Transcript No Slide Title

XVI научная конференция молодых ученых и специалистов ОИЯИ
Поиск эта-мезонных ядер на
Нуклотроне ЛФВЭ ОИЯИ
Дряблов Дмитрий
Дубна 06.02.2012
[email protected]
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
Physical aims
• 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
[email protected]
Formation, evolution and decay
.
p0
1
+p2
p0
n1
1
A
(A - 1)
.
p0
1
+n2
p0
p1
0.1
A
(A - 1)
p0
1
+p2
p0
A
p1
(A - 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/9809054
PRODUCTION 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
S11   p
 p  180  10
0
0
Tp  110  10MeV
T  350  30MeV
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Experimental setup
K-arm
K1 - Start counter
K2 - Trigger &
Cherenkov counters
K3 - TOF - wall
K4 - E-counter
K5 - Veto counter
P-arm
S11   p
 p  1800  100
Tp  110  10MeV
T  350  30MeV
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
Reconstraction proceeding
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Effective mass formation in dA reaction at the energy 1.5 GeV/nuc
Counts/10MeV/c2
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-toback 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.
(a)
(a)
(b)
(b)
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.
Preliminary
(c)
(c)
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.
The yield of proton-pion pairs:
Effective mass formation in dC reaction at the energy 1.9 GeV/nuc
p1800
p1700
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.
Inelastic interaction : N in = 1.5-2.2 * 10 9 ;
Solid angle: ;
Cross-section of dC inelastic interactio ns at the
energy 2.1 GeV / n:  in= 426 ± 22 mb
Total cross-section:





3
9
=
(
*
(
N
N
)
)
/
(

*
N
)
=
4
2
6
*
3
2
.
5
*
4
/
8
*
1
0
*
1
.
8
5
*
1
0
=
1
1
.
6
±
7
.
5
b
i
n
A
i
n
e
f
f
f
o
n
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Y(,p)2.0 GeV/c2
New data 2010
Effective mass formation in dC reaction at the energy 2.0 GeV/nuc
1800
Best fit is Gaussian + constant
Mean
1465.1 MeV
Sigma
27.2 MeV
Constant
1310
N(1535)S11
I(JP)=1/2 ( 1/2- )
L(,) =0
Mass m=1520 to 1550
(1535) MeV
Full width =100 to
250 (150) MeV
Total events under picks
≈2000
ΔM≈70 MeV
Δ
S11
Distribution
after rejection
of the
constant level
S11
In medium
u
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.
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
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.
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
New proposal for η–nuclear study on nuclotron.
δE = δ(Eπ + EN) < 10 МэВ.
d+A1 A2(S11)  -+p+...
d+A1 A2(S11)  ++n+...
d+A1 A2(η+d*)  p +n+...
η+d  p +n
Neutron counters
(Stage-1 )
Two walls of scintillation counters.
8 counters – 12x12x100cm
8 counters – 2x12x100cm
Multi layers neutron counter
For first run test.
Magnet
SP-46
Magnetic volume - 100x300x420mm
Magnetic 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, 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. 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, 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
NTS 03.112011
[email protected]
Thank you
for attention!
    N,
PN  227MeV / c
The SCAN spectrometer can register
only tail of Δ-resonance. Momentum
of protons is limited Pp>230 МэВ/с.
NTS 03.10.2011
[email protected]
Numerical calculation
p+A d+ p=0+(A-1)p=0
d+A t+ p=0 +(A-1)p=0
d+A 3He+ p=0 +(A-1)p=0
(p)
(p)
(3He)
NTS 03.10.2011
[email protected]
Bounding energy
d+A t+ p=0 +(A-1)p=0
p+A d+ p=0+(A-1)p=0
Pp = Pd
Pd = Pt
Ed = 2.22MeV
Et = 6.25MeV
13C
+d= 12C+t+Q
Q=1.3 MeV
1) -meson production
2) To produce stable nucleus-rest from target
3) Effective capture of the meson
4) To measure the products of decay
NTS 03.10.2011
[email protected]
Kinematic of recoil-free transfer reaction
13C(p,d)12C
NTS 03.10.2011
13C(d,t)12C
[email protected]
Construction of the Internal Target Station
Dimension of the target region
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
PMT
for light control
NTS 03.10.2011
[email protected]
Setup of the experimental RUN
The geometry of the experiment
P-arm
NTS 03.10.2011
K-arm
[email protected]
Hadron Structure 2011
Reconstracted mass
(confidence level > 95%)
M recon  T
1  2
1 1  2
Effective mass
TOF0.2 ns
M5 MeV/c2
NTS 03.10.2011
M eff 1,2  E1  E2 
m1
1  12

m2
1  22
[email protected]
Photoproduction of mesons from nuclei
- In-medium properties of hadrons
B. Krusche,
nucl-ex/0411033
Formation of an
η mesic nucleus and its decay
via emission of back-to-back
nucleon-pion pairs.
NTS 03.10.2011
[email protected]
Estimates of the effect yield
Y(p, -)= L  (N12CN1N2n(A-1))  Br(N)      nc  f(p/)
- total cross section of eta-nuclei formation;

L
- luminosity;

- the solid angle;
Production of -mesons in nucleon-nucleon collisions
V. Baru,

- the probability to have the p pair
PHYSICAL REVIEW C 67, 024002 (2003)
f(p/) - a geometric fraction;
Br(N) - the branching ratio of S11(1535) decay;
nc
- accelerator cycles per hour;
Y(p)
Y(pp)
Y(pn)
 140 events/hour
 2-3 events/hour
 100 events/hour
Reconstraction proceeding
The y-coordinate (it’s coordinate along scintillators P3/K3 )


1
P3
P3
y  t top  t bot   c  y 0
2
 y  1.8см
 x  1.75см
The time of flight of a single particle on the basis of P3-P1/K3-K1
t

 

1
P3
P3
P1
P1
t top  t bot
 t top  t bot
 t0
2
 t  0.15  0.2нс
[email protected]
kinematic of recoil-free transfer reaction
12
Pd  Pt
C ( p, d )11C
12
C (d , t )11C
Pp  Pd
Motivation
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.
•
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 06.02.2012
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