Measurement of the Centrality Dependence of Charge Particle Pseudorapidity Density with the PHOBOS Detector

April 29, 2001

APS Meeting: Washington, DC

Page 4

Selecting Collisions

Negative Paddles

Positive Paddles

ZDC N

ZDC P

• Coincidence between Paddle counters

• Paddle + ZDC timing reject background

Sensitive to 97% of inelastic cross-section for Au+Au at ÖsNN = 130 GeV