Development of a Reconfigurable Monolithic Active Pixel Sensor in Radiation-hard Technology for Outer Tracking and Digital Electromagnetic Calorimetry

随着粒子物理学的发展，对探测器技术的要求总是朝着需要更精细的分割、更快的读出和更大的辐射耐受性的方向发展;所有这些都需要更低的成本。为了找到质量太大而无法观测到的粒子，粒子对撞机必须不断地向更高的能量推进。然而，随着碰撞能量的增加，包含这种新物理学潜在证据的事件的速率作为总数的一部分而减少，这使得在高能量下也具有非常高的相互作用速率变得重要。此外，随着能量的增加，每次碰撞产生的粒子数量增加，并且所产生的感兴趣粒子的平均能量增加。后者意味着带电粒子变得更难在检测器磁场中弯曲，并且因此需要更好的空间精度（因此更小的感测元件），导致需要更大的粒度（每单位面积的像素数量）。在更高的能量下，粒子簇射往往也更加准直，使得在每单位面积没有更多读出单元的情况下也更难进行轨道分离。最后，在强子对撞机上，高速率要求每个光束交叉多次碰撞，因此有趣的相互作用通常被同时产生的200个不感兴趣的相互作用所掩盖。从有趣的碰撞中提取轨迹也需要非常精确的测量。最后，每秒数十亿次的碰撞导致多年运行的辐射水平远远超出了正常电子设备的能力，需要专业设计才能在预期剂量后工作。粒子物理传感器无法利用超廉价的超大型像素相机在许多商业设备中，因为这些既不具有所需的速度也不具有辐射硬度，但它们容易满足以下方面的要求粒度因此，如果能够设计出快速、抗辐射的版本，这将在传感器的可负担性方面改变游戏规则。最近的工作表明，有商业CMOS技术，可以支持辐射硬的设计和这个建议试图利用这些来证明设备，可以允许非常大的实验领域配备这样的探测器负担得起的。使传感器抗辐射的设计方面也使它们更快，这是这些应用的附加优势。然而，证明小型传感器具有所需的性能是迈向最终阵列的第一步，最终阵列需要数千平方米的传感器，在设想一个非常大的阵列之前，需要大量的开发时间。因此，尽管可能的应用还有很长的路要走，但将新技术开发到在如此大的阵列中利用所需的成熟度所需的时间意味着这种研发非常及时。英国在许多技术方面处于领先地位，但国际上还有许多其他团体追求同样的目标，因此如果目前的领导地位（其中大部分是通过ATLAS和CMS升级以及国际线性学院的工作开发的）不会丢失，那么这项提案也很重要。

As particle physics progresses, the demands in terms of detector technologies always push toward needing fine segmentation, faster read-out and greater radiation tolerance; all at lower cost. To find particles too massive to have been seen already, particle colliders have to continuously push towards higher energies. However, as collision energies increase, the rates for events containing potential evidence for such new physics decreases as a fraction of the total, making it important at high energies to also have very high interaction rates. Also, as energies increase, the numbers of particles produced per collision increase and the mean energies of the produced particles of interest increase. The latter means that charged particles become harder to bend in the detector magnetic field and so better spatial precision (hence smaller sense elements) is needed leading to the need for much greater granularity (number of pixels per unit area). At higher energies, particle showers tend to also be much more collimated, making track separation also harder without many more read-out cells per unit area. Finally, at hadron colliders, high rates require many collisions per beam crossing so the interesting interactions are typically buried in 200 uninteresting ones produced at the same time. Unpicking the tracks from the interesting collision also requires very precise measurements. Finally, billions of collisions per second lead to radiation levels over years of operation that go way beyond the capabilities of normal electronics requiring specialist designs to work after the expected doses.Particle physics sensors are not able to exploit the development of ultra-cheap mega-pixel cameras in many commercial devices because these neither have the speed or radiation hardness needed but they easily meet the requirements in terms of granularity. Therefore, if fast, radiation-hard versions could be designed, these would be a game-changer in terms of sensor affordability. Recent work has shown that there are commercial CMOS technologies available that can support radiation-hard designs and this proposal seeks to exploit these to demonstrate devices that could allow very large areas of experiments to be equipped with such detectors affordably. Aspects of the design that makes the sensors radiation hard also make them faster which is an added advantage for these applications. Nevertheless, proving small sensors with the required properties is a first step towards final arrays requiring thousands of square metres of sensors and much development time is needed before a very large array could be envisaged. Therefore, even though the possible applications are quite a long way off, the amount of time to develop new technologies to the required maturity to be exploited in such large arrays means that this R&D is very timely. The UK has a lead in a number of the technology aspects for this but there are many other groups internationally pursuing the same goals and so this proposal is also important if current leadership, much of it developed through work for ATLAS and CMS upgrades and for the International Linear Colldier, is not to be lost.