october 7, 2004a. ceccucci/ cern1 future of rare kaon decays at the cern-sps fermilab, october 7,...

October 7, 2004 A. Ceccucci/ CERN 1

Future of Rare Kaon Decays at the CERN-SPS

Fermilab, October 7 , 2004

A. Ceccucci for the

NA48-Future Working Group


“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.………

……….


NA48 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

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


NA48-Future Working Group

• We identified the Rare Kaon Decays as the next logical step of the Kaon Programme at CERN

• Short term (2004-2010):

NA48/3 K+ → + LETTER OF INTENT

• Longer term (>2010):– Assuming a new or refurbished SPS capable to deliver higher

intensity/energy as the ultimate injector for LHC

NA48/4 KL → 0 ee () NA48/5 KL → 0

CERN-SPSC-2004-010SPSC-EOI-002


Letter of Intent to Measure the Rare Decay K → at the CERN SPS

Cambridge: D. Munday; CERN: N. Cabibbo, A. Ceccucci*, V. Falaleev, F. Formenti, B. Hallgren, A. Gonidec, P. Jarron, M. Losasso, A. Norton, P. Riedler G. Stefanini;Dubna: S. Balev, S. Bazylev, P. Frabetti, E. Goudzovski, D. Gurev,V. Kekelidze, D.

Madigozhin, N. Molokanova, R. Pismennyy, Y. Potrebenikov, A. Zinchenko; Ferrara: W. Baldini, A. Cotta Ramusino, P. Dalpiaz, C. Damiani, M. Fiorini,

A. Gianoli, M. Martini, F. Petrucci, M. Savrie’, M. Scarpa, H. Wahl; Firenze: E. Iacopini, M. Lenti, G. Ruggiero; Mainz: K. Kleinknecht, B. Renk, R. Wanke; UC Merced: R. Winston; Perugia: P. Cenci, M. Piccini; Pisa: A. Bigi, R. Casali, G. Collazuol, F.

Costantini, L. Di Lella, N.Doble, R. Fantechi, S.Giudici, I. Mannelli, A. Michetti, G.M. Pierazzini, M. Sozzi; Saclay: B. Peyaud, J. Derre; Sofia: V. Kozhuharov, L.Litov, S.

Stoynev; Torino: C. Biino, F. Marchetto

*contact person


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 !!


Framework• So far K+→+ only studied with kaon decays at rest

– This limits the statistics to a few events• We plan to collect ~100 events at the SPS by 2010

– We dubbed this initiative NA48/3 – the name is not an issue at this early stage

• Employ high energy kaons has the following advantages:– The larger cross section increases the kaon content in the beam– The rejection of backgrounds from K→ is simplified

• Tens of GeV of EM energy is deposited in the photon vetoes!– Accidental background are minimised

• The use of unseparated beam becomes a possibility• 2/3 of the final state is invisible !!

– The kaon and the pion must be redundantly measured to keep backgrounds under control

– Muon and photon vetoes are essential


Kinematics75 /KP GeV c

K

0K

Region I

K

Region II

K


Acceptance

75 / 40 /

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

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

Accep

tan

ce

Accep

tan

ce

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


THE BEAM


Rationale p0 = primary proton momentum

pk = secondary beam momentum

• Kaon production increases as p02

– Use highest p0 (that is 400 GeV/c protons from SPS)

• For a fixed fiducial length the number of decays increases as pk. If p0 is fixed the maximum is for:

pk = 0.23 p0 • For unseparated beams the limitation comes from

the detectors, not from the amount of protons


Choice of pk=75 GeV/c

Pk (GeV/c

60 75 90 120

K+ flux @ production

( 3 1012 400 GeV/c protons)x108 1.1

1.3 (meas)

1.5 1.9 2.4

2.3 (meas)

K+ survival over 102 m 0.80 0.83 0.86 0.89

K+ / Total beam rate x10-2 5.2

6.8 (meas)

5.5 5.6 5.2

4.7 (meas)

K+ decays in 50 m x106 8.9 10.7 11.6 11.4

75 GeV/c is about the maximum momentum for which a beam incorporatingstages for large solid angle acceptance, momentum selection, K+ tagging, beam momentum measurement and tracking using standard beam elements can fit into the present length of 102 m


NA48/3: Beam Layout

Beam-line 102 m long

about 17%K+ lost

Dipoles

Dipoles


NA48/3: Beam Across Tank


Beam:Present K12

(NA48/2)New HI K+

> 2006Factor

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)

/ … / cm2 (KABES) (MHz)

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


TURTLE SIMULATIONMOMENTUM DISTRIBUTION

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

<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


SPIBES1

X [mm]

Y [mm]

SPIBES2

FTPC (KABES)

BEAM TRANSVERE SIZE


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 6:

X [mm]

Y [mm]


Muon Halo Calculation

• The flux of “halo muons” crossing the WC has been calculated using the HALO program:

• Single rate in the WC is dominated by muons from kaon decays

• The total halo is about 7 MHz• Thank to the new beam design, the

situation appears much better than in NA48/2


DETECTORS


NA48/3 Detector Layout

800 MHz(/K/p)

Only the upstream detectors see the 800 MHz beam

10 MHz Kaon decays


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


2004 Test beam• It was of the utmost importance to test in 2004 the performance

of the NA48 detectors at intensities comparable to NA48/3 (no SPS in 2005!)

• This was a unique opportunity to collect data to validate our –simulated- understanding to quantify the necessary effort (technical and financial) to transform NA48 into an experiment capable to address K+→+ .

• Thank to the extension granted by CERN we could test:– 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 extra LKr electronics and a Small Angle Calorimeter SAC (CMS RCAL prototype)

– CHOD test of prototypes• A few very preliminary results will be shown


Increase of beam Intensity

• I0 = Intensity of NA48/2 K+ beam– Tune the K12 beam to + 75 GeV/c – Open up the aperture of the P42 line (X3.5)– Opening momentum bite P/P from 5 to 20 %

(X4)– Turn on both K+ and K- polarities (X1.3)– Employ a shorter T4 target (100 mm instead of 300

mm) (X1.6) • Tot ~ 29 I0

• Accidentals in 29 I0 beam NA48/2 are dominated by pions rather than kaons– Expect cleaner situation with new beam


CEDAR• CErenkov Differential Counter with Achromatic

Ring Focus• He pressure adjusted to make it sensitive only to kaons• Requires beam divergency < 0.1 mrad • Built at CERN in the 80’s (Bovet et al.) for use in the SPS beam lines• We will certainly need to upgrade the photon detectors and front-end

electronicsto operate at the NA48/3 rates (~60 MHz)

Beam


CEDAR

2 21 2

22

m m

p

K/

( / )p GeV c

Cedar-W

Cedar-N


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

October 7, 2004 A. Ceccucci/ CERN Mara Martini 28

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.


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


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


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


TEST OF KABES IN 2004LOW INTENSITY


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


BEAM DATA: 50/25μ mesh 2003/2004

Time over Threshold (ns)


2004 KABES TEST HIGH INTENSITY FLUX PER UNIT AREA CLOSE TO NA48/3 !


TEST OF KABES with 480 MHz FADC


FADC Readout (1)

• 8 bit FADC 960 MHz (2 interleaved 480 MHz) from NA48 proton tagger• 9 FADC boards (18 channels “480 MHz mode”)• 18 FADC channels connected to KABES strips

in station upstream UP and downstream

K1 23 FADC 16K1 24 FADC 14K1 25 FADC 12K1 26 FADC 10

K2 23 FADC 6K2 24 FADC 4K2 25 FADC 2K2 26 FADC 18

K5 23 FADC 1K5 24 FADC 8K5 25 FADC 3K5 26 FADC 5K5 27 FADC 7

K6 23 FADC 9K6 24 FADC 11K6 25 FADC 13K6 26 FADC 15K6 27 FADC 17

K2K1

K3 K4

K5 K6


Multiple pulses without Zero-suppression


FADC data (1)

• Distribution of time over threshold– Low intensity run– Threshold set to 37 ADC

counts (~27 mV)– ±2 samples over

threshold

~20 ns time over threshold(KABES 25 µm mesh)


FADC data

x1 x3

x7 x12

• Number of pulses per channel as a function of beam intensity

– noisy channels 10,12,14,16 all connected to K1


Multiple pulses with Zero-supp

• Some data from RUN 16964 (14xI0)

• horizontal scale: FADC time units (2×1.04 ns)


Attempt to fit single pulses

23

22

2241 1 P

Pt

ePtPP

• fit of 500 FADC pulses from the low intensity RUN (16916)

• 4 parameters function used:

• uncertainty of 1.7 counts per FADC value


Attempt to fit multiple pulses

• “hand fit” of a six pulses event from run 16964 (x 14 I0)


KABES FADC Conclusion

• We read-out the micro-strips with FADC

• Double pulse resolution capability is very good

• To do list:– develop reconstruction from list of times in

strips and measure resolution (space, time, angular) as a function of beam intensity


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


Current NA48 ANTI


WIRE CHAMBERS


NA48 WC


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 cannot be

overemphasised !!


WC @ 30 x I0


WC: Kinematical rejection

Events accepted

( / )P GeV c

2 2 2( / )missm GeV c0

Reg

ion

IR

eg

ion

I

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


Double spectrometer layoutDCH1DCH1 DCH2DCH2 DCH3DCH3 DCH4DCH4 DCH5DCH5 DCH6DCH6

KevlarKevlar Mag1Mag1 Mag2Mag2

zz

xx

VacuumVacuum HeHe

NA48 Wire chambers 0.004 XNA48 Wire chambers 0.004 X00KevlarKevlar

zz

xx

VacuumVacuum HeHe

NA48 Wire chambers 0.004 XNA48 Wire chambers 0.004 X00Straw tube 0.0025 XStraw tube 0.0025 X00

kickT 211 /P MeV c


Double spectrometerTwo independent measurement of P

DCH1 invacuum

Single configuration

Doubleconfiguration

Simulation with gaussian MS

0


WC (baseline solution) • NA48/2

– Four larger drift chambers and one large-gap dipole magnet (MNP33/1)

– The Read out of the chambers is modern (2002)– Chambers enclosed in He by thin (0.3 %) Kevlar membrane

• NA48/3 – Add two chambers and one copy of MNP/33– Consider first tracking station operated in vacuum to

improve the angular resolution (and missing mass)– For this we are evaluating the ATLAS/COMPASS Straw

technology– Straws have been employed in high rate rare kaon decays

experiment (AGS-E871, KL→e) with rates as high as 750 KHz/wire


Can we do w/o beampipe?


WC (More elegant solution)

• Replace all WC with straws and extend the vacuum down to the CHOD (original CKM idea)

• This would allow to remove the beam-pipe, thus simplify the scheme to render hermetic the photon vetoes in the intermediate region between the LKR and SAC3 at the end of the hall

• This solution will likely reduce the number of e.m. showers generated in the beam-pipe.

• These showers may lead to a non-negligible load on the chambers and read-out


CHOD

• It is used to provide a fast trigger and (together with the gigatracker) to provide the time coincidence to associate the “right” kaon track to the pion track

• Investigating three solutions:– Scintillator tiles– Fused silica to use cherenkov light– Multi-gap glass RPC (ALICE).

• Excellent time resolution (< 50 ps) for rates up to 1 KHz/cm^2

• But in the hottest regions near the beam pipe of NA48/3, rates up to 5 KHz/cm^ have been measured further studies needed


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


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


2004 TEST OF LKR AS PHOTON VETO


LKR Hermeticity

• According to simulation we should be able to address 0 rejection inefficiency to 10-5-10-6 complementing the NA48/2 setup with:– A SAC and the end of the hole– Read out the corner of LKR which are usually not

read out• We have prepared the above for the beam

test in 2004• Since we currently we have no beam

sweeper, intensity of beam was reduced to 1/6 of NA48/2 nominal: test of hermeticity at low intensity.


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


Full LKr read-out

Installed for last weekInstalled for last week

of data taking of data taking

New instrumentedNew instrumented

LKr regions work.LKr regions work.

XLKr (cm)

YLKr (cm)


General definitions

2 2 2( / )missm GeV c

Region I

Region II

( / )P GeV c

K

0

0 Peak Region


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


LKR: Work in progress...

• Detectors:– Read-out for LKr corners work– Must understand effect of e.m. showers initiated in

ANTI and Beam pipe spilling into WC on tight one track trigger (underestimate the photon rejection)

– SAC works; must improve reconstruction– Collected several millions of unbiased →

• These data are invaluable to compare with our assumptions and to design the new experiment


MAMUD• 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

• As shown by our Fermilab CKM friends, if backgrounds from K→ remains a concern, a tracking RICH in place of the second magnetic spectrometer would completely remove it


MAMUD rough parameters (MARCELLO

LOSASSO)Total weight ≈ 150 ton

Overall Dimension 2.6 m x 2.8 m x 5.25 m (WxHxL)

Number of iron plates (2x) 150

Current ≈ 4 KA

Power ≈ 0.8 MW

Field integral on axis (from -5 m to +5 m) 6.85 T m

Magnetic field into a “good field region”

(by 10 cm x 10 cm)

≈ 1.3 T


Proposed Dipole configuration

Pole gap is 11 cm V x 30 cm H

Coils cross section 15cm x 25cm


Main results of simulation

Magnetic field at z=0 m

Field integral on axe


NA48/3 Organisational Matters


Time Schedule• 2004

– Launch GIGATRACKER R&D– Vacuum tests– Evaluate straw tracker– Start realistic cost estimation– Complete analysis of beam-test data

• 2005– Complete of the above– Complete Specifications– 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

• The working group has now becoming a proto-collaboration seeking the qualified participation of new collaborators


*Breaking News*

• John Dainton, CERN SPSC Chairman, released this morning the conclusions of the “Villars” meeting on the Future of Fixed Target Programme at CERN during a CERN Particle Physics Seminar

• The SPSC supports our R&D and looks forward to receive the Proposal


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

• K0L→ 0eeand K0

L→ 0(NA48/4)

• K0L → 0 (NA48/5)


0++, 2++

Direct CPV

Indirect CPV

CPC

K0L→0ee and K0

L→0

Study Direct CP-Violation

•Indirect CP-Violating Contribution has been measured (NA48/1, see next slide)•Constructive Interference (theory)•CP-Conserving Contributions are negligible


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)

La Thuile, Moriond 2004


NA48/1 NA48/1


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


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


Comparing Apples with ApplesNA48/3 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


Optics drawing :


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


Detector Layout


0 20 40 60 80 1000

10

20

30

40

50

Pro

duct

ion

rati

o

Kaon momentum (GeV/c)

Ratio of K+ production at 400 and 120 GeV/c

By LAU GATIGNONCERN/AB

0 vetoing is easierfor high energy kaons, it pays off to go to highest proton energy!!

The CERN-SPS is the best machine


ALICE PIXEL IN NA48 BEAM

Giorgio StefaniniFadmar OsmicDOCT

Petra Riedler Alex Kluge Michel MorelMike BurnsPeter Chochula

ALICE pixel team members helping with the preparations and the test:


Reconstruction of K+ and K- beam spots

Beam spot size from K ∼ 7 cm2

Total Rate from π K ∼ 20 MHz

NA48/2

KABES IN NA48/2


Time resolution

0.6 ns

Position and time resolutions

Tagged K track

Space resolution from drift time measurement:

70 μm

Time resolution: 0.6 ns

Using TOT to correct time slewing

Tagging with reconstructed K± ± + -

(T0)KABES- (T0)DCH Spectrometer (ns)

XStation 1 or 2 - XStation 3 (cm)

NA48/2KABES IN NA48/2


Kaon Rare Decays and the SMC

P-V

iola

tio

n

(holy grail)

CP-Conservation

Kaons provide quantitative tests of SM independentfrom B mesons

NA48/3

|Vtd|NA48/4

NA48/5


Photon Vetoes (KAMI)


Trigger• INPUT: 10 MHz DC; The single rate particle is dominated by muons

from Kaon decays!! 2/3 of decays have 1 moun in filan state• Important to reduce rate using simple cuts to avoid correlations• MAMUD and ANTI used as a veto should reduce the rate to 2.5 MHz• LKR bidimensional pipelined trigger to count photons can be

envisaged now (follow LHC experience)• LKR will reduce rate to 1 MHz• Further suppression based on multiplicity in DCH, SAC, CHV • At this stage the rate will be sufficiently reduced to allow a processor-

based system to analyse the WC tracking information applying mild cuts on the missing mass ( 100 KZH?)

• High Level Trigger handled in PCFARM (cf. LHCB 1MHz level 1…)• ½ band-width reserved for down-scaled triggers• Others triggers to collect less rare but still very interesting kaon

decays


SPIBES• Si Sensor

– Wafers of thickness < 150 micron can be obtained but bump-bonding yield needs to be investigated

– Experience gained by LHC experiments very valuable– To achieve 100 ps time resolution 90% of the charge from the

sensor has to be collected in ~1ns • Pixel chip (Mixed-signal ASIC)

– Very fast preamp and shaper– Very low time walk discriminator– High Resolution TDC

• Front-end hybrid– Additional functionality is needed for clock, trigger distribution,

data multiplexing and transmission, and controls– This requires one or more ASICs in the immediate vicinity of the

pixel chip– For this design, to minimise thickness it is desirable to have

power, data buses and the front-end hybrid functionality at the periphery of the detector plane


SPIBES

• Silicon micro-pixel good candidate to achieve required time resolution– Capacitance of single pixel ~ 100 fF– Rise time requirement < 2 ns – Must be demonstrated in R&D phase

• The complexity of the analog/digital design with on-chip TDC capability will most likely require the use of 0.13 micron CMOS technology

• Hybrid Pixel Technology– Pixel chip bump-bonded on Si sensor– State-of-the-art: ALICE SPD 150 micron chip on 200 micron

sensor– Further reduction of material needs investigation


0++, 2++

Direct CPV

Indirect CPV

CPC

K0L→0ee and K0

L→0

Study Direct CP-Violation

•Indirect CP-Violating Contribution has been measured (NA48/1, see next slide)•Constructive Interference (theory)•CP-Conserving Contributions are negligible


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)


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)

La Thuile, Moriond 2004


NA48/1 NA48/1


Isidori, Unterdorfer,Smith:

Fleisher et al:

Ratios of B → modes could be explained by enhanced electroweak penguins

and enhance the BR’s:

* A. J. Buras, R. Fleischer, S. Recksiegel, F. Schwab, hep-ph/0402112

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 New Physics


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


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)


Estimation of the Radiation Effects for Future NA48

VERY PRELIMINARY! Fluence:

Assuming 5000 spills/day, 50MHz particles/cm2/spill and a spill length of 4.8s:

1.2E12 particles/cm2 per day

Assuming pion beam:eq= …hardness factor (9GeV pions:3.6, flat dist.)eq=4.32E12 (1 MeV neutrons)/cm2 per day

Assuming 100 days of running:eq= 4.32E14 (1 MeV neutrons)/cm2 per

run

>> Leakage current, depletion voltage, signal, operating conditions,….

Dose: 4.32E14/(6.24E9/(1.66 MeV g-1 cm2))=114kGy= 12 Mrad

Need an accurate investigationNeed an accurate investigation !


Comparison with TDC

TDCFADC

• Leading time distribution


FADC data (3)

• Pulse height distribution

– Threshold ~37 ADC counts


Data without Zero-supp (baseline)

• Baseline:– Mean: 20.2– R.m.s.: 2.4


Unexpected very big pulses (1)

• ADC count 255 = 400 mV

• width of this pulse:

~450 ns



occupies the wholeFADC R/O time window!



• Fraction of “big” pulses (>200 ADC counts) over “normal” pulses (<200 ADC counts) as a funcion of beam intensity

october 7, 2004a. ceccucci/ cern1 future of rare kaon decays at the cern-sps fermilab, october 7,...

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