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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
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)
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
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
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