Report

Studies of Nucleon Correlations using Direct Reactions Isospin Dependence of Nucleon Correlations (knockout and transfer reactions) Neutron-Proton Correlations (knockout, transfer, quasi-free scattering reactions) Di-neutron Correlations (breakup reaction ?) BCS to BEC Transitions ? (knockout and transfer reaction ??) Jenny Lee RIKEN , Nishina Center Studies of Nucleon Correlations using Direct Reactions Neutron-Proton Correlations Isospin Dependence of Nucleon Correlations 30Ne, 36Mg 34,46Ar(p,d) at 70 AMeV knockout on C at 250 AMeV np-transfer on sd-shell nuclei 14O knockout on C & p a 65 AMeV np-knockout Support from Theorists Di-neutron Correlations 6He breakup on C & p at 70 AMeV BCS to BEC Transitions ? on 12C at 200 AMeV Quasi-free scattering, proton beam at 2.8 GeV Isospin Dependence of Nucleon Correlations MSU/ NSCL 09084 (planned in 2014): Comparison of the Neutron Spectroscopic Factors from Transfer and Knockout Reactions at E/A=70 MeV RCNP E390 (planned in 2013): Understanding Nucleon Stripping Reaction Mechanisms from Exotic Nuclei at Intermediate Energy RIKEN NP1112-SAMURAI06 (submitted deferred): Steps to Clarify the Isospin Dependence of Nucleon Correlations RIKEN (performed in Dec 2010): Spectroscopic information towards “Island of Inversion” using knockout reaction withJenny in-beam Lee gamma technique RIKEN , Nishina Center Nucleon Correlations Truncated shell model space + effective interactions Greater distribution of nucleons to higher energy configuration In reality Short-range, tensor & collective correlations Few active orbitals High Occupancy Inert Core Reduction in Occupancy Inert Core Probing the nuclear wave function Removing nucleon from occupied orbital Cross sections (probability) depend on the single-particle occupancy & overlap of many-body wave functions Spectroscopic Factor (SF) Cross Sections Reaction Model Spectroscopic Factors (expt) How good the effective interaction in Shell Model can describe the correlations ? Quantify Occupancy Correlation Effects SM description is accurate How much ? What is the Isospin Dependence of nucleon correlations? Some correlations missing in the interactions ? (e,e’p) – Stable nuclei (near closed shell) • Constant ~30-40% of SF reduction compared to theory • Correlations missing in shell-model interactions L. Lapikas, Nucl. Phys. A553, 297c (1993) (e,e’p) reactions How about Transfer Reactions ? Transfer Reactions -- long history ( >50 years) abundant data, but Problems in SF(expt) ! Experimental SF from Transfer Reactions Well-known problem - optical model potentials - parameters - reaction models ADWA (consistent set) Johnson-Soper (JS) Adiabatic Approximation takes care of d-break-up effects Use global p and n optical potential with standardized parameters (CH89) Include finite range & nonlocality corrections n-potential : Woods-Saxon shape ro=1.25 & ao=0.65 fm; depth adjusted to reproduce experimental binding energy TWOFNR, M. Igarashi et al., X.D. Liu et al., Phys Rev. C 69 (2004) 064313 J. Lee et al., Phys. Rev. C75 (2007) 064320 Consistent SFs for 41Ca Reliable Framework Systematic Studies SF=1.01± 0.06 SF(SM) = 1.00 Survey of Spectroscopic Factor (Transfer Reactions) Extend to 88 nuclei (ground-state) : SF(expt) Found 225 relevant papers Re-analyzed (unified model) > 430 data sets Extracted 88 SF(expt) Ground-state Benchmark 20 % agreement to theory SF(theory) Re-analyzed >2,000 data ( >300 papers ) Extracted 565 SF(expt) SF(expt) Extend Survey to excited states : Z=8-16 Do we understand all the correlations ? M.B. Tsang, J. Lee et al., Phys. Rev. Lett 95, 222501 (2005) M.B. Tsang, J. Lee et al., Phys. Rev. Lett 102, 062501 (2009) J. Lee, M. B. Tsang et al., Phys. Rev. C75, 064320 (2007) J. Lee, M. B. Tsang et al., Phys. Rev. C79, 054611 (2009) SF(theory) Suppression of SFs in Transfer Reactions CH89 + ro=1.25 fm with minimum assumption consistent SF(expt) with Shell Model Microscopic Input in Reaction Model JLM potential & Hartree-Fock (SK20) ro=1.25 fm HF rms radius Global CH89 JLM + HF densities Constant ~30% reduction in SFs J. Lee et al., Phys. Rev. C 73 , 044608 (2006) Suppression of SFs in Transfer Reactions n-rich p-rich CH89 JLM+HF ΔS=Sn-Sp Constant ~30% reduction in SFs Different sets of consistent parameters different normalizations J. Lee et al., Phys. Rev. C 73 , 044608 (2006) • Transfer reactions do not yield absolute SF ; Systematic approach relative SF can be obtained reliably over a wide range of nuclei • Nuclear structure purpose Relative normalized SFs Isospin Dependence of Nucleon Correlations ΔS=Sn-Sp 34,36,46Ar + p→d + 33,35,45Ar Inverse kinematics at 33MeV/A (e,e p’) Rs = 0.6-0.7 S800 Neutron-rich Proton-rich Transfer Reactions: Weak Isospin Dependence of nucleon correlations J. Lee et al., Phys. Rev. Lett 104, 112701 (2010) Target Chamber Nucleon Knockout with Fast Beams on 9Be / 12C Target Target 9Be or 12C High incident energy Reaction only affects a nucleon at surface Reaction Theory: Eikonal & Sudden Approximations Core J. Tostevin et al., J. Phys. G, Part. Phys. 25, 735 (1999) Projectile (fast beam) Rs = σ(expt)/σ (ES+SM) One-nucleon knockout -- away from stability • Rs strongly depends on separation energy • More correlation effect - strongly bound valence nucleon A. Gade et al., Phys. Rev. C 77, 044306 (2008) and reference therein ΔS=Sn-Sp Isospin Dependence of Shell Occupancies? Reduction Factor Q: Isospin Dependence ? Knockout reactions: Yes & Strong A. Gade et al., Phys. Rev. C 77, 044306 (2008) & reference therein Transfer reactions: Weak p(34,36,46Ar,d) at 33 A MeV J. Lee et al., Phys. Rev. Lett 104, 112701 (2010) Systematic difference between two probes ! Incompatibility Incomplete understanding in underlying reaction mechanism MSU/ NSCL 09084 (planned in 2014): Comparison of the Neutron Spectroscopic Factors from Transfer and Knockout Reactions at E/A=70 MeV Focal Plane 34,46Ar(p,d) 33,45Ar NSCL 09084: at 70 AMeV Target Chamber S800 Same incident energy as knockout reaction Direct comparison Same SF from transfer at higher energy ? (reliability and applicability of model) 70 AMeV Very few reliable transfer reaction measurements exist Establishing transfer reactions can be used as spectroscopic tools at reasonably high energy due to the beam intensity and quality (eg at RIKEN, energy degraded beam) Isospin Dependence of Shell Occupancies? Reduction Factor Q: Isospin Dependence ? Knockout reactions: Yes & Strong A. Gade et al., Phys. Rev. C 77, 044306 (2008) & reference therein Transfer reactions: Weak p(34,36,46Ar,d) at 33 A MeV J. Lee et al., Phys. Rev. Lett 104, 112701 (2010) Systematic difference between two probes ! Incompatibility Incomplete understanding in underlying reaction mechanism Transfer Reaction Future NSCL 09084: 34,46Ar(p,d) at 70 MeV/A - same energy as knockout reactions for direct comparison Knockout Reaction ? Is Strong Dependence Theoretically Explaned ? Dispersive Optical Model (DOM) (elastic-scattering & bound-level data for 40-49Ca) R.J. Charity et al., Phys. Rev. C 76 , 044314 (2007) Weak dependence Self-consistent Green’s Functions + FRPA C. Barbieri & W. H. Dickhoff, arXiv:0901.1920v1 Knockout reactions: Strong Dependence Applicability of Eikonal Model (inert-core approximation) for nucleon removal from deeply bound states ? Weak dependence Knockout Reaction Mechanism Deeply-bound Weakly-bound Rs=sexp/stheo Direct KO (d,t) transfer Multiple scattering/ Evaporation Core excitation Intranuclear Cascade Model (INC) C. Louchart, A. Obertelli et al., Phys. Rev. C 83, 011601 (R) (2011) 14O(d,t) ΔS=Sn-Sp (MeV) NSCL, MSU - 14O knockout at 60 AMeV F. Flavigny, A. Obertelli et al., Phys. Rev. Lett 108, 252501 (2012) INC: GANIL E569S – SPIRAL d(14O,t) 13O at 18 A MeV F. Flavigny, A. Obertelli et al. paper in preparation Significant core-excitation process depletes the one-neutron removal channel Knockout Reaction Mechanism Deeply-bound Weakly-bound kinematical cut (d,t) transfer low energy tail 14O(d,t) Low energy tail : ΔS=Sn-Sp (MeV) NSCL, MSU - 14O knockout at 60 AMeV Inelastic interaction between core and target ? FSI between the neutron and the target ? F. Flavigny, A. Obertelli et al., Phys. Rev. Lett 108, 252501 (2012) GANIL E569S – SPIRAL d(14O,t) 13O at 18 A MeV F. Flavigny, A. Obertelli et al. paper in preparation Complete Sets of Data Detailed Investigation of Nucleon Stripping Mechanisms at Intermediate-energy RCNP E390: Exclusive Measurement I 14O (Z=8) - p-shell spherical nucleus, in reach of ab-initio Calc. Reliable structure input examine different reaction models Goal (i) : Investigate the origin of discrepancies between Spectroscopic Factors extracted from Transfer and Knockout Nucleon removal Measuring core-excitation channels Justify over-prediction due to inert-core assumption 12N: 1n-knockout + 1p decay 11C: 1n-knockout + 2p decay Data: 12C( 14O, 13N), 12C( 14O, 13O), 12C( 14O, 12N+p), 12C( 14O, 11C+2p) @ 65 A MeV with detection of forward-moving protons tagging decayed protons (core-excitation) with detection of knocked-out nucleons in one-nucleon removal Planned in Fall 2013 at RCNP RCNP E390: Exclusive Measurement II “Proton” target – structure-less probe Simpler reaction mechanism Sensitive to larger part of wave function Semi-inclusive Data for looselybound neutron in 18C, 19C , 20C (40 A MeV & 81 A MeV) Y. Kondo et al, Phys. Rev. C 79, 014602 (2009) A. Ozawa et al, Phys. Rev. C 84, 064315 (2011) Fully-exclusive Data needed at inter-mediate energy better understanding & tight control of reaction mechanism benchmark technique for structure studies deeply-bounded nucleon -- determine origin of discrepancy in SF studies Goal (ii) : Study the dynamics of proton-induced deeply-bound nucleon-removal Data: 1H( 14O, 13N), 1H( 14O, 13O), 1H( 14O, 12N+p), 1H( 14O, 11C+2p) @ 65 A MeV Fully Exclusive Measurements with Detection of Knocked-out nucleons and Forward-moving proton Planned in Fall 2013 at RCNP 12C target : 13O + n 14O 13N + p 14O 12N + n + p 14O 11C + n + 2p 14O neutron energy/angular distribution proton energy/angular distribution evaporation channels evaporation channels CH2 target: 14O(p,pn)13O energy/angular distribution energy/angular distribution evaporation channels evaporation channels transfer -- angular distribution elastic scattering -- angular distribution 14O(p,2p)13N 14O(p,pn+p)12N 14O(p,pn+2p)11C 14O(p,d)13O 14O(p,p)14O RCNP E390 Proton / Neutron Target 14° γ Heavy Residues RIKEN NP1112-SAMURAI06 (submitted deferred): Steps to Clarify the Isospin Dependence of Nucleon Correlations Exclusive Knockout data of 14O on C & proton targets at ~ 250 A MeV Proton/ Neutron Neutron ( up to 10° ) Compete Data Set for Detailed Study of Reaction Mechanism Proton Detector was not ready Proposal Deferred Target With RCNP E390 at 60 AMeV necessary for 250AMeV data ? Proton, Heavy Residues SAMURAI Isospin Dependence of Nucleon Correlations MSU/ NSCL 09084 (planned in 2014): Comparison of the Neutron Spectroscopic Factors from Transfer and Knockout Reactions at E/A=70 MeV RCNP E390 (planned in 2013): Understanding Nucleon Stripping Reaction Mechanisms from Exotic Nuclei at Intermediate Energy RIKEN NP1112-SAMURAI06 (submitted deferred): Steps to Clarify the Isospin Dependence of Nucleon Correlations RIKEN (performed in Dec 2010): Spectroscopic information towards “Island of Inversion” using knockout reaction with in-beam gamma technique Jenny Lee RIKEN , Nishina Center Nuclear Structure in the “Island of Inversion” -1n Single-neutron Removal -1n -1n Island of Inversion 1p3/2 1f7/2 32Mg 33Mg 34Mg 35Mg 36Mg 1d3/2 31Na 32Na 33Na 2s1/2 1d5/2 25Ne 26Ne 27Ne 28Ne 29Ne 30Ne 31Ne 32Ne N=20 Energy Level Scheme Indicate the presence of pf-shell intrude configurations Cross Sections Quantify the intrusion of pf-shell configurations 20 Magic number 8 1p1/2 1p3/2 nlj 1s1/2 2 Systematic study towards and across the island of inversion: (36Mg,25Mg + g) establish the role of intruder configurations (30Ne, 29Ne + g) evaluate the current shell models RIKEN (performed in Dec 2010): Spectroscopic information towards “Island of Inversion” using knockout reaction with in-beam gamma technique Beams: 30Ne, 36Mg @ ~ 250 A MeV DALI2 (γ-ray detection) Target: Carbon BigRIPS (Beam PID) ZeroDegree (fragment PID & momentum measurement) Probing Neutron-Proton Correlations RCNP E365 (completed in Jan 2012): Systematic studies of neutron-proton pairing in sd-shell nuclei using (p,3He) and (3He,p) transfer reactions RIKEN NP1206-SAMURAI10 (April 18-19, 2013): Study of Neutron-Proton Correlation & 3N-Force in N=Z nuclei Proposal: Study of Short-range Correlation in nuclei with high energy proton beam Idea: np-knockout using proton target Jenny at Lee~ 400 AMeV ? RIKEN , Nishina Center Neutron-Proton Pair Correlations In nuclei: 4 types of Pairs Isovector (T=1, S=0) nn, pp, np pair np should be similar to nn & pp Isoscalar (T=0, S=1) np pair (deuteron-like) new phase of nuclear matter Theoretical & experimental efforts since 60’s Contradicting opinions & results ! Isovector (T=1) np-pairing Well defined from the Isospin Symmetry Isoscalar (T=0) np-pairing A lot of uncertainties !! Long-standing open fundamental questions: ○ Nature of T=0 pair in nuclear medium ? ○ Mutual Strength & Interplay of T=0 and T=1 np, nn, pp pairs ? ○ Does T=0 pairing give rise to collective modes ? 12C 12C(e,e’pN) – Interesting Physics Found & Hidden @ 4.627 GeV factor of 18 n p > n n + 12C X + anything @ 250 MeV/u (inclusive) 12C 12C Strong NN tensor force (short-range correlations) R. Subedi et al.,Science 320 (2008) 1476. J.M. Kidd et al., PRC 37, 2613 (1988). 12C(p,3He) , 12C(p,t) @ 40 MeV σnp / σ nn ~2.4 M. Yasue et al., J. Phys. Soc. Jap. 42, 367 (1977). For 12C, 4p & 4n on p3/2 shell No correlation: factor of 2.67 (pair counting) What is the behavior of np-correlations as a function of the relative momentum of the pair ? factor of ~ 8 -2p -np -2n Neutron-Proton Removal Reactions R. Schiavilla et al., Phys. Rev. Lett. 98, 132501 (2007) np M. Alvioli et al., Phys. Rev. Lett. 100, 162503 (2008) pp Tensor Interaction – different relative significance to Central at different region 12C: ratio of np/nn cross section • Transfer: ~ 1-2 • HI-induced Knockout : ~8 Different Reaction Mechanisms Sensitive to Different range of 2N Correlations • (e,e’pn): ~18 Various types of Reaction Mechanisms Complete Picture of np-tensor Correlations ? Probing Neutron-Proton Correlations RCNP E365 (completed in Jan 2012): longer-range Systematic studies of neutron-proton pairing in sd-shell nuclei using (p,3He) and (3He,p) transfer reactions RIKEN NP1206-SAMURAI10 (April 18, 2013): Study of Neutron-Proton Correlation & 3N-Force in N=Z nuclei Proposal: Study of Short-range Correlation in nuclei with high energy proton beam short-range Two-nucleon Transfer Reactions Similarity between pairing field and 2-body transfer operator Two-nucleon transfer reactions like (t,p) or (p,t) specific tool to probe T=1 pair correlations Spectra from (p,t) reactions Ground-state composed of BCS pairs, twonucleon transfer cross sections enhanced R.A. Broglia et al., Adv. Nucl. Phys. 6, 287 (1973) 76Ge & 76,78Se(p,t) strength: predominately to the ground states simple BCS paired states Neutron-Proton pairing using np transfer ? S.J. Freeman et al. PRC 75 051301(R) (2007) Two-nucleon Transfer Reactions T=0 (T=1) pairing: enhanced transfer probabilities 0+ → 1+ (0+ → 0+) levels Interacting Boson Model (IBM-4) T=0 stronger T=1 stronger Reactions (p, 3He), (3He,p) DT=0,1 (d,a), (a,d) DT=0 (a, 6Li), (6Li,a) DT=0 Measure the np transfer cross section to T=1 and T=0 states Absolute σ(T=1) and σ(T=0) – character and strength of the correlations σ(T=1) /σ(T=0) – interplay of T=1 and T=0 pairing modes Systematics of T=0 & T=1 np-pairing in sd-shell N=Z nuclei in sd-shell Ratio of cross section (T=1/ T=0) - reducing systematic effects of absolute normalization from A. Macchiavelli (LBNL) (3He,p) Shiro Yoshida, NP 33, 685 (1962) Inconsistencies in the trends (sd-shell): Closed-shell nuclei 16O, 40Ca NOT follow single-particle estimate ? No intuitive understanding – 20Ne, 24Mg follow single-particle prediction ? Doubtful increase of > a factor of 10 from 24Mg to 28Si ? Goals: Insight & quantitative knowledge of T=0 and T=1 np-pairing mechanism Five reactions proposed: 24Mg(3He,p), 32S(3He,p) @ 25 MeV 24Mg(p,3He), 28Si(p,3He) & 40Ca(p,3He) @ 65 MeV Systematic measurements spanning sd-shell nuclei under SAME condition Joint analysis (3He,p) & (p,3He) complete understanding – addition & removal transfer reactions for np-pairing Consistent absolute (dσ/dΩ) + at 0º Reliable systematics – Interplay of T=0 and T=1 np pairing – Individual T=0 & T=1 collectivity Systematic framework -- studies of np pairing in heavier N=Z nuclei (RI Beams) RCNP E365 (Completed in Jan 2012): Systematic studies of neutron-proton pairing in sd-shell nuclei using (p,3He) and (3He,p) transfer reactions 3H LAS beam at 25 MeV 24Mg(3He,p), 32S(3He,p) Proton beam at 65 MeV 24Mg(p,3He),28Si(p,3He),40Ca(p,3He) Grand Raiden Plastic scintillators (front of FP) Grand Raiden recoil particle Two MWDCs -- position LAS elastic scattering reaction One plastic scintillator -- E, TOF for PID (beam normalization & target thickness measurement) 65 MeV proton / 25 MeV 3He beams from injector AVF cyclotron (bypass Ring-Cyclotron) Revisiting (p,3He) and (3He,p) reactions in the sd shell RCNP Experiment – E365 24Mg (3He,p) Completed in Jan, 2012 at 25MeV Online Analysis Cross Sec on (ub /sr) Ex=1.05 (T=0) Distribu on 1.E+03 1.E+02 Online Analysis 1.E+01 0 4 8 12 16 20 24 28 32 36 lab - theta (deg) Data Analysis On-going 40 Theoretical analysis of structure by Alex Brown (MSU) and full two-step transfer reactions by Ian Thompson (LLNL) Probing Neutron-Proton Correlations RCNP E365 (completed in Jan 2012): Systematic studies of neutron-proton pairing in sd-shell nuclei using (p,3He) and (3He,p) transfer reactions RIKEN NP1206-SAMURAI10 (April 18, 2013): Study of Neutron-Proton Correlation & 3N-Force in N=Z nuclei longer-range Two-Nucleon Knockout Model Target 9Be/ 12C Theoretical Cross sections: Reaction: Eikonal & Sudden approximation Structure: 2N Overlap from Shell Model J. Tostevin, B.A. Brown, PRC 74, 064604 (2006) E.C. Simpson and J. Tostevin et al., PRL 102, 132502 (2009) Projectile (fast beam) - 2n knockout from 34Ar, 30S, 26Si 2n or 2p knockout (T=1) K. Yoneda et al., Phys. Rev. C 74 , 021303(R) (2006) D. Bazin et al., Phys. Rev. Lett. 91, 012501 (2003) A. Gade et al., Phys. Rev. C 74 , 021302(R) (2006) P. Fallon et al., PRC 81, 041302(R) (2010) 2N knockout cross sections carry information of 2N correlations Framework to quantitatively assess descriptions of 2n & 2p T=1 correlations 12C – Interesting Physics Found & Hidden Advanced Model np removal with T=0 First Calculations : np removal from 12C (with Shell Model Calc. from B.A. Brown) E.C. Simpson and J.A. Tostevin, PRC 83, 014605 (2011). -2n Shell model 10B PJT interaction -2p WBP -np p-shell T=0 np-spatial correlations in the wave functions are insufficient T = 0 cross-sections – sensitive to different effective interactions ! np-Correlations & 3-body Force Structure Model Eikonal-Theory Reaction Model np-removal of 12C on 12C target Significant Increase in the T=0 Cross Sections ! T=0 cross section Sensitive to 3N-force ! theo. σ-np (mb) Conventional Shell Model B.A. Brown (MSU) No-core Shell Model (NCSM) (realistic 2-body and 3-body forces ) P. Navratil (TRIUMF) σ(theo) Ο NCSM (NN+3N) ∆ NCSM (NN, w/o3N) 10B ■ Conventional Shell model E. C. Simpson, P. Navrátil, R. Roth, and J. A. Tostevin Phys. Rev. C 86, 054609 TOSM (tensor-optimized shell model) T. Myo (Osaka Tech) Final-State-Exclusive Data needed to pin-point the physics ! RIBF: First final-state exclusive measurement of np-pair removal in 12C (April 18, 2013) 12C 10B (-np), 10C (-2n), 10Be (-2p) @ 200 A MeV SAMURAI DALI2 γ-residues-neutron Measurement First quantitative study of npcorrelation & 3-body force First detailed study of diffractive mechanism in 2N removal reaction Target First insight into internal structure of correlated pairs (FSI considered) Benchmark: New Powerful Tool of Direct np-removal reaction SAMURAI at RIBF Systematic & Quantitative knowledge of np-Correlations & 3N-force toward exotic N=Z nuclei np-knockout using proton target (or proton beam) at ~ 400 AMeV ? More direct information about np-correlations ! Reaction Mechanism / Cross Sections ? GR (5.66 Tm) LAS (3.2 Tm) Neutron detectors SAMURAI Proton detectors SAMURAI large acceptance 1N and 2N removal channel can be measured simultaneously Probing Neutron-Proton Correlations RCNP E365 (completed in Jan 2012): longer-range Systematic studies of neutron-proton pairing in sd-shell nuclei using (p,3He) and (3He,p) transfer reactions RIKEN NP1206-SAMURAI10 (April 18, 2013): Study of Neutron-Proton Correlation & 3N-Force in N=Z nuclei Proposal Study of Short-range Correlation in nuclei with high energy proton beam short-range Short Range Correlations in Nuclei 2N-SRC SRC ~RN ~1 fm LRC ~RA 1.f 1.7f A~1057 o = 0.16 GeV/fm3 1.7 fm Nucleons What SRC in nuclei can tell us about: High – Momentum Component of the Nuclear Wave Function. The Strong Short-Range Force Between Nucleons. tensor force, repulsive core, 3N forces Cold-Dense Nuclear Matter (from deuteron to neutron-stars). Nucleon structure modification in the medium ? EMC and SRC Spectroscopic factors for (e, e’p) reactions show only 60-70% of the expected single-particle strength. Spectroscopic Factor Indication for SRC L. Lapikas, Nucl. Phys. A553, 297c (1993) Benhar et al., Phys. Lett. B 177 (1986) 135. MISSING : Correlations Between Nucleons SRC and LRC 12C – Interesting Physics found & hidden ~ 18 times n p 12C(e,e’pN) @ Jefferson Lab. (US) > n n How about using proton beam ? 12C(p,ppN) A variety of incident energies Larger Reaction Cross Sections Proton Target & Radioactive Beam Proton Beams on “radioactive target” Facility with GeV proton beams CSR, Lanzhou Under Discussion … GSI ->FAIR (2018 ?) IMP Proton beam with: max EK 2 . 8 GeV 3 . 6 GeV / c Kinematics -- High-energy Proton Beams They have Small deBroglie wavelength: = h/p = hc/pc = 2 0.197 GeV-fm/(2.8 GeV) 0.44 fm. p ~1 fm p1 SRC ~RN pf p n p0 p pn From p0, p1, and p2 we can deduce, event-by-event what pf and the binding energy of each knocked-out proton is. Target nucleus p2 p We can then compare pn with pf and see if they are roughly “back to back.” 2 planes of GEM or W.ch. ~1m apart Array : 3 layers of 10x10x200 cm3 scintillators Veto box 32.5o Beam 60o 2 meter 20o Array : 3 layers of 10x10x200 cm3 scintillators Total 450 scintillating counters 6 meter Array : 3 layers of 10x10x100 cm3 scintillators γ Brookhaven National Laboratory (BNL) Only 18 coincidence event ! Parasitic measurement No (nn or pp) data No more (p,ppn) Expt at BNL High Statistics & Resolution (p,ppN) data ! Mean-field SRC Rates (For a 109 protons/sec beam) Triple coincidence 12C(p,2pn) np pairs 100 events/hour In 15 days (100% beam availability) 35,000 events Triple coincidence 12C(p,pnn) nn pairs 1 events/hour In 15 days (100% beam availability) 350 events High Statistics & resolutions Physics Physics I : Mapping transition from mean field to SRC EVA / BNL: Only 18 12C(p,2p+n) events with pn>kF CSR Lanzhou: Expecting 35,000 12C(p,2p+n) events with pn>kF With 100ps TOF resolution: D p miss 15 MeV / c Mean-field SRC Sharp Transition ! Physics II. SRC Isospin Structure and the Tensor Force Asymmetric nuclei N>Z: np-SRC dominance The probability for a proton to be with momentum above kF is higher than for a neutron Theory prediction 12C 27Al Equal number of protons and neutrons above kF 56Fe 197Au Physics III: Pair-momentum Dependence of Tensor Force 3He At 400-600 MeV/c Sargsian, Abrahamyan, Strikman, Frankfurt PR C71 044615 (2005). At the CSR we propose to study the nucleon relative momentum range below 400 MeV/c, were the np/pp ratio is expected to be smaller. Physics VI: SRC C.M. and Relative Momenta Distributions: EVA / BNL: Only 18 12C(p,2p+n) events with pn>kF CSR Lanzhou: Expecting 35,000 12C(p,2p+n) events with pn>kF 350 12C(p,np+n) events with pn>kF Can compare nn-SRC to np-SRC Physics V: Reaction Mechanism Hard processes high energy and large momentum-transfer Important practical question: How low in t, u, Q2 … can we still use the advantages of hard scattering ? ~1 fm Experimental study of Short Range Correlation (SRC) New Physics of (p,ppN) @ 2.8 GeV , IMP Lanzhou I. Transition from Mean-field to Short-range Correlations II. SRC Isospin Structure and Tensor Force III. Pair relative-momentum dependence of Tensor Force IV. SRC COM and Relative Momentum Distribution V. Reaction Mechanism High-momentum components of nuclear wave function Tensor NN interaction, repulsive core & 3N forces Cold-dense nuclear matter (neutron stars) • Simple Measurement Direct and Clear Probe to SRC • Experimental Program: 12C (40Ca, 48Ca, 208Pb, deuteron) Universality of Tensor Correlations ? np R. Schiavilla et al., Phys. Rev. Lett. 98, 132501 (2007) W. Horiuchi et al., PRC 76, 024311 (2007) R.B. Wiringa et al., PRC 78, 021001 R (2008) W. Horiuchi et al., PRC 84, 061304 (2011) W. Horiuchi et al., arXiv 1202.0368v1 (2012) pp M. Vanhalst et al., PRC 84, 031302 R (2011) Correlations at ranges “longer” than “short-range” makes nuclei unique ? H. Feldeier,W. Horiuchi et al., PRC 84, 054003 (2011) Few hundred MeV/nucleon energy (eg.RIBF) Less selective in reaction mechanism Spatial (or “momentum”) Correlations Studies of Nucleon Correlations using Direct Reactions Isospin Dependence of Nucleon Correlations (knockout and transfer reactions) Neutron-Proton Correlations (knockout and transfer reactions) Di-neutron Correlations (breakup reaction) BCS to BEC Transitions ? (transfer reaction ?) Di-neutron Correlations 6He Y. Oganessian et al., Phys. Rev. Lett. 82, 4996 (1999) W. Horiuchi et al., Phys. Rev. C. 76, 024311 (2007) di-neutron Cigar-like Y. Oganessian et al., Phys. Rev. Lett. 82, 4996 (1999) 6He + 65Cu Elab=22.6 MeV A. Chatterjee et al., Phys. Rev. Lett. 101, 032701 (2008) Two-neutron exchange dashed: di-neutron dotted: cigar-like Neutron Correlations in 11Li T. Nakamura et al., Phys. Rev. Lett. 96, 252502 (2006) Strong two-nucleon correlation Coulomb breakup – not good probe Dominant effect of final-state interaction Y. Kikuchi et al., PRC 81, 044308 (2010) How about Nuclear Breakup reactions ? Studies of Nucleon Correlations using Direct Reactions Isospin Dependence of Nucleon Correlations (knockout and transfer reactions) Neutron-Proton Correlations (knockout, transfer, quasi-free scattering reactions) Di-neutron Correlations (breakup reaction ?) BCS to BEC Transitions ? (knockout and transfer reaction ??) Di-neutron Correlation: BCS BEC towards n-rich ? neutron cloud n Sn isotopes (Z=50) n 100Sn adding neutrons ……… 102Sn N=Z n n 134Sn More neutron-rich Neutron skin Low density distribution • How Pair Correlation in exotic nuclei is different from stable nuclei ? • Strong density dependence (normal density low nucleon density)? Cooper pair exhibits a strong spatial dineutron correlation over a wide range of neutron densities ρ/ρ0 ≈ 10-4 –0.5 M. Matsuo, PRC 73, 044309 (2006) Crossover behavior between the weak coupling BCS type and the Bose-Einstein condensation of bound neutron pairs (ρ/ρ0 ≈ 10-4 – 10-1 domain of BCS-BEC crosssover). Neutron-pairing in Sn Isotopes Skyrme HFB + QRPA approach Probability for Cooper pair to be correlated at short distances r < few fm is significantly enhanced at R > Rsurf How to probe the features ? M. Matsuo, H. Shimoyama, PRC 82, 024318 (2010). (2+ systematics) H. Shimoyama, M. Matsuo, paper in preparation (0+ systematics) How to see & interpret these nn-pairing structure in Transfer Reaction ? Neutron-pairing in Sn Isotopes Pair Transition density – Skyrme HFB + QRPA approach M. Matsuo et al., PRC 82, 024318 (2010) One-step transfer + QRPA Form Factor TWOFNR, M. Igarashi et al., Instruction: Y. Aoki (Tsukuba), Calc: D.Y. Pang, JL (p,t) Reaction Calc. Structure Calc. Pair Transfer Strength from QRPA Form Factor gs-gs Reaction Calc: 02+ & 21+ (in progress) Di-neutron Correlation: BCS BEC towards n-rich ? What is the appropriate observables ? Cross sections / Angular correlations / Momentum correlations / or ? Observables free from final-state-interactions What is the appropriate reaction mechanism ? Kinematics chosen to suppress the effect of final-state-interactions What is the appropriate energy ? Energy chosen for Kinematics & for model framework & experimental feasibility Studies of Nucleon Correlations using Direct Reactions Neutron-Proton Correlations Isospin Dependence of Nucleon Correlations 30Ne, 36Mg 34,46Ar(p,d) at 70 AMeV knockout on C at 250 AMeV np-transfer on sd-shell nuclei 14O knockout on C & p a 65 AMeV np-knockout Support from Theorists Di-neutron Correlations 6He breakup on C & p at 70 AMeV BCS to BEC Transitions ? on 12C at 200 AMeV Quasi-free scattering, proton beam at 2.8 GeV