TACTIC: A large solid angle particle detection system

我们提出了一种用于测量低能量和中等能量带电粒子反应的探测器的结构，几乎覆盖了整个立体角。这个探测器，命名为TACTIC，将是一个圆柱形的时间投影室，在径向方向上有一个电场。探测器的中心区域将包含气体目标。中心区域处于恒定电位并且对于检测不可见。离子穿过金属丝网格离开中心区域。然后，它们将在场区域中产生迹线。自由电子被施加的电场吸引向阳极。然而，在途中，电子会遇到GEM（气体电子倍增器）箔，从而将信号放大很大一部分。在阳极条记录的信号将被数字化。腔室将记录完整的轨迹，包括方向、完整的能量测量和每个阳极条的能量损失测量。一个BGO探测器阵列将被放置在粒子伽马反应室周围。阳极条将在极性方向上分开，以允许更高的计数率以及多个粒子反应的检测。到目前为止提出的反应包括测量8Li（alpha，n）11B，7Be（p，p）7Be弹性和非弹性散射反应，以及12C+12C。我们的测试证明，TACTIC所依据的原理是合理的，并且该室是可行的。我们还进行了广泛的GEANT模拟。一个类似的探测器（BONUS）已经在杰斐逊实验室建造，并已通过实验证明其工作。我们在这里要求建造成本，必要的人力和一些旅费，以建立最终版本的TACTIC探测器。有了今年的种子资金，我们能够继续建造一个原型探测器，目前（2006年9月）正在英国建造。今年4月，我们预计将有这个原型探测器可用，并完成一些α源和稳定束测试。我们主要在数据采集系统和系统集成方面还有欠缺。利用在原型探测器上获得的经验，我们计划建造最终的探测器，其中还包括Dragon BGO阵列。

We propose the construction of a detector for the measurement of low and intermediate energy charged particle reactions covering nearly the full solid angle. This detector, named TACTIC, will be a cylindrical timeprojection chamber with an electric field in the radial direction. The central region of the detector will contain the gas target. The central region is at a constant potential and is not visible to detection. Ions pass through a grid of wires leaving the central region. They will then produce a trace in the field region. The free electrons are drawn towards the anode by the electric field applied. However, on their way the electrons will encounter a GEM (Gas Electron Multiplier) foil, thus amplifying the signal by a large factor. Signals registered at the anode strips will be digitized. The chamber will register full traces which includes directions, a full energy measurement and for each anode strip an energy loss measurement. An array of BGO detectors will be placed around the chamber for particle-gamma reactions. The anode strips will be divided in polar direction to allow for higher counting rates as well as for the detection of multiple particle reactions. The reactions so far proposed include measurements of the 8Li(alpha,n)11B, the 7Be(p,p)7Be elastic and inelastic scattering reaction, and a 12C+12C. Our tests have proven that the principle on which TACTIC is based is sound and the chamber feasible. We also have performed extensive GEANT simulations. A similar detector (BONUS) has been built at the Jefferson Laboratory and has been experimentally demonstrated to work. We request here construction costs, the necessary manpower and some travel money to build the final version of the TACTIC detector. With the seed money of this year, we were able to progress with the construction of a prototype detector that at present (Sept06)is under construction in the UK. In April, we expect to have this prototype detector available and some alpha-source and stable beam tests done. We are still lacking mainly in the area of the data acquisition system and system integration. Using the experience gained at the prototype detector, we plan to build the final detector, incorporating also the DRAGON BGO array.