Study On The Light Concentrator Of The Wide Field Of View Cherenkov Telescope

The Large High Altitude Air Shower Observatory (LHAASO) is a significant scientific infrastructure construction project with core of cosmic ray research in the thirteenth Five-year Plan of our country. And The LHAASO will be one of the four biggest cosmic ray research base of the world. The Wide Field of Cherenkov Telescope Array (WFCTA) is an important component of LHAASO plan, it will achieve high accuracy measurement of cosmic ray energy spectrum so that we could explore the enigma of the world-the origin of cosmic ray.WFCTA is constituted by optical reflection system, electrical detector system, machinery support and regulating system, and the detector composed by photomultiplier array is located on the focal plane of spherical reflector. Because of the geometric profile and the photocathode’s effective response area of photomultiplier, no response area and invalid area would be inevitable when photomultipliers are arranged in detector array, so the collection efficiency of Cherenkov optical signal is reduced. In order to improve the detect efficiency and sensibility of Cherenkov Telescope, we’ve applied light concentrator on the front-end of the detector based on the practical application request of WFCTA, and the problems mentioned above are figured out efficiently. The major works of this paper are as follows:First, we’ve briefly introduced the background and the meaning of the high-energy cosmic ray detect research, as well as the general situation of the LHAASO plan. We’ ve investigated the light concentrator research situation of the world in this domain, and elaborate analysis of the composition, key parameters and characters of the compound parabolic concentrator (CPC) is provided in this paper. All of these works have laid a foundation for light concentrator design.Secondly, we’ve designed and optimized the concentrator structure parameters which is suitable for WFCTA’s detector on the basis of the edge-ray principle of concentrator. Four kinds of single concentrator like circular light cone, hexagon light cone, CPC and hexagon CPC in the non-sequential mode of ZEMAX have been simulated. Meanwhile, we’ve also simulated the focusing effect of the concentrator which comes from practical optical system of WFCTA in the mixed-sequential mode. The analysis suggests that hexagon CPC has better performance in light focus and light collection, so hexagon CPC has been determined as the prior plan of the WFCTA’s detector.Finally, according to the design parameters of hexagon CPC, the samples have been made and tested. The experiment results turn out that the hexagon CPC we’ve designed and processed have optimized the collection efficiency of light signal remarkably. Compared to the detector without light concentrator, about 30% collection efficiency has been promoted. Except the better performance in the collection efficiency, the property of well-distributed light collection is also deserved to be mentioned. In conclusion, the work we’ve done meets the request anticipated before.