A Search for Deeply Bound Kaonic Nuclear States at J-PARC Toshihiko Hiraiwa Kyoto University for the J-PARC E15 Collaboration

Contents Introduction J-PARC E15 Experiment Summary and Outlook Kaonic nuclei Experiment & Theory J-PARC E15 Experiment Method Current Status Summary and Outlook Hadron2009 @ Florida 1 December 2009

Introduction Hadron2009 @ Florida 1 December 2009

Kaonic nuclear states K-nucleon interaction Low energy K-p scattering data Kaonic hydrogen level shift (KEK-PS E228) Experimental searches for kaonic nuclei KEK-PS E471/E549 : K- stopped in 4He KEK-PS E548 : in-flight K- reaction on 12C, 16O OBELIX : pbar annihilation on 4He M.Iwasaki et al. , PRL 78, 3067(1997) Strongly attractive (I=0) Hadron2009 @ Florida 1 December 2009

Experimental results on K-pp FINUDA First evidence for K-pp Invariant mass of back-to-back Lp pairs in K- absorptions B = 115±6±4 MeV G = 67±14±3 MeV DISTO pp -> X+K+ X+->Lp B = 105±2 MeV G = 118±8 MeV M.Agnello et al. , PRL 94, 212303(2005) T.Yamazaki et al. , arXiv:0810.5182v1[nucl-ex] Hadron2009 @ Florida 1 December 2009

Theoretical study on K-pp B.E [MeV] G [MeV] Method Yamazaki and Akaishi 48 61 (mesonic) Variational Method (ATMS) Ivanov, Kienle, Marton, and Widdman 118 58 (non-mesonic) Phenomenological Model Shevchenko, Gal, and Mares 55-70 90-110 (mesonic) Coupled Channel Faddeev Calculation Ikeda and Sato 60-95 45-80 (mesonic) Nishikawa and Kondo ~126 Skyrme Model Dote, Hyodo, and Weise 20±3 (s-wave) 40-70 (mesonic) Chiral SU(3) Variational Method Arai, Oka, and Yasui depend on gΛ*Λ*σ Variational Method (as Λ*p state) All calculations say, “K-pp bound state exists” But … A Deep or Shallow state? Width is sufficiently narrow or not? Hadron2009 @ Florida 1 December 2009

J-PARC E15 Experiment Hadron2009 @ Florida 1 December 2009

J-PARC E15 Collaboration S.Ajimura1, G.Beer2, H.Bhang3, P.Bühler4, L.Busso5,6, M.Cargnelli4, S.Choi3, C.Curceanu7, S.Enomoto8, D.Faso5,6, H.Fujioka9, Y.Fujiwara10, T.Fukuda11, Y.Fukuda12, C.Guaraldo7, R.S.Hayano10, T.Hiraiwa9, M.Iio13, T.Ishikawa10, S.Ishimoto14, T.Ishiwatari4, K.Itahashi13, M.Iwai14, M.Iwasaki12,13 , P.Kienle4,15, J.Marton4, Y.Matsuda16, Y.Mizoi11, O.Morra5, T.Nagae9, H.Noumi1, H.Ohnishi13, S.Okada7, H.Outa13, A. Romero Vidal7, Y.Sada9, A.Sakaguchi8, F.Sakuma13, M.Sato10, M.Sekimoto14, D.Sirghi7,17, F.Sirghi7,17, K.Suzuki4, S.Suzuki14, T.Suzuki10, H.Tatsuno10, M.Tokuda12, D.Tomono13, A.Toyoda14, K.Tsukada13, O. Vazquez Doce7, E.Widmann4, T.Yamazaki10,13, H.Yim3, and J.Zmeskal4 1Osaka University, Japan, 2University of Victoria, Canada, 3Seoul National University, South Korea, 4Stefan Meyer Institut fur subatomare Physik, Austria, 5INFN Sezione di Torino, Italy, 6Universita’ di Torino, Italy, 7Tokyo University of Science, Japan, 8Laboratori Nazionali di Frascati dell’INFN, Italy, 9University of Tokyo, Japan, 10Osaka Electro-Communication University, Japan, 11Tokyo Institute of Technology, Japan, 12RIKEN, Japan, 13High Energy Accelerator Research Organization (KEK), Japan, 14Technische Universitat Munchen, Germany, 15INAF-IFSI, Sezione di Torino, Italy, 16Kyoto Univ., Japan Hadron2009 @ Florida 1 December 2009

J-PARC E15 experiment L neutron 3He K- p p- Experimental search for K-pp bound states using in-flight (K-, n) reactions K-pp cluster neutron K- 3He Formation Missing mass Spectroscopy via neutron Decay L p p- Mode to decay charged particles We can observe both the “Formation” and “Decay” of K-pp bound state Invariant mass reconstruction Hadron2009 @ Florida 1 December 2009

Experimental Setup J-PARC K1.8BR Neutron 1.0 GeV/c K- TOF length 15m Neutron counter Beam sweep magnet Cylindrical Detector System Neutron 1.0 GeV/c K- TOF length 15m Beamline Spectrometer Hadron2009 @ Florida 1 December 2009

Cylindrical Detector System acceptance ~ 2.2p [sr] Hadron2009 @ Florida 1 December 2009

Solenoid magnet Performance field strength : 0.5 T (max : 0.7 T) aperture : 1.2 m length : 1.2 m Solenoid magnet has been already installed. At the end of March 2010, the excitation test will be done! Hadron2009 @ Florida 1 December 2009

Cylindrical Detector Hodoscope (CDH) used for trigger and PID Plastic scintillator Size : 99x30x700mm3 (WxTxL) Configuration : 36 modules PMT : fine mesh type (H8409) cosmic ray test sint ~ 70 psec All the units are ready and installed ! sint = 71.1 +/- 2.9 ps Hadron2009 @ Florida 1 December 2009

Cylindrical Drift Chamber (CDC) Size Inner diameter : 300 mm Outer diameter : 1060 mm Length : 950 mm Cell hexagonal (Drift length~9mm) Layer 15 layers (7 super layers) AA’A UU’ VV’ AA’ UU’ VV’ AA’ Read out : 1816 ch Gas : Ar-C2H6 (50:50) Efficiency : >99% for all layers (using 90Sr) Efficiency curve Using 90Sr

CDC test with cosmic ray Cosmic-ray test of CDC was done at J-PARC By comparing with a simulation, Intrinsic resolution ~ 200 mm. Residual Intrinsic resolution cosmic ray s=206 mm Hadron2009 @ Florida 1 December 2009

Expected mass spectra of K0s Monte Carlo Simulation (Geant4) K- p -> K0s n (PK=1GeV/c) K0s->p-p+ CDC resolution : 200 mm Field strength : 0.5 T p- K0s vertex p+ K0s Expected mass resolution s ~ 6.7 MeV/c2 Hadron2009 @ Florida 1 December 2009

Expected mass spectra of K-pp (L) K-pp -> L p L -> pp- Generate Lp isotropically assuming the two decay B.E. : 100 MeV Width : 0 MeV Expected mass resolution s~ 3.0 MeV/c2 for Lambda s ~ 13 MeV/c2 for K-pp p K-pp vertex p p- L vertex K-pp Lambda Hadron2009 @ Florida 1 December 2009

Liquid 3He target Cooling test with 200L 3He gas Calculation Development and test of Liquid 3He target system was already completed!! Temperature in the Target Cell 1.3 K Pressure in the Target Cell 33 hPa Liq. 4He Consumption 45 L/day Heat Load to the 1K Parts 0.19 W Hadron2009 @ Florida 1 December 2009

Beamline spectrometer In Feb. 2009, K1.8BR beamline tuning started with 1.1 GeV/c beam success in p/K/p separation using TOF method　( flight length = 7.7m ) In this autumn, 0.75 GeV/c beam tuning started. (for E17 exp.) Hadron2009 @ Florida 1 December 2009

Neutron counter rearrange E549 neutron counter support frame for E15 20 x 5 x 150 cm3 Plastic Scintillator Configuration : 16 (wide) x 7 (depth) Surface area : 3.2m x 1.5m missing mass resolution for K-pp s = 9.2 MeV/c2 (Pn=1.3 GeV/c, sTOF=150 ps) Hadron2009 @ Florida 1 December 2009

Thank you for your attention! Summary and outlook J-PARC E15 experiment search for a K-pp bound state using in-flight (K-, n) reactions measure the missing mass and invariant mass of K-pp states simultaneously K1.8BR beamline tuning already started. Other detector components will be ready soon. We will start to take data in 2011! Thank you for your attention! Hadron2009 @ Florida 1 December 2009

Back up Hadron2009 @ Florida 1 December 2009

Momentum resolution Transverse momentum resolution was estimated by Geant4 simulation Theoretical calculation is found in R.Gluckstern, NIM 24 (1963) 381. Hadron2009 @ Florida 1 December 2009

Vertex resolution sx ~5.4mm sy ~4.9mm sz ~4.3mm K0s vtx sx ~3.2mm Lambda vtx K-pp vtx with beam and p from K-pp sx ~ 0.92mm sy ~0.89mm sz ~5.6mm Hadron2009 @ Florida 1 December 2009

Simulation(1) p+ p- K0s Hadron2009 @ Florida 1 December 2009

Simulation(2) p from Kpp p from L p from L L from Kpp Hadron2009 @ Florida 1 December 2009

To improve z-resolution, Z-TPC is newly constructing Z-Vetex TPC (Z-TPC) gas:P10 (150V/cm) expected resolution (w/o B-field) however, rf-resolution is limited by pad size, e.g., 20.0/sqrt(12) = 5.8mm To improve z-resolution, Z-TPC is newly constructing sz(Lpp-): 7mm  2mm w/o Z-TPC w/ ~500mm ~300mm f280mm f170mm readout-pad pad size:20x4mm # of pad:4x4x9=144 field strip double sided flexible print circuit board 8mm strip 10mm pitch

J-PARC P28 experiment (semi-)inclusive measurement exclusive measurement X± K- 3He p （undetected) 3He K- p (n; undetected) Λ (search for K-pn bound state)

proton detector system [new] TOF start/stop counters - momentum measurement Drift chambers - scattering angle measurement - consistency check Glass Cherenkov - particle identification (K- / p) [new] TOF stop counter [extended] [existing in E15 setup]

Hodoscope Counter (CDH) CDH is used for the charged trigger and particle identification. expected pID using ToF measurements Feb. 2009 Plastic Scintillator : 99x30x700 mm3 （WＸTＸL）Configuration : 36 modules PMT: Hamamatsu H8409 (fine mesh) x 72 sint = 76psec CDH system has been mounted inside the Solenoid Magnet

Expected Spectrometer Performance Calculated using Geant4 momentum resolution for p, K, p we can distinguish the two non-mesonic decay modes for K-pp K-pp  Lp  pp-p K-pp  S0p  gLp  gpp-p S0 channel L channel GK-pp= 60 MeV invariant mass resolution for K-pp and L Invariant mass of Lp (MeV) mass resolution K-ppLp Lpp- w/o chamber-resolution 5.8 MeV/c2 1.6MeV/c2 w/ chamber-resolution 18.7MeV/c2 2.5MeV/c2