Coherent Pion Production induced by neutrino and hadron beam

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1 Coherent Pion Production induced by neutrino and hadron beam Yasuhiro SAKEMI Research Center for Nuclear Physics (RCNP) Osaka University Contents Physics motivation Coherent Pion Production Proton induced CPP at RCNP Neutrino beam at J-PARC Summary

2 interaction in the nuclear medium ~ short range correlation of -hole: g g Ν 1 Hadron beam ~ Low density Neutrino beam ~ Saturated density Density dependence of g (ρ) interaction in high density

3 Coherent Pion Production Coincidence measurement of pion and external probe Virtual pion prove the pion correlation in the nucleus (n,µ ) Real Pion N -1 Nucleus (G.S.) Virtual Pion : π +* ~ interaction (ω,q) Beam (p,ν)

4 Spin Response in Nuclei n,µ- p,ν (q,ω) π+ Spin Longitudinal Response ~ Pion correlation maximum M.Ericson σ q π+

5 Longitudinal Response Longitudinal Response ~ Enhancement and Softening RL n σ q 0 Representing πνν and πν couplings Transverse Response ~ Quenching and Hardening RT n σ q 0 p-h interaction p-h and -h attractive force from OPEP ~ origin of the pion correlation g -h interaction

6 Hadron induced CPP Data Nuclear Structure Model (RPA, ) R L ~Extraction Effective Interaction: π+ρ+g model g determine Spin Response Function Input for the analysis of neutrino induced CPP ~ detailed study on reaction mechanism Neutrino induced CPP Data g in saturated density

7 π+ρ+g model π+ρ+g model : V Effective Interaction ( q, ω) = V + V ( q, ω) V ( q, ω) eff LM π + Landau-Migdal parameters ~ short range correlation V + LM f f = πn πnn f + f π πnn fπ NN mπ g' N ρ ( σ σ )( τ τ ) [(( τ T )( σ S ) + ( τ T )( σ S )) + h. c. ] g' { g' 1 NN [(( T T )( S S ) + ( T T )( S S )) + h. c. ]} δ ( r r ) g NN 1 1 g N 1 S 1 T g S 1 S T 1 T g NN N N -1 g N N -1 g N -1 N N -1 N N -1 N -1 Well known from Gamow-Teller resonance Known from Quasi-free scattering Unknown

8 g NN and g N Polarization transfer experiment : Quasi-free 1 C(p,n) RCNP: Tp=346 MeV T.Wakasa et al., Phys.Rev.C69, (004) LAMPF: Tp=494 MeV T.N.Taddeucci et al., Phys.Rev.Lett.73,3516 (1994) g N =0.3 m*=0.7m g ΝΝ =0.7 m*=0.7m g NN ~0.7, g N 0.3 g ΝΝ =0.7 g Ν =0.3

9 g and pion condensation g No experimental information g Sensitive to ¾Critical density of pion condensation ¾Cooling mechanism of neutron star propagation in the high density matter?

10 Inclusive process Proton/ 3 He induced CPP Neutrino induced CPP : p( 3 He)+A n(t)+π + +A g.s. : ν+α µ +π + +A g.s. Quasifree decay Nucleon knockout spreading Nucleon spreading CPP + + QF SP Osterfeld, Udagawa Information on Spin response

11 Spin longitudinal response CPP ~ forward peaked : Amplitude ~ (S q)(s k π ) qk π cosθ π Osterfeld, Udagawa θ π = 0 degree ~ cross section : maximum ~ Spin longitudinal component Dominant LO TR 0 degree measurement

12 g extraction from CPP Coincidence measurement of neutron and pion Observables -, n, t Hole Particle Real Pion Cross section Spectrum shape Peak position : E g' hcf m πn π ρ 0 Osterfeld, Udagawa g =0.33 =0.4 Interaction ~ Virtual Pion q Nucleus (G.S.) Depend on g, p, 3 He Coherent Pion Production (CPP) -Virtual pion ~ emitted from incidence proton beam -Excite /nucleon-particle nucleon-hole states -Propagate with mixing particle-hole states -Produce the real pion -Target nucleus is left in the Ground State (G.S.)

13 CPP experiments Hadron probe Saclay ( 3 He,t + ) ~ resolution : not enough to separate ground state LAMPF (p,n + ) ~ test experiment : shutdown RCNP (p,n + ) ( 3 He,t + ) ~ in progress study residual interaction with high resolution measurement Saclay Data Neutrino A(, - + )A a few GeV region ~ Data : poor KK ~ first data at <1.3 GeV> J-PARC!

14 Proton induced CPP at RCNP Neutron detector 70 m TOF π detector Target Neutron TOF NPOL Experiment 1 C(p,nπ + ) 1 C(g.s.) Beam ~ proton 400MeV Beam energy resolution ~ E~100keV Current ~ 1 na Target ~ 1 C (100mg/cm ) Detector Netron detector ~ E~300 kev π detector ~ E~1 MeV Identification of CPP select the ground state of residual nucleus ws Ring Cyclotron AVF Cyclotron AVF Cyclotron Facility

15 Experimental setup Charged particle detector in the sweeping magnet Neutron Counter Tracking detector : GEM Multi-anode PMT ~ set far from magnet through WLS fiber Position sensitive Neutron Counter (liq Sci.) TOF length ~ 70 m Energy resolution : 300 kev Detection efficiency : 15 MeV 10 cm scintillator WLS fiber 80 cm

16 Tracking Detector 1. Gas Electron Multiplier detector (GEM). Charged particle (π..) detection in the magnet 3. Detector components Three layers of GEM foil ~ high gain dimentional Readout board ~ high resolution 4. Specification high position resolution~ 100mm Effective area~ 300x50 mm radiation tolerance 5. Readout ~ high speed with parallel processing : SpaceWire 6. Installation ~ completed in the spring of 006. Triple GEM effective gain Effective Gain Ar/CO Ar/iso-C4H µm 70µmφ GEM (supplied by GDD CERN) Vgem gain as a function of biased voltage to GEM dimensional Readout Board 00 µmpitch

17 Test Experiment CPP event selection ~ need GEM detector for pion tracking background TOF spectrum of pion counter range of CPP event Energy loss of two sci.

18 Present status p Preliminary p g Cut E/TOF DE-DE CPP range Neutron energy spectrum CPP region ~ enhancement? ~ detailed analysis continued need much more statistics to confirm CPP Background ~ study in progress beam halo Transmission efficiency of the primary beam ~ bad beam optics tuning ~ considered now To identify CPP Separate ground state of residual nucleus by missing mass spectrum Tracking information ~ GEM detector is needed next step neutron energy loss (MeV) theoretical calculation RCNP coherent pion cross section E. Oset, Nucl. Phys. A 59 (1995) 47.

19 Neutrino Beam Neutrino Nucleus Weak interaction Can prove the interior of nucleus Cross section ~ behave volume like No distortion/absorption Adler s theorem : M~T( (q)+n X) Density r Neutrino Good Probe to study the interior of the nucleus keep the information of nuclear interior Hadron Can not transmit Nucleus Strong interaction Reaction ~ peripheral Sensitive to nuclear surface Distortion/Absorption effects can investigate residual interaction and response function with high accuracy

20 Density dependence of g A.Hosaka and H.Toki Neutrino profile function ~ one mean free path S(b) ~ λ ~ (Aρσ) -1 Light ions

21 Neutrino induced CPP J.Marteau Quasi-free Longitudinal attractive Transverse repulsive g NN =0.7, g N =0.5, g =0.5 Peak g Strength response function

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23 Neutrino induced CPP Coherent Pion Production data ~ not so much data First data from KK ~ GeV energy region NO evidence of CPP

24 Neutrino Beam at J-PARC Beam energy ~ 1 GeV suitable for Nuclear Physics in the resonance region Detector ~ LOI(AGS neutrino beam) ~ Liquid Sci. with W.L.S Target Proton Carbon! Heavy Nucleus Detector design in LOI@AGS ν beam Around Near Detector

25 Neutrino induced CPP E~1 GeV resonance region ~ interaction in the nuclear medium ~ π, propagation in the interior of nucleus LOI (AGS neutrino beam) S physics Nuclear physics ~ interaction

26 Summary Nuclear physics with Coherent Pion Production interaction in the nuclear medium Short range correlation : g Spin longitudinal response function : R L Hadron(Proton/3He) Beam ~ Prove the surface, low density region Detailed study of reaction mechanism, response function Input for the accurate analysis of neutrino induced CPP data proton induced CPP ~ test experiment ~ done Neutrino Beam ~ Probe the interior of the nucleus J-PARC neutrino beam ~ 1 GeV ~ suitable for the ν-nucleus physics CPP ~ important to know neutrino detector response ~ RICH Particle ID Physics discussion, Detector design ~ needed Strange Quark Content in the Nucleon by T.-A. Shibata, N.Saito, Y.Miyachi Nuclear Physics ~ interaction in the nuclear matter ~ pion condensation, cooling mechanism of neutron star Neutrino Beam

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29 Electron/Photon induced CPP Suggested by Prof. M. Sakuda Longitudinal Response R L n σ q0 Mixture of longitudinal and transverse responses Enhancement and Softening Transverse Response R T n σ q0 Quenching and Hardening h- h interaction (g ) include Transverse excitation ~ dominant Can extract Longitudinal response strength by reducing the Transverse component measured by e/ induced CPP

30 GEM detector Tracking Detector: Gas Electron Multiplier trigger tracking Sci Sci 1 position position 1 charged particle aramid carbon (6 m) size: 70um pitch: 140um charged particle Readout Board 00um separation divide 50. E GEM 1 GEM GEM 3 Ar+ Readout Board (GND) e - Drift (3 kv/cm) V ~400V electron avalanche 307. analog LSI amp. mux. analog data to ADC