总共 7 条目
显示最多 2000 每页条目: 较少 | 更多 | 所有
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