# Presentation: 810705

## Clean-up of the energy sharing problemand effects on EM objects, jets, MET

- Jan Stark, LPSC Grenoble

- Work done with the CATF.
- Many thanks to Dean Schamberger for all his help.

- D0 workshop, Beaune, June 16-20, 2003

## The energy sharing problem

- One of the BLS boards in a backplane was not letting go of
- the analog bus when it should.
-  charge (energy) read from this particular board is fine
-  for the other boards on the backplane we see the average
-      of their own charge and the charge of the bad board
- Six bad boards in total (not all during exactly the same time).
- This means:
-  if charge in bad board (and no charge in the other boards)
-    see seven more boards with half the energy of the
-        bad board
-  if charge in one of the other boards (and none in the bad
-   board)
-    see only half of the “real” energy in the other board

- Same event as above, but energy rather than
- transverse energy is shown.

- eta bin

- phi bin

- The worst bad boards affect data taken from February to April.

- D0 workshop, Beaune, June 16-20, 2003

- Jan Stark

## Strategy for the correction

- We know which boards were bad during which period of time (which runs)
- 	 can invert charge averaging.
- To do this for a given event, we need to know the raw number of ADC counts and the gain path
- for each of the affected cells.
- This information is available in the RAW data files. A good place to apply the correction is
- therefore d0reco running over RAW data files.
- But reprocessing RAW data is a heavy burden. It is desirable to have code that applies the
- correction at DST or TMB level.
- Inconveniences of DST/TMB:
-  gain information is not available
-  less information on very low energy cells than in RAW files (offline zero-suppression)
-  finite precision on number of ADC counts due to packing
- Correction at DST/TMB level requires some approximations
- 	 correction less accurate, but still possible.
- Two versions of the correction code have been written; one that works at RAW level, and another
- one that works at DST/TMB level. Will first show some results obtained with RAW data, and then
- discuss differences RAW  DST/TMB.

- D0 workshop, Beaune, June 16-20, 2003

- Jan Stark

## An event with energy in one of the bad BLS boards

- An event with energy in one of the bad BLS boards

- Before correction:

- After correction:

| eta | phi | pT | EM frac | CH frac |
| --- | --- | --- | --- | --- |
| 1.0177
0.9464 | 50.49
213.00 | 37.22
12.66 | 0.680
0.621 | 0.188
0.047 |

- 2 jets

| eta | phi | pT | EM frac | CH frac |
| --- | --- | --- | --- | --- |
| 1.0735
0.9464 | 47.79
213.00 | 8.86
12.66 | 0.832
0.621 | 0.000
0.047 |

- 2 jets

| eta | phi | pT | EM frac | isolation | HMx8 |
| --- | --- | --- | --- | --- | --- |
| 1.0930 | 51.00 | 10.39 | 0.791 | 0.078 | 493.2 |

- 1 EM

- 0 EM

- D0 workshop, Beaune, June 16-20, 2003

- Jan Stark

## Different views of the same event(after correction)

- D0 workshop, Beaune, June 16-20, 2003

- Jan Stark

## Energy in one of the “other boards”

- Before correction:

- After correction:

| eta | phi | pT | EM frac | CH frac |
| --- | --- | --- | --- | --- |
| 2.3725
0.8637 | 171.65
12.11 | 11.35
11.92 | 0.398
0.316 | 0.000
0.059 |

- 2 jets

- 2 jets

| eta | phi | pT | EM frac | isolation | HMx8 |
| --- | --- | --- | --- | --- | --- |
| 0.1078 | 265.52 | 5.13 | 0.838 | 0.086 | 26.21 |

- 1 EM

- 1 EM

| eta | phi | pT | EM frac | isolation | HMx8 |
| --- | --- | --- | --- | --- | --- |
| 0.1078 | 265.52 | 5.13 | 0.838 | 0.086 | 26.21 |

| eta | phi | pT | EM frac | CH frac |
| --- | --- | --- | --- | --- |
| 2.3586
0.8637 | 171.59
12.11 | 15.24
11.92 | 0.340
0.316 | 0.000
0.059 |

- D0 workshop, Beaune, June 16-20, 2003

- Jan Stark

## Can also lead to loss of calo objects ...

- Before correction:

- After correction:

| eta | phi | pT | EM frac | CH frac |
| --- | --- | --- | --- | --- |
| 0.6651
0.8293 | 115.77
295.34 | 36.57
25.53 | 0.95
0.70 | 0.035
0.082 |

- 2 jets

- 3 jets

- 1 EM

- 1 EM

| eta | phi | pT | EM frac | isolation | HMx8 |
| --- | --- | --- | --- | --- | --- |
| 0.7088 | 114.16 | 29.21 | 1.01 | 0.094 | 24.51 |

| eta | phi | pT | EM frac | isolation | HMx8 |
| --- | --- | --- | --- | --- | --- |
| 0.7088 | 114.16 | 29.21 | 1.01 | 0.094 | 24.51 |

| eta | phi | pT | EM frac | CH frac |
| --- | --- | --- | --- | --- |
| 0.6651
0.8293
-1.1667 | 115.77
295.34
105.05 | 36.57
25.53
8.82 | 0.95
0.70
0.30 | 0.035
0.082
0.199 |

- D0 workshop, Beaune, June 16-20, 2003

- Jan Stark

## (continued)

- Tower transverse energy (GeV)
- before correction

- Tower transverse energy (GeV)
- after correction

- Tower transverse energy difference
- | before – after |    (GeV)

- Tiny correction pushes jet candidate “over the edge”.

- D0 workshop, Beaune, June 16-20, 2003

- Jan Stark

## A slightly more tricky event

- Before correction:

- After correction:

| eta | phi | pT | EM frac | CH frac |
| --- | --- | --- | --- | --- |
| 3.4157
0.7291
0.4590
-0.9343 | 1.22
195.59
316.08
87.21 | 22.86
16.92
10.34
16.93 | 0.93
0.84
0.55
0.19 | 0.000
0.082
0.117
0.117 |

- 4 jets

- 5 jets

- 1 EM

- 2 EM

| eta | phi | pT | EM frac | isolation | HMx8 |
| --- | --- | --- | --- | --- | --- |
| 3.4456
-1.9700 | 359.96
357.66 | 25.77
1.51 | 0.89
1.05 | 0.180
0.164 | 277.16
84.05 |

| eta | phi | pT | EM frac | isolation | HMx8 |
| --- | --- | --- | --- | --- | --- |
| 3.4456 | 359.96 | 25.77 | 0.89 | 0.180 | 277.16 |

| eta | phi | pT | EM frac | CH frac |
| --- | --- | --- | --- | --- |
| 3.4157
0.7291
0.4590
-0.9498
-0.8095 | 1.22
195.59
316.08
61.89
110.02 | 22.86
16.92
10.34
9.13
9.45 | 0.93
0.84
0.55
0.21
0.19 | 0.000
0.082
0.117
0.152
0.082 |

- jet
- split !

- D0 workshop, Beaune, June 16-20, 2003

- Jan Stark

## (continued)

- Tower transverse energy (GeV)
- before correction

- Tower transverse energy (GeV)
- after correction

- Tower transverse energy difference
- | before – after |    (GeV)

- D0 workshop, Beaune, June 16-20, 2003

- Jan Stark

## Number of jets and EM objects

- Take 900 events reconstructed once without correction and once with correction. Compare number of jet
- candidates and number of EM candidates in a given event before and after correction.

- log scale

- log scale

- N(jets)
- after - before

- N(EM objects)
- after - before

- D0 workshop, Beaune, June 16-20, 2003

- Jan Stark

## “Modified” jets

- Let’s have a closer look at jets that are found both before and after the correction,
- but with different properties. The plots below compare the transverse momentum
- before and after the correction for this type of jets.

- jet pT
- after – before correction

- jet pT
- after – before
-       after

- D0 workshop, Beaune, June 16-20, 2003

- Jan Stark

## “Modified” jets (continued)

- jet 
- after – before

- jet  (rads)
- after – before

- jet EM fraction
- after – before

- jet CH fraction
- after – before

- D0 workshop, Beaune, June 16-20, 2003

- Jan Stark

## Impact on missing ET

- To estimate the impact of the shared energy problem on missing ET, plot distribution of missing ET for the
- first 51k events of run 175054 before and after the correction.

- log scale

- log scale

- log scale

- GeV

- GeV

- GeV

- missing ET before correction

- missing ET after correction

- difference
- after - before

- D0 workshop, Beaune, June 16-20, 2003

- Jan Stark

## Impact on missing ET

- log scale

- log scale

- log scale

- METBx before
- correction

- difference
- after - before

- METBx after
- correction

- METBy before
- correction

- difference
- after - before

- METBy after
- correction

- Impact on METBx and METBy not the same as affected cells have preferred region in phi.

- D0 workshop, Beaune, June 16-20, 2003

- Jan Stark

## DST/TMB vs. RAW

- zoom

- log scale

- GeV

- GeV

- The effects of the inconveniences of DST/TMB can be
- seen in these plots:
-  gain information is not available (need to guess gain)
-        leads to very rare outliers
-  less information on very low energy cells than
-  in RAW files (offline zero-suppression)
-        dominant effect
-  finite precision on ADC counts due to packing
-                very small effect

- Take 300 events from run 175054 and correct the
- shared energy problem, once at RAW level and once
- at TMB level. Compare the cell energies obtained with
- the two different versions of the correction.
- The plots on the right show the difference
-   [cell energy after TMB correction]
-         -  [cell energy after RAW correction]
- for all corrected cells.

- outlier due to wrong
- guess of gain

- either the cell itself, or its
- friend on the bad board is
- killed by the offline zero
- suppression

- D0 workshop, Beaune, June 16-20, 2003

- Jan Stark

## Conclusion

- Implemented code to correct the shared energy problem in data.
- Two versions of the code are available:
-   -  one that works on RAW data
- 	Correction integrated into d0reco.
- 	Available in CVS and included in the latest build of p14.03 .
-   -  and one that works on DST and TMB+ (thumbnails that include the CalDataChunk)
- 	Correction implemented as framework module.
- 	Available in CVS and included in the latest build of p14.03 .
- 	To be used for reprocessing from DST at remote sites.
- 	Can be added to analysis executables that run in post-processing mode
- 	(i.e. that re-reconstruct EM-candidates, jets, etc. from the CalDataChunk).
- 	Can provide physics groups with recipe to include this correction in their analysis jobs.
- 	The correction at DST/TMB level is less precise than the correction on RAW data,
- 	but still pretty good.

- D0 workshop, Beaune, June 16-20, 2003

- Jan Stark

## Conclusion (continued)

- Jets and EM objects in the calorimeter can get
-       - wiggled around,
-       - killed,
-       - created,
-       - joined and probably split
- by the energy sharing problem.
- The material in this presentation gives an idea of the size of these effects.
- Analysis groups who use the fix of the energy sharing problem to fix skims
- that have been obtained from unfixed data should keep this in mind.

- D0 workshop, Beaune, June 16-20, 2003

- Jan Stark