Author/Authors :
G. Bassompierre، نويسنده , , G. Bologna، نويسنده , , D. Boget، نويسنده , , M. Chevallier، نويسنده , , S. Costa، نويسنده , , J. Dufournaud، نويسنده , , M. Farizon، نويسنده , , B. Farizon Mazuy، نويسنده , , A. Feliciello، نويسنده , , M.J. Gaillard، نويسنده , , R. Garfagnini، نويسنده , , R. Genre، نويسنده , , M. Gouanère، نويسنده , , B. Ille، نويسنده , , Jeffrey R. Kirsch، نويسنده , , P. Lautesse، نويسنده , , M. Richard، نويسنده , , E. Rossetto، نويسنده , , D. Sillou، نويسنده , , M. Spighel، نويسنده , , et al.، نويسنده ,
Abstract :
We describe a search for a light neutral object X0 possibly produced by ≈ 100 GeV photons interacting with the QED strong field encountered along the <110 > axis of a cooled Ge crystal. We look at the e+e− decay mode, in short (10−18−10−12 s) as well as long (10−13−10−8 s) lifetime detection conditions. For a mass of 1.8 ±0.2MeV/c2 (“Darmstadton” mass) we find no evidence for X0 production. The upper limit for the ratio between e+e− decay rate and pair creation is given as a function of the X0 lifetime. It reaches ≈ 5 × 10−4 and ≈ 2 × 10−5 in the short and long lifetime mode, respectively, including the crystal absorption contribution. However, for the long-lifetime mode and 108 incident photons, 9 events are compatible with neutral objects having masses ranging from 2.1 to 3.5 MeVc2. A Monte Carlo simulation of the background gives only 1 event in the same energy range.
