Spin physics experements at NICA (Letter of Intent)

QUARKS2014 2-8 June, Suzdal, Russia

O.Kouznetsov and I.Savin On behalf of the LoI drafting committee

LHEP, JINR, Dubna

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List of LoI participants (>100) still is open for interested people

03.06.2014

R. Abramishvili1, V.V. Abramov6, F. Ahmadov1, R.R. Akhunzyanov1, V. A. Anosov1, N.V. Anfimov1, S. Anishchanka12, X. Artru15, A.A.Baldin1, V.G. Baryshevsky12, A. S. Belov5, D. A. Bliznyuk14, M.Bodlak8, A.V. Butenko1, A. P. Cheplakov1, I. E. Chirikov-Zorin1, G. Domanski10, S.V. Donskov6, V.V. Drugakov17, M. Dziewiecki10, A.V. Efremov1, Yu. N. Filatov1,3, V.V. Fimushkin1, M. Finger (jun.)7,1, M. Finger7,1, S.G. Gerassimov13, I.A. Golutvin1, A. L.Gongadze1, I. B. Gongadze1, M. I. Gostkin1, B.V. Grinyov14, A. Gurinovich12, A.V. Guskov1, A. N. Ilyichev17, Yu. I. Ivanshin1, A.V. Ivanov1, V. Jary8, A. Janata7,1, N. Javadov1, L. L. Jenkovszky4, V. D. Kekelidze1, D. V.Kharchenko1, A.P. Kobushkin4, B. Konarzewski10, A. M. Kondratenko2,M. A. Kondratenko2, I. Konorov13, A. D. Kovalenko1, O. M. Kouznetsov1, G. A. Kozlov1, A.D. Krisch16, U. G. Kruchonak1, Z.V. Krumshtein1, V.V. Kukhtin1, K. Kurek9, P. K. Kurilkin1, R. Kurjata10, L.V. Kutuzova1, N. K. Kuznetsov1, V. P. Ladygin1, R. Lednicky1, A. Lobko12, A.I. Malakhov1, J. Marzec10, J. Matousek7, G.V. Meshcheryakov1, V. A. Mikhaylov1, Yu.V. Mikhaylov6, P.V. Moissenz1, V.V. Myalkovskiy1, A. P. Nagaytsev1, J. Novy8,I. A.Orlov1, M. Pesek7, D.V. Peshekhonov1, V. D. Peshekhonov1, V. A. Polyakov6, Yu.V. Prokofichev1, A.V. Radyushkin1, V. K. Rodionov1, N. S. Rossiyskaya1, A. Rouba12,A. Rychter10, V. D. Samoylenko6, A. Sandacz9, I. A. Savin1, G. A.Shelkov1, N. M. Shumeiko17, O.Yu. Shevchenko1, S.S. Shimanskiy1, A.V. Sidorov1, M. Slunechka7,1, V. Slunechkova7,1, J. Soffer11, G.I. Smirnov1, N. B. Skachkov1, A.A. Solin17,A.V. Solin17, E. A. Strokovsky1, O. V. Teryaev1, M. Tomasek8, N.D.Topilin1, A.V.Turbabin5, Yu.N. Uzikov1, M.Virius8, V.Vrba8, M.V. Zavertyaev13, K. Zaremba10, E.V. Zemlyanichkina1, P.N. Zhmurin14, M. Ziembicki10, V. N. Zubets5, I. P.Yudin1

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Affiliations

03.06.2014

16University of Michigan, USA15CNRS, Lyon, France14Institute for Scintillation Materials, NAS, Kharkov, Ukraine13Lebedev Physics Institute, Moscow, Russia12Research Institute for Nuclear Problems, Minsk, Belarus11Temple University, Philadelphia, USA10Warsaw University of Technology, Institute of Radio electronics, Warsaw, Poland9National Center for Nuclear Research, Warsaw, Poland8Technical University, Faculty of Nuclear Science and Physics Engineering, Prague, Czech Rep. 7Charles University, Faculty of Mathematics and Physics, Prague, Czech Republic6Institute for High Energy Physics, Protvino, Russia5Institute for Nuclear Research of Russian Academy of Sciences, Moscow, Russia4Bogolyubov Institute for Theoretical Physics, Kiev, Ukraine3Moscow Institute of Physics and Technology, Dolgoprudny, Russia2Science and Technique Laboratory Zaryad, Novosibirsk, Russia1Joint Institute for Nuclear Research, Dubna, Russia

Expressed of Interest: INFN Italy (Torino), Belorussia (Gomel States University), Moscow States University, St. Petersburg (Gatchina), ITEP Moscow

17 National center of Particle and High Energy Physics, Belarusian State University, Minsk

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JINR in Spin Studies

Started in early 50-th from:- experiments at Laboratory of Nuclear Problems with polarized beams and targets at

Synchrocyclotron, -pioneering Development of super-frozen polarized targets (next slide), -experiments at Serpukhov 70 GeV proton Synchrotron, -experiments at Synchrophasotron with movable polarized

target and other fixed target experiments.Continued with JINR participation in Nucleon Spin structure experiments: SMC, COMPASS-I, COMPASS-II (SPS CERN), HERMES (DESY), STAR (BNL). Accompanied by theoretical developments (Lapidus, Ryndin, Kopeliovich, Efremov, Teryaev, Sidorov, Goloskokov…) and Organization of biannual International Spin Workshops DSPIN (1981-2013), SPIN2012 conference, DSPIN 2013: http://theor.jinr.ru/~spin/2013/

03.06.2014

Historical remarque

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Made in JINR: polarized targets •Pioneering development of frozen targets

• by group of B.Neganov at Dubna in 1965 • has reached the required super low temperature of ~20 mK.

Based on his idea of dilution of He3 in He4 (the dilution refrigerator)

• • B.Neganov, N.Borisov and M.Liburg, Sov.Phys. JETP23 (1966)959

• The first frozen polarized target in the experiments at the Synchrocyclotron

B.S.Neganov1928-2012

03.06.2014

Historical remarque

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Outline(LoI)

03.06.2014

2. Physics motivations

2.1 Twist-2 PDFs of the nucleon 2.2. Nucleon spin structure studies using the Drell-Yan mechanism 2.3. New nucleon PDFs and J/Ψ production mechanisms. 2.4. Direct photons. 2.5. Spin-dependent high-pT reactions.

2.6. Spin-dependent effects in elastic pp and dd scattering. 2.7. Spin-dependent reactions in heavy ion collisions.

3. Requirements to the NUCLOTRON-NICA complex

4. Requirements to the Spin Physics Detector (SPD) 4.1. Event topologies. 4.2. Possible layout of SPD. 4.3. Trigger system. 4.4. Local polarimeters and luminosity monitors. 4.5. Engineering infrastructure. 4.6. DAQ. 4.7. SPD reconstruction software. 4.8. Monte Carlo simulations. 4.9. Slow control. 4.10. Data accumulation, storing and distribution.

5. Proposed measurements with SPD

5.1. Estimations of DY and J/Ψ production rates. 5.2. Estimations of direct photon production rates. 5.3. Rates in high-pT

reactions. 5.4. Rates in elastic pp and dd scattering. 5.5. Feasibility of the spin-dependent reaction studies in heavy ion collisions.

6. Time scale of the Project

7. Conclusion

2. Physics motivations

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Basic twist-2 PDFs of the nucleon

03.06.2014

Sivers

Boer–Mulders

Transversity

8

Pretzelosity

• Taking taking into account the quark intrinsic transverse momentum kT ,

at LO 8 PDFs are needed for a full description of the nucleon structure• Vanish upon integration over kT except f1 , g1 , and h1

chiral -oddT -odd

aka

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Definitions of twist-2 PDFs of the nucleon

03.06.2014

f1 - density of partons in non-polarized nucleon, (x, Q2); g1 - helicity , longitudinal polarization of quarks in longitudinally polarized nucleon; h1 -- transversity, transverse polarization of quarks in transversely polarized nucleon ;f┴

1T - Sivers, correlation between the transverse polarization of nucleon (transverse spin) and the transverse momentum of non-polarized quarks; g┴

1T - worm-gear-T, correlation between the transverse spin and the longitudinal quark polarization ; h┴

1 - Boer-Mulders, distribution of the quark transverse momentum in the non-polarized nucleon ; h┴

1L - worm-gear-L, correlation between the longitudinal polarization of the nucleon (longitudinal spin) and the transverse momentum of quarks ; h┴

1T - pretzelosity, distribution of the transverse momentum of quarks in the transversely polarized nucleon

10QUARKS2014

measured from Deep Inelastic lepton Scattering (DIS) l + N l’ +X, nucleon can be polarized .

,'''

222

dEd

dSS

dEd

d

dEd

d pol

eN

unpSS Ne

R(x,Q2) and F2(x,Q2) have been measured by the collaborations SLAC, EMC, BCDMS, NMC, ZEUS, H1 and others.In QCD:F2 (x, Q2) = x∑q e2

q [q(x, Q2) + anti-q(x, Q2)], q=u, d, s. f1 PDFs for each parton are determined from the QCD analysis of all DIS data.

unp

unpd

dxdQ Q xF x Q y

y y

R x Q

2

2

2

4 22

2 2 2 2

2

41

4

1

2 1( , )

( )

( ( , ))

Status of f1 and g1 PDFs

Parton (density) distributions in non-polarized nucleons at Q2=10 GeV2 vs. x.

f1

03.06.2014

11QUARKS2014

g1 measured from pol separated off tot in so-called asymmetries.

The cross sections difference, //, for two opposite longitudinal target polarizations is given by the expression:

,242

116

2

2

1

22

4

2

2//

2

//

g

yg

yy

Q

y

dxdQ

d pol

connected with the longitudinal asymmetry, A// , defined as

unpA

2//

//

which, in the first approximation, related to g1: A// /D ≈ A1 ≈ (g1 –γ2 g2)/F1 ≈ g1 /F1,

The QPM expression for virtual photon asymmetry A1:

.

A

e q x q x

e q x q xp

p p

p p

i i i

i i i

11 2 3 2

1 2 3 2

2

2

/ /

/ /

( ) ( )

( ) ( )

.

g x e q x q xii

i i12( ) ( ) ( )

Status of f1 and g1 PDFs

03.06.2014

1203.06.2014 QUARKS2014

F2(x,Q2) g1(x,Q2)

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Status of PDFs: global analyses

Parton density distributions in non-polarized nucleons at

Q2=10 GeV2 vs x.

Parton helicity distributions in longitudinally

polarized nucleonat Q2=10 GeV2 vs

x

03.06.2014

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The knowledge about the transversity & Sivers PDFs is rather limited

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Collins asymmetry

COMPASS & HERMES results

03.06.2014

q

hq

qq

q

hq

qq

Dfe

Hhe

112

112

CollA

transversity PDF

Collins FF

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Sivers asymmetry

COMPAS &HERMES results

03.06.2014

q

hq

qq

q

hq

qTq

Dfe

Dfe

112

112

SivA

Sivers PDF

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Global fit result: COMPASS & HERMES &

BELL

03.06.2014

Global fit result: COMPASS &

HERMES & unpol. FF

Transversity PDF

Sivers PDF

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No data : Pretzelosity PDF h┴1T Worm-gear-L h┴

1L Worm-gear-T g┴1T Boer-Mulders h┴

1

03.06.2014

N.B.The pretzelosity PDF would give new information on possible role of the constituent’s orbital momenta in resolution of the nucleon spin crisis. It should be noted that Sivers PDF sensitive to orbital angular momentum also.

Concluding, one can summarize that precision measurement at NICA the

collinear and TMD PDFs can be the main subject of the NICA SPD spin program.

19

2.2. Nucleon structure studies using the Drell-Yan mechanism

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The parton model diagrams of the di-lepton production in collisions of hadrons Ha (Pa ,Sa) with hadrons Hb (Pb ,Sb) . The constituent quark (anti-quark) of the hadron Ha

annihilates with constituent anti-quark (quark) of the hadron Hb producing the virtual

photon which decays into a pair of leptons l± (electron-positron or µ±). The hadron spectator systems Xa and Xb are usually not detected. Both diagrams have to be taken

into account.

where Pa (Pb) and Sa (Sb) are the momentum and spin of the hadron Ha (Hb), while l

(l’) and λ (λ’) are the momentum and spin of the lepton, respectively.

20

Lepton plane

Polarization plane

Collins-Soper plane

The kinematics of the Drell-Yan process is considered usually in the Collins-Soper (CS) reference frame [ J.C. Collins, D.E. Soper, and G. Sterman, Nucl. Phys. B250, 199 (1985).]

Results of the most complete theoretical analysis of this process [S. Arnold, A. Metz and M. Schlegel, Phys.Rev. D79 (2009) 034005 [arXiv:hep-ph/0809.2262] are used .

03.06.2014 QUARKS2014

21

2

2 2

2 1 2 cos2 sin 2 sin 2

sin( ) sin(3 ) sin( )2 2

4

2 2(1 cos ) sin cos 2 sin sin 2 sin sin 2

sin( ) 1 cos sin sin(3 ) sin( )

sin

{S S Sa a a

a a a

a b T

UU UU aL LU bL UL

aT S TU S TU S TU

bT

d

dx dx d q d Q

F F S F S F

S F F F

S

sin( ) sin(3 ) sin( )2 2

2 1 2 cos2

( ) 1 cos sin sin(3 ) sin( )

1 cos sin cos 2 (2.1.2)

S S Sb b b

b b bS UT S UT S UT

aL bL LL LL

F F F

S S F F

S

cos( ) cos(3 ) cos( )2 2

cos( ) cos(3 ) cos( )2 2

cos( ) 1 cos sin cos(3 ) cos( )

cos( ) 1 cos sin cos(3 ) cos( )

S S Sb b b

b b b

S S Sa a a

a a a

aL bT S LT S LT S LT

aT bL S TL S TL S TL

aT b

S F F F

S S F F F

S S

cos(2 ) cos( )2

cos( ) cos(4 )2

cos(2 )2

1 cos cos(2 ) cos( )

sin cos( ) cos(4 )

sin cos(2 )

S S S Sa b b a

a b b a

S S Sa Sa b b

a b a b

S Sa b

a b

T S S TT S S TT

aT bT S S TT S S TT

aT bT S S TT

F F

S S F F

S S F

cos(2 )cos(2 ) }S Sa b

a bS S TTF

2 2 2 22, , and

2 2y y

a b Ta b

q q q qx e x e q q

P q s P q s

, y is the cm rapidity.

are the SFs, depend on four variables Pa ·q, Pb ·q, qT and q2 or on qT , q2 and the Bjorken variables of

colliding hadrons, xa , xb ,

.

ijF

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The X-section of the DY pair’s production in the QPM via LO PDFs is rewritten by us in the more convenient variables with a change of notations of the azimuthal angles corresp. to CS rf.

22

2 2 2 21 2

2 2 2 21 2 1 2

1( , ) ( ) ( , )

( , ) ( , ) ( , ) ( , ) ,

aT bT q aT bT T aT bT aT bTqc

q a aT q b bT q a aT q b bT

C w k k f f e d k d k q k k w k kN

f x k f x k f x k f x k

where kaT (kbT) is the transverse momentum of quark in the hadron Ha (Hb)

and f1 (f2) is a TMD PDF of the corresponding hadron.

The equation on previous slide include 24 leading twist SFs. Each of them is expressed through a weighted convolution, C, of corresponding leading twist TMD PDF in the transverse momentum space:

Expressions for all leading twist SFs of quarks and antiquarks are given in the text of LoI. f.e. in the unpolarized case:

1 cos 21 1 1 1

2( )( ), ,aT bT aT bT

UU UUa b

h k h k k kF C f f F C h h

M M

where h┴ 1 is the Boer-Mulders PDF for quarks & anti-quarks.

03.06.2014 QUARKS2014

cos 2

sin 2

sin 2

00

00int

0 0

0 0int int

0 0

0 0int int

0 0sin(3 )sin( )

0 0int int

1(1 cos 2 )

2

| |sin 2

2

| |sin 2

2

| |sin( ) s

2SS aa

a

UU UU

aLLU LU

bLUL UL

aTTU TU S TU

A D A

SA D A

SA D A

SA A D A

sin( )

0 0sin(3 ) sin( )sin( )

0 0int int

int int int int

in(3 ) sin( )

| |sin( ) sin(3 ) sin( )

2

|

Sa

a a

S SS b bb

b b b

S TU S

bTUT UT S UT S UT S

aLLL

A

SA A D A A

SA

1 cos2

cos(3 )

cos( )

cos( )int int int int

|cos 2

2

cos(3 )| |cos( )

2 cos( )

Sa

aSa

a Sa

a

bLLL LL

TL SaT bLTL TL S

TL S

SA DA

AS SA A D

A

cos(3 )

cos( )

cos( )int int int int

int int int int

cos(3 )| |cos( )

2 cos( )

|

Sb

bSb

b Sb

b

LT SaL bTLT LT S

LT S

aTTT

AS SA A D

A

SA

cos(2 ) cos( )

cos( ) cos(4 )

cos(2 ) cos(2 )

|| |cos(2 ) cos( )

2

cos( ) cos(4 )

cos(2 ) cos(2

(

[ S S S Sa b b a

a b b a

S S S Sb a a b

a b a b

S S S Sa b a b

a b a

bTTT S S TT S S

TT S S TT S S

TT S S TT S

SA A

D A A

A A

) (2.1.10))] bS

8 asymmetries to be measured: ALU, AUL, ATU , AUT, ALL, ATL, ALT, ATT

2303.06.2014 QUARKS2014

24

Applying the Fourier analysis to the measured asymmetries, one can separate each of all ratios .1i i

jk jk UUA F F

Extraction of different TMD PDFs from these ratios is a task of the global analysis since each of the SFs is a result of convolutions of different TMD PDFs in the quark transverse momentum space. For this purpose one needs either to assume a factorization of the transverse momentum dependence for each TMD PDFs, or to transfer them to impact parameter representation and to use the Bessel weighted TMD PDFs.

In above expressions: cross section σpq with superscripts: horizontal arrows - for positive (negative) longitudinal beam polarizations, vertical arrows - for transvers beam polarization , 0 - for the non-polarized hadr .

2 2sin (1 cos )D 1i i

jk jk UUA F F --amplitude of SF modulation

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25

The large number of independent SFs to be determined from the polarized DY processes at NICA (24 for identical hadrons in the initial state) is sufficient to map out all eight leading twist TMD PDFs for

quarks and anti-quarks.

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This fact indicates the high potential of the polarized DY process for studying new PDFs. This process has also a certain advantage over

SIDIS which also capable of mapping out the leading twist TMD PDFs

but requires knowledge of fragmentation functions.

1UTF 1

TUFThe transverse single spin asymmetries depending on the Structure Functions

are of the particular interests. The both SFs contain the Sivers PDF which was predicted to have the opposite sign in DY as compared to SIDIS. As the sign reversal is at the core of our present understanding of transverse single spin asymmetries in hard scattering processes, the experimental check of this prediction is of the utmost importance.

26

A number of conclusions can be drawn comparing some asymmetries to be measured. Let us compare the measured asymmetries ALU and AUL and assume that during these measurements the beam polarizations are equal, i.e. |SaL|=|SbL| and hadrons a,b are identical. Then one can intuitively expect that the integrated over xa and xb asymmetries ALU = AUL.

Similarly, comparing the asymmetries ATU and AUT or ATL and ALT one can expect that FTU = FUT and F TL = FLT . Tests of these expectations would be a good check of the parton model approximations.

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27

Future DY experiments in the world

03.06.2014 QUARKS2014

Experiment CERN,COMPASS-II

FAIR,PANDA

FNAL, E-906

RHIC,STAR

RHIC-PHENIX NICA,SPD

mode fixed target fixed target fixed target collider collider collider

Beam/target π- , p anti-p, p π- , p pp pp pp, pd,dd

Polarization:b/t 0; 0.8 0; 0 0; 0 0.5 0.5 0.9

Luminosity 2·1033 2·1032 3.5·1035 5·1032 5·1032 1032

√s , GeV 14 6 16 200, 500 200, 500 10-26

x1(beam) range 0.1-0.9 0.1-0.6 0.1-0.5 0.03-1.0 0.03-1.0 0.1-0.8

qT, GeV 0.5 -4.0 0.5 -1.5 0.5 -3.0 1.0 -10.0 1.0 -10.0 0.5 -6.0

Lepton pairs, μ-μ+ μ-μ+ μ-μ+ μ-μ+ μ-μ+ μ-μ+, e+e-

Data taking 2014 >2018 2013 >2016 >2016 >2018

Transversity NO NO NO YES YES YES

Boer-Mulders YES YES YES YES YES YES

Sivers YES YES YES YES YES YES

Pretzelosity YES (?) NO NO NO YES YES

Worm Gear YES (?) NO NO NO NO YES

J/Ψ YES YES NO NO NO YES

Flavour separ NO NO YES NO NO YES

Direct γ NO NO NO YES YES YES

28

2.4. Direct photons.Direct photon productions in the non-polarized and polarized pp (pd) reactions

provide information on the gluon distributions in nucleons

Vertex H corresponds to q + qbar →γ+X or g+q→γ+X hard processes.

One can show that the polarized gluon distribution (Sivers gluon function) can be extracted from measurement of the transverse single spin asymmetry AN

of order few %.Via double spin asymmetry ALL

a gluon polarization in the nucleon:

03.06.2014 QUARKS2014

29

2.7. Spin-dependent reactions in heavy ion collisions

Transverse polarization PN vs. xF of Λ from the reaction Au+Au→ Λ↑ +X at RHIC

Predictions for PN vs. η for the reaction A1+A2→ Λ↑ +X at √s=7 and 9 GeV

Au+Au Cu+Cu S+S

Systematic studies of inclusive transverse polarizations of hyperons and vector mesons vs. kinematic variables, energy and atomic weight of colliding beam can be performed at SPD.

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From a theoretical point of view the origin of sizable hyperon polarization in p+A and A1+A2 collisions represents a significant problem since in the perturbative QCD it is expected to be small

Chromo-Magnetic Polarization of Quarks

(CMPQ) model

The hyperons & vector mesons polarization have asignificant size (?)

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3. Requirements to the NUCLOTRON-NICA complex

03.06.2014

Beams. The following beams will be needed, polarized and non-polarized: pp, pd, dd, pp, pd , pp, pd , dd.Beam polarizations both at MPD and SPD: longitudinal and transversal. Absolute values of polarizations should be (90-50)%.The life time of the beam polarization should be long enough ≥24h. Measurements of Single Spin and Double Spin asymmetries in DY require running in different beam polarization modes: UU, LU, UL,TU, UT,LL ,LT and TL (spin flipping for every bunch or group of bunches should be considered).

Beam energies: pp(spp ) = 12 ÷ ≥ 27 GeV (5 ÷ ≥12.6 GeV kinetic energy), dd(sNN) = 4 ÷ ≥13.8 GeV (2 ÷ ≥5.9 GeV/u ion kinetic energy).Asymmetric beam energies should be considered also.

Beam luminosities: in the pp mode: Laverage 1·1032 cm-2s-1 (at spp = 27 GeV), in the dd mode: Laverage 1·1030 cm-2s-1 (at sNN = 14 GeV).

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The NICA Complex

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Possible NICA structure for polarized proton and deuteron beams

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The novel scheme of the polarization control at NICA, suitable for protons and deuterons, is based on the idea of manipulating polarized beams in the vicinity of the zero spin tune. This approach is actively developed at JLAB for the 8-shaped ring accelerator project. The zero spin tune is a natural regime for the mentioned case. To provide zero spin tune regime at the collider of the racetrack symmetry, it is necessary to install two identical Siberian snakes in the opposite straight sections

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NICA pp-collisions peak luminosity

29 November 2012 (I.N.Meshkov)

The number of particles reaches a value about 2.2∙1013 in each ring and the peak luminosity reaches Lpeack = 2∙1032 cm-2s-1 at 12.7 GeV

03.06.2014

3403.06.2014 QUARKS2014

4. Requirements to the spin physics detector (SPD)

Possible layout of SPD includes more or less standard detectors. To minimize the time and the cost of the Project the versions of already

developed and produced detectors for another experiments as COMPASS, PANDA, MPD-

NICA etc. should be used as much as possible

ECAL

TRACKIG, STRAW & DC

VERTEXDETECTOR,SILICON

HADRON & MUON DETECRORS

Fig. 5.13: possible view of SPD with the solenoid magnet.

The “almost 4π geometry” requested by DY and direct photons can be realized in the solenoid version of SPD if it has overall length and diameter of about 6 m.

3503.06.2014 QUARKS2014

solenoid

toroid

Magnet

36

Vertex detector The most obvious version of vertex detector (VD) is a silicon one. Several layers of double sided silicon strips can provide a precise vertex reconstruction and tracking of the particles before they reach the general SPD tracking system. The design should use a small number of silicon layers to minimize the radiation length of the material. With a pitch of 50-100 µm it is possible to reach a spatial resolution of 20-30 µm. Such a spatial resolution would provide 50-80 µm for precision of the vertex reconstruction. This permits to reject the secondary decay vertexes.

To minimize a background in the DY dimuon sample from π- µ decays, the first detection plane of VD should be as close to the beam as possible.

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37

There are several candidates for a tracking system: conventional drift chambers (DC) and their modification – thin wall drift tubes (straw chambers). The DCs are the good candidates for tracking detectors in the end cup parts of SPD, while straw chambers are the best for the barrel part.

Two groups have developed the technology of straw chamber production at JINR with two-coordinate reed out.

03.06.2014 QUARKS2014

The radial coordinate determination is organized via the electron drift time measurement while the measurement of the coordinate along the wire (z-coordinate) uses the cathode surface of the straw. Both technologies provide a radial coordinate resolution of 150-200 µm per plane.

Tracking

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Requirements- Photon energy range 0.2- 30 GeV- Size: 360cm x 360cm ;- Granularity 4x4 – 6x6 cm2

- Energy resolution < 10.0%/√E (GeV)   

- Thickness < 50 cm, - AMPD readout,Insensitive to the magnetic field.     

DVCS+BHEC

AL1&

2

New large-angle electromagnetic calorimeter for COMPASS is a good candidate for SPD also

AMPD, Avalanche Micropixel Photo Diodes,3 x 3 mm2, density of pixels 40 000/mm2251mm or 15 radiation length

342 mm

Total length 470mm with electronics

new shashlyk modules for tests in 2011109 plates made of Sc 0.8 mm /Pb 1.5 mm

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39

Hadron (muon) detectors A system of mini-drift chambers interleaved with layers of iron and called the Range System (RS) is developed at JINR for FAIR/PANDA . It can be used in the barrel part of SPD as a hadron and (or) muon detector

The hadron and muon detectors in the end caps part of SPD are to be identified. As candidates for these detectors, the COMPASS muon wall can be considered. It consists of two layers of mini-drift chambers with a block of absorber between them.

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We propose to perform measurements of asymmetries of the DY pairs production in collisions of polarized protons and deuterons which provide an access to all collinear and TMD PDFs of quarks and anti-quarks in nucleons. The measurements of asymmetries in production of J/Ψ and direct photons will be performed simultaneously with DY using dedicated triggers. The set of these measurements will supply complete information for tests of the QPM of nucleons at the twist-two level with minimal systematic errors.

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5. Proposed measurementswith SPD.

Typical di-lepton invariant mass spectrum

To estimate the precision of measurements, the set of original software packages for MC simulations, including generators for Sivers , Boer-Mulders and transversity PDFs were developed. With these packages we have generated a sample of 100K D Y events

(~ 1 year of data taking) for comparison with expected asymmetries.

41

5.1. Estimations of DY production rates

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Cross section (left) and number of DY events (right) versus the minimal invariant mass of lepton pair for various proton beam energies.

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5.1. DY, J/ and total pp X-sections

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Ös , GeV 24 26 Ös , GeV 24 26sJ/y ∙ Be+e- , nb 12 16 sDY , nb 0.06 0.07

Events“per year” 18·106 23·106 Events“per year” 92·103 142·103

Cross section of pp interaction versus s

In the energy range of NICA the total cross section of pp interactions is almost constant, about 40 mb. The expected event rates at the luminosity1032 sm-2 s-1 will be 4·106 per second.

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5.1. Projections for Sivers & Boer-Mulders asymmetries

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sin( ) TS

N

qw

MUTA

s

Estimated Sivers asymmetry

Numbers I, II, III denote corresponding fits.

sin( ) TS

N

qw

MUTA

Estimations of Boer-Mulders asymmetry

The solid and dotted curves correspond to the first and second versions of the evolution model, respectively..

=26 GeV and Q2 = 15 GeV2. Points show the expected errors obtained with 100K of events.

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5.2. Estimations of direct photon production rates

AN and ALL could be measured at SPD with statistical accuracy ~0.11% and ~0.18%, respectively, in each of 18 xF bins (-0.9< xF < +0.9).

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Large statistics of events provide opportunities to measure the asymmetries as a function of xF and pT.

45

3. Presentation of LoI at the JINR PAC on particle physics is foreseen for 25 June 2014.

4. The list of participants still is open for interested people.5. The draft of LoI is available on request (Igor.Savin@cern.ch)

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CONCLUSION

1. The comprehensive program of the nucleon structure study is suggested. It can be realized at NICA using the polarized proton and deuteron beams. The text of LoI is almost complete.

2. The participants of the LoI have submitted the document for an extensive discussions at JINR

EU-Russia-JINR @ Dubna Round Table, Dubna, 3-5 March LHEP Seminar, 7 March & LHEP NTS, 20 March & LNP Seminar, 23 April & LIT Seminar, 24 April & LTPH Seminar, 22 May & NTS JINR, 23 May

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FT experiment area

Nuclotron

Lu 20Booster

New Linac

New collaborators, welcome!

NICA accelerator complex

Collider

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47QUARKS201403.06.2014

48QUARKS201403.06.2014

NICA construction works looks feasible.

Back up slides

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QUARKS2014 50

New spin physics facility at JINR.

JINR developing the new accelerator facility “NICA Complex”

providing intensive beams of relativistic ions up to Au with max energy up to √SNN= 11 GeV (Au79+) and polarized protons and

deuterons .

Main targets of “NICA Complex” studies:

- hot and dense baryonic matter,

- nucleon spin structure,

- polarization phenomena in heavy ion collisions

in fixed target and collider experiments. For last ones: pp spp = 12 ÷ 27 GeV (5 ÷ 12.6 GeV kinetic energy )

dd sNN = 4 ÷ 13.8 GeV (2 ÷ 5.9 GeV/u ion kinetic energy )

Laverage 1·1032 cm-2s-1 (at spp = 27 GeV) 03.06.2014

1970 1980 1990 2000

SLAC

CERN

DESY

JLab

RHIC

Nucleon spin structure: a worldwide effort before TMD era

E80

EMC SMC COMPASS I

E130 E142/3 E154/5

HERMES

CLAS/HALL-A

Phenix/Star

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2010

1987 EMC Where does the proton really get its spin? Till now the “spin crisis” persists………….

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Collins asymmetry and Global fit

fit to HERMES p, COMPASS p and d, Belle e+e- dataM. Anselmino et al., arXiv:1303.3822 2013

2010 p data

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Infrastructure. The infrastructure of the Nuclotron-NICA complex should include:- a source(s) of polarized (non-polarized) protons and deuterons,- a system of polarization control and absolute measurements (3-5%),- a system of luminosity control and absolute measurements,- a system(s) of data distribution on polarization and luminosity to the experiments.The infrastructure tasks should be subjects of the separate project(s).

Beams intersection area. The area of ± 3m along and across of the beams second intersection point, where the detector for the spin physics experiment will be situated, must be free of any collider elements and equipment. The beam pipe diameter in this region should be minimal, 10 cm or less, to guaranty the angular detector acceptance close to 4π. The walls of the beam pipe in the region ± 1m of the beams intersections should have a minimal thickness and made of the low-Z material (Be?).

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NICA complex beams

10³²

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What is known : basic Parton Distribution Functions

q(x)f1

q (x)

Dq(x) g1

q(x)

DTq(x)

h1q(x)

poorly known – polarized SIDIS

unpolarized PDFquark/gluon with momentum xP in a nucleon well known – unpolarized DIS

helicity PDFquark/gluon with spin parallel to the nucleon spin in a longitudinally polarized nucleon known – polarized DIS

transversity PDF quark with spin parallel to the nucleon spin in a transversely polarized nucleon

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three distribution functions - twist-2 PDFs - are necessary to describe the spin structure of the nucleon at LO in the collinear case

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Extraction of unknown (poor known) parton distribution functions (PDFs):

Boer-Mulders PDF

Sivers PDFs (Efremov,… PLB 612 (2005), PRD

73(2006));

Transversity PDF (Anselmino, Efremov, …)

Transversity and first moment of Boer-Mulders PFDs (Sissakian, Shevchenko, Nagaytsev , Ivanov, PRD 72(2005),

EPJ C46 ,2006 C59, 2009)

Longitudinally polarized sea and strange PDFs and tenzor deuteron structure (Teryaev, …)

The same PDFs from J/y production processes ( ).

*( ) ( )p D p D X l l X *( ) ( )p D p D X l l X

*( ) ( )p D p D X l l X *( ) ( )p D p D X l l X

*( ) ( )p D p D X l l X

*( ) ( )p D p D X l l X

10s GeVA. Sissakian, O. Shevchenko, O. Ivanov, (Dubna, JINR). arXiv:0710.1791

Spin Physics at NICA

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