Measurement of forward direct photon production in p–A at LHC with ALICE – a probe for nuclear PDFs and saturation

Apr 12, 2016, 2:28 PM
Auditorium (DESY Hamburg)


DESY Hamburg

Notkestr. 85 D-22607 Hamburg Germany


Prof. Thomas Peitzmann (Utrecht University)


Direct photon production at forward rapidity is a promising probe for the gluon content of protons and nuclei at small x. In particular, the measurement of the nuclear modification factor for direct photons in p–A collisions at the LHC should provide a crucial test for gluon saturation. We discuss the unique role of such a photon measurement in the context of other measurements at the LHC and also of possible future measurements at EIC. To allow us to perform this measurement, a new forward calorimeter (FoCal) is proposed as an upgrade to the ALICE experiment. The proposed detector covers the range 3.5 < eta < 5 which probes the gluon distributions at x ~ 10^-5 and Q ~ pT > 4 GeV. We will discuss performance studies of such a detector, which demonstrate that extremely high-granularity calorimetry is required for a successful measurement, and show a few recent results from R&D for this project.

Primary author

Prof. Thomas Peitzmann (Utrecht University)

Presentation materials