Development of pulsed conducting target for high intensity and high luminosity muon beam

我们研究了用于高强度Muon源的“传导脉冲靶”。通过施加大的脉冲电流，二次产生的介子会由于大的环形场而被限制在靶内。最终，冠军将从目标的末端出来。为了实现这一新方案，我们从以下几个方面进行了研究：1.确定了低能Muon源--棱镜的基本参数。我们首先对汞靶进行了研究，并研制了几种装置：汞环、脉冲电源、脉冲变压器。束-靶相互作用产生的辐射加热是靶体设计的关键参数之一。我们开发了一种新技术，即所谓的“深冷量热计”，用于精确测量束流加热并校准蒙特卡罗模拟程序。选择能在强脉冲电流和强束流下存活的靶材是非常重要的。我们测量了几种候选材料的力学性能，并仔细观察了它们在辐照时的变化。对于像次级光束这样色散较大的光束，其发射度的测量是非常困难的。我们发展了一种通过测量每个次级粒子的轨迹和动量来测量束流发射度的新方法。我们研究并获得了许多实现“传导脉冲靶”的必要知识，尽管由于测试光束的时间有限和不可用，我们无法进行原理验证实验。我们将在这些成就的基础上，继续致力于开发目标技术。

We have studied "conducting pulsed target" for high intensity muon source. By applying large pulsed current, secondary-produced pions would be confined inside the target because of large toroid field. In the end, pions would come out from the end of the target. This scheme would provide much brighter secondary beam with smaller emittance.To realize this new scheme, we have investigated various fields as follows:1. We have determined the basic parameters for the PRISM, a low energy muon source. We first studied mercury target and have developed several equipments: mercury loop, pulsed power supply, and pulse transformer.2. Radiation heating caused by beam-target interaction is one of the key parameters in design of the target. We developed a new technique, so called "cryogenic calorimeter" to measure beam heating precisely and to calibrate Monte Carlo simulation code.3. It is very important to select the target material which could survive under high pulsed current and high intense beam. We have measured mechanical properties for several candidate materials and carefully watch their change when they are irradiated.4. It is very difficult to measure emittance of the beam with large dispersion such as secondary beam. We have developed a new measurement method of beam emittance by measuring track and momentum for each secondary particle.We have studied and obtained lots of essential knowledge to realize the "conducting pulsed target" although we could not carried out proof-of-principle experiments due to the limited time and unavailability of the test beam. We will to continue to work on developing the target technology, on the basis of these accomplishments.