# Presentation: 381519

## Domain (nxmxl -box) Clustering  Tests

-  Hit density methods to detect (seedless) cluster centroids
-  Hit density ***gradient*** methods  (for angular resolution)
- -- to detect cluster edges
- -- as a guide to cluster split/merge
-  Now applied to two gamma events;
- -- mar2001/angResSD/gamma_20_50.sio
- -- E **=** 20GeV , ang.separation **=** 50mrad
- -- SD Ecal inner radius **=** 127cm (6.4cm)
- -- two clusters separated by ~12--13 cells

**A. Maciel (NIU), *****SLAC-LCD***** meeting, 07-May-2002**

*Domain (n**x**m**x**l -box) Clustering  Tests*

## SD – 10GeV single  γ’s  in Em-Cal   (5k evts.)

- SD – 10GeV single  γ’s  in Em-Cal   (5k evts.)

***GeV***

**n.of cells**

**A. Maciel (NIU), *****SLAC-LCD***** meeting, 07-May-2002**

***First, a brief look***
***at EM-shower***
***characteristics***
***in “SD”***

**Layer num.**

**Layer num.**

**Layer num.**

**Layer num.**

## MC generation  (1000 two-gamma events)

- MC generation  (1000 two-gamma events)

- 50mrad
- appart

**A. Maciel (NIU), *****SLAC-LCD***** meeting, 07-May-2002**

## Test Routine

-  Sweep above domain with (8 x 8 x all) domain, select hottest **(“MAX”)**
** **Inspect **MAX**, find centroid (axis), cluster energy, stacking sigma, etc.
-  “Zero In” at (4 x 4 x all) and inspect neighbourhood for ***gradients***
-  Method used is simple dE**/**dV

- γ1

- γ2

*Test Routine*

**A. Maciel (NIU), *****SLAC-LCD***** meeting, 07-May-2002**

- dCell = 2
- dE = En.Acc.
- dV= #Cells Acc.

- γ1

## “ALL” = Domain that

- “ALL” = Domain that
- contains both clusters

- “MAX” = Domain that
- contains single gamma

**layer stacking**
**( cell units )**

**A. Maciel (NIU), *****SLAC-LCD***** meeting, 07-May-2002**

-  “MAX” is either the η=0 cluster,
- or the one orbitting around it.

- RMS.theta vs RMS.phi  is a measure
- of the layer-to-layer correlation

**Contains two**
**gammas**

**Single gamma**

## first event

- 1000 events

**d =**
**50 mrad**
**~12 cells**

**A. Maciel (NIU), *****SLAC-LCD***** meeting, 07-May-2002**

***Energy;***
**γ****1**** b****ox fixed, but**
**increasing in size**
**( cell units )**

***‘******Gradient’***

## 2nd Test

- 25mrad
- appart

***2******nd****** Test***
- 25 mrad
- Same
- routine
- Domain
- sizes
- halved

**A. Maciel (NIU), *****SLAC-LCD***** meeting, 07-May-2002**

- (half distance)

- MC generation  (1000 two-gamma events)

## “ALL” = Domain that

- “ALL” = Domain that
- contains both clusters

- “MAX” = Domain that
- contains single gamma

**A. Maciel (NIU), *****SLAC-LCD***** meeting, 07-May-2002**

- Again, “MAX” is either the η=0 cluster,
- or the one orbitting around it.

- same general performance repeated

**Contains two**
**gammas**

**Single gamma**

**layer stacking**
**( cell units )**

## first event

- 1000 events

**d =**
**25 mrad**
**~6 cells**

**A. Maciel (NIU), *****SLAC-LCD***** meeting, 07-May-2002**

***Energy;***
**γ****1**** b****ox fixed, but**
**increasing in size**
**( cell units )**

***‘******Gradient’***

## First Event  ( d=25 mrad )

- First Event  ( d=25 mrad )

- ECAL layers 0--9
- ( upstream showerMax )

- ECAL layers 10--29
- ( downstream showerMax )

**A. Maciel (NIU), *****SLAC-LCD***** meeting, 07-May-2002**

**d =**
**25 mrad**
**~6 cells**

## 1000 Events  ( d=25 mrad )

- 1000 Events  ( d=25 mrad )

- ECAL layers 0--9

- ECAL layers 10--29

**A. Maciel (NIU), *****SLAC-LCD***** meeting, 07-May-2002**

**d =**
**25 mrad**
**~6 cells**

## At 10 mrad separation, both gammas have 

**d =**
**10 mrad**
**~2--3 cells**

**400 Events  ****( d=10 mrad )**

- 32 x 32 x all

- 4 x 4 x all

- One event
- layers 0--9

- One event
- layers 10--29

- At 10 mrad separation, both gammas have
- practically merged to a single cluster

## Some  Final  Comments

- -- choose/test/tune “domain methods”
- -- get hard numbers for Energy & Angle resolutions
- -- apply (e.g.)  to π0  γγ resolution as a fn. of π0 momentum
- -- Study the hadronic sector,  apply to physics events, etc,etc.
-  At least, a seemingly powerful support tool for “clustering orthodoxy”
-  Possible E-Flow scenario;
- -- use domains to cross check tracking-seeded clusters. Check
-     gradients around centroid, inspect split/merge layer(s) wise.
- -- remove seeded clusters. Large domain sweeps for deposited
-     maxima. Sub-domain centroid/split/merge analysis.
-  Practical Outlook; my code has hit a steel wall (few secs/evt !!  Win-300Mhz).
-          Needs full re-vamp with efficient  geometry-to-hits  mapping, decent OO,
-          in good LCD/JAS style. Not clear how much (if any) in time for StaCruz...

**A. Maciel (NIU), *****SLAC-LCD***** meeting, 07-May-2002**

*Some  Final  Comments*

## SD – 10GeV single  e-  in Em-Cal   (5k evts.)

- SD – 10GeV single  e-  in Em-Cal   (5k evts.)

***GeV***

**n.of cells**

**A. Maciel (NIU), *****SLAC-LCD***** meeting, 07-May-2002**

***EM-shower***
***characteristics***
***in “SD”***