STATUS OF THE PROJECT ANKE-COSYSTATUS OF THE PROJECT ANKE-COSY

1. Introduction2. Deuteron breakup at high momentum transfer3. Forward detector system performance4. Experimental results and discussion5. Participation in other ANKE experiments6. Conclusions

18 January 200518 January 2005

ANKE CollaborationANKE Collaboration

V. Abaev1, H.-H. Adam2, N. Amaglobeli3, S. Barsov1, U. Bechstedt5, W. Borgs5, M. Büscher5, W. Cassing6, V. Chernetsky7, V. Chernyshev7, B. Chiladze3, D. Chiladze5,3, M. Chumakov7, V. Dimitrov8, M. Drochner4, S. Dymov5,9, A. Dzuba1,5, R. Engels5, W. Erven4, P. Fedorets7, L. V. Fil kov 10, A. Gerasimov7, Ye. S. Golubeva11, V. Goryachev7, O. Grebenyuk1, K. Grigoriev1, V. Grishina11, D. Gusev9, Ch. Hanhart5, G. Hansen12, M. Hartmann5, V. Hejny5, L. Jarczyk13, A. Kacharava15, N. Kadagidze9, B. Kamys13, M. Karnadi5, V. L. Kashevarov10, I. Keshelashvili5,3, A. Khoukaz2, St. Kistryn13, V. Kleber14, F. Klehr12, H. Kleines4, H. R. Koch5, V. I. Komarov9, L. Kondratyuk7, E. S. Konobeevski11, V. Koptev1, A. Kovalov1, P. Kravchenko1, P. Kravtsov1, T. Krings5, V. Kruglov9, P. Kulessa16, A. Kulikov9,17, A. Kurbatov9, N. Lang2, N. Langenhagen8, I. Lehmann5,8, V. Leontiev9,17, H. Loevenich4, B. Lorentz5, S. Lorenz15, G. Macharashvili3,9, Y. Maeda5, R. Maier5, R. Menke2, T. Mersmann2, S. Merzliakov9, M. Mikirtychiants5, S. Mikirtychiants1, H. Müller8, A. Mussgiller5, M. Nekipelov5, R. Nellen5, V. Nelyubin1, M. Nioradze3, H. Ohm5, S. I. Potashev11, D. Prasuhn5, D. Protic5, K. Pysz16, F. Rathmann5, B. Rimarzig8, Z. Rudy13, J. Sarkady4, H. Paetz gen. Schieck14, R. Schleichert5, F. Schmidt15, H. Schneider5, H. Seyfarth5, A. Sibirtsev5, K. Sistemich5, E. Steffens15, H. J. Stein5, H. Ströher5, A. Strzalkowski13, S. Trusov17,9, Yu. Uzikov9, Yu. Valdau1,5, A. Vassiliev1, A. Volkov9, K.-H. Watzlawik5, J. Wessels2, C. Wilkin18, A. Wronska5, P. Wüstner4, S. Yashenko15,9, B. Zalikhanov9, N. Zhuravlev9, K. Zwoll4, I. Zychor19.

1High Energy Physics Department, Petersburg Nuclear Physics Institute, Gatchina, Russia2Institut für Kernphysik, Universität Münster, Münster, Germany3High Energy Physics Institute, Tbilisi State University, Tbilisi, Georgia 4Zentrallabor für Elektronik, Forschungszentrum Jülich, Jülich, Germany5Institut für Kernphysik, Forschungszentrum Jülich, Jülich, Germany6Institut für Theoretische Physik, Universität Gieβen, Gieβen, Germany7Institute for Theoretical and Experimental Physics, Moscow, Russia8Institut für Hadronen und Kernphysik, Forschungszentrum Rossendorf, Dresden, Germany9Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, Dubna, Russia10Lebedev Physical Institute, Moscow, Russia 11Institute for Nuclear Research, Russian Academy of Sciences, Moscow, Russia 12Zentralabteilung Technologie, Forschungszentrum Jülich, Jülich, Germany13Institute of Physics, Jagellonian University, Cracow, Poland14Institut für Kernphysik, Universität Köln, Köln, Germany15Physikalisches Institut II, Universität Erlangen-Nürnberg, Erlangen, Germany16Institute of Nuclear Physics, Cracow, Poland17Dubna Branch , Moscow State University, Dubna, Moscow Region, Russia 18Physics Department, Univ. College London, London, Great Britain 19The Andrzej Soltan Institute for Nuclear Studies, Swierk, Poland

Spectrometer ANKESpectrometer ANKE

Triplet of magnets with several detector groups. Forward and Backward Detectors were proposed and produced by JINR physicists for the deuteron breakup study program. The Forward detector is used in a wide range of experiments atANKE.

Deuteron Breakup at High Momentum Deuteron Breakup at High Momentum TransferTransfer

A general problem:A general problem: hadron-nucleus interaction at high momentum transfer to more than one quasifree nucleon─ Study of a short–distance structure of nuclear matter

overlappingnucleons

q ≳ 0.4 GeV/c → rNN ~ 1/q ‹ 0.5 fm

nucleon radius ~ 0.86 fm

At which energies does the hadronic approach failand effects of the quark-gluon nature do appear?

The simplest cumulative process with 3-particle final state:

More clean and transparent interpretationin the framework of the hadronic approach

∆-isobar and πN(T=1/2, 3/2) suppression

Node in S-wave Ψpp(q) at q≈0.4 GeV/cYu.N.Uzikov(1990), (2002)Yu.N.Uzikov(1990), (2002)

p+d→(NN)forward +

p+ddforward +pbackward d — T=0, S=1

p+d→(pp)sforward +nbackward Epp<3MeV, (pp)s ― T=1, S=0

backwardlimitlkinematicatoclosefast,

N

The task: study of the deuteron breakup process in the most informative way which includes ― complete kinematical reconstruction ― measurement of polarization observables.

Forward Detector System PerformanceForward Detector System PerformanceB. Chiladze, et al. Part. and Nuclei, Lett. №4 (2002) 95

S. Dymov et al. Part. and Nuclei, Lett. №2 (2004) 40

A noticeable acceptance of ANKE for forward emitted particles: polar angle θp= 0°-11°

rigidity/Pbeam = 0.3-1.25

Θxz-p acceptance at 0.8 GeV beam energy.

Momentum correlation in double-track events at 0.8 GeV beam energy

Identification of the processes does not require Identification of the processes does not require particle mass identification (!)particle mass identification (!)

+

The setup provides:

momentum resolutionσ(p)/p = 0.5% - 1.0%

σ(θp) ≃ 0.2º

Missing mass accuracy

σ(Mx) = (17.5 ± 0.7) MeV for

pppp

σ(Mx)/Mp = 1.9%

time resolutionσ(∆t) = 200 ps

Sufficiently high relativeenergy (Epp) resolution (in cms of the proton pair)in the Epp range of 0.2-5.0 MeV

Simulated (pp) excitation energy resolutionfor pd(pp)n at 0.7 GeV

Particle identification using– momentum – energy losses in two consecutive scintillator planes– Cherenkov radiation amplitudes– time-of-flight difference for double-track events, σ(∆t) = 200 ps

Energy loss distribution in countersof two consecutive planes

Time-of-flight difference measured versus calculated one (assuming both

particles are protons).

E1 E2

pp

dddd

pppp

pd

d+H3 +

p+

pd

H+3

d+

p+

Experimental Results and Experimental Results and DiscussionDiscussion

First observation at intermediate energies

Missing mass (Selected: Epp, Ytarg, cosθ<0.7) p+d(pp) +nat the proton beam energyE = 0.6, 0.7, 0.8, 0.95, 1.35, 1.9 GeV

s

The data at E = 1.1, 1.4 and 2.0 GeVare also obtained and are in the stageof analysis.

Energy Dependence of the Differential Cross Energy Dependence of the Differential Cross SectionSection

pd(pp)n cross sectionintegrated over 0 <Epp<3 MeVaveraged in the interval 172º-180º

V. Komarov et al., Phys. Lett. V. Komarov et al., Phys. Lett. B553 (2003) 179 B553 (2003) 179

Model-independent determination of

dσs(t) =FSIs(t)·K·|As(t)|2 for pd(pp)sn and pd(pn)tp

2t

2s

A

Aς

Tp, GeV ζ, %

0.60.71.9

2.3 ± 0.51.6 ± 0.32.1 ± 1.2

*nθ

Yu.Uzikov et al. Eur.Phys.J. A18(2003)317

Description in the framework of theDescription in the framework of the ONE+SS+ONE+SS+ΔΔ ModelModel

J. Heidenbauer, Yu. UzikovJ. Heidenbauer, Yu. Uzikov

Phys. Lett. B562 (2003) 227Phys. Lett. B562 (2003) 227

Conclusion: the description is strongly sensitive to the short range behaviour of the NN potentials and definitely prefers the deuteron more soft at short distances than the Paris or Reid Soft Core potentials present.

Strong contradiction of the model using Paris orRSC NN potentials Qualitative agreement of the model with CD Bonn potentials

L.A. Kondratyuk et al (1981)L.A. Kondratyuk et al (1981)Yu.N. Uzikov (2002)Yu.N. Uzikov (2002)

Description inDescription in Bethe-Salpeter Approach: Bethe-Salpeter Approach:

Conclusion:Conclusion: Evidence for P-wave component contamination.

But: But: Only ONE mechanism is exploited.

L.P Kaptari, et al (1997)L.P. Kaptari, et al (2003)

Further experimental data are required to test validity of the hadronic approaches for the process description: - proton pair excitation spectra and angular distribution of the pair relative momentum - measurement of polarization observables

Polarization measurementsPolarization measurements

– Vanishing of Ayp at 0.8 GeV,

expected in the ONE+SS+∆ model

– High value of Ayp at 0.5 GeV,

contradicting the model Spin structure of the ΔΝ amplitude?

Analyzing power Ay

p(θn)

Submitted for publication in Phys. Rev. LettersData handling to obtain the Epp and θrt distributions is in

progress

E = 0.5, 0.8 GeVp

OutlookOutlook

—ABS polarized target is developed and constructed in IKP Jülich

—Installation of the ABS-target at ANKE and commissioning are planned for

2005. (Approved by the COSY PAC in November 2004.)

The needed maintenance and beam time is allocated.

pyA

Study of the pdppn process in the (Forward Detector)*(Backward Detector) configuration is foreseen as well.

Experiments with polarized deuteron target (2005-2008)

T20 and Cyy observables may be predicted in the model much more reliable than the observable . They will be measured with both the beam and the target polarized.

Participation in Other Experiments at Participation in Other Experiments at ANKEANKE

Various experiments on mesonmeson productionproduction a ) in pp, pd, dp, dd pp, pd, dp, dd interactions

Charge exchangeCharge exchange deuteron breakup, dp(pp)n

including - maintenance and upgrade of the Forward Detector - proposal preparation - software development - trigger upgrade - measurements - data analysis

0

List of ANKE publications with JINR co-authors in 2004List of ANKE publications with JINR co-authors in 2004

ExperimentExperiment

● Near-threshold production of omega-mesons in the pnd+ reaction. Eur. Phys. J. A21 (2004) 521

S. Barsov, ...S. Dymov, A. Kacharava, V. Komarov, G. Macharashvili, S. Merzliakov, A. Petrus, Yu. Uzikov, B. Zalikhanov, et al.

● Measurement of the analyzing power in pd (pp)n with a fast forward S diproton S . Yaschenko et al. Submitted to Phys.Rev.Lett.

InstrumentationInstrumentation

• Spectator detection for the measurement of proton-neutron interaction at ANKE. I. Lehmann, …, S. Merzliakov, S. Trusov et al. Nucl. Instr. and Methods V530/3 (2004) 275 • The forward detector of the ANKE spectrometer. Tracking system and its use in data analysis. S. Dymov, A. Kacharava, V. Komarov, A. Kulikov, V. Kurbatov, G. Macharashvili, A. Petrus, S. Yaschenko, B. Zalikhanov, N. Zhuravlev Part. and Nucl., Lett. No2 (2004) 40

Theory and analysisTheory and analysis

• Subthreshold antiproton production in proton-carbon reactions. V.Komarov, H. Mueller, A. Sibirtsev J. Phys. G: Nucl. Part. Phys. 30 (2004) 921 • Subthreshold antiproton production in pC, dC and αC reactions. H. Mueller, V. Komarov J. Phys. G: Nucl. Part. Phys. 30 (2004) 1379

01

ConclusionsConclusions

Performance of the ANKE setup is adequate to a scientific goal of fundamental character stated in the project.

First exclusive study of the deuteron breakup in kinematics close to that of the backward pd elastic scattering is performed.

The experimental results are not completely described by current models in the framework of the meson-nucleon approach. The experiment gives a tool for further insight into the short-range structure of a nuclear matter.

More refined theoretical description demands new experimental data.

The next stage of the study, with use of polarized deuteron target, starts in 2005. In addition to polarization physics at ANKE itself, it will be an important step towards the proposed future measurements with PAX at GSI.

The JINR group is strongly involved in the whole physical program of ANKE.