1. Kaon Physics at Hadron Machines
Augusto Ceccucci/CERN
KAON’07, Frascati, May 24, 2007
Panel Discussion

2. Kaon Physics at Hadron Machines has been tremendously successful
CP-Violation
Direct CP-Violation
Stringent test of LFV
Ultra-Rare Decays
Strong interactions (pp scattering, cPT )
CKM …

3. K  p nn decays
Example
The uncertainty of the SM prediction is mostly due to uncertainty of the CKM parameters and not to hadronic matrix elements:
BR(K+p+nn)  (1.6×10-5)|Vcb|4[sh2+(rc-r)2]  (8.0 ± 1.1)×10-11
BR(KLp0nn)  (7.6×10-5)|Vcb|4h2  (3.0 ± 0.6)×10-11

4. NP Reach of the K  p nn decays
F. Mescia
CKM 2006

5. These K  p nn measurements must be done…
These K  p nn measurements must be done…. …and require proton machines to make enough kaons

6. Proton Machines are Very Versatile
CERN:PS,
SPS,(PS2?),
LHC
IHEP:
U-70
J-PARC:
30 (50) GeV
FNAL: MI,
Tevatron

7. NA48

8. Proposal to Measure the Rare Decay K+p+ n n at the CERN SPS
CERN-SPSC
SPSC-P-326
Proposal to Measure the Rare Decay K+p+ n n at the CERN SPS
CERN, Dubna, Ferrara,
Florence, Frascati, Mainz,
Merced, Moscow, Naples,
Perugia, Protvino, Pisa,
Rome I & II, Saclay, San Luis Potosi,
Sofia, TRIUMF, Turin
Approved R&D Programme
Approved 2007 run to study KE2 & to test prototype detectors
Seek to start data taking in 2011
Experiment description:
see G. Ruggiero’s talk tomorrow morning
Unseparated 800 MHz beam (kaon fraction ~5-6%)

9. K+p+p+p- and other 3-tracks bckg.
P-326: K+p+ n n
Events/year
Total
Region I
Region II
Signal (SM) 65 16 49
K+p+p0
2.7±0.2
1.7±0.2
1.0±0.1
Km2
1.2±0.3
1.1±0.3
<0.1
Ke4
2±2
negligible
K+p+p+p- and other 3-tracks bckg.
1±1
Kp2g
1.3±0.4
Km2g
0.4±0.1
0.2±0.1
Ke3, Km3 ,others -
Total bkg
9±3
3.0±0.2
6±3
SPS used as LHC injector (so it will run in the future)
No flagrant time overlap with CNGS
P-326 fully compatible with the rest of CERN fixed target
Conservative beam request based on decennial NA48 experience at SPS

10. P-326 Status and Prospects
2007 Activities:
Continue R&D
Long run at SPS to measure
RK=G(K+  e+ n) /G(K+m+n)
to ~0.3%
Converge towards the technology choices
Seek approval
Aim to data taking in 2011

11. P-326
R&D

12. Gigatracker: R&D program
300 mm  300 mm Si pixel with ~200 ps time resolution
Readout chip: 1st MPW submission in 0.13mm
Submitted in February 07
Analogue FE blocks for the "CFD" option (Torino)
FE amplifier discriminator NINO, LVDS driver (CERN)
Wafers delivery ≈ end May 07
ASICs characterization (t resolution, jitter, time walk)
Tests card in progress (results by September)
Irradiated test diode
Si diode irradiation tests
Prototype wafers (200µm thick) produced by itc-IRST using ALICE pixel layout
3 mm × 3 mm and 7 mm × 7 mm test-diodes
Test diodes irradiated with n and p (Ljubljana, CERN)
Fluences: 1E12 to 2E14 1MeV n cm-2 (range P326)
Pre and post irradiation measurements (annealing) to study diode characteristics
itc-IRST wafer, 200µm
Si diode characterization with pulsed IR laser system

13. LKr calorimeter: R&D program
Measurement of the inefficiency
K+ data taken in a dedicated NA48 test run in 2004 using K+p+p0
h < 10-5 C.L., Eg>10 GeV)
Tagged g using an SPS electron beam (2006)
Inefficiency measured for Eg > 2.5 GeV
> 10 GeV, h < 10-5 confirmed
< 10 GeV analysis in progress
Energy deposition in LKr
electron x
Energy GeV z g
X LKr cm

14. Spectrometer: R&D program
Chosen technology: tube of mylar (25 mm, D=1 cm, L=2.1 m)
100 straws produced in Dubna
Tests on gas leakage
Tests on tube expansion in vacuum
Prototype assembled & cosmic ray tests
October 2007: Prototype integration in NA48 set-up and test on beam

15. RICH: R&D program Design, construction and test of a RICH prototype
Full length prototype (17 m, 0.6 m diameter, stainless steel tube at CERN)
Mirror built, delivered and under test in Firenze
Endcap with 96 Hamatsu PMs readout through Winston’s cones
PMs tested at SPS (2006) and Firenze (with laser)
Measured FWHM per single g per phototube: ps (150 ps electronics and 110 ps laser included)
FWHM ps
t ns
November 2007: prototype integration in the K12 beam set up and test
Simulation p K
p+m

16. Large angle photon vetoes: R&D program
KLOE-type lead/scintillating fiber: prototype constructed in Frascati
1 mm diameter scintillating fibers, mm thick lead foils.
Readout granularity: 18 cells
Very well known and tested technology
Under test at the Frascati BTF
Fibers+lead wires: 9 X0
All fiber: 8 X0
16.8 cm
8.2 cm
Lead scintillators tiles
Aijimura et al. NIM
Studies of the efficiency of detectors built with this technology available
Fermilab prototype under test at BTF
Outgassing tests performed at CERN on detectors built with same technology: they can be placed in the vacuum of the decay region (10-6 mbar)

17. RICH
STRAW
KE2

18. CERN Proton Complex *SPS: more than a LHC injector* SPS LHC
The High Energy
Frontier
P-326 The rarity frontier
SPS
CNGS

19. SPARES

20. FT versus CNGS performance [CERN-HIP Working Group]
CNGS request
pot/year
Double batch + Linac4
Without changes
P-326
Request J J
Double batch

21. K→p nn : SM Theoretical Prediction
NLO Calculation:
Buchalla & Buras: 1993, 1999
Misiak, Urban: 1999
charm contribution
NNLO
Buras, Gorbahn,
Haisch, Nierste
hep-ph/
top
contributions
The uncertainty of the SM prediction is mostly due to uncertainty of the CKM parameters and not to hadronic matrix elements:
BR(K+p+nn)  (1.6×10-5)|Vcb|4[sh2+(rc-r)2]  (8.0 ± 1.1)×10-11
BR(KLp0nn)  (7.6×10-5)|Vcb|4h2  (3.0 ± 0.6)×10-11

22. LKr inefficiency measured with data
p+ track and lower energy g are use to
predict the position of the other g
Cluster not
reconstructed
Eg = 22 GeV
Pion
P=42 GeV/c
Photon
E=11 GeV
Expected
position
K+  p+ p0 selected kinematically
Collected tagged g to measure
for Eg < 10 GeV using an e- beam and the
NA48 DCH’s as active target (Oct ’06)

23. P-326 Parameters K+ decays per year 1.0x1011 4.8x1012  48 Beam:
Present
(NA48/2)
P-326
Factor
wrt 2004
SPS protons per pulse on target
1 x 1012
3 x 1012
3.0
Duty cycle (s./s.)
4.8 / 16.8
1.0
Solid angle (msterad)
 0.40
 16 40
Av. K+momentum <pK> (GeV/c) 60 75
K+ ~ 1.5
Mom. band RMS: (Dp/p in %)
 4
 1
~0.25
Total beam per pulse (x 107)
per Effective spill length MHz
MHz/cm2 (gigatracker)
5.5 18
2.5
250
800
~45 (~27)
~24(~15)
Eff. running time / yr (pulses)
3 x 105
K+ decays per year
1.0x1011
4.8x1012
 48

24. CERN P-326: K+Decays in flight
~11 MHz n
800 MHz beam
p/K/p n