Electron cloud is a critical phenomenon in particle accelerators operating with high intensity and positively charged beams, as it is responsible for beam instabilities, vacuum degradation, and heat load on cryogenic sections. Electron clouds provoke a conditioning of the beam pipe that is reflected on the reduction of its secondary electron yield (SEY). However, such a benefit is partially lost when vacuum sectors are vented for maintenance of accelerators; this phenomenon is called deconditioning. Samples removed from accelerators are also vented before surface analysis. Deconditioning amplifies the electron cloud at the resuming of beam operation and, on the other hand, hinders the understanding of the electron multipacting mechanism from surface analysis data. In this paper, copper deconditioning was studied for samples stored in a desiccator over months. Immediately after air exposure, an increase of the SEY is observed. This increase is driven by carbon recontamination and copper hydroxide growth on the conditioned surface as observed by x-ray photoelectron spectroscopy. After deconditioning, the differences of SEY present on the tested samples partially vanish, in particular, for surfaces conditioned to a maximum SEY below 1.45, limiting the level of accessible information when analyzing components extracted from accelerators. However, for a maximum SEY above 1.45, the differences remain visible for at least 8 weeks of storage. Among different storage conditions, vacuum efficiently stops the SEY increase over time. Besides, the memory effect of the conditioning is preserved over at least 4 months when closing the vacuum system on itself after venting with a clean and dry gas.

中文翻译：

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退质对粒子加速器中铜表面二次电子产率的影响

电子云是在粒子加速器中以高强度和带正电的光束运行的一种关键现象，因为它导致了电子束的不稳定性，真空退化以及低温部分的热负荷。电子云引起束管的调节，这反映在其二次电子产率（SEY）的降低上。但是，当为维修加速器而抽真空部分时，这种好处会部分丧失。这种现象称为老化。从加速器中取出的样品在表面分析之前也要进行排气。降级会在恢复电子束操作时放大电子云，另一方面会妨碍从表面分析数据了解电子多步机制。在本文中，对于干燥器中存储了数月之久的样品，我们进行了铜脱盐研究。暴露在空气中后，立即观察到SEY升高。如通过X射线光电子能谱观察到的，这种增加是由碳重新污染和调节表面上氢氧化铜的生长所驱动。老化后，特别是对于表面最大SEY低于1.45的表面，存在于测试样品上的SEY差异会部分消失，从而限制了分析从加速剂中提取的成分时可访问信息的水平。但是，对于大于1.45的最大SEY，在至少存储8周后仍可以看到差异。在不同的存储条件下，真空有效地阻止了SEY随时间的增长。除了，