1. NA48
INFN-CSN Frascati
E. Iacopini
11 Novembre 2003

2. SPSC del 28 ottobre… Status Report di NA48/1: Augusto Ceccucci
(run Ks ad alta intensità del 2000 e 2002)
Status Report di NA48/2: Vladimir Kekelidze
(run K carichi 2003)

3. from NA48/1

4. KS →p0 ee 7 candidates meegg (GeV/c2) in the signal region
0 in the control region
Background: 0.15 events
The probability that all 7
events are background
is ~10-10
meegg (GeV/c2)
mgg (GeV/c2)
First observation of KS →p0 ee
October 28, A. Ceccucci: NA48/1 Status Report to SPSC

5. KS →p0 mm Mmmgg Mgg …dalla mia presentazione di Lecce …
Presto il risultato ! …
Mmmgg
Mgg

6. Six candidates!!
The red dots are the events passing 0 < tK < 3 tS
KL →p0 p+p- m m m
October 28, A. Ceccucci: NA48/1 Status Report to SPSC

7. The six KS →p0 mm candidates
Consistent with being a signal
BR measurement in progress …
October 28, A. Ceccucci: NA48/1 Status Report to SPSC

8. (piccolo, determinato dall’ampiezza K→ 3p)
KS  , 0ee
fattore di forma (O(p6)):
(Buchalla, D’Ambrosio,Isidori:hep-ph/ )
(piccolo, determinato dall’ampiezza K→ 3p)
KS  p0e+e-

9. First Observation
The plot shows the pp0 invariant mass, for decays with one identified muon
The b decay of X0 is the only source of S + in the neutral beam …
October 28, A. Ceccucci: NA48/1 Status Report to SPSC

10. from NA48/2

11. I Fasci …
Sezione verticale: gli assi dei fasci vengono fatti coincidere entro ~ 1 mm

12. NA48 Set-Up

13. New K12 beam line built for NA48/2
second achromat
first achromat

14. CP  Ag  (g+  g– )/(g+ + g–)  0
…dalla mia presentazione di Lecce …
La Fisica …
Misura della violazione diretta di CP nei decadimenti
dei K+ e K– in tre pioni carichi:
M (u,v)2  gu + hu2 + kv2
u = (2M/m2) (M/3 - E*)
CP  Ag  (g+  g– )/(g+ + g–)  0
Una “slope” in R (u)  N+(u) / N–(u) a Ag 
e la sensibilità prevista nella proposta era : Ag = 1.7  10-4
Misura del “quark condensate” <q q> della cPT attraverso la reazione Ke4 , i.e. K  e + - n (n) _ _

15. Dalitz plot

16. Strategia della misura
…dalla mia presentazione di Lecce …
Strategia della misura

17. Statistics for asymmetry
Statistics of supersamples in mln K±  ± + -
total
HD BU
HD BD
HU BU
HU BD
total
~ 450 mln K±  ± + - events of SS-1
reprocessed for the express analysis
October 28, V. Kekelidze: NA48/2 Status Report to SPSC

18. Osservabili aS & aJ : slopes di R(u)=N+(u)/N-(u)  r (1+a u)
BU N+(u)
t ~ 1 giorno
BD N+(u)
aJ(u) aJ
aS(u)
accettanza aS
BU N-(u)
BD N-(u)
aS = Dg = aJ
se aS(u) & aJ(u) rimangono stabili
a  0.5 (aS + aJ) = g
se aS(u),aJ(u) cambiano simmetricamente

19. Checks Sistematici di accettanza
Ra(u) = aS(u)/aJ(u)(1+da)u
BU N+(u) a+
BD N+(u)
aJ(u)
aS(u)
 aD   aU 
t = 1 day a-
BU N-(u)
BD N-(u)
aJ(u)
aS(u)
a+  da; a-  -da; (a+ + a-)/2  0
aU  g+da; aD  g-da
(aU + aD)/2  g
… se da è stabile nel tempo …

20. Acceptance cancellation check
< a± > = (a+ + a-)/2 = (1.2  2.3)10-4 a+ a-
(a+ + a-)/2
October 28, V. Kekelidze: NA48/2 Status Report to SPSC

21. Dg stability with momentum
(aS + aJ)/2 + offset
October 28, V. Kekelidze: NA48/2 Status Report to SPSC

22. Time stability of acceptances
aS + offset
aJ + offset
different achromats
different achromats HD HU HD HU
October 28, V. Kekelidze: NA48/2 Status Report to SPSC

23. (aS + aJ)/2 + offset HD HU Time stability of Dg
October 28, V. Kekelidze: NA48/2 Status Report to SPSC

24. are found much less significant
Systematics summary
Major systematics related to
- acceptance asymmetry
- time variation effects
are under control
Other possible systematics:
- residual (+ Earth) magnetic fields
- trigger efficiencies
- DCH’s efficiencies
- accidentals
- …..
are found much less significant
October 28, V. Kekelidze: NA48/2 Status Report to SPSC

25. beam line, detector and trigger
October 28, V. Kekelidze: NA48/2 Status Report to SPSC
Conclusion
NA48/2 experiment has been prepared:
beam line, detector and trigger
are put in operation & tuned
the major systematics are under control
& do not exceed statistical precision
to reach the proposal goals
more statistics are needed
Beam Request for 2004
as much proton time as possible
(400 GeV protons ~1·1012 ppp on T10)
as few beam interruptions as necessary

26. Al momento non sono ancora disponibili le minute dell’SPSC … ;
Conclusione finale
Al momento non sono ancora disponibili le minute
dell’SPSC … ;
informalmente sembra che il Comitato raccomanderà
al RB che NA48 possa prendere dati anche nel 2004,
per  3 mesi …
… il prossimo RB sarà il 13 novembre

27. Spares

28. KABES-1/2 (moved out by ~20 cm)
Beam rate ~20 MHz K+
time resolution
67 ps
entrance window
K+, K-
X,Y space
resolution
~100 mm
T/2 ns, Station2 – Station3 K-
time resolution
63 ps
T/2 ns, Station2 – Station3
Beam rate ~20 MHz
Momentum
resolution
1.1%
P(K), GeV/c
P0/P(K) - P0/P(S)
P(S) , GeV/c

29. Foto

30. Reconstructed K±  ± + -
PK, GeV/c K-
P, GeV/c K+
M(3)+ GeV/c2 K+ K-
M(3)- GeV/c2

31. lead to 40% statistics lost (beam stability dependent)
Selection criteria
radial cuts around the beam centres (in DCH1,4)
to symmetrize acceptances
day-by-day definition of the beam COG’s in each momentum bin
to reduce acceptance variations in time
Conservative cuts:
R(DCH1) > 11.5 cm
R(DCH4) > 13.5 cm
lead to 40% statistics lost
(beam stability dependent)

32. Spectrometer alignment
(after fine tuning of B)
surprising effect
MK – MPDG, KeV/c2
BUK+ & BDK- (to Jura)
~4 m / day
x DCH4
~ 35 KeV/c2
time variation term was compensated
BDK+ & BUK- (to Saleve)
day-sample

33. Osservabili AS & AJ - slopes di R(u)=N+(u)/N-(u)
BU N+(u)
t ~ 1 giorno
BD N+(u)
aS(u)
accettanza
R(u)S
aJ(u)
R(u)J
BU N-(u)
BD N-(u)
R(u)S = R(u)J  1+Dg
se aS(u) & aJ(u) sono stabili nel tempo
R = 0.5 (RS + RJ)  1+g
se Ra(u) = aS(u)/aJ(u) è stabile nel tempo

34. Ra(u) = aS(u)/aJ(u): Sa - slope
Checks Sistematici
+Sa
BU N+(u) R+
BD N+(u)
 RD 
 RU 
t = 1 day
-Sa
+Sa
-Sa R-
BU N-(u)
BD N-(u)
Ra(u) = aS(u)/aJ(u): Sa - slope
RU  1+g+Sa; RD  1+g-Sa
(RU + RD)/2  1+g
se Sa è stabile nel tempo
R+  1+Sa; R-  1-Sa; (R+ + R-)/2  0

35. a± for different achromat polarities
Beam geometry effects
a± for different achromat polarities
(a+ + a-)/2
(a+ + a-)/2
> 0
< 0 BD BU
October 28, V. Kekelidze: NA48/2 Status Report to SPSC

36. First look on K±  + - e± n
PDG K± mass
15807 events in SS-1 
BR = (3.87 ± 0.20)10-5
(PDG: (4.08 ± 0.09)10-5)
Background
~1% of Ke4
from K±  +- p±
from K±  p± 0D
M(3) GeV/c2
7105 expected
K±  + - e±n
in 2003
PK, GeV/c

37. Time stability of acceptances in momentum bins
aS + offset
aJ + offset
October 28, V. Kekelidze: NA48/2 Status Report to SPSC

38. Rare decay K   p  e+ e- : BR2.9 10-7
1400 events in 1 month
of data taking
~ 3500 events expected
in 2003 run
Events / 2 MeV/c2
500
400
300
200
100
M(p  e + e -), GeV/c2
October 28, V. Kekelidze: NA48/2 Status Report

39. la statistica effettiva…
…dalla mia presentazione di Lecce …
la statistica effettiva…

40. Beam availability & supersamples
SS-1
August 6- 20