• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Nature >Laser spectroscopy of pionic helium atoms
【24h】

Laser spectroscopy of pionic helium atoms

机译：离子氦原子的激光光谱

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Charged pions(1) are the lightest and longest-lived mesons. Mesonic atoms are formed when an orbital electron in an atom is replaced by a negatively charged meson. Laser spectroscopy of these atoms should permit the mass and other properties of the meson to be determined with high precision and could place upper limits on exotic forces involving mesons (as has been done in other experiments on antiprotons(2-9)). Determining the mass of the pi(-) meson in particular could help to place direct experimental constraints on the mass of the muon antineutrino(10-13). However, laser excitations of mesonic atoms have not been previously achieved because of the small number of atoms that can be synthesized and their typically short (less than one picosecond) lifetimes against absorption of the mesons into the nuclei(1). Metastable pionic helium (pi He-4(+)) is a hypothetical(14-16) three-body atom composed of a helium-4 nucleus, an electron and a pi(-) occupying a Rydberg state of large principal (n approximate to 16) and orbital angular momentum (l approximate to n - 1) quantum numbers. The pi He-4(+) atom is predicted to have an anomalously long nanosecond-scale lifetime, which could allow laser spectroscopy to be carried out(17). Its atomic structure is unique owing to the absence of hyperfine interactions(18,19) between the spin-0 pi(-) and the He-4 nucleus. Here we synthesize pi He-4(+) in a superfluid-helium target and excite the transition (n, l) = (17, 16) -> (17, 15) of the pi(-)-occupied pi He-4(+) orbital at a near-infrared resonance frequency of 183,760 gigahertz. The laser initiates electromagnetic cascade processes that end with the nucleus absorbing the pi(-) and undergoing fission(20,21). The detection of emerging neutron, proton and deuteron fragments signals the laser-induced resonance in the atom, thereby confirming the presence of pi He-4(+). This work enables the use of the experimental techniques of quantum optics to study a meson.Long-lived pionic helium atoms (composed of a helium-4 nucleus, an electron and a negatively charged pion) are synthesized in a superfluid-helium target, as confirmed by laser spectroscopy involving the pion-occupied orbitals.
机译：带电的介子（1）是最轻，寿命最长的介子。当原子中的轨道电子被带负电的介子取代时，就会形成介子原子。这些原子的激光光谱法应该可以高精度确定介子的质量和其他性质，并且可以对涉及介子的外来力施加上限（就像在其他对质子的实验中所做的那样[2-9]）。确定pi（-）介子的质量尤其有助于将直接的实验约束施加到介子反中微子的质量上（10-13）。但是，由于可以合成的原子数量少，并且对介子被吸收到原子核中的寿命通常较短（少于1皮秒），因此以前尚未实现对中子原子的激光激发（1）。亚稳态离子氦（pi He-4（+））是假设的（14-16）三体原子，由氦4核，电子和pi（-）组成，占据大本德的Rydberg态（n近似）到16）和轨道角动量（l近似于n-1）量子数。预测pi He-4（+）原子具有异常长的纳秒级寿命，这可能允许进行激光光谱分析（17）。由于自旋-0 pi（-）和He-4核之间不存在超精细相互作用，因此其原子结构是独特的（18,19）。在这里，我们在超流体氦靶中合成pi He-4（+），并激发pi（-）占据的pi He-4的跃迁（n，l）=（17，16）->（17，15） （+）轨道处于183,760吉赫兹的近红外共振频率。激光启动电磁级联过程，最终使原子核吸收pi（-）并发生裂变（20,21）。新兴中子，质子和氘核碎片的检测信号在原子中的激光诱导共振，从而确认pi He-4（+）的存在。这项工作使得能够利用量子光学的实验技术来研究介子。在超流体氦靶中合成了长寿命的离子氦原子（由4个氦原子，一个电子和一个带负电荷的介子组成），激光光谱法证实了涉及介子占据的轨道。

著录项

  • 来源
    《Nature》 |2020年第7806期|37-41|共5页
  • 作者

  • 作者单位

    Max Planck Inst Quantum Opt Garching Germany;

    Max Planck Inst Quantum Opt Garching Germany|McKinsey & Co Inc Munich Germany;

    Max Planck Inst Quantum Opt Garching Germany|Swiss Fed Inst Technol IPA Zurich Switzerland;

    Paul Scherrer Inst Villigen Switzerland;

    CERN Geneva Switzerland|Wigner Res Ctr Phys Inst Particle & Nucl Phys Budapest Hungary;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号