First Observation of Dielectron Production in Proton-Nucleus Collisions below 10 GeV

DLS Collaboration; G. Roche; G. Claesson; D. Hendrie; G. F. Krebs; E. Lallier; A. Letessier-Selvon; H. S. Matis; T. Mulera; C. Naudet; L. Schroeder; P. A. Seidl; A. Yegneswaran; Z. F. Wang; J. Bystricky; J. Carroll; J. Gordon; G. Igo; S. Trentalange; T. Hallman; L. Madansky; J. F. Gilot; P. Kirk; D. Miller; G. Landaud

doi:10.1103/PhysRevLett.61.1069

First Observation of Dielectron Production in Proton-Nucleus Collisions below 10 GeV

G. Roche, G. Claesson, D. Hendrie, G. F. Krebs, E. Lallier, A. Letessier-Selvon, H. S. Matis, T. Mulera, C. Naudet, L. Schroeder, P. A. Seidl, A. Yegneswaran, Z. F. Wang, J. Bystricky, J. Carroll, J. Gordon, G. Igo, S. Trentalange, T. Hallman, L. Madansky, J. F. Gilot, P. Kirk, D. Miller, and G. Landaud (DLS Collaboration)

Phys. Rev. Lett. 61, 1069 – Published 29 August 1988

Abstract

We have begun a program to measure dielectron production in $p$ -nucleus and nucleus-nucleus collisions at the LBL Bevalac. Results are presented for the reaction $p + Be$ at 4.9 GeV. For the first time, direct dilepton production is observed below 10 GeV incident energy. The cross sections are discussed and compared to previous data at higher energies. The observation of a structure at a mass of about 275 MeV suggests that pion annihilation may be the dominant production mechanism in this mass range.

Received 31 May 1988

DOI:https://doi.org/10.1103/PhysRevLett.61.1069

Authors & Affiliations

G. Roche^1,*, G. Claesson^1,†, D. Hendrie^1,‡, G. F. Krebs¹, E. Lallier^1,§, A. Letessier-Selvon¹, H. S. Matis¹, T. Mulera^1,∥, C. Naudet¹, L. Schroeder¹, P. A. Seidl¹, A. Yegneswaran¹, Z. F. Wang^1,¶, J. Bystricky^2,**, J. Carroll², J. Gordon², G. Igo², S. Trentalange^2,††, T. Hallman³, L. Madansky³, J. F. Gilot^4,‡‡, P. Kirk⁴, D. Miller⁵, and G. Landaud⁶ (DLS Collaboration)

¹Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720
²University of California at Los Angeles, Los Angeles, California 90024
³The Johns Hopkins University, Baltimore, Maryland 21218
⁴Louisiana State University, Baton Rouge, Louisiana 70803
⁵Northwestern University, Evanston, Illinois 60201
⁶Université de Clermont II, Institut National de Physique Nucléaire et de Physique des Particules, 63170 Aubière, France

^*On leave from the Université de Clermont II, 63170 Aubière, France.
^†Present address: University of Lund, Lund, Sweden.
^‡Present address: U.S. Department of Energy, Washington, DC.
^§Present address: Thomson Laboratoire Central de Recherches, Orsay, France.
^∥Present address: Perkin Elmer Company, Hayward, CA 94545.
^¶Present address: Louisiana State University, Baton Rouge, LA 70803.
^**Present address: Institut National de Physique Nucléaire et de Physique des Particules, Orsay, France.
^††Present address: Rutgers University, New Brunswick, NJ 08903.
^‡‡Present address: Eidenossische Technische Hochschule, Zurich, Switzerland.