project scan-3 of studying eta- mesic nuclei and other forms of excited nuclear matter at the jinr...
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Project SCAN-3 of studying eta-mesic nuclei and other forms of
excited nuclear matter at the JINR Nuclotron
Institute of Physics, Slovak Academy of Sciences, Slovak republicJ.Kliman, V.Matousek, S.Gmutsa, I.Turzo
Horia Hulubei National Institute of R&D for Physics and Nuclear engineering (IFIN-HH Bucharest, Romania
I.Cruceru, F.Constantin, M.Cruceru, G.Niolescu, L.Ciolacu Insitute for Space Science, Bucharest-Magurele, Romania
M. ParaipanJoint Institute for Nuclear Research, Dubna, Russia
S.V. Afanasiev, Yu.S.Anisimov, A. A.Baldin, A.I.Berlev, D.K.Dryablov, B.V.Dubinchik, A.F.Elishev, O.V.Fateev, Z.A.Igamkulov, L.V.Karnyushina, Yu.F.Krechetov, I.V.Kudashkin,
Z.P.Kuznecova, S.N.Kuznechov, A.I. Malakhov, V.A.Smirnov, S.S.Shimansky Institute advanced studies «OMEGA», Dubna, Russia
A.A.Baldin, A.I.Berlev, I.V.Kudashkin,Faculty of Science, University of P.J. Šafárik, Košice, Slovak republic
S. Vokál, J. VrlákováLebedev Physical Institute, Leninsky Prosect 53, Moscow, Russia
V.A.Baskov, A.I. Lebedev, A.I. L’vov, L.N. Pavlyuchenko, V.V. Polyansky, E.V.Rzhanov, S.S. Sidorin, G.A. SokolPTI, Tomsk, Russia
I.V.Glavanakov, A.N.TabachenkoJizzakh State Pedagogical Institute, Uzbekistan
D.M. Jomurodov, R.N. BekmirzaevSamarkand State University, Uzbekistan
R.M.Ibadov, M.U. Sultanov
Collaboration
Design of a precision three arms hybrid magnetic spectrometer for the study of excited baryon matter on the internal beams of the Nuclotron.
The spectrometer is designed for recording and analysis of charged particles (π, K, p), neutral particles (n), and nuclear fragments. Momentum resolution for elementary particles is 1.5-2%. Three arms allow studies of NN and πN correlations.
Studies of physical phenomena:- search and study of η-mesic nuclei;- study of Δ-isobars formed in the core of the target;- study of np and pp pair correlations;- study of cumulative processes;- study of disintegration of heavy nuclei into low energy fragments .
Project purpose
Searches for unstable eta-mesic nuclei
The existence of an eta-mesic nucleus, i.e., a quasibound state of the η meson and a nucleus was predicted due to the attractive nature of the ηN interaction. Since its first mention in 1986, several experimental and theoretical searches have been performed for light as well as heavy eta-mesic nuclei. The experimental searches involve the production of η mesons and hence signals for the existence of eta-mesic states via their possible decay modes, and final state interactions of eta mesons with nuclei.
The interaction of the η-meson with a nucleon near threshold is mainly determined by the S11, J_(spinparity) = ½ - resonance N*(1535), which is just 49 MeV above the ηN threshold (1486 MeV) and has a width Γ=150 MeV, thus covering the whole low energy region of the ηN interaction. As the S11-resonance also decays to πN, γN and ππN channels involves its coupling to all these channels.
[email protected]@moonhe.jinr.ruDubna, RussiaDubna, Russia
LPI experiment MAMI accelerator in Mainz
The method consists in detection and energymeasurements of components of N pairs from S11-resonance decays in the nuclear medium.
Layout of the experimental setup. Shown also are the time-of-flight spectra in the (left) and n (right) spectrometers.
Setup of the TAPS detector at the Mainz MAMI accelerator. Krusche, B nucl-ex/0411033
Such pion - nucleon pairs have been searched for in the channel πo - p, which is best suited for the TAPS detector.
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
Resulting energy shift of η+N pair in the nuclear medium,
E(η+N ) = (24÷30)η + (8)N =30-40 MeV
[email protected]@lhe.jinr.ru
Experimental setup2005-2008
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
Effective mass formation in dC reaction at the energy 2.0 GeV/nuc
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
Δ≈20 MeV
1800
Nuclotron based measurement of eta-nucleai.
Search for the η-mesic nuclei in a recoil-free transfer reaction COSY-GEM Collaboration
p + 27Al → 3He + π- + p + X
η-25Mg
A. Budzanowski et al., Phys. Rev. C 79 (2009)
The other one is a bit more recent measurement from COSY on the p 27Al → 3He X reaction in a recoil free kinematic setup, where one observes in coincidence with 3He, the decay of a possible bound η-25Mg state, again, through the S11 resonance.
What we are looking for?
It is important to recognize that if we register N pair with approximately equal but opposite momentum components, even with some suitable total energy E + EN m + mN = 1486 MeV, it does not necessarily mean that we have registered the decay products of the η-mesic nucleus.
The criterion of a bound -meson is the condition for the N pair's total energy, which should be below the threshold: E + EN <1486 MeV
N pair production from -meson annihilation occurs in the process + Ni + N, the mechanism of which is determined by the excitation and decay of the intermediate nucleon resonance S11(1535):
+ Ni S11 + N.
Next criterion of a bound -meson is the width of the peak in the distribution of πN pairs which is not related to the width of the resonance S11 (1535).
Determination of the η-nuclei according to their decay products.
Expected characteristics of pairs from decay of -nuclei and requirements to precisions of their measurements The task of the experiment is the allocation and measurement of the narrow peaks in the energy distribution of pairs, which are products of -nucleus decay. Apparently, future experiments should assume that the peak width will be about 10 MeV, and therefore they should provide accurate measurements of particle energies will be not worse than ~ 3.5 MeV, so that the accuracy of the total energy of the pair will be at least 5-7 MeV. The effects of an broadening of observable peak, caused by energy dispersion in cause intra nuclear nucleons motion. This dispersion a increases observable width of peak by ~20 MeV. This moment is reduce the accuracy to the level of 10 MeV. If we consider the process + Ni + N with initial particles at rest, the kinetic energy, momentum and velocity of the secondary particles can be estimated: T = E m = (W2 + m
2 mN2)/(2W) m = 313 MeV,
TN = EN mN = (W2 + mN2 m
2)/(2W) mN = 94 MeV, p = pN = [E
2 m2] 1/2 = [EN
2 mN2] 1/2 = 431 MeV/c,
= p/ E = 0.95, N = pN/ EN = 0.42.Here W = m + mN
= 1486 MeV, also were used masses m= 140 MeV, mN = 939 MeV, m = 547 MeV.
Besides the N mode, -nuclei can decay with emission of NN pairs due to the reaction
η + Ni + Nj N1 + N2
The rate of this decay channel is expected to be compatible with the rate of the channel p.Isotopic contents of the emerging NN system is
5% pp, 5% nn, 90% pn
Study of Δ-nuclei
Almost unknown phenomenon - Isobar in the nucleus, associated with the hypothetical quasi-bound Δ-nuclear state.Δ-Isobar and the residual nucleus may form unstable short-lived highly excited state (Δ-nuclei). The excitation energy of Δ-nuclei 12СΔ estimated equal to 280 MeV and the width is 2 MeV. The same parameters Δ-nuclei 4HeΔ equal to 285 MeV and 30 MeV. Formation of nuclei in the intermediate state of the process
evaluation of the cross section for the reaction
The differential output of photo-production of π-p pairs, depending on the angle of scattering of pion and proton. Experimental data from work [29].
Formation of Δ-nuclei in the scattering of deuteron at a nucleus.
Two ways that structure is revealed:1. The excitation spectrums
in the cumulative domain2. Scattering from "hard" centres in the x > 1 domain
- investigation of the nuclear fragments at high pT domain production and their isotopic composition, to obtain detailed information about isotopic composition of nuclear fragments with nucleon number more than three for which no experimental data;
- investigation of the fusion mechanism contribution to the nuclear fragments formation and to determine the contribution of direct formation process of nuclear fragments from the multinucleon (multiquark) configurations;
- investigation of the multineutron system formation as configurations that can be droplets of the neutron matter which properties can be similar to the properties of neutron star matter.
Внеочередной семинар ЛФВЭ, общелабораторная секция19 марта 2015 г., 10:30, большой конференц-зал ЛФВЭ, корпус 215 Experimental Study of Short Range Correlation in NucleiOr Hen, Eli Piasetzky (Tel Aviv University, Israel)Guy Ron (Hebrew University Jerusalem, Israel) Short-range correlations between pairs of nucleons in nuclei account for ~20% of the nuclear wave function and dominate its momentum distribution. Their characteristics are sensitive to the nucleon-nucleon interaction at short distances and are therefore eminently suitable for probing cold-dense nuclear matter, such as that which exists in neutron stars, here on the earth. Although studied for many years, only recently, with the reach of high-energy high-luminosity electron and proton beams, the experiments finally reveal the details of short-range nucleon-nucleon correlations. We review the experimental results and discuss their wide range implications for atomic, nuclear, and astrophysics, including neutrino-nucleus scattering, the EMC effect, the NuTeV anomaly, the nuclear symmetry energy, and more. Study of Short Range Correlation in Nuclei with Hadron BeamsEli Piasetzky (Tel Aviv University, Israel)Guy Ron (Hebrew University Jerusalem, Israel) We discuss the physics motivation and open questions, which show the need for a high statistics next generation of experimental studies of short-range correlations in nuclei. We review the possibility of using a few GeV/c proton beams for such measurements and the possible layout of the experiment.
Study of np and pp pair correlations;
[email protected]@lhe.jinr.ru
13C(p,d)12C 13C(d,t)12C
Kinematic of reactionBounding energy
Pp = Pd
p+A d+ p=0+(A-1)p=0
d+A t+ p=0 +(A-1)p=0
Pd = Pt
Ed = 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+η+QQ=1.3 MeV
N+A N+N+ p=0+(A-1)p=0
• significant improvement of the energy resolution (better than 10 MeV)
• simultaneous recording of the effect and background significantly reduces systematic errors
Experimental setup
shaft
Radial tunnel
Location of spectromrter
K-arm
P-arm
M-arm
Distortion of π+ and p of energy range of 200 – 425 МэВ in the magnetic field of SP-46 magnet.
Distortion of track in magnetic field as a function of particle type, kinetic energy and two values of the magnetic field Нмах=7 and 10 кГс.
Energy resolution for protons is 6.5 and 3.2 MeV, for pions – 3.5 and 2.6 MeV at the magnetic field 7 and 10 kHs accordingly.
Magnet SP-46
TOF
Timing and coordinate distribution for elements of the third detector, M-arm.
Time of flight hodoscope M-arm, before assembly
R&D for neutron counter
Preliminary data gave a time resolution is better then 300 ps for neutron detection.
Neutron detectors
Energy resolution EN 10 МэВ.
E = 3 mc2 ,
EN=270 МэВ ( = 0.63 и = 1.29) L = 6м
= 0.8*102 { t <0.4 нс { L < 8 см
Multi layers neutron counter
[email protected]@lhe.jinr.ru
Neutron detectors
Summary from beam test:TOF resolution vary from 0.27ns to 0.4ns with mean value is 0.31ns
Test neutron counters on “MARUSIA”-area
Characteristics of coordinate detectors must meet the requirements of the accuracy of the restoration of pair effective mass (4-6 MeV/c2 ).1) Detectors should work well et the rate 104 particles/s;2) The spatial resolution of one chamber should be no worse than 0,15 mm;3) Chambers must contain a minimum amount of the substance to reduce the multiple scattering.
There is a plan to produce two drift chambers Mc1 and Mc2 with dimensions 32х10 cm2. The design of the chambers will be similar to that of the chambers of HADES [Л.Н.Глонти и др., препринт ОИЯИ Р13-2000-80, 2000]. The chambers will consist of two layers. The layers are offset from each other by half the cell. Cell size is 5х5 mm2, therefore each plane will have 64 signal wires. Requirements for the coordinate detector Mc3 are easy, so we can use different types of gas detectors that is available.
Track system
The data acquisition system is built on the VME platform and includes a set of modules serving experimental setup. Basis of DAQ is VME modules , which are produced in VBLHEP JINR. DAQ consist of:FVME – VME crate controller;FVME2TM – trigger module;TQDC-16 - 16-channel converter of time and charge, the total number – 64 channels;TDC64V - 64-channel TDC with a resolution of 100ps, total - 128 channels;
DAQ
GEANT simulation
A study of the accuracy of the rotation angle of pions in a magnetic field (B=7 kGs) depending on the thickness of the detectors, the number of the coordinate cameras and gas environment.
Data analysis showed:
the passage of pions with kinetic energy 313 MeV.-the best angular resolution is achieved in a vacuum, -counters minimum thickness meters and 4 cameras 0.82 % (2.6 MeV) -in air and 3 cameras resolution deteriorates irrelevant to 1.28 % (4 MeV)for protons with kinetic energy of 270 MeV- in the first case, the accuracy of determination of the angle is 1.17% (3.2 МэВ)-In the second case, the accuracy of determination of the angle is 2.4% (6.5 МэВ)
Acceptance
For protons (left) and pions (right) in М-arm
Background
The total fluxes of particles in the aperture of the M - and P-arms of SCAN-3 setup. The X axis is the kinetic energy of particle (MeV), the Y axis is the number of particles. The black line is the total contribution; the yellow line is the contribution from protons; the red line is the contribution from neutrons; the green line is the contribution from charged pions; the blue line is the contribution from neutral pions.
Ekin=2GeV/nuc. Ф=109
Background
Ekin=1GeV/nuc. Ф=106
Nbg(S-πN) =Nn·Nπ·τ=104·102·10-9=10-3c-1
Nbg(S-NN) =NN·NN·τ=102·102·10-8=10-4c-1
Nbg(Δ-πN) =Nn·Nπ·τ=102·101·10-6=10-3c-1
Nbg(Δ-NN) =NN·NN·τ=102·102·10-5=10-1c-1
Background of pairs productionBackground of pairs production.
RQMD 2.4 + GEANT-3
The Number of pairs with the energy of 1535±30MeV forming from random coincidences depending on the energy of primary beam. The region of formation of η-nuclei.
The Number of pairs with the energy of 1232±30MeV forming from random coincidences depending on the energy of primary beam. The region of formation of Δ-nuclei.
Состояние дел по проекту NICA Г. Трубников (ОИЯИ) International workshop"NICA accelerating complex: problems and solutions — 2014"
Schedule of the project
As a result of project implementation we plan:•to create a precision magnetic spectrometer for the measurement of correlated pairs with an energy resolution up to 4-5 MeV;•to investigate the behavior of S11 and (1232) resonances in the nuclear medium;•search for η-Mesic and -nuclei in dA interaction;•to determine the cross-section of education -nuclei (A); and to investigate A-dependence of the cross section (A); •determine the bound energy of eta-mesons in nucleus – the main parameter characterizing the potential of attraction of this meson to nucleons at low energies;•to measure the relationship of outputs (-p) and (pN) events associated with the responses of S11(1535)N and S11NNN in the nucleus and to determine the relationship of the widths of Г(S11 N) and Г(S11NNN) of these reactions;•to determine the cross-section of education -nuclei on the core of carbon and possibly on other cores;•to determine the binding energy and width of the quasi-bound states of -isobar asymmetry in the nucleus taking into account a charge state;•to measure the ratio of probabilities πN and NN decay modes of -nuclei.•to investigate the release of nuclear fragments in the area of large PT and their isotopic composition;•to investigate the contribution of the mechanism of fusion in the formation of nuclear fragments;
Summary
