How to access QED at a supercritical Coulomb field
How to access QED at a supercritical Coulomb field
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DOI：
10.1103/physrevd.102.076005
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发表时间：
2020-08
影响因子：
5
通讯作者：
R. V. Popov;V. Shabaev;D. Telnov;I. Tupitsyn;I. A. Maltsev;Y. Kozhedub;A. I. Bondarev;N. V. Kozin-N. V.-Kozin-2126411581;X. Ma;G. Plunien;T. Stöhlker;D. Tumakov;V. Zaytsev
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文献类型：
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作者：
R. V. Popov;V. Shabaev;D. Telnov;I. Tupitsyn;I. A. Maltsev;Y. Kozhedub;A. I. Bondarev;N. V. Kozin-N. V.-Kozin-2126411581;X. Ma;G. Plunien;T. Stöhlker;D. Tumakov;V. Zaytsev
在两个裸核的慢碰撞中，总电荷数大于临界值Zcr = 173，初始中性真空可以自发衰变为带电真空和两个正电子。探测到正电子的自发辐射将是这一基本现象的直接证据。然而，自发辐射通常被动态正电子辐射所掩盖，动态正电子辐射是由碰撞核产生的强时间依赖性电场引起的。在我们最近的论文[I。A. Maltsev等人，物理修订信函123，113401（2019）PRLTAO 0031 -900710.1103/PhysRevLett.123.113401]已经表明，可以通过测量给定一组核轨迹的对产生概率来观察自发对产生。在本论文中，我们通过探索我们感兴趣的过程的其他方面，大大推进了这项研究。我们计算了正电子能谱，发现这些能谱可以给出从亚临界到超临界区域跃迁的清晰信号。研究发现，聚焦于正电子谱的一部分，这部分正电子谱占了自发产生的正电子可以贡献的能量区域，使我们能够得到更强有力的证据，证明向超临界模式的转变，这使得它在碰撞中非常明显，例如，两个铀核的碰撞。还考虑了将这一研究扩展到裸核与中性原子碰撞的可能性。本文计算了裸U核与中性U、Cm原子碰撞形成的准分子最低能态空位的几率。这种概率的相对较大的值使得这种碰撞适合于观察真空衰变。
In slow collisions of two bare nuclei with the total charge number larger than the critical value, Zcr≈173, the initially neutral vacuum can spontaneously decay into the charged vacuum and two positrons. Detection of the spontaneous emission of positrons would be the direct evidence of this fundamental phenomenon. However, the spontaneous emission is generally masked by the dynamical positron emission, which is induced by a strong time-dependent electric field created by the colliding nuclei. In our recent paper [I. A. Maltsev et al., Phys. Rev. Lett. 123, 113401 (2019)PRLTAO0031-900710.1103/PhysRevLett.123.113401] it has been shown that the spontaneous pair production can be observed via measurements of the pair-production probabilities for a given set of nuclear trajectories. In the present paper, we have significantly advanced this study by exploring additional aspects of the process we are interested in. We calculate the positron energy spectra and find that these spectra can give a clear signature of the transition from the subcritical to the supercritical regime. It is found that focusing on a part of the positron spectrum, which accounts for the energy region where the spontaneously created positrons can contribute, allows us to get a much stronger evidence of the transition to the supercritical mode, making it very well pronounced in collisions, for example, of two uranium nuclei. The possibility of extending this study to collisions of bare nuclei with neutral atoms is also considered. The probability of a vacancy in the lowest-energy state of a quasimolecule which is formed in collisions of a bare U nucleus with neutral U and Cm atoms has been calculated. The relatively large values of this probability make such collisions suitable for observing the vacuum decay.