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A study of complementary reactions: Single-proton knockout and single-proton pickup.

机译:互补反应的研究:单质子敲除和单质子拾取。

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摘要

Knockout reactions using fast, exotic beams in inverse kinematics are an established tool for probing the ground state wave function of the incident projectile and studying the spectroscopy of the projectile-like knockout residue. In a knockout reaction, the removal of a nucleon from the projectile populates single-hole states in the residue. Measured partial cross sections and longitudinal momentum distributions to final states of the residue, as tagged by the detection of gamma rays emitted in-flight and correlated event-by-event to the residue, are used to quantify the single-particle composition of the projectile wave function.;Recently, pickup reactions using fast, exotic beams in inverse kinematics have emerged as a complementary tool to single-nucleon knockout reactions by populating single-particle states in the residue. Recent analyeses have shown qualitative agreement between theoretical and measured strengths and population patterns to final states in the residue. This agreement suggests that pickup reactions can provide similar information about the ground state wavefunction of the projectile and the spectroscopy of the residue.;Two experiments were run at the NSCL that show the power and highlight the differences of these two complementary reactions. The one-proton knockout experiment 9Be(54Ti,53Sc+ gamma)X at 72 MeV/u was performed to probe the single-proton configurations of the N = 32 nuclei 54Ti and 53Sc and test the validity of the nuclear shell model and valance space in this interesting neutron-rich mass region. An unexpectedly large spectro-scopic strength to excited states was observed. The magnitude of strength observed was incompatible with shell model calculations using the f p model space only, and was therefore attributed to the knockout of deeply-bound sd-shell protons outside the calculation valance space. This interpretation was substantiated through a comparison to previous experimental work, the analogous 50Ti(d,3He)49Sc transfer reaction and the two-proton knockout reaction 9Be(54Ti, 52Ca + gamma)X, and through the comparison of the inclusive momentum distribution to a theoretical distribution that assumes sd-shell contributions. The results highlight the need for proton cross-shell interactions for the sdpf valance space.;Three different one-proton pickup reactions on proton-rich nuclei centered around 50Fe were studied on two different targets, 9Be and 12C: 9Be(48Cr, 49Mn+ )X, 9Be(49Mn,50Fe+ gamma)X, 9Be(50Fe,51Co+ gamma)X, 12 C(48Cr,49Mn+ gamma)X, 12C( 49Mn,50Fe+ gamma)X, and 12C( 50Fe,51Co + gamma)X. The investigation of these reactions, through the comparison of the experimentally measured and theoretically predicted partial cross sections and population pattern to final states in the pickup residue, was done with the goal of further developing pickup reactions as a spectroscopic tool. The theoretical partial cross sections were calculated using shell-model spectroscopic factors and single-particle cross sections calculated in a post-form Coupled Channels Born Approximation (CCBA ) framework assuming twobody final states. The reaction mechanism was further probed by measured longitudinal momentum distributions whose comparison to calculated distributions that assume the two-body character of the final reaction product tests the direct nature of the reaction processes, and by the use of the two different targets, through which the importance of including only a subset of target final states can be judged. We report the results for the first fast beam, inverse-kinematics, proton pickup reactions in the f p-shell, and the first proton pickup reactions from a 12C target.
机译:在反向运动学中使用快速,奇异的射束进行敲除反应是探查入射弹丸的基态波函数并研究类似弹丸的敲除残留物的光谱学的成熟工具。在敲除反应中,从子弹中除去核子会在残基中形成单孔态。通过检测飞行中发射的伽玛射线并与事件相关的事件与残渣相关联,测得的残渣最终状态的部分横截面和纵向动量分布用于量化弹丸的单颗粒组成最近,逆运动学中使用快速,奇特的光束进行拾取反应已成为通过填充残基中的单粒子状态作为单核子敲除反应的补充工具。最近的分析表明,理论强度和实测强度以及种群模式与残留物中的最终状态之间存在定性一致性。该协议表明,拾取反应可以提供有关弹丸基态波函数和残留物光谱的相似信息。在NSCL上进行的两个实验显示了功率,并突出了这两个互补反应的区别。进行了72 MeV / u的单质子敲除实验9Be(54Ti,53Sc +γ)X,以探测N = 32核54Ti和53Sc的单质子构型,并测试了核壳模型和价空间的有效性这个有趣的中子富集区域。观察到激发态的光谱强度出乎意料地大。观察到的强度大小仅与使用f p模型空间的壳模型计算不兼容,因此归因于在计算价空间外敲除深层结合的sd-壳质子。通过与先前的实验工作,类似的50Ti(d,3He)49Sc转移反应和双质子敲除反应9Be(54Ti,52Ca +γ)X进行比较以及通过将包含的动量分布与假设有sd-shell贡献的理论分布。结果强调了sdpf价态空间需要质子跨壳相互作用。;在9Be和12C两个不同目标上研究了以50Fe为中心的富质子核的三个不同的单质子拾取反应:9Be(48Cr,49Mn +) X,9Be(49Mn,50Fe +γ)X,9Be(50Fe,51Co +γ)X,12 C(48Cr,49Mn +γ)X,12C(49Mn,50Fe +γ)X和12C(50Fe,51Co +γ)X。通过将实验测量和理论上预测的部分横截面和种群格局与拾取残留物中的最终状态进行比较,对这些反应进行了研究,目的是进一步开发作为光谱学工具的拾取反应。使用壳模型光谱因子计算理论局部截面,并在假设两体最终状态的情况下,在后形式耦合通道出生近似(CCBA)框架中计算出单颗粒截面。通过测得的纵向动量分布进一步探讨了反应机理,将其与假设最终反应产物的二体特征的计算分布进行比较,从而测试了反应过程的直接性质,并通过使用两个不同的靶标,通过可以判断仅包括目标最终状态的子集的重要性。我们报告了第一个快速束,逆运动学,f p壳中的质子拾取反应以及来自12C目标的第一个质子拾取反应的结果。

著录项

  • 作者

    McDaniel, Sean Michael.;

  • 作者单位

    Michigan State University.;

  • 授予单位 Michigan State University.;
  • 学科 Physics Nuclear.
  • 学位 Ph.D.
  • 年度 2011
  • 页码 240 p.
  • 总页数 240
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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