Research on Track Detector in Hadron Collider Experiment

在本项目中，我们调查了闪烁光纤跟踪系统的发展前沿情况。对于作为跟踪装置的闪烁纤维，它们的直径必须小到30 μ m。几年前，塑料光纤不可能达到如此小的直径，因为闪烁光在单根光纤中不能被充分吸收，并且发生严重的串扰。最近开发的是一种新的WLS（波长移位器），它使塑料闪烁纤维成为跟踪设备元件的有希望的候选者。这种称为PMP的WLS具有很大的Stokes位移，在30 μ m光纤中可以同时实现对闪烁光的充分吸收和较长的衰减长度。根据最近的报告（C。Angelini等，NIM A295（1990）299），掺1.5%（重量）PMP的30 μ m聚苯乙烯光纤具有9光子/keV的光子产额和长达30 cm的衰减长度。1）单独的光纤必须涂覆有适当的EMA（Extramural Absorber），其有效地限制闪烁光从一根光纤进入另一根光纤。2）研制能对光学图像信号进行放大、选通和延迟的器件; 3）在读出系统的最后一级，必须对CCD图像数据进行快速处理。随着最近在工业领域建立的DSP（数字信号处理）技术，这将成为可能。

In this program, we have investigated the forefront situation of the development on a scintillation fiber tracking system. A short summary of the present investigation are described below.For the scintillation fibers as an tracking device, their diameter must be as small as 30mum. It was impossible by several years ago for a plastic fiber to achieve such a small diameter because the scintillation light could not be absorbed sufficiently in the single fiber and a serious cross-talktook place. Developed recently was a new WLS (Wave Length Shifter) which enables a plastic scintillation fiber to be a promising candidate for the elements of the Tracking device. The WLS named as PMP has such a large Stokes shift that both sufficient absorption of scintillation light and long attenuation length can be realized at the same time in 30mum fiber. According to the recent report (C. Angelini et al. NIM A295 (1990) 299), 30mum polystylene fiber doped with 1.5% (weight) PMP exhibits the photon yield of 9 photon/kev and the attenuation length of as long as 30cm.For the construction of a realistic detector with a plastic scintillation fiber, the further investigation are required in the following points :1) The individual fibers must be coated with an appropriate EMA (Extramural Absorber), which effectively restricts the passage of scintillation light from one fiber into another. The development of a new EMA compatible with the manufacturing process of fibers are necessary.2) The device which can amplify, strobe and delay the optical image signal, must be developed.3) Fast processing of the image data from CCD must be required for the final stage of the read-out system. This will become possible with the recent DSP (Digital Signal Processing) technique established in the industrial field.