The Atlas Tile Calorimeter

1. The Atlas Tile Calorimeter Muon Studies at 90° Presented at CERN by Michael Borysow for the University of Michigan REU Program 14/08/03

2. Outline • Tile Calorimeter Description • What is Calorimetry? • Specifics to the Atlas Tile Calorimeter • My Analysis • Muons at 90 Degrees • Discoveries • Conclusions

3. Atlas Overview • Four Major Components • Inner Tracker • Calorimeter – Electromagnetic • Calorimeter – Hadronic • Muon Spectrometer • Magnet System

5. What is Calorimetry? • Calorimetry refers to the detection of particles through total absorption in a block of matter. • Calorimetry is a destructive method. • The only exceptions being muons. • Muons can penetrate substantial amounts of mass represented by the calorimeter, thus they become ID’d as muons. • True Calorimeters measure the total energy of a particle and are made of a single substance, such as Germanium or NaI crystal. • The Atlas Tile Calorimeter is a Sampling Calorimeter.

6. Sampling Calorimeters • Sampling Calorimeters are made of more than one substance • Active Medium • Generates light or charge that forms the basis of the calorimeter signal • Passive Medium • Absorbs energy • In Sampling Calorimeters, only a small fraction of the energy is deposited in the active medium. • The advantage of a Sampling Calorimeter is that it is much cheaper and smaller. • The goal is still to stop the particle, and the passive medium can help do this much more quickly.

7. Benefits of a Calorimeter • Calorimeters, with tracking data, allow for effective identification of particles. • Can measure the energy of neutral particles, whereas a magnetic spectrometer cannot. • Fast Response time; Can be used as a trigger for other detector components.

8. The Tile Calorimeter • Made of 64x4 submodules • Two Long Barrels • Two Extended Barrels • Each submodule is composed of alternating tiles of polystyrene and steel separated into 11 tile rows. • Polystyrene is the active medium, while steel is the passive medium.

9. Long Barrels Extended Barrels

12. The Tile Calorimeter • Polystyrene acts as a scintillating material. • Through various processes, molecules and atoms will become excited, and then emit light when they drop to the ground state. • The scintillation light is picked up by wavelength shifting fibers (WSF) and carried to Photo Multiplier Tubes (PMTs). • The PMTs then produce an electronic signal, which is digitized and sent to the Data Acquisition Systems.

14. Cell Layout • Each cell can be read out individually in two channels. • Each cell has WSFs which on either side. These fibers carry the light to the PMT. • WSFs are used, because the light emitted by the scintillation process is ~100 nm. The PMTs are most sensitive around ~550nm.

15. Studies at 90° • Studies at 90 degrees are used to check tile row uniformity. • Muons are made use of for the reason that they deposit the roughly the same energy in each cell (per Tile) as they pass through the detector. • Thus, muons are useful for detecting bad equipment.

17. Tile Row Uniformity

18. Channel Uniformity per Row

19. Channel Summary

20. Distribution of Channel Response

21. Geometry Problems? • Currently investigating possibility of misalignment of the test setup.

22. Acknowledgements • Jean Krisch, Homer Neal, and Tom Dershem • My Adviser, Richard Teuscher • The Argonne Boys • University of Michigan • National Science Foundation • Ford Motor Company