Producing Slow Antihydrogen for a Test of CPT Symmetry with ATHENA

The ATHENA experiment at the Antiproton Decelerator facility at CERN aims at testing CPT symmetry with antihydrogen. An overview of the experiment, together with preliminary results of development towards the production of slow antihydrogen are reported.The ATHENA experiment at the Antiproton Decelerator facility at CERN aims at testing CPT symmetry with antihydrogen. An overview of the experiment, together with preliminary results of development towards the production of slow antihydrogen are reported.The ATHENA experiment at the Antiproton Decelerator facility at CERN aims at testing CPT symmetry with antihydrogen. An overview of the experiment, together with preliminary results of development towards the production of slow antihydrogen are reported.The ATHENA experiment at the Antiproton Decelerator facility at CERN aims at testing CPT symmetry with antihydrogen. An overview of the experiment, together with preliminary results of development towards the production of slow antihydrogen are reported

Temperature dependence of pure CsI: scintillation light yield and decay time

The temperature dependence of the light emission for pure CsI crystals has been measured with photomultipliers, and photodiodes with wavelength shifters from 80-300 K. The light yield at 80 K is N subgamma=50,000+-5000 photons/MeV. This number was deduced from the number of electron-hole pairs produced in the photodiode, N sub e sub h =39,600+-1200. The light yield at room temperature is lower by a factor of 15.8+-1.0, giving 3200+-400 photons/MeV. Decay times were measured with a photomultiplier. At room temperature two fast decay components were observed with decay times of 6+-1 and 28+-2 ns. Below 180 K only one component is observed and at 80 K the decay time is 1015+-17 ns

Detection of antihydrogen annihilations with a cryogenic pure-CsI crystal detector

In the framework of the ATHENA experiment a combined tracking and photon detector, operating close to liquid nitrogen temperatures, was developed to determine simultaneously the vertex of an antiproton annihilation and energy and direction of photons stemming from a positron annihilation. The photon detector consists of 192 pure-CsI scintillation crystals (=4 cm3) coupled to 5 x 5 mm2 avalanche photo-diodes, which are read by electronic chips realised in VLSI CMOS technology. These read out chips are also operational at liquid nitrogen temperature and feature a self-triggering capability

The ATHENA antihydrogen apparatus

The ATHENA apparatus that recently produced and detected the first cold antihydrogen atoms is described. Its main features, which are described herein, are: an external positron accumulator, making it possible to accumulate large numbers of positrons; a separate antiproton catching trap, optimizing the catching, colling and handling of antiprotons: a unique high resolution antihydrogen annihilation detector, allowing a clear determination that antihydrogen has been produced; an open, modular design making variations in the experimental approach possible and a "nested" Penning trap situated in a cryogenic, 3T magnetic field environment used for the mixing of the antiprotons and positrons