Automatic Track Follow Program

• A program to trace a given set of tracks automatically– Event location for PEANUT and OPERA

– DONUT “not-located” events

Koichi KodamaAichi University of EducationDONUT meeting 2005/05/28

( )シート中心部 ビーム有

1

10

100

1000

3 4 5 6 7 8

PH

0.1s

ec/v

iew

0.40.30.20.10.05

low noise require existence of micro tracks on both sides ( base track ) high efficiency scan at lower PH threshold

Base Track Recognition

Low PH scan takes timerestricted scan in

position and in angle space

At least a micro track should be detected in one of 2 sides of a sheet by Normal PH scan.

The other side are checked with LOW PH threshold scan for its existence if it is not found by Normal PH scan

Idea for base track recognition in a plate

Algorithm for Point Scan

Input : position and angle of a track to be found

Scan on both surfaces with Normal PH threshold

A Base Track exists ?( allowed distortion < 50mrad )

A Micro Track exists in either side ?

Found

Not Found

Scan on the other side with LOW PH threshold

A Base Track exists ?( allowed distortion < 50mrad )

YES

NO

YESNO

Found

Not FoundNO

YES

Test with OPERA emulsion sheet

1mm Pb

2GeV pi-5x103/cm2

Point scan with this algorithmNormal PH threshold = 8Low PH threshold = 6

Sample : 537 tracks found in 4 sides ( pl.51A & pl.50A )4mm x 3mm area

pl.51A

pl.50A

Micro TracksUP side

Micro TracksDown side

Base Tracks

Efficiency @ sqrt(chi2/ndf)<3

This algorithm 0.985 ( 527 )U only 0.933 ( 501 )D only 0.944 ( 507 )Both U&D 0.881 ( 472 )

evaluated with 537 tracks

Base Track PH

Plate to Plate Connection

1. A set of tracks to be followed are given.

2. Find alignment between plates• 200micron x 200micron area scan for DONUT• Choose 10 tracks among given tracks

and require >5 tracks to match

3. Check existence of all tracks• Connection judged at Z in the middle• Multiple candidates are kept

Test with OPERA type brick

1mm Pb

2GeV pi-5x103/cm2

follow down

1mm Pb

Sample : 537 tracks found in 4 sides ( pl.51A & pl.50A )4mm x 3mm area

skipfollow down

search window+/- 16micron+/- 20mradfor 1 plate jump

Last Found Plate by OXX rule

Plate # 51 50 49 48 47 46 45 44 43 42 41 40

Last

found

plate

0 0 3 1 2 2 0 1 2 3 3 8 512

For 1mm thick Lead, int ( high energy protons ) = 0.6% thus … int ( high energy pions ) ~ 0.6% x 2/3 = 0.4%537 x 0.4% = 2.1

search window+/- 16micron+/- 20mradfor 1 plate jump

search window+/- 16micron+/- 20mradfor 1 plate jump

Multiple Connection

Test with DONUT not located event

Scan Back 5246 tracksfound on CS ( both sides ) & SS ( down only )

16mm x 15mm < 200mrad

ECC200

Last Found Plate by OXX rule

Plate # 1 2 3 4 5 6 7 8

Last connected plate

270 195 48 6 5 23 1 105 3821

search window+/- 16micron+/- 20mradfor 1 plate jump

Problem in Scanning

search window+/- 16micron+/- 20mradfor 1 plate jump

Multiple Connection

Summary

• Base Track recognition algorithm works.– Efficiency ~ 0.98 possible for OPERA type sheet

• Track follow program works.– ~1 sec/track for Point Scan– 1000 tracks corresponds to ~30 min/sheet

• Good filter program is needed

to suppress grow up of paths to follow.