Status of the SP8-GDH experiment Yamagata University Takahiro Iwata On behalf of the SP8-GDH...
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Transcript of Status of the SP8-GDH experiment Yamagata University Takahiro Iwata On behalf of the SP8-GDH...
Status of the SP8-GDH experiment
Yamagata UniversityTakahiro Iwata
On behalf of the SP8-GDH collaboration
2005.Oct.6 @QPAC at RCNP
• SP8-GDH proposal• Introduction of GDH sum rule• Status of the world data• Status of the SP8-GDH experiment• PT, IGD, ID, GD, …
Proposal : GDH experiment at SPring-8
• Study of the GDH sum rule for proton (measurement of helicity dependent photo-absorption cross-sections)
• Energy region: 1.8 ~ 2.4 GeV & 2.3 ~ 2.8 GeV• Circularly polarized gamma beam • Polarized polyethylene target • 4-detector system
• 1st double polarization experiment at SPring-8 • Approved in Oct. 2001 (QPAC )• Status: in preparation
SP8-GDH collaboration• Yamagata Univ. T.Iwata, H.Yoshida, Y.Tajima, S.Kato
• Miyazaki Univ. T.Mastuda, Y.Toi
• KEK S.Ishimoto
• SPring-8 Y.Ohashi
• Chubu Univ. N.Horikawa,
• Tohoku Univ. H.Shimizu, T.Ishikawa
• Melbourne Univ. M.Thompson, R.Rassool
• Royal Melbourne Institute of Technology M.Geso
• UCLA G.Igo, O.Tsai, C.Witten, S.Trentalange, V.Ghazikanian
• Bochum Univ. G.Reicherz, W.Meyer
• CUA F.Klein
GDH sum rule
• Gerasimov-Drell-Hearn sum rule
23/ 2 1/ 2 22
GDHN
I dm
p p
n n
,p ,
: photon energy
: pion threshold energy
: anomalous magnetic moment
( ) / 1.79
( 0) / 1.91
205 , 233
N N
N
GDH GDH nI b I b
• S.B.Gerasimov: Yad.Fiz. 2 (1965) 598 / Sov. J. Nucl. Phys. 2, 430(1966)• S.D.Drell and A.C.Hearn: Phys.Rev. Lett. 16, 430 (1966) • M.Hosoda and K.Yamamoto: Prog. Theor Phys. 36 (1966) No.2, Lett. to Editor 425
AnomalousMagnetic Moment(static property)
- Circularly polarized gamma &
polarized nucleon target
22 2 2
0
unsubtracted dipersion relation
mfef P d
2lim 0f
2 3/ 2 1/ 2
optical theorem
8mf
222 2
0
low energy theo
2
rem
ff
m
23/ 2 1/ 2 22
N
dm
GDH sum rule
ASSUMPTION:spin flip amplitudevanishes at infinite energy
General Principles
Lorenz invariance, gauge invariance, causality, relativity, crossing symmetry, analytic amplitude
Similar sum rules areformulated for any particles having non-zero spin !
Universal sum rule
spin non-flip spin fli
†2
p
1
Forward Compton Amplitud
[ ]
e
f f i if if f if
Derivation
GDH for proton
3/ 2 1/ 2
RUN
E
I E d
Running GDH integral
. .
2.9
226 5 12 RUN
stat sys
I GeV
b
GDH sum rule
205 b.tot
The running GDH integral overshoots the GDH prediction at 2.9 GeV by ~10%.
ELSA(Bonn)
MAMI(Mainz)
3 122
33P
13D
15F35 37 or ?F F
High-energy contribution
.tot
High-energy behavior evaluated by fitting DIS data with Regge parameterizations
Contribution above 2.9 GeV: Bianchi and Thomas: -14b Simula et al.: -13b
Total integral: . .(212 213) 5 12stat sys b
GDH sum rule 205 bIf the evaluations are correct, the sum rule is verified at 10% level.
SP8
Extrapolation to high energy is good?
3 122
3 122
GDH for neutron
phenomenological Regge approach
phenomenologicalanalyses with real photon data in resonance region
• Data analyses in resonance region give contrary results to GDH s.r.• Interesting to see neutron GDH
Data of neutron GDH• preliminary Mainz data ( < 800 MeV) • published Bonn data up to 1.8GeV large errors compared with proton data• no data above 1.8 GeV
SP8
3 122
neutron
Mainz dataO. Jahn, Proc.GDH2004 Bonn data[PRL 94,162001(2005)]
3 122
neutron
Objectives of SP8-GDH experimentMeasurements of for protonin the energy range of 1.8-2.8 GeVwith high precision and finer energy binning• confirmation of ELSA data ( with different technique) • study extrapolation to high energy
• Prospects• double pol. measurements in exclusive channels ( PT+TPC+LEPS configuration )• resonance studies with double polarization technique• new GDH data for neutron with pol.d target
• new proposal to be submitted • spin study of + : d
SP8-GDH SetupForward Detector(FD);TOF wall
InnerDetector(ID)
Gas Cerenkov(GC)
PT-Magnet
Polarized Target(PT)
Inner Gamma Detector(IGD)
Gamma beam
Large AngleDetector(LAD)
Forward GammaDetector(FG);lead-glass+ PWO
Large AngleGamma Detector(LAG);lead-plastic
1 m
geometrical acceptance97% of 4
Layout of experiment
PT: Yamagata + Bochum IGD: UCLAID: MelbourneLAD: YamagataLAG: YamagataGC: MiyazakiFD: YamagataFG: Tohoku+YamagataDAQ: Yamagata
responsibility
beam
Polarizedtarget
Magnetfor pol. target
modified part
final heat exchanger
still
microwave cavity
beam pipefinal heat exchangerswalls
outer pipe of the final HE
Polarized target • Modification of KEK-cryostat ongoing
• a few steps for final assembly
• Most parts ready except MC, waveguide
• NMR for pol. monitor made by Bochum
G.V. JIS150
JIS250
DN160
DN160
G.V.
RSV2000
R601H2060
JIS65
pipe d=76.3
flange O.D.=285
pipe d=267.4flange d=350
JIS250
JIS250
JIS65
~2500
~1000
3300
500
1400
300
300
2000
2000400
300 2000400
200
1000 2000200500
200
2000
500
500
~2500
100LDewar
200LDewar
EH12 00
EH500
EH80
EXP.hatch
He3
He4
Cryogenics system for polarized target at SPring-8
PT
He4 pump systemHe3 pump system
Inner Gamma Detector (IGD)
Designed and R&D by UCLA
26 layers of 5mm thick scintillators and 1.2mm thick lead sheets
Avalanche Photodiode readout1 APD/segment
10 MeV equiv. light outputO.Tsai(UCLA) invited to Yamagata by JSPS
for 10 month( from Nov. 2005)
Budget application to DOE (280k$)
• Charged particle detection• tile scintillators 25mm thick• 10 segments x 8 sectors
– 80 tiles in total– neighboring segments rotated by ha
lf a sector
• Readout: WLS fiber(d=1mm) + clear fiber(3m long)• 4-dimensional readout(32ch)• Multi-anode-PMT(16ch)• Melbourne group made prelimin
ary study • tiles to be made at Melbourne w
orkshop
Inner Detector (ID)
40cm
Gas Cherenkov CounterMiyazaki Univ. group in charge
Gas box constructedleak check OK.
Mirror design ongoing
Electron rejection
CO2 gas at 1 bar
Other detectors
• LAD (charged particle detection)– scintillator plate 20mm thick , 4 PMTs
• LAG ( gamma detection)– scintillator+ lead, WLS readout, 10 PMTs
• FD (charged particle detection)– TOF wall (LEPS)
• FG ( gamma detection)– scintillator+ lead, WLS readout, 20 PMTs– (or lead glass blocks borrowed from KEK)– PWO(LEPS)
Realistic design should be started soon
• Proton GDH– It is verified at 10% level at Mainz and Bonn– Confirmation of the data is necessary– Extrapolation to high energy is important
• Neutron GDH– No data is available above 1.8GeV
• SP8-GDH experiment can provide additional data for proton and new data for neutron
• Preparation of SP8-GDH– A few steps for completion of PT – Work for cryogenics system at SPring-8– Preparations of IGD, ID, GC are on the track– Others should be started.
• Funding is required for construction, installation and running• But , it is not reserved, yet.
Summary
GDH activities in the worldproton Neutron
MAMI 200-800MeV, complete 200-800MeV, completed
(D-butanole)
ELSA 0.68-2.9GeV, complete 0.8-1.8,complete(LiD)
JLAB 2.5-6GeV, proposed
GRAAL 0.5-1.5GeV,proposed,(HD) 0.5-1.5GeV, proposed (HD)
SLAC 4-40GeV, proposed
LEGS 130-470MeV, running,(HD) 130-470MeV, running,(HD)
SPring-8 1.8-2.8GeV, proposed, (PE) 1.8-2.8GeV, to be proposed,
(D-butanole)
Q.Zhao, J.Al-Khalili and C.Bennhold( th-nucl 0201002v2) quark model approach
Contributions from partial channels
Double polarized data for exclusive channels(Mainz data for eta p channel)
131/ 2 3/ 2
d d
d d
p p ))))))))))))) )
Forward Detector(TOF wall)
Gas Cerenkov
PT-Magnet
Gamma beam
LEPS spectrometer
TPC
TPC
Forward GammaDetector(lead-glass, PWO)
PT+TPC
80 mm
SuperconductingSolenoidB=2.5T(max=2.6T)B/B~130ppm(20x50mm)warm bore: 60cmlength: 100cmcooled by cryocooler(GM-refrigerator) no need of liq. He
PT-Magnet
proton Neutron
energyrange(GeV)
energy step(MeV)
errorstat.+sys.
energyrange(GeV)
energy step(MeV)
errorstat.+sys.
SPring-8
1.8-2.8 100 1+ 0.7 b 1.8-2.8 200 5+ 5 b
ELSA 0.7-2.9 200(above 1.5GeV
)
4+ 0.3 available data only <1.8GeV
- -
Comparison between ELSA and SPring-8