Transcript PowerPoint プレゼンテーション - Yamagata University

2005.Oct.6 @QPAC at RCNP
Status of the SP8-GDH
experiment
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Yamagata University
Takahiro Iwata
On behalf of the SP8-GDH
collaboration
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 photoabsorption cross-sections)
• Energy region: 1.8 ~ 2.4 GeV & 2.3 ~ 2.8 GeV
• Circularly polarized gamma beam
• Polarized polyethylene target
• 4p-detector system
• 1st double polarization experiment at SPring-8
• Approved in Oct. 2001 (QPAC )
• Status: in preparation
SP8-GDH collaboration
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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
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Circularly polarized gamma &
polarized nucleon target
 3/ 2     1/ 2   2p 2 2
  d



mN
p

I GDH
 : photon energy
 p : pion threshold energy
 : anomalous magnetic moment
 p  ( p   N ) /  N  1.79
 n  ( n  0) /  N  1.91
I GDH ,p  205b, I GDH ,n  233b
Anomalous
Magnetic Moment
(static property)
• 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
Derivation
ASSUMPTION:
spin flip amplitude
vanishes at infinite energy
Forward Compton Amplitude
f     †f [ f1    f   i  if 2      f   i ]i
spin non-flip
lim f 2    0
 
spin flip
General Principles
Lorenz invariance,
gauge invariance,
causality, relativity,
crossing symmetry,
analytic amplitude
unsubtracted dipersion relation
  mf 2  
ef 2    P  2
d 
p 0    2
optical theorem
mf 2   

 3/ 2     1/ 2   
8p
GDH sum rule
 3/ 2     1/ 2   2p 2 2


 d

mN
p

low energy theorem
f
 2
f 2    2


  0 2m2
Similar sum rules are
formulated for any particles
having non-zero spin !
Universal sum rule
GDH for proton
Running GDH integral
E
 3/ 2     1/ 2  
I RUN  E    d


P33
p
D13
F15
MAMI(Mainz)
F35 or F37 ?
GDH sum rule
 tot .
   3   1
2
205b
ELSA(Bonn)
2
I RUN  2.9GeV 
 226  5stat .  12sys.  b
The running GDH integral overshoots
the GDH prediction at 2.9 GeV by ~10%.
High-energy contribution
High-energy behavior evaluated by fitting
DIS data with Regge parameterizations
 tot .
   3   1
2
   3   1
2
2
Extrapolation
to high energy
is good?
2
SP8
Contribution above 2.9 GeV:
Bianchi and Thomas: -14b
Simula et al.: -13b
Total integral: (212 213)  5stat. 12sys. b
GDH sum rule
205b
If the evaluations are correct,
the sum rule is verified at 10% level.
GDH for neutron
• Data analyses in resonance region give contrary results to GDH s.r.
• Interesting to see neutron GDH
phenomenological
analyses with
real photon data
in resonance region
phenomenological Regge approach
Data of neutron GDH
   3   1
2
2
neutron
• preliminary Mainz data ( < 800 MeV)
• published Bonn data up to 1.8GeV
large errors compared with proton data
• no data above 1.8 GeV
   3   1
2
2
neutron
SP8
Mainz data
O. Jahn, Proc.GDH2004
Bonn data[PRL 94,162001(2005)]
Objectives of SP8-GDH experiment
Measurements of  for proton
in the energy range of 1.8-2.8 GeV
with 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 q+ :    d     q 
SP8-GDH Setup
Polarized Target(PT)
Forward
Detector
(FD);
TOF wall
Large Angle
geometrical acceptance
Detector(LAD)
97% of 4p
Gas Cerenkov(GC)
Inner
Detector
(ID)
Gamma
beam
PT-Magnet
Large Angle
Gamma Detector
(LAG);
Inner Gamma Detector
lead-plastic
(IGD)
Forward Gamma
Detector(FG);
lead-glass+ PWO
1m
Layout of experiment
responsibility
Polarized
target
beam
Magnet
for pol. target
PT: Yamagata + Bochum
IGD: UCLA
ID: Melbourne
LAD: Yamagata
LAG: Yamagata
GC: Miyazaki
FD: Yamagata
FG: Tohoku+Yamagata
DAQ: Yamagata
Polarized target
outer pipe of the final HE
• Modification of
KEK-cryostat ongoing
microwave cavity
• Most parts ready
except MC, waveguide
modified part
still
beam pipe
final heat exchangers
walls
• a few steps for
final assembly
• NMR for pol. monitor
made by Bochum
final heat exchanger
Cryogenics system for polarized target at SPring-8
~2500
400
300
JIS250
2000
400
2000
~1000
Ｈｅ３
1000
500
200
2000
500
2000
200
He3 pump system
He4 pump system
Ｈｅ４
EXP.
hatch
300
500
JIS250
3300
2000
JIS250
JIS65
pipe d=76.3
200
pipe d=267.4
flange d=350
JIS65
300
500
G.V.
JIS150
DN160
flange
O.D.=285
G.V.
ＥＨ１２00
DN160
RSV2000
200L
Dewar
ＥＨ５００
100L
Dewar
PT
1400
R６０１
ＥＨ８０
H2060
~2500
Inner Gamma Detector (IGD)
Designed and R&D by UCLA
26 layers of
5mm thick scintillators
and
1.2mm thick lead sheets
Avalanche Photodiode readout
1 APD/segment
Budget application to DOE (280k$)
O.Tsai(UCLA) invited to Yamagata by JSPS
for 10 month( from Nov. 2005)
10 MeV equiv.
light output
Inner Detector (ID)
• Charged particle detection
• tile scintillators 25mm thick
• 10 segments x 8 sectors
– 80 tiles in total
– neighboring segments rotated by
half a sector
• Readout: WLS fiber(d=1mm)
+ clear fiber(3m long)
• 4-dimensional readout(32ch)
• Multi-anode-PMT(16ch)
• Melbourne group made
preliminary study
• tiles to be made at Melbourne
workshop
Gas Cherenkov Counter
Miyazaki Univ. group in charge
Electron rejection
CO2 gas at 1 bar
Gas box
constructed
leak check OK.
Mirror design
ongoing
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
Summary
• 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
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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.
GDH activities in the world
proton
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)
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)
0.5-1.5GeV, proposed (HD)
Contributions from partial channels
Q.Zhao, J.Al-Khalili and C.Bennhold
（th-nucl 0201002v2)
quark model approach
Double polarized data for exclusive channels
(Mainz data for eta p channel)
 p  p
13 
d
d

d  1/ 2 d  3/ 2
PT+TPC
ＬＥＰＳ spectrometer
Forward
Detector
(TOF wall)
Gas Cerenkov
TPC
Gamma
beam
80 mm
TPC
PT-Magnet
Forward Gamma
Detector
(lead-glass, PWO)
PT-Magnet
Superconducting
Solenoid
B=2.5T(max=2.6T)
B/B~130ppm
(f20x50mm)
warm bore: 60cm
length: 100cm
cooled by cryocooler
(GM-refrigerator)
 no need of liq. He
Comparison between ELSA and SPring-8
proton
energy
range(GeV)
energy
step
(MeV)
Neutron
error
stat.+sys.
energy
range(GeV)
SPring-8
1.8-2.8
100
1+ 0.7 b
1.8-2.8
ELSA
0.7-2.9
200
(above
1.5GeV)
4+ 0.3
available
data only
<1.8GeV
energy
step
(MeV)
error
stat.+sys
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200
5+ 5 b
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