1. Development of Digital Hadron Calorimeter Using GEM Shahnoor Habib For HEP Group, UT Arlington Oct. 12, 2002 TSAPS Fall ’02, UT Brownsville Simulation of GEM using available software

2. Oct. 12, 2002DHCAL with GEM TSAPS Fall ‘02, S. Habib, UTA 2 Introduction Linear Collider –A future HEP accelerator which studies forces in nature –Use electron-positron collisions for the study –High center of mass energies: 500GeV-3TeV Examples of Linear Collider – TESLA – (Tera Electon Volt Energy SuperConducting Linear Collider) Germany – NLC – Next Generation Linear Collider in the US – JCL – Japan Linear Collider For the HEP research at the LC – Need a good jet energy resolution of the calorimeter Use a Technique called Energy Flow Algorithm Need high granularity  More readout channels Need to control costs  Digital hadron calorimeter a solution Couple of designs for DHCAL depending on sensitive gap – Scintillation counter, GEM, RPC (Resistive Plate Chamber)

3. Oct. 12, 2002DHCAL with GEM TSAPS Fall ‘02, S. Habib, UTA 3 The gas electron multiplier (GEM) consists of a thin, metal- clad polymer foil, chemically pierced by a high density of holes. How does it work? GEM as a detector or as an pre-amplifier Large overall gains (10 4 with spark probabilities per incident pion less than 10 -10 ) in harsh radiation environment. Fast response (50ns drift time for 10mm gap with ArCO 2 ) Relatively low voltage (A few 100V compared to 10-16KV for Resistive Plate Chamber) Reasonable cost (Foils are basically copper-clad kapton - $4 for a specially prepared framed 1cm 2 ) Why GEM?

4. Oct. 12, 2002DHCAL with GEM TSAPS Fall ‘02, S. Habib, UTA 4 Ionization electrons released by ionization fall thru the holes and get amplified in the electric field represented by red & green lines and then drift to collection regions. Large amplification

5. Oct. 12, 2002DHCAL with GEM TSAPS Fall ‘02, S. Habib, UTA 5

6. Oct. 12, 2002DHCAL with GEM TSAPS Fall ‘02, S. Habib, UTA 6 Discharge Characteristics of GEM Important characteristic for reasonable calorimeter To see the discharge characteristics of GEM without using GEM because GEM is still under design and construction stage I had to simulate GEM using computer software that is available for High Energy Physics. Default geometry and then later GEM geometry Study single particle events

7. Oct. 12, 2002DHCAL with GEM TSAPS Fall ‘02, S. Habib, UTA 7 Software used in the simulation Detector simulation involve –Event generation –Detector simulation of the event –Reconstruction –Analysis Software used for event generation is Pandora_Pythia version 3.2. Software used for Detector simulation is Mokka and the default detector is TDR- TESLA Design Report. Program ROOT for analysis

8. Oct. 12, 2002DHCAL with GEM TSAPS Fall ‘02, S. Habib, UTA 8 Mokka Detector Simulation Mokka is full detector simulation for the TESLA detector calorimeter. Mokka has been used extensively for the TESLA T.D.R calorimeter energy flow studies. Advantage of Mokka is that it is object oriented program and hence provides a facility to add sub detector of our design to replace Mokka’s default sub-detector and that is going to be our next stage. This is the stage on which my colleague Venkat is going to give a talk.

9. Oct. 12, 2002DHCAL with GEM TSAPS Fall ‘02, S. Habib, UTA 9 TESLA TDR Ecal – Electromagnetic Calorimeter Material: W/G10/Si/G10 plates (in yellow) 1mm W absorber plates 0.5 mm thick Si, embeded 2 G10 plates of 0.8 mm each Hcal – Hadronic Calorimeter Material: 18 mm of Fe 6.5 mm of Polystyrene scintillator (in green)

10. Oct. 12, 2002DHCAL with GEM TSAPS Fall ‘02, S. Habib, UTA 10 Single Pion Studies 1000 single pion events using Mokka particle gun command. –Mokka produced 1000 hits file for ecal –1000 hits files for hcal –kinematics information on primary particles in the files Energies of Incident particle –5 - 200 GeV Developed an analysis program to read total energies deposited per pion for each incident energy. –Mean Energy vs Incident pion energies –Energy conversion from the slope of the straight line –Conversion factor is 3.54% and agrees with the computed sampling fraction

11. Oct. 12, 2002DHCAL with GEM TSAPS Fall ‘02, S. Habib, UTA 11

12. Oct. 12, 2002DHCAL with GEM TSAPS Fall ‘02, S. Habib, UTA 12

13. Oct. 12, 2002DHCAL with GEM TSAPS Fall ‘02, S. Habib, UTA 13

14. Oct. 12, 2002DHCAL with GEM TSAPS Fall ‘02, S. Habib, UTA 14 Conclusion Digital Hadron Calorimeter augmented with Energy Flow is a possible solution for obtaining good jet energy resolution UTA is developing a DHCAL with GEM as the sensitive gap Sanity check of the analysis package completed After the successful installation and testing of Pandora_Pythia, Mokka and Root, the next steps are to – incorporate GEM geometry in the Mokka TDR detector and study the discharge characteristics of GEM. –Run LCDRoot for reconstruction of events –Study characteristics of GEM-DHCAL