Nuclear Excitation by Single-Quantum Annihilation of Positrons

正电子单量子湮灭的核激发

• 批准号: 9505886
• 负责人: Jose Palathingal
• 金额: $ 13.73万
• 依托单位: University of Puerto Rico Mayaguez
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-11-01 至 1998-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9505886&HistoricalAwards=false
• 关键词: Nuclear; Excitation; Single; Quantum; Annihilation

9505886 Palathingal When the electromagnetic energy released as a positron gets annihilated in flight with a bound atomic electron in the Coulomb field of the nucleus, meets the energy criterion for resonance absorption, the excitation of the nucleus could be a possible result. There are major discrepancies between the results of calculations of this phenomenon and the available experimental data. The various experiments conducted so far have all suffered from common disadvantages. They utilized whole spectra of positrons derived from radioactive sources and thick targets. Metastable states of the nucleus were studied for periods of a few life times. The results were not accurate, and were prone to ambiguities for interpretation. In view of this, experiments have been called for that would use monoenergetic positrons and thin targets. Such studies will be undertaken utilizing the Dynamitron at Brookhaven and at ORELA at Oak Ridge National Lab. Short-lived states will be studied, that would make a continuous- running beam experiment possible. Thin targets of varied thickness will be used. Secondary effects that might contribute to the nuclear excitation alongside the single-quantum annihilation, proposed by differing theoretical models, would be explored. It is expected that data could be derived that would be accessible for unambiguous interpretation, and would lead to a clear understanding of the physical processes underlying the phenomenon. ***

9505886帕拉辛格当正电子释放的电磁能量在飞行中与束缚原子电子在原子核的库仑场中湮灭，满足共振吸收的能量标准时，可能是原子核激发的结果。对这一现象的计算结果与已有的实验数据有很大的出入。到目前为止进行的各种实验都有共同的缺点。他们利用了来自放射源和厚靶的正电子的全部光谱。在几个寿命周期内研究了原子核的亚稳态。结果并不准确，而且在解释上容易产生歧义。有鉴于此，人们呼吁进行使用单能正电子和薄靶的实验。这类研究将利用布鲁克海文的Dynamitron和橡树岭国家实验室的ORELA进行。短寿命状态将被研究，这将使连续运行的光束实验成为可能。将使用不同厚度的薄靶。不同的理论模型提出的可能有助于核激发和单量子湮灭的次要效应将被探索。预计可以得出可供进行明确解释的数据，并将导致对该现象背后的物理过程有一个清楚的了解。***