Transcript Study of Rare Kaon Decays at the CERN-SPS Villars, 27 September, 2004 A.

Study of Rare Kaon Decays at
the CERN-SPS
Villars, 27 September, 2004
A. Ceccucci for the
NA48-Future Working Group
September 27, 2004
A. Ceccucci/ CERN
Villars
1
“CERN Director General Outlines Sevenpoint 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 sevenpoint 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.
………
……….
September 27, 2004
A. Ceccucci/ CERN
Villars
2
NA48-Future Working Group
CERN-SPSC-2004-010
SPSC-EOI-002
• We identified the Rare Kaon Decays as the next
logical step of the Kaon Programme at CERN
• Short term (2004-2010):
NA48/3 K+ → p+
nn
**LETTER OF INTENT**
• Longer term (>2010):
– Assuming a new or refurbished SPS capable to deliver higher
intensity/energy as the ultimate injector for LHC
0 ee (
NA48/4 KL
)
0
NA48/5 KL
→p
mm
→p nn
September 27, 2004
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Villars
3
CP-Violation
Kaon Rare Decays and the SM
NA48/3
NA48/5
(holy grail)
|Vtd|
NA48/4
CP-Conservation
Kaons provide
quantitative tests
of SM independent
from B mesons
September 27, 2004
The Physics case was reviewed by G. Isidori
The state-of-the-art was reviewed by L. Littenberg
A. Ceccucci/ CERN
Villars
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Letter of Intent to Measure the Rare
Decay K+ → p+ n n 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
September 27, 2004
A. Ceccucci/ CERN
Villars
person
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Main K+ decay modes
competing with K+→p+ nn
Decay
m+n
p+p0
p+p+pp+p0p0
p0m+n
p0e+n
BR
63 %
21 %
6%
2%
3 % (called K+m3)
5 % (called K+e3)
Suppression:
m PID, kinematics
g veto, kinematics
CHV, kinematics
g veto, kinematics
g veto, m PID
g veto, E/P
BR(K+→p+ nn)~10-10 !!
September 27, 2004
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Villars
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Framework
• So far K+→p+
nn
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+→ p+p0 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
September 27, 2004
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Villars
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Kinematics
PK  75 GeV / c
K +  p +nn
K +  m +n
Region I
K +  p +p 0
K +  p +p +p -
September 27, 2004
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Acceptance
Region I
14  Pp (GeV / c)
14  Pp (GeV / c)  40
14  Pp (GeV / c)  30
75 GeV/c
2
0.026  mmiss
 0.068 (GeV / c2 )2
Acceptance
Acceptance
2
0  mmiss
 0.01 (GeV / c2 )2
Region II
PK (GeV / c)
PK (GeV / c)
PK  75 GeV / c Pp  40 GeV / c
Acceptance (Region I+II) ~ 0%
September 27, 2004
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THE BEAM
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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
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Villars
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Choice of pk=75 GeV/c
Pk (GeV/c
K+ flux @ production
( 3 1012 400 GeV/c protons)
x108
K+ survival over 102 m
60
75
90
120
1.1
1.3 (meas)
1.5
1.9
2.4
2.3 (meas)
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 incorporating
stages 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
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Layout of the Beam
• SPS North Area High Intensity Facility
– TCC8 tunnel + ECN3 cavern (where NA48 is installed)
• Modified K12 beam line (102 m long)
– Achromatic design (no net bend)
– Triplet of radiation hard quadrupoles to capture large solid
angle
– Front-end achromat:
• Four radiation hard dipoles
• Narrow momentum bite Dpk/pk~1% RMS
– Parallel section to house a He filled CEDAR
– Final quadrupoles to make beam slightly converging
– Second achromat to allow for redundant momentum
measurement
• Optics calculated using the TRANSPORT programme
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NA48/3: Beam Layout
Dipoles
Dipoles
Beam-line
102 m long
September 27, 2004
about 17%
K+ lost
A. Ceccucci/ CERN Villars
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Decay Tank
• ~100 m long decay tank closed by thin Kevlar
window
• A 160 mm diametre beam pipe traverses the
principal detectors to allow the beam to be
transported in vacuum
• Double magnetic spectrometer, achromatic design,
with two large gap dipoles to provide horizontal
deflections of -2.1 and +3.5 mrad for 75 GeV/c beam
– Charged particles of all momenta are centered on the beam
axis again downstream of the e.m. calorimeter
• A magnetised hadron calorimeter provides a +18
mrad deflection, displacing the charged beam 160
mm 8 m further downstream to clear a 100 mm
radius photon veto at the end of the hall
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Villars
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NA48/3: Beam Across Tank
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Already
Available
New high-intensity K+ beam for NA48/3
Beam:
SPS protons per pulse on T10
Duty cycle (s./s.)
Present K12
(NA48/2)
New HI K+
> 2006
Factor
wrt 2004
1 x 1012
3 x 1012
3.0
4.8 / 16.8
Solid angle (msterad)
1.0
 0.40
 16
40
Av. K+momentum <pK> (GeV/c)
60
75
Total : 1.35
Mom. band RMS: (Dp/p in %)
4
1
~0.25
Area at Gigatracker (cm2)
 7.0
 20
 2.8
5.5
250
~45 (~27)
18
2.5
800
40
~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
Total beam per pulse (x 107)
per Effective spill length (MHz)
/ … / cm2 (KABES)
September 27, 2004
(MHz)
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Villars
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1HISTOGRAM NO 21
DISTRIBUTION OF
P IN GEVC
0
INTERVAL
0LESS THAN
72.000
0
102.000 M
FROM THE TARGET
SCALE FACTOR.. 100 X'S EQUAL
5637 ENTRIES
TURTLE SIMULATION
MOMENTUM DISTRIBUTION
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
0
0GREATER THAN 78.000
0
0
TOTAL NUMBER OF ENTRIES =
51031
INCLUDING OVERFLOW AND UNDERFLOW
0
MEAN = 74.981
RMS HALF WIDTH =
0.710
0HISTOGRAM NO 21
DISTRIBUTION OF
P IN GEVC
102.000 M
FROM THE TARGET
<p> = 74.981 GeV/c, RMS = 0.710 GeV/c
September 27, 2004
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Villars
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-60.000
-20.000
20.000
60.000 TOTALS
-60.000
-20.000
20.000
60.000 TOTALS
I**---**---**---**---**---**---**I-------I**---**---**---**---**---**---**I--------60.000 I
I
0
-60.000 I
I
0
-54.000 I
I
0
-54.000 I
I
0
-48.000 I
I
0
-48.000 I
I
0
-42.000 I
I
0
-42.000 I
I
0
-36.000 I
I
0
-36.000 I
I
0
-30.000 I
I
0
-30.000 I
I
0
-24.000 I
2AQ$$$$$$OF1
I
397
-24.000 I
8T$$$$$$$$$A
I
932
-18.000 I
A$$$$$$$$$$$$A
I
5407
-18.000 I
$$$$$$$$$$$$
I
4016
-12.000 I
Z$$$$$$$$$$$$Z
I
8326
-12.000 I
1$$$$$$$$$$$$4
I
8053
-6.000 I
$$$$$$$$$$$$$$
I
9999
-6.000 I
2$$$$$$$$$$$$2
I
9999
0.000 I
$$$$$$$$$$$$$$
I
9999
0.000 I
3$$$$$$$$$$$$2
I
9999
6.000 I
W$$$$$$$$$$$$W
I
8536
6.000 I
$$$$$$$$$$$$
I
8186
12.000 I
4$$$$$$$$$$$$G
I
5529
12.000 I
$$$$$$$$$$$$2
I
4102
18.000 I
2GS$$$$$$$F2
I
396
18.000 I
3Q$$$$$$$$T2
I
787
24.000 I
I
0
24.000 I
I
0
30.000 I
I
0
30.000 I
I
0
36.000 I
I
0
36.000 I
I
0
42.000 I
I
0
42.000 I
I
0
48.000 I
I
0
48.000 I
I
0
-60.000
-20.000
20.000
60.000 TOTALS
54.000 I
I
0
54.000 I
I
0
I**---**---**---**---**---**---**I-------I**---**---**---**---**---**---**I---------60.000 I
I**---**---**---**---**---**---**I-------I
0
I
I
I
I
-54.000 I
I
0
I
134455554431
I
I
2456666542
I
-48.000 I
I
0
I
15428485392461
I
I
631337614046
I
-42.000 I
I
0
I
59077738177357
I
I
7435062357861
I
-36.000 I
I
0
TOTALS I 000000007855957371007700000000 I
9999 -30.000 I
TOTALS
I
000000006682187334832000000000
I
9999
I
0
BEAM TRANSVERE
SIZE
SPIBES2
TOTAL NUMBER OF ENTRIES =
51031
SPIBES1
Y [mm]
X [mm]
-24.000
-18.000
-12.000
-6.000
0.000
6.000
12.000
18.000
24.000
30.000
36.000
42.000
48.000
54.000
I
4H$$$$$$$$K5
I
603
I
3$$$$$$$$$$$$
I
5010
I
H$$$$$$$$$$$$K
I
8414
I
H$$$$$$$$$$$$H
I
9999
I
L$$$$$$$$$$$$H
I
9999
I
A$$$$$$$$$$$$E
I
8483
I
$$$$$$$$$$$$6
I
5058
I
4L$$$$$$$$H3
I
590
I
I
0
I
I
0
I
I
0
I
I
0
I
I
0
I
I
0
I**---**---**---**---**---**---**I-------I
I
I
134456555431
I
I
213971951312
I
I
61257420138277
I
TOTALS I 000000008999158636733400000000 I
9999
TOTAL NUMBER OF ENTRIES =
September 27, 2004
A. Ceccucci/ CERN
TOTAL NUMBER OF ENTRIES =
51031
FTPC (KABES)
51031
Villars
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Spot at Wire Chamber 6:
1HISTOGRAM NO 29
HORIZONTAL AXIS
VERTICAL AXIS
0
X IN MM
Y IN MM
-60.000
+
-60.000
-54.000
-48.000
-42.000
-36.000
-30.000
-24.000
-18.000
-12.000
-6.000
0.000
6.000
12.000
18.000
24.000
30.000
36.000
42.000
48.000
54.000
Y [mm]
X [mm]
0
0
-20.000
20.000
FROM THE TARGET
FROM THE TARGET
60.000
TOTALS
I**---**---**---**---**---**---**I-------TO -54.000 I
I
0
TO -48.000 I
I
0
TO -42.000 I
I
0
TO -36.000 I
I
0
TO -30.000 I
2321 11
I
10
TO -24.000 I
159XT$$$$SJE73
I
334
TO -18.000 I
8$$$$$$$$$$$U72
I
1947
TO -12.000 I
1E$$$$$$$$$$$$D
I
4900
TO -6.000 I
G$$$$$$$$$$$$J1
I
8143
TO
0.000 I
1L$$$$$$$$$$$$I2
I
9999
TO
6.000 I
G$$$$$$$$$$$$82
I
9984
TO 12.000 I
G$$$$$$$$$$$$E1
I
8252
TO 18.000 I
F$$$$$$$$$$$$E1
I
4901
TO 24.000 I
AV$$$$$$$$$$X7
I
1929
TO 30.000 I
2ERYVWQSPFF5
I
254
TO 36.000 I
21
1 1
I
5
TO 42.000 I
I
0
TO 48.000 I
I
0
TO 54.000 I
I
0
TO 60.000 I
I
0
I**---**---**---**---**---**---**I-------I
I
I
1356776531
I
I
15731887723651
I
I
16166042762880
I
TOTALS I 000000027056033304565390000000 I
9999
TOTAL NUMBER OF ENTRIES =
51031 INCLUDING UNDERFLOW AND OVERFLOW AS FOLLOWS
UNDERFLOW
OVERFLOW
ACROSS
0
0
DOWN
0
0
0HISTOGRAM NO 29
HORIZONTAL AXIS
VERTICAL AXIS
September 27, 2004
204.858 M
204.858 M
X IN MM
Y IN MM
A. Ceccucci/ CERN
204.858 M
204.858 M
Villars
FROM THE TARGET
FROM THE TARGET
20
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
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DETECTORS
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Villars
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NA48/3 Detector Layout
10 MHz Kaon
decays
800 MHz
(p/K/p)
Only the upstream detectors see
the 800 MHz beam
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Villars
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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
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Villars
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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+→p+ nn.
• 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
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Villars
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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 DP/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
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Villars
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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
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CEDAR
D
D

K/p
m12 - m22


2 p2
Cedar-W
Cedar-N
p (GeV / c )
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Villars
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GIGATRACKER
• Specifications:
–
–
–
–
–
Momentum resolution to ~ 0.5 %
Angular resolution ~ 10 mrad
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
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FTPC
SPIBES2
SPIBES1
GIGATRACKER
♠ 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)
6.25
12.45 m
September 27, 2004
♠ 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.
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Martini
30
Proposal for SPIBES
Beam square shape
5x5 cm2
5 cm
300 x 100 µm pixel cell
September 27, 2004
•
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)
80000 pixels in total to cover the beam
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Martini
31
SPIBES: Time scale & Resources
• A Preliminary time scale has been established based
on the experience gained in other silicon pixel
detector projects
• The baseline technologies are those already adopted
in the most advanced current designs further
extended (0.13 micron technology for the pixel chip
probably needed)
• Novel solutions may have to be worked out for the
hybrid and cooling
• Preliminary work should start without delay
• Front-end ASIC will require contribution of several
expert designers for a period of two or three years.
• Good definition of the DAQ environment is needed to
develop a matching back-end readout and
calibration system
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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
September 27, 2004
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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=15V
Vop=50V
Sensor
8192 pixels
Produced 2003, tested in
ALICE p-TB 2003
September 27, 2004
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Chip
Villars
34
MULTIPLICITY (200 nsec
gate)
I0
I0/4
<mult> = 1.1
<mult> = 1.3
14xI0
4xI0
<mult> = 7.8
<mult> = 3.1
September 27, 2004
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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
September 27, 2004
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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
September 27, 2004
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KABES principle: TPC + micromegas
Edrift
Tdrift2
Micromegas
Gap 50 μm
Micromegas
Gap 50 μm
Operated @ Edrift=0.83kV/cm
Tdrift1
Tdrift1 + Tdrift2 = 750ns
Edrift
September 27, 2004
48 strips with 0.8 mm pitch
A. Ceccucci/ CERN
Very low discharge probability
38
Villars
NA48/2
KABES IN NA48/2
Position and time resolutions
Space resolution from drift
time measurement: 70 μm
Time resolution: 0.6 ns
Using TOT to correct time slewing
Tagged K track
Time resolution
0.6 ns
(T0)KABES- (T0)DCH
Spectrometer
(ns)
Tagging with reconstructed K±  p± p+ p
September 27, 2004
A. Ceccucci/ CERN
-
XStation 1 or 2 - XStation 3 (cm)
Villars
39
TEST OF KABES IN 2004
LOW INTENSITY
September 27, 2004
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KABES 25 micron amplification gap
Recent lab test with 25 mm gap
Width ~30 ns
Width ~18 ns
50 mm gap
25 mm gap
improvement of occupancy observed with 25mm amplification gap
September 27, 2004
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BEAM DATA: 50/25μ mesh
2003/2004
Time over Threshold (ns)
September 27, 2004
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2004 KABES TEST HIGH INTENSITY
FLUX PER UNIT AREA CLOSE TO NA48/3 !
September 27, 2004
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TEST OF KABES with 480
MHz FADC
September 27, 2004
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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
K1
K1
K1
23
24
25
26




K2
K2
K2
K2
23
24
25
26
FADC
FADC
FADC
FADC




16
14
12
10
FADC
FADC
FADC
FADC
K1
6
4
2
18
September 27, 2004
K2
K5
K3
K6
K4
A. Ceccucci/ CERN
Villars
K5
K5
K5
K5
K5
23
24
25
26
27





FADC
FADC
FADC
FADC
FADC
1
8
3
5
7
K6
K6
K6
K6
K6
23
24
25
26
27





FADC
FADC
FADC
FADC
FADC
9
11
13
15
17
45
Multiple pulses without
Zero-suppression
September 27, 2004
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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)
September 27, 2004
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FADC data
• Number of pulses
per channel as a
function of beam
intensity
x1
x3
x7
x12
– noisy channels
10,12,14,16 all
connected to K1
September 27, 2004
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Multiple pulses with Zero-supp
• Some data from RUN
16964 (14xI0)
• horizontal scale:
FADC time units
(2×1.04 ns)
September 27, 2004
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49
Attempt to fit single pulses
• fit of 500 FADC pulses
from the low intensity
RUN (16916)
• 4 parameters function
used:
P1  1 + P4 t - P2  e

t - P2 2
2 P3 2
• uncertainty of 1.7
counts per FADC
value
September 27, 2004
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Attempt to fit multiple pulses
• “hand fit” of a six
pulses event from
run 16964 (x 14 I0)
September 27, 2004
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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
September 27, 2004
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52
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
September 27, 2004
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Current NA48 ANTI
September 27, 2004
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WIRE CHAMBERS
September 27, 2004
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NA48 WC
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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 !!
September 27, 2004
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WC @ 30 x I0
September 27, 2004
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WC: Kinematical rejection
p +p 0
2
mmiss
(GeV / c2 )2
Events accepted
Region I
mn
Pp (GeV / c )
2
miss
m
 m + mp - 2( EK Ep - pK pp cos Kp )
2
K
2
Measured quantities
September 27, 2004
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Double spectrometer layout
Kevlar
Mag1
DCH2
DCH3
DCH1
Mag2
DCH4
DCH5
p+
DCH6
x
He
Vacuum
Kevlar
z
NA48 Wire chambers 0.004 X0
PTkick   211MeV / c
x
p+
Vacuum
Straw tube 0.0025 X0
September 27, 2004
He
z
NA48 Wire chambers 0.004 X0
A. Ceccucci/ CERN
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Double spectrometer
Two independent measurement of Pp
s

Single
configuration
Double
configuration
p +p 0
DCH1 in
vacuum
Simulation with gaussian MS
September 27, 2004
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61
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→me) with rates as high as 750
KHz/wire
September 27, 2004
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Can we do w/o beampipe?
September 27, 2004
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63
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
September 27, 2004
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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
September 27, 2004
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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
September 27, 2004
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NA48 Liquid Krypton Calorimeter
s(E)/E = 3.2%/E  9 % /E  0.42%
s(mgg)~1 MeV/c2 ;
s(t) ~ 300 ps
FAST: 70 ns FWHM (it can be reduced)
EXCELLENT GRABULARITY: 2  2 cm2
September 27, 2004
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67
2004 TEST OF LKR AS PHOTON
VETO
September 27, 2004
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68
LKR Hermeticity
• According to simulation we should be able to
address p0 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.
September 27, 2004
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Small angle photon veto
PbWO4 crystals (CMS)
 Dimension of crystals
2x2x23 cm3
 7 x 7 cm matrix
 ~ 25 X0
 Readout with light
guides and PMT
Installed for last week
of data taking
September 27, 2004
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Full LKr read-out
YLKr (cm)
Installed for last week
of data taking
New instrumented
LKr regions work.
XLKr (cm)
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General definitions
 Kp
mn
Region I
p0 Peak
Region
Region II
p +p 0
p +p +p -
2
mmiss
(GeV / c2 )2
September 27, 2004
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Pp (GeV / c )
Villars
72
How to measure p+p0 Rejection
p0 peak BEFORE APPLICATION
OF EXTRA CLUSTERS IN LKR
DATA
MC
AFTER APPLICATION OF
EXTRA CLUSTERS IN LKR
DATA
MC
1486 MC
678 DATA
745862 MC
212569 DATA
M2(miss) (GeV/c2)2
September 27, 2004
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M2(miss) (GeV/c2)2
Villars
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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 K+ →p+ p0
• These data are invaluable to compare
with our assumptions and to design the
new experiment
September 27, 2004
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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+→ m+ n remains a concern, a
tracking RICH in place of the second magnetic
spectrometer would completely remove it
September 27, 2004
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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
September 27, 2004
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76
Proposed Dipole configuration
Pole gap is 11 cm V x 30 cm H
Coils cross section 15cm x 25cm
September 27, 2004
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77
Main results of simulation
Field integral on axe
Magnetic field at z=0 m
September 27, 2004
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78
NA48/3
Organisational Matters
September 27, 2004
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79
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
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Tentative Indication of cost
Element
Cost (MCHF)
Comments
BEAM LINE
0.5
Modified K12 line
CEDAR
0.2
Photon Detectors
GIGATRACKER
1.4
Assuming 0.13 mm
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
SAC & CHV
0.5
Cost of iron: ~500 KCHF
TRIGGER & DAQ
TOTAL
September 27, 2004
19.0
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81
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
September 27, 2004
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Comparing Apples with Apples
NA48/3
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 / 60 m)
Acceptance (%)
10
5
Events/y (BR~10-10)
82
28
September 27, 2004
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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
September 27, 2004
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Kaons: Longer term
(i.e. More Protons Needed!)
• K0L→ p0e+e- and K0L→ p0m+m- (NA48/4)
• K0L → p0 n n (NA48/5)
September 27, 2004
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K0L→p0ee(mm) : Perspectives
•
Detector sgg ×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
–
explore the window of opportunity between current upper limit and
SM
Tot ~ ×240 → sens on BR ~ ×15 (on Im lt ~×4-15)
Ideal Kaon Application for High Intensity/High Energy Machine
September 27, 2004
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KL→p0nn @CERN?
From KAMI proposal
E391A
J-PARC
NA48/5?
SPS
CERN may become competitive if the E391A technique works
September 27, 2004
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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
September 27, 2004
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SPARES
September 27, 2004
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Optics drawing :
September 27, 2004
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Detector Layout
September 27, 2004
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Production ratio
Ratio of K+ production at 400 and 120 GeV/c
50
p0 vetoing is easier
for high energy kaons, it pays off
to go to highest proton energy!!
40
The CERN-SPS is the best machine
30
20
By
LAU GATIGNON
CERN/AB
10
0
0
September 27, 2004
20
40
60
80
Kaon momentum (GeV/c)
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100
92
ALICE PIXEL IN NA48 BEAM
ALICE pixel team members helping with the preparations and the test:
Fadmar Osmic
DOCT
Petra Riedler
September 27, 2004
Giorgio Stefanini
Mike Burns
A. Ceccucci/ CERN
Peter Chochula
Villars
Alex Kluge
Michel Morel
93
KABES IN NA48/2
NA48/2
Reconstruction
of K+ and K- beam spots
Beam spot size from K ∼ 7 cm2
Total Rate from π K ∼ 20 MHz
September 27, 2004
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Photon Vetoes (KAMI)
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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 processorbased 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
September 27, 2004
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SPIBES
• Si Sensor
– Wafers of thickness < 150 micron can be obtained but bumpbonding 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
September 27, 2004
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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 onchip 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
September 27, 2004
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K0L→p0e+e- and K0L→p0m+mStudy Direct CP-Violation
•Indirect CP-Violating Contribution
has been measured (NA48/1, see next slide) Direct CPV
•Constructive Interference (theory)
•CP-Conserving Contributions are negligible
Indirect CPV
CPC
September 27, 2004
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Villars
0++, 2++
99
0
K
S
0
→p
+
ee
and
0
K
S
0
→p
KS →p0 ee
+
mm
KS →p0 mm
NA48/1
7 events, expected back. 0.15
NA48/1
6 events, expected back. 0.22
BR(KS→p0ee)  10-9 =
5.8 +2.8-2.3(stat) ± 0.8(syst)
BR(KS→p0mm)  10-9 =
2.9 +1.4-1.2(stat) ± 0.2(syst)
|as|=1.06+0.26-0.21 (stat) ± 0.07 (syst)
PLB 576 (2003)
|as|=1.55+0.38-0.32 (stat) ± 0.05 (syst)
September 27, 2004
Villars
A. Ceccucci/ CERN
La Thuile, Moriond 2004
100
K0L→p0ee (mm): Sensitivity to New Physics
Isidori, Unterdorfer,Smith:
Br (KL  p0m+m- )
 10-12 
Fleisher et al:
Ratios of B → Kp modes
could be explained by
enhanced electroweak
penguins
and enhance the BR’s:
+1.6
-11
BeNP
+ -  9.0-1.6 10
e
+0.7
-11
BmNP

4.3

10
+ -0.7
m
Br (K L  p0e+e- )
September 27, 2004
A. Ceccucci/ CERN Villars
* A. J. Buras, R. Fleischer, S. Recksiegel, F. Schwab, hep-ph/0402112
 10-12 
101
0
K
L
→
0
p
nn
•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 p0→eeg decay
BR(K0 → p0nn) < 5.9 × 10-7 90% CL
Still far from the model independent limit:
BR(K0 → p0nn) < 4.4 × BR(K+ → p+nn) ~ 1.4 × 10-9
Grossman & Nir, PL B407 (1997)
September 27, 2004
A. Ceccucci/ CERN
Villars
102
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:
feq= kf
k…hardness factor (9GeV pions:3.6, flat dist.)
feq=4.32E12 (1 MeV neutrons)/cm2 per day
Assuming 100 days of running:
feq= 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 investigation !
September 27, 2004
A. Ceccucci/ CERN VillarsMara
Martini
103
Residual events after LKr
P (GeV / c ) rejection
p
Events with no g on
LKr and at least one
g at high angle
Events with at least
one g on LKr
Events with no g on
LKr and at least one
g at small angle
September 27, 2004
Zvertex (cm )
A. Ceccucci/ CERN
Villars
104
g Rejection with AKL
Pocket 1-7
|Thit-Ttrack+offset| < 10 ns
Pp (GeV / c )
Pp (GeV / c )
Zvertex (cm )
September 27, 2004
Zvertex (cm )
A. Ceccucci/ CERN
Villars
105
g rejection with SAC
Events with a shower reconstructed in SAC rejected
Pp (GeV / c )
Pp (GeV / c )
Zvertex (cm )
Zvertex (cm )
Fraction of surviving events: (2.8 ± 0.2) × 10-3
September 27, 2004
A. Ceccucci/ CERN
Villars
106
Residual events
Look at NUT signals (SPY)
Pp (GeV / c )
Pp (GeV / c )
Zvertex (cm )
September 27, 2004
Zvertex (cm )
A. Ceccucci/ CERN
Villars
107
Comparison with TDC
• Leading time distribution
FADC
TDC
September 27, 2004
A. Ceccucci/ CERN
Villars
108
FADC data (3)
• Pulse height
distribution
– Threshold ~37 ADC
counts
September 27, 2004
A. Ceccucci/ CERN
Villars
109
Data without Zero-supp
(baseline)
• Baseline:
September 27, 2004
A. Ceccucci/ CERN
– Mean: 20.2
Villars – R.m.s.: 2.4
110
Unexpected very big pulses (1)
• ADC count 255 = 400
mV
• width of this pulse:
~450 ns
September 27, 2004
A. Ceccucci/ CERN
Villars
111
Unexpected very big pulses (2)
occupies the whole
FADC R/O time window!
September 27, 2004
A. Ceccucci/ CERN
Villars
112
Unexpected very big pulses (3)
• Fraction of “big”
pulses (>200 ADC
counts) over
“normal” pulses
(<200 ADC
counts) as a
funcion of beam
intensity
September 27, 2004
A. Ceccucci/ CERN
Villars
113