BGOeggと前方PWO検出器を用いたメソン光生成の研究 宮部　学 東北大学・電子光理学研究センター ELPH研究会C015 2016/12/01

Physics Motivation h’ mesic nuclei Other meson production h’ and UA(1) anomaly Yuji Matsumura, ELPH workshop C015(12/02), 「LEPS2/BGOegg 実験における原子核中で の η' メソンの性質変化測定」 Other meson production f1(1285) /h(1295), f2(1270) Property, Reaction mechanism.

h’(958) and UA(1) anomaly The experimental mass of h’ is more than 2 times larger expected value. UA(1) anomaly effect. Origin of large h’ mass Chiral symmetry breaking UA(1) anomaly Daisuke Jido, Hideko Nagahiro, and Satoru Hirenzaki, Phys. Rev. C 85 (2012) 032201(R). No experimental information for UA(1) anomaly effect

h’-mesic nuclei Search for the h’ mesic nuclei using nuclear target. Strong attractive force and small absorption Attractive force UA(1) anomaly effect Absorption ReW0～7.5-12.5MeV（CB- ELSA） M. Nanova et al., PLB 710, 600 (2012) Experimental results Re ah’N<0.8fm Phys. Lett. B474(2000)p416 |ah’N| <0.1fm　 Phys. Lett. B482(2000)p356 Optical potential with Chiral unitary model ReV >> ImV　(possible) 　→ more detailed experiment! Transparency ratio Search for the h’ mesic nuclei using nuclear target.

h’ mesic nuclei in (g,p) reaction Low recoil momentum of h’ Experimental parameters Eg 1.6~2.9 GeV Target C Forward proton detection C( g, p )X　missing mass Hirenzaki@ELPH 2011

Lineshape analysis Eur. Phys. J. A (2013) 49: 132 ω lineshapes for the different nuclei are compared and a broadening of the ω signal for the niobium target is observed in comparison to the liquid- hydrogen target. h’ linesapes study Lineshape comparison for the three targets LH2 (dashed green), C (dotted red) and Nb (black)

Other meson production

f1(1285)/h(1295) photoproduction f1(1285)/h(1295) decay into p p h. h(1295) first radial exictation of h? h(1405), h(1475) Glueball? Gluon component? PHYSICAL REVIEW C 93, 065202 (2016)

Vector meson photoproduction Eur. Phys. J C26, 271 (2002) Vector Meson Dominance Meson Exchange Dominant at low energies Pomeron Exchange Slowly increasing with energy.  N     (~ss) N uud

Recent Result from LEPS T. Mibe, et al. PRL95 182001(2005) E1 E1 E2 ρ3=0.199+/-0.052 E2 ρ3=0.189+/-0.030 Bump structure around 2GeV. Natural parity exchange is dominant 　→　0+ glueball ? Pseudo scalar meson exchange is not negligible. CF. Hiraiwa-san’s previous talk

Glueball, Pomeron/Odderon The phenomenological pomeron has long been established as an effective Regge pole with Trajectory. Phenomenological odderon, a C = P = −1 partner of the C = P = +1 pomeron, should not exist. Commun. Theor. Phys. (Beijing, China) 49 (2008) pp. 729–738

f2(1270) photo-production Rho, Omega, gamma and Odderon exchange careful analysis of all contributing C = +1 and C = -1 exchanges is necessary arXiv:1412.3234v3 [nucl-th] 20 Nov 2015

Physics Motivations h’ mesic nuclei Other meson production h’ and UA(1) anomaly Yuji Matsumura, ELPH workshop C015(12/02), 「LEPS2/BGOegg 実験における原子核中での η' メ ソンの性質変化測定」 Other meson production a2, f1(1285) / h(1295), f2(1270) h production T. Nam, JPS meeting 2017A, “Eta photo-production from proton target at LEPS2/BGOegg experiment (1)” Toshikazu Hashimoto, JPS meetin 2017A, "LEPS2/BGOegg 実験における液体水素標的を用いたη 中間子光生成反応(2) “ h’ production from nucleon h’ scattering length

Experiment

LEP2 Project at SPring-8 Laser room Backward Compton Scattering High intensity： Multi (ex. 4) laser injection w/ large aperture beam-line & Laser beam shaping 　 ~ 5 x 10 6 photons/s （LEPS ~10 6 ） Recoil electron (tagging) LEP (GeV g -ray) Laser room Inside SR bldg 30m long line 8 GeV electron Laser Outside SR bldg Experimental bldg Beam dump BGOegg LEPS2 spectrometer Storage ring Energy spectrum with large BGO crystal (f 8 cm x L 30cm ) Large acceptance EM calorimeter BGOegg + PWO

Large acceptance EM calorimeter BGOegg Egg like shape Total volume 264L Total weight 1.9t (crystal only) Two type photomultipliers H11334 (metal package type) H6524 (head on type) Very few dead-region Without housing material Only with 3M-Vikuity ESR film reflector.

Overview of BGOEGG Forward (24°-90°) Backward (90°-144°) 13 layers (153L) Backward (90°-144°) 9 layers (112L) 1320 BGO Crystal with 220mm(20X0) length Each crystal is pyramidal shape with isosceles trapezoid face. 60 BGO crystals per layer Cross section view of BGOEGG

Construction of BGOegg Assembly in ELPH ~ 2012/12 Departure from ELPH ~ 2012/12/13 Arrival in LEPS2 ~ 2012/12/15 Beam Ready 2013/12~

PWO forward gamma counter (FG) Total 252 PbWO4 crystals PWO crystal 22 x 22 x 180 mm r = 8.3 g/cm3 X0 = 0.89 cm RM = 2.0 cm From particle data group Fast light output Maintenance and performance test in ELPH FG @ ELPH 2016 FG @ LEPS 2003

Previous setup Time of flight counter Charge identification detector Resistive Plate Chamber (RPC) Charge identification detector Inner Plastic Scintilators(IPS) Caharged particle tracker chambers CDC, DC BGOEGG + Charge ID + CDC E949 Solenoid RPC DC ~12m g IPS CDC RPC DC FG

New setup candidate BGOegg covers from 24 – 144 degree IPS and CDC for charge identification FG (PWO) covers 3 -16 degree New charge veto counter for PWO BGOegg upgrade (XX-24 degree in future)

Performance of BGOegg 3.1 mm for centeral modules 3.7 mm for peripheral modules @1GeV 1.4% energy resolution @ 1GeV T. Ishikawa, Nucl. Instr. Meth. A837(2016)109–122

BGOegg performance World best invariant mass resolution sMp, sMh, sMh’ 7, 14, 19 MeV (Carbon) 8, 22, 30 MeV (LH2) Y. Matsumura’s talk h’ mesic nuclei search h’ line shape study h production

Performance of FG 2.9% energy resolution @ 1GeV Nuclear Instruments and Methods in Physics Research A 447 (2000) 467}475

MC simulation for BGOegg+FG Geant4 base MC simulation FG Calibration Energy resolution BGOegg + FG IPS, CDC + FGPS gg invariant mass distribution : FG only

Simulation result improve the Forward region acceptance BGOegg+FG BGOegg only BGOegg+FG BGOegg only h’ -> gg yield f1(1285) -> pph -> 6g

Summary BGOegg calorimeter experiments with H2 and carbon target was performed until 2016/07. LEPS2 has one order of magnitude higher intensity beam and large acceptance coverage. h’ mesic nuclei, baryon resonance, etc FG PWO counter will be test in ELPH We plan to build the BGOegg + FG setup as a next possible candidate.