1. The 8th International Workshop
on Chiral Dynamics 2015
Experimental tests of nuclear interaction models in few-nucleon systems
Elżbieta Stephan
University of Silesia, Katowice, POLAND

2. System of 3 Nucleons Predictions of NN potentials alone
fail to reproduce binding energies of 3N, 4N and heavier systems
fail to reproduce minimum of the d(N,N)d elastic scattering cross section
Introducing concept of three-nucleon forces: genuine (irreducible) interaction of three nucleons
Systematic approach within ChPT
E. Stephan UŚl
PISA - CD2015

3. Experimental studies of 3N Systems
Reactions:
Elastic scattering: N + d → N + d
Breakup: N + d → N + N + N
and electromagnetic processes
Observables:
differential cross section
vector&tensor analyzing powers
polarization transfer, correlations
Energy range - why "medium" and what does it mean?
measurable 3NF effects
below pion threshold
Technique:
spectrometers
large acceptance detectors
E. Stephan UŚl
PISA - CD2015

4. More Dynamical Effects ? Coulomb force and relativity
Predictions for the N-d elastic scattering
Coulomb
without C.
with C.
E=135 MeV
3NF
relativity
Effects small, located at extreme angles only !
E. Stephan UŚl
PISA - CD2015

5. 3N Systems – Elastic Scattering Vector & Tensor Analyzing Powers (130 MeV)
NN is enough
140 MeV - K. Sekiguchi et al., Phys. Rev. C 70, (2004)
130 MeV - H. Mardanpour et al., Eur. Phys. Jour. 31, 383 (2007), E.Stephan et al., Phys. Rev (2007)
100 MeV E.Stephan et al.,
3NF spoils?
???
E. Stephan UŚl
PISA - CD2015

6. 3N Systems Elastic Nucleon-Deuteron Scattering
Number of observables for the elastic scatterng channel - complete set would provide full dynamical information (at the given energy)
Only fraction has been measured accurately and systematically (RIKEN/RCNP/IUCF/KVI)
Not completely clear picture - still much to explore !
Complementary studies needed: Nucleon-Deuteron Breakup
E. Stephan UŚl
PISA - CD2015
Diagram: K. Sekiguchi, FB20

7. 3N Systems-Breakup Reaction
Three nucleons in the final state - 9 variables
Energy-momentum conservation – 4 equations
Five independent kinematical variables
Complete (exclusive) exp. – measured ≥ 5
Inclusive exp. – measured ≤ 4 parameters
Arclength Variable S
1H(d,pp)n
measured:
directions and
energies of two
protons, i.e.
θ1,φ1,E1
θ2,φ2,E2
E. Stephan UŚl
PISA - CD2015

8. 1H(d,pp)n and 2H(p,pp)n Breakup Cross Section 3NF+Coulomb / 3NF+Relativistic Effects
p+d 200 MeV
d+p 130 MeV (75 MeV/nucleon)
A.Deltuva et al.,
Phys. Rev. C80, , (2009)
H. Witała et al.,
Phys. Rev. C83, , (2011)
E. Stephan UŚl
PISA - CD2015

9. Detection Systems at KVI
BINA
SALAD
140 ΔE-E telescopes
3 plane MWPC
angular acceptance:
θ = (12º, 38º), φ = (0º, 360º)
Wall - very similar to SALAD
Ball - system of 149 phoswitches
angular acceptance: nearly 4π
E. Stephan UŚl
PISA - CD2015

10. 1H(d,pp)n and 2H(p,pp)n Studies at KVI
Experiment
dp130
+GeWall
dp100
dp160
pd135
pd190
Beam energy
130 MeV
65 MeV/A
100 MeV
50 MeV/A
160 MeV
80 MeV/A
135 MeV
190 MeV
Average
current
50 pA
8 pA
10 pA
Polarization
vector & tensor
(7 states)
(5 states) NO
vector
(1 state)
(2 states)
Target
LH2
LD2
Detector
SALAD
(GeWall-FZ-Juelich)
BINA
W. Parol PhD
data points per observable on systematic grid of proton emission angles
Simultaneous measurement of the elastic scattering channel
Part of the data still being analysed
E. Stephan UŚl
PISA - CD2015

11. 1H(d,pp)n Measurement at 130 MeV Cross Section Results – Highlights
Faddeev
calculations
Realistic NN potentials CD Bonn, NijmI, NijmII, Av18
3NF models: TM99, UIX
Coupled channel pot.
CD Bonn (mod) + Δ
EFT/ChPT potentials
NNLO – 2N only
NNLO – 2N + 3 N

12. 1H(d,pp)n Measurement at 130 MeV Cross Section Results – 3NF & Coulomb Effects
Including Coulomb force effects improves the agreement with the data at low Erel values
The best agreement is reached when both, the Coulomb force and the 3NF are taken into account !
E. Stephan UŚl
PISA - CD2015 12

13. 1H(d,pp)n breakup at 130 MeV Tensor analyzing power
Problem with TM99 3NF
E. Stephan UŚl
PISA - CD2015

14. 3N system - 2H(p,pp)n Breakup Vector (proton) Analyzing Power
190 MeV, H. Mardanpour et al.
135 MeV, M. Eslami-Kalantari et al. P Ay Ay

15. continuation: BINA in Cyclotron Center Bronowice
Cyclotron Proteus C-235:
Energy 230 MeV
(degradation down to 70 MeV)
ΔE/E < 0.7%
Beam current 500 nA – 0.1 nA
STEPS/ACTIONS:
Installation in CCB (adapting to beam line & infrastructure)
Checks of detectors: repairs, improvements, maintenance
Test run with scintillator detectors; ZnS, CD2 targets
Test run with all datectors (including MWPC);
ZnS, CD2 , CH2 targets
Liquid target system
E. Stephan UŚl
PISA - CD2015 15

16. Test run: CH2 vs CD2 targets
Coincidence trigger: WALL & BALL
E. Stephan UŚl
PISA - CD2015

17. d+p breakup reaction WASA@COSY
Deuteron beam
Energies 340, 380, 400 MeV
Pellet H target
WASA detector
forward part: 3o-18o
central part: 20o-169o
E. Stephan UŚl
PISA - CD2015 17

18. WASA
KVI
CCB
E. Stephan UŚl
PISA - CD2015

19. Next step: System of 4 Nucleons
IUCF
d+d elastic scattering at 241 MeV
KVI - BBS
d+d elastic scattering at 135 MeV
KVI - BINA
d+d -> d+p+n at 135 MeV
d+d -> d+p+n at 160 MeV
Considered (CCB):
p+3He -> d+p+p (and other channels)
comparison of dd breakup data for quasi-elastic scattering with pd elastic scattering
G.Khatri PhD
E. Stephan UŚl
PISA - CD2015

20. p+d Breakup versus Elastic Scattering Invariant variables
based on 4-momenta of:
in entrance channel: proton pp, deuteron pd,
in exit channel: protons pp1, pp2 and neutron pn
deuteron treated as proton-neutron pair, elastic scattering treated consistently with breakup
modified to intuitive energy variables
FSI:
QFS:
E. Stephan UŚl
PISA - CD2015

21. Breakup versus Elastic Scattering any relation between the effects?
d+p at 130 MeV
kinematical points limited to angles and energies of particles registered in SALAD
NN interaction: AV18 + 3NF UrbanaIX
effect of adding Coulomb force studied
the largest Coulomb force effects in breakup observed far from elastic scattering
acceptance for el.scatt
E. Stephan UŚl
PISA - CD2015

22. 1H(d,pp)n breakup versus elastic scattering any relation between the effects?
d+p at 130 MeV
kinematical points limited to angles and energies of particles registered in SALAD
NN interaction: AV18 + Coulomb
effect of adding UrbanaIX 3NF studied
the 3NF largest effects in breakup observed in pn FSI region
E. Stephan UŚl
PISA - CD2015

23. Breakup Measurements Summary
Systematic, precise sets of cross sections and analyzing powers
basis for comparing different approaches which predict the 3N system observables
Significant 3NF effects for cross sections !
Found large influence of the Coulomb force on c.s.
Relativistic effects to be studied in detail
Discrepancies – hint of missing pieces in dynamic models
Necessary:
further precise and rich data sets,
systematic way of comparing data with calculations
as well as theoretical advances – new ChPT ?
E. Stephan UŚl
PISA - CD2015 23

24. Thank you for attention !
E. Stephan UŚl
PISA - CD2015

25. System of 3 Nucleons Models of 3NF:
Naturally appearing in Chiral Perturbation Theory at N2LO:
E. Stephan UŚl
PISA - CD2015