# Presentation: 265864

## FCal Simulation and Performance Summary

- Submitted to Milano Hadronic Calibration Meeting
- April 26,27 2007
- P.Krieger (on behalf of the FCal group)

- FCal Input to Milano Hadronic Calibration Workshop, April 2007

- P.Krieger

## FCal Simulation Work

- Carleton: J.P. Archambault / M.Khakzad (TB03 setup using Athena FCal Geometry )
- Toronto: S.L. Cheung (working on parametrized Monte Carlo for FCal, but performs full simulation work for comparison).
- Toronto: P. Thompson (block FCal, similar to early ITEP work, but using geant4.8 and predicted hadronic matrix densities).

- Results have been sent by I. Tsukerman, summarizing ITEP simulation work.
- There are also other efforts, both within the ATHENA framework, and standalone:

- The Carleton work so far uses QGSP_GN
- Both U of T analyses are using QGSP_EMV

- FCal Input to Milano Hadronic Calibration Workshop, April 2007

- P.Krieger

## FCal2/3 Sampling Fraction vs Material Density

- The setup of the hadronic FCal modules in LArGeoFcal uses a mixture to describe the “matrix” (mixture of copper tubes, WFeNi slugs, and LAr, and the Cu endplates). In the latest LArGeoFcal the effective matrix density is still set to 15.366 g/cm3. This has been known to be too high for some time now.
- Our current best estimate (based on unit-cell properties, component dimensions and masses as well as the measured module masses) is 14.33 g/cm3 for the FCal2 and 14.45 g/cm3 for the FCal3.
- Note that the effective matrix density of the Module-0 used in the 1998 testbeam is probably not so well known. So any comparison of simulations with the experimental result for the FCal1/FCal2 ratio of sampling fractions may have an uncertainly of the order 4-5%, which is the size of the effect seen when changing from a density of 15.366 g/cm3 to 14.33 g/cm3 (the former value has been around for some time and may well have been calculated for the module0).

- Some comments on the FCal material description:

- FCal Input to Milano Hadronic Calibration Workshop, April 2007

- P.Krieger

## Tungsten Rod Material Incorrect in LArGeoFcal

- // Electrodes:
-       if(m_absPhysical2==0)
-       {
- 	double halfDepth    = fcalData[1].fullGapDepth/2.0;
- 	double innerRadius  = fcalData[1].innerGapRadius;
- 	double outerRadius  = fcalData[1].outerGapRadius;
- 	GeoTubs *gapTubs       = new GeoTubs(0,outerRadius,halfDepth,0.0, 2.0*M_PI);
- 	GeoLogVol *gapLog      = new GeoLogVol(baseName + "Module2::Gap",gapTubs, LAr);
- 	GeoPhysVol *gapPhys    = new GeoPhysVol(gapLog);
- 	GeoTubs *rodTubs       = new GeoTubs(0,innerRadius,halfDepth,0.0, 2.0*M_PI);
- 	GeoLogVol *rodLog      = new GeoLogVol(baseName + "Module2::Rod",rodTubs, FCal23Slugs);
- 	GeoPhysVol *rodPhys    = new GeoPhysVol(rodLog);
- 	..............

- Rods are ~pure tungsten. Density quite a bit higher than what is currently in the GeoModel description. In LArG4 version these were pure tungsten

- Note that the material FCal23Slugs should appear only as a component of the mixture used to describe the bulk of the FCal absorber matrix (*e.g.* everything excluding the rods and the LAr gaps).
- This has NOT been corrected for in the plots provided here, though some initial runs with tungsten rods have recently been performed - see slide 7

- From current HEAD version of FCALConstruction.cxx (offline/LArCalorimeter/LArGeoModel/LArGeoFcal/src)

- FCal Input to Milano Hadronic Calibration Workshop, April 2007

- P.Krieger

## FCal Electron Sampling Fractions

- Athena 12.0.31, geant4.7.1.patch01.atlas03,LArGeoFcal-00-00-21, 30m range cut, QGSP_GN

- Athena 12.0.31, geant4.8.1.patch01.atlas01,LArGeoFcal-00-00-21,30m range cut, QGSP_GN

**SF1 = (1.309 +/- .001)%**

**SF1 = (1.342 +/- .001)%**

**SF2 = (0.682 +/- .002)%**

**SF2 = (0.651 +/- .002)%**

**SF2 = (0.847 +/- .002)%**

**SF2 = (0.810 +/- .002)%**

**SF3 = (0.974 +/- .003)%**

**SF3 = (0.939 +/- .003)%**

**SF3 = (1.066 +/- .003)%**

**SF3 = (1.027 +/- .003)%**

- J.P.Archambault/M. Khakzad

- FCal2/3 results show for both current default effective matrix density, and for predicted values.

- FCal Input to Milano Hadronic Calibration Workshop, April 2007

- P.Krieger

## Comparison with ITEP Results

- There is some discrepancy when these values (calculated with the default matrix density of 15.366 g/cm3) are compared to the results shown by Ilya Tsukerman. There are large differences in the absolute sampling fractions. The *ratios, *however*,* are quite consistent:

- Carleton  1.34           0.81            1.03            1.65          1.30
- ITEP        1.60           0.95            1.23            1.68          1.30

-     SF1          SF2             SF3        SF1/SF2    SF1/SF3

- The simulation were not the same, but the absolute differences are rather large and  should be investigated.

- FCal Input to Milano Hadronic Calibration Workshop, April 2007

- P.Krieger

## FCal2/3 Sampling Fractions vs Material Density

- Dependence of FCal2/3 SFs on material density is visible on the previous slide.
- This is confirmed by other  studies (S.L. Cheung, P. Thompson)

- SF2 = 0.844 for  = 14.33 g/cm3

- SF3 = 1.060 for  = 14.45 g/cm3

- Athena 12.5.0, geant4.8.2.patch00.atlas01,LArGeoFcal-00-00-26,30m range cut, QGSP_EMV

- Standalone studies using “block” FCal modules yield similar results

- SF2 = 0.850   for  = 14.33 g/cm3

- SF3 = 1.060   for  = 14.45 g/cm3

- G4.8, QGSP_EMV, 30m range cut, 10 GeV e-

- 100 GeV e-

- Initial look (standalone) with correct rod material shows ~ 1-2% effect on FCal2/3 SFs

- FCal Input to Milano Hadronic Calibration Workshop, April 2007

- P.Krieger

## FCal Calibration Testbeam Results

- Analysis will be presented to the collaboration at the BNL LAr week in May.
- Here I provide only preliminary results without detailed explanation of the analysis.
- For more details on the testbeam setup and on the analysis, please see the talks presented at the Barcelona Calorimeter Calibration workshop in September 2006.
**Please note that these distributions are from recent work in progress. In some cases they have not yet been discussed by the full FCal group, so they should be viewed as rather preliminary, though we hope to have the analysis completed rather soon.**
- Note also that it is our plan / wish to also do this analysis using topological clustering. This was made difficult for some period of time by mapping problems in the FCal3, which we hope are now resolved. It is not clear to us whether the updated Nearest Neighbours map is available. Perhaps that could be clarified in the discussions at this meeting.

- FCal Input to Milano Hadronic Calibration Workshop, April 2007

- P.Krieger

## FCal Electromagnetic Scale / Linearity

- Fitted value agrees well with value predicted from detector properties and modeling of the electronics chain (J.Rutherfoord). Predictions exist also for the EM scales of the FCal2 and FCal3 modules. The numbers currently in use are:

- FCal1: 12.0 ADC/GeV
- FCal2:   6.1 ADC/GeV
- FCal3:   5.4 ADC/GeV

- On the following slides, when the EM scale is referred to, it refers to these values.

- residuals

- FCal Input to Milano Hadronic Calibration Workshop, April 2007

- P.Krieger

## EM Energy Resolution

- Noise subtracted

- FCal Input to Milano Hadronic Calibration Workshop, April 2007

- P.Krieger

## Hadronic Energy Reconstruction

-  Cylindrical clustering (16cm) around cluster centre, flat weights (one per module)

- Two methods:  each calculates weights by minimizing

- Where the ’s are appropriate EM scale factors and the g’s are the fitted weights.

- EM scale factors taken from predictions (verified in the case of FCal1, and with some input from 1998 testbeam for the relative response of the FCal2 modules).
- Weights are obtained at each energy. Results shown here are obtained using an average of the weights obtained from the data samples at 60-200 GeV.

- FCal Input to Milano Hadronic Calibration Workshop, April 2007

- P.Krieger

## Hadronic Energy Reconstruction with Radial Weights

- Radial weights *W**k**(R*) obtained by interpolation between set of radial weights *W**k**(R**k**)* at discrete distances *R**k**,* where *k = 1,2,.....N*. Here the weights are calculated for distances up to 16cm from the particle impact point (in 1*cm* steps).
- Here S*j* is the energy of cell* j* reconstructed at the EM scale.
*N = 16* for each module, giving a total of 48 free parameters to be fitted.
- Energy dependence of radial weights is not strong, can use average or highest energy weights.
- Plots shown here obtained using radial weights extracted from 200 GeV data sample.

- Transverse or radial weighting of cells according to the distance from the beam impact point (taken from the tracking).

- FCal Input to Milano Hadronic Calibration Workshop, April 2007

- P.Krieger

## FCal Hadronic Reponse Linearity

- FCal Input to Milano Hadronic Calibration Workshop, April 2007

- P.Krieger

## FCal Hadronic Energy Resolution

- Noise subtracted

- FCal Input to Milano Hadronic Calibration Workshop, April 2007

- P.Krieger