| Autor: |
Veronica Canoa Roman |
| Jazyk: |
angličtina |
| Rok vydání: |
2019 |
| Předmět: |
|
| Zdroj: |
Proceedings, Vol 10, Iss 1, p 32 (2019) |
| Druh dokumentu: |
article |
| ISSN: |
2504-3900 |
| DOI: |
10.3390/proceedings2019010032 |
| Popis: |
Direct photons are a unique probe to study the properties of the medium created in heavy ion collisions. Low transverse momentum ( p T ) direct photons are of special interest since thermal photons are supposed to be dominant, while at high p T direct photons come from initial hard scattering (pQCD). PHENIX has observed a large excess of direct photon yield as well as large azimuthal anisotropy at low p T in Au+Au collisions at the c.m.s energy per nucleon pair s N N = 200 GeV. The mechanism to produce a large direct photon yield with a large elliptic anisotropy ( v 2 ) is not well understood yet. PHENIX has made systematic measurements of direct photons with different collision energies and system configurations. It has been found that direct photon yield d N γ / d η is proportional to charge particle multiplicity ( d N c h / d η ) 1 . 25 . This behavior holds for beam energies measured both at RHIC and at the LHC in large systems. This scaling suggests that there is a transition from p+p to A+A system which could be understood with the analysis of smaller systems like p+Au and d+Au. |
| Databáze: |
Directory of Open Access Journals |
| Externí odkaz: |
|
