Author :
Aihara, H. ; Alston-Garnjost, M. ; Badtke, D.H. ; Bakken, J.A. ; Barbaro-Galtieri, A. ; Barnes, A.V. ; Barnett, B.A. ; Blumenfeld, B. ; Bross, A. ; Buchanan, C.D. ; Carithers, W.C. ; Chamberlain, O. ; Chiba, J. ; Chien, C-Y. ; Clark, A.R. ; Dahl, O.I. ; D
Author_Institution :
Department of Physics, University of Tokyo, Tokyo, Japan
Abstract :
The PEP-4 hexagonal barrel calorimeter, with lead-laminate layers and 5×lOmm2 Geiger-mode discharge cells, has demonstrated excellent stability and uniformity in operation. The use of projective geometry in half degree-wide cathode strips at ±60 degrees to the sense wire channels provides excellent spatial resolution and reconstruction capability. The electronic noise-to-signal ratio without preamplification is sufficiently low that individual 50 pC Geiger discharges are accurately measured and used for energy calibration. Measurements made at 14.5 GeV e± beam energy have provided preliminary spectra of Bhabhas and of photon-photon invariant mass. The latter show that ¿o´s can be reconstructed.
