# Presentation: 866441

## Slide 1

## Calorimeter Task Force

- _Members:_
- Gregorio Bernardi, Volker Buescher, Christophe Clement, Silke Duensing, Anna Goussiou,
- Leslie Groer (co-chair), Marumi Kado, Nirmalya Parua, Serban Protopopescu, Dean Schamberger,
- Marek Zielinski (co-chair), Robert Zitoun
_**Charge:**_
**The task force will determine the zero-suppression threshold for the calorimeter readout.  **
- In order to fully  understand the consequences of the zero-suppression threshold the Monte Carlo should be
- tuned to observed calorimeter energy and multiplicity distributions.  Simulated data and collider data should be
- used to optimize the reconstruction and properties of physics objects as a function of threshold.
- Selection of the threshold will also require an understanding of the L3 processing time and the data
- set size at L3 and off-line all as a function of threshold.
- Specifically, the task force should:
- Characterize the calorimeter performance on the cell level.
- Characterize particle identification (such as energy response and resolution) as a function of threshold.
- Tune the Monte-Carlo to the data at the cell and physics object levels.
- Understand the consequences of the threshold level on L3 computing and data size and offline data size.
- Recommend a zero-suppression threshold.
- The task force will report to the spokespersons.
- A preliminary recommendation should be available by October 15th
- and a final report by January 15, 2003.

- Marek Zielinski

## A story of zero-suppression

- Suppression threshold of 2.5 for calorimeter cells was originally chosen based on Run I experience ( being the RMS of online noise)
- Run I noise was dominated by Uranium and not electronics –
-     very different regime now
- Jet response, jet widths, taus too skinny etc. were interpreted that threshold was too high
- High suppression removes noise, but also real shower energy
- General consensus from the ID and physics groups that we need to go lower
- Changed threshold on June 26 from 2.5 to 1.5
- First run #158062
- Occupancies gone from 3% to 15%
- Processing time increased sharply
- In p11.11 (Aug 10) reintroduced a “2.5” zesu offline
- But what happened in data?

- Marek Zielinski

## Calorimeter occupancy

- Average occupancy up by factor 4-6
-                            _2.5___         _1.5___
-       Zero-bias      0.9k          6.5k
-       Min-bias        1.4k         7.0k
-       JT_95            1.9k         7.6k

**Silke Duensing**

- Marek Zielinski

## Missing ET very sensitive

- Major change of average missing ET when going from 2.5 to 1.5 sigma zero- suppression cut:                From 6-7 GeV to 14-18 GeV, with a wider scattering from run to run.
- Also true for RMS(MET)
- One entry per root-tuple, data from 19th june till 9th of July.
- Not shown -- METx and METy are also skewed at low threshold

**Gregorio Bernardi**

**<MET>**

**RMS(<MET>)**

- Marek Zielinski

## What’s wrong with the jets?!

- July data, p11.09, 1.5 zesu
- Very high jet multiplicity
- Could not even study dijet resolution!
- Large CH fraction, persisting to high pT
- Enhancement of bad jets (and suppression of good jets) in ICR
- High split-merge activity

**Alexander Kupco**
**Vu Anh Tuan**

- Marek Zielinski

## Could it be zero-suppression?

**Could it be zero-suppression?**

- Comparisons for run 162594, processed twice:
- with only 1.5 online zesu
- and with 2.5 offline zesu
- Data with
-      1.5 online + 2.5 offline
-      are similar (but not identical) to data in special run with
-      2.5 online
- Before, interpretations were confused by other calorimeter issues
-      (non-linearity corrections, event misalignment, trigger changes... all occurred during June)

**Greg Davis**

**Silke Duensing**

- Marek Zielinski

## Offline zero suppression

**calunpdata** package has been modified to apply offline zero suppression similar to the hardware -- “2.5” default
- comparison is “<” instead of “****”, the offline zesu is softer, effectively ~2.1
- Suppression done in ADC counts before _any_ corrections (non-linearity, gains, etc)
- Pedestal threshold file taken from online for a calibration run
- Implemented in p11.11 (Aug 10)
- BUT: L3 is protected only by the online cut at 1.5 -- and suffers from similar problems...

**Rough guess, based on effective zesu: **
** ****1.5 online/0.0 offline     5800**
** ****1.5 online/"2.5" offline  2100**
** ****2.5 online                         750**

**Silke Duensing**

**Leslie Groer**

- Marek Zielinski

## Suppression and L3

**Suppression and L3**

- The thresholds have NO effect on L1 and L2 triggering or readout
- Unpacking time scales ~linearly in L3
- Will have to apply a threshold before filtering algorithms
- L3 calorimeter issues under review by Marumi Kado & Markus Klute

**Marumi Kado**

- RMS

- Online cut

- L3 cut

- Marek Zielinski

## So, what’s the noise?

- Noise in detector (per cell, in MeV)
-      calibration by Robert Zitoun, in p11.13.00
-             15-50 EM, 60-90 FH, 300 CH, 450 OH
**(RunI: 10-15,          40-70,        100,           80)**
-      With  1.5 zero suppression, it is not hard to create 5 GeV of noise energy within the jet cone in CH/OH, or a jet seed of 500 MeV
- Noise in MC simulation
-      has been underestimated by factors:              2-2.3 EM, 2-2.8 FH, 2-3.2 CH/OH/MG, 8 ICDin p11.xx (except xx=13) and in p12
-      and by factors
-      6-10 EM, 3 FH, 25 CH, 15 OH
-      up to p10.xx (with no noise in ICD and MG)
-       P10.15 was our major MC production so far!
- A “lucky bug” in the d0sim code inflated the effective noise by factor 1.4 – but it was fixed in p11.12...

- CH

- OH

- FH

- FH

- EM

- EM

- CH

- CH

- FH

- Marek Zielinski

## Jets and noise

- Vishnu Zutshi studied jet behavior in MC with roughly correct noise
- drmin is matching distance between reco and generated jets
- Many fake jets formed with 1.5 zesu
- Much cleaner for 2.5 zesu
- Most fake jets in ICR

- 3*raw-noise

- 1.5 zesu

- 2.5 zesu

- True jets

- Noise jets

- Marek Zielinski

## Jets and noise - II

- No-noise() 1.5() 2.0() 2.5()

- Jet Response

- Jet Resolution

- 3*raw-noise

- ET

- 20

- 0.9

- 120

- 0.1

- 0.8

- 0.15

- This study suggests that optimal zero-suppression for jet response and resolution may be around 2
- Then need further protection against fake jets:
- Higher zesu only in CH/OH?
- Higher requirements for seed towers? (currently 0.5 GeV)
- Restrict seeds in CH/OH?
- Compensate by including negative calls/towers?
- Worse response, resolution
- Many combinations to sort out
- John Krane is developing a “Toy MC” to allow quick insights

- Marek Zielinski

## MET, SET  and CH

- First look at the influence of CH layers on MET and SET
- CH provides >20% of scalar ET in both Zero+MinBias events and QCD events
- The difference between CH energy in both event samples is not large
- 9.7 GeV in ZMB, 14.3 in QCD
- CH layers contribute significantly to MET
- The Mean and RMS values are much higher at 1.5
- Is CH adding more noise than physics signal?
- How to handle negative cells?
- Need more studies...

- QCD

- ZMB

**From CH**
**Without CH**
**With CH**

- Stephanie Beauceron

- 2.5 run

- Marek Zielinski

## Status of calorimeter MC 

- Code status:
- Noise simulation file in pileup is low by factor of ~2-3 (corrected in p11.13)
- No resistor swap factor incorporated  (1.39 )
- No linearity correction applied (1.5-1.7  )
- Double-gaussian “lucky bug” for noise simulation corrected in p11.12
-  actually worse noise simulation!
- Noise simulation in pileup in GeV
- Intend to switch to ADC
- Calorimeter z0 offset by 2.9 cm
- Introduced in p12.03
- ICD ADCtoGEV low by at least 35% determined from MIP calibration
- Bug in offline “2.5” sigma cut – same as for p11.11 data

- Current CTF production at UTA farm:
- D0gstar files generated with p11.10
- Currently using p11.12.01 for d0sim/reco, with two rcp changes
- cal_noise.rcp in pileup from Robert Z
- d0sim suppression lowered
- Also mc_runjob updates
- No useful objects present in  rootuples – under investigation
- Processed 10k each of
- Z  ee
- Z  tau tau
- QCD pT>20
- Pending requests
- gamma+jet pT>20
- W  enu
- QCD, higher pT thresholds

- Marek Zielinski

## Interim Proposal for Data

- Zero suppression:
- Keep 1.5 sigma threshold online
- For offline suppression:
- Correct the bug in 2.5 sigma suppression; stay at 2.5 threshold
- Use Robert Zitoun’s pedestal width measurement
- Apply the same suppression at L3
- this will affect L3 trigger objects dramatically – improve rejection
- will introduce a second data set

- Beyond zesu:
- Correct ICD ADCtoGEV based on MIP measurements (x1.35)
- Correct CC MG layer weight for feedback capacitor gain factor (x1.9)
- Reprocess all p11.xx data after June 26th (ignore the mixed event data for now — July through Aug 15)
- “redo” L3, but not tracking?
- A wish list:
- Modify jet algorithms to protect against effects of CH noise
- Turn on L3 NADA for MET and jet objects (and electrons?)

_**Month**_**   ****	**_**Raw**_**           **_**Processed**_
**Jun****	****  5.2****	****  2.2**
**Jul****	****22.0****	****  9.7**
**Aug****	****23.0****	****10.2**
**Sep****	****31.7****	****11.0 **
**Oct****	****  2.4****	****  0**

**                                            ****Processed so far (Mevents)**
**       **_**Version**_**                     **_**Raw**_**              **_**Processed**_
**p10.15     ****	****75****	****55.0**
**p11.09****	****	****11****	****  9.9**
**p11.11****	****	****85****	****11.6**
**p11.12.01****	****19****	****   6.1**

- Marek Zielinski

## Interim Proposal for MC

- Two options for noise simulation:
- Use the new phi-averaged noise file (in GeV) in pileup  (from p11.13)
- Exists already, we should see MC files soon
- Zero suppression in reco, only a precut in d0sim
- If new pileup code is ready, apply Robert’s cell-by-cell noise measurement in linearized ADC
- The preferred method
- Use Robert’s raw ADC noise file for suppression in d0sim
- Still needs to be completed, released and verified
- Correct offline “2.5” bug and ADCtoGEV in ICR (same as for data)
- Apply calorimeter z0 offset in d0gstar

- Unfortunately, no MC studies yet to show that the newnoise simulation matches the current data more closely ...

- Marek Zielinski

## Studies needed in the next few months

- Get MC samples to study effects in response, resolution and identification efficiencies as function of threshold schemes
- jet, MET, electron, photon...
- Comparisons between MC and data
- Explore different suppression schemes:
- Threshold dependent on ilayer?, ieta?
- Other modifications to algorithms?
- Noise in CH and OH is relatively larger by a factor ~2-3 compared to the other layers than was the case in Run I
- Eta’s in the far forward (>3) region have ~3-4x the occupancy

- Noise samples (single )
- Z ee, 
- We
- QCD pT > 10, 20, 40, 80 GeV
- Photon + jet
- B-jets, Top, Higgs, ...

- Marek Zielinski

## Outlook

- Expected work for the final report (01/15/03)
- Raise online threshold slightly
- Readout times become more of an issue at higher DAQ rates (~1 kHz) to reduce FEB
- Data size reduction translates directly to saving in storage media costs
- The fine-tuning could have layer and eta dependencies
- Readout time determined by the crate with highest occupancy
- Suppressing forward regions can help a lot with little effect on ET
- 1.5  1.7-1.8?
- Similarly, drop the offline thresholds somewhat at least in some layers and maybe some etas
- 2.5  2.0?
- Utilize the calibrated pedestal widths for the actual run both at L3 and offline from the database
- Requires significant infrastructure work to calunpdata
- Use unsuppressed zero-bias data for pileup overlays

- Marek Zielinski

## Work beyond the CTF

- Need to strengthen the effort in the calorimeter software group and related ID groups
- Cleanup and consolidate simulation and reconstruction code
- conversions in cal_tables and cal_weights
- integrate preshower information
- Many things should be studied in longer term
- Evaluate robustness of algorithms at high luminosity
- Readjust layer weights, or apply layer corrections for
-      energy lost due to zero suppression on the object level
- Develop algorithmic protections
- Reevaluate the use of negative energy cells and towers
- Revisit d0gstar choices for shower development
- We are accumulating a list of needs...
- Need new _active_ contributors!

- Marek Zielinski

## Status of production versions

- Major versions of reco used
- p10.15   Feb 12
- Cal weights corrected for resistor swap
- Dynamic NADA in kill mode
- p11.09   Jun 1
- NLC first applied
- ICD ADCtoGeV corrections
- ICD addressing corrections
- p11.11   Aug 10
- “2.5” offline suppression
- NLC correctly applied
- ICD addressing corrections
- p11.12   Sep 14
- Single gaussian for noise simulation

- June 18-Aug 15 FPGA code v26+27 mixes events in multi-buffer mode
- Offline suppression in p11.11 has a bug
- “<“ used instead of “<=“ in suppressing cells i.e. cut is about 2.0 to 2.4, depending on layer
- L3 NADA tested and runs but not used
- CPU time tends to scale linearly with occupancy (i.e. threshold)
- No “offline” suppression at L3 yet
- ICD  ADCtoGEV still low by at least 35%, determined from MIP calibration
- June 26 – changed from 2.5 to 1.5 sigma in the online data taking
- CC massless gap ieta=8 ADCtoGEV off by a factor of 1.9

- Marek Zielinski