# Presentation: 204149

## CALGO Meeting

- Checkerboard pattern problem
- What’s the problem ?
- What’s the fix ?
-  What’s the follow up ?

- Jan Stark, Jean-Roch Vlimant

## The problem

- J. Gardner

- Discovered by John Gardner.
- / distribution of all candidate EM objects:
-   pT > 25 GeV
-   EM fraction > 0.9
-   isolation < 0.15
-   HMx8 < 20
- pink boxes: tower two problem
- blue boxes: energy sharing problem
- red boxes: other stuff ...

-          Cable swaps

- Checkerboard

- Jan Stark, Jean-Roch Vlimant

## Reminder: BLS

- Figure taken from Run II CAL electronics TDR

**ADC raw****+****gain bit****+****L1 trigger**

- Trigger is unbiased with gain path

- The gainpath chosen
- is reported on a
- separate line.

- Jan Stark, Jean-Roch Vlimant

## Between gain paths

| Short circuit hypothesis
 between paths0 always wins | Gain bit0 = gain 8, 1 = gain 1 |  | What Jan saw
If the short circuit is not symetricalcopy of tower 0(3) |
| --- | --- | --- | --- |
|  | Tower 0(3) | Tower 1(2) |  |
| 0 | 0 | 0 | 0 |
| 0 | 0 | 1 | 0 |
| 0 | 1 | 0 | 1 |
| 1 | 1 | 1 | 1 |

- Reason
- Still under investigation

- Jan Stark, Jean-Roch Vlimant

## What does that mean ?

- Gain 1 path_only preamplifier_, ADC raw ranges [3100 ; 25000 ]
- Reported gain 1 : keep as it is , ADC ranges [ 3100 ; 25000 ]
- Reported gain 8 : _software_ division by 8, ADC ranges [ 375 ; 3100 ]******Cells energy at reco level, will be 8 times **_**lower**_** than what it should be**
- Gain 8 path_preamplifier multiplication_ by 8, ADC raw ranges [0 ; 25000 ]
- Reported gain 8 : _software_ division by 8 , ADC ranges [ 0 ; 3100 ]
- Reported gain 1 : keep as it is , ADC ranges [ 0 ; 25000 ] ******Cells energy at reco level, will be 8 times **_**higher**_** than what it should be**

- Jan Stark, Jean-Roch Vlimant

## ADC counts  reported gain inconsistencies

- Raw ADC counts

- Use raw data from run 187812.
- In each event, look for all cells that are
- reported in gain x1.
- Plot number of raw ADC counts
- for all of these cells.
- Do not expect any cells in gain x1 with less
- than  3100 ADC counts.
- Observe a significant population of events
- that are inconsistent with this expectation.
******Cells with an actual gain 8 but the gain 1 is being reported **
******Cells energy at reco level, will be 8 times higher than it should be**

- Jan Stark, Jean-Roch Vlimant

## Location of troubles (1)

- For gain inconsistencies location
- Run 176839

- Jan Stark, Jean-Roch Vlimant

## Location of troubles (2)

- L1-L3 Et>15GeV
- 89k entries
- Gain 8 instead of 1

- L1-L3 Et<-15GeV
- 12k entries
- Gain 1 instead of 8 (previous slide configuration)

- EM layersL1<59GeV

**Mostly tower 1 and 2**

**Uniform tower distribution**

- Jan Stark, Jean-Roch Vlimant

## L1/L3 discrepancies

- ECNorth iphi <32

- ECNorth iphi >32

- ECsouth iphi <32

- ECSouth iphi >32

- Bad tail!Other reported features

- Bad tail !Main checkerboard

- |L1-L3|>2, EM layers , 5<L1<59GeV

- Crap at L1<20

- « Clean » Distribution is like exp(-0.5|L|)RMS is 2Gev

- Jan Stark, Jean-Roch Vlimant

## Check over Raw data

- ECSouth
- ECNorth iphi>16
- ECNorth iphi<16

- EM layers, L1>20GeV

- Jan Stark, Jean-Roch Vlimant

## Gain switching : The fix

- Sum up L3 energy in L1 trigger tower
- If difference is less than a few L1-L3 RMS , then do nothing
- If not, then change the gain factor of one cell so that |L1-L3| is minimum
- We do not have the actual gain for each cell
- Gain Guessing
- Give maximum confidence to L1
- Fine tuning of parameters in its way
- Only correct in tower 1 or 2
- Only on region showing gain  for checker board
- ieta<-7 and iphi16 (main checker board location )
- ieta<-16 and 41  iphi  44
- ieta<-20 and 47  iphi  48
- -12  ieta  -1 and 43  iphi  48(all towers)
- ... ?!?

- Most frequent

- Less frequent

- Jan Stark, Jean-Roch Vlimant

## L1/L3 discrepanciesafter corrections

- L1/L3 discrepanciesafter corrections

- ECNorth iphi <32

- ECNorth iphi >32

- ECsouth iphi <32

- ECSouth iphi >32

- Corrected Distribution is like exp(-1.6|L|)RMS is 0.7GeV

- Jan Stark, Jean-Roch Vlimant

## Location of troubles (3)

- L1-L3 Et>15GeV
- 89k entries

- L1-L3 Et<-15GeV
- 12k entries

- EM layersL1<59GeV

**Uniform tower distribution**

**Excess of tower 2 and 3**

**Hot cell –12:48**

- Jan Stark, Jean-Roch Vlimant

## Location of troubles (4)

- Layer 1

- Layer 2

- Layer 3

- Layer 4

- Layer 5

- Layer 6

- Layer 7

- L1-L3 Et>15GeV , EM layers , L1<59GeV

- Jan Stark, Jean-Roch Vlimant

## Location of troubles (5a)

- Layer 1

- Layer 2

- Layer 3

- Layer 4

- Layer 5

- Layer 6

- Layer 7

- L1-L3 Et<-15GeV , EM layers , L1<59GeV

- Jan Stark, Jean-Roch Vlimant

## Location of troubles (5b)

- Layer 1

- Layer 2

- Layer 3

- Layer 4

- Layer 5

- Layer 6

- Layer 7

- L1-L3 Et<-15GeV , EM layers , L1<59GeV

- Jan Stark, Jean-Roch Vlimant

## Summary

- Gain switching problem is obvious and still present in data
- As for data already taken
- Fix at tmb level is ready(means tested, checked, and ran over more than 25Millions events )
- Need fine tuning of rcp parameters (this talk will help)
- Fix at raw level can be more precise due to gain information ?
- And fix the electronics
- But there are other sources of L1/L3 mismatch
- Widespread, eta, phi, tower ?
- What happen in central region ?
- Up to 15GeV Et difference !
- Although small fraction (~300times affected / 25Mevts )

- Jan Stark, Jean-Roch Vlimant