# Quark Matter 2018

May 13 – 19, 2018
Venice, Italy
Europe/Zurich timezone
The organisers warmly thank all participants for such a lively QM2018! See you in China in 2019!

## Direct photon production at low pT in small systems with ALICE

May 15, 2018, 5:00 PM
2h 40m
First floor and third floor (Palazzo del Casinò)

### First floor and third floor

#### Palazzo del Casinò

Poster Electromagnetic and weak probes

### Speaker

Mike Henry Petrus Sas (Nikhef National institute for subatomic physics (NL))

### Description

Measurements of low $p_{\rm T}$ direct photon production at midrapidity in pp collisions at $\sqrt{s}=2.76$ and 8 TeV, as well as in p-Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV were carried out by the ALICE experiment at the LHC. Photons were detected with either of the two electromagnetic calorimeters, EMCal and PHOS, and via reconstruction of $e^+e^-$ pairs from conversions in the ALICE detector material using the central tracking system. Where possible the results were combined for the inclusive photon spectra. An additional hybrid method, combining the conversion information with that of the calorimeters, was included in our best estimate of the direct photon excess ratio $R_{\gamma}$, as well as the extraction of direct photon spectra or their upper limits. Below $3$ GeV/$c$, $R_\gamma$ was found to be consistent with unity in all of the investigated collision systems. Furthermore, the direct photon spectra will be compared to pQCD next-to-leading order calculations.

Content type Experiment ALICE Presenter name already specified