Transcript Document

Experimental Study of Three Nucleon
Forces via Few Nucleon System
RIKEN
Kimiko Sekiguchi
Three Nucleon Force (3NF)
1934 Yukawa’s meson theory(2NF)
Three nucleon force (3NF) has been predicted
as a concept of the meson theory.
3NF is relatively weak compared to 2NF.
Hard to approach and find evidence
for 3NF experimentally.
1950’s pN scattering experiment
D (1232) was discovered.
1957 Fujita-Miyazawa 3NF Model
Prog. Theor. Phys. 17, 360 (1957)
2-p Exchange 3NF Model
Tucson-Melbourne (TM)
Urbana IX
Brazil
Texas
Ruhr Pot.
3NF Effects in Nuclei

First Indication of 3NF in 3H (A=3 Nuclei)
 Exp. v.s. Faddeev calc.
 B.E. (Exp.)－B.E.(Faddev Calc.)
= 0.5 – 1 MeV

A few methods are applied to descriptions
of A>4 Nuclei
GFMC
 Green’s Function Monte Carlo
 Ab Initio No-Core Shell Model
Pieper et al. Phys. Rev. C 64, 014001(2001)
etc…
well reproduce B.E. of light nuclei
 Better understanding of 3NF is one key element to describe Nuclear Structure.
 How to constrain the properties of 3NF ?
To study dynamical aspects of 3NF, Spin and Momentum
dependences,
Few Nucleon (3N,4N) Scattering is attractive.
Cross Section for d-p Elastic Scattering
at Intermediate Energies
Comparing the Faddeev Calculations
based on 2NF
(e.g. CDBonn, AV18, Nijm I, II)
-
Discrepancy in the Cross Section
Minimum → 3NF Effect!
Nd elastic scattering at intermediate
energies (E/A～100 MeV） is a good
probe to study 3NFs.
K. Sekiguchi et al.
Phys. Rev. C 65, 034003 (2002)
d-p
N-d Elastic Scattering
Data at 70-400 MeV/A
on the Market
Data mainly came from
RIKEN, RCNP, KVI, IUCF .
N-d Elastic Scattering
Data at 70-400 MeV/A
on the Market
RIKEN
d-p Elastic Measurement
at 70,100, and 135 MeV/A
Observables :
Ady , Ayy , Axx , Axz , P y' (  Ayp )
K yy' , K xxy' , K yyy' , K xzy'
– d to p polarization transfer
RIKEN Accelerator Research Facility (RARF)
Spin symmetry axis of polarized d beams is freely controlled.
E ×B Spin Rotator
Beam Line Polarimeter
By d+p Elastic Scattering
Polarized Ion Source
vector & tensor d
Spin axis is controlled by Spin Rotator
prior to acceleration.
Single-turn extraction feature of RARF
maintain the polarization amplitudes
Beam polarizations : 60-80%
RIKEN Magnetic Spectrograph SMART
Focal Plane Polarimeter
DPOL
Swinger

Target
CH2 / Liq.H2
d
Focal Plane
SMART: Swinger and Magnetic Analyzer with Rotator and Twister
Comparison of the Data with the Faddeev Calculations
List of the Calculations
By Bochum-Cracow-KIT Group
NN Forces Only
NN Interactions : CDBonn, AV18, Nijmegen I, II, &
93
NN + Tucson Melbourne (TM) 3NF
NN Interactions : CDBonn, AV18, Nijmegen I, II, &
93
NN + TM99 3NF
- closer to chiral symmetry
NN Interactions : CDBonn, AV18, Nijimegen I,II
NN + Urbana IX 3NF
NN Interactions : AV18
By Hannover Group
NN with (
) & w/o (
) D-isobar Excitations
NN Interactions : CDBonn
Summary of Comparison :
Results for d-p Elastic Scattering at 70-135MeV/A
Discrepancies between the data and the calculations based on 2NF only
Angular range
: Clearly seen in the Cross Section Minimum
Energy dependence : Large as an Energy Increases
When the 2p-exchange 3NFs are included …
d/d : good agreement
 3NFs are clearly needed.
Spin Observables :
TM99/ Urbana IX does better job for Ayp & T20
 Requirement of chiral symmetry
Vector Pol. (Ayp & iT11 ) : good agreement
Tensor Pol. ( T20 , T21 , T22 ) :
T20 & T21 : moderate agreement
T22 : Chaotic
Defects of 3NF
Higher order pol. (pol. transfer) : moderate agreement
Directions are O.K, but sizes are not enough for Kyy’ & Kxzy’.
What are we missing?
Further ingredients of 3NF
rr and pr exchange 3NF
many D-contributions with p-rings
e.g. 3π-rings with D-isobar excitations
(Illinois Model)
Treatment of Relativistic Effect
New Nuclear Potential
Chiral Effective Field Theory etc…
- Link to QCD
- Nuclear forces (2NF, 3NF, … )
and currents are derived in a consistent way.
Systematic Exp. Study of Few-Nucleon (3N-, 4N-) Scattering
Spin Observables
Energy Dependence
Solid Base to Test Theory
Three Nucleon Force Study
via Few Nucleon Scattering at RIBF with pol d. beams
pol. d beams at RIBF : E/A = 250 – 440 MeV
up to near p threshold energy
E/A ≤ 350 MeV (Ed ≤ 700 MeV)
- 3NF effects are most strongly enhanced.
- Max. energy where the state of the art Faddeev calc.
based on NN forces are applicable.
Nail down the spin parts of 3NF
PIS-AVF-RRC-SRC – then,
Where?
Polarized Ion Source
vector & tensor pol. d
Beam Line
Polarimeter
dp elastic/breakup
Measurement
SAMURAI
dp elastic & radiative
capture Measurement
N-d Elastic Scattering Data at 70-400 MeV/A
on the Market
at RARF
at RIBF
Finally
A new microscope “Few-N Scattering-at-intermediateenergies” has been set for exploring 3NFs.
The 1st step is the Nd elastic scattering.
Cross section shows the clear signature of 3NFs.
Spin observables have started showing their ability
but not fully yet.
Future Key Elements :
- Precise Data Set for Few Nucleon Scattering
- Chiral Effective Field Theory
- Relativistic Effect
- Further Ingredients of 3NF based on meson-exchange picture
The new microscope will lead us to clear understanding of
3NFs but also allow us to step into a further process.
Experiments were carried out under the collaboration of
RIKEN
K. Sekiguchi, N. Sakamoto, T. Ohnishi
University of Tokyo
H. Sakai, T. Uesaka, K. Yako, T. Kawabata, K. Suda, S. Sakoda,
Y. Maeda, H. Kato, M. Hatano, T. Saito, N. Uchigashima, H. Kuboki,
M. Sasano, S. Satoshi, Y. Sasamoyoto, Y. Takahashi
RCNP, Osaka University
H. Okamura, A.Tamii,
Tokyo Institute of Technology
Y. Satou
Kyushu University
T. Wakasa
KVI
N. Kalantar, K. Ermisch
Saitama University
J. Nishikawa, K. Itoh