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Nuclear Physics at RCNP

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Presentation on theme: "Nuclear Physics at RCNP"— Presentation transcript:

1 Nuclear Physics at RCNP
International Workshop on Nuclear Physics with RIB August 28-31, 2001, Lanzhou, China Nuclear Physics at RCNP Yasuhiro Sakemi Research Center for Nuclear Physics, Osaka University In this meeting, I would like to propose the test measurement of the coherent pion production in 12C at the proton incidence energy 400 MeV. This is the collaboration member, mainly from this institute, RCNP, and from Saitama, Tokyo, and Kyoto universities.

2 Contents Overview of the Experimental Facility
Overview of the Physics Programs Physics Topics at RCNP Modification of the nuclear interaction in the nuclear medium studied by (p,2p) reaction Quenching of Gamow-Teller strength and Pionic nuclear collectivity studied by (p,n) reaction Construction of High resolution beam line for the study of the 0- (pionic) state in 16O 4. Planned experiment : Coherent Pion Production Summary This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction.

3 Physics Activities at RCNP
Cyclotron Laboratory : Nucleon, Meson, Hadron Physics AVF cyclotron with K=0.14 GeV and Ring cyclotron with K=0.4 GeV Polarized p,d & light heavy ion with Ep=0.01 ~ 0.4 GeV , E/A=0.01 ~ 0.1 GeV This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction. West Harima, Spring8, Hyogo Suita, Osaka Tentsuji-tunnel in Ohto, Nara Laser Electron Photon Laboratory : Quark Nuclear Physics 1 ~ 3.5 GeV Polarized Photon Beams by Back Scattering of Laser Photons (2 ~ 6 eV) from 8 GeV electrons at Spring8 Ohto Cosmo Observatory : Lepton Nuclear Physics Underground laboratory with low background (500 m depth, 10 Bq/m3 Rn & 4*10-3/m2/s cosmic μ

4 Overview of RCNP Facility
Neutron Course Ring Cyclotron East experimental hall This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction. West experimental hall AVF Cyclotron Polarized proton/deuteron beam High resolution beam/spectrometer Two arm spectrometers Focal Plane Polarimeter to measure the polarization transfer Neutron Polarimeter

5 Accelerators AVF cyclotron : Used as injector of Ring Cyclotron
Magnet Pole diameter : 3.3 m Pole gap : 20.6 cm ~ 34.7 cm Averaged field : 1.6 T Trim coils : 16 sets Valley coils : 3 ~ 5 sets Weight : 400 tons Acceleration system Dee : Single 180 degrees type Resonator : Moving short Frequency : 6 ~ 19 MHz Max. acceleration voltage: 80 kV Extraction system : Electrostatic deflector Ion Sources Internal ion source : Oak Ridge Type External ion source : Atomic beam type polarized ion source ECR ion source RING cyclotron Sector magnets : 6 sets Pole gap : 6 cm Maximum magnetic field : 1.75 T Trim coils : 36 sets Injection radius : 2 m Extraction radius : 4 m Weight : 2200 tons Single gap type : 3 sets Frequency : 30 ~ 52 MHz Max. acceleration voltage: 500 kV RF power : 250 kW/cavity Flat-topping cavity Single gap type : 1 set Frequency : 90 ~ 156 MHz Accelerated Ions and Energies Proton : 100, 200, 250, 300, 350, 365, 380, 390, 400 MeV Deuteron : 150, 170, 200 MeV 3He : 450 MeV Alpha : 300, 400 MeV 14N7+ : 560, 980 MeV This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction.

6 Physics Programs at RCNP
Unique Points Polarized beam Proton Neutron Polarimeter Polarization Transfer measurement Double Arm Spectrometer Correlation measurement High resolution beam ~30 keV High resolution spectrometer + Nucleus Light ion Precise Measurements This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction. Nucleon and Nuclear Interactions in Nuclear Medium . (p,2p) reaction : K.Hatanaka et al. Phys. Rev. Lett. 78 (1997) 1014 : Modification of the nuclear interaction in the nuclear medium.. Proton Elastic Scattering : Polarization transfer measurements Medium modification of the exchanged mesons masses in the N-N interaction. Proton Inelastic Scattering : Polarization transfer measurements Study the isoscalar spin-dependent central interaction. Spin Isospin Excitations . (p,n) reaction : T. Wakasa et al. Phys. Lett. B426 (1998) 257, Phys. Rev. C59 (1999) 3177: Study the quenching problem of the Gamow-Teller (GT) transion (3He,t) reaction : Gamow-Teller resonance (n,p) reaction : The construction of the (n,p) experimental facility was completed, now experiment is in progress. Giant Resonance. (p,p’) / (α,α’) / (7Li,7Be) reactions Fragmentation of Deep Hole States in Light Nuclei . Proton-proton Bremsstrahlung (p,p’γ) Reaction . K.Yasuda et al. Phys. Rev. Lett. 82 (1999) 4775 : Study the non-nucleonic freedom such as meson exchange and Δ currents etc. 6. Pion Production Mechanism in Nucleon-Nucleon Collisions . 7. Solar Neutrino Response by the 176Yb(3He,t)176Lu Reaction . Weak Hyperon Nucleon Interaction by the pn → pΛ Reaction . Other many experimental plans …

7 Grand RAIDEN + Polarimeter : Measure the polarization transfer
T. Noro and H.P.Yoshida et al. Topics 1 : Physics Modification of the nuclear interaction in the nuclear medium Physics Motivation Partial restoration of Chiral Symmetry in the nuclear medium →Modification of hadron properties : hadron mass reduction : m*(ρ)/m ~ f(ρ) compare This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction. <0|qq|0> ~ (-250 MeV)3 at free <0*|qq|0*> → 0 at high density Exchanged meson mass reduction → Nucleon – Nucleon (NN) interaction modification Physics Goal Extract NN interaction in the nuclear medium and compare it with free NN int. Obtain the information on hadron mass change in the nuclear medium via NN int. Unique Points of Experimental Technique Exclusive measurements : measure knockout proton together with scattered one Polarization transfer measurements : sensitive to the meson mass Study the density dependence of the hadron properties such as meson mass reduction in the nuclear medium LAS + Detector Grand RAIDEN + Polarimeter : Measure the polarization transfer Polarized beam

8 High resolution two arm spectrometer
M.Fujiwara, N.Matsuoka et al. High resolution two arm spectrometer Two arm spectrometer High resolution spectrometer : Grand Raiden Large Acceptance Spectrometer : LAS Grand Raiden LAS Maximum Magnetic Rigidity (Bρ) : 5.4 Tm 3.2 Tm 1st Order Momentum Resolution (M/D) : 2.7 × ×10-4 Confirmed Momentum Resolution (ΔP/P) : 4.7 × ×10-4 Momentum Bite (Pmax/Pmin) : Acceptance (ΔΩ) : 5.6 msr 20 msr Total Weight : 600 t 150 t This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction. DSR Dipole magnet for Spin Rotator (DSR) : Used to perform the complete measurements of the polarization transfer Dij →Scattered proton spin is precessed by DSR, and the polarization is determined from the combination of the measurements with DSR excited positively/negatively.

9 Experiment Beam Energy : Ep = 392 MeV
M.Yosoi et al. Experiment Beam Energy : Ep = 392 MeV Beam Intensity : 0.1 ~ 100 nA (depend on the background condition) Targets : 6Li, 12C, 16O, 40Ca Observed Reaction : 1s1/2(6Li, 12C, 16O), 2s1/2(40Ca) Energy Resolution : ~ 350 keV (beam energy distribution ~ dominant) Measured Observable : Analyzing power (Ay), Polarization Transfer (Dij, where i,j = n, l, s) This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction. 2nd level trigger : →Use FPGA (Field  Programmable  Gate Array) Reject the events scattered at forward angles which is not necessary to determine Dij

10 Unique Points 6Li 12C 40Ca Measurement condition:
T. Noro and H.P.Yoshida et al. Unique Points Measurement condition: Knockout of s1/2 nucleons ~ knockout of the nucleon at rest in the plane wave Advantage: The cross section of the s1/2 knockout ~ maximum at zero recoil condition. Bound nucleons are regarded to be unpolarized ~ simple relation between the spin observable of (p,2p) reaction and of the NN scattering. Obtained spectrum: s1/2 state observed clearly Events in s1/2 state (black area) ~ selected and used to determine the polarization Energy resolution : about 350 keV ~ beam energy distribution : dominant This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction. 6Li 12C 40Ca

11 T. Noro and H.P.Yoshida et al.
Nuclear Density Evaluation of the averaged nuclear density seen through the reaction non-relativisitic DWIA with factorized and local density approximation NN amplitude : t (r,ρ) = t0 + t1ρ(r) ~ assuming the linear density dependence This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction. 12C 1s1/2 knockout reaction ~ see the nuclear density 40 % of saturated density Averaged density ρ~ ranged from 7 to 40 % Nuclear density dependence of various observable ~ can be observed

12 Results Observed features :
T. Noro and H.P.Yoshida et al. Results Observed features : Ay and Dij ~ shows the density dependence : decreased with density Ay ~ significant difference from the theoretical calculations (PWIA/DWIA) Dij ~ sell reproduced by DWIA Difference of PWIA and DWIA ~ small : distortion effects can be neglected Ay: monotonically decreasing with nuclear density ~ some medium effects in the NN interaction Possible medium effects : Multi step process ~ but can not be seen in Dij : not likely × ~ detailed theoretical calculation shows the contribution × to the cross section within a few % Distortion effects ~ negligible (almost no difference between DWIA/PWIA) × Modification of the NN interaction : most likely ○ This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction.

13 Medium Effects observed in Ay
T. Noro and H.P.Yoshida et al. Medium Effects observed in Ay Medium effects g-matrix (NN interaction in the nuclear filed) ~ include Pauli Blocking effects Amos group : completely microscopic ~ reproduce data of elastic and inelastic scattering from 65 to 400 MeV Kelly group : empirical g-matrix Both calculations : not reproduce the density dependent reduction of Ay Hadron mass reduction in the nuclear medium T-matrix (T) in the framework of relativistic impulse approximation: where Ψi(r) is 4 component wave function (i=0:incidence and i=1,2:outgoing) Φ(r) is wave function of knockout nucleon, F is Lorentz-invariant NN ampilitude, and Fk is kinematical factor. ① nucleon mass reduction : M* → where S(r): scalar potential ② meson mass reduction :F ~ parameterize NN interaction with OBEP shape modification of the meson mass(m) ~ momentum transfer (q) dependence of a relevant component of NN amplitudes: This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction. at saturated density Value used by ref. G.Krein et al., Phys. Rev. C51 (1995)2646 Reproduce the density dependence of Ay well by the meson mass reduction

14 Polarization Transfer and Next Step
T. Noro and H.P.Yoshida et al. Polarization Transfer and Next Step Dij ~ universal scaling (m* & g*) such as ~ not reproduce all the Dij well Only one meson mass (mω) reduction ~ 0.9 : significant change of Dij Dij ~ sensitive to each meson mass reductions Spin observable (Dij) for (p,2p) reactions ~ good probe to study the possible modification of the NN interaction and meson mass reduction in the nuclear medium This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction. Outlook To observe the mass modification for each kind of mesons in the nuclear medium → Complete measurements : Cross section + Analyzing power : exists + Polarization transfer for the scattered and knockout particles : exists/planned Grand RAIDEN + Polarimeter Polarized beam 2‘nd polarimeter construction LAS + Polarimeter

15 H.Sakai and T.Wakasa et al.
Topics 2 : Physics Quenching of Gamow-Teller Strength and Pionic Nuclear Collectivity Physics Motivation Pionic nuclear collectivity enhancement Strong attraction produced by pions → leads to various interesting phenomena such as pion condensation and its precursor Interaction of nucleon, pion, and Δ in the nucleus This phenomena is related to short range correlation of Nucleon-Nucleon interaction. Experimental Observation of Quenching of Gamow-Teller strength Enhancement of Longitudinal Spin Response → access the Pionic Collectivity in the nucleus at different kinematics region Physics Goal 1. Determine the short range correlation of NN interaction (Landau-Migdal parameters) from the measurements of the quenching factor for Gamow-Teller strength by (p,n) reaction Longitudinal spin response function by (p,n) quasi-elastic scattering 2. Investigate the enhancement of the pionic collectivity (pion condensation) Unique Points of Experiment High efficiency neutron polarimeter Complete polarization transfer measurement for (p,n) reaction u d p Δ This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction. 400 300 200 100 ω(MeV) Quasi-elastic peak q (fm-1) Pion line Δh region ph region Precursor of pion cond. Pion condensatin Pionic Atom GT resonance

16 Spin-Isospin Correlation
Spin-Isospin Response Function Longitudinal : Transverse: π+ρ+g’ model NN effective interaction of τσ channel where Characteristics of interaction Shift to repulsive force due to g’ short range correlation Difference of VL and VT ~ due to the mass difference of πand ρmeson Small q region → repulsive ~ Gamow-Teller resonance and quenching VL becomes attractive at q > 1.0 fm-1 → enhance of pionic collectivity One π exchange This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction. One ρ exchange g’ ~ Short range correlation of NN interaction If g’ ~ large : Coupling of Δ and N ~ strong GT strength absorbed by Δ transition Reason of Quenching of B(GT) If g’ ~ small : Attractive force of VL ~ strong Enhancement of pionic mode Experimental g’ determination Important

17 Experiment H.Sakai and T.Wakasa et al.
This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction.

18 Neutron Polarimeter : NPOL2
H.Sakai and T.Wakasa et al. Neutron Polarimeter : NPOL2 Position sensitive neutron counters : 6 layers Size : 1 m × 1 m × 0.1 m for 1 layer 4 layers ~ liquid scintillator + 2 layers ~ plastic scintillator Figure of Merit (FOM) = εd.s.×<Ay>2 where εd.s.= (scattering probability from analyzer) ×(detection efficiency) Ay is effective analyzing powers of analyzer Comparison of the specification of neutron polarimeter < Facility > < Construction > < Beam Energy > < FOM > IUCF MeV 4.6×10-5 LAMPF / NTOF MeV 2.3×10-4 RCNP / NPOL MeV 4.9×10-4 → High FOM neutron polarimeter at RCNP This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction.

19 (p,n) Experimental Topics 1 Quenching of the GT strength
T.Wakasa et al. (p,n) Experimental Topics 1 Quenching of the GT strength Motivation to search the missing strength at continuum region Ikeda’s sum rule for GT strength : Sβ – – Sβ + = 3(Z - N) Missing strength in terms of the sum rule : Quenching of the GT strength In the previous experiment : Large quenching value : 40 ~ 50 % → derived from the (p,n) reaction at IUCF (beam energy 100 ~ 200 MeV) Well explained by using the Landau-Migdal parameters g’ = 0.6 ~ 0.8 assuming the universality ansatz with g’(=g’NN=g’NΔ=g’ΔΔ) → large g’NΔ value ~ suggests pion condensation and its precursor are unlikely Possible explanations 1. Contribution from Δ excitation Fragmentation of GT strength to higher excitation energy due to higher configuration mixing such as 2p-2h state Experimentally, it was not well known how much is contained in small amplitudes at excitation energies higher in the continuum as a tail of the GT resonance Gamow-Teller strength search in the continuum region experimentally This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction. IUCF data RCNP data

20 Results of the GT strength
T.Wakasa et al. Results of the GT strength What is new on the experiment at RCNP GT strength search in the continuum by the (p,n) reaction at 300 MeV Polarization transfer measurement to confirm spin flip ΔS=1 Multipole decomposition analysis to extract ΔL=0 Obtained data shows Observe the GT resonance at Ex ~ 9 MeV Total spin transfer : Σ~ 0.99 for GT resonance region (6 < Ex < 16 MeV) Σ~ 0.86 for continuum region (Ex ~ 50 MeV) → event at higher excitation region, confirm spin transfer reaction ΔS=1 GT resonance : 1. at peak area ~ all the yield contributes GT transition 2. GT strength contribution ~ exists at higher excitation energy up to 50 MeV This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction. Extraction of GT strength B(GT) σΔL=0(q,ω)=σGT・F(q, ω) ・B(GT) (measured) (calculated) (extract) Quenching Factor Q Quenching of the GT strength Mainly due to the configuration mixing Δ-h admixture into 1p-1h GT ~ small

21 Extraction of Landau-Migdal parameters
T.Suzuki and H.Sakai et al. Extraction of Landau-Migdal parameters Obtained from experiment : 2 values Excitation energy of the GT state: ωGT Quenching factor: Q = (Sexp(β-) - Sexp(β+))/(3(N – Z)) Theoretical Evaluation : Random-Phase approximation (RPA) in p-h and Δ-h spaces 2 input data : ωGT , Q ~ determined from the experiment : can be described by 3 outputs : Landau-Migdal parameters ~ g’NN, g’NΔ, g’ΔΔ g’ ΔΔ dependence ~ small : assuming reasonable condition 0< g’ ΔΔ <1, then, 0.18 < g’NΔ < 0.23 and < g’NN < 0.59 Conclusion 1. The universality assumption g’(=g’NN=g’NΔ=g’ΔΔ) does not hold 2. g’NN and g’NΔ values are around 0.6 and 0.2 3. Small g’NΔ value suggests that The dependence of the critical density of pion condensationρc is softened : 1.4 ρ0<ρc < 2.2ρ0 The pion condensation becomes likely where This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction. New Landau-Migdal parameters g’ NΔ = 0.2 / g’ NN = 0.6 / m*=0.8m In the previous values (universal Assumption) g’ NΔ = g’ NN = 0.6 ~ 0.8

22 T.Wakasa et al. (p,n) Experimental Topics 2 Longitudinal Response Function from (p,n) Quasi-elastic scattering Quasi-Elastic Scattering (QES) (q = 1 ~ 3 fm-1) Momentum transfer: q Energy transfer: ω Spin transfer ΔS (longitudinal:π/ transverse:ρ) Isospin transfer ΔT Transferred by NN scattering from the nucleon in the nucleus Simple reaction mechanism → information of nuclear spin response Factorized impulse approximation model : Cross section:σQES(q,ω) = Neff・σNN(q, ω) ・R (q,ω) Spin transfer : Dij→(distortion)×(NN scattering)×(Response) p n q, ω ΔS ΔT=1 This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction. Longitudinal response Transverse response Experiment: Ep=346 MeV, q~1.7fm-1 Longitudinal cross section: IDq Transverse cross section : Idp Analysis Continuum RPA + DWIA g’ NΔ = 0.3 / g’ NN = 0.7 / g’ Δ Δ = 0.5 / m*=0.7m Conclusion Small g’ NΔ enhance IDq Reproduce data well Consistent with the LM parameters extracted from GT strength quenching factor

23 Enhancement of Pionic Nuclear Collectivity
T.Suzuki and H.Sakai et al. Enhancement of Pionic Nuclear Collectivity Small g’NΔ~ 0.3 means : at large q region (>1 fm-1) Attractive force in the longitudinal channel : becomes large Coupling between nucleon and Δ : increased Enhance of pionic nuclear collectivity →Pion condensation and its precursor ~ become likely Experiment by (p,n) reaction with polarization transfer measurement 1. Quenching of the GT strength : q ~ 0 2. Enhancement of longitudinal spin response function : q ~ 1.7 fm-1 Landau-Migdal parameter, short range correlation of NN interaction, Enhancement of Pionic Nuclear Collectivity Attractive This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction. Next Step Other evidence of enhancement of Pionic Nuclear Collectivity :0- state study Landau-Migdal parameter determination independently : Coherent Pion Production

24 Next step to study pion collectivity
Topics 3: High Resolution Study of 0- States in 16O Study the Isovector Jπ=0-, 0+ → 0- excitation → carry the simplest pion-like quantum number Measure dσ/dΩ, Ay, Dij for the states 16O (0-, T=1 Ex=12.80 MeV and T=0 Ex=10.96 MeV) : → Observe the precursor of the Pion Condensation ? Theoretical works suggest : Surface Pion Condensation Need High Resolution Beam, Spectrometer and Detector to separet the 0- peaks from the large background of other excitation peaks Construction of the new high resolution beam line : Completed. Test measurements on 16O 0- state : in progress Nuclear Surface This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction. Pion Collectivity in the Nucleus Topics 4: Coherent Pion Production Critical density for Pion Condensation Property of condensation phase Short range correlation of NN interaction Determine g’NN, g’NΔ, g’ ΔΔ Planned experiment: Coherent Pion Production (CPP) Inside the Nucleus

25 Layout of new beam line T.Wakasa et al.
This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction.

26 Dispersion Matching Lateral / Angular Dispersion Matching
T.Wakasa et al. Dispersion Matching Lateral / Angular Dispersion Matching This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction.

27 Dispersion Matching with Spectrometer
T.Wakasa et al. Dispersion Matching with Spectrometer This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction.

28 Results of the Dispersion Matching
T.Wakasa et al. Results of the Dispersion Matching Lateral and Angular dispersion matching between WS-BL and Grand RAIDEN Quite high resolution beam with ΔE = 12.8 keV is achieved in this new beam line. This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction.

29 Status of the Measurement
T.Wakasa et al. Status of the Measurement Test experiment to check the experimental feasibility to measure the 0- states in 16O Target : 16O(p,p’) = SiO2(p,p’) – Si(p,p’) Beam Energy : Tp = 295 MeV Energy resolution ~ sufficient to isolate 0- states To reduce the background, ice (H2O) target will be used next This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction.

30 Topics 4 : Planed Experiment Coherent Pion Production
(E,k) (E’,k’) p n (ω,q) virtual π+ (ω,kπ) real Nucleus + + … = × This figure show the schematic diagram of the coherent pion production. It means that the virtual pion emitted from the proton goes through the nucleus, And scatters with the nucleon inside the nucleus, and obtain the momentum. Finaly, the virtual pion becomes the on-shell pion, and emitted to the outside Leaving the target nucleus with the ground state. So, the several reaction to produce the coherent pions can be considered, By using the hadron and electromagnetic probes like this. Here, we want to measure the CPP by using the (p,n) reaction. Coherent Pion Production (CPP) : Virtual pion, emitted from proton (spin longitudinal part of transferred quantum), propagates through the nucleus by mixing with -hole states. 2. ends up on-shell pion with the target nucleus recoiling with the difference in momentum between the off-shell and on-shell pion. 3. target nucleus is left in the ground state Physics Goal Study the production process of the coherent pions. Investigate the longitudinal part of the spin-isospin interaction involving the Δ excitation. Extract g’ ΔΔ to get information on the property of the predicted pion condensation phase.

31 Unique Points Cross section: where The cross section depends on
This is the schematic diagram of the CPP process. It shows that the CPP is the chain of the delta-hole interaction Additional to one pion exchange. Then, the cross section can be written with this equation, and the Important points are The cross section depends on the phase factor defined pn/pp Also on the long/trans response function. Distortion of the incoming/outgping partiucles. The cross section depends on the phase factor pn/pp Longitudinal / Transverse response function: VL / VT distortion of incoming/outgoing particles Tp = 400 MeV The angular distribution of the coherent pion production on 12C at Ep = 400 MeV. has a forward peak angular correlation due to the dominant contribution of the longitudinal component.

32 Extraction of g’ΔΔ The magnitude and the shape of the cross sections are sensitive to the g’ΔΔ. Energy shift is proportional to the change of g’ ΔΔ : ΔE ~ Δg’ ΔΔ(hcfπNΔ2/2πmπ2)ρ0 Pion coincidence Spectrum for the 12C(3He,t) reaction at E = 2 GeV. g’ ΔΔ = 0.4 × 1.5 g’ ΔΔ = 1/3 Limit the value of g’ ΔΔ experimentally from the CPP , g’ ΔΔ is important for the study of the condensation phase. p + 12C → n + π+ + 12C (g.s.) Proton incidence energy : MeV Scattered neutron :~ 180 MeV Produced pions : ~ 70 MeV LAS Target and Scattering chamber Neutron counters and charged veto Concrete shields neutron pion Proton beam Beam dump > 30 m

33 International Workshop on Nuclear Physics with RIB
August 28-31, 2001, Lanzhou, China Summary 1. The RCNP is unique facility for High resolution beam and High resolution detector Polarized beam and polarization transfer measurements Double arm spectrometer to measure the scattered particle correlation 2. Nuclear Physics to investigate Modification of nuclear interaction in the nuclear medium Spin-Isospin excitations in Nuclei have been/are now performed actively. 3. The hadron properties in the nuclear medium such as Meson mass reduction in the nucleus Enhancement of Pionic Nuclear Collectivity (Pion Condensation) are understood experimentally in more detail. Further experimental study is in progress. High resolution beam line to study pionic state : construction Coherent Pion Production to determine g’ΔΔ Other experimental plans …. Systematic and Precise Study of Modification of Hadron Properties due to partial chiral symmetry restoration in the nuclear medium at RCNP In this meeting, I would like to propose the test measurement of the coherent pion production in 12C at the proton incidence energy 400 MeV. This is the collaboration member, mainly from this institute, RCNP, and from Saitama, Tokyo, and Kyoto universities.


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