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January 18, 2005 A. Ceccucci, CERN 1

Rare Kaon Decays: Opportunities at CERN

Augusto Ceccucci/CERN Padova, January 18, 2005

http://www.cern.ch/CERN50/


Why study Rare Kaon DecaysIn the 21st century?

• Search for explicit violation of Standard Model – Lepton Flavour Violation

• Study the strong interactions at low energy – Chiral Perturbation Theory, Form Factors

• Test fundamental symmetries– CP,CPT

• Probe the flavour sector of the Standard Model– FCNC

Unique probe of the s→d quark transitions

s d Vtd

Vts*



Quark mixing and CP-Violation

'

'

'

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

Quark mixing is described by the Cabibbo-Kobayashi-Maskawa (CKM) matrix

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

Paradigm shift: having established the abovelook for inconsistencies in SM using observables with small theoretical errors

Im t= Im Vts*Vtd ≠ 0



Kaon Rare Decays and the SM

(holy grail)

Kaons provide quantitative tests of SM independentfrom B mesons…

…and a large windowof opportunity exists!

|Vtd|

G. Isidori

Im t = A2 5 Re t = A2 5



Further Enticement: New Physics?

• These rare kaon decays are second order weak interactions mediated by Z penguins that could be sensitive to NP

• A deviation from the predicted rates of SM would be a clear indication of new physics

• Complementary programme to the high energy frontier:– When/if new physics will appear at the LHC, the rare decays may help to

understand the nature of it



Kaons@CERN:NA48

1997

1998

1999

2000

2001

2002

2003

NA48: ’/

’/

’/

’/ lower inst. intensity

NA48/1 KS

NA48/1: KS

KL

no spectrometer

NA48/2: K

1996

2004NA48/2: K

Re ’/= 14.7 ± 2.2 10-4

First observation ofK0

S →0 ee and K0S →0

Ave: Re ’/= 16.7 ± 2.3 10-4

+ KL Rare Decays

Search for Direct CP-Violation in charged kaon decays

Direct CP-Violation established!



NA48 Vacuum Tank



NA48 Detector

1996Total: 5.3M KL00

Magnetic spectrometerLiquid krypton EM calorimeter

90 m longVacuum tank

400 GeV protonsFrom CERN SPS



Recent but well established Rare Kaon Decay Tradition @CERN:

NA48/1



0++, 2++

Direct CPV

Indirect CPV

CPC

NA48/1: K0s→0ee and K0

s→0

Principal aim of NA48/1: Measure the IndirectCP-Violating Contributionto K0

L→0ee and K0L→0



NA48/1: Backgrounds

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

KS →0 Source

KL →

KL,S → Accidentals

Total

0. +0.02 -0.00

0.04+0.04-0.03

0.18+0.18-0.11

0.22+0.18-0.11

• 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



K0S →0 ee and K0

S →0

KS →0 eeKS →0

BR(KS→0ee) 10-9 = 5.8 +2.8

-2.3(stat) ± 0.8(syst)

|as|=1.06+0.26-0.21 (stat) ± 0.07 (syst)

PLB 576 (2003)

7 events, expected back. 0.15

BR(KS→0) 10-9 = 2.9 +1.4

-1.2(stat) ± 0.2(syst)

|as|=1.55+0.38-0.32 (stat) ± 0.05 (syst)

PLB 599 (2004)

6 events, expected back. 0.22

NA48/1 NA48/1

M. Patel PhD thesisM. Slater PhD thesis



Isidori, Unterdorfer,Smith:

Fleischer et al*:

Ratios of Bd → modes could be explained by enhanced electroweak penguins which, in turn, would enhance the KL BR’s:

•A. J. Buras, R. Fleischer, S. Recksiegel,

F. Schwab, hep-ph/0402112, NP B697 (2004)

1.6 111.6

0.7 110.7

9.0 10

4.3 10

NP

e e

NP

B

B

0 12L(K ) 10Br

0 12L( ) 10Br e e

K0L→0ee (): Sensitivity to NP



NA48/1: Semileptonic decays

+

semileptonic decay is the only source of in the neutral beam because→ is kinematically forbidden


Preliminary Result

• Based on 6238 -decays:BR(→e)=(2.51 ± 0.03sta ±0.11sys)10-4

Compare KTeV: (2.71 ± 0.38) 10-4

Systematics: Trigger Efficiency 2.6 % Acceptance 3.0 % ff (g1 and f2) 1.0 % Polarisation 1.0 % Lifetime 0.5 % Tot systematics 4.2 % Stat Uncertainty 1.2 %


NA48/2 : K+/K-

Simultaneous K+ and K- beams


January 18, 2005 A. Ceccucci, CERN

17

Direct CP violation

in K± ± ± , K± ± 0 0 M(u) 1 + gu, u= f( )

(Ag ) < 210 – 4

NA48/2: AimNA48/2: Aim

g + - g -

Ag = ———— g+ + g -

In addition:• Study of scattering using Ke4 (and ± events

• Study of medium-rare charged kaon decays• Study of semi-leptonic decays

*

oddE


cos(e)

K±+-e±ν (Ke4) selection (preliminary)

Cabibbo-Maksymowicz

variables [backgr. in red]

Background

Ke4 hypothesisK- mass

0 0.1 0.2m(e), GeV/c2

0.3 0.4 m(), GeV/c2

2003 data: > 500k (background ~0.6%)



19

First Observation of the + - - rescatteringin K 0 0 decays

M2(00), (GeV/c2)2 M2(00), (GeV/c2)2

4m2()= 0.0779(GeV/c2)2

29M decaysNA48/2 Preview!


20

M2(00), (MeV/c2)2

Determination of a0-a2

from K 0 0 decays

a0-a2 = 0.265

= 0.N. Cabibbo hep-ph 0405001, PRL93 (2004)


Z=(M(ee)/MK)2

Form-factorK± ± e+e-

> 2600ev.

M(± e+e-), GeV/c2

• low background (1-2%)

• expected data sample in 2003-2004 comparable to the World best sample

Kee & K±±+- selection(preliminary)

K± ± +-

> 1000ev. (PDG:

~ 800)

NA48/2(2003)



“CERN Director General Outlines Seven-point Strategy for European Laboratory”

18.6.2004 Official CERN Press Release Geneva 18 June 2004. “At the 128th session of CERN Council, held today under the chairmanship of Professor Enzo Iarocci, CERN Director General, Robert Aymar, outlined a seven-point scientific strategy for the Organization. Top of the list was completion of the Large Hadron Collider (LHC) project with start-up on schedule in 2007. This was followed by consolidation of existing infrastructure at CERN to guarantee reliable operation of the LHC, with the third priority being an examination of a possible future experimental programme apart from the LHC.”………

……… The possible Future Programme was reviewed by the SPSC in

Villars (September 22-27, 2004)



Message from the CERN Director General to the staff (Jan 05)

• The top priority is to maintain the goal of starting up the Large Hadron Collider (LHC) in 2007

• “…Meanwhile, the natural break we have in the fixed-target programme in 2005 is already allowing the community to develop a well-focused programme for the future”



The Next Step: NA48/3 K → at the CERN-SPS

SPSC-2004-029SPSC-I229

Cambridge, CERN, Dubna, Ferrara,

Firenze, Mainz, UC Merced, Perugia,

Pisa, Saclay, Sofia, Torino, + ??

Work inspired by:•High Quality NA48/2 charged Kaon beams and Beam Spectrometers•Outstanding Progress by BNL E787/E949 •In flight technique with separated beam proposed by FNAL CKM

• not ratified by HEPAP P5



Prediction (CKM Workshop): BR(K+ → ) = 8.0 ± 1.1 × 10-11

Expect improvements NNLO calculation + reduction parametric uncertainty 4 % error (Buras)

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



Main K+ decay modes competing with K+→+

Decay

e

BR

63 %

21 %

6 %

2 %

3 % (called K+3)

5 % (called K+e3)

Suppression:

PID, kinematics

veto, kinematics

CHV, kinematics veto, kinematics veto, PID veto, E/P

BR(K+→+ )~10-10 !!



K+→+ : State of the art

BR(K+ → + ) = 1.47+1.30-0.89 × 10-10

•Twice the SM, but only based on 3 events…

hep-ex/0403036 PRL93 (2004)

Stopped K~0.1 % acceptance

AGS



NA48/3 (I229): Decay In Flight

• Collect 80 K+→+ events in about two years of data taking for:

– 4 1012 Kaon decays/SPS year– BR( K+→+ ~10-10

– Acceptance ~ 10%

– Absolute advantage:

High energy kaon beam: >35 GeV of EM energy deposited in the vetoes Vey Difficult to miss 0 !!

– Disadvantage:

Unseparated Kaon beam

Region II

Region I

P(K)=75 GeV/c



NA48/3 Detector Layout

800 MHz(/K/p)

Only the upstream detectors see the 800 MHz beam

10 MHz Kaon decays

K++

undetected



Acceptance

75 / 40 /

Assume Acceptance (Region I+II) ~ %KP GeV c P GeV c

( / )KP GeV c ( / )KP GeV c

Acceptance

Acceptance

Region I Region II

2 2 20 0.01 ( / )missm GeV c 2 2 20.026 0.068 ( / )missm GeV c

14 ( / ) 40P GeV c 14 ( / )P GeV c

14 ( / ) 30P GeV c

75 GeV/c



Beam:Present

K12(NA48/2)

New HI K+

> 2006

Factor wrt 2004

SPS protons per pulse on T10

1 x 1012 3 x 1012 3.0

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

Solid angle (sterad) 0.40 16 40

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

60 75 Total : 1.35

Mom. band RMS: (p/p in %)

4 1 ~0.25

Area at Gigatracker (cm2) 7.0 20 2.8

Total beam per pulse (x 107)per Effective spill length MHz MHz/cm2 (gigatracker)

5.5182.5

25080040

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

Eff. running time / yr (pulses)

3* x 105 3.1 * 105 1.0

K+ decays per year 1.0x1011 4.0x1012 40

New high-intensity K+ beam for NA48/3 AlreadyAvailable



GIGATRACKER

• Specifications: – Momentum resolution to ~ 0.5 % – Angular resolution ~ 10 rad– Time resolution ~ 100 ps– Minimal material budget– Perform all of the above in

• 800 MHz hadron beam, 40 MHz / cm^2• Hybrid Detector:

– SPIBES (Fast Si micro-pixels)• Momentum measurement • Facilitate pattern recognition in subsequent FTPC• Time coincidence with CHOD

– FTPC (NA48/2 KABES technology with FADC r/o)• Track direction



NA48 WC



Main Tracker w/o beam pipe?

?

We are considering a full straw tracker operated in vacuum



TRT ATLAS

Straw diameter – 4 mm, length – 40 and 150 cm

17 end-cap wheels are built in JINR (105 kpc of straws)

COMPASS TRACKER

Straw diameter – 6 and 10 mm, length up to 3.8 m

15 chambers were built in JINRStraw tracker operated in vacuum:

COSY-TOF, Juelich,IKP

Straw tracker, 3100 straws, evacuated –

10-3 mbar (P.Wintz)

MECO, BNL (W.Molzon)

Etc.



Straw Tacker w/o beampipe

Four views (X,Y,U,V)One Station (Exploded view)



New NA48/3 simulation

Uncorrelated non gaussian tails

Gaussian MSC (old)

Non-Gaussian MSC

P (Spectrometer 1) GeV/c P (Spectrometer 1) GeV/c

P (Spectrometer 2) GeV/c

P (Spectrometer 2)GeV/c

M(miss)2 (GeV/c2)2

New MSC

REGION I

REGION II



ANTI

• Set of ring-shaped photon vetoes surrounding the decay tank• Specification: inefficiency to detect photons above 100 MeV < 10-4

• The NA48 ANTI’s (AKL) need to be replaced• Extensive R&D Performed by American and Japanese groups • Claims that inefficiency as low as 10-5 can be achieved• Baseline solution: Lead/ Plastic scintillator sandwich (1-2 mm

lead / 5 mm plastic scintillator)• Cost driver of NA48/3



LKR

• The NA48 Liquid Krypton Calorimeter • Must achieve inefficiency < 10-5 to

detect photons above 1 GeV • Advantages:

– It exists – Homogeneous (not sampling)

ionization calorimeter– Very good granularity (~2 2 cm2)– Fast read-out (Initial current,

FWHM~70 ns)– Very good energy (~1%, time ~

300ps and position (~1 mm) resolution

• Disadvantages– 0.5 % X0 of passive material in

front of active LKR– The cryogenic control system

needs to be updated



MAMUD

Pole gap is 11 cm V x 30 cm H

Coils cross section 15cm x 25cm

•To provide pion/muon separation and beam sweeping.

–Iron is subdivided in 150 2 cm thick plates (260 260 cm2 )

•Four coils magnetise the iron plates to provide a 1.3 T dipole field in the beam region•Active detector:

–Strips of extruded polystyrene scintillator (1 x 4 x130 cm3) –Light is collected by WLS fibres 1.2 mm diameter



Where are we?

• August 2004 test run– WC: raise intensity to about 30 times NA48/2– GIGATRACKER

• Tested a state-of the-art ALICE SPD assembly in our beam• Use a thinner 25 micron MICROMEGAS amplification gap• Read out KABES with 480 MHz FADC (former NA48 tagger FADC)• Read KABES at ~14 times the NA48/2 rate

– LKR: Complement the photon coverage with Small Angle Calorimeter SAC (CMS ECAL prototype)

– CHOD test of prototypes• September 26-27, 2004

– Our presentations at Villars were well received• October 7, 2004

– John Dainton, SPSC Chairman reported the conclusions from Villars at CERN in a seminar at CERN

– Verbally: ”The SPSC looks forward to receive a proposal”• October 18, 2004

– Letter of Intent officially submitted. SPSC-2004-029 SPSC-I229– We have establishing working groups aiming to submit a proposal by mid 2005:


John DaintonVillars 2004

October 7th 2004CERN seminar

SPSCSPSC

● new rare decay frontier in K physics at CERN

● new experiments planned for Kπνν important

● support R&D now for K+π +νν results ≤ 2010- no competition … yet!

● longer term opportunity for K0π 0νν - direct competition (decay at rest)

● synergy with energy frontier @ LHC … @ CERN - B-physics - LF violation

● rare charm decay: feasibility of operating experiment (NA60) ?


Time Schedule

• 2005– Launch GIGATRACKER R&D– Vacuum tests– Evaluate straw tracker– Start realistic cost estimation– Complete analysis of beam-test data– Submit proposal to SPSC

• 2006-2008– Costruction, Installation and beam-tests

• 2009-2010– Data Taking



Conclusions

• We have found a fortunate combination where a compelling physics case can be addressed with an existing accelerator, employing the infrastructure (i.e. civil engineering, hardware, some sub-systems) of an existing experiment

• We stress that this initiative in not a mere continuation of NA48

• We are seeking new Collaborators!



Kaons: Longer term (i.e. More Protons Needed!)

• K0L→ 0eeand K0

L→ 0(NA48/4)

• K0L → 0 (NA48/5)



K0L→ee() : Perspectives

• 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 (≤ 1 TeV), DC • Tot ~ ×240 → sens on BR ~ ×15 (on Im t ~×4-15)

– explore the window of opportunity between current upper limit and SM

Ideal Kaon Application for High Intensity/High Energy Machine


K0L → 0

•Purely theoretical error ~2%: SM 3 10-11

•Purely CP-Violating (Littenberg, 1989) •Totally dominated from t-quark•Computed to NLO in QCD ( 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+ → +) ~ 1.4 × 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?



KL→0@CERN?

NA48/5?

E391A

J-PARC

CERN may become competitive if the E391A technique works

From KAMI proposal

SPS



Conclusions

– A competitive programme can start pnow for charged kaons at the current SPS

– For a very competitive neutral kaon decay experiment, ~ 1013 slowly extracted, high energy protons per second would be needed



SPARES



CompetitionNA48/3 P940

Accelerator CERN-SPS FNAL-MI

Energy (GeV) 400 120

Duty cycle (s /s ) 4.8 / 16.8 = 0.29 1.0 / 3.0 = 0.33

1 HEP year (s) 107 107

Eff. Spill. Length (s / s) 3.0 / 4.8 = 0.63 1.0 / 1.0 (?)

Total Rate (GHz) 0.8 0.23

Fraction of Kaons (%) 6 4

Flux of Kaons (MHz) 50 10

Decay fraction (%) 9 (50 m / 100 m) 17 (60 m / 67 m)

Acceptance (%) 10 5

Events/y (BR~10-10) 82 31


KL→0@CERN?

NA48/5?

E391A

J-PARC

CERN may become competitive if the E391A technique works

From KAMI proposal

SPS


Intermezzo: Vus puzzle

• The Unitarity of the CKM matrix requires for the first row:

• PDG04:

• Semileptonic kaon decays are the best method to determine |Vus|: – protection from first order SU(3) symmetry

breaking

2 2 2| | | | | | 1ud us ub

V V V

2 2 2 3| | | | | | 1 3.3 1.5 10ud us ub

V V V

2.2

3

| | 0.9738 0.0005 | | 0.2200 0.0026| | (3.67 0.47) 10

ud us

ub

V VV


NA48 KL→e (Ke3) analysis

• Data from minimum bias run 1999 (80 M events) • The basic measured quantity is the ratio R of

decay rates of Ke3 decays relative to all decays with two charged tracks

2 2

0 0 0 0 0

0

/

/ (2 ) 1 (3 ) ( ) (2 ) (2 ) (4 ) = 1.0048 (3 )

( 3) (2 )

e e

T T

D

N aR

N a

B T B B B B B TB

B Ke R B T

External input: BR(KL→0 00)



NA48 Experimental Result

R= 0.4978 ± 0.0035

• To compute BR(K3e) we need : BR(KL→0 00)• PDG04: 0.2105 ± 0.0028• KTeV 04: 0.1945 ± 0.0018 Take average*: 0.1992 ± 0.0070

BR(2T) = 0.8056 ± 0.0070

BR(Ke3) = R * BR(2T) = 0.4010 ± 0.028 ± 0.0035

*NA48/1 Internal cross check (Y2K data, see later)

in good agreement with KTeV

5 !!



Extraction of Vus

• Taking the latest calculation:– (Cirigliano et al., 2004) f+(0)= 0.981 ± 0.010

|Vus| = 0.2187 ± 0.0028 still 2.4 from unitarity (0.2274)• For comparison, if one takes the old Leutwyler and Ross

value: – f+(0)= 0.961 ± 0.008

|Vus| = 0.2232 ± 0.0029 one finds good agreement with unitarity



59

ICHEP-2004

PDG

SMV

us x f

+(0

)

8 hours of 2003minimum-bias run9104

K 0e

normalizationchannel: 7105 K+ 0

Br(Ke3)= (5.14 ± 0.02stat ± 0.06syst)%

BR (K 0e ) preliminary


FTPC (KABES+FADC)

• NA48/2– KABES has achieved very good performance – Position resolution ~ 70 micron– Time resolution ~ 0.6 ns– Rate per micro-strip ~ 2 MHz

• NA48/3 – Intensity ~ 10 higher per unit area– 600 ns drift – The long drift (600 ns) makes a standalone pattern

recognition very difficult or just impossible ( That’s why we plan to have SPIBES in front)

– To reduce double pulse resolution and improve the time resolution one has to reduce the pulse duration and possibly read-out every micro-strip with 1 GHz FADC

January 18, 2005 A. Ceccucci, CERNMara Martini 61

GIGATRACKERS

PIB

ES

1

SP

IBE

S2

FT

PC

6.25 12.45 m

♠ momentum: use SP1 and SP2 to measure y = 40 mm displacement. Assuming σp~50µm from pixel and 350µm thick Si (0.37% X0)

σ = (σp√2 ‡ σMS ) ⁄ 40 mm = 0.25%

♠ direction: use SP2 and FTPC. Assuming σp~100µm from pixel and similar from FTPC and no MS from FTPC (from SP2 no influence)

∆Өх= σp√2 ⁄ 12.4m = 11µrad

Tails in the beam? (Turtle simulation)

♠ time resolution: essential to obtain a low background due to accidental hits and to allow the pattern recognition (see result from test beam) . For a pixel C≈ 100 fF a risetime ~ 2 ns should be achievable for 130 nm technology and a good S/N.

January 18, 2005 A. Ceccucci, CERNMara Martini 62

Proposal for SPIBES

5 cm

300 x 100 µm pixel cell 80000 pixels in total to cover the beam

• An effort must be done to minimize the overall thickness to ≤ 350 µm of Si without loosing in yield .

• Should avoid a substrate

• The cooling should be studied

• The dimension of the pixel cell and of the chip must be optimized to fit the 2n rule and to match the design requirements (PA, Discri, multiplexed TDC, power consumption, r/o bus)

Beam square shape 5x5 cm2


Test of ALICE pixel in NA48/2 beam 1 ALICE assembly

1 DAQ adapter card 30 m DAQ cables

30 m JTAG control cables LV and HV power supplies

VME crate with r.o. module (Pilot) and JTAG

controller JTAG multiplexer

MXI interface to PC ALICE PTS software

(LabView)

PC remotely controlled from NA48 control room


Single Chip Alice Assembly tested

Assembly 7:•150µm thick ALICE chip•200µm thick sensor• 1.1 % X0 all together

Mounted on a thin test-PCB

Vfd=15VVop=50V

8192 pixelsProduced 2003, tested inALICE p-TB 2003

Sensor

Chip


MULTIPLICITY (200 nsec gate)

I0I0/4

4xI0

14xI0

<mult> = 1.1 <mult> = 1.3

<mult> = 3.1 <mult> = 7.8


MULTIPLICITY (200 nsec gate)MULTIPLICITY (200 nsec gate)

for r/o window of 10 ns:

1GHz x 10 ns x 1.1 ~ 10 hits/ trig

for σ = 100ps we expect in a ±2.5σ:0.5 accident hits/trig


driftE

driftE

Tdrift1

Tdrift2

Operated @ Edrift=0.83kV/cm

Tdrift1 + Tdrift2 = 750ns

48 strips with 0.8 mm pitch

Very low discharge probability

Micromegas

Gap 50 μm

Micromegas

Gap 50 μm

KABES principle: TPC + micromegas


Recent lab test with 25 m gap

50 m gap 25 m gap

improvement of occupancy observed with 25m amplification gap

Width ~30 ns Width ~18

ns

KABES 25 micron amplification gap


480 MHz FADC


Beam Test 2004: WC

• With the exception of one sector in the Y view of DCH3 all other channels could be operated at nominal HV at the highest beam intensity

• Quite encouraging: plane efficiency decreases only by 1-2% • Ability to operate the WC at intensity close to NA48/3 is very

important


NA48 Liquid Krypton Calorimeter

9 m

3 o

f Lk

r (132

12

ce

l ls)

1.2

5 m

dep

h (27

X0 )

(E)/E = 3.2%/E 9 % /E 0.42%(m)~1 MeV/c2 ;(t) ~ 300 ps

FAST: 70 ns FWHM (it can be reduced)EXCELLENT GRABULARITY: 2 2 cm2


Small angle photon vetoPbWO4 crystals (CMS) Dimension of crystals 2x2x23 cm3 7 x 7 cm matrix ~ 25 X0

Readout with light guides and PMTInstalled for last week of data taking


General definitions

2 2 2( / )missm GeV c

Region I

Region II

( / )P GeV c

K

0

0 Peak Region


Detectors• CEDAR

– To tag positive kaon identification• GIGATRACKER

– To Track secondary beam before it enters the decay region

• ANTI

– Photon vetoes surrounding the decay tank • WC

– Wire chambers to track the kaon decay products• CHOD

– Fast hodoscope to make a tight K-pi time coincidence

• LKR

– Forward photon veto and e.m. calorimeter• MAMUD

– Hadron calorimeter, muon veto and sweeping magnet• SAC and CHV

– Small angle photon and charged particle vetoes


Tentative Indication of costElement Cost (MCHF) Comments

BEAM LINE 0.5 Modified K12 line

CEDAR 0.2 Photon Detectors

GIGATRACKER 1.4 Assuming 0.13 m

VACUUM 0.7 Upgrade of vacuum system

ANTI 4.2 Based on CKM estimate + elec.

WC 3.0 Two more chambers + R/O

MNP33/2 2.5 Including prolongation of He tank

CHOD 1.0 2000 PMs, 500 CHF/channel

LKR 2.0 New supervion system and R/O

A state-of the art calorimeter is 15 MCHF

MAMUD 2.0 Cost of iron: ~500 KCHF

SAC & CHV 0.5

TRIGGER & DAQ

TOTAL 19.0


Compatibility/Competition

• NA48/3 is fully compatible with COMPASS running– We need only 3 1012 per cycle (already available now on

T4!)

• There are two approved competitors for beam time – LHC filling and CNGS

• The extent of the project implies that there should not be in addition (at the stage of data taking)– A fixed target heavy ion programme– Any other experiment in ECN3 competing for proton

beam time

• We understand that the SPS can deliver protons for fixed target physics even when LHC is being operated with ions


Simulation: GeometryStandardStandard

Upgrade2Upgrade2

Testrun 2004 (beatch file)NA48/3 (beatch file)

Upgrade1Upgrade1



Kaons @ CERNPast:NA48: Direct CP Violation Established ! NA48/1: First Observations of K0

S → 0 ee () •Mixing CP-Violation in K0

L → 0 ee () measured !Present: NA48/2: K+ / K- Taken data in 2003/2004

•Search for Direct CP-Violation•Inspiration to study K+ → + in flight

Future Opportunities:•Short to medium term (≤ 2010)NA48/3 K+ → + TODAY MAIN FOCUS•Longer term

NA48/4 K0L → 0 ee ()

NA48/5 K0L → 0



Direct CP

Indirect CP

Short Distance Contribution

directly from

Interference Term ?Constructive

Destructive

Interference between K0L→0ee and

K0s→0ee

Two independent theoretical analyses find that theinterference term is constructive:•Buchalla,Isidori,D’Ambrosio: hep-ph/0308008, NP B 672 (2003)•Friot, Greynat, de Rafael: hep-ph/0404136, PL B 595 (2004)



NA48/1: K0s→0ee

• Experimental difficulties:• Backgrounds from K0

s→00→0ee (with one lost photon)

– Apply cut m(ee)>0.165 GeV/c2

• Backgrounds from double Dalitz and photon conversions

• Radiative backgrounds from K0L→ee

– Measured directly from large (2001) KL sample

• Accidental backgrounds from two event overlap, e.g.

K0s→00 (with 2 lost photons) + K0

L→e(with pion mistaken as electron)– Measure in time-side-bands exploiting excellent time

resolution (signal region < 3 ns) , Side time band ~50 ns



NA48/3: Beam Layout

Beam-line 102 m long

about 17%K+ lost

Dipoles

Dipoles



Villars 2004

Report on the SPSC Villars MeetingSeptember 22-28 2004

John DaintonUniversity of Liverpool, GB

(on behalf of the SPSC)


NA48: Re ’/=14.7 ± 2.2 10-4

Top “down-loaded” 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



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 •Study of backgrounds from KL→ →



0 12L(K ) 10Br

0 12L( ) 10Br e e

Constructive

now favored by two independent analyses*

(Isidori, Unterdorfer, Smith,

EPJC36 (2004))

1.1 110.9

0.3 110.3

3.7 10

1.5 10

e eB

B

Destructive0.7 110.6

0.2 110.2

1.7 10

1.0 10

e eB

B

*G. Buchalla, G. D’Ambrosio, G. Isidori, Nucl.Phys.B672,387 (2003)

*S. Friot, D. Greynat, E. de Rafael, hep-ph/0404136, PL B 595

*

K0L→0ee () in SM

Thank to the NA48/1, the KL BR can now be predicted* Interference between short- and long-distance physics*

Exp (KTeV) (90%CL):BR(K0

L→0ee)<2.8 10-10

BR(K0L→0)<3.8 10-10



How to measure +0 Rejection

M2(miss) (GeV/c2)2 M2(miss) (GeV/c2)2

DATAMC

DATAMC

745862 MC212569 DATA

1486 MC678 DATA

0 peak BEFORE APPLICATION OF EXTRA CLUSTERS IN LKR

AFTER APPLICATION OF EXTRA CLUSTERS IN LKR



Kinematical rejection

Events accepted

( / )P GeV c

2 2 2( / )missm GeV c0

Region I

Region I

2 2 2 2( cos )miss K K K Km EE pm m p Measured quantities

Region II

Download - Rare Kaon Decays: Opportunities at CERN

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