Interferometry of Direct Photons in CentralPb208+Pb208Collisions at158A GeV

M M Aggarwal,T H Shah,I Kosarev,D Silvermyr,K Karpio,T K Nayak,H Delagrange,V Nikitine,G Stefanek,M P Decowski,L Luquin,N Slavine,T Bernier,T Siemiarczuk,I Koutcheryaev,V Avdeitchikov,V S Bhatia,B W Kolb,K Söderström,L Tykarski,S C Phatak,Y Schutz,P Nomokonov,K Enosawa,S Vörös,B Mohanty,I Sibiriak,O Gavrishchuk,V Antonenko,R Santo,S Nikolaev,H Schlagheck,G Sood,Y Miake,T Peitzmann,S K Badyal,G Roland,K Reygers,M Ippolitov,V Manko,J M Rubio,W Pinganaud,S Nishimura,B Batiounia,E Stenlund,G C Mishra,S K Nayak,I Roufanov,G R Young,S Fokin,R Glasow,J Rak,C Blume,R Raniwala,K El Chenawi,A Tsvetkov,A Maximov,S Bathe,D P Mahapatra,J Nystrand,F J M Geurts,H Kalechofsky,B Wysłouch,M S Ganti,H Naef,K B Bhalla,I Otterlund,A K Dubey,A Lebedev,T C Awes,P Steinberg,Y P Viyogi,B K Nandi,M R Dutta Majumdar,V Astakhov,L Rosselet,P Kulinich,M L Purschke,A Nianine,S Garpman,Z Ahammed,H Büsching,S Raniwala,P Nilsson,D Bucher,V Arefiev,H Löhner,C Roy,K Karadjev,G Shabratova,Subhasis Chattopadhyay ,P Dönni ,A.s Vodopianov ,Tomas Svensson ,A Öskarsson ,F Plášil ,Michel Martin ,N.v Eijndhoven ,S Sambyal ,Susumu Sato ,M J Mora ,H.h Gutbrod ,M Šumbera ,V Petráček ,N Kameswara Rao ,T V Moukhanova ,S Sörensen ,D Yu Peressounko ,H.-Å Gustafsson ,Masahiro Kurata ,Tushar K Ghosh ,I Hřivnáčová ,L Carlén ,А Виноградов ,В Фролов ,D P Morrison ,P W Stankus ,B.n Gus'kov ,Bikash Sinha ,P.v.k.s Baba ,A.l.s Angelis ,G Martı́nez ,А Куглер ,D Mukhopadhyay ,E C V D Pijll ,H R Schmidt ,G J Van Nieuwenhuizen ,F Retière

doi:10.1103/physrevlett.93.022301

Abstract

Two-particle correlations of direct photons were measured in central 208Pb+208Pb collisions at 158A GeV. The invariant interferometric radii were extracted for 100<K(T)<300 MeV/c and compared to radii extracted from charged pion correlations. The yield of soft direct photons, K(T)<300 MeV/c, was extracted from the correlation strength and compared to theoretical calculations.

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