SuperKEKB試運轉期間之BEAST2偵測器中的BGO背景與光度監測器的設計、製造與測試

Abstract

利用BGO閃爍體作為偵測器的BGO系統在新升級的SuperKEKB加速器的試運轉偵測器Beast2中，擔任階段一的背景監控器與階段二的粒子反應亮度監控器。 在階段一，SuperKEKB加速器初步試運轉，此時雖然沒有碰撞產生，但背景能量會慢慢上升。Beast2 的偵測器有部分會進駐，而我們的BGO系統在此階段可藉由能量校準的數據偵測及累加得知即時的背景能量，作為此階段的背景能量監控器。 在階段二，伴隨著高能電子及正子的碰撞，產生許多Bha-bha散射。由於動量守恆，在質心座標中，具有｢背對背｣的特性。藉由測量背對背事件的事件率，BGO系統可以計算出粒子反應的亮度，作為此階段的亮度監控器。 我的研究主要是讀出板的設計、製造與測試，以及整個系的組裝。在這篇文章中，會特別詳細介紹讀出板從設計到最後的測試結果，以及整個系統運作的數據校準。

The BGO system is a detector with BGO crystals. In the SuperKEKB commissioning, which is the accelerator upgraded in these years, BGO system is one of the Beast2 detectors. It will be the background monitor in the phase 1 and the luminosity monitor in the phase 2. In the phase 1, SuperKEKB starts to work. Although there’s no collision, the background energy still rises slowly. Some of the Beast2 detector will be inside the SuperKEKB. The BGO system will sum up to calculate the background energy for monitoring with the important data from the energy calibration. In the phase 2, there’re so many Bha-bha scattering after the collision between high energy electrons and positrons. In the C.M. frame, there’s the so-called “back to back” property in the scattering because of the conservation of momentum. By detecting the back to back event and calculating the rate, BGO system can get the luminosity of interaction for monitoring. My study is focused on the design, production, testing of the readout board and the building up of the whole system. In this thesis, I’ll introduce more on the readout board from design to the final test and the calibration for whole system running.