Present status of pionic atom spectroscopy experiments at RIBF and - PowerPoint PPT Presentation

Present status of pionic atom spectroscopy experiments at RIBF and future perspectives Kenta Itahashi RIKEN Nishina Center π − for piAF collaboration

Strong interaction in low energy region Quark confinement ↔ evolution of matter Spontaneous breakdown of chiral symmetry ↔ non-trivial structure of vacuum Non-perturbative aspects when energy < Λ QCD Finite density → sign problem makes Lattice QCD approach difficult Low T, high ρ experimental inputs are important 2

d u _ Pionic Atoms π − nucleus Strong Overlap between π and nucleus Strong + 
 Coulomb Strong interaction: Coulomb V s-wave = b 0 ρ + b 1 ( ρ n − ρ p ) + B 0 ρ 2 → Nuclear structure including skins Ericson, Ericson, Ann. Phys. 36, 323 ~ 1966 ! .

d _ u Pionic Atoms M. Gell-Mann et al. , PR175(1968)2195. π − Gell-Mann-Oakes-Renner relation f 2 π m 2 π = � 2 m q � ¯ qq � f π : pion decay constant nucleus Y. Tomozawa, NuovoCimA46(1966)707. S. Weinberg, PRL17(1966)616. Tomozawa-Weinberg relation b 1 = − m π 8 π f 2 π � ¯ qq � ρ � b free 1 Strong interaction: � ¯ qq � 0 b 1 ( ρ ) V s-wave = b 0 ρ + b 1 ( ρ n − ρ p ) + B 0 ρ 2 Jido, Hatsuda, Kunihiro, Phys.Lett.B670:109-113,2008. Kolomeitsev, Kaiser, Weise, Phys. Rev. Lett. 90(2003)092501

b 1 acting as an order parameter of χ -symmetry Order parameter of Calculated B 1s w. different b 1 for Sn Chiral symmetry breaking b 1 = -0.05 4.0 b = − 0.05 1 � ¯ qq � ρ No restoration of chiral symmetry � b free 1 B 1s [MeV] 3.9 � ¯ qq � 0 b 1 ( ρ ) b 1 = - 0 . 1 0 b 1 = − 0.10 no restoration 3.8 b 1 = -0.15 b 1 = − 0.15 3.7 Strong interaction: 115 120 A Mass number A V s-wave = b 0 ρ + b 1 ( ρ n − ρ p ) + B 0 ρ 2 aft. combination with light pi-A data Jido, Hatsuda, Kunihiro, Phys.Lett.B670:109-113,2008. Kolomeitsev, Kaiser, Weise, Phys. Rev. Lett. 90(2003)092501 5

Sn123 Calibration Pionic Sn 1s isotopes at GSI Calculated B 1s w. different b 1 for Sn Sn119 b 1 = -0.05 4.0 b = − 0.05 1 N o r e s t o r a t i o n o f c h i r a l s y m B 1s [MeV] 3.9 m e t r y b 1 = -0.10 Sn115 b 1 = − 0.10 no restoration 3.8 b 1 = -0.15 b 1 = − 0.15 3.7 Strong interaction: 115 120 A Mass number A V s-wave = b 0 ρ + b 1 ( ρ n − ρ p ) + B 0 ρ 2 aft. combination with light pi-A data K. Suzuki et al., PRL92(04)072302. 6

Spectroscopy of pionic atoms Direct production in (d, 3 He) nuclear reaction Missing mass spectroscopy to measure excitation spectrum in Q-value measurement Pion bound state (coupled with n hole) We are aiming at threshold e e r f 300 keV (FWHM) resolution. - i s a u q (prev. 400 keV) Excitation energy Kenta Itahashi, RIKEN 7

Theoretical predictions Ikeno ＠ Hadron 2013 8

Theoretical predictions Ikeno ＠ Hadron 2013 9

Precision spectroscopy at RI Beam Factory RILAC RIKEN-RIBF AVF RIPS SRC RRC fRC BigRIPS IRC Target GSI RIBF 0 50 m d beam Intensity 10 >10 Target 20 mg/cm 10 mg/cm Δ 0.03% 0.06% Resolution (FWHM) 400 keV 1000 keV Acceptance (mrad) 15H, 10V 40H, 60V RIKEN Nishina Center, Kenta Itahashi 10

Precision spectroscopy at RI Beam Factory RILAC RIKEN-RIBF AVF RIPS SRC RRC fRC BigRIPS IRC Target GSI RIBF 0 50 m d beam Intensity 10 >10 Target 20 mg/cm 10 mg/cm Δ 0.03% 0.06% Resolution (FWHM) 400 keV < 300 keV Resol. Matching Acceptance (mrad) 15H, 10V 40H, 60V RIKEN Nishina Center, Kenta Itahashi 11

Experimental setup BigRIPS TOF measurement Δ E measurement p 10 5 /s F7 Scintillator 3 He 10 2 /s F5 MWDC x 2 Target 3 He Tracking Scintillator SRC Dispersive focal plane d beam >10 12 /s, 250 MeV/u Kenta Itahashi, RIKEN 12

13 PID by relative timing to RF F5 timing and particles proton 122 Sn( d , 3 He) 3 He 5 10 proton ! in half bunch 4 10 3 He 
 Good 3 He detection in half bunch Count efficiency + small contamination 3 10 3 He ! contamination ! ~ 10 -4 from beam dump of proton 2 10 40 30 20 10 0 10 20 30 40 − − − − ~ t [ns] ∆ SciF5-RF

Experimental spectra of 122,117 Sn(d, 3 He) threshold RIBF54R1 (preliminary) 122 Sn(d, 3 He)

Experimental spectra of 122,117 Sn(d, 3 He) Theoretical predictions RIBF54R1 (preliminary) 122 Sn(d, 3 He)

First observation of y θ dependence of 1.5-2° r π atom cross section a n 1-1.5° reaction angle i ∝ m momentum transfer 0.5-1° i � l Δ L=q × r e r momentum transfer P 0-0.5° 2010 16 hour measurement T. Nishi et al., to be submitted 16

Theory Theory 2 deg vs Experiment 1 deg Angular dependent Xsec is explained fairly well by theory based on q dependence 0 deg momentum transfer Ikeno, Hirenzaki 17

ー ー ー ー ー ー Angular dependence ・ The dependences are qualitatively consistent 
 with the theoretical predictions. Target: 122 Sn Target: 117 Sn — 1s state 1s state — 1s state 1s state 2p state 2p state — 2p state — 2p state 2s state 2s state Plots normalized at forward reaction points Ikeno, Hirenzaki, priv. comm.

Experimental spectra of 122,117 Sn(d, 3 He) Theoretical predictions RIBF54R1 (preliminary) 122 Sn(d, 3 He) 1s 1s 2p 2p

Experimental spectra of 122,117 Sn(d, 3 He) RIBF54R1 (preliminary) RIBF54R1 measured 122 Sn(d, 3 He) binding energies and widths 2p 1s 2p Binding energies are 1s determined with very high precision of 3 keV and (stat.) 117 Sn(d, 3 He) Ikeno, Hirenzaki, priv. comm.

Achieved high quality data RIBF54R1 (preliminary) 122 Sn(d, 3 He) Calculated B 1s w. different b 1 2p preliminary 1s no restoration GSI 2p 1s A aft. combination with light pi-A data 117 Sn(d, 3 He)

Suppression of systematic errors (i) calibration by two body reaction of 
 the p ( d , 3 He) π 0 reaction on polyethylene target (ii) deduction of B 1s - B 2p in addition Use the peak from 
 θ reaction [mrad] θ reaction [mrad] the p ( d , 3 He) π 0 reaction as reference. � Peak position depends on θ reaction → Compared with 
 the Monte Carlo simulation. δ [%] δ [%] experiment simulation ※ N. Ikeno et al., Prog. Theor. Phys. 126 (2011) 483., S. Itoh, Doctoral Dissertation, Univ. of Tokyo (2011)

Suppression of systematic errors (i) calibration by two body reaction of 
 the p ( d , 3 He) π 0 reaction on polyethylene target (ii) deduction of B 1s - B 2p in addition Use pionic 2 p state as a reference. Shift of B 2 p by strong interaction is much smaller than that of B 1 s (~ 1/50) Theoretically calculated Excitation spectrum of 121 Sn (exp. in 2014) B 1s and B 2p in 121 Sn ※ ※ N. Ikeno et al., Prog. Theor. Phys. 126 (2011) 483., S. Itoh, Doctoral Dissertation, Univ. of Tokyo (2011)

Inputs for b 1 deduction (i) calibration by two body reaction of 
 the p ( d , 3 He) π 0 reaction on polyethylene target (ii) deduction of B 1s - B 2p in addition Preliminary After considerations on the correlations in the errors…

Result of recent experiment Preliminary aft. combination with light pi-A data V s-wave = b 0 ρ + b 1 ( ρ n − ρ p ) + B 0 ρ 2 ρ e = 0.6 ρ 0 25

π -nucleus interaction and χ -symmetry χ -perturbation 
 QCD sum rule theory 0.6 0.7 0.8 0.9 1.0 0.5 χ -condensate <qq>/<qq> 0 Preliminary − 0.14 − 0.13 − 0.12 − 0.11 − 0.10 − 0.09 isovector interaction b 1 1998 GSI π Pb In-vacuum b 1 2002 GSI π Sn 2014 RIBF π Sn In-medium b 1* at ρ 0 Kenta Itahashi, RIKEN 26

Order parameter at nuclear density π − Symmetry broken ← 30 % reduction � Nuclear density e s r e v i n U y l r a E W.Weise, LHC, RHIC NPA553(93)59. χ -condensate decreases by 30 % at ρ 0 27

Future perspectives Pionic atoms with long chain of tin isotopes We proposed to perform measurement of pionic atoms over the long chain of tin isotopes with a similar statistical precision level of ~ 3 keV RIBF54R1 RIBF135 → Density dependence of chiral symmetry

Resolution Improvements Unprecedented resolution of Construction of in-vacuum ~250 keV(FWHM) MWDC for good & uniform but strong E x dependence resolution in collaboration with DGTGR exp. (Uesaka, Zenihiro…) + CNS (Yako …) 29

3 He Silicon Detector (Micron W1) Heavy Ion Beam Future perspectives RIBF135 Large impacts on Systematic high precision • Density dependence of χ -condensate RIBF54 • Nuclear structure including EOS 
 2016 (neutron stars) Pionic atoms with unstable Perturbative effects on nuclei the nuclear structure induced by pionic atoms 30

Conclusion •Deeply bound pionic atoms provides b 1* information 
 → chiral condensate at nuclear medium •World highest precision in RIBF •Extremely good statistics for 121 Sn-pi •First data for pionic even N atom, 116 Sn-pi •First measurement of angular dependent X-sec •Analysis is ongoing and will be finalized soon •New experiment is proposed and approved for 
 systematic spectroscopy with much better precision •We are also working on piA with unstable nuclei Kenta Itahashi, RIKEN 31