LHC／ALICE及其光子探测

LHC/ALICE and Photon Detection

大型强子对撞机（LHC）上的大型离子对撞机实验（ALICE）将致力于TeV能区重离子碰撞，探测夸克退禁闭的新物质形态——夸克-胶子等离子体（QGP），探索宇宙诞生之初的物态性质。本文介绍其上的新一代电磁谱仪ALICE光子探测器（PHOS），它将用于铅-铅碰撞实验中测量直接光子和衰变光子产物，诊断夸克物质的电磁信号。束流测试结果显示，ALICE光子谱仪——PHOS将能够高效探测0．5～100GeV／c的光子。

A large ion collider experiment （ALICE） at the large hadron collider （LHC） will be indicated to the detection of quark-gluon plasma （QGP） formed in heavy-ion collisions at TeV, and the exploration of the early universe as it was in the first few microseconds after its birth. A high precision electromagnetic calorimeter--ALICE photon spectrometer （PHOS）, designed and produced by ALICE collaboration was described in the paper. It was used to detect the prompt- and decay-photons and diagnose the electromagnetic signal of quark-gluon plasma in lead-lead collisions at √SNN= 5. 5 TeV. The beam test results show that PHOS is capable to detect photons efficiently up to 0. 5- 100 GeV/c in ALICE.