1. 16-Nov-2002Konstantin Beloous1 Digital Hadron Calorimeter Energy Resolution

2. 16-Nov-2002Konstantin Beloous2 n Some definitions n Energy resolution n Cell size n Read-out efficiency n Signal overlapping

3. 16-Nov-2002Konstantin Beloous3 Some definitions n Each distribution is fitted by Gaussian n Fit is iterative in the specified interval n  /Mean is used as energy resolution

4. 16-Nov-2002Konstantin Beloous4 n The distribution of the number of hits for the events when shower starts in HCAL is much narrower with respect to all events n But this is only small fraction of such events, about 20% n Some cuts were used to select events with the main deposits in HCAL N hits( Ecal) < 10 - 15

5. 16-Nov-2002Konstantin Beloous5 Some problems at low energies. The results of the fitting procedure is not stable with respect to changing low limit of the fitting region.

6. 16-Nov-2002Konstantin Beloous6 Energy resolution Response for K 0 L

7. 16-Nov-2002Konstantin Beloous7 Cell size Number of hits strongly depends on the size of the cell It reaches rather small value of 17 hits for cell size 5 cm This leads to some dependence in energy resolution

8. 16-Nov-2002Konstantin Beloous8 Dependence is more clear at low energy

9. 16-Nov-2002Konstantin Beloous9  E/E = 6% + 101% /  E  E/E = 0% + 160% /  E Energy resolution for different Cell size

10. 16-Nov-2002Konstantin Beloous10 Cell size & response for gamma n Response for single photon emitted at the entrance of HCAL n The number of hits is a bit smaller than for K 0 L with the same energy

11. 16-Nov-2002Konstantin Beloous11 n While the energy resolution is much better u there is no material between the starting point of the particle and its entrance to the calorimeter n Lower dependence than for K 0 L at the same energy

12. 16-Nov-2002Konstantin Beloous12 Read-out efficiency under assumption that efficiency does not depend on particle energy or position and therefore stays the same for each hit n Almost linear dependence of the number of hits on the read- out efficiency

13. 16-Nov-2002Konstantin Beloous13 Some resolution improvement when increasing the efficiency The improvement has almost the same order of magnitude for different energies

14. 16-Nov-2002Konstantin Beloous14 Signal overlapping n Charge leakage - ionization produced by passing through particle could induce charge not only on the nearest Pad but on some of it neighbors n Crosstalk - read-out of the channel could cause other channels to be fired under assumption that signal overlapping does not depend on particle energy or position and therefore stays the same for each hit

15. 16-Nov-2002Konstantin Beloous15 n Number of additionally fired cells is calculated through Poisson distribution n Energy resolution practically does not depend on signal overlapping

16. 16-Nov-2002Konstantin Beloous16 Conclusion n Some obvious dependencies of energy resolution u decreasing when the cell size increases u small improvement when the read-out efficiency increases n Energy resolution practically does not depend on signal overlapping n Choosing of the cell size can done after studying the reconstruction.