Search for direct evidence of tensor interaction in nuclei = high momentum component in nuclei = TERASHIMA Satoru 寺嶋 知 Depart. of Nuclear Science and Technology, Beihang University

Contents Motivation Theoretical Calculation Previous Experiments Proposed Experiment Summary and outlook

Physics Motivation The tensor force plays an important role in the pion exchange interactions The clear evidence of tensor force <= the binding energy of deuteron and alpha <= D-wave mixing NO OTHER EXPERIMENTAL EVIDENCES In contrast, this interaction has not been included explicitly in nuclear models e.g. Traditional mean field theory and shell model. even shell structure change due to (probably) tensor force is also indirect evidence. What is ‘direct’ experimental evidence of tensor force ? New probe and a clear difference from tensor force are needed. => Momentum distribution in the high momentum transfer via (p,d) reaction

Momentum distribution Single particle motion ~80 % Short Range correlation Momentum distribution is mainly satisfied single nucleon motion in nucleus (Fermi motion). ~ 80 % from many experiments f.e. (e,e’p), … Other components are thought to short range correlation of nucleon-nucleon. Tensor effect should be maximized on 2 fm -1 from pion-exchange region.

Theoretical calculations High momentum component on the ground state R. Schiavilla * et. al, Phys. Rev. Lett. 98, (2007) They recommended to measure A(e,e’np) and A(e,e’pp) * Jefferson Laboratory and Old Dominion University around 2 fm -1 (~400 MeV/c). component n-p and p-p is quit different. D-wave component

Effect of tensor interaction W. Horiuchi and Y. Suzuki, PRC76, (2007) T. Neff and H. Feldmeier, NPA713, 311(2003) Difference due to tensor interactions We expect the maximum difference at q ~2 fm -1 = 400 MeV/c 6 He is a unique tensor-less particle because α + 2 n

Previous Experiment BNL 12 C(p,ppn) EVA n-p correlation in > 0.22 GeV/c, Phys. Rev. Lett (2003) Jlab 12 C(e,e’pN) HallA n-p correlation in 0.35, 0.45, 0.55 GeV/c, Phys. Rev. Lett (2007) + p-p correlation MeV/c, Science (2008) Jlab 3 He(e,e’pp)n σ pp /σ pn : clear enhancement of pn in 0.3~0.5 GeV/c Phys. Rev. Lett. 105, (2010) RCNP 12 C[ 16 O](p,d) Ong’s talk new methods, what is significant?

Previous Experiment BNL [PRL] Jlab [PRL] Jlab [Science] Mean Field Short Range Correlation Clear Significance, but less statistics, FSI,…. From R. Subedi et. al, Science 320, 1476(2008) p-n and p-p

Measurements p( 6 He, d), p( 6 Li, d) rection at E/A=200, 400, 800 MeV at 0 degree scattering angle of deuteron (0 degree in cm of p+ 6 X -> d + 5 X reaction; pick up of high momentum neutron in 6 X nucleus.)

New experiment using (p,d) reaction -Experimental Requirement- High energy HI acceleration  for choice of high momentum transfer Fragment Separator  for use 6 He Medium Resolution Spectrometer (~ a few 1000) at 0 degree  to separate excite state of 5 He, 5 Li High rate tracker [or good quality RI beam at the high energy]  scintillation fiber array + multi-hit TDC GSI-FRS is a good candidate to perform experiment. with new high rate tracker

Beam energy and the momentum transfer at 0 degree scattering region of maximum difference at least 800 MeV/u is needed to see a clear difference

(p,d) kinematics at 800 MeV/u Scattering Angle lab. Scattering Angle c.m MeV MeV 0 Our interest 0o0o 180 o Low energy deuteron detection at zero degree.

Experiment in detail Bring the beam to S2 with dispersion mode. Place the CH 2 target at S2 （ keep resolution and sufficient yield) Detect deuteron at S3 [ or S4: higher resolution, lower acceptance] High rate detector at S1,S2 for timing, position, PI of 6 He,Li  Scintillation fiber Standard detector at S3(, S4) for timing, position, PI of d  Drift Chamber, TPC, Plastic.

Optics Realistic Acceptance including 6 He production FRS-S3 spectrometer mode +-5 cm on the CH 2 Target momentum bite: +-3% solid angle: 1 msr resolution power: a few … %+-5cm +-50 mrad

High rate tracker Y. Matsuda, ST, et. al. NIM A submitted Detector requirement Good high rate capability[~10 6 Hz/fiber] Moderate position resolution [<1 mm] Moderate timing information [<1 nsec] Base design is similar structure which had already developed and used for other experiment Z<8 and 2 momentum dispersive plane.

Born approximation or Dedicated calculation What we will learn Experimental output: ∫ dσ/dΩ GS δΩ [<3 deg.] or dσ/dΩ GS [around 0 deg.] [also low-line excited states (Its another our interest Related tensor force) ] momentum density n(q) at 1.0,1.5,2.0 fm -1 Direct evidence of tensor effect First measurement of ‘Tensor’ effect from n-n(“new”) IN FUTURE W. Horiuchi and Y. Suzuki, PRC76, (2007)

Summary Tensor force is the important part of nuclear force. Transfer reaction is a good method to select high momentum component. We plan to perform new type experiment to measure the clear effect from tensor force. The reaction mechanism is probably simple, we need reaction theory for deeply understandings Could you join and discuss about new momentum measurement and its physics. STAY TUNE!!

(n,d) reaction? proton pickup channel => more variable combinaition reaction mechanism is similar to (p,d) Y. Maeda et. al., Phys. Rev. C76, (2007) no stable neutron target => deuteron target deuteron would be able to play individual proton and neutron at the high energy (~ 1 GeV) kinematics crossing normal deuteron inelastic channel => need to measure 6 Li(d[n]),d)X  6 He(p,d)X hopefully similar behavior. for proof of principle same final states same primary process

Example -Isospin symmetry of short range correlation- Total strength of p-n correlation 16 O(p[n],d) 6 He(p,d)  6 Be(n,d) 6 Li(p,d)  6 Li(n,d)

kinematics on (d[n],d) channel around 0 deg. Hopefully background free!! except from C of CD 2 Normal kinematics (d,d’) Transfer kinematics (n,d)

Calculation