Поиск эта-мезонных ядер на Нуклотроне ЛФВЭ ОИЯИ dryablov@lhe.jinr.ru Дубна 06.02.2012 Дряблов Дмитрий XVI научная конференция молодых ученых и специалистов. - презентация

1 Поиск эта-мезонных ядер на Нуклотроне ЛФВЭ ОИЯИ Дубна Дряблов Дмитрий XVI научная конференция молодых ученых и специалистов ОИЯИ

2 Two states of an -nucleus: a state with the -meson (right) and a state with the S 11 (1535) nucleon resonance (left). These states are mixed due to fast transitions N S 11

3 a new field in studies on nuclear and particle physics. new data on the -meson and the S 11 (1535) resonance interactions with nucleons determination of the energy levels E_g (S 11 ) and E_g( ) and their widths g (S 11 ) and g ( ) in the -nucleus determine mass shift m (S 11 ) and m ( ) in the nuclear medium a study N N (for example, determination of real part of the scattering length process ) determination of the amplitude of the reaction S 11 N NN Physical

4 Formation, evolution and decay

5 K. Tsushima Nuclear Physics A670 (2000) 198c-201 c, Study o f,, ' and D -- mesic nuclei K. Tsushima, D.H. Lu, A.W. Thomas, K. Saito Physics Letters B –32, Are - and -nuclear states bound. A. I. L'VOV nucl-th/ PRODUCTION AND DECAY OF ETA -MESIC NUCLEI Proposed mass shift for S 11 m(S 11 ) = (24÷30) η + (8) N =30-40 MeV In nuclear medium

6 Kinematical characteristics Method of identification

7 Experimental setup K-arm K1 - Start counter K2 - Trigger & Cherenkov counters K3 - TOF - wall K4 - E-counter K5 - Veto counterP-arm P1 - Start counter P2 - Trigger & Cherenkov counters P3 - TOF - wall P4 - E-counter P5 - Veto counter Hm - Ring counter N - Neutron detector An - Neutron-Veto FL,FR,BL,BR - Monitors

8 Reconstraction proceeding

9 Effective mass formation in dA reaction at the energy 1.5 GeV/nuc Preliminary The distributions of the N pair yields are shown in Fig.(a,b) versus M eff of the pair nucleons. The histogram Fig.(b) shows the contamination obtained at the arm angle 170 o.The Fig.(a) corresponds to a back-to- back correlation coming from the two-body decay. The histogram Fig.(c) is the result of subtraction the back-to-back (180 o ) and the contamination measurements. The ratio of the nucleon pair numbers was N{170}/N{180}= (stat) in the mass region of 1450 < M eff < 1550 MeV/c 2. New data are collected. They are include 10 5 pairs coming from target in d+Cu and d+C reactions at the energy of primary beam 1.5GeV/nuc and 1.9Gev/nuc. (a) (b) (c) Counts/10MeV/c 2 (a) (b) (c)

10 Effective mass formation in dC reaction at the energy 1.9 GeV/nuc The yield of proton-pion pairs: p p 180 0

11 The value of the total cross-section of the process can be assessed based on the number of inelastic interactions dC, measured on the accounts of monitor telescopes, and the simulation results using the software package GEANT and RQMD.

12 Effective mass formation in dC reaction at the energy 2.0 GeV/nuc New data 2010 u Y(,p) 2.0 GeV/c 2 Best fit is Gaussian + constant Mean MeV Sigma 27.2 MeV Constant 1310 Distribution after rejection of the constant level Δ S 11 In medium Total events under picks 2000 N(1535)S 11 I(J P )=1/2 ( 1/2 - ) L(, ) =0 Mass m=1520 to 1550 ( 1535) MeV Full width =100 to 250 ( 150) MeV S 11 ΔM70 MeV 180 0

13 Зависимость энергетического разрешения (МэВ) МС для π-мезонов и нейтронов разных энергий от его относительного импульсного разрешения (%). Энергетическое разрешение TOF-системы в зависимости от длины базы (вакуум) для дискретного набора заданных ( , , , , нс) величин её времени разрешения и без учета дополнительных алгоритмов восстановления данных.

14 Распределение х-координат частиц в объеме дрейфовой камеры RDCh2 в зависимости от величины напряженности магнитного поля в условиях наличия воздуха на пути распространения (воздух+вещество детекторов). Начальное направление движения частиц совпадало с осевой линией межполюсного объема магнита Для протона (mc2 = 939 МэВ) с кинетической энергией 94 МэВ (β = 0.42, γ = 1.10) необходимая точность в δβ = 5.7*10-3 достигается при δX = 0.7 мм. Для протона с кинетической энергией 273 МэВ (β = 0.63, γ = 1.29) точности δβ = 2.3*10-3 отвечает δX = 0.15 мм. Указанные величины δX диктуют минимальные требования к постранственному разрешеню двух дрейфовых камер (не хуже δX/2), используемых для определения места входа и места выхода частиц, пролетающих магнитное поле. Для заряженного пиона (mc2 = 140 МэВ) с кинетической энергией 313 МэВ (β = 0.95, γ = 3.24) требуемая точность определения скорости δβ = 6.6*10-4 достигается при точности измерения поперечного отклонения δX=0.3мм

15 New proposal for η–nuclear study on nuclotron. d+A 1 A 2 (S 11 ) - +p+... d+A 1 A 2 (S 11 ) + +n+... d+A 1 A 2 (η+d*) p +n+... η+d p +n δE = δ(E π + E N ) < 10 МэВ.

16 Neutron counters (Stage-1 ) Two walls of scintillation counters. 8 counters – 12x12x100cm 8 counters – 2x12x100cm Multi layers neutron counter For first run test.

17 Magnet SP-46 Magnetic volume - 100x300x420mm Magnetic field - 7kGs

18 Project objectives The main aims of the proposed experiment are: search for -mesic nuclei in d+A reaction a determination of the total cross section of -nucleus production and A-dependence a determination of bounding energy of -mesic in nucleus a measurement of the yield ratio for ( p) and (N p) pairs

19 Collaboration S.V. Afanasiev, A.S. Artiomov, D.K. Dryablov, Z.A. Igamkulov, V.I. Ivanov, A.Yu. Isupov, A.I. Malakhov, 1 E.B. Plekhanov Joint Institute for Nuclear Research, Dubna, Moscow Region, Russia I.Cruceru, F.Constantin, M.Cruceru, G.Niolescu, L.Ciolacu Horia Hulubei National Institute of R&D for Physics and Nuclear engineering (IFIN-HH Bucharest, Romania V.A.Baskov, A.I. Lebedev, A.I. Lvov, L.N. Pavlyuchenko, V.V. Polyansky, E.B.Rzhanov, S.S. Sidorin, G.A. Sokol, Lebedev Physical Institute, Leninsky Prosect 53, Moscow , Russia V.Matousek, I.Turzo Institute of Physics, Slovak Academy of Sciences, Slovak republic S. Vokál. Vrláková, A. Kravčáková, A. Dirner, M. Špavorová, Faculty of Science, University of P.J. Šafárik, Košice, Slovak republic D.M. Jomurodov, R.N. Bekmirzaev, Jizzakh State Pedagogical Institute, Uzbekistan R.M.Ibadov, M.U. Sultanov, Samarkand State University, Uzbekistan

20 NTS

21 Thank you for attention!

22 The SCAN spectrometer can register only tail of Δ-resonance. Momentum of protons is limited P p >230 МэВ/с. NTS

23 Numerical calculation p+A d+ p=0 +(A-1) p=0 d+A t+ p=0 +(A-1) p=0 d+A 3 He+ p=0 +(A-1) p=0 (p) ( 3 He) NTS

24 Bounding energy P p = P d p+A d+ p=0 +(A-1) p=0 d+A t+ p=0 +(A-1) p=0 P d = P t E d = 2.22MeV E t = 6.25MeV 1) -meson production 2) To produce stable nucleus-rest from target 3) Effective capture of the meson 4) To measure the products of decay 13 C +d= 12 C+t+Q Q=1.3 MeV NTS

25 13 C(p,d) 12 C 13 C(d,t) 12 C Kinematic of recoil-free transfer reaction NTS

26 Target C, 8 wires x 8 mkm Target Al, 1 mm strip x 10 mkm Target Cu, 8 wire x 50 mkm Target W, 1 wire x 20 mkm Target Ag, 1 mm strip x 20 mkm Target CH 2, 1 mm strip x 10 mkm Construction of the Internal Target Station Dimension of the target region PMT for light control NTS

27 Setup of the experimental RUN The geometry of the experiment P-arm K-arm NTS

28 Reconstracted mass (confidence level > 95%) Effective mass Hadron Structure 2011 M 5 MeV/c 2 TOF 0.2 ns NTS

29 Formation of an η mesic nucleus and its decay via emission of back-to-back nucleon-pion pairs. Photoproduction of mesons from nuclei - In-medium properties of hadrons B. Krusche, nucl-ex/ NTS

30 Estimates of the effect yield Y(p ) 140 events/hour Y(pp) 2-3 events/hour Y(pn) 100 events/hour Y(p, - )= L (N 12 C N 1 N 2 n (A-1)) Br( N) n c f( p / ) - total cross section of eta-nuclei formation; L - luminosity; - the solid angle; - the probability to have the p pair f( p / ) - a geometric fraction; Br( N) - the branching ratio of S 11 (1535) decay; n c - accelerator cycles per hour; Production of -mesons in nucleon-nucleon collisions V. Baru, PHYSICAL REVIEW C 67, (2003)

31 Reconstraction proceeding The y-coordinate (its coordinate along scintillators P3/K3 ) The time of flight of a single particle on the basis of P3-P1/K3-K1

32 kinematic of recoil-free transfer reaction

33 The properties of hadrons in nuclear medium are one of the interesting topics of the modern hadron and nuclear physics. All nuclei have essentially smaller mass than sum of masses all neutrons and the protons formed nuclei. The difference of masses is a result of strong interaction between hadrons which formed composite system. It is possible to assume, that particles, distinct from nucleons such as an - meson, in nuclear medium will have smaller mass than in a free state. Motivation The first experimental evidence of -mesic nuclei was obtained in 1998 at LPI (Moscow, Russia) at the photon beam Last years active preparations for experiments on a search of -mesic nuclei in European labs A possibility to perform studies on physics of - mesic nuclei at the JINR nuclotron internal proton beam is proposed reaction p+A n+p+ (A - 1) elementary process p+n* n+S + 11 (1535)* n+ p + * Дубна