oxford 09 october 2003 id alignment meeting pawel brückman de renstrom software prototype –...

Oxford09 October 2003

ID Alignment MeetingPawel Brückman de Renstrom

Software Prototype – recent updatesSoftware Prototype – recent updates

Pawel Brückman de Renstrom

• Just a few observations• No real work done since last meeting• Verification of derivatives tedious – subtle

effects seem to play role!• The proof-of-principle exercise will not be

conclusive unless we start using the “exact” derivatives

ID Alignment MeetingUniversity of Oxford 07/10/03



Potential problem pointed out during last meeting: strangely mixed modes??? Just an artefact of inversed tilt angles in the display program:

before after

No indication for mixed modes any more!



Switch to the latest ntuples from DC1 including exact Z information for extrapolations to the SCT Reminder: I could not observe “low modes” corresponding to global rotations around X & Y on the old ntuples. Reason: derivatives v.r.t. local in-plane rotations of modules are proportional to local_y! New ntuples perfectly cure the problem – just as expected!

NOTE: The DC1 multimu ntuple has over twice smaller statistics than the old one – larger fluctuations observed



Rem

ind

er:

“lo

wes

t m

od

es”

in P

IX+

SC

T a

s re

con

stru

cted

fro

m t

he

old

ntu

ple

s



Mode #

eigenvalue

0 0.0000000000

1 0.0000072838

2 0.0001599211

3 0.0001632777

PIX+SCT Ring, no VTX (DC1 ntuple: 23kev)



Mode #

eigenvalue

4 0.0003927623

5 0.0004008616

6 0.0005043090

7 0.0007637286




Mode #

eigenvalue

0 0.0000000000

1 0.0000000000

2 0.0000000000

3 0.0000243961

PIX+SCT Ring, VTX fit (DC1 ntuple: 23kev)

NOTE: now three translations are distinct. The reason being the direct numerical matching of the derivatives (de/dbde/da) for translations



Mode #

eigenvalue

4 0.0006027754

5 0.0006612646

6 0.0023209506

7 0.0023502892

PIX+SCT Ring, VTX fit (DC1 ntuple: 23kev)



So I was happy and relaxed untill… BUT… wait a moment. There should NOT be 6 exact degeneracies of the system! B field has a direction:

It simply shouldn’t work!

B



And I realised that the “SUPERsymmetry” I obtain was due to oversimplified calculation of de/dcot. It didn’t correctly treat hits further down the helix. After correction…

…again everything as expected!




Mode #

eigenvalue

0 0.0000000000

1 0.0000012014

2 0.0003974228

3 0.0004080927

de/dcot corrected!




Mode #

eigenvalue

4 0.0007558214

5 0.0007961715

6 0.0013165807

7 0.0013501549

de/dcot corrected!

oxford 09 october 2003 id alignment meeting pawel brückman de renstrom software prototype –...

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