Research
Experiments and research plans at the J-PARC Hadron Experimental Facility, including K1.8, K1.8BR, K1.1, KL, High-p, COMET and facility-extension projects.
Identifiers, beamlines and categories follow the public PAC41 approval summary (April 3, 2026 version), checked on September 18, 2026.
J-PARC PAC / Proposal archive / Hadron Facility Extension
Approved experiments (preparation, running and analysis)
[E03] Measurement of X rays from Ξ- Atom
K1.8 — Stage 2[E08] Pion double-charge exchange on oxygen
K1.8 — Stage 1[E10] Neutron-rich Lambda hypernuclei
K1.8 — Stage 2[E14] Proposal for KL→π0νν Experiment at J-PARC
KL — Stage 2[E16] Nuclear-medium effects on vector-meson spectra
High-p — Stage 2 (first 300 hours)[E18] Weak decays of carbon-12 Lambda hypernuclei
K1.8 — Stage 2[E21] COMET: muon-to-electron conversion
COMET — Stage 2[E22] Lambda-nucleon weak interactions in A=4 hypernuclei
K1.8 — Stage 1[E26] Omega mesons bound in nuclei and mass modification
K1.8 — Stage 1[E29] Phi-meson nuclear bound states
K1.1 — Stage 1[E45] Baryon resonances through three-body reactions
K1.8 / K1.8BR — Stage 2[E50] Charmed-baryon spectroscopy
High-p — Stage 1[E57] Kaonic-deuterium X-ray spectroscopy
K1.8BR — Stage 1[E63] Hypernuclear gamma spectroscopy: second stage of E13
K1.1 / K1.8 — Stage 2[E70] Xi hypernuclei with S-2S: successor to E05
K1.8 — Stage 2[E72] Narrow Lambda resonance search with hypTPC
K1.8BR — Stage 2[E75] Double-Lambda hypernuclei through decay-pion spectroscopy
K1.8 — Stage 2[E79] Isospin-3 dibaryon search
High-p — Stage 1[E80] Light kaonic nuclei
K1.8BR — Stage 2[E86] Polarized Lambda-proton scattering
K1.1 — Stage 1[E88] Phi mesons in nuclei through charged-kaon pairs
High-p — Stage 1[E89] Properties of the antikaon-two-nucleon system
K1.8BR — Stage 1[E90] Precision study of the Sigma-N cusp
K1.8 — Stage 2[E94] Lambda-hypernuclear spectroscopy with S-2S
K1.8 — Stage 2[E95] Phi production with a pion beam
High-p — Stage 1[E97] Excited Xi baryons
High-p — Stage 1[E104] Near-threshold phi-pair production in antiproton-proton reactions
K1.8BR — Stage 2[E107] KOTO II
KL2 (extension) — Stage 1
Proposals awaiting further review
These proposals are listed separately from approved experiments.
[P84] High-resolution Lambda spectroscopy at HIHR
HIHR (extension) — Deferred[P85] Omega-baryon spectroscopy at K10
K10 / T2 (extension) — Deferred[P87] Dielectrons from heavy-ion collisions with upgraded E16
High-p / heavy ions — Deferred[P91] Nucleon charm content through J/psi measurements
High-p — Deferred[P92] E80 Phase I: antikaon-three-nucleon states via Lambda-d decay
K1.8BR — Deferred[P93] Secondary-beam performance studies
High-p — Deferred[P102] The 1680-MeV structure in pion-induced eta production
K1.8 — Deferred[P111] Near-threshold J/psi production with pions
High-p — Deferred[P115] Antideuteron-carbon interactions
K1.8 — Deferred
Experiments with completed beam runs (including analysis)
[E05] Spectroscopic Study of Ξ-Hypernucleus, 12ΞBe, via the 12C(K-,K+) Reaction
K1.8 — Finished[E07] Systematic Study of Double Strangeness System with an Emulsion-counter Hybrid Method
K1.8 — Finished[E13] Gamma-ray spectroscopy of light hypernuclei
K1.8 — Finished[E15] A Search for deeply-bound kaonic nuclear states by in-flight 3He(K-,n) reaction
K1.8BR — Finished[E19] High-resolution Search for Pentaquark in π-p→K-X Reactions
K1.8 — Finished[E27] Antikaon-proton-proton bound-state search
K1.8 — Finished[E31] Subthreshold hyperon resonances in deuterium reactions
K1.8BR — Finished[E36] Kaon leptonic-decay ratios and sterile-neutrino searches
K1.1BR — Finished[E40] Sigma-proton scattering
K1.8 — Finished[E42] H-dibaryon search with hypTPC
K1.8 — Finished[E62] Kaonic-atom spectroscopy using TES
K1.8BR — Finished[E73] Lifetimes of light hydrogen hypernuclei
K1.8BR — Finished[E96] Xi-carbon X-rays with an active target
K1.8 — Finished
Beam and detector test experiments
[P109] Low-momentum kaon beam optimization
K1.8BR — Test Experiment[T112] Secondary-beam characterization: second stage of P93
High-p — Test Experiment[T113] Multi-GeV muon radiography
High-p — Test Experiment
Selected recently completed test experiments
[T98] Antimatter reactions in a liquid-argon TPC
K1.8BR — Finished[T103] Streaming data-acquisition tests
K1.8BR — Finished[T105] Test-beam-line development
K1.8BR — Finished[T106] Secondary-beam tests: first stage of P93
High-p — Finished[T108] Antideuteron beam optimization
K1.8 — Finished[T110] Trigger-counter tests for E72
K1.8BR — Finished
Earlier entries and related experiments
PAC39 approval summary: these earlier entries are not separate entries in the PAC41 summary.
[E06] Measurement of T-violation Transverse Muon Polarization in K+→π0μ+ν Decays
K1.1BR — PAC39: E36 as the first step[E17] Precision spectroscopy of Kaonic 3He 3d→2p X-rays
K1.8BR — PAC39: registered as E62 with an updated proposal