Experiments of Few-Nucleon Scattering and Three-Nucleon Forces - PowerPoint PPT Presentation

International Symposium on Neutron Star Matter (NSMAT2016) November 22nd, 2016 Experiments of Few-Nucleon Scattering and Three-Nucleon Forces Effects Kimiko Sekiguchi Department of Physics, Tohoku University

Three-Nucleon Forces in Nucleus Three-Nucleon Force (3NF) key element to fully understand properties of nucleus. First evidence of 3NF : Binding Energies of Triton ( 3 H) ’90 ～ Nucleon-Deuteron Elastic Scattering at Intermediate Energies Biding Energies / Levels of Light Mass Nuclei Equation of State of Nuclear Matter etc ... Existence of 3NF was predicted in 1930‘s (after Yukawa’s meson theory). To find Evidence of 3NF is very hard. • 3NF < 2NF • One needs, 1. Reliable 2NF 2. Ab initio calculations based on 2NF 3. Precise experimental data 2

Three-Nucleon Force (3NF) 1957 Fujita-Miyazawa 3NF Chiral Effective Field Theory Prog. Theor. Phys. 17, 360 (1957) 2NF 3NF 4NF N 2 π -exchange 3NF : - Main Ingredients : Δ -isobar excitations in the intermediate 3NFs appear at NNLO. N Δ : excited state of nucleon N M ∆ = 1232 MeV Tucson-Melbourne (TM) + ⇤ 3 , 3 ⌅ Urbana IX � ⇥ ( = ) J π , T 2 2 2NF > 3NF > 4NF > ... Brazil, Texas etc…

Where can we find 3NF effects ? - I - 3NFs in Finite Nuclei Ab Initio Calculations for Light Nuclei � Green’s Function Monte Carlo � No-Core Shell Model etc.. • 2NF provide less binding energies 2NF • 3NF : well reproduce the data IL2 3NF (Illinois-II 3NF) : 2 π -exchange 3NF + 3 π -ring with Δ -isobar 3NF 3NF effects in B.E. • 10-25% • Attractive Note : Recently extended to T=3/2 3NFs play important roles to explain B.E. medium mass nuclei - in neutron rich nuclei. candidates of tetra-neutron state -

Where can we find 3NF effects ? - II - 3NFs in Infinite Nuclei 3NFs play important roles at high density A. Akmal et al., PRC 58, 1804(’98) • All NN potentials (AV18, Nijmegen I,II, CD Bonn) provide larger saturation point of Nuclear Matter. • Short range repulsive terms of 3NFs • 3NF (3-Baryon Fs) are taken as key elements - shift to the empirical to understand 2 M(sun) neutron star. saturation point - significant at higher density 5

• Understanding of 3NF is one key element to describe nuclear phenomena. • How to constrain the properties of 3NF ? Three - Nucleon Scattering is a good probe to study the dynamical aspects of 3 NFs . � Momentum dependence � Spin dependence � Iso-spin dependence : only T =1/2

Three-Nucleon Scattering a good probe to study the dynamical aspects of 3NFs. � Momentum & Spin dependence � Iso-spin dependence : only T=1/2 Direct Comparison between Theory and Experiment � Theory : Faddeev Calculations Rigorous Numerical Calculations of 3N System 2NF Input 3NF Input 2NF & 3NF Input • CDBonn • Tucson-Melbourne • Chiral Effective Field Theory • Argonne V18 (AV18) • Urbana IX • Nijmegen I, II, 93 etc.. � Experiment : Precise Data � d σ / d Ω , Spin Observables ( A i , K ij , C ij ) Extract fundamental information of Nuclear Forces.

Where is the hot spot for 3NF ? Predictions by H. Witala et al. (1998) Cross Section minimum for Nd Scattering at 100-200 MeV/A Nd scattering Low Energy Higher Energy NN 3NF NN Forward Backward 3NF 3NF q =0 ～ 4 fm -1

dp Scattering at Low Energies ( E ≤ 30 MeV/A ) High precision data are explained by Faddeev calculations based on 2NF. No signatures of 3NF. Exp. Data from Kyushu, TUNL, Cologne etc.. W. Glöckle et al., Phys. Rep. 274, 107 (1996).

Facilities � p + d BINA RIKEN BINA � 2004-??? d + p & SALAD � d + p KVI BBS magnetic spectrograph to Krakow SMART NTOF � n + d IUCF Cooler Ring � p + d + PINTEX Grand Raiden & LAS p + � RCNP � d

Nd Elastic Scattering Data at Intermediate Energies ~2016 • High precision data of d σ / d Ω & Spin Observables from RIKEN, RCNP, KVI, IUCF • Energy dependent data ✓ d σ / d Ω ✓ Proton Analyzing Power ✓ Deuteron Analyzing Powers

Precise Measurement of d-p scattering at RIKEN d + p → d + p 1 Differential Cross Section & All Deuteron Analyzing Powers ( iT 11 , T 20 , T 21 , T 22 ) at 70, 100, 135, 190, 250, 300 MeV/A - Whole Angular Range : θ c.m. = 10° － 180° 2 ． Deuteron to Proton Polarization Transfer Coefficients at 135 MeV/A - Double Scattering Experiment : Measurement of Polarizations of Recoil Protons - Angular range : θ c.m. = 90° － 180° - Strong sensitivities to Three Nucleon Force d + p → p + p + n - Extension from Elastic to Breakup - Limited kinematical configurations : sensitive to 3NF - Polarization Transfer Coefficient at 135 MeV/A

RIKEN RI Beam Factory (RIBF) • Polarized d beam : 70 - 300 MeV/nucleon • Spin axis of deuteron beam was rotated prior to acceleration. • Single turn extraction of beam was successfully obtained for all the cyclotrons. Polarization amplitudes were maintained during acceleration. • Beam Polarization : 80% of theoretical maximum values Spin axis of polarized d beams is freely controlled ! Polarized Ion Source SRC Polarimeter BigDpol SMART ( - 2005)

from Layout for pol. d beam Experiment at RIBF RRC IRC bypass beam transport line Dpol - beam line for AVF-RRC-SRC acceleration mode - beam line polarimeter - used for pol. d as well as light ions - measurement of beam polarization prior to acceleration by SRC - reaction : d-p elastic scattering at 90 MeV/nucleon GV 91 K91 G93 BigDpol - Target : CH 2 - d & p detected in kinematical coincidence condition Faraday cup @F0 - W( φ 3cm × 30cm) +Pb( φ 25cm × 70cm)

Data are compared with • CD Bonn, AV18, Nijmegen I, II • CD Bonn, AV18, Nijmegen I, II + TM’99 3NF • AV18 + Urbana IX 3NF • Chiral EFT N4LO NN

dp elastic scattering Cross Section K.S. et al., Phys. Rev. C. 65,034003 (2002) K.Hatanaka et al., Phys. Rev. C 66,044002 (2002) K.S. et al., Phys. Rev. Lett. 95,162301 (2005) Y. Maeda et al., Phys. Rev. C 76,014004 (2007)

NN only Large discrepancy in the backward region 3NF : improve the agreement not enough at very backward angles at higher energies Significant components are missing in higher-momentum transfer region. Differential Cross Section at 70 - 400 MeV/nucleon

It is very interesting to see how χEFT 3NFs explain the cross section data especially at very backward angles at 250 MeV/nucleon ! How does Chiral EFT pot. describe the Nd elastic scattering ? Various types of 3NFs appear in higher-leading orders… Theory in Progress : up to N 4 LO (NN + NNN). E. Epelbaum et al, Calc. based on Chiral EFT N4LO NN pot. are available. private communications NN(N4LO) NN(CD Bonn)

dp elastic scattering Spin Observables K.S. et al., Phys. Rev. C 89,064007 (2014) etc.

Deuteron Analyzing Powers at 135, 190, 250MeV/nucleon 135 MeV T 21 iT 11 T 20 T 22 190 MeV 250 MeV

Deuteron Analyzing Powers at 135, 190, 250MeV/nucleon 135 MeV 3NF iT 11 (vector analyzing power) iT 11 : good agreement T 22 T 22 (tensor analyzing power) : not always explained 190 MeV Defects of Spin dependent parts of 3NFs Higher Energies (250MeV) “backward angles” are not explained by any 250 MeV calculations.

Deuteron Analyzing Powers at 135 & 190 MeV/nucleon 135 MeV Chiral EFT N4LO NN pot. E. Epelbaum et al, private communications iT 11 (Vector analyzing power) iT 11 T 22 → No Room for 3NFs ? 190 MeV Large discrepancies in Tensor analyzing power T 22 → Rooms for 3NFs ? NN(N4LO) NN(CD Bonn)

Summary & Outlook Deuteron-Proton Scattering is a good probe to investigate the dynamics of 3NFs. - Momentum & Spin dependence - . For iso-spin, T=1/2 only. Precise data of d σ / d Ω and deuteron analyzing powers at 70- 300 MeV/nucleon Cross Sections : 3NFs are clearly needed in Elastic Scattering. Spin Observables : not always described by adding 2 π -exchange 3NFs Serious discrepancy at backward angles at higher energies : short-range terms of 3NFs ? It is interesting to see how χ EFT NN+NNN potentials explain the data. Next Step Four Nucleon Scattering (e.g. p+ 3 He) : - First Step from Few to Many - Iso-spin states of T=3/2 3NF - 4NF

p+ 3 He scattering 4-nucleon scattering First Step from Few to Many Approach to iso-spin dependence of 3NFs T=3/2 3NFs Large 3NF effects in cross section minimum at intermediate energies A. Deltuva and A.C. Fonseca 4NF ? Phys. Rev. C 87, 054002 (2013) 8.5 MeV 100 Theory in Progress 19.4 MeV d σ /d Ω (mb/sr) Calculations above 4-body breakup threshold energy open new possibilities for 3NF study in 4N scat. 10 CD Bonn AV18 Clegg Murdoch 30.0 MeV 1 0 60 120 180 Θ c.m. (deg)

pol. 3 He target for p + 3 He scattering is under construction at CYRIC, Tohoku University ✦ Method : Spin Exchange Optical Pumping ✦ Polarization : about 15 % (current) ✦ Planning First Experiment : p+ 3 He at 70 MeV pol. 3 He target m a e Detector b p May 2016@CYRIC