Date post: | 18-Jan-2018 |
Category: |
Documents |
Upload: | jean-bradley |
View: | 226 times |
Download: | 0 times |
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 11 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
Future rare kaon decays experimentsFuture rare kaon decays experiments
How will the UT look like in years >2010?…
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 22 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
Why study rare K decays in the LHC era?Why study rare K decays in the LHC era? Are K rare decays still interesting? Are K rare decays still interesting? More importantly, will it be worth to study them in the years of LHC? More importantly, will it be worth to study them in the years of LHC?
Theory tells us: yes, a few K rare decays are – and will be – still very Theory tells us: yes, a few K rare decays are – and will be – still very interestinginteresting
because:because: There could be more degrees of freedom near the electroweak scale, i.e. There could be more degrees of freedom near the electroweak scale, i.e.
New Physics beyond the SMNew Physics beyond the SM We know very well the flavour mixing, but we still do not understand the We know very well the flavour mixing, but we still do not understand the
underlying mechanismunderlying mechanism
Rare K decays are the ideal toolsRare K decays are the ideal tools
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 33 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
Why study rare K decays in the LHC era?Why study rare K decays in the LHC era?
Rare K decays are the ideal tools:Rare K decays are the ideal tools: Mediated by Mediated by Flavour Changing Neutral CurrentsFlavour Changing Neutral Currents Strongly Strongly suppressedsuppressed by the by the hierarchyhierarchy in the CKM matrix in the CKM matrix Theoretically Theoretically cleanclean since dominated by since dominated by short-distanceshort-distance contributions contributions
In other words, from K rare decays we can extract information on the flavour In other words, from K rare decays we can extract information on the flavour structure of New Physicsstructure of New Physics
ss ddVVtdtdVVtsts**
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 44 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
Flavour mixingFlavour mixing
'''
ub
cb
td
ud us
cd cs
ts tb
VV
V V
d ds sb b
V
V
VV V
- 3 generations (implying CP violation is possible)3 generations (implying CP violation is possible)- hierarchyhierarchy
Quark mixing is described by the Cabibbo-Kobayashi-Maskawa (CKM) matrixQuark mixing is described by the Cabibbo-Kobayashi-Maskawa (CKM) matrix
Success of the Standard Model: Direct CP violation in the K system: ’ 0 [NA48, KTeV] CP violation in the B sector: ACP(J/ Ks), [BaBar, Belle]
Now we need precise determinations of the CKM parameters: Use observables with small theoretical errors
Im Im tt= Im V= Im Vtsts*V*Vtd td ≠ 0≠ 0
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 55 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
UT fitsUT fits
Constraints from |VConstraints from |Vubub| / |V| / |Vcbcb|, Δm|, ΔmBdBd and Δm and ΔmBsBs compared with constraints from CP violating compared with constraints from CP violating quantities in the K (εquantities in the K (εKK) and in the B (sin2β) ) and in the B (sin2β) sectorssectors
ρ = 0.181 ± 0.060 ρ = 0.181 ± 0.060 η = 0.404 ± 0.035 η = 0.404 ± 0.035
95% confidence regions extracted using 95% confidence regions extracted using |V|Vubub| / | V| / | Vcbcb|, ε|, εKK, Δm, ΔmBdBd, Δm, ΔmBsBs and sin2β and sin2β
ρ = 0.214 ± 0.047 ρ = 0.214 ± 0.047 η = 0.343 ± 0.028 η = 0.343 ± 0.028
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 66 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
KL eeKL vv
UT and rare K decaysUT and rare K decays
KL
K vv
Already strong bounds on the unitarity triangle come from K and B Already strong bounds on the unitarity triangle come from K and B F=2 and tree level transitionsF=2 and tree level transitions FCNC transitions can tell us more…FCNC transitions can tell us more…
Im t = A2 5 Re t = A2 5
Enhanced sensitivity to SM Enhanced sensitivity to SM violations because of strong violations because of strong CKM suppression ~CKM suppression ~5
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 77 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
New Physics potentialNew Physics potential
SecondSecond order weak interactions order weak interactions sensitive to NPsensitive to NP
A A deviationdeviation from the predicted rates of SM would be a from the predicted rates of SM would be a clear clear indicationindication of of NPNP
Complementary program to the highComplementary program to the high--energy frontier:energy frontier: If [If [WhenWhen!]!] new physics will appear at the new physics will appear at the LHCLHC, rare decays may help , rare decays may help
to understand the nature of it to understand the nature of it
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 88 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
New Physics scenarioNew Physics scenarioVVttddVVttss
**
ss dd
ss dd
•Is flavour mixing completely Is flavour mixing completely governed by universal CKM matrix?governed by universal CKM matrix?
No extra complex phasesNo extra complex phases
Same operators as in Standard Same operators as in Standard Model, but with different coefficientsModel, but with different coefficients
High correlation between K and B High correlation between K and B rare decaysrare decays
yesyes
Minimal flavour violation (MFV)Minimal flavour violation (MFV)
Extra phases Extra phases
- can lead to large deviations from - can lead to large deviations from SM prediction (especially for the SM prediction (especially for the CP-violating modes)CP-violating modes)
nono
New flavour simmetry breaking, New flavour simmetry breaking, ~ 1 TeV natural scale ~ 1 TeV natural scale
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 99 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
Expected improvements NNLO calculation + reduction parametric CKM Expected improvements NNLO calculation + reduction parametric CKM uncertainties uncertainties 2 % error expected in the next few years 2 % error expected in the next few years
KK++→→++ : SM prediction : SM prediction
The hadronic matrix element can be extracted from theThe hadronic matrix element can be extracted from the well measured Kwell measured K++→→ee++ Small theoretical uncertainty, no long distance contributionsSmall theoretical uncertainty, no long distance contributions
QCD NLOBuchalla,Buras 1999
= C+ A4 [] = (8.0±1.0) 10-11
BRSM(K)
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 1010 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
Expect to be completely dominated by parametric CKM uncertainties [VExpect to be completely dominated by parametric CKM uncertainties [Vtdtd and and mmtt] in the next few years] in the next few years
The cleanest mode!The cleanest mode!
KKLL→→00 : SM prediction : SM prediction
BRSM(KL) = C0 [Im(Vts* Vtd)/10-4]2 = (3.0±0.6) 10-11
Already at the level of 2 % Already at the level of 2 %
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 1111 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
So, why study rare K decays in the LHC era?So, why study rare K decays in the LHC era?1.1. Search for Search for explicit violation of Standard Modelexplicit violation of Standard Model
Lepton Flavour ViolationLepton Flavour Violation2.2. Study the Study the strong interactions at low energystrong interactions at low energy
Chiral Perturbation Theory, Form FactorsChiral Perturbation Theory, Form Factors3.3. Test fundamental Test fundamental symmetriessymmetries
CP,CPT CP,CPT 4.4. Probe the Probe the flavour sectorflavour sector of the Standard Model of the Standard Model
FCNCFCNC
11stst ingredient: ingredient:
Physics!Physics!
KKLL→→llllKKLL→→KK++→→are the golden modes…are the golden modes…
BR ~ 10BR ~ 10-10-10 or below or belowfew % precision desirable to match the theoretical errorfew % precision desirable to match the theoretical error
Need very intense kaon beamsNeed very intense kaon beams Need dedicated detectors with exceptional background rejectionNeed dedicated detectors with exceptional background rejection
……more more
needed!needed!
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 1212 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
Rare K decays panoramaRare K decays panorama
KAMI @FNALpK=10 GeV38M/s
CKM @FNALseparated, pK=22 GeV9 M/s
P940 @FNALunseparated, pK=45 GeV 3.5 M/s
KOPIO @BNLpK=0.7 GeV33 M/s
P326 @CERNunseparated, pK=75 GeV9 M/s
E391a @KEKpK=2 GeV0.6 M/s
E391a @JPARCpK=2 GeV 320 M/s
K
K
E787 @BNLstopped K
E949 @BNL
OKA @Protvinoseparated, pK=15 GeV 0.4 M/s
E949 @JPARCpK=0.6 GeV2.3 M/s
KLOD @Protvino7 M/s
JPARC is coming …JPARC is coming … you’ve heard from Tadashi Nomurayou’ve heard from Tadashi Nomura
I will concentrate on I will concentrate on P326 in the followingP326 in the following
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 1313 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
P326: KP326: K→→ at the CERN SPS… at the CERN SPS… 400 GeV protons from the SPS, producing an 400 GeV protons from the SPS, producing an high intensityhigh intensity kaon beam kaon beam
22ndnd ingredient: ingredient:
The beamThe beam
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 1414 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
……using part of the NA48 setup…using part of the NA48 setup…
Some pieces [and many physicists] from previous [successful] kaon experimentsSome pieces [and many physicists] from previous [successful] kaon experiments
33rdrd ingredient: ingredient:
A community A community
of physicistsof physicists
44thth ingredient: ingredient:
A suitable detector!
A suitable detector!
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 1515 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
……but P326 is also much more!but P326 is also much more!The P326 project wants to exploit aThe P326 project wants to exploit a combination of opportunitiescombination of opportunities::
1.1. A strongA strong physics casephysics case eagerly waited from theoristseagerly waited from theorists fully complementary to the high-energy frontierfully complementary to the high-energy frontier
2.2. The possibility of having an high intensity kaon beam at the CERN SPS, The possibility of having an high intensity kaon beam at the CERN SPS, using anusing an existing infrastructureexisting infrastructure
3.3. A A communitycommunity of of (enthusiast) (enthusiast) physicists coming from successful kaon physicists coming from successful kaon physics experiments (NA48, KLOE, and more)physics experiments (NA48, KLOE, and more)
4.4. The possibility of using The possibility of using part ofpart of anan high-performance and highly-high-performance and highly-specializedspecialized detectordetector as NA48 [in particular very valuable parts as the as NA48 [in particular very valuable parts as the Liquid Kr, the vacuum tank, the hodoscope, the magnet, the muon Liquid Kr, the vacuum tank, the hodoscope, the magnet, the muon detector, …]detector, …]
… … but it is also a playground for further improving experimental but it is also a playground for further improving experimental techniques for rare kaon decays studies by dedicated R&D studiestechniques for rare kaon decays studies by dedicated R&D studies
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 1616 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
Measurement technique: decay in flightMeasurement technique: decay in flight
K
p (GeV/c)
ppK K = 75 GeV/c= 75 GeV/c At least 10% acceptanceAt least 10% acceptance Signal to background Signal to background 10:1 10:1 80 events in 2 years80 events in 2 years 10101212 rejection power needed rejection power needed Define kinematical cuts ...Define kinematical cuts ...
K
K
2 2 2 2( cos )miss K K K Km EE pm m p
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 1717 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
Background rejectionBackground rejection
92% of total background92% of total background
Define a Define a signal regionsignal region Due to KDue to K++ , , split signal region in 2 split signal region in 2
Span across the signal regionSpan across the signal region
Kinematically constrainedKinematically constrained Not kinematically constrainedNot kinematically constrained
8% of total background8% of total background
2 2 2 2( cos )miss K K K Km EE pm m p
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 1818 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
Background rejectionBackground rejection
Kinematical cuts Kinematical cuts are not sufficient to are not sufficient to bring down bring down backgrounds by a backgrounds by a factor ~10factor ~101212
Need Need veto veto detectordetectors!s!
RejectionRejection
0.05e
0.03
0.02
0.06
0.21
0.63
BRBRDecayDecay
kine
mat
ics
kine
mat
ics
charged charged
vetoveto
E/pE/p
vetoveto
vetoveto
vetoveto
vetoveto
vetoveto
vetoveto
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 1919 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
An experimental challenge!An experimental challenge! Track and identify kaons in the beamTrack and identify kaons in the beam
atat 0.8 GHz0.8 GHz rateratewithwith 0.5%0.5% momentum resolutionmomentum resolutionwithwith 150 ps150 ps time resolutiontime resolutionwith a tight material budgetwith a tight material budget
Track decay productsTrack decay productsin ain a 1010-6-6 mbar mbar vacuumvacuumwithwith 0.5%0.5% momentum resolutionmomentum resolutionwithwith 150 ps150 ps time resolutiontime resolutionwith a tight material budgetwith a tight material budget
Reject Reject and veto additional and veto additional with awith a 1010-5-5 single single detection detection inefficiency inefficiency EE > 1 GeV > 1 GeV
Reject Reject background atbackground at 1010-6-6 levellevel1010 separation at high pseparation at high p
GigaTracker
GigaTracker
+ Cherenkov
+ Cherenkov
Liquid Krypton
Liquid Krypton
+ + vetoes vetoes
Straw tracker
Straw tracker
+ hodoscope
+ hodoscope
Magnetized
Magnetized
Iron + RICH
Iron + RICH
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 2020 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
What is already available: NA48 What is already available: NA48
1996Total: 5.3M KL00
Magnetic spectrometerMagnetic spectrometer
90 m vacuum tank90 m vacuum tank
beambeam
Liquid krypton Liquid krypton EM calorimeterEM calorimeter
HodoscopeHodoscopeMagnetizedMagnetizedIronIron
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 2121 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
Experiment layoutExperiment layout
*
*
**m
agne
t
mag
net
*
* Already available
1 m
200 m0 m 100 m
Gigatracker
Notice the ~30:1 aspect ratioNotice the ~30:1 aspect ratio
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 2222 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
P326 beamP326 beamK12
NA48/2K12 P326
SPS protons/pulse on T10 1×1012 3×1012
Duty cycle (s./s.) 4.8 / 16.8Solid angle (msterad) 0.40 16K+ momentum <pK> [band] (GeV/c)
60 [4%] 75 [1%]
Area at Gigatracker (cm2) 7.0 20Total beam/pulse (107) 5.5 250[per eff. spill length MHz] 18 800 MHz/cm2 (at Gigatracker) 2.5 40Eff. run time / year (pulses)
3×105 3.1×105
K+ decays per year (60 m fiducial region)
1.01011 4.8×1012
QuadrupolesQuadrupolesQuadrupolesQuadrupoles
Dipoles Dipoles (1(1stst achromat) achromat)
Muon Muon sweepsweep C
ED
AR
CE
DA
R
Dipoles Dipoles (2(2ndnd achromat) achromat)
GigatrackerGigatracker
ScraperScraper
Col
limat
orC
ollim
ator
Col
limat
orC
ollim
ator
From From T10 targetT10 target
Col
limat
orC
ollim
ator
Almost 50Almost 50×× more kaons with more kaons with presentpresent SPS SPS
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 2323 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
Challenge #1Challenge #1 Track and identify kaons in the beamTrack and identify kaons in the beam
atat 0.8 GHz0.8 GHz rateratewithwith 0.5%0.5% momentum resolutionmomentum resolutionwithwith 150 ps150 ps time resolutiontime resolutionwith a tight material budgetwith a tight material budget
GigaTracker
GigaTracker
+ Cherenkov
+ Cherenkov
Beam Cherenkov counter already available (CEDAR) Beam Cherenkov counter already available (CEDAR) New photo-detectorsNew photo-detectors Will be tested at SPS North Area in OctoberWill be tested at SPS North Area in October
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 2424 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
GigatrackerGigatrackerSpecifications: Specifications:
Momentum resolution Momentum resolution ~ 0.5 % ~ 0.5 % Angular resolution Angular resolution ~ 10 ~ 10 radrad Time resolution Time resolution ~ 100 ps~ 100 ps Minimal material budgetMinimal material budget Perform all of the above in Perform all of the above in 800 MHz800 MHz hadron beam, hadron beam,
40 MHz/cm40 MHz/cm22
36 mm36 mm
48 m
m48
mm
Station 1Station 1
Station Station 22
Station Station 33
Hybrid Detector:Hybrid Detector: SPIBES (Fast Si micro-pixels)SPIBES (Fast Si micro-pixels)
Momentum measurement Momentum measurement Facilitate pattern recognition in subsequent FTPCFacilitate pattern recognition in subsequent FTPC Timing to select the right trackTiming to select the right track
FTPC (NA48/2 KABES micro-megas with FADC readout)FTPC (NA48/2 KABES micro-megas with FADC readout) Track directionTrack direction
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 2525 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
Gigatracker: Si micro-pixelGigatracker: Si micro-pixel
Timing resolution (ps)Timing resolution (ps)
Sign
al/B
ackg
roun
d ra
tioSi
gnal
/Bac
kgro
und
ratio
size: 36 mm (X) × 48 mm (Y)size: 36 mm (X) × 48 mm (Y) pixel size: 300 pixel size: 300 m × 300 m × 300 mm chip thickness 100 chip thickness 100 mm X/XX/X << 1% << 1% momentum resolution 0.4%momentum resolution 0.4%
Objective: Objective: (t) ~ 200 ps (per station):(t) ~ 200 ps (per station):
Complex readout chip bump-bonded on Complex readout chip bump-bonded on the sensor 0.13 the sensor 0.13 m CMOS technology m CMOS technology (now under development, CERN+INFN)(now under development, CERN+INFN)
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 2626 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
Gigatracker: FTPCGigatracker: FTPC
driftE
driftE
Tdrift1
Tdrift2
mmicroicro-m-megasegas
ggap 25 ap 25 mm
Gas TPC + micro-megasGas TPC + micro-megas Coming from NA48/2Coming from NA48/2 R&D on new, fast, readout electronics R&D on new, fast, readout electronics
to improve time resolutionto improve time resolution
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 2727 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
Challenge #2Challenge #2
Track decay productsTrack decay productsin ain a 1010-6-6 mbar mbar vacuumvacuumwithwith 0.5%0.5% momentum resolutionmomentum resolutionwithwith 150 ps150 ps time resolutiontime resolutionwith a tight material budgetwith a tight material budget
Straw tracker
Straw tracker
+ hodoscope
+ hodoscopeUncorrelated Non-Gaussian Uncorrelated Non-Gaussian tails due to Non-Gaussian ptails due to Non-Gaussian p resolutionresolution
MMmissmiss22 (GeV/c (GeV/c22))22
Region IRegion I Region IIRegion II
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 2828 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
Straw tracker in vacuumStraw tracker in vacuum 6 chambers with 4 double layers of 6 chambers with 4 double layers of straw tubesstraw tubes 9.6 mm diameter 9.6 mm diameter Rate: ~45 KHz per tube (max 0.5 MHz) (Rate: ~45 KHz per tube (max 0.5 MHz) ())
130 130 m/hit m/hit (p)/p = 0.23% (p)/p = 0.23% 0.005% p 0.005% p(() ~ 50 ) ~ 50 20 mrad 20 mrad
2 magnets2 magnets270 and 360 MeV P270 and 360 MeV Pt t kickkick
5 cm radius beam holes 5 cm radius beam holes displaced in the bending plane displaced in the bending plane according to the beam path according to the beam path
Redundant Redundant p measurementp measurement
Good resolutionGood resolution
Low massLow mass Operate in high vacuumOperate in high vacuum
X/XX/X00 ~ 0.1% per view ~ 0.1% per view
Veto for charged Veto for charged particles particles up to 60 GeV/cup to 60 GeV/c
8.8
m
7.2
m
7.2
m
5.4
m
2.3
m
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 2929 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
TRT ATLAS TRT ATLAS
Straw diameter – 4 mm, length – 40 and 150 cmStraw diameter – 4 mm, length – 40 and 150 cm
17 end-cap wheels are built in JINR (105 kpc of straws)
COMPASS TRACKERCOMPASS TRACKER
Straw diameter – 6 and 10 mm, length up to 3.8 mStraw diameter – 6 and 10 mm, length up to 3.8 m
15 chambers were built in JINR15 chambers were built in JINR
Straw trackers were already operated in vacuum:Straw trackers were already operated in vacuum:COSY-TOF, Juelich,COSY-TOF, Juelich,MECO, BNL MECO, BNL
but …but …
Straw tracker in vacuumStraw tracker in vacuum
… … no large straw detector operated in vacuum since nowno large straw detector operated in vacuum since now
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 3030 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
Challenge #3Challenge #3
Reject Reject and veto additional and veto additional with awith a 1010-5-5 single single detection detection inefficiency inefficiency EE > 1 GeV > 1 GeV
Liquid Krypton
Liquid Krypton
+ + vetoes vetoes
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 3131 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
Photon vetoesPhoton vetoes
Large angle vetoesLarge angle vetoes
EE GeV GeV InefficiencyInefficiency
< 0.05< 0.05 11
0.05 ÷ 10.05 ÷ 1 1010-4-4
>1>1 1010-5-5
Liquid Kripton
Liquid Kripton
EE GeV GeV InefficiencyInefficiency
< 1< 1 11
1 ÷ 31 ÷ 3 1010-4-4
3 ÷ 53 ÷ 5 1010-4-4,10,10-5-5
>5>5 1010-5-5
ANTI: ANTI: Rate ~4 MHz (Rate ~4 MHz ()+ ~0.5 MHz ()+ ~0.5 MHz () (OR of 13 rings)) (OR of 13 rings)
Liquid Kripton: Liquid Kripton: Rate ~7 MHz (Rate ~7 MHz () + ~4 MHz () + ~4 MHz ()+ ~3 MHz ()+ ~3 MHz () )
in vetoin veto
in LKrin LKr
(rad)
(rad)
E (G
eV)
E (G
eV)
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 3232 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
Liquid Kripton calorimeterLiquid Kripton calorimeter
Must achieve inefficiency Must achieve inefficiency < 10< 10-5-5 to detect photons above to detect photons above 1 GeV 1 GeV
Advantages:Advantages: It exists It exists Homogeneous (not sampling) ionization calorimeterHomogeneous (not sampling) ionization calorimeter Very good granularity (~2 Very good granularity (~2 2 cm2 cm22)) Fast read-out (Initial current, FWHM~70 ns)Fast read-out (Initial current, FWHM~70 ns) Very good energy ~1%, Very good energy ~1%, Very good time ~ 300 ps, and position ~1 mm resolutionVery good time ~ 300 ps, and position ~1 mm resolution
Disadvantages:Disadvantages: 0.5 % X0.5 % X00 of passive material in front of active LKr of passive material in front of active LKr The cryogenic control system needs to be updatedThe cryogenic control system needs to be updated
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 3333 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
Veto ringsVeto rings Set of ring-shaped photon vetoes Set of ring-shaped photon vetoes
surrounding the decay tanksurrounding the decay tank Extensive R&D performed by American and Extensive R&D performed by American and
Japanese groups…Japanese groups…… … followed by specialized studies for P326 by followed by specialized studies for P326 by
INFN groupsINFN groups Inefficiency as low asInefficiency as low as 10 10-5-5 challenging but challenging but
possiblepossible Baseline solution: Baseline solution:
Lead/Plastic scintillator sandwich with WLS Lead/Plastic scintillator sandwich with WLS fibers readoutfibers readout
Large contribution to the total cost of the Large contribution to the total cost of the P326 project P326 project
Small angle calorimeters to close the gap of Small angle calorimeters to close the gap of the beam-pipethe beam-pipe
Decay tubeDecay tube
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 3434 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
Challenge #4Challenge #4
Reject Reject background atbackground at 1010-6-6 levellevel1010 separation at high pseparation at high p
Magnetized
Magnetized
Iron + RICH
Iron + RICH
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 3535 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
MAMAgnetized gnetized MUMUon on DDetectoretector
Pole gap is 30Pole gap is 3011 cm11 cm22
Coils cross section 15Coils cross section 1525 cm25 cm22
To provide pion/muon separation and beam sweeping.To provide pion/muon separation and beam sweeping. 150 iron plates, 2 cm thick (260150 iron plates, 2 cm thick (260260 cm260 cm22))
Four coilsFour coils magnetize the iron plates to provide amagnetize the iron plates to provide a 1.3 T dipole field1.3 T dipole field in the beam regionin the beam region Active detector:Active detector:
Strips of extruded polystyrene Strips of extruded polystyrene scintillatorscintillator ( (1144130 cm130 cm33) ) Light is collected by Light is collected by WLS fibers WLS fibers ((1.2 mm diameter1.2 mm diameter)) rejection 10rejection 10-5-5
About 7 MHz of muons and 3 MHz of pionsAbout 7 MHz of muons and 3 MHz of pions
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 3636 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
A A RICHRICH for P326 for P326
1 atm Ne gas1 atm Ne gas
18 m18 m
Spherical split mirror, f=17 mSpherical split mirror, f=17 m
PMT’s
PMT’s
PMT’s
PMT’s
18 m long, 1 atm Neon gas18 m long, 1 atm Neon gas 12 GeV threshold for 12 GeV threshold for >3 >3 separation p<35 GeV separation p<35 GeV
beam pipebeam pipe
mirrormirror
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 3737 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
P326 collaboration P326 collaboration
Proposal Proposal SPSC
-P-326SPSC
-P-326
CERNCERN Beam, CEDAR, Gigatracker (SPiBeS), Beam, CEDAR, Gigatracker (SPiBeS), LKr, Trigger & DAQ, SoftwareLKr, Trigger & DAQ, Software
DubnaDubna Straw trackerStraw tracker
INFN Ferrara, TorinoINFN Ferrara, Torino Gigatracker (SPiBeS)Gigatracker (SPiBeS)
INFN Firenze, PerugiaINFN Firenze, Perugia HodoscopeHodoscope
INFN Frascati, Napoli, Pisa, RomaINFN Frascati, Napoli, Pisa, Roma -veto large angle, Trigger & DAQ, -veto large angle, Trigger & DAQ, SoftwareSoftware
MainzMainz Straw trackerStraw tracker
MoscowMoscow MaMuDMaMuD
ProtvinoProtvino MaMuDMaMuD
SaclaySaclay Gigatracker (KaBeS)Gigatracker (KaBeS)
Saint Luis-PotosiSaint Luis-Potosi RICHRICH
SofiaSofia
-veto small angle-veto small angle
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 3838 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
P326 time scheduleP326 time schedule2006-20072006-2007
Refine layout, RICH R&DRefine layout, RICH R&D Gigatracker R&DGigatracker R&D Photon vetoes R&DPhoton vetoes R&D Vacuum testsVacuum tests Straw tracker R&DStraw tracker R&D
Liquid krypton test-beam (Oct. ’06)Liquid krypton test-beam (Oct. ’06)
ApprovalApproval
2008-20092008-2009 Construction, installation and testsConstruction, installation and tests
2010-20112010-2011 Data takingData taking
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 3939 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
P326: going on…P326: going on…
We have found a fortunate combination where aWe have found a fortunate combination where a compelling physics casecompelling physics case can be addressed with ancan be addressed with an existing acceleratorexisting accelerator, employing the , employing the infrastructure (i.e. civil engineering, hardware, some sub-systems) of aninfrastructure (i.e. civil engineering, hardware, some sub-systems) of an existing experiment …existing experiment …
… … even though this aeven though this a newnew initiativeinitiative
And with new, challenging detectors to be designed and builtAnd with new, challenging detectors to be designed and built
We are looking for new collaborators!We are looking for new collaborators!
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 4040 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
Longer term (more protons needed!)Longer term (more protons needed!)
• KK00LL→→ 00eeeeandand K K00
LL→→ 00
• KK00LL →→ 00
See T. Nomura… E391a and JPARCSee T. Nomura… E391a and JPARC
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 4141 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
ConclusionsConclusions Rare K decays Rare K decays areare interesting now, interesting now,
since they are since they are sensitive to New Physicssensitive to New Physics effects effects They will still be very interesting when results will be coming from the LHC? They will still be very interesting when results will be coming from the LHC?
Yes, maybe even more, since they can give unique information on the Yes, maybe even more, since they can give unique information on the flavour structureflavour structure of New Physics of New Physics
Very Very ambitiousambitious experimental programs experimental programs- requiring very requiring very intenseintense hadron hadron beamsbeams - requiring requiring challenging detectorschallenging detectors: hermetic, highly efficient, with PID : hermetic, highly efficient, with PID capabilitiescapabilities
A lively and enthusiastic A lively and enthusiastic communitycommunity- stillstill not tired not tired of many years of success from glorious past kaon of many years of success from glorious past kaon experiments…experiments…- … … even in hard times from the even in hard times from the funding funding point of view! point of view!
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 4242 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 4343 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
KKLL→→00 Purely theoretical error:Purely theoretical error: 2%2%
Purely CP-Violating (Littenberg, 1989) Purely CP-Violating (Littenberg, 1989) Totally dominated from t-quarkTotally dominated from t-quark Computed to NLO in QCD ( Buchalla, Buras, 1999)Computed to NLO in QCD ( Buchalla, Buras, 1999) No long distance contribution: No long distance contribution:
SM 3SM 31010-11-11
Experimentally: 2/3 invisible final state !!Experimentally: 2/3 invisible final state !! Best limit from KTeV using Best limit from KTeV using →→eeee decay decay
BR(K0 → ) < 5.9 10-7 90% CL
Still far from the model independent limit: Still far from the model independent limit: BR(KBR(K00 → → ) < 4.4 ) < 4.4 BR(KBR(K++ → → ) ~ 1.4) ~ 1.41010-9-9 Grossman & Nir, PL B407 (1997)Grossman & Nir, PL B407 (1997)
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 4444 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
Looking at the far future…Looking at the far future…
A competitive program can start A competitive program can start nownow for charged kaons for charged kaons at the current SPS at the current SPS
For a very competitive neutral kaon decay experiment, For a very competitive neutral kaon decay experiment, ~ 10~ 101313 slowly extracted, high energy protons per second slowly extracted, high energy protons per second would be neededwould be needed
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 4545 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
E949E949Stopped K technique ~0.1 % acceptanceStopped K technique ~0.1 % acceptance
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 4646 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
2 events E787 + 1 event E9492 events E787 + 1 event E949
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 4747 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
E787/E949 resultE787/E949 result
BR(KBR(K→→ = 1.47 = 1.47 +1.30+1.30-0.89 -0.89 1010-10 -10
22 the Standard Model, the Standard Model, but with a large error (3 events…)but with a large error (3 events…)
AGS
hep-ex/0403036 PRL93 (2004)
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 4848 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
E391aE391a
CsI calorimeterCsI calorimeter
Front barrelFront barrel Main barrelMain barrel
Vacuum tankVacuum tank
Then going to J-PARC…Then going to J-PARC…
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 4949 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
E949 @JPARCE949 @JPARC Stopped KStopped K++
With respect to E787/949:With respect to E787/949: Lower energy Lower energy Separated beamSeparated beam Spectrometer: higher B fieldSpectrometer: higher B field More compactMore compact Better resolutionBetter resolution Finer segmentationFiner segmentation Improved Improved veto detector (crystals) veto detector (crystals)
Objective: Objective: 50 events50 events
Not in J-PARC phase-1Not in J-PARC phase-1 Needs beamline, room, fundingNeeds beamline, room, funding
Paolo Valente – INFN Roma – Paolo Valente – INFN Roma – 5050 BEACH 2006, Lancaster UniversityBEACH 2006, Lancaster University
KLODKLOD
IHEP Protvino 60 GeV proton beamIHEP Protvino 60 GeV proton beam
Off-axis angle=35 mradOff-axis angle=35 mrad
KKLL’s peak momentum = ~6 GeV/c’s peak momentum = ~6 GeV/c
Objective: Objective:
28 events/9 background in 3 years28 events/9 background in 3 years
Run in 2008Run in 2008