# Presentation: 087964

## CAT meeting 

- VLIMANT Jean-Roch 	LPNHE		 8 july 2003

- _T42 noise suppresion_
- _Toward killing mode_
- www-d0.fnal.gov/~vlimant/noise-suppdescr/Description.html

- Threshold study
- Effects on unclestered energy
- Effects on electrons
- Conclusions

## Energy loss vs pTLook at reconstructed EM cluster that have a MONTE CARLO electron match

- T32.5

- T52.5

- T43

- T53

## Threshold study MC

- T5x/Tx3 are bad : too high rejection of signal in inner/outter shell of the cluster
- T32.5 shows best results but isolated gaussian noise rejection will be very bad (50 times less than with T4x)
- T4,2.5 is good : low energy reduction and sharp isolated noise rejection
- T42 will be even better (could not try it due to offline zero supression)
- pT of the fake EM objects is twice more reduced than for true EM cluster (not shown)

- T42.5

## Energy loss vs Energy Look at reconstructed EM cluster Emid+trackmatch in Zee picked DATA sample 

- T32.5

- T52.5

- T43

- T53

## Threshold study Data

- 0.6 ‰ transverse energy reduction
- Expect even better result with actual T42

- T42.5

## MEt and unclustered Et qcd sample (recoT)

- (x)MET

- (y)UnET

- NO T42

- T42

- (y)UnET

## Set versus Scalar unclustered energy

- NO T42

- T42

## Unclustered energyfrom recoT file (run 174234)

- The unclustered transverse energy goes from  8.8 to 6.3 GeV (30% less) while missing transverse energy is 14 to 12 GeV11% less : Mostly unclustered energy rejection
- MET and unclestered energy are getting more correlated at low MET (from 18% to 31%) : reducing the number of « fake  » clusters
- Scalar unclustered Energy increases; no low SuncE
- Less energy in the calo (SeT decreases), some objects go unclustered (correlation increases), the released energy goes unclustered (SuncE increases) and phi distribution becomes more uniform (UnT decreases) :

## Peaks and odd features are removed

- Before

- After

- Rejected

- Smoothing effect

## Effect on Electronsfrom calorimeter cluster

- 30% more EMid objects
- 18% more EMid+track match objects(electrons)
- Mostly at low energy

- Difference

## EMid efficiency at high energy 

- EMid efficiency at high energy

- no T42

- Method : use diem events, Probe is a track matched EM cluster and Tag is a tight electron back to back with the Probe

## Effect on Electrons

- T42

## J/Ψ mass with cluster electrons

-  T42

- no T42

- 48 tights events in the mass window 2.5-3.5 without increasing the background

## Effect on Electrons from Road Method

- Tiny gain ( 8.10-2%) at low energy ( improvement limited by the number of isolated tracks )

- Difference

## Effect on Soft Electrons

-  T42

- no T42

## Effect on Soft Electrons

-  T42

- no T42

## Summary on  EM objects

- From calorimeter cells clustering

- EMiD was 90.02.8 % is 90.32.7 %

- Slightly more J/Psi
- Better Soft Electron Tag efficiency

- Same efficiency in central region
- Fake rate not estimated yet

- TighSoftEl was 887 % is 927 %

- From Road method

## Effect on mEtx

## Effect on mEty

## Effect on missing energy

- Less missing energy
- Better resolution
- Met-x,y Distributions now centered at zero

- x y decreases by 30%
- <SEt> decreases by 30%
- <mEt> decreases by 10%

## Summary and reminder

- T42 algorithm removes 40% of cells which represents 30% of the unclustered Et and 0.06‰ of EM objects pT
- without modifying calorimeter physics (even improves it)
- smoothes the occupancy distributions
- Still beam pipe BLS over-occupancy (we cannot do much)
- Strong evidence of noise rejection
- Negative/Positive rejection is symetrical
- Mostly unclustered ET reduction
- pT of fakes are more reduced
- MEt is better
- Identification of calorimeter based objects within ||=2.5 is improved even though studied on biased (skimmed) samples
- T42 improves the data quality so we suggest T42 be set in killing mode
- Keep trace of killed cells in Calt42Chunk (code for thumbnail is being coded)