1. KLOE at DAFNE The DAFNE facility Physics at a f-factory
P. de Simone – Cipanp 2000
KLOE at DAFNE
P.de Simone,INFN LNF
for the KLOE collaboration
Cipanp 2000, May 22-28, Quebec City
The DAFNE facility
Physics at a f-factory
The KLOE experiment
Data taking in 1999
Outlook
The KLOE experiment in the DAFNE hall

2. DAFNE specifications L0 = 5 × 1032 cm-2 s-1
P. de Simone - Cipanp 2000
L0 = 5 × 1032 cm-2 s-1
conservative approach 
L0 single bunch  5 ×10 30cm-2 s-1 L VEPP-2M
but high collision frequency, so that
L0 = L0 single bunch × N bunches
E beam
510 MeV
N bunches
120
Bunch spacing
2.7 ns
Particles/bunch
9 × 1010
Crossing angle
25 mrad
Bunch length (sz)
3.0 cm
Bunch size (sx/sy)
2000/20 mm
Performance in ’99  L 20 ÷30 bunches  1  3 × cm-2 s-1
Jan-Mar2000  kickers modified to dump higher order mode and IR quads adjustments made
May 2000  L 6 bunches  2 × cm-2 s-1

3. DAFNE performance in ‘99
P. de Simone – Cipanp 2000 30 13 1
Bunches
50%
550 mA
Imax
40%
200 mA I
20%
1 × 1031 cm-2 s-1 L
11/1998, Pre-KLOE roll-in, multi-bunch mode
250%
110 mA
45%
20 mA
30%
1.6 × 1030 cm-2 s-1 L1
11/1998, Pre-KLOE roll-in, single-bunch mode
Design/bunch
Achieved
At end of DAFNE commissioning, performance results obtained were quite respectable
20—40
350/250 mA
I-/I+
~1.5%
1.8 × 1030 cm-2 s-1
Lsustained
~3%
3.5 × 1030 cm-2 s-1
Lstart
12/1999, Best conditions delivered to KLOE in 1999
Situation changed after installation of KLOE
Jan-Feb 2000: Kickers modified to damp higher-order mode
Mar 2000: Vacuum broken at KLOE IP and IR quads adjustments made

4. Physics at a f-factory Target L0 × 3.2 mb  1600 f per second
P. de Simone – Cipanp 2000
Physics at a f-factory
Target L0 × 3.2 mb  f per second
vector meson f  Jpc = 1 - -, Mf = ±0.008 MeV
Mode
Br(%) bK
bgctK(cm)
plab(MeV/c)
# per year
K+K-
49.1
0.24
95.4
127
7.9 × 109
KLKS
34.1
0.21
343.8
0.59
110
5.5 × 109 rp
12.9 -
182
2.1 × 109
p+p-p0
1.9
462
3 × 108 hg
1.28
362
2 × 108
neutral and charged K pairs collinear and monochromatic
the observation of one K guarantees the existence of the other, with determined direction and identity, i.e., K’s can be tagged  this enables KLOE to be essentially SELF-CALIBRATING via numerous K decay channels
absolute normalization of the KS, KL fluxes

5. The KLOE physics program
P. de Simone – Cipanp 2000
The KLOE physics program
The main physics motivation of the KLOE experiment is the measurement of the CP violation parameters to an accuracy of O(10-4)
with the classic method of the double ratio
and by quantum interferometry f1 f2 t2 t1 e+ e-
KL ,KS
KS ,KL
f1 = p+p-
f2 = p0p0

6. The KLOE physics program
P. de Simone – Cipanp 2000
The KLOE physics program
Measurements of CP and CPT violation parameters
double ratio KL  2p vs. KS  2p
interferometry KS,KL  f1,f2
KS ,KL semileptonic asymmetries
Kaon physics
form factors KL pl n, K+ pl+n, eventually Kl4
rare KS decays KS pl n, also KS pee, pmm, pnn
regeneration cross section at low momentum
Non-kaon physics
radiative decays s(f  f0g, a0g),
Br (f  hg)/Br (f  hg)
s(e+e-  hadrons) using e+e-  p+p-g (ISR)

7. The KLOE Experiment Be beam pipe (0.5 mm thick)
P. de Simone – Cipanp 2000
Be beam pipe (0.5 mm thick)
Instrumented permanent magnet
quadrupoles (32 PMT’s)
Drift chamber (4 m   3.3 m)
90% helium 10% isobutane
12582/52140 sense/total wires
Electromagnetic calorimeter
Lead/scintillating fibers
4880 PMT’s
Superconducting coil
B = 0.6 T (  B dl = 2.2 T·m)

8. Electromagnetic calorimeter
P. de Simone - Cipanp 2000
Physics demands
Construction solutions
measure the KL  p0p0 vertices with
svertex 1. cm
reduce the background KL  3 p0
sE/E  5% /
st  70 ps /
srf (apices)  1 cm
4p coverage and high efficiency for g detection
some particle ID capability
hermetic lead/scintillating fibers calorimeter
barrel 24 modules 4.3 m long and
23 cm thick
end caps C shaped modules of variable length
sampling fraction of  13 % for MIP ( 1 mm fibers mm lead foils 
r  5 gr/cm3 and X0  1.5 cm )
the readout granularity is 4.4×4.4 cm2 , varying slowly in size across the module
module read-out at both ends for the reconstruction of the z coordinates
5000 ADC & TDC channels

9. Unique to the KLOE calorimeter
P. de Simone - Cipanp 2000
.. is the determination of the KL flight path 
EMC measures
impact point of photon L
total time-of-flight t = tL + tg
DC measures Pf- PS
Each g gives an estimate of LL
Starting point for kinematic fit
EMC L LL Lg KS
Lg2 = L2 + LL2 – 2L•LL
ctg = LL / bL + Lg
With Eg  100 MeV
st  70 ps/E (GeV)
Obtain sL  0.7 cm for 4 g’s

10. EMC time & energy calibration
P. de Simone - Cipanp 2000
e+e- e+e-g Eg from DC
Non-linearity ~1%
d(E)/E
E (MeV)
s(E)/E 57 ps
s(t) = Å
120 ps Å 40 ps 1 2 3 1 2 3 E /
GeV
E (MeV)
Bunch structure
Miscalibration term

11. EMC time & energy calibration
P. de Simone - Cipanp 2000
f  p+p-p0 Eg from DC
Non-linearity ~1% 57 ps
s(t) = Å
120 ps Å 40 ps 1 2 3 1 2 3 E /
GeV
Bunch structure
Miscalibration term

12. In agreement with PDG < 1%
Emc mass reconstruction
P. de Simone - Cipanp 2000
f  p+p-p0
M(p0  gg)
f  hg
M(h  gg)
M = MeV
sM = 14.7 MeV
M = MeV
sM = 41.8 MeV
MeV
MeV
In agreement with PDG < 1%

13. Drift chamber Physics demands Construction solutions
P. de Simone – Cipanp 2000
Physics demands
Construction solutions
lL  340 cm  large volume
KL decay vertices are uniformly distributed  high and uniform track and vertex reconstruction efficiency
srf  200 mm,
sVrf  500 mm, sVz  2 mm
good momentum resolution @ 0.6 T 
sp / p 0.4 %
gas transparency to reduce regeneration and multiple scattering
walls transparency because of the low energy g’s
uniform cells structure on a large volume of 4 m diameter and 3.3 m length
square cells, field:sense = 3:1
60 ÷ 150 mrad stereo angle
cells 2×2cm2 inner 12 layers;
cells 3×3cm2 outer 46 layers
low mass
25 mm W sense wires
80 mm silver plated Al field wires
gas  90% He – 10% iC4H10
X0 (wires+gas)  900 m
whole mechanical structure in carbon fiber  0.1 X0
sense field guard = total wires !

14. Drift chamber
P. de Simone - Cipanp 2000

15. time-to-space relations
P. de Simone - Cipanp 2000 ns
Drift velocity not saturated and
depends on:
drift distance (s)
cell shape (b)
crossing angle (f)
3 × 3 cm2 cells
Constant f
Different b b s f cm
Compact parameterization of
t-s relations:
6 reference cells (b)
36 bins in crossing angle (f)
242 t-s relations total
each described by 5th order Chebyshev polynomial ns
3 × 3 cm2 cells
Constant b
Different f cm

16. DC resolution and efficiency
P. de Simone - Cipanp 2000
The contribution due to the electron diffusion is  140 mm for 1 cm of drift
The primary ionization statistics has been parametrized as a function of the mean free path between two consecutive ionizing collisions 
l = 718  14 mm corresponding to
np = 13.9  0.1 cm-1 clusters per cm, for
2 GeV muons ns
Layer
3×3 cm2 cells all layers
2×2 cm2 cells all layers
Efficiency
All impact parameters
eHW  99 % eSW  97 %

17. After calibration: srf 150 mm
DC performance
P. de Simone - Cipanp 2000
After calibration: srf 150 mm
KS  p+p-
Bhabha
sM 1 MeV/c2
sp/p < 0.3%
45° < q < 135°
Momentum Resolution (Mev/c)
KL p+p-p0
M(p0) = MeV
Polar Angle (Degrees)

18. permanent magnet quadrupoles
Quadrupoles and QCAL
P. de Simone - Cipanp 2000
45 cm
0.5 mm Be 9°
permanent magnet quadrupoles
10 cm
The QCALs have severe weight and space limitations 
r  8 g/cm3, and L  6 X0
Lead and scintillator tile sampling calorimeters. The absorber/scintillator ratio is chosen to increase the density at the expenses of a tolerable reduction in the light output
MC simulations show that  1.5% of the
KL  3p0 decaying inside the FV have only 4g detected, and in the vast majority of cases both g’s are lost in the quadrupole sink 
to reduce this loss the qudrupoles are instrumented with dedicated calorimeters: the QCALs

19. Trigger extremely low inefficiency on f events  few × 10-3
P. de Simone – Cipanp 2000
Physics demands
Construction solutions
at the target luminosity the f event rate is  1.6 kHz
extremely low inefficiency on f events  few × 10-3
reject/scale Bhabha events down to  3 kHz
reject/scale cosmic ray and machine background events
in DAFNE the bunch crossing occurs every  2.7 ns The KLOE trigger must work in continuous mode operation
two level trigger based both on calorimeter and chamber infos
T1 (  200 ns after f) fast trigger is synchronized with DAFNE clock and provides the start to EMC FEE
T2 ( 1.5 mm after T1) validation trigger provides the stop to DC TDC allowing for drift time and start the DAQ
T1 and T2 decisions are based on topology and energy deposits in calorimeter and/or number and distribution of DC hits

20. Data acquisition DAQ handles 23000 FEE channels
P. de Simone – Cipanp 2000
DAQ handles FEE channels
Designed for 5 KHz event rate and sustained bandwidth of 25 MB/sec
5 KB average event size
Low dead time (~2% at 10 KHz) independent of event configuration
All FEE channels digitized and
buffered during 2.2 ms dead time
Fully tested at design rate

21. Data taking: 1999 2.4 pb-1  7.7 × 106 f’s 1999 total: L dt =
P. de Simone - Cipanp 2000
First collisions at DAFNE in mid-April Single bunch mode f line-shape scan (3 nb-1) to find peak
Short data-taking periods in August, October, and November (~200 nb-1 each)
Sustained data-taking during November and December (L ~ 3.51030 cm-2s-1 )
1999 total: L dt =
2.4 pb-1  7.7 × 106 f’s

22. Background < 1 % (f  K+ K-)
Tagging of KL by KSp+p-
P. de Simone - Cipanp 2000
ls = 5.70 ± 0.05 ± 0.30 mm
KS identified by vertex with 2 tracks of opposite sign and
r  6 cm,z 8 cm from I.P.
50 < P single track < 170 MeV/c
400 < M inv < 600 MeV/c2
(KSp-p+) eid  72 %
50% of KLKS evts
Background < 1 % (f  K+ K-)

23. Tagging of KL by KSp0p0 20% of KLKS evts KS  p0p0 identified by
P. de Simone - Cipanp 2000
KS  p0p0 identified by
4 prompt clusters (0.9  b ) no associated tracks
q cluster  21° (to avoid hits on QCAL)
390 < M < 600 MeV/c2
(KSp0p0) eid  65%
20% of KLKS evts
Background < 1% (machine)

24. lL(charged) = 330  14 cm lL(neutral) = 349  12 cm
KL vertices measurement
P. de Simone - Cipanp 2000
KL tag by KSp+p-
charged vertices in 5° cone about pf – pS
neutral vertices with at least 5 neutral clusters on time
 KL  Kl3 , p+ p- p0  KL  3p0
KL FV
lL(charged) = 330  14 cm lL(neutral) = 349  12 cm

25. Tagging of KS by KL crashes
P. de Simone - Cipanp 2000
Single late neutral clusters are used to tag the KS
The measure of b(KL) is sensitive to the f boost and the machine energy spread
Tag efficiency  31% of KL KS evts
KL crash

26. KLp+p- selection from KLpln, p+p-p0
P. de Simone - Cipanp 2000
Apply a loose cut
Pmiss < 10 MeV/c
|M2miss| < (70 MeV/c2)2
KL  p+p-
sM ~ 1 MeV/c2

27. PID using TOF from EMC
P. de Simone - Cipanp 2000 t L L t KL IP

28. Charged/neutral fiducial volumes
P. de Simone - Cipanp 2000
Check alignment of FV’s using events with reconstructible charged and neutral vertices from same decay
K±  pp0
KL  p+ p-p0
KL  p+ p-p0
For KL  p+ p-p0 (shown), residuals not expected to differ from KL p0p0 but resolution is worse:
KLp+ p-p0
KL  p0p0
K±   Ng 2 4 Eg
60—80 MeV
100—120 MeV
100—120 MeV

29. Outlook & Data taking in 2000
P. de Simone - Cipanp 2000
In 1999, KLOE has collected 2.4 pb-1
Detector calibrated, performance fully satisfactory
CP violating events observed, other physics analysis going on (neutral and charged K decays…)
Preliminary results achieved on f radiative decays (hg, h’g, a0g, f0g,)
Next milestone: 100 pb-1 (1 year at L = 1031 cm-2 s-1  100 pb-1  108 KL)
Measurement of Re(e/e) to 10-3 statistical accuracy;
Measurement of Kl3 form factors, KS semileptonic decays
Measurement of regeneration cross section at p ~ 100 MeV
Complete analysis of f radiative decays