rare kaon decays: opportunities for cern

2/4/2004 ROMA I A. Ceccucci, CERN 1

Rare Kaon Decays: Opportunities for CERN

Short Introduction

Present:NA48/1: KS → 0 ee () First Observations! NA48/2: K+ / K- Data Taking in 2003/2004

Future:NA48/3 K+ → + TODAY MAIN FOCUS

NA48/4 KL → 0 ee () NA48/5 KL → 0


CP-Violation in SM

'

'

'

ub

cb

td

ud us

cd cs

ts tb

V

V

V V

d d

s s

b b

V

V

V

V V

Ng=2 Nphase=0 No CP-Violation

Ng=3 Nphase=1 CP-Violation Possible

A phase in the CKM matrix leads to CP-Violation

Predictions: •Direct-CP Violation: ’/ 0 NA48, KTeV •CP violation in the B meson sector: ACP(J/ Ks), BaBar, Belle

Paradigm shift:Look for inconsistencies measuring the SM parameters using observables with small theoretical errors (< 10%)


Kaon Rare Decays and the SM

JCP=2(Triangle Area) is the unique measure of CP-Violation in SM

JCP = Im(Vud*VusVts

*Vtd) ~ cosc sinc Imt

Im t = A2 5 , Re t = A2 5

CP

-Vio

lati

on

(holy grail)

CP-ConservationKaons provide quantitative tests of SM independentfrom B mesons


Current Status

STILL A LARGE WINDOW OF OPPORTUNITY EXISTS

G. Isidori


NA48 Detector & Data Taking

1997

1998

1999

2000

2001

2002

2003

NA48: ’/

’/

’/

’/ lower inst. intensity

NA48/1 KS

NA48/1: KS

KL

no spectrometer

NA48/2: K

1996Total: 5.3M KL00

• CERN SPS• Magnetic spectrometer• Liquid krypton EM calorimeter2004NA48/2: K


The Past: NA48


NA48: Re ’/=14.7 ± 2.2 10-4

Top 10 articles from Physics Letters B:

• 1. The hierarchy problem and new dimensions at a millimeter http://dx.doi.org/10.1016/S0370-2693(98)00466-3 Physics Letters B, Volume 429, Issues 3-4 , 18 June 1998, Pages 263-272 Nima Arkani-Hamed, Savas Dimopoulos and Gia Dvali

• 2. A precision measurement of direct CP violation in the decay of neutral kaons into two pions http://dx.doi.org/10.1016/S0370-2693(02)02476-0 Physics Letters B, Volume 544, Issues 1-2 , 19 September 2002, Pages 97-112 J. R. Batley et al. (NA48 Collaboration)

• 3. Has the GZK suppression been discovered? http://dx.doi.org/10.1016/S0370-2693(03)00105-9 Physics Letters B, Volume 556, Issues 1-2 , 13 March 2003, Pages 1-6, John N. Bahcall and Eli Waxman

• 4. Testable scenario for relativity with minimum length http://dx.doi.org/10.1016/S0370-2693(01)00506-8 Physics Letters B, Volume 510, Issues 1-4 , 21 June 2001, Pages 255-263 Giovanni Amelino-Camelia

• 5. Role of effective interaction in nuclear disintegration processes http://dx.doi.org/10.1016/S0370-2693(03)00801-3 Physics Letters B, Volume 566, Issues 1-2 , 24 July 2003, Pages 90-97 D. N. Basu

• 6. Determination of solar neutrino oscillation parameters using 1496 days of Super-Kamiokande-I data http://dx.doi.org/10.1016/S0370-2693(02)02090-7 Physics Letters B, Volume 539, Issues 3-4 , 18 July 2002, Pages 179-187 S. Fukuda et al.

• ….

http://dx.doi.org/10.1016/S0370-2693(98)00466-3

http://dx.doi.org/10.1016/S0370-2693(02)02476-0

http://dx.doi.org/10.1016/S0370-2693(03)00105-9

http://dx.doi.org/10.1016/S0370-2693(01)00506-8

http://dx.doi.org/10.1016/S0370-2693(03)00801-3

http://dx.doi.org/10.1016/S0370-2693(02)02090-7


The Present: NA48/1


KL→ 0ee()

• Before discussing KL decays later in the talk, one has to address:

• CP-Conserving amplitude – Very small for KL→ 0ee , according to the NA48

measurement of KL→ 0 • CP-Violating amplitude from K0-K0bar mixing

– A measurement of KS→ 0ee() is required…– ...it was exactly the goal of NA48/1

KL KS

0

e

e


Converges to KLaxis at -0.6 mrad

MDX100magnet

MTNV magnet

W insertBe targ

et

Pt C

on

verter

KS KL

400 GeV

protons

Artist’s view of theTarget station(Vertical section)

0.6 m

Horizontal (KL) beam axis

0.5 m

10mm1:1

1:25 6.23 m

MTNV magnet

Bronze plug

MDX100magnet

CERN-NA48/1: High Intensity KS


NA48/1: KS → 0 ee

• To reject the KS → 0 0D decays that may mimic KS →0 ee if

a is lost, a cut mee>0.165 GeV/c2 is applied

KS →0 ee KS → 0 0D→ee()

MCMC


NA48/1: KS →0 ee

e+-e-+ (Odd Sign) DATA e+-e-+ DATA vs. MC

Blind Control& Signal regions

mee (GeV/c2)

me

e

(G

eV/c

2)


NA48/1: KS →0 ee

e+-e+- (Same Sign) DATAe+-e+- DATA vs. MC

Search region

me

e

(G

eV/c

2)

mee (GeV/c2)


NA48/1: KS →0 ee

Background from KL,S→ee : measured using NA48 KL data from 2001N(KL→ee, 2001) 10 × N(KL,S →ee, 2002)

mGeV/c2)

me

e

(GeV

/c2)


NA48/1: KS →0 ee

• DC proton beam• Read out window: ~ 200ns• Use time side band to

measure background from time-overlapping fragments from different decays

• Major component:– e+ 00(0)– Confirmed relaxing E/P

cuts m (GeV/c2)

Accidental backgrounds

me

e

(G

eV/c

2)


NA48/1: KS →0 ee

Source Control Region

Signal region

KS→0D0

D 0.03 0.007

KL,S → ee 0.11 0.075

e+20(0) 0.19 0.069

Total 0.33+0.18-0.11 0.15+0.05

-0.04• Many other sources investigated and found to be negligible (e,g neutral cascade decays)

• Blind analysis: Control and signal region remained masked until the study of the background was finished

SUMMARY OF BACKGROUNDS:


NA48/1: KS →0 ee

•7 candidates in the signal region

•0 in control region•Background 0.15

The probability that all 7events are background is ~10-10

me

e

(G

eV/c

2)

m (GeV/c2)

First observation of KS →0 ee


The 7 KS→0ee candidates

Mee (GeV/c2)

M (GeV/c2)

t/S

Mee (GeV/c2)


NA48/1: KS →0 ee

BR(KS→0ee, mee>165 MeV/c2) = (3.0+1.5-1.2(stat) ± 0.2(syst))×10-9

• Assuming vector interaction and unity form factor:

– In remarkable agreement with L. Sehgal prediction: ~5.5 ×10-9 NP B19 (1970)

BR(KS→0ee) = (5.8 +2.8-2.3(stat) ± 0.8(syst))×10-9

PL B576 (2003); hep-ex/0309075


NA48/1: KS →0 •Study of backgrounds from KL→ →•MC = 22 times the data•None of the simulated events falls in the signal box


NA48/1: KS →0

• Backgrounds from Neutral Cascade decays are rejected using a Momentum ratio cut

• Radiative () backgrounds:

0.04 ± 0.04 events


NA48/1: KS →0

• KL → + KS →0(0)

• KS→+- + KS →0(0)

• Studied in time side band • 6 events in ~125 ns• 0.18 +0.18

-0.11 background events expected in the in time signal region

Study of accidental backgrounds


NA48/1: KS →0 BR(KS→0) 109 = 2.9 +1.4

-1.2(stat) ± 0.2(syst) La Thuile 2004

First Observation!

6 eventsExpected back.0.22+019

-0.12


Dilepton invariant mass distributions

NA48/1

NA48/1


Extraction of form factor

Assuming VMD:

BR(KS →0 ee= 5.2 |as|2 10-9 |as|ee = 1.06 +0.26 -0.21 ±0.07

BR(KS →0 = 1.2 |as|2 10-9 |as| = 1.55 +0.38 -0.32 ±0.05

•VMD bs/as = 0.4

•Data compatible with VMD•Too low statistics to

extract the two parameters


Prediction using SM fit and NA48/1 result

20 12 2

4 4

Im( ) Im( )( ) 10 15.3 6.8 2.8

10 10t t

L CPV s sB K e e a a

See Buchalla,Isidori,D’Ambrosio for updates: hep-ph/0308008


The Present: NA48/2


NA48/2 : K+/K-

NA48/2 takes data also in 2004

•Search for direct CP violation in Dalitz plot slope asymmetry in K± decay• Ke4 decays• Rare K± decays

Simultaneous K+ and K- beams

NA48/2Very Preliminary

K± → ± ee


The Future: NA48/3 K+→+


Importance of Villars SPSC Meeting

From the address of R. Aymar, CERN CEO, tothe CERN staff on 13/1/04:

“…4. Another goal [for 2004-2010] would be:

– To define possible new fixed-target experiments, highly praised at another “Cogne” meeting in September 2004

5. To decide in 2006 on the possible planning and the start of implementation of the Linac 4 and/or any proposed R&D or experiment, depending on thefunds available or expected at that time...”


Implications of Villars • Focus on a programme that can have a big impact (don’t be

modest): – The reviewers will have a close look at the physics potential– Aim to a 10% measurement of |Vtd| via K+ → +

• Since the time is very tight, use what is best best known– Start from NA48/2 and extrapolate to the ultimate experiment

• To have a proposal evaluated by a Scientific Committee takes time– To seek approval in 2006 and take data in 2008 one has to act now

• Express Interest now in order to protect assets such as:– Availability of ECN3 (the only high radiation area for SPS)– Availability of high intensity, slowly extracted protons from SPS– LKr calorimeter

• Beam test as many things as possible in 2004 before the planned stop of the SPS in 2005 (2006?)


As an example, within the SM, using ACP(J/KS) and k as input:

BR(K+ → ) = 7.1 ± 1.0 × 10-11

(Kettell, Nguyen, Landsberg, hep-ph/0212321 )

K+→+ : Theory

220

411

2242

32

)(109.8

||||sin2

)()(

A

XXV

KBKB

lcctt

usW

eSD

•The hadronic matrix element can be extracted from the well measured K+→ 0 e •No long distance contributions

QCD NLOBuchalla,Buras 1999


K+→+ Experiment

Region I

Region II

+ in the K+ CM


State of the art:AGS-E787/E949 K+→+


AGS-E787/E949 K+→+

BR(K+ → + ) = 1.47+1.30-0.89 × 10-10 (SM~0.7 10-10)

hep-ex/0403036


K+→+ E949

• Run 12 weeks in 2002: – Result just released

– Plans to collect more data

to reach ~10 events @ SM

by 2010?

• Plans to continue with the stopped kaon technique at J-PARC?


CKM@FNAL-MI

•Proposal to measure ~100 K+→+ in flight

•Make redundant measurements: spectrometer and RICH– 22 GeV/c separated kaon beam

•TURNED DOWN BY P5 HEPAP SUB-PANEL FOR COST REASONS (100 MUSD)


CKM@MI22 GeV/c Separated Kaon beam

0 from K+0+ of soft energy not easy to veto

In addition 0 is backward in CM very bulky vetoesAre required


NA48/3

• Build on the NA48/2 infrastructure and detectors to save on cost

• Use a high energy (un-separated) kaon beam to simplify the rejection

of K+ → +


K+→+ NA48/3 (75 GeV/c)

K+→ ++-

K+→ +0

K+→ +

K+→ + Region II

Region I


NA48/3: Layout 0.0 • Unseparated, positive beam of 75 GeV/c with P/P~1% • Detectors upstream of the decay region:

– Differential Cherenkov counter (CEDAR) to positively identify kaons

– Beam spectrometer to make a redundant momentum measurement and to measure the kaon direction (KABES)

• It requires ~100 ps time resolution. We are investigating:– Micromega-type chambers (already employed in NA48/2) – Silicon micro-pixel detectors

• Detectors Downstream of the decay region– Double magnetic spectrometer for redundancy (with “Chinese”

copy of NA48 dipole) – Charged hodoscope for timing– Hermetic photon vetoes (upgrade NA48 ring anti-counters) – High performance forward photon veto (NA48 LKr calorimeter)– Finely segmented Hadron Calorimeter/Muon veto


NA48/3: Beam layout


Please find below the updated geometry files (Beatch) for the P42 and K12 beams to NA48:

Some documentation is available on the Web ( http://cern.ch/doble ) :

Beam Documentation for NA48

. . . . . . .K12HIKA (dated 18/03/04) represents the latest tentative attempt to describe the layout of a high- acceptance, small momentum-bite (75.00.7 GeV/c) K+ beam for a possible future K+ -> pi+ nu nubar experiment (NA48/3). The beam is derived from the existing target station T10 along the present K12 beam line of length 102.0m to the exit of the final collimator. It features large-acceptance, radiation-resistant quadrupoles, a front-end achromat for momentum definition, a beam cleaning stage and a parallel section, incorporating a CEDAR differential Cerenkov counter to tag the K+, followed by a second achromat accommodating 3 spectrometer+tracking stations: KABES(1),(2)+(3). For the measurement of the decay pi+, the last 12m section of the decay-vacuum tank (blue tube) has been replaced by an additional (first) spectrometer comprising detectors: WC 1,2, 4 fore and aft of a (new) MNP33-1 magnet, followed by the present (second) spectrometer comprising: WC 3, 5,6 and the present MNP33-2 magnet, giving pT-kicks of +-210 MeV/c (deflecting the beam by +-2.8mrad.), respectively, resulting in a ~35 mm parallel displacement inside the beam tube. Photon veto counters with radial coverage of, respectively, 40 < r < 90mm (PHOT.VETO1) and r < 90mm (PHOT.2) are shown in front of the Kevlar window and at the end of the hall - following a ~10 mrad. beam deflecting magnet (MBPL101245) installed in place of the HAC.

http://cern.ch/doble

http://cern.ch/doble/k12hika.txt


Turtle simulations:

1HISTOGRAM NO 21 DISTRIBUTION OF P IN GEVC 102.000 M FROM THE TARGET0 INTERVAL SCALE FACTOR.. 100 X'S EQUAL 5637 ENTRIES0LESS THAN 72.000 0

72.000 TO 72.200 0 72.200 TO 72.400 0 72.400 TO 72.600 0 72.600 TO 72.800 0 72.800 TO 73.000 1 73.000 TO 73.200 20 73.200 TO 73.400 178 XXX 73.400 TO 73.600 576 XXXXXXXXXX 73.600 TO 73.800 1210 XXXXXXXXXXXXXXXXXXXXX 73.800 TO 74.000 2068 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 74.000 TO 74.200 2870 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 74.200 TO 74.400 3727 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 74.400 TO 74.600 4598 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 74.600 TO 74.800 5354 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 74.800 TO 75.000 5637 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 75.000 TO 75.200 5596 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 75.200 TO 75.400 5126 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 75.400 TO 75.600 4288 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 75.600 TO 75.800 3400 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 75.800 TO 76.000 2623 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 76.000 TO 76.200 1820 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 76.200 TO 76.400 1068 XXXXXXXXXXXXXXXXXX 76.400 TO 76.600 552 XXXXXXXXX 76.600 TO 76.800 250 XXXX 76.800 TO 77.000 61 X 77.000 TO 77.200 8 77.200 TO 77.400 0 77.400 TO 77.600 0 77.600 TO 77.800 0 77.800 TO 78.000 00GREATER THAN 78.000 00 TOTAL NUMBER OF ENTRIES = 51031 INCLUDING OVERFLOW AND UNDERFLOW0 MEAN = 74.981 RMS HALF WIDTH = 0.7100HISTOGRAM NO 21 DISTRIBUTION OF P IN GEVC 102.000 M FROM THE TARGET

Momentum distribution: <p> = 74.981 GeV/c, RMS = 0.710 GeV/c


-60.000 -20.000 20.000 60.000 TOTALS I**---**---**---**---**---**---**I---------60.000 I I 0-54.000 I I 0-48.000 I I 0-42.000 I I 0-36.000 I I 0-30.000 I I 0-24.000 I 8T$$$$$$$$$A I 932-18.000 I A$$$$$$$$$$$$A I 5407-12.000 I Z$$$$$$$$$$$$Z I 8326 -6.000 I $$$$$$$$$$$$$$ I 9999 0.000 I $$$$$$$$$$$$$$ I 9999 6.000 I W$$$$$$$$$$$$W I 8536 12.000 I 4$$$$$$$$$$$$G I 5529 18.000 I 3Q$$$$$$$$T2 I 787 24.000 I I 0 30.000 I I 0 36.000 I I 0 42.000 I I 0 48.000 I I 0 54.000 I I 0 I**---**---**---**---**---**---**I-------- I I I 134455554431 I

I 15428485392461 I I 59077738177357 I TOTALS I 000000007855957371007700000000 I 9999

TOTAL NUMBER OF ENTRIES = 51031

-60.000 -20.000 20.000 60.000 TOTALS I**---**---**---**---**---**---**I---------60.000 I I 0-54.000 I I 0-48.000 I I 0-42.000 I I 0-36.000 I I 0-30.000 I I 0-24.000 I 4H$$$$$$$$K5 I 603-18.000 I 3$$$$$$$$$$$$ I 5010-12.000 I H$$$$$$$$$$$$K I 8414 -6.000 I H$$$$$$$$$$$$H I 9999 0.000 I L$$$$$$$$$$$$H I 9999 6.000 I A$$$$$$$$$$$$E I 8483 12.000 I $$$$$$$$$$$$6 I 5058 18.000 I 4L$$$$$$$$H3 I 590 24.000 I I 0 30.000 I I 0 36.000 I I 0 42.000 I I 0 48.000 I I 0 54.000 I I 0 I**---**---**---**---**---**---**I-------- I I I 134456555431 I I 213971951312 I I 61257420138277 I TOTALS I 000000008999158636733400000000 I 9999


-60.000 -20.000 20.000 60.000 TOTALS I**---**---**---**---**---**---**I---------60.000 I I 0-54.000 I I 0-48.000 I I 0-42.000 I I 0-36.000 I I 0-30.000 I I 0-24.000 I 2AQ$$$$$$OF1 I 397-18.000 I $$$$$$$$$$$$ I 4016-12.000 I 1$$$$$$$$$$$$4 I 8053 -6.000 I 2$$$$$$$$$$$$2 I 9999 0.000 I 3$$$$$$$$$$$$2 I 9999 6.000 I $$$$$$$$$$$$ I 8186 12.000 I $$$$$$$$$$$$2 I 4102 18.000 I 2GS$$$$$$$F2 I 396 24.000 I I 0 30.000 I I 0 36.000 I I 0 42.000 I I 0 48.000 I I 0 54.000 I I 0 I**---**---**---**---**---**---**I-------- I I I 2456666542 I I 631337614046 I I 7435062357861 I TOTALS I 000000006682187334832000000000 I 9999


KABES-1

X [mm]

Y [mm]

KABES-2

KABES-3


1HISTOGRAM NO 29 HORIZONTAL AXIS X IN MM 204.858 M FROM THE TARGET VERTICAL AXIS Y IN MM 204.858 M FROM THE TARGET0 -60.000 -20.000 20.000 60.000+ TOTALS I**---**---**---**---**---**---**I-------- -60.000 TO -54.000 I I 0 -54.000 TO -48.000 I I 0 -48.000 TO -42.000 I I 0 -42.000 TO -36.000 I I 0 -36.000 TO -30.000 I 2321 11 I 10 -30.000 TO -24.000 I 159XT$$$$SJE73 I 334 -24.000 TO -18.000 I 8$$$$$$$$$$$U72 I 1947 -18.000 TO -12.000 I 1E$$$$$$$$$$$$D I 4900 -12.000 TO -6.000 I G$$$$$$$$$$$$J1 I 8143 -6.000 TO 0.000 I 1L$$$$$$$$$$$$I2 I 9999 0.000 TO 6.000 I G$$$$$$$$$$$$82 I 9984 6.000 TO 12.000 I G$$$$$$$$$$$$E1 I 8252 12.000 TO 18.000 I F$$$$$$$$$$$$E1 I 4901 18.000 TO 24.000 I AV$$$$$$$$$$X7 I 1929 24.000 TO 30.000 I 2ERYVWQSPFF5 I 254 30.000 TO 36.000 I 21 1 1 I 5 36.000 TO 42.000 I I 0 42.000 TO 48.000 I I 0 48.000 TO 54.000 I I 0 54.000 TO 60.000 I I 0 I**---**---**---**---**---**---**I-------- I I I 1356776531 I I 15731887723651 I I 16166042762880 I TOTALS I 000000027056033304565390000000 I 9999 0 TOTAL NUMBER OF ENTRIES = 51031 INCLUDING UNDERFLOW AND OVERFLOW AS FOLLOWS 0 UNDERFLOW OVERFLOW ACROSS 0 0 DOWN 0 0

0HISTOGRAM NO 29 HORIZONTAL AXIS X IN MM 204.858 M FROM THE TARGET VERTICAL AXIS Y IN MM 204.858 M FROM THE TARGET

Spot at Wire Chamber 1:

X [mm]

Y [mm]


Beam:Present K12

(NA48/2)New HI K+

> 2006Factor gainwrt 2004

SPS protons per pulse 1 x 1012 3 x 1012 3.0

Duty cycle (s./s.) 4.8 / 16.8 1.0

Beam acceptance H,V (mrad) 0.36 2.4, 2.0

Solid angle (sterad) 0.40 16 40

Av. K+momentum <pK> (GeV/c)

60 75 K+ : 1.50+ : 1.35Total : 1.35

Momentum band pK (GeV/c)

Eff.: (p/p in %)

RMS: (p/p in %)

57 – 63 = 6 5 4

73.9-76.1=2.251.5

0.95

0.3750.3

0.25

Beam size (cm)Area at KABES (cm2)

1.5 7.0

2.5 20

2.8

Divergence: RMS (mrad) 0.05 0.1 2

Possible new high-intensity K+ beam for ‘NA48/3’ (K+→)


Beam:Present K12

(NA48/2)New HI K+

> 2006Factor gainwrt 2004

Decay fid. length (m)

(K+)50

0.11

500.09 0.8

Beam flux/pulse: p (x 107)

K+

+

e+

0.86

0.313.320.95

49

1515035

50 (~30)45 (~27)

Total per pulse (x 107) per Effective spill length (MHz)

/ … / cm2 (KABES) (MHz)

5.5182.5

25080040

~45 (~27)~45 (~27)~16 (~10)

Eff. running time / yr (days)

(pulses)

½ * 1203.1 105

2/3 * 90

3.1 * 105 1.0

K+ decays per year

inside fiducial length

1.0 1011 4 * 1012 40

Possible new high-intensity K+ beam for ‘NA48/3’ - page 2


Detector Layout


NA48/3: Acceptance (Region I)Not Even Preliminary!

5 % acceptance would translate into 20 events/year @BR~10-10

E. Goudzovski


NA48/3: Kaon Spectrometer

Currently used in NA48/2: micromega via TPC read-out (KABES)

NA48/2: @ 2 MHz/strip:Resolution strips 80 mRisolution drift 50 mTime resolution 0.7 nsDead Time/strip 40 nsP/P ~0.5 %

The expected rate per strip in NA48/3 is about 10 times larger:-New micro-mesh (25 micron)-FADC-smaller strip size-New gasMust test all of the above (2004?)


CEDAR / ~ 1/2p (m22 –m1

2)


CEDAR


P(+) (GeV/c)

mm2

region 1

Region 1 -> signal region -> mm2 in the range between 0 and 0.01 (GeV/c2)2

mm2 = MK2 + m

2 – 2 ( EKE – pKp cos) instead of

mm2 = MK2 + m

2 – 2 ( EKE – pKp cos) ~ 0

F. MarchettoKinematical Rejection


mm210 GeV

30 GeV

20 GeV

40 GeV

50 GeV 60 GeV

1. I = 1200 A

2. K smeared with

p = 0.5 GeV/c

= 15 rad

being the angular resolution of the spectrometer ~17 rad

F. Marchetto


Double spectrometer geometryDCH1DCH1 DCH2DCH2 DCH3DCH3 DCH4DCH4 DCH5DCH5 DCH6DCH6KevlarKevlar

Mag1Mag1 Mag2Mag2

K

zz

xx

2m2m 10m10m 10m10m10m10m2.5m2.5m 2.5m2.5m 2.5m2.5m2.5m2.5m

G. Ruggiero


Alternative layout

DCH1DCH1 DCH2DCH2 DCH3DCH3 DCH4DCH4 DCH5DCH5 DCH6DCH6

KevlarKevlarMag1Mag1 Mag2Mag2

K

zz

xx

11m11m 9m9m9m9m2.5m2.5m 2.5m2.5m 2.5m2.5m2.5m2.5m

DCH1:32.5 10 r.l.

Straw tube in vacuum: X and Y view Compass straw tube (real): per view CKM straw tube (immaginary): per view

32.3 10 r.l. 30.9 10 r.l.

G. Ruggiero


Square missing mass resolution

Single spectrometerSingle spectrometer

9 m9 m

7 m7 m

Double spectrometerDouble spectrometer

2 2 4miss ) ( / )M GeV c

( / )P GeV c

50% improvement at “low momenta”

Better use of P measurement redundancy

G. Ruggiero


Energy distribution of the photon closer to beam axis

E (GeV) L. Di Lella

Photon Rejection


Photon Vetoes (KAMI)


Muon Vetoes


Tests in 2004• KABES

– 25 m Micro-mega mesh– 1 Ghz FADC read-out (24 channels recuperated from the

old NA48 proton tagger)– Silicon micro-pixels in beam similar to final beam

• CEDAR– Test in M2 hadron beam (Compass)

• Photon vetoes– Install small angle calorimeter

• Drift chamber rate test (HV vs. resolution)


Far Future: NA48/4 KL→ 0ee


State of the art: KTeV KL→ 0ee

1999 dataBR(KL → 0 ee ) < 2.8 × 10-10 @90%CL

• SES ~ 10-10

• Tantalisingly close to the SM prediction…

• …But progress is slow due to radiative backgrounds from KL→ee

Full Statistics: 1997+1999


NA48/4: KL→ee()

• Detector ×2 – Very ambitious, KTeV/NA48 already state of the art

• KS-KL time dependent interference ×2– Position experiment between 9 and 16 KS lifetimes (hep-ph/0107046)

• KS-KL time independent interference ×3 – Assume constructive interference (theoretically preferred)

• Data Taking ×5 – Run in “factory mode”. After all E799-II run only for a few

months to collect ~7 × 1011 KL decays• Beam intensity ×4

– Need ~1012 protons/sec, slowly extracted, high energy, DC • Tot ~ ×240 → sens on BR ~ ×15 (on Im t ~×4-15)

– close the gap between current upper limit and SM


Far future: NA48/5KL→0


KL → 0 (reminder)

•Theoretical error ~2%:•Purely CP-Violating (Littenberg, 1989) •Totally dominated from t-quark•Computed to NLO in QCD (e.g. Buchalla Buras, 1999)•No long distance contribution SM~3 × 10-11

• Experimentally: 2/3 invisible final state !!• Best limit from KTeV using →ee decay

BR(K0 → 0) < 5.9 × 10-7 90% CL

Still far from the model independent limit: BR(K0 → 0) < 4.4 × BR(K+ → +) ~7 × 10-9 Grossman & Nir, PL B407 (1997)


E391a@PS-KEK

•First dedicated experiment to search for KL→ •SES~ 3 10-10

•Based on pencil kaon beam and photon vetoesScheduled for ~100 days KEK PS beam in 2004 This is a Stage I project for further study at J-PARC


KOPIO@BNL

• Aim to collect 60 KL→ events with S/B~2 (Im t to 15%)• Measure as much as possible

– Energy, Position and Angle for each photon

• Work in the Kaon Center of Mass – Micro-bunched AGS beam– Use TOF to measure KL momentum

• Start construction in 2005?


NA48/5: KL→0

NA48/5

E391A

J-PARC

CERN may become competitive if the E391A technique works

From KAMI proposal


A forward look….

sin 2

K+→ + to 10%

K

Vub

K0-K0barmixing

B tree decays

KL→ 0 ee


[email protected]

rare kaon decays: opportunities for cern

Documents

physics letters b

p0 gg cp

p0 n n

ks p0 p0d decays

directcp violation

ks p0 eee e

data http

ktev cp violation