Validation of Beam Tests parameter space
Last update February 04, 2003
Goals
The main goal is to verify the number of photons expected for parameter space to be used during the LAT beam test in 2004. The exercise is done on the calibration unit, which consists of 1 x 4 towers (click here for pictures). I also wrote a code to decide which angle you want to shoot from. This helps in preparing the Monte Carlo runs. Click here the get the software.
Status
Preliminary Results - using pdrAppv7r1
The phi angle is chosen at 0 deg and we shot from the center of a single tower, x=20 cm, y =0 cm, z = 90 cm (see figures) See coordinate definitions in LAT-TD-00035-01. Out of 100 events per run the numbers we get from FstCnvLyr are shown below. If one calculates from the radiation length , the probability for conversion for zero degrees is (1-exp (-7/9*1.35)) = 65% , where 1.35 corresponds the number of radiation lengths in the tracker.
| Particle | Energy (GeV) | Q(deg) | FstCnvLyr | Comments |
| photon | 0.0176 | 3.5 | 64 | OK |
| photon | 0.0176 | 30.0 | 75 | Maybe the path is longer by 10% ? |
| photon | 0.0176 | 45.0 | 6 | Maybe we missed the tower ? |
| photon | 0.100 | 3.5 | 77 | Maybe the path is longer by 10% ? |
| photon | 0.100 | 30.0 | 74 | Maybe the path is longer ? |
| photon | 0.100 | 45.0 | 8 | Maybe we missed the tower ? |
According to Leon FstCnVLyr gives the first bilayer (we have 18 in the LAT) that has at least one silicon cluster. This is NOT identical to the conversion layer because one may have: noisy hits in the MC data, backward going daughters, or particle can go through a dead region. He also expects about 15% increase in path length at 30 degrees.