1. 1 PP Minimum Bias Triggering Simulations Alan Dion Stony Brook University

2. 2 A simple event generator to simplify simulations Geometry Triggering algorithm Results without noise Results with noise Conclusions Outline

3. 3 Event generator for pp minimum bias events N ch given by a negative binomial distribution Kinematic distribution of particles: assume p t, h, and f factorize Random distribution in f For h, assume constant distribution for | h | < 2, and distribution decreases linearly to 0 at h = 6

4. 4 For p t, use fit to UA1 spectrum Simple field approximation Df Df /2 h R1R1 Constant 1.2 T cylindrical field with detector layers at R 1 and 2 R 1

5. 5 Geometry 2 pixel layers, one at R=2.5 cm and the other at R=5 cm Utilize the fast OR of all pixels in a given chip For given z, inner layer has 10 channels and outer layer has 20 (in f ) Each layer has 16 channels in z for given f 2 30 degree gaps in f coverage 95% channel efficiency

6. 6 Triggering algorithm Find all f channels in the inner layer which have a hit and a corresponding hit in one of the 2 channels in outer layer with the same f For each such channel, pair each outer hit and inner hit, and fill 3 bins along the beam axis. Each bin has the same size as a detector channel. Find the bins on the beam axis which have the maximum number of hits. If all such bins are within the acceptance, then we trigger.

7. 7 Dependence on z vertex

8. 8 Dependence on N ch

9. 9 Noise Efficiency = # triggered events in acceptance / # events in acceptance Rejection = # non-triggered events outside acceptance / # events outside acceptance

10. 10 To do Get realistic figures for the channel efficiency, geometry, etc. Get estimate for the noise per chip The algorithm can easily be improved to make noise less of a problem