V.Patera – KLOE GM – Otranto – 10 June 2002

K reconstruction statusK reconstruction status

K+K- retracking features

New vs Old : resolution

New vs Old : efficiencies

Conclusion and outlook

K+K- retracking features

New vs Old : resolution

New vs Old : efficiencies

Conclusion and outlook

P. BranchiniE. De LuciaP. De SimoneM. MartemianovB. SciasciaV. Patera

V.Patera – KLOE GM – Otranto – 10 June 2002

KPM ReconstructionKPM Reconstruction

KPM Selection KPM retracking DST production

Done and working

Finalized, under test

Not yet addressed

The KPM reconstruction has been updated/ridesigned, in particular with respect of: Track merging, T0 finding, K± TOF correction, Multiple scattering treatment optimization, ECLO and Event selection interaction

V.Patera – KLOE GM – Otranto – 10 June 2002

KPM retracking:new & updated modules

KPM retracking:new & updated modules

Kmerge

T0_find

atfmod

Merge tracks and udpdate pattern candidates. Orders and updates K id from different ECL algos in ECLO

Pattern Banks & ECLO

Finds the KPM t0 global T0GL

New K TOF implementation, specific K m.s. treatment, correct hit times for T0

Fit Banks

module New features Updated bank

V.Patera – KLOE GM – Otranto – 10 June 2002

K+K- reconstruction: merging

K+K- reconstruction: merging

K+

K-

Due to K large TOF, wrong T0 and large m.s. the “standard” rec. produces a large fraction of broken tracks (at the pattern level!). No recovery possible by the Fit

The Kmerge module merge all the possible tracks (not only K+K- ) on the basis of their angle, distance and momenta and rebuild the KPM ECLO banks. After merging and T0 correction, the tracking/pass=2 (usually) splits only the correct kinks

V.Patera – KLOE GM – Otranto – 10 June 2002

K reconstruction: T0 findingK reconstruction: T0 finding

o Applied to tagged events with K decay products with ECAL cluster associated.

o From K decay vertex position, cluster times, momentum of K and charged daughter at vertex is possible to trace back the T0 of the event.

t+-t- (ns)

2001 data

V.Patera – KLOE GM – Otranto – 10 June 2002

K reconstruction: multiple scattering

K reconstruction: multiple scattering

K (DTFS) first point - K(DHIT) first point

Kaon length > 80 cmKaon length < 80 cm

RED : Lynch approximation

PINK : Gaussian formula

= 2.3 MeV/c

= 2.9 MeV/c

= 1.7 MeV/c

= 2.6 MeV/c

KL

OE

mem

o 27

0

Good performance in KPM stream are obtained switching off m.s. only for K . Optimization still needed !! ( m.s. step, m.s. calculation..)

V.Patera – KLOE GM – Otranto – 10 June 2002

K retracking AC pathK retracking AC path

use dcdbini raw2dtce dconvr dcprar - merge atfmod/par=1 vtxfin/par=1 -eclmod ecl_kpmfilt kmerge -t0_find/par=4 atfmod/par=2 -vtxfin/par=2

The correct merging of the broken tracks must be done at level of pattern candidates DTCE1 and DHRE1 banks are needed. The minimal AC path for K retracking is reported. The red modules have been updated/written for this stream

The KPM retracking is very CPU consuming. The production rate on fibm12 has been estimated to be ~ 2 pb-

1/day/CPU

Now M.S. is switched off for K here !!!

V.Patera – KLOE GM – Otranto – 10 June 2002

New vs Old: comparison is on the way

New vs Old: comparison is on the way

We are tuning the retracking on MC. To use old reconstruction

chain we are forced to use the events streamed by the OLD

selection algorithms.

The problem is a multivariate one.. We analize one refinement

per time, but correlations are big! The fine tuning is still

missing and only relative comparison are presented.

The efficiencies have been studied in a subsample of tagged

events: given a tag we look at what happen in the opposite

emisphere.

V.Patera – KLOE GM – Otranto – 10 June 2002

KPM MC sample selectionKPM MC sample selection

The KPM EVCL algorithms are OR-ed together. There is a big overlap among the three. The shown efficiency is computed by MC. Estimation from DATA is in progress

~ 5x105 MC events have been generated

and reconstructed (with MB addition in the Drift Chamber). Out of that only ~

1.7x105 are filtered as KPM

V.Patera – KLOE GM – Otranto – 10 June 2002

New vs Old : K momentum resolution

New vs Old : K momentum resolution

@ first hit @ vertex

V.Patera – KLOE GM – Otranto – 10 June 2002

New vs Old : K momentum resolution/2

New vs Old : K momentum resolution/2

The distorsion induced in the OLD rec. gets more evident as far the track gets longer

Kaon Prec – Ptrue distribution at the decay vertex versus the Kaon decay path

V.Patera – KLOE GM – Otranto – 10 June 2002

New vs Old: vertex resolution

New vs Old: vertex resolution

New

Old

The vertex resolutionis slightly improved. In particular tails are reduced

V.Patera – KLOE GM – Otranto – 10 June 2002

New vs Old : broken tracks New vs Old : broken tracks

Distribution of total length vs momentum of splitted kaons of the entire MC sample (1.7x105 ev).The merging get rid of most of the broken track better decay length distribution !

OLD

NEW

V.Patera – KLOE GM – Otranto – 10 June 2002

New vs Old : resolution on PdaughterNew vs Old : resolution on Pdaughter

The K momentum improved resolution slightly improves also the reconstruction of the daughter momentum in the K rest frame.

Distribution of the reconstructed M0

2 in the K rest frame

The peak width can be looked at also in data !!

V.Patera – KLOE GM – Otranto – 10 June 2002

New vs Old : resolution on PdaughterNew vs Old : resolution on Pdaughter

Distribution of the reconstructed neutrino invariant mass squared in the K rest frame

V.Patera – KLOE GM – Otranto – 10 June 2002

New vs Old : tracking eff. vs DC hitsNew vs Old : tracking eff. vs DC hits

On the selected sample the tracking efficiency are similar. This analisys must be repeated on data to have the final answer on the retracking behaviour !

K tracking efficiency

V.Patera – KLOE GM – Otranto – 10 June 2002

New vs Old : tracking eff. vs cos K

New vs Old : tracking eff. vs cos K

Due to the request for at least a TAG to compute any eff, large events statistic is needed.

Rec.

Rec.

V.Patera – KLOE GM – Otranto – 10 June 2002

New vs Old : tagging eff. vs DC hits

New vs Old : tagging eff. vs DC hits

The new reconstruction seems to behaviour better than the standard one. The tagging efficiency is sensitive to the combination of tracking and vertex eff iciency

N.B. is the eff of a very clean sub-sample!

Tagged/tracked eff.

V.Patera – KLOE GM – Otranto – 10 June 2002

ConclusionsConclusions

• The retracking code of the KPM stream is in its final shape, yet has to be tested on high statistics

• Sizeable (but not fantastic) improvement with respect to the standard reconstruction at first glance

• Fine tuning is missing ( cuts on track merging, m.s. scatterers distribution, T0 for non tagged events..)

• DST production could ( and should ) start since July