Beam-induced heat loads on the cryogenic regions of the Large Hadron Collider (LHC) exhibit a wide and unexpected dispersion along the accelerator, with potential impact on the performance of its High-Luminosity upgrade. Studies related the heat load source to the avalanche multiplication of electrons at the surface of the beam vacuum chamber, a phenomenon known as electron could build-up. Here, we demonstrate that the topmost copper surface of beam pipes extracted from a low heat load region of the LHC consists of native Cu₂O, while the pipe surface from a high heat load region had been oxidized to CuO during LHC operation and maintenance cycles. Experiments show that this process increases the secondary electron yield and inhibits efficient surface conditioning, thus enhancing the electron cloud intensity during LHC operation. This study relates the abnormal LHC heat loads to beam-induced surface modifications of its beam pipes, enabling the development of curative solutions to overcome this critical limitation.

大型强子对撞机 (LHC) 低温区域的光束引起的热载荷沿着加速器呈现出广泛且出乎意料的分散，对其高亮度升级的性能有潜在影响。研究将热负荷源与电子束真空室表面的雪崩倍增联系起来，这种现象称为电子可能积聚。在这里，我们证明了从 LHC 的低热负荷区域提取的束管的最顶部铜表面由天然 Cu ₂O，而来自高热负荷区域的管道表面在 LHC 运行和维护周期中已被氧化为 CuO。实验表明，该过程增加了二次电子产率并抑制了有效的表面调节，从而增强了 LHC 运行期间的电子云强度。这项研究将异常 LHC 热载荷与其梁管的梁诱导表面修改联系起来，从而能够开发出治愈性解决方案来克服这一关键限制。