Nuclear Excitation by Single-Quantum Annihilation of Positrons

9505886 Palathingal当正电子释放的电磁能量在飞行中与原子核库仑场中的束缚原子电子湮灭时，满足共振吸收的能量标准，原子核的激发可能是一个可能的结果。 这种现象的计算结果与现有的实验数据之间存在很大的差异。 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整个光谱。 原子核的亚稳态被研究了几个生命周期。 结果并不准确，在解释时容易产生歧义。 有鉴于此，人们呼吁使用单能正电子和薄靶进行实验。 这些研究将利用布鲁克海文和橡树岭国家实验室的ORELA的Dynamitron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。 将探讨不同理论模型提出的可能有助于核激发和单量子湮灭的次级效应。 预计可以获得数据，以便作出明确的解释，并有助于清楚地了解这一现象背后的物理过程。 ***

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. ***