Photoreactions with Polarized HD target at SPring-8

1. SPring-8 Facility

2. Physics Motivation

3. HD projects: Polarized proton and deuteron target: HD

target project for complete polarization observables.

M. Fujwawa@EMI200919 September 2009, Moscow

Collaborators of HD projectK. Fukuda, M. Fujiwara, T. Hotta, H. Kohri, T. Kunimatsu, C. Morisaki, T. Ohta, K. Ueda, M. Uraki, M. Utsuro, M. Yosoi, (RCNP, Osaka)

S. Bouchigny, J.P. Didelez, G. Rouille(IN2P3, Orsay, France)

M. Tanaka(Kobe Tokiwa University, Japan)

Su-Yin Wang(Institute of Physics, Academia Sinica, Taiwan)

Super Photon ring – 8 GeV

• 8 GeV electron beam• Diameter ≈457 m• RF 508 MHz• One-bunch is spread

within ＝ 12 psec.• Beam Current = 100 mA• Life time 30 － 50 hours

Osaka – SPring-8: about 100 km,One hour highway drive.

Sapporo

TokyoNagoyaOsaka

RussiaChina

South Korea

North Korea

Back Compton Scattering

Back Compton scattering

Incident electrons Ee

Incident Photons El

Scattered electrons

Scattered photons E

: Electron velocity /cL: Incident angle of laser photon

: Scattered angle of photon

e

cos1cos1

cos1

EE

EE

Llaser

Llaser

Energy of BCS photons

22

2

41

4

mcE

EE

l

l

Head-on collision (L=0)

ex. Ee=8 GeV, (Laser =351 nm)

2.4 GeV Maximum

LEPS facility

b) laser hutch

a) SPring-8 SR ring

c) experimental hutch

Laser light

8 GeV electron

Recoil electron

Electron tagging

Collision

Inverse Compton -ray

M. Fujiwara, Nuclear Physics News 11 (2001) 28-32.

Laser System• 351 nm Ar laser

（ multi-line UV, 4 W ） 106 photons/sec on target

• Linearly polarized laser beam

Polarized LEP beam

~95% at 2.4 GeV

tagged

351 nm257 nm

Energy spectrum

tagged

351 nm257 nm

Linear Polarization

LEPS spectrometer

Liquid HydrogenTarget (15 cm thick)

AerogelCherenkov(n=1.03)

Start counter

Silicon VertexDetector

Dipole Magnet (0.7

T)

MWDC 1

MWDC 2 MWDC 3

1m

TOF wall

Missing mass spectrum

• p(,K+) (1116)

• p(,K+)0 (1193)

• 1.5 ~ 2.4 GeV

• 0.6 < coscm < 1

Photon beam asymmetry

Photon beam asymmetry

N : K+ photoproduction yield : K+ azimuthal angle

P : Polarization of photon

n : Normalization factor for Nv For all events

R. Zegers et al., Phys. Rev. Lett. 91 (2003) 092001.M. Sumihama et al., C 73 (2006) 035214.H. Kohri et al., Phys. Rev. Lett. 97 (2006) 082003.

)2cos(1:

)2cos(1:

Pd

d

d

dHorizontal

Pd

d

d

dVertical

unpol

unpol

)2cos(

PNnN

NnNR

hv

hv

LEPS experiments (2000 – 2009)

Published Papers from LEPS@SPring-8(Results from polarization observables in Red)

2003 1. p -> K+ p -> +0 R. G. T. Zegers et al. Phys. Rev. Lett. 91 092001 2. Pentaquark search T. Nakano et al. Phys. Rev. Lett. 91 012002 2005 3. meson production Li, C, Al, Cu T. Ishikawa et al. Phys. Lett. B 608 215 4. meson production proton target T. Mibe et al. Phys. Rev. Lett. 95 182001 2006 5. p -> K+, p -> K+0 M. Sumihama et al. Phys. Rev. C 73 035214 6. n -> K+- H. Kohri et al. Phys. Rev. Lett. 97 082003 2007 7. p -> p0p M. Sumihama et al. Phys. Lett. B 657 32 8. p -> K+ K. Hicks et al. Phys. Rev. C 76 042201(R) 2008 9. d -> d W.C. Chang et al. Phys. Lett. B 658 209 10. p -> K+(1405), 0(1385) M. Niiyama et al. Phys. Rev. C 78 0352022009 11. Pentaquark search T. Nakano et al. Phys. Rev. C 79 025210 12. p -> K+0(1385) K. Hicks et al. Phys. Rev. Lett. 102 012501 13. p -> K+(1520) N. Muramatsu et al. Phys. Rev. Lett. 103 012001 14. p -> K+(1520) H. Kohri et al. arXiv:0906.0197

Physics motivation

We challenge current controversial problems in hadron physics.

1. Hidden strangeness content study via

2. To investigate the bump structure in excitation energy observed inmeson photoproduction.

3. To investigate the bump structure in excitation energy observed in K+(1520) photoproduction from the proton.

4. Others from the complete polarization observables in photoreactions.

)( nnpp

1. Hidden Strangeness Content World data indicating strangeness content in the nucleon

• Nucleon structure function obtained by the lepton deep inelastic scattering and 　　 elastic p scattering indicate that the amount of spin carried by ss is comparable 　　 to that carried by u and d quarks.

• Analysis of N sigma term suggests proton contains 20% strange quarks.

• Annihilation pp X reaction at rest shows strong violation of 　　 OZI(Okubo-Zweig-Iizuka) rule.

HERMES semi-inclusive DIS data

A. Airapetian et al. Phys. Rev. Lett. 92 012005 (2004)

Previous datas ~ -0.10 +- 0.04 K. Abe et al. PRL 74 346 (1995)

s ~ -0.12 +- 0.04 D. Adams et al. PLB 329 399 (1994)

New DataStrange quark contribution is found to be small.

This simple picture depicts pairs of strange quarks as they pop into and out of existence alongside the permanent quark residents of the proton. Nuclear physicists have found that strange quarks, though present for just tiny fractions of a second at a time, also contribute to the proton's properties. Image: JLab

SPIN CRISIS at least 10% ss content in nucleon

G0 experiment at JLAB: Anapole moment

Z0

e

e

http://www.jlab.org/div_dept/dir_off/public_affairs/news_releases/2005/gzero.html

electroweak process

nucl-ex/0506021

HAPPEX (JLab) parity violating elastic ep scattering

A. Acha et al. Phys. Rev. Lett. 98 032301 (2007)

Electric strangeform factor

Magnetic strangeform factor

Strange quark distribution

A. Airapetian et al. HERMES collaboration PLB 666 (2008) 446

Fig. 3. The strange parton distribution xS(x) from the measured Hermes multiplicityfor charged kaons evolved to Q 0

2= 2.5 GeV2 assuming The solid curve is a 3-parameter fit forfor S(x) = x−0.924e−x/0.0404(1 − x), the dashedcurve gives xS(x) from Cteq6l, and the dot–dash curve is the sum of light antiquarksfrom Cteq6l.

.13.027.1 dzDKS

meson photoproduction @ LEPS of SPring-8

Studying diffractive channels as a tool for non-perturbative QCD (Pomeron structure, search for glueball, f2’-meson trajectories, etc )

Search for exotic processes as ss-knockout

Henley et al. [94]Titov, Yang, Oh [94-98]

Non-polarized observablesare not suitable for this study

ss contents in proton

・　 -meson: ~ ss

pp

pomeron exchange + exchange + ss knock-out

Study small amplitudes by interference double polarization asymmetry

Reconstructed events (K+K- event)

Missing mass (,K+K-)X (GeV)

eve

nts

/2

.5M

eV

Proton(938)

=10 MeV

Invariant mass (K+K-) (GeV)

even

ts /2

.5M

eV

Inva

rian

t mas

s sq

uar

e (

K+K

- ) (G

eV2)

Invariant mass square (K-p) (GeV2)

Selections for event (KK mode) |M(KK)-M |< 10 MeV |MM((,K+K-)X)- Mproton|< 30 MeV

Beam-target asymmetry and exotic processes with unnatural parity exchange ( -knockout)ss

LEPS, Spring-8 (calculated by Titov)with 1% ss-bar content

Physics motivation 2To investigate the bump structure found

in meson photoproduction

Diffractive meson photoproduction on proton

T. Mibe, W. C. Chang, T. Nakano et al. Phys. Rev. Lett. 95 182001 (2005)

Bump

Physics motivation 3To investigate the bump structure found in K+(1520)

photoproduction from the proton 　

Solid curve : with N* by Nam et al.Dashed curve : without N*

by Nam et al.Dotted curve : without N* by Titov et al.

Comparison with calculations based on effective Lagrangian approach

Bump

Bump

p → K+X

Complete Polarization Observables are needed !

H. Kohri et al. LEPS collaboration arXiv: 0906.0197 (2009)

4. Otherp p p p p p p p ’

M. Sumihama et al. LEPS collaboration to be submitted.

p p

Experimental consideration for complete polarization observables

and

Instrumentation

Error estimation for CBT measurement

BGAp

Ap

BGABGp

BGABGp

BTC 2)()(

)()(

2

2

2

22

22222

)1()1(2

)1(1

BG

BG

p

p

BT

BTBT

BT

BT

R

R

RC

RCRCC

C

2/)(

Ap

BGR

Polarization in thermal equilibrium

BIgBH zN(B)

| -1/2>

|+1/2>

E=gNB

If I=1/2,

TkTkTE

TkTkTE

TkTkTE

T

E

ee

ee

NN

NNP

e

d

p

T

E

T

E

T

E

T

E

B0.672B2

0.000874B2Bg2

0.00102B2Bg2

)2k

tanh(

B

d

n

2k

Δ

2k

Δ

2k

Δ

2k

Δ

ｐ

ｐ

E

B=17T T=10mK,

Proton polarization 95%

Deuteron polarization 70%

Principle of HD

• Longstanding effort at Syracuse, LEGS/BNL ORSAY

• 10-20 mK• 15-17T• 80% for H, 20% for

D (vector)• 20%70% in D

with DNP

S. Bouchigny, C. Commeaux, J.-P. Didelez, G. Rouillé, Nucl. Instrum. Meth in Phys. Res. A 544 (2005) 417

When [HD]~99.5; T~500mk; B~1T

the relaxation time is about 20 hours.

Polarized HD NMR Coils

Solenoid Coil

Saddle coils

Liquid 3He (0.5 K)

Liquid 4He (4.2 K)

70 K Shield

Al Wires

HYDILE target @Orsay

Dilution refrigerator (DRS)Leiden Cryogenics

DRS-3000 (3He/4He dilution refrigerator)

Cooling power 　　 　

　　　 3000μW at 120 mK

Lowest temperature 　

　　　 6 mK

1220

mm

170mm

70m

m

Mixing Chamber

Nb3Sn joints&Protection Circuit

NbTi joints&Switch

Main Coil

Correction Coil

Null Coil

Rough dimensions of the magnet

400mm

600m

m

550m

m

1K Pot

538m

m

Dilution refrigerator (DRS)Superconducting magnet

Magnetic Field 　　　 17 Tesla

Homogeneity of Magnetic Field 5×10-4 for 15 cm

Magnetic Field (Tesla) Magnetic Field (Tesla)

Y Position (mm)

Y axis DRS

MagnetY Position (mm)

HDtarget

HD gas distillation systemPure HD gas of an impurity ~0.01% is needed for obtaininga long relaxation time. HD gas distillation system is still underdevelopment at RCNP

IBC 3He/4He Dilution RefrigeratorLowest temperature : 250 mKMagnetic field : 1 TeslaField homogeneity : 5 x 10-4 for target region

IBCIBC （（ In Beam CryostatIn Beam Cryostat ））

2.5cm

Al wire

5 cm

TC （ Transfer Cryostat ）

Road map (5 years from 2005 fiscal year) for Studies of Hardron structures

2008200720062005

（ DR ＋ SC magnet ）

2009 After 2010Fiscal year

Spin and parity determination of + particle

HD gas 、 IBC 、TRC 、 others

TRC

NMR

DR+IBC

SRC

New DR

Scintillator ball 、TPC Scintillator ball

Installation of new detectors

Roma2, ORSAY

HD at Spring-8 、meson production, K-production, hidden strangness of nucleon

New TPC

design

HD polarization

Charged meson productionExperiments with magnetic spectrometer

Polarized HD SPring-8

Collaboration with Roma2 、 ORSAY 、 US

Neutral particle detection withScintillator ball

total 92,507 kyen 103,000 103,000 93,000 93,000

New badget 83,505 96,000 96,000 86,000 86,000

totalAbout 480,000 kyen

IBC cryostat and newData taking system

Summary1. Physics Motivation of HD project at RCNP/Spring-8

2. CBT measurements with polarized target +p + p +pK+, K+ +p + p etc …..3. Present status of HD at RCNP

The first trial of the experiment will start from January 2010.

Your joining is really welcome!