Hadron Physics at J-PARC

Hadron Physics at J-PARC Shin’ya Sawada 澤田　真也 KEK (High Energy Accelerator Research Organization, Japan) AFTER@LHC, ECT*, Feb. 5. 2013

Contents • Overview of J-PARCand Hadron Experimental Facility (Hadron Hall) • Physics with Low Momentum Secondary Beams • Physics with High-Momentum Beams • Extension • Summary

Materials & Life Sciences at 3 GeV Nuclear & Particle Physics at 50 GeV R&D toward Transmutation at 0.6 GeV Goals at J-PARC Need to have high-power proton beams MW-class proton accelerator (current frontier is about 0.1 MW)

Location of J-PARC at Tokai 295 km JAEA Tokai 1 hour J-PARC Tsukuba

Linac 3 GeV Synchrotron Neutrino Beams(to Kamioka) Materials and Life Experimental Facility 50 GeV Synchrotron JFY2007 Beams Hadron Exp. Facility JFY2008 Beams JFY2009 Beams J-PARC Facility (KEK/JAEA） South to North Experimental Areas Bird’s eye photo in January of 2008

Hadron Experimental Facility (Current Layout) Ｔ１ Target (30/50% Loss) 50GeVSynchrotron Extension SM1 (2% Loss) T0 0.1% Loss) 50GeV Tunnel Test BL Hi-P BL Switchyard Hadron Hall Beam Dump 6

Slide By H.Tamura X hypernuclei LL hypernuclei X-atomic X-rays L hypernuclear grays Neutron-rich Lhypern. PentaquarkQ+ search K-pp bound state n Hyp. weak decay(A=4) Hyp. weak decay(A=12) p Double charge exch. w mesonic nuclei Sp scattering L p K- p p experiments in Hadron Hall Beam Dump K1.8 Hadron mass in nuclei Nucleon quark structure K0L rare decays KL K1.8BR K-pp bound states K- atomic X rays h mesonic nuclei High momentum line K1.1 • Production • target (T1) Not constructed yet Fmesonic nuclei L hypernuclear g rays S-nuclear systems YN scatering Q+ hypernuclei K1.1BR T violation in K+ decay Universality in K+ decay Q+ study by K+n scattering 30~50 GeV primary beam m-e conversion search 7 Approved (stage-2)/ (stage-1) /proposed,LOI

Season of Fruits at Hadron Hall Comes! Beam Intensity is being upgraded.

Physics with Low Momentum Secondary Beams • So far there are only low-momentum beam lines. • Strangeness nuclear physics • With (pi, K), (K, pi), and (K-, K+) reactions • Other hadron physics • Many strangeness related, but a few non-strange. • Low Momentum Secondary Beams • Pions and Kaons <2 GeV/c at K1.8 beam line • Momentum was selected so that the production cross section of the Xsi baryon is at the maximum. • Major goal is S=-2 hypernuclei (Xsi nuclei and double-Lambda nuclei). • Used also for (pi, K) reaction for single hypernuclei. • Pions and Kaons <1.1GeV/c at K1.8BR and K1.1 beam line • Single Lambda hypernuclei • Gamma ray spectroscopy • Search for K-pp bound states

Nu ~ Nd ~ Ns Strangeness in neutron stars ( r > 3 - 4 r0 ) Strange hadronic matter (A → ∞) Strangeness LL, X Hypernuclei Z L, S Hypernuclei -2 N -1 0 Three Dimensional Nuclear Chart “Stable” Higher density

Single strangeness experiments • E19 (published): Pentaquark search • E10 (took data): Neutron-rich hypernuclei with double-charge exchange • E13 (coming soon): Gamma ray spectroscopy of hypernuclei • E15 (took some data): Search for K-+p+p bound state • … (many waiting)

E19: Pentaquark Search • search for Θ+in p(π– , K–) • target : liquid H2, 0.86g/cm2 • at K1.8 beamline + SKS • beam momentum : • pπ=(1.87,1.92,2.00GeV/c) • 4.8 x 1011p on target for each pπ • beam intensity : 107/spill(2sec.) • beam time : 160 hours Yield : 104 events for each momentum Sensitivity : 75nb/sr  confirm the existence of Θ+ E19 took the first physics data with p=1.92 GeV/c in Oct/Nov, 2010, and p=2.0 GeV/c in Feb, 2012. • SKS: ideal for Θ+ detection • large acceptance : 0.1sr • ΔM =2.5MeV FWHM

E19: Pentaquark Search

Study on 6ΛH hypernucleus by the (π-,K+) reaction at J-PARC Hitoshi Sugimura Kyoto University/JAEA For J-PARC E10 Collaboration International Nuclear Physics Conference 2013

N>>Z (I=3/2 or 2) J-PARC E10 J-PARC E10 experiment N~Z (I=0 or 1/2) L-hypernuclei Non Charge-Exchange (NCX) ordinary nuclei hyperfragments by emulsions exp. π-+p+p->K++n+Λ Double Charge-Exchange (DCX) International Nuclear Physics Conference 2013

6ΛHproduction by FINUDA M. Agnello et al., FINUDA Collaboration, PRL 108 (2012) 042501 • 6Li(stopped K-,π+) reaction • Measured formation and weak decay in coincidence • cut on T(π+)+T(π-) • 3 events of candidates International Nuclear Physics Conference 2013 17

Experimental Setup LC SDC4 SDC3 • K1.8 Beamline • -1.2GeV/c π- Beam • Δp/p ~3.3x10-4 • Momentum is measured by the • Transfer Matrix • BFT(x)-BC3,4(x,y,x’,y’) • SKS Spectrometer • Central Momentum 0.9GeV/c • Δp/p~1.0x10-3 • Momentum is calculated or estimated • Runge-Kutta method • SFT,SDC2(x,y,x’,y’)-SDC3,4(x,y,x’,y’) • Scattered Kaon identified TOFxLCxAC in • online trigger K+ AC SKS SDC2 TOF SFT BH2 SSD BC4 BC3 GC π- BFT J-PARC K1.8 Beam Line BH1 International Nuclear Physics Conference 2013

Calibration Runs ΔM:2.6MeV/c2 (FWHM) • Results of analysis • +1.20GeV/c 12C(π+,K+)12ΛC • - 1.37GeV/c p(π-,K+)Σ- • +1.37GeV/c p(π+,K+)Σ+ p(π+,K+)Σ+ Preliminary Measure: 1188.41MeV PDG: 1189.37MeV Yield : ~2000 events 12C(π+,K+)12ΛC ΔBΛ:2.8MeV/c2 (FWHM) ΔM:2.5MeV/c2 (FWHM) p(π-,K+)Σ- Ex(pΛ) g.s.(sΛ) Preliminary Preliminary Measure:1200.39MeV PDG: 1197.45MeV Yield : ~6000events Σ-QF Λ-QF Yield (g.s): ~600events International Nuclear Physics Conference 2013

Missing Mass Counts/MeV Preliminary Preliminary Λ- continuum Σ- continuum Missing Mass[GeV/c2] Missing Mass[GeV/c2] • Could measure not only Λ-continuum region but also Σ-continuum region. • Back ground level is enough lower than Λ-continuum. • According to simple extrapolation of Λ-continuum, we observed some excess at the low mass region. But it is too early to conclude at this moment. • Production cross section of6ΛH is smaller than we expected (10nb/sr). International Nuclear Physics Conference 2013

E13 E13 E13: Hypernuclear g Spectroscopy High-precision (DE～3 keV FWHM) spectroscopy with Ge detectors 1. YN, YY interactions Unified picture of B-B interactions Understand short-range nuclear forces Understandhigh density nuclear matter (n-star) Level energies ->LN spin-dependent forces, Charge symmetry breaking, SN-LN force,… 2.Impurity effects in nuclear structure Changes of size/shape, symmetry, cluster/shell structure,.. B(E2), E(2+) -> shrinking effect, deformation change 3. Medium effects of baryons probed by hyperons B(M1) -> mLin nucleus

#1 A X- #3 #2 10 5 0 #2 #1 5 10 B (mm) Ξ- Double-strangeness hypernuclei soon • With the improvement of the proton beam intensity, double-strangess experiments with (K-, K+) become possible soon. • E07: Systematic Study of Double Strangeness System with an Emulsion-Counter Hybrid Method PS-E373 PS-E176 in ~700 Ξstops in ~80 Ξstops NAGARA event +6 cand. for L6LHe ΔBLL =1.01±0.20 MeV Double-Hypernucleus with sequential decay surely exists. p - S-

Double-strangeness hypernuclei soon • E07: Systematic Study of Double Strangeness System with an Emulsion-Counter Hybrid Method • Physics 1) S=-2 nuclear chartby~102LLZvia104 X--stopping events. =>DBLLof several nuclideswill providedefinitive informationon LL interaction and structure of S=-2 nuclei. 2) H-dibaryon state in S=-2 system ? =>measure A-dependence ofDBLL & S-decay mode ofLLZ. 3) X--nucleus potential =>detection oftwin hypernuclei =>First measurementof X-ray ofX-atom

Physics with High-Momentum Beams • “High-momentum beam line” (+ COMET beam line) has been funded! • High-momentum primary proton beam (30GeV) • Meson mass modification inside nuclei • Dilepton measurement for nucleon and baryon structure • High-momentum meson (pion) beam (~<15 GeV/c) • Pion-induced Drell-Yan? • Baryon spectroscopy with pion beams.

High-p and COMET • New primary Proton Beam Line= High-momentum BL + COMET BL • High-momentum Beam Line • Primary protons (~1010 – 1012pps) • E16 (phi meson) is considered to be the first experiment. • Unseparated secondary particles (pi, …) • High-resolution secondary beam by adding several quadrupole and sextupole magnets. • COMET • Search for m to e conversion • 8 GeV, 50 kW protons • Branch from the high-momentum BL • Annex building will be built at the south side.

New Primary Proton Beam Line Separation High-p COMET

Mass modification of vector meson QCD Vaccum Spontaneous Breaking of Chiral Symmetry Restoration Hot/Dense Matter Vector meson mass at normal nuclear density m*/m=1-kr/r0 (Hatsuda&Lee PRC46(92)R34) r/w : Dm = 130 MeV at r0 f : Dm = 20~40 MeV at r0

Results of a previous experiment (KEK-PS E325): Invariant mass spectra of f e+e- 1.75<bg (Fast) bg<1.25 (Slow) 1.25<bg<1.75 Small Nucleus Large Nucleus PRL 98(2007)042501

J-PARC E16: Electron pair spectrometer to explore the chiral symmetry in QCD primary proton beam at high momentum beam line + large acceptanceelectron spectrometer 107 interaction (10 X E325) 1010 protons/spill with 0.1% interaction length target  GEM Tracker eID : Gas Cherenkov + Lead Glass Large Acceptance (5 X E325) velocitydependence nuclear number dependence (p  Pb) centrality dependence systematic study of mass modification

Possible hadron exps at high-momentum BL • Sea quark structure through Drell-Yan measurement • Currently the E906/SeaQuest is running at Fermilab with 120-GeV protons to see d-bar/u-bar asymmetry. • Larger x possible with 50-GeV protons at J-PARC. • J-PARC is currently operated with 30-GeV and there are no demands of 50-GeV operation from other experiments, which needs modification of a part of the accelerator components. • There could be other possibilities of physics with dimuon measurement such as, • J/Psi measurements to see the nucleon sea, • dimuons from pion/kaon induced reactions to see meson-like substructure of a nucleon. • Spin related quantities • Polarized beam relatively far future. • Polarized target would be available in the near future. • Measurement such as Bohr-Mulders can be carried out even with unpol. Drell-Yan measurements.

J/Psi: gg or q-qbar? Lingyan Zhu et al., PRL, 100 (2008) 062301 Gluon distributions in proton and neutron are very similar at 800 GeV. At much lower energies, J/Psi might be produced by q-qbar annihilation.  Azimuthal angle dependence. If J/Psi production is q-qbar annihilation, J/Psi becomes a tool to investigate quark structure of nucleon at lower energies.

Unseparated Secondary Beam Intensity beam loss limit @ SM1:15kW (limited by the thickness of the tunnel wall) with 15kW beam loss [GeV/c] extraction angle：5° smaller angle possibility being investigated

Exclusive Pion-Induced Drell-Yan Process Bernard Pire , IWHS2011 • DA characterizes the minimal valence Fock state of hadrons. • DA of pion are also explored by pion-photon transition form factor in Belle and Barbar Exps. • TDA characterizes the next-to-minimal valence Fock state of hadrons. • TDA of pion-nucleon is related to the pion cloud of nucleons. 35

Accident • Radiation accident occurred at Hadron Hall on May 23rd. • Due to a malfunction of the beam extraction system of the 50 GeV synchrotron, a proton beam was delivered to the gold target of the Hadron facility within a very short time (30GeV, 2E13protons in ~5ms). As a result, the gold target is considered to have momentarily reached an extremely high temperature and a part of the target was damaged. Radioactive material then leaked into the hadron experimental hall and some workers were externally and/or internally exposed to radiation. • Operation of ventilation fans of the hall resulted in leak of radioactive material out of the radiation controlled area of the Hadron Experimental Facility. The data logs of radiation dose rates at monitoring posts at the border of the J-PARC site showed no signatures. However, at three monitoring posts and stations of a neighboring JAEA facility, momentary increases of the radiation dose rate were observed. It is assessed that the released radioactive material was diluted and attenuated as it dispersed in a narrow strip towards the west. The maximum integrated radiation dose has been estimated even at the site boundary closest to the Hadron Experimental Facility was 0.29 µSv (preliminary). • All the J-PARC facilities have been shutdown since the accident. A full investigation of the cause of the accident is now underway along with the complete review of safety practices and emergency procedures at all J-PARC facilities. Our first priority is to restore public trust in the facility by developing and implementing measures to prevent the reoccurrence of an accident and to provide a safe experimental environment for users and workers.

Summary • Physics experiments have started at the Hadron Hall of J-PARC, and the first physics paper is being published from the E19 experiment. So far experiments with lower momentum pions/kaons are being carried out. • The funding for the high-momentum beam line with COMET has been approved by the government. The construction is expected to start soon. Mass shift of phi meson would be the first experiment, and other experiments are being discussed. • J-PARC is now very busy to respond to the accident. We don’t have any forecast on the schedule, but we make our best.

Hadron Physics at J-PARC