Photoproduction of J/psi and of High Mass e+e- in Ultra-Peripheral Au+Au Collisions at sqrt ^S_NN = 200 GeV

Journal Article · Thu Jan 01 00:00:00 EST 2009 · Physics Letters B

DOI:https://doi.org/10.1016/j.physletb.2009.07.061· OSTI ID:963397

Afanasiev, S. ^[1]; Awes, Terry C ^[2]; Cianciolo, Vince ^[2]; Enokizono, Akitomo ^[3]; Read, Jr, Kenneth F ^[2]; Silvermyr, David O ^[2]; Sorensen, Soren P ^[4]; Stankus, Paul W ^[2]; Young, Glenn R ^[2]

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1. Joint Institute for Nuclear Research, Dubna, Russia
2. ORNL
3. Oak Ridge National Laboratory (ORNL)
4. University of Tennessee, Knoxville (UTK)

We present the first measurement of photoproduction of J/{Psi} and of two-photon production of high-mass e{sup +}e{sup -} pairs in electromagnetic (or ultra-peripheral) nucleus-nucleus interactions, using Au + Au data at {radical}S{sub NN} = 200 GeV. The events are tagged with forward neutrons emitted following Coulomb excitation of one or both Au* nuclei. The event sample consists of 28 events with m{sub e{sup +}e{sup -}} > 2 GeV/c{sup 2} with zero like-sign background. The measured cross sections at midrapidity of d{sigma}/dy (J/{Psi} + Xn,y = 0) = 76 {+-} 33(stat) {+-} 11(syst) {micro}b and d{sup 2}{sigma}/dm dy(e{sup +}e{sup -} + Xn, y = 0) = 86 {+-} 23(stat) {+-} 16(syst) {micro}b/(GeV/c{sup 2}) for m{sub e{sup +}e{sup -}} {element_of} [2.0,2.8] GeV/c{sup 2} have been compared and found to be consistent with models for photoproduction of J/{Psi} and QED based calculations of two-photon production of e{sup +}e{sup -} pairs.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 963397
• Journal Information: Physics Letters B, Vol. 679, Issue 4
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
COULOMB EXCITATION
CROSS SECTIONS
NEUTRONS
NUCLEI
PHOTOPRODUCTION
PRODUCTION