1. Status of KLOE Status of the detector The y2000 data taking
Physics analyses
The spring 2001 data taking
Outlook
G. Finocchiaro
LNF 18 May 2001
Sci.Com. Open session

2. The KLOE detector
d=4m
18 May 2001
G. Finocchiaro

3. EmC: time and energy performances)
GeV ( ps 54 E =
s(t)
 50 ps
Time resolution (neutrals channel only)
Energy residuals
e+e-e+e-g Eg from DC
Energy resolution
e+e-g
effects due to the beam (spread and bunch to bunch fluctuation) and to EMC cell to cell variation have been subctracted from the constant term
18 May 2001
G. Finocchiaro

4. EmC Calibration Monitoring & Stability
MeV
November 2000, end cap
(e+e-  gg events)
Energy variations (~2%)
measured and corrected
every 100 nb-1
Nrun
MeV
Energy absolute
calibration  0.1%
After correction
Nrun
18 May 2001
G. Finocchiaro

5. EmC resolution on full neutral channels
f  p0(h)g  ggg
mp0 = MeV
sm = MeV
mh = MeV
sm = MeV
p0  gg
h  gg
PDG ‘00
KLOE 10.7 pb-1
18 May 2001
G. Finocchiaro

6. DC: s-t relations coefficients vs. P
Linear and quadratic
Higher orders cm
p (mbar)
Constant term
18 May 2001
G. Finocchiaro

7. DC resolution and stability
Residuals
Resolution
Well below 200 mm spatial resolution
in most of the impact parameter range
Drift distance (cm)
Stability vs Pressure
calibration performed when residuals > 40mm
each color represents a calibration point
1 month
18 May 2001
G. Finocchiaro

8. DC momentum resolution I
sp (MeV/c)
fK+K-
e+e-e+e-
sp/p < 0.3%
45°<<135°
After correcting for K  dE/dx:
mf= MeV
s = 1.2 MeV
Polar angle
18 May 2001
G. Finocchiaro

9. DC momentum resolution II
KS  p+p-
pc.o.m. = 110 MeV/c
sp = 1.8 MeV/c
mpp = MeV/c2
sm = 1 MeV/c2
18 May 2001
G. Finocchiaro

10. The KLOE Data taking
18 May 2001
G. Finocchiaro

11. A good day in Y2K ® L=650nb-1 500 mA 2000 Hz 1  1031 currents
trigger rate
2000 Hz
1  1031
luminosity
18 May 2001
G. Finocchiaro

12. Informations provided to DAFNE
Luminosity (with LABs)
Crossing point position (60mm in x,y ; 1mm in z)
Dimensions of luminous point (100mm in x,y ; 1mm in z)
Center of mass energy (using Bhabha’s and KS  p+p-)
Background
see next slide
QCAL rate
Trigger rate
EndCap rate (cosmic run)
18 May 2001
G. Finocchiaro

13. Data quality control September/December 2000 Wt Avg = MeV
s Wt Avg = ± 0.001
Center of mass energy
monitored by the KLOE offline analysis: all the “jumps” are correlated with machine changes and f scan.
Wt Avg =
Ks mass reconstruction stable during the physics runs
MeV
m(Ks) Wt Avg = ± 0.001
Kspp/pb-1
September/December 2000
18 May 2001
G. Finocchiaro

14. Event streaming: datarec flow diagram
Data composition:
700 Hz Unvetoed cosmics
400 Hz Prescaled cosmics
900 Hz Mach.Bkg + Bhabha <20o
100 Hz Physics (f + Bhabha>20o)
2100 Hz
RAW
Prescaled
cosmics
1650Hz
Cluster reconstruction
5 ms/evt
Cosmic filter
Background filter
Calibration Bhabhas
520Hz (26% of raw)
DC track/vertex recon.
151 ms/evt
DC track/vertex recon.
UFO
Event classification
K +K -
KLKS rp
Rad
m+m-
p+p-
40Hz
Bha
50Hz
18 May 2001
G. Finocchiaro

15. datarec performance in fall 2000
Evts. acquired
Evts. processed
Acquisition rate
Reconstruction rate
Farm bandwidth
23 Sep
11 Dec
End of data taking
Follow-up
After Xmas
Missed runs
Reprocessing
No DC trig
Once in stable situation, able to follow with ~75% of data processed
18 May 2001
G. Finocchiaro

16. y2000 Data composition (Offline L int= 23.1 pb-1)
Stream
Events (M)
Volume (GB)
Summary
kpm
ksl
rpi
rad
clb 19 64 6 23 1
687
2270
166
520
112M Events
3.6 TB
bha
127
2623
2.6 TB
flt
afl
cos
1248 31 96
3791 92
273
1379M Events
4.2 TB
Raw data: 5605M Events, 13.6 TB
Physics: 2.0% of total events
25% of raw volume
160 GB/pb-1
Total : 24 TB
Avg. rec. time per trigger: 38ms
Avg. rec. time per tracked event: 151ms
Avg. bandwidth on 40 CPU’s: 1060 Hz
10.9M KL tags
7.2M KL crash
18 May 2001
G. Finocchiaro

17. The KLOE physics program
Luminosity
arrow (pb-1)
CPT limits (KS ® p+e -n /p-e+n vs KL ® p+e -n / p-e+n)
CP violation studies (double ratio+interf.)
rare and not so rare KS decays (gg, pee, pmm, pnn)
kaon form factors (KL ® pl n, K  ® p0 l n)
K± decays (in particular p0e±n, ppp)
sHAD for (g-2)m and aem(mZ2)
semileptonic KS decays (KS ® pl n)
regeneration measurements at low momenta
f®p+p-p0
radiative f decays (f ® hg , h’g , f0 g , a0g , …)
2000
1000
100 20
non Kaon physics
Kaon physics
18 May 2001
G. Finocchiaro

18. Non-Kaon Physics: preliminary results
Analysis of f radiative decays:
scalar sector
BR(f0 g  p0p0g), BR(f  0 g  p+p-g)
BR(fa0 g  hp0g)
pseudoscalar sector
BR(f  hg) and h-h mixing angle
Measurement of s(e+e- p+p-) by using the process e+e- p+p-g with the g radiated in the Initial State
f  p+p-p0
PRELIMINARY results based on ~ 17pb-1
unknown nature of f0,a0 mesons (qq,qqqq,KK,…)
test of CHPT
direct vs indirect (rp) contribution
18 May 2001
G. Finocchiaro

19. Scalar states: f  0g  popog
Analysis cuts:
5 prompt clusters with g>21o
Kin. Fit (mass constrained)
|mpog-mw(PDG)|<3 s(mw)
cos()>0.4
f  a0 g  p0 h g
f  r0p0  p0 p0 g
Preliminary 2000 result (17.2 pb-1):
Nobs = 2164
Nbkg=
Excess of 1712 ± 51 events p0 g
cosy
18 May 2001
G. Finocchiaro

20. Scalar states: f hpog Selection: Signal:
  p0 g (via f a0g, f rp0)
Main backgrounds:
e+e- w p0  gp0
f p0 p0 g
f g 3,7 g (5 g observed)
Selection:
No tracks, 5 prompt photons, ETOT>900MeV
Kin. fit to select  p0 g states
2nd kin. Fit imposing  and p0 mass
Preliminary 2000 result (17.2 pb-1):
Nobs = 1109
Nbkg=
N(f hpog) = 565±42 events
18 May 2001
G. Finocchiaro

21. Background estimate and subtraction
Main source = hg  7g , wp0  5g for f  p0p0g hg  “7g“ , p0p0g for f  hp0g
18 May 2001
G. Finocchiaro

22. Scalar decays result summary
KLOE (*) SND CMD-2 BR (fp0p0g) 0.810.09 0.10   0.08  0.06 BR (fhp0g) 0.15 0.14   0.24  0.10
(*) KLOE 99 results: 193 evts (1712 in y2K data) evts (564 in y2k data)
fhp0g
fp0p0g
m(p0p0) (MeV)
18 May 2001
G. Finocchiaro
m(hp0) (MeV)

23. Pseudoscalar states: BR(fhg p+p-3g)
Bulk of fg events out of the figure range (365MeV g) !
fg p+p- g p+p-3 g
3 prompt g’s in EmC, 1 prompt vtx
Eg=60MeV (radiative)
Ep++ Ep-<412 MeV (ppp killer)
Eggg>520 MeV (KsKL killer)
Kin. Fit (no mass constraints)
Ellipse Cut on energy of 2 most
energetic g’s (fg rejection)
18 May 2001
G. Finocchiaro

24. BR(fhg p+p-3g) (cont.)
KLOE Preliminary
1999 DATA (2.4 pb-1)
21.0±4.6 events selected (bkg< 0.4, eff~19%)
(using a constr. mass fit)
BR(fhg) = ( 8.9 ± 2.0 ± 0.6) 10-5
(6.7 ± 3.5) 10-5 (PDG)
(6.7 ± 2.1) 10-5 (CMD2)
2000 DATA (16 pb-1)
~ 120 candidates after background subtraction (systematics still under study) s(mixing)~1o
18 May 2001
G. Finocchiaro

25. f  g, f  p0g p0g band hg band Analysis of 3g events: Kin. fit
correlation between cosqgg
and DEgg (non radiative gs).
Background uniform in the sidebands.
p0g band
KLOE PDG
N(h)/N(p) 0.02 0.35
BR(fhg) 0.008 0.033
(10-2)
BR(fp0g) 0.01 0.10
(10-3)
hg band
18 May 2001
G. Finocchiaro

26. Hadronic cross section measurement
AIM: measure s (e+e-p+p-, Q2) RELEVANT FOR amhad
NEW METHOD: measure s (e+e-p+p-g) vs. Eg (ISR) at fixed s=mf
1 vtx near IP, 35 o< < 155 o
likelihood cut (Bhabha killer)
|mtrack-mp|< 9.6 MeV
5°< g <21° (DC-based selection): enhance statistics, reduce FSR and ppp background
Efficiency vs Q2 mostly from data (trigger effect)
Absolute comparison with EVA Montecarlo generator including:
1) Matrix element ISR+FSR+Interf.
2) Collinear radiation at LO
20 pb-1 : check with MC
200 pb-1 : cross section measurement + fit to p form factor (r0 mass and line shape)
5°< g <21°
Q2p+ p- (GeV2)
18 May 2001
G. Finocchiaro

27. Preliminary f  p+p-p0 ~3M events
3 contributions to the binned Dalitz plot
Preliminary
f  r, 0 p0, 
f  p+p-p0 (direct)
e+e- wp 0
E0 – mp0 GeV
Parameter
Fit Result
PDG value
m(r0) MeV/c2
773.00.6
776.00.9
m(r+) MeV/c2
775.30.4
Dm(+/-) MeV/c2
0.40.3*
G(r0) (MeV)
145.62.2
150.20.8
A(direct)/A(rp)%
8.50.5
-1511
f(direct)-f(rp)
(889)o
(E+-E-)/3 GeV
* CPT test, at 5 ·10-4
Efficiency from MC. Work in progress to reduce systematics.
18 May 2001
G. Finocchiaro

28. KAON PHYSICS: Ks tagging by KLcrash
db = (compatible with machine energy spread)
Clean Ks selection by time of flight of KL interacting in calorimeter KS
b* distribution
“KLCrash”
Ecl  100 MeV
|cos(cl)|  0.7
b* = [0.195,0.245]
18 May 2001
G. Finocchiaro

29. KSKL: BR (KS p+p-)/BR (KS p0p0)
Important for e/e measurement
Tag from Klcrash
Efficiency from DATA
First result on:
=  0.016
(PDG mean value  )
Most of systematics from data
(dominated by reco. efficiency uncertainties)
18 May 2001
G. Finocchiaro

30. Ks semileptonic decays
BRth(KS®pen) = BR (KL®pen) GL/GS  6.7 if DS=DQ
Only measurement: (7.2±1.4)·10-4 from CMD-2 (based on 75 candidates)
Background from KS®pp (Signal/bckgd  10 -3)
KS®ppg (Signal/bckgd  1/3)
Strategy:
Kinematic cuts (2-body vs.3-body decays)
KS®pp
KS®pp
KS®pen
18 May 2001
G. Finocchiaro

31. Ks semileptonic decays
Strategy (cont):
time-of-flight to reduce
KS®pp and KS®ppg
...and identify KS®pen
D tpe = (t-L/bc)p- (t-L/bc)e
Reconstruct pn from KL
KS®pp
KS®pe n p- e+ n KL
18 May 2001
G. Finocchiaro

32. Ks semileptonic decays
(global efficiency ~7% mainly due to KLCRASH and geometrical acceptance)
KLOE very preliminary
Nov data, ~6pb-1:
226 signal events
July 2000 data, ~3.6pb-1:
136 signal events
Emiss-pmiss (MeV)
Emiss-pmiss (MeV)
18 May 2001
G. Finocchiaro

33. Analysis of KL pp events
KS Selection:
charged vertex
r < 5 cm from I.P.
50 < P < 170 MeV/c
400 < M < 600 MeV/c2
KL- tag by KS  p+p- KL
lS = 5.8±0.1 mm
18 May 2001
G. Finocchiaro

34. KL p+p- eFV=28% eselection=57% D.C. p - Em.C. p +
Kin. Fit to reject Km3 background
eFV=28% eselection=57%
purity = 98%
rejection factor 40,000
~ 130 evts./pb-1
Use KS p+p- for KL tagging
D.C.
Em.C.
p +
p -
~ 5 pb-1
KL mass (MeV/c2)
18 May 2001
G. Finocchiaro

35. KL p0p0 eFV=31% eselection=55% ~ 14 pb-1 KS p+p- KL p0p0
Kin. Fit to reject p0p0 p0 bckgd
eFV=31% eselection=55%
purity ~ 70%
rejection factor ~ 790
~ 90 evts./pb-1
~ 14 pb-1
KS p+p-
KL p0p0
KL mass (MeV/c2)
18 May 2001
G. Finocchiaro

36. KL Regeneration Decay length for selected events
Incoherent regen. expected (elastic) due to K momenta and small regen. volume BP DC
(sreg)bp = 75.7  9.6  10.6 mb
(sreg)dc = 51.9  6.2  mb
DC wall 750 mm C mm Al
Beam pipe 500 mm 61%Be + Al
Fit of Ks lifetime on sperical beam pipe
yields the correct value.
18 May 2001
G. Finocchiaro

37. The spring 2001 data taking A good day in spring (27 April) 500 mA
Currents (mA)
Lumi (1030)
Int Lumi (nb-1)
500 mA
1.5·1031cm-2s-1
1.2·pb-1
18 May 2001
G. Finocchiaro

38. Data filtering 2000 DATA 2001 DATA <Event processing time> (ms)
Total
Tracked
Fraction of tracked events
(function of DAFNE conditions)
has increased
Fully reconstructed events per trigger (%)
18 May 2001
G. Finocchiaro

39. 2001 DATA taking: bgkd rates
Both luminosity and background increased
Rate of energy releases > 7 MeV
23-30 Nov 2000
23-30 Apr 2001 E W
18 May 2001
G. Finocchiaro

40. 2001 DATA taking: bgkd rates
… but the ratio is (almost) unchanged E W
23-30 Nov 2000
23-30 Apr 2001
18 May 2001
G. Finocchiaro

41. 2001 DATA taking: bgkd rates
Rates on the inner layer of DC increased more…
23-30 Nov 2000
23-30 Apr 2001
18 May 2001
G. Finocchiaro

42. 2001 DATA taking: impact on physics
Denominator:
KSp0p0
e2000=34% e2001=34%
Denominator:
KLcrash
1 track w/p*=106MeV/c
e2000=96.7% e2001=96.6%
18 May 2001
G. Finocchiaro

43. 2001 DATA taking: impact on physics (2)
fhg, hgg
fhg, hp+p-p0
Change in rate compatible with different s
18 May 2001
G. Finocchiaro

44. Conclusions Several analyses are close to publication.
The KLOE detector is performing well.
Several analyses are close to publication.
The KLOE detector is sensitive to high background
rates (mainly the DC: how much integrated charge
before damaging the wires in the innermost layers)?
A first look at data collected in 2001 (quite respe-
ctable bckd rates) indicates that the data quality is
not spoiled.
It would be VERY important to integrate ~200pb-1 in
stable conditions.
18 May 2001
G. Finocchiaro