Поиск эта-мезонных ядер на Нуклотроне ЛФВЭ ОИЯИ

Поиск эта-мезонных ядер на Нуклотроне ЛФВЭ ОИЯИ

[email protected]@lhe.jinr.ruДубнаДубна 0606..0202.201.20122

Дряблов Дмитрий

XVI XVI научная конференция молодых ученых и специалистов ОИЯИнаучная конференция молодых ученых и специалистов ОИЯИ

Two states of an -nucleus: a state with the -meson (right) and a state with the S11

(1535) nucleon resonance (left). These states are mixed due to fast transitions N S11

• a new field in studies on nuclear and particle physics.• new data on the -meson and the S11(1535) resonance

interactions with nucleons • determination of the energy levels E_g (S11) and E_g() and

their widths g(S11) and g() in the -nucleus

• determine mass shift m(S11) 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 S11 N NN

Physical aims

[email protected]@lhe.jinr.ru

Formation, evolution and decay. p0 1 +p2 p0 n1

A (A - 1) . p0 1 +n2 p0 p1

A (A - 1) p0 1 +p2 p0 p1

A (A - 1)

1

0.1

10-5

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 443 1998 26–32,

“Are - and -nuclear states bound.”

A. I. L'VOV nucl-th/9809054PRODUCTION AND DECAY OF ETA

-MESIC NUCLEI

Proposed mass shift for S11

m(S11) = (24÷30)η + (8)N =30-40 MeV

In nuclear medium


Kinematical characteristics Method of identification

11

0 0180 10

110 10

350 30

p

p

S p

T MeV

T MeV

Experimental setup

K-armK-armK1 - Start counterK2 - Trigger & Cherenkov countersK3 - TOF - wallK4 - E-counterK5 - Veto counter

P-armP-armP1 - Start counterP2 - Trigger & Cherenkov countersP3 - TOF - wallP4 - E-counterP5 - Veto counter

Hm - Ring counterN - Neutron detectorAn - Neutron-Veto

FL,FR,BL,BR - Monitors

11

0 0180 10

110 10

350 30

p

p

S p

T MeV

T MeV


Reconstraction proceeding

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 Meff of the pair nucleons. The histogram Fig.(b) shows the contamination obtained at the arm angle 170o.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 (180o) and the contamination measurements.

The ratio of the nucleon pair numbers was N{170}/N{180}=0.42 + 0.08(stat)in the mass region of 1450 < Meff< 1550 MeV/c2.

New data are collected.They are include 105 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/c2

(a)

(b)

(c)

Effective mass formation in dC reaction at the energy 1.9 GeV/nuc

The yield of proton-pion pairs:

p1700p1800


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.

9in

in

Inelastic interaction : N = 1.5-2.2 * 10 ;

Solid angle: ;

Cross-section of dC inelastic interactio ns at the

energy 2.1 GeV / n: = 426 ± 22 mb

Total cross-section:

-3 9A in eff fon in = ( *(N -N ))/( *N ) = 426*32.5*4 /8*10 *1.85*10 =11.6 ± 7.5 b

Effective mass formation in dC reaction at the energy 2.0 GeV/nuc

New data 2010

uu

Y(,p)2.0 GeV/c2

Best fit is Gaussian + constant Mean 1465.1 MeV Sigma 27.2 MeVConstant 1310

Distribution after rejection

of the constant level

Δ

S11

In medium

Total events under picks ≈2000

N(1535)S11 I(JP)=1/2 ( 1/2- )

L(,) =0Mass m=1520 to

1550 (1535) MeVFull width =100 to

250 (150) MeV

S11

ΔM≈70 MeV

1800

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 (--- 0.1, --- 0.2, --- 0.3, --- 0.4, --- 0.5 нс) величин её времени разрешения и без учета дополнительных алгоритмов восстановления данных.

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

New proposal for η–nuclear study on nuclotron.

d+A1 A2(S11) -+p+...

d+A1 A2(S11) ++n+...

d+A1 A2(η+d*) p +n+...

η+d p +n

δE = δ(Eπ + EN) < 10 МэВ.

Neutron counters (Stage-1 )

Two walls of scintillation counters. 8 counters – 12x12x100cm8 counters – 2x12x100cm

Multi layers neutron counterFor first run test.

Magnet

SP-46

Magnetic volume - 100x300x420mmMagnetic field - 7kGs

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

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, 141980 Dubna, Moscow Region, RussiaI.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. L’vov, L.N. Pavlyuchenko, V.V. Polyansky, E.B.Rzhanov, S.S. Sidorin, G.A. Sokol,

Lebedev Physical Institute, Leninsky Prosect 53, Moscow 117924, RussiaV.Matousek, I.Turzo

Institute of Physics, Slovak Academy of Sciences, Slovak republicS. Vokál. Vrláková, A. Kravčáková, A. Dirner, M. Špavorová,

Faculty of Science, University of P.J. Šafárik, Košice, Slovak republicD.M. Jomurodov, R.N. Bekmirzaev,

Jizzakh State Pedagogical Institute, UzbekistanR.M.Ibadov, M.U. Sultanov,

Samarkand State University, Uzbekistan

[email protected]@lhe.jinr.ruNTS 03.112011NTS 03.112011

Thank you for attention!


cMeVPN N /227,

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

NTS 03.10.2011NTS 03.10.2011


Numerical calculation

p+A d+ p=0+(A-1)p=0d+A t+ p=0 +(A-1)p=0

d+A 3He+ p=0 +(A-1)p=0

(p)(p)

(3He)

NTS 03.10.2011NTS 03.10.2011


Bounding energy

Pp = Pd

p+A d+ p=0+(A-1)p=0d+A t+ p=0 +(A-1)p=0

Pd = PtEd = 2.22MeV Et = 6.25MeV

1) -meson production 2) To produce stable nucleus-rest from target3) Effective capture of the meson4) To measure the products of decay

13C +d= 12C+t+QQ=1.3 MeV

NTS 03.10.2011NTS 03.10.2011


13C(p,d)12C 13C(d,t)12C

Kinematic of recoil-free transfer reaction

NTS 03.10.2011NTS 03.10.2011

Target -1 -- 12C, 8 wires x 8 mkm

Target -2 -- 27Al, 1 mm strip x 10 mkm

Target -3 - - 64Cu, 8 wire x 50 mkm

Target -4 - - 183W, 1 wire x 20 mkm

Target -5 -- 108Ag, 1 mm strip x 20 mkm

Target -6 -- CH2, 1 mm strip x 10 mkm

Construction of the Internal Target Station

Dimension of the target region

PMT for light control

[email protected]@lhe.jinr.ruNTS 03.10.2011NTS 03.10.2011


Setup of the experimental RUNThe geometry of the experiment

P-arm K-arm

NTS 03.10.2011NTS 03.10.2011

Reconstracted mass (confidence level > 95%)

2

2

1,2 1 21 2 2 2

1 2

1

1 1

1 1

recon

eff

M T

m mM E E

Effective mass

Hadron Structure 2011


M5 MeV/c2

TOF0.2 ns

NTS 03.10.2011NTS 03.10.2011

[email protected]@moonhe.jinr.ru

Formation of anη mesic nucleus and its decayvia emission of back-to-back

nucleon-pion pairs.

Photoproduction of mesons from nuclei- In-medium properties of hadrons

B. Krusche,nucl-ex/0411033

NTS 03.10.2011NTS 03.10.2011

Estimates of the effect yield

Y(p) 140 events/hourY(pp) 2-3 events/hourY(pn) 100 events/hour

Y(p, -)= L (N12CN1N2n(A-1)) Br(N) nc f(p/)

- total cross section of eta-nuclei formation;

L - luminosity; - the solid angle; - the probability to have the p pairf(p/) - a geometric fraction;Br(N) - the branching ratio of S11(1535) decay;nc - accelerator cycles per hour;

Production of -mesons in nucleon-nucleon collisionsV. Baru,

PHYSICAL REVIEW C 67, 024002 (2003)


033

2

1ytty c

Pbot

Ptop 1.8y см

Reconstraction proceeding

The y-coordinate (it’s coordinate along scintillators P3/K3 )

1.75x см

The time of flight of a single particle on the basis of P3-P1/K3-K1

01133

2

1tttttt P

botP

topP

botP

top 0.15 0.2t нс

kinematic of recoil-free transfer reaction

12 11( , )C p d C12 11( , )C d t C

p dP Pd tP P

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 + *

ДубнаДубна 0606..0202.201.20122

Поиск эта-мезонных ядер на Нуклотроне ЛФВЭ ОИЯИ

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