Eur. Phys. J. A (2011) 47: 63
https://doi.org/10.1140/epja/i2011-11063-x

Regular Article - Experimental Physics

pp and ππ intensity interferometry in collisions of Ar+KCl at 1.76A GeV

¹ Laboratori Nazionali del Sud, Istituto Nazionale di Fisica Nucleare, 95125, Catania, Italy
² LIP-Laboratório de Instrumentação e Fısica Experimental de Partıculas, 3004-516, Coimbra, Portugal
³ Smoluchowski Institute of Physics, Jagiellonian University of Cracow, 30-059, Kraków, Poland
⁴ GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291, Darmstadt, Germany
⁵ Institut für Strahlenphysik, Helmholtz-Zentrum Dresden-Rossendorf, 01314, Dresden, Germany
⁶ Joint Institute of Nuclear Research, 141980, Dubna, Russia
⁷ Institut für Kernphysik, Johann Wolfgang Goethe-Universität, 60438, Frankfurt, Germany
⁸ II.Physikalisches Institut, Justus Liebig Universität Giessen, 35392, Giessen, Germany
⁹ Sezione di Milano, Istituto Nazionale di Fisica Nucleare, 20133, Milano, Italy
¹⁰ Institute for Nuclear Research, Russian Academy of Science, 117312, Moscow, Russia
¹¹ Physik Department E12, Technische Universität München, 85748, München, Germany
¹² Department of Physics, University of Cyprus, 1678, Nicosia, Cyprus
¹³ Institut de Physique Nucléaire (UMR 8608), CNRS/IN2P3 - Université Paris Sud, F-91406, Orsay Cedex, France
¹⁴ Nuclear Physics Institute, Academy of Sciences of Czech Republic, 25068, Rez, Czech Republic
¹⁵ Departamento de Fısica de Partıculas, Universidad de Santiago de Compostela, 15706, Santiago de Compostela, Spain
¹⁶ Instituto de Fısica Corpuscular, Universidad de Valencia-CSIC, 46971, Valencia, Spain
¹⁷ Excellence Cluster Universe, Technische Universität München, 85748, Garching, Germany
¹⁸ ISEC Coimbra, Coimbra, Portugal
¹⁹ Dipartimento di Fisica, Università di Milano, 20133, Milano, Italy
²⁰ Technische Universität Dresden, 01062, Dresden, Germany
²¹ Lawrence Berkeley National Laboratory, 94720, Berkeley, CA, USA
²² Dipartimento di Fisica Generale, Università di Torino, 10125, Torino, Italy

^* e-mail: kotte@fzd.de

Received: 28 October 2010
Revised: 1 February 2011
Accepted: 16 April 2011
Published online: 20 May 2011

Abstract

Results on pp, π⁺π⁺, and π⁻π⁻ intensity interferometry are reported for collisions of Ar+KCl at 1.76A GeV beam energy, studied with the High Acceptance Di-Electron Spectrometer (HADES) at SIS18/GSI. The experimental correlation functions as a function of the relative momentum are compared to model calculations allowing the determination of the space-time extent of the corresponding emission sources. The ππ source radii are found significantly larger than the pp emission radius. The present radii do well complement the beam-energy dependences of Gaussian source radii of the collision system of size A + A ≃ 40 + 40 . The pp source radius at fixed beam energy is found to increase linearly with the cube root of the number of participants. From this trend, a lower limit of the pp correlation radius is deduced.