Abstract

The electromagnetic dissociation of ultrarelativistic nuclei has a substantial impact on the lifetime of beams in the Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC), and secondary nuclei produced upon this dissociation may have an adverse effect on collider components. At the same time, the detection of neutrons originating from the electromagnetic dissociation process makes it possible to monitor the luminosity of colliders. In order to calculate the total and partial cross sections for the electromagnetic dissociation process by the Weizsäcker–Williams method, one needs reliable photonuclear reaction models preliminarily tested via a comparison of the results that they produce with available experimental data. Since the commissioning of the LHC, attention has been given primarily to \({}^{208}\)Pb–\({}^{208}\)Pb collisions. A run involving \({}^{129}\)Xe nuclei was also performed. In contrast to the case of \({}^{208}\)Pb nuclei, for which the photonuclear reaction and electromagnetic dissociation cross sections have been measured at various laboratories, there are no data for \({}^{129}\)Xe. By employing the experimental–theoretical method, the (\(\gamma,1n\)), (\(\gamma,2n\)), (\(\gamma,3n\)), and (\(\gamma\), abs) cross sections for the \({}^{129}\)Xe nucleus are evaluated on the basis of available data for the neighboring nucleus of \({}^{127}\)I and the combined photonuclear reaction model (CPNRM). It is found that the results of CPNRM calculations performed for \({}^{129}\)Xe at photon energies up to 40 MeV by employing the TENDL-2017 library compiled by means of the TALYS code are close to one another and are in fairly good agreement with data obtained at the Saclay laboratory for \({}^{127}\)I. These new evaluated data, the TENDL-2017 library, and approximations of the total photoabsorption cross sections above the pion production threshold are used to calculate the electromagnetic dissociation cross section for \({}^{129}\)Xe at the LHC and at the FCC-hh collider being designed. The results of these calculations are compared with their counterparts obtained on the basis of the RELDIS model.

中文翻译：

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$$ {} ^ {\ mathbf {129}} $$ Xe核上的光中子反应及其在碰撞子中的电磁离解

摘要

超相对论核的电磁离解对相对论重离子对撞机（RHIC）和大强子对撞机（LHC）中的电子束寿命产生重大影响，并且在这种解离后产生的次级原子核可能会对对撞机组件产生不利影响。同时，对源自电磁解离过程的中子的检测使得可以监视对撞机的发光度。为了通过Weizsäcker-Williams方法计算电磁离解过程的总横截面和部分横截面，需要通过将其产生的结果与可用的实验数据进行比较来初步测试可靠的光核反应模型。自大型强子对撞机投入运行以来，人们主要关注\（{} ^ {208} \）Pb – \（{} ^ {208} \） Pb碰撞。还执行了涉及\（{} ^ {129} \） Xe核的运行。与\（{} ^ {208} \） Pb核的情况相反，在不同实验室已测量了该核的光核反应和电磁离解截面，没有\（{} ^ {129} \ ） Xe。通过采用实验理论方法，（\（\ gamma，1n \）），（\（\ gamma，2n \）），（\（\ gamma，3n \））和（\（\ gamma \），绝对压力）为横截面的\（{} ^ {129} \）的Xe核是可用的数据为所述相邻核的基础上评价\（{} ^ {127} \）我和组合的光核反应模型（CPNRM）。结果发现，通过使用借助TALYS代码编译的TENDL-2017库，在光子能量高达40 MeV时对\（{} ^ {129} \） Xe执行的CPNRM计算结果彼此接近，并且与在Saclay实验室获得的\（{} ^ {127} \） I的数据非常吻合。使用了这些新评估的数据，TENDL-2017库以及高于介子产生阈值的总光吸收截面的近似值。计算在LHC和正在设计的FCC-hh对撞机上\（{} ^ {129} \） Xe的电磁解离截面。将这些计算的结果与在RELDIS模型的基础上获得的结果进行比较。