DRAFT

Results from

SLAC Experiments T-438,452 

C.G. Allgower^a, J. Balewski^a, L.C. Bland^a, V. Dunin^a,b, G. Eppley^c, T. Fieguth^d,C. Gagliardi^g, R. Iverson^d, W.W. Jacobs^a, A. Klyachko^a, A. Ogawa^e, G. Rakness^a, S. Razin^a, T. Rinckel^a, K. Solberg^a, H.M. Spinka^f, R. Tribble^g,S.E. Vigdor^a, S.W. Wissink^a

^a Indiana University Cyclotron Facility, Bloomington, IN USA

^b JINR, Dubna, Russia

^c Rice University, Houston, TX USA

^d SLAC, Stanford, CA USA

^e Penn State University, College Park, PA USA

^f Argonne National Laboratory, Chicago, IL USA

^g Texas A and M, College Station, TX USA

This report presents results from SLAC test beam runs T-438 and T-452: an in-beam test of a prototype lead+scintillator sampling calorimeter and shower-maximum detector. The experiments were conducted in the SLAC Final Focus Test Beam (FFTB) in two runs. T-438 used 14 shifts of parasitic beam time on the dates, 10/20-24/99. T-452 used 10 shifts of beam during SLAC commissioning on the dates, 1/12-16/2001. The unique properties of the FFTB at SLAC made it possible to rapidly determine the linearity of the response of the electromagnetic calorimeter (EMC). Exquisite instrumentation in the FFTB enabled the delivery of a beam containing, on average, 1.5 electrons per 1-ps long pulse at a repetition rate of 10 Hz. Beam energies of 5, 10 and 20 GeV were employed during the two runs. In addition to obtaining data with a tightly focused beam, the detailed understanding of the FFTB line made it possible to defocus the electron beam to a spot size of approximately 1 cm in diameter. Some fraction of the two-electron events have the incident electrons spatially separated by ~1 cm at the entrance to the detector. This can provide a stringent test of the shower-maximum detector, designed to discriminate a single photon from a pair of photons arising from the decay of an energetic neutral meson at STAR.

This report will be updated as results from the test runs are obtained.

Send comments to:

L.C. Bland (IUCF), for the T-438 collaboration

Last revised: 11 August 2001