NA48 INFN-CSN1 Frascati E. Iacopini 11 Novembre 2003

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)

from NA48/1

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, 2003 A. Ceccucci: NA48/1 Status Report to SPSC

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

Six candidates!! The red dots are the events passing 0 < tK < 3 tS KL →p0 p+p- m m m October 28, 2003 A. Ceccucci: NA48/1 Status Report to SPSC

The six KS →p0 mm candidates Consistent with being a signal BR measurement in progress … October 28, 2003 A. Ceccucci: NA48/1 Status Report to SPSC

(piccolo, determinato dall’ampiezza K→ 3p) KS  , 0ee fattore di forma (O(p6)): (Buchalla, D’Ambrosio,Isidori:hep-ph/0308008) (piccolo, determinato dall’ampiezza K→ 3p) KS  p0e+e-

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, 2003 A. Ceccucci: NA48/1 Status Report to SPSC

from NA48/2

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

NA48 Set-Up

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

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  1 + 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  0 ... 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) _ _

Dalitz plot

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

Statistics for asymmetry Statistics of supersamples in mln K±  ± + - 1 2 3 total HD BU HD BD HU BU HU BD 98 166 38 302 150 58 86 294 127 162 50 339 130 142 60 332 total 505 528 234 1313 ~ 450 mln K±  ± + - events of SS-1 reprocessed for the express analysis October 28, 2003 V. Kekelidze: NA48/2 Status Report to SPSC

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

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 …

Acceptance cancellation check < a± > = (a+ + a-)/2 = (1.2  2.3)10-4 a+ a- (a+ + a-)/2 October 28, 2003 V. Kekelidze: NA48/2 Status Report to SPSC

Dg stability with momentum (aS + aJ)/2 + offset October 28, 2003 V. Kekelidze: NA48/2 Status Report to SPSC

Time stability of acceptances aS + offset aJ + offset different achromats different achromats HD HU HD HU October 28, 2003 V. Kekelidze: NA48/2 Status Report to SPSC

(aS + aJ)/2 + offset HD HU Time stability of Dg October 28, 2003 V. Kekelidze: NA48/2 Status Report to SPSC

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, 2003 V. Kekelidze: NA48/2 Status Report to SPSC

beam line, detector and trigger October 28, 2003 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

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

Spares

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 -10 0 10 T/2 ns, Station2 – Station3 Beam rate ~20 MHz Momentum resolution 1.1% P(K), GeV/c 50 60 70 -0.2 0 +0.2 50 60 70 P0/P(K) - P0/P(S) P(S) , GeV/c

Foto

Reconstructed K±  ± + - PK, GeV/c 40 50 60 70 80 K- P, GeV/c K+ M(3)+ GeV/c2 K+ K- M(3)- GeV/c2

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)

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

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

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

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, 2003 V. Kekelidze: NA48/2 Status Report to SPSC

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

Time stability of acceptances in momentum bins aS + offset aJ + offset October 28, 2003 V. Kekelidze: NA48/2 Status Report to SPSC

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, 2003 V. Kekelidze: NA48/2 Status Report

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

Beam availability & supersamples SS-1 August 6- 20