Yu. PotrebenikovYu. PotrebenikovJINR, DubnaJINR, Dubna
1313thth Lomonosov Conference Lomonosov Conference on Elementary Particle Physics, on Elementary Particle Physics,
Moscow, August 23-29, 2007Moscow, August 23-29, 2007
The The KK++ experiment at experiment at CERNCERN
P326 – NA48/3 – NA62P326 – NA48/3 – NA62
22
The The decays: a clean test of SM decays: a clean test of SM sensitive to new physicssensitive to new physics
Flavor Changing Neutral Current loop process: sFlavor Changing Neutral Current loop process: sd coupling d coupling and highest CKM suppressionand highest CKM suppression
Very clean theoretically: short Very clean theoretically: short distance contributions dominate, distance contributions dominate, hadronic matrix element can be hadronic matrix element can be related to measured quantitiesrelated to measured quantities((KK++00ee++..
SM predictions (uncertainties from CKM elements):SM predictions (uncertainties from CKM elements): BR(BR(KK++++) ) (1.6×10 (1.6×10-5-5)|V)|Vcbcb||44[[22+(+(cc--))22] ] (8.0 ± (8.0 ± 1.1)×101.1)×10-11-11
BR(BR(KKLL00) ) (7.6×10 (7.6×10-5-5)|V)|Vcbcb||442 2 ± 0.6± 0.6×10×10-11-11
Sensitive to New PhysicsSensitive to New PhysicsPresent measurement (E787/949): Present measurement (E787/949): BR(KBR(K++) = 1.47 ) = 1.47 × 10× 101010 (3 events)(3 events)
+1.30
-0.89
-
Golden modes
33
Effects of new physics on KEffects of new physics on K decaysdecays
F. MesciaCKM 2006
Effects of new physics on decays
44
Setting the bar for future Setting the bar for future experiments experiments
P3
26
P3
26
E787/949E787/949
BR(KBR(K++) = 1.47 ) = 1.47 ×10×101010
+1.30-0.89
SM
F. MesciaCKM 2006
100 100 eventseventsMean:
E787/949
55
September 2005: presented at CERN SPSCSeptember 2005: presented at CERN SPSCDecember 2005: R&D endorsed by CERN Research BoardDecember 2005: R&D endorsed by CERN Research BoardStart of the Gigatracker projectStart of the Gigatracker projectStart of test beams at CERN in 2006Start of test beams at CERN in 20062007: prototypes construction and test at CERN and Frascati 2007: prototypes construction and test at CERN and Frascati beamsbeams2008 – 2010: Technical design and construction2008 – 2010: Technical design and construction2011 - Start of data taking2011 - Start of data taking
Proposal to Measure the Rare Decay Proposal to Measure the Rare Decay at the CERN SPS (P326)at the CERN SPS (P326)
CERN, Dubna, Ferrara,CERN, Dubna, Ferrara,Florence, Frascati, Mainz,Florence, Frascati, Mainz,Merced, Moscow, Naples,Merced, Moscow, Naples,Perugia, Protvino, Pisa,Perugia, Protvino, Pisa,Rome, Saclay, San Luis Rome, Saclay, San Luis
Potosi, Potosi, Sofia, Triumf, TurinSofia, Triumf, Turin
CERN-SPSC-2005-013 SPSC-P-326
Schedule
Located in the same hall of NA48Located in the same hall of NA48
66
Base of the NA62 (NA48/3)Base of the NA62 (NA48/3)
O(100) K++events ~ 10% background
1) Physics: BR(SM) = 8×10-11
Acceptance 10%Acceptance 10%KK decays ~10 decays ~101313
Kaon decay in flight techniqueKaon decay in flight techniqueIntense proton beam from SPSIntense proton beam from SPSHigh energy K (PHigh energy K (PKK = 75 GeV/c) = 75 GeV/c) Kaon IDKaon ID
Kinematical rejectionKinematical rejection
Veto and particle IDVeto and particle ID
Kaon 3-momentum: beam trackerKaon 3-momentum: beam trackerPion 3-momentum: spectrometer Pion 3-momentum: spectrometer // detection: calorimeters detection: calorimetersCharged veto: spectrometerCharged veto: spectrometer///e separation: RICH/e separation: RICH
2) Budget: …Use as much as possible Use as much as possible the existing the existing NA48 NA48 infrastructuresinfrastructures
Be pragmaticBe pragmatic
KK+
m2miss=(PKP)2
77
BackgroundsBackgrounds
92% of total background
Allows us to define a signal region K+ +0 forces us to split it into
two parts (Region I and Region II)
Span across the signal region Rejection must rely on veotes
Kinematically constrained Not kinematically constrained
8% of total background
88
K+→ (K)
Largest BR: 63.4%Need ~10-12 rejection factor• Kinematics: 10-5
• Muon Veto: 10-5 MAMUD• Particle ID: 5×10-
3RICH
K+→ (K)
2nd largest BR: 20.9%Need ~10-12 rejection factor• Kinematics: 5×10-3• Photon Veto: 10-5 per photon
Assuming the above veto inefficiencies and an acceptance of 10%, a S/B > 10 is obtained if
mmiss2 ~ 8×10-3GeV2/c4
Resolution requirements:
P< 1 %, PK 0.3 %, K 50-60 μrad
Largest background rejectionLargest background rejection
99
Layout of the experimentLayout of the experiment
+
10-6 mbar
+
VACUUM10-6 mbar
50 MHz
800 MHz 11 MHz
K+ ~ 75 GeV
P proton = 400 GeV/cProton/pulse 3.3×1012 (3.3×NA48/2)
Duty cycle 4.8/16.8 s
P Kaon = 75 GeV/c (P/P = 1.1%)Fraction of Kaons ~ 6.6%Negligible amount of e+
Beam acceptance = 12 str (25× NA48/2)Area @ beam tracker = 58×24 mm2
Integrated average rate = 760 MHzKaon decays / year = 4.8 × 1012
1010
The Tracking system: GigatrackerThe Tracking system: Gigatracker
Low Low X/XX/X00 not to spoil the beam not to spoil the beam
Good space resolution to match the Good space resolution to match the downstream tracker resolutiondownstream tracker resolution
200 Si m sensor + 100 Si m chip
300×300 m pixels(PK)/PK ~ 0.22%(K) ~ 16 rad(
(
Excellent time resolution Excellent time resolution needed for K+/needed for K+/+ association: + association: (t)~200 ps(t)~200 ps per station per station
Readout chip bump-bonded on the sensor (0.13 m technology)
The Gigatracker (i.e. the beam tracker)
Rate: 760 MHz (charged particles) ~60MHz/cmRate: 760 MHz (charged particles) ~60MHz/cm22
3 Si pixel stations across the 2nd achromat: size 60 × 27 mm2
Readout chip: 1st MPW in 0.13Readout chip: 1st MPW in 0.13m technologym technology is ready to test is ready to test (results by September)(results by September)
Si diode irradiation testsPrototype wafers (200µm thick) produced by itc-IRST using ALICE pixel layout3 mm × 3 mm and 7 mm × 7 mm test-diodesTest 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
1111
The Tracking system: Double The Tracking system: Double SpectrometerSpectrometer
6 chambers with 16 layers of straw tubes each
Low X/XLow X/X00
Good space Good space & angle resolution& angle resolution
Redundant p Redundant p measurementmeasurement
Veto for chargedVeto for charged particlesparticles
130 130 m per hitm per hit
2 magnets
The Double Spectrometer (i.e. the downstream tracker)
Rate: ~ 45 KHz per tube (max 0.8 MHz)Rate: ~ 45 KHz per tube (max 0.8 MHz)
5 cm radius beam hole displaced in the bending plane
8.8
m
7.2
m
2
.3 m
In vacuum, X/X0~0.1% per view
1212
Straw prototypeStraw prototype
Chosen technology: ultrasound welded gilded mylar tube (36 Chosen technology: ultrasound welded gilded mylar tube (36 m, D=10 mm, L=2.3 m)m, D=10 mm, L=2.3 m)48 straw prototype has been produced in Dubna48 straw prototype has been produced in DubnaTests on gas leakageTests on gas leakageTests on tube expansion in vacuum Tests on tube expansion in vacuum Prototype assembled & cosmic ray tests Prototype assembled & cosmic ray tests
October 2007: October 2007: Prototype integration in NA48 set-up and test on a beamPrototype integration in NA48 set-up and test on a beam
Design, construction and test of a Straw prototype (Dubna, CERN)Design, construction and test of a Straw prototype (Dubna, CERN)
1313
The Particle Identification system: The Particle Identification system: CEDARCEDAR
CEDAR: existing differential Cerenkov counter at CERN to be placed on the beam Tagging the kaon to keep the Tagging the kaon to keep the
beam background under controlbeam background under controlMinimal material budgetMinimal material budgetGood time resolutionGood time resolution
HH22 instead of Ne instead of NeNew phototubesNew phototubes
The CEDAR (i.e. the kaon ID)
CEDAR W-type filled with NeCEDAR W-type filled with Ne tested tested at CERN in November 2006, using a at CERN in November 2006, using a 100 GeV hadron beam with 10100 GeV hadron beam with 1055 – 10 – 1077 ppp (CERN, Firenze, Perugia).ppp (CERN, Firenze, Perugia).
Beam Composition
00,10,20,30,40,50,60,70,8
1650 1700 1750 1800 1850 1900 1950 2000 2050
Pressure
%
Plan:Plan: to test of fast to test of fast photomultipliers photomultipliers using Cerenkov using Cerenkov light.light.
pion
kaon
proton
1414
The Particle Identification system: RICHThe Particle Identification system: RICH
18 m long tube (2.5 m diamater) filled with Ne @ 1 atm, two 17m focal length mirrors
>3>3 pion/muon pion/muon separation @ 35 GeV/c separation @ 35 GeV/c (13 GeV/c threshold for (13 GeV/c threshold for ))
Time resolution 100 ps Time resolution 100 ps (track timing)(track timing)
VelocityVelocityspectrometerspectrometer(redundancy)(redundancy)
High granularity(2000 PMTs)Small pixel size(18 mm PMT)
Phototubes with very good (t)
The RICH (i.e. the pion ID)
1515
RICH prototypeRICH prototype
Design, construction and test of a RICH prototype (CERN, Design, construction and test of a RICH prototype (CERN, Firenze, Perugia)Firenze, Perugia)
Full length prototype (17 m, 0.6 m diamater, Full length prototype (17 m, 0.6 m diamater, stainless steel tube at CERN) stainless steel tube at CERN)Mirror built, delivered and under test in FirenzeMirror built, delivered and under test in FirenzeEndcap with 96 Hamatsu PMs readout Endcap with 96 Hamatsu PMs readout through Winston’s cones through Winston’s conesPMs tested at SPS (2006) and Firenze (with laser)PMs tested at SPS (2006) and Firenze (with laser)
Measured Measured Full Width Half MaximumFull Width Half Maximum ( (FWHM) FWHM) per single per single per phototube: per phototube: 390ps390ps (150 ps (150 ps electronics and 110 ps laser included)electronics and 110 ps laser included)
FWHM 0.375 ps
t ns
November 2007: November 2007: prototype integration prototype integration into the NA48 set up into the NA48 set up and test with beam and test with beam
1616
The Veto systemThe Veto system
Large angle (10, 50 mrad): Rings calorimeters (in vacuum)Rate: ~4.5 MHz (Rate: ~4.5 MHz () + ~0.5 MHz () + ~0.5 MHz () ) 1010-4-4 inefficiency for E inefficiency for E in 0.05,1 GeV in 0.05,1 GeV1010-5-5 inefficiency for E inefficiency for E>1 GeV >1 GeV
20 X/X0 Lead scintillator tiles orLead scintillator fibers (KLOE-like) Medium angle (1, 10 mrad): LKr
calorimeterRate: ~8.7 MHz (Rate: ~8.7 MHz ()+~4 MHz ()+~4 MHz () )+~3 MHz () )+~3 MHz ())1010-4-4 inefficiency for E inefficiency for E in 1,5 GeV in 1,5 GeV1010-5-5 inefficiency for E inefficiency for E>5 GeV >5 GeV
Small angle (<1 mrad): Shashlik technologyRate: 0.5 MHz (Rate: 0.5 MHz ())
1010-5-5 inefficiency (high energy photons) inefficiency (high energy photons)
New Readout
Extruded scintillator – lead sampling calorimeter 6 m long + magnet for beam deflectionRate: ~7 MHz (Rate: ~7 MHz ()+~3 MHz ()+~3 MHz ())1010-5-5 inefficiency for inefficiency for detection detection
Deviate the beam out from the SACDeviate the beam out from the SAC
em/hadronic cluster separation.Sensitivity to the MIP5Tm B field in a 30×20cm2 beam hole
Photon vetoes
Muon veto
1717
Large angle Photon VetoesLarge angle Photon Vetoes
KLOE-type lead/scintillating fiber: prototype constructed in KLOE-type lead/scintillating fiber: prototype constructed in FrascatiFrascati1 mm diameter scintillating fibers, 1 mm diameter scintillating fibers, 0.5 mm thick lead foils. 0.5 mm thick lead foils.
Readout granularity: 18 cellsReadout granularity: 18 cellsVery well known and tested technologyVery well known and tested technologyUnder test at the Frascati BTFUnder test at the Frascati BTF
16.8 cm 8.2 cm
All fiber: 8 X0
Fibers+lead wires:
9 X0
Studies of the efficiency of detectors Studies of the efficiency of detectors built with this technology availablebuilt with this technology availableFermilab prototype under test at BTFFermilab prototype under test at BTF
Outgassing tests performed at CERN Outgassing tests performed at CERN on detectors built with same on detectors built with same technology: they can be placed in the technology: they can be placed in the vacuum of the decay region (10vacuum of the decay region (10 -6-6 mbar)mbar)
Lead scintillator tiles
1818
Large angle Photon Vetoes testsLarge angle Photon Vetoes tests
ee
Test beam activity at BTF in Test beam activity at BTF in FrascatiFrascati (Frascati, Napoli, Pisa, Roma)(Frascati, Napoli, Pisa, Roma)
ee-- beam (300-500 MeV/c) beam (300-500 MeV/c)Both calorimeter prototypes under testBoth calorimeter prototypes under test11stst step: test with electrons step: test with electrons22ndnd step: test with photons step: test with photons
Test beam periods: March, April, June 2007Test beam periods: March, April, June 2007The main result:The main result: both prototypes show both prototypes show goodgoodcharacteristics: inefficiency ~ 10characteristics: inefficiency ~ 10-5 -5 for for E=500,E=500,200-350 MeV (10200-350 MeV (10-4-4 for LG due to statistics). for LG due to statistics).Good energy resolution is obtained for fiber Good energy resolution is obtained for fiber
calorimeter:calorimeter:
It is necessary to understand the beam It is necessary to understand the beam background and to make background and to make calibrations of the prototypescalibrations of the prototypes
%63.4)(
%88.5)(
GeVEE
E
1919
Measurement of the inefficiencyMeasurement of the inefficiencyKK++ data taken in a dedicated NA48 data taken in a dedicated NA48 test run in 2004 using Ktest run in 2004 using K++++00
LKr calorimeterLKr calorimeter
Tagged Tagged using an SPS electron beam (2006) using an SPS electron beam (2006)
Inefficiency measured for EInefficiency measured for E > 2.5 GeV > 2.5 GeV> 10 GeV, > 10 GeV, < 10 < 10-5-5 confirmed confirmed< 10 GeV analysis in progress< 10 GeV analysis in progress
Consolidation of the readoutConsolidation of the readoutCustom boards (FPGA based) sending data directly to PC FarmCustom boards (FPGA based) sending data directly to PC FarmTest of the new electronics in 2007 NA48 runTest of the new electronics in 2007 NA48 run
< 10< 10-5-5 (@90% C.L., E(@90% C.L., E>10 >10 GeV)GeV)
electronelectron
Energy deposition in LKr
X LKr cm
En
erg
y G
eV
z
x
vacuum
e beam25 GeV/c
Bremsstrahlung
Kevlar window
Drift chambers
Magnet LKr
e-
He
2020
Preliminary sensitivity studiesPreliminary sensitivity studies
Acceptance (60 m fiducial
volume): Region I: 4% Region II: 13% Total: 17%
To be reduced because of losses due dead time, reconstruction inefficiencies…
Simulation of the P-326 apparatus
Acceptance ~ 10% is achievable
Region I and II Momentum range: 15 < P < 35 GeV/c
Against muons RICH operational reasons Plenty of energy in photon vetoes
2121
Analysis: background rejectionAnalysis: background rejection
Events/yearEvents/year TotalTotal Region IRegion I Region Region IIII
Signal Signal (acc=17%)(acc=17%) 6565 1616 4949
KK++++00 2.72.7 1.71.7 1.01.0
KK++++ 1.21.2 1.11.1 <0.1<0.1
KK++ee++++ ~2~2 negligiblnegligiblee
~2~2
Other 3 – track Other 3 – track decaysdecays
~1~1 negligiblnegligiblee
~1~1
KK++++00 1.31.3 negligiblnegligiblee
1.31.3
KK++++ 0.50.5 0.20.2 0.20.2
KK++ee++((++))00, , othersothers
negligibnegligiblele
Total bckg.Total bckg. <9<9 3.03.0 <6<6
S/B ~ 8 (Region I ~5, Region II ~9)
2222
TriggerTrigger
LevelLevel L0 “hardware” L0 “hardware” L1-L2 “software” L1-L2 “software”
InputInput ~10 MHz~10 MHz 1 MHz1 MHz
OutputOutput 1 MHz1 MHz OO(KHz)(KHz)
ImplementatImplementationion
Dedicated Dedicated hardwarehardware
TDAQ farmTDAQ farm
ActionsActions RICH minimum RICH minimum multiplicity, multiplicity,
Muon vetoing, Muon vetoing, LKr vetoingLKr vetoing
L1 = single sub-L1 = single sub-detectorsdetectors
L2 = whole eventL2 = whole event
Main work on possible solutions for the L0 hardwareMain work on possible solutions for the L0 hardwareTELL-1 board (LHCb) based implementation for all non FADC sub TELL-1 board (LHCb) based implementation for all non FADC sub detectorsdetectorsDesign of a new 100 ps TDC daughter-card (RICH, Straws, MAMUD,…)Design of a new 100 ps TDC daughter-card (RICH, Straws, MAMUD,…)Two prototypes under study (Mainz and Pisa)Two prototypes under study (Mainz and Pisa)
A possible scheme:A possible scheme:
2323
Other physics opportunitiesOther physics opportunities
P-326 Kaon Flux ~100 times NA48/2 Kaon P-326 Kaon Flux ~100 times NA48/2 Kaon FluxFlux
Other physics opportunities can be Other physics opportunities can be addressed:addressed:
Lepton – flavor violation (Lepton – flavor violation (started with a run 2007started with a run 2007): ): KKe2e2/K/K22,K,K++++++ee--, K, K++--++ee++
Search for new low mass particles:Search for new low mass particles: KK++(light RH neutrinos)(light RH neutrinos) KK++++00P P (pseudoscalar sGoldstino)(pseudoscalar sGoldstino)
Hadron spetroscopyHadron spetroscopy
……
2424
ConclusionsConclusions
To search for new physics using rare Kaon decays To search for new physics using rare Kaon decays P-326 experimentP-326 experiment is proposed and prepared for is proposed and prepared for measurement of the Br(Kmeasurement of the Br(K++++) with a ~10% ) with a ~10% accuracy accuracy (& for other physics opportunities(& for other physics opportunities))
General design is mostly defined. Overall simulation Overall simulation and performances are under review.and performances are under review.
The R&D program The R&D program is well advanced: construction of is well advanced: construction of detector prototypes and tests are in progress (in detector prototypes and tests are in progress (in some cases - completed). Important results should some cases - completed). Important results should be obtained be obtained by the end of 2007by the end of 2007
The new experimentThe new experiment should be able to reach a should be able to reach a ~10~10--
1212 sensitivity per event sensitivity per event at at an existing machine and an existing machine and employing the infrastructures of an existing employing the infrastructures of an existing experimentexperiment. .