LIFETIME MEASUREMENT OF AND ATOMS TO TEST LOW ENERGY QCD Addendum to the DIRAC Proposal. L. Nemenov 27 April 2004. CERN-SPSC-2004-009 SPSC-P-284 Add. 4 12 April, 2004. EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH. - PowerPoint PPT Presentation
EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH CERN Geneva, Switzerland Czech Technical University Prague, Czech Republic Institute of Physics ASCR Prague, Czech Republic Ioannina University, Greece INFN - Laboratori Nazionali di Frascati Frascati, Italy Trieste University and INFN-Trieste Italy KEK Tsukuba, Japan Kyoto Sangyou University Japan UOEH-Kyushu Japan Tokyo Metropolitan University Japan National Institute for Physics and Nuclear Engineering IFIN-HH Bucharest, Romania JINR Dubna, Russia Skobeltsyn Institute for Nuclear Physics of Moscow State University Moscow, Russia IHEP Protvino, Russia CERN-SPSC-2004- 009 SPSC-P-284 Add. 4 12 April, 2004 L. Nemenov 27 April 2004 LIFETIME MEASUREMENT OF AND ATOMS TO TEST LOW ENERGY QCD Addendum to the DIRAC Proposal K
Transcript
EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH
CERN Geneva, Switzerland
Czech Technical University Prague, Czech Republic
Institute of Physics ASCR Prague, Czech RepublicIoannina University, Greece
INFN - Laboratori Nazionali di Frascati Frascati, Italy
Trieste University and INFN-Trieste Italy
KEK Tsukuba, Japan
Kyoto Sangyou University Japan
UOEH-Kyushu JapanTokyo Metropolitan University Japan
National Institute for Physics and Nuclear Engineering IFIN-HH Bucharest, Romania
JINR Dubna, Russia
Skobeltsyn Institute for Nuclear Physics of Moscow State University Moscow, Russia
IHEP Protvino, Russia
Santiago de Compostela University Spain
Basel University Switzerland
Bern University Switzerland
75 Physicists from 17 Institutes
CERN-SPSC-2004-009SPSC-P-284 Add. 412 April, 2004
L. Nemenov 27 April 2004
LIFETIME MEASUREMENT OF AND ATOMS TO TEST LOW ENERGY QCD
Addendum to the DIRAC Proposal
K
The proposed experiment is the further development of the
current DIRAC experiment at CERN PS. It aims to measure
simultaneously the lifetime of + - atoms (A2), to observe K
atoms (A K) and to measure their lifetime using 24 GeV proton
beam PS CERN and the upgraded DIRAC setup.
The precision of A2 lifetime measurement will be better than 6%
and the difference |a0 - a2| will be determined within 3% or
better.
The accuracy of A K lifetime measurement will be at the level of
20% and the difference |a1/2-a3/2| will be estimated at the level of
10%.
The pion-pion and pion-kaon scattering lengths have never been
verified by experimental data with the sufficient accuracy. For
this reason the proposed measurements will be a crucial check of
the low energy QCD predictions and our understanding of the
nature of the QCD vacuum.
The observation of the long-lived (metastable) A2 states is also
considered with the same setup. This will allow us to measure
the energy difference between ns and np states and to determine
the value of 2a0+a2 in a model-independent way.
L. Nemenov 27 April 2004
perturbative QCD: LQCD (q,g)
interaction „weak“(asympt. freedom):expansion in coupling
Check only Lsym
chiral sym. & break: Leff (GB: ,K,)
interaction „strong“(confinement) - but: expansion in energy
Check Lsym as well as Lbreak-sym
q-condensate
QFD
QCD
QED
Standard Model
Q>> Q<<
LOW energy(large distance)
HIGH energy(small distance)
L. Nemenov 27 April 2004
ChPT predicts s-wave scattering lengths:
0
2
0 2
0.220 0.005(2.3%)
0.0444 0.0010(2.3%)
0.265 0.004(1.5%)
a
a
a a
Chiral expansion of the mass:
M2 mu md B mu md B 2 l 3
32 2F 2O (mu md )3 (1)
2where | 0 | | 0 | is t hereflecting a prop
,.erty of the
quark condensateQCD vacu
uu
BF um
M mu md 0 u u 0 F2
0 2 3
0 3(BNL)
e.g.: 0.260 3% 1 11 or 1.00 / 1.06
E865: 0.216 6% 12 or .98 / 1.06
a a l M M
a l M M
scatteringscattering
3SchPT 0 5l
(1)
3Measurement of estimate of | 0 | | 0 |:u dl m m uu
L. Nemenov 27 April 2004
A2* is a metastable atom
small angle
π πE E
+
Externalbeam
p
For pA = 5.6 GeV/c and = 20 1s = 2.9 × 10 15 s , 1s = 1.7 × 10 3 cm
2s = 2.3 × 10 14 s , 2s = 1.4 × 10 2 cm
2p = 1.17 × 10 11 s , 2p = 7 cm
3p 43 cm
4p 170 cm
L. Nemenov 27 April 2004
TargetZ
Thickness Μm
Br Σ(l ≥1)
2p0 3p0 4p0 Σ(l =1, m = 0)
04 100 4.45% 5.86% 1.05% 0.46% 0.15% 1.90%
06 50 5.00% 6.92% 1.46% 0.51% 0.16% 2.52%
13 20 5.28% 7.84% 1.75% 0.57% 0.18% 2.63%
28 5 9.42% 9.69% 2.40% 0.58% 0.18% 3.29%
78 2 18.8% 10.5% 2.70% 0.54% 0.16% 3.53%
Probabilities of the A2π breakup (Br) and yields of the long-lived states for different targets provided the maximum yield of
summed population of the long-lived states: Σ(l ≥1)
L. Nemenov 27 April 2004
4( )e eK e K
Rosselet et al. CERN, 1977
0 0.216 0.013 (stat)0.004 (sys) 0.002 (th),
a
Pislak et al. E865/BNL,2001/03
0 0.26 0.05,a 1) using Roy eq.
2a)0
2
0.203 0.0330.055 0.023
aa
0 1 2 20 1
measurement of the phase difference (s) (s)- (s) for 4 KM s M
2c)
2b)
using Roy eq. & 2 ChPT 0( )a f a
same method as in 2b:
0
0
0.221 0.026(at 95% CL)cp. 0.220 0.005(2 loop)a
a
Colangelo, Gasser, Leutwyler, 2001
33
322 2
16 and therefore
64u d u d
ll
M m m B m m BF
> 94%
L. Nemenov 27 April 2004
I. ChPT predicts s-wave scattering lengths:
( 2 ) ( 4 )
1/ 2 3/ 20 00.19 0.2 0.05 0.0
1
2
,L L
a a
and loop
KK scattering scattering
1/ 2 3/ 20 0 0.23 0.01 a a
( 2 ) ( 4 ) ( 6), , 2 -L L L and loop
1/ 2 3/ 20 0 0.269 0.015 a a
V. Bernard, N. Kaiser, U. Meissner. – 1991
J. Bijnens, P. Talaver. – April 2004
A. Rossel. – 1999
II. Roy-Steiner equations:
III. AK lifetime:0 0 0 0
0 0 1/ 2 3/ 2 20 0
15(3.7
( )
( ) ~ | prec
0.4)
issio
1
~ %
0
n 1|
K K
A K A K
K a a
s
J. Schweizer. – 2004
L. Nemenov 27 April 2004
In the 60’s and 70’s set of experiments were performed to measure πK scattering amplitudes. Most of them were done studying the scattering of kaons on protons or neutrons, andlater also on deuterons. The kaon beams used in these experiments had energies ranging from 2 to 13 GeV. The main idea of those experiments was to determine the contribution of the One Pion Exchange (OPE) mechanism. This allows to obtain the πK scattering amplitude. Analysis of experiments gave the phases of πK-scattering in the region of 0.7 ≤ m(πK) ≤ 2.5 GeV. The most reliable data on the phases belong to the region 1 ≤ m(πK) ≤ 2.5 GeV.
KK scattering, scattering, experimental resultsexperimental results
The measurement of s-wave πK scattering length would test our understanding of chiral SU(3)L SU(3)R symmetry breaking of QCD (u, d and s), while the measurement of ππ scattering length checks only SU(2)L SU(2)R symmetry breaking (u, d).
This is the main difference between ππ and πK scattering!
What new will be What new will be known ifknown if KK
scattering length will scattering length will be measured?be measured?
Schematic top view of the DIRAC spectrometer. Upstream of the magnet: microstrip gas chambers (MSGC), scintillating fiber detectors (SFD), ionization hodoscopes (IH) and shielding of iron.
Downstream of the magnet, in each spectrometer arm: drift chambers (DC) , vertical and horizontal scintillation hodoscopes (VH, HH), gas Cherenkov counter (Ch), preshower detector (PSh) and, behind the iron absorber, muon detector (Mu).
L. Nemenov 27 April 2004
Schematic top view of the updated DIRAC spectrometer.
Upstream of the spectrometer magnet: microdrift chambers (MDC) , scintillating fiber detectors (SFD) , ionization hodoscopes (IH).
Downstream of the magnet, in each spectrometer arm: drift chambers (DC), vertical and horizontal scintillation hodoscopes (VH, HH), gas Cherenkov counters (Ch), preshower detector (PSh) and, behind the iron absorber, muon detector (Mu).
In the left arm: Aerogel Cherenkov counters.
L. Nemenov 27 April 2004
present shielding
new shielding
L. Nemenov 27 April 2004
Size of sensitive area: 5050 mm2
SciFi used: KURARAY SCSF-78, 0.28 mm ø.
Number of SciFi layers/bundle: 7
Thickness of the bundles: 3 mm ( 1% X0)
Fiber pitch: 0.205 mm
Number of channels: 240(X) + 240(Y)
Number of PSPM(H6568): 15(X) + 15(Y)
L. Nemenov 27 April 2004
Yield of +, K+ and p at the proton energy of 24 GeV/c, in arbitrary units
(T.Eichten and D.Haidt Nucl. Phys. B44 (1972) 333)
Target θ, mrd GeV/c + K + p /K+ p/K+
Cu 87 4 52.9 6.25 24.8 8.5 4.0
Cu 87 6 18.6 2.82 20.2 6.6 7.2
Cu 127 4 27.8 4.02 17.9 6.9 4.5
Cu 127 6 6.38 1.20 9.30 5.3 7.7
L. Nemenov 27 April 2004
2
7.(
)4
)
(%
K K
N A A
N A
Atoms Yields11.0·10 -10
0.52·10 -10
0.29·10 -10
0.81·10 -10
Table 1: Yields of detected A and A K
(NA per one p-Ni interaction).
Yield of A K for the reaction p + Ni→A K + X (left figure for -K+ and right for
+K-) at the proton energy Ep=24 GeV as a function of the atom momentum. Yellow histogram shows A K emitted into the angular aperture of the secondary channel. Green histogram refers to the atoms detected by the DIRAC setup.
Yield of A2 in the upgraded setup for the reaction p + Ni→ A2 + X at the proton energy Ep=24 GeV as a function of the atom momentum. Yellow histogram shows A2 emitted into the angular aperture of the secondary channel. Green histogram refers to atoms detected by the DIRAC setup.
2A
KA
KA
KK
AA
L. Nemenov 27 April 2004
Trajectories of Trajectories of -- and and K K ++
from the from the AAKK break up break up
The numbers to the right of the tracks lines are the -
and K+ momenta in GeV/c.
The A K, - and K+ momenta are shown in the table in
the upper left corner.
L. Nemenov 27 April 2004
Side view of the target station and the new shielding 1. The target station, the shielding and the rectangle vacuum tubes (initial part of the secondary particle channel and part of the proton tube) are cut along the proton beam. The secondary beam and a collimator for the secondary beam are shown. The small permanent magnet is visible in vacuum between the target station and shielding.
L. Nemenov 27 April 2004
1. Single–multilayer targets decrease the systematic errors.
2. Identification of e±, ±, K ± and p3. Increasing of statistics and efficiency of the setup
Shielding K ≈ 1.9 Formation of time structure of the spill with the
trigger of setup
Microdrift chambers
New electronics for SFD
Increase in the aperture on VH hodoscope and PSH Total K ≈ 4
L. Nemenov 27 April 2004
Cost estimation for Cost estimation for AA22 and and AAKK experiment experiment
Setup upgradingVacuum channel and shielding: 20 kCHFMicro Drift Chambers: 18 kCHFElectronics for SFD (960 channels): 210 kCHFDrift Chambers: 30 kCHFElectronics for VH (72 channels): 20 kCHFScintillation counters (8 counters): 20 kCHFAerogel detectors(2 detectors): 48 kCHFUpgrade of the existing Cherenkov counters: 20 kCHFGas Cherenkov counters with heavy gas(2 counters): 52 kCHFPreshower detector: 30 kCHFTrigger and Readout system: 100 kCHF_______________________________________________Overall cost of the setup upgrading: 568 kCHF
It is 16% from the cost of the existing DIRAC setup
Cost of the existing DIRAC setupSetup: 3.5 MCHFElectronics rented from CERN pool: 0.4 MCHF
3.9 MCHF
L. Nemenov 27 April 2004
Microdrift Chambers with readout electronics JINR Dubna, Bazel; Scintillating Fiber Detector Japanese group, INFN–Trieste, IHEP Protvino; Ionization Hodoscope IHEP Protvino; Drift Chambers with readout electronics JINR Dubna; Vertical Hodoscope Santiago de Compostela University; Horizontal Hodoscope IHEP Protvino; Preshower Detector IFIN–HH Bucharest; Cherenkov Counters INFN Frascati Muon Counters IHEP Protvino; Trigger and DAQ JINR Dubna with the support of the collaboration.
L. Nemenov 27 April 2004
Manufacture of all new detectors and electronics: 18 months
Installation of new detectors: 3
months
2006Upgraded setup test and calibration: 4 monthsObservation A2 in the long-lived states.
2007 and 2008Measurement of A2 lifetime: 10 months
In this time 66000 atomic pairs will be collected to
estimate A2 lifetime with precision of:
In the same time we also plan to observe AK and to detect 5000 K atomic pairs to estimate AK lifetime with precision of:
This estimation of the beam time is based on the A2
statistics collected in 2001-2003 and on the assumptionof having 2.5 spills per supercycle during 20hours per day.
Time scale for the Time scale for the AA22 and and AAKK experimentexperiment
0 2
0 2
( )6%, 3%
a a
a a
1/ 2 3/ 2
1/ 2 3/ 2
( )20%, 10%
a a
a a
L. Nemenov 27 April 2004
(2001) G. Colangelo, J. Gasser and H. Leutwyler E2 ≈ 0.56 eV
L. Nemenov 27 April 2004
Energy Splitting between Energy Splitting between npnp – – nsns states in ( states in ( ++ - - ) atom ) atom
