Diffraction Dissociation — 50 Years later

Abstract

The field of Diffraction Dissociation, which is the subject of this workshop, began 50 years ago with the analysis of deuteron stripping in low energy collisions with nuclei. We return to the subject in a modern context-deuteron dissociation in √ s NN = 200 GeV d-Au collisions recorded during the 2003 RHIC run in the PHENIX experiment. At RHIC energy, d→n+p proceeds predominantly (90%) through Electromagnetic Dissociation and the remaining fraction via the hadronic shadowing described by Glauber. Since the dissociation cross section has a small theoretical error we adopt this process to normalize other cross sections measured in RHIC.

Cold-Nuclear-Matter Effects on Heavy-Quark Production at Forward and Backward Rapidity ind+AuCollisions atsNNAdare1, Aidala2, Ajitanand3 et al. 2014Phys. Rev. Lett.635350View full textAdd to dashboardCite

“…Previous results in d þ Au collisions at midrapidity show a significant enhancement of heavy-flavor electrons at moderate p T [17]. In this Letter, we present measurements of the p T spectra and the nuclear-modification factor (R dA ) of [18], and this selection covers 88 AE 4% (55 AE 5%) of the total d þ Au (p þ p) inelastic cross section [19]. The integrated luminosity, sampled using single muon triggers [8] in coincidence with the minimum-bias trigger, used for this analysis of d þ Au (p þ p) collisions is 50 nb −1 (10 pb −1 ).…”

Diffraction at the LHC: a non-technical introduction

“…The PHENIX experiment studied dissociation of the deuteron in relativistic d-Au collisions [14] and observed both the Serber process and the Glauber one through the outgoing proton and neutron. At high energies dissociation, which has a significant contribution from photodissociation, is used as a basis for calculating other cross sections in d-Au collisions in PHENIX.…”

The role of Spectator Fragments at an electron Ion collider

“…Currently PHENIX is analyzing a larger sample where it should be possible to use the neutron spectators, measured in the ZDC, to extract the incoherent cross section. PHENIX also measured the electromagnetic breakup cross section in deuteron-Au collisions detecting the neutrons from the deuteron [9].…”

“…As we already mentioned, measurement of coherent scattering off heavy nuclei at −t = p 2 t ≥ 0.02GeV 2 that is near and beyond the first minimum, presents a challenge due to the contribution of the excited levels. At the same time in the case of 238 U the situation may be more promising because the threshold for fission is close to 1 MeV which means a typical Figure 5: Performance of PHENIX forward proton calorimeter in the deuteron photodissociation analysis [9]. The predominant background is the deuteron stripping process in which the proton breaks up.…”