1

Pass 6 Topology (TKR) AnalysisPass 6 Topology (TKR) Analysis

Create variables for use in this analysis

Veto the Interrupted Shower Topology

Use ToT to kill Range-outs & Heavy Ions

Divide up into 3 Topological groups and apply PreFilters and CTs

TKR (Topology) SchematicTKR (Topology) Schematic

What's new in Pass 6What's new in Pass 6 Global IST Veto Global Heavies &

Range-outs Veto

2

Incoming e+ and e- can interact in the first few layers going to an all-neutral state. The resulting gammas can then pair convert particularly in the thick layers.

A New Background Class IdentifiedA New Background Class Identified (Robert Johnson)

3Max loss: ~ 7% around 500-1000 MeV

Events in RED - Vetoed Interrupted Shower CutInterrupted Shower CutAcdTileEventEnergyRatio > max(.003, (6 - TkrUpstreamHC)* .006) &AcdTileEventEnergyRatio > (-.015 - .00002*AcdTkr1ActiveDistENorm) &TkrUpstreamHC > 0

What's Left What's Killed

Note: This cut could be broken out as a separate stand-alone cut to improve efficiency for some Event Classes

4

Heavy Ions & Range outs from BelowHeavy Ions & Range outs from Below

Tracker ToTs give a dE/dX meas.Plotting Tkr1ToTFirst vs CTBBestLogEnergy suggested that scaling the ToT to energy had merit:

ScaledToT = Tkr1FirstTot * 2.5/CTBBestLogEnergy

Decoding by Source Type

Heavies & Range Out CutHeavies & Range Out CutTkr1ToTFirst < .2 & CTBBestEnergy < 25000) | Tkr1ToTFirst * 2.5/CTBBestLogEnergy > 6.5

MIP Range Outs

5

Totals Totals

Which Sources are Effected by these new vetosWhich Sources are Effected by these new vetos

Interupted Shower Veto Heavy Ion / Range-out Veto

The IS Veto seems to take out more then just e+/e-

The HR Veto does its job well

6

Topology ClassesTopology Classes

VTXVTX

CoreHCRatio GAM BKG

All 48497 7982

< .05 200 1725

< .10 499 2412

HC == 0 178 1588

HC > 1 757 2967

Tkr1CoreHC is the number of extra hits close to the first track. Electrons/positrons like to make lots of delta-rays. You can use this variable directly or as a ratio to the number of hits on the first track

7

TkrDisp GAM BKG

All 48497 7982

> 400 9 100

> 300 31 213

> 200 143 455

> 150 307 751

Another good discriminator is the track-dispersion. This variable measure how spread out the various found tracks are in the detector. EM showers make bundles of closely packed tracks

VTX Topology VetoVTX Topology VetoTkr1CoreHC > 1 & TkrDispersion < 400

8

TKR VTX CTTKR VTX CTNodeSplit/Remainder: 30/10 6 Trees 2k/Tree

9

1Tkr Front1Tkr Front

CoreHCRatio GAM BKG

All 4076 25495

< .05 690 16735

< .10 1131 19118

HC == 0 598 15371

HC > 1 1157 21265

1Tkr Front Veto1Tkr Front Veto Tkr1CoreHC < 2

Again it’s a question of which to use: the scaled Core Hit Count or

This seems like a big hit, except there are not a lot of Gammas in this class

10

TKR 1Tkr Front CTTKR 1Tkr Front CTNode Split/Remainder: 30/105 Trees 2k/Tree

11

1Tkr Back1Tkr Back

CoreHCRatio GAM BKG

All 29269 67266

< .05 7726 40895

< .10 8044 41458

HC == 0 7726 40895

HC > 1 13779 55079

1 Tkr Back Veto1 Tkr Back Veto Tkr1CoreHC < 1

This is more serious. There are just very few handles on these events. They are dirty

Note: The numbers in various parts here are not the same due to different data samples that were used over time to do this: v13r7, v13r9, and partial and full samples

12

TKR 1Tkr Back CTTKR 1Tkr Back CTNode Split/Remainder: 30/10 20 Trees 2.5k/Tree

13

nTKR TopologynTKR TopologyTkrDisp GAM BKG

All 66478 61679

> 800 20 871

> 600 51 2445

> 400 137 6619

> 300 325 11024

> 200 801 18952

> 150 1375 25571

CoreHCRatio GAM BKG

All 66478 61679

< .00 491 15747

< .05 520 16435

< .10 868 19882

< .15 1365 23421

< .20 2239 31926

nTkr Topology VetonTkr Topology VetoTkr1CoreHCRatio > .1 & CTBBestEnergy > 50 &TkrDispersion < 300

14

TKR nTkr CTTKR nTkr CTNode Split/Remainder: 30/1020 Trees 3k/Tree

15

Pass 5 - Pass 6 PreFilter ComparisonPass 5 - Pass 6 PreFilter Comparison

Pass 6 sacrofices 3.5% Gamma efficiency for a 1.5x improvement in background rejection power

16

Pass 5 - Pass 6 CT ComparisonPass 5 - Pass 6 CT Comparison

Pass 5Pass 5 Pass 6Pass 6