TACTIC: A large solid angle particle detection system

我们提出了一个探测器的建设，以测量低能和中能带电粒子反应几乎覆盖整个立体角。这个名为“战术”的探测器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，检测不可见。离子穿过导线网离开中心区域。然后，它们将在现场区域产生痕迹。自由电子被施加的电场吸引到阳极。然而，在它们的途中，电子将遇到GEM（气体电子倍增器）箔，从而将信号放大很大。在阳极条上记录的信号将被数字化。该室将记录完整的走线，其中包括方向，全能量测量和每个阳极带的能量损失测量。一组BGO探测器将被放置在粒子-伽马反应室周围。阳极条将在极性方向上划分，以允许更高的计数率以及多粒子反应的检测。目前提出的反应包括8Li(α,n)11B, 7Be(p,p)7Be弹性和非弹性散射反应，以及12C+12C。我们的试验证明，该战术所依据的原理是合理的，试验室是可行的。我们还进行了大量的agent模拟。一个类似的探测器（BONUS）已经在杰斐逊实验室建成，并已被实验证明是有效的。我们在这里要求建设费用，必要的人力和一些旅费，以建立战术探测器的最终版本。有了今年的种子基金，我们能够继续建造一个原型探测器，目前（2006年9月）正在英国建造中。在四月，我们期望这个原型探测器可用，并完成一些α源和稳定光束的测试。目前的不足主要集中在数据采集系统和系统集成方面。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，也包括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.