Cosmic Ray Telescope
宇宙射線望遠鏡示意圖
Schematic Diagram of Cosmic Ray Telescope
宇宙射線望遠鏡─探測部份
Detection Part
宇宙射線望遠鏡─數據收集部份
Data Acquisition (DAQ) Part
宇宙射線望遠鏡主要是由三件探測器、一組觸發電路、一個全球定位系統接收器和一部配備計時器介面的電腦組成。
The Cosmic Ray Telescope contains 3 detectors, a trigger electronics, a GPS receiver and a timer card in a computer.
宇宙射線探測器
Cosmic Ray Detector
塑膠閃爍器和波長變換器的樣本
Scintillator and Wavelength Shifter
塑膠閃爍器─受環境光線激發而呈現藍色
Scintillator looks bluish due to excitation
波長變換器─受環境光線激發而呈現黃綠色
Wavelength shifter looks greenish yellow due to excitation
光電倍增管─連接至波長變換器（右）
PM tube is connected to the wavelength shifter (right)
光電倍增管─連接至訊號輸出（左）及電源輸入（下）
PM tube is connected to signal cable (left) and power input (right)
每件探測器是由一塊塑膠閃爍器、一條波長變換器和一個光電倍增管組成，並加以密封。密封可避免環境光線影響光電倍增管。每當宇宙射線粒子穿透塑膠閃爍器時，閃爍器內的有機摻雜物便會受激發而放出藍光及紫外光。光訊號經波長變換器轉換為波長較長的黃綠光，並導向光電倍增管。光電倍增管將光訊號轉為電訊號，並放大輸出至觸發電路。
Every light-proof detector consists of a plastic scintillator, a wavelength shifter and a photomultiplier (PM) tube. When cosmic ray particles pass through the scintillator, the organic doping within is excited and hence emit ultra-violet and bluish light. It is changed to light of longer wavelength (greenish yellow) and guided to the PM tube. The optical signal is transformed and amplified into electrical signal and then transmitted to the trigger electronics.
觸發電路模組
Trigger Electronics Module
原型 Prototype / 運作型 Model
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類比訊號（左）經鑒別器轉變為邏輯訊號（右）
Analog signal (left) is discriminated into logical signal (right)
觸發電路是由三個鑒別器和一個「與」門電路組成。鑒別器先將形狀不一的類比訊號轉換成同樣的邏輯訊號，再由「與」門電路決定是否觸發數據收集。這樣便可除去由環境輻射所產生的大量噪音訊號。
The trigger electronics consists of 3 discriminators and a coincidence unit. A discriminator transforms shapeless signals into identical logic signals. Afterwards the coincidence unit triggers data acquisition. This can reduce lots of background noise due to surrounding radiations.
電腦程式─控制電腦介面計時器以獲取數據
Computer program controls the timer card for DAQ
利用電腦程式，計時器可記錄來自觸發電路的宇宙射線訊號。同時，由於電腦的內置時鐘不夠精確，計時器亦會記錄來自全球定位系統的報時訊號，以便準確計算宇宙射線的接收時間。
Implementing a computer program, the timer card can record cosmic ray signals from trigger eletronics. As the computer clock is not accurate enough, the timer card also records time beats from Global Positioning System (GPS). This makes accurate timing of cosmic ray arrival feasible.
全球定位系統接收器─天線及電路
GPS receiver module including antenna and electronics
原型 Prototype / 運作型 Model
全球定位系統天線─伸出窗外以接收衛星訊號
A GPS antenna is receiving satellite signals outdoor
全球定位系統接收器負責接收來自衛星的訊號。訊號包含該衛星的時間和位置資料；利用不同衛星的資料，可以推算該觀測站的準確位置和時間，並將準確的報時訊號傳送到計時器。
GPS receiver module get signals from satellites ahead. The signals contain timing and positioning information from the satellites, which can determine the time and the position of the receiver accurately.