&
ZEUS
Trigger Selection:
INITIAL SELECTION : DST 34 Charged current
(EXO TLT 2
or EXO TLT 6
or PT(-ir) > 6 GeV)
& (PT > 7 GeV)
FLT (at least one of the slots) : SLOTS 60 (Gen CC)
61 (Diff CC)
41 (High Et)
42
43 (High Et & good track)
SLT : SLOT EXO 4
see http://www-zeus.desy.de/~tapperad/ZEUS_ONLY/trigger/slt.html
TLT (at least one of the slots) : SLOTS DIS 30,31
EXO 18,22
see http://www-zeus.desy.de/~tapperad/ZEUS_ONLY/trigger/tlt.html
Cuts (All Data):
Q2 (jaquet Blondel) > 200
y (jaquet Blondel) > 0.9
Muon Removal (Sjors Grijpink - http://www-zeus.desy.de/~grijpink/muffcandlist/)
NC background removal (Sinistra e-finder)
Events rejected as NC if
e prob >0.9 (best sinistra candidate)
& E-Pz >20
& Pt(miss)<30
& e energy>4 (best sinistra candidate)
& Enear <5 (energy not assoc. with electron in eta,phi cone of 0.8)
& either:
e candidate is in CTD acceptance 15-164 degrees
track DCA < 15 (e track passes within 15cm of energy in Cal)
track P/E >0.25 (track must have at least 25% of energy in Cal)
or:
e candidate lies outside CTD acceptance
candidate must have at least 20 GeV of transverse momentum
Cuts (Gamma0 15-164 degrees):
Pt >12 (Missing Pt greater than 12 GeV)
Pt(-ir) >10 (Missing Pt excluding 1st inner ring greater than 10 GeV)
(removes forward beam gas events)
|Zvtx| <50 (vertex measured using CTD)
Pt/Et >0.5 for Pt <30
(reduces background from PhP and Beam gas as highly collimated)
Ngood >=1 (At least one 'good' track. -
Primary vertex track
Pt(track) >0.2
Passes within 1.5 cm of (0,0,0)
has polar angle 15-164 degrees
Ngood >(Ntrks-20)/4 (a large fraction of tracks required to be 'good')
Ebhac/Ebcal <0.9 for Ebcal >2 (Energy in BCAL not entirely hadronic)
|delta phi| <0.5 radians for Pt<30 (difference in angle measured by CTD/CAL)
|delta phi| <2.0 radians for Pt>=30
Cuts ( 15 > Gamma0 > 164 degrees):
Pt >25 (Missing Pt greater than 25 GeV)
Pt(-ir) >25 (Missing Pt excluding 1st inner ring greater than 25 GeV)
(removes forward beam gas events)
|Zvtx| <50 (vertex measured using timing of deposits in FCAL)
Cuts (Other & 'to do'):
Sparks: Orange spark rejection only (to be improved!)
Ora_SparkF
To Do : Beam gas estimation using pilot bunches
To Do : Remove Photo Production using background MC
To Do : Topology study of PhP events where e+ lost down beampipe
- 2 hadronic jets in opp. directions with missing Pt