Introduction Contents Kaonic nuclei Status of Kaonic nuclei

• Introduction Contents • Kaonic nuclei • Status of Kaonic nuclei study • J-PARC E 15 experiment • Set up o Beamline o CDS o Neutron Counter • Analysis status • Summary 2

3 Kaonic nuclei • Bound state of anti-kaon and nuclei with strong interaction • High density matter? ? DISTO FINUDA B = 115± 6± 4 Me. V G = 67± 14± 3 Me. V • • • FINUDA exp. (DAFNE) 6 Li, 7 Li, 12 C target, stop K− reaction Lp　invariant mass B = 105± 2± 5 Me. V G = 118± 8± 10 Me. V • • • DISTO exp. p+p →X +K+, X →L + p reaction missing-mass &　invariant mass And LEPS/Spring-8（ d(g, Kp) <=previous talk by Tokiyasu-san J -PARC　E 27 exp（ d(π+, K+) <=previous talk by Ichikawa-san Kaonic nuclei exist or not? binding energy and width? ⇒result with other reaction is important ! 3

Theoretical calc. Of KNN(K pp) Binding energy[Me. V] Width[Me. V] N. Barnea, A. Gal, E. Z. Liverts(2012) 16 41 A. Dote, T. Hyodo, W. Weise(2008, 2009) 17 -23 40 -70 Y. Ikeda, H. Kamano, T. Sato(2010) 9 -16 34 -46 Binding energy[Me. V] width[Me. V] T. Yamazaki, Y. Akaishi(2002) 48 61 N. V. Shevchenko, A. Gal, J. Mares(2007) 50 -70 90 -110 Y. Ikeda, T. Sato (2007, 2009) 60 -95 45 -80 S. Wycech, A. M. Green (2009) 40 -80 40 -85 Potential is deep or shallow? ? 4

J-PARC E 15 Experiment 5 in-flight (K-, n) reaction on 3 He target 3 He K 1. 0 Ge. V/c Formation Mode to decay charged particles L pp p KNN cluster Decay Neutron ss a m y g n p i s o s c i M ctros n o r e t p u S e n a vi We are able to observe both ss “Formation” & “Decay” a m n t n io of KNN bound state ia t r c a Inv onstru 5 rec

J-PARC K 1. 8 BR beam line[Jun. 2012] beam dump beam sweeping magnet neutron counter & TOFstop/proton counter CDS 3 He-target 3 He(K-, N) reaction beam line spectrometer 6

Formation spectra : in-flight 3 He(K-, n) K- + 3 He “K-pp” + n @ PK=1 Ge. V/c, q=0º quasi-free V 0 = -292 W 0 = -107 Me. V (YA YA potential) potential bound K- conversion Quasi-free peak ~1. 2 Ge. V/c Kpp peak >1. 22 Ge. V/c K- escape One of the examples T. Koike and T. Harada. , PLB 652 (2007) 262 Easy to observe If ds/d. W >1. 0 mb/sr (This example ds/d. W ~3. 0 mb/sr. ) 7

Physics Data amount Beam intensity Duration [hour] K on target Mar 2013 14. 5 k. W 30 0. 9 x 109 May 2013 24 k. W 88 4. 0 x 109 We accumulated physics data =>total ~5 x 109 Kaon on target Reaction in accumulated data • 3 He(K-, n) • 3 He(K-, p) • 3 He(K-, d) => KNN search, multi-nucleon absorption, hyperon production etc. 8

Detector performance & preliminary result 9

Beamline spectrometers • BHD & T 0(Beam trigger) • Plastic scintillator • PID for beam • Time resolution TOF(BHD-T 0)~160 ps • AC(Kaon ID at trigger level) • Aerogel Cherenkov (index=1. 05) • P ID eff. =97%(Vth=5. p. e. ) • D 5 magnet & BLC (Beam spectrometer) • Dipole Mag. & wire chamber • Momentum resl=0. 2% p K P TOF (BHD-T 0) 1. 0 Ge. V/c beam 10

Pspectrometer [Me. V/c] Beam Spectrometer σspectrometer~ 0. 2% @1 Ge. V/c Pspectrometer - PTOF[Me. V/c] We achieved Enough performance

Cylindrical Detector System • Counters & chamber around 3 He target 12 CDC n n Cell　Drift length~9 mm Layer　15 layers Read out : 1816 ch Gas : Ar-C 2 H 6 (50: 50) Hodoscope And Solenoid • Size : 99 x 30 x 700 mm 3 (W x T x L) • Configuration : 36 modules • PMT : fine-mesh type (H 8409) • Solenoid Mag. Max 0. 7 T Expected mass resolution : - s ~ 3. 5 Me. V/c 2 for L - s ~ 10 Me. V/c 2 for K-pp ( scdc = 200 mm / Field : 0. 7 T) 12

PID for CDS Kaon P vs cosq ”N”(K-, K-)N • • • PID for CDS (vertex in target volume) Cos q is angle between K- 　beam and scattered particle Good consistency of cosq - momentum plot (K- p) and elastic scattering curve 13

Invariant mass of + p p & proton p • We achieved design performance o o K 0 s , L’s center of peak & width is consistent with simulation result Kpp resl ~10 Me. V (from simulation) d. Pt/Pt @1 Ge. V ~8% Vertex resl. xy ~2 mm z ~5 mm 14

Forward TOF counters 15 Neutron counter(NC) • 20 x 5 x 150 cm 3 Plastic Scintillator • Configuration : Neutron counter 16 (wide) x 7 (depth) • Surface area : 3. 2 m x 1. 5 m • missing mass resolution for K-pp s = 9. 2 Me. V/c 2 (Pn=1. 3 Ge. V/c, s. TOF=150 ps) Proton counter Pro Caved Beam dump ton cou n To suppress background of NC from beam ter • 10 x 3 x 150 cm 3 Plastic Scintillator • Configuration : 27+34 layer • missing mass resolution for KNN s = 6. 8 Me. V/c 2 (Pp=1. 3 Ge. V/c, s. TOF=100 ps) 15

Neutron & Proton Counter Neutron Counter 1/b Proton Counter TOF • Neutron counter =>separated g & neutron • Proton counter => separated p & d 16

Forward neutron spectrum r e V i l e r P y y r a n i m Enhanced ”p”(K-, n)K 0 s reaction 17

Summary • Kaonic nuclei o Bound state of anti-kaon and nuclei with strong interaction o J-ARC E 15 Experiment o Search for KNN with in-flight 3 He(K-, N) reaction o We achieved design performance in every system • Beam line =>momentum resl. 0. 2% • from mass resolution of K 0 s , L => Kpp invariant mass resl. =10 Me. V/c 2(with sim) =>Missing mass resolution (Kpp) =10 Me. V/c 2 • We accumulated physics data (Mar & May 2013) o total ~5 x 109 Kaon on target o Detail Analysis is under way 18

19 J-PARC E 15 Collaboration 19