HIRFL-CSR实验环团簇内靶的首批测试实验

First test experiment of HIRFL-CSR cluster internal target system

内靶装置是兰州重离子冷却储存环（HIRFL-CSR）实验环的一个重要的插入件，也是世界上第一个嵌入在重离子储存环中的内靶装置，它位于HIRFL-CSR实验环的一个直线段．团簇内靶具有传统外靶所不具备的一些优点，如高亮度、高精度和高灵敏度等．这些优点可使我们在内靶实验平台上进行一些高精度的物理实验．为满足不同物理实验的需求，内靶可以有两种工作模式：非极化靶运行模式和极化靶远行模式，用于为实验环内的物理实验提供厚度为10^11～10^13atoms／cm^2的非极化靶和极化靶．团簇靶是属于非极化靶运行模式，它采用超声喷气和冷凝相结合的方法获得团簇粒子束，并在碰撞靶室中与环内束流相碰撞，未反应的团簇柬被收集级抽走．团簇内靶可以提供靶密度约为2×10^13atoms／cm^2的Ne、Ar、Kr、Xe和N2、CH4等团簇束．目前已完成了团簇靶的现场安装和准直，并进行了真空达标、喷嘴冷却和稳定性等首批测试实验．本文主要介绍团簇靶的工作原理和首批测试实验结果．

The internal target system is an important inset device in HIRFL-CSR, also is the first one mstalled at the heavy-ion cooler-storage ring. The internal target has many unique advantages such as high luminosity, high precision and high sensitivity, which make the internal target an important tool of high-precision experiments. The internal target is located at one straight section of CSRe which is designed to operate both in the unpolarized mode and in the polarized mode. The unpolarized target is a cluster target and may provide the gas target of H2, N2, inert gases and small molecular gases with the expected density of ≥10^12 atorns/cm^2. The cluster target obtains the cluster beam by cooling supersonic gas-jet. The first test experiment has been done after the installation and collimation of cluster internal target. The experiments include the test of vacuum system and stability of cluster target system, cooling of nozzle. The principle of cluster target is introduced and the results of first test experiment are reported here.