1. HCAL Leakage Studies CLIC Physics & Detector Meeting 10. November 2008 Christian Grefe CERN

2. Page 2 10. November 2008, Christian Grefe HCAL Leakage Studies Overview ● investigate impact of HCAL depth in order to make a reasonable choice for CLIC 001 ● energy deposits depending on particle energy and HCAL depth ● in HCAL ● in coil ● in a possible tail catcher ● effects of reduced coil material (2λ vs 1λ) ● first glimpse on possible corrections for energy lost in coil ● using TMVA (Toolkit for Multivariate Data Analysis)

3. Page 3 10. November 2008, Christian Grefe HCAL Leakage Studies HCAL stack ● using the CLIC000 HCAL structure: ● 200 layers of tungsten (2cm tungsten + 0.5cm scint ≈ 0.2 λ per layer ) ● fully contained showers (40 λ ) ● no dedicated ECAL or coil structure ● parameter scan for λ vs (single) particle energy ● virtually cutting out 2λ afterwards at different positions to represent the coil ● simulated 1000 π+ events for different energies ● 1, 2, 4, 8, 16, 25, 50, 75, 100, 125, 150, 200 GeV

4. Page 4 10. November 2008, Christian Grefe HCAL Leakage Studies Energy deposit - HCAL+ECAL

5. Page 5 10. November 2008, Christian Grefe HCAL Leakage Studies Energy deposit – coil (2λ)

6. Page 6 10. November 2008, Christian Grefe HCAL Leakage Studies Energy deposit – coil (2λ)

7. Page 7 10. November 2008, Christian Grefe HCAL Leakage Studies Energy deposit – tail (2λ coil)

8. Page 8 10. November 2008, Christian Grefe HCAL Leakage Studies Fraction of events contained in Calorimeter

9. Page 9 10. November 2008, Christian Grefe HCAL Leakage Studies Energy deposit – thinner coil (1λ)

10. Page 10 10. November 2008, Christian Grefe HCAL Leakage Studies Energy deposit – thinner coil (1λ)

11. Page 11 10. November 2008, Christian Grefe HCAL Leakage Studies Lost energy reconstruction (Peter Speckmayer) ● using TMVA (Toolkit for Multivariate Data Analysis) ● some shower variables have been created ● energy-weighted position of the shower ● shower center (in z and r) ● RMS as shower length and width ● energy density of the shower ● two methods used for regression analysis ● linear model ● PDERS (probability density estimator – range search) ● information used for the reconstruction is from full HCAL and 1 λ tail catcher for different coil positions (6λ and 9λ ECAL+HCAL depth) and 2λ of coil material

12. Page 12 10. November 2008, Christian Grefe HCAL Leakage Studies Lost energy reconstruction ● PDERS vs linear model for ECAL+HCAL depth of 6 λ and 9 λ

13. Page 13 10. November 2008, Christian Grefe HCAL Leakage Studies Lost energy reconstruction

14. Page 14 10. November 2008, Christian Grefe HCAL Leakage Studies Conclusion & Outlook ● this work is a basis for a reasonable choice of HCAL depth towards clic001 ● reconstructing the lost energy in the coil is possible to a certain extend ● no optimization of the algorithms yet ● using the high granular cell information could improve this ● additional information from particle flow might improve it further ● remember that this is a worst case scenario (90deg particles in the barrel) ● repeat the exercise for jets (up to 1.5 TeV) ● verify the results with a more realistic stack for a few λ-points (realistic ECAL and coil regions)